title:
Ultrahigh Dimensional Feature Selection via Kernel Canonical Correlation
  Analysis

abstract:
  High-dimensional variable selection is an important issue in many scientific
fields, such as genomics. In this paper, we develop a sure independence feature
screening pro- cedure based on kernel canonical correlation analysis (KCCA-SIS,
for short). KCCA- SIS is easy to be implemented and applied. Compared to the
sure independence screen- ing procedure based on the Pearson correlation (SIS,
for short) developed by Fan and Lv [2008], KCCA-SIS can handle nonlinear
dependencies among variables. Compared to the sure independence screening
procedure based on the distance correlation (DC- SIS, for short) proposed by Li
et al. [2012], KCCA-SIS is scale free, distribution free and has better
approximation results based on the universal characteristic of Gaussian Kernel
(Micchelli et al. [2006]). KCCA-SIS is more general than SIS and DC-SIS in the
sense that SIS and DC-SIS correspond to certain choice of kernels. Compared to
supremum of Hilbert Schmidt independence criterion-Sure independence screening
(sup-HSIC-SIS, for short) developed by Balasubramanian et al. [2013], KCCA-SIS
is scale free removing the marginal variation of features and response
variables. No model assumption is needed between response and predictors to
apply KCCA-SIS and it can be used in ultrahigh dimensional data analysis.
Similar to DC-SIS and sup- HSIC-SIS, KCCA-SIS can also be used directly to
screen grouped predictors and for multivariate response variables. We show that
KCCA-SIS has the sure screening prop- erty, and has better performance through
simulation studies. We applied KCCA-SIS to study Autism genes in a
spatiotemporal gene expression dataset for human brain development, and
obtained better results based on gene ontology enrichment analysis comparing to
the other existing methods.


title: Limitations of cosmography in extended theories of gravity

abstract:
  The cosmographic approach, which only relies upon the homogeneity and
isotropy of the Universe on large scales, has become an essential tool in
dealing with an increasing number of theoretical possibilities for explaining
the late-time acceleration of the Universe, ranging from Modified Gravity
theories to Dark Energy alternatives passing from testing the cosmological
concordance Lambda-CDM model. Despite its generality, we show that this method
has a number of shortcomings when trying to adequately reconstruct theories
with higher-order derivatives in either the gravitational or the matter sector.
Herein some paradigmatic examples of such an inability, explanations of the
limitations and prospective cures will be presented.


title: Fast nonlinear embeddings via structured matrices

abstract:
  We present a new paradigm for speeding up randomized computations of several
frequently used functions in machine learning. In particular, our paradigm can
be applied for improving computations of kernels based on random embeddings.
Above that, the presented framework covers multivariate randomized functions.
As a byproduct, we propose an algorithmic approach that also leads to a
significant reduction of space complexity. Our method is based on careful
recycling of Gaussian vectors into structured matrices that share properties of
fully random matrices. The quality of the proposed structured approach follows
from combinatorial properties of the graphs encoding correlations between rows
of these structured matrices. Our framework covers as special cases already
known structured approaches such as the Fast Johnson-Lindenstrauss Transform,
but is much more general since it can be applied also to highly nonlinear
embeddings. We provide strong concentration results showing the quality of the
presented paradigm.


title: Fermions in five-dimensional brane world models

abstract:
  In the present paper the fermion fields, living in the background of
five-dimensional warped brane world models with compact extra dimension, are
thoroughly examined. The Kaluza-Klein decomposition and isolation of the
physical degrees of freedom is performed for those five-dimensional fermion
field Lagrangians, which admit such a decomposition to be performed in a
mathematically consistent way and provide a physically reasonable
four-dimensional effective theory. It is also shown that for the majority of
five-dimensional fermion field Lagrangians there are no (at least rather
obvious) ways to perform the Kaluza-Klein decomposition consistently. Moreover,
in these cases one may expect the appearance of various pathologies in the
four-dimensional effective theory. Among the cases, for which the Kaluza-Klein
decomposition can be performed in a mathematically consistent way, the case,
which reproduces the Standard Model by the zero Kaluza-Klein modes most closely
regardless of the size of the extra dimension, is examined in detail in the
background of the Randall-Sundrum model.


title: New Physics at the TeV Scale

abstract:
  The Standard Model of particle physics is assumed to be a low-energy
effective theory with new physics theoretically motivated to be around TeV
scale. The dissertation presents theories with new physics beyond the Standard
Model at the TeV scale testable in the current High Energy Colliders. The study
on leptoquarks gauge bosons in reference to TopSU(5) model in chapter 2 showed
that their discovery mass range extends upto 1.5 TeV at 14 TeV LHC with
luminosity of 100 $fb^{-1}$. On the other hand, in chapter 3 we studied the
collider phenomenology of TeV scale mirror fermions in Left-Right Mirror model
finding that the reaches for the mirror quarks goes upto $750$ GeV at the $14$
TeV LHC with $~300 ~fb^{-1}$ luminosity. In chapter 4 we have enlarged the
bosonic symmetry to fermi-bose symmetry e.g. supersymmetry and have shown that
SUSY with non-universalities in gaugino or scalar masses within high scale
SUGRA set up can still be accessible at LHC with 14 TeV. In chapter 5, we
performed a study in respect to the $e^+e^-$ collider and find that precise
measurements of the higgs boson mass splittings upto $\sim 100$ MeV may be
possible with high luminosity in the International Linear Collider (ILC). In
chapter 6 we have shown that the experimental data on neutrino masses and
mixings are consistent with the proposed 4/5 parameter Dirac neutrino models
yielding a solution for the neutrino masses with inverted mass hierarchy and
large CP violating phase $\delta$ and thus can be tested experimentally.
Chapter 7 incorporates a warm dark matter candidate in context of two Higgs
doublet model. The model has several testable consequences at LHC. This
dissertation presents an endeavor to study beyond standard model (BSM) physics
at the TeV scale with testable signals in the Colliders.


title:
Fast approximation algorithms for $p$-centres in large
  $\delta$-hyperbolic graphs

abstract:
  We provide a quasilinear time algorithm for the $p$-center problem with an
additive error less than or equal to 3 times the input graph's hyperbolic
constant. Specifically, for the graph $G=(V,E)$ with $n$ vertices, $m$ edges
and hyperbolic constant $\delta$, we construct an algorithm for $p$-centers in
time $O(p(\delta+1)(n+m)\log(n))$ with radius not exceeding $r_p + \delta$ when
$p \leq 2$ and $r_p + 3\delta$ when $p \geq 3$, where $r_p$ are the optimal
radii. Prior work identified $p$-centers with accuracy $r_p+\delta$ but with
time complexity $O((n^3\log n + n^2m)\log(diam(G)))$ which is impractical for
large graphs.


title:
Attributes for Improved Attributes: A Multi-Task Network for Attribute
  Classification

abstract:
  Attributes, or semantic features, have gained popularity in the past few
years in domains ranging from activity recognition in video to face
verification. Improving the accuracy of attribute classifiers is an important
first step in any application which uses these attributes. In most works to
date, attributes have been considered to be independent. However, we know this
not to be the case. Many attributes are very strongly related, such as heavy
makeup and wearing lipstick. We propose to take advantage of attribute
relationships in three ways: by using a multi-task deep convolutional neural
network (MCNN) sharing the lowest layers amongst all attributes, sharing the
higher layers for related attributes, and by building an auxiliary network on
top of the MCNN which utilizes the scores from all attributes to improve the
final classification of each attribute. We demonstrate the effectiveness of our
method by producing results on two challenging publicly available datasets.


title:
Persistence Lenses: Segmentation, Simplification, Vectorization, Scale
  Space and Fractal Analysis of Images

abstract:
  A persistence lens is a hierarchy of disjoint upper and lower level sets of a
continuous luminance image's Reeb graph. The boundary components of a
persistence lens's interior components are Jordan curves that serve as a
hierarchical segmentation of the image, and may be rendered as vector graphics.
A persistence lens determines a varilet basis for the luminance image, in which
image simplification is a realized by subspace projection. Image scale space,
and image fractal analysis, result from applying a scale measure to each basis
function.


title:
[CII] 158$\mu$m and [NII] 205$\mu$m emission from IC 342 - Disentangling
  the emission from ionized and photo-dissociated regions

abstract:
  Aims: We investigate how much of the [CII] emission in the nucleus of the
nearby spiral galaxy IC 342 is contributed by PDRs and by the ionized gas. We
examine the spatial variations of starburst/PDR activity and study the
correlation of the [CII] line with the [NII] 205{\textmu}m emission line coming
exclusively from the HII regions. Methods: We present small maps of [CII] and
[NII] lines recently observed with the GREAT receiver on board SOFIA. In
particular we present a super-resolution method to derive how unresolved,
kinematically correlated structures in the beam contribute to the observed line
shapes. Results: We find that the emission coming from the ionized gas shows a
kinematic component in addition to the general Doppler signature of the
molecular gas. We interpret this as the signature of two bi-polar lobes of
ionized gas expanding out of the galactic plane. We then show how this requires
an adaptation of our understanding of the geometrical structure of the nucleus
of IC~342. Examining the starburst activity we find ratios
$I([CII])/I(^{12}\mathrm{CO} (1-0))$ between 400 and 1800 in energy units.
Applying predictions from numerical models of HII and PDR regions to derive the
contribution from the ionized phase to the total [CII] emission we find that
35-90% of the observed [CII] intensity stems from the ionized gas if both
phases contribute. Averaged over the central few hundred parsec we find for the
[CII] contribution a HII-to-PDR ratio of 70:30. Conclusions: The ionized gas in
the center of IC 342 contributes more strongly to the overall [CII] emission
than is commonly observed on larger scales and than is predicted. Kinematic
analysis shows that the majority of the [CII] emission is related to the strong
but embedded star formation in the nuclear molecular ring and only marginally
emitted from the expanding bi-polar lobes of ionized gas.


title:
Efficient estimation of probability of conflict between air traffic
  using Subset Simulation

abstract:
  This paper presents an efficient method for estimating the probability of
conflict between air traffic within a block of airspace. Autonomous
Sense-and-Avoid is an essential safety feature to enable Unmanned Air Systems
to operate alongside other (manned or unmanned) air traffic. The ability to
estimate probability of conflict between traffic is an essential part of
Sense-and-Avoid. Such probabilities are typically very low. Evaluating low
probabilities using naive Direct Monte Carlo generates a significant
computational load. This paper applies a technique called Subset Simulation.
The small failure probabilities are computed as a product of larger conditional
failure probabilities, reducing the computational load whilst improving the
accuracy of the probability estimates. The reduction in the number of samples
required can be one or more orders of magnitude. The utility of the approach is
demonstrated by modeling a series of conflicting and potentially conflicting
scenarios based on the standard Rules of the Air.


title:
Ultraviolet emission lines of Si II in quasars --- investigating the "Si
  II disaster"

abstract:
  The observed line intensity ratios of the Si II 1263 and 1307 \AA\ multiplets
to that of Si II 1814\,\AA\ in the broad line region of quasars are both an
order of magnitude larger than the theoretical values. This was first pointed
out by Baldwin et al. (1996), who termed it the "Si II disaster", and it has
remained unresolved. We investigate the problem in the light of newly-published
atomic data for Si II. Specifically, we perform broad line region calculations
using several different atomic datasets within the CLOUDY modeling code under
optically thick quasar cloud conditions. In addition, we test for selective
pumping by the source photons or intrinsic galactic reddening as possible
causes for the discrepancy, and also consider blending with other species.
However, we find that none of the options investigated resolves the Si II
disaster, with the potential exception of microturbulent velocity broadening
and line blending. We find that a larger microturbulent velocity ($\sim 500 \rm
\, kms^{-1}$) may solve the Si II disaster through continuum pumping and other
effects. The CLOUDY models indicate strong blending of the Si II 1307 \AA\
multiplet with emission lines of O I, although the predicted degree of blending
is incompatible with the observed 1263/1307 intensity ratios. Clearly, more
work is required on the quasar modelling of not just the Si II lines but also
nearby transitions (in particular those of O I) to fully investigate if
blending may be responsible for the Si II disaster.


title: An operator basis for the Standard Model with an added scalar singlet

abstract:
  Motivated by the possible di-gamma resonance at 750 GeV, we present a basis
of effective operators for the Standard Model plus a scalar singlet at
dimensions 5, 6, and 7. We point out that an earlier list at dimensions 5 and 6
contains two redundant operators at dimension 5.


title:
A unifying asymptotic approach for nonadiabatic transitions near pairs
  of real or complex turning points

abstract:
  An asymptotic approach for a Schroedinger type equation with non selfadjoint
Hamiltonian of a special type in the case of two close degeneracy (turning)
points is developed. Both real and complex degeneracy points are treated by a
method of matched asymptotic expansions in the context of a unifying approach.
An asymptotic expansion near degeneracy point containing the parabolic cylinder
functions is constructed and the transition matrix connecting the coefficients
of adiabatic modes in front of and behind the degeneracy point is derived.
  A simple non-technical recipe is also provided, which enables one to apply
results to different physical problems without performing intermediate
calculations.


title: Ultimate precision bound of quantum and sub-wavelength imaging

abstract:
  We determine the ultimate potential of quantum imaging for boosting the
resolution of a far-field, diffraction-limited, linear imaging device within
the paraxial approximation. First we show that the problem of estimating the
separation between two point-like sources is equivalent to the estimation of
the loss parameters of two lossy bosonic channels, i.e., the transmissivities
of two beam splitters. Using this representation, we establish the ultimate
precision bound for resolving two point-like sources in an arbitrary quantum
state, with a simple formula for the specific case of two thermal sources. We
find that the precision bound scales with the number of collected photons
according to the standard quantum limit. Then we determine the sources whose
separation can be estimated optimally, finding that quantum-correlated sources
(entangled or discordant) can be super-resolved at the sub-Rayleigh scale. Our
results set the upper bounds on any present or future imaging technology, from
astronomical observation to microscopy, which is based on quantum detection as
well as source engineering.


title: Analog computing by Brewster effect

abstract:
  Optical computing has emerged as a promising candidate for real-time and
parallel continuous data processing. Motivated by recent progresses in
metamaterial-based analog computing [Science 343, 160 (2014)], we theoretically
investigate realization of two-dimensional complex mathematical operations
using rotated configurations, recently reported in [Opt. Lett. 39, 1278
(2014)]. Breaking the reflection symmetry, such configurations could realize
both even and odd Green's functions associated with spatial operators. Based on
such appealing theory and by using Brewster effect, we demonstrate realization
of a first-order differentiator. Such efficient wave-based computation method
not only circumvents the major potential drawbacks of metamaterials, but also
offers the most compact possible device compared to the conventional bulky
lens-based optical signal and data processors.


title: Note on the physical basis of spatially resolved thermodynamic functions

abstract:
  The spatial resolution of extensive thermodynamic functions is discussed. A
physical definition of the spatial resolution based on a spatial analogy of
partial molar quantities is advocated, which is shown to be consistent with how
hydration energies are typically spatially resolved in the molecular simulation
literature. It is then shown that, provided the solvent is not at a phase
transition, the spatially resolved entropy function calculated by first-order
grid inhomogeneous solvation theory (Nguyen et al. J. Chem. Phys., 137, 044101
[2012]) satisfies the definition rigorously, whereas that calculated by grid
cell theory (Gerogiokas et al., J. Chem. Theory Comput., 10, 35 [2014]) most
likely does not. Moreover, for an ideal gas in an external field, the former
theory is shown consistent in the limit of weak field or high temperature
whereas the latter is not. Finally, consistent with the proposed definition and
with the case of an ideal gas in an external field, we derive an approximate
expression for the solvent contribution to the free energy of solvation in the
limit of infinite dilution from the spatial variation of the density around the
solute.


title: Parsing Argumentation Structures in Persuasive Essays

abstract:
  In this article, we present a novel approach for parsing argumentation
structures. We identify argument components using sequence labeling at the
token level and apply a new joint model for detecting argumentation structures.
The proposed model globally optimizes argument component types and
argumentative relations using integer linear programming. We show that our
model considerably improves the performance of base classifiers and
significantly outperforms challenging heuristic baselines. Moreover, we
introduce a novel corpus of persuasive essays annotated with argumentation
structures. We show that our annotation scheme and annotation guidelines
successfully guide human annotators to substantial agreement. This corpus and
the annotation guidelines are freely available for ensuring reproducibility and
to encourage future research in computational argumentation.


title:
Do the Hard Stuff First: Scheduling Dependent Computations in
  Data-Analytics Clusters

abstract:
  We present a scheduler that improves cluster utilization and job completion
times by packing tasks having multi-resource requirements and
inter-dependencies. While the problem is algorithmically very hard, we achieve
near-optimality on the job DAGs that appear in production clusters at a large
enterprise and in benchmarks such as TPC-DS. A key insight is that carefully
handling the long-running tasks and those with tough-to-pack resource needs
will produce good-enough schedules. However, which subset of tasks to treat
carefully is not clear (and intractable to discover). Hence, we offer a search
procedure that evaluates various possibilities and outputs a preferred schedule
order over tasks. An online component enforces the schedule orders desired by
the various jobs running on the cluster. In addition, it packs tasks, overbooks
the fungible resources and guarantees bounded unfairness for a variety of
desirable fairness schemes. Relative to the state-of-the art schedulers, we
speed up 50% of the jobs by over 30% each.


title: Local noise in a diffusive conductor

abstract:
  The control and measurement of local non-equilibrium configurations is of
utmost importance in applications on energy harvesting, thermoelectrics and
heat management in nano-electronics. This challenging task can be achieved with
the help of various local probes, prominent examples including superconducting
or quantum dot based tunnel junctions, classical and quantum resistors, and
Raman thermography. Beyond time-averaged properties, valuable information can
also be gained from spontaneous fluctuations of current (noise). From these
perspective, however, a fundamental constraint is set by current conservation,
which makes noise a characteristic of the whole conductor, rather than some
part of it. Here we demonstrate how to remove this obstacle and pick up a local
noise temperature of a current biased diffusive conductor with the help of a
miniature noise probe. This approach is virtually noninvasive and extends
primary local measurements towards strongly non-equilibrium regimes.


title: Decay of Bogoliubov excitations in one-dimensional Bose gases

abstract:
  We study the decay of Bogoliubov quasiparticles in one-dimensional Bose
gases. Starting from the hydrodynamic Hamiltonian, we develop a microscopic
theory that enables one to systematically study both the excitations and their
decay. At zero temperature, the leading mechanism of decay of a quasiparticle
is disintegration into three others. We find that low-energy quasiparticles
(phonons) decay with the rate that scales with the seventh power of momentum,
whereas the rate of decay of the high-energy quasiparticles does not depend on
momentum. In addition, our approach allows us to study analytically the
quasiparticle decay in the whole crossover region between the two limiting
cases. When applied to integrable models, including the Lieb-Liniger model of
bosons with contact repulsion, our theory confirms the absence of the decay of
quasiparticle excitations. We account for two types of integrability-breaking
perturbations that enable finite decay: three-body interaction between the
bosons and two-body interaction of finite range.


title: Small Entangled Quantum Worlds with a Simple Structure

abstract:
  We introduce the notion of a small quantum world (SQW) , which in our
opinion, is very helpful in the situations when an experimenter's tools for
preparing quantum states and (or) for measuring the observables of a quantum
system under study are restricted due to some kind of reasons. In this case it
is advisable to use as original an appropriate subspace of complete Hilbert
space of states and respectively to utilize observables acting only in this
subspace. If this subspace possesses some additional symmetries, the structure
of a pure states set, as a rule, is simpler by far than in general case.
Moreover in such SQWs some specific irreducible entangled states may appear.
The similar states could be very helpful in various tasks connected with
quantum informational applications. In the present paper main ideas outlined
above are developed in detail in the simple and instructive case of a two-qubit
system in which the accessible space of states possesses the additional
symmetry structure of permutation group of three elements.


title:
Dynamic characterizations of quasi-isometry, and applications to
  cohomology

abstract:
  We build a bridge between geometric group theory and topological dynamical
systems by establishing a dictionary between coarse equivalence and continuous
orbit equivalence. As an application, we give conceptual explanations for
previous results of Shalom and Sauer on coarse invariance of homological and
cohomological dimensions and Shalom's property $H_{FD}$. As another
application, we show that group homology and cohomology in a class of
coefficients, including all induced and co-induced modules, are coarse
invariants. We deduce that being of type $FP_n$ (over arbitrary rings) is a
coarse invariant, and that being a (Poincar\'e) duality group over a ring is a
coarse invariant among all groups which have finite cohomological dimension
over that ring. Our results also imply that every self coarse embedding of a
Poincar\'e duality group over an arbitrary ring must be a coarse equivalence.


title:
A Modified $8f$ Geometry With Reduced Optical Aberrations For Improved
  Time Domain Terahertz Spectroscopy

abstract:
  We present a modified $8f$ geometry for time domain terahertz (THz)
spectroscopy (TDTS) experiments. We show, through simulations and data, that a
simple rearranging of the off-axis parabolic mirrors, which are typically used
to focus and direct THz radiation in TDTS experiments, results in a nearly 40%
reduction in the THz focal spot diameter. This effect stems from significant
reduction of the principle optical aberrations which are enhanced in the
conventional $8f$ geometry but partially compensated in the modified $8f$
experimental setup. We compare data from our home-built TDTS spectrometer in
the modified $8f$ geometry to that of previous iterations that were designed in
the conventional $8f$ geometry to demonstrate the effect.


title:
Schauder estimates for an integro-differential equation with
  applications to a nonlocal Burgers equation

abstract:
  We obtain Schauder estimates for a general class of linear
integro-differential equations. The estimates are applied to a scalar non-local
Burgers equation and complete the global well-posedness results obtained in
\cite{ISV}.


title: Towards Real-time Simulation of Hyperelastic Materials

abstract:
  We present a new method for real-time physics-based simulation supporting
many different types of hyperelastic materials. Previous methods such as
Position Based or Projective Dynamics are fast, but support only limited
selection of materials; even classical materials such as the Neo-Hookean
elasticity are not supported. Recently, Xu et al. [2015] introduced new
"spline-based materials" which can be easily controlled by artists to achieve
desired animation effects. Simulation of these types of materials currently
relies on Newton's method, which is slow, even with only one iteration per
timestep. In this paper, we show that Projective Dynamics can be interpreted as
a quasi-Newton method. This insight enables very efficient simulation of a
large class of hyperelastic materials, including the Neo-Hookean, spline-based
materials, and others. The quasi-Newton interpretation also allows us to
leverage ideas from numerical optimization. In particular, we show that our
solver can be further accelerated using L-BFGS updates (Limited-memory
Broyden-Fletcher-Goldfarb-Shanno algorithm). Our final method is typically more
than 10 times faster than one iteration of Newton's method without compromising
quality. In fact, our result is often more accurate than the result obtained
with one iteration of Newton's method. Our method is also easier to implement,
implying reduced software development costs.


title: Context Encoders: Feature Learning by Inpainting

abstract:
  We present an unsupervised visual feature learning algorithm driven by
context-based pixel prediction. By analogy with auto-encoders, we propose
Context Encoders -- a convolutional neural network trained to generate the
contents of an arbitrary image region conditioned on its surroundings. In order
to succeed at this task, context encoders need to both understand the content
of the entire image, as well as produce a plausible hypothesis for the missing
part(s). When training context encoders, we have experimented with both a
standard pixel-wise reconstruction loss, as well as a reconstruction plus an
adversarial loss. The latter produces much sharper results because it can
better handle multiple modes in the output. We found that a context encoder
learns a representation that captures not just appearance but also the
semantics of visual structures. We quantitatively demonstrate the effectiveness
of our learned features for CNN pre-training on classification, detection, and
segmentation tasks. Furthermore, context encoders can be used for semantic
inpainting tasks, either stand-alone or as initialization for non-parametric
methods.


title: The center of small quantum groups I: the principal block in type A

abstract:
  We develop an elementary algebraic method to compute the center of the
principal block of a small quantum group associated with a complex semisimple
Lie algebra at a root of unity. The exemplary case of $\mathfrak{sl}_3$ is
computed explicitly, and further evidence of $\mathfrak{sl}_4$ is sketched.
This allows us to formulate the conjecture that, as a bigraded vector space,
the center of a regular block of the small quantum $\mathfrak{sl}_m$ at a root
of unity is isomorphic to Haiman's diagonal coinvariant algebra for the
symmetric group $S_{m}$.


title: A solution to the problem of Rasa connected with Bernstein polynomials

abstract:
  During the Conference on Ulam's Type Stability (Rytro, Poland, 2014), Ioan
Rasa recalled his 25-years-old problem concerning some inequality involving the
Bernstein polynomials. We offer the complete solution (in positive). As a~tool
we use stochastic orderings (which we prove for binomial distributions) as well
as so-called concentration inequality. Our methods allow us to pose (and solve)
the extended version of the problem in question.


title:
Stability of stochastic differential equation driven by time-changed
  L\'evy noise

abstract:
  This paper studies stabilities of stochastic differential equation (SDE)
driven by time-changed L\'evy noise in both probability and moment sense. This
provides more flexibility in modeling schemes in application areas including
physics, biology, engineering, finance and hydrology. Necessary conditions for
solution of time-changed SDE to be stable in different senses will be
established. Connection between stability of solution to time-changed SDE and
that to corresponding original SDE will be disclosed. Examples related to
different stabilities will be given. We study SDEs with time-changed L\'evy
noise, where the time-change processes are inverse of general L\'evy
subordinators. These results are important improvements of the results in "Q.
Wu, Stability of stochastic differential equation with respect to time-changed
Brownian motion, 2016.".


title: Exploring the BTZ bulk with boundary conformal blocks

abstract:
  We point out a simple relation between the bulk field at an arbitrary radial
position and the boundary OPE, by placing some old work by Ferrara, Gatto,
Grillo and Parisi in the AdS/CFT context. This gives us, in principle, a
prescription for extracting the classical bulk field from the boundary
conformal block, and also clarifies why the latter is computed by a geodesic
Witten diagram. We apply this prescription to the BTZ black hole - viewed as a
pure state created by the insertion of a heavy operator in the boundary CFT_2 -
and use it to relate a classical field in the bulk to a heavy-light Virasoro
conformal block in the boundary. In particular, we obtain a relation between
the radial bulk position and the conformal ratios in the boundary CFT. We use
this to show that the singular points of the radial bulk equation occur when
the dual boundary operators approach each other and that the associated bulk
monodromies map to monodromies of the (appropriately transformed) conformal
block, thus providing a CFT interpretation of the radial monodromy.


title:
Universality for the Toda algorithm to compute the largest eigenvalue of
  a random matrix

abstract:
  We prove universality for the fluctuations of the halting time for the Toda
algorithm to compute the largest eigenvalue of real symmetric and complex
Hermitian matrices. The proof relies on recent results on the statistics of the
eigenvalues and eigenvectors of random matrices (such as delocalization,
rigidity and edge universality) in a crucial way.


title: Subdividing the cd-index of Eulerian Posets

abstract:
  This thesis aims to give the reader an introduction and overview of the
cd-index of a poset, as well as establish some new results. We give a
combinatorial proof of Ehrenborg and Karu's cd-index subdivision decomposition
for Gorenstein* complexes and extend it to a wider class of subdivisions. In
doing so, we define a local cd-index that behaves analogously to the well
studied local h-vector. We examine known cd-index and h-vector bounds, and then
use the local cd-index to bound a particular class of polytopes with the
cd-index of a stacked polytope. We conclude by investigating the h-vector and
local h- vector of posets in full generality, and use an algebra morphism
developed by Bayer and Ehrenborg to demonstrate the structural connection
between the cd-index subdivision decomposition and the local h-vector
subdivision decomposition. iii


title:
Security in The Gaussian Interference Channel: Weak and Moderately Weak
  Interference Regimes

abstract:
  We consider a secure communication scenario through the two-user Gaussian
interference channel: each transmitter (user) has a confidential message to
send reliably to its intended receiver while keeping it secret from the other
receiver. Prior work investigated the performance of two different approaches
for this scenario; i.i.d. Gaussian random codes and real alignment of
structured codes. While the latter achieves the optimal sum secure degrees of
freedom (s.d.o.f.), its extension to finite SNR regimes is challenging. In this
paper, we propose a new achievability scheme for the weak and the moderately
weak interference regimes, in which the reliability as well as the
confidentiality of the transmitted messages are maintained at any finite SNR
value. Our scheme uses lattice structure, structured jamming codewords, and
lattice alignment in the encoding and the asymmetric compute-and-forward
strategy in the decoding. We show that our lower bound on the sum secure rates
scales linearly with log(SNR) and hence, it outperforms i.i.d. Gaussian random
codes. Furthermore, we show that our achievable result is asymptotically
optimal. Finally, we provide a discussion on an extension of our scheme to K>2
users.


title:
Origin of the mass splitting of azimuthal anisotropies in a multi-phase
  transport model

abstract:
  Both hydrodynamics-based models and a multi-phase transport (AMPT) model can
reproduce the mass splitting of azimuthal anisotropy ($v_n$) at low transverse
momentum ($p_{\perp}$) as observed in heavy ion collisions. In the AMPT model,
however, $v_n$ is mainly generated by the parton escape mechanism, not by the
hydrodynamic flow. In this study we provide detailed results on the mass
splitting of $v_n$ in this transport model, including $v_2$ and $v_3$ of
various hadron species in d+Au and Au+Au collisions at the Relativistic Heavy
Ion Collider and p+Pb collisions at the Large Hadron Collider. We show that the
mass splitting of hadron $v_2$ and $v_3$ in AMPT first arises from the
kinematics in the quark coalescence hadronization process, and then, more
dominantly, comes from hadronic rescatterings, even though the contribution
from the latter to the overall charged hadron $v_n$ is small. We further show
that there is no qualitative difference between heavy ion collisions and
small-system collisions or between elliptic ($v_2$) and triangular ($v_3$)
anisotropies. Our studies thus demonstrate that the mass splitting of $v_2$ and
$v_3$ at low-$p_{\perp}$ is not a unique signature of hydrodynamic collective
flow but can be the interplay of several physics effects.


title: Photolytic Hazes in the Atmosphere of 51 Eri b

abstract:
  We use a 1D model to address photochemistry and possible haze formation in
the irradiated warm Jupiter, 51 Eridani b. The intended focus was to be carbon,
but sulfur photochemistry turns out to be important. The case for organic
photochemical hazes is intriguing but falls short of being compelling. If
organic hazes form, they are likeliest to do so if vertical mixing in 51 Eri b
is weaker than in Jupiter, and they would be found below the altitudes where
methane and water are photolyzed. The more novel result is that photochemistry
turns H$_2$S into elemental sulfur, here treated as S$_8$. In the cooler
models, S$_8$ is predicted to condense in optically thick clouds of solid
sulfur particles, whilst in the warmer models S$_8$ remains a vapor along with
several other sulfur allotropes that are both visually striking and potentially
observable. For 51 Eri b, the division between models with and without
condensed sulfur is at an effective temperature of 700 K, which is within error
its actual effective temperature; the local temperature where sulfur condenses
is between 280 and 320 K. The sulfur photochemistry we have discussed is quite
general and ought to be found in a wide variety of worlds over a broad
temperature range, both colder and hotter than the 650-750 K range studied
here, and we show that products of sulfur photochemistry will be nearly as
abundant on planets where the UV irradiation is orders of magnitude weaker than
it is on 51 Eri b.


title: A new perspective on materials for plasmonics

abstract:
  Surface plasmon polaritons are electromagnetic waves propagating on the
surface of a metal. Thanks to subwavelength confinement to the surface, they
can concentrate optical energy on the micrometer or even nanometer scale,
enabling new applications in bio-sensing, optical interconnects, and nonlinear
optics, where small footprint and strong field concentration is of the essence.
The major obstacle in developing plasmonic applications is dissipative loss,
which limits the propagation length of surface plasmons and broadens the
bandwidth of surface-plasmon resonances. Here we present a new analysis of
plasmonic materials and geometries that fully considers the trade-off between
the propagation length and the degree of confinement of surface plasmon
polaritons and allows a fair comparison between different substrates.


title: Subspace concentration of dual curvature measures

abstract:
  We prove a tight subspace concentration inequality for the dual curvature
measures of a symmetric convex body.


title: Ubiquity of Benfords law and emergence of the reciprocal distribution

abstract:
  We apply the Law of Total Probability to the construction of scale-invariant
probability distribution functions (pdfs), and require that probability
measures be dimensionless and unitless under a continuous change of scales. If
the scale-change distribution function is scale invariant then the constructed
distribution will also be scale invariant. Repeated application of this
construction on an arbitrary set of (normalizable) pdfs results again in
scale-invariant distributions. The invariant function of this procedure is
given uniquely by the reciprocal distribution, suggesting a kind of
universality. We separately demonstrate that the reciprocal distribution
results uniquely from requiring maximum entropy for size-class distributions
with uniform bin sizes.


title:
Dispersion regions overlapping for bulk and surface polaritons in a
  magnetic-semiconductor superlattice

abstract:
  Extraordinary dispersion features of both bulk and surface polaritons in a
finely-stratified magnetic-semiconductor structure which is under an action of
an external static magnetic field in the Voigt geometry are discussed in this
letter. It is shown that the conditions for total overlapping dispersion
regions of simultaneous existence of bulk and surface polaritons can be reached
providing a conscious choice of the constitutive parameters and material
fractions for both magnetic and semiconductor subsystems.


title: Analytic functional calculus for two operators

abstract:
  Properties of the mappings \begin{align*} C&\mapsto\frac1{(2\pi
i)^2}\int_{\Gamma_1}\int_{\Gamma_2}f(\lambda,\mu)\,R_{1,\,\lambda}\,C\,
R_{2,\,\mu}\,d\mu\,d\lambda, C&\mapsto\frac1{2\pi
i}\int_{\Gamma}g(\lambda)R_{1,\,\lambda}\,C\, R_{2,\,\lambda}\,d\lambda
\end{align*} are discussed; here $R_{1,\,(\cdot)}$ and $R_{2,\,(\cdot)}$ are
pseudo-resolvents, i.~e., resolvents of bounded, unbounded, or multivalued
linear operators, and $f$ and $g$ are analytic functions. Several applications
are considered: a representation of the impulse response of a second order
linear differential equation with operator coefficients, a representation of
the solution of the Sylvester equation, and an exploration of properties of the
differential of the ordinary functional calculus.


title:
Pilot-wave dynamics in a harmonic potential: Quantization and stability
  of circular orbits

abstract:
  We present the results of a theoretical investigation of the dynamics of a
droplet walking on a vibrating fluid bath under the influence of a harmonic
potential. The walking droplet's horizontal motion is described by an
integro-differential trajectory equation, which is found to admit steady
orbital solutions. Predictions for the dependence of the orbital radius and
frequency on the strength of the radial harmonic force field agree favorably
with experimental data. The orbital quantization is rationalized through an
analysis of the orbital solutions. The predicted dependence of the orbital
stability on system parameters is compared with experimental data and the
limitations of the model are discussed.


title: Build-up of macroscopic eigenstates in a memory-based constrained system

abstract:
  A bouncing drop and its associated accompanying wave forms a walker. Based on
previous works, we show in this article that it is possible to formulate a
simple theoretical framework for the walker dynamics. It relies on a time scale
decomposition corresponding to the effects successively generated when the
memory effects increase. While the short time scale effect is simply
responsible for the walker's propulsion, the intermediate scale generates
spontaneously pivotal structures endowed with angular momentum. At an even
larger memory scale, if the walker is spatially confined, the pivots become the
building blocks of a self-organization into a global structure. This new
theoretical framework is applied in the presence of an external harmonic
potential, and reveals the underlying mechanisms leading to the emergence of
the macroscopic spatial organization reported by Perrard et al. (2014, Nature
Commun. 5, 3219)


title:
Some new Fibonacci difference spaces of non-absolute type and compact
  operators

abstract:
  The aim of the paper is to introduced the spaces $c_{0}^{\lambda}(\hat{F})$
and $c^{\lambda}(\hat{F})$ which are the BK-spaces of non-absolute type and
also derive some inclusion relations. Further, we determine the
$\alpha-,\beta-,\gamma-$duals of those spaces and also construct their bases.
We also characterize some matrix classes on the spaces
$c_{0}^{\lambda}(\hat{F})$ and $c^{\lambda}(\hat{F}).$ Here we characterize the
subclasses $\mathcal{K}(X,Y)$ of compact operators where $X$ is
$c_{0}^{\lambda}(\hat{F})$ or $c^{\lambda}(\hat{F})$ and $Y$ is one of the
spaces $c_{0},c, l_{\infty}, l_{1}, bv$ by applying Hausdorff measure of
noncompactness.


title: Teaching Data Science

abstract:
  We describe an introductory data science course, entitled Introduction to
Data Science, offered at the University of Illinois at Urbana-Champaign. The
course introduced general programming concepts by using the Python programming
language with an emphasis on data preparation, processing, and presentation.
The course had no prerequisites, and students were not expected to have any
programming experience. This introductory course was designed to cover a wide
range of topics, from the nature of data, to storage, to visualization, to
probability and statistical analysis, to cloud and high performance computing,
without becoming overly focused on any one subject. We conclude this article
with a discussion of lessons learned and our plans to develop new data science
courses.


title: Do Galactic Antiprotons Come from Decaying Dark Matter?

abstract:
  It is shown that the antiproton spectrum reported by the AMS02 collaboration
can be accounted for by dark matter (DM) decay if the residence time in the
Galactic halo is of order 90 Myr. The DM lifetime assumed, $ 5 \cdot 10^{27}$ s
for DM particle mass of 3 TeV, is shown to be consistent with the constraints
of diffuse gamma ray background. Alternative sources of antiprotons, such as
those from compact objects, are shown to be strongly constrained by neutrino
astronomy and therefore unlikely candidates.


title: Simulating cosmic ray physics on a moving mesh

abstract:
  We discuss new methods to integrate the cosmic ray (CR) evolution equations
coupled to magneto-hydrodynamics (MHD) on an unstructured moving mesh, as
realised in the massively parallel AREPO code for cosmological simulations. We
account for diffusive shock acceleration of CRs at resolved shocks and at
supernova remnants in the interstellar medium (ISM), and follow the advective
CR transport within the magnetised plasma, as well as anisotropic diffusive
transport of CRs along the local magnetic field. CR losses are included in
terms of Coulomb and hadronic interactions with the thermal plasma. We
demonstrate the accuracy of our formalism for CR acceleration at shocks through
simulations of plane-parallel shock tubes that are compared to newly derived
exact solutions of the Riemann shock tube problem with CR acceleration. We find
that the increased compressibility of the post-shock plasma due to the produced
CRs decreases the shock speed. However, CR acceleration at spherically
expanding blast waves does not significantly break the self-similarity of the
Sedov-Taylor solution; the resulting modifications can be approximated by a
suitably adjusted, but constant adiabatic index. In first applications of the
new CR formalism to simulations of isolated galaxies and cosmic structure
formation, we find that CRs add an important pressure component to the ISM that
increases the vertical scale height of disk galaxies, and thus reduces the star
formation rate. Strong external structure formation shocks inject CRs into the
gas, but the relative pressure of this component decreases towards halo centres
as adiabatic compression favours the thermal over the CR pressure.

categories: astro-ph.GA astro-ph.CO astro-ph.HE astro-ph.IM


title: Supersymmetric Explanation of CP Violation in $K\to \pi\pi$ Decays

abstract:
  Recent progress in the determination of hadronic matrix elements has revealed
a tension between the measured value of $\epsilon_K^{\prime}/\epsilon_K$, which
quantifies direct $CP$ violation in $K \to \pi\pi$ decays, and the
Standard-Model prediction. The well-understood indirect $CP$ violation encoded
in the quantity $\epsilon_K$ typically precludes large new-physics
contributions to $\epsilon_K^{\prime}/\epsilon_K$ and challenges such an
explanation of the discrepancy. We show that it is possible to cure the
$\epsilon_K^{\prime}/\epsilon_K$ anomaly in the Minimal Supersymmetric Standard
Model with squark masses above 3 TeV without overshooting $\epsilon_K$. This
solution exploits two features of supersymmetry: the possibility of large
isospin-breaking contributions (enhancing $\epsilon_K^{\prime}$) and the
Majorana nature of gluinos (permitting a suppression of $\epsilon_K$). Our
solution involves no fine-tuning of $CP$ phases or other parameters.


title:
Shock finding on a moving-mesh: II. Hydrodynamic shocks in the Illustris
  universe

abstract:
  Hydrodynamical shocks are a manifestation of the non-linearity of the Euler
equations and play a fundamental role in cosmological gas dynamics. In this
work, we identify and analyse shocks in the Illustris simulation, and contrast
the results with those of non-radiative runs. We show that simulations with
more comprehensive physical models of galaxy formation pose new challenges for
shock finding algorithms due to radiative cooling and star-forming processes,
prompting us to develop a number of methodology improvements. We find in
Illustris a total shock surface area which is about 1.4 times larger at the
present epoch compared to non-radiative runs, and an energy dissipation rate at
shocks which is higher by a factor of around 7. Remarkably, shocks with Mach
numbers above and below $\mathcal{M}\approx10$ contribute about equally to the
total dissipation across cosmic time. This is in sharp contrast to
non-radiative simulations, and we demonstrate that a large part of the
difference arises due to strong black hole radio-mode feedback in Illustris. We
also provide an overview of the large diversity of shock morphologies, which
includes complex networks of halo-internal shocks, shocks on to cosmic sheets,
feedback shocks due to black holes and galactic winds, as well as ubiquitous
accretion shocks. In high redshift systems more massive than
$10^{12}\,\mathrm{M}_\odot$ we discover the existence of a double accretion
shock pattern in haloes. They are created when gas streams along filaments
without being shocked at the outer accretion shock, but then forms a second,
roughly spherical accretion shock further inside.


title: The IRX-$\beta$ relation: Insights from simulations

abstract:
  We study the relationship between the UV continuum slope and infrared excess
(IRX$\equiv L_{\rm IR}/L_{\rm FUV}$) predicted by performing dust radiative
transfer on a suite of hydrodynamical simulations of galaxies. Our suite
includes both isolated disk galaxies and mergers intended to be representative
of galaxies at both $z \sim 0$ and $z \sim 2-3$. Our low-redshift isolated
disks and mergers often populate a region around the the locally calibrated
\citet[][M99]{M99} relation but move well above the relation during
merger-induced starbursts. Our high-redshift simulated galaxies are blue and
IR-luminous, which makes them lie above the M99 relation. The value of UV
continuum slope strongly depends on the dust type used in the radiative
transfer calculations: Milky Way-type dust leads to significantly more negative
(bluer) slopes compared with Small Magellanic Cloud-type dust. The effect on
$\beta$ due to variations in the dust composition with galaxy properties or
redshift can dominate over other sources of $\beta$ variations and is the
dominant model uncertainty. The dispersion in $\beta$ is anticorrelated with
specific star formation rate and tends to be higher for the $z \sim 2-3$
simulations. In the actively star-forming $z \sim 2-3$ simulated galaxies, dust
attenuation dominates the dispersion in $\beta$, whereas in the $z \sim 0$
simulations, the contributions of SFH variations and dust are similar. For
low-SSFR systems at both redshifts, SFH variations dominate the dispersion.
Finally, the simulated $z \sim 2-3$ isolated disks and mergers both occupy a
region in the \irxbeta\ plane consistent with observed $z \sim 2-3$ dusty
star-forming galaxies (DSFGs). Thus, contrary to some claims in the literature,
the blue colors of high-z DSFGs do not imply that they are short-lived
starbursts.


title: The Correlation Between Metallicity and Debris Disk mass

abstract:
  We find that the initial dust masses in planetary debris disks are correlated
with the metallicities of their central stars. We compiled a large sample of
systems, including Spitzer, the Herschel DUNES and DEBRIS surveys, and WISE
debris disk candidates. We also merged 33 metallicity catalogs to provide
homogeneous [Fe/H] and $\sigma_{[Fe/H]}$ values. We analyzed this merged
sample, including 222 detected disks (74 warm and 148 cold) around a total of
187 systems (some with multiple components) and 440 disks with only upper
limits (125 warm and 315 cold), around a total of 360 systems. The disk dust
masses at a common early evolutionary point in time were determined using our
numerical disk evolutionary code, evolving a unique model for each of the 662
disks backward to an age of 1 Myr. We find that disk-bearing stars seldom have
metallicities less than [Fe/H] = -0.2 and that the distribution of warm
component masses lacks examples with large mass around stars of low metallicity
([Fe/H] < -0.085). Previous efforts to find a correlation have been largely
unsuccessful; the primary improvements supporting our result are: 1.) basing
the study on dust masses, not just infrared excess detections; 2.) including
upper limits on dust mass in a quantitative way; 3.) accounting for the
evolution of debris disk excesses as systems age; 4.) accounting fully for the
range of uncertainties in metallicity measurements; and 5.) having a
statistically large enough sample.


title:
Discovery of a galaxy cluster with a violently starbursting core at
  z=2.506

abstract:
  We report the discovery of a remarkable concentration of massive galaxies
with extended X-ray emission at $z_{spec} = 2.506$, which contains 11 massive
($M_{*} \gtrsim 10^{11} M_{\odot}$) galaxies in the central 80kpc region
(11.6$\sigma$ overdensity). We have spectroscopically confirmed 17 member
galaxies with 11 from CO and the remaining ones from $H\alpha$. The X-ray
luminosity, stellar mass content and velocity dispersion all point to a
collapsed, cluster-sized dark matter halo with mass $M_{200c} = 10^{13.9\pm0.2}
M_{\odot}$, making it the most distant X-ray-detected cluster known to date.
Unlike other clusters discovered so far, this structure is dominated by
star-forming galaxies (SFGs) in the core with only 2 out of the 11 massive
galaxies classified as quiescent. The star formation rate (SFR) in the 80kpc
core reaches $\sim$3400 $M_{\odot}$ yr$^{-1}$ with a gas depletion time of
$\sim 200$ Myr, suggesting that we caught this cluster in rapid build-up of a
dense core. The high SFR is driven by both a high abundance of SFGs and a
higher starburst fraction ($\sim25\%$, compared to 3\%-5\% in the field). The
presence of both a collapsed, cluster-sized halo and a predominant population
of massive SFGs suggests that this structure could represent an important
transition phase between protoclusters and mature clusters. It provides
evidence that the main phase of massive galaxy passivization will take place
after galaxies accrete onto the cluster, providing new insights into massive
cluster formation at early epochs. The large integrated stellar mass at such
high redshift challenges our understanding of massive cluster formation.


title:
Simultaneous infrared and optical observations of the transiting debris
  cloud around WD 1145+017

abstract:
  We present multi-wavelength photometric monitoring of WD 1145+017, a white
dwarf exhibiting periodic dimming events interpreted to be the transits of
orbiting, disintegrating planetesimals. Our observations include the first set
of near-infrared light curves for the object, obtained on multiple nights over
the span of one month, and recorded multiple transit events with depths varying
between ~20 to 50 per cent. Simultaneous near-infrared and optical observations
of the deepest and longest duration transit event were obtained on two epochs
with the Anglo-Australian Telescope and three optical facilities, over the
wavelength range of 0.5 to 1.2 microns. These observations revealed no
measurable difference in transit depths for multiple photometric pass bands,
allowing us to place a 2 sigma lower limit of 0.8 microns on the grain size in
the putative transiting debris cloud. This conclusion is consistent with the
spectral energy distribution of the system, which can be fit with an optically
thin debris disc with minimum particle sizes of 10 +5/-3 microns.


title: Is lightning a possible source of the radio emission on HAT-P-11b?

abstract:
  Lightning induced radio emission has been observed on Solar system planets.
There have been many attempts to observe exoplanets in the radio wavelength,
however, no unequivocal detection has been reported. Lecavelier des Etangs et
al. carried out radio transit observations of the exoplanet HAT-P-11b, and
suggested that a small part of the radio flux can be attributed to the planet.
Here, we assume that this signal is real, and study if this radio emission
could be caused by lightning with similar energetic properties like in the
Solar system. We find that a lightning storm with 3.8 x $10^6$ times larger
flash densities than the Earth-storms with the largest lightning activity is
needed to produce the observed signal from HAT-P-11b. The optical emission of
such thunderstorm would be comparable to that of the host star. We show that
HCN produced by lightning chemistry is observable 2-3 yr after the storm, which
produces signatures in the L (3.0-4.0 \mu m) and N (7.5-14.5 \mu m) infrared
bands. We conclude that it is unlikely that the observed radio signal was
produced by lightning, however, future, combined radio and infrared
observations may lead to lightning detection on planets outside the Solar
system.

categories: astro-ph.EP astro-ph.CO physics.ao-ph physics.geo-ph


title: Conversational Markers of Constructive Discussions

abstract:
  Group discussions are essential for organizing every aspect of modern life,
from faculty meetings to senate debates, from grant review panels to papal
conclaves. While costly in terms of time and organization effort, group
discussions are commonly seen as a way of reaching better decisions compared to
solutions that do not require coordination between the individuals (e.g.
voting)---through discussion, the sum becomes greater than the parts. However,
this assumption is not irrefutable: anecdotal evidence of wasteful discussions
abounds, and in our own experiments we find that over 30% of discussions are
unproductive.
  We propose a framework for analyzing conversational dynamics in order to
determine whether a given task-oriented discussion is worth having or not. We
exploit conversational patterns reflecting the flow of ideas and the balance
between the participants, as well as their linguistic choices. We apply this
framework to conversations naturally occurring in an online collaborative world
exploration game developed and deployed to support this research. Using this
setting, we show that linguistic cues and conversational patterns extracted
from the first 20 seconds of a team discussion are predictive of whether it
will be a wasteful or a productive one.

categories: cs.CL cs.AI cs.SI physics.soc-ph stat.ML


title: The collimation of magnetic jets by disk winds

abstract:
  The collimation of a Poynting-flux dominated jet by a wind emanating from the
surface of an accretion flow is computed using a semi-analytic model. The
injection of the disk wind is treated as a boundary condition in the equatorial
plane, and its evolution is followed by invoking a prescribed geometry of
streamlines. Solutions are obtained for a wide range of disk wind parameters.
It is found that jet collimation generally occurs when the total wind power
exceeds about ten percents of the jet power. For moderate wind powers we find
gradual collimation. For strong winds we find rapid collimation followed by
focusing of the jet, after which it remains narrow over many Alfv\'en crossing
times before becoming conical. We estimate that in the later case the jet's
magnetic field may be dissipated by the current-driven kink instability over a
distance of a few hundreds gravitational radii. We apply the model to M87 and
show that the observed parabolic shape of the radio jet within the Bondi radius
can be reproduced provided that the wind injection zone extends to several
hundreds gravitational radii, and that its total power is about one third of
the jet power. The radio spectrum can be produced by synchrotron radiation of
relativistically hot, thermal electrons in the sheath flow surrounding the
inner jet.


title:
Substructure and galaxy formation in the Copernicus Complexio warm dark
  matter simulations

abstract:
  We use the Copernicus Complexio (COCO) high resolution $N$-body simulations
to investigate differences in the properties of small-scale structures in the
standard cold dark matter (CDM) model and in a model with a cutoff in the
initial power spectrum of density fluctuations consistent with both a thermally
produced warm dark matter (WDM) particle or a sterile neutrino with mass 7 keV
and leptogenesis parameter $L_6=8.7$. The latter corresponds to the "coldest"
model with this sterile neutrino mass compatible with the identification of the
recently detected 3.5 keV X-ray line as resulting from particle decay. CDM and
WDM predict very different number densities of subhaloes with mass $\leq
10^9\,h^{-1}\,M_\odot$ although they predict similar, nearly universal,
normalised subhalo radial density distributions. Haloes and subhaloes in both
models have cuspy NFW profiles, but WDM subhaloes below the cutoff scale in the
power spectrum (corresponding to maximum circular velocities
$V_{\mathrm{max}}^{z=0} \leq50~\mathrm{kms}^{-1}$) are less concentrated than
their CDM counterparts. We make predictions for observable properties using the
GALFORM semi-analytic model of galaxy formation. Both models predict Milky Way
satellite luminosity functions consistent with observations, although the WDM
model predicts fewer very faint satellites. This model, however, predicts
slightly more UV bright galaxies at redshift $z>7$ than CDM, but both are
consistent with observations. Gravitational lensing offers the best prospect of
distinguishing between the models.


title:
CIV Broad Absorption Line Acceleration in Sloan Digital Sky Survey
  Quasars

abstract:
  We present results from the largest systematic investigation of broad
absorption line (BAL) acceleration to date. We use spectra of 140 quasars from
three Sloan Digital Sky Survey programs to search for global velocity offsets
in BALs over timescales of ~2.5-5.5 years in the quasar rest frame. We
carefully select acceleration candidates by requiring monolithic velocity
shifts over the entire BAL trough, avoiding BALs with velocity shifts that
might be caused by profile variability. The CIV BALs of two quasars show
velocity shifts consistent with the expected signatures of BAL acceleration,
and the BAL of one quasar shows a velocity-shift signature of deceleration. In
our two acceleration candidates, we see evidence that the magnitude of the
acceleration is not constant over time; the magnitudes of the change in
acceleration for both acceleration candidates are difficult to produce with a
standard disk-wind model or via geometric projection effects. We measure upper
limits to acceleration and deceleration for 76 additional BAL troughs and find
that the majority of BALs are stable to within about 3% of their mean
velocities. The lack of widespread acceleration/deceleration could indicate
that the gas producing most BALs is located at large radii from the central
black hole and/or is not currently strongly interacting with ambient material
within the host galaxy along our line of sight.


title:
Protophobic Fifth Force Interpretation of the Observed Anomaly in $^8$Be
  Nuclear Transitions

abstract:
  Recently a 6.8$\sigma$ anomaly has been reported in the opening angle and
invariant mass distributions of $e^+ e^-$ pairs produced in $^8\text{Be}$
nuclear transitions. The data are explained by a 17 MeV vector gauge boson $X$
that is produced in the decay of an excited state to the ground state,
$^8\text{Be}^* \to {}^8\text{Be} \, X$, and then decays through $X \to e^+
e^-$. The $X$ boson mediates a fifth force with a characteristic range of 12 fm
and has milli-charged couplings to up and down quarks and electrons, and a
proton coupling that is suppressed relative to neutrons. The protophobic $X$
boson may also alleviate the current 3.6$\sigma$ discrepancy between the
predicted and measured values of the muon's anomalous magnetic moment.


title:
Impacts of a Flaring Star-forming Disc and Stellar Radial Mixing on the
  Vertical Metallicity Gradient

abstract:
  Using idealised N-body simulations of a Milky Way-sized disc galaxy, we
qualitatively study how the metallicity distributions of the thin disc star
particles are modified by the formation of the bar and spiral arm structures.
The thin disc in our numerical experiments initially has a tight negative
radial metallicity gradient and a constant vertical scale-height. We show that
the radial mixing of stars drives a positive vertical metallicity gradient in
the thin disc. On the other hand, if the initial thin disc is flared, with
vertical scale-height increasing with galactocentric radius, the metal poor
stars originally in the outer disc become dominant in regions above the disc
plane at every radii. This process can drive a negative vertical metallicity
gradient, which is consistent with the current observed trend. This model
mimics a scenario where the star-forming thin disc was flared in the outer
region at earlier epochs. Our numerical experiment with an initial flared disc
predicts that the negative vertical metallicity gradient of the mono-age
relatively young thin disc population should be steeper in the inner disc, and
the radial metallicity gradient of the mono-age population should be shallower
at greater heights above the disc plane. We also predict that the metallicity
distribution function of mono-age young thin disc populations above the disc
plane would be more positively skewed in the inner disc compared to the outer
disc.


title:
Constraints on the Evolution of the Galaxy Stellar Mass Function I: Role
  of Star Formation, Mergers and Stellar Stripping

abstract:
  We study the connection between the observed star formation rate-stellar mass
(SFR-$M_*$) relation and the evolution of the stellar mass function (SMF) by
means of a Subhalo Abundance Matching technique coupled to merger trees
extracted from a N-body simulation. Our approach, which considers both galaxy
mergers and stellar stripping, is to force the model to match the observed SMF
at redshift $z>2$, and let it evolve down to the present time according to the
observed (SFR-$M_*$) relation. In this study, we use two different sets of SMFs
and two SFR-$M_*$ relations: a simple power law and a relation with a
mass-dependent slope. Our analysis shows that the evolution of the SMF is more
consistent with a SFR-$M_*$ relation with a mass-dependent slope, in agreement
with predictions from other models of galaxy evolution and recent observations.
In order to fully and realistically describe the evolution of the SMF, both
mergers and stellar stripping must be considered, and we find that both have
almost equal effects on the evolution of SMF at the massive end. Taking into
account the systematic uncertainties in the observed data, the high-mass end of
the SMF obtained by considering stellar stripping results in good agreement
with recent observational data from the Sloan Digital Sky Survey (SDSS). At
$\log M_* < 11.2$, our prediction at z=0.1 is close to \citet{li-white09} data,
but the high-mass end ($\log M_* > 11.2$) is in better agreement with
\citet{dsouza15} data which account for more massive galaxies.


title:
Binary Stellar Mergers with Marginally-Bound Ejecta: Excretion Disks,
  Inflated Envelopes, Outflows, and their Luminous Transients

abstract:
  We study mass loss from the outer Lagrange point (L2) in binary stellar
mergers and their luminous transients by means of radiative hydrodynamical
simulations. Previously, we showed that for binary mass ratios 0.06 < q < 0.8,
synchronous L2 mass loss results in a radiatively inefficient, dust-forming
unbound equatorial outflow. A similar outflow exists irrespective of q if the
ratio of the sound speed to the orbital speed at the injection point is
sufficiently large, \epsilon = c_T/v_orb > 0.15. By contrast, for cold L2
mass-loss (\epsilon < 0.15) from binaries with q < 0.06 or q > 0.8, the
equatorial outflow instead remains marginally-bound and falls back to the
binary over tens to hundreds of binary orbits, where it experiences additional
tidal torqueing and shocking. As the bound gas becomes virialized with the
binary, the luminosity of the system increases slowly at approximately constant
photosphere radius, causing the temperature to rise. Subsequent evolution
depends on the efficiency of radiative cooling. If the bound atmosphere is able
to cool efficiently, as quantified by radiative diffusion time being shorter
than the advection time (t_diff/t_adv < 1), then the virialized gas collapses
to an excretion disk, while for t_diff/t_adv > 1 an isotropic wind is formed.
Between these two extremes, an inflated envelope transports the heat generated
near the binary to the surface by meridional flows. In all cases, the radiated
luminosity reaches a fraction ~0.01 to 0.1 of Mdot v_orb^2/2, where Mdot is the
mass outflow rate. We discuss the implications of our results for transients in
the luminosity gap between classical novae and supernovae, such as V1309 Sco
and V838 Mon.


title: Distribution amplitudes of radially-excited pi- and K-mesons

abstract:
  A symmetry-preserving truncation of the two-body bound-state problem in
relativistic quantum field theory is used to compute the leading-twist parton
distribution amplitudes (PDAs) for the first radial excitations of the $\pi$-
and $K$-mesons. In common with ground states in these channels, the PDAs are
found to be dilated with respect to the relevant conformal-limit form and
skewed toward the heavier valence-quark in asymmetric systems. In addition, the
PDAs of radially-excited pseudoscalar mesons are not positive definite, owing
to the fact that dynamical chiral symmetry breaking (DCSB) forces the leptonic
decay constant of such states to vanish in the chiral limit. These results
highlight that DCSB is expressed visibly in every pseudoscalar meson
constituted from light-quarks. Hence, so long as its impact is empirically
evident in the pseudoscalar members of a given spectrum level, it is unlikely
that chiral symmetry is restored in any of the hadrons that populate this
level.


title: Large N Correlation Functions in Superconformal Field Theories

abstract:
  We compute correlation functions of chiral primary operators in N=2
superconformal theories at large N using a construction based on supersymmetric
localization recently developed by Gerchkovitz et al. We focus on N=4 SYM as
well as on superconformal QCD. In the case of N=4 we recover the free field
theory results as expected due to non-renormalization theorems. In the case of
superconformal QCD we study the planar expansion in the large N limit. The
final correlators admit a simple generalization to a finite N formula which
exactly matches the various small $N$ results in the literature.


title: High-energy evolution to three loops

abstract:
  The Balitsky-Kovchegov equation describes the high-energy growth of gauge
theory scattering amplitudes as well as nonlinear saturation effects which stop
it. We obtain the three-loop corrections to this equation in planar
$\mathcal{N}=4$ super Yang-Mills theory. Our method exploits a recently
established equivalence with the physics of soft wide-angle radiation,
so-called non-global logarithms, and thus yields at the same time the
three-loop evolution equation for non-global logarithms. As a by-product of our
analysis, we develop a Lorentz-covariant method to subtract infrared and
collinear divergences in cross-section calculations in the planar limit. We
compare our result in the linear regime with a recent prediction for the
so-called Pomeron trajectory, and compare its collinear limit with predictions
from the spectrum of twist-two operators.


title: Herschel detects oxygen in the beta Pictoris debris disk

abstract:
  The young star beta Pictoris is well known for its dusty debris disk,
produced through the grinding down by collisions of planetesimals,
kilometre-sized bodies in orbit around the star. In addition to dust, small
amounts of gas are also known to orbit the star, likely the result from
vaporisation of violently colliding dust grains. The disk is seen edge on and
from previous absorption spectroscopy we know that the gas is very rich in
carbon relative to other elements. The oxygen content has been more difficult
to assess, however, with early estimates finding very little oxygen in the gas
at a C/O ratio 20x higher than the cosmic value. A C/O ratio that high is
difficult to explain and would have far-reaching consequences for planet
formation. Here we report on observations by the far-infrared space telescope
Herschel, using PACS, of emission lines from ionised carbon and neutral oxygen.
The detected emission from C+ is consistent with that previously reported being
observed by the HIFI instrument on Herschel, while the emission from O is hard
to explain without assuming a higher-density region in the disk, perhaps in the
shape of a clump or a dense torus, required to sufficiently excite the O atoms.
A possible scenario is that the C/O gas is produced by the same process
responsible for the CO clump recently observed by ALMA in the disk, and that
the re-distribution of the gas takes longer than previously assumed. A more
detailed estimate of the C/O ratio and the mass of O will have to await better
constraints on the C/O gas spatial distribution.


title:
Dilepton bounds on left-right symmetry at the LHC run II and
  neutrinoless double beta decay

abstract:
  In the light of the new 13 TeV dilepton data set with $ 3.2\, {\rm fb^{-1}}$
integrated luminosity from the ATLAS collaboration, we derive limits on the
$Z^{\prime}$ mass in the context of left-right symmetric models and exploit the
complementarity with dijet and $lljj$ data, as well as neutrinoless double beta
decay. We keep the ratio of the left- and right-handed gauge coupling free in
order to take into account different patterns of left-right symmetry breaking.
By combining the dielectron and dimuon data we can exclude $Z^{\prime}$ masses
below $3$ TeV for $g_R=g_L$, and for $g_R \sim 1$ we rule out masses up to
$\sim 4$ TeV. Those comprise the strongest direct bounds on the $Z^{\prime}$
mass from left-right models up to date. We show that in the usual plane of
right-handed neutrino and charged gauge boson mass, dilepton data can probe a
region of parameter space inaccessible to neutrinoless double beta decay and
$lljj$ studies. Lastly, through the mass relation between $W_R$ and
$Z^{\prime}$ we present an indirect bound on the lifetime of neutrinoless
double beta decay using dilepton data. Our results prove that the often ignored
dilepton data in the context of left-right models actually provide important
complementary limits.


title: Eta and rho invariants on manifolds with edges

abstract:
  We establish existence of the eta-invariant as well as of the
Atiyah-Patodi-Singer and the Cheeger-Gromov rho-invariants for a class of Dirac
operators on an incomplete edge space. Our analysis applies in particular to
the signature, the Gauss-Bonnet and the spin Dirac operator. We derive an
analogue of the Atiyah-Patodi-Singer index theorem for incomplete edge spaces
and their non-compact infinite Galois coverings with edge singular boundary.
Our arguments employ microlocal analysis of the heat kernel asymptotics on
incomplete edge spaces and the classical argument of Atiyah-Patodi-Singer. As
an application, we discuss stability results for the two rho-invariants we have
defined.


title:
Probing TeV scale Top-Philic Resonances with Boosted Top-Tagging at the
  High Luminosity LHC

abstract:
  We investigate the discovery potential of singly produced top-philic
resonances at the high luminosity (HL) LHC in the four-top final state. Our
analysis spans over the fully-hadronic, semi-leptonic, and same-sign dilepton
channels where we present concrete search strategies adequate to a boosted
kinematic regime and high jet-multiplicity environments. We utilize the
Template Overlap Method (TOM) with newly developed template observables for
tagging boosted top quarks, a large-radius jet variable $M_J$ and customized
b-tagging tactics for background discrimination. Our results show that the
same-sign dilepton channel gives the best sensitivity among the considered
channels, with an improvement of significance up to 10%-20% when combined with
boosted-top tagging. Both the fully-hadronic and semi-leptonic channels yield
comparable discovery potential and contribute to further enhancements in the
sensitivity by combining all channels. Finally, we show the sensitivity of a
top-philic resonance at the LHC and HL-LHC by showing the $2\sigma$ exclusion
limit and $5\sigma$ discovery reach, including a combination of all three
channels.


title: Quantum theory cannot consistently describe the use of itself

abstract:
  Quantum theory provides an extremely accurate description of fundamental
processes in physics. It thus seems likely that the theory is applicable beyond
the, mostly microscopic, domain in which it has been tested experimentally.
Here we propose a Gedankenexperiment to investigate the question whether
quantum theory can, in principle, have universal validity. The idea is that, if
the answer was yes, it must be possible to employ quantum theory to model
complex systems that include agents who are themselves using quantum theory.
Analysing the experiment under this presumption, we find that one agent, upon
observing a particular measurement outcome, must conclude that another agent
has predicted the opposite outcome with certainty. The agents' conclusions,
although all derived within quantum theory, are thus inconsistent. This
indicates that quantum theory cannot be extrapolated to complex systems, at
least not in a straightforward manner.


title: Ultrafast many-body interferometry of impurities coupled to a Fermi sea

abstract:
  The fastest possible collective response of a quantum many-body system is
related to its excitations at the highest possible energy. In condensed-matter
systems, the corresponding timescale is typically set by the Fermi energy.
Taking advantage of fast and precise control of interactions between ultracold
atoms, we report on the observation of ultrafast dynamics of impurities coupled
to an atomic Fermi sea. Our interferometric measurements track the
non-perturbative quantum evolution of a fermionic many-body system, revealing
in real time the formation dynamics of quasiparticles and the quantum
interference between attractive and repulsive states throughout the full depth
of the Fermi sea. Ultrafast time-domain methods to manipulate and investigate
strongly interacting quantum gases open up new windows on the dynamics of
quantum matter under extreme non-equilibrium conditions.


title:
The Hunt for Planet Nine: Atmosphere, Spectra, Evolution, and
  Detectability

abstract:
  We investigate the physical characteristics of the Solar System's proposed
Planet Nine using modeling tools with a heritage in studying Uranus and
Neptune. For a range of plausible masses and interior structures, we find upper
limits on the intrinsic Teff, from ~35-50 K for masses of 5-20 M_Earth, and we
also explore lower Teff values. Possible planetary radii could readily span
from 3 to 6 R_Earth depending on the mass fraction of any H/He envelope. Given
its cold temperature, the planet encounters significant methane condensation,
which dramatically alters the atmosphere away from simple Neptune-like
expectations. We find the atmosphere is strongly depleted in molecular
absorption at visible wavelengths, suggesting a Rayleigh scattering atmosphere
with a high geometric albedo approaching 0.75. We highlight two diagnostics for
the atmosphere's temperature structure, the first being the value of the
methane mixing ratio above the methane cloud. The second is the wavelength at
which cloud scattering can be seen, which yields the cloud-top pressure.
Surface reflection may be seen if the atmosphere is thin. Due to
collision-induced opacity of H2 in the infrared, the planet would be extremely
blue (instead of red) in the shortest wavelength WISE colors if methane is
depleted, and would, in some cases, exist on the verge of detectability by
WISE. For a range of models, thermal fluxes from ~3-5 microns are ~20 orders of
magnitude larger than blackbody expectations. We report a search of the AllWISE
Source Catalog for Planet Nine, but find no detection.


title: Photoproduction of the $f_1(1285)$ Meson

abstract:
  The $f_1(1285)$ meson with mass $1281.0 \pm 0.8$ MeV/$c^2$ and width $18.4
\pm 1.4$ MeV (FWHM) was measured for the first time in photoproduction from a
proton target using CLAS at Jefferson Lab. Differential cross sections were
obtained via the $\eta\pi^{+}\pi^{-}$, $K^+\bar{K}^0\pi^-$, and $K^-K^0\pi^+$
decay channels from threshold up to a center-of-mass energy of 2.8 GeV. The
mass, width, and an amplitude analysis of the $\eta\pi^{+}\pi^{-}$ final-state
Dalitz distribution are consistent with the axial-vector $J^P=1^+$ $f_1(1285)$
identity, rather than the pseudoscalar $0^-$ $\eta(1295)$. The production
mechanism is more consistent with $s$-channel decay of a high-mass $N^*$ state,
and not with $t$-channel meson exchange. Decays to $\eta\pi\pi$ go dominantly
via the intermediate $a_0^\pm(980)\pi^\mp$ states, with the branching ratio
$\Gamma(a_0\pi \text{ (no} \bar{K} K\text{)}) / \Gamma(\eta\pi\pi \text{(all)})
= 0.74\pm0.09$. The branching ratios $\Gamma(K \bar{K} \pi)/\Gamma(\eta\pi\pi)
= 0.216\pm0.033$ and $\Gamma(\gamma\rho^0)/\Gamma(\eta\pi\pi) = 0.047\pm0.018$
were also obtained. The first is in agreement with previous data for the
$f_1(1285)$, while the latter is lower than the world average.


title:
HybridRanker: Integrating network structure and disease knowledge to
  prioritize cancer candidate genes

abstract:
  One of the notable fields in studying the genetics of cancer is disease gene
identification which affects disease treatment and drug discovery. Many
researches have been done in this field. Genome-wide association studies (GWAS)
are one of them that focus on the identification of diseases-susceptible loci
on chromosomes. Recently, computational approaches, known as gene
prioritization methods have been used to identify candidate disease genes. Gene
prioritization methods integrate several data sources to discover and
prioritize the most probable candidate disease genes. In this paper, we propose
a prioritization method, called HybridRanker which is a network-based technique
and it also uses experimental data to identify candidate cancer genes. We apply
our proposed method on colorectal cancer data. It is notable to say that in
HybridRanker, for considering both local and global network information of a
protein-protein interaction network, different algorithms such as
shortest-path, random walk with restart and network propagation are exploited.
By using these algorithms, initial scores are given to genes within the
network. Furthermore, by looking through diseases with similar symptoms and
also comorbid diseases and by extracting their causing genes, the gene scores
are recalculated. We also use gene-phenotype relations for an additional
scoring of the candidate genes. Our method is validated and compared with other
prioritization methods in leave one-out cross-validation and the comparison
results show the better performance of the HybridRanker.


title:
NRSSPrioritize: Associating Protein Complex and Disease Similarity
  Information to Prioritize Disease Candidate Genes

abstract:
  The identification of disease-associated genes has recently gathered much
attention for uncovering disease complex mechanisms that could lead to new
insights into the treatment of diseases. For exploring disease-susceptible
genes, not only experimental approaches such as genome-wide association studies
(GWAS) have been used, but also computational methods. Since experimental
approaches are both time-consuming and expensive, numerous studies have
utilized computational techniques to explore disease genes. These methods use
various biological data sources and known disease genes to prioritize disease
candidate genes. In this paper, we propose a gene prioritization method
(NRSSPrioritize), which benefits from both local and global measures of a
protein-protein interaction (PPI) network and also from disease similarity
knowledge to suggest candidate genes for colorectal cancer (CRC)
susceptibility. Network Propagation, Random Walk with Restart, and Shortest
Paths are three network analysis tools that are applied to a PPI network for
the purpose of scoring candidate genes. Also, by looking through diseases with
similar symptoms to CRC and obtaining their causing genes, candidate genes are
scored in a different way. Finally, to integrate these four different scoring
schemes, Technique for Order Preference by Similarity to Ideal Solution
(TOPSIS) and Analytic Network Process (ANP) methods are applied to obtain
appropriate weights for the above four quantified measures and the weighted
summation of these measures are used to calculate the final score of each
candidate gene. NRSSPrioritize was validated by cross-validation analysis and
its results were compared with other prioritization tools, which gave the best
performance when using our proposed method.


title:
Quasi-local gravitational angular momentum and centre of mass from
  generalised Witten equations

abstract:
  Witten's proof for the positivity of the ADM mass gives a definition of
energy in terms of three-surface spinors. In this paper, we give a
generalisation for the remaining six Poincar\'e charges at spacelike infinity,
which are the angular momentum and centre of mass. The construction improves on
certain three-surface spinor equations introduced by Shaw. We solve these
equations asymptotically obtaining the ten Poincar\'e charges as integrals over
the Nester--Witten two-form. We point out that the defining differential
equations can be extended to three-surfaces of arbitrary signature and we study
them on the entire boundary of a compact four-dimensional region of spacetime.
The resulting quasi-local expressions for energy and angular momentum are
integrals over a two-dimensional cross-section of the boundary. For any two
consecutive such cross-sections, conservation laws are derived that determine
the influx (outflow) of matter and gravitational radiation.


title: Balancing Appearance and Context in Sketch Interpretation

abstract:
  We describe a sketch interpretation system that detects and classifies clock
numerals created by subjects taking the Clock Drawing Test, a clinical tool
widely used to screen for cognitive impairments (e.g., dementia). We describe
how it balances appearance and context, and document its performance on some
2,000 drawings (about 24K clock numerals) produced by a wide spectrum of
patients. We calibrate the utility of different forms of context, describing
experiments with Conditional Random Fields trained and tested using a variety
of features. We identify context that contributes to interpreting otherwise
ambiguous or incomprehensible strokes. We describe ST-slices, a novel
representation that enables "unpeeling" the layers of ink that result when
people overwrite, which often produces ink impossible to analyze if only the
final drawing is examined. We characterize when ST-slices work, calibrate their
impact on performance, and consider their breadth of applicability.


title:
Scanning tunneling microscopy of superconducting topological surface
  states in Bi$_2$Se$_3$

abstract:
  In this paper we present scanning tunneling microscopy of a large
$\textrm{Bi}_2\textrm{Se}_3$ crystal with superconducting PbBi islands
deposited on the surface. Local density of states measurements are consistent
with induced superconductivity in the topological surface state with a
coherence length of order 540 nm. At energies above the gap the density of
states exhibits oscillations due to scattering caused by a nonuniform order
parameter. Strikingly, the spectra taken on islands also display similar
oscillations along with traces of the Dirac cone, suggesting an inverse
topological proximity effect.


title: Discovery of a deep Seyfert-2 galaxy at z = 0.222 behind NGC 300

abstract:
  We report on the unveiling of the nature of the unidentified X-ray source
3XMM J005450.3-373849 as a Seyfert-2 galaxy located behind the spiral galaxy
NGC 300 using Hubble Space Telescope data, new spectroscopic Gemini
observations and available XMM-Newton and Chandra data. We show that the X-ray
source is positionally coincident with an extended optical source, composed by
a marginally resolved nucleus/bulge, surrounded by an elliptical disc-like
feature and two symmetrical outer rings. The optical spectrum is typical of a
Seyfert-2 galaxy redshifted to z=0.222 +/- 0.001, which confirms that the
source is not physically related to NGC 300. At this redshift the source would
be located at 909+/-4 Mpc (comoving distance in the standard model). The X-ray
spectra of the source are well-fitted by an absorbed power-law model. By tying
$N_\mathrm{H}$ between the six available spectra, we found a variable index
$\Gamma$ running from ~2 in 2000-2001 years, to 1.4-1.6 in the 2005-2014
period. Alternatively, by tying $\Gamma$, we found variable absorption columns
of N_H ~ 0.34 x $10^{-22}$ cm$^{-2}$ in 2000-2001 years, and 0.54-0.75 x
$10^{-22}$ cm$^{-2}$ in the 2005-2014 period. Although we cannot distinguish
between an spectral or absorption origin, from the derived unabsorbed X-ray
fluxes, we are able to assure the presence of long-term X-ray variability.
Furthermore, the unabsorbed X-ray luminosities of 0.8-2 x 10$^{43}$ erg
s$^{-1}$ derived in the X-ray band are in agreement with a weakly obscured
Seyfert-2 AGN at $z \approx 0.22$.


title: Degree and Sensitivity: tails of two distributions

abstract:
  The sensitivity of a Boolean function f is the maximum over all inputs x, of
the number of sensitive coordinates of x. The well-known sensitivity conjecture
of Nisan (see also Nisan and Szegedy) states that every sensitivity-s Boolean
function can be computed by a polynomial over the reals of degree poly(s). The
best known upper bounds on degree, however, are exponential rather than
polynomial in s.
  Our main result is an approximate version of the conjecture: every Boolean
function with sensitivity s can be epsilon-approximated (in L_2) by a
polynomial whose degree is O(s log(1/epsilon)). This is the first improvement
on the folklore bound of s/epsilon. Further, we show that improving the bound
to O(s^c log(1/epsilon)^d)$ for any d < 1 and any c > 0 will imply the
sensitivity conjecture. Thus our result is essentially the best one can hope
for without proving the conjecture.
  We postulate a robust analogue of the sensitivity conjecture: if most inputs
to a Boolean function f have low sensitivity, then most of the Fourier mass of
f is concentrated on small subsets, and present an approach towards proving
this conjecture.


title: CN Zeeman and dust polarization in a high-mass cold clump

abstract:
  We report on the young massive clump (G35.20w) in W48 that previous molecular
line and dust observations have revealed to be in the very early stages of star
formation. Based on virial analysis, we find that a strong field of ~1640
microG is required to keep the clump in pressure equilibrium. We performed a
deep Zeeman effect measurement of the 113 GHz CN (1-0) line towards this clump
with the IRAM 30 m telescope. We combine simultaneous fitting of all CN
hyperfines with Monte Carlo simulations for a large range in realization of the
magnetic field to obtain a constraint on the line-of-sight field strength of
-687 +/- 420 microG. We also analyze archival dust polarization observations
towards G35.20w. A strong magnetic field is implied by the remarkably ordered
field orientation that is perpendicular to the longest axis of the clump. Based
on this, we also estimate the plane-of-sky component of the magnetic field to
be ~740 microG. This allows for a unique comparison of the two orthogonal
measurements of magnetic field strength of the same region and at similar
spatial scales. The expected total field strength shows no significant conflict
between the observed field and that required for pressure equilibrium. By
producing a probability distribution for a large range in field geometries, we
show that plane-of-sky projections are much closer to the true field strengths
than line-of-sight projections. This can present a significant challenge for
Zeeman measurements of magnetized structures, even with ALMA. We also show that
CN molecule does not suffer from depletion on the observed scales in the
predominantly cold and highly deuterated core in an early stage of high-mass
star formation and is thus a good tracer of the dense gas.


title: On the Deuterium-to-Hydrogen Ratio of the Interstellar Medium

abstract:
  Observations show that the global deuterium-to-hydrogen ratio (D/H) in the
local interstellar medium (ISM) is about 90% of the primordial ratio predicted
by big bang nucleosynthesis. The high (D/H)$_{ISM}$ implies that only a small
fraction of interstellar gas has been processed through stars, which destroy
any deuterium they are born with. Using analytic arguments for one-zone
chemical evolution models that include accretion and outflow, I show that the
deuterium abundance is tightly coupled to the abundance of core collapse
supernova (CCSN) elements such as oxygen. These models predict that the ratio
of (D/H)$_{ISM}$ to the primordial abundance is $\approx 1/(1+r Z_O/m_O)$,
where r is the recycling fraction, $Z_O$ is the ISM oxygen mass fraction, and
$m_O$ is the population averaged CCSN yield of oxygen. Using values $r=0.4$ and
$m_O=0.015$ appropriate to a Kroupa (2001) initial mass function and recent
CCSN yield calculations, solar oxygen abundance corresponds to an ISM (D/H)
that is 87\% of the primordial value, consistent with observations. This
approximation is accurate for a wide range of parameter values, and physical
arguments suggest that it should remain accurate for more complex chemical
evolution models, making the deuterium abundance a robust prediction of almost
any model that reproduces the observed ISM metallicity. The good agreement with
the upper range of observed (D/H)$_{ISM}$ values supports the long-standing
suggestion that sightline-to-sightline variations of deuterium are a
consequence of dust depletion, rather than a low global (D/H)$_{ISM}$ enhanced
by localized accretion of primordial composition gas. This agreement limits
deviations from conventional yield and recycling values, and it implies that
Galactic outflows eject ISM hydrogen as efficiently as they eject CCSN metals.


title: Equilibrium and Sudden Events in Chemical Evolution

abstract:
  We present new analytic solutions for one-zone (fully mixed) chemical
evolution models and explore their implications. In contrast to existing
analytic models, we incorporate a realistic delay time distribution for Type Ia
supernovae (SNIa) and can therefore track the separate evolution of
$\alpha$-elements produced by core collapse supernovae (CCSNe) and iron peak
elements synthesized in both CCSNe and SNIa. In generic cases, $\alpha$ and
iron abundances evolve to an equilibrium at which element production is
balanced by metal consumption and gas dilution, instead of continuing to
increase over time. The equilibrium absolute abundances depend principally on
supernova yields and the outflow mass loading parameter $\eta$, while the
equilibrium abundance ratio [$\alpha$/Fe] depends mainly on yields and
secondarily on star formation history. A stellar population can be metal-poor
either because it has not yet evolved to equilibrium or because high outflow
efficiency makes the equilibrium abundance itself low. Systems with ongoing gas
accretion develop metallicity distribution functions (MDFs) that are sharply
peaked, while "gas starved" systems with rapidly declining star formation have
broadly peaked MDFs. A burst of star formation that consumes a significant
fraction of a system's available gas can temporarily boost [$\alpha$/Fe] by
0.1-0.3 dex, a possible origin for rare, $\alpha$-enhanced stars with
intermediate age or high metallicity. Other sudden transitions in system
properties can produce surprising behavior, including backward evolution of a
stellar population from high metallicity to low metallicity. An Appendix
provides a user's guide for calculating enrichment histories, [$\alpha$/Fe]
tracks, and MDFs for a wide variety of scenarios, including flexible forms of
star formation history.


title:
Long Time Asymptotic Behavior of the Focusing Nonlinear Schrodinger
  Equation

abstract:
  We study the Cauchy problem for the focusing nonlinear Schrodinger (NLS)
equation. Using the DBAR generalization of the nonlinear steepest descent
method we compute the long time asymptotic expansion of the solution in any
fixed space-time cone x_1 + v_1 t <= x <= x_2 + v_2 t with v_1 <= v_2 up to an
(optimal) residual error of order O(t^(-3/4)). In each (x,t) cone the leading
order term in this expansion is a multi-soliton whose parameters are modulated
by soliton-soliton and soliton-radiation interactions as one moves through the
cone. Our results only require that the initial data possess one L^2(R) moment
and (weak) derivative and that it not generate any spectral singularities
(embedded eigenvalues).


title: Entropy in adiabatic regions of convection simulations

abstract:
  One of the largest sources of uncertainty in stellar models is caused by the
treatment of convection in stellar envelopes. One dimensional stellar models
often make use of the mixing length or equivalent approximations to describe
convection, all of which depend on various free parameters. There have been
attempts to rectify this by using 3D radiative-hydrodynamic simulations of
stellar convection, and in trying to extract an equivalent mixing length from
the simulations. In this paper we show that the entropy of the deeper,
adiabatic layers in these simulations can be expressed as a simple function of
og g and log T_{eff} which holds potential for calibrating stellar models in a
simple and more general manner.


title:
Multi-channel assault on natural supersymmetry at the high luminosity
  LHC

abstract:
  Recent clarifications of naturalness in supersymmetry robustly require the
presence of four light higgsinos with mass ~100-300 GeV while gluinos and
(top)-squarks may lie in the multi-TeV range, possibly out of LHC reach. We
project the high luminosity (300-3000 fb^{-1}) reach of LHC14 via gluino
cascade decays and via same-sign diboson production. We compare these to the
reach for neutralino pair production \tz_1\tz_2 followed by
\tz_2\to\tz_1\ell^+\ell^- decay to soft dileptons which recoil against a hard
jet. It appears that 3000 fb^{-1} is just about sufficient integrated
luminosity to probe naturalness with up to 3\% fine-tuning at the 5-sigma
level, thus either discovering natural supersymmetry or else ruling it out.