title:
Scaling relations and mass bias in hydrodynamical f(R) gravity
  simulations of galaxy clusters

abstract:
  We investigate the impact of chameleon-type f(R) gravity models on the
properties of galaxy clusters and groups. Our f(R) simulations follow for the
first time also the hydrodynamics of the intracluster and intragroup medium.
This allows us to assess how f(R) gravity alters the X-ray scaling relations of
clusters and how hydrostatic and dynamical mass estimates are biased when
modifications of gravity are ignored in their determination. We find that
velocity dispersions and intracluster medium temperatures are both increased by
up to 1/3 in f(R) gravity in low-mass halos, while the difference disappears in
massive objects. The mass scale of the transition depends on the background
value f_R0 of the scalar degree of freedom. These changes in temperature and
velocity dispersion alter the mass-temperature and X-ray luminosity-temperature
scaling relations and bias dynamical and hydrostatic mass estimates that do not
explicitly account for modified gravity towards higher values. Recently, a
relative enhancement of X-ray compared to weak lensing masses was found by the
Planck Collaboration (2013). We demonstrate that an explanation for this offset
may be provided by modified gravity and the associated bias effects, which
interestingly are of the required size. Finally, we find that the abundance of
subhalos at fixed cluster mass is only weakly affected by f(R) gravity.


title: A Merger Shock in Abell 2034

abstract:
  We present a $250\,$ks Chandra observation of the cluster merger A2034 with
the aim of understanding the nature of a sharp edge previously characterized as
a cold front. The new data reveal that the edge is coherent over a larger
opening angle and is significantly more bow-shock-shaped than previously
thought. Within $\sim 27\,$degrees about the axis of symmetry of the edge the
density, temperature and pressure drop abruptly by factors of
$1.83^{+0.09}_{-0.08}$, $1.85^{+0.41}_{-0.41}$ and $3.4^{+0.8}_{-0.7}$,
respectively. This is inconsistent with the pressure equilibrium expected of a
cold front and we conclude that the edge is a shock front. We measure a Mach
number $M = 1.59^{+0.06}_{-0.07}$ and corresponding shock velocity $v_{\rm
shock}\simeq 2057\,$km/s. Using spectra collected at the MMT with the Hectospec
multi-object spectrograph we identify 328 spectroscopically confirmed cluster
members. Significantly, we find a local peak in the projected galaxy density
associated with a bright cluster galaxy which is located just ahead of the nose
of the shock. The data are consistent with a merger viewed within $\sim
23\,$degrees of the plane of the sky. The merging subclusters are now moving
apart along a north-south axis approximately $0.3\,$Gyr after a small impact
parameter core passage. The gas core of the secondary subcluster, which was
driving the shock, appears to have been disrupted by the merger. Without a
driving 'piston' we speculate that the shock is dying. Finally, we propose that
the diffuse radio emission near the shock is due to the revival of pre-existing
radio plasma which has been overrun by the shock.


title:
3D simulations of the early stages of AGN jets: geometry, thermodynamics
  and backflow

abstract:
  We investigate the interplay between jets from Active Galactic Nuclei (AGNs)
and the surrounding InterStellar Medium (ISM) through full 3D, high resolution,
Adaptive Mesh Refinement simulations performed with the FLASH code. We follow
the jet- ISM system for several Myr in its transition from an early, compact
source to an extended one including a large cocoon. During the jet evolution,
we identify three major evolutionary stages and we find that, contrary to the
prediction of popular theoretical models, none of the simulations shows a
self-similar behavior. We also follow the evolution of the energy budget, and
find that the fraction of input power deposited into the ISM (the AGN coupling
constant) is of order of a few percent during the first few Myr. This is in
broad agreement with galaxy formation models employing AGN feedback. However,
we find that in these early stages, this energy is deposited only in a small
fraction (< 1%) of the total ISM volume. Finally we demonstrate the relevance
of backflows arising within the extended cocoon generated by a relativistic AGN
jet within the ISM of its host galaxy, previously proposed as a mechanism for
self-regulating the gas accretion onto the central object. These backflows tend
later to be destabilized by the 3D dynamics, rather than by hydrodynamic
(Kelvin- Helmholtz) instabilities. Yet, in the first few hundred thousand
years, backflows may create a central accretion region of significant extent,
and convey there as much as a few millions of solar masses.


title: Geometric and dynamic distortions in anisotropic galaxy clustering

abstract:
  We examine the signature of dynamic (redshift-space) distortions and
geometric distortions (including the Alcock-Paczynski effect) in the context of
the galaxy power spectrum measured in upcoming galaxy redshift surveys.
Information comes from both the baryon acoustic oscillation (BAO) feature and
the broadband power spectrum shape. Accurate modeling is required to extract
this information without introducing systematic biases in the result. We
consider an analytic model for the power spectrum of dark matter halos in
redshift space, based on the distribution function expansion, and compare with
halo clustering measured in N-body simulations. We forecast that the
distribution function model is sufficiently accurate to allow the inclusion of
broadband information on scales down to k~0.2 h/Mpc, with somewhat better
accuracy for higher bias halos. Compared with a BAO-only analysis with
reconstruction, including broadband shape information can improve unbiased
constraints on distance measures H(z) and D_A(z) by ~30% and 20%, respectively,
for a galaxy sample similar to the DESI luminous red galaxies. The gains in
precision are larger in the absence of BAO reconstruction. Furthermore,
including broadband shape information allows the measurement of structure
growth, through redshift-space distortions. For the same galaxy sample, the
distribution function model is able to constrain f*sigma_8 to ~2%, when
simultaneously fitting for H(z) and D_A(z). We discuss techniques to optimize
the analysis of the power spectrum, including removing modes near the
line-of-sight that are particularly challenging to model, and whether these
approaches can improve parameter constraints. We find that such techniques are
unlikely to significantly improve constraints on geometry, although they may
allow higher precision measurements of redshift-space distortions.


title:
Testing the No-Hair Theorem with Event Horizon Telescope Observations of
  Sagittarius A*

abstract:
  The advent of the Event Horizon Telescope (EHT), a millimeter-wave very-long
baseline interferometric array, has enabled spatially-resolved studies of the
sub-horizon-scale structure for a handful of supermassive black holes. Among
these, the supermassive black hole at the center of the Milky Way, Sagittarius
A* (Sgr A*), presents the largest angular cross section. Thus far, these
studies have focused upon measurements of the black hole spin and the
validation of low-luminosity accretion models. However, a critical input into
the analysis of EHT data is the structure of the black hole spacetime, and thus
these observations provide the novel opportunity to test the applicability of
the Kerr metric to astrophysical black holes. Here we present the first
simulated images of a radiatively inefficient accretion flow (RIAF) around Sgr
A* employing a quasi-Kerr metric that contains an independent quadrupole moment
in addition to the mass and spin that fully characterize a black hole in
general relativity. We show that these images can be significantly different
from the images of a RIAF around a Kerr black hole with the same spin and
demonstrate the feasibility of testing the no-hair theorem by constraining the
quadrupolar deviation from the Kerr metric with existing EHT data. Equally
important, we find that the disk inclination and spin orientation angles are
robust to the inclusion of additional parameters, providing confidence in
previous estimations assuming the Kerr metric based upon EHT observations.
However, at present the limits upon potential modifications of the Kerr metric
remain weak.


title:
Physical Properties of the Inner Shocks in Hot, Tilted Black Hole
  Accretion Flows

abstract:
  Simulations of hot, pressure supported, tilted black hole accretion flows, in
which the angular momentum of the flow is misaligned with the black hole spin
axis, can exhibit two non-axisymmetric shock structures in the inner regions of
the flow. We analyze the strength and significance of these shock structures in
simulations with tilt angles of 10 and 15 degrees. By integrating fluid
trajectories in the simulations through the shocks, and tracking the variations
of fluid quantities along these trajectories, we show that these shocks are
strong, with substantial compression ratios, in contrast to earlier claims.
However, they are only moderately relativistic. We also show that the two
density enhancements resembling flow streams in their shape are in fact merely
post-shock compressions, as fluid trajectories cut across, rather than flow
along, them. The dissipation associated with the shocks is a substantial
fraction ($\simeq3-12$ percent) of the rest mass energy advected into the hole,
and therefore comparable to the dissipation expected from turbulence. The
shocks should therefore make order unity changes in the observed properties of
black hole accretion flows that are tilted.


title:
MyGIsFOS: an automated code for parameter determination and detailed
  abundance analysis in cool stars

abstract:
  The current and planned high-resolution, high-multiplexity stellar
spectroscopic surveys, as well as the swelling amount of under-utilized data
present in public archives have led to an increasing number of efforts to
automate the crucial but slow process to retrieve stellar parameters and
chemical abundances from spectra. We present MyGIsFOS, a code designed to
derive atmospheric parameters and detailed stellar abundances from medium -
high resolution spectra of cool (FGK) stars. We describe the general structure
and workings of the code, present analyses of a number of well studied stars
representative of the parameter space MyGIsFOS is designed to cover, and
examples of the exploitation of MyGIsFOS very fast analysis to assess
uncertainties through Montecarlo tests. MyGIsFOS aims to reproduce a
``traditional'' manual analysis by fitting spectral features for different
elements against a precomputed grid of synthetic spectra. Fe I and Fe II lines
can be employed to determine temperature, gravity, microturbulence, and
metallicity by iteratively minimizing the dependence of Fe I abundance from
line lower energy and equivalent width, and imposing Fe I - Fe II ionization
equilibrium. Once parameters are retrieved, detailed chemical abundances are
measured from lines of other elements. MyGIsFOS replicates closely the results
obtained in similar analyses on a set of well known stars. It is also quite
fast, performing a full parameter determination and detailed abundance analysis
in about two minutes per star on a mainstream desktop computer. Currently, its
preferred field of application are high-resolution and/or large spectral
coverage data (e.g UVES, X-Shooter, HARPS, Sophie).


title:
On Constructing Constrained Tree Automata Recognizing Ground Instances
  of Constrained Terms

abstract:
  An inductive theorem proving method for constrained term rewriting systems,
which is based on rewriting induction, needs a decision procedure for
reduction-completeness of constrained terms. In addition, the sufficient
complete property of constrained term rewriting systems enables us to relax the
side conditions of some inference rules in the proving method. These two
properties can be reduced to intersection emptiness problems related to sets of
ground instances for constrained terms. This paper proposes a method to
construct deterministic, complete, and constraint-complete constrained tree
automata recognizing ground instances of constrained terms.


title: Random Generation of Nondeterministic Finite-State Tree Automata

abstract:
  Algorithms for (nondeterministic) finite-state tree automata (FTAs) are often
tested on random FTAs, in which all internal transitions are equiprobable. The
run-time results obtained in this manner are usually overly optimistic as most
such generated random FTAs are trivial in the sense that the number of states
of an equivalent minimal deterministic FTA is extremely small. It is
demonstrated that nontrivial random FTAs are obtained only for a narrow band of
transition probabilities. Moreover, an analytic analysis yields a formula to
approximate the transition probability that yields the most complex random
FTAs, which should be used in experiments.


title:
Signatures of spin-triplet excitations in optical conductivity of
  valence bond solids

abstract:
  We show that the optical responses below the Mott gap can be used to probe
the spin-triplet excitations in valence bond solid (VBS) phases in Mott
insulators. The optical conductivity in this regime arises due to the
electronic polarization mechanism via virtual electron hopping processes. We
apply this mechanism to the Hubbard model with spin-orbit couplings and/or the
corresponding spin model with significant Dzyaloshinskii-Moriya (DM)
interactions, and compute the optical conductivity of VBS states on both ideal
and deformed Kagome lattices. In case of the deformed Kagome lattice, we study
the antiferromagnet, Rb$_2$Cu$_3$SnF$_{12}$ with the pinwheel VBS state. In
case of the ideal Kagome lattice, we explore the optical conductivity
signatures of the spin-triplet excitations for three VBS states with (1) a
12-site unit cell, (2) a 36-site unit cell with six-fold rotation symmetry, and
(3) a 36-site unit cell with three-fold rotation symmetry, respectively. We
find that increasing the DM interactions generally leads to broad and smooth
features in the optical conductivity with interesting experimental
consequences. The optical conductivity reflects the features of the
spin-triplet excitations that can be measured in future experiments.


title:
Relativistic Self-similar Dynamic Collapses of Black Holes in General
  Polytropic Spherical Clouds

abstract:
  We study the hydrodynamic self-similar mass collapses of general polytropic
(GP) spherical clouds to central Schwarzschild black holes and void evolution
with or without shocks. In order to grossly capture characteristic effects of
general relativity (GR) outside yet close to the event horizon of a
Schwarzschild black hole and to avoid mathematical complexity, we adopt the
approximation of the Paczynski-Wiita gravity to replace the simple Newtonian
gravity in our model formulation. A new dimensionless parameter s appears with
the physical meaning of the square of the ratio of the sound speed to the speed
of light $c$. Various self-similar dynamic solutions are constructed for a
polytropic index $\gamma>4/3$. Two (for small enough $s<1$) or no (for large
enough $s<1$) expansion-wave collapse solutions (EWCSs) with central event
horizons exist when $\gamma>4/3$, representing the collapse of static singular
GP spheres towards the central singularity of spacetime. Such GP spherical
dynamic mass collapse is shown to be highly efficient for the rapid formation
of supermassive black holes (SMBHs; mass range of $10^6-10^{10}M_{\odot}$) in
the early universe or even hypermassive black holes (HMBHs; mass range of
$10^{10}-10^{12}M_{\odot}$) if extremely massive mass reservoirs could be
sustained for a sufficiently long time, which may evolve into hard X-ray/gamma
ray sources or quasars according to their surroundings. Self-similar dynamic
solutions of a GP gas are also proposed for the stellar mass black hole
formation during the violent supernova explosion of a massive progenitor star,
the timescale of which is estimated of $10^{-3}$ seconds. Rebound shocks
travelling in supernovae are also discussed based on our self-similar shock
expansion solutions.


title: Expressiveness of Visibly Pushdown Transducers

abstract:
  Visibly pushdown transducers (VPTs) are visibly pushdown automata extended
with outputs. They have been introduced to model transformations of nested
words, i.e. words with a call/return structure. As trees and more generally
hedges can be linearized into (well) nested words, VPTs are a natural formalism
to express tree transformations evaluated in streaming. This paper aims at
characterizing precisely the expressive power of VPTs with respect to other
tree transducer models.


title:
Node Query Preservation for Deterministic Linear Top-Down Tree
  Transducers

abstract:
  This paper discusses the decidability of node query preservation problems for
XML document transformations. We assume a transformation given by a
deterministic linear top-down data tree transducer (abbreviated as DLT^V) and
an n-ary query based on runs of a tree automaton. We say that a DLT^V Tr
strongly preserves a query Q if there is a query Q' such that for every
document t, the answer set of Q' for Tr(t) is equal to the answer set of Q for
t. Also we say that Tr weakly preserves Q if there is a query Q' such that for
every t_d in the range of Tr, the answer set of Q' for t_d is equal to the
union of the answer set of Q for t such that t_d = Tr(t). We show that the weak
preservation problem is coNP-complete and the strong preservation problem is in
2-EXPTIME.


title: XPath Node Selection over Grammar-Compressed Trees

abstract:
  XML document markup is highly repetitive and therefore well compressible
using grammar-based compression. Downward, navigational XPath can be executed
over grammar-compressed trees in PTIME: the query is translated into an
automaton which is executed in one pass over the grammar. This result is
well-known and has been mentioned before. Here we present precise bounds on the
time complexity of this problem, in terms of big-O notation. For a given
grammar and XPath query, we consider three different tasks: (1) to count the
number of nodes selected by the query, (2) to materialize the pre-order numbers
of the selected nodes, and (3) to serialize the subtrees at the selected nodes.


title:
Mechanism of Ultrafast Relaxation of a Photo-Carrier in
  Antiferromagnetic Spin Background

abstract:
  We study the relaxation mechanism of a highly excited carrier propagating in
the antiferromagnetic background modeled by the $t$-$J$ Hamiltonian on a square
lattice. We show that the relaxation consists of two distinct stages. The
initial ultrafast stage with the relaxation time $\tau\sim
(\hbar/t_0)(J/t_0)^{-2/3}$ (where $t_0$ is the hopping integral and $J$ is the
exchange interaction) is based on generation of string states in the close
proximity of the carrier. This unusual scaling of $\tau$ is obtained by means
of comparison of numerical results with a simplified $t$-$J_z$ model on a Bethe
lattice. In the subsequent (much slower) stage local spin excitations are
carried away by magnons. The relaxation time on the two-leg ladder system is an
order of magnitude longer due to the lack of string excitations. This further
reinforces the importance of string excitations for the ultrafast relaxation in
the two-dimensional system.


title:
PAMELA and AMS-02 positron and electron spectra are reproduced by
  three-dimensional cosmic-ray modeling

abstract:
  The PAMELA collaboration recently released the $e^+$ absolute spectrum
between 1 and 300 GeV in addition to the positron fraction and the $e^-$
spectrum previously measured in the same period. We use the newly developed
three-dimensional upgrade of the DRAGON package to model those data. This code
allows us to consider a realistic spiral arm source distribution in the Galaxy,
which impacts the high-energy shape of the propagated spectra. At low energy we
treat solar modulation with the HelioProp code and compare its results with
those obtained using the usual force-field approximation. We show that all
PAMELA data sets can be consistently, and accurately, described in terms of a
standard background on top of which a charge symmetric $e^+$ + $e^-$ extra
component with harder injection spectrum is added; this extra contribution is
peaked at about 1 - 10 TeV and may originate from a diffuse population of
sources located in the Galactic arms. For the first time, we compute the energy
required to sustain such a relevant positron flux in the Galaxy, finding that
it is naturally compatible with an astrophysical origin. We considered several
reference propagation setups; we find that models with a low (or null)
reacceleration - tuned against light nuclei data - nicely describe both PAMELA
leptonic and hadronic data with no need to introduce a low-energy break in the
proton and helium spectra, as it would be required for high reacceleration
models. We also compare our models with the preliminary $e^-$ and $e^+$
absolute spectra recently measured by AMS-02. We find that those data,
differently from what is inferred from the positron fraction alone, favor a
high energy cutoff (about 10 TeV) of the extra component if this is uniquely
generated in the Galactic arms. A lower cutoff may be allowed if a relevant
contribution from powerful $e^-$ + $e^+$ nearby accelerators is invoked.


title:
Bayesian quantum frequency estimation in presence of collective
  dephasing

abstract:
  We advocate a Bayesian approach to optimal quantum frequency estimation - an
important issue for future quantum enhanced atomic clock operation. The
approach provides a clear insight into the interplay between decoherence and
the extent of the prior knowledge in determining the optimal interrogation
times and optimal estimation strategies. We propose a general framework capable
of describing local oscillator noise as well as additional collective atomic
dephasing effects. For a Gaussian noise the average Bayesian cost can be
expressed using the quantum Fisher information and thus we establish a direct
link between the two, often competing, approaches to quantum estimation theory


title: Effects of Fluid Velocity Gradients on Heavy Quark Energy Loss

abstract:
  We use holographic duality to analyze the drag force on, and consequent
energy loss of, a heavy quark moving through a strongly coupled conformal fluid
with non-vanishing gradients in its velocity and temperature. We derive the
general expression for the drag force to first order in the fluid gradients.
Using this general expression, we show that a quark that is instantaneously at
rest, relative to the fluid, in a fluid whose velocity is changing with time
feels a nonzero force. And, we show that for a quark that is moving
ultra-relativistically, the first order gradient "corrections" become larger
than the zeroth order drag force, suggesting that the gradient expansion may be
unreliable in this regime. We illustrate the importance of the fluid gradients
for heavy quark energy loss by considering a fluid with one-dimensional boost
invariant Bjorken expansion as well as the strongly coupled plasma created by
colliding sheets of energy.


title:
The proportion of plane cubic curves over ${\mathbb Q}$ that everywhere
  locally have a point

abstract:
  We show that the proportion of plane cubic curves over ${\mathbb Q}_p$ that
have a ${\mathbb Q}_p$-rational point is a rational function in $p$, where the
rational function is independent of $p$, and we determine this rational
function explicitly. As a consequence, we obtain the density of plane cubic
curves over ${\mathbb Q}$ that have points everywhere locally; numerically,
this density is shown to be $\approx 97.3\%$.


title:
Monte Carlo studies on the expanding behavior of the early universe in
  the Lorentzian type IIB matrix model

abstract:
  The type IIB matrix model is a conjectured nonperturbative formulation of
superstring theory. Recently the Lorentzian version of the model has been
studied by Monte Carlo simulation, and it has been shown that only three out of
nine spatial directions start to expand after a critical time. We extend this
work by investigating the expanding behavior for much longer time. We find that
the 3d space expands exponentially for some period of time, which may be
interpreted as inflation. We also simulate a simplified model, which is
expected to capture some qualitative features of the original model at much
later times. We observe that the exponential expansion eventually changes into
a power-law t^(1/2) behavior, which agrees with the expanding behavior of the
Friedmann-Robertson-Walker (FRW) universe in the radiation dominated era.


title:
Quenched disorder and vestigial nematicity in the pseudo-gap regime of
  the cuprates

abstract:
  We have carried out a theoretical analysis of the Landau-Ginzburg-Wilson
effective field theory of a classical incommensurate CDW in the presence of
weak quenched disorder. While the possibility a sharp phase transition and
long-range CDW order are precluded in such systems, we show that any discrete
symmetry breaking aspect of the charge order -- nematicity in the case of the
unidirectional (stripe) CDW we consider explicitly -- generically survives up
to a non-zero critical disorder strength. Such "vestigial order", which is
subject to unambiguous macroscopic detection, can serve as an avatar of what
would be CDW order in the ideal, zero disorder limit. Various recent
experiments in the pseudo-gap regime of the hole-doped cuprate high-temperature
superconductors are readily interpreted in light of these results.


title:
The First Pulse of the Extremely Bright GRB 130427A: A Test Lab for
  Synchrotron Shocks

abstract:
  Gamma-ray burst (GRB) 130427A is one of the most energetic GRBs ever
observed. The initial pulse up to 2.5 s is possibly the brightest well-isolated
pulse observed to date. A fine time resolution spectral analysis shows
power-law decays of the peak energy from the onset of the pulse, consistent
with models of internal synchrotron shock pulses. However, a strongly
correlated power-law behavior is observed between the luminosity and the
spectral peak energy that is inconsistent with curvature effects arising in the
relativistic outflow. It is difficult for any of the existing models to account
for all of the observed spectral and temporal behaviors simultaneously.


title:
Parallel Tempering Simulation of the three-dimensional Edwards-Anderson
  Model with Compact Asynchronous Multispin Coding on GPU

abstract:
  Monte Carlo simulations of the Ising model play an important role in the
field of computational statistical physics, and they have revealed many
properties of the model over the past few decades. However, the effect of
frustration due to random disorder, in particular the possible spin glass
phase, remains a crucial but poorly understood problem. One of the obstacles in
the Monte Carlo simulation of random frustrated systems is their long
relaxation time making an efficient parallel implementation on state-of-the-art
computation platforms highly desirable. The Graphics Processing Unit (GPU) is
such a platform that provides an opportunity to significantly enhance the
computational performance and thus gain new insight into this problem. In this
paper, we present optimization and tuning approaches for the CUDA
implementation of the spin glass simulation on GPUs. We discuss the integration
of various design alternatives, such as GPU kernel construction with minimal
communication, memory tiling, and look-up tables. We present a binary data
format, Compact Asynchronous Multispin Coding (CAMSC), which provides an
additional $28.4\%$ speedup compared with the traditionally used Asynchronous
Multispin Coding (AMSC). Our overall design sustains a performance of 33.5
picoseconds per spin flip attempt for simulating the three-dimensional
Edwards-Anderson model with parallel tempering, which significantly improves
the performance over existing GPU implementations.


title: NSMAXG: A new magnetic neutron star spectral model in XSPEC

abstract:
  The excellent sensitivity of X-ray telescopes, such as Chandra and
XMM-Newton, is ideal for the study of cooling neutron stars, which can emit at
these energies. In order to exploit the wealth of information contained in the
high quality data, a thorough knowledge of the radiative properties of neutron
star atmospheres is necessary. A key factor affecting photon emission is
magnetic fields, and neutron stars are known to have strong surface magnetic
fields. Here I briefly describe our latest work on constructing magnetic (B >=
10^10 G) atmosphere models of neutron stars and the NSMAXG implementation of
these models in XSPEC. Our results allow for more robust extractions of neutron
star parameters from observations.


title:
On the analysis of a coupled kinetic-fluid model with local alignment
  forces

abstract:
  This paper studies global existence, hydrodynamic limit, and large-time
behavior of weak solutions to a kinetic flocking model coupled to the
incompressible Navier-Stokes equations. The model describes the motion of
particles immersed in a Navier-Stokes fluid interacting through local
alignment. We first prove the existence of weak solutions using energy and
$L^p$ estimates together with the velocity averaging lemma. We also rigorously
establish a hydrodynamic limit corresponding to strong noise and local
alignment. In this limit, the dynamics can be totally described by a coupled
compressible Euler - incompressible Navier-Stokes system. The proof is via
relative entropy techniques. Finally, we show a conditional result on the
large-time behavior of classical solutions. Specifically, if the mass-density
satisfies a uniform in time integrability estimate, then particles align with
the fluid velocity exponentially fast without any further assumption on the
viscosity of the fluid.


title: On the $N_f$-dependence of gluonic observables

abstract:
  We compute $t_0$, $w_0$ and the topological susceptibility, defined at finite
gradient flow time for two-flavour QCD. The use of three lattice spacings and
pion masses between 192 and 500 MeV together with a careful error analysis
allow to approach the continuum limit of the two-flavour theory despite
significant auto-correlations. A comparison to $N_f=0$ results shows the size
of sea quark effects in $t_0^2\chi$, with $\chi$ the topological
susceptibility, and low energy observables such as $t_0/w_0^2$ and $t_0/r_0^2$.


title:
Active Galactic Nuclei, Neutrinos, and Interacting Cosmic Rays in NGC
  253 & NGC 1068

abstract:
  The galaxies M82, NGC 253, NGC 1068, and NGC 4945 have been detected in
gamma-rays by Fermi. Previously, we developed and tested a model for cosmic ray
interactions in the starburst galaxy M82. Now, we aim to explore the
differences between starburst and active galactic nuclei (AGN) environments by
applying our self-consistent model to the starburst galaxy NGC 253 and the
Seyfert galaxy NGC 1068. Assuming constant cosmic-ray acceleration efficiency
by supernova remnants with Milky-Way parameters, we calculate the cosmic-ray
proton and primary and secondary electron/positron populations, predict the
radio and gamma-ray spectra, and compare with published measurements. We find
that our models easily fits the observed gamma-ray spectrum for NGC 253 while
constraining the cosmic ray source spectral index and acceleration efficiency.
However, we encountered difficultly modeling the observed radio data and
constraining the speed of the galactic wind and the magnetic field strength,
unless the gas mass is less than currently preferred values. Additionally, our
starburst model consistently underestimates the observed gamma-ray flux and
overestimates the radio flux for NGC 1068; these issues would be resolved if
the AGN is the primary source of gamma-rays. We discuss the implications of
these results and make predictions for the neutrino fluxes for both galaxies.


title: Dynamic Integration of ALM Tools for Agile Software Development

abstract:
  The paper describes the need for and goals of tool-integration within
software development processes. In particular we focus on agile software
development but are not limited to. The integration of tools and data between
the different domains of the process is essential for an efficient, effective
and customized software development. We describe what the next steps in the
pursuit of integration are and how major goals can be achieved. Beyond
theoretical and architectural considerations we describe the prototypical
implementation of an open platform approach. The paper introduces platform apps
and a functionality store as general concepts to make apps and their
functionalities available to the community. We describe the implementation of
the approach and how it can be practically utilized. The description is based
on one major use case and further steps are motivated by various other
examples.


title: The Dust Scattering Halo of Cygnus X-3

abstract:
  Dust grains scatter X-ray light through small angles, producing a diffuse
halo image around bright X-ray point sources situated behind a large amount of
interstellar material. We present analytic solutions to the integral for the
dust scattering intensity, which allow for a Bayesian analysis of the
scattering halo around Cygnus X-3. Fitting the optically thin 4-6 keV halo
surface brightness profile yields the dust grain size and spatial distribution.
We assume a power law distribution of grain sizes ($n \propto a^{-p}$) and fit
for $p$, the grain radius cut-off amax, and dust mass column. We find that a $p
\approx 3.5$ dust grain size distribution with amax $\approx 0.2$ um fits the
halo profile relatively well, whether the dust is distributed uniformly along
the line of sight or in clumps. We find that a model consisting of two dust
screens, representative of foreground spiral arms, requires the foreground
Perseus arm to contain 80\% of the total dust mass. The remaining 20\% of the
dust, which may be associated with the outer spiral arm of the Milky Way, is
located within 1 kpc of Cyg X-3. Regardless of which model was used, we found
$\tau_{\rm sca} \sim 2 \ E_{\rm keV}^{-2}$. We examine the energy resolved
halos of Cyg X-3 from 1 - 6 keV and find that there is a sharp drop in
scattering halo intensity when $E < 2-3$ keV, which cannot be explained with
multiple scattering effects. We hypothesize that this may be caused by large
dust grains or material with unique dielectric properties, causing the
scattering cross-section to depart from the Rayleigh-Gans approximation that is
used most often in X-ray scattering studies. The foreground Cyg OB2
association, which contains several evolved stars with large extinction values,
is a likely culprit for grains of unique size or composition.


title:
Transmission electron microscopy and ferromagnetic resonance
  investigations of tunnel magnetic junctions using Co2MnGe Heusler alloy as
  magnetic electrodes

abstract:
  HRTEM, nano-beam electronic diffraction, energy dispersive X-rays scanning
spectroscopy, Vibrating Sample Magnetometry (VSM) and FerroMagnetic Resonance
(FMR) techniques are used in view of comparing (static and dynamic) magnetic
and structural properties of Co2MnGe (13 nm)/Al2O3 (3 nm)/Co (13 nm) tunnel
magnetic junctions (TMJ), deposited on various single crystalline substrates
(a-plane sapphire, MgO(100) and Si(111)). They allow for providing a
correlation between these magnetic properties and the fine structure
investigated at atomic scale. The Al2O3 tunnel barrier is always amorphous and
contains a large concentration of Co atoms, which, however, is significantly
reduced when using a sapphire substrate. The Co layer is polycrystalline and
shows larger grains for films grown on a sapphire substrate. The VSM
investigation reveals in-plane anisotropy only for samples grown on a sapphire
substrate. The FMR spectra of the TMJs are compared to the obtained ones with a
single Co and Co2MnGe films of identical thickness deposited on a sapphire
substrate. As expected, two distinct modes are detected in the TMJs while only
one mode is observed in each single film. For the TMJ grown on a sapphire
substrate the FMR behavior does not significantly differ from the superposition
of the individual spectra of the single films, allowing for concluding that the
exchange coupling between the two magnetic layers is too small to give rise to
observable shifts. For TMJs grown on a Si or on a MgO substrate the resonance
spectra reveal one mode which is nearly identical to the obtained one in the
single Co film, while the other observed resonance shows a considerably smaller
intensity and cannot be described using the magnetic parameters appropriate to
the single Co2MnGe film.


title: Adaptive Learning of Region-based pLSA Model for Total Scene Annotation

abstract:
  In this paper, we present a region-based pLSA model to accomplish the task of
total scene annotation. To be more specific, we not only properly generate a
list of tags for each image, but also localizing each region with its
corresponding tag. We integrate advantages of different existing region-based
works: employ efficient and powerful JSEG algorithm for segmentation so that
each region can easily express meaningful object information; the introduction
of pLSA model can help better capturing semantic information behind the
low-level features. Moreover, we also propose an adaptive padding mechanism to
automatically choose the optimal padding strategy for each region, which
directly increases the overall system performance. Finally we conduct 3
experiments to verify our ideas on Corel database and demonstrate the
effectiveness and accuracy of our system.


title: PANDA: Pose Aligned Networks for Deep Attribute Modeling

abstract:
  We propose a method for inferring human attributes (such as gender, hair
style, clothes style, expression, action) from images of people under large
variation of viewpoint, pose, appearance, articulation and occlusion.
Convolutional Neural Nets (CNN) have been shown to perform very well on large
scale object recognition problems. In the context of attribute classification,
however, the signal is often subtle and it may cover only a small part of the
image, while the image is dominated by the effects of pose and viewpoint.
Discounting for pose variation would require training on very large labeled
datasets which are not presently available. Part-based models, such as poselets
and DPM have been shown to perform well for this problem but they are limited
by shallow low-level features. We propose a new method which combines
part-based models and deep learning by training pose-normalized CNNs. We show
substantial improvement vs. state-of-the-art methods on challenging attribute
classification tasks in unconstrained settings. Experiments confirm that our
method outperforms both the best part-based methods on this problem and
conventional CNNs trained on the full bounding box of the person.


title: On multiple peaks and moderate deviations for supremum of Gaussian field

abstract:
  We prove two theorems concerning extreme values of general Gaussian fields.
Our first theorem concerns with the concept of multiple peaks. A theorem of
Chatterjee states that when a centered Gaussian field admits the so-called
superconcentration property, it typically attains values near its maximum on
multiple near-orthogonal sites, known as multiple peaks. We improve his theorem
in two aspects: (i) the number of peaks attained by our bound is of the order
$\exp(c / \sigma^2)$ (as opposed to Chatterjee's polynomial bound in
$1/\sigma$), where $\sigma$ is the standard deviation of the supremum of the
Gaussian field, which is assumed to have variance at most $1$ and (ii) our
bound need not assume that the correlations are non-negative. We also prove a
similar result based on the superconcentration of the free energy. As primary
applications, we infer that for the S-K spin glass model on the $n$-hypercube
and directed polymers on $\mathbb{Z}_n^2$, there are polynomially (in $n$) many
near-orthogonal sites that achieve values near their respective maxima.
  Our second theorem gives an upper bound on moderate deviation for the
supremum of a general Gaussian field. While the Gaussian isoperimetric
inequality implies a sub-Gaussian concentration bound for the supremum, we show
that the exponent in that bound can be improved under the assumption that the
expectation of the supremum is of the same order as that of the independent
case.


title:
Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the
  Sgr A complex

abstract:
  We observed OH, H$_2$O, HN$_3$, C$^{18}$O, and C$_I$ towards the +50 km/s
cloud (M-0.02-0.07), the CND and the +20 km/s (M-0.13-0.08) cloud in the Sgr A
complex with the VLA, Odin and SEST. Strong OH absorption, H$_2$O emission and
absorption lines were seen at all three positions. Strong C$^{18}$O emissions
were seen towards the +50 and +20 km/s clouds. The CND is rich in H$_2$O and
OH, and these abundances are considerably higher than in the surrounding
clouds, indicating that shocks, star formation and clump collisions prevail in
those objects. A comparison with the literature reveals that it is likely that
PDR chemistry including grain surface reactions, and perhaps also the
influences of shocks has led to the observed abundances of the observed
molecular species studied here. In the redward high-velocity line wings of both
the +50 and +20 km/s clouds and the CND, the very high H$_2$O abundances are
suggested to be caused by the combined action of shock desorption from icy
grain mantles and high-temperature, gas-phase shock chemistry. Only three of
the molecules are briefly discussed here. For OH and H$_2$O three of the nine
observed positions are shown, while a map of the C$^{18}$O emission is
provided. An extensive paper was recently published with Open Access (Karlsson
et al. 2013; http://www.aanda.org/articles/aa/pdf/2013/06/aa20471-12.pdf ).


title:
The virialization density of peaks with general density profiles under
  spherical collapse

abstract:
  We calculate the non-linear virialization density, $\Delta_c$, of halos under
spherical collapse from peaks with an arbitrary initial and final density
profile. This is in contrast to the standard calculation of $\Delta_c$ which
assumes top-hat profiles. Given our formalism, the non-linear halo density can
be calculated once the shape of the initial peak's density profile and the
shape of the virialized halo's profile are provided. We solve for $\Delta_c$
for halos in an Einstein de-Sitter and $\Lambda$CDM universe. As examples, we
consider power-law initial profiles as well as spherically averaged peak
profiles calculated from the statistics of a Gaussian random field.
  We find that, depending on the profiles used, $\Delta_c$ is smaller by a
factor of a few to as much as a factor of 10 as compared to the density given
by the standard calculation ($\approx 200$). Using our results, we show that,
for halo finding algorithms that identify halos through an over-density
threshold, the halo mass function measured from cosmological simulations can be
enhanced at all halo masses by a factor of a few. This difference could be
important when using numerical simulations to assess the validity of analytic
models of the halo mass function.


title: On Nonrigid Shape Similarity and Correspondence

abstract:
  An important operation in geometry processing is finding the correspondences
between pairs of shapes. The Gromov-Hausdorff distance, a measure of
dissimilarity between metric spaces, has been found to be highly useful for
nonrigid shape comparison. Here, we explore the applicability of related shape
similarity measures to the problem of shape correspondence, adopting spectral
type distances. We propose to evaluate the spectral kernel distance, the
spectral embedding distance and the novel spectral quasi-conformal distance,
comparing the manifolds from different viewpoints. By matching the shapes in
the spectral domain, important attributes of surface structure are being
aligned. For the purpose of testing our ideas, we introduce a fully automatic
framework for finding intrinsic correspondence between two shapes. The proposed
method achieves state-of-the-art results on the Princeton isometric shape
matching protocol applied, as usual, to the TOSCA and SCAPE benchmarks.


title:
Shock Reflection-Diffraction, von Neumann's Conjectures and Nonlinear
  Equations of Mixed Type

abstract:
  Shock waves are fundamental in nature. One of the most fundamental problems
in fluid mechanics is shock reflection-diffraction by wedges. The complexity of
reflection-diffraction configurations was first reported by Ernst Mach in 1878.
The problems remained dormant until the 1940s when John von Neumann, as well as
other mathematical/experimental scientists, began extensive research into all
aspects of shock reflection-diffraction phenomena. In this paper we start with
shock reflection-diffraction phenomena and historic perspectives, their
fundamental scientific issues and theoretical roles in the mathematical theory
of hyperbolic systems of conservation laws. Then we present how the global
shock reflection-diffraction problem can be formulated as a boundary value
problem in an unbounded domain for nonlinear conservation laws of mixed
hyperbolic-elliptic type, and describe the von Neumann conjectures: the sonic
conjecture and the detachment conjecture. Finally we discuss some recent
developments in solving the von Neumann conjectures and establishing a
mathematical theory of shock reflection-diffraction, including the existence,
regularity, and stability of global regular configurations of shock
reflection-diffraction by wedges.


title: Large-volume results in SU(2) with adjoint fermions

abstract:
  Taming finite-volume effects is a crucial ingredient in order to identify the
existence of IR fixed points. We present the latest results from our numerical
simulations of SU(2) gauge theory with 2 Dirac fermions in the adjoint
representation on large volumes. We compare with previous results, and
extrapolate to thermodynamic limit when possible.


title: The Glauber-Sudarshan and Kirkwood-Rihaczec functions

abstract:
  It is shown how to write the Kirkwood-Rihaczec quasiprobability distribution
as an expectation value of the vacuum state. We do this, by writing the
position eigenstates as a "displacment" of the vacumm. We also give a relation
between the Glauber-Sudarshan and Kirkwood-Rihaczec quasiprobability
distributions.


title:
Compressive Measurement Designs for Estimating Structured Signals in
  Structured Clutter: A Bayesian Experimental Design Approach

abstract:
  This work considers an estimation task in compressive sensing, where the goal
is to estimate an unknown signal from compressive measurements that are
corrupted by additive pre-measurement noise (interference, or clutter) as well
as post-measurement noise, in the specific setting where some (perhaps limited)
prior knowledge on the signal, interference, and noise is available. The
specific aim here is to devise a strategy for incorporating this prior
information into the design of an appropriate compressive measurement strategy.
Here, the prior information is interpreted as statistics of a prior
distribution on the relevant quantities, and an approach based on Bayesian
Experimental Design is proposed. Experimental results on synthetic data
demonstrate that the proposed approach outperforms traditional random
compressive measurement designs, which are agnostic to the prior information,
as well as several other knowledge-enhanced sensing matrix designs based on
more heuristic notions.


title: Model for the Atomic Dielectric Response in Time Dependent Laser Fields

abstract:
  A nonlocal quantum model is presented for calculating the atomic dielectric
response to a strong laser electric field. By replacing the Coulomb potential
with a nonlocal potential in the Schrodinger equation, a 3+1D calculation of
the time-dependent electric dipole moment can be replaced with a 0+1D integral
equation, offering significant computational savings. The model is benchmarked
against an established ionization model and \textit{ab initio} simulation of
the time-dependent Schrodinger equation. The reduced computational overhead
makes the model a promising candidate to incorporate full quantum mechanical
time dynamics in laser pulse propagation simulations.

categories: physics.atom-ph physics.optics physics.plasm-ph quant-ph


title:
Cu(Ir$_{1-x}$Cr$_x$)$_2$S$_4$: a model system for studying nanoscale
  phase coexistence at the metal-insulator transition

abstract:
  Increasingly, nanoscale phase coexistence and hidden broken symmetry states
are being found in the vicinity of metal-insulator transitions (MIT), for
example, in high temperature superconductors, heavy fermion and colossal
magnetoresistive materials, but their importance and possible role in the MIT
and related emergent behaviors is not understood. Despite their ubiquity, they
are hard to study because they produce weak diffuse signals in most
measurements. Here we propose Cu(Ir$_{1-x}$Cr$_x$)$_2$S$_4$ as a model system,
where robust local structural signals lead to key new insights. We demonstrate
a hitherto unobserved coexistence of a Ir$^{4+}$ charge-localized dimer phase
and Cr-ferromagnetism. The resulting phase diagram that takes into account the
short range dimer order, is highly reminiscent of a generic MIT phase diagram
similar to the cuprates. We suggest that the presence of quenched strain from
dopant ions acts as an arbiter deciding between the competing ground states.


title: General entropy-like uncertainty relations in finite dimensions

abstract:
  We revisit entropic formulations of the uncertainty principle for an
arbitrary pair of positive operator-valued measures (POVM) $A$ and $B$, acting
on finite dimensional Hilbert space. Salicr\'u generalized
$(h,\phi)$-entropies, including R\'enyi and Tsallis ones among others, are used
as uncertainty measures associated with the distribution probabilities
corresponding to the outcomes of the observables. We obtain a nontrivial lower
bound for the sum of generalized entropies for any pair of entropic
functionals, which is valid for both pure and mixed states. The bound depends
on the overlap triplet $(c_A,c_B,c_{A,B})$ with $c_A$ (resp. $c_B$) being the
overlap between the elements of the POVM $A$ (resp. $B$) and $c_{A,B}$ the
overlap between the pair of POVM. Our approach is inspired by that of de
Vicente and S\'anchez-Ruiz [Phys.\ Rev.\ A \textbf{77}, 042110 (2008)] and
consists in a minimization of the entropy sum subject to the Landau-Pollak
inequality that links the maximum probabilities of both observables. We solve
the constrained optimization problem in a geometrical way and furthermore, when
dealing with R\'enyi or Tsallis entropic formulations of the uncertainty
principle, we overcome the H\"older conjugacy constraint imposed on the
entropic indices by the Riesz-Thorin theorem. In the case of nondegenerate
observables, we show that for given $c_{A,B} > \frac{1}{\sqrt2}$, the bound
obtained is optimal; and that, for R\'enyi entropies, our bound improves
Deutsch one, but Maassen-Uffink bound prevails when $c_{A,B} \leq\frac12$.
Finally, we illustrate by comparing our bound with known previous results in
particular cases of R\'enyi and Tsallis entropies.


title: Submodular Welfare Maximization

abstract:
  An overview of different variants of the submodular welfare maximization
problem in combinatorial auctions. In particular, I studied the existing
algorithmic and game theoretic results for submodular welfare maximization
problem and its applications in other areas such as social networks.


title:
Estimation of Extreme Quantiles for Functions of Dependent Random
  Variables

abstract:
  We propose a new method for estimating the extreme quantiles for a function
of several dependent random variables. In contrast to the conventional approach
based on extreme value theory, we do not impose the condition that the tail of
the underlying distribution admits an approximate parametric form, and,
furthermore, our estimation makes use of the full observed data. The proposed
method is semiparametric as no parametric forms are assumed on all the marginal
distributions. But we select appropriate bivariate copulas to model the joint
dependence structure by taking the advantage of the recent development in
constructing large dimensional vine copulas. Consequently a sample quantile
resulted from a large bootstrap sample drawn from the fitted joint distribution
is taken as the estimator for the extreme quantile. This estimator is proved to
be consistent. The reliable and robust performance of the proposed method is
further illustrated by simulation.


title:
Observing interferences between past and future quantum states in
  resonance fluorescence

abstract:
  In quantum physics, measurement results are random but their statistics can
be predicted assuming some knowledge about the system in the past. Additional
knowledge from a future measurement deeply changes the statistics in the
present and leads to purely quantum features. In particular conditioned average
outcomes of a weak measurement, so-called weak values, were shown to go beyond
the conventional range, give a way to directly measure complex quantities, and
can be used to enhance the sensitivity of quantum meters. Recently, these
concepts have been considered in the general case of open quantum systems where
decoherence occurs. Then, what are the properties of weak values for the
unavoidable measurement associated to decoherence, the one performed by the
environment? Here, we answer this question in the simplest open quantum system:
a quantum bit in presence of a relaxation channel. We continuously monitor the
fluorescence emitted by a superconducting qubit driven at resonance.
Conditioned on initial preparation and final single shot measurement outcome of
the qubit state, we probe weak values displaying all the above properties. The
fluorescence signal exhibits interferences between oscillations associated to
past and future quantum states. The measured data are in complete agreement
with theory.


title: Power Spectrum and Non-Gaussianities in Anisotropic Inflation

abstract:
  We study the planar regime of curvature perturbations for single field
inflationary models in an axially symmetric Bianchi I background. In a theory
with standard scalar field action, the power spectrum for such modes has a pole
as the planarity parameter goes to zero. We show that constraints from back
reaction lead to a strong lower bound on the planarity parameter for
high-momentum planar modes and use this bound to calculate the signal-to-noise
ratio of the anisotropic power spectrum in the CMB, which in turn places an
upper bound on the Hubble scale during inflation allowed in our model. We find
that non-Gaussianities for these planar modes are enhanced for the flattened
triangle and the squeezed triangle configurations, but show that the estimated
values of the f_NL parameters remain well below the experimental bounds from
the CMB for generic planar modes (other, more promising signatures are also
discussed). For a standard action, f_NL from the squeezed configuration turns
out to be larger compared to that from the flattened triangle configuration in
the planar regime. However, in a theory with higher derivative operators,
non-Gaussianities from the flattened triangle can become larger than the
squeezed configuration in a certain limit of the planarity parameter.


title: Holographic description of quantum black hole on a computer

abstract:
  The discovery of the fact that black holes radiate particles and eventually
evaporate led Hawking to pose the well-known information loss paradox. This
paradox caused a long and serious debate since it claims that the fundamental
laws of quantum mechanics may be violated. A possible cure appeared recently
from superstring theory, a consistent theory of quantum gravity: if the
holographic description of a quantum black hole based on the gauge/gravity
duality is correct, the information is not lost and quantum mechanics remains
valid. Here we test this gauge/gravity duality on a computer at the level of
quantum gravity for the first time. The black hole mass obtained by Monte Carlo
simulation of the dual gauge theory reproduces precisely the quantum gravity
effects in an evaporating black hole. This result opens up totally new
perspectives towards quantum gravity since one can simulate quantum black holes
through dual gauge theories.


title:
A nonlocal kinetic energy functional for an inhomogeneous
  two-dimensional Fermi gas

abstract:
  The average-density approximation is used to construct a nonlocal kinetic
energy functional for an inhomogeneous two-dimensional Fermi gas. This
functional is then used to formulate a Thomas-Fermi von Weizs\"acker-like
theory for the description of the ground state properties of the system. The
quality of the kinetic energy functional is tested by performing a fully
self-consistent calculation for an ideal, harmonically confined,
two-dimensional system. Good agreement with exact results are found, with the
number and kinetic energy densities exhibiting oscillatory structure associated
with the nonlocality of the energy functional. Most importantly, this
functional shows a marked improvement over the two-dimensional Thomas-Fermi von
Weizs\"acker theory, particularly in the vicinity of the classically forbidden
region.


title: Higher-rank instanton cohomology and the quilted Atiyah-Floer conjecture

abstract:
  Given a closed, connected, oriented 3-manifold with positive first Betti
number, one can define an instanton Floer group as well as a quilted Lagrangian
Floer group. The quilted Atiyah-Floer conjecture states that these cohomology
groups are isomorphic. We initiate a program for proving this conjecture.


title: Diffusion Parameters of Flows in Stable Multi-class Queueing Networks

abstract:
  We consider open multi-class queueing networks with general arrival
processes, general processing time sequences and Bernoulli routing. The network
is assumed to be operating under an arbitrary work-conserving scheduling policy
that makes the system stable. We study the variability of flows within the
network. Computable expressions for quantifying flow variability have
previously been discussed in the literature. However, in this paper, we shed
more light on such analysis to justify the use of these expressions in the
asymptotic analysis of network flows. Towards that end, we find a simple
diffusion limit for the inter-class flows and establish the relation to
asymptotic (co-)variance rates.


title: On the components of the gauge group for PU(r)-bundles

abstract:
  We discuss a general procedure for using characteristic classes to study the
components of the gauge group for a principal G-bundle. To illustrate this, we
work out the case where G is the projective unitary group.


title:
Tracking and Characterizing Botnets Using Automatically Generated
  Domains

abstract:
  Modern botnets rely on domain-generation algorithms (DGAs) to build resilient
command-and-control infrastructures. Recent works focus on recognizing
automatically generated domains (AGDs) from DNS traffic, which potentially
allows to identify previously unknown AGDs to hinder or disrupt botnets'
communication capabilities.
  The state-of-the-art approaches require to deploy low-level DNS sensors to
access data whose collection poses practical and privacy issues, making their
adoption problematic. We propose a mechanism that overcomes the above
limitations by analyzing DNS traffic data through a combination of linguistic
and IP-based features of suspicious domains. In this way, we are able to
identify AGD names, characterize their DGAs and isolate logical groups of
domains that represent the respective botnets. Moreover, our system enriches
these groups with new, previously unknown AGD names, and produce novel
knowledge about the evolving behavior of each tracked botnet.
  We used our system in real-world settings, to help researchers that requested
intelligence on suspicious domains and were able to label them as belonging to
the correct botnet automatically.
  Additionally, we ran an evaluation on 1,153,516 domains, including AGDs from
both modern (e.g., Bamital) and traditional (e.g., Conficker, Torpig) botnets.
Our approach correctly isolated families of AGDs that belonged to distinct
DGAs, and set automatically generated from non-automatically generated domains
apart in 94.8 percent of the cases.


title:
Unitary S Matrices With Long-Range Correlations and the Quantum Black
  Hole

abstract:
  We propose an S matrix approach to the quantum black hole in which causality,
unitarity and their interrelation play a prominent role. Assuming the 't Hooft
S matrix ansatz for a gravitating region surrounded by an asymptotically flat
space-time we find a non-local transformation which changes the standard
causality requirement but is a symmetry of the unitarity condition of the S
matrix. This new S matrix then implies correlations between the in and out
states of the theory with the involvement of a third entity which in the case
of a quantum black hole, we argue is the horizon S matrix. Such correlations
are thus linked to preserving the unitarity of the S matrix and to the fact
that entangling unitary operators are nonlocal. The analysis is performed
within the Bogoliubov S matrix framework by considering a spacetime consisting
of causal complements with a boundary in between. No particular metric or
lagrangian dynamics need be invoked even to obtain an evolution equation for
the full S matrix. Constraints imposed by the new causality requirement and
implications for the effectiveness of field theoretical descriptions and for
complementarity are also discussed. We find that the tension between
information preservation and complementarity may be resolved provided the full
quantum gravity theory either through symmetries or fine tuning forbids the
occurrence of closed time like curves of information flow. Then, even if
causality is violated near the horizon at any intermediate stage, a standard
causal ordering may be preserved for the observer away from the horizon. In the
context of the black hole, the novelty of our formulation is that it appears
well suited to understand unitarity at any intermediate stage of black hole
evaporation. Moreover, it is applicable generally to all theories with long
range correlations including the final state projection models.


title: Geometric multigrid for an implicit-time immersed boundary method

abstract:
  The immersed boundary (IB) method is an approach to fluid-structure
interaction that uses Lagrangian variables to describe the structure and
Eulerian variables to describe the fluid. Explicit time stepping schemes for
the IB method require solvers only for Eulerian equations, for which fast
Cartesian grid solution methods are available. Such methods are relatively
straightforward to develop and are widely used in practice but often require
very small time steps to maintain stability. Implicit-time IB methods permit
the stable use of large time steps, but efficient implementations of such
methods require significantly more complex solvers that effectively treat both
Lagrangian and Eulerian variables simultaneously. Several different approaches
to solving the coupled Lagrangian-Eulerian equations have been proposed, but a
complete understanding of this problem is still emerging. This paper presents a
geometric multigrid method for an implicit-time discretization of the IB
equations. This multigrid scheme uses a generalization of box relaxation that
is shown to handle problems in which the physical stiffness of the structure is
very large. Numerical examples are provided to illustrate the effectiveness and
efficiency of the algorithms described herein. These tests show that using
multigrid as a preconditioner for a Krylov method yields improvements in both
robustness and efficiency as compared to using multigrid as a solver. They also
demonstrate that with a time step 100--1000 times larger than that permitted by
an explicit IB method, the multigrid-preconditioned implicit IB method is
approximately 50--200 times more efficient than the explicit method.


title:
Modified Friedmann Equation from Nonminimally Coupled Theories of
  Gravity

abstract:
  In this work we study how nonminimally coupled theories of gravity modify the
usual Friedmann equation, and develop two methods to treat these. The ambiguity
in the form of the Lagrangian density of a perfect fluid is emphasized, and the
impact of different dominant matter species is assessed. The Cosmological
Constant problem is also discussed.


title: The effect of confinement on the deformation of microfluidic drops

abstract:
  We study the deformation of drops squeezed between the floor and ceiling of a
microchannel and subjected to a hyperbolic flow. We observe that the maximum
deformation of drops depends on both the drop size and the rate of strain of
the external flow and can be described with power laws with exponents 2.59 +/-
0.28 and 0.91 +/- 0.05 respectively. We develop a theoretical model to describe
the deformation of squeezed drops based on the Darcy approximation for shallow
geometries and the use of complex potentials. The model describes the
steady-state deformation of the drops as a function of a non-dimensional
parameter Ca d^2, where Ca is the capillary number (proportional to the strain
rate and the drop size) and d is a confinement parameter equal to the drop size
divided by the channel height. For small deformations, the theoretical model
predicts a linear relationship between the deformation of drops and this
parameter, in good agreement with the experimental observations.


title: T-modules and Pila-Wilkie estimates

abstract:
  The $T-$modules, introduced by G. Anderson in the '80s, are the natural
analogue of abelian varieties in Function Field Arithmetic in positive
characteristic. For a special class of them we highlight that a totally similar
description of the classic Weierstrass function still holds. In particular,
torsion points correspond modulo a finite-rank lattice to rational points of
the tangent space. We present in this work an upper bound estimate of the
number of rational points of the trascendent part of the analytic set
corresponding, into the tangent space, to a nontrivial algebraic subvariety of
a $T-$module of this special class. Such an estimate, which takes the same
shape of that proved by J. Pila and J. Wilkie, represents our first step of our
strategy to prove Manin-Mumford conjecture for such special $T-$modules, based
on the ideas developped by U. Zannier and J. Pila.


title: A Generalization of Lie's Theorem

abstract:
  We prove that in a locally finite dimensional Lie algebra L, any maximal,
locally solvable subalgebra (Borel subalgebra) is the stabilizer of a maximal,
generalized flag in an integrable, faithful module over L.


title: Towards universal quantum computation through relativistic motion

abstract:
  We show how to use relativistic motion and local phase shifts to generate
continuous variable Gaussian cluster states within cavity modes. Our results
can be demonstrated experimentally using superconducting circuits where
tuneable boundary conditions correspond to mirrors moving with velocities close
to the speed of light. In particular, we propose the generation of a
quadripartite square cluster state as a first example that can be readily
implemented in the laboratory. Since cluster states are universal resources for
universal one-way quantum computation, our results pave the way for
relativistic quantum computation schemes.


title:
Solution of Extremal Problems in Bergman Spaces Using the Bergman
  Projection

abstract:
  In this paper we discuss the explicit solution of certain extremal problems
in Bergman spaces. In order to do this, we develop methods to calculate the
Bergman projections of various functions. As a special case, we deal with
canonical divisors for certain values of $p$.


title: Dissipative plasmon-solitons in multilayer graphene

abstract:
  Nonlinear properties of a multi-layer stack of graphene sheets are studied.
It is predicted that such a structure may support dissipative plasmon-solitons
generated and supported by an external laser radiation. Novel nonlinear
equations describing spatial dynamics of the nonlinear plasmons driven by a
plane wave in the Otto configuration are derived and the existence of single
and multi-hump dissipative solitons in the graphene structure is predicted.


title: Improved Extractors for Affine Lines

abstract:
  Let $F$ be the field of $q$ elements.
  We investigate the following Ramsey coloring problem for vector spaces: Given
a vector space $\F^n$, give a coloring of the points of $F^n$ with two colors
such that no affine line (i.e., affine subspace of dimension $1$) is
monochromatic. Our main result is as follows:
  For any $q\geq 25\cdot n$ and $n>4$, we give an explicit coloring $D:F^n\ar
\set{0,1}$ such that for every affine line $l\subseteq F^n$, $D(l)=\set{0,1}$.
Previously this was known only for $q\geq c\cdot n^2$ for some constant $c$
\cite{GR05}. We note that this beats the random coloring for which the expected
number of monochromatic lines will be 0 only when $q\geq c\cdot n\log n$ for
some constant $c$. Furthermore, our coloring will be `almost balanced' on every
affine line. Let us state this formally in the lanuage of \emph{extractors}. We
say that a function $D:F^n\mapsto \set{0,1}$ is a \afsext{1}{\eps} if for every
affine line $l\subseteq \F^n$, $D(X)$ is $\eps$-close to uniform when $X$ is
uniformly distributed over $l$. We construct a \afsext{1}{\eps} with $\eps =
\Omega(\sqrt{n/q})$ whenever $q\geq c\cdot n$ for some constant $c$.
  The previous result of \cite{GR05} gave a \afsext{1}{\eps} only for
$q=\Omega(n^2)$.


title: Fermi-LAT Observations of the Gamma-ray Burst GRB 130427A

abstract:
  The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by
the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide
constraints on the nature of such unique astrophysical sources. GRB 130427A had
the largest fluence, highest-energy photon (95 GeV), longest $\gamma$-ray
duration (20 hours), and one of the largest isotropic energy releases ever
observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge
the widely accepted model that the non-thermal high-energy emission in the
afterglow phase of GRBs is synchrotron emission radiated by electrons
accelerated at an external shock.


title: Critical superconductors

abstract:
  Bogomolnyi critical point, originally introduced in string theories, is
fundamental to superconductivity. At the critical temperature T_c it marks the
sharp border between ideally diamagnetic bulk type-I superconductors and
type-II ones that can host vortices, while itself it harbors infinitely
degenerate distributions of magnetic flux in the superconducting state. Here we
show that below T_c the physics of the Bogomolnyi critical point projects onto
a wider range of microscopic parameters, even extremely wide for multiband
superconductors. In this critical range, the degeneracy of the superconducting
state at Tc is lifted into a sequence of novel topological equilibria and the
customary understanding of superconducting phenomena does not suffice. As a
radical departure from traditional views, we introduce the paradigm of critical
superconductors, discuss their distinct magnetic properties, advocate their
subdivision in terms of possible intermediate states, and demonstrate direct
relevance of this paradigm to superconducting materials of prime interest
today.


title:
Regularization after retention in ultrahigh dimensional linear
  regression models

abstract:
  In ultrahigh dimensional setting, independence screening has been both
theoretically and empirically proved a useful variable selection framework with
low computation cost. In this work, we propose a two-step framework by using
marginal information in a different perspective from independence screening. In
particular, we retain significant variables rather than screening out
irrelevant ones. The new method is shown to be model selection consistent in
the ultrahigh dimensional linear regression model. To improve the finite sample
performance, we then introduce a three-step version and characterize its
asymptotic behavior. Simulations and real data analysis show advantages of our
method over independence screening and its iterative variants in certain
regimes.


title:
Determination of the representations and a basis for the
  Yokonuma-Temperley-Lieb algebra

abstract:
  We determine the representations of the Yokonuma-Temperley-Lieb algebra,
which is defined as a quotient of the Yokonuma-Hecke algebra by generalising
the construction of the classical Temperley-Lieb algebra. We then deduce the
dimension of this algebra, and produce an explicit basis for it.


title:
Optical Soliton Propagation in a Free-Standing Nonlinear Graphene
  Monolayer with Defects

abstract:
  Recently, optical soliton propagation in an intrinsic nonlinear graphene
monolayer configuration has been discovered. However, optical soliton behavior
in a free-standing graphene monolayer with defects has not yet been studied.
The objective of this article is to employ the generalized finite- difference
time-domain (G-FDTD) method to efficiently simulate bright optical solitons,
illustrating propagation of the electric field distribution in a free-standing
nonlinear layer with variation in nonlinearity along its width. These
variations of nonlinearity along the width represent graphene impurities, or
defects. Results show that solitons propagate effectively even in the presence
of strong spatial variations in the nonlinearity, implying the robustness of
the medium with respect to optical propagation.


title:
Recurrence in resonant transmission of one-dimensional array of delta
  potentials

abstract:
  The resonant transmission of a moving particle which interacts with an
one-dimensional array of N delta-function potentials is investigated. A
suitable transfer matrix formulation is used to obtain the particle
transmission. We give the parameters for perfect tunnelling and the
transcendental equation for the quasi-bound state energies for N = 2, 3 and 4.
Conditions for perfect tunnelling and resonant transmission are discussed for
arrays with arbitrary N. A model to explain how the tunnelling energy filter
works in these systems is proposed here.


title:
Outage Minimization via Power Adaptation and Allocation for Truncated
  Hybrid ARQ

abstract:
  In this work, we analyze hybrid ARQ (HARQ) protocols over the independent
block fading channel. We assume that the transmitter is unaware of the channel
state information (CSI) but has a knowledge about the channel statistics. We
consider two scenarios with respect to the feedback received by the
transmitter: i) ''conventional'', one-bit feedback about the decoding
success/failure (ACK/NACK), and ii) the multi-bit feedback scheme when, on top
of ACK/NACK, the receiver provides additional information about the state of
the decoder to the transmitter. In both cases, the feedback is used to allocate
(in the case of one-bit feedback) or adapt (in the case of multi-bit feedback)
the power across the HARQ transmission attempts. The objective in both cases is
the minimization of the outage probability under long-term average and peak
power constraints. We cast the problems into the dynamic programming (DP)
framework and solve them for Nakagami-m fading channels. A simplified solution
for the high signal-to-noise ratio (SNR) regime is presented using a geometric
programming (GP) approach. The obtained results quantify the advantage of the
multi-bit feedback over the conventional approach, and show that the power
optimization can provide significant gains over conventional power-constant
HARQ transmissions even in the presence of peak-power constraints.


title: Anapole Dark Matter at the LHC

abstract:
  The anapole moment is the only allowed electromagnetic moment for Majorana
fermions. Fermionic dark matter acquiring an anapole can have a standard
thermal history and be consistent with current direct detection experiments. In
this paper, we calculate the collider monojet signatures of anapole dark matter
and show that the current LHC results exclude anapole dark matter with mass
less than 100 GeV, for an anapole coupling that leads to the correct thermal
relic abundance.


title: Geometric phases between biorthogonal states

abstract:
  We investigate the evolution of a state which is dominated by a
finite-dimensional non-Hermitian time-dependent Hamiltonian operator with a
nondegenerate spectrum by using a biorthonormal approach. The geometric phase
between any two states, biorthogonal or not, are generally derived by employing
the generalized interference method. The counterpart of Manini-Pistolesi
non-diagonal geometric phase in the non-Hermitian setting is taken as a typical
example.


title: Entropy and Graphs

abstract:
  The entropy of a graph is a functional depending both on the graph itself and
on a probability distribution on its vertex set. This graph functional
originated from the problem of source coding in information theory and was
introduced by J. K\"{o}rner in 1973. Although the notion of graph entropy has
its roots in information theory, it was proved to be closely related to some
classical and frequently studied graph theoretic concepts. For example, it
provides an equivalent definition for a graph to be perfect and it can also be
applied to obtain lower bounds in graph covering problems.
  In this thesis, we review and investigate three equivalent definitions of
graph entropy and its basic properties. Minimum entropy colouring of a graph
was proposed by N. Alon in 1996. We study minimum entropy colouring and its
relation to graph entropy. We also discuss the relationship between the entropy
and the fractional chromatic number of a graph which was already established in
the literature.
  A graph $G$ is called \emph{symmetric with respect to a functional $F_G(P)$}
defined on the set of all the probability distributions on its vertex set if
the distribution $P^*$ maximizing $F_G(P)$ is uniform on $V(G)$. Using the
combinatorial definition of the entropy of a graph in terms of its vertex
packing polytope and the relationship between the graph entropy and fractional
chromatic number, we prove that vertex transitive graphs are symmetric with
respect to graph entropy. Furthermore, we show that a bipartite graph is
symmetric with respect to graph entropy if and only if it has a perfect
matching. As a generalization of this result, we characterize some classes of
symmetric perfect graphs with respect to graph entropy. Finally, we prove that
the line graph of every bridgeless cubic graph is symmetric with respect to
graph entropy.


title:
Electron Cloud Density Measurements in Accelerator Beam-pipe Using
  Resonant Microwave Excitation

abstract:
  An accelerator beam can generate low energy electrons in the beam-pipe,
generally called electron cloud, that can produce instabilities in a positively
charged beam. One method of measuring the electron cloud density is by coupling
microwaves into and out of the beam-pipe and observing the response of the
microwaves to the presence of the electron cloud. In the original technique,
microwaves are transmitted through a section of beam-pipe and a change in EC
density produces a change in the phase of the transmitted signal. This paper
describes a variation on this technique in which the beam-pipe is resonantly
excited with microwaves and the electron cloud density calculated from the
change that it produces in the resonant frequency of the beam-pipe. The
resonant technique has the advantage that measurements can be localized to
sections of beam-pipe that are a meter or less in length with a greatly
improved signal to noise ratio.


title: Disconnecting strongly regular graphs

abstract:
  In this paper, we show that the minimum number of vertices whose removal
disconnects a connected strongly regular graph into non-singleton components,
equals the size of the neighborhood of an edge for many graphs. These include
blocks graphs of Steiner $2$-designs, many Latin square graphs and strongly
regular graphs whose intersection parameters are at most a quarter of their
valency.


title: Strongly incompressible curves

abstract:
  Let $G$ be a finite group. A faithful $G$-variety $X$ is called strongly
incompressible if every dominant $G$-equivariant rational map of $X$ onto
another faithful $G$-variety $Y$ is birational. We settle the problem of
existence of strongly incompressible $G$-curves for any finite group $G$ and
any base field $k$.


title: Learning Non-Linear Feature Maps

abstract:
  Feature selection plays a pivotal role in learning, particularly in areas
were parsimonious features can provide insight into the underlying process,
such as biology. Recent approaches for non-linear feature selection employing
greedy optimisation of Centred Kernel Target Alignment(KTA), while exhibiting
strong results in terms of generalisation accuracy and sparsity, can become
computationally prohibitive for high-dimensional datasets. We propose randSel,
a randomised feature selection algorithm, with attractive scaling properties.
Our theoretical analysis of randSel provides strong probabilistic guarantees
for the correct identification of relevant features. Experimental results on
real and artificial data, show that the method successfully identifies
effective features, performing better than a number of competitive approaches.


title: Shape coexistence and triaxiality in nuclei near 80Zr

abstract:
  Total-Routhian-Surface calculations have been performed to investigate the
shape evolutions of $A\sim80$ nuclei, $^{80-84}$Zr, $^{76-80}$Sr and
$^{84,86}$Mo. Shape coexistences of spherical, prolate and oblate deformations
have been found in these nuclei. Particularly for the nuclei, $^{80}$Sr and
$^{82}$Zr, the energy differences between two shape-coexisting states are less
than 220 keV. At high spins, the $g_{9/2}$ shell plays an important role for
shape evolutions. It has been found that the alignment of the $g_{9/2}$
quasi-particles drives nuclei to be triaxial.


title:
Electrical Tuning of Surface Plasmon Polariton Propagation in
  Graphene-Nanowire Hybrid Structure

abstract:
  We demonstrate a dynamic surface plasmonic modulation of graphene-nanowire
hybrid structures in visible light range, which was thought to be a tough task
for graphene based field effect transistor modulator previously. Static
modulation depth of as high as 0.07 dB/{\mu}m has been achieved experimentally.
Carefully simulation indicates the strongly focused electromagnetic field and
dramatically enhanced electric field at the interface between a silver NW and a
graphene sheet are key roles for bringing the optical response of the device to
the visible range. Furthermore, the modulation behaviors near the Dirac point
of monolayer graphene and the singularity of gap-induced bilayer graphene are
investigated.


title:
Classification of ST and Q Type MI variant using thresholding and
  neighbourhood estimation method after cross wavelet based analysis

abstract:
  This paper proposes a cross wavelet transform based method for
Electrocardiogram signal analysis where parameters are identified from wavelet
cross spectrum and wavelet cross coherence of ECG patterns. Most of the ECG
analysing systems use explicit time plane features for cardiac pattern
classification. Application of this proposed technique for classification
eliminates the need for extraction of various explicit time plane features and
hence reduces the complexity of the system. The cross-correlation is the
measure of similarity between two waveforms or two time series and the cross
examination reveals localized similarities in time and scale. Parameters
extracted from Wavelet Cross Spectrum (WCS) and Wavelet Coherence (WCOH) is
used for classification. A pathologically varying pattern in QT zone of
inferior lead III shows the presence of Inferior Myocardial Infarction (IMI).
The Cross Wavelet Transform and Wavelet Coherence is used for the cross
examination of single normal and abnormal (IMI) beats. A normal template beat
is selected as the absolute normal pattern. Computation of the WCS and WCOH of
the selected normal template and various other normal and abnormal beats
reveals the existence of variation among patterns under study. The Wavelet
cross spectrum and Wavelet coherence of various ECG patterns shows
distinguishing characteristics over two specific regions R1 and R2, where R1 is
the QRS complex location and R2 is the T wave region. Parameters are identified
for classification of Type 1 IMI (non Q type, with ST elevation and attenuated
QRS complex) and Type 2 IMI (Q type MI with deep Q and inverted T) and normal
subjects. Accuracy of the proposed classification method is obtained as 99.43%
for normal and abnormal class and 88.5% and 87.02% for Type I and Type II
respectively.


title:
An Intrinsic Characterization of Bonnet Surfaces Based on a Closed
  Differential Ideal

abstract:
  The structure equations for a surface are introduced and two required results
based on the Codazzi equations are obtained from them. Important theorems
pertaining to isometric surfaces are stated and a theorem of Bonnet is
obtained. A tranformation formula for the connection forms is developed. It is
proved that the angle of deformation must be harmonic. It is shown that the
differentials of many of the important variables generate a closed differential
ideal. This implies that a coordinate system exists in which many of the
variables satisfy particular ordinary differential equations and these results
can be used to characterize Bonnet surfaces.


title:
High order difference schemes for a time fractional differential
  equation with Neumann boundary conditions

abstract:
  Based on our recent results, in this paper, a compact finite difference
scheme is derived for a time fractional differential equation subject to the
Neumann boundary conditions. The proposed scheme is second order accurate in
time and fourth order accurate in space. In addition, a high order alternating
direction implicit (ADI) scheme is also constructed for the two-dimensional
case. Stability and convergence of the schemes are analyzed using their matrix
forms.


title: On the Configuration Spaces of Grassmannian Manifolds

abstract:
  Let $\mathcal{F}_h^i(k,n)$ be the $i$th ordered configuration space of all
distinct points $H_1,\ldots,H_h$ in the Grassmannian $Gr(k,n)$ of
$k$-dimensional subspaces of $\mc^n$, whose sum is a subspace of dimension $i$.
We prove that $\mathcal{F}_h^i(k,n)$ is (when non empty) a complex
sub\-ma\-ni\-fold of $Gr(k,n)^h$ of dimension $i(n-i)+hk(i-k)$ and its
fundamental group is trivial if $i=min(n,hk)$, $hk \neq n$ and $n>2$ and equal
to the braid group of the sphere $\mc P^1$ if $n=2$. Eventually we compute the
fundamental group in the special case of hyperplane arrangements, i.e. $k=n-1$.


title: Braid groups in complex Grassmannians

abstract:
  We describe the fundamental group and second homotopy group of ordered
$k-$point sets in $Gr(k,n)$ generating a subspace of fixed dimension.


title:
Unified dark fluid with fast transition: including entropic
  perturbations

abstract:
  In this paper, we investigate a unified dark fluid model with fast transition
and entropic perturbations. An effective sound speed is designated as an
additional free model parameter when the entropic perturbations are included,
and if the entropic perturbations are zero, the effective sound speed will
decrease to the adiabatic sound speed. In order to analyze the viability of the
unified model, we calculate the squared Jeans wave number with the entropic
perturbations. Furthermore, by using the Markov Chain Monte Carlo method, we
perform a global fitting for the unified dark fluid model from the type Ia
supernova Union 2.1, baryon acoustic oscillation and the full information of
cosmic microwave background measurement given by the WMAP 7-yr data points. The
constrained results favor a small effective sound speed. Compared to the
$\Lambda$CDM, it is found that the cosmic observations do not favor the
phenomenon of fast transition for the unified dark fluid model.


title: An Emergent World of Gauge Force and Partons

abstract:
  We illustrate how a completely new world of gauge force emerges from a
conventional condensed matter system in a rigorous way. A characteristic energy
scale (Mott gap) separates such an exotic universe from the ordinary one that
we condensed matter physicists are more familiar with at higher energies. The
governing physical law is no longer about individual electrons but concerns
fractionalized particles, i.e., partons, as the new collective modes resulted
from strong correlation among the electrons. Novel phenomena in this low-energy
universe are clearly distinguished from Landau's Fermi liquid described by the
perturbative quantum many-body theory.


title: On the Products $(1^\ell+1)(2^\ell+1)\cdots (n^\ell +1)$, II

abstract:
  In this paper, the following results are proved: (i) For any odd integer
$\ell$ with at most two distinct prime factors and any positive integer $n$,
the product $(1^\ell+1)(2^\ell+1)\cdots (n^\ell +1)$ is not a powerful number;
(ii) For any integer $r\ge 1$, there exists a positive integer $T_r$ such that,
if $\ell$ is a positive odd integer with at most $r$ distinct prime factors and
$n$ is an integer with $n\ge T_r$, then $(1^\ell+1)(2^\ell+1)\cdots (n^\ell
+1)$ is not a powerful number.


title:
High-Resolution Near Infrared Spectroscopy of HD 100546: II. Analysis of
  variable rovibrational CO emission lines

abstract:
  We present observations of rovibrational CO in HD 100546 from four epochs
spanning January 2003 through December 2010. We show that the equivalent widths
of the CO lines vary during this time period with the v=1-0 CO lines
brightening more than the UV fluoresced lines from the higher vibrational
states. While the spectroastrometric signal of the hot band lines remains
constant during this period, the spectroastrometric signal of the v=1--0 lines
varies substantially. At all epochs, the spectroastrometric signals of the UV
fluoresced lines are consistent with the signal one would expect from gas in an
axisymmetric disk. In 2003, the spectroastrometric signal of the v=1-0 P26 line
was symmetric and consistent with emission from an axisymmetric disk. However,
in 2006, there was no spatial offset of the signal detected on the red side of
the profile, and in 2010, the spectroastrometric offset was yet more strongly
reduced toward zero velocity. A model is presented that can explain the
evolution of the equivalent width of the v=1-0 P26 line and its
spectroastrometric signal by adding to the system a compact source of CO
emission that orbits the star near the inner edge of the disk. We hypothesize
that such emission may arise from a circumplanetary disk orbiting a gas giant
planet near the inner edge of the circumstellar disk. We discuss how this idea
can be tested observationally and be distinguished from an alternative
interpretation of random fluctuations in the disk emission.


title: Homological Stability For Moduli Spaces of Odd Dimensional Manifolds

abstract:
  We prove a homological stability theorem for the moduli spaces of manifolds
diffeomorphic to $\#^{g}(S^{n+1}\times S^{n})$, provided $n \geq 4$. This is an
odd dimensional analogue of a recent homological stability result of S.
Galatius and O. Randal Williams for the moduli space of manifolds diffeomorphic
to $\#^{g}(S^{n}\times S^{n})$ for $n \geq 3$.


title:
Stability and convergence analysis of the kinematically coupled scheme
  for fluid-structure interaction

abstract:
  In this work we analyze the stability and convergence properties of a
loosely-coupled scheme, called the kinematically coupled scheme, for
interaction between an incompressible viscous fluid and a thin structure. We
consider a benchmark problem where the structure is modeled using the linearly
elastic Koiter membrane model and the coupling between the fluid and structure
is linear. We derive the energy estimates associated with the unconditional
stability and, for the first time, present a priori estimates showing optimal,
first-order in time, convergence. The theoretical stability and convergence
results are supported with numerical examples.


title: A Hennings TQFT Construction for Quasi-Hopf Algebras

abstract:
  We extend the construction of the Hennings TQFT for ribbon Hopf algebras to
the case of ribbon quasi-Hopf algebras as defined by Drinfeld. Calculations
proceed in a similar fashion to the ordinary Hopf algebra case, but also
require the handling of the non-trivial coassociator in the triple tensor
product of the algebra as well as several special elements. The main technical
difficulties we encounter are representing tangle categories in the
non-associative setting, and the definition and use of integrals and
cointegrals in the non-coassociative case. We therefore discuss the integral
theory for quasi-Hopf algebras, using work of Hausser and Nill. A motivating
example for this work is the Dijkgraaf-Pasquier-Roche algebra which is believed
to be related to the Dijkgraaf-Witten TQFT.


title:
Effects of anisotropy on gravitational infall in galaxy clusters using
  an exact general relativistic model

abstract:
  We study the effects and implications of anisotropies at the scale of galaxy
clusters by building an exact general relativistic model of a cluster using the
inhomogeneous and anisotropic Szekeres metric. The model is built from a
modified Navarro-Frenk-White (NFW) density profile. We compare this to a
corresponding spherically symmetric structure in the Lemaitre-Tolman (LT) model
and quantify the impact of introducing varying levels of anisotropy. We examine
two physical measures of gravitational infall -- the growth rate of density and
the velocity of the source dust in the model. We introduce a generalization of
the LT dust velocity profile for the Szekeres metric and demonstrate its
consistency with the growth rate of density. We find that the growth rate of
density in one substructure increases by 0.5%, 1.5%, and 3.75% for 5%, 10%, and
15% levels of introduced anisotropy, which is measured as the fractional
displaced mass relative to the spherically symmetric case. The infall velocity
of the dust is found to increase by 2.5, 10, and 20 km/s (0.5%, 2%, and 4.5%),
respectively, for the same three levels of anisotropy. This response to the
anisotropy in a structure is found to be strongly nonlinear with respect to the
strength of anisotropy. These relative velocities correspond to an equivalent
increase in the total mass of the spherically symmetric structure of 1%, 3.8%,
and 8.4%, indicating that not accounting for the presence of anisotropic mass
distributions in cluster models can strongly bias the determination of physical
properties like the total mass.


title:
Interspecific Introgressive Origin of Genomic Diversity in the House
  Mouse

abstract:
  We report on a genome-wide scan for introgression in the house mouse (Mus
musculus domesticus) involving the Algerian mouse (Mus spretus), using samples
from the ranges of sympatry and allopatry in Africa and Europe. Our analysis
reveals wide variability in introgression signatures along the genomes, as well
as across the samples. We find that fewer than half of the autosomes in each
genome harbor all detectable introgression, while the X chromosome has none.
Further, European mice carry more M. spretus alleles than the sympatric African
ones. Using the length distribution and sharing patterns of introgressed
genomic tracts across the samples, we infer, first, that at least three
distinct hybridization events involving M. spretus have occurred, one of which
is ancient, and the other two are recent (one presumably due to warfarin
rodenticide selection). Second, several of the inferred introgressed tracts
contain genes that are likely to confer adaptive advantage. Third, introgressed
tracts might contain driver genes that determine the evolutionary fate of those
tracts. Further, functional analysis revealed introgressed genes that are
essential to fitness, including the Vkorc1 gene, which is implicated in
rodenticide resistance, and olfactory receptor genes. Our findings highlight
the extent and role of introgression in nature, and call for careful analysis
and interpretation of house mouse data in evolutionary and genetic studies.


title: A duality theorem for syzygies of Veronese ideals

abstract:
  We prove a duality theorem for simplicial complexes arising from a
combinatorial construction we define, which applies to the squarefree monomial
complexes for Veronese ideals of projective spaces and weighted projective
spaces. Our theorem yields a formula for the multigraded Betti numbers of these
Veronese ideals in terms of the reduced homology groups of these complexes
which is dual to one given by Bruns and Herzog. We apply this formula in
several ways, including by giving an algorithm for finding the highest syzygy
of such a Veronese ideal.


title:
Generic Continuity of Metric Entropy for Volume-preserving
  Diffeomorphisms

abstract:
  Let $M$ be a compact manifold and $\text{Diff}^1_m(M)$ be the set of $C^1$
volume-preserving diffeomorphisms of $M$. We prove that there is a residual
subset $\mathcal {R}\subset \text{Diff}^1_m(M)$ such that each $f\in
\mathcal{R}$ is a continuity point of the map $g\to h_m(g)$ from
$\text{Diff}^1_m(M)$ to $\mathbb{R}$, where $h_m(g)$ is the metric entropy of
$g$ with respect to volume measure $m$.


title: Binary distributions of concentric rings

abstract:
  We introduce families of jointly symmetric, binary distributions that are
generated over directed star graphs whose nodes represent variables and whose
edges indicate positive dependences. The families are parametrized in terms of
a single parameter. It is an outstanding feature of these distributions that
joint probabilities relate to evenly-spaced concentric rings. Kronecker product
characterizations make them computationally attractive for a large number of
variables. We study the behaviour of different measures of dependence and
derive maximum likelihood estimates when all nodes are observed and when the
inner node is hidden.