title: Continuum Hamiltonian Hopf Bifurcation II

abstract:
  Building on the development of [MOR13], bifurcation of unstable modes that
emerge from continuous spectra in a class of infinite-dimensional noncanonical
Hamiltonian systems is investigated. Of main interest is a bifurcation termed
the continuum Hamiltonian Hopf (CHH) bifurcation, which is an
infinite-dimensional analog of the usual Hamiltonian Hopf (HH) bifurcation.
Necessary notions pertaining to spectra, structural stability, signature of the
continuous spectra, and normal forms are described. The theory developed is
applicable to a wide class of 2+1 noncanonical Hamiltonian matter models, but
the specific example of the Vlasov-Poisson system linearized about homogeneous
(spatially independent) equilibria is treated in detail. For this example,
structural (in)stability is established in an appropriate functional analytic
setting, and two kinds of bifurcations are considered, one at infinite and one
at finite wavenumber. After defining and describing the notion of dynamical
accessibility, Kre\u{i}n-like theorems regarding signature and bifurcation are
proven. In addition, a canonical Hamiltonian example, composed of a negative
energy oscillator coupled to a heat bath, is treated and our development is
compared to pervious work in this context. A careful counting of eigenvalues,
with and without symmetry, is undertaken, leading to the definition of a
degenerate continuum steady state (CSS) bifurcation. It is described how the
CHH and CSS bifurcations can be viewed as linear normal forms associated with
the nonlinear single-wave model described in [BAL13], which is a companion to
the present work and that of [MOR13].

categories: math-ph math.DS math.MP physics.flu-dyn physics.plasm-ph


title:
Characterization of the Young Open Cluster G144.9+0.4 in the
  Camelopardalis OB1 Association

abstract:
  Our star-count analysis of the Two Micron All Sky Survey point sources
resulted in an identification of the star cluster G144.9+0.4. The cluster was
found, but not characterized, by Glushkova et al. We show that the cluster is
physically associated with the Cam OB1 association at a distance of about 1 kpc
and with an age of 1-2 Myr. Pre-main sequence stars are identified on the basis
of photometric and proper motion data. A total of 91 additional OB star
candidates was found in subgroups 1A and 1B, a significant increase from the
currently known 43 OB stars. The OB members show an age spread that indicates a
sustained star formation for at least the last 10-15 Myr. The young cluster
G144.9+0.4 represents the latest episode of sequential star formation in this
cloud complex.


title: Integral geometry of unitary area measures

abstract:
  The existence of kinematic formulas for area measures with respect to any
connected, closed subgroup of the orthogonal group acting transitively on the
unit sphere is established. In particular, the kinematic operator for area
measures is shown to have the structure of a co-product. In the case of the
unitary group the algebra associated to this co-product is described explicitly
in terms of generators and relations. As a consequence, a simple algorithm that
yields explicit kinematic formulas for unitary area measures is obtained.


title: The Role of Dimensional Analysis in Teaching Physics

abstract:
  Dimensional analysis is a simple qualitative method for determining essential
connections between physical quantities. It is applicable to a multitude of
physics problems, many of which canbe introduced early on in a university
physics curriculum. Despite the relative simplicity of theapproach, it is
rarely included in physics curricula. Here, we apply dimensional analysis to
find the radiated power from an electric dipole. Employing dimensional
analysis, we demonstrate a straightforward way to derive the latter without the
need for complex mathematical treatments.


title:
Atom-canonicity, relativized representations and omitting types for
  clique guarded semantics and guarded logics

abstract:
  We study atom canonicity for several varieties of cylindric like algebras
that contain properly the variety of representable algebras. The algebras in
such varieties have relativized representations, and we thereby obtain many
omitting types theorems, both negative and positive for finite variable
fragments and / or modifications of first order logic. Negative results are
obtained when we keep usual syntax and relativize models (so that they witness
commutativity of quantifiers only locally) and positive ones are obtained when
we weaken 'commutativity of quantifiers' in the syntax and relativize semantics
differently.
  Such algebras have weak neat embedding properties, too, in the sense that
they embed into neat reducts of algebras in higher dimensions possibly finite.
In the second part of the paper various notions of representability originally
formulated for atom structure are lifted in an obvious way to the algebra
level, like weak and strong representability. Such classes of algebras (that
are atomic) are characterized completely via neat embeddings.
  Finally, several model theoretic questions on such classes consisting of
algebras having weak neat embedding properties and relativized representations,
like decidability of their equational or universal theory, their finite
axiomatizability if first order definable, are posed and answered.


title: Bidimensionality of Geometric Intersection Graphs

abstract:
  Let B be a finite collection of geometric (not necessarily convex) bodies in
the plane. Clearly, this class of geometric objects naturally generalizes the
class of disks, lines, ellipsoids, and even convex polygons. We consider
geometric intersection graphs GB where each body of the collection B is
represented by a vertex, and two vertices of GB are adjacent if the
intersection of the corresponding bodies is non-empty. For such graph classes
and under natural restrictions on their maximum degree or subgraph exclusion,
we prove that the relation between their treewidth and the maximum size of a
grid minor is linear. These combinatorial results vastly extend the
applicability of all the meta-algorithmic results of the bidimensionality
theory to geometrically defined graph classes.


title: Analytic PSF Correction for Gravitational Flexion Studies

abstract:
  Given a galaxy image, one cannot simply measure its flexion. An image's spin
one and three shape properties, typically associated with F- and G-flexion, are
actually complicated functions of the galaxy's intrinsic shape and the
telescope's PSF, in addition to the lensing properties. The same is true for
shear. In this work we create a completely analytic mapping from apparent
measured galaxy flexions to gravitational flexions by (1) creating simple
models for a lensed galaxy and for a PSF whose distortions are dominated by
atmospheric smearing and optical aberrations, (2) convolving the two models,
and (3) comparing the pre- and post-convolved flexion-like shape variations of
the final image. For completeness, we do the same for shear. As expected,
telescope astigmatism, coma, and trefoil can corrupt measurements of shear, F-
flexion, and G-flexion, especially for small galaxies. We additionally find
that PSF size dilutes the flexion signal more rapidly than the shear signal.
Moreover, mixing between shears, flexions, and asymmetric aberrations can
create additive offsets in lensing measurements that vary with both galaxy size
and galaxy ellipticity and flexion values. But all is not lost; by measuring
the patterns, we can correct for them.


title: Jet dynamics. Recollimation shocks and helical patterns

abstract:
  The dynamics and stability of extragalactic jets may be strongly influenced
by small (and probable) differences in pressure between the jet and the ambient
and within the jet itself. The former give rise to expansion and recollimation
of the jet. This occurs in the form of conical shocks, or Mach disks, if the
pressure difference is large enough. Pressure asymmetries within the jet may
trigger the development of helical patterns via coupling to kink current-driven
instability, or to helical Kelvin-Helmholtz instability, depending on the
physical conditions in the jet. I summarize here the evidence collected during
the last years on the presence of recollimation shocks and waves in jets. In
the jet of CTA 102 evidence has been found for (traveling)shock-(standing)shock
interaction in the core-region (0.1 mas from the core), using information from
the light-curve of the source combined with VLBI data. The conclusions derived
have been confirmed by numerical simulations combined with emission
calculations that have allowed to study the spectral evolution of the perturbed
jet. Helical structures can also be identified in radio-jets. The ridge-line of
emission of the jet of S5~0836+710 has been identified as a physical structure
corresponding to a wave developing in the jet flow. I review here the evidence
that has allowed to reach this conclusion, along with an associated caveat.
Current data do not allow to distinguish between magnetic or hydrodynamical
instabilities. I finally discuss the importance of these linear and non-linear
waves for jet evolution.


title: On string topology of classifying spaces

abstract:
  Let G be a compact Lie group. By work of Chataur and Menichi, the homology of
the space of free loops in the classifying space of G is known to be the value
on the circle in a homological conformal field theory. This means in particular
that it admits operations parameterized by homology classes of classifying
spaces of diffeomorphism groups of surfaces. Here we present a radical
extension of this result, giving a new construction in which diffeomorphisms
are replaced with homotopy equivalences, and surfaces with boundary are
replaced with arbitrary spaces homotopy equivalent to finite graphs. The result
is a novel kind of field theory which is related to both the diffeomorphism
groups of surfaces and the automorphism groups of free groups with boundaries.
Our work shows that the algebraic structures in string topology of classifying
spaces can be brought into line with, and in fact far exceed, those available
in string topology of manifolds. For simplicity, we restrict to the
characteristic 2 case. The generalization to arbitrary characteristic will be
addressed in a subsequent paper.


title:
Superconducting energy gap versus pseudogap in hole-doped cuprates as
  revealed by infrared spectroscopy

abstract:
  We present in-plane infrared reflectance measurement on two superconducting
cuprates with relatively low T$_c$: a nearly optimally-doped
Bi$_2$Sr$_{1.6}$La$_{0.4}$CuO$_{6+\delta}$ with T$_c$=33 K and an underdoped
La$_{1.89}$Sr$_{0.11}$CuO$_4$ with T$_c$=30 K. The measurement clearly reveals
that the superconducting energy gap is distinct from the pseudogap. They have
different energy scales and appear at different temperatures. The results
suggest that the pseudogap is not a precursor to the superconducting state. The
data also challenge the longstanding viewpoint that the superconductivity
within the ab-plane is in the clean limit and the superconducting pairing
energy gap could not be detected by in-plane infrared spectroscopy.


title:
Reconnections of quantized vortex rings in superfluid $^4$He at very low
  temperatures

abstract:
  Collisions in a beam of unidirectional quantized vortex rings of nearly
identical radii $R$ in superfluid $^4$He in the limit of zero temperature (0.05
K) were studied using time-of-flight spectroscopy. Reconnections between two
primary rings result in secondary vortex loops of both smaller and larger
radii. Discrete steps in the distribution of flight times, due to the limits on
the earliest possible arrival times of secondary loops created after either one
or two consecutive reconnections, are observed. The density of primary rings
was found to be capped at the value $500{\rm \,cm}^{-2} R^{-1}$ independent of
the injected density. This is due to collisions between rings causing piling-up
of many other vortex rings. Both observations are in quantitative agreement
with our theory.


title: Some Remarks on Kite Pseudo Effect Algebras

abstract:
  Recently a new family of pseudo effect algebras, called kite pseudo effect
algebras, was introduced. Such an algebra starts with a po-group $G$, a set $I$
and with two bijections $\lambda,\rho:I \to I.$ Using a clever construction on
the ordinal sum of $(G^+)^I$ and $(G^-)^I,$ we can define a pseudo effect
algebra which can be non-commutative even if $G$ is an Abelian po-group. In the
paper we give a characterization of subdirect product of subdirectly
irreducible kite pseudo effect algebras, and we show that every kite pseudo
effect algebra is an interval in a unital po-loop.


title: VERITAS contributions to the 33rd International Cosmic Ray Conference

abstract:
  Compilation of papers contributed by the VERITAS Collaboration to the 33rd
International Cosmic Ray Conference, held 2-9 July, 2013, in Rio de Janeiro,
Brazil.


title:
Generating Entangled Spin States for Quantum Metrology by Single-Photon
  Detection

abstract:
  We propose and analyze a probabilistic but heralded scheme to generate pure,
entangled, non-Gaussian states of collective spin in large atomic ensembles by
means of single-photon detection. One photon announces the preparation of a
Dicke state, while two or more photons announce Schr\"odinger cat states. The
method produces pure states even for finite photon detection efficiency and
weak atom-photon coupling. The entanglement generation can be made
quasi-deterministic by means of repeated trial and feedback, enabling metrology
beyond the standard quantum limit.


title: Connections Between Construction D and Related Constructions of Lattices

abstract:
  Most practical constructions of lattice codes with high coding gains are
multilevel constructions where each level corresponds to an underlying code
component. Construction D, Construction D$'$, and Forney's code formula are
classical constructions that produce such lattices explicitly from a family of
nested binary linear codes. In this paper, we investigate these three closely
related constructions along with the recently developed Construction A$'$ of
lattices from codes over the polynomial ring $\mathbb{F}_2[u]/u^a$. We show
that Construction by Code Formula produces a lattice packing if and only if the
nested codes being used are closed under Schur product, thus proving the
similarity of Construction D and Construction by Code Formula when applied to
Reed-Muller codes. In addition, we relate Construction by Code Formula to
Construction A$'$ by finding a correspondence between nested binary codes and
codes over $\mathbb{F}_2[u]/u^a$. This proves that any lattice constructible
using Construction by Code Formula is also constructible using Construction
A$'$. Finally, we show that Construction A$'$ produces a lattice if and only if
the corresponding code over $\mathbb{F}_2[u]/u^a$ is closed under shifted Schur
product.


title: First Look at the Physics Case of TLEP

abstract:
  The discovery by the ATLAS and CMS experiments of a new boson with mass
around 125 GeV and with measured properties compatible with those of a
Standard-Model Higgs boson, coupled with the absence of discoveries of
phenomena beyond the Standard Model at the TeV scale, has triggered interest in
ideas for future Higgs factories. A new circular e+e- collider hosted in a 80
to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far.
It has a clean experimental environment, produces high luminosity for
top-quark, Higgs boson, W and Z studies, accommodates multiple detectors, and
can reach energies up to the t-tbar threshold and beyond. It will enable
measurements of the Higgs boson properties and of Electroweak Symmetry-Breaking
(EWSB) parameters with unequalled precision, offering exploration of physics
beyond the Standard Model in the multi-TeV range. Moreover, being the natural
precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it
builds up a long-term vision for particle physics. Altogether, the combination
of TLEP and the VHE-LHC offers, for a great cost effectiveness, the best
precision and the best search reach of all options presently on the market.
This paper presents a first appraisal of the salient features of the TLEP
physics potential, to serve as a baseline for a more extensive design study.


title: Low Mach Asymptotic Preserving Scheme for the Euler-Korteweg Model

abstract:
  We present an all speed scheme for the Euler-Korteweg model. We study a
semi-implicit time-discretisation which treats the terms, which are stiff for
low Mach numbers, implicitly and thereby avoids a dependence of the timestep
restriction on the Mach number. Based on this we present a fully discrete
finite difference scheme. In particular, the scheme is asymptotic preserving,
i.e., it converges to a stable discretisation of the incompressible limit of
the Euler-Korteweg model when the Mach number tends to zero.


title: Russian meteorite Bronze Age (rock record)

abstract:
  This paper presents the results of a study of petroglyphs found in the
quartzite grotto near the Skelnovsky small village in the Northern Black Sea in
the South of Russia. The aim of the study was the analysis and interpretation
of the Early Bronze Age petroglyphs using archaeoastronomical methods. The
article presents a comparative analysis of Skelnovsky grotto ancient images and
contemporary eyewitness accounts of the Sikhote-Alin meteorite fall and
meteorite shower. Some petroglyphs were interpreted by us using ethnographic
and folklore material. In this study, the magnetic declination for the
geographical coordinates Skelnovsky farm was calculated, and the projection of
the whole picture Skelnovskih petroglyphs on the topographical map of the area
was built. The proposed location of the meteorite fall was determined with this
projection. It is confirmed by satellite pictures, on which are the
distinguishable terrain features, typical for the meteorite fall, are visible
including the possible impact crater, and the corresponding symbols on a
topographical map. The studies in the article conclude the astronomical
character of the main content of the Skelnovsky petroglyphs picture which
depicts the fall of a large meteoroid (bolide), similar to the Sikhote-Alin
meteorite, accompanied by a meteorite shower. After a comparative analysis of
the images in Sklenovsky Grotto it was discovered that the petroglyph is a copy
of the figure depicted on the famous Mesopotamic clay tablet YBC 7289. We
speculate that this figure is a prototype of an important building used either
for ritual or farm purposes, typical for the Bronze Age and distributed as in
Mesopotamia, as also on the coast of the Northern Black Sea. archaeoastronomy,
petroglyphs, rock art, meteoroid, meteorite shower, impact crater, Babylonian
clay tablet YBC 7289


title: PT-symmetry broken by point-group symmetry

abstract:
  We discuss a PT-symmetric Hamiltonian with complex eigenvalues. It is based
on the dimensionless Schr\"{o}dinger equation for a particle in a square box
with the PT-symmetric potential $V(x,y)=iaxy$. Perturbation theory clearly
shows that some of the eigenvalues are complex for sufficiently small values of
$|a|$. Point-group symmetry proves useful to guess if some of the eigenvalues
may already be complex for all values of the coupling constant. We confirm
those conclusions by means of an accurate numerical calculation based on the
diagonalization method. On the other hand, the Schr\"odinger equation with the
potential $V(x,y)=iaxy^{2}$ exhibits real eigenvalues for sufficiently small
values of $|a|$. Point group symmetry suggests that PT-symmetry may be broken
in the former case and unbroken in the latter one.


title:
Generic Off--Diagonal Solutions and Solitonic Hierarchies in Einstein
  and Modified Gravity

abstract:
  We summarize some our recent results on encoding exact solutions of field
equations in Einstein and modified gravity theories into solitonic hierarchies
derived for nonholonomic curve flows with associated bi-Hamilton structure. We
argue that there is a canonical distinguished connection for which the
fundamental geometric/ physical equations decouple in general form. This allows
us to construct very general classes of generic off-diagonal solutions
determined by corresponding types of generating and integration functions
depending on all (spacetime) coordinates. If the integral varieties are
constrained to zero torsion configurations, we can extract solutions for the
general relativity theory. We conclude that the geometric and physical data for
various classes of effective/modified Einstein spaces can be encoded into
multi-component versions of the sine-Gordon, or modified Korteweg - de Vries
equations.


title:
Bayesian Conditional Gaussian Network Classifiers with Applications to
  Mass Spectra Classification

abstract:
  Classifiers based on probabilistic graphical models are very effective. In
continuous domains, maximum likelihood is usually used to assess the
predictions of those classifiers. When data is scarce, this can easily lead to
overfitting. In any probabilistic setting, Bayesian averaging (BA) provides
theoretically optimal predictions and is known to be robust to overfitting. In
this work we introduce Bayesian Conditional Gaussian Network Classifiers, which
efficiently perform exact Bayesian averaging over the parameters. We evaluate
the proposed classifiers against the maximum likelihood alternatives proposed
so far over standard UCI datasets, concluding that performing BA improves the
quality of the assessed probabilities (conditional log likelihood) whilst
maintaining the error rate.
  Overfitting is more likely to occur in domains where the number of data items
is small and the number of variables is large. These two conditions are met in
the realm of bioinformatics, where the early diagnosis of cancer from mass
spectra is a relevant task. We provide an application of our classification
framework to that problem, comparing it with the standard maximum likelihood
alternative, where the improvement of quality in the assessed probabilities is
confirmed.


title: Gromov-Witten theory of target curves and the tautological ring

abstract:
  In the Gromov-Witten theory of a target curve we consider descendent
integrals against the virtual fundamental class relative to the forgetful
morphism to the moduli space of curves. We show that cohomology classes
obtained in this way lie in the tautological ring.


title:
Electric-field-induced metal maintained by current of the Mott insulator
  Ca2RuO4

abstract:
  Recently, application of electric field (E-field) has received considerable
attention as a new method to induce novel quantum phenomena since application
of E-field can tune the electronic states directly with obvious scientific and
industrial advantages over other turning methods. However, E-field-induced Mott
transitions are rare and typically require high E-field and low temperature.
Here we report that the multiband Mott insulator Ca2RuO4 shows unique
insulator-metal switching induced by applying a dry-battery level voltage at
room temperature. The threshold field Eth ~40 V/cm is much weaker than the Mott
gap energy. Moreover, the switching is accompanied by a bulk structural
transition. Perhaps the most peculiar of the present findings is that the
induced metal can be maintained to low temperature by a weak current.


title:
The photon polarization tensor in a homogeneous magnetic or electric
  field

abstract:
  We revisit the photon polarization tensor in a homogeneous external magnetic
or electric field. The starting point of our considerations is the momentum
space representation of the one-loop photon polarization tensor in the presence
of a homogeneous electromagnetic field, known in terms of a double parameter
integral. Our focus is on explicit analytical insights for both on- and
off-the-light-cone dynamics in a wide range of well-specified physical
parameter regimes, ranging from the perturbative to the manifestly
nonperturbative strong field regime. The basic ideas underlying
well-established approximations to the photon polarization tensor are carefully
examined and critically reviewed. In particular, we systematically keep track
of all contributions, both the ones to be neglected and those to be taken into
account explicitly, to all orders. This allows us to study their ranges of
applicability in a much more systematic and rigorous way. We point out the
limitations of such approximations and manage to go beyond at several
instances.


title: Interpreting the Role of the Magnetic Field from Dust Polarization Maps

abstract:
  Dust polarization observations from the Submillimeter Array (SMA) and the
Caltech Submillimeter Observatory (CSO) are analyzed with the goal of providing
a general tool to interpret the role of the magnetic field in molecular clouds.
Magnetic field and dust emission gradient orientations are observed to show
distinct patterns and features. The angle $\delta$ between these two
orientations can be interpreted as a magnetic field alignment deviation,
assuming the emission gradient orientation to coincide with the density
gradient orientation in the magnetohydrodynamics (MHD) force equation. In SMA
high-resolution (collapsing) cores, additional symmetry properties in $\delta$
can reveal accretion and outflow zones. All these observational findings
suggest the angle $\delta$ to be a relevant quantity that can assess the role
of the magnetic field. Indeed, when comparing this angle with the
(projection-free) magnetic field significance \Sigma_B (Koch et al. 2012a), it
is demonstrated that |\delta| yields an approximation to the change in
\Sigma_B. Thus, changes in the magnetic field alignment deviation $\delta$
trace changes in the role of the magnetic field. The angle $\delta$ is
observationally straightforward to determine, providing a tool to distinguish
between zones of minor or significant magnetic field impact. This is
exemplified by the CSO M+0.25+0.01, Mon R2, CO+0.02-0.02, M-0.02-0.07 sources
and by the SMA high-resolution data from W51 e2, W51 North, Orion BN/KL and
g5.89. Additional CSO sources are analyzed, providing further support of this
result. Finally, based on the different features found in our sample of 31
sources in total, covering sizes from large-scale complexes to collapsing
cores, a schematic evolutionary scenario is proposed (abridged).


title:
Cosmological Parameter Estimation with Large Scale Structure
  Observations

abstract:
  We estimate the sensitivity of future galaxy surveys to cosmological
parameters, using the redshift dependent angular power spectra of galaxy number
counts, $C_\ell(z_1,z_2)$, calculated with all relativistic corrections at
first order in perturbation theory. We pay special attention to the redshift
dependence of the non-linearity scale and present Fisher matrix forecasts for
Euclid-like and DES-like galaxy surveys. We compare the standard $P(k)$
analysis with the new $C_\ell(z_1,z_2)$ method. We show that for surveys with
photometric redshifts the new analysis performs significantly better than the
$P(k)$ analysis. For spectroscopic redshifts, however, the large number of
redshift bins which would be needed to fully profit from the redshift
information, is severely limited by shot noise. We also identify surveys which
can measure the lensing contribution and we study the monopole, $C_0(z_1,z_2)$.


title: Camina pairs that are not $p$-closed

abstract:
  We show for every prime $p$ that there exists a Camina pair $(G,N)$ where $N$
is a $p$-group and $G$ is not $p$-closed.


title:
Numerical identification of a nonlinear diffusion law via regularization
  in Hilbert scales

abstract:
  We consider the reconstruction of a diffusion coefficient in a quasilinear
elliptic problem from a single measurement of overspecified Neumann and
Dirichlet data. The uniqueness for this parameter identification problem has
been established by Cannon and we therefore focus on the stable solution in the
presence of data noise. For this, we utilize a reformulation of the inverse
problem as a linear ill-posed operator equation with perturbed data and
operators. We are able to explicitly characterize the mapping properties of the
corresponding operators which allow us to apply regularization in Hilbert
scales. We can then prove convergence and convergence rates of the regularized
reconstructions under very mild assumptions on the exact parameter. These are,
in fact, already needed for the analysis of the forward problem and no
additional source conditions are required. Numerical tests are presented to
illustrate the theoretical statements.


title: Dispersion based beam tilt correction

abstract:
  In Free Electron Lasers (FEL), a transverse centroid misalignment of
longitudinal slices in an electron bunch reduces the effective overlap between
radiation field and electron bunch and therefore the FEL performance. The
dominant sources of slice misalignments for FELs are the incoherent and
coherent synchrotron radiation within bunch compressors as well as transverse
wake fields in the accelerating cavities. This is of particular importance for
over-compression which is required for one of the key operation modes for the
SwissFEL planned at the Paul Scherrer Institute.
  The centroid shift is corrected using corrector magnets in dispersive
sections, e.g. the bunch compressors. First and second order corrections are
achieved by pairs of sextupole and quadrupole magnets in the horizontal plane
while skew quadrupoles correct to first order in the vertical plane.
Simulations and measurements at the SwissFEL Injector Test Facility are done to
investigate the proposed correction scheme for SwissFEL. This paper presents
the methods and results obtained.


title:
Curvature-induced Rashba spin-orbit interaction in strain-driven
  nanostructures

abstract:
  We derive the effective dimensionally reduced Schr\"odinger equation with
spin-orbit interaction in low-dimensional electronic strain driven
nanostructures. A method of adiabatic separation among fast normal quantum
degrees of freedom and slow tangential quantum degrees of freedom is used to
show the emergence of a strain-induced Rashba-like spin-orbit interaction
(SOI). By applying this analysis to one-dimensional curved quantum wires we
demonstrate that the curvature-induced Rashba SOI leads to enhanced spin-orbit
effects.


title: Picard--Vessiot structures

abstract:
  We demonstrate existence and uniqueness of Picard--Vessiot extensions
satisfying prescribed properties, for systems of linear differential equations
over a field satisfying the same properties, under some closure assumptions on
the field of constants. An example includes the case of a equations over a real
field, with a real-closed field of constants. The result is obtained through a
model theoretic approach.


title: Cross sections, multiplicity and moment distributions at the LHC

abstract:
  The unitarity of the $S$-matrix requires that the absorptive part of the
elastic scattering amplitude receives contributions from both the inelastic and
the elastic channels. We explore this unitarity condition in order to describe,
in a connected way, hadron-hadron observables like the total and elastic
differential cross sections, the ratio of the real to imaginary part of the
forward scattering amplitude and the inclusive multiplicity distributions in
full phase space, over a large range of energies. We introduce non-perturbative
QCD effects in the forward scattering amplitude by using the infrared QCD
effective charge dependent on the dynamical gluon mass. In our analysis we pay
special attention to the theoretical uncertainties in the predictions due to
this mass scale variation. We also present quantitative predictions for the
$H_{q}$ moments at high energies. Our results reproduce the moment oscillations
observed in experimental data, and are consistent with the behavior predicted
by QCD.


title:
Random walks on dynamical percolation: mixing times, mean squared
  displacement and hitting times

abstract:
  We study the behavior of random walk on dynamical percolation. In this model,
the edges of a graph G are either open or closed and refresh their status at
rate \mu\ while at the same time a random walker moves on G at rate 1 but only
along edges which are open. On the d-dimensional torus with side length n, we
prove that in the subcritical regime, the mixing times for both the full system
and the random walker are n^2/\mu\ up to constants. We also obtain results
concerning mean squared displacement and hitting times. Finally, we show that
the usual recurrence transience dichotomy for the lattice Z^d holds for this
model as well.


title:
Integral forms of Kac-Moody groups and Eisenstein series in low
  dimensional supergravity theories

abstract:
  Kac-Moody groups $G$ over $\mathbb{R}$ have been conjectured to occur as
symmetry groups of supergravities in dimensions less than 3, and their integer
forms $G(\mathbb{Z})$ are conjecturally U-duality groups. Mathematical
descriptions of $G(\mathbb{Z})$, due to Tits, are functorial and not amenable
to computation or applications. We construct Kac-Moody groups over $\mathbb{R}$
and $\mathbb{Z}$ using an analog of Chevalley's constructions in finite
dimensions and Garland's constructions in the affine case. We extend a
construction of Eisenstein series on finite dimensional semisimple algebraic
groups using representation theory, which appeared in the context of
superstring theory, to general Kac-Moody groups. This coincides with a
generalization of Garland's Eisenstein series on affine Kac-Moody groups to
general Kac-Moody groups and includes Eisenstein series on $E_{10}$ and
$E_{11}$. For finite dimensional groups, Eisenstein series encode the quantum
corrections in string theory and supergravity theories. Their Kac-Moody analogs
will likely also play an important part in string theory, though their roles
are not yet understood.


title:
Measuring temperature - dependent propagating disturbances in coronal
  fan loops using multiple SDO/AIA channels and surfing transform technique

abstract:
  A set of co-aligned high resolution images from the Atmospheric Imaging
Assembly (AIA) on board the Solar Dynamics Observatory (SDO) is used to
investigate propagating disturbances (PDs) in warm fan loops at the periphery
of a non-flaring active region NOAA AR 11082. To measure PD speeds at multiple
coronal temperatures, a new data analysis methodology is proposed enabling
quantitative description of subvisual coronal motions with low signal-to-noise
ratios of the order of 0.1 %. The technique operates with a set of
one-dimensional "surfing" signals extracted from position-time plots of several
AIA channels through a modified version of Radon transform. The signals are
used to evaluate a two-dimensional power spectral density distribution in the
frequency - velocity space which exhibits a resonance in the presence of
quasi-periodic PDs. By applying this analysis to the same fan loop structures
observed in several AIA channels, we found that the traveling velocity of PDs
increases with the temperature of the coronal plasma following the square root
dependence predicted for the slow mode magneto-acoustic wave which seems to be
the dominating wave mode in the studied loop structures. This result extends
recent observations by Kiddie et al. (Solar Phys., 2012) to a more general
class of fan loop systems not associated with sunspots and demonstrating
consistent slow mode activity in up to four AIA channels.

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


title: Regularity of Canonical Operators and Nebenh\"ulle: Hartogs Domains

abstract:
  We relate the regularity of the Bergman projection operator and the canonical
solution operator to the Nebenh\"ulle of complete Hartogs domains.


title: Transfer Functions for the DAMA Experiments

abstract:
  We examine what can and what cannot be revealed by the available DAMA dataset
by computing the relevant amplitude transfer function (the ratio of the
amplitude of the detected signal to that of an input signal) and the
corresponding power transfer function. We find that the transfer functions are
small except in the neighborhood of 1 cycle per year.


title:
PDA: Semantically Secure Time-Series Data Analytics with Dynamic
  Subgroups

abstract:
  Third-party analysis on private records is becoming increasingly important
due to the widespread data collection for various analysis purposes. However,
the data in its original form often contains sensitive information about
individuals, and its publication will severely breach their privacy. In this
paper, we present a novel Privacy-preserving Data Analytics framework PDA,
which allows a third-party aggregator to obliviously conduct many different
types of polynomial-based analysis on private data records provided by a
dynamic sub-group of users. Notably, every user needs to keep only O(n) keys to
join data analysis among O(2^n) different groups of users, and any data
analysis that is represented by polynomials is supported by our framework.
Besides, a real implementation shows the performance of our framework is
comparable to the peer works who present ad-hoc solutions for specific data
analysis applications. Despite such nice properties of PDA, it is provably
secure against a very powerful attacker (chosen-plaintext attack) even in the
Dolev-Yao network model where all communication channels are insecure.


title: Fermi velocity renormalization and dynamical gap generation in graphene

abstract:
  We study the renormalization of the Fermi velocity by the long-range Coulomb
interactions between the charge carriers in the Dirac-cone approximation for
the effective low-energy description of the electronic excitations in graphene
at half filling. Solving the coupled system of Dyson-Schwinger equations for
the dressing functions in the corresponding fermion propagator with various
approximations for the particle-hole polarization we observe that Fermi
velocity renormalization effects generally lead to a considerable increase of
the critical coupling for dynamical gap generation and charge-density wave
formation at the semimetal-insulator transition.


title: The intrinsic shapes of dwarf irregular galaxies

abstract:
  We use the measured B band axial ratios of galaxies from an updated catalog
of Local Volume galaxies to determine the intrinsic shape of dwarf irregular
galaxies (de Vacouleurs' morphological types 8, 9 and 10). We find that the
shapes change systematically with luminosity, with fainter galaxies being
thicker. In particular, we divide our sample into sub-samples and find that the
most luminous dwarfs (-19.6 < M_B < -14.8) have thin discs (thickness ~ 0.2),
with the disc being slightly elliptical (axial ratio ~ 0.8). At intermediate
luminosity, viz. -14.8 < M_B < -12.6, the galaxies are still characterized by
elliptical discs (axial ratio ~ 0.7), but the discs are somewhat thicker
(thickness ~ 0.4). The faintest dwarfs, viz. those with -12.6 < M_B < -6.7 are
well described as being oblate spheroids with an axial ratio ~ 0.5. The
increasing thickness of the stellar discs of dwarf irregulars with decreasing
luminosity is compatible with the increasing ratio of velocity dispersion to
rotational velocity with decreasing galaxy size.


title: Exotic Higgs Decay via AZ/HZ Channel: a Snowmass Whitepaper

abstract:
  While the conventional searches for the Higgs boson focus on its decays to
Standard Model (SM) particles: gamma gamma, ZZ, WW, bb and tau tau, in this
study, we explore the decays A --> HZ or H --> AZ. Such decays could appear in
the exotic decay of the observed SM-like Higgs h --> AZ with a light A, or for
extra Higgses in beyond the SM new physics scenarios with an extended Higgs
sector. We study the exclusion bounds as well as discovery reach at the LHC for
various combinations of (m_A, m_H) for the process: gg --> A/H --> HZ/AZ -->
bbll for l =e, mu. We find that for 14 TeV LHC with 300 fb^{-1} integrated
luminosity, the 95% C.L. limits on the cross-section for gg --> A/H --> HZ/AZ
--> bbll vary between about 30 fb to a few fb for the parent heavy Higgs mass
in the range 200 GeV to 600 GeV, while the limits for 5 sigma discovery are
about 2-3 times larger. Comparing with the specific case of Next to Minimal
Supersymmetric Standard Model, we find that this channel could be useful for
heavy Higgs searches, especially for Higgs masses below 350 GeV.


title: Enabling Privacy-preserving Auctions in Big Data

abstract:
  We study how to enable auctions in the big data context to solve many
upcoming data-based decision problems in the near future. We consider the
characteristics of the big data including, but not limited to, velocity,
volume, variety, and veracity, and we believe any auction mechanism design in
the future should take the following factors into consideration: 1) generality
(variety); 2) efficiency and scalability (velocity and volume); 3) truthfulness
and verifiability (veracity). In this paper, we propose a privacy-preserving
construction for auction mechanism design in the big data, which prevents
adversaries from learning unnecessary information except those implied in the
valid output of the auction. More specifically, we considered one of the most
general form of the auction (to deal with the variety), and greatly improved
the the efficiency and scalability by approximating the NP-hard problems and
avoiding the design based on garbled circuits (to deal with velocity and
volume), and finally prevented stakeholders from lying to each other for their
own benefit (to deal with the veracity). We achieve these by introducing a
novel privacy-preserving winner determination algorithm and a novel payment
mechanism. Additionally, we further employ a blind signature scheme as a
building block to let bidders verify the authenticity of their payment reported
by the auctioneer. The comparison with peer work shows that we improve the
asymptotic performance of peer works' overhead from the exponential growth to a
linear growth and from linear growth to a logarithmic growth, which greatly
improves the scalability.


title:
Adaptive detection and severity level characterization algorithm for
  Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) via oximetry signal
  analysis

abstract:
  In this paper, an abstract definition and formal specification is presented
for the task of adaptive-threshold OSAHS events detection and severity
characterization. Specifically, a low-level pseudocode is designed for the
algorithm of raw oximetry signal pre-processing, calculation of the 'drop' and
'rise' frames in the related time series, detection of valid apnea/hypopnea
events via SpO2 saturation level tracking, as well as calculation of
corresponding event rates for OSAHS severity characterization. The designed
algorithm can be used as the first module in a machine learning application
where these data can be used as inputs or encoded into higher-level statistics
(features) for pattern classifiers, in the context of computer-aided or fully
automated diagnosis of OSAHS and related pathologies.


title:
Simulations of Emerging Magnetic Flux. I: The Formation of Stable
  Coronal Flux Ropes

abstract:
  We present results from 3D visco-resistive magnetohydrodynamic (MHD)
simulations of the emergence of a convection zone magnetic flux tube into a
solar atmosphere containing a pre-existing dipole coronal field, which is
orientated to minimize reconnection with the emerging field. We observe that
the emergence process is capable of producing a coronal flux rope by the
transfer of twist from the convection zone as found in previous simulations. We
find that this flux rope is stable, with no evidence of a fast rise, and that
its ultimate height in the corona is determined by the strength of the
pre-existing dipole field. We also find that although the electric currents in
the initial convection zone flux tube are almost perfectly neutralized, the
resultant coronal flux rope carries a significant net current. These results
suggest that flux tube emergence is capable of creating non-current-neutralized
stable flux ropes in the corona, tethered by overlying potential fields, a
magnetic configuration that is believed to be the source of coronal mass
ejections.


title: Smooth affine shear tight frames with MRA structure

abstract:
  Finding efficient representations is one of the most challenging and heavily
sought problems in mathematics. Representation using shearlets recently
receives a lot of attention due to their desirable properties in both theory
and applications. Using the framework of frequency-based affine systems, in
this paper we introduce and systematically study affine shear tight frames
which include all known shearlet tight frames as special cases. Our results in
this paper will resolve several key questions on shearlets. We provide a
complete characterization for an affine shear tight frame and then use it to
obtain smooth affine shear tight frames with all their generators in the
Schwarz class. Though multiresolution analysis (MRA) is the foundation and key
feature of wavelet analysis for fast numerical implementation of a wavelet
transform, all the known shearlets so far do not possess any MRA structure and
filter banks. In order to study affine shear tight frames with MRA structure,
we introduce the notion of a sequence of affine shear tight frames and then we
provide a complete characterization for it. Based on our characterizations, we
present two different approaches, i.e., non-stationary and quasi-stationary,
for the construction of sequences of affine shear tight frames with MRA
structure such that all their generators are smooth (in the Schwarz class) and
they have underlying filter banks. Consequently, their associated transforms
can be efficiently implemented using filter banks similarly as a fast wavelet
transform does.


title: The Partner Units Configuration Problem: Completing the Picture

abstract:
  The partner units problem (PUP) is an acknowledged hard benchmark problem for
the Logic Programming community with various industrial application fields like
surveillance, electrical engineering, computer networks or railway safety
systems. However, computational complexity remained widely unclear so far. In
this paper we provide all missing complexity results making the PUP better
exploitable for benchmark testing. Furthermore, we present QuickPup, a
heuristic search algorithm for PUP instances which outperforms all
state-of-the-art solving approaches and which is already in use in real world
industrial configuration environments.


title: Decoding color codes by projection onto surface codes

abstract:
  We propose a new strategy to decode color codes, which is based on the
projection of the error onto three surface codes. This provides a method to
transform every decoding algorithm of surface codes into a decoding algorithm
of color codes. Applying this idea to a family of hexagonal color codes, with
the perfect matching decoding algorithm for the three corresponding surface
codes, we find a phase error threshold of approximately 8.7%. Finally, our
approach enables us to establish a general lower bound on the error threshold
of a family of color codes depending on the threshold of the three
corresponding surface codes. These results are based on a chain complex
interpretation of surface codes and color codes.


title: Toward Cloud-based Vehicular Networks with Efficient Resource Management

abstract:
  In the era of Internet of Things, all components in intelligent
transportation systems will be connected to improve transport safety, relieve
traffic congestion, reduce air pollution and enhance the comfort of driving.
The vision of all vehicles connected poses a significant challenge to the
collection and storage of large amounts of traffic-related data. In this
article, we propose to integrate cloud computing into vehicular networks such
that the vehicles can share computation resources, storage resources and
bandwidth resources. The proposed architecture includes a vehicular cloud, a
roadside cloud, and a central cloud. Then, we study cloud resource allocation
and virtual machine migration for effective resource management in this
cloud-based vehicular network. A game-theoretical approach is presented to
optimally allocate cloud resources. Virtual machine migration due to vehicle
mobility is solved based on a resource reservation scheme.


title:
The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey IX:
  $^{12}$CO $J=3\to2$ Observations of NGC 2976 and NGC 3351

abstract:
  We present $^{12}$CO \textit{J=3$\rightarrow$2} maps of NGC 2976 and NGC 3351
obtained with the James Clerk Maxwell Telescope (JCMT), both early targets of
the JCMT Nearby Galaxy Legacy Survey (NGLS). We combine the present
observations with $^{12}$CO \textit{J=1$\rightarrow$0} data and find that the
computed $^{12}$CO \textit{J=3$\rightarrow$2} to $^{12}$CO
\textit{J=1$\rightarrow$0} line ratio ($R_{31}$) agrees with values measured in
other NGLS field galaxies. We compute the M$_{\rm{H_2}}$ value and find that it
is robust against the value of $R_{31}$ used. Using \textsc{Hi} data from the
The \textsc{Hi} Nearby Galaxy Survey (THINGS) survey, we find a tight
correlation between surface density of H$_2$ and star formation rate density
for NGC 3351 when $^{12}$CO \textit{J=3$\rightarrow$2} data are used. Finally,
we compare the $^{12}$CO \textit{J=3$\rightarrow$2} intensity with the PAH 8
$\mu$m surface brightness and find a good correlation in the high surface
brightness regions. We extend this study to include all 25 \textit{Spitzer}
Infrared Nearby Galaxies Survey (SINGS) galaxies within the NGLS sample and
find a tight correlation at large spatial scales. We suggest that both PAH 8
$\mu$m and $^{12}$CO \textit{J=3$\rightarrow$2} are likely to originate in
regions of active star formation.


title: Hyperbolic Illusion of the Mid-Holocene Turning Point

abstract:
  Using the growth of population in Australia in the past 10,000 years it is
illustrated here how an illusion created by hyperbolic distributions may lead
easily to incorrect conclusions. Contrary to the published claim, there was no
change in the mechanism of growth of the ancient human population in Australia
around 5000 years before present (BP). Data for the number of rock-shelter
sites, interpreted as reflecting the growth of human population, are analysed.
They are shown to be monotonically increasing with time without any sign of
intensification in the past 10,000 years. The growth of human population in
Australia is in excellent agreement with the similar pattern describing the
growth of the world population.


title: Phases of correlated spinless fermions on the honeycomb lattice

abstract:
  We use exact diagonalization and cluster perturbation theory to address the
role of strong interactions and quantum fluctuations for spinless fermions on
the honeycomb lattice. We find quantum fluctuations to be very pronounced both
at weak and strong interactions. A weak second-neighbor Coulomb repulsion $V_2$
induces a tendency toward an interaction-generated quantum anomalous Hall
phase, as borne out in mean-field theory. However, quantum fluctuations prevent
the formation of a stable quantum Hall phase before the onset of the
charge-modulated phase predicted at large $V_2$ by mean-field theory.
Consequently, the system undergoes a direct transition from the semimetal to
the charge-modulated phase. For the latter, charge fluctuations also play a key
role. While the phase, which is related to pinball liquids, is stabilized by
the repulsion $V_2$, the energy of its low-lying charge excitations scales with
the electronic hopping $t$, as in a band insulator.


title: Entanglement, Superselection Rules and Supersymmetric Quantum Mechanics

abstract:
  In this paper we show that the energy eigenstates of supersymmetric quantum
mechanics (SUSYQM) with non definite "fermion" number are entangled states.
They are "physical states" of the model provided that observables with odd
number of spin variables are allowed in the theory like it happens in the
Jaynes-Cummings model. Those states generalize the so called "spin spring"
states of the Jaynes-Cummings model which have played an important role in the
study of entanglement.


title:
Data Driven Search in the Displaced $b\bar{b}$ Pair Channel for a Higgs
  Boson Decaying to Long-Lived Neutral Particles

abstract:
  This article presents a proposal for a new search channel for the Higgs boson
decaying to two long-lived neutral particles, each of which decays to $b\bar b$
at a displaced vertex. The decay length considered is such that the decay takes
place within the LHC beampipe. We present a new data-driven analysis using jet
substructure and properties of the tracks from the highly-displaced vertices.
  We consider a model with a 125 GeV Higgs boson with a significant branching
fraction to decay via this mode, with the long-lived neutral particle having a
mass in the range of 15--40 GeV and a decay length commensurate with the beam
pipe radius.
  Such a signal can be readily observed with an integrated luminosity of 19.5
fb$^{-1}$ at 8TeV at the LHC.


title: Stability of the Almost Hermitian Curvature Flow

abstract:
  The Almost Hermitian Curvature flow was introduced by Streets and Tian in
order to study almost hermitian structures, with a particular interest in
symplectic structures. This flow is given by a diffusion-reaction equation.
Hence it is natural to ask the following: which almost hermitian structures are
dynamically stable? An almost hermitian structure $(\omega,J)$ is dynamically
stable if it is a fixed point of the flow and there exists a neighborhood
$\mathcal{N}$ of $(\omega,J)$ such that for any almost hermitian structure
$(\omega(0),J(0)) \in \mathcal{N}$ the solution of the Almost Hermitian
Curvature flow starting at $(\omega(0),J(0))$ exists for all time and converges
to a fixed point of the flow. We prove that on a closed K\"{a}hler-Einstein
manifold $(M,\omega,J)$ such that either $c_1(J) <0$ or $(M,\omega,J)$ is a
Calabi-Yau manifold, then the K\"{a}hler-Einstein structure $(\omega,J)$ is
dynamically stable.


title: High-n Hydrogen Recombination Lines from the First Galaxies

abstract:
  We investigate the prospects of blind and targeted searches in the radio
domain (10 MHz to 1 THz) for high-n hydrogen recombination lines from the first
generation of galaxies, at z < 10. The expected optically thin spontaneous
alpha-line luminosities are calculated as a function of the absolute AB
magnitude of a galaxy at 1500 angstrom. For a blind search, semi-empirical
luminosity functions are used to calculate the number of galaxies whose
expected flux densities exceed an assumed detectability threshold. Plots of the
minimum sky area, within which at least one detectable galaxy is expected at a
given observing frequency, in the fiducial instantaneous passband of 10^4 km/s,
allow to assess the blind search time necessary for detection by a given
facility. We show that the chances for detection are the highest in the mm and
submm domains, but finding spontaneous emission in a blind search, especially
from redshifts z >> 1, is a challenge even with powerful facilities, such as
ALMA and SKA. The probability of success is higher for a targeted search of
lines with principal quantum number n ~ 10 in Lyman-break galaxies amplified by
gravitational lensing. Detection of more than one hydrogen line in such a
galaxy will allow for line identification and a precise determination of the
galaxy's redshift.


title: Securing Cognitive Radio Networks against Primary User Emulation Attacks

abstract:
  Cognitive Radio (CR) is a promising technology for next-generation wireless
networks in order to efficiently utilize the limited spectrum resources and
satisfy the rapidly increasing demand for wireless applications and services.
Security is a very important but not well addressed issue in CR networks. In
this paper we focus on security problems arising from Primary User Emulation
(PUE) attacks in CR networks. We present a comprehensive introduction to PUE
attacks, from the attacking rationale and its impact on CR networks, to
detection and defense approaches. In order to secure CR networks against PUE
attacks, a two-level database-assisted detection approach is proposed to detect
such attacks. Energy detection and location verification are combined for fast
and reliable detection. An admission control based defense approach is proposed
to mitigate the performance degradation of a CR network under a PUE attack.
Illustrative results are presented to demonstrate the effectiveness of the
proposed detection and defense approaches.


title:
Numerical Analysis of Gate Conflict Duration and Passenger Transit Time
  in Airport

abstract:
  Robustness is as important as efficiency in air transportation. All
components in the air traffic system are connected to form an interactive
network. So, a disturbance that occurs in one component, for example, a severe
delay at an airport, can influence the entire network. Delays are easily
propagated between flights through gates, but the propagation can be reduced if
gate assignments are robust against stochastic delays. In this paper, we
analyze gate delays and suggest an approach that involves assigning gates while
making them robust against stochastic delays. We extract an example flight
schedule from data source and generate schedules with increased traffic to
analyze how the compact flight schedules impact the robustness of gate
assignment. Simulation results show that our approach improves the robustness
of gate assignment. Particularly, the robust gate assignment reduces average
duration of gate conflicts by 96.3% and the number of gate conflicts by 96.7%
compared to the baseline assignment. However, the robust gate assignment
results in longer transit time for passengers, and a trade-off between the
robustness of gate assignment and passenger transit time is presented.


title: Probing light sterile neutrinos in medium baseline reactor experiments

abstract:
  Medium baseline reactor experiments (Double Chooz, Daya Bay and RENO) provide
a unique opportunity to test the presence of light sterile neutrinos. We
analyze the data of these experiments in the search of sterile neutrinos and
also test the robustness of theta_13 determination in the presence of sterile
neutrinos. We show that existence of a light sterile neutrino state improves
the fit to these data moderately. We also show that the measured value of
theta_{13} by these experiments is reliable even in the presence of sterile
neutrinos, and the reliability owes significantly to the Daya Bay and RENO
data. From the combined analysis of the data of these experiments we constrain
the mixing of a sterile neutrino with mass squared difference in the range of
(10^{-3}-10^{-1}) eV^2 to sin^2 2 theta_{14} <0.1 at 95 % C.L..


title: Second harmonic generation spectroscopy of excitons in ZnO

abstract:
  Nonlinear optics of semiconductors is an important field of fundamental and
applied research, but surprisingly the role of excitons in the coherent
processes leading to harmonics generation has remained essentially unexplored.
Here we report results of a comprehensive experimental and theoretical study of
the three-photon process of optical second harmonic generation (SHG) involving
the exciton resonances of the noncentrosymmetric hexagonal wide-band-gap
semiconductor ZnO in the photon energy range of 3.2-3.5 eV. Resonant
crystallographic SHG is observed for the 1s(A,B), 2s(A,B), 2p(A,B), and 1s(C)
excitons. We show that strong SHG signals at these exciton resonances are
induced by the application of a magnetic field when the incident and the SHG
light wave vectors are along the crystal z-axis where the crystallographic SHG
response vanishes. A microscopic theory of SHG generation through excitons is
developed, which shows that the nonlinear interaction of coherent light with
excitons has to be considered beyond the electric-dipole approximation.
Depending on the particular symmetry of the exciton states SHG can originate
from the electric- and magnetic-field-induced perturbations of the excitons due
to the Stark effect, the spin as well as orbital Zeeman effects, or the
magneto-Stark effect. The importance of each mechanism is analyzed and
discussed by confronting experimental data and theoretical results for the
dependencies of the SHG signals on photon energy, magnetic field, electric
field, crystal temperature, and light polarization. Good agreement is obtained
between experiment and theory proving the validity of our approach to the
complex problem of nonlinear interaction of light with ZnO excitons. This
general approach can be applied also to other semiconductors.


title:
Simulated annealing: in mathematical global optimization computation,
  hybrid with local or global search, and practical applications in
  crystallography and molecular modelling

abstract:
  Simulated annealing (SA) was inspired from annealing in metallurgy, a
technique involving heating and controlled cooling of a material to increase
the size of its crystals and reduce their defects, both are attributes of the
material that depend on its thermodynamic free energy. In this Paper, firstly
we will study SA in details on its practical implementation. Then, hybrid pure
SA with local (or global) search optimization methods allows us to be able to
design several effective and efficient global search optimization methods. In
order to keep the original sense of SA, we clarify our understandings of SA in
crystallography and molecular modeling field through the studies of prion
amyloid fibrils.


title:
A computational framework for infinite-dimensional Bayesian inverse
  problems: Part II. Stochastic Newton MCMC with application to ice sheet flow
  inverse problems

abstract:
  We address the numerical solution of infinite-dimensional inverse problems in
the framework of Bayesian inference. In the Part I companion to this paper
(arXiv.org:1308.1313), we considered the linearized infinite-dimensional
inverse problem. Here in Part II, we relax the linearization assumption and
consider the fully nonlinear infinite-dimensional inverse problem using a
Markov chain Monte Carlo (MCMC) sampling method. To address the challenges of
sampling high-dimensional pdfs arising from Bayesian inverse problems governed
by PDEs, we build on the stochastic Newton MCMC method. This method exploits
problem structure by taking as a proposal density a local Gaussian
approximation of the posterior pdf, whose construction is made tractable by
invoking a low-rank approximation of its data misfit component of the Hessian.
Here we introduce an approximation of the stochastic Newton proposal in which
we compute the low-rank-based Hessian at just the MAP point, and then reuse
this Hessian at each MCMC step. We compare the performance of the proposed
method to the original stochastic Newton MCMC method and to an independence
sampler. The comparison of the three methods is conducted on a synthetic ice
sheet inverse problem. For this problem, the stochastic Newton MCMC method with
a MAP-based Hessian converges at least as rapidly as the original stochastic
Newton MCMC method, but is far cheaper since it avoids recomputing the Hessian
at each step. On the other hand, it is more expensive per sample than the
independence sampler; however, its convergence is significantly more rapid, and
thus overall it is much cheaper. Finally, we present extensive analysis and
interpretation of the posterior distribution, and classify directions in
parameter space based on the extent to which they are informed by the prior or
the observations.

categories: stat.ME math.NA math.OC math.ST stat.CO stat.TH


title:
Quasars Probing Quasars VI. Excess HI Absorption Within One Proper Mpc
  of z~2 Quasars

abstract:
  With close pairs of quasars at different redshifts, a background quasar
sightline can be used to study a foreground quasar's environment in absorption.
We use a sample of 650 projected quasar pairs to study the HI Lya absorption
transverse to luminous, z~2 quasars at proper separations of 30kpc < R < 1Mpc.
In contrast to measurements along the line-of-sight, regions transverse to
quasars exhibit enhanced HI Lya absorption and a larger variance than the
ambient intergalactic medium, with increasing absorption and variance toward
smaller scales. Analysis of composite spectra reveals excess absorption
characterized by a Lya equivalent width profile W = 2.3A (R/100kpc)^-0.46. We
also observe a high (~60%) covering factor of strong, optically thick HI
absorbers (HI column log NHI > 17.3) at separations R<200kpc, which decreases
to ~20% at R~1Mpc, but still represents a significant excess over the cosmic
average. This excess of optically thick absorption can be described by a
quasar-absorber cross-correlation function xi_QA(r) = (r/r_0)^gamma with a
large correlation length r_0 = 12.5+2.7-1.4 Mpc/h (comoving) and gamma =
1.68+0.14-0.30. The HI absorption measured around quasars exceeds that of any
previously studied population, consistent with quasars being hosted by massive
dark matter halos Mhalo~10^12.5 Msun at z~2.5. The environments of these
massive halos are highly biased towards producing optically thick gas, and may
even dominate the cosmic abundance of Lyman limit systems and hence the
intergalactic opacity to ionizing photons at z~2.5. The anisotropic absorption
around quasars implies the transverse direction is much less likely to be
illuminated by ionizing radiation than the line-of-sight, which we interpret in
terms of the same obscuration effects frequently invoked in unified models of
active galactic nuclei.


title: Connections on Cahen-Wallach spaces

abstract:
  We systematically discuss connections on the spinor bundle of Cahen-Wallach
symmetric spaces. A large class of these connections is closely connected to a
quadratic relation on Clifford algebras. This relation in turn is associated to
the symmetric linear map that defines the underlying space. We present various
solutions of this relation. Moreover, we show that the solutions we present
provide a complete list with respect to a particular algebraic condition on the
parameters that enter into the construction.


title:
The genesis of streamwise-localized solutions from globally periodic
  travelling waves in pipe flow

abstract:
  The aim in the dynamical systems approach to transitional turbulence is to
construct a scaffold in phase space for the dynamics using simple invariant
sets (exact solutions) and their stable and unstable manifolds. In large
(realistic) domains where turbulence can co-exist with laminar flow, this
requires identifying exact localized solutions. In wall-bounded shear flows the
first of these has recently been found in pipe flow, but questions remain as to
how they are connected to the many known streamwise-periodic solutions. Here we
demonstrate the origin of the first localized solution in a modulational
symmetry-breaking Hopf bifurcation from a known global travelling wave that has
2-fold rotational symmetry about the pipe axis. Similar behaviour is found for
a global wave of 3-fold rotational symmetry, this time leading to two localized
relative periodic orbits. The clear implication is that all global solutions
should be expected to lead to more realistic localised counterparts through
such bifurcations, which provides a constructive route for their generation.


title: Voronoi's Conjecture for extensions of Voronoi parallelohedra

abstract:
  Let $I$ be a segment in the $d$-dimensional Euclidean space $\mathbb E^d$.
Let $P$ and $P+I$ be parallelohedra in $\mathbb E^d$, where "+" denotes the
Minkowski sum. We prove that Voronoi's Conjecture holds for $P+I$, i.e. $P+I$
is a Voronoi parallelohedron for some Euclidean metric in $\mathbb E^d$, if
Voronoi's Conjecture holds for $P$.


title:
Commutator Estimates for the Dirichlet-to-Neumann Map in Lipschitz
  Domains

abstract:
  We establish two commutator estimates for the Dirichlet-to-Neumann map
associated with a second-order elliptic system in divergence form in Lipschitz
domains. Our approach is based on Dahlberg's bilinear estimates.


title: On the Convergence of Regular Families of Cardinal Interpolators

abstract:
  In this note a general way to develop a cardinal interpolant for $l^2$-data
on the integer lattice $Z^n$ is shown. Further, a parameter is introduced which
allows one to recover the original Paley-Weiner function from which the data
came.


title: Cherenkov loss factor of short relativistic bunches:general approach

abstract:
  The interaction of short relativistic charged particle bunches with
waveguides and other accelerator system components is a critical issue for the
development of X-ray FELs (free electron lasers) and linear collider projects.
Wakefield Cherenkov losses of short bunches have been studied previously for
resistive wall, disk-loaded, corrugated and dielectric loaded waveguides. It
was noted in various publications [1] that if the slowdown layer is thin, the
Cherenkov loss factor of a short bunch does not depend on the guiding system
material and is a constant for any given transverse cross section dimensions of
the waveguides. In this paper, we consider a new approach to the analysis of
loss factors for relativistic short bunches and formulate a general integral
relation that allows calculation of the loss factor for a short relativistic
bunch passing an arbitrary waveguide system. The loss factors calculated by
this new method for various types of waveguides with arbitrary thickness
slowdown layers, including infinite media, are shown to be equivalent to those
obtained by a conventional approach.


title: Electric Field Effects on Armchair MoS2 Nanoribbons

abstract:
  {\it Ab initio} density functional theory calculations are performed to
investigate the electronic structure of MoS$_2$ armchair nanoribbons in the
presence of an external static electric field. Such nanoribbons, which are
nonmagnetic and semiconducting, exhibit a set of weakly interacting edge states
whose energy position determines the band-gap of the system. We show that, by
applying an external transverse electric field, $E_\mathrm{ext}$, the
nanoribbons band-gap can be significantly reduced, leading to a metal-insulator
transition beyond a certain critical value. Moreover, the presence of a
sufficiently high density of states at the Fermi level in the vicinity of the
metal-insulator transition leads to the onset of Stoner ferromagnetism that can
be modulated, and even extinguished, by $E_\mathrm{ext}$. In the case of
bi-layer nanoribbons we further show that the band-gap can be changed from
indirect to direct by applying a transverse field, an effect which might be of
significance for opto-electronics applications.


title: Forecasting cosmological constraints from age of high-z galaxies

abstract:
  We perform Monte Carlo simulations based on current age estimates of high-z
objects to forecast constraints on the equation of state (EoS) of the dark
energy. In our analysis, we use two different EoS parameterizations, namely,
the so-called CPL and its uncorrelated form and calculate the improvements on
the figure of merit for both cases. Although there is a clear dependence of the
FoM with the size and accuracy of the synthetic age samples, we find that the
most substantial gain in FoM comes from a joint analysis involving age and
baryon acoustic oscillation data.


title: Equidistant Codes in the Grassmannian

abstract:
  Equidistant codes over vector spaces are considered. For $k$-dimensional
subspaces over a large vector space the largest code is always a sunflower. We
present several simple constructions for such codes which might produce the
largest non-sunflower codes. A novel construction, based on the Pl\"{u}cker
embedding, for 1-intersecting codes of $k$-dimensional subspaces over $\F_q^n$,
$n \geq \binom{k+1}{2}$, where the code size is $\frac{q^{k+1}-1}{q-1}$ is
presented. Finally, we present a related construction which generates
equidistant constant rank codes with matrices of size $n \times \binom{n}{2}$
over $\F_q$, rank $n-1$, and rank distance $n-1$.


title: The threshold for integer homology in random d-complexes

abstract:
  Let Y ~ Y_d(n,p) denote the Bernoulli random d-dimensional simplicial
complex. We answer a question of Linial and Meshulam from 2003, showing that
the threshold for vanishing of homology H_{d-1}(Y; Z) is less than 80d log n /
n. This bound is tight, up to a constant factor.


title: Magnetic properties of a long, thin-walled ferromagnetic nanotube

abstract:
  We consider magnetic properties of a long, thin-walled ferromagnetic
nanotube. We assume that the tube consists of isotropic homogeneous magnet
whose spins interact via the exchange energy, the dipole-dipole interaction
energy, and also interact with an external field via Zeeman energy. Possible
stable states are the parallel state with the magnetization along the axis of
the tube, and the vortex state with the magnetization along azimuthal
direction. For a given material, which of them has lower energy depends on the
value \gamma=R^2d/(L \lambda_x^2), where R is the radius of the tube, d is its
thickness, L is its length and \lambda_x is an intrinsic scale of length
characterizing the ration of exchange and dipolar interaction. At \gamma<1 the
parallel state wins, otherwise the vortex state is stable. A domain wall in the
middle of the tube is always energy unfavorable, but it can exist as a
metastable structure. Near the ends of a tube magnetized parallel to the axis a
half-domain structure transforming gradually the parallel magnetization to a
vortex just at the edge of the tube is energy favorable. We also consider the
equilibrium magnetization textures in an external magnetic field either
parallel or perpendicular to the tube. Finally, magnetic fields produced by a
nanotube and an array of tubes is analyzed.


title: Exterior differential systems via functors of Artin rings

abstract:
  We apply the theory of functors of Artin rings to prove the existence of a
universal formal solution to a exterior differential system. We compute the
tangent space and the obstruction theory of the funtor of Artin ring governing
the solutions of the exterior differential system.


title:
A free boundary problem modeling electrostatic MEMS: I. Linear bending
  effects

abstract:
  The dynamical and stationary behaviors of a fourth-order evolution equation
with clamped boundary conditions and a singular nonlocal reaction term, which
is coupled to an elliptic free boundary problem on a non-smooth domain, are
investigated. The equation arises in the modeling of microelectromechanical
systems (MEMS) and includes two positive parameters $\lambda$ and $\varepsilon$
related to the applied voltage and the aspect ratio of the device,
respectively. Local and global well-posedness results are obtained for the
corresponding hyperbolic and parabolic evolution problems as well as a
criterion for global existence excluding the occurrence of finite time
singularities which are not physically relevant. Existence of a stable steady
state is shown for sufficiently small $\lambda$. Non-existence of steady states
is also established when $\varepsilon$ is small enough and $\lambda$ is large
enough (depending on $\varepsilon$).


title:
A room-temperature alternating current susceptometer - Data analysis,
  calibration, and test

abstract:
  An AC susceptometer operating in the range of 10 Hz to 100 kHz and at room
temperature is designed, built, calibrated and used to characterize the
magnetic behaviour of coated magnetic nanoparticles. Other weakly magnetic
materials (in amounts of some millilitres) can be analyzed as well. The setup
makes use of a DAQ-based acquisition system in order to determine the amplitude
and the phase of the sample magnetization as a function of the frequency of the
driving magnetic field, which is powered by a digital waveform generator. A
specific acquisition strategy makes the response directly proportional to the
sample susceptibility, taking advantage of the differential nature of the coil
assembly. A calibration method based on conductive samples is developed.


title: An intriguing ring structure on the set of d-forms

abstract:
  The purpose of this note is to introduce a multiplication on the set of
homogeneous polynomials of fixed degree d, in a way to provide a duality theory
between monomial ideals of K[x_1,\ldots,x_d] generated in degrees \leq n and
block stable ideals (a class of ideals containing the Borel fixed ones) of
K[x_1,\ldots,x_n] generated in degree d. As a byproduct we give a new proof of
the characterization of Betti tables of ideals with linear resolution given by
Murai.


title:
A Galaxy Model from 2MASS Star Counts in the Whole Sky Including the
  Plane

abstract:
  We use the star counts model of Ortiz & L\'epine (1993) to perform an
unprecedented exploration of the most important galactic parameters comparing
the predicted counts with the 2MASS observed star counts in the J, H and K_S
bands for a grid of positions covering the whole sky. The comparison is made
using a grid of lines-of-sight given by the HEALPix pixelization scheme. The
resulting best fit values for the parameters are: (2120 +- 200) pc for the
radial scale length and (205 +- 40) pc for the scale height of the thin disk,
with a central hole of (2070_{-800}^{+2000}) pc for the same disk; (3050 +-
500) pc for the radial scale length and (640 +- 70) pc for the scale height of
the thick disk; (400 +- 100) pc for the central dimension of the spheroid,
(0.0082 +- 0.0030) for the spheroid to disk density ratio, and (0.57 +- 0.05)
for the oblate spheroid parameter.


title: Pro-p-Iwahori invariants for SL_2 and L-packets of Hecke modules

abstract:
  Let p be a prime number, and F a nonarchimedean local field of residual
characteristic p. We explore the interaction between the pro-p-Iwahori-Hecke
algebras of the group GL_n(F) and its derived subgroup SL_n(F). Using the
interplay between these two algebras, we deduce two main results. The first is
an equivalence of categories between Hecke modules in characteristic p over the
pro-p-Iwahori-Hecke algebra of SL_2(Q_p) and smooth mod-p representations of
SL_2(Q_p) generated by their pro-p-Iwahori-invariants. The second is a
"numerical correspondence" between packets of supersingular Hecke modules in
characteristic p over the pro-p-Iwahori-Hecke algebra of SL_n(F), and
irreducible, n-dimensional projective Galois representations.


title:
Diminishing Return for Increased Mappability with Longer Sequencing
  Reads: Implications of the k-mer Distributions in the Human Genome

abstract:
  The amount of non-unique sequence (non-singletons) in a genome directly
affects the difficulty of read alignment to a reference assembly for high
throughput-sequencing data. Although a greater length increases the chance for
reads being uniquely mapped to the reference genome, a quantitative analysis of
the influence of read lengths on mappability has been lacking. To address this
question, we evaluate the k-mer distribution of the human reference genome. The
k-mer frequency is determined for k ranging from 20 to 1000 basepairs. We use
the proportion of non-singleton k-mers to evaluate the mappability of reads for
a corresponding read length. We observe that the proportion of non-singletons
decreases slowly with increasing k, and can be fitted by piecewise power-law
functions with different exponents at different k ranges. A faster decay at
smaller values for k indicates more limited gains for read lengths > 200
basepairs. The frequency distributions of k-mers exhibit long tails in a
power-law-like trend, and rank frequency plots exhibit a concave Zipf's curve.
The location of the most frequent 1000-mers comprises 172 kilobase-ranged
regions, including four large stretches on chromosomes 1 and X, containing
genes with biomedical implications. Even the read length 1000 would be
insufficient to reliably sequence these specific regions.


title: The LHeC Detector

abstract:
  The Large Hadron Electron Collider (LHeC) is a proposed upgrade to the LHC,
to provide high energy, high luminosity electron-proton collisions to run
concurrently with Phase 2 of the LHC. The baseline design of a detector for the
LHeC is described, driven by the requirements from the projected physics
programme and including some preliminary results from first simulations.


title:
NRC-Canada: Building the State-of-the-Art in Sentiment Analysis of
  Tweets

abstract:
  In this paper, we describe how we created two state-of-the-art SVM
classifiers, one to detect the sentiment of messages such as tweets and SMS
(message-level task) and one to detect the sentiment of a term within a
submissions stood first in both tasks on tweets, obtaining an F-score of 69.02
in the message-level task and 88.93 in the term-level task. We implemented a
variety of surface-form, semantic, and sentiment features. with sentiment-word
hashtags, and one from tweets with emoticons. In the message-level task, the
lexicon-based features provided a gain of 5 F-score points over all others.
Both of our systems can be replicated us available resources.


title:
Comment on Increased mortality is predicted of Inachis io larvae caused
  by Bt-maize pollen in European farmland, Ecological Modelling, 2013

abstract:
  In this comment, we analyze the mathematical model by Holst et al that
estimates the increased mortality of Inachis io larvae caused by Bt-maize
pollen in European farmaland. In particular, we focus our attention on the part
of Holst et al's work that models the Bt-maize pollen loss on plant leaves by a
differential equation. We provide the exact solution of the differential
equation, showing that the behaviour of the solution, when the time goes to
infinity, is different from what claimed in Holst et al's work.


title:
Elliptical Tracers in Two-dimensional, Homogeneous, Isotropic Fluid
  Turbulence: the Statistics of Alignment, Rotation, and Nematic Order

abstract:
  We study the statistical properties of orientation and rotation dynamics of
elliptical tracer particles in two-dimensional, homogeneous and isotropic
turbulence by direct numerical simulations. We consider both the cases in which
the turbulent flow is generated by forcing at large and intermediate length
scales. We show that the two cases are qualitatively different. For large-scale
forcing, the spatial distribution of particle orientations forms large-scale
structures, which are absent for intermediate-scale forcing. The alignment with
the local directions of the flow is much weaker in the latter case than in the
former. For intermediate-scale forcing, the statistics of rotation rates
depends weakly on the Reynolds number and on the aspect ratio of particles. In
contrast with what is observed in three-dimensional turbulence, in two
dimensions the mean-square rotation rate decreases as the aspect ratio
increases.


title:
Using Volcano Plots and Regularized-Chi Statistics in Genetic
  Association Studies

abstract:
  Labor intensive experiments are typically required to identify the causal
disease variants from a list of disease associated variants in the genome. For
designing such experiments, candidate variants are ranked by their strength of
genetic association with the disease. However, the two commonly used measures
of genetic association, the odds-ratio (OR) and p-value, may rank variants in
different order. To integrate these two measures into a single analysis, here
we transfer the volcano plot methodology from gene expression analysis to
genetic association studies. In its original setting, volcano plots are scatter
plots of fold-change and t-test statistic (or -log of the p-value), with the
latter being more sensitive to sample size. In genetic association studies, the
OR and Pearson's chi-square statistic (or equivalently its square root, chi; or
the standardized log(OR)) can be analogously used in a volcano plot, allowing
for their visual inspection. Moreover, the geometric interpretation of these
plots leads to an intuitive method for filtering results by a combination of
both OR and chi-square statistic, which we term "regularized-chi". This method
selects associated markers by a smooth curve in the volcano plot instead of the
right-angled lines which corresponds to independent cutoffs for OR and
chi-square statistic. The regularized-chi incorporates relatively more signals
from variants with lower minor-allele-frequencies than chi-square test
statistic. As rare variants tend to have stronger functional effects,
regularized-chi is better suited to the task of prioritization of candidate
genes.


title:
Observation of Self-Sustaining Relativistic Ionization Wave Launched by
  Sheath Field

abstract:
  We present experimental evidence supported by simulations of a relativistic
ionization wave launched into surrounding gas by the sheath field of a plasma
filament with high energy electrons. Such filament is created by irradiating a
clustering gas jet with a short pulse laser ($\sim$115 fs) at a peak intensity
of $5 \times 10^{17}$ W/cm$^2$. We observe an ionization wave propagating
radially through the gas for about 2 ps at 0.2-0.5 $c$ after the laser has
passed, doubling the initial radius of the filament. The gas is ionized by the
sheath field, while the longevity of the wave is explained by a moving field
structure that traps the high energy electrons near the boundary, maintaining a
strong sheath field despite the significant expansion of the plasma.


title: Fast dynamos in spherical boundary-driven flows

abstract:
  We numerically demonstrate the feasibility of kinematic fast dynamos for a
class of time-periodic axisymmetric flows of conducting fluid confined inside a
sphere. The novelty of our work is in considering the realistic flows, which
are self-consistently determined from the Navier-Stokes equation with specified
boundary driving. Such flows can be achieved in a new plasma experiment, whose
spherical boundary is capable of differential driving of plasma flows in the
azimuthal direction. We show that magnetic fields are self-excited over a range
of flow parameters such as amplitude and frequency of flow oscillations, fluid
Reynolds (Re) and magnetic Reynolds (Rm) numbers. In the limit of large Rm, the
growth rates of the excited magnetic fields are of the order of the advective
time scales and practically independent of Rm, which is an indication of the
fast dynamo.


title: Tunneling spectroscopy for probing orbital anisotropy in iron pnictides

abstract:
  Using realistic multi-orbital tight-binding Hamiltonians and the T-matrix
formalism, we explore the effects of a non-magnetic impurity on the local
density of states in Fe-based compounds. We show that scanning tunneling
spectroscopy (STS) has very specific anisotropic signatures that track the
evolution of orbital splitting (OS) and antiferromagnetic gaps. Both
anisotropies exhibit two patterns that split in energy with decreasing
temperature, but for OS these two patterns map onto each other under 90 degree
rotation. STS experiments that observe these signatures should expose the
underlying magnetic and orbital order as a function of temperature across
various phase transitions.


title:
Sheaf Representations for Algebraic Systems. A personal historical
  account

abstract:
  From personal experience, I report about the development of sheaf
representations for algebraic structures between the years 1966 and 1976.
Starting with rings, lattice-ordered groups and rings it turns to general
algebraic structures.


title:
Circumnavigation of an Unknown Target Using UAVs with Range and Range
  Rate Measurements

abstract:
  This paper presents two control algorithms enabling a UAV to circumnavigate
an unknown target using range and range rate (i.e., the derivative of range)
measurements. Given a prescribed orbit radius, both control algorithms (i) tend
to drive the UAV toward the tangent of prescribed orbit when the UAV is outside
or on the orbit, and (ii) apply zero control input if the UAV is inside the
desired orbit. The algorithms differ in that, the first algorithm is smooth and
unsaturated while the second algorithm is non-smooth and saturated. By
analyzing properties associated with the bearing angle of the UAV relative to
the target and through proper design of Lyapunov functions, it is shown that
both algorithms produce the desired orbit for an arbitrary initial state. Three
examples are provided as a proof of concept.


title:
Implementation and optimization of Wavelet modulation in Additive
  Gaussian channels

abstract:
  In this paper, we investigate the implementation of wavelet modulation (WM)
in a digital communication system and propose novel methods to improve its
performance. We will put particular focus on the structure of an optimal
detector in AWGN channels and address two main methods for inserting the
samples of the message signal in different frequency layers. Finally, computer
based algorithms are described in order to implement and optimize receivers and
transmitters.


title:
Three New Galactic Center X-ray Sources Identified with Near-Infrared
  Spectroscopy

abstract:
  We have conducted a near-infrared spectroscopic survey of 47 candidate
counterparts to X-ray sources discovered by the Chandra X-ray Observatory near
the Galactic Center (GC). Though a significant number of these astrometric
matches are likely to be spurious, we sought out spectral characteristics of
active stars and interacting binaries, such as hot, massive spectral types or
emission lines in order to corroborate the X-ray activity and certify the
authenticity of the match. We present three new spectroscopic identifications,
including a Be high mass X-ray binary (HMXB) or a gamma Cassiopeiae (Cas)
system, a symbiotic X-ray binary and an O-type star of unknown luminosity
class. The Be HMXB/gamma Cas system and the symbiotic X-ray binary are the
first of their classes to be spectroscopically identified in the GC region.


title: Quantum Simulation

abstract:
  Simulating quantum mechanics is known to be a difficult computational
problem, especially when dealing with large systems. However, this difficulty
may be overcome by using some controllable quantum system to study another less
controllable or accessible quantum system, i.e., quantum simulation. Quantum
simulation promises to have applications in the study of many problems in,
e.g., condensed-matter physics, high-energy physics, atomic physics, quantum
chemistry and cosmology. Quantum simulation could be implemented using quantum
computers, but also with simpler, analog devices that would require less
control, and therefore, would be easier to construct. A number of quantum
systems such as neutral atoms, ions, polar molecules, electrons in
semiconductors, superconducting circuits, nuclear spins and photons have been
proposed as quantum simulators. This review outlines the main theoretical and
experimental aspects of quantum simulation and emphasizes some of the
challenges and promises of this fast-growing field.


title: Shifts of a resonance line in a dense atomic sample

abstract:
  We study the collective response of a dense atomic sample to light
essentially exactly using classical-electrodynamics simulations. In a
homogeneously broadened atomic sample there is no overt Lorentz-Lorenz local
field shift of the resonance, nor a collective Lamb shift. However, addition of
inhomogeneous broadening restores the usual mean-field phenomenology.

categories: physics.atom-ph cond-mat.quant-gas physics.class-ph physics.comp-ph physics.optics


title: The Shapley Axiomatization for Values in Partition Function Games

abstract:
  One of the long-debated issues in coalitional game theory is how to extend
the Shapley value to games with externalities (partition-function games). When
externalities are present, not only can a player's marginal contribution - a
central notion to the Shapley value - be defined in a variety of ways, but it
is also not obvious which axiomatization should be used. Consequently, a number
of authors extended the Shapley value using complex and often unintuitive
axiomatizations. Furthermore, no algorithm to approximate any extension of the
Shapley value to partition-function games has been proposed to date. Given this
background, we prove in this paper that, for any well-defined measure of
marginal contribution, Shapley's original four axioms imply a unique value for
games with externalities. As an consequence of this general theorem, we show
that values proposed by Macho-Stadler et al., McQuillin and Bolger can be
derived from Shapley's axioms. Building upon our analysis of marginal
contribution, we develop a general algorithm to approximate extensions of the
Shapley value to games with externalities using a Monte Carlo simulation
technique.


title:
G-consistent price system and bid-ask pricing for European contingent
  claims under Knightian uncertainty

abstract:
  The target of this paper is to consider model the risky asset price on the
financial market under the Knightian uncertainty, and pricing the ask and bid
prices of the uncertain risk. We use the nonlinear analysis tool, i.e., G-frame
work [26], to construct the model of the risky asset price and bid-ask pricing
for the European contingent claims under Knightian uncertain financial market.
Firstly, we consider the basic risky asset price model on the uncertain
financial market, which we construct here is the model with drift uncertain and
volatility uncertain. We describe such model by using generalized G-Brownian
motion and call it as G-asset price system. We present the uncertain risk
premium which is uncertain and distributed with maximum distribution. We derive
the closed form of bid-ask price of the European contingent claim against the
underlying risky asset with G-asset price system as the discounted conditional
G-expecation of the claim, and the bid and ask prices are the viscosity
solutions to the nonlinear HJB equations.Furthermore, we consider the main part
of this paper, i.e., consider the risky asset on the Knightian uncertain
financial market with the price fluctuation shows as continuous trajectories.
We propose the G-conditional full support condition by using uncertain
capacity, and the risky asset price path satisfying the G-conditional full
support condition could be approximated by its G-consistent asset price
systems. We derive that the bid and ask prices of the European contingent claim
against such risky asset under uncertain can be expressed by discounted of some
conditional G-expectation of the claim. We give examples, such as G-Markovian
processes and the geometric fractional G-Brownian motion [9], satisfying the
G-conditional full support condition.


title:
Entanglement in ground and excited states of gapped fermion systems and
  their relationship with fermi surface and thermodynamic equilibrium
  properties

abstract:
  We study bipartite entanglement entropies in the ground and excited states of
model fermion systems, where a staggered potential, $\mu_s$, induces a gap in
the spectrum. Ground state entanglement entropies satisfy the `area law', and
the `area-law' coefficient is found to diverge as a logarithm of the staggered
potential, when the system has an extended Fermi surface at $\mu_s=0$. On the
square-lattice, we show that the coefficient of the logarithmic divergence
depends on the fermi surface geometry and its orientation with respect to the
real-space interface between subsystems and is related to the Widom conjecture
as enunciated by Gioev and Klich (Phys. Rev. Lett. 96, 100503 (2006)). For
point Fermi surfaces in two-dimension, the `area-law' coefficient stays finite
as $\mu_s\to 0$. The von Neumann entanglement entropy associated with the
excited states follows a `volume law' and allows us to calculate an entropy
density function s_{V}(e), which is substantially different from the
thermodynamic entropy density function $s_{T}(e)$, when the lattice is
bipartitioned into two equal subsystems but approaches the thermodynamic
entropy density as the fraction of sites in the larger subsystem, that is
integrated out, approaches unity.


title:
Tune-out wavelengths and landscape modulated polarizabilities of alkali
  Rydberg atoms in infrared optical lattices

abstract:
  Intensity modulated optical lattice potentials can change sign for an alkali
metal Rydberg atom, and the atoms are not always attracted to intensity minima
in optical lattices with wavelengths near the CO$_2$ laser band. Here we
demonstrate that such IR lattices can be tuned so that the trapping potential
seen by the Rydberg atom can be made to vanish for atoms in \targeted" Rydberg
states. Such state selective trapping of Rydberg atoms can be useful in
controlled cold Rydberg collisions, cooling Rydberg states, and
species-selective trapping and transport of Rydberg atoms in optical lattices.
We tabulate wavelengths at which the trapping potential vanishes for the $n$s,
$n$p, and $n$d Rydberg states of Na and Rb atoms, and discuss advantages of
using such optical lattices for state selective trapping of Rydberg atoms. We
also develop exact analytic expressions for the lattice induced polarizability
for the $m_z = 0$ Rydberg states, and derive an accurate formula predicting
tune-out wavelengths at which the optical trapping potential becomes invisible
to Rydberg atoms in targeted $l = 0$ states.


title: Emissivity and conductivity of parton-hadron matter

abstract:
  We investigate the properties of the QCD matter across the deconfinement
phase transition. In the scope of the parton-hadron string dynamics (PHSD)
transport approach, we study the strongly interacting matter in equilibrium as
well as the out-of equilibrium dynamics of relativistic heavy-ion collisions.
We present here in particular the results on the electromagnetic radiation,
i.e. photon and dilepton production, in relativistic heavy-ion collisions and
the relevant correlator in equilibrium, i.e. the electric conductivity. By
comparing our calculations for the heavy-ion collisions to the available data,
we determine the relative importance of the various production sources and
address the possible origin of the observed strong elliptic flow $v_2$ of
direct photons.