title: Legendre-Gauss-Lobatto grids and associated nested dyadic grids

abstract:
  Legendre-Gauss-Lobatto (LGL) grids play a pivotal role in nodal spectral
methods for the numerical solution of partial differential equations. They not
only provide efficient high-order quadrature rules, but give also rise to norm
equivalences that could eventually lead to efficient preconditioning techniques
in high-order methods. Unfortunately, a serious obstruction to fully exploiting
the potential of such concepts is the fact that LGL grids of different degree
are not nested. This affects, on the one hand, the choice and analysis of
suitable auxiliary spaces, when applying the auxiliary space method as a
principal preconditioning paradigm, and, on the other hand, the efficient
solution of the auxiliary problems. As a central remedy, we consider certain
nested hierarchies of dyadic grids of locally comparable mesh size, that are in
a certain sense properly associated with the LGL grids. Their actual
suitability requires a subtle analysis of such grids which, in turn, relies on
a number of refined properties of LGL grids. The central objective of this
paper is to derive just these properties. This requires first revisiting
properties of close relatives to LGL grids which are subsequently used to
develop a refined analysis of LGL grids. These results allow us then to derive
the relevant properties of the associated dyadic grids.


title: Dark Sectors and New, Light, Weakly-Coupled Particles

abstract:
  Dark sectors, consisting of new, light, weakly-coupled particles that do not
interact with the known strong, weak, or electromagnetic forces, are a
particularly compelling possibility for new physics. Nature may contain
numerous dark sectors, each with their own beautiful structure, distinct
particles, and forces. This review summarizes the physics motivation for dark
sectors and the exciting opportunities for experimental exploration. It is the
summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled
Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions,
which solve the strong CP problem and are an excellent dark matter candidate,
and their generalization to axion-like particles. We also review dark photons
and other dark-sector particles, including sub-GeV dark matter, which are
theoretically natural, provide for dark matter candidates or new dark matter
interactions, and could resolve outstanding puzzles in particle and
astro-particle physics. In many cases, the exploration of dark sectors can
proceed with existing facilities and comparatively modest experiments. A rich,
diverse, and low-cost experimental program has been identified that has the
potential for one or more game-changing discoveries. These physics
opportunities should be vigorously pursued in the US and elsewhere.


title:
Local derivations on Rings containing a von Neumann algebra and a
  question of Kadison

abstract:
  We prove that if M is a von Neumann algebra whose abelian summand is
discrete, then every local derivation on the algebra of all measurable
operators affilated with M is a derivation. This answers a question of Richard
Kadison.


title: Multiwavelength Observations of Swift J1753.5-0127

abstract:
  We present contemporaneous X-ray, ultraviolet, optical and near-infrared
observations of the black hole binary system, Swift J1753.5-0127, acquired in
2012 October. The UV observations, obtained with the Cosmic Origins
Spectrograph on the Hubble Space Telescope, are the first UV spectra of this
system. The dereddened UV spectrum is characterized by a smooth, blue continuum
and broad emission lines of CIV and HeII. The system was stable in the UV to
<10% during our observations. We estimated the interstellar reddening by
fitting the 2175 A absorption feature and fit the interstellar absorption
profile of Ly$\alpha$ to directly measure the neutral hydrogen column density
along the line of sight. By comparing the UV continuum flux to steady-state
thin accretion disk models, we determined upper limits on the distance to the
system as a function of black hole mass. The continuum is well fit with disk
models dominated by viscous heating rather than irradiation. The broadband
spectral energy distribution shows the system has declined at all wavelengths
since previous broadband observations in 2005 and 2007. If we assume that the
UV emission is dominated by the accretion disk the inner radius of the disk
must be truncated at radii above the ISCO to be consistent with the X-ray flux,
requiring significant mass loss from outflows and/or energy loss via advection
into the black hole to maintain energy balance.


title: Quantum field theory based on birefringent modified Maxwell theory

abstract:
  In the current paper the properties of a birefringent Lorentz-violating
extension of quantum electrodynamics is considered. The theory results from
coupling modified Maxwell theory, which is a CPT-even Lorentz-violating
extension of the photon sector, to a Dirac theory of standard spin-1/2
particles. It is then restricted to a special birefringent case with one
nonzero Lorentz-violating coefficient. The modified dispersion laws of
electromagnetic waves are obtained plus their phase and group velocities are
considered. After deriving the photon propagator and the polarization vectors
for a special momentum configuration we prove both unitarity at tree-level and
microcausality for the quantum field theory based on this Lorentz-violating
modification. These analytical proofs are done for a spatial momentum with two
vanishing components and the proof of unitarity is supported by numerical
investigations in case all components are nonvanishing. The upshot is that the
theory is well-behaved within the framework of our assumptions where there is a
possible issue for negative Lorentz-violating coefficients. The paper shall
provide a basis for the future analysis of alternative birefringent quantum
field theories.


title: One dimensional massless Dirac bands in semiconductor superlattices

abstract:
  Semiconductor superlattices may display dispersions that are degenerate
either at the zone center or zone boundary. We show that they are linear upon
the wave-vector in the vicinity of the crossing point. This establishes a
realisation of massless Dirac bands within semiconductor materials. We show
that the eigenstates and the corresponding Wannier functions of these
superlattices have peculiar symmetry properties. We discuss the stability of
the properties of such superlattices versus the electron in-plane motion. As a
distinct fingerprint, the inter-subband magneto-absorption spectrum for such
superlattices is discussed.


title:
Solution to sign problems in half-filled spin-polarized electronic
  systems

abstract:
  We solve the sign problem in a particle-hole symmetric spin-polarized fermion
model on bipartite lattices using the idea of fermion bags. The solution can be
extended to a class of models at half filling but without particle-hole
symmetry. Attractive Hubbard models with an odd number of fermion species can
also be solved. The new solutions should allow us to study quantum phase
transitions that have remained unexplored so far due to sign problems.


title: Parameterless Optimal Approximate Message Passing

abstract:
  Iterative thresholding algorithms are well-suited for high-dimensional
problems in sparse recovery and compressive sensing. The performance of this
class of algorithms depends heavily on the tuning of certain threshold
parameters. In particular, both the final reconstruction error and the
convergence rate of the algorithm crucially rely on how the threshold parameter
is set at each step of the algorithm. In this paper, we propose a
parameter-free approximate message passing (AMP) algorithm that sets the
threshold parameter at each iteration in a fully automatic way without either
having an information about the signal to be reconstructed or needing any
tuning from the user. We show that the proposed method attains both the minimum
reconstruction error and the highest convergence rate. Our method is based on
applying the Stein unbiased risk estimate (SURE) along with a modified gradient
descent to find the optimal threshold in each iteration. Motivated by the
connections between AMP and LASSO, it could be employed to find the solution of
the LASSO for the optimal regularization parameter. To the best of our
knowledge, this is the first work concerning parameter tuning that obtains the
fastest convergence rate with theoretical guarantees.


title: Trimodal steady water waves

abstract:
  We construct three-dimensional families of small-amplitude gravity-driven
rotational steady water waves on finite depth. The solutions contain
counter-currents and multiple crests in each minimal period. Each such wave
generically is a combination of three different Fourier modes, giving rise to a
rich and complex variety of wave patterns. The bifurcation argument is based on
a blow-up technique, taking advantage of three parameters associated with the
vorticity distribution, the strength of the background stream, and the period
of the wave.


title:
Coronal magnetic field strength from Type II radio emission:
  complementarity with Faraday rotation measurements

abstract:
  We analyzed the band splitting of a Type II radio burst observed on 1997 May
12 by ground- and space-based radio spectrometers. Type II radio emission is
the most evident signature of coronal shock waves and the observed band
splitting is generally interpreted as due to plasma emission from both upstream
and downstream shock regions. From the inferred compression ratio we estimated,
using the magnetohydrodynamic (MHD) Rankine-Hugoniot relations, the ambient
Alfven Mach number. By means of the electron density obtained by inverting
white-light polarized brightness (pB) coronagraph data and the shock speed
inferred from the Type II frequency drift, we finally derived a radial profile
for the magnetic field strength in the middle corona. The result was compared
with the field profile obtained in May 1997 (but above $\sim 5 R_{sun}$) with
Faraday rotation measurements of extragalactic radio sources occulted by the
corona. The power law of the form $B(r)$ = 3.76 $r^{-2.29}$ Gauss inferred in
that work nicely describes the combined set of data in a wide range of
heliocentric distances ($r$ $\sim$ 1.8 - 14 $R_{sun}$).


title:
On the Spectrum of weighted Laplacian operator and its application to
  uniqueness of K\"ahler Einstein metrics

abstract:
  The purpose of this paper is to provide a new proof of Bando-Mabuchi's
uniqueness theorem of K\"ahler Einstein metrics on Fano manifolds, based on
Chen's weak C^{1,1} geodesic without using any further regularities. Unlike the
smooth case, the lack of regularities on the geodesic forbids us to use
spectral formula of the weighed Laplacian operator directly. However, we can
use smooth geodesics to approximate the weak one, then prove that a sequence of
eigenfunctions will converge into the first eigenspace of the weighted
Laplacian operator.


title:
Dilute Magnetism and Spin-Orbital Percolation Effects in Rh-doped
  Sr2IrO4

abstract:
  We have used a combination of resonant magnetic x-ray scattering (RMXS) and
x-ray absorption spectroscopy (XAS) to investigate the properties of the doped
spin-orbital Mott insulator Sr2Ir(1-x)Rh(x)O4 (0.07 < x < 0.70). We show that
Sr2Ir(1-x)Rh(x)O4 represents a unique model system for the study of dilute
magnetism in the presence of strong spin-orbit coupling, and provide evidence
of a doping-induced change in magnetic structure and a suppression of magnetic
order at x_c ~ 0.17. We demonstrate that Rh-doping introduces Rh3+/Ir5+ ions
which effectively hole-dope this material. We propose that the magnetic phase
diagram for this material can be understood in terms of a novel spin-orbital
percolation picture.


title: Heavy Flavor & Dark Sector

abstract:
  We consider some contributions to rare processes in $B$ meson decays from a
Dark Sector containing 2 light unstable scalars, with large couplings to each
other and small mixings with Standard Model Higgs scalars. We show that
existing constraints allow for an exotic contribution to high multiplicity
final states with a branching fraction as large as $\mathcal{O}(10^{-4})$, and
that exotic particles could appear as narrow resonances or long lived particles
which are mainly found in high multiplicity final states from $B$ decays.


title:
A Technique for Write-endurance aware Management of Resistive RAM Last
  Level Caches

abstract:
  Due to increasing cache sizes and large leakage consumption of SRAM device,
conventional SRAM caches contribute significantly to the processor power
consumption. Recently researchers have used non-volatile memory devices to
design caches, since they provide high density, comparable read latency and low
leakage power dissipation. However, their high write latency may increase the
execution time and hence, leakage energy consumption. Also, since their write
endurance is small, a conventional energy saving technique may further
aggravate the problem of write-variations, thus reducing their lifetime. In
this paper, we present a cache energy saving technique for non-volatile caches,
which also attempts to improve their lifetime by making writes equally
distributed to the cache. Our technique uses dynamic cache reconfiguration to
adjust the cache size to meet program requirement and turns off the remaining
cache to save energy. Microarchitectural simulations performed using an x86-64
simulator, SPEC2006 benchmarks and a resistive-RAM LLC (last level cache) show
that over an 8MB baseline cache, our technique saves 17.55% memory subsystem
(last level cache + main memory) energy and improves the lifetime by 1.33X.
Over the same resistive-RAM baseline, an SRAM of similar area with no cache
reconfiguration leads to an energy loss of 186.13%.


title:
Optimization with Discrete Simultaneous Perturbation Stochastic
  Approximation Using Noisy Loss Function Measurements

abstract:
  Discrete stochastic optimization considers the problem of minimizing (or
maximizing) loss functions defined on discrete sets, where only noisy
measurements of the loss functions are available. The discrete stochastic
optimization problem is widely applicable in practice, and many algorithms have
been considered to solve this kind of optimization problem. Motivated by the
efficient algorithm of simultaneous perturbation stochastic approximation
(SPSA) for continuous stochastic optimization problems, we introduce the middle
point discrete simultaneous perturbation stochastic approximation (DSPSA)
algorithm for the stochastic optimization of a loss function defined on a
p-dimensional grid of points in Euclidean space. We show that the sequence
generated by DSPSA converges to the optimal point under some conditions.
Consistent with other stochastic approximation methods, DSPSA formally
accommodates noisy measurements of the loss function. We also show the rate of
convergence analysis of DSPSA by solving an upper bound of the mean squared
error of the generated sequence. In order to compare the performance of DSPSA
with the other algorithms such as the stochastic ruler algorithm (SR) and the
stochastic comparison algorithm (SC), we set up a bridge between DSPSA and the
other two algorithms by comparing the probability in a big-O sense of not
achieving the optimal solution. We show the theoretical and numerical
comparison results of DSPSA, SR, and SC. In addition, we consider an
application of DSPSA towards developing optimal public health strategies for
containing the spread of influenza given limited societal resources.


title: Szpiro's small points conjecture for cyclic covers

abstract:
  Let $X$ be a smooth, projective and geometrically connected curve of genus at
least two, defined over a number field. In 1984, Szpiro conjectured that $X$
has a "small point". In this paper we prove that if $X$ is a cyclic cover of
prime degree of the projective line, then $X$ has infinitely many "small
points". In particular, we establish the first cases of Szpiro's small points
conjecture, including the genus two case and the hyperelliptic case. The proofs
use Arakelov theory for arithmetic surfaces and the theory of logarithmic
forms.


title: Thread-Based Obfuscation through Control-Flow Mangling

abstract:
  The increasing use of cloud computing and remote execution have made program
security especially important. Code obfuscation has been proposed to make the
understanding of programs more complicated to attackers. In this paper, we
exploit multi-core processing to substantially increase the complexity of
programs, making reverse engineering more complicated. We propose a novel
method that automatically partitions any serial thread into an arbitrary number
of parallel threads, at the basic-block level. The method generates new
control-flow graphs, preserving the blocks' serial successor relations and
guaranteeing that one basic-block is active at a time using guards. The method
generates m^n different combinations for m threads and n basic-blocks,
significantly complicating the execution state. We provide a correctness proof
for the algorithm and implement the algorithm in the LLVM compilation
framework.


title:
Spatially Resolved Emission of a High Redshift DLA Galaxy with the
  Keck/OSIRIS IFU

abstract:
  We present the first Keck/OSIRIS infrared IFU observations of a high redshift
damped Lyman-alpha (DLA) galaxy detected in the line of sight to a background
quasar. By utilizing the Laser Guide Star Adaptive Optics (LGSAO) to reduce the
quasar PSF to FWHM~0.15 arcsec, we were able to search for and map the
foreground DLA emission free from the quasar contamination. We present maps of
the H-alpha and [OIII] $\lambda \lambda$ 5007, 4959 emission of DLA 2222-0946
at a redshift of z ~ 2.35. From the composite spectrum over the H-alpha
emission region we measure a star formation rate of 9.5 $\pm$ 1.0 M$_{\odot}$
year$^{-1}$ and a dynamical mass, M$_{dyn}$ = 6.1 x 10$^9$ M$_{\odot}$. The
average star formation rate surface density is < \Sigma_{SFR} > = 0.55
M$_{\odot}$ yr$^{-1}$ kpc$^{-2}$, with a central peak of 1.7 M$_{\odot}$
yr$^{-1}$ kpc$^{-2}$. Using the standard Kennicutt-Schmidt relation, this
corresponds to a gas mass surface density of $\Sigma_{gas}$ = 243 M$_{\odot}$
pc$^{-2}$. Integrating over the size of the galaxy we find a total gas mass of
M$_{gas}$ = 4.2 x 10$^9$ M$_{\odot}$. We estimate the gas fraction of DLA
2222-0946 to be $f_{gas}$ ~ 40%. We detect [NII]$\lambda$6583 emission at 2.5
sigma significance with a flux corresponding to a metallicity of 75% solar.
Comparing this metallicity with that derived from the low-ion absorption gas ~6
kpc away, ~30% solar, indicates possible evidence for a metallicity gradient or
enriched in/outflow of gas. Kinematically, both H-alpha and [OIII] emission
show relatively constant velocity fields over the central galactic region.
While we detect some red and blueshifted clumps of emission, they do not
correspond with rotational signatures that support an edge-on disk
interpretation.


title: On annular maps of the torus and sublinear diffusion

abstract:
  There is a classification by Misiurewicz and Ziemian of elements in
Homeo$_0(\mathbf{T}^2)$ by their rotation set $\rho$, according to wether
$\rho$ is a point, a segment or a set with nonempty interior. A recent
classification of nonwandering elements in Homeo$_0(\mathbf{T}^2)$ by Koropecki
and Tal has been given, according to the itrinsic underlying ambient where the
dynamics takes place: planar, annular and strictly toral maps. We study the
link between these two classifications, showing that, even abroad the
nonwandering setting, annular maps are characterized by rotation sets which are
\textit{rational segments}. Also, we obtain information on the
\textit{sublinear diffusion} of orbits in the -not very well understood- case
that $\rho$ has nonempty interior.


title:
Bayesian inferences of galaxy formation from the K-band luminosity and
  HI mass functions of galaxies: constraining star formation and feedback

abstract:
  We infer mechanisms of galaxy formation for a broad family of semi-analytic
models (SAMs) constrained by the K-band luminosity function and HI mass
function of local galaxies using tools of Bayesian analysis. Even with a broad
search in parameter space the whole model family fails to match to constraining
data. In the best fitting models, the star formation and feedback parameters in
low-mass haloes are tightly constrained by the two data sets, and the analysis
reveals several generic failures of models that similarly apply to other
existing SAMs. First, based on the assumption that baryon accretion follows the
dark matter accretion, large mass-loading factors are required for haloes with
circular velocities lower than 200 km/s, and most of the wind mass must be
expelled from the haloes. Second, assuming that the feedback is powered by
Type-II supernovae with a Chabrier IMF, the outflow requires more than 25% of
the available SN kinetic energy. Finally, the posterior predictive
distributions for the star formation history are dramatically inconsistent with
observations for masses similar to or smaller than the Milky-Way mass. The
inferences suggest that the current model family is still missing some key
physical processes that regulate the gas accretion and star formation in
galaxies with masses below that of the Milky Way.


title: JEWEL 2.0.0 - Directions for Use

abstract:
  In this publication the first official release of the JEWEL 2.0.0 code is
presented. JEWEL is a Monte Carlo event generator simulating QCD jet evolution
in heavy-ion collisions. It treats the interplay of QCD radiation and
re-scattering in a medium with fully microscopic dynamics in a consistent
perturbative framework with minimal assumptions. After a qualitative
introduction into the physics of JEWEL detailed information about the practical
aspects of using the code is given.


title:
Large spin splitting in the conduction band of transition metal
  dichalcogenide monolayers

abstract:
  We study the conduction band spin splitting that arises in transition metal
dichalcogenide (TMD) semiconductor monolayers such as MoS$_2$, MoSe$_2$, WS$_2$
and WSe$_2$ due to the combination of spin-orbit coupling and lack of inversion
symmetry. Two types of calculation are done. First, density functional theory
(DFT) calculations based on plane waves and pseudo potentials that yield large
splittings, between 3 and 30 meV. Second, we derive a tight-binding model, that
permits to address the atomic origin of the splitting. The basis set of the
model is provided by the maximally localized Wannier orbitals, obtained from
the DFT calculation, and formed by 11 atomic-like orbitals corresponding to
5$d$ and 3$p$ orbitals of the transition metal (W,Mo) and chalcogenide (S,Se)
atoms respectively. In the resulting Hamiltonian we can independently change
the atomic spin-orbit coupling constant of the two atomic species at the unit
cell, which permits to analyse their contribution to the spin splitting at the
high symmetry points. We find that ---in contrast to the valence band--- both
atoms give comparable contributions to the conduction band splittings. Given
that these materials are most often $n-$doped, our findings are important for
developments in TMD spintronics.


title:
Deciphering transcriptional dynamics in vivo by counting nascent RNA
  molecules

abstract:
  Transcription of genes is the focus of most forms of regulation of gene
expression. Even though careful biochemical experimentation has revealed the
molecular mechanisms of transcription initiation for a number of different
promoters in vitro, the dynamics of this process in cells is still poorly
understood. One approach has been to measure the transcriptional output
(fluorescently labeled messenger RNAs or proteins) from single cells in a
genetically identical population, which could then be compared to predictions
from models that incorporate different molecular mechanisms of transcription
initiation. However, this approach suffers from the problem, that processes
downstream from transcription can affect the measured output and therefore mask
the signature of stochastic transcription initiation on the cell-to-cell
variability of the transcriptional outputs. Here we show theoretically that
measurements of the cell-to-cell variability in the number of nascent RNAs
provide a more direct test of the mechanism of transcription initiation. We
derive exact expressions for the first two moments of the distribution of
nascent RNA molecules and apply our theory to published data for a collection
of constitutively expressed yeast genes. We find that the measured nascent RNA
distributions are inconsistent with transcription initiation proceeding via one
rate-limiting step, which has been generally inferred from measurements of
cytoplasmic messenger RNA. Instead, we propose a two-step mechanism of
initiation, which is consistent with the available data. These findings for the
yeast promoters highlight the utility of our theory for deciphering
transcriptional dynamics in vivo from experiments that count nascent RNA
molecules in single cells.


title: The Greenberg functor revisited

abstract:
  The proof, but not the statement, of Proposition 18.2 contained an error
which is repaired in this version. See Remark 18.3 in this version. No other
changes.
  We extend Greenberg's original construction to arbitrary (in particular,
non-reduced) schemes over (certain types of) local artinian rings. We then
establish a number of basic properties of the extended functor and determine,
for example, its behavior under Weil restriction. We also discuss a formal
analog of the functor.


title:
The Moduli and Gravitino (non)-Problems in Models with Strongly
  Stabilized Moduli

abstract:
  In gravity mediated models and in particular in models with strongly
stabilized moduli, there is a natural hierarchy between gaugino masses, the
gravitino mass and moduli masses: $m_{1/2} \ll m_{3/2} \ll m_{\phi}$. Given
this hierarchy, we show that 1) moduli problems associated with excess entropy
production from moduli decay and 2) problems associated with moduli/gravitino
decays to neutralinos are non-existent. Placed in an inflationary context, we
show that the amplitude of moduli oscillations are severely limited by strong
stabilization. Moduli oscillations may then never come to dominate the energy
density of the Universe. As a consequence, moduli decay to gravitinos and their
subsequent decay to neutralinos need not overpopulate the cold dark matter
density.


title: Robust Compressed Sensing and Sparse Coding with the Difference Map

abstract:
  In compressed sensing, we wish to reconstruct a sparse signal $x$ from
observed data $y$. In sparse coding, on the other hand, we wish to find a
representation of an observed signal $y$ as a sparse linear combination, with
coefficients $x$, of elements from an overcomplete dictionary. While many
algorithms are competitive at both problems when $x$ is very sparse, it can be
challenging to recover $x$ when it is less sparse. We present the Difference
Map, which excels at sparse recovery when sparseness is lower and noise is
higher. The Difference Map out-performs the state of the art with
reconstruction from random measurements and natural image reconstruction via
sparse coding.


title: Relative information at the foundation of physics

abstract:
  Shannon's notion of relative information between two physical systems can
function as foundation for statistical mechanics and quantum mechanics, without
referring to subjectivism or idealism. It can also represent a key missing
element in the foundation of the naturalistic picture of the world, providing
the conceptual tool for dealing with its apparent limitations. I comment on the
relation between these ideas and Democritus.


title:
HiggsBounds-4: Improved Tests of Extended Higgs Sectors against
  Exclusion Bounds from LEP, the Tevatron and the LHC

abstract:
  We describe the new developments in version 4 of the public computer code
HiggsBounds. HiggsBounds is a tool to test models with arbitrary Higgs sectors,
containing both neutral and charged Higgs bosons, against the published
exclusion bounds from Higgs searches at the LEP, Tevatron and LHC experiments.
From the model predictions for the Higgs masses, branching ratios, production
cross sections and total decay widths - which are specified by the user in the
input for the program - the code calculates the predicted signal rates for the
search channels considered in the experimental data. The signal rates are
compared to the expected and observed cross section limits from the Higgs
searches to determine whether a point in the model parameter space is excluded
at 95% confidence level. In this document we present a modification of the
HiggsBounds main algorithm that extends the exclusion test in order to ensure
that it provides useful results in the presence of one or more significant
excesses in the data, corresponding to potential Higgs signals. We also
describe a new method to test whether the limits from an experimental search
performed under certain model assumptions can be applied to a different
theoretical model. Further developments discussed here include a framework to
take into account theoretical uncertainties on the Higgs mass predictions, and
the possibility to obtain the $\chi^2$ likelihood of Higgs exclusion limits
from LEP. Extensions to the user subroutines from earlier versions of
HiggsBounds are described. The new features are demonstrated by additional
example programs.


title: Derived-equivalent rational threefolds

abstract:
  We describe an infinite set of smooth projective threefolds that have
equivalent derived categories but are not isomorphic, contrary to a conjecture
of Kawamata. These arise as blow-ups of $\mathbb P^3$ at various configurations
of 8 points, which are related by Cremona transformations.


title:
Spectroscopy of z ~ 7 candidate galaxies: Using Lyman-alpha to constrain
  the neutral fraction of hydrogen in the high-redshift universe

abstract:
  Following our previous spectroscopic observations of $z>7$ galaxies with
Gemini/GNIRS and VLT/XSHOOTER, which targeted a total of 8 objects, we present
here our results from a deeper and larger VLT/FORS2 spectroscopic sample of
Wide Field Camera 3 selected $z>7$ candidate galaxies. With our FORS2 setup we
cover the 737-1070nm wavelength range, enabling a search for Lyman-$\alpha$ in
the redshift range spanning 5.06 - 7.80. We target 22 $z$-band dropouts and
find no evidence of Lyman-$\alpha$ emission, with the exception of a tentative
detection ($<5\sigma$, which is our adopted criterion for a secure detection)
for one object. The upper limits on Lyman-$\alpha$ flux and the broad-band
magnitudes are used to constrain the rest-frame Equivalent Widths for this line
emission. We analyse our FORS2 observations in combination with our previous
GNIRS and XSHOOTER observations, and suggest that a simple model where the
fraction of high rest-frame Equivalent Width emitters follows the trend seen at
$z=3-6.5$ is inconsistent with our non-detections at $z\sim7.8$ at the 96\%
confidence level. This may indicate that a significant neutral HI fraction in
the intergalactic medium suppresses Lyman-$\alpha$, with an estimated neutral
fraction $\chi_{HI}\sim0.5$, in agreement with other estimates.


title: Dynamic web cache publishing for IaaS clouds using Shoal

abstract:
  We have developed a highly scalable application, called Shoal, for tracking
and utilizing a distributed set of HTTP web caches. Squid servers advertise
their existence to the Shoal server via AMQP messaging by running Shoal Agent.
The Shoal server provides a simple REST interface that allows clients to
determine their closest Squid cache. Our goal is to dynamically instantiate
Squid caches on IaaS clouds in response to client demand. Shoal provides the
VMs on IaaS clouds with the location of the nearest dynamically instantiated
Squid Cache. In this paper, we describe the design and performance of Shoal.


title:
Revisiting Aggregation for Data Intensive Applications: A Performance
  Study

abstract:
  Aggregation has been an important operation since the early days of
relational databases. Today's Big Data applications bring further challenges
when processing aggregation queries, demanding adaptive aggregation algorithms
that can process large volumes of data relative to a potentially limited memory
budget (especially in multiuser settings). Despite its importance, the design
and evaluation of aggregation algorithms has not received the same attention
that other basic operators, such as joins, have received in the literature. As
a result, when considering which aggregation algorithm(s) to implement in a new
parallel Big Data processing platform (AsterixDB), we faced a lack of "off the
shelf" answers that we could simply read about and then implement based on
prior performance studies.
  In this paper we revisit the engineering of efficient local aggregation
algorithms for use in Big Data platforms. We discuss the salient implementation
details of several candidate algorithms and present an in-depth experimental
performance study to guide future Big Data engine developers. We show that the
efficient implementation of the aggregation operator for a Big Data platform is
non-trivial and that many factors, including memory usage, spilling strategy,
and I/O and CPU cost, should be considered. Further, we introduce precise cost
models that can help in choosing an appropriate algorithm based on input
parameters including memory budget, grouping key cardinality, and data skew.


title: Singularities of the discrete KdV equation and the Laurent property

abstract:
  We study the distribution of singularities for partial difference equations,
in particular, the bilinear and nonlinear form of the discrete version of the
Korteweg-de Vries (dKdV) equation. By the Laurent property, the irreducibility,
and the co-primeness of the terms of the bilinear dKdV equation, we clarify the
relationship of these properties with the appearance of zeros in the time
evolution. The results are applied to the nonlinear dKdV equation and we
formulate the famous integrability criterion (singularity confinement test) for
nonlinear partial difference equations with respect to the co-primeness of the
terms. (v2,v3,v4: minor revisions have been made)


title:
Renormalization Group Invariance in the Subtractive Renormalization
  Approach to the NN Interactions

abstract:
  In this work, we apply the subtracted kernel method (SKM) to the chiral
nucleon-nucleon ($NN$) interaction in the $^3P_0$ channel up to
next-to-next-to-leading-order ($NNLO$). We demonstrate, by explicit numerical
calculations, that the SKM procedure is renormalization group invariant under
the change of the subtraction scale provided the driving-term of the subtracted
scattering equation is evolved through a non-relativistic Callan-Symanzik
(NRCS) flow-equation.


title:
Properties of rotating Einstein-Maxwell-Dilaton black holes in odd
  dimensions

abstract:
  We investigate rotating Einstein-Maxwell-Dilaton (EMd) black holes in odd
dimensions. Focusing on black holes with equal-magnitude angular momenta, we
determine the domain of existence of these black holes. Non-extremal black
holes reside with the boundaries determined by the static and the extremal
rotating black holes. The extremal EMd black holes show proportionality of
their horizon area and their angular momenta. Thus the charge does not enter.
We also address the Einstein-Maxwell case, where the extremal rotating black
holes exhibit two branches. On the branch emerging from the Myers-Perry
solutions their angular momenta are proportional to their horizon area, whereas
on the branch emerging from the static solutions their angular momenta are
proportional to their horizon angular momenta. Only subsets of the near-horizon
solutions are realized globally. Investigating the physical properties of these
EMd black holes, we note that one can learn much about the extremal rotating
solutions from the much simpler static solutions. The angular momenta of the
extremal black holes are proportional to the area of the static ones for the
Kaluza-Klein value of the dilaton coupling constant, and remain analogous for
other values. The same is found for the horizon angular velocities of the
extremal black holes, which possess an analogous behavior to the surface
gravity of the static black holes. The gyromagnetic ratio is rather well
approximated by the `static' value, obtained perturbatively for small angular
momenta.


title:
A multiphase constitutive modeling framework for unsaturated soil
  behavior

abstract:
  We develop a framework for constitutive modeling of unsaturated soils that
has the embedded elements of lower scale grain to grain contacts. Continuum
models developed from this framework will possess two different phases
idealizing the solid grains and their interactions. As a consequence, two
different constitutive relationships, corresponding to the grain to grain
contact and bulk behavior, co-exist in a constitutive model and govern the
response of the model. To be specific, grain to grain sliding under dry or wet
condition is idealized and appears as a simple contact law embedded in a
continuum framework. There is no need to define plastic strain, as this
quantity naturally emerges at the continuum scale as the consequence of
frictional sliding at the lower scale. In addition, the effective stress can be
naturally worked out from the grain to grain contact law embedded in the model
without being subjected to any interpretation. This, in our opinion, is a
closer representation of unsaturated soil behavior, compared to existing
continuum approaches that map everything onto a single stress-strain
relationship. In this paper, the framework is presented in its simplest form
that takes into account sliding on a single orientation. Grain to grain contact
law with capillary effects is used for the demonstration of the concept, and
the technical details behind it. Generalization of the framework for better
representation of unsaturated soil behavior will also be sketched out.


title:
Screening Charged Impurities and Lifting the Orbital Degeneracy in
  Graphene by Populating Landau Levels

abstract:
  We report the observation of an isolated charged impurity in graphene and
present direct evidence of the close connection between the screening
properties of a 2D electron system and the influence of the impurity on its
electronic environment. Using scanning tunneling microscopy and Landau level
spectroscopy we demonstrate that in the presence of a magnetic field the
strength of the impurity can be tuned by controlling the occupation of
Landau-level states with a gate-voltage. At low occupation the impurity is
screened becoming essentially invisible. Screening diminishes as states are
filled until, for fully occupied Landau-levels, the unscreened impurity
significantly perturbs the spectrum in its vicinity. In this regime we report
the first observation of Landau-level splitting into discrete states due to
lifting the orbital degeneracy.


title:
New Coordinates for the Amplitude Parameter Space of Continuous
  Gravitational Waves

abstract:
  The parameter space for continuous gravitational waves (GWs) can be divided
into amplitude parameters (signal amplitude, inclination and polarization
angles describing the orientation of the source, and an initial phase) and
phase-evolution parameters. The division is useful in part because the
Jaranowski-Krolak-Schutz (JKS) coordinates on the four-dimensional amplitude
parameter space allow the GW signal to be written as a linear combination of
four template waveforms with the JKS coordinates as coefficients. We define a
new set of coordinates on the amplitude parameter space, with the same
properties, which is more closely connected to the physical amplitude
parameters. These naturally divide into two pairs of Cartesian-like coordinates
on two-dimensional subspaces, one corresponding to left- and the other to
right-circular polarization. We thus refer to these as CPF (circular
polarization factored) coordinates. The corresponding two sets of polar
coordinates (known as CPF-polar) can be related in a simple way to the physical
parameters. We illustrate some simplifying applications for these various
coordinate systems, such as: a calculation of Jacobians between various
coordinate systems; an illustration of the signal coordinate singularities
associated with left- and right-circular polarization, which correspond to the
origins of the two two-dimensional subspaces; and an elucidation of the form of
the log-likelihood ratio between hypotheses of Gaussian noise with and without
a continuous GW signal. These are used to illustrate some of the prospects for
approximate evaluation of a Bayesian detection statistic defined by
marginalization over the physical parameter space. Additionally, in the
presence of simplifying assumptions about the observing geometry, we are able
to explicitly evaluate the integral for the Bayesian detection statistic, and
compare it to the approximate results.


title:
K-theoretic Chow groups of derived categories of schemes-on a question
  by Green-Griffiths

abstract:
  Based on Balmer's tensor triangular Chow group, we propose K-theoretic Chow
groups of derived categories of noetherian schemes and their Milnor variants
for regular schemes and their thickenings. We discuss functoriality and show
that our Chow groups agree with the classical ones for regular schemes.
Moreover, we also define tangent spaces to our Chow groups as usually and
identify them with cohomology groups of differentials. As an application, we
extend Bloch-Quillen identification and soule's variant from regular schemes to
their thickenings. This gives a positive answer to a question by
Green-Griffiths.


title: Higgs Pair Production at the LHC and ILC from general potential

abstract:
  Higgs cubic coupling plays a crucial role to probe an origin of electroweak
symmetry breaking. It is expected that the cubic coupling is measured by Higgs
pair production at the LHC and ILC, and the deviations from the standard model
can be extracted from the Higgs pair production process, and those can give us
a hint of new physics beyond the standard model. We consider a general
potential that achieves the suitable electroweak symmetry breaking. As one of
the interesting models, we suggest a non-perturbative Higgs model in which a
run-away type of potential is used. In the model, the cross sections of pair
production at the LHC is enlarged compared to the standard model. We also study
the Higgs pair production induced by a non-canonical kinetic term of Higgs
fields which will be important to search the pair-production at the ILC.


title:
Pre-neutron-emission mass distributions for reaction $^{232}$Th(n, f) up
  to 60 MeV

abstract:
  The pre-neutron-emission mass distributions for reaction $^{232}$Th(n, f) up
to 60 MeV are systematically studied with an empirical fission potential model.
The energy dependences of the peaks and valleys of the pre-neutron-emission
mass distributions are described by the exponential expressions based on the
newly measured data. The energy dependence of evaporation neutrons before
scission, which plays a crucial role for the reasonable description of the mass
distribution, is also considered. Both the double-humped and triple-humped
shape of the measured pre-neutron-emission mass distributions for reaction
$^{232}$Th(n, f) are reasonably well reproduced at incident energies up to 60
MeV. The mass distributions at unmeasured energies and the critical energies at
which the humped pre-neutron-emission mass distributions are transformed into
each other are also predicted.


title:
The Second Order Terms of the Variance Curves for Some Queueing Output
  Processes

abstract:
  We consider queueing output processes of some elementary queueing models such
as the M/M/1/K queue and the M/G/1 queue. An important performance measure for
these counting processes is their variance curve, indicating the variance of
the number of served customers over a time interval. Recent work has revealed
some non-trivial properties dealing with the asymptotic rate at which the
variance curve grows. In this paper we add to the results by finding explicit
expressions for the second order approximation of the variance curve, namely
the y-intercept of the linear asymptote.
  For M/M/1/K queues our results are based on the Drazin inverse of the
generator. It turns out that by viewing output processes as MAPs (Markovian
Arrival Processes) and considering the Drazin inverse, one can obtain explicit
expressions for the y-intercept, together with some further insight regarding
the BRAVO effect (Balancing Reduces Asymptotic Variance of Outputs). For M/G/1
queues our results are based on a classic transform of D.J. Daley. In this case
we represent the y-intercept of the variance curve in terms of the first three
moments of the service time distribution.
  A further performance measure that we are able to calculate for both models,
is the asymptotic covariance between the queue length and the number of
arrivals or departures. In addition we shed light on a classic conjecture of
Daley, dealing with characterization of stationary M/M/1 queues within the
class of stationary M/G/1 queues, based on the variance curve.


title: Tunable slowing, storing and releasing of a weak microwave field

abstract:
  We study the slowing, storing and releasing of microwave pulses in a
superconducting circuits composed of two coplanar waveguide resonators and a
superconducting transmon-type qubit. The quantum interference analogy to
electromagnetically induced transparency is created in two coupled resonators.
By tuning the resonance frequency of the transmon, we dynamically tune the
effective coupling between the resonators. Via the modulation of the coupling,
we show the tunable true time delay of microwave pulses at the single-photon
level. We also store the microwave field in a high-Q resonator and release the
signal from it to the output port. Our scheme promises applications in both
quantum information processing and classical wireless communications.


title:
Directional infrared emission resulting from cascade population
  inversion and four-wave mixing in Rb vapours

abstract:
  Directional infrared emission at 1367 and 5230 nm is generated in Rb vapours
that are step-wise excited by low-power resonant light. The mid-infrared
radiation originating from amplified spontaneous emission on the 5D-6P
transition consists of forward- and backward-directed components with
distinctive spectral and spatial properties. Diffraction limited near-infrared
light at 1367 nm generated in the co-propagating direction only is a product of
parametric wave mixing around the 5P-5D-6P-6S-5P transition loop. This highly
non-degenerate mixing process involves one externally applied and two
internally generated optical fields. Similarities between wave mixing generated
blue and near-IR light are demonstrated.


title:
Bayesian inference as iterated random functions with applications to
  sequential inference in graphical models

abstract:
  We propose a general formalism of iterated random functions with semigroup
property, under which exact and approximate Bayesian posterior updates can be
viewed as specific instances. A convergence theory for iterated random
functions is presented. As an application of the general theory we analyze
convergence behaviors of exact and approximate message-passing algorithms that
arise in a sequential change point detection problem formulated via a latent
variable directed graphical model. The sequential inference algorithm and its
supporting theory are illustrated by simulated examples.


title:
The effect of optical lattice heating on the momentum distribution of a
  1D Bose gas

abstract:
  We theoretically study how excitations due to spontaneous emission and trap
fluctuations combine with elastic collisions to change the momentum
distribution of a trapped non-degenerate one-dimensional (1D) Bose gas. Using
calculated collisional relaxation rates, we first present a semi-analytical
model for the momentum distribution evolution to get insight into the main
processes responsible for the system dynamics. We then present a Monte-Carlo
simulation that includes features that cannot be handled analytically, and
compare its results to experimental data. These calculations provide a baseline
for how integrable 1D Bose gases evolve due to heating processes in the absence
of diffractive collisions that might thermalize the gases.


title: Magnetic Generation due to Mass Difference between Charge Carriers

abstract:
  The possibility of spontaneous magnetization due to the "asymmetry in mass"
of charge carriers in a system is investigated. Analysis shows that when the
masses of positive and negative charge carriers are identical, no magnetization
is predicted. However, if the masses of two species are different, spontaneous
magnetic field would appear, either due to the equipartition of magnetic energy
or due to fluctuations together with a feedback mechanism. The conditions for
magnetization to occur are also obtained, in the form of n-T phase diagram. The
theory proposed here, if confirmed by future observations and/or experiments,
would provide a new insight on the origin of magnetic fields in the universe.


title:
Traveling Through the Universe: Back in Time to the Quark-Gluon Plasma
  Era

abstract:
  We survey the early history of the discovery of quark gluon plasma and the
early history of the Universe, beginning with the present day and reaching deep
into QGP and almost beyond. We introduce cosmological Universe dynamics and
connect the different Universe epochs with one another. We describe some of the
many remaining open questions that emerge.


title: The Astronomy of the Kamilaroi People and their Neighbours

abstract:
  The Kamilaroi people and their neighbours, the Euahlayi, Ngemba, and
Murrawarri, are an Aboriginal cultural grouping located in the northwest and
north central of New South Wales. They have a rich history, but have been
missed in much of the literature concerned with sky knowledge in culture. This
study collected stories, some of which have not previously been reported in an
academic format, from Aboriginal people practicing their culture, augmented
with stories from the literature, and analysed the data to create a database of
sky knowledge that will be added to the larger body of Aboriginal cultural
knowledge in Australia. We found that there is a strong sky culture reflected
in the stories, and we also explored the stories for evidence of an
ethnoscientific approach to knowledge of the sky.


title:
Stratified Magnetically-Driven Accretion-Disk Winds and Their Relations
  to Jets

abstract:
  We explore the poloidal structure of two-dimensional (2D) MHD winds in
relation to their potential association with the X-ray warm absorbers (WAs) and
the highly-ionized ultra-fast outflows (UFOs) in AGN, in a single unifying
approach. We present the density $n(r,\theta)$, ionization parameter
$\xi(r,\theta)$, and velocity structure $v(r,\theta)$ of such ionized winds for
typical values of their fluid-to-magnetic flux ratio, $F$, and specific angular
momentum, $H$, for which wind solutions become super-\Alfvenic. We explore the
geometrical shape of winds for different values of these parameters and
delineate the values that produce the widest and narrowest opening angles of
these winds, quantities necessary in the determination of the statistics of AGN
obscuration. We find that winds with smaller $H$ show a poloidal geometry of
narrower opening angles with their \Alfven\ surface at lower inclination angles
and therefore they produce the highest line of sight (LoS) velocities for
observers at higher latitudes with the respect to the disk plane. We further
note a physical and spatial correlation between the X-ray WAs and UFOs that
form along the same LoS to the observer but at different radii, $r$, and
distinct values of $n$, $\xi$ and $v$ consistent with the latest spectroscopic
data of radio-quiet Seyfert galaxies. We also show that, at least in the case
of 3C 111, the winds' pressure is sufficient to contain the relativistic plasma
responsible for its radio emission. Stratified MHD disk-winds could therefore
serve as a unique means to understand and unify the diverse AGN outflows.


title:
A Local Characterization of Lyapunov Functions and Robust Stability of
  Perturbed Systems on Riemannian Manifolds

abstract:
  This paper proposes several Converse Lyapunov Theorems for nonlinear
dynamical systems defined on smooth connected Riemannian manifolds and
characterizes properties of corresponding Lyapunov functions in a normal
neighborhood of an equilibrium. We extend the methods of constructing of
Lyapunov functions for ordinary differential equations on $\mathds{R}^{n}$ to
dynamical systems defined on Riemannian manifolds by employing the differential
geometry. By employing the derived properties of Lyapunov functions, we
obtained the stability of perturbed dynamical systems on Riemannian manifolds.
The results are obtained by employing the notions of normal neighborhoods, the
injectivity radius on Riemannian manifolds and existence of bump functions on
manifolds.


title: Hosotani mechanism on the lattice

abstract:
  We explore the phase structure and symmetry breaking in four-dimensional
SU(3) gauge theory with one spatial compact dimension on the lattice in the
presence of fermions in the adjoint and fundamental representations with
general boundary conditions. The eigenvalue phases of Polyakov loops and the
associated susceptibility are measured on 16^3 x 4 lattice. We establish a
correspondence between the phases found on the lattice and the gauge symmetry
breaking by the Hosotani mechanism.


title:
Coherent Magnetism and Spin-Orbit Interaction in Garnet Films Probed
  with Femtosecond Magneto-Optical Four Wave Mixing

abstract:
  We report about the dephasing of the spins states in a Garnet film excited by
femtosecond laser pulses. It is shown that magneto-optical four-wave-mixing
signals are efficiently generated and controlled with an external static
magnetic field. The self-diffraction of either two or three femtosecond pulses
allows us determining independently the coherent response time ($T_2$ < 50 fs)
and the population relaxation, which occurs in several steps. After the laser
induced demagnetization, the spin-lattice relaxation is the dominant mechanism
($T_{1,spin-lat}$ < 1.35 ps) and the precession of the magnetization takes
place at later times ($T_{1,prec}$ < 150 ps). The coherent response of the
spins states is modeled with a multi-level hydrogen-like system, taking into
account the fundamental relativistic quantum dynamics of the spins. Our
experimental approach is general and opens the way to investigating quantum
magnetism in ordered magnetic systems useful for applications in information
and communications technologies.


title:
To P or not to P: on the evidential nature of P-values and their place
  in scientific inference

abstract:
  The customary use of P-values in scientific research has been attacked as
being ill-conceived, and the utility of P-values has been derided. This paper
reviews common misconceptions about P-values and their alleged deficits as
indices of experimental evidence and, using an empirical exploration of the
properties of P-values, documents the intimate relationship between P-values
and likelihood functions. It is shown that P-values quantify experimental
evidence not by their numerical value, but through the likelihood functions
that they index. Many arguments against the utility of P-values are refuted and
the conclusion is drawn that P-values are useful indices of experimental
evidence. The widespread use of P-values in scientific research is well
justified by the actual properties of P-values, but those properties need to be
more widely understood.


title:
Well-posedness and Ill-posedness for the cubic fractional Schr\"odinger
  equations

abstract:
  We study the low regularity well-posedness of the 1-dimensional cubic
nonlinear fractional Schr\"odinger equations with L\'{e}vy indices $1 < \alpha
< 2$. We consider both non-periodic and periodic cases, and prove that the
Cauchy problems are locally well-posed in $H^s$ for $s \geq \frac {2-\alpha}4$.
This is shown via a trilinear estimate in Bourgain's $X^{s,b}$ space. We also
show that non-periodic equations are ill-posed in $H^s$ for $\frac {2 -
3\alpha}{4(\alpha + 1)} < s < \frac {2-\alpha}4$ in the sense that the flow map
is not locally uniformly continuous.


title: The Correlation Potential of a Test Ion Near a Strongly Charged Plate

abstract:
  We analytically calculate the correlation potential of a test ion near a
\emph{strongly} charged plate inside a dilute $m:-n$ electrolyte. We do this by
calculating the electrostatic Green's function in the presence of a nonlinear
background potential, the latter having been obtained using the nonlinear
Poisson-Boltzmann theory. We consider the general case where the dielectric
constants of the plate and the electrolyte are distinct. The following generic
results emerge from our analyses: (1) If the distance to the plate $\Delta z$
is much larger than a Gouy-Chapman length, the plate surface will behave
effectively as an infinitely charged surface, and the dielectric constant of
the plate effectively plays no role. (2) If $\Delta z$ is larger than a
Gouy-Chapman length but shorter than a Debye length, the correlation potential
can be interpreted in terms of an image charge that is three times larger than
the source charge. This behavior is independent of the valences of the ions.
(3) The Green's function vanishes inside the plate if the surface charge
density is infinitely large; hence the electrostatic potential is constant
there. In this respect, a strongly charged plate behaves like a conductor
plate. (4) If $\Delta z$ is smaller than a Gouy-Chapman length, the correlation
potential is dominated by the conventional image charge due to the dielectric
discontinuity at the interface. (5) If $\Delta z$ is larger than a Debye
length, the leading order behavior of the correlation potential will depend on
the valences of the ions in the electrolyte. Furthermore, inside an
\emph{asymmetric} electrolyte, the correlation potential is \emph{singly}
screened, i.e., it undergoes exponential decay with a decay width equal to the
Debye length.


title: JLQCD IroIro++ lattice code on BG/Q

abstract:
  We describe our experience on the multipurpose C++ code IroIro++ designed for
JLQCD to run on the BG/Q installation at KEK. We discuss some details on the
performance improvements specific for the IBM Blue Gene Q.


title: Selection and Estimation for Mixed Graphical Models

abstract:
  We consider the problem of estimating the parameters in a pairwise graphical
model in which the distribution of each node, conditioned on the others, may
have a different parametric form. In particular, we assume that each node's
conditional distribution is in the exponential family. We identify restrictions
on the parameter space required for the existence of a well-defined joint
density, and establish the consistency of the neighbourhood selection approach
for graph reconstruction in high dimensions when the true underlying graph is
sparse. Motivated by our theoretical results, we investigate the selection of
edges between nodes whose conditional distributions take different parametric
forms, and show that efficiency can be gained if edge estimates obtained from
the regressions of particular nodes are used to reconstruct the graph. These
results are illustrated with examples of Gaussian, Bernoulli, Poisson and
exponential distributions. Our theoretical findings are corroborated by
evidence from simulation studies.


title:
Layer potentials and boundary value problems for elliptic equations with
  complex $L^{\infty}$ coefficients satisfying the small Carleson measure norm
  condition

abstract:
  We consider divergence form elliptic equations $Lu:=\nabla\cdot(A\nabla u)=0$
in the half space $\mathbb{R}^{n+1}_+ :=\{(x,t)\in
\mathbb{R}^n\times(0,\infty)\}$, whose coefficient matrix $A$ is complex
elliptic, bounded and measurable. In addition, we suppose that $A$ satisfies
some additional regularity in the direction transverse to the boundary, namely
that the discrepancy $A(x,t) -A(x,0)$ satisfies a Carleson measure condition of
Fefferman-Kenig-Pipher type, with small Carleson norm. Under these conditions,
we establish a full range of boundedness results for double and single layer
potentials in $L^p$, Hardy, Sobolev, BMO and H\"older spaces. Furthermore, we
prove solvability of the Dirichlet problem for $L$, with data in
$L^p(\mathbb{R}^n)$, $BMO(\mathbb{R}^n)$, and $C^\alpha(\mathbb{R}^n)$, and
solvability of the Neumann and Regularity problems, with data in the spaces
$L^p(\mathbb{R}^n)/H^p(\mathbb{R}^n)$ and
$L^p_1(\mathbb{R}^n)/H^{1,p}(\mathbb{R}^n)$ respectively, with the appropriate
restrictions on indices, assuming invertibility of layer potentials in for the
$t$-independent operator $L_0:= -\nabla\cdot(A(\cdot,0)\nabla)$.


title: Can a black hole with conformal scalar hair rotate?

abstract:
  It is shown that, under the separability assumption for the metric, the
slow-rotation approximation for the Bocharova-Bronnikov-Melnikov-Bekenstein
black hole in general relativity with a conformally coupled scalar field does
not work outside the event horizon. Suggestions indicated by our present
analysis towards a fully rotating black hole solution are discussed.


title: A strong version of implicit function theorem

abstract:
  We suggest the necessary/sufficient criteria for the existence of a
(order-by-order) solution y(x) of a functional equation F(x,y)=0 over a ring.
In full generality, the criteria hold in the category of filtered groups, this
includes the wide class of modules over (commutative, associative) rings. The
classical implicit function theorem and its strengthening obtained by Tougeron
and Fisher appear to be (weaker) particular forms of the general criterion.
  We obtain a special criterion for solvability of the equations arising from
group actions, g(w)=w+u, here u is "small". As an immediate application we
re-derive the classical criteria of determinacy, in terms of the tangent space
to the orbit.
  Finally, we prove the Artin-Tougeron-type approximation theorem: if a system
of C^\infty-equations has a formal solution and the derivative satisfies a
Lojasiewicz-type condition then the system has a C^\infty-solution.


title: An FFT-based Galerkin Method for Homogenization of Periodic Media

abstract:
  In 1994, Moulinec and Suquet introduced an efficient technique for the
numerical resolution of the cell problem arising in homogenization of periodic
media. The scheme is based on a fixed-point iterative solution to an integral
equation of the Lippmann-Schwinger type, with action of its kernel efficiently
evaluated by the Fast Fourier Transform techniques. The aim of this work is to
demonstrate that the Moulinec-Suquet setting is actually equivalent to a
Galerkin discretization of the cell problem, based on approximation spaces
spanned by trigonometric polynomials and a suitable numerical integration
scheme. For the latter framework and scalar elliptic setting, we prove
convergence of the approximate solution to the weak solution, including
a-priori estimates for the rate of convergence for sufficiently regular data
and the effects of numerical integration. Moreover, we also show that the
variational structure implies that the resulting non-symmetric system of linear
equations can be solved by the conjugate gradient method. Apart from providing
a theoretical support to Fast Fourier Transform-based methods for numerical
homogenization, these findings significantly improve on the performance of the
original solver and pave the way to similar developments for its many
generalizations proposed in the literature.

categories: math.NA cond-mat.mtrl-sci math.AP physics.comp-ph


title:
Conceptual quantification of the dynamicity of longitudinal social
  networks

abstract:
  A longitudinal social network evolves over time through the creation and/ or
deletion of links among a set of actors (e.g. individuals or organizations).
Longitudinal social networks are studied by network science and social science
researchers to understand networke volution, trend propagation, friendship and
belief formation, diffusion of innovation, the spread of deviant behavior and
more. In the current literature, there are different approaches and methods
(e.g. Sampsons approach and the markov model) to study the dynamics of
longitudinal social networks. These approaches and methods have mainly been
utilised to explore evolutionary changes of longitudinal social networks from
one state to another and to explain the underlying reasons for these changes.
However, they cannot quantify the level of dynamicity of the over time network
changes and the contribution of individual network members (i.e. actors) to
these changes. In this study, we first develop a set of measures to quantify
different aspects of the dynamicity of a longitudinal social network. We then
apply these measures, in order to conduct empirical investigations, to two
different longitudinal social networks. Finally, we discuss the implications of
the application of these measures and possible future research directions of
this study.


title:
Environmental Dependence of Star Formation Law in the Disk and Center of
  IC 342

abstract:
  The Kennicutt-Schmidt (K--S) law in IC 342 is examined using the 12CO-to-H2
conversion factor (Xco,v), which depends on the metallicity and CO intensity.
Additionally, an optically thin 13CO (1-0) is also independently used to
analyze the K--S law. Xco,v is two to three times lower than the Galactic
standard Xco in the galactic center and approximately two times higher than Xco
at the disk. The surface densities of molecular gas (Sigma_H2) derived from
12CO and 13CO are consistent at the environment in a high-Sigma_H2 region. By
comparing the K-S law in the disk and the central regions of IC 342, we found
that the power law index of K-S law (N) increases toward the central region.
Furthermore, the dependence of N on Sigma_H2 is observed. Specifically, N
increases with Sigma_H2. The derived N in this work and previous observations
are consistent with the implication that star formation is likely triggered by
gravitational instability in the disk (low-Sigma_H2 region) of IC 342 and both
gravitational instability and cloud-cloud collisions in the central region
(high-Sigma_H2 regime). In addition, the increasing N toward the high-Sigma_H2
domain also matches the theoretical prediction regarding the properties of
giant molecular clouds. The results of IC 342 are supported by the same
analysis of other nearby galaxies.


title:
Plan for VLBI observations of close approaches of Jupiter to compact
  extragalactic radio sources in 2014-2016

abstract:
  Very Long Baseline Interferometry is capable of measuring the gravitational
delay caused by the Sun and planet gravitational fields. The post-Newtonian
parameter $\gamma$ is now estimated with accuracy of $\sigma_{\gamma}=2\cdot
10^{-4}$ using a global set of VLBI data from 1979 to present (Lambert,
Gontier, 2009), and $\sigma_{\gamma}=2\cdot10^{-5}$ by the Cassini spacecraft
(Bertotti et. al, 2003). Unfortunately, VLBI observations in S- and X-bands
very close to the Solar limb (less than 2-3 degrees) are not possible due to
the strong turbulence in the Solar corona. Instead, the close approach of big
planets to the line of sight of the reference quasars could be also used for
testing of the general relativity theory with VLBI. Jupiter is the most
appropriate among the big planets due to its large mass and relatively fast
apparent motion across the celestial sphere. Six close approaches of Jupiter
with quasars in 2014-2016 were found using the DE405/LE405 ephemerides,
including one occultation in 2016. We have formed tables of visibility for all
six events for VLBI radio telescopes participating in regular IVS programs.
Expected magnitudes of the relativistic effects to be measured during these
events are discussed in this paper.


title:
Quantum states as complex probabilities: The physics behind direct
  observations of photon wavefunctions in weak measurements

abstract:
  Weak measurements of photon position can be used to obtain direct
experimental evidence of the wavefunction of a photon between generation and
ultimate detection. Significantly, these measurement results can also be
understood as complex valued conditional probabilities of intermediate photon
positions. It is therefore possible to interpret the quantum state as a complex
valued probability distribution from which measurement probabilities can be
derived according to Bayesian rules. The conventional measurement probabilities
derived from squares of the wavefunction then describes the effects of
measurement back-action, which originate from a non-classical relation between
dynamics and statistics that is characteristic of quantum mechanics. It is
pointed out that this relation can be used to derive the complete Hilbert space
formalism directly from complex probabilities, without the axiomatic
introduction of quantum states or operators.


title:
Existence of maximizers for Hardy-Littlewood-Sobolev inequalities on the
  Heisenberg group

abstract:
  In this paper, we investigate the sharp Hardy-Littlewood-Sobolev inequalities
on the Heisenberg group. On one hand, we apply the concentration compactness
principle to prove the existence of the maximizers. While the approach here
gives a different proof under the special cases discussed in a recent work of
Frank and Lieb, we generalize the result to all admissible cases. On the other
hand, we provide the upper bounds of sharp constants for these inequalities.


title:
Reconstruction algorithm in compressed sensing based on maximum a
  posteriori estimation

abstract:
  We propose a systematic method for constructing a sparse data reconstruction
algorithm in compressed sensing at a relatively low computational cost for
general observation matrix. It is known that the cost of l1-norm minimization
using a standard linear programming algorithm is O(N^3). We show that this cost
can be reduced to O(N^2) by applying the approach of posterior maximization.
Furthermore, in principle, the algorithm from our approach is expected to
achieve the widest successful reconstruction region, which is evaluated from
theoretical argument. We also discuss the relation between the belief
propagation-based reconstruction algorithm introduced in preceding works and
our approach.


title:
Higher-Order Improvements of the Sieve Bootstrap for Fractionally
  Integrated Processes

abstract:
  This paper investigates the accuracy of bootstrap-based inference in the case
of long memory fractionally integrated processes. The re-sampling method is
based on the semi-parametric sieve approach, whereby the dynamics in the
process used to produce the bootstrap draws are captured by an autoregressive
approximation. Application of the sieve method to data pre-filtered by a
semi-parametric estimate of the long memory parameter is also explored.
Higher-order improvements yielded by both forms of re-sampling are demonstrated
using Edgeworth expansions for a broad class of statistics that includes first-
and second-order moments, the discrete Fourier transform and regression
coefficients. The methods are then applied to the problem of estimating the
sampling distributions of the sample mean and of selected sample
autocorrelation coefficients, in experimental settings. In the case of the
sample mean, the pre-filtered version of the bootstrap is shown to avoid the
distinct underestimation of the sampling variance of the mean which the raw
sieve method demonstrates in finite samples, higher order accuracy of the
latter notwithstanding. Pre-filtering also produces gains in terms of the
accuracy with which the sampling distributions of the sample autocorrelations
are reproduced, most notably in the part of the parameter space in which
asymptotic normality does not obtain. Most importantly, the sieve bootstrap is
shown to reproduce the (empirically infeasible) Edgeworth expansion of the
sampling distribution of the autocorrelation coefficients, in the part of the
parameter space in which the expansion is valid.


title:
Anomalous D'yakonov-Perel' spin relaxation in InAs (110) quantum wells
  under strong magnetic field: role of Hartree-Fock self-energy

abstract:
  We investigate the influence of the Hartree-Fock self-energy, acting as an
effective magnetic field, on the anomalous D'yakonov-Perel' spin relaxation in
InAs (110) quantum wells when the magnetic field in the Voigt configuration is
much stronger than the spin-orbit-coupled field. The transverse and
longitudinal spin relaxations are discussed both analytically and numerically.
For the transverse configuration, it is found that the spin relaxation is very
sensitive to the Hartree-Fock effective magnetic field, which is very different
from the conventional D'yakonov-Perel' spin relaxation. Even an extremely small
spin polarization ($P=0.1\%$) can significantly influence the behavior of the
spin relaxation. It is further revealed that this comes from the {\em unique}
form of the effective inhomogeneous broadening, originated from the mutually
perpendicular spin-orbit-coupled field and strong magnetic field. It is shown
that this effective inhomogeneous broadening is very small and hence very
sensitive to the Hartree-Fock field. Moreover, we further find that in the spin
polarization dependence, the transverse spin relaxation time decreases with the
increase of the spin polarization in the intermediate spin polarization regime,
which is also very different from the conventional situation, where the spin
relaxation is always suppressed by the Hartree-Fock field. It is revealed that
this {\em opposite} trends come from the additional spin relaxation channel
induced by the HF field. For the longitudinal configuration, we find that the
spin relaxation can be either suppressed or enhanced by the Hartree-Fock field
if the spin polarization is parallel or antiparallel to the magnetic field.


title: A Bayesian framework for functional time series analysis

abstract:
  The paper introduces a general framework for statistical analysis of
functional time series from a Bayesian perspective. The proposed approach,
based on an extension of the popular dynamic linear model to Banach-space
valued observations and states, is very flexible but also easy to implement in
many cases. For many kinds of data, such as continuous functions, we show how
the general theory of stochastic processes provides a convenient tool to
specify priors and transition probabilities of the model. Finally, we show how
standard Markov chain Monte Carlo methods for posterior simulation can be
employed under consistent discretizations of the data.


title: Lattice study on chiral dynamics of two-color six-flavors QCD

abstract:
  The electroweak symmetry breaking and origin of masses may be attributed to
the breakdown of chiral symmetry due to a strong gauge dynamics. Among several
candidates of such gauge systems, we focus on two-color QCD with $N_f=6$
massless Dirac fermions in the fundamental representation, and study on whether
the dynamics of this gauge system trigger chiral symmetry breaking or not by
simulating with Wilson fermions on lattices up to $L/a=32$. We show the result
for the quark mass dependence and the volume dependence of some quantities such
as the mass of the lightest pseudoscalar meson, decay constant, and give the
three evidences supporting the absence of chiral symmetry breaking in the
six-flavor theory.


title:
An Efficient Feedback Coding Scheme with Low Error Probability for
  Discrete Memoryless Channels

abstract:
  Existing fixed-length feedback communication schemes are either specialized
to particular channels (Schalkwijk--Kailath, Horstein), or apply to general
channels but either have high coding complexity (block feedback schemes) or are
difficult to analyze (posterior matching). This paper introduces a new
fixed-length feedback coding scheme which achieves the capacity for all
discrete memoryless channels, has an error exponent that approaches the sphere
packing bound as the rate approaches the capacity, and has $O(n\log n)$ coding
complexity. These benefits are achieved by judiciously combining features from
previous schemes with new randomization technique and encoding/decoding rule.
These new features make the analysis of the error probability for the new
scheme easier than for posterior matching.


title: Quantum Action Principle with Generalized Uncertainty Principle

abstract:
  One of the common features in all promising candidates of quantum gravity is
the existence of a minimal length scale, which naturally emerges with a
generalized uncertainty principle, or equivalently a modified commutation
relation. Schwinger's quantum action principle was modified to incorporate this
modification, and was applied to the calculation of the kernel of a free
particle, partly recovering the result previously studied using path integral.


title: Lie bialgebras of generalized loop Virasoro algebras

abstract:
  The first cohomology group of a generalized loop Virasoro algebra with
coefficients in the tensor product of its adjoint module is shown to be
trivial. The result is applied to prove that Lie bialgebra structures on
generalized loop Virasoro algebras are coboundary triangular. We then
generalize the results to generalized map Virasoro algebras.


title: Influence of Kaluza Scalar on the Raychaudhuri Equation

abstract:
  It is shown that the influence of Kaluza scalar is to induce expansion in the
Raychaudhuri equation for two representative solutions of the Kaluza theory.


title: The Dual Gromov-Hausdorff Propinquity

abstract:
  Motivated by the quest for an analogue of the Gromov-Hausdorff distance in
noncommutative geometry which is well-behaved with respect to C*-algebraic
structures, we propose a complete metric on the class of Leibniz quantum
compact metric spaces, named the dual Gromov-Hausdorff propinquity. This metric
resolves several important issues raised by recent research in noncommutative
metric geometry: it makes *-isomorphism a necessary condition for distance
zero, it is well-adapted to Leibniz seminorms, and --- very importantly --- is
complete, unlike the quantum propinquity which we introduced earlier. Thus our
new metric provides a natural tool for noncommutative metric geometry, designed
to allow for the generalizations of techniques from metric geometry to
C*-algebra theory.


title: On enumeration of a class of toroidal graphs

abstract:
  We present enumerations of a class of toroidal graphs which give rise to
semi-equivelar maps. There are eleven different types of semi-equivelar maps on
the torus. These are of the types $\{3^{6}\}$, $\{4^{4}\}$, $\{6^{3}\}$,
$\{3^{3}, 4^{2}\}$, $\{3^{2}, 4, 3, 4\}$, $\{3, 6, 3, 6\}$, $\{3^{4}, 6\}$,
$\{4, 8^{2}\}$, $\{3, 12^{2}\}$, $\{4, 6, 12\}$, $\{3, 4, 6, 4\}$. We know the
classification of the maps of types $\{3^{6}\}$, $\{4^{4}\}$, $\{6^{3}\}$ on
the torus. In this article, we attempt to classify maps of types $\{3^{3},
4^{2}\}$, $\{3^{2}, 4, 3, 4\}$, $\{3, 6, 3, 6\}$, $\{3^{4}, 6\}$, $\{4,
8^{2}\}$, $\{3, 12^{2}\}$, $\{4, 6, 12\}$, $\{3, 4, 6, 4\}$ on the torus.


title: Loop Virasoro Lie Conformal Algebra

abstract:
  The Lie conformal algebra of loop Virasoro algebra, denoted by
$\mathscr{CW}$, is introduced in this paper. Explicitly, $\mathscr{CW}$ is a
Lie conformal algebra with $\mathbb{C}[\partial]$-basis
$\{L_i\,|\,i\in\mathbb{C}\}$ and $\lambda$-brackets $[L_i\, {}_\lambda \,
L_j]=(-\partial-2\lambda) L_{i+j}$. Then conformal derivations of
$\mathscr{CW}$ are determined. Finally, rank one conformal modules and
$\mathbb{Z}$-graded free intermediate series modules over $\mathscr{CW}$ are
classified.


title:
Hard X-ray emission cutoff in anomalous X-ray pulsar 4U 0142+61 detected
  by INTEGRAL

abstract:
  The anomalous X-ray pulsar 4U 0142+61 was studied by the INTEGRAL
observations. The hard X-ray spectrum of 18 -- 500 keV for 4U 0142+61 was
derived using near 9 years of INTEGRAL/IBIS data. We obtained the average hard
X-ray spectrum of 4U 0142+61 with all available data. The spectrum of 4U
0142+61 can be fitted with a power-law with an exponential high energy cutoff.
This average spectrum is well fitted with a power-law of $\Gamma\sim 0.51\pm
0.11$ plus a cutoff energy at $128.6\pm 17.2$ keV. The hard X-ray flux of the
source from 20 -- 150 keV showed no significant variations (within 20$\%$) from
2003 -- 2011. The spectral profiles have some variability in nine years: photon
index varied from 0.3 -- 1.5, and cutoff energies of 110 -- 250 keV. The
detection of the high energy cutoff around 130 keV shows some constraints on
the radiation mechanisms of magnetars and possibly probes the differences
between magnetar and accretion models for these special class of neutron stars.
Future HXMT observations could provide stronger constraints on the hard X-ray
spectral properties of this source and other magnetar candidates.


title: Universal short-time quantum critical dynamics in imaginary time

abstract:
  We propose a scaling theory for the universal imaginary-time quantum critical
dynamics for both short times and long times. We discover that there exists a
universal critical initial slip related to a small initial order parameter
$M_0$. In this stage, the order parameter $M$ increases with the imaginary time
$\tau$ as $M\propto M_0\tau^\theta$ with a universal initial slip exponent
$\theta$. For the one-dimensional transverse-field Ising model, we estimate
$\theta$ to be $0.373$, which is markedly distinct from its classical
counterpart. Apart from the local order parameter, we also show that the
entanglement entropy exhibits universal behavior in the short-time region. As
the critical exponents in the early stage and in equilibrium are identical, we
apply the short-time dynamics method to determine quantum critical properties.
The method is generally applicable in both the Landau-Ginzburg-Wilson paradigm
and topological phase transitions.


title:
Alternative Scenarios of Relativistic Heavy-Ion Collisions: III.
  Transverse Momentum Spectra

abstract:
  Transverse-mass spectra, their inverse slopes and mean transverse masses in
relativistic collisions of heavy nuclei are analyzed in a wide range of
incident energies 2.7 GeV $\le \sqrt{s_{NN}}\le$ 39 GeV. The analysis is
performed within the three-fluid model employing three different equations of
state (EoS's): a purely hadronic EoS, an EoS with the first-order phase
transition and that with a smooth crossover transition into deconfined state.
Calculations show that inverse slopes and mean transverse masses of all the
species (with the exception of antibaryons within the hadronic scenario)
exhibit a step-like behavior similar to that observed for mesons and protons in
available experimental data. This step-like behavior takes place for all
considered EoS's and results from the freeze-out dynamics rather than is a
signal of the deconfinement transition. A good reproduction of experimental
inverse slopes and mean transverse masses for light species (up to proton) is
achieved within all the considered scenarios. The freeze-out parameters are
precisely the same as those used for reproduction of particles yields in
previous papers of this series. This became possible because the freeze-out
stage is not completely equilibrium.


title:
Opportunistic Multiuser Two-Way Amplify-and-Forward Relaying with a
  Multi Antenna Relay

abstract:
  We consider the opportunistic multiuser diversity in the multiuser two-way
amplify-and-forward (AF) relay channel. The relay, equipped with multiple
antennas and a simple zero-forcing beam-forming scheme, selects a set of two
way relaying user pairs to enhance the degree of freedom (DoF) and consequently
the sum throughput of the system. The proposed channel aligned pair scheduling
(CAPS) algorithm reduces the inter-pair interference and keeps the signal to
interference plus noise power ratio (SINR) of user pairs relatively
interference free in average sense when the number of user pairs become very
large. For ideal situations, where the number of user pairs grows faster than
the system signal to noise ratio (SNR), the DoF of $M$ per channel use can be
achieved when $M$ is the relay antenna size. With a limited number of pairs,
the system is overloaded and the sum rates saturate at high signal to noise
ratio (SNR) though modifications of CAPS can improve the performance to a
certain amount. The performance of CAPS can be further enhanced by
semi-orthogonal channel aligned pair scheduling (SCAPS) algorithm, which not
only aligns the pair channels but also forms semi-orthogonal inter-pair
channels. Simulation results show that we provide a set of approaches based on
(S)CAPS and modified (S)CAPS, which provides system performance benefit
depending on the SNR and the number of user pairs in the network.


title:
Direct femtosecond pulse compression with miniature-sized Bragg
  cholesteric liquid crystal

abstract:
  Direct compression of femtosecond optical pulses from a Ti:sapphire laser
oscillator was realized with a cholesteric liquid crystal acting as a nonlinear
1D periodic Bragg grating. With a 6-um thick sample, the pulse duration could
be compressed from 100 to 48 femtoseconds. Coupled-mode equations for forward
and backward waves were employed to simulate the dynamics therein and good
agreement between theory and experiment was obtained.


title:
A DFT study of structural, dynamical properties and quasiparticle band
  structure of solid nitromethane

abstract:
  We report a detailed theoretical study of the structural, vibrational, and
optical properties of solid nitromethane using first principles density
functional calculations. The ground state properties were calculated using a
plane wave pseudopotential code with either the local density approximation
(LDA), the generalized gradient approximation (GGA), or with a correction to
include van derWaals interactions. Our calculated equilibrium lattice
parameters and volume using a dispersion correction are found to be in
reasonable agreement with the experimental results. Also, our calculations
reproduce the experimental trends in the structural properties at high
pressure. It was found to be a discontinuity in the bond length, bond angles
and also a weaking of hydrogen bond strength in the pressure range from 10 to
12 GPa, picturing the structural transition from phase I to Phase II. Moreover,
we predict the elastic constants of solid nitromethane and found that the
corresponding bulk modulus is in good agreement with experiments. The
calculated elastic constants are showing an order of C11> C22 > C33, indicating
that the material is more compressible along the c-axis. We also calculated the
zone center vibrational frequencies and discuss the internal and external modes
of this material under pressure. From this, we found the softing of lattice
modes around 8 to 12 GPa. We have also attempt the quasiparticle band structure
of solid nitromethane with the G0W0 approximation and found that nitromethane
is an indirect band gap insulator with a value of the band gap of about 7.8 eV
with G0W0 approximation. Finally, the optical properties of this material,
namely the absorptive and dispersive part of the dielectric function, and the
refractive index and absorption spectra are calculated and the contribution of
different transition peaks of the absorption spectra are analyzed.


title: Neighbour-transitive codes in Johnson graphs

abstract:
  The Johnson graph J(v,k) has, as vertices, the k-subsets of a v-set V, and as
edges the pairs of k-subsets with intersection of size k-1. We introduce the
notion of a neighbour-transitive code in J(v,k). This is a vertex subset \Gamma
such that the subgroup G of graph automorphisms leaving \Gamma invariant is
transitive on both the set \Gamma of `codewords' and also the set of
`neighbours' of \Gamma, which are the non-codewords joined by an edge to some
codeword. We classify all examples where the group G is a subgroup of the
symmetric group on V and is intransitive or imprimitive on the underlying v-set
V. In the remaining case where G lies in Sym(V) and G is primitive on V, we
prove that, provided distinct codewords are at distance at least 3 in J(v,k),
then G is 2-transitive on V. We examine many of the infinite families of finite
2-transitive permutation groups and construct surprisingly rich families of
examples of neighbour-transitive codes. A major unresolved case remains.


title: The static quark self-energy at O($\alpha^{20}$) in perturbation theory

abstract:
  In Refs. [1,2] we determined the infinite volume coefficients of the
perturbative expansions of the self-energies of static sources in the
fundamental and adjoint representations in SU(3) gluodynamics to order
$\alpha^{20}$. We used numerical stochastic perturbation theory [3], where we
employed a new second order integrator and twisted boundary conditions. The
expansions were obtained in lattice regularization with the Wilson action and
two different discretizations of the covariant time derivative within the
Polyakov loop. Overall, we obtained four different perturbative series. For all
of them the high order coefficients displayed the factorial growth predicted by
the conjectured renormalon picture, based on the operator product expansion.
This enabled us to determine the normalization constants of the leading
infrared renormalons of heavy quark and heavy gluino pole masses. Here we
present improved determinations of the normalization constants and the
perturbative coefficients by incorporating the four-loop beta-function
coefficient (which we also determine) in the fit function.


title:
Canonical equations of Hamilton for the nonlinear Schr\"{o}dinger
  equation

abstract:
  We define two different systems of mathematical physics: the second-order
differential system (SODS) and the first-order differential system (FODS). The
Newton's second law of motion and the nonlinear Schr\"{o}dinger equation (NLSE)
are the exemplary SODS and FODS, respectively. We obtain a new kind of
canonical equations of Hamilton (CEH), which are of some kind of symmetry in
form and are formally different with the conventional CEH without symmetry [H.
Goldstein, C. Poole, J. Safko, Classical Mechanics, third ed., Addison-Wesley,
2001]. We also prove that the number of the CEHs is equal to the number of the
generalized coordinates for the FODS, but twice the number of the generalized
coordinates for the SODS. We show that the FODS can only be expressed by the
new CEH, but do not by the conventional CEH, while the SODS can be done by both
the new and the conventional CEHs. As an example, we prove that the nonlinear
Schr\"{o}dinger equation can be expressed with the new CEH in a consistent way.

categories: physics.class-ph math-ph math.MP nlin.SI


title:
Distributed PI-Control with Applications to Power Systems Frequency
  Control

abstract:
  This paper considers a distributed PI-controller for networked dynamical
systems. Sufficient conditions for when the controller is able to stabilize a
general linear system and eliminate static control errors are presented. The
proposed controller is applied to frequency control of power transmission
systems. Sufficient stability criteria are derived, and it is shown that the
controller parameters can always be chosen so that the frequencies in the
closed loop converge to nominal operational frequency. We show that the load
sharing property of the generators is maintained, i.e., the input power of the
generators is proportional to a controller parameter. The controller is
evaluated by simulation on the IEEE 30 bus test network, where its
effectiveness is demonstrated.


title: Delaunay triangulation of manifolds

abstract:
  We present an algorithm for producing Delaunay triangulations of manifolds.
The algorithm can accommodate abstract manifolds that are not presented as
submanifolds of Euclidean space. Given a set of sample points and an atlas on a
compact manifold, a manifold Delaunay complex is produced provided the
transition functions are bi-Lipschitz with a constant close to 1, and the
sample points meet a local density requirement; no smoothness assumptions are
required. If the transition functions are smooth, the output is a triangulation
of the manifold.
  The output complex is naturally endowed with a piecewise flat metric which,
when the original manifold is Riemannian, is a close approximation of the
original Riemannian metric. In this case the ouput complex is also a Delaunay
triangulation of its vertices with respect to this piecewise flat metric.


title: Regulatory-Compliant Derivatives Pricing is Not Risk-Neutral

abstract:
  Regulations impose idiosyncratic capital and funding costs for holding
derivatives. Capital requirements are costly because derivatives desks are
risky businesses; funding is costly in part because regulations increase the
minimum funding tenor. Idiosyncratic costs mean no single measure makes
derivatives martingales for all market participants. Hence Regulatory-compliant
pricing is not risk-neutral. This has implications for exit prices and
mark-to-market.


title: Structure-preserving color transformations using Laplacian commutativity

abstract:
  Mappings between color spaces are ubiquitous in image processing problems
such as gamut mapping, decolorization, and image optimization for color-blind
people. Simple color transformations often result in information loss and
ambiguities (for example, when mapping from RGB to grayscale), and one wishes
to find an image-specific transformation that would preserve as much as
possible the structure of the original image in the target color space. In this
paper, we propose Laplacian colormaps, a generic framework for
structure-preserving color transformations between images. We use the image
Laplacian to capture the structural information, and show that if the color
transformation between two images preserves the structure, the respective
Laplacians have similar eigenvectors, or in other words, are approximately
jointly diagonalizable. Employing the relation between joint diagonalizability
and commutativity of matrices, we use Laplacians commutativity as a criterion
of color mapping quality and minimize it w.r.t. the parameters of a color
transformation to achieve optimal structure preservation. We show numerous
applications of our approach, including color-to-gray conversion, gamut
mapping, multispectral image fusion, and image optimization for color deficient
viewers.


title:
WISE Discovery of Hyper Luminous Galaxies at z=2-4 and Their
  Implications for Galaxy and AGN Evolution

abstract:
  On behalf of the WISE Science team, we present the discovery of a class of
distant dust-enshrouded galaxies with extremely high luminosity. These galaxies
are selected to have extreme red colors in the mid-IR using NASA's Wide-field
Infrared Survey Explorer (WISE). They are faint in the optical and near-IR,
predominantly at z=2-4, and with IR luminosity > $10^{13}\, L_{Sun}$, making
them Hyper-Luminous Infrared Galaxies (HyLIRGs). SEDs incorporating the WISE,
Spitzer, and Herschel PACS and SPIRE photometry indicate hot dust dominates the
bolometric luminosity, presumably powered by AGN. Preliminary multi-wavelength
follow-up suggests that they are different from normal populations in the local
M-sigma relation. Their low source density implies that these objects are
either intrinsically rare, or a short-lived phase in a more numerous
population. If the latter is the case, these hot, dust-enshrouded galaxies may
be an early stage in the interplay between AGN and galaxies.


title:
Subspace Thresholding Pursuit: A Reconstruction Algorithm for Compressed
  Sensing

abstract:
  We propose a new iterative greedy algorithm for reconstructions of sparse
signals with or without noisy perturbations in compressed sensing. The proposed
algorithm, called \emph{subspace thresholding pursuit} (STP) in this paper, is
a simple combination of subspace pursuit and iterative hard thresholding.
Firstly, STP has the theoretical guarantee comparable to that of $\ell_1$
minimization in terms of restricted isometry property. Secondly, with a tuned
parameter, on the one hand, when reconstructing Gaussian signals, it can
outperform other state-of-the-art reconstruction algorithms greatly; on the
other hand, when reconstructing constant amplitude signals with random signs,
it can outperform other state-of-the-art iterative greedy algorithms and even
outperform $\ell_1$ minimization if the undersampling ratio is not very large.
In addition, we propose a simple but effective method to improve the empirical
performance further if the undersampling ratio is large. Finally, it is showed
that other iterative greedy algorithms can improve their empirical performance
by borrowing the idea of STP.


title: Determination of the {\eta}'-nucleus optical potential

abstract:
  The excitation function and momentum distribution of $\eta^\prime$ mesons
have been measured in photon induced reactions on $^{12}{}$C in the energy
range of 1250-2600 MeV. The experiment was performed with tagged photon beams
from the ELSA electron accelerator using the Crystal Barrel and TAPS detectors.
The data are compared to model calculations to extract information on the sign
and magnitude of the real part of the $\eta^\prime$-nucleus potential. Within
the model, the comparison indicates an attractive potential of -($37 \pm
10(stat)\pm10(syst)$) MeV depth at normal nuclear matter density. Since the
modulus of this depth is larger than the modulus of the imaginary part of the
$\eta^\prime$-nucleus potential of -($10\pm2.5$) MeV, determined by
transparency ratio measurements, a search for resolved $\eta^\prime$-bound
states appears promising.


title:
Thermo-magnonic diode: rectification of energy and magnetization
  currents

abstract:
  We investigate the dynamics of two coupled macrospins connected to thermal
baths at different temperatures. The system behaves like a diode which allows
the propagation of energy and mag- netization currents in one direction only.
This effect is described by a simple model of two coupled nonlinear oscillators
interacting with two independent reservoirs. It is shown that the rectification
phenomenon can be interpreted as a a stochastic phase synchronization of the
two spin-oscillators. A brief comparison with realistic micromagnetic
simulations is presented. This new effect yields promising opportunities in
spin-caloritronics devices.