title:
Resonantly damped oscillations of elliptically shaped stratified
  emerging coronal loops

abstract:
  The effects of both elliptical shape and stage of emergence of the coronal
loop on the resonant absorption of standing kink oscillations are studied. To
do so, a typical coronal loop is modeled as a zero-beta longitudinally
stratified cylindrical magnetic flux tube. We developed the connection formulae
for the resonant absorption of standing transversal oscillations of a coronal
loop with an elliptical shape, at various stages of its emergence. Using the
connection formulae, the dispersion relation is derived and solved numerically
to obtain the frequencies and damping rates of the fundamental and
first-overtone kink modes. Our numerical results show that both the elliptical
shape and stage of emergence of the loop alter the frequencies and damping
rates of the tube as well as the ratio of frequencies of the fundamental and
its first-overtone modes. However, the ratio of the oscillation frequency to
the damping rate is not affected by the tube shape and stage of its emergence
and also is independent of the density stratification parameter.


title:
Numerical analysis of topological characteristics of three-dimensional
  geological models of oil and gas fields

abstract:
  We discuss the study of topological characteristics of random fields that are
used for numerical simulation of oil and gas reservoirs and numerical
algorithms (see arXiv:1302.3669), for computing such characteristics, for which
we demonstrate results of their applications.


title: When metal organic frameworks turn into linear magnets

abstract:
  We investigate the existence of linear magnetism in the metal organic
framework materials MOF-74-Fe, MOF-74-Co, and MOF-74-Ni, using first-principles
density functional theory. MOF-74 displays regular quasi-linear chains of
open-shell transition metal atoms, which are well separated. Our results show
that within these chains-for all three materials-ferromagnetic coupling of
significant strength occurs. In addition, the coupling in-between chains is at
least one order of magnitude smaller, making these materials almost perfect 1D
magnets at low temperature. The inter-chain coupling is found to be
anti-ferromagnetic, in agreement with experiments. While some quasi-1D
materials exist that exhibit linear magnetism-mostly complex oxides, polymers,
and a few other rare material-they are typically very difficult to synthesize.
The significance of our finding is that MOF-74 is very easy to synthesize and
it is likely the simplest realization of the 1D Ising model in nature. MOF-74
could thus be used in future experiments to study 1D magnetism at low
temperature.


title: Soliton surfaces and generalized symmetries of integrable systems

abstract:
  In this paper, we discuss some specific features of symmetries of integrable
systems which can be used to contruct the Fokas-Gel'fand formula for the
immersion of 2D-soliton surfaces, associated with such systems, in Lie
algebras. We establish the sufficient condition for the applicability of this
formula. This condition requires the existence of two vector fields which
generate a common symmetry of the initial system and its corresponding linear
spectral problem. This means that these two fields have to be group-related and
we determine an explicit form of this relation. It provides a criterion for the
selection of symmetries suitable for the use of the Fokas-Gel'fand formula. We
include some examples illustrating its application.


title: Ways to resolve Selleri's paradox

abstract:
  Selleri's paradox, based on an analysis of rotating frames, appears to show
that the speed of light in an inertial system is not normally isotropic. This
in turn seems at odds with the second postulate of special relativity requiring
a universal light speed in inertial systems. First, it is demonstrated how to
circumvent Selleri's argument using Einstein synchronization in rotating
frames. Then the nature of Selleri's result is exposed: it simply corresponds
to the adoption of a synchronization procedure different from Einstein's. In
this scheme, anisotropic one-way speeds of light by no means contradict special
relativity.


title:
Octet to decuplet electromagnetic transition in a relativistic quark
  model

abstract:
  We study the octet to decuplet baryon electromagnetic transitions using the
covariant spectator quark model, and predict the transition magnetic dipole
form factors for those involving the strange baryons. Utilizing SU(3) symmetry,
the valence quark contributions are supplemented by the pion cloud dressing
based on the one estimated in the $\gamma^\ast N \to \Delta$ reaction. Although
the valence quark contributions are dominant in general, the pion cloud effects
turn out to be very important to describe the experimental data. We also show
that, other mesons besides the pion in particular the kaon, may be relevant for
some reactions such as $\gamma^\ast \Sigma^+ \to \Sigma^{*+}$, based on our
analysis for the radiative decay widths of the strange decuplet baryons.


title: A Graphical Language for Proof Strategies

abstract:
  Complex automated proof strategies are often difficult to extract, visualise,
modify, and debug. Traditional tactic languages, often based on stack-based
goal propagation, make it easy to write proofs that obscure the flow of goals
between tactics and are fragile to minor changes in input, proof structure or
changes to tactics themselves. Here, we address this by introducing a graphical
language called PSGraph for writing proof strategies. Strategies are
constructed visually by "wiring together" collections of tactics and evaluated
by propagating goal nodes through the diagram via graph rewriting. Tactic nodes
can have many output wires, and use a filtering procedure based on goal-types
(predicates describing the features of a goal) to decide where best to send
newly-generated sub-goals.
  In addition to making the flow of goal information explicit, the graphical
language can fulfil the role of many tacticals using visual idioms like
branching, merging, and feedback loops. We argue that this language enables
development of more robust proof strategies and provide several examples, along
with a prototype implementation in Isabelle.


title: Fluctuations in Shear-Jammed States: A Statistical Ensemble Approach

abstract:
  Granular matter exists out of thermal equilibrium, i.e. it is athermal. While
conventional equilibrium statistical mechanics is not useful for characterizing
granular materials, the idea of constructing a statistical ensemble analogous
to its equilibrium counterpart to describe static granular matter was proposed
by Edwards and Oakshott more than two decades ago. Recent years have seen
several implementations of this idea. One of these is the stress ensemble,
which is based on properties of the force moment tensor, and applies to
frictional and frictionless grains. We demonstrate the full utility of this
statistical framework in shear jammed (SJ) experimental states [1,2], a special
class of granular solids created by pure shear, which is a strictly
non-equilbrium protocol for creating solids. We demonstrate that the stress
ensemble provides an excellent quantitative description of fluctuations in
experimental SJ states. We show that the stress fluctuations are controlled by
a single tensorial quantity: the angoricity of the system, which is a direct
analog of the thermodynamic temperature. SJ states exhibit significant
correlations in local stresses and are thus inherently different from
density-driven, isotropically jammed (IJ) states.


title: Selection theory of free dendritic growth in a potential flow

abstract:
  The Kruskal-Segur approach to selection theory in diffusion-limited or
Laplacian growth is extended via combination with the Zauderer decomposition
scheme. This way nonlinear bulk equations become tractable. To demonstrate the
method, we apply it to two-dimensional crystal growth in a potential flow. We
omit the simplifying approximations used in a preliminary calculation for the
same system [T. Fischaleck, K. Kassner, EPL 81, 54004 (2008)], thus exhibiting
the capability of the method to extend mathematical rigor to more complex
problems than hitherto accessible.


title:
Characterizing entanglement in pulsed parametric downconversion using
  chronocyclic Wigner functions

abstract:
  Pulsed parametric downconversion (PDC) processes generate photon pairs with a
rich spectral-temporal structure, which offer an attractive potential for
quantum information and communication applications. In this paper, we
investigate the four-dimensional chronocyclic Wigner function of the PDC state,
which naturally lends itself to the pulsed characteristics of these states.
From this function we derive the conditioned time-bandwidth product of one of
the pair photons, a quantity which is not only a valid measure of entanglement
between the PDC photons but also allows to highlight a remarkable link between
the discrete and continuous variable descriptions of PDC. We numerically
analyze PDC processes with different conditions to demonstrate the versatility
of our approach, which is applicable to a large number of current PDC sources.


title: Spin-velocity correlations of optically pumped atoms

abstract:
  We present efficient theoretical tools for describing the optical pumping of
atoms by light propagating at arbitrary directions with respect to an external
magnetic field, at buffer-gas pressures that are small enough for
velocity-selective optical pumping (VSOP) but large enough to cause substantial
collisional relaxation of the velocities and the spin. These are the conditions
for the sodium atoms at an altitude of about 100 km that are used as guidestars
for adaptive optics in modern ground-based telescopes to correct for
aberrations due to atmospheric turbulence. We use spin and velocity relaxation
modes to describe the distribution of atoms in spin space (including both
populations and coherences) and velocity space. Cusp kernels are used to
describe velocity-changing collisions. Optical pumping operators are
represented as a sum of poles in the complex velocity plane. Signals simulated
with these methods are in excellent agreement with previous experiments and
with preliminary experiments in our laboratory.


title: A Semiclassical Heat Kernel Proof of the Poincar\'e-Hopf Theorem

abstract:
  We treat the Witten operator on the de Rham complex with semiclassical heat
kernel methods to derive the Poincar\'e-Hopf theorem and degenerate
generalizations of it. Thereby, we see how the semiclassical asymptotics of the
Witten heat kernel are related to approaches using the Thom form of Mathai and
Quillen.


title: Adaptive Finite Element Approximations for Kohn-Sham Models

abstract:
  The Kohn-Sham equation is a powerful, widely used approach for computation of
ground state electronic energies and densities in chemistry, materials science,
biology, and nanosciences. In this paper, we study the adaptive finite element
approximations for the Kohn-Sham model. Based on the residual type a posteriori
error estimators proposed in this paper, we introduce an adaptive finite
element algorithm with a quite general marking strategy and prove the
convergence of the adaptive finite element approximations. Using D{\" o}rfler's
marking strategy, we then get the convergence rate and quasi-optimal
complexity. We also carry out several typical numerical experiments that not
only support our theory,but also show the robustness and efficiency of the
adaptive finite element computations in electronic structure calculations.


title: The AD775 cosmic event revisited: the Sun is to blame

abstract:
  Miyake et al. (henceforth M12) recently reported, based on 14C data, an
extreme cosmic event ca. AD775. Using a simple model, M12 claimed that the
event was too strong to be caused by a solar flare within the standard theory.
This implied a new paradigm of either an impossibly strong solar flare or a
very strong cosmic ray event of unknown origin occurred ca. AD775. We show that
the strength of the event was significantly overestimated by M12. Several
subsequent works have attempted to find a possible exotic source for such an
event, but they are all based on incorrect estimates by M12. We revisit this
event with analysis of new datasets and consistent theoretical modelling. We
verified the experimental result for the AD775 event using independent datasets
including 10Be series and newly measured 14C annual data. We surveyed available
historical chronicles for astronomical observations for the AD770s to identify
potential sightings of aurorae or supernovae. We interpreted the 14C
measurements using an appropriate carbon cycle model. We show that: (1) The
reality of the AD775 event is confirmed by new measurements of 14C; (2) by
using an inappropriate carbon cycle model, M12 strongly overestimated the
event's strength; (3) The revised magnitude of the event is consistent with
different independent datasets (14C, 10Be, 36Cl) and can be associated with a
strong, but not inexplicably strong, SEP event (or a sequence of events), and
provides the first evidence for an event of this magnitude (the fluence >30 MeV
was about 4.5*10^{10} /cm2) in multiple datasets; (4) This is in agreement with
increased auroral activity identified in historical chronicles. This point to
the likely solar origin of the event, which is the greatest solar event on a
multi-millennial time scale, placing a strong observational constraint on the
theory of explosive energy releases on the Sun and cool stars.


title: High-energy emission of variable objects in the OMC--VAR catalogue

abstract:
  OMC-VAR is the first catalogue of variable sources observed by the Optical
Monitoring Camera (OMC) on board INTEGRAL. It includes photometry and
variability data for more than 5000 sources of very different nature. In order
to study the multi-wavelength similarities and differences of the engines
powering AGN and X-ray binaries, especially those powered by a black hole, we
have searched for counterparts in several high-energy and infrared catalogues,
including the 4th IBIS/ISGRI soft gamma-ray survey catalogue, the XMM-Newton
Serendipitous Source catalogue, the 2MASS All-Sky catalogue of Point Sources,
the 2MASS Extended Source Catalog and the WISE All-Sky Data Release.
Preliminary multiwavelength results for the IBIS counterparts are presented and
discussed.


title:
Contraction and stability analysis of steady-states for open quantum
  systems described by Lindblad differential equations

abstract:
  For discrete-time systems, governed by Kraus maps, the work of D. Petz has
characterized the set of universal contraction metrics. In the present paper,
we use this characterization to derive a set of quadratic Lyapunov functions
for continuous-time systems, governed by Lindblad differential equations, that
have a steady-state with full rank. An extremity of this set is given by the
Bures metric, for which the quadratic Lyapunov function is obtained by
inverting a Sylvester equation. We illustrate the method by providing a strict
Lyapunov function for a Lindblad equation designed to stabilize a quantum
electrodynamic "cat" state by reservoir engineering. In fact we prove that any
Lindblad equation on the Hilbert space of the (truncated) harmonic oscillator,
which has a full-rank equilibrium and which has, among its decoherence
channels, a channel corresponding to the photon loss operator, globally
converges to that equilibrium.


title:
Exploiting Independent Subformulas: A Faster Approximation Scheme for
  #k-SAT

abstract:
  We present an improvement on Thurley's recent randomized approximation scheme
for #k-SAT where the task is to count the number of satisfying truth
assignments of a Boolean function {\Phi} given as an n-variable k-CNF. We
introduce a novel way to identify independent substructures of {\Phi} and can
therefore reduce the size of the search space considerably. Our randomized
algorithm works for any k. For #3-SAT, it runs in time
O(\epsilon^{-2}*1.51426^n), for #4-SAT, it runs in time
O(\epsilon^{-2}*1.60816^n), with error bound \epsilon.


title:
Ferromagnetic to antiferromagnetic transition of one-dimensional spinor
  Bose gases with spin-orbit coupling

abstract:
  We have analytically solved one-dimensional interacting two-component bosonic
gases with spin-orbit (SO) coupling by the Bethe-ansatz method. Through a gauge
transformation, the effect of SO coupling is incorporated into a spin-dependent
twisted boundary condition. Our result shows that the SO coupling can influence
the eigenenergy in a periodical pattern. The interplay between interaction and
SO coupling may induce the energy level crossing for the ground state, which
leads to a transition from the ferromagnetic to antiferromagnetic state.


title: Quantitative Mode Stability for the Wave Equation on the Kerr Spacetime

abstract:
  We give a quantitative refinement and simple proofs of mode stability type
statements for the wave equation on Kerr backgrounds in the full sub-extremal
range (|a| < M). As an application, we are able to quantitatively control the
energy flux along the horizon and null infinity and establish integrated local
energy decay for solutions to the wave equation in any bounded-frequency
regime.


title: An extension of Nunokawa lemma and its example

abstract:
  For analytic functions p(z) in the open unit disk U with p(0)=1, Nunokwa has
given a result which called Nunokawa lemma (Proc. Japan Acad., Ser. A 68
(1992)). By studying Nunokawa lemma, we obtain this expansion. In this paper,
we introduce this result and its example.


title:
Calculating conjugacy classes in Sylow p-subgroups of finite Chevalley
  groups of rank six and seven

abstract:
  Let G(q) be a finite Chevalley group, where q is a power of a good prime p,
and let U(q) be a Sylow p-subgroup of G(q). Then a generalized version of a
conjecture of Higman asserts that the number k(U(q)) of conjugacy classes in
U(q) is given by a polynomial in q with integer coefficients. In an earlier
paper, the first and the third authors developed an algorithm to calculate the
values of k(U(q)). By implementing it into a computer program using GAP, they
were able to calculate k(U(q)) for G of rank at most 5, thereby proving that
for these cases k(U(q)) is given by a polynomial in q. In this paper we present
some refinements and improvements of the algorithm that allow us to calculate
the values of k(U(q)) for finite Chevalley groups of rank six and seven, except
E_7. We observe that k(U(q)) is a polynomial, so that the generalized Higman
conjecture holds for these groups. Moreover, if we write k(U(q)) as a
polynomial in q-1, then the coefficients are non-negative.
  Under the assumption that k(U(q)) is a polynomial in q-1, we also give an
explicit formula for the coefficients of k(U(q)) of degrees zero, one and two.


title: Weak magnetic transitions in pyrochlore Bi2Ir2O7

abstract:
  Muon spin relaxation measurements on Bi2Ir2O7 show that it undergoes a bulk
magnetic transition at 1.84(3) K. This is accompanied by increases in the muon
spin relaxation rate and the amplitude of the non-relaxing part of the signal.
The magnetic field experienced by muons is estimated to be 0.7 mT at
low-temperature, around two orders of magnitude smaller than that in other
pyrochlore iridates. These results suggest that the low-temperature state
represents ordering of exceptionally small magnetic moments with persistent
weak dynamics. The relaxation rate increases further below 0.23(4) K,
coincident with a growth in the specific heat, suggesting the existence of a
second low-temperature magnetic transition.


title: Tradition and Innovation in Scientists' Research Strategies

abstract:
  What factors affect a scientist's choice of research problem? Qualitative
research in the history, philosophy, and sociology of science suggests that
this choice is shaped by an "essential tension" between the professional demand
for productivity and a conflicting drive toward risky innovation. We examine
this tension empirically in the context of biomedical chemistry. We use complex
networks to represent the evolving state of scientific knowledge, as expressed
in publications. We then define research strategies relative to these networks.
Scientists can introduce novel chemicals or chemical relationships--or delve
deeper into known ones. They can consolidate existing knowledge clusters, or
bridge distant ones. Analyzing such choices in aggregate, we find that the
distribution of strategies remains remarkably stable, even as chemical
knowledge grows dramatically. High-risk strategies, which explore new chemical
relationships, are less prevalent in the literature, reflecting a growing focus
on established knowledge at the expense of new opportunities. Research
following a risky strategy is more likely to be ignored but also more likely to
achieve high impact and recognition. While the outcome of a risky strategy has
a higher expected reward than the outcome of a conservative strategy, the
additional reward is insufficient to compensate for the additional risk. By
studying the winners of 137 different prizes in biomedicine and chemistry, we
show that the occasional "gamble" for extraordinary impact is the most
plausible explanation for observed levels of risk-taking. Our empirical
demonstration and unpacking of the "essential tension" suggests policy
interventions that may foster more innovative research.


title: Thermostated Hamiltonian dynamics with log-oscillators

abstract:
  With this work we present two new methods for the generation of thermostated,
manifestly Hamiltonian dynamics and provide corresponding illustrations. The
basis for this new class of thermostats are the peculiar thermodynamics as
exhibited by logarithmic oscillators. These two schemes are best suited when
applied to systems with a small number of degrees of freedom.


title: Extensions of Nunokawa lemma for argument properties

abstract:
  Let H[a_0,n] be the class of functions p(z)=a_0+a_nz^n+... which are analytic
in the open unit disk U. For p(z)in H[1,2], M. Nunokawa, S. Owa, N. Uyanik and
H. Shiraishi (Math. Comput. Modelling. 55 (2012), 1245-1250) have shown some
theorems for argument properties. The object of the present paper is to discuss
some extensions of Nnnokawa lemma and its applications for argument properties.


title: SVZ + 1/q2 expansion versus some QCD holographic Models

abstract:
  Considering the classical two-point correlators built from (axial)-vector,
scalar \bar qq and gluonium currents, we confront results obtained using the
SVZ + 1/q^2 expansion to the ones from some QCD holographic models in the
Euclidian region and with negative dilaton \Phi_i(z)=- |c_i^2| z^2. We conclude
that the presence of the 1/q^2-term in the SVZ-expansion due to a tachyonic
gluon mass appears naturally in the Minimum Soft Wall (MSW) and the
Gauge/String Dual (GSD) models which can also reproduce semi-quantitatively
some of the higher dimension condensate contributions appearing in the OPE. The
Hard-Wall model shows a large departure from the SVZ + 1/q^2 expansion in the
vector, scalar and gluonium channels due to the absence of any power
corrections. The equivalence of the MSW and GSD models is manifest in the
vector channel through the relation of the dilaton parameter with the tachyonic
gluon mass. For approximately reproducing the phenomenological values of the
dimension d=4,6 condensates, the holographic models require a tachyonic gluon
mass (\alpha_s/\pi)\lambda^2= -(0.12- 0.14) GeV^2, which is about twice the
fitted phenomenological value from e^+e^- data. The relation of the inverse
length parameter c_i to the tachyonic gluon mass also shows that c_i is channel
dependent but not universal for a given holographic model. Using the MSW model
and M_\rho=0.78 GeV as input, we predict a scalar \bar qq mass M_S=(0.95-1.10)
GeV and a scalar gluonium mass M_G= (1.1- 1.3) GeV.


title: Pawel Max Maksym (1983-2013) Polish Astronomer and Film-maker

abstract:
  The sudden and untimely death of Pawel Max Maksym will not diminish his
contributions to the field of occultation astronomy, and to Polish society in
general. Founder of the Pope Silvester II Observatory in Bukowiec, he was also
writing a book to introduce children to astronomy. Graduating in Geography with
an experimental thesis in Lunar Occultations at Lodz University, Pawel earned a
diploma from the prestigious National Film School in Lodz. An expert observer,
he mastered the technique of stellar occultations, fostering the scientific
activity of the Observatory. A review of his publications in Minor Planet
Circulars and on YouTube is presented here.


title: Using Virtual Addresses with Communication Channels

abstract:
  While for single processor and SMP machines, memory is the allocatable
quantity, for machines made up of large amounts of parallel computing units,
each with its own local memory, the allocatable quantity is a single computing
unit. Where virtual address management is used to keep memory coherent and
allow allocation of more than physical memory is actually available, virtual
communication channel references can be used to make computing units stay
connected across allocation and swapping.


title:
Magnetic Hyperthermia with Fe3O4 nanoparticles: the Influence of
  Particle Size on Energy Absorption

abstract:
  We have studied the magnetic and power absorption properties of a series of
magnetic nanoparticles (MNPs) of Fe3O4 with average sizes <d> ranging from 3 to
26 nm. Heating experiments as a function of particle size revealed a strong
increase in the specific power absorption (SPA) values for particles with <d> =
25-30 nm. On the other side saturation magnetization MS values of these MNPs
remain essentially constant for particles with <d> above 10 nm, suggesting that
the absorption mechanism is not determined by MS. The largest SPA value
obtained was 130 W/g, corresponding to a bimodal particle distribution with
average size values of 17 and 26 nm.


title: A Mathematical Model for an Hourglass Magnetic Field

abstract:
  Starting with a mathematical boundary value problem for the magnetic vector
potential in an axisymmetric cylindrical coordinate system, we derive a general
solution for any arbitrary current distribution using the method of Green's
functions. We use this to derive an analytic form for an hourglass magnetic
field pattern created by electrical currents that are concentrated near (but
not confined within) the equatorial plane of a cylindrical coordinate system.
Our solution is not characterized by a cusp at the equatorial plane, as in
previous solutions based on a current sheet. The pattern we derive provides a
very good fit to hourglass magnetic field patterns emerging from
three-dimensional numerical simulations of core formation, and can in principle
be used for source-fitting of observed magnetic hourglass patterns.


title: The Fresh-Finger Property

abstract:
  The unified property roughly states that searching for an element is fast
when the current access is close to a recent access. Here, "close" refers to
rank distance measured among all elements stored by the dictionary. We show
that distance need not be measured this way: in fact, it is only necessary to
consider a small working-set of elements to measure this rank distance. This
results in a data structure with access time that is an improvement upon those
offered by the unified property for many query sequences.


title: The IBIS / ISGRI Source Location Accuracy

abstract:
  We present here results on the source location accuracy of the INTEGRAL
IBIS/ISGRI coded mask telescope, based on ten years of INTEGRAL data and on
recent developments in the data analysis procedures. Data were selected and
processed with the new Off-line Scientific Analysis pipeline (OSA10.0) that
benefits from the most accurate background corrections, the most performing
coding noise cleaning and sky reconstruction algorithms available. We obtained
updated parameters for the evaluation of the point source location error from
the source signal to noise ratio. These results are compared to previous
estimates and to theoretical expectations. Also thanks to a new fitting
procedure the typical error at 90% confidence level for a source at a signal to
noise of 10 is now estimated to be 1.5 arcmin. Prospects for future analysis on
the Point Spread Function fitting procedure and on the evaluation of residual
biases are also presented. The new consolidated parameters describing the
source location accuracy that will be derived in the near future using the
whole INTEGRAL database, the new fitting technique and the bias correction,
will be included in future versions of OSA.


title: Coefficient estimates for Schwarz functions

abstract:
  Let $\mathcal{B}$ be the class of functions $w(z)$ of the form
$w(z)=\sum\limits_{k=1}^{\infty}b_k z^k$ which are analytic and satisfy the
condition $|w(z)|<1$ in the open unit disk $\mathbb{U}=\left\{z\in
\mathbb{C}:|z|<1\right\}$. Then we call $w(z)\in \mathcal{B}$ the Schwarz
function. In this paper, we discuss new coefficient estimates for Schwarz
functions by applying the lemma due to Livingston (Proc. Amer. Math. Soc.
21(1969), 545--552).


title:
Superconducting pairing and the pseudogap in nematic striped
  La2-xSrxCuO4

abstract:
  The individual k\parallel and k\perp stripe excitations in fluctuating
spin-charge stripes have not been observed yet. In Raman scattering if we set,
for example, incident and scattered light polarizations to two possible stripe
directions, we can observe the fluctuating stripe as if it is static. Using the
different symmetry selection rule between the B1g two-magnon scattering and the
B1g and B2g isotropic electronic scattering, we succeeded to obtain the
k\parallel and k\perp strip magnetic excitations separately in La2-xSrxCuO4.
Only the k\perp stripe excitations appear in the wide-energy isotropic
electronic Raman scattering, indicating that the charge transfer is restricted
to the direction perpendicular to the stripe. This is the same as the Burgers
vector of an edge dislocation which easily slides perpendicularly to the
stripe. Hence charges at the edge dislocation move together with the
dislocation perpendicularly to the stripe, while other charges are localized. A
looped edge dislocation has lower energy than a single edge dislocation. The
superconducting coherence length is close to the inter-charge stripe distance
at x \le 0.2. Therefore we conclude that Cooper pairs are formed at looped edge
dislocations. The restricted charge transfer direction naturally explains the
opening of a pseudogap around (0, {\pi}) for the stripe parallel to the b axis
and the reconstruction of the Fermi surface to have a flat plane near (0,
{\pi}). They break the four-fold rotational symmetry. Furthermore the
systematic experiments revealed the carrier density dependence of the isotropic
and anisotropic electronic excitations, the spin density wave and/or charge
density wave gap near ({\pi}/2, {\pi}/2), and the strong coupling between the
electronic states near ({\pi}/2, {\pi}/2) and the zone boundary phonons at
({\pi}, {\pi}).


title: Simulation of Lattice QCD with Domain-Wall Fermions

abstract:
  Quantum Chromodynamics (QCD) is the fundamental theory for the interaction
between quarks and gluons. It manifests as the short-range strong interaction
inside the nucleus, and plays an important role in the evolution of the early
universe, from the quark-gluon phase to the hadron phase. To solve QCD is a
grand challenge, since it requires very large-scale numerical simulations of
the discretized action of QCD on the 4-dimensional space-time lattice.
Moreover, since quarks are relativistic fermions, the 5-th dimension is
introduced such that massless quarks with exact chiral symmetry can be realized
at finite lattice spacing, on the boundaries of the 5-th dimension, the
so-called domain-wall fermion (DWF). In this talk, I discuss how to simulate
lattice QCD with DWF such that the chiral symmetry can be preserved optimally
with a finite extent in the 5-th dimension. I also outline the simulations
which have been performing by the TWQCD Collaboration and present some recent
physical results.


title: Effective Action for Dp-Brane in Large RR (p-1)-Form Background

abstract:
  We construct the low energy effective action for the bosonic sector on a
Dp-brane in large constant RR (p-1)-form field background. The action is
invariant under both U(1) gauge symmetry and the volume-preserving
diffeomorphism characterizing the RR-field background. Scalar fields
representing transverse coordinates of the Dp-brane are included. It also
respects T-duality and is consistent with the action for M5-brane in C-field
background.


title: A possible new test of general relativity with Juno

abstract:
  The expansion in multipoles of the gravitational potential of a rotating body
affects the orbital motion of a test particle orbiting it with long-term
perturbations both at a classical and at a relativistic level. In this
preliminary sensitivity analysis, we show that, for the first time, the J2 c^-2
effects could be measured by the ongoing Juno mission in the gravitational
field of Jupiter during its yearlong science phase (10 November 2016-5 October
2017) thanks to its high eccentricity (e=0.947) and to the huge oblateness of
Jupiter (J2=1.47 10^-2). The semi-major axis a and the perijove \omega\ of Juno
are expected to be shifted by \Delta a =700-900 m and \Delta\omega = 50-60
milliarcseconds, respectively, over 1-2 yr. A numerical analysis shows also
that the expected J2c^-2 range-rate signal for Juno should be as large as 280
microns per second during a typical 6 h pass at its closest approach.
Independent analyses previously performed by other researchers about the
measurability of the Lense-Thirring effect showed that the radio science
apparatus of Juno should reach an accuracy in Doppler range-rate measurements
of 1-5 microns per second over such passes. The range-rate signature of the
classical even zonal perturbations is different from the 1PN one. Thus, further
investigations, based on covariance analyses of simulated Doppler data and
dedicated parameters estimation, are worth of further consideration. It turns
out that the J2 c^-2 effects cannot be responsible of the flyby anomaly in the
gravitational field of the Earth. A dedicated spacecraft in a 6678 km X 57103
km polar orbit would experience a geocentric J2 c^-2 range-rate shift of 0.4 mm
s^-1.


title: Inflations of ideal triangulations

abstract:
  Starting with an ideal triangulation of the interior of a compact 3-manifold
M with boundary, no component of which is a 2-sphere, we provide a
construction, called an inflation of the ideal triangulation, to obtain a
strongly related triangulations of M itself. Besides a step-by-step algorithm
for such a construction, we provide examples of an inflation of the
two-tetrahedra ideal triangulation of the complement of the figure-eight knot
in the 3-sphere, giving a minimal triangulation, having ten tetrahedra, of the
figure-eight knot exterior. As another example, we provide an inflation of the
one-tetrahedron Gieseking manifold giving a minimal triangulation, having seven
tetrahedra, of a nonorientable compact 3-manifold with Klein bottle boundary.
Several applications of inflations are discussed.


title: Dust-forming molecules in VY Canis Majoris (and Betelgeuse)

abstract:
  The formation of inorganic dust in circumstellar environments of evolved
stars is poorly understood. Spectra of molecules thought to be most important
for the nucleation, i.e. AlO, TiO, and TiO2, have been recently detected in the
red supergiant VY CMa. These molecules are effectively formed in VY CMa and the
observations suggest that non-equilibrium chemistry must be involved in their
formation and nucleation into dust. In addition to exploring the recent
observations of VY CMa, we briefly discuss the possibility of detecting these
molecules in the dust-poor circumstellar environment of Betelgeuse.


title: Study of a quantum scattering process by means of entropic measures

abstract:
  In this work, a scattering process of quantum particles through a potential
barrier is considered. The statistical complexity and the Fisher-Shannon
information are calculated for this problem. The behaviour of these
entropy-information measures as a function of the energy of the incident
particles is compared with the behaviour of a physical magnitude, the
reflection coefficient in the barrier. We find that these statistical
magnitudes present their minimum values in the same situations in which the
reflection coefficient is null. These are the situations where the total
transmission through the barrier is achieved, {\it the transparency points}, a
typical phenomenon due to the quantum nature of the system.


title: Homotopy-theoretic E-theory and n-order

abstract:
  The bootstrap category in E-theory for C*-algebras over a finite space X is
embedded into the homotopy category of certain diagrams of K-module spectra.
Therefore it has infinite n-order for every n. The same holds for the bootstrap
category in G-equivariant E-theory for a compact group G and for the
Spanier--Whitehead category in connective E-theory.


title:
Equation of state of hypernuclear matter: impact of
  hyperon--scalar-meson couplings

abstract:
  We study the equation of state and composition of hypernuclear matter within
a relativistic density functional theory with density-dependent couplings. The
parameter space of hyperon--scalar-meson couplings is explored by allowing for
mixing and breaking of SU(6) symmetry, while keeping the nucleonic couplings
constant fixed. The subset of equations of state, which corresponds to small
values of hyperon--scalar-meson couplings allows for massive M < 2.25 M_solar
compact stars; the radii of hypernuclear stars are within the range 12--14 km.
We also study the equation of state of hot neutrino-rich and neutrinoless
hypernuclear matter and confirm that neutrinos stiffen the equation of state
and dramatically change the composition of matter by keeping the fractions of
charged leptons nearly independent of the density prior to the onset of
neutrino transparency. We provide piecewise polytropic fits to six
representative equations of state of hypernuclear matter, which are suitable
for applications in numerical astrophysics.


title:
A functional central limit theorem for the partial sums of sorted i.i.d.
  random variables

abstract:
  Let $(X_i,i\geq 1)$ be a sequence of i.i.d. random variables with values in
$[0,1]$, and $f$ be a function such that $`E(f(X_1)^2)<+\infty$. We show a
functional central limit theorem for the process $t\mapsto \sum_{i=1}^n
f(X_i)1_{X_i\leq t}$.


title: Online Learning for Time Series Prediction

abstract:
  In this paper we address the problem of predicting a time series using the
ARMA (autoregressive moving average) model, under minimal assumptions on the
noise terms. Using regret minimization techniques, we develop effective online
learning algorithms for the prediction problem, without assuming that the noise
terms are Gaussian, identically distributed or even independent. Furthermore,
we show that our algorithm's performances asymptotically approaches the
performance of the best ARMA model in hindsight.


title: The conformal metric structure of Geometrothermodynamics

abstract:
  We present a thorough analysis on the invariance of the most widely used
metrics in the Geometrothermodynamics (GTD) programme. We centre our attention
in the invariance of the curvature of the space of equilibrium states under a
change of fundamental representation. Assuming that the systems under
consideration can be described by a fundamental relation which is a homogeneous
function of a definite order, we demonstrate that such invariance is only
compatible with total Legendre transformations in the present form of the
programme. We give the explicit form of a metric which is invariant under total
Legendre transformations and whose induced metric produces a curvature which is
independent of the fundamental representation. Finally, we study a generic
system with two degrees of freedom and whose fundamental relation is
homogeneous of order one.


title: Nonwandering sets of interval skew products

abstract:
  In this paper we consider a class of skew products over transitive subshifts
of finite type with interval fibers. For a natural class of 1-parameter
families we prove that for all but countably many parameter values the
nonwandering set (in particular, the union of all attractors and repellers) has
zero measure. As a consequence, the same holds for a residual subset of the
space of skew products.


title:
Triangularization properties of power linear maps and the Structural
  Conjecture

abstract:
  In this paper, we discuss several additional properties a power linear Keller
map may have. The Structural Conjecture by Druzkowski in [Dru] asserts that two
such properties are equivalent, but we show that one of this properties is
stronger than the other. We even show that the property of linear
triangularizability is strictly in between. Furthermore, we give some positive
results for small dimensions and small Jacobian ranks.


title:
Disorder to chaos transition in the conductance distribution of
  corrugated waveguides

abstract:
  We perform a detailed numerical study of the distribution of conductances
$P(T)$ for quasi-one-dimensional corrugated waveguides as a function of the
corrugation complexity (from rough to smooth). We verify the universality of
$P(T)$ in both, the diffusive ($\bra T \ket> 1$) and the localized ($\bra T
\ket\ll 1$) transport regimes. However, at the crossover regime ($\bra T \ket
\sim 1$), we observe that $P(T)$ evolves from the surface-disorder to the
bulk-disorder theoretical predictions for decreasing complexity in the
waveguide boundaries. We explain this behavior as a transition from disorder to
deterministic chaos; since, in the limit of smooth boundaries the corrugated
waveguides are, effectively, linear chains of chaotic cavities.


title:
Describing the complexity of systems: multi-variable "set complexity"
  and the information basis of systems biology

abstract:
  Context dependence is central to the description of complexity. Keying on the
pairwise definition of "set complexity" we use an information theory approach
to formulate general measures of systems complexity. We examine the properties
of multi-variable dependency starting with the concept of interaction
information. We then present a new measure for unbiased detection of
multi-variable dependency, "differential interaction information." This
quantity for two variables reduces to the pairwise "set complexity" previously
proposed as a context-dependent measure of information in biological systems.
We generalize it here to an arbitrary number of variables. Critical limiting
properties of the "differential interaction information" are key to the
generalization. This measure extends previous ideas about biological
information and provides a more sophisticated basis for study of complexity.
The properties of "differential interaction information" also suggest new
approaches to data analysis. Given a data set of system measurements
differential interaction information can provide a measure of collective
dependence, which can be represented in hypergraphs describing complex system
interaction patterns. We investigate this kind of analysis using simulated data
sets. The conjoining of a generalized set complexity measure, multi-variable
dependency analysis, and hypergraphs is our central result. While our focus is
on complex biological systems, our results are applicable to any complex
system.


title: Small cancellation theory and Burnside problem

abstract:
  In these notes we detail the geometrical approach of small cancellation
theory used by T. Delzant and M. Gromov to provide a new proof of the
infiniteness of free Burnside groups and periodic quotients of torsion-free
hyperbolic groups.


title:
Optimum Header Positioning in Successive Interference Cancellation (SIC)
  based Aloha

abstract:
  Random Access MAC protocols are simple and effective when the nature of the
traffic is unpredictable and sporadic. In the following paper, investigations
on the new Enhanced Contention Resolution ALOHA (ECRA) are presented, where
some new aspects of the protocol are investigated. Mathematical derivation and
numerical evaluation of the symbol interference probability after SIC are here
provided. Results of the optimum header positioning which is found to be in the
beginning and in the end of the packets, are exploited for the evaluation of
ECRA throughput and Packet Error Rate (PER) under imperfect knowledge of
packets positions. Remarkable gains in the maximum throughput are observed for
ECRA w.r.t. Contention Resolution ALOHA (CRA) under this assumption.


title: Stellar activity as a tracer of moving groups

abstract:
  We present the results of a study of the stellar activity in the solar
neighborhood using complete kinematics (galactocentric velocities U,V,W) and
the chromospheric activity index $\log R'_{\rm{HK}}$. We analyzed the average
activity level near the centers of known moving groups using a sample of 2529
stars and found that the stars near these associations tend to be more active
than field stars. This supports the hypothesis that these structures, or at
least a significant part of them, are composed of kinematically bound, young
stars. We confirmed our results by using Galaxy Evolution Explorer (GALEX) UV
data and kinematics taken from the Geneva-Copenhagen Survey for the stars in
the sample. Finally, we present a compiled catalog with kinematics and
activities for 2529 stars and a list of potential moving group members selected
based on their stellar activity level.


title:
The energy of waves in the photosphere and lower chromosphere: IV.
  Inversion results of Ca II H spectra

abstract:
  Most static 1D atmosphere models in the quiet Sun predict a rise of the gas
temperature at chromospheric layers, but numerical simulations only yield an
increase in the brightness temperature. We investigate the thermal structure in
the solar chromosphere as derived from an LTE inversion of Ca II H spectra in
QS and active regions. We investigate the temperature stratifications on
differences between magnetic and field-free regions in the QS, and between QS
and ARs. We determine the energy content of individual calcium bright grains
(BGs). The rms temperature fluctuations are below 100 K in the photosphere and
200-300 K in the chromosphere. The average temperature stratification in the QS
does not exhibit a clear chromospheric temperature rise, opposite to the AR
case. We find an energy content of about 7*10E18 J for BGs that repeat with a
cadence of about 160 secs. The precursors of BGs have a vertical extent of
about 200 km and a horizontal extent of about 1 Mm. The comparison of observed
with synthetic NLTE profiles confirms that the solar chromosphere in the QS
oscillates between an atmosphere in radiative equilibrium and one with a
moderate chromospheric temperature rise. Two-dimensional x-z temperature maps
exhibit nearly horizontal canopy-like structures with a few Mm extent around
photospheric magnetic field concentrations at a height of about 600 km. The
large difference between QS regions and ARs, and the better match of AR and
non-LTE reference spectra suggest that magnetic heating processes are more
important than commonly assumed. The temperature fluctuations in QS derived by
the LTE inversion do not suffice on average to maintain a stationary
chromospheric temperature rise. The spatially and vertically resolved
information on the temperature structure allows one to investigate in detail
the topology and evolution of the thermal structure in the lower solar
atmosphere.


title:
Online Convex Optimization Against Adversaries with Memory and
  Application to Statistical Arbitrage

abstract:
  The framework of online learning with memory naturally captures learning
problems with temporal constraints, and was previously studied for the experts
setting. In this work we extend the notion of learning with memory to the
general Online Convex Optimization (OCO) framework, and present two algorithms
that attain low regret. The first algorithm applies to Lipschitz continuous
loss functions, obtaining optimal regret bounds for both convex and strongly
convex losses. The second algorithm attains the optimal regret bounds and
applies more broadly to convex losses without requiring Lipschitz continuity,
yet is more complicated to implement. We complement our theoretic results with
an application to statistical arbitrage in finance: we devise algorithms for
constructing mean-reverting portfolios.


title: Hidden charm N and Delta resonances with heavy-quark symmetry

abstract:
  We develop a model to describe odd parity baryon resonances generated
dynamically through a unitary baryon-meson coupled-channels approach. The
scheme applies to channels with light and/or heavy quark content. Distinct
features of the model are that, i) the interaction is an S-wave contact one,
ii) it reduces to the SU(3) Weinberg-Tomozawa Hamiltonian when light
pseudoscalar mesons are involved, thus, respecting chiral symmetry, iii)
spin-flavor in preserved in the light quark sector, and iv) heavy quark spin
symmetry is fulfilled in the heavy quark sector. In particular, baryon-meson
states with different content in c or in c-bar do not mix. The model is a
minimal one and it contains no free parameters. In this work, we focus on
baryon resonances with hidden-charm (at least one c-bar and one c quarks). We
analyze several possible sectors and, for the sector with zero net charm, we
write down the most general Lagrangian consistent with SU(3) and heavy quark
spin symmetry. We explicitly study the N and Delta states, which are produced
from the S-wave interaction of pseudoscalar and vector mesons with 1/2+ and
3/2+ baryons within the charmless and strangeless hidden charm sector. We
predict seven odd parity N-like and five Delta-like states with masses around 4
GeV, most of them as bound states. These states form heavy-quark spin
multiplets, which are almost degenerate in mass. The predicted new resonances
definitely cannot be accommodated by quark models with three constituent quarks
and they might be looked for in the forthcoming PANDA experiment at the future
FAIR facility.


title: Simulation of ultra-high energy photon propagation with PRESHOWER 2.0

abstract:
  In this paper we describe a new release of the PRESHOWER program, a tool for
Monte Carlo simulation of propagation of ultra-high energy photons in the
magnetic field of the Earth. The PRESHOWER program is designed to calculate
magnetic pair production and bremsstrahlung and should be used together with
other programs to simulate extensive air showers induced by photons. The main
new features of the PRESHOWER code include a much faster algorithm applied in
the procedures of simulating the processes of gamma conversion and
bremsstrahlung, update of the geomagnetic field model, and a minor correction.
The new simulation procedure increases the flexibility of the code so that it
can also be applied to other magnetic field configurations such as, for
example, encountered in the vicinity of the sun or neutron stars.


title:
Ba-ion extraction from a high pressure Xe gas for double-beta decay
  studies with EXO

abstract:
  An experimental setup is being developed to extract Ba ions from a
high-pressure Xe gas environment. It aims to transport Ba ions from 10 bar Xe
to vacuum conditions. The setup utilizes a converging-diverging nozzle in
combination with a radio-frequency (RF) funnel to move Ba ions into vacuum
through the pressure drop of several orders of magnitude. This technique is
intended to be used in a future multi-ton detector investigating double-beta
decay in $^{136}$Xe. Efficient extraction and detection of Ba ions, the decay
product of Xe, would allow for a background-free measurement of the $^{136}$Xe
double-beta decay.


title: Scaling limit and cube-root fluctuations in SOS surfaces above a wall

abstract:
  Consider the classical $(2+1)$-dimensional Solid-On-Solid model above a hard
wall on an $L\times L$ box of $\bbZ^2$. The model describes a crystal surface
by assigning a non-negative integer height $\eta_x$ to each site $x$ in the box
and 0 heights to its boundary. The probability of a surface configuration
$\eta$ is proportional to $\exp(-\beta \mathcal{H}(\eta))$, where $\beta$ is
the inverse-temperature and $\mathcal{H}(\eta)$ sums the absolute values of
height differences between neighboring sites.
  We give a full description of the shape of the SOS surface for low enough
temperatures. First we show that with high probability the height of almost all
sites is concentrated on two levels, $H(L)=\lfloor (1/4\beta)\log L\rfloor$ and
$H(L)-1$. Moreover, for most values of $L$ the height is concentrated on the
single value $H(L)$. Next, we study the ensemble of level lines corresponding
to the heights $(H(L),H(L)-1,...)$. We prove that w.h.p. there is a unique
macroscopic level line for each height. Furthermore, when taking a diverging
sequence of system sizes $L_k$, the rescaled macroscopic level line at height
$H(L_k)-n$ has a limiting shape if the fractional parts of $(1/4\beta)\log L_k$
converge to a noncritical value. The scaling limit is an explicit convex subset
of the unit square $Q$ and its boundary has a flat component on the boundary of
$Q$. Finally, the highest macroscopic level line has $L_k^{1/3+o(1)}$
fluctuations along the flat part of the boundary of its limiting shape.


title:
Top SU(5) Models: Baryon and Lepton Number Violating Resonances at the
  LHC

abstract:
  We propose the minimal and renormalizable non-supersymmetric top SU(5) models
where the $SU(5)\times SU(3)'_C \times SU(2)'_L \times U(1)'_Y$ gauge symmetry
is broken down to the Standard Model (SM) gauge symmetry at the TeV scale. The
first two families of the SM fermions are charged under $SU(3)'_C \times
SU(2)'_L \times U(1)'_Y$ while the third family is charged under SU(5). In the
minimal top SU(5) model, we show that the quark CKM mixing matrix can be
generated via dimension-five operators, and the proton decay problem can be
solved by fine-tuning the coefficients of the higher dimensional operators at
the order of $10^{-4}$. In the renormalizable top SU(5) model, we can explain
the quark CKM mixing matrix by introducing vector-like particles, and we do not
have proton decay problem. The models give rise to leptoquark and diquark gauge
bosons which violate both lepton and baryon numbers involving the third family
quarks and leptons. The current experimental limits for these particles is well
below the TeV scale. We also discuss the productions and decays of these new
gauge bosons, and their ensuing signals, as well as their reach at the LHC.


title: Photometric Analysis of Variable Stars in NGC 299

abstract:
  We have analyzed OGLE-III photometry for stars in the SMC cluster NGC 299.
Two eclipsing binaries and one intrinsic variable (most likely a Be star) are
identified. Unlike other young SMC clusters, no low-amplitude pulsating
variables are present.


title: Reduced Density Matrix after a Quantum Quench

abstract:
  We consider the reduced density matrix (RDM) \rho_A(t) for a finite subsystem
A after a global quantum quench in the infinite transverse-field Ising chain.
It has been recently shown that the infinite time limit of \rho_A(t) is
described by the RDM \rho_{GGE,A} of a generalized Gibbs ensemble. Here we
present some details on how to construct this ensemble in terms of local
integrals of motion, and show its equivalence to the expression in terms of
mode occupation numbers widely used in the literature. We then address the
question, how \rho_A(t) approaches \rho_{GGE,A} as a function of time. To that
end we introduce a distance on the space of density matrices and show that it
approaches zero as a universal power-law t^{-3/2} in time. As the RDM
completely determines all local observables within A, this provides information
on the relaxation of correlation functions of local operators. We then address
the issue, of how well a truncated generalized Gibbs ensemble with a finite
number of local higher conservation laws describes a given subsystem at late
times. We find that taking into account only local conservation laws with a
range at most comparable to the subsystem size provides a good description.
However, excluding even a single one of the most local conservation laws in
general completely spoils this agreement.

categories: cond-mat.stat-mech math-ph math.MP quant-ph


title: Superfast Tikhonov Regularization of Toeplitz Systems

abstract:
  Toeplitz-structured linear systems arise often in practical engineering
problems. Correspondingly, a number of algorithms have been developed that
exploit Toeplitz structure to gain computational efficiency when solving these
systems. The earliest "fast" algorithms for Toeplitz systems required O(n^2)
operations, while more recent "superfast" algorithms reduce the cost to O(n
(log n)^2) or below. In this work, we present a superfast algorithm for
Tikhonov regularization of Toeplitz systems. Using an
"extension-and-transformation" technique, our algorithm translates a
Tikhonov-regularized Toeplitz system into a type of specialized polynomial
problem known as tangential interpolation. Under this formulation, we can
compute the solution in only O(n (log n)^2) operations. We use numerical
simulations to demonstrate our algorithm's complexity and verify that it
returns stable solutions.


title: Category theory for scientists (Old version)

abstract:
  There are many books designed to introduce category theory to either a
mathematical audience or a computer science audience. In this book, our
audience is the broader scientific community. We attempt to show that category
theory can be applied throughout the sciences as a framework for modeling
phenomena and communicating results. In order to target the scientific
audience, this book is example-based rather than proof-based. For example,
monoids are framed in terms of agents acting on objects, sheaves are introduced
with primary examples coming from geography, and colored operads are discussed
in terms of their ability to model self-similarity.
  A new version with solutions to exercises will be available through MIT
Press.


title:
Topological spin excitations induced by an external magnetic field
  coupled to a surface with rotational symmetry

abstract:
  We study the Heisenberg model in an external magnetic field on curved
surfaces with rotational symmetry. The Euler-Lagrange static equations, derived
from the Hamiltonian lead to the inhomogeneous double sine-Gordon equation
(DSG). However, if the magnetic field is coupled with the metric elements of
the surface, and consequently, its curvature, the homogeneous DSG appears and a
$2\pi$-soliton is obtained as a solution for this model. In order to obey the
self-dual equations, surface deformations are predicted at the sector where the
spins point in the opposite direction to the magnetic field. The model was used
to particularize the characteristic lenght of the 2$\pi$-soliton for three
specific rotationally symmetric surfaces: the cylinder, the catenoid and the
hyperboloid. Fractional 2$\pi$-solitons must appear on finite surfaces, as the
sphere, torus and barrels, for example.


title:
Some exact solutions to the Lighthill Whitham Richards Payne traffic
  flow equations

abstract:
  We find a class of exact solutions to the Lighthill Whitham Richards Payne
(LWRP) traffic flow equations. Using two consecutive lagrangian
transformations, a linearization is achieved. Next, depending on the initial
density, we either apply (again two) Lambert functions and obtain exact
formulas for the dependence of the car density and velocity on x and t, or
else, failing that, the same result in a parametric representation. The
calculation always involves two possible factorizations of a consistency
condition. Both must be considered. In physical terms, the lineup usually
separates into two offshoots at different velocities. Each velocity soon
becomes uniform. This outcome in many ways resembles the two soliton solution
to the Korteweg-de Vries equation. We check general conservation requirements.
Although traffic flow research has developed tremendously since LWRP, this
calculation, being exact, may open the door to solving similar problems, such
as gas dynamics or water flow in rivers. With this possibility in mind, we
outline the procedure in some detail at the end.


title: On the gauge action of a Leavitt path algebra

abstract:
  We introduce a revised notion of gauge action in relation with Leavitt path
algebras. This notion is based on group schemes and captures the full
information of the grading on the algebra as it is the case of the gauge action
of the graph $C^*$-algebra of the graph.


title: A Witt type formula

abstract:
  This paper investigates some combinatorial and algebraic properties of a Witt
type formula for graphs.


title:
Large deviations, dynamics and phase transitions in large stochastic
  heterogeneous neural networks

abstract:
  We analyze the macroscopic behavior of multi-populations randomly connected
neural networks with interaction delays. Similar to cases occurring in spin
glasses, we show that the sequences of empirical measures satisfy a large
deviation principle, and converge towards a self-consistent non-Markovian
process. The proof differs in that we are working in infinite-dimensional
spaces (interaction delays), non-centered interactions and multiple cell types.
The limit equation is qualitatively analyzed, and we identify a number of phase
transitions in such systems upon changes in delays, connectivity patterns and
dispersion, particularly focusing on the emergence of non-equilibrium states
involving synchronized oscillations.


title: Macroscopic equations governing noisy spiking neuronal populations

abstract:
  At functional scales, cortical behavior results from the complex interplay of
a large number of excitable cells operating in noisy environments. Such systems
resist to mathematical analysis, and computational neurosciences have largely
relied on heuristic partial (and partially justified) macroscopic models, which
successfully reproduced a number of relevant phenomena. The relationship
between these macroscopic models and the spiking noisy dynamics of the
underlying cells has since then been a great endeavor. Based on recent
mean-field reductions for such spiking neurons, we present here {a principled
reduction of large biologically plausible neuronal networks to firing-rate
models, providing a rigorous} relationship between the macroscopic activity of
populations of spiking neurons and popular macroscopic models, under a few
assumptions (mainly linearity of the synapses). {The reduced model we derive
consists of simple, low-dimensional ordinary differential equations with}
parameters and {nonlinearities derived from} the underlying properties of the
cells, and in particular the noise level. {These simple reduced models are
shown to reproduce accurately the dynamics of large networks in numerical
simulations}. Appropriate parameters and functions are made available {online}
for different models of neurons: McKean, Fitzhugh-Nagumo and Hodgkin-Huxley
models.


title: Template Mode Hierarchies for Binary Black Hole Mergers

abstract:
  Matched filtering is a popular data analysis framework used to search for
gravitational wave signals emitted by compact object binaries. The templates
used in matched filtering searches are constructed predominantly from the
quadrupolar mode because this mode is the energetically most dominant channel.
However, for highly precessing binaries or binaries with moderately large mass
ratios, significant power is also carried by higher-order modes. We investigate
how the inclusion of higher modes in the templates increases the prospects for
detecting gravitational waves. Specifically, we use numerical relativity
waveforms from the late inspiral and coalescence of binary black holes to
identify mode hierarchies that cover the sky of binary orientations. We show
that the ordering in these hierarchies depends on the characteristics of the
binary system and the mode strengths. Our study demonstrates that detecting
moderately high precessing or unequal mass binaries requires the inclusion of
higher modes in the templates banks.


title: Dynamical models for some torus homeomorphisms

abstract:
  It is well known that the rotation number of a circle homeomorphism defined
by H. Poincar\'e allows to completely understand the dynamics of such a map
from the topological point of view. In this paper, we collect some results
concerning the existence of topological dynamical models associated to rotation
sets of homeomorphisms of $\T^2$.


title: One-loop contributions in the EFT for the $\Lambda N \to NN$ transition

abstract:
  We consider the $\Lambda N\to NN$ weak transition, responsible for a large
fraction of the non-mesonic weak decay of hypernuclei. We follow on the
previously derived effective field theory and compute the next-to-leading
one-loop corrections. Explicit expressions for all diagrams are provided, which
result in contributions to all relevant partial waves.


title:
Experimental Tests on Yang-Mills Gravity with Accurate Measurements of
  the Deflection of Light

abstract:
  In the geometric-optics limit, Yang-Mills gravity with space-time
translational gauge symmetry predicts $\D \phi =7Gm/(2R) \approx 1.53''$ for
the deflection of a light ray by the sun. The result, which is about 12%
smaller than that in the conventional theory, is consistent with experiments
involving optical frequencies that had an accuracy of 10-20%.


title: Ensemble Sparse Models for Image Analysis

abstract:
  Sparse representations with learned dictionaries have been successful in
several image analysis applications. In this paper, we propose and analyze the
framework of ensemble sparse models, and demonstrate their utility in image
restoration and unsupervised clustering. The proposed ensemble model
approximates the data as a linear combination of approximations from multiple
\textit{weak} sparse models. Theoretical analysis of the ensemble model reveals
that even in the worst-case, the ensemble can perform better than any of its
constituent individual models. The dictionaries corresponding to the individual
sparse models are obtained using either random example selection or boosted
approaches. Boosted approaches learn one dictionary per round such that the
dictionary learned in a particular round is optimized for the training examples
having high reconstruction error in the previous round. Results with compressed
recovery show that the ensemble representations lead to a better performance
compared to using a single dictionary obtained with the conventional
alternating minimization approach. The proposed ensemble models are also used
for single image superresolution, and we show that they perform comparably to
the recent approaches. In unsupervised clustering, experiments show that the
proposed model performs better than baseline approaches in several standard
datasets.


title: Forward Brownian Motion

abstract:
  We consider processes which have the distribution of standard Brownian motion
(in the forward direction of time) starting from random points on the
trajectory which accumulate at $-\infty$. We show that these processes do not
have to have the distribution of standard Brownian motion in the backward
direction of time, no matter which random time we take as the origin. We study
the maximum and minimum rates of growth for these processes in the backward
direction. We also address the question of which extra assumptions make one of
these processes a two-sided Brownian motion.


title:
Notes on $\omega$-graphs, reflexive $\omega$-graphs, their higher
  transformations, and $\omega$-operads

abstract:
  In this note we propose an $\omega$-operadical way to prove the existence of
the $\omega$-graph of the $\omega$-graphs and the reflexive $\omega$- graph of
the reflexive $\omega$-graphs.


title:
Decidable Classes of Tree Automata Mixing Local and Global Constraints
  Modulo Flat Theories

abstract:
  We define a class of ranked tree automata TABG generalizing both the tree
automata with local tests between brothers of Bogaert and Tison (1992) and with
global equality and disequality constraints (TAGED) of Filiot et al. (2007).
TABG can test for equality and disequality modulo a given flat equational
theory between brother subterms and between subterms whose positions are
defined by the states reached during a computation. In particular, TABG can
check that all the subterms reaching a given state are distinct. This
constraint is related to monadic key constraints for XML documents, meaning
that every two distinct positions of a given type have different values. We
prove decidability of the emptiness problem for TABG. This solves, in
particular, the open question of the decidability of emptiness for TAGED. We
further extend our result by allowing global arithmetic constraints for
counting the number of occurrences of some state or the number of different
equivalence classes of subterms (modulo a given flat equational theory)
reaching some state during a computation. We also adapt the model to unranked
ordered terms. As a consequence of our results for TABG, we prove the
decidability of a fragment of the monadic second order logic on trees extended
with predicates for equality and disequality between subtrees, and cardinality.


title: Einstein's Special Relativity: The Hyperbolic Geometric Viewpoint

abstract:
  The analytic hyperbolic geometric viewpoint of Einstein's special theory of
relativity is presented.


title: Convergence of densities of some functionals of Gaussian processes

abstract:
  The aim of this paper is to establish the uniform convergence of the
densities of a sequence of random variables, which are functionals of an
underlying Gaussian process, to a normal density. Precise estimates for the
uniform distance are derived by using the techniques of Malliavin calculus,
combined with Stein's method for normal approximation. We need to assume some
non-degeneracy conditions. First, the study is focused on random variables in a
fixed Wiener chaos, and later, the results are extended to the uniform
convergence of the derivatives of the densities and to the case of random
vectors in some fixed chaos, which are uniformly non-degenerate in the sense of
Malliavin calculus. Explicit upper bounds for the uniform norm are obtained for
random variables in the second Wiener chaos, and an application to the
convergence of densities of the least square estimator for the drift parameter
in Ornstein-Uhlenbeck processes is discussed.


title: Numerical solutions to the cosmological 3-fluid problem

abstract:
  We show that, for the scalar field cosmology with exponential potential, the
set of values of the coupling parameter for which the solutions undergo a
transient period of acceleration is much larger than the set discussed in the
literature. The gradual inclusion of ordinary and dark matters results in an
everywhere, but near the origin, smoother and right shifted (along the time
axis) acceleration curve. For the 3-fluid problem, the energy density need not
exhibit a plateau during the acceleration period. Much excess in the dark
matter and/or ordinary matter energy densities would lead the universe to
undergo an eternal deceleration expansion. For the 3-fluid problem with a
single exponential potential we conclude that the Big Bang Nucleosynthesis
constraint is not fulfilled if the universe is to undergo a transient period of
acceleration. The 3-fluid model remains a good approximation for the
description of large scale structures.


title: On the exact and $\varepsilon$-strong simulation of (jump) diffusions

abstract:
  This paper introduces a framework for simulating finite dimensional
representations of (jump) diffusion sample paths over finite intervals, without
discretisation error (exactly), in such a way that the sample path can be
restored at any finite collection of time points. Within this framework we
extend existing exact algorithms and introduce novel adaptive approaches. We
consider an application of the methodology developed within this paper which
allows the simulation of upper and lower bounding processes which almost surely
constrain (jump) diffusion sample paths to any specified tolerance. We
demonstrate the efficacy of our approach by showing that with finite
computation it is possible to determine whether or not sample paths cross
various irregular barriers, simulate to any specified tolerance the first
hitting time of the irregular barrier and simulate killed diffusion sample
paths.


title: From aether theory to Special Relativity

abstract:
  At the end of the 19th century light was regarded as an electromagnetic wave
propagating in a material medium called ether. The speed c appearing in
Maxwell's wave equations was the speed of light with respect to the ether.
Therefore, according to the Galilean addition of velocities, the speed of light
in the laboratory would differ from c. The measure of such difference would
reveal the motion of the laboratory (the Earth) relative to the ether (a sort
of absolute motion). However the Earth's absolute motion was never evidenced.
  Galileo addition of velocities is based on the assumption that lengths and
time intervals are invariant (independent of the state of motion). This way of
thinking the spacetime emanates from our daily experience and lies at the heart
of Newton's Classical Mechanics. Nevertheless, in 1905 Einstein defied Galileo
addition of velocities by postulating that light travels at the same speed c in
any inertial frame. In doing so, Einstein extended the principle of relativity
to the electromagnetic phenomena described by Maxwell's laws. In Einstein's
Special Relativity the ether does not exist and the absolute motion is devoid
of meaning. The invariance of the speed of light forced the replacement of
Galileo transformations with Lorentz transformations. Thus, relativistic length
contractions and time dilations entered our understanding of the spacetime.
Newtonian mechanics had to be reformulated, which led to the discovery of the
mass-energy equivalence.


title: Recovering the geometry of a flat spacetime from background radiation

abstract:
  We consider globally hyperbolic flat spacetimes in 2+1 and 3+1 dimensions, in
which a uniform light signal is emitted on the $r$-level surface of the
cosmological time for $r\to 0$. We show that the frequency of this signal, as
perceived by a fixed observer, is a well-defined, bounded function which is
generally not continuous. This defines a model with anisotropic background
radiation that contains information about initial singularity of the spacetime.
In dimension 2+1, we show that this observed frequency function is stable under
suitable perturbations of the spacetime, and that, under certain conditions, it
contains sufficient information to recover its geometry and topology. We
compute an approximation of this frequency function for a few simple examples.


title: Coloring Link Diagrams And Conway-type Polynomial Of Braids

abstract:
  In this paper we define and present a simple combinatorial formula for a
3-variable Laurent polynomial invariant of conjugacy classes in Artin braid
group $B_m$. We show that this Laurent polynomial satisfies the Conway skein
relation and its coefficients are Vassiliev invariants of braids.


title: Evidence for Large-N Phase Transitions in N=2* Theory

abstract:
  We solve, using localization, for the large-N master field of N=2*
super-Yang-Mills theory. From that we calculate expectation values of large
Wilson loops and the free energy on the four-sphere. At weak coupling, these
observables only receive non-perturbative contributions. The analytic solution
holds for a finite range of the 't Hooft coupling and terminates at the point
of a large-N phase transition. We find evidence that as the coupling is further
increased the theory undergoes an infinite sequence of similar transitions that
accumulate at infinity.


title:
Dilaton-scalar models in context of generalized affine gravity theories:
  their properties and integrability

abstract:
  Nowadays it is widely accepted that the evolution of the universe was driven
by some scalar degrees of freedom both on its early stage and at present. The
corresponding cosmological models often involve some scalar fields introduced
ad hoc. In this paper we cultivate a different approach, which is based on a
derivation of new scalar degrees of freedom from fundamental modifications of
Einstein's gravity. In elaboration of our previous work, we here investigate
properties of the dilaton-scalar gravity obtained by dimensional reductions of
a recently proposed affine generalized gravity theory. We show that these
models possess the same symmetries as related models of GR with ordinary scalar
fields. As a result, for a rather general class of dilaton-scalar gravity
models we construct additional first integrals and formulate an integral
equation well suited for solving by iterations.


title:
Equivariant deformations of Hamiltonian stationary Lagrangian
  submanifolds

abstract:
  We prove an equivariant deformation result for Hamiltonian stationary
Lagrangian submanifolds of a Kahler manifold, with respect to deformations of
its metric and almost complex structure that are compatible with an isometric
Hamiltonian group action. This yields existence of Hamiltonian stationary
Lagrangian submanifolds in possibly non-Kahler symplectic manifolds whose
metric is arbitrarily close to a Kahler metric.


title:
Escape of Lyman continuum radiation from local galaxies - Detection of
  leakage from the young starburst Tol 1247-232

abstract:
  The escape fraction of hydrogen ionizing photons (f_esc) from galaxies has
been suggested to be evolving with time, but the picture is far from clear.
While evidence for significant escape fractions has been found at high
redshifts in several studies, the picture looks different in the more nearby
universe. Here, we apply a new background subtraction routine on archival data
from the Far Ultraviolet Spectroscopic Explorer (FUSE), in order to study local
galaxies in search for possible Lyman Continuum (LyC) leakage. In the process,
for the first time a stacked spectrum in the LyC is produced for local
galaxies. With this small sample, we also make a more tentative approach to
look for possible correlations between f_esc and physical parameters such as
internal absorption E(B-V)_i, mass, H I mass, specific star formation rate
(SSFR), metallicity, and Ly-alpha emission. Eight star forming galaxies with
redshifts z > 0.015 from the FUSE archive were re-examined. Also, a sub-sample
of an additional four galaxies with lower redshifts were included, for which
the escape fraction was estimated from residual flux in the low ionization
interstellar C II(1036{\AA}) line. Out of the eight galaxies, only one was
found to have significant LyC leakage, Tol 1247-232 (S/N=5.2). This is the
second detection of a leaking galaxy in the local universe. We find an absolute
escape fraction for Tol 1247-232 of f_esc = 2.4(+0.9/-0.8) %. The stacked
sample show an excess in the LyC with f_esc = 1.4(+0.6/-0.5) %, but we note
that there might be important selection biases involved. With the small sample,
we suggest a possible trend for higher f_esc with lower mass and with enhanced
SSFR. None of the galaxies with high values of E(B-V)_i were found to show any
sign of leakage.


title:
Direct calculation of exciton binding energies with time-dependent
  density-functional theory

abstract:
  Excitons are electron-hole pairs appearing below the band gap in insulators
and semiconductors. They are vital to photovoltaics, but are hard to obtain
with time-dependent density-functional theory (TDDFT), since most standard
exchange-correlation (xc) functionals lack the proper long-range behavior.
Furthermore, optical spectra of bulk solids calculated with TDDFT often lack
the required resolution to distinguish discrete, weakly bound excitons from the
continuum. We adapt the Casida equation formalism for molecular excitations to
periodic solids, which allows us to obtain exciton binding energies directly.
We calculate exciton binding energies for both small- and large-gap
semiconductors and insulators, study the recently proposed bootstrap xc kernel
[S. Sharma et al., Phys. Rev. Lett. 107, 186401 (2011)], and extend the
formalism to triplet excitons.


title: Nucleosynthetic Constraints on the Mass of the Heaviest Supernovae

abstract:
  Assuming a Salpeter initial mass function and taking the solar abundances as
a representative sample, we explore the sensitivity of nucleosynthesis in
massive stars to the truncation of supernova explosions above a certain mass.
It is assumed that stars of all masses contribute to nucleosynthesis by their
pre-explosive winds, but above a certain limiting main sequence mass, the
presupernova star becomes a black hole and ejects nothing more. The solar
abundances from oxygen to atomic mass 90 are fit quite well assuming no cut-off
at all, i.e., by assuming all stars up to 120 solar masses make successful
supernovae. Little degradation in the fit occurs if the upper limit is reduced
to 25 solar masses. The limit can be further reduced, but the required event
rate of supernovae in the remaining range rises rapidly to compensate for the
lost nucleosynthesis of the more massive stars. The nucleosynthesis of the
s-process declines precipitously and the production of species made in the
winds, e.g., carbon, becomes unacceptably large compared with elements made in
the explosion, e.g., silicon and oxygen. However, by varying uncertain physics,
especially the mass loss rate for massive stars and the rate for the neon-22 to
magnesium-25 reaction rate, acceptable nucleosynthesis might still be achieved
with a cutoff as low as 18 solar masses. This would require a supernova
frequency three times greater than the fiducial value obtained when all stars
explode in order to produce the required oxygen-16. The nucleosynthesis of
iron-60 and aluminum-26 is also examined.


title: Spectrum Bandit Optimization

abstract:
  We consider the problem of allocating radio channels to links in a wireless
network. Links interact through interference, modelled as a conflict graph
(i.e., two interfering links cannot be simultaneously active on the same
channel). We aim at identifying the channel allocation maximizing the total
network throughput over a finite time horizon. Should we know the average radio
conditions on each channel and on each link, an optimal allocation would be
obtained by solving an Integer Linear Program (ILP). When radio conditions are
unknown a priori, we look for a sequential channel allocation policy that
converges to the optimal allocation while minimizing on the way the throughput
loss or {\it regret} due to the need for exploring sub-optimal allocations. We
formulate this problem as a generic linear bandit problem, and analyze it first
in a stochastic setting where radio conditions are driven by a stationary
stochastic process, and then in an adversarial setting where radio conditions
can evolve arbitrarily. We provide new algorithms in both settings and derive
upper bounds on their regrets.


title:
Ambitoric geometry I: Einstein metrics and extremal ambikaehler
  structures

abstract:
  We present a local classification of conformally equivalent but oppositely
oriented 4-dimensional Kaehler metrics which are toric with respect to a common
2-torus action. In the generic case, these "ambitoric" structures have an
intriguing local geometry depending on a quadratic polynomial q and arbitrary
functions A and B of one variable.
  We use this description to classify Einstein 4-metrics which are hermitian
with respect to both orientations, as well a class of solutions to the
Einstein-Maxwell equations including riemannian analogues of the
Plebanski-Demianski metrics. Our classification can be viewed as a riemannian
analogue of a result in relativity due to R. Debever, N. Kamran, and R.
McLenaghan, and is a natural extension of the classification of selfdual
Einstein hermitian 4-manifolds, obtained independently by R. Bryant and the
first and third authors.
  These Einstein metrics are precisely the ambitoric structures with vanishing
Bach tensor, and thus have the property that the associated toric Kaehler
metrics are extremal (in the sense of E. Calabi). Our main results also
classify the latter, providing new examples of explicit extremal Kaehler
metrics. For both the Einstein-Maxwell and the extremal ambitoric structures, A
and B are quartic polynomials, but with different conditions on the
coefficients. In the sequel to this paper we consider global examples, and use
them to resolve the existence problem for extremal Kaehler metrics on toric
4-orbifolds with second betti number b2=2.


title:
Effect of Heavy-Ion Irradiation on Superconductivity in Single Crystals
  of Ba0.6K0.4Fe2As2 Pnictide Superconductor

abstract:
  The London penetration depth was measured in optimally doped Ba0.6K0.4Fe2As2
crystals, with and without columnar defects produced by 1.4 GeV 208Pb
irradiation. The low temperature behavior of unirradiated samples was
consistent with a fully gapped superconducting state with a minimum energy gap
delta_min/(k_B T_C) = 1. Similar gap values were observed for irradiation
levels corresponding to mean column-column separations of 32 nm and 22 nm. At
very high irradiation levels (column-column separation of 10 nm) a T^2 power
law was observed below Tc/3, most likely due to elevated scattering. Neither
the location nor the sharpness of the superconducting transition was affected
by irradiation. The data provides evidence for an s+/- pairing state.


title: Utilizing Protein Structure to Identify Non-Random Somatic Mutations

abstract:
  Motivation: Human cancer is caused by the accumulation of somatic mutations
in tumor suppressors and oncogenes within the genome. In the case of oncogenes,
recent theory suggests that there are only a few key "driver" mutations
responsible for tumorigenesis. As there have been significant pharmacological
successes in developing drugs that treat cancers that carry these driver
mutations, several methods that rely on mutational clustering have been
developed to identify them. However, these methods consider proteins as a
single strand without taking their spatial structures into account. We propose
a new methodology that incorporates protein tertiary structure in order to
increase our power when identifying mutation clustering.
  Results: We have developed a novel algorithm, iPAC: identification of Protein
Amino acid Clustering, for the identification of non-random somatic mutations
in proteins that takes into account the three dimensional protein structure. By
using the tertiary information, we are able to detect both novel clusters in
proteins that are known to exhibit mutation clustering as well as identify
clusters in proteins without evidence of clustering based on existing methods.
For example, by combining the data in the Protein Data Bank (PDB) and the
Catalogue of Somatic Mutations in Cancer, our algorithm identifies new
mutational clusters in well known cancer proteins such as KRAS and PI3KCa.
Further, by utilizing the tertiary structure, our algorithm also identifies
clusters in EGFR, EIF2AK2, and other proteins that are not identified by
current methodology.


title:
The Trispectrum as a Diagnostic of Primordial Orthogonal
  non-Gaussianities

abstract:
  In single-field inflationary models with a low sound speed, the orthogonal
shape of the primordial bispectrum arises due to partial cancellations between
equilateral-type shapes. This fact allows for a speed of sound c_s as low as
about 0.01, which is actually weakly preferred by WMAP data. For such values,
the trispectrum, scaling like 1/c_s^4, is of order 10^8 and is therefore
comparable to, and greater than, the 1 sigma observational bound t_NL^eq=(-3.11
+- 7.5)*10^6. Hence, the trispectrum is already constraining inflationary
mechanisms candidates for generating an orthogonal bispectrum at the level
hinted in WMAP data. If this signal persists in imminent Planck data, most of
the parameter space of the simplest effective field theory of inflation will be
under observational pressure, while a dedicated analysis will be needed for the
substantial fraction of parameter space where we show that a qualitatively new,
orthogonal, trispectrum naturally arises.


title: Ambitoric geometry II: Extremal toric surfaces and Einstein 4-orbifolds

abstract:
  We provide an explicit resolution of the existence problem for extremal
Kaehler metrics on toric 4-orbifolds M with second Betti number b2(M)=2. More
precisely we show that M admits such a metric if and only if its rational
Delzant polytope (which is a labelled quadrilateral) is K-polystable in the
relative, toric sense (as studied by S. Donaldson, E. Legendre, G. Szekelyhidi
et al.). Furthermore, in this case, the extremal Kaehler metric is ambitoric,
i.e., compatible with a conformally equivalent, oppositely oriented toric
Kaehler metric, which turns out to be extremal as well. These results provide a
computational test for the K-stability of labelled quadrilaterals.
  Extremal ambitoric structures were classified locally in Part I of this work,
but herein we only use the straightforward fact that explicit Kaehler metrics
obtained there are extremal, and the identification of Bach-flat (conformally
Einstein) examples among them. Using our global results, the latter yield
countably infinite families of compact toric Bach-flat Kaehler orbifolds,
including examples which are globally conformally Einstein, and examples which
are conformal to complete smooth Einstein metrics on an open subset, thus
extending the work of many authors.


title: Gravitational Tension and Thermodynamics of Planar AdS Spacetimes

abstract:
  We derive new thermodynamic relations for asymptotically planar AdS black
hole and soliton solutions. In addition to the ADM mass, these spacetimes are
characterized by gravitational tensions in each of the planar spatial
directions. We show that with planar AdS asymptotics, the sum of the ADM mass
and tensions necessarily vanishes, as one would expect from the AdS /CFT
correspondence. Each Killing vector of such a spacetime leads to a Smarr
formula relating the ADM mass and tensions, the black hole horizon and soliton
bubble areas, and a set of thermodynamic volumes that arise due to the
non-vanishing cosmological constant. These Smarr relations display an
interesting symmetry between black holes and bubbles, being invariant under the
simultaneous interchange of the mass and black hole horizon area with the
tension and soliton bubble area. This property may indicate a symmetry between
the confining and deconfined phases of the dual gauge theory.


title: On the galaxy spiral arms' nature as revealed by rotation frequencies

abstract:
  High resolution N-body simulations using different codes and initial
condition techniques reveal two different behaviours for the rotation frequency
of transient spiral arms like structures. Whereas unbarred disks present spiral
arms nearly corotatingwith disk particles, strong barred models (bulged or
bulge-less) quickly develop a bar-spiral structure dominant in density, with a
pattern speed almost constant in radius. As the bar strength decreases the arm
departs from bar rigid rotation and behaves similar to the unbarred case. In
strong barred models we detect in the frequency space other subdominant and
slower modes at large radii, in agreement with previous studies, however we
also detect them in the configuration space. We propose that the distinctive
behaviour of the dominant spiral modes can be exploited in order to constraint
the nature of Galactic spiral arms by the astrometric survey GAIA and by 2-D
spectroscopic surveys like CALIFA and MANGA in external galaxies.


title: The Variety of Solutions for Dynamics in the Local Group

abstract:
  This exploration of solutions for the orbits of Local Group galaxies under
the cosmological initial condition of growing peculiar velocities and fitted to
measured distances, redshifts, and proper motions reveals a considerable
variety of histories allowed by present constraints. The solutions also point
to computations and measurements at the current level of precision that may
lead to a more accurate picture of Local Group dynamics, or perhaps point to
adjustments of our simple picture of the arrangement of mass within the Local
Group.


title: Teleparallelism: A New Insight Into Gravity

abstract:
  Teleparallel gravity, a gauge theory for the translation group, turns up as
fully equivalent to Einstein's general relativity. In spite of this
equivalence, it provides a whole new insight into gravitation. It breaks
several paradigms related to the geometric approach of general relativity, and
introduces new concepts in the description of the gravitational interaction.
The purpose of this chapter is to explore some of these concepts, as well as
discuss possible consequences for gravitation, mainly those that could be
relevant for the quantization of the gravitational field.


title:
Discontinuous Galerkin finite element differential calculus and
  applications to numerical solutions of linear and nonlinear partial
  differential equations

abstract:
  This paper develops a discontinuous Galerkin (DG) finite element differential
calculus theory for approximating weak derivatives of Sobolev functions and
piecewise Sobolev functions. By introducing numerical one-sided derivatives as
building blocks, various first and second order numericaloperators such as the
gradient, divergence, Hessian, and Laplacian operator are defined, and their
corresponding calculus rules are established. Among the calculus rules are
product and chain rules, integration by parts formulas and the divergence
theorem. Approximation properties and the relationship between the proposed DG
finite element numerical derivatives and some well-known finite difference
numerical derivative formulas on Cartesian grids are also established.
Efficient implementation of the DG finite element numerical differential
operators is also proposed. Besides independent interest in numerical
differentiation, the primary motivation and goal of developing the DG finite
element differential calculus is to solve partial differential equations. It is
shown that several existing finite element, finite difference and DG methods
can be rewritten compactly using the proposed DG finite element differential
calculus framework. Moreover, new DG methods for linear and nonlinear PDEs are
also obtained from the framework.


title: Valence-band effective-potential evolution for coupled holes

abstract:
  We present the metamorphosis in the effective-potential profile of layered
heterostructures, for several III-V semiconductor binary compounds, when the
band mixing of light and heavy holes increases. A root-locus-like procedure, is
directly applied to an eigenvalue quadratic problem obtained from a
multichannel system of coupled modes, in the context of multiband effective
mass approximation. By letting grow valence-band mixing, it is shown the
standard fixed-height rectangular potential-energy for the scatterer
distribution, to be a reliable test-run input for heavy holes. On the contrary,
this scheme is no longer valid for light holes and a mutable effective
\emph{band offset} profile has to be considered instead, whenever the in-plane
kinetic energy changes.


title:
\delta N Formalism in Anisotropic Inflation and Large Anisotropic
  Bispectrum and Trispectrum

abstract:
  We present a consistent \delta N formalism for curvature perturbations in
anisotropic cosmological backgrounds. We employ our \delta N formalism to
calculate the power spectrum, the bispectrum and the trispectrum in models of
anisotropic inflation with the background gauge fields in Bianchi I universe.
Our results coincide exactly with the recent results obtained from in-in
formalism. To satisfy the observational constraints the anisotropies generated
on power spectrum are kept small but large orientation-dependent
non-Gaussianities can be generated. We study the Suyama-Yamaguchi inequality
for the amplitudes of the bispectrum and the trispectrum in the presence of
anisotropic shapes.


title: Measuring the configurational temperature of a binary disc packing

abstract:
  Jammed packings of granular materials differ from systems normally described
by statistical mechanics in that they are athermal. In recent years a
statistical mechanics of static granular media has emerged where the
thermodynamic temperature is replaced by a configurational temperature X which
describes how the number of mechanically stable configurations depends on the
volume. Four different methods have been suggested to measure X. Three of them
are computed from properties of the Voronoi volume distribution, the fourth
takes into account the contact number and the global volume fraction. This
paper answers two questions using experimental binary disc packings: First we
test if the four methods to measure compactivity provide identical results when
applied to the same dataset. We find that only two of the methods agree
quantitatively. Secondly, we test if X is indeed an intensive variable; this
becomes true only for samples larger than roughly 200 particles. This result is
shown to be due to recently found correlations between the particle volumes
[Zhao et al., Europhys. Lett., 2012, 97, 34004].


title:
Gold particle quantification in immuno-gold labelled sections for
  transmission electron microscopy

abstract:
  We briefly outline an algorithm for accurate quantification of specific
binding of gold particles to fixed biological tissue samples prepared for
immuno-transmission electron microscopy (TEM). The algorithm is based on
existing protocols for rational accounting of colloidal gold particles used in
secondary antibodies for immuno-gold labeling.


title: The Bayesian Approach To Inverse Problems

abstract:
  These lecture notes highlight the mathematical and computational structure
relating to the formulation of, and development of algorithms for, the Bayesian
approach to inverse problems in differential equations. This approach is
fundamental in the quantification of uncertainty within applications involving
the blending of mathematical models with data.