title: Freezing of an unconventional two-dimensional plasma

abstract:
  We study an unconventional two-dimensional, two-component classical plasma on
a sphere, with emphasis on detecting signatures of melting transitions. This
system is relevant to Ising-type quantum Hall states, and is unconventional in
the sense that it features particles interacting via two different
two-dimensional Coulomb interactions. One species of particles in the plasma
carries charge of both types (Q_1,Q_2), while the other species carries only
charge of the second type (0,-Q_2). We find signatures of a freezing transition
at Q_1^2 approximately 140. This means that the species with charge of both
types will form a Wigner crystal, whereas the species with charge of the second
type also shows signatures of being a Wigner crystal, due to the attractive
inter-component interaction of the second type. Moreover, there is also a
Berezinskii-Kosterlitz-Thouless phase transition at Q_2^2 approximately 4, at
which the two species of particles bind to form molecules that are neutral with
respect to the second Coulomb interaction. These two transitions appear to be
independent of each other, giving a rectangular phase diagram. As a special
case, Q_2=0 describes the (conventional) two-dimensional one-component plasma.
Our study is consistent with previous studies of this plasma, and sheds new
light on the freezing transition of this system.


title: Irreversibility in an ideal fluid

abstract:
  When a real fluid is expelled quickly from a tube, it forms a jet separated
from the surrounding fluid by a thin, turbulent layer. On the other hand, when
the same fluid is sucked into the tube, it comes in from all directions,
forming a sink-like flow. We show that, even for the ideal flow described by
the time-reversible Euler equation, an experimenter who only controls the
pressure in a pump attached to the tube would see jets form in one direction
exclusively. The asymmetry between outflow and inflow therefore does not depend
on viscous dissipation, but rather on the experimenter's limited control of
initial and boundary conditions. This illustrates, in a rather different
context from the usual one of thermal physics, how irreversibility may arise in
systems whose microscopic dynamics are fully reversible.


title: Polya's random walk theorem

abstract:
  This note presents a proof of P\'olya's random walk theorem using classical
methods from special function theory and asymptotic analysis.


title: Rigidity of Julia sets for Henon type maps

abstract:
  We prove that the Julia set of a Henon type automorphism on C^2 is very
rigid: it supports a unique positive ddc-closed current of mass 1. A similar
property holds for the cohomology class of the Green current associated with an
automorphism of positive entropy on a compact Kaehler surface. Relations
between this phenomenon, several quantitative equidistribution properties and
the theory of value distribution will be discussed. We also survey some
rigidity properties of Henon type maps on C^k and of automorphisms of compact
Kaehler manifolds.


title: Isofrequency pairing of geodesic orbits in Kerr geometry

abstract:
  Bound geodesic orbits around a Kerr black hole can be parametrized by three
constants of the motion: the (specific) orbital energy, angular momentum and
Carter constant. Generically, each orbit also has associated with it three
frequencies, related to the radial, longitudinal and (mean) azimuthal motions.
Here we note the curious fact that these two ways of characterizing bound
geodesics are not in a one-to-one correspondence. While the former uniquely
specifies an orbit up to initial conditions, the latter does not: there is a
(strong-field) region of the parameter space in which pairs of physically
distinct orbits can have the same three frequencies. In each such isofrequency
pair the two orbits exhibit the same rate of periastron precession and the same
rate of Lense-Thirring precession of the orbital plane, and (in a certain
sense) they remain "synchronized" in phase.


title:
A subtraction scheme for computing QCD jet cross sections at NNLO:
  integrating the doubly unresolved subtraction terms

abstract:
  We finish the definition of a subtraction scheme for computing NNLO
corrections to QCD jet cross sections. In particular, we perform the
integration of the soft-type contributions to the doubly unresolved
counterterms via the method of Mellin-Barnes representations. With these final
ingredients in place, the definition of the scheme is complete and the
computation of fully differential rates for electron-positron annihilation into
two and three jets at NNLO accuracy becomes feasible.


title:
Photospheric emission as the dominant radiation mechanism in
  long-duration gamma-ray bursts

abstract:
  We present the results of a set of numerical simulations of long-duration
gamma-ray burst jets associated with massive, compact stellar progenitors. The
simulations extend to large radii and allow us to locate the region in which
the peak frequency of the advected radiation is set before the radiation is
released at the photosphere. Light curves and spectra are calculated for
different viewing angles as well as different progenitor structures and jet
properties. We find that the radiation released at the photosphere of
matter-dominated jets is able to reproduce the observed Amati and
energy-Lorentz factor correlations. Our simulations also predict a correlation
between the burst energy and the radiative efficiency of the prompt phase,
consistent with observations.


title: Inherent Symmetry and Microstructure Ambiguity in Micromechanics

abstract:
  The computational cost of micromechanics for heterogeneous materials can be
reduced in certain cases where symmetric boundary conditions are applicable. We
derived an eighth symmetric formulation of the Generalized Method of Cells for
triply periodic microstructures. During this endeavor, an inherent symmetry was
discovered. This implied that all repeating unit cells may be quarter symmetric
representations of other microstructures. Additionally, it was discovered that
a repeating unit cell can have columns of subcells swapped with no changes to
the local or global fields. We concluded that first-order micromechanics are
not well suited for capturing detailed or complex microstructures; however,
higher-order theories, such as High Fidelity Generalized Method of Cells, can
adequately model these microstructures.


title:
Concurrent Supermassive Black Hole and Galaxy Growth: Linking
  Environment and Nuclear Activity in z = 2.23 H-alpha Emitters

abstract:
  We present results from a ~100 ks Chandra observation of the 2QZ Cluster
1004+00 structure at z = 2.23 (hereafter, 2QZ Clus). 2QZ Clus was originally
identified as an overdensity of four optically-selected QSOs at z = 2.23 within
a 15x15 arcmin^2 region. Narrow-band imaging in the near-IR revealed that the
structure contains an additional overdensity of 22 z = 2.23 Halpha-emitting
galaxies (HAEs), resulting in 23 unique z = 2.23 HAEs/QSOs. Our Chandra
observations reveal that 3 HAEs in addition to the 4 QSOs harbor powerfully
accreting supermassive black holes (SMBHs), with 2-10 keV luminosities of
~(8-60) x 10^43 ergs/s and X-ray spectral slopes consistent with unobscured
AGN. Using a large comparison sample of 210 HAEs in Chandra-COSMOS (C-COSMOS),
we find suggestive evidence that the AGN fraction increases with local HAE
galaxy density. The 2QZ Clus HAEs reside in a moderately overdense environment
(a factor of ~2 times over the field), and after excluding optically-selected
QSOs, we find the AGN fraction is a factor of ~3.5^+3.8_-2.2 times higher than
C-COSMOS HAEs in similar environments. Using stacking analyses of the Chandra
data and Herschel SPIRE observations at 250 um, we respectively estimate mean
SMBH accretion rates (Mdot) and star-formation rates (SFRs) for the 2QZ Clus
and C-COSMOS samples. We find that the mean 2QZ Clus HAE stacked 2-10 keV
luminosity is QSO-like (~6-10 x 10^43 ergs/s), and the implied Mdot/SFR \sim
(1.6-3.2) x10^-3 is broadly consistent with the local MBH/M* relation and z ~ 2
X-ray selected AGN. The C-COSMOS HAEs are on average an order of magnitude less
X-ray luminous and have Mdot/SFR \sim (0.2-0.4) x10^-3, comparable to z ~ 1-2
star-forming galaxies with similar mean X-ray luminosities. We estimate that a
periodic QSO phase with duty cycle ~2-8% would be sufficient to bring the
star-forming galaxies onto the local MBH/M* relation.


title: A sum rule for charged elementary particles

abstract:
  There may be a link between the quantum properties of the vacuum and the
parameters describing the properties of light propagation, culminating in a sum
over all types of elementary particles existing in Nature weighted only by
their squared charges and independent of their masses. The estimate for that
sum is of the order of 100.


title: Linear Koszul Duality II - Coherent sheaves on perfect sheaves

abstract:
  In this paper we continue the study (initiated in a previous article) of
linear Koszul duality, a geometric version of the standard duality between
modules over symmetric and exterior algebras. We construct this duality in a
very general setting, and prove its compatibility with morphisms of vector
bundles and base change.


title: Sparse Non-Negative Stencils for Anisotropic Diffusion

abstract:
  We introduce a new discretization scheme for Anisotropic Diffusion, AD-LBR,
on two and three dimensional cartesian grids. The main features of this scheme
is that it is non-negative, and has a stencil cardinality bounded by 6 in 2D,
by 14 in 3D, despite allowing diffusion tensors of arbitrary anisotropy. Our
scheme also has good spectral properties, which permits larger time steps and
avoids e.g. chessboard artifacts.
  AD-LBR relies on Lattice Basis Reduction, a tool from discrete mathematics
which has recently shown its relevance for the discretization on grids of
strongly anisotropic Partial Differential Equations. We prove that AD-LBR is in
2D asymptotically equivalent to a finite element discretization on an
anisotropic Delaunay triangulation, a procedure more involved and
computationally expensive. Our scheme thus benefits from the theoretical
guarantees of this procedure, for a fraction of its cost. Numerical experiments
in 2D and 3D illustrate our results.


title: Cloud Computing with Context Cameras

abstract:
  We summarize methods and plans to monitor and calibrate photometric
observations with our autonomous, robotic network of 2m, 1m and 40cm
telescopes. These are sited globally to optimize our ability to observe
time-variable sources. Wide field "context" cameras are aligned with our
network telescopes and cycle every 2 minutes through BVriz filters, spanning
our optical range. We measure instantaneous zero-point offsets and transparency
(throughput) against calibrators in the 5-12m range from the all-sky Tycho2
catalog, and periodically against primary standards. Similar measurements are
made for all our science images, with typical fields of view of 0.5 degrees.
These are matched against Landolt, Stetson and Sloan standards, and against
calibrators in the 10-17m range from the all-sky APASS catalog. Such
measurements provide pretty good instantaneous flux calibration, often to
better than 5%, even in cloudy conditions. Zero-point and transparency
measurements can be used to characterize, monitor and inter-compare sites and
equipment. When accurate calibrations of Target against Standard fields are
required, monitoring measurements can be used to select truly photometric
periods when accurate calibrations can be automatically scheduled and
performed.


title: Ergoregions in Magnetised Black Hole Spacetimes

abstract:
  The spacetimes obtained by Ernst's procedure for appending an external
magnetic field $B$ to a seed Kerr-Newman black hole are commonly believed to be
asymptotic to the static Melvin solution. We show that this is not in general
true. Unless the electric charge of the black hole satisfies $Q= jB(1+ 1/4 j^2
B^4)$, where $j$ is the angular momentum of the original seed solution, an
ergoregion extends all the way from the black hole horizon to infinity. We give
a self-contained account of the solution-generating procedure, including
including explicit formulae for the metric and the vector potential. In the
case when $Q= jB(1+ 1/4 j^2 B^4)$, we show that there is an arbitrariness in
the choice of asymptotically timelike Killing field $K_\Omega=
\partial/\partial t+ \Omega \partial/\partial \phi$, because there is no
canonical choice of $\Omega$. For one choice, $\Omega=\Omega_s$, the metric is
asymptotically static, and there is an ergoregion confined to the neighbourhood
of the horizon. On the other hand, by choosing $\Omega=\Omega_H$, so that
$K_{\Omega_H}$ is co-rotating with the horizon, then for sufficiently large $B$
numerical studies indicate there is no ergoregion at all. For smaller values,
in a range $B_-<B<B_+$, there is a toroidal ergoregion outside and disjoint
from the horizon. If $B\le B_-$ this ergoregion expands all the way to infinity
in a cylindrical region near to the rotation axis. For black holes whose size
is small compared to the Melvin radius 2/B, we recover Wald's result that it is
energetically favourable for the hole to acquire a charge $2jB$.


title:
Importance sampling for weighted binary random matrices with specified
  margins

abstract:
  A sequential importance sampling algorithm is developed for the distribution
that results when a matrix of independent, but not identically distributed,
Bernoulli random variables is conditioned on a given sequence of row and column
sums. This conditional distribution arises in a variety of applications and
includes as a special case the uniform distribution over zero-one tables with
specified margins. The algorithm uses dynamic programming to combine hard
margin constraints, combinatorial approximations, and additional non-uniform
weighting in a principled way to give state-of-the-art results.


title:
NMR Investigation of the Low Temperature Dynamics of solid 4He doped
  with 3He impurities

abstract:
  The lattice dynamics of solid 4He has been explored using pulsed NMR methods
to study the motion of 3He impurities in the temperature range where
experiments have revealed anomalies attributed to superflow or unexpected
viscoelastic properties of the solid 4He lattice. We report the results of
measurements of the nuclear spin-lattice and spin-spin relaxation times that
measure the fluctuation spectrum at high and low frequencies, respectively, of
the 3He motion that results from quantum tunneling in the 4He matrix. The
measurements were made for 3He concentrations 16<x_3<2000 ppm. For 3He
concentrations x_3 = 16 ppm and 24 ppm, large changes are observed for both the
spin-lattice relaxation time T_1 and the spin-spin relaxation time T_2 at
temperatures close to those for which the anomalies are observed in
measurements of torsional oscillator responses and the shear modulus. These
changes in the NMR relaxation rates were not observed for higher 3He
concentrations.


title:
H.E.S.S. Observations of the Binary System PSR B1259-63/LS 2883 around
  the 2010/2011 Periastron Passage

abstract:
  Aim. In this paper we present very high energy (VHE; E>100 GeV) data from the
\gamma-ray binary system PSR B1259-63/LS 2883 taken around its periastron
passage (15th of December 2010) with the High Energy Stereoscopic System
(H.E.S.S.) of Cherenkov Telescopes. We aim to search for a possible TeV
counterpart of the GeV flare detected by the Fermi LAT. In addition, we aim to
study the current periastron passage in the context of previous observations
taken at similar orbital phases, testing the repetitive behavior of the source.
  Methods. Observations at VHE were conducted with H.E.S.S. from 9th to 16th of
January 2011. The total dataset amounts to around 6 h of observing time.
  Results. The source is detected in the 2011 data at a significance level of
11.5\sigma\ revealing an averaged integral flux above 1 TeV of (1.01 \pm
0.18_{stat} \pm 0.20_{sys}) \times 10^{-12} cm^{-2}s^{-1}. The differential
energy spectrum follows a power-law shape with a spectral index \Gamma = 2.92
\pm 0.30_{stat} \pm 0.20_{sys} and a flux normalisation at 1 TeV of N_{0} =
1.95 \pm 0.32_{stat} \pm 0.39_{sys}) \times 10^{-12} TeV^{-1} cm^{-2} s^{-1}.
The measured lightcurve does not show any evidence for variability of the
source on the daily scale.
  Conclusions. The measured integral flux and the spectral shape of the 2011
data are compatible with the results obtained around previous periastron
passages. The absence of variability in the H.E.S.S. data indicates that the
GeV flare observed by Fermi LAT in the time period covered also by H.E.S.S.
observations originates in a different physical scenario than the TeV emission.
Additionaly, new results compared to those obtained in the observations which
were performed in 2004 at a similar orbital phase, further support the
hypothesis of the repetitive behavior of the source.


title:
(Extended Version) Algebraic Characterization of the Class of Languages
  recognized by Measure Only Quantum Automata

abstract:
  We study a model of one-way quantum automaton where only measurement
operations are allowed ($\mon$). We give an algebraic characterization of
$\lmo(\Sigma)$, showing that the syntactic monoids of the languages in
$\lmo(\Sigma)$ are exactly the $J$-trivial literally idempotent syntactic
monoids, where $J$ is the Green's relation determined by two-sided ideals. We
also prove that $\lmo(\Sigma)$ coincides with the literal variety of literally
idempotent piecewise testable regular languages. This allows us to prove the
existence of a polynomial time algorithm for deciding whether a regular
language belongs to $\lmo(\Sigma)$ and to discuss definability issues in terms
of the existential first-order logic $\Sigma_1[<]$ and the linear temporal
logic without the next operator LTLWN.


title:
Superconductivity of F-substituted LnOBiS2 (Ln = La, Ce, Pr, Nd, Yb)
  compounds

abstract:
  Polycrystalline samples of F-substituted LnOBiS2 (Ln = La, Ce, Pr, Nd, Yb)
compounds were synthesized by solid-state reaction. The samples were
characterized by x-ray diffraction measurements and found to have the ZrCuSiAs
crystal structure. Electrical resistivity and magnetic susceptibility
measurements were performed on all of the samples and specific heat
measurements were made on those with Ln = La, Ce, and Yb. All of these
compounds exhibit superconductivity in the range 1.9 K - 5.4 K, which has not
previously been reported for the compounds based on Ce, Pr, and Yb. The
YbO0.5F0.5BiS2 compounds was also found to exhibit magnetic order at ~2.7 K
that apparently coexists with superconductivity below 5.4 K.


title: Gene set bagging for estimating replicability of gene set analyses

abstract:
  Background: Significance analysis plays a major role in identifying and
ranking genes, transcription factor binding sites, DNA methylation regions, and
other high-throughput features for association with disease. We propose a new
approach, called gene set bagging, for measuring the stability of ranking
procedures using predefined gene sets. Gene set bagging involves resampling the
original high-throughput data, performing gene-set analysis on the resampled
data, and confirming that biological categories replicate. This procedure can
be thought of as bootstrapping gene-set analysis and can be used to determine
which are the most reproducible gene sets. Results: Here we apply this approach
to two common genomics applications: gene expression and DNA methylation. Even
with state-of-the-art statistical ranking procedures, significant categories in
a gene set enrichment analysis may be unstable when subjected to resampling.
Conclusions: We demonstrate that gene lists are not necessarily stable, and
therefore additional steps like gene set bagging can improve biological
inference of gene set analysis.


title:
Intrinsic cell factors that influence tumourigenicity in cancer stem
  cells - towards hallmarks of cancer stem cells

abstract:
  Since the discovery of a cancer initiating side population in solid tumours,
studies focussing on the role of so-called cancer stem cells in cancer
initiation and progression have abounded. The biological interrogation of these
cells has yielded volumes of information about their behaviour, but there has,
as of yet, not been many actionable generalised theoretical conclusions. To
address this point, we have created a hybrid, discrete/continuous computational
cellular automaton model of a generalised stem-cell driven tissue and explored
the phenotypic traits inherent in the inciting cell and the resultant tissue
growth. We identify the regions in phenotype parameter space where these
initiating cells are able to cause a disruption in homeostasis, leading to
tissue overgrowth and tumour formation. As our parameters and model are
non-specific, they could apply to any tissue cancer stem-cell and do not assume
specific genetic mutations. In this way, our model suggests that targeting
these phenotypic traits could represent generalizable strategies across cancer
types and represents a first attempt to identify the hallmarks of cancer stem
cells.


title:
Scanning Tunneling Microscopy of Gate Tunable Topological Insulator
  Bi2Se3 Thin Films

abstract:
  Electrical field control of the carrier density of topological insulators
(TI) has greatly expanded the possible practical use of these materials.
However, the combination of low temperature local probe studies and a gate
tunable TI device remains challenging. We have overcome this limitation by
scanning tunneling microscopy and spectroscopy measurements on in-situ
molecular beam epitaxy growth of Bi2Se3 films on SrTiO3 substrates with
pre-patterned electrodes. Using this gating method, we are able to shift the
Fermi level of the top surface states by 250 meV on a 3 nm thick Bi2Se3 device.
We report field effect studies of the surface state dispersion, band gap, and
electronic structure at the Fermi level.


title:
Classical Forces on Solitons in Finite and Infinite, Nonlinear, Planar
  Waveguides

abstract:
  Conservation equations for the mass, linear momentum and energy densities of
solitons propagating in finite, infinite and periodic, nonlinear, planar
waveguides and governed by the nonlinear Schr\"odinger equation are derived.
These conservation equations are used to determine classical force densities
which are compared with those derived by drawing a quantum mechanics analogy
between the propagation of solitons and the motion of a quantum particle in a
nonlinear potential well.


title: Endpoint Logarithms in e+e- -> J/psi + eta_c

abstract:
  We investigate the origin of the double logarithms of Q^2/m_c^2 that appear
in the calculation of the cross section for e+e- -> J/psi + eta_c at
next-to-leading order in alpha_s. We find that, diagram-by-diagram, the double
logarithms are accounted for by Sudakov double logarithms and endpoint double
logarithms. The Sudakov double logarithms cancel in the sum over all diagrams,
but the endpoint double logarithms do not. We reinterpret the endpoint double
logarithms in terms of a leading region of loop integration in which a
spectator fermion line becomes soft. This reinterpretation may simplify the
process of establishing an all-orders factorization theorem for this
helicity-flip process, which, in turn, might allow one to resum logarithms of
Q^2/m_c^2 to all orders in alpha_s.


title:
Quantum simulation of a spin polarization device in an electron
  microscope

abstract:
  A proposal for an electron-beam device that can act as an efficient
spin-polarization filter has been recently put forward [E. Karimi et al., Phys.
Rev. Lett. 108, 044801 (2012)]. It is based on combining the recently developed
diffraction technology for imposing orbital angular momentum to the beam with a
multipolar Wien filter inducing a sort of artificial non-relativistic
spin-orbit coupling. Here we reconsider the proposed device with a fully
quantum-mechanical simulation of the electron beam propagation, based on the
well established multi-slice method, supplemented with a Pauli term for taking
into account the spin degree of freedom. Using this upgraded numerical tool, we
study the feasibility and practical limitations of the proposed method for
spin-polarizing a free electron beam


title: Optimal Networks of Future Gravitational-Wave Telescopes

abstract:
  We aim to find the optimal site locations for a hypothetical network of 1-3
triangular gravitational-wave telescopes. We define the following N-telescope
figures of merit (FoMs) and construct three corresponding metrics: (a)
capability of reconstructing the signal polarization; (b) accuracy in source
localization; and (c) accuracy in reconstructing the parameters of a standard
binary source. We also define a combined metric that takes into account the
three FoMs with practically equal weight. After constructing a geomap of
possible telescope sites, we give the optimal 2-telescope networks for the four
FoMs separately in example cases where the location of the first telescope has
been predetermined. We found that based on the combined metric, placing the
first telescope to Australia provides the most options for optimal site
selection when extending the network with a second instrument. We suggest
geographical regions where a potential second and third telescope could be
placed to get optimal network performance in terms of our FoMs. Additionally,
we use a similar approach to find the optimal location and orientation for the
proposed LIGO-India detector within a five-detector network with Advanced LIGO
(Hanford), Advanced LIGO (Livingston), Advanced Virgo, and KAGRA. We found that
the FoMs do not change greatly in sites within India, though the network can
suffer a significant loss in reconstructing signal polarizations if the
orientation angle of an L-shaped LIGO-India is not set to the optimal value of
~58.2deg(+k*90deg) (measured counterclockwise from East to the bisector of the
arms).


title:
Exact separation phenomenon for the eigenvalues of large
  Information-Plus-Noise type matrices. Application to spiked models

abstract:
  We consider large Information-Plus-Noise type matrices of the form
$M_N=(\sigma \frac{X_N}{\sqrt{N}}+A_N)(\sigma \frac{X_N}{\sqrt{N}}+A_N)^*$
where $X_N$ is an $n \times N$ ($n\leq N)$ matrix consisting of independent
standardized complex entries, $A_N$ is an $n \times N$ nonrandom matrix and
$\sigma>0$. As $N$ tends to infinity, if $n/N \rightarrow c\in ]0,1]$ and if
the empirical spectral measure of $A_N A_N^*$ converges weakly to some
compactly supported probability distribution $\nu \neq \delta_0$, Dozier and
Silverstein established that almost surely the empirical spectral measure of
$M_N$ converges weakly towards a nonrandom distribution $\mu_{\sigma,\nu,c}$.
Bai and Silverstein proved, under certain assumptions on the model, that for
some closed interval in $]0;+\infty[$ outside the support of
$\mu_{\sigma,\nu,c}$ satisfying some conditions involving $A_N$, almost surely,
no eigenvalues of $M_N$ will appear in this interval for all $N$ large. In this
paper, we carry on with the study of the support of the limiting spectral
measure previously investigated by Dozier and Silverstein and later by Vallet,
Loubaton and Mestre and Loubaton and P. Vallet, and we show that, under almost
the same assumptions as Bai and Silvertein, there is an exact separation
phenomenon between the spectrum of $M_N$ and the spectrum of $A_NA_N^*$: to a
gap in the spectrum of $M_N$ pointed out by Bai and Silverstein, it corresponds
a gap in the spectrum of $A_NA_N^*$ which splits the spectrum of $A_NA_N^*$
exactly as that of $M_N$. We use the previous results to characterize the
outliers of spiked Information-Plus-Noise type models.


title: Topological invariants for the fractional quantum Hall states

abstract:
  We calculate a topological invariant, whose value would coincide with the
Chern number in case of integer quantum Hall effect, for fractional quantum
Hall states. In case of Abelian fractional quantum Hall states, this invariant
is shown to be equal to the trace of the K-matrix. In case of non-Abelian
fractional quantum Hall states, this invariant can be calculated on a case by
case basis from the conformal field theory describing these states. This
invariant can be used, for example, to distinguish between different fractional
Hall states numerically even though, as a single number, it cannot uniquely
label distinct states.


title:
On two dimensional non-abelian chiral lattice gauge theories in
  Ginsparg-Wilson formalism

abstract:
  Defining chiral lattice gauge theories in the Ginsparg-Wilson formalism is
complicated by the so-called fermion measure problem. It has been proven for
the abelian theories that smooth well-behaved fermion measure exists if and
only if the anomaly-free condition is granted, and the same was shown to hold
in perturbative theories for non-abelian gauge groups, but the non-perturbative
proof is absent. In this paper, we consider a simpler problem in 2-d and
present a proof for the existence of smooth and gauge invariant fermion measure
on the gauge field configuration space with zero field strengths for arbitrary
compact Lie groups, provided the anomaly-free conditions are satisfied. It is
conjectured that such consideration is sufficient for the unknown full proof.


title: Polyakov loop in 2+1 flavor QCD

abstract:
  We study the temperature dependence of the renormalized Polyakov loop in 2+1
flavor QCD for temperatures T<210 MeV. We extend previous calculations by the
HotQCD collaboration using the highly improved staggered quark action and
perform a continuum extrapolation of the renormalized Polyakov loop. We compare
the lattice results with the prediction of non-interacting static-light hadron
resonance gas, which describes the temperature dependence of the renormalized
Polyakov loop up to T<140 MeV but fails above that temperature. Furthermore, we
discuss the temperature dependence of the light and strange quark condensates.


title:
A Quantum Mechanics Analogy for the Nonlinear Schr\"{o}dinger Equation
  in the Finite Line

abstract:
  A quantum mechanics analogy is used to determine the forces acting on and the
energies of solitons governed by the nonlinear Schr\"odinger equation in finite
intervals with periodic and with homogeneous Dirichlet, Neumann and Robin
boundary conditions. It is shown that the energy densities remain nearly
constant for periodic, while they undergo large variations for homogeneous,
boundary conditions. The largest variations in the force and energy densities
occur for the Neumann boundary conditions, but, for all the boundary conditions
considered in this paper, the magnitudes of these forces and energies recover
their values prior to the interaction of the soliton with the boundary, after
the soliton rebound process is completed. It is also shown that the quantum
momentum changes sign but recovers its original value after the collision of
the soliton with the boundaries. The asymmetry of the Robin boundary conditions
shows different dynamic behaviour at the left and right boundaries of the
finite interval.


title: Stability of solutions of certain extended Ricci flow systems

abstract:
  We consider four extended Ricci flow systems---that is, Ricci flow coupled
with other geometric flows---and prove dynamical stability of certain classes
of stationary solutions of these flows. The systems include Ricci flow coupled
with harmonic map flow (studied abstractly and in the context of Ricci flow on
warped products), Ricci flow coupled with both harmonic map flow and Yang-Mills
flow, and Ricci flow coupled with heat flow for the torsion of a
metric-compatible connection. The methods used to prove stability follow a
program outlined by Guenther, Isenberg, and Knopf, which uses maximal
regularity theory for quasilinear parabolic systems and a result of Simonett.


title:
Efficient Identification of Equivalences in Dynamic Graphs and Pedigree
  Structures

abstract:
  We propose a new framework for designing test and query functions for complex
structures that vary across a given parameter such as genetic marker position.
The operations we are interested in include equality testing, set operations,
isolating unique states, duplication counting, or finding equivalence classes
under identifiability constraints. A motivating application is locating
equivalence classes in identity-by-descent (IBD) graphs, graph structures in
pedigree analysis that change over genetic marker location. The nodes of these
graphs are unlabeled and identified only by their connecting edges, a
constraint easily handled by our approach. The general framework introduced is
powerful enough to build a range of testing functions for IBD graphs, dynamic
populations, and other structures using a minimal set of operations. The
theoretical and algorithmic properties of our approach are analyzed and proved.
Computational results on several simulations demonstrate the effectiveness of
our approach.


title:
Removing batch effects for prediction problems with frozen surrogate
  variable analysis

abstract:
  Batch effects are responsible for the failure of promising genomic prognos-
tic signatures, major ambiguities in published genomic results, and retractions
of widely-publicized findings. Batch effect corrections have been developed to
re- move these artifacts, but they are designed to be used in population
studies. But genomic technologies are beginning to be used in clinical
applications where sam- ples are analyzed one at a time for diagnostic,
prognostic, and predictive applica- tions. There are currently no batch
correction methods that have been developed specifically for prediction. In
this paper, we propose an new method called frozen surrogate variable analysis
(fSVA) that borrows strength from a training set for individual sample batch
correction. We show that fSVA improves prediction ac- curacy in simulations and
in public genomic studies. fSVA is available as part of the sva Bioconductor
package.


title: The consistency and convergence of K-energy minimizing movements

abstract:
  We show that K-energy minimizing movements agree with smooth solutions to
Calabi flow as long as the latter exist. As corollaries we conclude that in a
general Kahler class long time solutions of Calabi flow minimize both K-energy
and Calabi energy. Lastly, by applying convergence results from the theory of
minimizing movements, these results imply that long time solutions to Calabi
flow converge in the weak distance topology to minimizers of the K-energy
functional on the metric completion of the space of Kahler metrics, assuming
one exists.


title: De-noising procedures for frame operators

abstract:
  The present paper provides a comprehensive study of de-noising properties of
frames and, in particular, tight frames, which constitute one of the most
popular tools in contemporary signal processing. The objective of the paper is
to bridge the existing gap between mathematical and statistical theories on one
hand and engineering practice on the other and explore how one can take
advantage of a specific structure of a frame in contrast to an arbitrary
collection of vectors or an orthonormal basis. For both the general and the
tight frames, the paper presents a set of practically implementable de-noising
techniques which take frame induced correlation structures into account. These
results are supplemented by an examination of the case when the frame is
constructed as a collection of orthonormal bases. In particular,
recommendations are given for aggregation of the estimators at the stage of
frame coefficients. The paper is concluded by a finite sample simulation study
which confirms that taking frame structure and frame induced correlations into
account indeed improves de-noising precision.


title: Memory-efficient w-projection with the fast Gauss transform

abstract:
  We describe a method performing w-projection using the fast Gauss transform
of Strain (1991). We derive the theoretical performance, and simulate the
actual performance for a range of w for a canonical array. While our
implementation is dominated by overheads, we argue that this approach could for
the basis of a higher-performing algorithms with particular application to the
Square Kilometer Array.


title: The Nonlinear Schr\"{o}dinger Equation in the Finite Line

abstract:
  A numerical study of the nonlinear Schr\"odinger (NLS) equation subject to
homogeneous Dirichlet, Neumann and Robin boundary conditions in the finite line
is presented. The results are compared with both the exact analytical ones for
the initial-value problem (IVP) of the NLS equation and the numerical ones for
periodic boundary conditions. It is shown that initial solutions obtained by
truncating the exact N-soliton solution of the IVP of the NLS equation into a
finite interval develop solitary waves that behave as solitons, even after
collisions with the boundaries. For periodic and homogeneous Dirichlet and
Neumann boundary conditions, it is observed that the interaction between
solitons and boundaries is equivalent to the collision between solitons in IVP
or quarterplane problems. It is shown that for homogeneous Robin boundary
conditions, boundary layers that trap and delay the soliton are formed at the
boundaries. Phase diagrams for the soliton amplitude at the boundary points and
for the soliton's maximum amplitude show a recurrent phenomenon, and are
similar to those of the cubic Duffing equation. It is also shown that the phase
diagrams are strong functions of the parameter that defines the Robin boundary
conditions. A method of images, similar to the one used in potential theory, is
developed for the NLS equation in the quarterplane with homogeneous Dirichlet
and Neumann boundary conditions at the finite boundary.


title: On the mechanism of elasto-inertial turbulence

abstract:
  Elasto-inertial turbulence is a new state of turbulence found in flows with
polymer additives . The dynamics of turbulence generated and controlled by such
additives is investigated from the perspective of the coupling between polymer
dynamics and flow structures. Direct numerical simulations of channel flow with
Reynolds numbers ranging from 1000 to 6000 (based on the bulk and the channel
height) are used to study the formation and dynamics of elastic instabilities
and their effects on the flow. The resulting mechanism of interactions between
polymer dynamics and the flow helps resolve a long-standing controversy in the
understanding of polymer drag reduction and explains the phenomenon of early
turbulence, or onset of turbulence at lower Reynolds numbers than for Newtonian
flows, previously observed in polymeric flows. Polymers also point out an
interesting analogy with the forward and backward energy cascade in
two-dimensional turbulence.


title: The brightest ULIRG:watching the birth of a quasar

abstract:
  The extreme ULIRG F00183-7111 has recently been found to have a radio-loud
AGN with jets in its centre, representing an extreme example of the class of
radio-loud AGNs buried within dusty star-forming galaxies. This source appears
to be a rare example of a ULIRG glimpsed in the (presumably) brief period as it
changes from "quasar mode" to "radio mode" activity. Such transition stages
probably account for many of the high-redshift radio-galaxies and extreme
high-redshift ULIRGs, and so this object at the relatively low redshift of
0.328 offers a rare opportunity to study this class of objects in detail. We
have also detected the CO signal from this galaxy with the ATCA, and here
describe the implications of this detection for future ULIRG studies.


title:
Stability and electronic structure of covalently functionalized graphene
  layers

abstract:
  We present exemplary results of extensive studies of mechanical, electronic
and transport properties of covalent functionalization of graphene monolayers
(GML) with -NH2. We report new results of ab initio studies of covalent
functionalization of GML with -NH2 groups up to 12.5% concentration. Our
studies are performed in the framework of the density functional theory (DFT)
and non-equilibrium Green's function (NEGF). We discuss the stability
(adsorption energy), elastic moduli, electronic structure, band gaps, and
effective electron masses as a function of the density of the adsorbed
molecules. We also show the conductance and I(V) characteristic of these
systems. Generally, the stability of the functionalized graphene layers
decreases with the growing concentration of attachments and we determine the
critical density of the molecules that can be chemisorbed on the surface of
GLs. Because of local deformations of GLs and sp3 rehybridization of the bonds
induced by fragments, elastic moduli decrease with increasing number of groups.
Simultaneously, we observe that the functionalizing molecules stretch the
graphenes lattice, the effect being more pronounced for higher concentration of
adsorbed molecules. We find out that the GLs functionalization leads in many
cases to the opening of the graphene band gap (up to 0.5302 eV for 12.5%
concentration) and can be therefore utilized in graphene devices. The new HOMO
and LUMO originate mostly from the impurity bands induced by the
functionalization and they exhibit parabolic dispersion with electron effective
masses comparable to ones in silicon or gallium nitride.


title: Observations of the WASP-2 System by the APOSTLE Program

abstract:
  We present transit observations of the WASP-2 exoplanet system by the Apache
Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) program. Model
fitting to these data allows us to improve measurements of the hot-Jupiter
exoplanet WASP-2b and its orbital parameters by a factor of ~2 over prior
studies; we do not find evidence for transit depth variations. We do find
reduced chi^2 values greater than 1.0 in the observed minus computed transit
times. A sinusoidal fit to the residuals yields a timing semi-amplitude of 32
seconds and a period of 389 days. However, random rearrangements of the data
provide similar quality fits, and we cannot with certainty ascribe the timing
variations to mutual exoplanet interactions. This inconclusive result is
consistent with the lack of incontrovertible transit timing variations (TTVs)
observed in other hot-Jupiter systems. This outcome emphasizes that unique
recognition of TTVs requires dense sampling of the libration cycle (e.g.
continuous observations from space-based platforms). However, even in systems
observed with the Kepler spacecraft, there is a noted lack of transiting
companions and TTVs in hot-Jupiter systems. This result is more meaningful, and
indicates that hot-Jupiter systems, while they are easily observable from the
ground, do not appear to be currently configured in a manner favorable to the
detection of TTVs. The future of ground-based TTV studies may reside in
resolving secular trends, and/or implementation at extreme quality observing
sites to minimize atmospheric red noise.


title: Electronic structure of graphene functionalized with boron and nitrogen

abstract:
  We present a theoretical study of the structural and electronic properties of
graphene monolayer functionalized with boron and nitrogen atoms substituting
carbon atoms. Our study is based on the ab initio calculations in the framework
of the density functional theory. We calculate the binding energies of the
functionalized systems, changes in the morphology caused by functionalization,
and further the band gap energy as a function of the concentration of dopants.
Moreover, we address the problem of possible clustering of dopants at a given
concentration. We define the clustering parameter to quantify the dependence of
the properties of the functionalized systems on the distribution of B/N atoms.
  We show that clustering of B/N atoms in graphene is energetically unfavorable
in comparison to the homogenous distribution of dopants. For most of the
structures, we observe a nonzero energy gap that is only slightly dependent on
the concentration of the substituent atoms.


title: Particle-in-cell simulations of a current-free double layer

abstract:
  Current-free double layers of the type reported in plasmas in the presence of
an expanding magnetic field [C. Charles and R. W. Boswell, Appl. Phys. Lett.
82, 1356 (2003)] are modeled theoretically and with particle-in-cell/Monte
Carlo simulations. Emphasis is placed on determining what mechanisms affect the
electron velocity distribution function (EVDF) and how the EVDF influences the
double layer. A theoretical model is developed based on depletion of electrons
in certain velocity intervals due to wall losses and repletion of these
intervals due to ionization and elastic electron scattering. This model is used
to predict the range of neutral pressures over which a double layer can form
and the electrostatic potential drop of the double layer. These predictions are
shown to compare well with simulation results.


title:
A finite element solver and energy stable coupling for 3D and 1D fluid
  models

abstract:
  The paper develops a solver based on a conforming finite element method for a
3D--1D coupled incompressible flow problem. New coupling conditions are
introduced to ensure a suitable bound for the cumulative energy of the model.
We study the stability and accuracy of the discretization method, and the
performance of some state-of-the-art linear algebraic solvers for such flow
configurations. Motivated by the simulation of the flow over inferior vena cava
(IVC) filter, we consider the coupling of a 1D fluid model and a 3D fluid model
posed in a domain with anisotropic inclusions. The relevance of our approach to
realistic cardiovascular simulations is demonstrated by computing a blood flow
over a model IVC filter.


title:
Interactions of solitons with a Gaussian barrier: Splitting and
  recombination in quasi-1D and 3D

abstract:
  The interaction of matter-wave solitons with a potential barrier is a
fundamentally important problem, and the splitting and subsequent recombination
of the soliton by the barrier is the essence of soliton matter-wave
interferometry. We demonstrate the three-dimensional (3D) character of the
interactions in the case relevant to ongoing experiments, where the number of
atoms in the soliton is sufficiently large that the soliton is close to
collapse. The mean-field description is quite accurate, but the proximity to
the collapse threshold makes the use of the 1D Gross-Pitaevskii equation (GPE)
irrelevant. We examine the soliton dynamics in the framework of the effectively
1D nonpolynomial Schr{\"{o}}dinger equation (NPSE), which admits the collapse
in a modified form, and in parallel we use the full 3D GPE. Both approaches
produce results which are very different from those produced in recent work
which used the 1D cubic GPE. The features observed in both the NPSE and the 3D
GPE include (a) an increase in the first reflection coefficient for increasing
barrier height and decreasing atom number; (b) strong modulation in the
secondary reflection/recombination probability vs. barrier height; (c) a
pronounced asymmetry in the oscillation amplitudes of the transmitted and
reflected fragments; (d) an enhancement of the transverse excitations as the
number of atoms is increased. We also explore effects produced by variations of
the barrier width and outcomes of the secondary collision upon phase imprinting
on the fragment in one arm of the interferometer.


title:
System-environment coupling derived by Maxwell's boundary conditions
  from weak to ultrastrong light-matter coupling regime

abstract:
  In the standard theory of cavity quantum electrodynamics (QED), coupling
between photons inside and outside a cavity (cavity system and photonic
reservoir) is given conserving the total number of photons. However, when the
cavity photons (ultra)strongly interact with atoms or excitations in matters,
the system-reservoir coupling must be determined from a more fundamental
viewpoint. Based on the Maxwell's boundary conditions in the QED theory for
dielectric media, we derive the quantum Langevin equation and input-output
relation, in which the total number of polaritons (not photons) inside the
cavity and photons outside is conserved.


title: Sequences of Open Riemannian Manifolds with Boundary

abstract:
  We consider sequences of open Riemannian manifolds with boundary that have no
regularity conditions on the boundary. To define a reasonable notion of a limit
of such a sequence, we examine "$\delta$ inner regions" which avoid the
boundary by a distance $\delta$. We prove Gromov-Hausdorff compactness theorems
for sequences of these "$\delta$ inner regions". We then build "glued limit
spaces" out of the Gromov-Hausdorff limits of these $\delta$ interior regions
and study the properties of these glued limit spaces. Our main applications
assume the sequence is noncollapsing and has nonnegative Ricci curvature. We
include open questions.


title: Isomorphism between two realizations of the Yangian Y(so_3)

abstract:
  The isomorphism between Drinfeld's new realization and the FRT realization is
proved for the Yangian algebra Y(so_3) by using Gauss decomposition.


title: Spectral calculus and Lipschitz extension for barycentric metric spaces

abstract:
  The metric Markov cotype of barycentric metric spaces is computed, yielding
the first class of metric spaces that are not Banach spaces for which this
bi-Lipschitz invariant is understood. It is shown that this leads to new
nonlinear spectral calculus inequalities, as well as a unified framework for
Lipschitz extension, including new Lipschitz extension results for CAT(0)
targets. An example that elucidates the relation between metric Markov cotype
and Rademacher cotype is analyzed, showing that a classical Lipschitz extension
theorem of Johnson, Lindenstrauss and Benyamini is asymptotically sharp.


title: Multiscale Discriminant Saliency for Visual Attention

abstract:
  The bottom-up saliency, an early stage of humans' visual attention, can be
considered as a binary classification problem between center and surround
classes. Discriminant power of features for the classification is measured as
mutual information between features and two classes distribution. The estimated
discrepancy of two feature classes very much depends on considered scale
levels; then, multi-scale structure and discriminant power are integrated by
employing discrete wavelet features and Hidden markov tree (HMT). With wavelet
coefficients and Hidden Markov Tree parameters, quad-tree like label structures
are constructed and utilized in maximum a posterior probability (MAP) of hidden
class variables at corresponding dyadic sub-squares. Then, saliency value for
each dyadic square at each scale level is computed with discriminant power
principle and the MAP. Finally, across multiple scales is integrated the final
saliency map by an information maximization rule. Both standard quantitative
tools such as NSS, LCC, AUC and qualitative assessments are used for evaluating
the proposed multiscale discriminant saliency method (MDIS) against the
well-know information-based saliency method AIM on its Bruce Database wity
eye-tracking data. Simulation results are presented and analyzed to verify the
validity of MDIS as well as point out its disadvantages for further research
direction.


title:
Unified origin for visible and dark matter in a baryon-symmetric
  universe from a first-order phase transition

abstract:
  In a baryon-symmetric universe, the baryon asymmetry observed for visible
matter is matched by an equal and opposite asymmetry for dark matter, thereby
closely connecting the number densities of both types of matter. This is a
necessary step towards the goal of explaining the mystery of why the visible
and dark matter densities are observed to be similar. In this talk, a way of
producing such a universe from bubble nucleation during a first-order phase
transition is reviewed. The process is an analog of electroweak baryogenesis.


title:
Efficient Sample Reuse in Policy Gradients with Parameter-based
  Exploration

abstract:
  The policy gradient approach is a flexible and powerful reinforcement
learning method particularly for problems with continuous actions such as robot
control. A common challenge in this scenario is how to reduce the variance of
policy gradient estimates for reliable policy updates. In this paper, we
combine the following three ideas and give a highly effective policy gradient
method: (a) the policy gradients with parameter based exploration, which is a
recently proposed policy search method with low variance of gradient estimates,
(b) an importance sampling technique, which allows us to reuse previously
gathered data in a consistent way, and (c) an optimal baseline, which minimizes
the variance of gradient estimates with their unbiasedness being maintained.
For the proposed method, we give theoretical analysis of the variance of
gradient estimates and show its usefulness through extensive experiments.


title: Algebra retracts and Stanley-Reisner rings

abstract:
  In a paper from 2002, Bruns and Gubeladze conjectured that graded algebra
retracts of polytopal algebras over a field $k$ are again polytopal algebras.
Motivated by this conjecture, we prove that graded algebra retracts of
Stanley-Reisner rings over a field $k$ are again Stanley-Reisner rings.
Extending this result further, we give partial evidence for a conjecture saying
that monomial quotients of standard graded polynomial rings over $k$ descend
along graded algebra retracts.


title: Performance of a novel fast transients detection system

abstract:
  We investigate the S/N of a new incoherent dedispersion algorithm optimized
for FPGA-based architectures intended for deployment on ASKAP and other SKA
precursors for fast transients surveys. Unlike conventional CPU- and
GPU-optimized incoherent dedispersion algorithms, this algorithm has the
freedom to maximize the S/N by way of programmable dispersion profiles that
enable the inclusion of different numbers of time samples per spectral channel.
This allows, for example, more samples to be summed at lower frequencies where
intra-channel dispersion smearing is larger, or it could even be used to
optimize the dedispersion sum for steep spectrum sources. Our analysis takes
into account the intrinsic pulse width, scatter broadening, spectral index and
dispersion measure of the signal, and the system's frequency range, spectral
and temporal resolution, and number of trial dedispersions. We show that the
system achieves better than 80% of the optimal S/N where the temporal
resolution and the intra-channel smearing time are smaller than a quarter of
the average width of the pulse across the system's frequency band (after
including scatter smearing). Coarse temporal resolutions suffer a
Delta_t^(-1/2) decay in S/N, and coarse spectral resolutions cause a
Delta_nu^(-1/2) decay in S/N, where Delta_t and Delta_nu are the temporal and
spectral resolutions of the system, respectively. We show how the system's S/N
compares with that of matched filter and boxcar filter detectors. We further
present a new algorithm for selecting trial dispersion measures for a survey
that maintains a given minimum S/N performance across a range of dispersion
measures.


title:
Giant Magnetoresistance Effect in the Metal-Insulator Transition of
  Pyrochlore Oxide Nd2Ir2O7

abstract:
  We investigated the magnetoresistance (MR) effect of the pyrochlore oxide
Nd2Ir2O7, which shows a metal-insulator transition at T_MI =33 K. A small
positive MR effect was observed in the metallic state above T_MI, while a large
negative MR effect was observed in the insulating state below T_MI . MR effects
exceeding 3000% were found at 1 K at a field of 9 T. As a result, we confirmed
the crossover from the insulating state to a state with a small or partial band
gap in a field up to 56 T. Furthermore, from the MR effect in Eu2Ir2O7 (T_MI =
120 K) and Gd$_2$Ir$_2$O$_7$ (T_MI = 127 K), we revealed that the large
negative MR effect of the pyrochlore iridate Ln2Ir2O7 depends on the magnetism
of the lanthanide Ln^{3+} ion. The d-f interaction plays a significant role in
the large negative MR effect in the insulating state.


title: Resultants and Gravity Amplitudes

abstract:
  Two very different formulations of the tree-level S-matrix of N=8 Einstein
supergravity in terms of rational maps are known to exist. In both
formulations, the computation of a scattering amplitude of n particles in the k
R-charge sector involves an integral over the moduli space of certain
holomorphic maps of degree d=k-1. In this paper we show that both formulations
can be simplified when written in a manifestly parity invariant form as
integrals over holomorphic maps of bi-degree (d,n-d-2). In one formulation the
full integrand becomes directly the product of the resultants of each of the
two maps defining the one of bi-degree (d,n-d-2). In the second formulation, a
very different structure appears. The integrand contains the determinant of a
(n-3)x(n-3) matrix and a 'Jacobian'. We prove that the determinant is a
polynomial in the coefficients of the maps and contains the two resultants as
factors.


title: Effectiveness of the GT200 Molecular Detector: A Double-Blind Test

abstract:
  The GT200 is a device that has been extensively used by the Mexican armed
forces to remotely detect and identify substances such as drugs and explosives.
A double blind experiment has been performed to test its effectivity. In
seventeen out of twenty attempts, the GT200 failed in the hands of certified
operators to find more than 1600 amphetamine pills and four bullets hidden in a
randomly chosen cardboard box out of eight identical boxes distributed within a
90m$\times$20m ballroom. This result is compatible with the 1/8 probability
expected for a completely ineffectual device, and is incompatible with even a
moderately effective working one.


title: Finiteness conditions in covers of Poincar\'e duality spaces

abstract:
  A closed 4-manifold (or, more generally, a finite $PD_4$-space) has a
finitely dominated infinite regular covering space if and only if either its
universal covering space is finitely dominated or it is finitely covered by the
mapping torus of a self homotopy equivalence of a $PD_3$-complex.


title: All-optical Compton gamma-ray source

abstract:
  One of the major goals of research for laser-plasma accelerators is the
realization of compact sources of femtosecond X-rays. In particular, using the
modest electron energies obtained with existing laser systems, Compton
scattering a photon beam off a relativistic electron bunch has been proposed as
a source of high-energy and high-brightness photons. However, laser-plasma
based approaches to Compton scattering have not, to date, produced X-rays above
1 keV. Here, we present a simple and compact scheme for a Compton source based
on the combination of a laser-plasma accelerator and a plasma mirror. This
approach is used to produce a broadband spectrum of X-rays extending up to
hundreds of keV and with a 10,000-fold increase in brightness over Compton
X-ray sources based on conventional accelerators. We anticipate that this
technique will lead to compact, high-repetition-rate sources of ultrafast
(femtosecond), tunable (X- through gamma-ray) and low-divergence (~1 degree)
photons from source sizes on the order of a micrometre.


title:
63,65Cu Nuclear Resonance Study of the Coupled Spin Dimers and Chains
  Compound Cu2Fe2Ge4O13

abstract:
  Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) of Cu
have been measured in a coupled spin dimers and chains compound Cu2Fe2Ge4O13.
Cu NQR has also been measured in an isostructural material Cu2Sc2Ge4O13
including only spin dimers. Comparison of the temperature dependence of the
63Cu nuclear spin-lattice relaxation rate between the two compounds reveals
that the Fe chains in Cu2Fe2Ge4O13 do not change a spin gap energy of the Cu
dimers from that in Cu2Sc2Ge4O13, contributing additionally to the relaxation
rate at the Cu site. A modestly large internal field of 3.39 T was observed at
the Cu site in the antiferromagnetic state of Cu2Fe2Ge4O13 at 4.2 K, which is
partly because of quantum reduction of the ordered moment of a Cu atom. The
internal field and the ordered moment of Cu are noncollinear due to large
anisotropy of the hyperfine interaction at the Cu site. A model analysis of the
internal field based on the fourfold planar coordination of Cu suggests that a
3d hole of the Cu2+ ion is mainly in the d(x2-y2) orbital state.


title:
X-ray plateaus followed by sharp drops in GRBs 060413, 060522, 060607A
  and 080330: Further evidences for central engine afterglow from Gamma-ray
  Bursts

abstract:
  The X-ray afterglows of GRBs 060413, 060522, 060607A and 080330 are
characterized by plateaus that are followed by very sharp drops. An X-ray
plateau is interpretable within the framework of the external forward shock
model but the sharp drop is not. In this work we interpret these peculiar X-ray
afterglow data as the central engine afterglows from some magnetized central
engines, plausibly magnetars. In this model, the X-ray afterglows are powered
by the internal magnetic energy dissipation and the sudden drop is caused by
the collapse of the magnetar. Accordingly, the X-ray plateau photons should
have a high linear polarization, which can be tested by the future X-ray
polarimetry.


title: Semistable periods of finite slope families

abstract:
  We introduce the notion of finite slope families to encode the local
properties of the p-adic families of Galois representations appearing in the
work of Harris, Lan, Taylor and Thorne on the construction of Galois
representations for (non-self dual) regular algebraic cuspidal automorphic
representations of GL(n) over CM fields. Our main result is to prove the
analytic continuation of semi-stable (and crystalline) periods for such
families.


title: Three Dimensional Broadband Tunable Terahertz Metamaterials

abstract:
  We present optically tunable magnetic 3D metamaterials at terahertz (THz)
frequencies which exhibit a tuning range of ~30% of the resonance frequency.
This is accomplished by fabricating 3D array structures consisting of
double-split-ring resonators (DSRRs) on silicon-on-sapphire, fabricated using
multilayer electroplating. Photoexcitation of free carriers in the silicon
within the capacitive region of the DSRR results in a red-shift of the resonant
frequency from 1.74 THz to 1.16 THz. The observed frequency shift leads to a
transition from a magnetic-to-bianisotropic response as verified through
electromagnetic simulations and parameter retrieval. Our approach extends
dynamic metamaterial tuning to magnetic control, and may find applications in
switching and modulation, polarization control, or tunable perfect absorbers.


title:
Twist-3 light-cone distribution amplitudes of the scalar mesons within
  the QCD sum rules and their application to the $B \to S$ transition form
  factors

abstract:
  We investigate the twist-3 light-cone distribution amplitudes (LCDAs) of the
scalar mesons $a_0$, $K^{\ast}_0$ and $f_0$ within the QCD sum rules. The QCD
sum rules are improved by a consistent treatment of the sizable $s$-quark mass
effects within the framework of the background field approach. Adopting the
valence quark component $(\bar{q}_1 q_2)$ as the dominant structure of the
scalar mesons, our estimation for their masses are close to the measured
$a_0(1450)$, $K^{\ast}_0(1430)$ and $f_0(1710)$. From the sum rules, we obtain
the first two non-zero moments of the twist-3 LCDAs $\phi^{s,\sigma}_{a_0}$:
$\langle \xi_{s,a_0}^{2(4)} \rangle=0.369 \;(0.245)$ and $\langle
\xi_{\sigma,a_0}^{2(4)} \rangle=0.203 \;(0.093)$; those of the twist-3 LCDAs
$\phi_{K^*_0}^{s,\sigma}$: $\langle \xi_{s,K^{\ast}_0}^{1(2)} \rangle
=0.004\;(0.355)$ and $\langle \xi_{\sigma,K^{\ast}_0}^{1(2)} \rangle
=0.018\;(0.207)$; and those of the twist-3 LCDAs $\phi_{f_0}^{s,\sigma}$:
$\langle \xi_{s,f_0}^{2(4)} \rangle=0.335 \;(0.212)$ and $\langle
\xi_{\sigma,f_0}^{2(4)} \rangle=0.196 \; (0.088)$, respectively. As an
application of those twist-3 LCDAs, we study the $B \to S$ transition form
factors by introducing proper chiral currents into the correlator, which is
constructed such that the twist-3 LCDAs give dominant contribution and the
twist-2 LCDAs make negligible contribution. Our results of the $B \to S$
transition form factors at the large recoil region $q^2 \simeq 0$ are
consistent with those obtained in the literature, which inversely shows the
present twist-3 LCDAs are acceptable.


title: On retracts, absolute retracts, and folds in cographs

abstract:
  Let G and H be two cographs. We show that the problem to determine whether H
is a retract of G is NP-complete. We show that this problem is fixed-parameter
tractable when parameterized by the size of H. When restricted to the class of
threshold graphs or to the class of trivially perfect graphs, the problem
becomes tractable in polynomial time. The problem is also soluble when one
cograph is given as an induced subgraph of the other. We characterize absolute
retracts of cographs.


title:
Extensions of solvable potentials with finitely many discrete
  eigenstates

abstract:
  We address the problem of rational extensions of six examples of
shape-invariant potentials having finitely many discrete eigenstates. The
overshoot eigenfunctions are proposed as candidates unique in this group for
the virtual state wavefunctions, which are an essential ingredient for
multi-indexed and iso-spectral extensions of these potentials. They have
exactly the same form as the eigenfunctions but their degrees are much higher
than n_{max} so that their energies are lower than the groundstate energy.


title: Evolution of molecular phenotypes under stabilizing selection

abstract:
  Molecular phenotypes are important links between genomic information and
organismic functions, fitness, and evolution. Complex phenotypes, which are
also called quantitative traits, often depend on multiple genomic loci. Their
evolution builds on genome evolution in a complicated way, which involves
selection, genetic drift, mutations and recombination. Here we develop a
coarse-grained evolutionary statistics for phenotypes, which decouples from
details of the underlying genotypes. We derive approximate evolution equations
for the distribution of phenotype values within and across populations. This
dynamics covers evolutionary processes at high and low recombination rates,
that is, it applies to sexual and asexual populations. In a fitness landscape
with a single optimal phenotype value, the phenotypic diversity within
populations and the divergence between populations reach evolutionary
equilibria, which describe stabilizing selection. We compute the equilibrium
distributions of both quantities analytically and we show that the ratio of
mean divergence and diversity depends on the strength of selection in a
universal way: it is largely independent of the phenotype's genomic encoding
and of the recombination rate. This establishes a new method for the inference
of selection on molecular phenotypes beyond the genome level. We discuss the
implications of our findings for the predictability of evolutionary processes.


title:
Construction of scrambled polynomial lattice rules over $\mathbb{F}_2$
  with small mean square weighted $\mathcal{L}_2$ discrepancy

abstract:
  The $\mathcal{L}_2$ discrepancy is one of several well-known quantitative
measures for the equidistribution properties of point sets in the
high-dimensional unit cube. The concept of weights was introduced by Sloan and
Wo\'{z}niakowski to take into account the relative importance of the
discrepancy of lower dimensional projections. As known under the name of
quasi-Monte Carlo methods, point sets with small weighted $\mathcal{L}_2$
discrepancy are useful in numerical integration. This study investigates the
component-by-component construction of polynomial lattice rules over the finite
field $\mathbb{F}_2$ whose scrambled point sets have small mean square weighted
$\mathcal{L}_2$ discrepancy. An upper bound on this discrepancy is proved,
which converges at almost the best possible rate of $N^{-2+\delta}$ for all
$\delta>0$, where $N$ denotes the number of points. Numerical experiments
confirm that the performance of our constructed polynomial lattice point sets
is comparable or even superior to that of Sobol' sequences.


title:
Mutation graphs of maximal rigid modules over finite dimensional
  preprojective algebras

abstract:
  Let $Q$ be a finite quiver of Dynkin type and $\Lambda=\Lambda_Q$ be the
preprojective algebra of $Q$ over an algebraically closed field $k$. Let
$\mathcal {T}_\Lambda$ be the mutation graph of maximal rigid $\Lambda$
modules. Geiss, Leclerc and Schr$\ddot{\rm o}$er conjectured that $\mathcal
{T}_\Lambda$ is connected, see [C.Geiss, B.Leclerc, J.Schr\"{o}er, Rigid
modules over preprojective algebras, Invent.Math., 165(2006), 589-632]. In this
paper, we prove that this conjecture is true when $\Lambda$ is of
representation finite type or tame type. Moreover, we also prove that $\mathcal
{T}_\Lambda$ is isomorphic to the tilting graph of ${\rm End}_\Lambda T$ for
each maximal rigid $\Lambda$-module $T$ if $\Lambda$ is representation-finite.


title: Coloring Planar Graphs via Colored Paths in the Associahedra

abstract:
  Hassler Whitney's theorem of 1931 reduces the task of finding proper, vertex
4-colorings of triangulations of the 2-sphere to finding such colorings for the
class \(\mathfrak H\) of triangulations of the 2-sphere that have a Hamiltonian
circuit. This has been used by Whitney and others from 1936 to the present to
find equivalent reformulations of the 4 Color Theorem (4CT). Recently there has
been activity to try to use some of these reformuations to find a shorter proof
of the 4CT. Every triangulation in \(\mathfrak H\) has a dual graph that is a
union of two binary trees with the same number of leaves. Elements of a group
known as Thompson's group \(F\) are equivalence classes of pairs of binary
trees with the same number of leaves. This paper explores this resemblance and
finds that some recent reformulations of the 4CT are essentially attempting to
color elements of \(\mathfrak H\) using expressions of elements of \(F\) as
words in a certain generating set for \(F\). From this, we derive information
about not just the colorability of certain elements of \(\mathfrak H\), but
also about all possible ways to color these elements. Because of this we raise
(and answer some) questions about enumeration. We also bring in an extension
\(E\) of the group \(F\) and ask whether certain elements ``parametrize'' the
set of all colorings of the elements of \(\mathfrak H\) that use all four
colors.


title: Four-point distortion theorem for complex polynomials

abstract:
  We prove a theorem on distortion of cross ratio of four points under the
mapping effected by a complex polynomial with restricted critical values. Its
corollaries include inequalities involving the absolute value and certain
coefficients of a polynomial. In particular, an exact lower bound is
established for maximal moduli of critical values of polynomials $P$ of degree
$n$ normalized by $P(0)=0$, $P'(0)\ne0$.


title: A categorification of U_T sl(1,1) and its tensor product representations

abstract:
  We define the Hopf superalgebra U_T sl(1,1), which is a variant of the
quantum supergroup U_q sl(1,1), and its tensor product representations
V_1^{\otimes n} for n>0. We construct families of DG algebras A, B and R_n, and
consider the DG categories DGP(A), DGP(B) and DGP(R_n), which are full DG
subcategories of the categories of DG A-, B- and R_n-modules generated by
certain distinguished projective modules. Their 0th homology categories HP(A),
HP(B), and HP(R_n) are triangulated and give algebraic formulations of the
contact categories of an annulus, a twice punctured disk, and an n times
punctured disk. We categorify the multiplication and comultiplication on U_T
sl(1,1) to a bifunctor HP(A) \times HP(A) --> HP(A) and a functor HP(A) -->
HP(B), respectively. The U_T sl(1,1)-action on V_1^{\otimes n} is lifted to a
bifunctor HP(A) \times HP(R_n) --> HP(R_n).


title:
Tres lecciones en combinatoria algebraica. I. Matrices totalmente no
  negativas y funciones sim\'etricas

abstract:
  En esta serie de tres articulos, damos una exposicion de varios resultados y
problemas abiertos en tres areas de la combinatoria algebraica y geometrica:
las matrices totalmente no negativas, las representaciones del grupo simetrico,
y los arreglos de hiperplanos. Esta primera parte presenta una introduccion a
las matrices totalmente no negativas, y su relacion con las funciones
simetricas.
  In this series of three articles, we give an exposition of various results
and open problems in three areas of algebraic and geometric combinatorics:
totally non-negative matrices, representations of the symmetric group, and
hyperplane arrangements. This first part presents an introduction to totally
non-negative matrices and their relationship with symmetric functions.


title:
Tres lecciones en combinatoria algebraica. II. Las funciones
  sim\'etricas y la teor\'{\i}a de representaciones

abstract:
  En esta serie de tres articulos, damos una exposicion de varios resultados y
problemas abiertos en tres areas de la combinatoria algebraica y geometrica:
las matrices totalmente no negativas, las representaciones del grupo simetrico,
y los arreglos de hiperplanos. Esta segunda parte trata la coneccion entre las
funciones simetricas y la teoria de representaciones.
  In this series of three articles, we give an exposition of various results
and open problems in three areas of algebraic and geometric combinatorics:
totally non-negative matrices, representations of the symmetric group, and
hyperplane arrangements. This second part treats the connection between
symmetric functions and representation theory.


title: Tres lecciones en combinatoria algebraica. III. Arreglos de hiperplanos

abstract:
  In this series of three articles, we give an exposition of various results
and open problems in three areas of algebraic and geometric combinatorics:
totally non-negative matrices, representations of the symmetric group, and
hyperplane arrangements. This first part is an introduction to hyperplane
arrangements from a combinatorial point of view. ----- En esta serie de tres
articulos, damos una exposicion de varios resultados y problemas abiertos en
tres areas de la combinatoria algebraica y geometrica: las matrices totalmente
no negativas, las representaciones del grupo simetrico, y los arreglos de
hiperplanos. Esta tercera parte presenta una introduccion a los arreglos de
hiperplanos desde un punto de vista combinatorio.


title:
Light Axigluon Contributions to b-bbar and c-cbar Asymmetry and
  Constraints on Flavor Changing Axigluon Currents

abstract:
  The light axigluon model of Tavares and Schmaltz is a viable candidate to
explain the Tevatron t-tbar forward-backward asymmetry. In this paper we
present the forward-backward asymmetries for b-bbar and c-cbar systems
predicted by the light axigluon. Furthermore, we modify this model to include
flavor changing couplings of axigluons with the SM quarks. We constrain these
couplings from the available neutral meson mixing data, and investigate their
effects on the rare decay B^0_s -> mu^+ mu^-, CP violating D -> h^+ h^- and
isospin violating B -> K^(*) mu^+ mu^- decays. We show that a light axigluon
can contribute to the observed CP violation in D -> h^+ h^- decays.


title: Generic Regular Decompositions for Parametric Polynomial Systems

abstract:
  This paper presents a generalization of our earlier work in [19]. In this
paper, the two concepts, generic regular decomposition (GRD) and
regular-decomposition-unstable (RDU) variety introduced in [19] for generic
zero-dimensional systems, are extended to the case where the parametric systems
are not necessarily zero-dimensional. An algorithm is provided to compute GRDs
and the associated RDU varieties of parametric systems simultaneously on the
basis of the algorithm for generic zero-dimensional systems proposed in [19].
Then the solutions of any parametric system can be represented by the solutions
of finitely many regular systems and the decomposition is stable at any
parameter value in the complement of the associated RDU variety of the
parameter space. The related definitions and the results presented in [19] are
also generalized and a further discussion on RDU varieties is given from an
experimental point of view. The new algorithm has been implemented on the basis
of DISCOVERER with Maple 16 and experimented with a number of benchmarks from
the literature.


title: Anisotropic Zeeman splitting in p-type GaAs quantum point contacts

abstract:
  Low-temperature electrical conductance spectroscopy measurements of quantum
point contacts implemented in p-type GaAs/AlGaAs heterostructures are used to
study the Zeeman splitting of 1D subbands for both in-plane and out-of-plane
magnetic field orientations. The resulting in-plane g-factors agree
qualitatively with those of previous experiments on quantum wires while the
quantitative differences can be understood in terms of the enhanced quasi-1D
confinement anisotropy. The influence of confinement potential on the
anisotropy is discussed and an estimate for the out-of-plane g-factor is
obtained which, in contrast to previous experiments, is closer to the
theoretical prediction.


title: On paired root systems of Coxeter groups

abstract:
  This paper examines a systematic method to construct a pair of
(inter-related) root systems for arbitrary Coxeter groups from a class of
non-standard geometric representations. This method can be employed to
construct generalizations of root systems for a large family of groups
generated only by involutions. We then give a characterization of Coxeter
groups, among these groups, in terms of such paired root systems. Furthermore,
we use this method to construct and study the paired root systems for
reflection subgroups of Coxeter groups.


title: The planetary nebula Abell 48 and its [WN] nucleus

abstract:
  We have conducted a detailed multi-wavelength study of the peculiar nebula
Abell 48 and its central star. We classify the nucleus as a helium-rich,
hydrogen-deficient star of type [WN4-5]. The evidence for either a massive WN
or a low-mass [WN] interpretation is critically examined, and we firmly
conclude that Abell 48 is a planetary nebula (PN) around an evolved low-mass
star, rather than a Population I ejecta nebula. Importantly, the surrounding
nebula has a morphology typical of PNe, and is not enriched in nitrogen, and
thus not the `peeled atmosphere' of a massive star. We estimate a distance of
1.6 kpc and a reddening, E(B-V) = 1.90 mag, the latter value clearly showing
the nebula lies on the near side of the Galactic bar, and cannot be a massive
WN star. The ionized mass (~0.3 M_Sun) and electron density (700 cm^-3) are
typical of middle-aged PNe. The observed stellar spectrum was compared to a
grid of models from the Potsdam Wolf-Rayet (PoWR) grid. The best fit
temperature is 71 kK, and the atmospheric composition is dominated by helium
with an upper limit on the hydrogen abundance of 10 per cent. Our results are
in very good agreement with the recent study of Todt et al., who determined a
hydrogen fraction of 10 per cent and an unusually large nitrogen fraction of ~5
per cent. This fraction is higher than any other low-mass H-deficient star, and
is not readily explained by current post-AGB models. We give a discussion of
the implications of this discovery for the late-stage evolution of
intermediate-mass stars. There is now tentative evidence for two distinct
helium-dominated post-AGB lineages, separate to the helium and carbon dominated
surface compositions produced by a late thermal pulse. Further theoretical work
is needed to explain these recent discoveries.


title: Origins of conductance anomalies in a p-type GaAs quantum point contact

abstract:
  Low temperature transport measurements on a p-GaAs quantum point contact are
presented which reveal the presence of a conductance anomaly that is markedly
different from the conventional `0.7 anomaly'. A lateral shift by asymmetric
gating of the conducting channel is utilized to identify and separate different
conductance anomalies of local and generic origins experimentally. While the
more generic 0.7 anomaly is not directly affected by changing the gate
configuration, a model is proposed which attributes the additional conductance
features to a gate-dependent coupling of the propagating states to localized
states emerging due to a nearby potential imperfection. Finite bias
conductivity measurements reveal the interplay between the two anomalies
consistently with a two-impurity Kondo model.


title: Parameterizable Byzantine Broadcast in Loosely Connected Networks

abstract:
  We consider the problem of reliably broadcasting information in a multihop
asynchronous network, despite the presence of Byzantine failures: some nodes
are malicious and behave arbitrarly. We focus on non-cryptographic solutions.
Most existing approaches give conditions for perfect reliable broadcast (all
correct nodes deliver the good information), but require a highly connected
network. A probabilistic approach was recently proposed for loosely connected
networks: the Byzantine failures are randomly distributed, and the correct
nodes deliver the good information with high probability. A first solution
require the nodes to initially know their position on the network, which may be
difficult or impossible in self-organizing or dynamic networks. A second
solution relaxed this hypothesis but has much weaker Byzantine tolerance
guarantees. In this paper, we propose a parameterizable broadcast protocol that
does not require nodes to have any knowledge about the network. We give a
deterministic technique to compute a set of nodes that always deliver authentic
information, for a given set of Byzantine failures. Then, we use this technique
to experimentally evaluate our protocol, and show that it significantely
outperforms previous solutions with the same hypotheses. Important disclaimer:
these results have NOT yet been published in an international conference or
journal. This is just a technical report presenting intermediary and incomplete
results. A generalized version of these results may be under submission.


title:
Performance Comparison of Proposed Lifetime Maximizing Trees for Data
  Aggregation in Wireless Sensor Networks

abstract:
  In this paper a packet level simulator is used to explore the performance of
the proposed DLMT and CLMT algorithms under various traffic conditions.
Performance of the proposed algorithms is compared with already existing E-Span
tree structure. These proposed algorithms tend to extend the node lifetime in
order to increase the amount of information gathered by the tree root.
Decentralized lifetime maximizing tree (DLMT) features in nodes with higher
energy to be chosen as data aggregating parents while Centralized Lifetime
Maximizing Tree (CLMT) features with the identification of the bottleneck node
to collect data in a central manner among given set of nodes. By choosing
Forwarded Diffusion as our underlying routing platform the simulations are
carried on J-Sim. Our simulation results have shown that the functional
lifetime of event sources can be enhanced by a maximum of 147% when data is
aggregated via DLMT and by 139% when data is aggregated via CLMT. Our proposed
DLMT algorithm has shown maximum of 13% additional lifetime saving without
increasing the delay. Packet delivery ratio has also shown a remarkable
increase when the tree depth is considered in these proposed tree structures.
Furthermore, the delay is also reduced by using DLMT & CLMT in comparison with
E-Span.


title: Action of dihedral groups

abstract:
  Let $K$ be any field and $G$ be a finite group. Let $G$ act on the rational
function field $K(x_g: \ g \in G)$ by $K$-automorphisms defined by $g \cdot
x_h=x_{gh}$ for any $g, \ h \in G$. Denote by $K(G)$ the fixed field $K(x_g: \
g \in G)^G$. Noether's problem asks whether $K(G)$ is rational (=purely
transcendental) over $K$. We will give a brief survey of Noether's problem for
abelian groups and dihedral groups, and will show that $\Bbb Q(D_n)$ is
rational over $\Bbb Q$ for $n \le 10$.


title:
Stable Routing for achieving Quality of Service in wireless Sensor
  Networks

abstract:
  Networking in Wireless Sensor networks is a challenging task due to the lack
of resources in the network as well as the frequent changes in network
topology. Although lots of research has been done on supporting QoS in the
Internet and other networks, but they are not suitable for wireless sensor
networks and still QoS support for such networks remains an open problem. In
this paper, a new scheme has been proposed for achieving QoS in terms of packet
delivery, multiple connections, better power management and stable routes in
case of failure. It offers quick adaptation to distributed processing, dynamic
linking, low processing overhead and loop freedom at all times. The proposed
scheme has been incorporated using QDPRA protocol and by extensive simulation
the performance has been studied, and it is clearly shown that the proposed
scheme performs very well for different network scenarios.


title:
Wiener-Hopf matrix factorization using ordinary differential equations
  in the commutative case

abstract:
  A matrix factorization problem is considered. The matrix to be factorized is
algebraic, has dimension 2 X 2 and belongs to Moiseev's class. A new method of
factorization is proposed. First, the matrix factorization problem is reduced
to a Riemann-Hilbert problem using the Hurd's method. Secondly, the
Riemann-Hilbert problem is embedded into a family of Riemann-Hilbert problems
indexed by a variable b taking values on a half-line. A linear ordinary
differential equation (ODE1) with respect to b is derived. The coefficient of
this equation remains unknown at this step. Finally, the coefficient of the
ODE1 is computed. For this, it is proven that it obeys a non-linear ordinary
differential equation (ODE2) on a half-line. Thus, the numerical procedure of
matrix factorization becomes reduced to two runs of solving of ordinary
differential equations on a half-line: first ODE2 for the coefficient of ODE1,
and then ODE1 for the unknown function. The efficiency of the new method is
demonstrated on some examples.


title:
Far-Infrared and submillimeter properties of SDSS galaxies in the
  Herschel ATLAS science demonstration phase field

abstract:
  Using the Herschel ATLAS science demonstration phase data crossidentified
with SDSS DR7 spectra, we select 297 galaxies with F250{\mu}m > 5{\sigma}. The
sample galaxies are classified into five morphological types, and more than 40%
of the galaxies are peculiar/compact galaxies. The peculiar galaxies show
higher far-infrared/submillimeter luminosity-to-mass ratios than the other
types. We perform and analyze the correlations of far-infrared/submillimeter
and H{\alpha} luminosities for different morphological types and different
spectral types. The Spearman rank coefficient decreases and the scatter
increases with the wavelength increasing from 100 {\mu}m to 500 {\mu}m. We
conclude that a single Herschel SPIRE band is not good for tracing star
formation activities in galaxies. AGNs contribute less to the
far-infrared/submillimeter luminosities and do not show a difference from
star-forming galaxies. However, the earlier type galaxies present significant
deviations from the best fit of star-forming galaxies.


title: Pseudo-effective classes and pushforwards

abstract:
  Given a morphism between complex projective varieties, we make several
conjectures on the relations between the set of pseudo-effective (co)homology
classes which are annihilated by pushforward and the set of classes of
varieties contracted by the morphism. We prove these conjectures for classes of
curves or divisors. We also prove that one of these conjectures implies
Grothendieck's generalized Hodge conjecture for varieties with Hodge coniveau
at least 1.


title: HI shells in the Leiden/Argentina/Bonn HI survey

abstract:
  We analyse the all-sky Leiden/Argentina/Bonn HI survey, where we identify
shells belonging to the Milky Way. We used an identification method based on
the search of continuous regions of a low brightness temperature that are
compatible with given properties of HI shells. We found 333 shells in the whole
Galaxy. The size distribution of shells in the outer Galaxy is fitted by a
power law with the coefficient of 2.6 corresponding to the index 1.8 in the
distribution of energy sources. Their surface density decreases exponentially
with a scale length of 2.8 kpc. The surface density of shells with radii >= 100
pc in the solar neighbourhood is around 4 per kpc^2 and the 2D porosity is
approximately 0.7.


title: Studies on X(4260) and X(4660) particles

abstract:
  Studies on the X(4260) and X(4660) resonant states in an effective lagrangian
approach are reviewed. Using a Breit--Wigner propagator to describe their
propagation, we find that the X(4260) has a sizable coupling to the
$\omega\chi_{c0}$ channel, while other couplings are found to be negligible.
Besides, it couples much stronger to $\sigma$ than to $f_0(980)$: $|g_{X\Psi
\sigma}^2/g^2_{X\Psi f_0(980)}|\sim O(10) \ .$ As an approximate result for
X(4660), we obtain that the ratio of
$\frac{Br(X\rightarrow\Lambda_c^+\Lambda_c^-)}{Br(X\rightarrow\Psi(2s)\pi^+\pi^-)}\simeq
20$. Finally, taking X(3872) as an example, we also point out a possible way to
extend the previous method to a more general one in the effective lagrangian
approach.


title:
Remark on nondegeneracy of simple abelian varieties with many
  endomorphisms

abstract:
  We investigate a relationship between nondegeneracy of a simple abelian
variety $A$ over an algebraic closure of $\mb{Q}$ and of its reduction $A_0$.
We prove that under some assumptions, nondegeneracy of $A$ implies
nondegeneracy of $A_0$.


title: Spatially partitioned embedded Runge-Kutta methods

abstract:
  We study spatially partitioned embedded Runge--Kutta (SPERK) schemes for
partial differential equations (PDEs), in which each of the component schemes
is applied over a different part of the spatial domain. Such methods may be
convenient for problems in which the smoothness of the solution or the
magnitudes of the PDE coefficients vary strongly in space. We focus on embedded
partitioned methods as they offer greater efficiency and avoid the order
reduction that may occur in non-embedded schemes. We demonstrate that the lack
of conservation in partitioned schemes can lead to non-physical effects and
propose conservative additive schemes based on partitioning the fluxes rather
than the ordinary differential equations. A variety of SPERK schemes are
presented, including an embedded pair suitable for the time evolution of
fifth-order weighted non-oscillatory (WENO) spatial discretizations. Numerical
experiments are provided to support the theory.


title:
Electric-field control of domain wall nucleation and pinning in a
  metallic ferromagnet

abstract:
  The electric (E) field control of magnetic properties opens the prospects of
an alternative to magnetic field or electric current activation to control
magnetization. Multilayers with perpendicular magnetic anisotropy (PMA) have
proven to be particularly sensitive to the influence of an E-field due to the
interfacial origin of their anisotropy. In these systems, E-field effects have
been recently applied to assist magnetization switching and control domain wall
(DW) velocity. Here we report on two new applications of the E-field in a
similar material : controlling DW nucleation and stopping DW propagation at the
edge of the electrode.


title: Simultaneous Domination in Graphs

abstract:
  Let $F_1, F_2, ..., F_k$ be graphs with the same vertex set $V$. A subset $S
\subseteq V$ is a simultaneous dominating set if for every $i$, $1 \le i \le
k$, every vertex of $F_i$ not in $S$ is adjacent to a vertex in $S$ in $F_i$;
that is, the set $S$ is simultaneously a dominating set in each graph $F_i$.
The cardinality of a smallest such set is the simultaneous domination number.
We present general upper bounds on the simultaneous domination number. We
investigate bounds in special cases, including the cases when the factors,
$F_i$, are $r$-regular or the disjoint union of copies of $K_r$. Further we
study the case when each factor is a cycle.


title:
The deconfinement phase transition in the Hamiltonian approach to
  Yang-Mills theory in Coulomb gauge

abstract:
  The deconfinement phase transition of SU(2) Yang-Mills theory is investigated
in the Hamiltonian approach in Coulomb gauge assuming a quasi-particle picture
for the grand canonical gluon ensemble. The thermal equilibrium state is found
by minimizing the free energy with respect to the quasi-gluon energy. At the
deconfinement phase transition the gluon energy, being infrared divergent in
the confined phase, becomes infrared finite in the deconfined phase, while the
ghost form factor remains infrared divergent in the deconfined phase but its
infrared exponent is approximately halved. Using the lattice results for the
gluon propagator to fix the scale the deconfinement transition temperature is
obtained in the range of 275 to 290 MeV.


title: Approximating Bin Packing within O(log OPT * log log OPT) bins

abstract:
  For bin packing, the input consists of n items with sizes s_1,...,s_n in
[0,1] which have to be assigned to a minimum number of bins of size 1. The
seminal Karmarkar-Karp algorithm from '82 produces a solution with at most OPT
+ O(log^2 OPT) bins.
  We provide the first improvement in now 3 decades and show that one can find
a solution of cost OPT + O(log OPT * log log OPT) in polynomial time. This is
achieved by rounding a fractional solution to the Gilmore-Gomory LP relaxation
using the Entropy Method from discrepancy theory. The result is constructive
via algorithms of Bansal and Lovett-Meka.


title:
The Symmetries of the Three Heavy Quark Bound State and the Singlet
  Static Energy

abstract:
  Potential non-relativistic QCD provides a convenient framework to study the
three heavy-quark system. We have studied its symmetries under exchange of the
heavy quarks and determined the leading ultrasoft contributions to the singlet
static potential and to the singlet static energy. Specializing to an
equilateral geometry, we have solved the renormalization group equations in
order to resum the leading ultrasoft logarithms for the singlet static
potential, which is thus known at NNLL accuracy.


title: Remarks on the stochastic transport equation with H\"{o}lder drift

abstract:
  We consider a stochastic linear transport equation with a globally H\"{o}lder
continuous and bounded vector field. Opposite to what happens in the
deterministic case where shocks may appear, we show that the unique solution
starting with a C^{1}-initial condition remains of class $C^{1}$ in space. We
also improve some results of Flandoli-Gubinelli-Priola (2009) about
well-posedness. Moreover, we prove a stability property for the solution with
respect to the initial datum.


title: Confinement and Z_3 symmetry in three-flavor QCD

abstract:
  We investigate the confinement mechanism in three-flavor QCD with imaginary
isospin chemical potentials $(\mu_u,\mu_d,\mu_s)=(i\theta T,-i\theta T,0)$,
using the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model, where $T$ is
temperature. As for three degenerate flavors, the system has $\mathbb{Z}_{3}$
symmetry at $\theta=2\pi/3$ and hence the Polyakov loop $\Phi$ vanishes there
for small $T$. As for 2+1 flavors, the symmetry is not preserved for any
$\theta$, but $\Phi$ becomes zero at $\theta=\theta_{\rm conf} < 2\pi/3$ for
small $T$. The confinement phase defined by $\Phi=0$ is realized, even if the
system does not have $\mathbb{Z}_{3}$ symmetry exactly. In the $\theta$-$T$
plane, there is a critical endpoint of deconfinement transition. The
deconfinement crossover at zero chemical potential is a remnant of the
first-order deconfinement transition at $\theta=\theta_{\rm conf}$. The
relation between the non-diagonal element $\chi_{us}$ of quark number
susceptibilities and the deconfinement transition is studied. The present
results can be checked by lattice QCD simulations directly, since the
simulations are free from the sign problem for any $\theta$.


title: The radiative decays of $0^{++}$ and $1^{+-}$ heavy mesons

abstract:
  The radiative decay is believed to be an ideal lab to study hadronic
structure of newly observed resonances because the reactions are governed by
only the electromagnetic interaction (tree level). However, to obtain correct
theoretical values, one has to properly deal with the non-perturbative QCD
effects in the wavefunction and hadronization. In this work we derive the
formulas for the radiative decays of $0^{++}$ and $1^{-+}$ heavy mesons in the
light front quark model (LFQM). Because $\mathcal{B}(\chi_{c0}\rightarrow
J/\psi\gamma)$ is well measured, the theoretical evaluation of the transition
rate can be used to test our approach. Within this theoretical framework, the
width of $\chi_{b0}\rightarrow \Upsilon(1S)\gamma$ is evaluated. The formulas
can be applied to identify the inner structures of new resonances, for example
the isospin of $h_{c(b)}$ and the structure of $D_s(2317)$, via processes
$h_c\rightarrow \eta_c\gamma$, $h_b\rightarrow \eta_b\gamma$ and
$D_s(2317)\rightarrow D_s^*+\gamma$.