title: Universal Diffusion in Incoherent Black Holes

abstract:
  We study charge and energy diffusion in simple holographic theories with
broken translational symmetry. We find that when the effects of momentum
relaxation are very strong the diffusion constants take universal values $D_{c}
\sim D_{e} \sim \hbar v_B^2/(k_B T)$. Here $v_B$ is the velocity of the
butterfly effect and the coefficients of proportionality depend only on the
scaling exponents of the infra-red fixed point. Our results suggest that
diffusion in these incoherent black holes is controlled by $\tau \sim
{\hbar}/(k_B T)$ independently of the mechanism of momentum relaxation.


title: Enhanced Thermoelectric Power and Electronic Correlations in RuSe$_2$

abstract:
  We report the electronic structure, electric and thermal transport properties
of Ru$_{1-x}$Ir$_{x}$Se$_2$ ($x \leq 0.2$). RuSe$_2$ is a semiconductor that
crystallizes in a cubic pyrite unit cell. The Seebeck coefficient of RuSe$_2$
exceeds -200 $\mu$V/K around 730 K. Ir substitution results in the suppression
of the resistivity and the Seebeck coefficient, suggesting the removal of the
peaks in density of states near the Fermi level. Ru$_{0.8}$Ir$_{0.2}$Se$_{2}$
shows a semiconductor-metal crossover at about 30 K. The magnetic field
restores the semiconducting behavior. Our results indicate the importance of
the electronic correlations in enhanced thermoelectricity of RuSb$_{2}$.


title: Lagrangian analysis of the laminar flat plate boundary layer

abstract:
  The flow properties at the leading edge of a flat plate represent a
singularity to the Blasius laminar boundary layer equations; by applying the
Lagrangian approach the leading edge velocity profiles of the laminar boundary
layer over a flat plate are studied. Experimental observations as well as the
theoretical analysis show an exact Gaussian distribution curve as the original
starting profile of the laminar flow. Comparisons between the Blasius solution
and the Gaussian curve solution are carried out providing a new insight into
the physics of the laminar flow.


title: On semigroups with PSPACE-complete subpower membership problem

abstract:
  Fix a finite semigroup $S$ and let $a_1, \ldots, a_k, b$ be tuples in a
direct power $S^n$. The subpower membership problem (SMP) for $S$ asks whether
$b$ can be generated by $a_1, \ldots, a_k$. For combinatorial Rees matrix
semigroups we establish a dichotomy result: if the corresponding matrix is of a
certain form, then the SMP is in P; otherwise it is NP-complete. For
combinatorial Rees matrix semigroups with adjoined identity, we obtain a
trichotomy: the SMP is either in P, NP-complete, or PSPACE-complete. This
result yields various semigroups with PSPACE-complete SMP including the
$6$-element Brandt monoid, the full transformation semigroup on $3$ or more
letters, and semigroups of all $n$ by $n$ matrices over a field for $n\ge 2$.


title:
Smooth crossed products induced by minimal unique ergodic
  diffeomorphisms on odd spheres

abstract:
  For minimal unique ergodic diffeomorphisms $\alpha_n$ of $S^{2n+1} (n>0)$ and
$\alpha_m$ of $S^{2m+1}(m>0)$, the $C^*$-crossed product algebra
$C(S^{2n+1})\rtimes_{\alpha_n} \mathbb{Z}$ is isomorphic to
$C(S^{2m+1})\rtimes_{\alpha_m} \mathbb{Z}$ even though $n\neq m$ . However, by
cyclic cohomology, we show that smooth crossed product algebra
$C^\infty(S^{2n+1})\rtimes_{\alpha_n} \mathbb{Z}$ is not isomorphic to
$C^\infty(S^{2m+1})\rtimes_{\alpha_m} \mathbb{Z}$ if $n\neq m$.


title:
Radial Profile of the 3.55 keV line out to $R_{200}$ in the Perseus
  Cluster

abstract:
  The recent discovery of the unidentified emission line at 3.55 keV in
galaxies and clusters has attracted great interest from the community. As the
origin of the line remains uncertain, we study the surface brightness
distribution of the line in the Perseus cluster since that information can be
used to identify its origin. We examine the flux distribution of the 3.55 keV
line in the deep Suzaku observations of the Perseus cluster in detail. The 3.55
keV line is observed in three concentric annuli in the central observations,
although the observations of the outskirts of the cluster did not reveal such a
signal. We establish that these detections and the upper limits from the
non-detections are consistent with a dark matter decay origin. However, absence
of positive detection in the outskirts is also consistent with some unknown
astrophysical origin of the line in the dense gas of the Perseus core, as well
as with a dark matter origin with a steeper dependence on mass than the dark
matter decay. We also comment on several recently published analyses of the
3.55 keV line.


title: Solving Diophantine Equations

abstract:
  In this book a multitude of Diophantine equations and their partial or
complete solutions are presented. How should we solve, for example, the
equation {\eta}({\pi}(x)) = {\pi}({\eta}(x)), where {\eta} is the Smarandache
function and {\pi} is Riemann function of counting the number of primes up to
x, in the set of natural numbers? If an analytical method is not available, an
idea would be to recall the empirical search for solutions. We establish a
domain of searching for the solutions and then we check all possible
situations, and of course we retain among them only those solutions that verify
our equation. In other words, we say that the equation does not have solutions
in the search domain, or the equation has n solutions in this domain. This mode
of solving is called partial resolution. Partially solving a Diophantine
equation may be a good start for a complete solving of the problem. The authors
have identified 62 Diophantine equations that impose such approach and they
partially solved them. For an efficient resolution it was necessarily that they
have constructed many useful tools for partially solving the Diophantine
equations into a reasonable time. The computer programs as tools were written
in Mathcad, because this is a good mathematical software where many
mathematical functions are implemented. Transposing the programs into another
computer language is facile, and such algorithms can be turned to account on
other calculation systems with various processors.


title: Increasing and decreasing prime gaps

abstract:
  Let $p_n$ denote the $n$th prime and $g_n:=p_{n+1}-p_n$ the $n$th prime gap.
We demonstrate the existence of infinitely many values of $n$ for which
$g_n>g_{n+1}>\cdots>g_{n+m}$ with $m\gg \log\log\log n$ and similarly for the
reversed inequalities. In doing so we settle a conjecture of Erd\"os for the
case $m=2$.


title: The Fundamental Theorems of Affine and Projective Geometry Revisited

abstract:
  The fundamental theorem of affine geometry is a classical and useful result.
For finite-dimensional real vector spaces, the theorem roughly states that a
bijective self-mapping which maps lines to lines is affine. In this note we
prove several generalizations of this result and of its classical projective
counterpart. We show that under a significant geometric relaxation of the
hypotheses, namely that only lines parallel to one of a fixed set of finitely
many directions are mapped to lines, an injective mapping of the space must be
of a very restricted polynomial form. We also prove that under mild additional
conditions the mapping is forced to be affine-additive or affine-linear. For
example, we show that five directions in three dimensional real space suffice
to conclude affine-additivity. In the projective setting, we show that n+2
fixed projective points in real n-dimensional projective space , through which
all projective lines that pass are mapped to projective lines, suffice to
conclude projective-linearity.


title: Proceedings of the 39th Scandinavian Symposium on Physical Acoustics

abstract:
  The 39th Scandinavian Symposium on Physical Acoustics was held at Geilo,
Norway from January 31 to February 3, 2016. It was arranged by the Acoustics
and Optics group of the Norwegian Physical Society, and was coordinated by Ulf
Kristiansen and Erlend Magnus Viggen. This year, there were 48 participants,
holding a total of 31 presentations on various topics in physical acoustics,
such as ultrasonics, underwater sound propagation, waves in solids, flow
acoustics, and sonar. After the conference, 9 of these presentations were
submitted as papers to these proceedings.


title:
The MASSIVE Survey IV.: The X-ray halos of the most massive early-type
  galaxies in the nearby Universe

abstract:
  Studies of the physical properties of local elliptical galaxies (e.g., gas
temperatures, halo masses, stellar kinematics) are shedding new light on galaxy
formation. Here we present the hot X-ray gas properties of 33 early-type
systems within the MASSIVE galaxy survey sample that have archival Chandra
X-ray observations. Through careful X-ray spectral modeling, we derive X-ray
luminosities (L_X) and plasma temperatures (T_gas) for the diffuse gas
components in these galaxies. We combine the MASSIVE sample with 41 galaxies
from the ATLAS^3D survey to investigate the X-ray and optical properties of a
statistically significant sample of nearby early-type galaxies across a
wide-range of environments. We deduce that all early-type galaxies (independent
of galaxy mass and rotational support) follow a universal scaling law such that
L_X~T_gas^4.5. When X-ray measurements are performed consistently in apertures
set by the galaxy stellar content, the wide-scale environment does not
contribute to the intrinsic scatter (~0.5dex) within the scaling relation. We
further demonstrate that the scatter in L_X around both K-band luminosity (L_K)
and the galaxy stellar velocity dispersion is primarily driven by T_gas, with
no clear trends with halo mass, radio power, or angular momentum of the stars.
It is not trivial to tie the origin of the gas directly to either the stellar
mass or the galaxy potential. Indeed, our data require a steeper relation
between L_X, L_K, and sigma_e than predicted by standard mass-loss models.
Finally, we find a statistically significant correlation between sigma_e and
T_gas, suggesting that T_gas is set by the galaxy potential inside the optical
effective radius. We conclude that within the inner-most 10-30kpc region,
early-types maintain pressure-supported hot gas, with a minimum T_gas set by
the virial temperature, but the majority show evidence for some additional
heating.


title:
Revealing the spiral arms through radial migration and the shape of the
  Metallicity Distribution Function

abstract:
  Recent observations show that the Milky Way's metallicity distribution
function (MDF) changes its shape as a function of radius. This new evidence of
radial migration within the stellar disc sets additional constraints on
Galactic models. By performing controlled test particle simulations in a very
detailed, observationally motivated model of the Milky Way, we demonstrate
that, in the inner region of the disc, the MDF is shaped by the joint action of
the bar and spiral arms, while at outer radii the MDF is mainly shaped by the
spiral arms. We show that the spiral arms are able to imprint their signature
in the radial migration, shaping the MDF in the outskirts of the Galactic disc
with a minimal participation of the bar. Conversely, this work has the
potential to characterise some structural and dynamical parameters of the
spiral arms based on radial migration and the shape of the MDF. Finally, the
resemblance obtained with this approximation to the MDF curves of the Galaxy as
seen by APOGEE, show that a fundamental factor influencing their shape is the
Galactic potential.


title: A Conformal Truncation Framework for Infinite-Volume Dynamics

abstract:
  We present a new framework for studying conformal field theories deformed by
one or more relevant operators. The original CFT is described in infinite
volume using a basis of states with definite momentum, $P$, and conformal
Casimir, $\mathcal{C}$. The relevant deformation is then considered using
lightcone quantization, with the resulting Hamiltonian expressed in terms of
this CFT basis. Truncating to states with $\mathcal{C} \leq
\mathcal{C}_{\max}$, one can numerically find the resulting spectrum, as well
as other dynamical quantities, such as spectral densities of operators. This
method requires the introduction of an appropriate regulator, which can be
chosen to preserve the conformal structure of the basis. We check this
framework in three dimensions for various perturbative deformations of a free
scalar CFT, and for the case of a free $O(N)$ CFT deformed by a mass term and a
non-perturbative quartic interaction at large-$N$. In all cases, the truncation
scheme correctly reproduces known analytic results. We also discuss a general
procedure for generating a basis of Casimir eigenstates for a free CFT in any
number of dimensions.


title:
Predicted Sizes of Pressure-Supported HI Clouds in the Outskirts of the
  Virgo Cluster

abstract:
  Using data from the ALFALFA Arecibo HI survey of galaxies and the Virgo
cluster X-ray pressure profiles from XMM-Newton, we investigate the possibility
that starless dark HI clumps, also known as "dark galaxies", are supported by
external pressure in the surrounding intercluster medium. We find that the
starless HI clump masses, velocity dispersions and positions allow these clumps
to be in pressure equilibrium with the X-ray gas near the virial radius of the
Virgo cluster. We predict the sizes of these clumps to range from 1-10 kpc, in
agreement with the range of sizes found for spatially resolved HI starless
clumps outside of Virgo. Based on the predicted HI surface density of the Virgo
sources, as well as a sample of other similar resolved ALFALFA HI dark clumps
with follow up optical/radio observations, we predict that most of the HI dark
clumps are on the cusp of forming stars. These HI sources therefore mark the
transition between starless HI clouds and dwarf galaxies with stars.


title:
The Globular Cluster System of the Coma cD Galaxy NGC 4874 from Hubble
  Space Telescope ACS and WFC3/IR Imaging

abstract:
  We present new HST optical and near-infrared (NIR) photometry of the rich
globular cluster (GC) system of NGC 4874, the cD galaxy in the core of the Coma
cluster (Abell 1656). NGC 4874 was observed with the HST Advanced Camera for
Surveys in the F475W (g) and F814W (I) passbands and the Wide Field Camera 3 IR
Channel in F160W (H). The GCs in this field exhibit a bimodal optical color
distribution with more than half of the GCs falling on the red side at g-I > 1.
Bimodality is also present, though less conspicuously, in the optical-NIR I-H
color. Consistent with past work, we find evidence for nonlinearity in the g-I
versus I-H color-color relation. Our results thus underscore the need for
understanding the detailed form of the color-metallicity relations in
interpreting observational data on GC bimodality. We also find a very strong
color-magnitude trend, or "blue tilt," for the blue component of the optical
color distribution of the NGC 4874 GC system. A similarly strong trend is
present for the overall mean I-H color as a function of magnitude; for M_814 <
-10 mag, these trends imply a steep mass-metallicity scaling with $Z\propto
M_{\rm GC}^{1.4\pm0.4}$, but the scaling is not a simple power law and becomes
much weaker at lower masses. As in other similar systems, the spatial
distribution of the blue GCs is more extended than that of the red GCs, partly
because of blue GCs associated with surrounding cluster galaxies. In addition,
the center of the GC system is displaced by 4+/-1 kpc towards the southwest
from the luminosity center of NGC 4874, in the direction of NGC 4872. Finally,
we remark on a dwarf elliptical galaxy with a noticeably asymmetrical GC
distribution. Interestingly, this dwarf has a velocity of nearly -3000 km/s
with respect to NGC 4874; we suggest it is on its first infall into the cluster
core and is undergoing stripping of its GC system by the cluster potential.


title: Microlensing as a possible probe of event-horizon structure in quasars

abstract:
  In quasars which are lensed by galaxies, the point-like images sometimes show
sharp and uncorrelated brightness variations (microlensing). These brightness
changes are associated with the innermost region of the quasar passing through
a complicated pattern of caustics produced by the stars in the lensing galaxy.
In this paper, we study whether the universal properties of optical caustics
could enable extraction of shape information about the central engine of
quasars. We present a toy model with a crescent-shaped source crossing a fold
caustic. The silhouette of a black hole over an accretion disk tends to produce
roughly crescent sources. When a crescent-shaped source crosses a fold caustic,
the resulting light curve is noticeably different from the case of a circular
luminosity profile or Gaussian source. With good enough monitoring data, the
crescent parameters, apart from one degeneracy, can be recovered.


title: The Trispectrum in the Effective Field Theory of Large Scale Structure

abstract:
  We compute the connected four point correlation function (the trispectrum in
Fourier space) of cosmological density perturbations at one-loop order in
Standard Perturbation Theory (SPT) and the Effective Field Theory of Large
Scale Structure (EFT of LSS). This paper is a companion to our earlier work on
the non-Gaussian covariance of the matter power spectrum, which corresponds to
a particular wavenumber configuration of the trispectrum. In the present
calculation, we highlight and clarify some of the subtle aspects of the EFT
framework that arise at third order in perturbation theory for general
wavenumber configurations of the trispectrum. We consistently incorporate
vorticity and non-locality in time into the EFT counterterms and lay out a
complete basis of building blocks for the stress tensor. We show predictions
for the one-loop SPT trispectrum and the EFT contributions, focusing on
configurations which have particular relevance for using LSS to constrain
primordial non-Gaussianity.


title: Majorana Dark matter with B+L gauge symmetry

abstract:
  We present a new model that extends the Standard Model (SM) with the local
B+L symmetry, and point out that the lightest new fermion $\zeta$, introduced
to cancel anomalies and stabilized automatically by the B+L symmetry, can serve
as the cold dark matter candidate. We study constraints on the model from Higgs
measurements, electroweak precision measurements as well as the relic density
and direct detections of the dark matter. Numerical results reveal that the
pseudo-vector coupling of $\zeta$ with $Z$ and the Yukawa coupling with the SM
Higgs are highly constrained by the latest results of LUX, while there are
viable parameter space that could satisfy all the constraints and give testable
predictions.


title: EPR Pairs, Local Projections and Quantum Teleportation in Holography

abstract:
  In this paper we analyze three quantum operations in two dimensional
conformal field theories (CFTs): local projection measurements, creations of
partial entanglement between two CFTs, and swapping of subsystems between two
CFTs. We also give their holographic duals and study time evolutions of
entanglement entropy. By combining these operations, we present an analogue of
quantum teleportation between two CFTs and give its holographic realization. We
introduce a new quantity to probe tripartite entanglement by using local
projection measurement.


title: A Degeneracy in DRW Modelling of AGN Light Curves

abstract:
  Individual light curves of active galactic nuclei (AGNs) are nowadays
successfully modelled with the damped random walk (DRW) stochastic process,
characterized by the power exponential covariance matrix of the signal, with
the power $\beta=1$. By Monte Carlo simulation means, we generate mock AGN
light curves described by non-DRW stochastic processes ($0.5\leq\beta\leq 1.5$
and $\beta\neq1$) and show they can be successfully and well-modelled as a
single DRW process, obtaining comparable goodness of fits. A good DRW fit, in
fact, may not mean that DRW is the true underlying process leading to
variability and it cannot be used as a proof for it. When comparing the input
(non-DRW) and measured (DRW) process parameters, the recovered time scale
(amplitude) increases (decreases) with the increasing input $\beta$. In
practice, this means that the recovered DRW parameters may lead to biased (or
even non-existing) correlations of the variability and physical parameters of
AGNs if the true AGN variability is caused by non-DRW stochastic processes. The
proper way of identifying the processes leading to variability are
model-independent structure functions and/or power spectral densities and then
using such information on the covariance matrix of the signal in light curve
modelling.


title: Semiclassical OPE coefficients from 3D gravity

abstract:
  We present a closed form expression for the semiclassical OPE coefficients
that are universal for all 2D CFTs with a "weak" light spectrum, by taking the
semiclassical limit of the fusion kernel. We match this with a properly
regularized and normalized bulk action evaluated on a geometry with three
conical defects, analytically continued in the deficit angles beyond the range
for which a metric with positive signature exists. The analytically continued
geometry has a codimension-one coordinate singularity surrounding the heaviest
conical defect. This singularity becomes a horizon after Wick rotating to
Lorentzian signature, suggesting a connection between universality and the
existence of a horizon.


title:
(Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC
  submillimetre galaxies III. Environments

abstract:
  We study the environment of 23 submillimetre galaxies (SMGs) drawn from the
JCMT/AzTEC 1.1mm S/N-limited sample in the COSMOS field, as well as 4 COSMOS
SMGs at z_spec>4.5, and 1 at z_spec=2.49, yielding a sample of 28 SMGs. We
search for overdensities using the COSMOS photometric redshifts based on over
30 UV-NIR photometric bands, reaching an accuracy of sigma(Delta
z/(1+z))=0.0067 (0.0155) at z<3.5 (>3.5). To identify overdensities we apply
the Voronoi tessellation analysis, and estimate the overdensity estimator
delta_g as a function of distance from the SMG and/or overdensity center. We
test and validate our approach via simulations, X-ray detected groups, and
spectroscopic verifications using VUDS and zCOSMOS catalogues showing that even
with photometric redshifts in COSMOS we can efficiently retrieve overdensities
out to z~5. Our results yield that 11/23 (48%) JCMT/AzTEC 1.1mm SMGs occupy
overdense environments. Considering the entire JCMT/AzTEC 1.1mm S/N>4 sample,
and accounting for the expected fraction of spurious detections, yields that
35-61% of the SMGs in the S/N-limited sample occupy overdense environments. We
perform an X-ray stacking analysis in the 0.5-2keV band using a 32" aperture
and our SMG positions, and find statistically significant detections. For our
z<2 [z>2] subsample we find an average flux of (4.0+/-0.8)x10^{-16}
[(1.3+/-0.5)x10^{-16}] erg/s/cm^2 and a corresponding total mass of M_200 =
2.8x10^{13} [2x10^{13}] MSol. Our results suggest a higher occurrence of SMGs
occupying overdense environments at z>3, than at z<3. This may be understood if
highly star forming galaxies can only be formed in the highest peaks of the
density field tracing the most massive dark matter haloes at early cosmic
epochs, while at later times cosmic structure may have matured sufficiently
that more modest overdensities correspond to sufficiently massive haloes to
form SMGs.


title: Effects of Bound States on Dark Matter Annihilation

abstract:
  We study the impact of bound state formation on dark matter annihilation
rates in models where dark matter interacts via a light mediator, the dark
photon. We derive the general cross section for radiative capture into all
possible bound states, and point out its non-trivial dependence on the dark
matter velocity and the dark photon mass. For indirect detection, our result
shows that dark matter annihilation inside bound states can play an important
role in enhancing signal rates over the rate for direct dark matter
annihilation with Sommerfeld enhancement. The effects are strongest for large
dark gauge coupling and when the dark photon mass is smaller than the typical
momentum of dark matter in the galaxy. As an example, we show that for thermal
dark matter the Fermi gamma ray constraint is substantially increased once
bound state effects are taken into account. We also find that bound state
effects are not important for dark matter annihilation during the freeze out
and recombination epochs.


title:
Anatomy of the AGN in NGC 5548 VIII. XMM-Newton's EPIC detailed view of
  an unexpected variable multilayer absorber

abstract:
  In 2013 we conducted a large multi-wavelength campaign on the archetypical
Seyfert 1 galaxy NGC 5548. Unexpectedly, this usually unobscured source
appeared strongly absorbed in the soft X-rays during the entire campaign, and
signatures of new and strong outflows were present in the almost simultaneous
UV HST/COS data. Here we carry out a comprehensive spectral analysis of all
available XMM-Newton observations of NGC 5548 (for a total of ~763 ks) in
combination with 3 simultaneous NuSTAR obs. We obtain a best-fit composed by i)
a weakly varying flat (Gamma~1.5-1.7) power-law component; ii) a constant, cold
reflection (FeK + continuum) component; iii) a soft excess, possibly due to
thermal Comptonization; and iv) a constant, ionized scattered emission-line
dominated component. Our main findings are that, during the 2013 campaign, the
first 3 of these components appear to be partially covered by a heavy and
variable obscurer located along the l.o.s. that is consistent with a multilayer
of cold and mildly ionized gas. We characterize in detail the short timescale
(~ks-to-days) spectral variability of this new obscurer, and find it is mostly
due to a combination of Nh and Cf variations, on top of intrinsic power-law
variations. In addition, our best-fit spectrum is left with several (but
marginal) absorption features at rest-frame energies ~6.7-6.9 keV and ~8 keV,
as well as a weak broad emission line feature redwards of the 6.4 keV emission
line. These could indicate a more complex underlying model, e.g. a P-Cygni-type
profile if allowing for a large velocity and wide-angle outflow. These findings
are consistent with a picture where the obscurer represents the manifestation
along the l.o.s. of a multilayer of gas that is likely outflowing at high
speed, and simultaneously producing heavy obscuration and scattering in the
X-rays and broad absorption features in the UV.


title:
Modelling circumbinary protoplanetary disks II. Gas disk feedback on
  planetesimal dynamical and collisional evolution in the circumbinary systems
  Kepler-16 and 34

abstract:
  Aims. We investigate the feasibility of planetesimal growth in circumbinary
protoplanetary disks around the observed systems Kepler- 16 and Kepler-34 under
the gravitational influence of a precessing eccentric gas disk. Methods. We
embed the results of our previous hydrodynamical simulations of protoplanetary
disks around binaries into an N-body code to perform 3D, high-resolution,
inter-particle gravity-enabled simulations of planetesimal growth and dynamics
that include the gravitational force imparted by the gas. Results. Including
the full, precessing asymmetric gas disk generates high eccentricity orbits for
planetesimals orbiting at the edge of the circumbinary cavity, where the gas
surface density and eccentricity have their largest values. The gas disk is
able to efficiently align planetesimal pericenters in some regions leading to
phased, non-interacting orbits. Outside of these areas eccentric planetesimal
orbits become misaligned and overlap leading to crossing orbits and high
relative velocities during planetesimal collisions. This can lead to an
increase in the number of erosive collisions that far outweighs the number of
collisions that result in growth. Gravitational focusing from the static
axisymmetric gas disk is weak and does not significantly alter collision
outcomes from the gas free case. Conclusions. Due to asymmetries in the gas
disk, planetesimals are strongly perturbed onto highly eccentric orbits. Where
planetesimals orbits are not well aligned, orbit crossings lead to an increase
in the number of erosive collisions. This makes it difficult for sustained
planetesimal accretion to occur at the location of Kepler-16b and Kepler-34b
and we therefore rule out in-situ growth. This adds further support to our
initial suggestions that most circumbinary planets should form further out in
the disk and migrate inwards.


title:
An X-ray and Radio Study of the Varying Expansion Velocities in Tycho's
  Supernova Remnant

abstract:
  We present newly obtained X-ray and radio observations of Tycho's supernova
remnant using {\it Chandra} and the Karl G. Jansky Very Large Array in 2015 and
2013/14, respectively. When combined with earlier epoch observations by these
instruments, we now have time baselines for expansion measurements of the
remnant of 12-15 year in the X-rays and 30 year in the radio. The remnant's
large angular size allows for proper motion measurements at many locations
around the periphery of the blast wave. We find, consistent with earlier
measurements, a clear gradient in the expansion velocity of the remnant,
despite its round shape. The proper motions on the western and southwestern
sides of the remnant are about a factor of two higher than those in the east
and northeast. We showed in an earlier work that this is related to an offset
of the explosion site from the geometric center of the remnant due to a density
gradient in the ISM, and using our refined measurements reported here, we find
that this offset is $\sim 23"$ towards the northeast. An explosion center
offset in such a circular remnant has implications for searches for progenitor
companions in other remnants.


title: Not Just a Phase: Bose Metal Unveiled

abstract:
  I analyze the recent observation of a Bose metal in NbSe$_2$ and place these
results in the wider context of the first sighting of such a phase in amorphous
Bi and MoGe thin films.


title:
Dynamical constraints on the origin of hot and warm Jupiters with close
  friends

abstract:
  Gas giants orbiting their host star within the ice line are thought to have
migrated to their current locations from farther out. Here we consider the
origin and dynamical evolution of observed Jupiters, focusing on hot and warm
Jupiters with outer friends. We show that the majority of the observed Jupiter
pairs (twenty out of twenty-four) will be dynamically unstable if the inner
planet was placed at >~1AU distance from the stellar host. This finding is at
odds with formation theories that invoke the migration of such planets from
semi-major axes >~1AU due to secular dynamical processes (e.g., secular chaos,
Lidov-Kozai oscillations) coupled with tidal dissipation. In fact, the results
of N-body integrations show that the evolution of dynamically unstable systems
does not lead to tidal migration but rather to planet ejections and collisions
with the host star. This and other arguments lead us to suggest that most of
the observed planets with a companion could not have been transported from
further out through secular migration processes. More generally, by using a
combination of numerical and analytic techniques we show that the high-e
Lidov-Kozai migration scenario can only account for less than 10% of all gas
giants observed between 0.1-1 AU. Simulations of multi-planet systems support
this result. Our study indicates that rather than starting on highly eccentric
orbits with orbital periods above one year, these "warm" Jupiters are more
likely to have reached the region where they are observed today without having
experienced significant tidal dissipation.


title: Constraints on Perturbative RG Flows in Six Dimensions

abstract:
  When conformal field theories (CFTs) are perturbed by marginally relevant
deformations, renormalization group (RG) flows ensue that can be studied with
perturbative methods, at least as long as they remain close to the original
CFT. In this work we study such RG flows in the vicinity of six-dimensional
unitary CFTs. Neglecting effects of scalar operators of dimension two and four,
we use Weyl consistency conditions to prove the $a$-theorem in perturbation
theory, and establish that scale implies conformal invariance. We identify a
quantity that monotonically decreases in the flow to the infrared due to
unitarity, showing that it does not agree with the one studied recently in the
literature on the six-dimensional $\phi^3$ theory.


title: Cutkosky Rules for Superstring Field Theory

abstract:
  Superstring field theory expresses the perturbative S-matrix of superstring
theory as a sum of Feynman diagrams each of which is manifestly free from
ultraviolet divergences. The interaction vertices fall off exponentially for
large space-like external momenta making the ultraviolet finiteness property
manifest, but blow up exponentially for large time-like external momenta making
it impossible to take the integration contours for loop energies to lie along
the real axis. This forces us to carry out the integrals over the loop energies
by choosing appropriate contours in the complex plane whose ends go to infinity
along the imaginary axis but which take complicated form in the interior
navigating around the various poles of the propagators. We consider the general
class of quantum field theories with this property and prove Cutkosky rules for
the amplitudes to all orders in perturbation theory. Besides having
applications to string field theory, these results also give an alternative
derivation of Cutkosky rules in ordinary quantum field theories.


title:
A high transmission broadband gradient index lens using elastic shell
  acoustic metamaterial elements

abstract:
  The use of cylindrical elastic shells as elements in acoustic metamaterial
devices is demonstrated through simulations and underwater measurements of a
cylindrical-to-plane wave lens. Transformation acoustics (TA) of a circular
region to a square dictates that the effective density in the lens remain
constant and equal to that of water. Piecewise approximation to the desired
effective compressibility is achieved using a square array with elements based
on the elastic shell metamaterial concept developed in [30]. The size of the
elements are chosen based on availability of shells, minimizing fabrication
difficulties. The tested device is neutrally buoyant comprising 48 elements of
nine different types of commercial shells made from aluminum, brass, copper,
and polymers. Simulations indicate a broadband range in which the device acts
as a cylindrical to plane wave lens. The experimental findings confirm the
broadband quadropolar response from approximately 20 to 40 kHz, with positive
gain of the radiation pattern in the four plane wave directions.


title: Safe Probability

abstract:
  We formalize the idea of probability distributions that lead to reliable
predictions about some, but not all aspects of a domain. The resulting notion
of `safety' provides a fresh perspective on foundational issues in statistics,
providing a middle ground between imprecise probability and multiple-prior
models on the one hand and strictly Bayesian approaches on the other. It also
allows us to formalize fiducial distributions in terms of the set of random
variables that they can safely predict, thus taking some of the sting out of
the fiducial idea. By restricting probabilistic inference to safe uses, one
also automatically avoids paradoxes such as the Monty Hall problem. Safety
comes in a variety of degrees, such as "validity" (the strongest notion),
"calibration", "confidence safety" and "unbiasedness" (almost the weakest
notion).


title:
Post Markovian Dynamics of Quantum Correlations: Entanglement vs.
  Discord

abstract:
  Dynamics of an open two-qubit system is investigated in the post-Markovian
regime, where the environments have a short-term memory. Each qubit is coupled
to separate environment which is held in its own temperature. The inter-qubit
interaction is modeled by XY-Heisenberg model in the presence of spin-orbit
interaction and inhomogeneous magnetic field. The dynamical behavior of
entanglement and discord has been considered. The results show that, quantum
discord is more robust than quantum entanglement, during the evolution. Also
the asymmetric feature of quantum discord can be monitored by introducing the
asymmetries due to inhomogeneity of magnetic field and temperature difference
between the reservoirs. By employing proper parameters of the model, it is
possible to maintain non-vanishing quantum correlation at high degree of
temperature. The results can provide a useful recipe for studying of dynamical
behavior of two-qubit systems such as trapped spin-electrons in coupled quantum
dots.


title: A Subpath Kernel for Learning Hierarchical Image Representations

abstract:
  Tree kernels have demonstrated their ability to deal with hierarchical data,
as the intrinsic tree structure often plays a discriminative role. While such
kernels have been successfully applied to various domains such as nature
language processing and bioinformatics, they mostly concentrate on ordered
trees and whose nodes are described by symbolic data. Meanwhile, hierarchical
representations have gained increasing interest to describe image content. This
is particularly true in remote sensing, where such representations allow for
revealing different objects of interest at various scales through a tree
structure. However, the induced trees are unordered and the nodes are equipped
with numerical features. In this paper, we propose a new structured kernel for
hierarchical image representations which is built on the concept of subpath
kernel. Experimental results on both artificial and remote sensing datasets
show that the proposed kernel manages to deal with the hierarchical nature of
the data, leading to better classification rates.


title:
The Carnegie-Chicago Hubble Program. I. An Independent Approach to the
  Extragalactic Distance Scale Using only Population II Distance Indicators

abstract:
  We present an overview of the Carnegie-Chicago Hubble Program, an ongoing
program to obtain a 3 per cent measurement of the Hubble constant using
alternative methods to the traditional Cepheid distance scale. We aim to
establish a completely independent route to the Hubble constant using RR Lyrae
variables, the tip of the red giant branch (TRGB), and Type Ia supernovae (SNe
Ia). This alternative distance ladder can be applied to galaxies of any Hubble
Type, of any inclination, and, utilizing old stars in low density environments,
is robust to the degenerate effects of metallicity and interstellar extinction.
Given the relatively small number of SNe Ia host galaxies with independently
measured distances, these properties provide a great systematic advantage in
the measurement of the Hubble constant via the distance ladder. Initially, the
accuracy of our value of the Hubble constant will be set by the five Galactic
RR Lyrae calibrators with Hubble Space Telescope Fine-Guidance Sensor
parallaxes. With Gaia, both the RR Lyrae zero point and TRGB method will be
independently calibrated, the former with at least an order of magnitude more
calibrators and the latter directly through parallax measurement of tip red
giants. As the first end-to-end "distance ladder" completely independent of
both Cepheid variables and the Large Magellanic Cloud, this path to the Hubble
constant will allow for the high precision comparison at each rung of the
traditional distance ladder that is necessary to understand tensions between
this and other routes to the Hubble constant.


title:
GateKeeper: A New Hardware Architecture for Accelerating Pre-Alignment
  in DNA Short Read Mapping

abstract:
  Motivation: High throughput DNA sequencing (HTS) technologies generate an
excessive number of small DNA segments -- called short reads -- that cause
significant computational burden. To analyze the entire genome, each of the
billions of short reads must be mapped to a reference genome based on the
similarity between a read and "candidate" locations in that reference genome.
The similarity measurement, called alignment, formulated as an approximate
string matching problem, is the computational bottleneck because: (1) it is
implemented using quadratic-time dynamic programming algorithms, and (2) the
majority of candidate locations in the reference genome do not align with a
given read due to high dissimilarity. Calculating the alignment of such
incorrect candidate locations consumes an overwhelming majority of a modern
read mapper's execution time. Therefore, it is crucial to develop a fast and
effective filter that can detect incorrect candidate locations and eliminate
them before invoking computationally costly alignment operations. Results: We
propose GateKeeper, a new hardware accelerator that functions as a
pre-alignment step that quickly filters out most incorrect candidate locations.
GateKeeper is the first design to accelerate pre-alignment using
Field-Programmable Gate Arrays (FPGAs), which can perform pre-alignment much
faster than software. GateKeeper can be integrated with any mapper that
performs sequence alignment for verification. When implemented on a single FPGA
chip, GateKeeper maintains high accuracy (on average >96%) while providing up
to 90-fold and 130-fold speedup over the state-of-the-art software
pre-alignment techniques, Adjacency Filter and Shifted Hamming Distance (SHD),
respectively. The addition of GateKeeper as a pre-alignment step can reduce the
verification time of the mrFAST mapper by a factor of 10. Availability:
https://github.com/BilkentCompGen/GateKeeper


title: The Mathematics of Entanglement

abstract:
  These notes are from a series of lectures given at the Universidad de Los
Andes in Bogot\'a, Colombia on some topics of current interest in quantum
information. While they aim to be self-contained, they are necessarily
incomplete and idiosyncratic in their coverage. For a more thorough
introduction to the subject, we recommend one of the textbooks by Nielsen and
Chuang or by Wilde, or the lecture notes of Mermin, Preskill or Watrous. Our
notes by contrast are meant to be a relatively rapid introduction into some
more contemporary topics in this fast-moving field. They are meant to be
accessible to advanced undergraduates or starting graduate students.


title:
Effect of strain and temperature on the threshold displacement energy in
  body-centered cubic iron

abstract:
  The threshold displacement energy (TDE) is the minimum amount of kinetic
energy required to displace an atom from its lattice site. The magnitude of the
TDE displays significant variance as a function of the crystallographic
direction, system temperature and applied strain, among a variety of other
factors. It is critically important to determine an accurate value of the TDE
in order to calculate the total number of displacements due to a given
irradiation condition, and thus to understand the materials response to
irradiation. In this study, molecular dynamics simulations have been performed
to calculate the threshold displacement energy in body-centered cubic iron as a
function of strain and temperature. With applied strain, a decrease of the TDE
of up to approximately 14 eV was observed. A temperature increase from 300 K to
500 K can result in an increase of the TDE of up to approximately 9 eV.


title: Advances in Very Deep Convolutional Neural Networks for LVCSR

abstract:
  Very deep CNNs with small 3x3 kernels have recently been shown to achieve
very strong performance as acoustic models in hybrid NN-HMM speech recognition
systems. In this paper we investigate how to efficiently scale these models to
larger datasets. Specifically, we address the design choice of pooling and
padding along the time dimension which renders convolutional evaluation of
sequences highly inefficient. We propose a new CNN design without timepadding
and without timepooling, which is slightly suboptimal for accuracy, but has two
significant advantages: it enables sequence training and deployment by allowing
efficient convolutional evaluation of full utterances, and, it allows for batch
normalization to be straightforwardly adopted to CNNs on sequence data. Through
batch normalization, we recover the lost peformance from removing the
time-pooling, while keeping the benefit of efficient convolutional evaluation.
We demonstrate the performance of our models both on larger scale data than
before, and after sequence training. Our very deep CNN model sequence trained
on the 2000h switchboard dataset obtains 9.4 word error rate on the Hub5
test-set, matching with a single model the performance of the 2015 IBM system
combination, which was the previous best published result.


abstract:
  We investigate Hawking radiation from a five-dimensional Lovelock black hole
using the Hamilton-Jacobi method. The behavior of the rate of radiation is
plotted for various values of the ultraviolet correction parameter and the
cosmological constant. The results show that, owing to the ultraviolet
correction and the presence of dark energy represented by the cosmological
constant, the black hole radiates at a slower rate in comparison to the case
without ultraviolet correction or cosmological constant. Moreover, the presence
of the cosmological constant makes the effect of the ultraviolet correction on
the black hole radiation negligible.


title:
Optimal initial condition of passive tracers for their maximal mixing in
  finite time

abstract:
  The efficiency of a fluid mixing device is often limited by fundamental laws
and/or design constraints, such that a perfectly homogeneous mixture cannot be
obtained in finite time. Here, we address the natural corollary question: Given
the best available mixer, what is the optimal initial tracer pattern that leads
to the most homogeneous mixture after a prescribed finite time? For ideal
passive tracers, we show that this optimal initial condition coincides with the
right singular vector (corresponding to the smallest singular value) of a
suitably truncated Perron-Frobenius (PF) operator. The truncation of the PF
operator is made under the assumption that there is a small length-scale
threshold $\ell_\nu$ under which the tracer blobs are considered, for all
practical purposes, completely mixed. We demonstrate our results on two
examples: a prototypical model known as the sine flow and a direct numerical
simulation of two-dimensional turbulence. Evaluating the optimal initial
condition through this framework only requires the position of a dense grid of
fluid particles at the final instance and their preimages at the initial
instance of the prescribed time interval. As such, our framework can be readily
applied to flows where such data is available through numerical simulations or
experimental measurements.

categories: physics.flu-dyn math.DS math.OC physics.comp-ph


title:
Collective intelligence: aggregation of information from neighbors in a
  guessing game

abstract:
  Complex systems show the capacity to aggregate information and to display
coordinated activity. In the case of social systems the interaction of
different individuals leads to the emergence of norms, trends in political
positions, opinions, cultural traits, and even scientific progress. Examples of
collective behavior can be observed in activities like the Wikipedia and Linux,
where individuals aggregate their knowledge for the benefit of the community,
and citizen science, where the potential of collectives to solve complex
problems is exploited. Here, we conducted an online experiment to investigate
the performance of a collective when solving a guessing problem in which each
actor is endowed with partial information and placed as the nodes of an
interaction network. We measure the performance of the collective in terms of
the temporal evolution of the accuracy, finding no statistical difference in
the performance for two classes of networks, regular lattices and random
networks. We also determine that a Bayesian description captures the behavior
pattern the individuals follow in aggregating information from neighbors to
make decisions. In comparison with other simple decision models, the strategy
followed by the players reveals a suboptimal performance of the collective. Our
contribution provides the basis for the micro-macro connection between
individual based descriptions and collective phenomena.


title:
Lack of a thermodynamic finite-temperature spin-glass phase in the
  two-dimensional randomly-coupled ferromagnet

abstract:
  The search for problems where quantum adiabatic optimization might excel over
classical optimization techniques has sparked a recent interest in inducing a
finite-temperature spin-glass transition in quasi-planar topologies. We have
performed large-scale finite-temperature Monte Carlo simulations of a
two-dimensional square-lattice bimodal spin glass with next-nearest
ferromagnetic interactions claimed to exhibit a finite-temperature spin-glass
state for a particular relative strength of the next-nearest to nearest
interactions [Phys. Rev. Lett. 76, 4616 (1996)]. Our results show that the
system is in a paramagnetic state in the thermodynamic limit, despite
zero-temperature simulations [Phys. Rev. B 63, 094423 (2001)] suggesting the
existence of a finite-temperature spin-glass transition. Therefore, deducing
the finite-temperature behavior from zero-temperature simulations can be
dangerous when corrections to scaling are large.


title:
The shape of health: A comparison of five alternative ways of
  visualizing personal health and wellbeing

abstract:
  The combination of clinical and personal health and wellbeing data can tell
us much about our behaviors, risks and overall status. The way this data is
visualized may affect our understanding of our own health. To study this
effect, we conducted a small experiment with 30 participants in which we
presented a holistic overview of the health and wellbeing of two modeled
individuals, one of them with metabolic syndrome. We used an insight-based
methodology to assess the effectiveness of the visualizations. The results show
that adequate visualization of holistic health data helps users without medical
background to better understand the overall health situation and possible
health risks related to lifestyles. Furthermore, we found that the application
of insight-based methodology in the health and wellbeing domain remains
unexplored and additional research and methodology development are needed.


title: Comments on "Searching for a continuum limit in CDT quantum gravity"

abstract:
  To facilitate the search for a continuum limit of causal dynamical
triangulations, Ambjorn, Coumbe, Gizbert-Studnicki, and Jurkiewicz recently
reported measurements of the lattice spacing as a function of the bare
couplings. Although these authors' methods are technically sound, the
conclusions that they draw from their analyses rest crucially on certain
unstated assumptions. I elucidate these assumptions, and I argue that our
current understanding of causal dynamical triangulations does not entail their
justification.


title: Fast Radio Bursts---A Brief Review: Some Questions, Fewer Answers

abstract:
  Fast Radio Bursts are millisecond bursts of radio radiation at frequencies of
about 1 GHz, recently discovered in pulsar surveys. They have not yet been
definitively identified with any other astronomical object or phenomenon. The
bursts are strongly dispersed, indicating passage through a high column density
of low density plasma. The most economical interpretation is that this is the
interglactic medium, indicating that FRB are at "cosmological" distances with
redshifts in the range 0.3--1.3. Their inferred brightness temperatures are as
high as $10^{37\,\circ}$K, implying coherent emission by "bunched" charges, as
in radio pulsars. I review the astronomical sites, objects and emission
processes that have been proposed as the origin of FRB, with particular
attention to Soft Gamma Repeaters and giant pulsar pulses.


title: Birefringence phenomena revisited

abstract:
  The propagation of electromagnetic waves is investigated in the context of
the isotropic and nonlinear dielectric media at rest in the eikonal limit of
the geometrical optics. Taking into account the functional dependence
$\varepsilon=\varepsilon(E,B)$ and $\mu=\mu(E,B)$ for the dielectric
coefficients, a set of phenomena related to the birefringence of the
electromagnetic waves induced by external fields are derived and discussed. Our
results contemplate the known cases already reported in the literature: Kerr,
Cotton-Mouton, Jones and magnetoelectric effects. Moreover, new effects are
presented here as well as the perspectives of its experimental confirmations.


title:
The Role of Conservation Principles in the Abraham--Minkowski
  Controversy

abstract:
  The Abraham--Minkowski controversy refers to a long-standing inability to
adequately address certain issues involving the conservation of the momentum of
an electromagnetic field in a linear dielectric medium. We apply the usual
assumption of a material subsystem that couples to the electromagnetic
subsystem such that the total energy and total momentum are conserved. We then
construct the total energy--momentum tensor from the total energy density and
the total momentum density. Applying conservation principles to the total
energy--momentum tensor, we construct the tensor energy--momentum continuity
equation. We show that one of the components of the tensor energy--momentum
continuity equation, the energy continuity equation, is manifestly false. We
conclude that the Abraham--Minkowski controversy is unresolvable because the
extant principles of conservation are inconsistent in a simple linear
dielectric medium.


title: Learning to Track at 100 FPS with Deep Regression Networks

abstract:
  Machine learning techniques are often used in computer vision due to their
ability to leverage large amounts of training data to improve performance.
Unfortunately, most generic object trackers are still trained from scratch
online and do not benefit from the large number of videos that are readily
available for offline training. We propose a method for offline training of
neural networks that can track novel objects at test-time at 100 fps. Our
tracker is significantly faster than previous methods that use neural networks
for tracking, which are typically very slow to run and not practical for
real-time applications. Our tracker uses a simple feed-forward network with no
online training required. The tracker learns a generic relationship between
object motion and appearance and can be used to track novel objects that do not
appear in the training set. We test our network on a standard tracking
benchmark to demonstrate our tracker's state-of-the-art performance. Further,
our performance improves as we add more videos to our offline training set. To
the best of our knowledge, our tracker is the first neural-network tracker that
learns to track generic objects at 100 fps.


title:
Spreading, Fingering Instability and Shrinking of a Hydrosoluble
  Surfactant on Water

abstract:
  We report an experimental investigation of spreading then shrinking of a
surfactant droplet at the air-water interface with fingering instability
appearing at the edge of the droplet stain. We find out that a droplet of a
surfactant on the water shows three regimes of spreading, shrinking and resting
at the appropriate parameters values. These regimes can be distinguished by
measuring the mean square displacement of the droplet parts, fractal dimension
of stain, or radius of fingerless part of the stain (to measure it, we define
the angular box-counting dimension), versus time. The shrinking regime is a
novel phenomenon.


title: Truly trapped rainbow by utilizing nonreciprocal waveguides

abstract:
  The concept of a "trapped rainbow" has generated considerable interest for
optical data storage and processing. It aims to trap different frequency
components of the wave packet at different positions permanently. However, all
the previously proposed structures cannot truly achieve this effect, due to the
difficulties in suppressing the reflection caused by strong intermodal coupling
and distinguishing different frequency components simultaneously. In this
article, we found a physical mechanism to achieve a truly "trapped rainbow"
storage of electromagnetic wave. We utilize nonreciprocal waveguides under a
tapered magnetic field to achieve this and such a trapping effect is stable
even under fabrication disorders. We also observe hot spots and relatively long
duration time of the trapped wave around critical positions through frequency
domain and time domain simulations. The physical mechanism we found has a
variety of potential applications ranging from wave harvesting and storage to
nonlinearity enhancement.


title:
New quantum critical points of $j=3/2$ Dirac electrons in antiperovskite
  topological crystalline insulators

abstract:
  We study the effect of the long-range Coulomb interaction in $j=3/2$ Dirac
electrons in cubic crystals with the $O_h$ symmetry, which serves as an
effective model for antiperovskite topological crystalline insulators. The
renormalization group analysis reveals three fixed points that are Lorentz
invariant, rotationally invariant, and $O_h$ invariant. Among them, the
Lorentz- and $O_h$-invariant fixed points are stable in the low-energy limit
while the rotationally invariant fixed point is unstable. The existence of a
stable $O_h$-invariant fixed point of Dirac fermions with finite velocity
anisotropy presents an interesting counterexample to emergent Lorentz
invariance in solids.


title: Generalising the Discriminative Restricted Boltzmann Machine

abstract:
  We present a novel theoretical result that generalises the Discriminative
Restricted Boltzmann Machine (DRBM). While originally the DRBM was defined
assuming the {0, 1}-Bernoulli distribution in each of its hidden units, this
result makes it possible to derive cost functions for variants of the DRBM that
utilise other distributions, including some that are often encountered in the
literature. This is illustrated with the Binomial and {-1, +1}-Bernoulli
distributions here. We evaluate these two DRBM variants and compare them with
the original one on three benchmark datasets, namely the MNIST and USPS digit
classification datasets, and the 20 Newsgroups document classification dataset.
Results show that each of the three compared models outperforms the remaining
two in one of the three datasets, thus indicating that the proposed theoretical
generalisation of the DRBM may be valuable in practice.


title: Realization of a twin beam source based on four-wave mixing in Cesium

abstract:
  Four-wave mixing (4WM) is a known source of intense non-classical twin beams.
It can be generated when an intense laser beam (the pump) and a weak laser beam
(the seed) overlap in a $\chi^{(3)}$ medium (here cesium vapor), with
frequencies close to resonance with atomic transitions. The twin beams
generated by 4WM have frequencies naturally close to atomic transitions, and
can be intense (gain $\gg 1$) even in the CW pump regime, which is not the case
for PDC $\chi^{(2)}$ phenomenon in non-linear crystals. So, 4WM is well suited
for atom-light interaction and atom-based quantum protocols. Here we present
the first realization of a source of 4-wave mixing exploiting $D_2$ line of
Cesium atoms.


title: Plaquette Valence Bond Theory of High-Temperature Superconductivity

abstract:
  We present a strong-coupling approach to the theory of high-temperature
superconductivity based on the observation of a quantum critical point in the
plaquette within the t,t' Hubbard model. The crossing of ground state energies
in the N=2,3,4 sectors occurs for parameters close to the optimal doping. The
theory predicts the maximum of the d(x2-y2)-wave order parameter at the border
between localized and itinerant electron behavior and gives a natural
explanation for the pseudo-gap formation via soft-fermion mode related to local
singlet states of the plaquette in the environment. Our approach follows the
general line of resonating valence bond theory stressing a crucial role of
singlets in the physics of high-Tc superconductors, but focuses on the
formation of local singlets, similar to phenomena observed in frustrated
one-dimensional quantum spin models.


title: Homoclinic bifurcation in Morse-Novikov theory, a doubling phenomenon

abstract:
  We consider a compact manifold of dimension greater than 2 and a differential
form of degree one which is closed but non-exact. This form, viewed as a
multi-valued function has a gradient vector field with respect to any
Riemannian metric. After S. Novikov's work and a complement by J.-C. Sikorav,
under some genericity assumptions these data yield a complex, called today the
Morse-Novikov complex. Due to the non-exactness of the form, its gradient has a
non-trivial dynamics in contrary to gradients of functions. In particular, it
is possible that the gradient has a homoclinic orbit. The one-form being fixed,
we investigate the codimension-one stratum in the space of gradients which is
formed by gradients having one simple homoclinic orbit. Such a stratum S breaks
up into a left and a right part separated by a substratum. The algebraic effect
on the Morse-Novikov complex of crossing S depends on the part, left or right,
which is crossed. The sudden creation of infinitely many new heteroclinic
orbits may happen. Moreover, some gradients with a simple homoclinic orbit are
approached by gradients with a simple homoclinic orbit of double energy. These
two phenomena are linked.


title: Metrical Characterizations of super weakly compact operators

abstract:
  We characterize super weakly compact operators as those through which binary
tree and diamond and Laakso graphs may not be factored with uniform distortion.


title:
Tunable photonic cavity coupled to a voltage-biased double quantum dot
  system: Diagrammatic NEGF approach

abstract:
  We investigate gain in microwave photonic cavities coupled to voltage-biased
double quantum dot systems with an arbitrary strong dot-lead coupling and with
a Holstein-like light-matter interaction, by adapting the diagrammatic Keldysh
nonequilibrium Green's function approach. We compute out-of-equilibrium
properties of the cavity : its transmission, phase response, mean photon
number, power spectrum, and spectral function. We show that by the careful
engineering of these hybrid light-matter systems, one can achieve a significant
amplification of the optical signal with the voltage-biased electronic system
serving as a gain medium. We also study the steady state current across the
device, identifying elastic and inelastic tunnelling processes which involve
the cavity mode. Our results show how recent advances in quantum electronics
can be exploited to build hybrid light-matter systems that behave as
single-atom amplifiers and photon source devices. The diagrammatic Keldysh
approach is primarily discussed for a cavity-coupled double quantum dot
architecture, but it is generalizable to other hybrid light-matter systems.


title: Moduli spaces of flat tori with prescribed holonomy

abstract:
  We generalise to the genus one case several results of Thurston concerning
moduli spaces of flat Euclidean structures with conical singularities on the
two dimensional sphere.
  More precisely, we study the moduli space of flat tori with $n$ cone points
and a prescribed holonomy $\rho$. In his paper `Flat Surfaces' Veech has
established that under some assumptions on the cone angles, such a moduli space
${\mathcal{F}}_{[\rho]}\subset \mathscr M_{1,n}$ carries a natural geometric
structure modeled on the complex hyperbolic space ${\mathbb C}{\mathbb{H}
}^{n-1}$ which is not metrically complete. Using surgeries for flat surfaces,
we prove that the metric completion $\overline{{\mathcal{F}}_{[\rho]}}$ is
obtained by adjoining to $ {\mathcal{F}}_{[\rho]} $ certain strata that are
themselves moduli spaces of flat surfaces of genus 0 or 1, obtained as
degenerations of the flat tori whose moduli space is $ {\mathcal{F}}_{[\rho]}$.
We show that the ${\mathbb C}{\mathbb{H} }^{n-1}$-structure of $
{\mathcal{F}}_{[\rho]}$ extends to a complex hyperbolic cone-manifold structure
of finite volume on $ \overline{{\mathcal{F}}_{[\rho]}}$ and we compute the
cone angles associated to the different strata of codimension 1.
  Finally, we address the question of whether or not the holonomy of Veech's
${\mathbb C}{\mathbb{H} }^{n-1}$-structure on $ \mathcal F_\rho$ has a discrete
image in $ {\rm Aut}({\mathbb C}{\mathbb{H} }^{n-1})=\mathrm{PU}(1,n-1)$. We
outline a general strategy to find moduli spaces $\mathcal F_{[\rho]}$ whose
${\mathbb C}{\mathbb{H} }^{n-1}$-holonomy gives rise to lattices in
$\mathrm{PU}(1,n-1)$ and eventually we give a finite list of $\mathcal
F_{[\rho]}$'s whose holonomy is a complex hyperbolic arithmetic lattice.


title: Multipolar robust optimization

abstract:
  We consider linear programs involving uncertain parameters and propose a new
tractable robust counterpart which contains and generalizes several other
models including the existing Affinely Adjustable Robust Counterpart and the
Fully Adjustable Robust Counterpart. It consists in selecting a set of poles
whose convex hull contains some projection of the uncertainty set, and
computing a recourse strategy for each data scenario as a convex combination of
some optimized recourses (one for each pole). We show that the proposed
multipolar robust counterpart is tractable and its complexity is controllable.
Further, we show that under some mild assumptions, two sequences of upper and
lower bounds converge to the optimal value of the fully adjustable robust
counterpart. To illustrate the approach, a robust problem related to lobbying
under some uncertain opinions of authorities is studied. Several numerical
experiments are carried out showing the advantages of the proposed robustness
framework and evaluating the benefit of adaptability.


title:
A fast immersed boundary method for external incompressible viscous
  flows using lattice Green's functions

abstract:
  A new parallel, computationally efficient immersed boundary method for
solving three-dimensional, viscous, incompressible flows on unbounded domains
is presented. Immersed surfaces with prescribed motions are generated using the
interpolation and regularization operators obtained from the discrete delta
function approach of the original (Peskin's) immersed boundary method. Unlike
Peskin's method, boundary forces are regarded as Lagrange multipliers that are
used to satisfy the no-slip condition. The incompressible Navier-Stokes
equations are discretized on an unbounded staggered Cartesian grid and are
solved in a finite number of operations using lattice Green's function
techniques. These techniques are used to automatically enforce the natural
free-space boundary conditions and to implement a novel block-wise adaptive
grid that significantly reduces the run-time cost of solutions by limiting
operations to grid cells in the immediate vicinity and near-wake region of the
immersed surface. These techniques also enable the construction of practical
discrete viscous integrating factors that are used in combination with
specialized half-explicit Runge-Kutta schemes to accurately and efficiently
solve the differential algebraic equations describing the discrete momentum
equation, incompressibility constraint, and no-slip constraint. Linear systems
of equations resulting from the time integration scheme are efficiently solved
using an approximation-free nested projection technique. The algebraic
properties of the discrete operators are used to reduce projection steps to
simple discrete elliptic problems, e.g. discrete Poisson problems, that are
compatible with recent parallel fast multipole methods for difference
equations. Numerical experiments on low-aspect-ratio flat plates and spheres at
Reynolds numbers up to 3,700 are used to verify the accuracy and physical
fidelity of the formulation.


title:
Micron-scale deformation: a coupled in-situ study of strain bursts and
  acoustic emission

abstract:
  Plastic deformation of micron-scale crystalline materials differ considerably
from bulk ones, because it is characterized by random strain bursts. To obtain
a detailed picture about this stochastic phenomenon, micron sized pillars have
been fabricated and compressed in the chamber of a SEM. An improved FIB
fabrication method is proposed to get non-tapered micro-pillars with a maximum
control over their shape. The in-situ compression device developed allows high
accuracy sample positioning and force/displacement measurements with high data
sampling rate. The collective avalanche-like motion of dislocations appears as
stress drops on the stress-strain curve. To confirm that these stress drops are
directly related to dislocation activity, and not to some other effect, an
acoustic emission transducer has been mounted under the sample to record
emitted acoustic activity during strain-controlled compression tests of Al-5\%
Mg micro-pillars. The correlation between the stress drops and the acoustic
emission signals indicates that indeed dislocation avalanches are responsible
for the stochastic character of the deformation process.


title:
Solar irradiance changes and phytoplankton productivity in Earth's ocean
  following astrophysical ionizing radiation events

abstract:
  Two atmospheric responses to simulated astrophysical ionizing radiation
events significant to life on Earth are production of odd-nitrogen species,
especially NO2, and subsequent depletion of stratospheric ozone. Ozone
depletion increases incident short-wavelength ultraviolet radiation (UVB,
280-315 nm) and longer ( > 600 nm) wavelengths of photosynthetically available
radiation (PAR, 400 -700 nm). On the other hand, the NO2 haze decreases
atmospheric transmission in the long-wavelength UVA (315-400 nm) and short
wavelength PAR. Here we use the results of previous simulations of incident
spectral irradiance following an ionizing radiation event to predict changes in
Terran productivity focusing on photosynthesis of marine phytoplankton. The
prediction is based on a spectral model of photosynthetic response developed
for the dominant genera in central regions of the ocean (Synechococcus and
Prochlorococcus), and remote-sensing based observations of spectral water
transparency, temperature, wind speed and mixed layer depth. Predicted
productivity declined after a simulated ionizing event, but the effect
integrated over the water column was small. For integrations taking into
account the full depth range of PAR transmission (down to 0.1% of utilizable
PAR), the decrease was at most 2-3% (depending on strain), with larger effects
(5-7%) for integrations just to the depth of the surface mixed layer. The
deeper integrations were most affected by the decreased utilizable PAR at depth
due to the NO2 haze, whereas shallower integrations were most affected by the
increased surface UV.

categories: astro-ph.EP astro-ph.HE physics.ao-ph q-bio.PE


title: Short periodic orbits theory for partially open quantum maps

abstract:
  We extend the semiclassical theory of short periodic orbits [Phys. Rev. E
{\bf 80}, 035202(R) (2009)] to partially open quantum maps. They correspond to
classical maps where the trajectories are partially bounced back due to a
finite reflectivity $R$. These maps are representative of a class that has many
experimental applications. The open scar functions are conveniently redefined,
providing a suitable tool for the investigation of these kind of systems. Our
theory is applied to the paradigmatic partially open tribaker map. We find that
the set of periodic orbits that belong to the classical repeller of the open
map ($R=0$) are able to support the set of long-lived resonances of the
partially open quantum map in a perturbative regime. By including the most
relevant trajectories outside of this set, the validity of the approximation is
extended to a broad range of $R$ values. Finally, we identify the details of
the transition from qualitatively open to qualitatively closed behaviour,
providing an explanation in terms of short periodic orbits.


title:
R-FUSE: Robust Fast Fusion of Multi-Band Images Based on Solving a
  Sylvester Equation

abstract:
  This paper proposes a robust fast multi-band image fusion method to merge a
high-spatial low-spectral resolution image and a low-spatial high-spectral
resolution image. Following the method recently developed in [1], the
generalized Sylvester matrix equation associated with the multi-band image
fusion problem is solved in a more robust and efficient way by exploiting the
Woodbury formula, avoiding any permutation operation in the frequency domain as
well as the blurring kernel invertibility assumption required in [1]. Thanks to
this improvement, the proposed algorithm requires fewer computational
operations and is also more robust with respect to the blurring kernel compared
with the one in [1]. The proposed new algorithm is tested with different priors
considered in [1]. Our conclusion is that the proposed fusion algorithm is more
robust than the one in [1] with a reduced computational cost.


title: Aggregating time preferences with decreasing impatience

abstract:
  It is well-known that for a group of time-consistent decision makers their
collective time preferences may become time-inconsistent. Jackson and Yariv
(2014) demonstrated that the result of aggregation of exponential discount
functions always exhibits present bias. We show that when preferences satisfy
the axioms of Fishburn and Rubinstein (1982), present bias is equivalent to
decreasing impatience (DI). Applying the notion of comparative DI introduced by
Prelec (2004), we generalize the result of Jackson and Yariv (2014). We prove
that the aggregation of distinct discount functions from comparable DI classes
results in the collective discount function which is strictly more DI than the
least DI of the functions being aggregated. We also prove an analogue of
Weitzman's (1998) result, for hyperbolic rather than exponential discount
functions. We show that if a decision maker is uncertain about her hyperbolic
discount rate, then long-term costs and benefits will be discounted at a rate
which is the probability-weighted harmonic mean of the possible hyperbolic
discount rates.


title: Note on algebro-geometric solutions to triangular Schlesinger systems

abstract:
  We construct algebro-geometric upper triangular solutions of rank two
Schlesinger systems. Using these solutions we derive two families of solutions
to the sixth Painlev\'e equation with parameters $({1}/{8}, -{1}/{8}, {1}/{8},
{3}/{8})$ expressed in simple forms using periods of differentials on elliptic
curves. Similarly for every integer $n$ different from $0$ and $-1$ we obtain
one family of solutions to the sixth Painlev\'e equation with parameters
$(\frac{9n^2+12n+4}{8}, -\frac{n^2}{8}, \frac{n^2}{8}, \frac{4-n^2}{8})$.


title:
Disorder is good for you: The influence of local disorder on strain
  localization and ductility of strain softening materials

abstract:
  We formulate a generic concept model for the deformation of a locally
disordered, macroscopically homogeneous material which undergoes irreversible
strain softening during plastic deformation. We investigate the influence of
the degree of microstructural heterogeneity and disorder on the concomitant
strain localization process (formation of a macroscopic shear band). It is
shown that increased microstructural heterogeneity delays strain localization
and leads to an increase of the plastic regime in the macroscopic stress-strain
curves. The evolving strain localization patterns are characterized and
compared to models of shear band formation published in the literature.


title:
Galaxy evolution in nearby galaxy groups. III. A GALEX view of NGC 5846,
  the largest group in the local universe

abstract:
  We explore the co-evolution of galaxies in nearby groups (V < 3000 km/s) with
a multi-wavelength approach. We analyze GALEX far-UV (FUV) and near-UV (NUV)
imaging and SDSS u,g,r,i,z data of groups spanning a large range of dynamical
phases. We characterize the photometric properties of
spectroscopically-confirmed galaxy members and investigate the global
properties of the groups through a dynamical analysis. Here we focus on NGC
5846, the third most massive association of Early-Type Galaxies (ETG) after the
Virgo and Fornax clusters. The group, composed of 90 members, is dominated by
ETGs (about 80 per cent), and among ETGs about 40\% are dwarfs. Results are
compared with those obtained for three groups in the LeoII cloud, which are
radically different both in member-galaxy population and dynamical properties.
The FUV-NUV cumulative colour distribution and the normalized UV luminosity
function (LF) significantly differ due to the different fraction of late-type
galaxy population. The UV LF of NGC 5846 resembles that of the Virgo cluster,
however our analysis suggests that star-formation episodes are still occurring
in most of the group galaxies, including ETGs. The NUV-i colour distribution,
the optical-UV colour-colour diagram, and NUV-r vs. Mr colour-magnitude
relation suggest that the gas contribution cannot be neglected in the evolution
of ETG-type group members. Our analysis highlights that NGC~5846 is still in an
active phase of its evolution, notwithstanding the dominance of dwarf and
bright ETGs and its virialized configuration.


title:
Cascades and Spectra of a Turbulent Spinodal Decomposition in 2D
  Symmetric Binary Liquid Mixture

abstract:
  We study the fundamental physics of cascades and spectra in 2D
Cahn-Hilliard-Navier-Stokes (CHNS) turbulence, and compare and contrast this
system with 2D MagnetoHydroDynamic (MHD) turbulence. The important similarities
include basic equations, ideal quadratic invariants, cascades and the role of
linear elastic waves. Surface tension induces elasticity, and the balance
between surface tension energy and turbulent kinetic energy determines a length
scale (Hinze scale) of the system. The Hinze scale may be thought of as the
scale of emergent critical balance between fluid straining and elastic
restoring forces. The scales between the Hinze scale and dissipation scale
constitute the elastic range of the 2D CHNS system. By direct numerical
simulation, we find that in the elastic range, the mean square concentration
spectrum $H^\psi_k$ of the 2D CHNS system exhibits the same power law ($-7/3$)
as the mean square magnetic potential spectrum $H^A_k$ in the inverse cascade
regime of 2D MHD. This power law is consistent with an inverse cascade of
$H^\psi$, which is observed. The kinetic energy spectrum of the 2D CHNS system
is $E^K_k\sim k^{-3}$ if forced at large scale, suggestive of the direct
enstrophy cascade power law of 2D Navier-Stokes (NS) turbulence. The difference
from the energy spectra of 2D MHD turbulence implies that the back reaction of
the concentration field to fluid motion is limited. We suggest this is because
the surface tension back reaction is significant only in the interfacial
regions. The interfacial regions fill only a small portion of the 2D CHNS
system, and their interface packing fraction is much smaller than that for 2D
MHD.


title:
The statistical significance of multivariate Hawkes processes fitted to
  limit order book data

abstract:
  Hawkes processes have seen a number of applications in finance, due to their
ability to capture event clustering behaviour typically observed in financial
systems. Given a calibrated Hawkes process, of concern is the statistical fit
to empirical data, particularly for the accurate quantification of self- and
mutual-excitation effects. We investigate the application of a multivariate
Hawkes process with a sum-of-exponentials kernel and piecewise-linear
exogeneity factors, fitted to liquidity demand and replenishment events
extracted from limit order book data. We consider one-, two- and
three-exponential kernels, applying various tests to ascertain goodness-of-fit
and stationarity of residuals, as well as stability of the calibration
procedure. In line with prior research, it is found that performance across all
tests improves as the number of exponentials is increased, with a
sum-of-three-exponentials yielding the best fit to the given set of coupled
point processes.


title: Search for solar axions with CsI(Tl) crystal detectors

abstract:
  The results of a search for solar axions from the Korea Invisible Mass Search
(KIMS) experiment at the Yangyang Underground Laboratory are presented.
Low-energy electron-recoil events would be produced by conversion of solar
axions into electrons via the axio-electric effect in CsI(Tl) crystals. Using
data from an exposure of 34,596 $\rm kg \cdot days$, we set a 90 \% confidence
level upper limit on the axion-electron coupling, $g_{ae}$, of $1.39 \times
10^{-11}$ for an axion mass less than 1 keV/$\rm c^2$. This limit is lower than
the indirect solar neutrino bound, and fully excludes QCD axions heavier than
0.48 eV/$\rm c^2$ and 140.9 eV/$\rm c^2$ for the DFSZ and KSVZ models
respectively.


title: Multi-shell model of ion-induced nucleic acid condensation

abstract:
  We present a semi-quantitative model of condensation of short nucleic acid
(NA) duplexes induced by tri-valent cobalt(III) hexammine (CoHex) ions. The
model is based on partitioning of bound counterion distribution around singleNA
duplex into "external" and "internal" ion binding shells distinguished by the
proximity to duplex helical axis. In the aggregated phase the shells overlap,
which leads to significantly increased attraction of CoHex ions in these
overlaps with the neighboring duplexes. The duplex aggregation free energy is
decomposed into attractive and repulsive components in such a way that they can
be represented by simple analytical expressions with parameters derived from
molecular dynamic (MD) simulations and numerical solutions of Poisson equation.
The short-range interactions described by the attractive term depend on the
fractions of bound ions in the overlapping shells and affinity of CoHex to the
"external" shell of nearly neutralized duplex. The repulsive components of the
free energy are duplex configurational entropy loss upon the aggregation and
the electrostatic repulsion of the duplexes that remains after neutralization
by bound CoHex ions. The estimates of the aggregation free energy are
consistent with the experimental range of NA duplex condensation propensities,
including the unusually poor condensation of RNA structures and subtle sequence
effects upon DNA condensation. The model predicts that, in contrast to DNA, RNA
duplexes may condense into tighter packed aggregates with a higher degree of
duplex neutralization. The model also predicts that longer NA fragments will
condense more readily than shorter ones. The ability of this model to explain
experimentally observed trends in NA condensation, lends support to proposed NA
condensation picture based on the multivalent "ion binding shells".


title: Exploiting Semantic Information and Deep Matching for Optical Flow

abstract:
  We tackle the problem of estimating optical flow from a monocular camera in
the context of autonomous driving. We build on the observation that the scene
is typically composed of a static background, as well as a relatively small
number of traffic participants which move rigidly in 3D. We propose to estimate
the traffic participants using instance-level segmentation. For each traffic
participant, we use the epipolar constraints that govern each independent
motion for faster and more accurate estimation. Our second contribution is a
new convolutional net that learns to perform flow matching, and is able to
estimate the uncertainty of its matches. This is a core element of our flow
estimation pipeline. We demonstrate the effectiveness of our approach in the
challenging KITTI 2015 flow benchmark, and show that our approach outperforms
published approaches by a large margin.


title: Differential TD Learning for Value Function Approximation

abstract:
  Value functions arise as a component of algorithms as well as performance
metrics in statistics and engineering applications. Computation of the
associated Bellman equations is numerically challenging in all but a few
special cases. A popular approximation technique is known as Temporal
Difference (TD) learning. The algorithm introduced in this paper is intended to
resolve two well-known problems with this approach: In the discounted-cost
setting, the variance of the algorithm diverges as the discount factor
approaches unity. Second, for the average cost setting, unbiased algorithms
exist only in special cases. It is shown that the gradient of any of these
value functions admits a representation that lends itself to algorithm design.
Based on this result, the new differential TD method is obtained for Markovian
models on Euclidean space with smooth dynamics. Numerical examples show
remarkable improvements in performance. In application to speed scaling,
variance is reduced by two orders of magnitude.


title:
The Raspberry model for protein-like particles: ellipsoids and
  confinement in cylindrical pores

abstract:
  The study of protein mass transport via atomistic simulation requires time
and length scales beyond the computational capabilities of modern computer
systems. The raspberry model for colloidal particles in combination with the
mesoscopic hydrodynamic method of lattice Boltzmann facilitates coarse-grained
simulations that are on the order of microseconds and hundreds of nanometers
for the study of diffusive transport of protein-like colloid particles. The
raspberry model reproduces linearity in resistance to motion versus particle
size and correct enhanced drag within cylindrical pores at off-center
coordinates for spherical particles. Owing to the high aspect ratio of many
proteins, ellipsoidal raspberry colloid particles were constructed and
reproduced the geometric resistance factors of Perrin and of Happel and Brenner
in the laboratory-frame and in the moving body-frame. Accurate body-frame
rotations during diffusive motion have been captured for the first time using
projections of displacements.


title: Extraction of Cosmological Information from WiggleZ

abstract:
  In this thesis, I analyse the 2D anisotropic Baryon Acoustic Oscillation
(BAO) signal present in the final WiggleZ dataset. I utilise newly released
covariance matrices from the WizCOLA simulations and follow well tested
methodologies used in prior analyses of the BAO signal in alternative datasets.
The WiggleZ data is presented in two forms - in multipole expansion and in data
wedges - both of which are analysed in this thesis. I test my model against
previous one dimensional analyses of the BAO signal in the WiggleZ data and
against WizCOLA simulations, and find it to be free of bias or systematic
offsets. However, the analysis on the wedge data format was unable to properly
constrain cosmological parameters, and thus discarded in favour of the
multipole analysis. The multipole analysis determined $\Omega_c h^2$, $H(z)$
and $D_A(z)$ for three redshift bins, of effective redshifts $z = 0.44, 0.60$
and $0.73$. The respective constraints on $\Omega_c h^2$ are
$0.119^{+0.029}_{-0.026}$, $0.151^{+0.038}_{-0.025}$ and
$0.140^{+0.036}_{-0.022}$. The fits for $H(z)$ are respectively $87 \pm 16$,
$90 \pm 15$ and $82 \pm 13$ km s$^{-1}$ Mpc$^{-1}$, and for $D_A(z)$ I find
values of $1300 \pm 160$, $1300 \pm 180$ and $1350 \pm 160$ Mpc. These
cosmological constraints are consistent with Flat $\Lambda$CDM cosmology.


title: The Sobolev stability threshold for 2D shear flows near Couette

abstract:
  We consider the 2D Navier-Stokes equation on $\mathbb T \times \mathbb R$,
with initial datum that is $\varepsilon$-close in $H^N$ to a shear flow
$(U(y),0)$, where $\| U(y) - y\|_{H^{N+4}} \ll 1$ and $N>1$. We prove that if
$\varepsilon \ll \nu^{1/2}$, where $\nu$ denotes the inverse Reynolds number,
then the solution of the Navier-Stokes equation remains $\varepsilon$-close in
$H^1$ to $(e^{t \nu \partial_{yy}}U(y),0)$ for all $t>0$. Moreover, the
solution converges to a decaying shear flow for times $t \gg \nu^{-1/3}$ by a
mixing-enhanced dissipation effect, and experiences a transient growth of
gradients. In particular, this shows that the stability threshold in finite
regularity scales no worse than $\nu^{1/2}$ for 2D shear flows close to the
Couette flow.


title:
Comment on "More on Heisenberg's model for high energy nucleon-nucleon
  scattering"

abstract:
  We comment on the treatment of asymptotic black-disk scattering in a recent
paper of Nastase and Sonnenschein, Phys.\ Rev.\ D\ {\bf 92}, 015028 (2015), on
scattering in an updated version of the Heisenberg model which gives $pp$ and
$\bar{p}p$ cross sections which increase at very high energies as $\ln^2s$. We
show that the total cross section they define does not correspond to that
measured in experiments, with the result that their limit for the ratio
$\sigma_{\rm elas}/\sigma_{\rm tot}$ is too small by a factor 2. The correct
ratio for black-disk scattering, $\sigma_{\rm elas}/\sigma_{\rm tot}
\rightarrow 1/2$ for $s\rightarrow\infty$, is strongly supported by experiment.


title: System for Filtering Messages on Social Media Content

abstract:
  The social networking era has left us with little privacy. The details of the
social network users are published on Social Networking sites. Vulnerability
has reached new heights due to the overpowering effects of social networking.
The sites like Facebook, Twitter are having a huge set of users who publish
their files, comments, messages in other users walls. These messages and
comments could be of any nature. Even friends could post a comment that would
harm a persons integrity. Thus there has to be a system which will monitor the
messages and comments that are posted on the walls. If the messages are found
to be neutral (does not have any harmful content), then it can be published. If
the messages are found to have non-neutral content in them, then these messages
would be blocked by the social network manager. The messages that are
non-neutral would be of sexual, offensive, hatred, pun intended nature. Thus
the social network manager can classify content as neutral and non-neutral and
notify the user if there seems to be messages of non-neutral behavior.


title: Quartz-superconductor quantum electromechanical system

abstract:
  We propose and analyse a quantum electromechanical system composed of a
monolithic quartz bulk acoustic wave (BAW) oscillator coupled to a
superconducting transmon qubit via an intermediate LC electrical circuit.
Monolithic quartz oscillators offer unprecedentedly high effective masses and
quality factors for the investigation of mechanical oscillators in the quantum
regime. Ground-state cooling of such mechanical modes via resonant
piezoelectric coupling to an LC circuit, which is itself sideband cooled via
coupling to a transmon qubit, is shown to be feasible. The fluorescence
spectrum of the qubit, containing motional sideband contributions due to the
couplings to the oscillator modes, is obtained and the imprint of the
electromechanical steady-state on the spectrum is determined. This allows the
qubit to function both as a cooling resource for, and transducer of, the
mechanical oscillator. The results described are relevant to any hybrid quantum
system composed of a qubit coupled to two (coupled or uncoupled) thermal
oscillator modes.


title:
Exploiting Full-duplex Receivers for Achieving Secret Communications in
  Multiuser MISO Networks

abstract:
  We consider a broadcast channel, in which a multi-antenna transmitter (Alice)
sends $K$ confidential information signals to $K$ legitimate users (Bobs) in
the presence of $L$ eavesdroppers (Eves). Alice uses MIMO precoding to generate
the information signals along with her own (Tx-based) friendly jamming.
Interference at each Bob is removed by MIMO zero-forcing. This, however, leaves
a "vulnerability region" around each Bob, which can be exploited by a nearby
Eve. We address this problem by augmenting Tx-based friendly jamming (TxFJ)
with Rx-based friendly jamming (RxFJ), generated by each Bob. Specifically,
each Bob uses self-interference suppression (SIS) to transmit a friendly
jamming signal while simultaneously receiving an information signal over the
same channel. We minimize the powers allocated to the information, TxFJ, and
RxFJ signals under given guarantees on the individual secrecy rate for each
Bob. The problem is solved for the cases when the eavesdropper's channel state
information is known/unknown. Simulations show the effectiveness of the
proposed solution. Furthermore, we discuss how to schedule transmissions when
the rate requirements need to be satisfied on average rather than
instantaneously. Under special cases, a scheduling algorithm that serves only
the strongest receivers is shown to outperform the one that schedules all
receivers.


title: Radial Limits of Capillary Surfaces at Corners

abstract:
  Consider a solution $f\in C^{2}(\Omega)$ of a prescribed mean curvature
equation \[ {\rm div}\left(\frac{\nabla f}{\sqrt{1+|\nabla
f|^{2}}}\right)=2H(x,f) \ \ \ \ {\rm in} \ \ \Omega\subset R^{2}, \] where
$\Omega$ is a domain whose boundary has a corner at ${\cal
O}=(0,0)\in\partial\Omega$ and the angular measure of this corner is $2\alpha,$
for some $\alpha\in (0,\pi).$ Suppose $\sup_{x\in\Omega} |f(x)|$ and
$\sup_{x\in\Omega} |H(x,f(x))|$ are both finite. If $\alpha>\frac{\pi}{2},$
then the (nontangential) radial limits of $f$ at ${\cal O},$ \[ Rf(\theta) =
\lim_{r\downarrow 0} f(r\cos(\theta),r\sin(\theta)), \] were recently proven by
the authors to exist, independent of the boundary behavior of $f$ on
$\partial\Omega,$ and to have a specific type of behavior.
  Suppose $\alpha\in \left(\frac{\pi}{4},\frac{\pi}{2}\right],$ the contact
angle $\gamma(\cdot)$ that the graph of $f$ makes with one side of
$\partial\Omega$ has a limit (denoted $\gamma_{2}$) at ${\cal O}$ and \[
\pi-2\alpha < \gamma_{2} <2\alpha. \] We prove that the (nontangential) radial
limits of $f$ at ${\cal O}$ exist and the radial limits have a specific type of
behavior, independent of the boundary behavior of $f$ on the other side of
$\partial\Omega.$ We also discuss the case $\alpha\in
\left(0,\frac{\pi}{2}\right].$


title:
Inflation and Acceleration of the Universe by Nonlinear Magnetic
  Monopole Fields

abstract:
  Despite impressive phenomenological successes, cosmological models are
incomplete without an understanding of what happened at the big bang
singularity. Maxwell electrodynamics, considered as a source of the classical
Einstein field equations, leads to the singular isotropic Friedmann solutions.
In the context of Friedmann-Robertson-Walker (FRW) spacetime, we show that
singular behavior does not occur for a class of nonlinear generalizations of
the electromagnetic theory for strong fields. A new mathematical model is
proposed for which the analytical nonsingular extension of FRW solutions is
obtained by using the nonlinear magnetic monopole fields.


title: Tropical Homology

abstract:
  Given a tropical variety X and two non-negative integers p and q we define
homology group $H_{p,q}(X)$. We show that if X is a smooth tropical variety
that can be represented as the tropical limit of a 1-parameter family of
complex projective varieties, then $\dim H_{p,q}(X)$ coincides with the Hodge
number $h^{p,q}$ of a general member of the family.


title: Clustering Via Crowdsourcing

abstract:
  In recent years, crowdsourcing, aka human aided computation has emerged as an
effective platform for solving problems that are considered complex for
machines alone. Using human is time-consuming and costly due to monetary
compensations. Therefore, a crowd based algorithm must judiciously use any
information computed through an automated process, and ask minimum number of
questions to the crowd adaptively.
  One such problem which has received significant attention is {\em entity
resolution}. Formally, we are given a graph $G=(V,E)$ with unknown edge set $E$
where $G$ is a union of $k$ (again unknown, but typically large $O(n^\alpha)$,
for $\alpha>0$) disjoint cliques $G_i(V_i, E_i)$, $i =1, \dots, k$. The goal is
to retrieve the sets $V_i$s by making minimum number of pair-wise queries $V
\times V\to\{\pm1\}$ to an oracle (the crowd). When the answer to each query is
correct, e.g. via resampling, then this reduces to finding connected components
in a graph. On the other hand, when crowd answers may be incorrect, it
corresponds to clustering over minimum number of noisy inputs. Even, with
perfect answers, a simple lower and upper bound of $\Theta(nk)$ on query
complexity can be shown. A major contribution of this paper is to reduce the
query complexity to linear or even sublinear in $n$ when mild side information
is provided by a machine, and even in presence of crowd errors which are not
correctable via resampling. We develop new information theoretic lower bounds
on the query complexity of clustering with side information and errors, and our
upper bounds closely match with them. Our algorithms are naturally
parallelizable, and also give near-optimal bounds on the number of adaptive
rounds required to match the query complexity.