title:
Wave propagation in relaxed micromorphic continua: modelling
  metamaterials with frequency band-gaps

abstract:
  In this paper the relaxed micromorphic model proposed in [Patrizio Neff,
Ionel-Dumitrel Ghiba, Angela Madeo, Luca Placidi, Giuseppe Rosi. A unifying
perspective: the relaxed linear micromorphic continuum, submitted, 2013,
arXiv:1308.3219; and Ionel-Dumitrel Ghiba, Patrizio Neff, Angela Madeo, Luca
Placidi, Giuseppe Rosi. The relaxed linear micromorphic continuum: existence,
uniqueness and continuous dependence in dynamics, submitted, 2013,
arXiv:1308.3762] has been used to study wave propagation in unbounded continua
with microstructure. By studying dispersion relations for the considered
relaxed medium, we are able to disclose precise frequency ranges (band-gaps)
for which propagation of waves cannot occur. These dispersion relations are
strongly nonlinear so giving rise to a macroscopic dispersive behavior of the
considered medium. We prove that the presence of band-gaps is related to a
unique elastic coefficient, the so-called Cosserat couple modulus $\mu_{c}$,
which is also responsible for the loss of symmetry of the Cauchy force stress
tensor. This parameter can be seen as the trigger of a bifurcation phenomenon
since the fact of slightly changing its value around a given threshold
drastically changes the observed response of the material with respect to wave
propagation. We finally show that band-gaps cannot be accounted for by
classical micromorphic models as well as by Cosserat and second gradient ones.
The potential fields of application of the proposed relaxed model are manifold,
above all for what concerns the conception of new engineering materials to be
used for vibration control and stealth technology.


title: Luminogenesis from Inflationary Dark Matter

abstract:
  A cosmological model is introduced in which dark matter plays a dominant role
throughout the history of the universe, and is the only matter present for
temperatures $T \gtrsim T_{15} \sim 10^9$ GeV. The gauge group is $SU(3) \times
SU(6)_{DM} \times U(1)_Y$ and unifies in such a way that luminous matter is
generated at $T \sim T_{15}$ with the correct amount and eventual asymmetry.
Construction of more highly sensitive direct detectors of dark matter (e.g.
XENON1T) is encouraged. We offer a new explanation of why grand unification
theories involving only luminous matter may be fatally flawed.


title:
Fragmentation and Limits to Dynamical Scaling in Viscous Coarsening: An
  Interrupted in situ X-Ray Tomographic Study

abstract:
  X-Ray microtomography was used to follow the coarsening of the structure of a
ternary silicate glass experiencing phase separation in the liquid state. The
volumes, surfaces, mean and Gaussian curvatures of the domains of minority
phase were measured after reconstruction of the 3D images and segmentation. A
linear growth law of the characteristic length scale $\ell \sim t$ was
observed. A detailed morphological study was performed. While dynamical scaling
holds for most of the geometrical observables under study, a progressive
departure from scaling invariance of the distributions of local curvatures was
evidenced. The latter results from a gradual fragmentation of the structure in
the less viscous phase that also leads to a power-law size distribution of
isolated domains.


title: Hypercyclic abelian semigroups of affine maps on C^n

abstract:
  We give a characterization of hypercyclic abelian semigroup G of affine maps
on C^n. If G is finitely generated, this characterization is explicit. We prove
in particular that no abelian group generated by n affine maps on C^n has a
dense orbit.


title:
The distribution of values of short hybrid exponential sums on curves
  over finite fields

abstract:
  Let $p$ be a prime number, $X$ be an absolutely irreducible affine plane
curve over $\mathbb{F}_p$, and $g,f\in\mathbb{F}_p(x,y)$. We study the
distribution of the values of the hybrid exponential sums S_n on
$n\in\mathcal{I}$ for some short interval $\mathcal{I}$. We show that under
some natural conditions the limiting distribution of the projections of the sum
$S_n$, $n\in\mathcal{I}$ on any straight line through the origin is Gaussian as
$p$ tends to infinity.


title:
High-Throughput Screening of Perovskite Alloys for Piezoelectric
  Performance and Formability

abstract:
  We screen a large chemical space of perovskite alloys for systems with the
right properties to accommodate a morphotropic phase boundary (MPB) in their
composition-temperature phase diagram, a crucial feature for high piezoelectric
performance. We start from alloy end-points previously identified in a
high-throughput computational search. An interpolation scheme is used to
estimate the relative energies between different perovskite distortions for
alloy compositions with a minimum of computational effort. Suggested alloys are
further screened for thermodynamic stability. The screening identifies alloy
systems already known to host a MPB, and suggests a few new ones that may be
promising candidates for future experiments. Our method of investigation may be
extended to other perovskite systems, e.g., (oxy-)nitrides, and provides a
useful methodology for any application of high-throughput screening of
isovalent alloy systems.


title:
The Three-Dimensional Jump Conditions for the Stokes Equations with
  Discontinuous Viscosity, Singular Forces, and an Incompressible Interface

abstract:
  The three-dimensional jump conditions for the pressure and velocity fields,
up to the second normal derivative,across an incompressible/inextensible
interface in the Stokes regime are derived herein. The fluid viscosity is only
piecewise continuous in the domain while the embedded interface exerts singular
forces on the surround fluids. This gives rise to discontinuous solutions in
the pressure and velocity field. These jump conditions are required to develop
accurate numerical methods, such as the Immersed Interface Method, for the
solutions of the Stokes equations in such situations.


title:
Twisted-light-induced intersubband transitions in quantum wells at
  normal incidence

abstract:
  We examine theoretically the intersubband transitions induced by laser beams
of light with orbital angular momentum (twisted light) in semiconductor quantum
wells at normal incidence. These transitions become possible in the absence of
gratings thanks to the fact that collimated laser beams present a component of
the light's electric field in the propagation direction. We derive the matrix
elements of the light-matter interaction for a Bessel-type twisted-light beam
represented by its vector potential in the paraxial approximation. Then, we
consider the dynamics of photo-excited electrons making intersubband
transitions between the first and second subbands of a standard semiconductor
quantum well. Finally, we analyze the light-matter matrix elements in order to
evaluate which transitions are more favorable for given orbital angular
momentum of the light beam in the case of small semiconductor structures.


title: Benefits of Objective Collapse Models for Cosmology and Quantum Gravity

abstract:
  We display a number of advantages of objective collapse theories for the
resolution of long-standing problems in cosmology and quantum gravity. In
particular, we examine applications of objective reduction models to three
important issues: the origin of the seeds of cosmic structure, the problem of
time in quantum gravity and the information loss paradox; we show how reduction
models contain the necessary tools to provide solutions for these issues. We
wrap up with an adventurous proposal, which relates the spontaneous collapse
events of objective collapse models to microscopic virtual black holes.


title: SLAM, a Mathematica interface for SUSY spectrum generators

abstract:
  We present and publish a Mathematica package, which can be used to
automatically obtain any numerical MSSM input parameter from SUSY spectrum
generators, which follow the SLHA standard, like Spheno, Softsusy, Suseflav or
Suspect. The package enables a very comfortable way of numerical evaluations
within the MSSM using Mathematica. It implements easy to use predefined high
scale and low scale scenarios like mSUGRA or $m_h^{\rm max}$ and if needed
enables the user to directly specify the input required by the spectrum
generators. In addition it supports an automatic saving and loading of SUSY
spectra to and from a SQL data base, avoiding the rerun of a spectrum generator
for a known spectrum.


title: Throughput Maximization in the Speed-Scaling Setting

abstract:
  We are given a set of $n$ jobs and a single processor that can vary its speed
dynamically. Each job $J_j$ is characterized by its processing requirement
(work) $p_j$, its release date $r_j$ and its deadline $d_j$. We are also given
a budget of energy $E$ and we study the scheduling problem of maximizing the
throughput (i.e. the number of jobs which are completed on time). We propose a
dynamic programming algorithm that solves the preemptive case of the problem,
i.e. when the execution of the jobs may be interrupted and resumed later, in
pseudo-polynomial time. Our algorithm can be adapted for solving the weighted
version of the problem where every job is associated with a weight $w_j$ and
the objective is the maximization of the sum of the weights of the jobs that
are completed on time. Moreover, we provide a strongly polynomial time
algorithm to solve the non-preemptive unweighed case when the jobs have the
same processing requirements. For the weighted case, our algorithm can be
adapted for solving the non-preemptive version of the problem in
pseudo-polynomial time.


title:
Superconducting qubit as a probe of quantum fluctuations in a nonlinear
  resonator

abstract:
  In addition to their central role in quantum information processing, qubits
have proven to be useful tools in a range of other applications such as
enhanced quantum sensing and as spectrometers of quantum noise. Here we show
that a superconducting qubit strongly coupled to a nonlinear resonator can act
as a probe of quantum fluctuations of the intra-resonator field. Building on
previous work [M. Boissoneault et al. Phys. Rev. A 85, 022305 (2012)], we
derive an effective master equation for the qubit which takes into account
squeezing of the resonator field. We show how sidebands in the qubit excitation
spectrum that are predicted by this model can reveal information about
squeezing and quantum heating. The main results of this paper have already been
successfully compared to experimental data [F. R. Ong et al. Phys. Rev. Lett.
110, 047001 (2013)] and we present here the details of the derivations.


title:
Mean-field yrast spectrum of a two-component Bose gas in ring geometry:
  persistent currents at higher angular momentum

abstract:
  We use analytic soliton solutions of a two-component Bose gas in ring
geometry to analyze the mean-field yrast spectrum of the system. We find that
the spectrum exhibits a surprisingly rich structure as a result of the
interplay of interparticle interactions and population imbalance. We discuss
the implication of these results in regard to the possibility of persistent
currents at higher angular momenta.


title:
$B_{s,d}^0 \to \mu\bar{\mu}$ and $B\to X_s\gamma$ in the R-parity
  violating MSSM

abstract:
  The recent measurements of $B_s^0 \to \mu\bar{\mu}$ decay candidates at the
LHC consistent with the standard model rate, and the improving upper limits for
$B_d^0 \to \mu\bar{\mu}$ can strongly constrain beyond the standard model
physics. For example, in supersymmetric models with broken R-parity (RpV), they
restrict the size of the new couplings. We use the combination of the public
software packages SARAH and SPheno to derive new bounds on several combinations
of R-parity violating couplings. We improve existing limits for the couplings
which open tree-level decay channels and state new limits for combinations
which induce loop contributions. This is the first study which performs a full
one-loop analysis of these observables in the context of R-parity violation. It
turns out that at one-loop despite the strong experimental limits only
combinations of R-parity violating couplings are constrained which include
third generation fermions. We compare our limits with those obtained via $B\to
X_s\gamma$ and discuss the differences.


title: Performance of simulated annealing in p-spin glasses

abstract:
  We perform careful numerical simulations of slow Monte-Carlo annealings in
the dense 3-body spin glass model and compare with the predictions from
different theories: thresholds states, isocomplexity, following state. We
conclude that while isocomplexity and following state both provide excellent
agreement the numerical data, the influence of threshold states -- that is
still the most commonly considered theory -- can be excluded from our data.


title: Covariance Matrix Estimation for the Cryo-EM Heterogeneity Problem

abstract:
  In cryo-electron microscopy (cryo-EM), a microscope generates a top view of a
sample of randomly-oriented copies of a molecule. The problem of single
particle reconstruction (SPR) from cryo-EM is to use the resulting set of noisy
2D projection images taken at unknown directions to reconstruct the 3D
structure of the molecule. In some situations, the molecule under examination
exhibits structural variability, which poses a fundamental challenge in SPR.
The heterogeneity problem is the task of mapping the space of conformational
states of a molecule. It has been previously suggested that the leading
eigenvectors of the covariance matrix of the 3D molecules can be used to solve
the heterogeneity problem. Estimating the covariance matrix is challenging,
since only projections of the molecules are observed, but not the molecules
themselves. In this paper, we formulate a general problem of covariance
estimation from noisy projections of samples. This problem has intimate
connections with matrix completion problems and high-dimensional principal
component analysis. We propose an estimator and prove its consistency. When
there are finitely many heterogeneity classes, the spectrum of the estimated
covariance matrix reveals the number of classes. The estimator can be found as
the solution to a certain linear system. In the cryo-EM case, the linear
operator to be inverted, which we term the projection covariance transform, is
an important object in covariance estimation for tomographic problems involving
structural variation. Inverting it involves applying a filter akin to the ramp
filter in tomography. We design a basis in which this linear operator is sparse
and thus can be tractably inverted despite its large size. We demonstrate via
numerical experiments on synthetic datasets the robustness of our algorithm to
high levels of noise.


title: Characterizing the Strong Maximum Principle

abstract:
  In this paper we characterize the degenerate elliptic equations F(D^2u)=0
whose viscosity subsolutions, (F(D^2u) \geq 0), satisfy the strong maximum
principle. We introduce an easily computed function f(t) for t > 0, determined
by F, and we show that the strong maximum principle holds depending on whether
the integral \int dy / f(y) near 0 is infinite or finite. This complements our
previous work characterizing when the (ordinary) maximum principle holds. Along
the way we characterize radial subsolutions.


title: Beam-beam Effects of 'Gear-changing' in Ring-Ring Colliders

abstract:
  In ring-ring colliders, the collision frequency determines the bunch
structures, e.g. the time between the bunches in both rings should be
identical. Because of relatively low relativistic speed of the hadron beam in
sub-TeV hadron-hadron- and electron-ions-colliders, scanning the hadron beam's
energy would require either a change in the circumference of one of the rings,
or a switching of the bunch (harmonic) number in a ring. The later would cause
so-called 'gear-changing', i.e. the change of the colliding bunches turn by
turn. In this article, we study the difficulties in beam dynamics in this
'gear-changing' scheme.


title: The CAPTAIN Detector and Physics Program

abstract:
  The Cryogenic Apparatus for Precision Tests of Argon Interactions with
Neutrino (CAP- TAIN) program is designed to make measurements of scientific
importance to long-baseline neutrino physics and physics topics that will be
explored by large underground detectors. The CAPTAIN detector is a liquid argon
TPC deployed in a portable and evacuable cryostat. Five tons of liquid argon
are instrumented with a 2,000 channel liquid argon TPC and a photon detection
system. Subsequent to the commissioning phase, the detector will collect data
in a high-energy neutron beamline that is part of the Los Alamos Neutron
Science Center to measure cross-sections of spallation products that are
backgrounds to measurements of neutrinos from a supernova burst, cross-sections
of events that mimic the electron neutrino appearance signal in long-baseline
neutrino physics and neutron signatures to constrain neutrino energy
reconstruction in LBNE's long-baseline program. Subsequent to the neutron
running, the CAPTAIN detector will be moved to a neutrino source. Two
possibilities are an on-axis run in the NuMI beamline at FNAL and a run in the
neutrino source produced by the SNS. An on-axis run at NuMI produces more than
one million events of interest in a two or three year run at neutrino energies
between 1 and 10 GeV - complementary to the MicroBooNE experiment, which will
measure similar interactions at a lower energy range - 0.5 to 2 GeV. At the SNS
the neutrinos result from the decays stopped positively charged pions and muons
yielding a broad spectrum up to 50 MeV. If located close to the spallation
target, CAPTAIN can detect several thousand events per year in the same
neutrino energy regime where neutrinos from a supernova burst are. Measurements
at the SNS yield a first measurement of the cross- section of neutrinos on
argon in this important energy regime.


title: Optimal Time-Trial Bicycle Racing with Headwinds and Tailwinds

abstract:
  Many time-trial and triathlon bicycle races take place on relatively flat,
closed-circuit courses. In the absence of hills, riding-speed is limited almost
solely by aerodynamic drag; consequently, winds can have a big effect on
elapsed times. I analyze the special case of a straight out-and-back race in a
steady wind, assuming the rider has a given total amount of energy to expend
and can choose only two speeds - the aided speed with tailwind and the hindered
speed into headwind. In this ideal circumstance the problem of choosing optimal
riding speeds reduces to a constrained nonlinear optimization that can be
solved with elementary calculus. My analysis reveals a practical rule of thumb
that can be used more generally to choose optimal riding speeds for time-trial
racing on closed-circuit courses in the presence of headwinds and tailwinds.


title: Multi-Agent Systems and Blood Cell Formation

abstract:
  The objective of this chapter is to give an insight of the mathematical
modellng of hematopoiesis using multi-agent systems. Several questions may
arise then: what is hematopoiesis and why is it interesting to study this
problem from a mathematical point of view? Has the multi-agent system approach
been the only attempt done until now? What does it bring more than other
techniques? What were the results obtained? What is there left to do?


title:
Dynamical Electroweak Symmetry Breaking with a heavy fermion in light of
  recent LHC results

abstract:
  The recent announcement of a discovery of a possible Higgs-like particle -its
spin and parity is yet to be determined- at the LHC with a mass of 126 GeV
necessitates a fresh look at the nature of the electroweak symmetry breaking,
in particular if this newly-discovered particle will turn out to have the
quantum numbers of a Standard Model Higgs boson. Even if it were a $0^+$ scalar
with the properties expected for a SM Higgs boson, there is still the
quintessential hierarchy problem that one has to deal with and which, by
itself, suggests a new physics energy scale around 1 TeV. This article presents
a mini-review of one possible scenario: The formation of a fermion-antifermion
condensate coming from a very heavy fourth generation and carrying the quantum
number of the the SM Higgs field and thus breaking the electroweak symmetry.


title: Wave turbulence in shallow water models

abstract:
  We study wave turbulence in shallow water flows in numerical simulations
using two different approximations: the shallow water model, and the Boussinesq
model with weak dispersion. The equations for both models were solved using
periodic grids with up to $2048^2$ points. In all simulations, the Froude
number varies between $0.015$ and $0.05$, while the Reynolds number and level
of dispersion are varied in a broader range to span different regimes. In all
cases, most of the energy in the system remains in the waves, even after
integrating the system for very long times. For shallow flows, non-linear waves
are non-dispersive and the spectrum of potential energy is compatible with
$\sim k^{-2}$ scaling. For deeper (Boussinesq) flows, the non-linear dispersion
relation as directly measured from the wave and frequency spectrum (calculated
independently) shows signatures of dispersion, and the spectrum of potential
energy is compatible with predictions of weak turbulence theory, $\sim
k^{-4/3}$. In this latter case, the non-linear dispersion relation differs from
the linear one and has two branches, which we explain with a simple qualitative
argument. Finally, we study probability density functions of the surface height
and find that in all cases the distributions are asymmetric. The probability
density function can be approximated by a skewed normal distribution as well as
by a Tayfun distribution.


title: Metal-insulator transition induced in SrTi_{1-x}V_xO_3 thin films

abstract:
  Epitaxial SrTi1-xVxO3 thin films with thicknesses of ~16 nm were grown on
(001)-oriented LSAT substrates using the pulsed electron-beam deposition
technique. The transport study revealed a temperature driven metal-insulator
transition (MIT) at 95 K for the film with x = 0.67. The films with higher
vanadium concentration (x > 0.67) were metallic, and the electrical resistivity
followed the T^2 law corresponding to a Fermi liquid system. In the insulating
region of x < 0.67, the temperature dependence of electrical resistivity for
the x = 0.5 and 0.33 films can be scaled with the variable range hopping model.
The possible mechanisms behind the observed MIT were discussed, including the
effects of electron correlation, lattice distortion and Anderson localization.


title: Quantum Dynamics Simulation with Classical Oscillators

abstract:
  In a previous paper [J.S.Briggs and A.Eisfeld, Phys.Rev.A 85, 052111] we
showed that the time-development of the complex amplitudes of N coupled quantum
states can be mapped by the time development of positions and velocities of N
coupled classical oscillators. Here we examine to what extent this mapping can
be realised to simulate the "quantum" properties of entanglement and qubit
manipulation. By working through specific examples, e.g. of quantum gate
operation, we seek to illuminate quantum/classical differences which hitherto
have been treated more mathematically. In addition we show that important
quantum coupled phenomena, such as the Landau-Zener transition and the
occurrence of Fano resonances can be simulated by classical oscillators.


title: Stochastic Agent-Based Simulations of Social Networks

abstract:
  The rapidly growing field of network analytics requires data sets for use in
evaluation. Real world data often lack truth and simulated data lack narrative
fidelity or statistical generality. This paper presents a novel,
mixed-membership, agentbased simulation model to generate activity data with
narrative power while providing statistical diversity through random draws. The
model generalizes to a variety of network activity types such as Internet and
cellular communications, human mobility, and social network interactions. The
simulated actions over all agents can then drive an application specific
observational model to render measurements as one would collect in real-world
experiments. We apply this framework to human mobility and demonstrate its
utility in generating high fidelity traffic data for network analytics.


title:
Inflated Cauchy Filters - A Way to Construct the Completion of a General
  Uniform Space

abstract:
  Treatises about General Topology that emphasize the notion of uniformity and
uniform space find, of course, no difficulty in defining the notion of a
complete uniform space and in constructing the completion of a metric space,
via its Cauchy sequences. In contrast, constructing the completion of a general
uniform space, especially without recourse to pseudometrics, presents itself as
somewhat awkward. In this note the notion of an inflated Cauchy filter is
proposed as a way to accomplish that. As the author learned later, all that was
actually expounded in Bourbaki, Topologie Generale, 1966 edition (where the
filters are referred to as minimal Cauchy rather than inflated Cauchy), hence
this note was withdrawn by the author.


title: Nodal theorems for the Dirac equation in d >= 1 dimensions

abstract:
  A single particle obeys the Dirac equation in $d \ge 1$ spatial dimensions
and is bound by an attractive central monotone potential that vanishes at
infinity. In one dimension, the potential is even, and monotone for $x\ge 0.$
The asymptotic behavior of the wave functions near the origin and at infinity
are discussed. Nodal theorems are proven for the cases $d=1$ and $d > 1$, which
specify the relationship between the numbers of nodes $n_1$ and $n_2$ in the
upper and lower components of the Dirac spinor. For $d=1$, $n_2 = n_1 + 1,$
whereas for $d >1,$ $n_2 = n_1 +1$ if $k_d > 0,$ and $n_2 = n_1$ if $k_d < 0,$
where $k_d = \tau(j + \frac{d-2}{2}),$ and $\tau = \pm 1.$ This work
generalizes the classic results of Rose and Newton in 1951 for the case $d=3.$
Specific examples are presented with graphs, including Dirac spinor orbits
$(\psi_1(r), \psi_2(r)), r \ge 0.$


title: Operadic multiplications in equivariant spectra, norms, and transfers

abstract:
  We study homotopy-coherent commutative multiplicative structures on
equivariant spaces and spectra. We define N-infinity operads, equivariant
generalizations of E-infinity operads. Algebras in equivariant spectra over an
N-infinity operad model homotopically commutative equivariant ring spectra that
only admit certain collections of Hill-Hopkins-Ravenel norms, determined by the
operad. Analogously, algebras in equivariant spaces over an N-infinity operad
provide explicit constructions of certain transfers. This characterization
yields a conceptual explanation of the structure of equivariant infinite loop
spaces.
  To explain the relationship between norms, transfers, and N-infinity operads,
we discuss the general features of these operads, linking their properties to
families of finite sets with group actions and analyzing their behavior under
norms and geometric fixed points. A surprising consequence of our study is that
in stark contract to the classical setting, equivariantly the little disks and
linear isometries operads for a general universe $U$ need not determine the
same algebras.
  Our work is motivated by the need to provide a framework to describe the
flavors of commutativity seen in recent work of the second author and Hopkins
on localization of equivariant commutative ring spectra.


title:
Asymptotic formulas for spectral gaps and deviations of Hill and 1D
  Dirac operators

abstract:
  Let $L$ be the Hill operator or the one dimensional Dirac operator on the
interval $[0,\pi].$ If $L$ is considered with Dirichlet, periodic or
antiperiodic boundary conditions, then the corresponding spectra are discrete
and for large enough $|n|$ close to $n^2 $ in the Hill case, or close to $n, \;
n\in \mathbb{Z}$ in the Dirac case, there are one Dirichlet eigenvalue $\mu_n$
and two periodic (if $n$ is even) or antiperiodic (if $n$ is odd) eigenvalues
$\lambda_n^-, \, \lambda_n^+ $ (counted with multiplicity).
  We give estimates for the asymptotics of the spectral gaps $\gamma_n =
\lambda_n^+ - \lambda_n^-$ and deviations $ \delta_n =\mu_n - \lambda_n^+$ in
terms of the Fourier coefficients of the potentials. Moreover, for special
potentials that are trigonometric polynomials we provide precise asymptotics of
$\gamma_n$ and $\delta_n.$


title: Percolation with constant freezing

abstract:
  We introduce and study a model of percolation with constant freezing (PCF)
where edges open at constant rate 1, and clusters freeze at rate \alpha
independently of their size. Our main result is that the infinite volume
process can be constructed on any amenable vertex transitive graph. This is in
sharp contrast to models of percolation with freezing previously introduced,
where the limit is known not to exist. Our interest is in the study of the
percolative properties of the final configuration as a function of \alpha. We
also obtain more precise results in the case of trees. Surprisingly the
algebraic exponent for the cluster size depends on the degree, suggesting that
there is no lower critical dimension for the model. Moreover, even for
\alpha<\alpha_c, it is shown that finite clusters have algebraic tail decay,
which is a signature of self organised criticality. Partial results are
obtained on Z^d, and many open questions are discussed.


title: Gyro-induced acceleration of magnetic reconnection

abstract:
  The linear and nonlinear evolution of magnetic reconnection in collisionless
high-temperature plasmas with a strong guide field is analyzed on the basis of
a two-dimensional gyrofluid model. The linear growth rate of the reconnecting
instability is compared to analytical calculations over the whole spectrum of
linearly unstable wave numbers. In the strongly unstable regime (large \Delta
'), the nonlinear evolution of the reconnecting instability is found to undergo
two distinctive acceleration phases separated by a stall phase in which the
instantaneous growth rate decreases. The first acceleration phase is caused by
the formation of strong electric fields close to the X-point due to ion
gyration, while the second acceleration phase is driven by the development of
an open Petschek-like configuration due to both ion and electron temperature
effects. Furthermore, the maximum instantaneous growth rate is found to
increase dramatically over its linear value for decreasing diffusion layers.
This is a consequence of the fact that the peak instantaneous growth rate
becomes weakly dependent on the microscopic plasma parameters if the diffusion
region thickness is sufficiently smaller than the equilibrium magnetic field
scale length. When this condition is satisfied, the peak reconnection rate
asymptotes to a constant value.

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


title: Bayesian estimation of a sparse precision matrix

abstract:
  We consider the problem of estimating a sparse precision matrix of a
multivariate Gaussian distribution, including the case where the dimension $p$
is large. Gaussian graphical models provide an important tool in describing
conditional independence through presence or absence of the edges in the
underlying graph. A popular non-Bayesian method of estimating a graphical
structure is given by the graphical lasso. In this paper, we consider a
Bayesian approach to the problem. We use priors which put a mixture of a point
mass at zero and certain absolutely continuous distribution on off-diagonal
elements of the precision matrix. Hence the resulting posterior distribution
can be used for graphical structure learning. The posterior convergence rate of
the precision matrix is obtained. The posterior distribution on the model space
is extremely cumbersome to compute. We propose a fast computational method for
approximating the posterior probabilities of various graphs using the Laplace
approximation approach by expanding the posterior density around the posterior
mode, which is the graphical lasso by our choice of the prior distribution. We
also provide estimates of the accuracy in the approximation.


title: From adhesion to wetting of a soft particle

abstract:
  Using a thermodynamical approach, we calculate the deformation of a spherical
elastic particle placed on a rigid substrate, under zero external load, and
including an ingredient of importance in soft matter: the interfacial tension
of the cap. In a first part, we limit the study to small deformation. In
contrast with previous works, we obtain an expression for the energy that
precisely contains the JKR and Young-Dupr\'e asymptotic regimes, and which
establishes a continuous bridge between them. In a second part, we consider the
large deformation case, which is relevant for future comparison with numerical
simulations and experiments on very soft materials. Using a fruitful analogy
with fracture mechanics, we derive the exact energy of the problem and thus
obtain the equilibrium state for any given choice of physical parameters.

categories: cond-mat.soft cond-mat.mes-hall cond-mat.mtrl-sci physics.chem-ph physics.class-ph


title:
An exchange functional that tests the robustness of the plasmon
  description of the van der Waals density functional

abstract:
  Is the plasmon description within the non-local correlation of the van der
Waals density functional by Dion and coworkers (vdW-DF1) robust enough to
describe all exchange-correlation components? To address this question, we
design an exchange functional, termed LV-PW86r based on this plasmon
description as well as recent analysis on exchange in the large $s$-regime. In
the regime with reduced gradients $s=|\nabla n|/2n k_{\rm F}(n)$ smaller than
$\approx 2.5$, dominating the non-local correlation part of the binding energy,
the enhancement factor $F_x(s)$ closely resembles the Langreth-Vosko screened
exchange. In the $s$-regime beyond, dominated by exchange, $F_x(s)$ passes
smoothly over to the revised Perdew-Wang-86 form. Our tests indicate that
vdW-DF1(LV-PW86r) produces accurate separations and binding energies of the S22
data set of molecular dimers as well as accurate lattice constants of layered
materials and tightly-bound solids. These results suggest that vdW-DF1 has a
good plasmon description in the low-to-moderate $s$-regime.

categories: cond-mat.mtrl-sci cond-mat.mes-hall cond-mat.soft physics.chem-ph


title:
Inflation, unemployment, and labor force. Phillips curves and long-term
  projections for Japan

abstract:
  The evolution of the rate of price inflation and unemployment in Japan has
been modeled within the Phillips curve framework. As an extension to the
Phillips curve, we represent both variables as linear functions of the change
rate of labor force. All models were first estimated in 2005 for the period
between 1980 and 2003. Here we update these original models with data through
2012. The revisited models accurately describe disinflation during the 1980s
and 1990s as well as the whole deflationary period started in the late 1990s.
The Phillips curve for Japan confirms the original concept that growing
unemployment results in decreasing inflation. A linear and lagged generalized
Phillips curve expressed as a link between inflation, unemployment, and labor
force has been also re-estimated and validated by new data. Labor force
projections allow a long-term inflation and unemployment forecast: the GDP
deflator will be negative (between -0.5% and -2% per year) during the next 40
years. The rate of unemployment will increase from 4.3% in 2012 to 5.5% in
2050.


abstract:
  We present Finslerian perturbation for the $\Lambda$CDM model, which breaks
the isotropic symmetry of the universe. The analysis on the Killing vectors
shows that the Randers-Finsler spacetime breaks the isotropic symmetry even if
the scalar perturbations of the FRW metric vanish. In Randers-Finsler
spacetime, the modified geodesic equation deduces a modified Boltzmann
equation. We propose a perturbational version of the gravitational field
equation in Randers-Finsler spacetime, where we have omitted the curvature
tensor that does not belong to the base space of the tangent bundle. The
gravitational field equations for the gravitational wave are also presented.
The primordial power spectrum of the gravitational wave is investigated. We
show that the primordial power spectrum for super-horizon perturbations is
unchanged. For sub-horizon perturbations, however, the power spectrum is
modified.


title: Weighted energy decay for magnetic Klein-Gordon equation

abstract:
  We obtain a dispersive long-time decay in weighted energy norms for solutions
of 3D Klein-Gordon equation with magnetic and scalar potentials. The decay
extends the results obtained by Jensen and Kato for the Schroedinger equation
with scalar potential. For the proof we develop the spectral theory of Agmon,
Jensen and Kato and minimal escape velocities estimates of Hunziker, Sigal and
Soffer.


title:
Hypercyclicity and k-Transitivity (k>=2) for abelian semigroup of affine
  maps on C^n

abstract:
  In this paper, we prove that the minimal number of affine maps on C^n,
required to form a hypercyclic abelian semigroup on C^n is n+1. We also prove
that the action of any abelian group finitely generated by affine maps on C^n,
is never k-transitive for k>=2.


title:
Convergence of Nearest Neighbor Pattern Classification with Selective
  Sampling

abstract:
  In the panoply of pattern classification techniques, few enjoy the intuitive
appeal and simplicity of the nearest neighbor rule: given a set of samples in
some metric domain space whose value under some function is known, we estimate
the function anywhere in the domain by giving the value of the nearest sample
per the metric. More generally, one may use the modal value of the m nearest
samples, where m is a fixed positive integer (although m=1 is known to be
admissible in the sense that no larger value is asymptotically superior in
terms of prediction error). The nearest neighbor rule is nonparametric and
extremely general, requiring in principle only that the domain be a metric
space. The classic paper on the technique, proving convergence under
independent, identically-distributed (iid) sampling, is due to Cover and Hart
(1967). Because taking samples is costly, there has been much research in
recent years on selective sampling, in which each sample is selected from a
pool of candidates ranked by a heuristic; the heuristic tries to guess which
candidate would be the most "informative" sample. Lindenbaum et al. (2004)
apply selective sampling to the nearest neighbor rule, but their approach
sacrifices the austere generality of Cover and Hart; furthermore, their
heuristic algorithm is complex and computationally expensive. Here we report
recent results that enable selective sampling in the original Cover-Hart
setting. Our results pose three selection heuristics and prove that their
nearest neighbor rule predictions converge to the true pattern. Two of the
algorithms are computationally cheap, with complexity growing linearly in the
number of samples. We believe that these results constitute an important
advance in the art.


title: Radio Synchrotron Emission from the Bow Shock of G2

abstract:
  The radio flux from the synchrotron emission of electrons accelerated in the
forward bow shock of G2 is expected to peak when the forward shock passes
pericenter, possibly 7 to 9 months before the center of mass of G2 reaches
pericenter ~3x10^15 cm from the Galactic Center (Narayan et al. 2012; Sadowski
et al. 2013a,b). In this letter, we calculate the radio emission from the
forward and reverse shock if G2 is a momentum-supported bow shock of a faint
star with a high mass-loss rate as suggested by Scoville & Burkert (2013);
Ballone et al. (2013). We show that the radio flux lies well below the
quiescent radio flux of Sgr A* and will be difficult to detect. By contrast, in
the cloud model of G2, the radio flux of the forward shock is predicted to be
much larger than the quiescent radio flux and therefore should have already
been detected (Narayan et al. 2012; Sadowski et al. 2013b). Therefore, radio
measurements can reveal the nature of G2 well before G2 completes its periapsis
passage.


title:
Abundant cyanopolyynes as a probe of infall in the Serpens South
  cluster-forming region

abstract:
  We have detected bright HC7N J = 21-20 emission toward multiple locations in
the Serpens South cluster-forming region using the K-Band Focal Plane Array at
the Robert C. Byrd Green Bank Telescope. HC7N is seen primarily toward cold
filamentary structures that have yet to form stars, largely avoiding the dense
gas associated with small protostellar groups and the main central cluster of
Serpens South. Where detected, the HC7N abundances are similar to those found
in other nearby star forming regions. Toward some HC7N `clumps', we find
consistent variations in the line centroids relative to NH3 (1,1) emission, as
well as systematic increases in the HC7N non-thermal line widths, which we
argue reveal infall motions onto dense filaments within Serpens South with
minimum mass accretion rates of M ~ 2-5 M_sun Myr^-1. The relative abundance of
NH3 to HC7N suggests that the HC7N is tracing gas that has been at densities n
~ 10^4 cm^-3, for timescales t < 1-2 x 10^5 yr. Since HC7N emission peaks are
rarely co-located with those of either NH3 or continuum, it is likely that
Serpens South is not particularly remarkable in its abundance of HC7N, but
instead the serendipitous mapping of HC7N simultaneously with NH3 has allowed
us to detect HC7N at low abundances in regions where it otherwise may not have
been looked for. This result extends the known star-forming regions containing
significant HC7N emission from typically quiescent regions, like the Taurus
molecular cloud, to more complex, active environments.


title:
Standard Model Explanation of the Ultra-high Energy Neutrino Events at
  IceCube

abstract:
  The recent observation of two PeV events at IceCube, followed by an
additional 26 events between 30 - 300 TeV, has generated considerable
speculations on its origin, and many exotic New Physics explanations have been
invoked. For a reliable interpretation, it is however important to first
scrutinize the Standard Model (SM) expectations carefully, including the
theoretical uncertainties, mainly due to the parton distribution functions.
Assuming a new isotropic cosmic neutrino flux with a simple unbroken power-law
spectrum, $\Phi\propto E^{-s}$ for the entire energy range of interest, we find
that with $s=1.5$ - 2, the SM neutrino-nucleon interactions are sufficient to
explain all the observed events so far, without the need for any beyond the SM
explanation. With more statistics, this powerful detector could provide a
unique test of the SM up to the PeV scale, and lead to important clues of New
Physics.


title: Dynamics and Conductivity Near Quantum Criticality

abstract:
  Relativistic O(N) field theories are studied near the quantum critical point
in two space dimensions. We compute dynamical correlations by large scale Monte
Carlo simulations and numerical analytic continuation. In the ordered side, the
scalar spectral function exhibits a universal peak at the Higgs mass. For N=3
and 4 we confirm its \omega^3 rise at low frequency. On the disordered side,
the spectral function exhibits a sharp gap. For N=2, the dynamical conductivity
rises above a threshold at the Higgs mass (density gap), in the superfluid
(Mott insulator) phase. For charged bosons, (Josephson arrays) the power law
rise above the Higgs mass, increases from two to four. Approximate
charge-vortex duality is reflected in the ratio of imaginary conductivities on
either side of the transition. We determine the critical conductivity to be
\sigma^*_c = 0.3 (\pm 0.1) 4e^2/h. In the appendices, we describe a
generalization of the worm algorithm to N>2, and also a singular value
decomposition error analysis for the numerical analytic continuation.

categories: cond-mat.str-el cond-mat.quant-gas cond-mat.stat-mech cond-mat.supr-con


title: Vector Valued Siegel Modular Forms for \Gamma_2[2,4] and Sym^2

abstract:
  We develop two structure theorems for vector valued Siegel modular forms for
Igusa's subgroup \Gamma_2[2,4], the multiplier system induced by the theta
constants and the representation Sym^2. In the proof, we identify some of these
modular forms with rational tensors with easily handleable poles on P^3\C. It
follows that the observed modules of modular forms are generated by the
Rankin-Cohen brackets of the four theta series of the second kind.


title: Pulsar Timing Techniques

abstract:
  We describe the procedure, nuances, issues, and choices involved in creating
times-of-arrival (TOAs), residuals and error bars from a set of radio pulsar
timing data. We discuss the issue of mis-matched templates, the problem that
wide- bandwidth backends introduce, possible solutions to that problem, and
correcting for offsets introduced by various observing systems.


title: DNA evolved to minimize frameshift mutations

abstract:
  Point mutations can surely be dangerous but what is worst than to lose the
reading frame?! Does DNA evolved a strategy to try to limit frameshift
mutations?! Here we investigate if DNA sequences effectively evolved a system
to minimize frameshift mutations analyzing the transcripts of proteins with
high molecular weights.


title:
Energy release from impacting prominence material following the 2011
  June 7 eruption

abstract:
  Solar filaments exhibit a range of eruptive-like dynamic activity, ranging
from the full or partial eruption of the filament mass and surrounding magnetic
structure as a coronal mass ejection (CME), to a fully confined or 'failed'
eruption. On 2011 June 7, a dramatic partial eruption of a filament was
observed by multiple instruments on SDO and STEREO. One of the interesting
aspects of this event is the response of the solar atmosphere as non-escaping
material falls inward under the influence of gravity. The impact sites show
clear evidence of brightening in the observed EUV wavelengths due to energy
release. Two plausible physical mechanisms explaining the brightening are
considered: heating of the plasma due to the kinetic energy of impacting
material compressing the plasma, or reconnection between the magnetic field of
low-lying loops and the field carried by the impacting material. By analyzing
the emission of the brightenings in several SDO/AIA wavelengths, and comparing
the kinetic energy of the impacting material (7.6 x 10^26 - 5.8 x 10^27 ergs)
to the radiative energy (1.9 x 10^25 - 2.5 x 10^26 ergs) we find the dominant
mechanism of energy release involved in the observed brightening is plasma
compression.


title: The AE Theorem and addition theorems for quasi-convex functions

abstract:
  The main point of this paper is to prove the following useful result: If the
almost everywhere 2-jet of a locally quasi-convex function u satisfies a
degenerate elliptic constraint F, then u is F-subharmonic, i.e., u is a
viscosity F-subsolution. This AE Theorem makes otherwise difficult results
transparent. Some instances of this are presented, including two versions of
addition, and a comparison theorem.


title: When is a Squarefree Monomial Ideal of Linear Type ?

abstract:
  In 1995 Villarreal gave a combinatorial description of the equations of Rees
algebras of quadratic squarefree monomial ideals. His description was based on
the concept of closed even walks in a graph. In this paper we will generalize
his results for all squarefree monomial ideals by using a definition of even
walks in a simplicial complex.


title: Notes on the differentiation of quasi-convex functions

abstract:
  This expository paper presents elementary proofs of four basic results
concerning derivatives of quasi-convex functions. They are combined into a
fifth theorem which is simple to apply and adequate in many cases. Along the
way we establish the equivalence of the basic lemmas of Jensen and Slodkowski.


title: Iterative representing set selection for nested cross approximation

abstract:
  A new fast algebraic method for obtaining an $\mathcal{H}^2$-approximation of
a matrix from its entries is presented. The main idea behind the method is
based on the nested representation and the maximum-volume principle to select
submatrices in low-rank matrices. A special iterative approach for the
computation of so-called representing sets is established. The main advantage
of the method is that it uses only the hierarchical partitioning of the matrix
and does not require special "proxy surfaces" to be selected in advance.
  The numerical experiments for the electrostatic problem and for the boundary
integral operator confirm the effectiveness and robustness of the approach. The
complexity is linear in the matrix size and polynomial in the ranks. The
algorithm is implemented as an open-source Python package that is available
online.


title:
The Diffusion Approximation for the Linear Boltzmann Equation with
  Vanishing Scattering Coefficient

abstract:
  The present paper discusses the diffusion approximation of the linear
Boltzmann equation in cases where the collision frequency is not uniformly
large in the spatial domain. Our results apply for instance to the case of
radiative transfer in a composite medium with optically thin inclusions in an
optically thick background medium. The equation governing the evolution of the
approximate particle density coincides with the limit of the diffusion equation
with infinite diffusion coefficient in the optically thin inclusions.


title:
Prediction Stability in a data-based mechanistic model of sigmaF during
  sporulation in Bacillus subtilis

abstract:
  Mathematical modeling of biological networks can help to integrate a large
body of information into a consistent framework, which can then be used to
arrive at novel mechanistic insight and predictions. We have previously
developed a detailed, mechanistic model for the regulation of {\sigma}F during
sporulation in Bacillus subtilis. The model was based on a wide range of
quantitative data, and once fitted to the data, the model made predictions that
could be confirmed in experiments. However, the analysis was based on a single
optimal parameter set. We wondered whether the predictions of the model would
be stable for all optimal parameter sets. To that end we conducted a global
parameter screen within the physiological parameter ranges. The screening
approach allowed us to identify sensitive and sloppy parameters, and
highlighted further required datasets during the optimization. Eventually, all
parameter sets that reproduced all available data predicted the physiological
situation correctly.


title: Algorithms for group isomorphism via group extensions and cohomology

abstract:
  The isomorphism problem for finite groups of order n (GpI) has long been
known to be solvable in $n^{\log n+O(1)}$ time, but only recently were
polynomial-time algorithms designed for several interesting group classes.
Inspired by recent progress, we revisit the strategy for GpI via the extension
theory of groups.
  The extension theory describes how a normal subgroup N is related to G/N via
G, and this naturally leads to a divide-and-conquer strategy that splits GpI
into two subproblems: one regarding group actions on other groups, and one
regarding group cohomology. When the normal subgroup N is abelian, this
strategy is well-known. Our first contribution is to extend this strategy to
handle the case when N is not necessarily abelian. This allows us to provide a
unified explanation of all recent polynomial-time algorithms for special group
classes.
  Guided by this strategy, to make further progress on GpI, we consider
central-radical groups, proposed in Babai et al. (SODA 2011): the class of
groups such that G mod its center has no abelian normal subgroups. This class
is a natural extension of the group class considered by Babai et al. (ICALP
2012), namely those groups with no abelian normal subgroups. Following the
above strategy, we solve GpI in $n^{O(\log \log n)}$ time for central-radical
groups, and in polynomial time for several prominent subclasses of
central-radical groups. We also solve GpI in $n^{O(\log\log n)}$ time for
groups whose solvable normal subgroups are elementary abelian but not
necessarily central. As far as we are aware, this is the first time there have
been worst-case guarantees on a $n^{o(\log n)}$-time algorithm that tackles
both aspects of GpI---actions and cohomology---simultaneously.


title:
Ultrafast carrier dynamics in thin-films of the topological insulator
  Bi2Se3

abstract:
  Transient reflectivity measurements of thin films, ranging from 6 to 40 nm in
thickness, of the topological insulator Bi2Se3 revealed a strong dependence of
the carrier relaxation time on the film thickness. For thicker films the
relaxation dynamics are similar to those of bulk Bi2Se3, where the contribution
of the bulk insulating phase dominates over that of the surface metallic phase.
The carrier relaxation time shortens with decreasing film thickness, reaching
values comparable to those of noble metals. This effect may result from the
hybridization of Dirac cone states at the opposite surfaces for the thinnest
films.


title: Complex Network Structure of Flocks in the Standard Vicsek Model

abstract:
  In flocking models, the collective motion of self-driven individuals leads to
the formation of complex spatiotemporal patterns. The Standard Vicsek Model
(SVM) considers individuals that tend to adopt the direction of movement of
their neighbors under the influence of noise. By performing an extensive
complex network characterization of the structure of SVM flocks, we show that
flocks are highly clustered, assortative, and non-hierarchical networks with
short-tailed degree distributions. Moreover, we also find that the SVM dynamics
leads to the formation of complex structures with an effective dimension higher
than that of the space where the actual displacements take place. Furthermore,
we show that these structures are capable of sustaining mean-field-like
orientationally ordered states when the displacements are suppressed, thus
suggesting a linkage between the onset of order and the enhanced dimensionality
of SVM flocks.


title: Fractal dimension versus process complexity

abstract:
  Complexity measures are designed to capture complex behavior and quantify
*how* complex, according to that measure, that particular behavior is. It can
be expected that different complexity measures from possibly entirely different
fields are related to each other in a non-trivial fashion. Here we study small
Turing machines (TMs) with two symbols, and two and three states. For any
particular such machine $\tau$ and any particular input $x$ we consider what we
call the 'space-time' diagram which is the collection of consecutive tape
configurations of the computation $\tau(x)$. In our setting, we define fractal
dimension of a Turing machine as the limiting fractal dimension of the
corresponding space-time diagram. It turns out that there is a very strong
relation between the fractal dimension of a Turing machine of the
above-specified type and its runtime complexity. In particular, a TM with three
states and two colors runs in at most linear time iff its dimension is 2, and
its dimension is 1 iff it runs in super-polynomial time and it uses polynomial
space. If a TM runs in time $O(x^n)$ we have empirically verified that the
corresponding dimension is $(n+1)/n$, a result that we can only partially
prove. We find the results presented here remarkable because they relate two
completely different complexity measures: the geometrical fractal dimension on
the one side versus the time complexity of a computation on the other side.


title:
Software Abstractions and Methodologies for HPC Simulation Codes on
  Future Architectures

abstract:
  Large, complex, multi-scale, multi-physics simulation codes, running on high
performance com-puting (HPC) platforms, have become essential to advancing
science and engineering. These codes simulate multi-scale, multi-physics
phenomena with unprecedented fidelity on petascale platforms, and are used by
large communities. Continued ability of these codes to run on future platforms
is as crucial to their communities as continued improvements in instruments and
facilities are to experimental scientists. However, the ability of code
developers to do these things faces a serious challenge with the paradigm shift
underway in platform architecture. The complexity and uncertainty of the future
platforms makes it essential to approach this challenge cooperatively as a
community. We need to develop common abstractions, frameworks, programming
models and software development methodologies that can be applied across a
broad range of complex simulation codes, and common software infrastructure to
support them. In this position paper we express and discuss our belief that
such an infrastructure is critical to the deployment of existing and new large,
multi-scale, multi-physics codes on future HPC platforms.


title:
Experiences from Software Engineering of Large Scale AMR Multiphysics
  Code Frameworks

abstract:
  Among the present generation of multiphysics HPC simulation codes there are
many that are built upon general infrastructural frameworks. This is especially
true of the codes that make use of structured adaptive mesh refinement (SAMR)
because of unique demands placed on the housekeeping aspects of the code. They
have varying degrees of abstractions between the infrastructure such as mesh
management and IO and the numerics of the physics solvers. In this experience
report we summarize the experiences and lessons learned from two of such major
software efforts, FLASH and Chombo.


title: Decomposable multiphase entropic descriptor

abstract:
  To quantify degree of spatial inhomogeneity for multiphase materials we adapt
the entropic descriptor (ED) of a pillar model developed to greyscale images.
To uncover the contribution of each phase we introduce the suitable 'phase
splitting' of the adapted descriptor. As a result, each of the phase
descriptors (PDs) describes the spatial inhomogeneity attributed to each
phase-component. Obviously, their sum equals to the value of the overall
spatial inhomogeneity. We apply this approach to three-phase synthetic
patterns. The black and grey components are aggregated or clustered while the
white phase is the background one. The examples show how the valuable
microstuctural information related separately to each of the phases can be
obtained at any integer length scale. Even dissimilar hidden statistical
periodicities can be easily detected for chosen phases built-up of compact
regular clusters.


title:
DUNE as an Example of Sustainable Open Source Scientific Software
  Development

abstract:
  In this paper we describe how DUNE, an open source scientific software
framework, is developed. Having a sustainable software framework for the
solution of partial differential equations is the main driver of DUNE's
development. We take a look how DUNE strives to stay sustainable software.


title: Enabling Reproducible Science with VisTrails

abstract:
  With the increasing amount of data and use of computation in science,
software has become an important component in many different domains. Computing
is now being used more often and in more aspects of scientific work including
data acquisition, simulation, analysis, and visualization. To ensure
reproducibility, it is important to capture the different computational
processes used as well as their executions. VisTrails is an open-source
scientific workflow system for data analysis and visualization that seeks to
address the problem of integrating varied tools as well as automatically
documenting the methods and parameters employed. Growing from a specific
project need to supporting a wide array of users required close collaborations
in addition to new research ideas to design a usable and efficient system. The
VisTrails project now includes standard software processes like unit testing
and developer documentation while serving as a base for further research. In
this paper, we describe how VisTrails has developed and how our efforts in
structuring and advertising the system have contributed to its adoption in many
domains.


title:
#Santiago is not #Chile, or is it? A Model to Normalize Social Media
  Impact

abstract:
  Online social networks are known to be demographically biased. Currently
there are questions about what degree of representativity of the physical
population they have, and how population biases impact user-generated content.
In this paper we focus on centralism, a problem affecting Chile. Assuming that
local differences exist in a country, in terms of vocabulary, we built a
methodology based on the vector space model to find distinctive content from
different locations, and use it to create classifiers to predict whether the
content of a micro-post is related to a particular location, having in mind a
geographically diverse selection of micro-posts. We evaluate them in a case
study where we analyze the virtual population of Chile that participated in the
Twitter social network during an event of national relevance: the municipal
(local governments) elections held in 2012. We observe that the participating
virtual population is spatially representative of the physical population,
implying that there is centralism in Twitter. Our classifiers out-perform a non
geographically-diverse baseline at the regional level, and have the same
accuracy at a provincial level. However, our approach makes assumptions that
need to be tested in multi-thematic and more general datasets. We leave this
for future work.


title:
Turbulence in Binary Bose-Einstein Condensates Generated by Highly
  Non-Linear Rayleigh-Taylor and Kelvin-Helmholtz Instabilities

abstract:
  Quantum turbulence (QT) generated by the Rayleigh-Taylor instability in
binary immiscible ultracold 87Rb atoms at zero temperature is studied
theoretically. We show that the quantum vortex tangle is qualitatively
different from previously considered superfluids, which reveals deep relations
between QT and classical turbulence. The present QT may be generated at
arbitrarily small Mach numbers, which is a unique property not found in
previously studied superfluids. By numerical solution of the coupled
Gross-Pitaevskii equations we find that the Kolmogorov scaling law holds for
the incompressible kinetic energy. We demonstrate that the phenomenon may be
observed in the laboratory.


title:
Revisiting Dirac and Schr\"odinger: A Proof Offered for the
  Non-Relativistic Time-Dependent Schr\"odinger Equation

abstract:
  In this paper, three plausible axioms together with two definitions are
employed to build an axiomatic framework, and then with the help of the Dirac
formalism, it is demonstrated that the time-dependent Schr\"odinger wave
equation is no longer a postulate for the whole theory, but a theorem.
Subsequently, a proof for the theorem is presented. The result implies that the
other remaining axioms of the picture essentially involve the Schr\"odinger
equation, and this consequence lets the whole theory become stronger.


title: Web Standards as Standard Pieces in Robotics

abstract:
  Modern robotics often involves the use of web technologies as a means to cope
with the complexity of design and operation. Many of these technologies have
been formalized into standards, which are often avoided by those in robotics
and controls because of a sometimes warranted fear that "the web" is too slow,
or too uncertain for meaningful control applications.
  In this work we argue that while web technologies may not be applicable for
all control, they should not be dismissed outright because they can provide
critical help with system integration. Web technologies have also advanced
significantly over the past decade. We present the details of an application of
a web server to perform open and close-loop control (between 3Hz and 1kHz) over
a variety of different network topologies. In our study we also consider the
impact of a web browser to implement the control of the plant. Our results
confirm that meaningful control can be performed using web technologies, and
also highlight design choices that can limit their applicability.


title: Heteroepitaxy of Group IV-VI Nitrides by Atomic Layer Deposition

abstract:
  Heteroepitaxial growth of selected group IV-VI nitrides on various
orientations of sapphire (\alpha-Al2O3) is demonstrated using atomic layer
deposition. High quality, epitaxial films are produced at significantly lower
temperatures than required by conventional deposition methods. Characterization
of electrical and superconducting properties of epitaxial films reveals a
reduced room temperature resistivity and increased residual resistance ratio
(RRR) for films deposited on sapphire compared to polycrystalline samples
deposited concurrently on fused quartz substrates.


title:
New Global Exponential Stability Criteria for Nonlinear Delay
  Differential Systems with Applications to BAM Neural Networks

abstract:
  We consider a nonlinear non-autonomous system with time-varying delays $$
\dot{x_i}(t)=-a_i(t)x_{i}(h_i(t))+\sum_{j=1}^mF_{ij}(t,x_j(g_{ij}(t))) $$ which
has a large number of applications in the theory of artificial neural networks.
Via the M-matrix method, easily verifiable sufficient stability conditions for
the nonlinear system and its linear version are obtained. Application of the
main theorem requires just to check whether a matrix, which is explicitly
constructed by the system's parameters, is an $M$-matrix. Comparison with the
tests obtained by K. Gopalsamy (2007) and B. Liu (2013) for BAM neural networks
illustrates novelty of the stability theorems. Some open problems conclude the
paper.


title:
Free Pick functions: representations, asymptotic behavior and matrix
  monotonicity in several noncommuting variables

abstract:
  We extend the study of the Pick class, the set of complex analytic functions
taking the upper half plane into itself, to the noncommutative setting. R.
Nevanlinna showed that elements of the Pick class have certain integral
representations which reflect their asymptotic behavior at infinity. Loewner
connected the Pick class to matrix monotone functions. We generalize the
Nevanlinna representation theorems and Loewner's theorem on matrix monotone
functions to the free Pick class, the collection of functions that map tuples
of matrices with positive imaginary part into the matrices with positive
imaginary part which obey the free functional calculus.


title:
Desktop and Mobile Web Page Comparison: Characteristics, Trends, and
  Implications

abstract:
  The broad proliferation of mobile devices in recent years has drastically
changed the means of accessing the World Wide Web. Describing a shift away from
the desktop computer era for content consumption, predictions indicate that the
main access of web-based content will come from mobile devices. Concurrently,
the manner of content presentation has changed as well; web artifacts are
allowing for richer media and higher levels of user interaction which is
enabled through increasing access networks speeds. This article provides an
overview of more than two years of high level web page characteristics by
comparing the desktop and mobile client versions. Our study is the first
long-term evaluation of differences as seen by desktop and mobile web browser
clients. We showcase the main differentiating factors with respect to the
number of web page object requests, their sizes, relationships, and web page
object caching. We additionally highlight long-term trends and discuss their
future implications.


title: Inflationary Consistency Conditions from a Wavefunctional Perspective

abstract:
  It is shown that the squeezed limit of inflationary expectation values
follows from reparametrization invariance of the wavefunction of the universe.
This translates into a constraint on the longitudinal modes of functional
derivatives of the wavefunction. Thus, the local non-Gaussianity induced by
single field inflation is purely a gauge artifact, and should not yield a
physically measurable effect. We focus on Einstein gravity in de Sitter space
and single field inflation, although the formalism only relies on the
diffeomorphism invariance of the theory, and thus applies to any theory of
gravity.


title: An Adaptive Algorithm for Synchronization in Diffusively Coupled Systems

abstract:
  We present an adaptive algorithm that guarantees synchronization in
diffusively coupled systems. We first consider compartmental systems of ODEs,
where each compartment represents a spatial domain of components interconnected
through diffusion terms with like components in different compartments. Each
set of like components may have its own weighted undirected graph describing
the topology of the interconnection between compartments. The link weights are
updated adaptively according to the magnitude of the difference between
neighboring agents connected by the link. We next consider reaction-diffusion
PDEs with Neumann boundary conditions, and derive an analogous algorithm
guaranteeing spatial homogenization of solutions. We provide a numerical
example demonstrating the results.


title:
Finding role communities in directed networks using Role-Based
  Similarity, Markov Stability and the Relaxed Minimum Spanning Tree

abstract:
  We present a framework to cluster nodes in directed networks according to
their roles by combining Role-Based Similarity (RBS) and Markov Stability, two
techniques based on flows. First we compute the RBS matrix, which contains the
pairwise similarities between nodes according to the scaled number of in- and
out-directed paths of different lengths. The weighted RBS similarity matrix is
then transformed into an undirected similarity network using the Relaxed
Minimum-Spanning Tree (RMST) algorithm, which uses the geometric structure of
the RBS matrix to unblur the network, such that edges between nodes with high,
direct RBS are preserved. Finally, we partition the RMST similarity network
into role-communities of nodes at all scales using Markov Stability to find a
robust set of roles in the network. We showcase our framework through a
biological and a man-made network.


title: VisIt: Experiences with Sustainable Software

abstract:
  The success of the VisIt visualization system has been wholly dependent upon
the culture and practices of software development that have fostered its
welcome by users and embrace by developers and researchers. In the following
paper, we, the founding developers and designers of VisIt, summarize some of
the major efforts, both successful and unsuccessful, that we have undertaken in
the last thirteen years to foster community, encourage research, create a
sustainable open-source development model, measure impact, and support
production software. We also provide commentary about the career paths that our
development work has engendered.


title: Nonlocality in Homogeneous Superfluid Turbulence

abstract:
  Simulating superfluid turbulence using the localized induction approximation
in periodic bound- aries produces open-orbit vortices, which make superfluid
turbulence unsustainable. Calculating with the fully nonlocal Biot-Savart law
prevents the open-orbit state from forming, but also in- creases computation
time. We use a truncated Biot-Savart integral to investigate the effects of
nonlocality on homogeneous turbulence. We find that including the nonlocal
interaction up to the average intervortex spacing prevents this open-orbit
state from forming, yielding an accurate model of homogeneous superfluid
turbulence with less computation time.


title: Direct observation of dynamic charge stripes in La2-xSrxNiO4

abstract:
  The insulator-to-metal transition continues to be a challenging subject,
especially when electronic correlations are strong. In layered compounds, such
as La2-xSrxNiO4 and La2-xBaxCuO4, the doped charge carriers can segregate into
periodically-spaced charge stripes separating narrow domains of
antiferromagnetic order. Although there have been theoretical proposals of
dynamically fluctuating stripes, direct spectroscopic evidence of charge-stripe
fluctuations has been lacking. Here we report the detection of critical lattice
fluctuations, driven by charge-stripe correlations, in La2-xSrxNiO4 using
inelastic neutron scattering. This scattering is detected at large momentum
transfers where the magnetic form factor suppresses the spin fluctuation
signal. The lattice fluctuations associated with the dynamic charge stripes are
narrow in q and broad in energy. They are strongest near the charge stripe
melting temperature. Our results open the way towards the quantitative theory
of dynamic stripes and for directly detecting dynamical charge stripes in other
strongly-correlated systems, including high-temperature superconductors such as
La2-xSrxCuO4.


title: Bayesian Nonparametric Weighted Sampling Inference

abstract:
  It has historically been a challenge to perform Bayesian inference in a
design-based survey context. The present paper develops a Bayesian model for
sampling inference in the presence of inverse-probability weights. We use a
hierarchical approach in which we model the distribution of the weights of the
nonsampled units in the population and simultaneously include them as
predictors in a nonparametric Gaussian process regression. We use simulation
studies to evaluate the performance of our procedure and compare it to the
classical design-based estimator. We apply our method to the Fragile Family and
Child Wellbeing Study. Our studies find the Bayesian nonparametric finite
population estimator to be more robust than the classical design-based
estimator without loss in efficiency, which works because we induce
regularization for small cells and thus this is a way of automatically
smoothing the highly variable weights.


title:
Neutral pion cross section and spin asymmetries at intermediate
  pseudorapidity in polarized proton collisions at sqrt{s} = 200 GeV

abstract:
  The differential cross section and spin asymmetries for neutral pions
produced within the intermediate pseudorapidity range 0.8 < {\eta} < 2.0 in
polarized proton-proton collisions at sqrt{s} = 200 GeV are presented. Neutral
pions were detected using the endcap electromagnetic calorimeter in the STAR
detector at RHIC. The cross section was measured over a transverse momentum
range of 5 < p_T < 16 GeV/c and is found to be within the scale uncertainty of
a next-to-leading order perturbative QCD calculation. The longitudinal
double-spin asymmetry, A_LL, is measured in the same pseudorapidity range. This
quantity is sensitive to the gluonic contribution to the proton spin,
{\Delta}g(x), at low Bjorken-x (down to x approx 0.01), where it is less
constrained by measurements at central pseudorapidity. The measured A_LL is
consistent with model predictions. The parity-violating asymmetry, A_L, is also
measured and found to be consistent with zero. The transverse single-spin
asymmetry, A_N, is measured within a previously unexplored kinematic range in
Feynman-x and p_T. Such measurements may aid our understanding of the on-set
and kinematic dependence of the large asymmetries observed at more forward
pseudorapidity ({\eta} approx 3) and their underlying mechanisms. The A_N
results presented are consistent with a twist-3 model prediction of a small
asymmetry within the present kinematic range.


title: Applying computational complexity to the emergence of classicality

abstract:
  Can the computational complexity theory of computer science and mathematics
say something new about unresolved problems in quantum physics? Particularly,
can the P versus NP question in the computational complexity theory be a factor
in the elucidation of the emergency of classicality in quantum mechanics? The
paper compares two different ways of deriving classicality from the quantum
formalism resulted from two differing hypotheses regarding the P versus NP
question -- the approach of the quantum decoherence theory implying that P = NP
and the computational complexity approach which assumes that P is not equal to
NP.


title: Splitting tower and degree of tt-rings

abstract:
  After constructing a splitting tower for separable commutative ring objects
in tensor-triangulated categories, we define and study their degree.


title: Perverse Curves and Mirror Symmetry

abstract:
  This work establishes a subtle connection between mirror symmetry for
Calabi-Yau threefolds and that of curves of higher genus. The linking structure
is what we call a perverse curve. We show how to obtain such from Calabi-Yau
threefolds in the Batyrev mirror construction and prove that their Hodge
diamonds are related by the mirror duality.


title: Extinction of megafauna: How could the research get so wrong?

abstract:
  Published evidence for the human-mediated extinction of megafauna is examined
and is found to be unsubstantiated. It is shown that the claimed evidence is
not based on data describing the growth of human population but on the
fabricated data. However, even these fabricated data, which were claimed to
support the human-induced extinction of megafauna, contradict this claim. The
belief in the human-induced extinction of megafauna appears to be so strong
that even contradicting evidence based on the fabricated data is interpreted as
the evidence supporting this belief.


title:
nanoHUB.org: Experiences and Challenges in Software Sustainability for a
  Large Scientific Community

abstract:
  Managing and growing a successful cyberinfrastructure such as nanoHUB.org
presents a variety of opportunities and challenges, particularly in regard to
software. This position paper details a number of those issues and how we have
approached them.


title:
Software Engineering as Instrumentation for the Long Tail of Scientific
  Software

abstract:
  The vast majority of the long tail of scientific software, the myriads of
tools that implement the many analysis and visualization methods for different
scientific fields, is highly specialized, purpose-built for a research project,
and has to rely on community uptake and reuse for its continued development and
maintenance. Although uptake cannot be controlled over even guaranteed, some of
the key factors that influence whether new users or developers decide to adopt
an existing tool or start a new one are about how easy or difficult it is to
use or enhance a tool for a purpose for which it was not originally designed.
The science of software engineering has produced techniques and practices that
would reduce or remove a variety of barriers to community uptake of software,
but for a variety of reasons employing trained software engineers as part of
the development of long tail scientific software has proven to be challenging.
As a consequence, community uptake of long tail tools is often far more
difficult than it would need to be, even though opportunities for reuse abound.
We discuss likely reasons why employing software engineering in the long tail
is challenging, and propose that many of those obstacles could be addressed in
the form of a cross-cutting non-profit center of excellence that makes software
engineering broadly accessible as a shared service, conceptually and in its
effect similar to shared instrumentation.


title: Aggregate-Max Nearest Neighbor Searching in the Plane

abstract:
  We study the aggregate/group nearest neighbor searching for the MAX operator
in the plane. For a set $P$ of $n$ points and a query set $Q$ of $m$ points,
the query asks for a point of $P$ whose maximum distance to the points in $Q$
is minimized. We present data structures for answering such queries for both
$L_1$ and $L_2$ distance measures. Previously, only heuristic and approximation
algorithms were given for both versions. For the $L_1$ version, we build a data
structure of O(n) size in $O(n\log n)$ time, such that each query can be
answered in $O(m+\log n)$ time. For the $L_2$ version, we build a data
structure in $O(n\log n)$ time and $O(n\log \log n)$ space, such that each
query can be answered in $O(m\sqrt{n}\log^{O(1)} n)$ time, and alternatively,
we build a data structure in $O(n^{2+\epsilon})$ time and space for any
$\epsilon>0$, such that each query can be answered in $O(m\log n)$ time.
Further, we extend our result for the $L_1$ version to the top-$k$ queries
where each query asks for the $k$ points of $P$ whose maximum distances to $Q$
are the smallest for any $k$ with $1\leq k\leq n$: We build a data structure of
O(n) size in $O(n\log n)$ time, such that each top-$k$ query can be answered in
$O(m+k\log n)$ time.


title:
Separable extensions in tensor-triangular geometry and generalized
  Quillen stratification

abstract:
  We study the continuous map induced on spectra by a separable extension of
tensor-triangulated categories. We determine the image of this map and relate
the cardinality of its fibers to the degree of the extension. We then prove a
weak form of descent, "up-to-nilpotence", which allows us to generalize
Quillen's Stratification Theorem to equivariant derived categories.


title: Overlapping Domain Decomposition Methods for Linear Inverse Problems

abstract:
  We shall derive and propose several efficient overlapping domain
decomposition methods for solving some typical linear inverse problems,
including the identiffication of the flux, the source strength and the initial
temperature in second order elliptic and parabolic systems. The methods are
iterative, and computationally very efficient: only local forward and adjoint
problems need to be solved in each subdomain, and the local minimizations have
explicit solutions. Numerical experiments are provided to demonstrate the
robustness and efficiency of the methods, in particular, the convergences seem
nearly optimal, i.e., they do not deteriorate or deteriorate only slightly when
the mesh size reduces.


title: Niche Modeling: Ecological Metaphors for Sustainable Software in Science

abstract:
  This position paper is aimed at providing some history and provocations for
the use of an ecological metaphor to describe software development
environments. We do not claim that the ecological metaphor is the best or only
way of looking at software - rather we want to ask if it can indeed be a
productive and thought provoking one.


title: Context Aware Sensor Configuration Model for Internet of Things

abstract:
  We propose a Context Aware Sensor Configuration Model (CASCoM) to address the
challenge of automated context-aware configuration of filtering, fusion, and
reasoning mechanisms in IoT middleware according to the problems at hand. We
incorporate semantic technologies in solving the above challenges.


title: Cactus: Issues for Sustainable Simulation Software

abstract:
  The Cactus Framework is an open-source, modular, portable programming
environment for the collaborative development and deployment of scientific
applications using high-performance computing. Its roots reach back to 1996 at
the National Center for Supercomputer Applications and the Albert Einstein
Institute in Germany, where its development jumpstarted. Since then, the Cactus
framework has witnessed major changes in hardware infrastructure as well as its
own community. This paper describes its endurance through these past changes
and, drawing upon lessons from its past, also discusses future


title:
Reusability in Science: From Initial User Engagement to Dissemination of
  Results

abstract:
  Effective use of parallel and distributed computing in science depends upon
multiple interdependent entities and activities that form an ecosystem. Active
engagement between application users and technology catalysts is a crucial
activity that forms an integral part of this ecosystem. Technology catalysts
play a crucial role benefiting communities beyond a single user group. An
effective user-engagement, use and reuse of tools and techniques has a broad
impact on software sustainability. From our experience, we sketch a life-cycle
for user-engagement activity in scientific computational environment and posit
that application level reusability promotes software sustainability. We
describe our experience in engaging two user groups from different scientific
domains reusing a common software and configuration on different computational
infrastructures.


title: Stability of Branched Flow from a Quantum Point Contact

abstract:
  In classically chaotic systems, small differences in initial conditions are
exponentially magnified over time. However, it was observed experimentally that
the (necessarily quantum) "branched flow" pattern of electron flux from a
quantum point contact (QPC) traveling over a random background potential in
two-dimensional electron gases(2DEGs) remains substantially invariant to large
changes in initial conditions. Since such a potential is classically chaotic
and unstable to changes in initial conditions, it was conjectured that the
origin of the observed stability is purely quantum mechanical, with no
classical analog. In this paper, we show that the observed stability is a
result of the physics of the QPC and the nature of the experiment. We show that
the same stability can indeed be reproduced classically, or quantum
mechanically. In addition, we explore the stability of the branched flow with
regards to changes in the eigenmodes of quantum point contact.


title: Information Sharing in Networks of Strategic Agents

abstract:
  To ensure that social networks (e.g. opinion consensus, cooperative
estimation, distributed learning and adaptation etc.) proliferate and
efficiently operate, the participating agents need to collaborate with each
other by repeatedly sharing information. However, sharing information is often
costly for the agents while resulting in no direct immediate benefit for them.
Hence, lacking incentives to collaborate, strategic agents who aim to maximize
their own individual utilities will withhold rather than share information,
leading to inefficient operation or even collapse of networks. In this paper,
we develop a systematic framework for designing distributed rating protocols
aimed at incentivizing the strategic agents to collaborate with each other by
sharing information. The proposed incentive protocols exploit the ongoing
nature of the agents' interactions to assign ratings and through them,
determine future rewards and punishments: agents that have behaved as directed
enjoy high ratings -- and hence greater future access to the information of
others; agents that have not behaved as directed enjoy low ratings -- and hence
less future access to the information of others. Unlike existing rating
protocols, the proposed protocol operates in a distributed manner, online, and
takes into consideration the underlying interconnectivity of agents as well as
their heterogeneity. We prove that in many deployment scenarios the price of
anarchy (PoA) obtained by adopting the proposed rating protocols is one. In
settings in which the PoA is larger than one, we show that the proposed rating
protocol still significantly outperforms existing incentive mechanisms such as
Tit-for-Tat. Importantly, the proposed rating protocols can also operate
efficiently in deployment scenarios where the strategic agents interact over
time-varying network topologies where new agents join the network over time.


title:
Fermion in a multi-kink-antikink soliton background, and exotic
  supersymmetry

abstract:
  We construct a fermion system in a multi-kink-antikink soliton background,
and present in an explicit form all its trapped configurations (bound state
solutions) as well as scattering states. This is achieved by exploiting an
exotic N=4 centrally extended nonlinear supersymmetry of completely isospectral
pairs of reflectionless Schrodinger systems with potentials to be n-soliton
solutions for the Korteweg-de Vries equation. The obtained reflectionless Dirac
system with a position-dependent mass is shown to possess its own exotic
nonlinear supersymmetry associated with the matrix Lax-Novikov operator being a
Darboux-dressed momentum. In the process, we get an algebraic recursive
representation for the multi-kink-antikink backgrounds, and establish their
relation to the the modified Korteweg-de Vries equation. We also indicate how
the results can be related to the physics of self-consistent condensates based
on the Bogoliubov-de Gennes equations.


title:
Initial Findings from a Study of Best Practices and Models for
  Cyberinfrastructure Software Sustainability

abstract:
  We present a set of common themes and recommendations extracted from in depth
interviews with the leaders of 12 distinct cyberinfrastructure software
projects. These interviews were conducted as part of a larger study to identify
and elucidate the best practices and management models that lead to
sustainability for cyberinfrastructure software. Respondents in a formal survey
of cyberinfrastructure users identified these projects as good examples of
sustained software initiatives. While there is clearly no single method or plan
that will guarantee sustainability for all projects, we can draw general
guidance from these exemplars. This paper presents the common themes, ideas,
and recommendations that emerged from those interviews.


title:
Error-Rate Performance Analysis of Wireless Sensor Networks over Fading
  Channels

abstract:
  In this paper, we analyze the bit-error-rate (BER) performance of wireless
sensor networks. A wireless sensor node with a single transmitter antenna and
multiple receiver antennas is considered here. We consider M (M greater or
equal ro 1) receiver antennas to mitigate channel fading effects. BER
performance is analyzed in the presence of a co-channel interference source.
Wireless channel is assumed to follow independently Nakagami fading for the
wireless sensor network and Rayleigh fading for the interference signal. Based
on the derived analytical expressions, the effects of different fading channel
and co-channel interference parameters on the BER performance of wireless
sensor networks are assessed.


title:
TCO Nanostructures as building blocks for nanophotonic devices in the
  infrared

abstract:
  Transparent conducting oxides (TCOs), in general, are degenerated
semiconductors with large electronic band-gap. They have been widely used for
display screens, optoelectronic, photonic, and photovoltaic devices due to
their unique dual transparent and conductive properties. In this study, we
report in detail a technique that we developed to fabricate single crystal TCO
nanorod arrays with controlled conductivity, height, and lattice spacing in a
simple one-zone tube furnace system. We demonstrate how novel
photonic/plasmonic properties can be obtained by selecting unique combinations
of these basic parameters of the nano-rod arrays.


title:
Is the Sunyaev-Zeldovich effect responsible for the observed steepening
  in the spectrum of the Coma radio halo ?

abstract:
  The spectrum of the radio halo in the Coma cluster is measured over almost
two decades in frequency. The current radio data show a steepening of the
spectrum at higher frequencies, which has implications for models of the radio
halo origin. There is an on-going debate on the possibility that the observed
steepening is not intrinsic to the emitted radiation, but is instead caused by
the SZ effect. Recently, the Planck satellite measured the SZ signal and its
spatial distribution in the Coma cluster allowing to test this hypothesis.
Using the Planck results, we calculated the modification of the radio halo
spectrum by the SZ effect in three different ways. With the first two methods
we measured the SZ-decrement within the aperture radii used for flux
measurements of the halo at the different frequencies. First we adopted the
global compilation of data from Thierbach et al. and a reference aperture
radius consistent with those used by the various authors. Second we used the
available brightness profiles of the halo at different frequencies to derive
the spectrum within two fixed apertures, and derived the SZ-decrement using
these apertures. As a third method we used the quasi-linear correlation between
the y and the radio-halo brightness at 330 MHz discovered by Planck to derive
the modification of the radio spectrum by the SZ-decrement in a way that is
almost independent of the adopted aperture radius. We found that the spectral
modification induced by the SZ-decrement is 4-5 times smaller than that
necessary to explain the observed steepening. Consequently a break or cut-off
in the spectrum of the emitting electrons is necessary to explain current data.
We also show that, if a steepening is absent from the emitted spectrum, future
deep observations at 5 GHz with single dishes are expected to measure a halo
flux in a 40 arcmin radius that would be 7-8 times higher than currently seen.


title: The classification of ACM line bundles on quartic hypersurfaces on P^3

abstract:
  In this paper, we give a complete classification of initialized and ACM line
bundles on a smooth quartic hypersurface on P^3$.


title: Rational representations of the Yangian Y(gl_n)

abstract:
  We construct a series of rational representations of Y(gl_n) and intertwining
operators between them. We find explicit expressions for the images of
highest-weight vectors under the intertwining operators. Finally, we state a
conjecture that all irreducible finite-dimensional rational Y(gl_n)-modules
arise as images of the constructed intertwining operators.


title: On Limits to the Scope of the Extended Formulations "Barriers"

abstract:
  In this paper, we introduce the notion of augmentation for polytopes and use
it to show the error in two presumptions that have been key in arriving at
over-reaching/over-scoped claims of "impossibility" in recent extended
formulations (EF) developments. One of these presumptions is that: "If
Polytopes P and Q are described in the spaces of variables x and y
respectively, and there exists a linear map x=Ay between the feasible sets of P
and Q, then Q is an EF of P". The other is: "(An augmentation of Polytope A
projects to Polytope B) ==> (The external descriptions of A and B are
related)". We provide counter-examples to these presumptions, and show that in
general: (1) If polytopes can always be arbitrarily augmented for the purpose
of establishing EF relations, then the notion of EF becomes
degenerate/meaningless in some cases, and that: (2) The statement: "(Polytope B
is the projection of an augmentation of Polytope A) ==> (Polytope B is the
projection of Polytope A)" is not true in general (although, as we show, the
converse statement, "(B is the projection of A) ==> (B is the projection of
every augmentation of A)", is true in general). We illustrate some of the ideas
using the minimum spanning tree problem, as well as the "lower bounds"
developments in Fiorini et al. (2011; 2012), in particular.


title:
Use of approximations of Hamilton-Jacobi-Bellman inequality for solving
  periodic optimization problems

abstract:
  We show that necessary and sufficient conditions of optimality in periodic
optimization problems can be stated in terms of a solution of the corresponding
HJB inequality, the latter being equivalent to a max-min type variational
problem considered on the space of continuously differentiable functions. We
approximate the latter with a maximin problem on a finite dimensional subspace
of the space of continuously differentiable functions and show that a solution
of this problem (existing under natural controllability conditions) can be used
for construction of near optimal controls. We illustrate the construction with
a numerical example.


title: Social Interactive Media Tools and Knowledge Sharing: A Case Study

abstract:
  Purpose: Social Media Tools (SMT) have provided new opportunities for
libraries and librarians in the world. In academic libraries, we can use of
them as a powerful tool for communication. This study is to determine the use
of the social interactive media tools [Social Networking Tools (SNT), Social
Bookmarking Tools (SBT), Image or Video Sharing Tools (IVShT), and Mashup Tools
(MT)] in disseminating knowledge and information among librarians in the
Limerick University, Ireland. Methodology: The study was a descriptive survey.
The research population included all librarians in Glucksman library. A
questionnaire survey was done to collect data. Statistical software, SPSS16 was
used at two levels (descriptive and inferential statistics) for data analyzing.
Findings: The findings show that the mean (out of 5.00) of using each of SMT in
sharing knowledge by the librarians of Glucksman library is as the following:
SNT (2.49), SBT (2.92), IVShT (2.99) and MT (2.5). It shows that most of their
interaction related to share of image or video. Originality: SMT provides an
excellent platform for the exchange information between students, faculty
members, and the librarians themselves. The Glucksman library at the University
of Limerick is using this technology. This paper gives an example of how using
these tools in the field of Library and Information Science in Ireland. The
issues expressed could be beneficial for the development of library services in
general and knowledge sharing among librarians in particular.


title:
Equicontinuity and normality of mappings with integrally bounded
  $p$-moduli

abstract:
  We consider the generic discrete open mappings in ${\mathbb R}^n$ under which
the perturbation of extremal lengths of curve collections is controlled
integrally via $\int Q(x)\eta^p(|x-x_0|) dm(x)$ with $n-1<p<n$, where $Q$ is a
measurable function on ${\mathbb R}^n$ and $\int\limits_{r_1}^{r_2} \eta(r) dr
\ge 1$ for any $\eta$ on a given interval $[r_1,r_2].$ We proved that the
family of all open discrete mappings of above type is normal under appropriate
restrictions on the majorant $Q.$


title:
Towards reconstruction of unlensed, intrinsic CMB power spectra from
  lensed map

abstract:
  We propose a method to extract the unlensed, intrinsic CMB temperature and
polarization power spectra from the observed (i.e., lensed) spectra. Using a
matrix inversion technique, we demonstrate how one can reconstruct the
intrinsic CMB power spectra directly from lensed data for both flat sky and
full sky analyses. The delensed spectra obtained by the technique are
calibrated against the Code for Anisotropies in the Microwave Background (CAMB)
using WMAP 7-year best-fit data and applied to WMAP 9-year unbinned data as
well. In principle, our methodology may help in subtracting out the E-mode
lensing contribution in order to obtain the intrinsic B-mode power.