title:
Model and Visualization of Ray Tracing using JavaScript and HTML5 for
  TIR Measurement System Equipped with Equilateral Right Angle Prism

abstract:
  Trace of ray deviated by a prism, which is common in a TIR (total internal
reflection) measurement system, is sometimes difficult to manage, especially if
the prism is an equilateral right angle prism (ERAP). The point where the ray
is reflected inside the right-angle prism is also changed as the angle of
incident ray changed. In an ATR (attenuated total reflectance) measurement
system, range of this point determines size of sample. Using JavaScript and
HTML5 model and visualization of ray tracing deviated by an ERAP is perform and
reported in this work. Some data are obtained from this visualization and an
empirical relations between angle of incident ray source \theta_S, angle of ray
detector hand \theta_D, and angle of ray detector \theta'_D are presented for
radial position of ray source R_S, radial position of ray detector R_D, height
of right-angle prism t, and refractive index of the prism n. Keywords:
deviation angle, equilateral right angle prism, total internal reflection,
JavaScript, HTML5.


title: E_n Genera

abstract:
  Let R be an E_2 ring spectrum with zero odd dimensional homotopy groups.
Every map of ring spectra MU to R is represented by a map of E_2 ring spectra.
If 2 is invertible in pi_0(R), then every map of ring spectra MSO to R is
represented by a map of E_2 ring spectra.


title:
Observation of magnetic field generation via the Weibel instability in
  interpenetrating plasma flows

abstract:
  Collisionless shocks can be produced as a result of strong magnetic fields in
a plasma flow, and therefore are common in many astrophysical systems. The
Weibel instability is one candidate mechanism for the generation of
sufficiently strong fields to create a collisionless shock. Despite their
crucial role in astrophysical systems, observation of the magnetic fields
produced by Weibel instabilities in experiments has been challenging. Using a
proton probe to directly image electromagnetic fields, we present evidence of
Weibel-generated magnetic fields that grow in opposing, initially unmagnetized
plasma flows from laser-driven laboratory experiments. Three-dimensional
particle-in-cell simulations reveal that the instability efficiently extracts
energy from the plasma flows, and that the self-generated magnetic energy
reaches a few percent of the total energy in the system. This result
demonstrates an experimental platform suitable for the investigation of a wide
range of astrophysical phenomena, including collisionless shock formation in
supernova remnants, large-scale magnetic field amplification, and the radiation
signature from gamma-ray bursts.


title: Quantum Nucleodynamics

abstract:
  The core ideas underlying a quantitative, bottom-up theory of nuclear
structure, i.e., quantum nucleodynamics, are introduced. The replacement of the
fictitious "mean-field" approximation of the nuclear force with the
empirically-known nuclear potential-well is the essential first step. From
there, calculation of short-range nucleon-nucleon effects can be achieved on
the basis of a unique lattice representation of nuclear quantum space, as
introduced by Wigner in 1937. The lattice reproduces all of the n-shells and j-
and m-subshells of the well-established independent-particle model on a
geometrical basis, and represents a return to a comprehensible,
coordinate-space depiction of the atomic nucleus. Multiple regression results
for the binding energies of 273 stable isotopes using 1st-3rd neighbor
interactions in the lattice are presented as "in principle" demonstration of
the utility of the nuclear lattice. Noteworthy is the fact that all
near-neighbor nuclear binding effects fall between -1.2 and 3.0 MeV.


title: Weak Gravitational Lensing Systematics from Image Combination

abstract:
  Extremely accurate shape measurements of galaxy images are needed to probe
dark energy properties with weak gravitational lensing surveys. To increase
survey area with a fixed observing time and pixel count, images from surveys
such as the Wide Field Infrared Survey Telescope (WFIRST) or Euclid will
necessarily be undersampled and therefore distorted by aliasing. Oversampled,
unaliased images can be obtained by combining multiple, dithered exposures of
the same source with a suitable reconstruction algorithm. Any such
reconstruction must minimally distort the reconstructed images for weak lensing
analyses to be unbiased. In this paper, we use the IMage COMbination (IMCOM)
algorithm of Rowe, Hirata, and Rhodes to investigate the effect of image
combination on shape measurements (size and ellipticity). We simulate dithered
images of sources with varying amounts of ellipticity and undersampling,
reconstruct oversampled output images from them using IMCOM, and measure shape
distortions in the output. Our simulations show that IMCOM creates no
significant distortions when the relative offsets between dithered images are
precisely known. Distortions increase with the uncertainty in those offsets but
become problematic only with relatively poor astrometric precision. E.g. for
images similar to those from the Astrophysics Focused Telescope Asset (AFTA)
implementation of WFIRST, combining eight undersampled images (sampling ratio
Q=1) with highly pessimistic uncertainty in astrometric registration
(\sigma_d~10^{-3} pixels) yields an RMS shear error of O(10^{-4}). Our analysis
pipeline is adapted from that of the Precision Projector Laboratory -- a joint
project between NASA Jet Propulsion Laboratory and Caltech which characterizes
image sensors using laboratory emulations of astronomical data.


title:
Application of matrix product states to the Hubbard model in one spatial
  dimension

abstract:
  We investigate the application of matrix product states to the Hubbard model
in one spatial dimension with both of open and periodic boundary conditions. We
develop the variatinal method that the optimization of the variational
parameters is carried out locally and sequentially in the framework of matrix
product operators (MPO) by including the sign, due to the anti-commutation
relation of fermion operators, in the matrix element of MPO. The numerical
accuracy of the ground state energy is examined.


title:
Exact Algorithm for Graph Homomorphism and Locally Injective Graph
  Homomorphism

abstract:
  For graphs $G$ and $H$, a homomorphism from $G$ to $H$ is a function $\varphi
\colon V(G) \to V(H)$, which maps vertices adjacent in $G$ to adjacent vertices
of $H$. A homomorphism is locally injective if no two vertices with a common
neighbor are mapped to a single vertex in $H$. Many cases of graph homomorphism
and locally injective graph homomorphism are NP-complete, so there is little
hope to design polynomial-time algorithms for them. In this paper we present an
algorithm for graph homomorphism and locally injective homomorphism working in
time $\mathcal{O}^*((b + 2)^{|V(G)|})$, where $b$ is the bandwidth of the
complement of $H$.


title: Water in Protoplanetary Disks: Deuteration and Turbulent Mixing

abstract:
  We investigate water and deuterated water chemistry in turbulent
protoplanetary disks. Chemical rate equations are solved with the diffusion
term, mimicking turbulent mixing in vertical direction. Water near the midplane
is transported to the disk atmosphere by turbulence and destroyed by
photoreactions to produce atomic oxygen, while the atomic oxygen is transported
to the midplane and reforms water and/or other molecules. We find that this
cycle significantly decreases column densities of water ice at r < 30 AU, where
dust temperatures are too high to reform water ice effectively. The radial
extent of such region depends on the desorption energy of atomic hydrogen. Our
model indicates that water ice could be deficient even outside the sublimation
radius. Outside this radius, the cycle decreases the D/H ratio of water ice
from 2x10^-2, which is set by the collapsing core model, to 10^-4-10^-2 in 10^6
yr, without significantly decreasing the water ice column density. The
resultant D/H ratios depend on the strength of mixing and the radial distance
from the central star. Our finding suggests that the D/H ratio of cometary
water (10^-3-10^-4) could be established (i.e. cometary water could be formed)
in the solar nebula, even if the D/H ratio of water ice delivered to the disk
was very high (10^-2).


title: Complex Structure of Dynamic Stall on Wind Turbine Airfoils

abstract:
  Fluid dynamics video demonstrating the evolution of dynamic stall on a wind
turbine blade.


title: A paradox about an atom and a photon

abstract:
  In this article we propose a new relativistic paradox concerning the
absorption of a photon by a hydrogen atom. We show that the actual cause of the
paradox is one of the hypotheses of Bohr model; therefore, in order to solve
the paradox, we have to move away from Bohr model. Our analysis is carried out
only in the special relativistic framework, so we are not interested in giving
a full quantum mechanical treatment of the problem. We derive some expressions
for emission and absorption of photons by atoms, which are in perfect agreement
with special relativity, although comparable to the classical Bohr formula with
an excellent degree of approximation. Quite interestingly, these expressions
are no more invariant under a global shift of energy levels, showing a breaking
of classical "gauge invariance" of energy. We stress that, to the best of our
knowledge, the present approach has never been considered in literature. At the
end we will be able to solve the proposed paradox.


title: Linear ODEs, Wronskians and Schubert Calculus

abstract:
  For a linear ODE with indeterminate coefficients, we explicitly exhibit a
fundamental system of solutions, in terms of the coefficients. We show that the
generalized Wronskians of the fundamental system are given by an action of the
Schur functions on the usual Wronskian, and thence enjoy Pieri's and
Giambelli's formulae. As an outcome, we obtain a natural isomorphism between
the free module generated by the generalized Wronskians and the singular
homology module of the Grassmannian.


title:
Multiplicity-free primitive ideals associated with rigid nilpotent
  orbits

abstract:
  We prove that any finite W-algebra U(g,e) admits a one-dimensional
representation fixed by the action of the component group of the centraliser of
e. As a consequence, for any nilpotent orbit O in g there exists a
multiplicity-free (and hence completely prime) primitive ideal of the universal
enveloping algebra U(g) whose associated variety coincides with the Zariski
closure of O.


title: Order Estimates for the Exact Lugannani-Rice Expansion

abstract:
  The Lugannani-Rice formula is a saddlepoint approximation method for
estimating the tail probability distribution function, which was originally
studied for the sum of independent identically distributed random variables.
Because of its tractability, the formula is now widely used in practical
financial engineering as an approximation formula for the distribution of a
(single) random variable. In this paper, the Lugannani-Rice approximation
formula is derived for a general, parametrized sequence of random variables and
the order estimates of the approximation are given.


title:
125 GeV Higgs Boson and TeV Scale Colored Fermions in Gauge-Higgs
  Unification

abstract:
  In the context of a simple gauge-Higgs unification scenario based on the
gauge group SU(3) times U(1)' in a 5-dimensional flat spacetime, we investigate
a possibility to realize the Higgs boson mass of 125 GeV with a
compactification scale at the TeV. With the introduction of colored bulk
fermions in a certain representation under the gauge group with a half-periodic
boundary condition, we analyze the one-loop RGE of the Higgs quartic coupling
with the gauge-Higgs condition and successfully obtain 125 GeV Higgs boson mass
by adjusting a bulk mass for the fermions with a fixed compactification scale.
The Kaluza-Klein modes of the colored fermions contribute to the
Higgs-to-digluon effective coupling through the one-loop corrections. Since the
contribution is destructive to the Standard Model one and reduces the Higgs
boson production cross section, the recent LHC result gives a lower bound on
the mass of the lightest Kaluza-Klein mode fermion. We find the mass of the
lightest Kaluza-Klein mode fermion in the range of 2-3 TeV for 10%-5%
reductions of the Higgs boson production cross section through the gluon fusion
channel. Such Kaluza-Klein mode fermions can be discovered at the LHC run II
with sqrt{s}=13-14 TeV, and LHC phenomenology for the Kaluza-Klein fermions is
briefly discussed.


title: Discovery of an Outstanding Disk in the cD Galaxy of the Hydra A Cluster

abstract:
  The central cD galaxy of the Hydra A cluster has one of the most powerful
active galactic nuclei (AGNs) in the nearby Universe (z <0.2). We report on the
discovery of a dust lane in the cD galaxy using Subaru telescope. The i'-band
image shows the existence of a dark band of the size of 3.6"x 0.7" (4 kpc x 0.8
kpc), which appears to be quite similar to the dust lane observed in Centaurus
A. The morphology indicates that the cold disk that seen as the dust lane is
almost edge-on and rotates around the AGN. Since the minor axis of the dust
lane is nearly parallel to the radio jets emerging from the AGN, the disk is
probably feeding its gas into the central black hole. From the absorption, we
estimate the hydrogen column density of the lane is N_H=2.0 x 10^21 cm^-2, and
the mass of the disk is ~8 x 10^7 M_sun. The column density is consistent with
constraints obtained from Chandra X-ray observations. The age of the disk is >~
4 x 10^7 yr. The position angle of the disk and the galaxy's photometric axis
are misaligned, which may imply that the cold gas in the disk is brought via
galaxy mergers. Our observations may indicate that the supply of cold gas by
galaxy mergers is required for the most intensive feedback from AGNs.


title: Thermoelectric properties of an ultra-thin topological insulator

abstract:
  Thermoelectric coefficients of an ultra-thin topological insulator are
presented here. The hybridization between top and bottom surface states of a
topological insulator plays a significant role. In absence of magnetic field,
thermopower increases and thermal conductivity decreases with increase of the
hybridization energy. In presence of magnetic field perpendicular to the
ultra-thin topological insulator, thermoelectric coefficients exhibit quantum
oscillations with inverse magnetic field, whose frequency is strongly modified
by the Zeeman energy and phase factor is governed by the product of the Lande
g-factor and the hybridization energy. In addition to the numerical results,
the low-temperature approximate analytical results of the thermoelectric
coefficients are also provided. It is also observed that for a given magnetic
field these transport coefficients oscillate with hybridization energy, whose
frequency depends on the Lande g-factor.


title: An MDS code associated to an elliptic curve

abstract:
  We will construct an MDS(= the most distance separable) code $C$ which admits
a decomposition such that every factor is still MDS. An effective way of
decoding will be also discussed.


title: On weighted norm inequalities for the Carleson operator

abstract:
  We obtain $L^p(w)$ bounds for the Carleson operator ${\mathcal C}$ in terms
of the $A_q$ constants $[w]_{A_q}$ for $1\le q\le p$. In particular, we show
that, exactly as for the Hilbert transform, $\|{\mathcal C}\|_{L^p(w)}$ is
bounded linearly by $[w]_{A_q}$ for $1\le q<p$. Our approach works in the
general context of maximally modulated Calder\'on-Zygmung operators.


title: Next Generation Cluster Editing

abstract:
  This work aims at improving the quality of structural variant prediction from
the mapped reads of a sequenced genome. We suggest a new model based on cluster
editing in weighted graphs and introduce a new heuristic algorithm that allows
to solve this problem quickly and with a good approximation on the huge graphs
that arise from biological datasets.


title:
Spin diffusion and magnetoresistance in
  ferromagnet/topological-insulator junctions

abstract:
  We study spin and charge diffusion in
metallic-ferromagnet/topological-insulator junctions. The coupled diffusion
equations are derived perturbatively with respect to the strength of the
interlayer tunneling. We calculate spin accumulation in the ferromagnet and
junction magnetoresistance associated with a current bias along the interface.


title:
CITIUS: an IR-XUV light source for fundamental and applied ultrafast
  science

abstract:
  We present the main features of CITIUS, a new light source for ultrafast
science, generating tunable, intense, femtosecond pulses in the spectral range
from IR to XUV. The XUV pulses (about 10^5-10^8 photons/pulse in the range
14-80 eV) are produced by laser-induced high-order harmonic generation in gas.
This radiation is monochromatized by a time-preserving monochromator, allowing
also to work with high-resolution bandwidth selection. The tunable IR-UV pulses
(10^{12}-10^{15} photons/pulse in the range 0.4-5.6 eV) are generated by an
optical parametric amplifier, which is driven by a fraction of the same laser
pulse that generates high order harmonics. The IR-UV and XUV pulses follow
different optical paths and are eventually recombined on the sample for
pump-probe experiments. The new light source will become the fulcrum of a new
center located at the University of Nova Gorica, active in a wide range of
scientific fields, including materials science, catalysis, biochemistry and
magnetism. We also present the results of two pump-probe experiments: with the
first one, we fully characterized the temporal duration of harmonic pulses in
the time-preserving configuration; with the second one, we demonstrated the
possibility of using CITIUS for studying of ultra-fast dynamics.


title:
A Novel Reconfigurable Computing Architecture for Image Signal
  Processing Using Circuit-Switched NoC and Synchronous Dataflow Model

abstract:
  In this paper, a novel reconfigurable architecture is proposed for
multifunctional image signal processing systems. A circuit-switched NoC is used
to provide interconnection because the non-TMD links ensure fixed throughput,
which is a desirable behavior for computational intensive image processing
algorithms compared with packet-switched NoC. Image processing algorithms are
modeled as synchronous dataflow graphs which provide a unified model for
general computing procedure. An image processing system is considered as
several temporally mutually exclusive algorithms. Thus, their dataflow graph
representations could be considered as a group and a merging algorithm could be
applied to generate a union graph while eliminating spatial redundancy for area
consumption optimization. After the union graph have been mapped and routed on
the NoC, the reconfigurable system could be configured to any of its target
image processing algorithms by properly setting the NoC topology. Experiments
show the demo reconfigurable system with two image processing applications cost
26.4% less hardware resource, compared with the non-reconfigurable
implementations.


title: Numerical resolution of algebraic equations with symmetries

abstract:
  Studied here is the effect of the presence of symmetry groups in a system of
algebraic equations on the numerical resolution with fixed-point algorithms. It
is proved that the symmetries imply two important properties of the system: the
solutions are not isolated, but distributed in orbits by the symmetry group and
zero is an eigenvalue of the Jacobian evaluated at any of the solutions, being
the multiplicity at least the dimension of the symmetry group. From the point
of view of the numerical resolution, the concept of orbital convergence is
introduced and a corresponding convergence theorem is proved. This establishes
the conditions under which a fixed-point algorithm converges to some element of
the orbit of a solution of the system. Two numerical examples illustrate these
results.


title:
A Kalman Filtering approach of improved precision for fault diagnosis in
  distributed parameter systems

abstract:
  The Derivative-free nonlinear Kalman Filter is proposed for state estimation
and fault diagnosis in distributed parameter systems and particularly in
dynamical systems described by partial differential equations of the nonlinear
wave type. At a first stage, a nonlinear filtering approach for estimating the
dynamics of a 1D nonlinear wave equation, from measurements provided from a
small number of sensors is developed. It is shown that the numerical solution
of the associated partial differential equation results into a set of nonlinear
ordinary differential equations. With the application of diffeomorphism that is
based on differential flatness theory it is shown that an equivalent
description of the system is obtained in the linear canonical (Brunovsky) form.
This transformation enables to obtain local estimates about the state vector of
the system through the application of the standard Kalman Filter recursion. At
a second stage, the local statistical approach to fault diagnosis is used to
perform fault diagnosis for the distributed parameters system by processing
with elaborated statistical tools the differences (residuals) between the
output of the Kalman Filter and the measurements obtained from the distributed
parameter system. Optimal selection of the fault threshold is succeeded by
using the local statistical approach to fault diagnosis. The efficiency of the
proposed filtering approach for performing fault diagnosis in distributed
parameters systems is confirmed through simulation experiments.


title: On normal subgroups of compact groups

abstract:
  Among compact Hausdorff groups G whose maximal profinite quotient is finitely
generated, we characterize those that possess a proper dense normal subgroup.
We also prove that the abstract commutator subgroup [H,G] is closed for every
closed normal subgroup H of G.


title: A Probabilistic Approach to Risk Mapping for Mt. Etna

abstract:
  We evaluate susceptibility to lava flows on Mt. Etna based on specially
designed die-toss experiments using probabilities for type, time and place of
activation from the volcano's 400-year recorded history and current studies on
its known fractures and fissures. The types of activations were forcast using a
table of probabilities for events, typed by duration and volume of ejecta.
Lengths of time were represented by the number of activations to expect within
a given time-frame, calculated assuming Poisson-distributed inter-arrival times
for activations. Locations of future activations were forecast with a
probability distribution function for activation probabilities. Most likely
scenarios for risk and resulting topography were generated for Etna's next
activation (average 7.76 years), the next 25, 50 and 100 years. Forecasts for
areas most likely affected are in good agreement with previous risk studies
made. Forecasts for risks of lava invasions, as well as future topographies
might be a first. Threats to lifelines are also discussed.


title:
Finite energy local well-posedness for the Yang-Mills-Higgs equations in
  Lorenz gauge

abstract:
  The Yang-Mills-Higgs equations (Y-M-H), when written relative to Lorenz
gauge, become a system of nonlinear wave equations. The key bilinear terms in
the resulting system turn out to be null forms--this is in light of a recent
discovery of null structure by Selberg and the present author for Yang-Mills
equations in Lorenz gauge. Using the null structure found and bilinear
space-time estimates, we prove local well-posedness of Y-M-H in Lorenz gauge
for finite energy data.


title: Deformation Operators of Spin Networks and Coarse-Graining

abstract:
  In the context of loop quantum gravity, quantum states of geometry are
mathematically defined as spin networks living on graphs embedded in the
canonical space-like hypersurface. In the effort to study the renormalisation
flow of loop gravity, a necessary step is to understand the coarse-graining of
these states in order to describe their relevant structure at various scales.
Using the spinor network formalism to describe the phase space of loop gravity
on a given graph, we focus on a bounded (connected) region of the graph and
coarse-grain it to a single vertex using a gauge-fixing procedure. We discuss
the ambiguities in the gauge-fixing procedure and their consequences for
coarse-graining spin(or) networks. This allows to define the boundary
deformations of that region in a gauge-invariant fashion and to identify the
area preserving deformations as U(N) transformations similarly to the already
well-studied case of a single intertwiner. The novelty is that the closure
constraint is now relaxed and the closure defect interpreted as a local measure
of the curvature inside the coarse-grained region. It is nevertheless possible
to cancel the closure defect by a Lorentz boost. We further identify a
Lorentz-invariant observable related to the area and closure defect, which we
name "rest area". Its physical meaning remains an open issue.


title:
Capacities, Measurable Selection and Dynamic Programming Part I:
  Abstract Framework

abstract:
  We give a brief presentation of the capacity theory and show how it derives
naturally a measurable selection theorem following the approach of Dellacherie
(1972). Then we present the classical method to prove the dynamic programming
of discrete time stochastic control problem, using measurable selection
arguments. At last, we propose a continuous time extension, that is an abstract
framework for the continuous time dynamic programming principle (DPP).


title:
Capacities, Measurable Selection and Dynamic Programming Part II:
  Application in Stochastic Control Problems

abstract:
  We aim to give an overview on how to derive the dynamic programming principle
for a general stochastic control/stopping problem, using measurable selection
techniques. By considering their martingale problem formulation, we show how to
check the required measurability conditions for different versions of
control/stopping problem, including in particular the controlled/stopped
diffusion processes problem. Further, we also study the stability of the
control problem, i.e. the approximation of the control process by piecewise
constant control problems. It induces in particular an equivalence result for
different versions of the controlled/stopped diffusion processes problem.


title: Electrohydrodynamically induced mixing in immiscible multilayer flows

abstract:
  In the present study we investigate electrostatic stabilization mechanisms
acting on stratified fluids. Electric fields have been shown to control and
even suppress the Rayleigh-Taylor instability when a heavy fluid lies above
lighter fluid. From a different perspective, similar techniques can also be
used to generate interfacial dynamics in otherwise stable systems. We aim to
identify active control protocols in confined geometries that induce time
dependent flows in small scale devices without having moving parts. This effect
has numerous applications, ranging from mixing phenomena to electric
lithography. Two-dimensional computations are carried out and several such
protocols are described. We present computational fluid dynamics videos with
different underlying mixing strategies, which show promising results.


title: PCG-Cut: Graph Driven Segmentation of the Prostate Central Gland

abstract:
  Prostate cancer is the most abundant cancer in men, with over 200,000
expected new cases and around 28,000 deaths in 2012 in the US alone. In this
study, the segmentation results for the prostate central gland (PCG) in MR
scans are presented. The aim of this research study is to apply a graph-based
algorithm to automated segmentation (i.e. delineation) of organ limits for the
prostate central gland. The ultimate goal is to apply automated segmentation
approach to facilitate efficient MR-guided biopsy and radiation treatment
planning. The automated segmentation algorithm used is graph-driven based on a
spherical template. Therefore, rays are sent through the surface points of a
polyhedron to sample the graph's nodes. After graph construction - which only
requires the center of the polyhedron defined by the user and located inside
the prostate center gland - the minimal cost closed set on the graph is
computed via a polynomial time s-t-cut, which results in the segmentation of
the prostate center gland's boundaries and volume. The algorithm has been
realized as a C++ modul within the medical research platform MeVisLab and the
ground truth of the central gland boundaries were manually extracted by
clinical experts (interventional radiologists) with several years of experience
in prostate treatment. For evaluation the automated segmentations of the
proposed scheme have been compared with the manual segmentations, yielding an
average Dice Similarity Coefficient (DSC) of 78.94 +/- 10.85%.


title:
Investigating the origin of cyclical spectral variations in hot, massive
  stars

abstract:
  OB stars are known to exhibit various types of wind variability, as detected
in their ultraviolet spectra, amongst which are the ubiquitous discrete
absorption components (DACs). These features have been associated with
large-scale azimuthal structures extending from the base of the wind to its
outer regions: corotating interaction regions (CIRs). There are several
competing hypotheses as to which physical processes may perturb the star's
surface and generate CIRs, including magnetic fields and non radial pulsations
(NRPs), the subjects of this paper with a particular emphasis on the former.
Although large-scale magnetic fields are ruled out, magnetic spots deserve
further investigation, both on the observational and theoretical fronts.


title:
Remarks on Blow-up of Smooth Solutions to the Compressible Fluid with
  Constant and Degenerate Viscosities

abstract:
  In this paper, we will show the blow-up of smooth solutions to the Cauchy
problem for the full compressible Navier-Stokes equations and isentropic
compressible Navier-Stokes equations with constant and degenerate viscosities
in arbitrary dimensions under some restrictions on the initial data. In
particular, the results hold true for the full compressible Euler equations and
isentropic compressible Euler equations and the blow-up time can be computed in
a more precise way. It is not required that the initial data has compact
support or contain vacuum in any finite regions. Moreover, a simplified and
unified proof on the blow-up results to the classical solutions of the full
compressible Navier-Stokes equations without heat conduction by Xin \cite{Xin}
and with heat conduction by Cho-Bin \cite{CJ} will be given.


title: Higher-order cauchy numbers and polynomials

abstract:
  Recently, Komatsu introduced the concept of poly-Cauchy numbers and
polynomials which generalize Cauchy numbers and polynomials. In this paper, we
consider the new concept of higher-order Cauchy numbers and polynomials which
generalize Cauchy numbers and polynomials in different direction and
investigate some properties of those new class of numbers and polynomials. From
our investigation, we derive some identities involving higher-order Cauchy
numbers and polynomials, which generalize some rela- tions between two kinds of
Cauchy polynomials and some identities for Cauchy numbers and Stirling numbers.


title:
Talking With Scholars: Developing a Research Environment for Oral
  History Collections

abstract:
  Scholars are yet to make optimal use of Oral History collections. For the
uptake of digital research tools in the daily working practice of researchers,
practices and conventions commonly adhered to in the subfields in the
humanities should be taken into account during development. To this end, in the
Oral History Today project a research tool for exploring Oral History
collections is developed in close collaboration with scholarly researchers.
This paper describes four stages of scholarly research and the first steps
undertaken to incorporate requirements of these stages in a digital research
environment.


title:
Unconventional magnetism in multivalent charge-ordered YbPtGe$_2$ probed
  by $^{195}$Pt- and $^{171}$Yb-NMR

abstract:
  Detailed $^{195}$Pt- and $^{171}$Yb nuclear magnetic resonance (NMR) studies
on the heterogeneous mixed valence system YbPtGe$_2$ are reported. The
temperature dependence of the $^{195}$Pt-NMR shift $^{195}K(T)$ indicates the
opening of an unusual magnetic gap below 200\,K. $^{195}K(T)$ was analyzed by a
thermal activation model which yields an isotropic gap $\Delta/k_B \approx
200$\,K. In contrast, the spin-lattice relaxation rate $^{195}$($1/T_1$) does
not provide evidence for the gap. Therefore, an intermediate-valence picture is
proposed while a Kondo-insulator scenario can be excluded. Moreover,
$^{195}$($1/T_1$) follows a simple metallic behavior, similar to the reference
compound YPtGe$_2$. A well resolved NMR line with small shift is assigned to
divalent $^{171}$Yb. This finding supports the proposed model with two sub-sets
of Yb species (di- and trivalent) located on the Yb2 and Yb1 site of the
YbPtGe$_2$ lattice.


title:
Absolutely continuous energy bands in the electronic spectrum of
  quasiperiodic ladder networks

abstract:
  The energy spectra of quasi-one dimensional quasiperiodic ladder networks are
analyzed within a tight binding description. In particular, we show that if a
selected set of sites in each strand of a ladder is tunnel-coupled to quantum
dots attached from a side, absolutely continuous subbands can be generated in
the spectrum if one tunes the dot potential and the dot-strand coupling
appropriately. Typical cases with two and three strand Fibonacci ladders in the
off diagonal model are discussed in details. We also discuss the possibility of
re-entrant insulator-metal transition for a general n-strand ladder network
when n becomes large. The observations remain valid even in the case of a
disordered ladder network with the same constituents. The results are
analytically exact.


title: MOND and its bimetric formulation

abstract:
  I first give a succinct account of the MOND paradigm--emphasizing the
centrality of scale invariance in the nonrelativistic, deep-MOND limit--and
describing rudiments of its phenomenology. I then present my credo, and some
generalities, concerning existing MOND theories. Then I concentrate on one
relativistic formulation of MOND in the form of a bimetric theory (BIMOND). I
describe its various limits: the weak field, with application to gravitational
waves, the nonrelativistic limit, and their further deep-MOND (low
acceleration) limits, which are scale invariant. Other aspects of BIMOND that
have been explored are aspects of cosmology, matter fluctuations in cosmology,
and matter-twin-matter interactions. BIMOND remains largely unexplored, despite
its promise in several regards: It tends to GR for a0 goes to 0 (a0 is the MOND
constant); it has a simple nonrelativistic limit; it describes gravitational
lensing correctly; and, it has a generic appearance of a cosmological-constant
term that is of order a0^2/c^4, as observed.


title:
Two Higgs doublet models for the LHC Higgs boson data at $\sqrt{s}=$ 7
  and 8 TeV

abstract:
  Updated LHC data on the new 126 GeV boson during the 7 and 8 TeV runnings
strengthen the standard model Higgs boson interpretation further. Through the
global $\chi^2$ analysis, we investigate whether the new particle could be one
of the scalar particles in two Higgs doublet models. Four types (Type I, II, X
and Y) are comprehensively studied. Taking the recent analysis on the
spin-parity of the new boson, we consider two scenarios: the new boson is
either the light CP-even one ($h^0$) or the heavy CP-even one ($H^0$). It is
found that both scenarios are consistent with the new data, not only in the
parameter regions near the decoupling limit but also in other regions far from
the decoupling limit. In addition, the current data are compatible with the
possibility that the light Higgs boson $h^0$ is hidden in the mass window of
90-100 GeV. The diphoton or $\tau\tau$ channel can provide a probe of this
possibility by the enhanced signal rates.


title: Compressed Baryonic Matter: from Nuclei to Pulsars

abstract:
  Our world is wonderful because of the negligible baryonic part although
unknown dark matter and dark energy dominate the Universe. Those nuclei in the
daily life are forbidden to fuse by compression due to the Coulomb repulse,
nevertheless, it is usually unexpected in extraterrestrial
extreme-environments: the gravity in a core of massive evolved star is so
strong that all the other forces (including the Coulomb one) could be
neglected. Compressed baryonic matter is then produced after supernova,
manifesting itself as pulsar-like stars observed. The study of this compressed
baryonic matter can not only be meaningful in fundamental physics (e.g., the
elementary color interaction at low-energy scale, testing gravity theories,
detecting nano-Hertz background gravitational waves), but has also profound
implications in engineering applications (including time standard and
navigation), and additionally, is focused by Chinese advanced telescopes,
either terrestrial or in space. Historically, in 1930s, L. Landau speculated
that dense matter at supra-nuclear density in stellar cores could be considered
as gigantic nuclei (the prototype of standard model of neutron star), however,
we address that the residual compact object of supernova could be of condensed
matter of quark clusters. The idea that pulsars are quark-cluster stars was not
ruled out during the last decade, and we are expecting to test further by
future powerful facilities. (in Chinese)


title: Analysis of an incompressible Navier-Stokes-Maxwell-Stefan system

abstract:
  The incompressible Navier-Stokes equations coupled to the Maxwell-Stefan
relations for the molar fluxes are analyzed in bounded domains with no-flux
boundary conditions. The system models the dynamics of a multicomponent gaseous
mixture under isothermal conditions. The global-in-time existence of bounded
weak solutions to the strongly coupled model and their exponential decay to the
homogeneous steady state are proved. The mathematical difficulties are due to
the singular Maxwell-Stefan diffusion matrix, the cross-diffusion terms, and
the Navier-Stokes coupling. The key idea of the proof is the use of a new
entropy functional and entropy variables, which allows for a proof of positive
lower and upper bounds of the mass densities without the use of a maximum
principle.


title:
Global existence analysis for degenerate energy-transport models for
  semiconductors

abstract:
  A class of energy-transport equations without electric field under mixed
Dirichlet-Neumann boundary conditions is analyzed. The system of degenerate and
strongly coupled parabolic equations for the particle density and temperature
arises in semiconductor device theory. The global-in-time existence of weak
nonnegative solutions is shown. The proof consists of a variable transformation
and a semi-discretization in time such that the discretized system becomes
elliptic and semilinear. Positive approximate solutions are obtained by
Stampacchia truncation arguments and a new cut-off test function.
Nonlogarithmic entropy inequalities yield gradient estimates which allow for
the limit of vanishing time step sizes. Exploiting the entropy inequality, the
long-time convergence of the weak solutions to the constant steady state is
proved. Because of the lack of appropriate convex Sobolev inequalities to
estimate the entropy dissipation, only an algebraic decay rate is obtained.
Numerical experiments indicate that the decay rate is typically exponential.


title: On Montel's theorem in several variables

abstract:
  Recently, the first author of this paper, used the structure of finite
dimensional translation invariant subspaces of C(R,C) to give a new proof of
classical Montel's theorem, about continuous solutions of Fr\'{e}chet's
functional equation $\Delta_h^mf=0$, for real functions (and complex functions)
of one real variable. In this paper we use similar ideas to prove a Montel's
type theorem for the case of complex valued functions defined over the discrete
group Z^d. Furthermore, we also state and demonstrate an improved version of
Montel's Theorem for complex functions of several real variables and complex
functions of several complex variables.


title: Pure Spinor b-ghost in a Super-Maxwell Background

abstract:
  In the pure spinor formalism for the superstring, the b-ghost is a composite
operator satisfying {Q,b}=T where Q is the pure spinor BRST operator and T is
the holomorphic stress tensor. The b-ghost is holomorphic in a flat
target-space background, but it is not holomorphic in a generic curved
target-space background and instead satisfies $\bar\partial b$ = [Q, \Omega]
for some \Omega. In this paper, \Omega\ is explicitly constructed for the case
of an open superstring in a super-Maxwell background.


title:
The VIMOS Public Extragalactic Redshift Survey (VIPERS): $\Omega_{\rm
  m_0}$ from the galaxy clustering ratio measured at $z \sim 1$

abstract:
  We use a sample of about 22,000 galaxies at $0.65<z<1.2$ from the VIPERS
PDR-1 catalogue, to constrain the cosmological model through a measurement of
the galaxy {\it clustering ratio} $\eta_{g,R}$. This statistic has favourable
properties, being defined as the ratio of two quantities characterizing the
smoothed density field in spheres of given radius $R$: the value of its
correlation function on a multiple of this scale, $\xi(nR)$, and its variance
$\sigma^2(R)$. For sufficiently large values of $R$, this is a universal
number, capturing 2-point clustering information independently of the linear
bias and linear redshift-space distortions of the specific galaxy tracers. In
this paper we discuss in detail how to extend the application of $\eta_{g,R}$
to quasi-linear scales and how to control and remove observational selection
effects which are typical of redshift surveys as VIPERS. We verify the accuracy
and efficiency of these procedures using mock catalogues that match the survey
selection process. These results evidence the robustness of $\eta_{g,R}$ to
non-linearities and observational effects, which is related to its very
definition as a ratio of quantities that are similarly affected.
  We measure $\Omega_{m,0}=0.270_{-0.025}^{+0.029}$. In addition to the great
precision achieved on our estimation of $\Omega_m$ using VIPERS PDR-1, this
result is remarkable because it appears to be in good agreement with a recent
estimate $z\simeq 0.3$, obtained applying the same technique to the SDSS-LRG
catalogue. It, therefore, suports the robustness of the present analysis.
Moreover, the combination of these two measurements at $z\sim 0.3$ and $z\sim
0.9$ provides us with a very precise estimate $\Omega_{m,0}=0.274\pm0.017$
which highlights the great consistency between our estimation and other
cosmological probes such as BAOs, CMB and Supernovae.


title:
A Low-Complexity Graph-Based LMMSE Receiver Designed for Colored Noise
  Induced by FTN-Signaling

abstract:
  We propose a low complexity graph-based linear minimum mean square error
(LMMSE) equalizer which considers both the intersymbol interference (ISI) and
the effect of non-white noise inherent in Faster-than-Nyquist (FTN) signaling.
In order to incorporate the statistics of noise signal into the factor graph
over which the LMMSE algorithm is implemented, we suggest a method that models
it as an autoregressive (AR) process. Furthermore, we develop a new mechanism
for exchange of information between the proposed equalizer and the channel
decoder through turbo iterations. Based on these improvements, we show that the
proposed low complexity receiver structure performs close to the optimal
decoder operating in ISI-free ideal scenario without FTN signaling through
simulations.


title:
Some problems in functional analysis inspired by Hahn Banach type
  theorems

abstract:
  As a cornerstone of functional analysis, Hahn Banach theorem constitutes an
indispensable tool of modern analysis where its impact extends beyond the
frontiers of linear functional analysis into several other domains of
mathematics, including complex analysis, partial differential equations and
ergodic theory besides many more. The paper is an attempt to draw attention to
certain applications of the Hahn Banach theorem which are less familiar to the
mathematical community, apart from highlighting certain aspects of the Hahn
Banach phenomena which have spurred intense research activity over the past few
years, especially involving operator analogues and nonlinear variants of this
theorem.


title:
Introducing single Mn2+ ions into spontaneously coupled quantum dot
  pairs

abstract:
  We present the photoluminescence excitation study of the self-assembled
CdTe/ZnTe quantum dots doped with manganese ions. We demonstrate the
identification method of spontaneously coupled quantum dots pairs containing
single Mn2+ ions. As the result of the coupling, the resonant absorption of the
photon in one quantum dot is followed by the exciton transfer into a
neighboring dot. It is shown that the Mn2+ ion might be present in the
absorbing, emitting or both quantum dots. The magnetic properties of the Mn2+
spin are revealed by a characteristic sixfold splitting of the excitonic line.
The statistics of the value of this splitting is analyzed for the large number
of the dots and gives the information on the maximum density of the neutral
exciton wave function.


title: Resonant dynamics of chromium condensates

abstract:
  We numerically study the dynamics of a spinor chromium condensate in low
magnetic fields. We show that the condensate evolution has a resonant character
revealing rich structure of resonances similar to that already discussed in the
case of alkali-atoms condensates. This indicates that dipolar resonances occur
commonly in the systems of cold atoms. In fact, they have been already observed
experimentally. We further simulate two recent experiments with chromium
condensates, in which the threshold in spin relaxation and the spontaneous
demagnetization phenomena were observed. We demonstrate that both these effects
originate in resonant dynamics of chromium condensate.


title:
Edge Modes in the Intermediate-D and Large-D Phases of the S=2 Quantum
  Spin Chain with XXZ and On-Site Anisotropies

abstract:
  We investigate the edge modes at T=0 in the intermediate-D (ID) phase and the
large-D (LD) phase of the S=2 quantum spin chain with the XXZ anisotropy and
the generalized on-site anisotropies by use of the DMRG. There exists a gapless
edge mode in the ID phase, while no gapless edge mode in the LD phase. These
results are consistent with the physical pictures of these phases. We also show
the ground-state phase diagrams obtained by use of the exact diagonalization
and the level spectroscopy analysis.


title: Regulatory-Optimal Funding

abstract:
  Funding is a cost to trading desks that they see as an input. Current
FVA-related literature reflects this by also taking funding costs as an input,
usually constant, and always risk-neutral. However, this funding curve is the
output from a Treasury point of view. Treasury must consider
Regulatory-required liquidity buffers, and both risk-neutral (Q) and physical
measures (P). We describe the Treasury funding problem and optimize against
both measures, using the Regulatory requirement as a constraint. We develop
theoretically optimal strategies for Q and P, then demonstrate a combined
approach in four markets (USD, JPY, EUR, GBP). Since we deal with physical
measures we develop appropriate statistical tests, and demonstrate highly
significant (p<0.00001), out-of-sample, improvements on hedged funding with a
combined approach achieving 44% to 71% of a perfect information criterion. Thus
regulatory liquidity requirements change both the funding problem and funding
costs.


title:
The "Tunneling Two-Level Systems" Model of the Low-Temperature
  Properties of Glasses: Are "Smoking-Gun" Tests Possible?

abstract:
  Following a brief review of the "two-level (tunneling) systems" model of the
low-temperature properties of amorphous solids ("glasses"), we ask whether it
is in fact the unique explanation of these properties as is usually assumed,
concluding that this is not necessarily the case. We point out that (a) one
specific form of the model is already experimentally refuted, and (b) that a
definitive test of the model in its most general form, while not yet carried
out, would appear to be now experimentally feasible.

categories: cond-mat.dis-nn cond-mat.mtrl-sci cond-mat.stat-mech quant-ph


title:
Finding the Largest Disk Containing a Query Point in Logarithmic Time
  with Linear Storage

abstract:
  Let D be a set of n disks in the plane. We present a data structure of size
O(n) that can compute, for any query point q, the largest disk in D that
contains q, in O(log n) time. The structure can be constructed in O(n log^3 n)
time. The optimal storage and query time of the structure improve several
recent solutions by Augustine et al. and by Kaplan and Sharir.


title: Spectra of random networks in the weak clustering regime

abstract:
  The asymptotic behaviour of dynamical processes in networks can be expressed
as a function of spectral properties of the corresponding adjacency and
Laplacian matrices. Although many theoretical results are known for the spectra
of traditional configuration models, networks generated through these models
fail to describe many topological features of real-world networks, in
particular non-null values of the clustering coefficient. Here we study effects
of cycles of order three (triangles) in network spectra. By using recent
advances in random matrix theory, we determine the spectral distribution of the
network adjacency matrix as a function of the average number of triangles
attached to each node for networks without modular structure and degree-degree
correlations. Implications to network dynamics are discussed. Our findings can
shed light in the study of how particular kinds of subgraphs influence network
dynamics.


title: Reconstructing Functions from Random Samples

abstract:
  From a sufficiently large point sample lying on a compact Riemannian
submanifold of Euclidean space, one can construct a simplicial complex which is
homotopy-equivalent to that manifold with high confidence. We describe a
corresponding result for a Lipschitz-continuous function between two such
manifolds. That is, we outline the construction of a simplicial map which
recovers the induced maps on homotopy and homology groups with high confidence
using only finite sampled data from the domain and range, as well as knowledge
of the image of every point sampled from the domain. We provide explicit bounds
on the size of the point samples required for such reconstruction in terms of
intrinsic properties of the domain, the co-domain and the function. This
reconstruction is robust to certain types of bounded sampling and evaluation
noise.


title: Low background x-ray detection with Micromegas for axion research

abstract:
  Axion helioscopes aim at the detection of solar axions through their
conversion into x-rays in laboratory magnetic fields. The use of low background
x-ray detectors is an essential component contributing to the sensitivity of
these searches. Here we review the recent advances on Micromegas detectors used
in the CERN Axion Solar Telescope (CAST) and proposed for the future
International Axion Observatory (IAXO). The most recent Micromegas setups in
CAST have achieved background levels of 1.5$\times10^{-6}$\ckcs, a factor of
more than 100 lower than the ones obtained by the first generation of CAST
detectors. This improvement is due to the development of active and passive
shielding techniques, offline discrimination techniques allowed by highly
granular readout patterns, as well as the use of radiopure detector components.
The status of the intensive R&D to reduce the background levels will be
described, including the operation of replica detectors in test benches and the
detailed Geant4 simulation of the detector setup and the detector response,
which has allowed the progressive understanding of background origins. The best
levels currently achieved in a test setup operating in the Canfranc Underground
Laboratory (LSC) are as low as $\sim10^{-7}$\ckcs, showing the good prospects
of this technology for application in the future IAXO.


title: Remarks on q-exponents of generalized modular functions

abstract:
  In this note, we prove multiplicity one theorems for generalized modular
functions (GMF), in terms of their q-exponents, and make a general statement
about the nature of values that the prime q-exponents of a GMF can take. We
shall also study the integrality of general q-exponents of a GMF and give an
upper bound on the first sign change of these q-exponents.


title: Flows in inkjet-printed aqueous rivulets

abstract:
  We used optical microscopy to investigate flows inside water rivulets that
were inkjet-printed onto different surfaces and under different ambient
conditions. The acquired fluid dynamics videos were submitted to the 2013
Gallery of Fluid Motion.


title:
Inversion Phenomena of the Anisotropies of the Hamiltonian and the Wave
  Function in Quantum Spin Chains

abstract:
  We investigate the inversion phenomena between the XXZ anisotropies of the
Hamiltonian and the wave function in quantum spin chains. We focus on the S=1/2
geometrically frustrated 3-leg ladder system with the XXZ interaction
anisotropy. By use of the degenerate perturbation theory from the strong rung
coupling limit, we have obtained the ground-state phase diagram. In some
parameter regions, the Tomonaga-Luttinger spin liquid state is realized in
spite of the Ising-like anisotropy, and the Neel state in spite of the XY-like
anisotropy.


title: A graph-based approach to repeating decimals

abstract:
  In this paper we deal with a classical problem in elementary number theory,
namely repeating decimals. We show how the digits of the period of the decimal
representation of any fraction $\frac{k}{m}$, where $k$ and $m$ are positive
integers arbitrarily chosen, can be obtained relying upon the graphs associated
with the iteration of a certain map over the finite set $\{0, 1, \dots, 10n-2
\}$ for a suitable integer $n$, which depends on $m$. In the last section of
the paper we generalize the results to any arbitrary choice of the base $B \geq
2$ for the representation of the fraction $\frac{k}{m}$.


title: Seven Sins in Portfolio Optimization

abstract:
  Although modern portfolio theory has been in existence for over 60 years,
fund managers often struggle to get its models to produce reliable portfolio
allocations without strongly constraining the decision vector by tight bands of
strategic allocation targets. The two main root causes to this problem are
inadequate parameter estimation and numerical artifacts. When both obstacles
are overcome, portfolio models yield excellent allocations. In this paper,
which is primarily aimed at practitioners, we discuss the most common mistakes
in setting up portfolio models and in solving them algorithmically.


title: Regression techniques for Portfolio Optimisation using MOSEK

abstract:
  Regression is widely used by practioners across many disciplines. We
reformulate the underlying optimisation problem as a second-order conic program
providing the flexibility often needed in applications. Using examples from
portfolio management and quantitative trading we solve regression problems with
and without constraints. Several Python code fragments are given. The code and
data are available online at http://www.github.com/tschm/MosekRegression.


title:
A Transition State Theory for Calculating Hopping Times and Diffusion in
  Highly Confined Fluids

abstract:
  Monte Carlo simulation is used to study the dynamical crossover from single
file diffusion to normal diffusion in fluids confined to narrow channels. We
show that the long time diffusion coefficients for a series of systems
involving hard and soft interaction potentials can be described in terms of a
hopping time that measures the time it takes for a particle to escape the cage
formed by its neighbors in the pore. Free energy barriers for the particle
hopping process are calculated and used to show that transition state theory
effectively describes the hopping time for all the systems studied, over a
range of pore diameters. Our work suggests that the combination of hopping
times and transition state theory offers a useful and general framework to
describe the dynamics of these highly confined fluids.


title:
An Improved K-means Clustering Based Approach to Detect a DNA Structure
  in H&E Image of Mouse Tissue Reacted with CD4-Green Antigen

abstract:
  In this manuscript we present the technique to detect and analyze the DNA
rich structure in Haemotoxylin & Eosin (H&E) image of a tissue treated with
anti CD4 green antigen. The detection of DNA rich structure can be considered
as a detection of blue nuclei present through the biomedical signal/image
processing technique performed on the image of the tissue obtained by the
Scanning Electron Microscope(SEM). Earlier the tissue treated with the anti CD4
green antigen, is stained with the H&E staining solution.


title: Dislocation networks in helium-4 crystals

abstract:
  The mechanical behavior of crystals is dominated by dislocation networks,
their structure and their interactions with impurities or thermal phonons.
However, in classical crystals, networks are usually random with impurities
often forming non-equilibrium clusters when their motion freezes at low
temperature. Helium provides unique advantages for the study of dislocations:
crystals are free of all but isotopic impurities, the concentration of these
can be reduced to the ppb level, and the impurities are mobile at all
temperatures and therefore remain in equilibrium with the dislocations. We have
achieved a comprehensive study of the mechanical response of 4He crystals to a
driving strain as a function of temperature, frequency and strain amplitude.
The quality of our fits to the complete set of data strongly supports our
assumption of string-like vibrating dislocations. It leads to a precise
determination of the distribution of dislocation network lengths and to
detailed information about the interaction between dislocations and both
thermal phonons and 3He impurities. The width of the dissipation peak
associated with impurity binding is larger than predicted by a simple Debye
model, and much of this broadening is due to the distribution of network
lengths.


title: On the reliability of Seasonal Climate Forecasts

abstract:
  Seasonal climate forecasts are being used increasingly across a range of
application sectors. A recent UK governmental report asked: How good are
seasonal climate forecasts on a scale of 1-5 (where 5 is very good), and how
good can we expect them to be in 30 years time? Seasonal climate forecasts are
made from ensembles of integrations of numerical models of climate. We argue
that goodness should be assessed primarily in terms of the probabilistic
reliability of these ensemble-based forecasts and that a 5 should be reserved
for systems which are not only reliable overall, but where, in particular,
small ensemble spread is a reliable indicator of low ensemble forecast error.
We study the reliability of regional temperature and precipitation forecasts of
the current operational seasonal forecast system of the European Centre for
Medium-Range Weather Forecasts, universally regarded as a world leading
operational institute producing seasonal climate forecasts. A wide range of
goodness rankings, depending on region and variable (with summer forecasts of
rainfall over Northern Europe performing exceptionally poorly) is found.
Finally, we discuss the prospects of reaching 5 across all regions and
variables in 30 years time.


title: Some surfaces with maximal Picard number

abstract:
  For a smooth complex projective variety, the rank of the N\'eron-Severi group
is bounded by the Hodge number h^{1,1}. Varieties with rk NS = h^{1,1} have
interesting properties, but are rather sparse, particularly in dimension 2. We
discuss in this note a number of examples, in particular those constructed from
curves with special Jacobians.


title: Disease Mapping via Negative Binomial Regression M-quantiles

abstract:
  We introduce a semi-parametric approach to ecological regression for disease
mapping, based on modelling the regression M-quantiles of a Negative Binomial
variable. The proposed method is robust to outliers in the model covariates,
including those due to measurement error, and can account for both spatial
heterogeneity and spatial clustering. A simulation experiment based on the
well-known Scottish lip cancer data set is used to compare the M-quantile
modelling approach and a random effects modelling approach for disease mapping.
This suggests that the M-quantile approach leads to predicted relative risks
with smaller root mean square error than standard disease mapping methods. The
paper concludes with an illustrative application of the M-quantile approach,
mapping low birth weight incidence data for English Local Authority Districts
for the years 2005-2010.


title:
QEMU/CPC: Static Analysis and CPS Conversion for Safe, Portable, and
  Efficient Coroutines

abstract:
  Coroutines and events are two common abstractions for writing concurrent
programs. Because coroutines are often more convenient, but events more
portable and efficient, it is natural to want to translate the former into the
latter. CPC is such a source-to-source translator for C programs, based on a
partial conversion into continuation-passing style (CPS conversion) of
functions annotated as cooperative.
  In this article, we study the application of the CPC translator to QEMU, an
open-source machine emulator which also uses annotated coroutine functions for
concurrency. We first propose a new type of annotations to identify functions
which never cooperate, and we introduce CoroCheck, a tool for the static
analysis and inference of cooperation annotations. Then, we improve the CPC
translator, defining CPS conversion as a calling convention for the C language,
with support for indirect calls to CPS-converted function through function
pointers. Finally, we apply CoroCheck and CPC to QEMU (750 000 lines of C
code), fixing hundreds of missing annotations and comparing performance of the
translated code with existing implementations of coroutines in QEMU.
  Our work shows the importance of static annotation checking to prevent actual
concurrency bugs, and demonstrates that CPS conversion is a flexible, portable,
and efficient compilation technique, even for very large programs written in an
imperative language.


title:
Emission line properties from broad-band photometry: Impact on selection
  and physical parameter estimation

abstract:
  Several works have now shown that nebular emission can have a significant
impact on broad-band photometry of high-redshift galaxies ($z > 3$), and how
this can affect parameter estimation from SED fitting. So far relatively small
spectroscopic samples have been used to measure this effect. Here we focus on a
large spectroscopic sample (N$\sim 2300$) at $z\sim2$, with measured H\alpha\
fluxes for $\sim100$ galaxies. Under appropriate assumptions, our SED fitting
code is able to reproduce observed H\alpha\ fluxes, and we infer that $\sim20$%
of our sample have parameters significantly affected when nebular emission is
taken into account. We also determine how nebular emission can affect selection
and parameter estimation of evolved galaxies (Balmer Break galaxies) at
high-redshift ($z\sim4$).


title: On the construction of l-equienergetic graphs

abstract:
  For a graph with $n$ vertices and $m$ edges, having Laplacian spectrum
$\mu_1, \mu_2, \cdots,\mu_n$ and signless Laplacian spectrum $\mu^+_1,\mu^+_2,
\cdots,\mu^+_n$, the Laplacian energy and signless Laplacian energy of $G$ are
respectively, defined as $LE(G)=\sum_{i=1}^{n}|\mu_i-\frac{2m}{n}|$ and
$LE^+(G)=\sum_{i=1}^{n}|\mu^+_i-\frac{2m}{n}|$. Two graphs $G_1$ and $G_2$ of
same order are said to be $L$-equienergetic if $LE(G_1)=LE(G_2)$ and
$Q$-equienergetic if $LE^{+}(G_1)=LE^{+}(G_2)$. The problem of constructing
graphs having same Laplacian energy has been considered by Stevanovic for
threshold graphs and by Liu and Liu for those graphs whose order is $n\equiv 0$
(mod 7). In general the problem of constructing $L$-equienergetic graphs from
any pair of given graphs is still not solved, and this work is an attempt in
that direction. We construct sequences of non-cospectral (Laplacian, signless
Laplacian) $L$-equienergetic and $Q$-equienergetic graphs from any pair of
graphs having same number of vertices and edges.


title:
Joint Indoor Localization and Radio Map Construction with Limited
  Deployment Load

abstract:
  One major bottleneck in the practical implementation of received signal
strength (RSS) based indoor localization systems is the extensive deployment
efforts required to construct the radio maps through fingerprinting. In this
paper, we aim to design an indoor localization scheme that can be directly
employed without building a full fingerprinted radio map of the indoor
environment. By accumulating the information of localized RSSs, this scheme can
also simultaneously construct the radio map with limited calibration. To design
this scheme, we employ a source data set that possesses the same spatial
correlation of the RSSs in the indoor environment under study. The knowledge of
this data set is then transferred to a limited number of calibration
fingerprints and one or several RSS observations with unknown locations, in
order to perform direct localization of these observations using manifold
alignment. We test two different source data sets, namely a simulated radio
propagation map and the environments plan coordinates. For moving users, we
exploit the correlation of their observations to improve the localization
accuracy. The online testing in two indoor environments shows that the plan
coordinates achieve better results than the simulated radio maps, and a
negligible degradation with 70-85% reduction in calibration load.


title: Poly(dA:dT)-rich DNAs are highly flexible in the context of DNA looping

abstract:
  Large-scale DNA deformation is ubiquitous in transcriptional regulation in
prokaryotes and eukaryotes alike. Though much is known about how transcription
factors and constellations of binding sites dictate where and how gene
regulation will occur, less is known about the role played by the intervening
DNA. In this work we explore the effect of sequence flexibility on
transcription factor-mediated DNA looping, by drawing on sequences identified
in nucleosome formation and ligase-mediated cyclization assays as being
especially favorable for or resistant to large deformations. We examine a
poly(dA:dT)-rich, nucleosome-repelling sequence that is often thought to belong
to a class of highly inflexible DNAs; two strong nucleosome positioning
sequences that share a set of particular sequence features common to
nucleosome-preferring DNAs; and a CG-rich sequence representative of high
G+C-content genomic regions that correlate with high nucleosome occupancy in
vivo. To measure the flexibility of these sequences in the context of DNA
looping, we combine the in vitro single-molecule tethered particle motion
assay, a canonical looping protein, and a statistical mechan- ical model that
allows us to quantitatively relate the looping probability to the looping free
energy. We show that, in contrast to the case of nucleosome occupancy, G+C
content does not positively correlate with looping probability, and that
despite sharing sequence features that are thought to determine nucleosome
affinity, the two strong nucleosome positioning sequences behave markedly
dissimilarly in the context of looping. Most surprisingly, the poly(dA:dT)-rich
DNA that is often characterized as highly inflexible in fact exhibits one of
the highest propensities for looping that we have measured.


title:
Monomial ideals with primary components given by powers of monomial
  prime ideals

abstract:
  We characterize monomial ideals which are intersections of monomial prime
ideals and study classes of ideals with this property, among them polymatroidal
ideals.


title: Verified computations for hyperbolic 3-manifolds

abstract:
  For a given cusped 3-manifold $M$ admitting an ideal triangulation, we
describe a method to rigorously prove that either $M$ or a filling of $M$
admits a complete hyperbolic structure via verified computer calculations.
Central to our method are an implementation of interval arithmetic and
Krawczyk's Test. These techniques represent an improvement over existing
algorithms as they are faster, while accounting for error accumulation in a
more direct and user friendly way.


title: pp scattering in t and b spaces

abstract:
  We propose analytical forms, in both momentum transfer and impact parameter
spaces, for the amplitudes of elastic pp scattering, giving coherent and
accurate description of the observables at all energies $\sqrt{s}\geq 20$ GeV.
The real and imaginary parts are separately identified through their roles at
small and large t values. The study of the differential cross sections in
b-space leads to the understanding of the effective interaction ranges
contributing to elastic and inelastic processes.


title: Modular cone metric spaces

abstract:
  In this paper the notion of modular cone metric space is introduced and some
properties of such spaces are investigated. Also we define convex modular cone
metric which takes values in CR(Y) where Y is a compact Hausdorff space. Then a
fixed point theorem is proved for contractions in these spaces. Furthermore, we
make a remark on paper [9] and it will be proved that their fixed point result
in modular metric spaces is not true.


title:
Grain boundary segregation of interstitial and substitutional impurity
  atoms in alpha-iron

abstract:
  The macroscopic behavior of polycrystalline materials is influenced by the
local variation of properties caused by the presence of impurities and defects.
The effect of these impurities at the atomic scale can either embrittle or
strengthen grain boundaries within. Thus, it is imperative to understand the
energetics associated with segregation to design materials with desirable
properties. Here, molecular statics simulations were employed to analyze the
energetics associated with the segregation of various elements (He, H, C, P,
and V) to four <100> (Sigma 5 and 13 GBs) and six <110> (Sigma 3,9,and 11 GBs)
symmetric tilt grain boundaries in alpha-Fe. This knowledge is important for
designing stable interfaces in harsh environments. Simulation results show that
the local atomic arrangements within the GB region and the resulting structural
units have a significant influence on the magnitude of binding energies of the
impurity (interstitial and substitutional) atoms. This data also suggests that
the site-to-site variation of energies within a boundary is substantial.
Comparing the binding energies of all ten boundaries shows that the Sigma
3(112) boundary possesses a much smaller binding energy for all interstitial
and substitutional impurity atoms among the boundaries examined here.
Additionally, based on the Rice-Wang model, our total energy calculations show
that V has a significant beneficial effect on the Fe grain boundary cohesion,
while P has a detrimental effect on grain boundary cohesion, much weaker than H
and He. This is significant for applications where extreme environmental damage
generates lattice defects and grain boundaries act as sinks for both
interstitial and substitutional impurity atoms. This methodology provides us
with a tool to effectively identify the local as well as the global segregation
behavior which can influence the GB cohesion.


title: Graphs and and two-step nilpotent Lie algebras

abstract:
  We consider a method popular in the literature of associating a two-step
nilpotent Lie algebra with a finite simple graph.
  We prove that the two-step nilpotent Lie algebras associated with two graphs
are Lie isomorphic if and only if the graphs from which they arise are
isomorphic.


title: Interlocking Resonance Patterns in Galaxy Disks

abstract:
  We have developed a method for finding dynamical resonances in disk galaxies
using the change in sense of the radial component of the in-plane velocity at a
resonance radius. Using simulations we show that we would expect to find these
changes at corotation radii, with a weaker effect at the ILR and a small effect
at the OLR. The method works well with observations at high spectral and
angular resolutions, and is suited to the analysis of 2D velocity fields in Ha
from Fabry-Perot spectroscopy, (though it is also applicable to fields in 21cm
emission from HI, or to CO emission lines). The observations are mainly from
the GHASP spectrometer data base, taken on the 1.93m telescope at Haute
Provence, plus some data from the GHaFaS spectrometer on the 4.2m WHT at La
Palma. We find clear indications of resonance effects in the disk velocity
fields of virtually all of the 104 galaxies. The number of resonance radii
detected ranges from one to seven, with a median of four. We have derived the
resonance curves: Omega, Omega+/-kappa/2, Omega+/-kappa/4 against radius for
all the galaxies, and used them to derive the ILR, the OLR, and the two 4:1
resonances for each corotation in each galaxy. This led us to discover a
pattern in over 70% of the sample: given two pattern speeds, say Omega1 and
Omega2, the OLR of Omega1 coincides with the corotation of Omega2, and the
inner 4:1 resonance of Omega2 coincides with the corotation of Omega1. Although
the second coincidence has been predicted, a prediction of this double
coincidence is not found in the literature. This pattern is found once in 42 of
the galaxies, twice in a further 26, three times in five, and even four times
in one galaxy. We also compute the ratio of corotation radius to bar length
where we have good enough image quality, finding a mean value of 1.3, and a
shallow increase towards later type galaxies.


title: Impact of Interleaver Pruning on Properties of Underlying Permutations

abstract:
  In this paper we address the issue of pruning (i.e., shortening) a given
interleaver via truncation of the transposition vector of the mother
permutation and study its impact on the structural properties of the
permutation. This method of pruning allows for continuous un-interrupted data
flow regardless of the permutation length since the permutation engine is a
buffer whose leading element is swapped by other elements in the queue. The
principle goal of pruning is that of construction of variable length and hence
delay interleavers with application to iterative soft information processing
and concatenated codes, using the same structure (possibly in hardware) of the
interleaver and deinterleaver units. We address the issue of how pruning
impacts the spread of the permutation and also look at how pruning impacts
algebraically constructed permutations. We note that pruning via truncation of
the transposition vector of the permutation can have a catastrophic impact on
the permutation spread of algebraically constructed permutations. To remedy
this problem, we propose a novel lifting method whereby a subset of the points
in the permutation map leading to low spread of the pruned permutation are
identified and eliminated. Practical realization of this lifting is then
proposed via dummy symbol insertion in the input queue of the Finite State
Permuter (FSP), and subsequent removal of the dummy symbols at the FSP output.


title:
Volume of a simplex as a multivalued algebraic function of the areas of
  its two-faces

abstract:
  For n greater than or equal to 4, the square of the volume of an n-simplex
satisfies a polynomial relation with coefficients depending on the squares of
the areas of 2-faces of this simplex. First, we compute the minimal degree of
such polynomial relation. Second, we prove that the volume an n-simplex
satisfies a monic polynomial relation with coefficients depending on the areas
of 2-faces of this simplex if and only if n is even and at least 6, and we
study the leading coefficients of polynomial relations satisfied by the volume
for other n.


title: A survey of Heegaard Floer homology

abstract:
  This work has two goals. The first is to provide a conceptual introduction to
Heegaard Floer homology, the second is to survey the current state of the
field, without aiming for completeness. After reviewing the structure of
Heegaard Floer homology, we list some of its most important applications. Many
of these are purely topological results, not referring to Heegaard Floer
homology itself. Then, we briefly outline the construction of Lagrangian
intersection Floer homology. We construct the Heegaard Floer chain complex as a
special case of the above, and try to motivate the role of the various
seemingly ad hoc features such as admissibility, the choice of basepoint, and
Spin^c-structures. We also discuss the proof of invariance of the homology up
to isomorphism under all the choices made, and how to define Heegaard Floer
homology using this in a functorial way (naturality). Next, we explain why
Heegaard Floer homology is computable, and how it lends itself to the various
combinatorial descriptions. The last chapter gives an overview of the
definition and applications of sutured Floer homology, which includes sketches
of some of the key proofs. Throughout, we have tried to collect some of the
important open conjectures in the area. For example, a positive answer to two
of these would give a new proof of the Poincar\'e conjecture.


title: Primitive Nonclassical Structures of the $N$-qubit Pauli Group

abstract:
  Several types of nonclassical structures within the $N$-qubit Pauli group
that can be seen as fundamental resources for quantum information processing
are presented and discussed. Identity Products (IDs), structures fundamentally
related to entanglement, are defined and explored. The Kochen-Specker theorem
is proved by particular sets of IDs that we call KS sets. We also present a new
theorem that we call the $N$-qubit Kochen-Specker theorem, which is proved by
particular sets of IDs that we call NKS sets, and whose utility is that it
leads to efficient constructions for KS sets. We define the criticality, or
irreducibility, of these structures, and its connection to entanglement. All
representative critical IDs for up to $N=4$ qubits are presented, and numerous
families of critical IDs for arbitrarily large values of $N$ are discussed. The
critical IDs for a given $N$ are a finite set of geometric objects that appear
to fully characterize the nonclassicality of the $N$-qubit Pauli group. Methods
for constructing critical KS sets and NKS sets from IDs are given, and
experimental tests of entanglement, contextuality, and nonlocality are
discussed. Possible applications and connections to other work are also
discussed


title: Single top quark production cross section at the Tevatron

abstract:
  The latest results on the measurements of electroweak top-quark production at
the Tevatron are presented with the full RunII dataset. The CDF and D0
Collaborations have performed measurements of the s, t, and s+t channels in
both l+jets and MET+jets final states. Evidence for the production of the s
channel is presented for the first time.


title: Hubble parameter corrected interactions in cosmology

abstract:
  In this paper we make steps in a new direction by considering fluids with EoS
of more general form $F(\rho,P)=0$. It is thought that there should be
interaction between cosmic fluids, but this assumption for this stage carries
only phenomenological character opening a room for different kind of
manipulations. In this article we will consider a modification of an
interaction $Q$, where we accept that interaction parameter $b_{1}$ (order of
unity) in $Q=3Hb_{1}\rho$ is time dependent and presented as a linear function
of Hubble parameter $H$ of the form $b_{0}+btH$, where $b$ and $b_{0}$ are
constants. We consider two different models include modified Chaplygin gas and
palotropic gas which have bulk viscosity. Then, we investigate problem
numerically and analyze behavior of different cosmological parameters
concerning to fluids and behavior of Universe.


title:
GPU-Acceleration of Parallel Unconditionally Stable Group Explicit
  Finite Difference Method

abstract:
  Graphics Processing Units (GPUs) are high performance co-processors
originally intended to improve the use and quality of computer graphics
applications. Once, researchers and practitioners noticed the potential of
using GPU for general purposes, GPUs applications have been extended from
graphics applications to other fields. The main objective of this paper is to
evaluate the impact of using GPU in solution of the transient diffusion type
equation by parallel and stable group explicit finite difference method and
encourage the researchers in this field to immigrate from implementing their
algorithms in CPU to the GPU emerging world. For comparing them, we implemented
the method in both GPU and CPU (multi-core) programming context. Moreover, we
proposed an optimal synchronization arrangement for the implementation
pseudo-code. Also, the interrelation of GPU parallel programming and
initializing the algorithm variables were discussed, taking advantage of
numerical experiences. The GPU-approach results are faster than those obtained
from a much expensive parallel 8-thread CPU-based programming. The GPU used in
this paper, is an ordinary old laptop GPU (GT 335M, launched at 2010) and is
accessible for everyone and the newer generations of GPU (as discussed in
paper) have even more performance priority over the similar-price GPUs. Then,
the results are expected to encourage the entire research society to take
advantage of GPUs and improve the time efficiency of their studies.


title:
Sublinear Column-wise Actions of the Matrix Exponential on Social
  Networks

abstract:
  We consider stochastic transition matrices from large social and information
networks. For these matrices, we describe and evaluate three fast methods to
estimate one column of the matrix exponential. The methods are designed to
exploit the properties inherent in social networks, such as a power-law degree
distribution. Using only this property, we prove that one of our algorithms has
a sublinear runtime. We present further experimental evidence showing that all
of them run quickly on social networks with billions of edges and accurately
identify the largest elements of the column.


title:
Optimal Energy Consumption Model for Smart Grid Households with Energy
  Storage

abstract:
  In this paper, we propose to model the energy consumption of smart grid
households with energy storage systems as an intertemporal trading economy.
Intertemporal trade refers to transaction of goods across time when an agent,
at any time, is faced with the option of consuming or saving with the aim of
using the savings in the future or spending the savings from the past. Smart
homes define optimal consumption as either balancing/leveling consumption such
that the utility company is presented with a uniform demand or as minimizing
consumption costs by storing energy during off-peak time periods when prices
are lower and use the stored energy during peak time periods when prices are
higher. Due to the varying nature of energy requirements of household and
market energy prices over different time periods in a day, households face a
trade-off between consuming to meet their current energy requirements and/or
storing energy for future consumption and/or spending energy stored in the
past. These trade-offs or consumption preferences of the household are modeled
as utility functions using consumer theory. We introduce two different utility
functions, one for cost minimization and another for consumption
balancing/leveling, that are maximized subject to respective budget,
consumption, storage and savings constraints to solve for the optimum
consumption profile. The optimization problem of a household with energy
storage is formulated as a geometric program for consumption
balancing/leveling, while cost minimization is formulated as a linear
programming problem. Simulation results show that the proposed model achieves
extremely low peak to average ratio in the consumption balancing/leveling
scheme with about 8% reduction in consumption costs and the least possible
amount for electricity bill with about 12% reduction in consumption costs in
the cost minimization scheme.


title: Infinite density for cold atoms in shallow optical lattices

abstract:
  Infinite densities can describe the long-time properties of systems when
ergodicity is broken and the equilibrium Boltzmann-Gibbs distribution fails. We
here perform semiclassical Monte Carlo simulations of cold atoms in dissipative
optical lattices with realistic parameters. We show that the momentum infinite
density, as well as its scale invariance, should be observable in shallow
potentials. We further evaluate the momentum autocorrelation function in the
stationary and aging regime.


title: Resolution of a Conjecture in Nonlocal Strain-gradient Plasticity

abstract:
  Strain-gradient theories of plasticity have been successful in modeling the
behavior of complex materials. However, the traditional formulation of these
theories lacks a material length scale, and is thus incapable of capturing
experimentally observed size effects that play an important role in the
behavior of nano structures. As a result, a modified theory was proposed which
incorporates an intrinsic dissipative length scale. The theory predicts that
the solutions to the flow rule are global minimizers of the functional for
energy dissipation. We prove that there are no global minimizers of the
functional, thus resolving a previously unsolved conjecture. Our result shows
that the variational formulation of the theory is unviable. The non-existence
of a global minimizer appears to be related to the formation of infinitely fine
plastic boundary layers.


title:
Microscopic Dirac Spectrum in a 2d Gauge Theory with Zero Chiral
  Condensate

abstract:
  Fermionic theories with a vanishing chiral condensate (in the chiral limit)
have recently attracted considerable interest; in particular variants of
multi-flavour QCD are candidates for this behaviour. Here we consider the
2-flavour Schwinger model as a simple theory with this property. Based on
simulations with light dynamical overlap fermions, we test the hypothesis that
in such models the low lying Dirac eigenvalues could be decorrelated. That has
been observed in 4d Yang-Mills theories at high temperature, but it cannot be
confirmed for the 2-flavour Schwinger model. We also discuss subtleties in the
evaluation of the mass anomalous dimension and its IR extrapolation.


title:
Phase-space dependence of particle-ratio fluctuations in Pb+Pb
  collisions from 20A to 158A GeV beam energy

abstract:
  A novel approach, the identity method, was used for particle identification
and the study of fluctuations of particle yield ratios in Pb+Pb collisions at
the CERN Super Proton Synchrotron (SPS). This procedure allows to unfold the
moments of the unknown multiplicity distributions of protons (p), kaons (K),
pions ($\pi$) and electrons (e). Using these moments the excitation function of
the fluctuation measure $\nu_{\text{\text{dyn}}}$[A,B] was measured, with A and
B denoting different particle types. The obtained energy dependence of
$\nu_{\text{dyn}}$ agrees with previously published NA49 results on the related
measure $\sigma_{\text{dyn}}$. Moreover, $\nu_{\text{dyn}}$ was found to depend
on the phase space coverage for [K,p] and [K,$\pi$] pairs. This feature most
likely explains the reported differences between measurements of NA49 and those
of STAR in central Au+Au collisions.


title: How many double squares can a string contain?

abstract:
  Counting the types of squares rather than their occurrences, we consider the
problem of bounding the number of distinct squares in a string. Fraenkel and
Simpson showed in 1998 that a string of length n contains at most 2n distinct
squares. Ilie presented in 2007 an asymptotic upper bound of 2n - Theta(log n).
We show that a string of length n contains at most 5n/3 distinct squares. This
new upper bound is obtained by investigating the combinatorial structure of
double squares and showing that a string of length n contains at most 2n/3
double squares. In addition, the established structural properties provide a
novel proof of Fraenkel and Simpson's result.


title: Stochastic homogenization of the Keller-Segel chemotaxis system

abstract:
  In this paper, we focus on the Keller-Segel chemotaxis system in a random
heterogeneous domain. We assume that the corresponding diffusion and chemotaxis
coefficients are given by stationary ergodic random fields and apply stochastic
two-scale convergence methods to derive the homogenized macroscopic equations.
In establishing our results, we also derive a priori estimates for the
Keller-Segel system that rely only on the boundedness of the coefficients; in
particular, no differentiability assumption on the diffusion and chemotaxis
coefficients for the chemotactic species is required. Finally, we prove the
convergence of a periodization procedure for approximating the homogenized
macroscopic coefficients.


title:
Cyclotron resonance study of quasiparticle mass and scattering rate in
  the hidden-order and superconducting phases of URu2Si2

abstract:
  The observation of cyclotron resonance in ultra-clean crystals of URu2Si2 [S.
Tonegawa et al., PRL 109, 036401 (2012)] provides another route besides quantum
oscillations to the determination of the bulk electronic structure in the
hidden order phase. We report detailed analyses of the resonance lines, which
fully resolve the cyclotron mass structure of the main Fermi surface sheets. A
particular focus is given to the anomalous splitting of the sharpest resonance
line near the [110] direction under in-plane magnetic-field rotation, which
implies peculiar electronic structure in the hidden order phase. The results
under the field rotation from [110] toward [001] direction reveal that the
splitting is a robust feature against field tilting from the basal plane. This
is in sharp contrast to the reported frequency branch alpha in the quantum
oscillation experiments showing a three-fold splitting that disappears by a
small field tilt, which can be explained by the magnetic breakdown between the
large hole sphere and small electron pockets. Our analysis of the cyclotron
resonance profiles reveals that the heavier branch of the split line has a
larger scattering rate, providing evidence for the existence of hot-spot
regions along the [110] direction. These results are consistent with the broken
fourfold rotational symmetry in the hidden-order phase, which can modify the
interband scattering in an asymmetric manner. We also extend our measurements
down to 0.7 K, which results in the observation of cyclotron resonance in the
superconducting state, where novel effects of vortex dynamics may enter. We
find that the cyclotron mass undergoes no change in the superconducting state.
In contrast, the quasiparticle scattering rate shows a rapid decrease below the
vortex-lattice melting transition temperature, which supports the formation of
quasiparticle Bloch state in the vortex lattice phase.


title: Heisenberg limited metrology using Quantum Error-Correction Codes

abstract:
  Methods borrowed from the world of quantum information processing have lately
been used to enhance the signal-to-noise ratio of quantum detectors. Here we
analyze the use of stabilizer quantum error-correction codes for the purpose of
signal detection. We show that using quantum error-correction codes a small
signal can be measured with Heisenberg limited uncertainty even in the presence
of noise. We analyze the limitations to the measurement of signals of interest
and discuss two simple examples. The possibility of long coherence times,
combined with their Heisenberg limited sensitivity to certain signals, pose
quantum error-correction codes as a promising detection scheme.


title: Knotted Vortices: Entropic Lattice Boltzmann Method for Vortex Dynamics

abstract: This fluid dynamics video shows "knotted" vortices in real fluids.


title:
Role of Anion Ordering in the Coexistence of Spin-Density-Wave and
  Superconductivity in (TMTSF)2ClO4

abstract:
  Using various transport and magnetotransport probes we study the coexistence
of spin-density wave and superconductor states in (TMTSF)2ClO4 at various
degrees of ClO4 anions ordering. In the two-phase complex state when both
superconductivity and spin-density wave are observed in transport, we find
prehistory effects, enhancement of the superconducting critical field, and
strong spatial anisotropy of the superconducting state. These features are
inconsistent with the conventional model of structural inhomogeneities produced
by anion ordering transition. We reveal instead that superconductor and
spin-density wave regions overlap on the temperature -- dimerization gap V
phase diagram, where V is varied by anion ordering. The effect of anion
ordering on (TMTSF)2ClO4 properties is thus analogous to that of pressure on
(TMTSF)2X (X=PF6 or AsF6), thereby unifying general picture of the coexistence
of superconductivity and spin-density wave in these compounds.


title: Parallel stochastic methods for PDE based grid generation

abstract:
  The efficient generation of meshes is an important step in the numerical
solution of various problems in physics and engineering. We are interested in
situations where global mesh quality and tight coupling to the physical
solution is important. We consider elliptic PDE based mesh generation and
present a method for the construction of adaptive meshes in two spatial
dimensions using domain decomposition that is suitable for an implementation on
parallel computing architectures. The method uses the stochastic representation
of the exact solution of a linear mesh generator of Winslow type to find the
points of the adaptive mesh along the subdomain interfaces. The meshes over the
single subdomains can then be obtained completely independently of each other
using the probabilistically computed solutions along the interfaces as boundary
conditions for the linear mesh generator. Further to the previously
acknowledged performance characteristics, we demonstrate how the stochastic
domain decomposition approach is particularly suited to the problem of grid
generation - generating quality meshes efficiently. In addition we show further
improvements are possible using interpolation of the subdomain interfaces and
smoothing of mesh candidates. An optimal placement strategy is introduced to
automatically choose the number and placement of points along the interface
using the mesh density function. Various examples of meshes constructed using
this stochastic-deterministic domain decomposition technique are shown and
compared to the respective single domain solutions using a representative mesh
quality measure. A brief performance study is included to show the viability of
the stochastic domain decomposition approach and to illustrate the effect of
algorithmic choices on the solver's efficiency.


title: The mechanics of a chain or ring of spherical magnets

abstract:
  Strong magnets, such as neodymium-iron-boron magnets, are increasingly being
manufactured as spheres. Because of their dipolar characters, these spheres can
easily be arranged into long chains that exhibit mechanical properties
reminiscent of elastic strings or rods. While simple formulations exist for the
energy of a deformed elastic rod, it is not clear whether or not they are also
appropriate for a chain of spherical magnets. In this paper, we use
discrete-to-continuum asymptotic analysis to derive a continuum model for the
energy of a deformed chain of magnets based on the magnetostatic interactions
between individual spheres. We find that the mechanical properties of a chain
of magnets differ significantly from those of an elastic rod: while both
magnetic chains and elastic rods support bending by change of local curvature,
nonlocal interaction terms also appear in the energy formulation for a magnetic
chain. This continuum model for the energy of a chain of magnets is used to
analyse small deformations of a circular ring of magnets and hence obtain
theoretical predictions for the vibrational modes of a circular ring of
magnets. Surprisingly, despite the contribution of nonlocal energy terms, we
find that the vibrations of a circular ring of magnets are governed by the same
equation that governs the vibrations of a circular elastic ring.


title: Parallelization of Kinetic Theory Simulations

abstract:
  Numerical studies of shock waves in large scale systems via kinetic
simulations with millions of particles are too computationally demanding to be
processed in serial. In this work we focus on optimizing the parallel
performance of a kinetic Monte Carlo code for astrophysical simulations such as
core-collapse supernovae. Our goal is to attain a flexible program that scales
well with the architecture of modern supercomputers. This approach requires a
hybrid model of programming that combines a message passing interface (MPI)
with a multithreading model (OpenMP) in C++. We report on our approach to
implement the hybrid design into the kinetic code and show first results which
demonstrate a significant gain in performance when many processors are applied.


title: On Optimal Probabilities in Stochastic Coordinate Descent Methods

abstract:
  We propose and analyze a new parallel coordinate descent method---`NSync---in
which at each iteration a random subset of coordinates is updated, in parallel,
allowing for the subsets to be chosen non-uniformly. We derive convergence
rates under a strong convexity assumption, and comment on how to assign
probabilities to the sets to optimize the bound. The complexity and practical
performance of the method can outperform its uniform variant by an order of
magnitude. Surprisingly, the strategy of updating a single randomly selected
coordinate per iteration---with optimal probabilities---may require less
iterations, both in theory and practice, than the strategy of updating all
coordinates at every iteration.