title:
Applying Artifical Neural Networks To Predict Nominal Vehicle
  Performance

abstract:
  This paper investigates the use of artificial neural networks (ANNs) to
replace traditional algorithms and manual review for identifying anomalies in
vehicle run data. The specific data used for this study is from undersea
vehicle qualification tests. Such data is highly non-linear, therefore
traditional algorithms are not adequate and manual review is time consuming. By
using ANNs to predict nominal vehicle performance based solely on information
available pre-run, vehicle deviation from expected performance can be
automatically identified in the post-run data. Such capability is only now
becoming available due to the rapid increase in understanding of ANN framework
and available computing power in the past decade. The ANN trained for the
purpose of this investigation is relatively simple, to keep the computing
requirements within the parameters of a modern desktop PC. This ANN showed
potential in predicting vehicle performance, particularly during transient
events within the run data. However, there were also several performance cases,
such as steady state operation and cases which did not have sufficient training
data, where the ANN showed deficiencies. It is expected that as computational
power becomes more readily available, ANN understanding matures, and more
training data is acquired from real world tests, the performance predictions of
the ANN will surpass traditional algorithms and manual human review.


title: gadfly: A pandas-based Framework for Analyzing GADGET Simulation Data

abstract:
  We present the first public release (v0.1) of the open-source GADGET
Dataframe Library: gadfly. The aim of this package is to leverage the
capabilities of the broader python scientific computing ecosystem by providing
tools for analyzing simulation data from the astrophysical simulation codes
GADGET and GIZMO using pandas, a thoroughly documented, open-source library
providing high-performance, easy-to-use data structures that is quickly
becoming the standard for data analysis in python. Gadfly is a framework for
analyzing particle-based simulation data stored in the HDF5 format using pandas
DataFrames. The package enables efficient memory management, includes utilities
for unit handling, coordinate transformations, and parallel batch processing,
and provides highly optimized routines for visualizing smoothed-particle
hydrodynamics (SPH) datasets.


title:
Distributed Inexact Damped Newton Method: Data Partitioning and
  Load-Balancing

abstract:
  In this paper we study inexact dumped Newton method implemented in a
distributed environment. We start with an original DiSCO algorithm
[Communication-Efficient Distributed Optimization of Self-Concordant Empirical
Loss, Yuchen Zhang and Lin Xiao, 2015]. We will show that this algorithm may
not scale well and propose an algorithmic modifications which will lead to less
communications, better load-balancing and more efficient computation. We
perform numerical experiments with an regularized empirical loss minimization
instance described by a 273GB dataset.


title:
First-principles study of the magnetic ground state in kagome
  francisites Cu3Bi(SeO3)2O2X (X=Cl, Br)

abstract:
  We explore magnetic behavior of kagome francisites Cu3Bi(SeO3)2O2X (X = Cl
and Br) using first-principles calculations. To this end, we propose an
approach based on the Hubbard model in the Wannier functions basis constructed
on the level of local-density approximation (LDA). The ground-state spin
configuration is determined by a Hartree-Fock solution of the Hubbard model
both in zero magnetic field and in applied magnetic fields. Additionally,
parameters of an effective spin Hamiltonian are obtained by taking into account
the hybridization effects and spin-orbit coupling. We show that only the former
approach, the Hartree-Fock solution of the Hubbard model, allows for a complete
description of the anisotropic magnetization process. While our calculations
confirm that the canted zero-field ground state arises from a competition
between ferromagnetic nearest-neighbor and antiferromagnetic
next-nearest-neighbor couplings in the kagome planes, weaker anisotropic terms
are crucial for fixing spin directions and for the overall magnetization
process. We thus show that the Hartree-Fock solution of an electronic
Hamiltonian is a viable alternative to the analysis of effective spin
Hamiltonians when a magnetic ground state and effects of external field are
considered.


title:
The effects of three-dimensional defects on one-way surface plasmon
  propagation for photonic topological insulators comprised of continuous media

abstract:
  We have investigated the one-way surface plasmon-polariton (SPP) at the
interface of a continuous magneto-plasma material and metal. We demonstrated
that TM modes inside a continuous material can be assigned non-trivial Chern
numbers analogous to those of topological photonic crystals; moreover these
Chern numbers can be calculated analytically. This leads to the appearance of
topologically protected surface modes propagating at frequencies inside the
bandgap of the magneto-plasma. Previous works considered 2D structures; here we
consider the effects of 3D defects, and show that, although backward
propagation/reflection cannot occur, side scattering does take place and it has
significant effect on the propagation of the surface mode. Several different
waveguiding geometries are considered for reducing the effects of
side-scattering, and we also consider the effects of metal loss.


title: Shocks in nova outflows. II. Synchrotron radio emission

abstract:
  The discovery of GeV gamma-rays from classical novae indicates that shocks
and relativistic particle acceleration are energetically key in these events.
Further evidence for shocks comes from thermal keV X-ray emission and an early
peak in the radio light curve on a timescale of months with a brightness
temperature which is too high to result from freely expanding photo-ionized
gas. Paper I developed a one dimensional model for the thermal emission from
nova shocks. This work concluded that the shock-powered radio peak cannot be
thermal if line cooling operates in the post-shock gas at the rate determined
by collisional ionization equilibrium. Here we extend this calculation to
include non-thermal synchrotron emission. Applying our model to three classical
novae, we constrain the amplification of the magnetic field $\epsilon_B$ and
the efficiency $\epsilon_e$ of accelerating relativistic electrons of
characteristic Lorentz factor $\gamma \sim 100$. If the shocks are radiative
(low velocity $v_{\rm sh} \lesssim 1000$ km s$^{-1}$) and cover a large solid
angle of the nova outflow, as likely characterize those producing gamma-rays,
then values of $\epsilon_e \sim 0.01-0.1$ are required to achieve the peak
radio brightness for $\epsilon_B = 10^{-2}$. Such high efficiencies exclude
secondary pairs from pion decay as the source of the radio-emitting particles,
instead favoring the direct acceleration of electrons at the shock. If the
radio-emitting shocks are instead adiabatic (high velocity), as likely
characterize those responsible for the thermal X-rays, then much higher
brightness temperatures are possible, allowing the radio-emitting shocks to
cover a smaller outflow solid angle.


title:
Setting the Stage for a Non-Supersymmetric UV-Complete String
  Phenomenology

abstract:
  In this talk, I discuss our recent work concerning the construction of
non-supersymmetric heterotic string models which have exponentially suppressed
dilaton tadpoles and cosmological constants, and thus greatly enhanced
stability properties. The existence of such models opens the door to
non-supersymmetric string model-building, and I discuss how semi-realistic
string models resembling the Standard Model or any of its unified variants may
be constructed within this framework. These models maintain modular invariance
and exhibit a misaligned supersymmetry which ensures UV finiteness, even
without spacetime supersymmetry. I also discuss the potential implications for
phenomenology.


title:
(p,q)-Five Brane and (p,q)-String Solutions, their Bound State and its
  Near Horizon Limit

abstract:
  We determine (p,q)-string and (p,q)-five brane solutions of type IIB
supergravity using SL(2,Z)-symmetry of the full type IIB superstring theory. We
also determine SL(2,Z)-transformed solution corresponding to the bound state of
NS5-branes and fundamental strings. Then we analyze its near horizon limit and
we show that it leads to the AdS(3)xS(3) with mixed fluxes.


title: Embedding by Normalisation

abstract:
  This paper presents the insight that practical embedding techniques, commonly
used for implementing Domain-Specific Languages, correspond to theoretical
Normalisation-By-Evaluation (NBE) techniques, commonly used for deriving
canonical form of terms with respect to an equational theory.
  NBE constitutes of four components: a syntactic domain, a semantic domain,
and a pair of translations between the two. Embedding also often constitutes of
four components: an object language, a host language, encoding of object terms
in the host, and extraction of object code from the host.
  The correspondence is deep in that all four components in embedding and NBE
correspond to each other. Based on this correspondence, this paper introduces
Embedding-By-Normalisation (EBN) as a principled approach to study and
structure embedding.
  The correspondence is useful in that solutions from NBE can be borrowed to
solve problems in embedding. In particular, based on NBE techniques, such as
Type-Directed Partial Evaluation, this paper presents a solution to the problem
of extracting object code from embedded programs involving sum types, such as
conditional expressions, and primitives, such as literals and operations on
them.


title:
Universal relations between nongaussian fluctuations in heavy-ion
  collisions

abstract:
  We show that universality near a critical end point implies a characteristic
relation between third- and fourth-order baryon susceptibilities $\chi_3$ and
$\chi_4$, resulting in a banana-shaped loop when $\chi_4$ is plotted as a
function of $\chi_3$ along a freeze-out line. Including the individual
enhancements of $\chi_3$ and $\chi_4$ near a critical point, these features may
be a consistent set of observations supporting the interpretation of baryon
fluctuations data as arising from criticality.


title: Triangle-hinge models for unoriented membranes

abstract:
  Triangle-hinge models [arXiv:1503.08812] are introduced to describe
worldvolume dynamics of membranes. The Feynman diagrams consist of triangles
glued together along hinges and can be restricted to tetrahedral decompositions
in a large N limit. In this paper, after clarifying that all the tetrahedra
resulting in the original models are orientable, we define a version of
triangle-hinge models that can describe the dynamics of unoriented membranes.
By regarding each triangle as representing a propagation of an open membrane of
disk topology, we introduce a local worldvolume parity transformation which
inverts the orientation of triangle, and define unoriented triangle-hinge
models by gauging the transformation. Unlike two-dimensional cases, this local
transformation generally relates a manifold to a nonmanifold, but still is a
well-defined manipulation among tetrahedral decompositions. We further show
that matter fields can be introduced in the same way as in the original
oriented models. In particular, the models will describe unoriented membranes
in a target spacetime by taking matter fields to be the target space
coordinates.


title:
Multi-Vehicle Collision Avoidance via Hamilton-Jacobi Reachability and
  Mixed Integer Programming

abstract:
  Multi-agent differential games are important and useful tools for analyzing
many practical problems. With the recent surge of interest in using UAVs for
civil purposes, the importance and urgency of developing tractable multi-agent
analysis techniques that provide safety and performance guarantees is at an
all-time high. Hamilton-Jacobi (HJ) reachability has successfully provided
safety guarantees to small-scale systems and is flexible in terms of system
dynamics. However, the exponential complexity scaling of HJ reachability
prevents its direct application to large scale problems when the number of
vehicles is greater than two. In this paper, we overcome the scalability
limitations of HJ reachability by using a mixed integer program that exploits
the properties of HJ solutions to provide higher-level control logic. Our
proposed method provides safety guarantee for three-vehicle systems -- a
previously intractable task for HJ reachability -- without incurring
significant additional computation cost. Furthermore, our method is scalable
beyond three vehicles and performs significantly better by several metrics than
an extension of pairwise collision avoidance to multi-vehicle collision
avoidance. We demonstrate our proposed method in simulations.


title:
Understanding and Improving Convolutional Neural Networks via
  Concatenated Rectified Linear Units

abstract:
  Recently, convolutional neural networks (CNNs) have been used as a powerful
tool to solve many problems of machine learning and computer vision. In this
paper, we aim to provide insight on the property of convolutional neural
networks, as well as a generic method to improve the performance of many CNN
architectures. Specifically, we first examine existing CNN models and observe
an intriguing property that the filters in the lower layers form pairs (i.e.,
filters with opposite phase). Inspired by our observation, we propose a novel,
simple yet effective activation scheme called concatenated ReLU (CRelu) and
theoretically analyze its reconstruction property in CNNs. We integrate CRelu
into several state-of-the-art CNN architectures and demonstrate improvement in
their recognition performance on CIFAR-10/100 and ImageNet datasets with fewer
trainable parameters. Our results suggest that better understanding of the
properties of CNNs can lead to significant performance improvement with a
simple modification.


title: Packing, coding, and ground states

abstract:
  These are the lecture notes from my 2014 PCMI graduate summer school
lectures. In these lectures, we'll study simple models of materials from
several different perspectives: geometry (packing problems), information theory
(error-correcting codes), and physics (ground states of interacting particle
systems). These perspectives each shed light on some of the same problems and
phenomena, while highlighting different techniques and connections. One
noteworthy phenomenon is the exceptional symmetry that is found in certain
special cases, and we'll examine when and why it occurs. The overall theme of
the lectures is thus order vs. disorder. How much symmetry can we expect to see
in optimal geometric structures?


title: Convergence of loop-erased random walk in the natural parametrization

abstract:
  Loop-erased random walk, abbreviated LERW, is one of the most well-studied
critical lattice models. It is the self-avoiding random walk one gets after
erasing the loops from a simple random walk in order or alternatively by
considering the branches in a uniformly chosen spanning tree. This paper proves
that planar LERW parametrized by renormalized length converges in the lattice
size scaling limit to SLE(2) parametrized by 5/4-dimensional Minkowski content.
In doing this we also provide a method for proving similar convergence results
for other models converging to SLE. Besides the main theorem, several of our
results about LERW are of independent interest: for example, two-point
estimates, estimates on maximal content, and a "separation lemma".


title: A Probabilistic Angle on One Loop Scalar Integrals

abstract:
  Recasting the $N$-point one loop scalar integral as a probabilistic problem,
allows the derivation of integral recurrence relations as well as exact
analytical expressions in the most common cases. $\epsilon$ expansions are
derived by writing a formula that relates an $N$-point function in decimal
dimension to an $N$-point function in integer dimension. As an example, we give
relations for the massive 5-point function in dimension $n=4-2\epsilon$,
$n=6-2\epsilon$. The reduction of tensor integrals of rank 2 with $N=5$ is
achieved showing the method's potential. Hypergeometric functions are not
needed but only integration of arcsine function whose analytical continuation
is well known.


title: Fast Reachable Set Approximations via State Decoupling Disturbances

abstract:
  With the recent surge of interest in using robotics and automation for civil
purposes, providing safety and performance guarantees has become extremely
important. In the past, differential games have been successfully used for the
analysis of safety-critical systems. In particular, the Hamilton-Jacobi (HJ)
formulation of differential games provides a flexible way to compute the
reachable set, which can characterize the set of states which lead to either
desirable or undesirable configurations, depending on the application. While HJ
reachability is applicable to many small practical systems, the curse of
dimensionality prevents the direct application of HJ reachability to many
larger systems. To address computation complexity issues, various efficient
computation methods in the literature have been developed for approximating or
exactly computing the solution to HJ partial differential equations, but only
when the system dynamics are of specific forms. In this paper, we propose a
flexible method to trade off optimality with computation complexity in HJ
reachability analysis. To achieve this, we propose to simplify system dynamics
by treating state variables as disturbances. We prove that the resulting
approximation is conservative in the desired direction, and demonstrate our
method using a four-dimensional plane model.


title:
Fractal scattering of Gaussian solitons in directional couplers with
  logarithmic nonlinearities

abstract:
  In this paper we study the interaction of Gaussian solitons in a dispersive
and nonlinear media with log-law nonlinearity. The model is described by the
coupled logarithmic nonlinear Schr\"odinger equations, which is a nonintegrable
system that allows the observation of a very rich scenario in the collision
patterns. By employing a variational approach and direct numerical simulations,
we observe a fractal-scattering phenomenon from the exit velocities of each
soliton as a function of the input velocities. Furthermore, we introduce a
linearization model to identify the position of the reflection/transmission
window that emerges within the chaotic region. This enable us the possibility
of controlling the scattering of solitons as well as the lifetime of bound
states.


title:
Spin-valley locking in the normal state of a transition-metal
  dichalocogenide superconductor

abstract:
  The metallic transition-metal dichalcogenides (TMDCs) are benchmark systems
for studying and controlling intertwined electronic orders in solids, with
superconductivity developing upon cooling from a charge density wave state. The
interplay between such phases is thought to play a critical role in the
unconventional superconductivity of cuprates, Fe-based, and heavy-fermion
systems, yet even for the more moderately-correlated TMDCs, their nature and
origins have proved highly controversial. Here, we study a prototypical
example, $2H$-NbSe$_2$, by spin- and angle-resolved photoemission and
first-principles theory. We find that the normal state, from which its hallmark
collective phases emerge, is characterised by quasiparticles whose spin is
locked to their valley pseudospin. This results from a combination of strong
spin-orbit interactions and local inversion symmetry breaking. Non-negligible
interlayer coupling further drives a rich three-dimensional momentum-dependence
of the underlying Fermi surface spin texture. Together, these findings
necessitate a fundamental re-investigation of the nature of charge order and
superconducting pairing in NbSe$_2$ and related TMDCs.

categories: cond-mat.supr-con cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.str-el


title:
Safe Sequential Path Planning Under Disturbances and Imperfect
  Information

abstract:
  Multi-UAV systems are safety-critical, and guarantees must be made to ensure
no unsafe configurations occur. Hamilton-Jacobi (HJ) reachability is ideal for
analyzing such safety-critical systems; however, its direct application is
limited to small-scale systems of no more than two vehicles due to an
exponentially-scaling computational complexity. Previously, the sequential path
planning (SPP) method, which assigns strict priorities to vehicles, was
proposed; SPP allows multi-vehicle path planning to be done with a
linearly-scaling computational complexity. However, the previous formulation
assumed that there are no disturbances, and that every vehicle has perfect
knowledge of higher-priority vehicles' positions. In this paper, we make SPP
more practical by providing three different methods to account for disturbances
in dynamics and imperfect knowledge of higher-priority vehicles' states. Each
method has different assumptions about information sharing. We demonstrate our
proposed methods in simulations.


title: Causality, initial conditions, and inflationary magnetogenesis

abstract:
  The post-inflationary evolution of inflation-produced magnetic fields,
conventional or not, can change dramatically when two fundamental issues are
accounted for. The first is causality, which demands that local physical
processes can never affect superhorizon perturbations. The second is the nature
of the transition from inflation to reheating and then to the radiation era,
which determine the initial conditions at the start of these epochs. Causality
implies that inflationary magnetic fields dot not freeze into the matter until
they have re-entered the causal horizon. The nature of the cosmological
transitions and the associated initial conditions, on the other hand, determine
the large-scale magnetic evolution after inflation. Put together, the two can
slow down the adiabatic magnetic decay on superhorizon scales throughout the
universe's post-inflationary evolution and thus lead to considerably stronger
residual magnetic fields. This is "good news" for both the conventional and the
non-conventional scenarios of cosmic magnetogenesis. Mechanisms operating
outside standard electromagnetism, in particular, do not need to enhance their
fields too much during inflation, in order to produce seeds that can feed the
galactic dynamo today. In fact, even conventionally produced inflationary
magnetic fields might be able to sustain the dynamo.


title: New longitudinal mode and compression of pair ions in plasma

abstract:
  Positive and negative ions forming so-called pair plasma differing in sign of
their charge but asymmetric in mass and temperature support a new acoustic mode
where damping of heavier ion dominates. The condition for the excitation of ion
sound wave through electron beam induced Cherenkov instability is also
investigated. This beam can generate a perturbation in the pair ion plasmas in
the presence of electrons when there is number density, temperature and mass
difference in the two species of ions. Basic emphasis is on the focusing of ion
sound waves and we show how, in the area of localization of wave energy, the
density of pair particles increases while electrons are pushed away from that
region. Further, this localization of wave is dependent on the shape of the
pulse. Considering the example of pancake and bullet shaped pulses, we find
that only the former leads to compression of pair ions in the supersonic regime
of the focusing region. Here possible existence of regions where pure pair
particles can exist may also be speculated which is not only useful from
academic point of view but also to mimic the situation of plasma (electro
positron asymmetric and symmetric) observed in astrophysical environment.


title:
Comparison of adaptive multiresolution and adaptive mesh refinement
  applied to simulations of the compressible Euler equations

abstract:
  We present a detailed comparison between two adaptive numerical approaches to
solve partial differential equations (PDEs), adaptive multiresolution (MR) and
adaptive mesh refinement (AMR). Both discretizations are based on finite
volumes in space with second order shock-capturing, and explicit time
integration either with or without local time-stepping. The two methods are
benchmarked for the compressible Euler equations in Cartesian geometry. As test
cases a 2D Riemann problem, Lax-Liu 6, and a 3D ellipsoidally expanding shock
wave have been chosen. We compare and assess their computational efficiency in
terms of CPU time and memory requirements. We evaluate the accuracy by
comparing the results of the adaptive computations with those obtained with the
corresponding FV scheme using a regular fine mesh. We find that both approaches
yield similar trends for CPU time compression for increasing number of
refinement levels. MR exhibits more efficient memory compression than AMR and
shows slightly enhanced convergence; however, a larger absolute overhead is
measured for the tested codes.


title: Analysis of the Cuban journal Bibliotecas: Anales de Investigacion

abstract:
  The objective of this article is to describe the academic impact, the
editorial process quality, and the editorial and visibility strategies of
Bibliotecas. Anales de Investigacion (BAI), a scientific Cuban journal edited
by National Library of Cuba Jose Marti. The academic impact is determined
through a citation analysis, which considers Google Scholar database as
reference source. The bibliometric indicators applied are: citation per year,
citation vs. self-citation, citable journals vs. non-citable documents, Hirsch
Index, and impact factor. The editorial process quality and the visibility
strategies are determined through a self-evaluation which takes into account
the SciELO, Scopus, CLASE, Redalyc, Latindex, Dialnet, and ERIH PLUS
methodologies. The results reveal an ascending citation line that highlights
citing journals from the field of Library and Information Science, Medicine and
Health Sciences, and Education. Aspects related content and format have
negatively influenced on editorial process quality. Some strategies are
proposed to improve scientific visibility through the inclusion in databases,
directories, and social and academic networks. In general, this study
contributes to the editorial decision taking, an issue that could augment the
impact and scientific visibility of BAI.


title: Jet effects in high-multiplicity pp events

abstract:
  The study of the high-multiplicity pp events has become important because we
need to understand the origin of the fluid-like features which have been found
in such small systems. In this work we concentrate on the radial flow
signatures. To this end, the role of jets in high-multiplicity pp collisions is
investigated using PYTHIA 8.


title: Guard Your Daggers and Traces: Properties of Guarded (Co-)recursion

abstract:
  Motivated by the recent interest in models of guarded (co-)recursion, we
study their equational properties. We formulate axioms for guarded fixpoint
operators generalizing the axioms of iteration theories of Bloom and \'Esik.
Models of these axioms include both standard (e.g., cpo-based) models of
iteration theories and models of guarded recursion such as complete metric
spaces or the topos of trees studied by Birkedal et al. We show that the
standard result on the satisfaction of all Conway axioms by a unique dagger
operation generalizes to the guarded setting. We also introduce the notion of
guarded trace operator on a category, and we prove that guarded trace and
guarded fixpoint operators are in one-to-one correspondence. Our results are
intended as first steps leading, hopefully, towards future description of
classifying theories for guarded recursion.


title:
Phase Retrieval from 1D Fourier Measurements: Convexity, Uniqueness, and
  Algorithms

abstract:
  This paper considers phase retrieval from the magnitude of 1D over-sampled
Fourier measurements, a classical problem that has challenged researchers in
various fields of science and engineering. We show that an optimal vector in a
least-squares sense can be found by solving a convex problem, thus establishing
a hidden convexity in Fourier phase retrieval. We also show that the standard
semidefinite relaxation approach yields the optimal cost function value (albeit
not necessarily an optimal solution) in this case. A method is then derived to
retrieve an optimal minimum phase solution in polynomial time. Using these
results, a new measuring technique is proposed which guarantees uniqueness of
the solution, along with an efficient algorithm that can solve large-scale
Fourier phase retrieval problems with uniqueness and optimality guarantees.

categories: math.OC cs.IR cs.IT math.IT math.ST stat.AP stat.TH


title:
Cooperative coupling of static magnetism and bulk superconductivity in
  the stripe phase of La_2-xBa_xCuO_4: Pressure- and doping-dependent studies

abstract:
  Static spin-stripe order and superconductivity were systematically studied in
La_2-xBa_xCuO_4 (0.11 - 0.17) at ambient pressure by means of magnetization and
muSR experiments. We find that all the investigated La_2-xBa_xCuO_4 samples
exhibit static spin-stripe order and that the quasi two-dimensional
superconducting (SC) transition temperature T_c1 and the static spin-stripe
order temperature T_so have very similar values throughout the phase diagram.
Moreover, the magnetic and the SC properties of the x = 0.155 (LBCO-0.155) and
x = 0.17 (LBCO-0.17) samples were studied under hydrostatic pressure. As a
remarkable result, in these bulk cuprate superconductors the three-dimensional
SC transition temperature T_c and T_so nearly coincide at all pressure
investigated (0 - 2.3 GPa). We also observed a pressure induced transition from
long-range spin stripe order to a disordered magnetic state at 1.6 GPa in
LBCO-0.155, coexisting with a SC state with substantial superfluid density. In
LBCO-0.17 a disordered magnetic state is present at all p. The present results
indicate that static magnetic order and SC pairing correlations develop in a
cooperative fashion in La_2-xBa_xCuO_4, and provide a new route of
understanding the complex interplay between static magnetism and
superconductivity in the stripe phase of cuprates.


title:
First Upper Limits on the Radar Cross Section of Cosmic-Ray Induced
  Extensive Air Showers

abstract:
  TARA (Telescope Array Radar) is a cosmic ray radar detection experiment
colocated with Telescope Array, the conventional surface scintillation detector
(SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. The TARA
detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting
antenna which broadcasts the radar carrier over the SD array and within the FD
field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data
since 2013 with the primary goal of observing the radar signatures of extensive
air showers (EAS). Simulations indicate that echoes are expected to be short in
duration (~10 microseconds) and exhibit rapidly changing frequency, with rates
on the order of 1 MHz/microsecond. The EAS radar cross-section (RCS) is
currently unknown although it is the subject of over 70 years of speculation. A
novel signal search technique is described in which the expected radar echo of
a particular air shower is used as a matched filter template and compared to
waveforms obtained by triggering the radar DAQ using the Telescope Array
fluorescence detector. No evidence for the scattering of radio frequency
radiation by EAS is obtained to date. We report the first quantitative RCS
upper limits using EAS that triggered the Telescope Array Fluorescence
Detector.


title:
Characteristics of Four Upward-pointing Cosmic-ray-like Events Observed
  with ANITA

abstract:
  We report on four radio-detected cosmic-ray (CR) or CR-like events observed
with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored
long-duration balloon payload. Two of the four were previously identified as
stratospheric CR air showers during the ANITA-I flight. A third stratospheric
CR was detected during the ANITA-II flight. Here we report on characteristics
these three unusual CR events, which develop nearly horizontally, 20-30~km
above the surface of the Earth. In addition, we report on a fourth steeply
upward-pointing ANITA-I CR-like radio event which has characteristics
consistent with a primary that emerged from the surface of the ice. This
suggests a possible $\tau$-lepton decay as the origin of this event, but such
an interpretation would require significant suppression of the Standard Model
${\tau}$-neutrino cross section.


title:
Highly anisotropic and two-fold symmetric superconducting gap in
  nematically ordered FeSe$_{0.93}$S$_{0.07}$

abstract:
  FeSe exhibits a novel ground state in which superconductivity coexists with a
nematic order in the absence of any long-range magnetic order. Here we report
an angle-resolved photoemission study on the superconducting gap structure in
the nematic state of FeSe$_{0.93}$S$_{0.07}$, without the complication caused
by Fermi surface reconstruction induced by magnetic order. We found that the
superconducting gap shows a pronounced 2-fold anisotropy around the elliptical
hole pocket near the Z point of the Brillouin zone, with gap minima at the
endpoints of its major axis, while no detectable gap was observed around the
zone center and zone corner. The large anisotropy and nodal gap distribution
demonstrate the substantial effects of the nematicity on the superconductivity,
and thus put strong constraints on the current theories.


title: Moment dynamics for a class of time-triggered stochastic hybrid systems

abstract:
  Stochastic Hybrid Systems (SHS) constitute an important class of mathematical
models that integrate discrete stochastic events with continuous dynamics. The
time evolution of statistical moments is generally not closed for SHS, in the
sense that the time derivative of the lower-order moments depends on
higher-order moments. Here, we identify an important class of SHS where moment
dynamics is automatically closed, and hence moments can be computed exactly by
solving a system of coupled differential equations. This class is referred to
as linear time-triggered SHS (TTSHS), where the state evolves according to a
linear dynamical system. Stochastic events occur at discrete times and the
intervals between them are independent random variables that follow a general
class of probability distributions. Moreover, whenever the event occurs, the
state of the SHS changes randomly based on a probability distribution. Our
approach relies on embedding a Markov chain based on phase-type processes to
model timing of events, and showing that the resulting system has closed moment
dynamics. Interestingly, we identify a subclass of linear TTSHS, where the
first and second-order moments depend only on the mean time interval between
events and invariant of their higher-order statistics. Finally, we discuss
applicability of our results to different application areas such as network
control systems and systems biology.


title: Noncompact RCD(0,N) spaces with linear volume growth

abstract:
  Since non-compact RCD(0, N) spaces have at least linear volume growth, we
study noncompact RCD(0, N) spaces with linear volume growth in this paper. One
of the main results is that the diameter of level sets of a Busemann function
grow at most linearly on a noncompact RCD(0, N) space satisfying the linear
volume growth condition. Another main result in this paper is a splitting
theorem at the noncompact end for a RCD(0, N) space with strongly minimal
volume growth. These results generalize some theorems on noncompact manifolds
with nonnegative Ricci curvature to non-smooth settings.


title:
Scaling transition for nonlinear random fields with long-range
  dependence

abstract:
  We obtain a complete description of anisotropic scaling limits and the
existence of scaling transition for nonlinear functions (Appell polynomials) of
stationary linear random fields on $\mathbb{Z}^2$ with moving average
coefficients decaying at possibly different rate in the horizontal and vertical
direction. The paper extends recent results on scaling transition for linear
random fields in Puplinskait\.e and Surgailis (2016), Puplinskait\.e and
Surgailis (2015).


title:
Time and direction of arrival detection and filtering for imaging in
  strongly scattering random media

abstract:
  We study detection and imaging of small reflectors in heavy clutter, using an
array of transducers that emits and receives sound waves. Heavy clutter means
that multiple scattering of the waves in the heterogeneous host medium is
strong and overwhelms the arrivals from the small reflectors. Building on the
adaptive time-frequency filter of [1], we propose a robust method for detecting
the direction of arrival of the direct echoes from the small reflectors, and
suppressing the unwanted clutter backscatter. This improves the resolution of
imaging. We illustrate the performance of the method with realistic numerical
simulations in a non-destructive testing setup.


title:
Confidence Intervals for Causal Effects with Invalid Instruments using
  Two-Stage Hard Thresholding with Voting

abstract:
  A major challenge in instrumental variables (IV) analysis is to find
instruments that are valid, or have no direct effect on the outcome and are
ignorable. Typically one is unsure whether all of the putative IVs are in fact
valid. We propose a general inference procedure in the presence of invalid IVs,
called Two-Stage Hard Thresholding (TSHT) with voting. TSHT uses two hard
thresholding steps to select strong instruments and generate candidate sets of
valid IVs. Voting takes the candidate sets and uses majority and plurality
rules to determine the true set of valid IVs. In low dimensions, if the
sufficient and necessary identification condition under invalid instruments is
met, which is more general than the so-called 50% rule or the majority rule,
our proposal (i) correctly selects valid IVs, (ii) consistently estimates the
causal effect, (iii) produces valid confidence intervals for the causal effect,
and (iv) has oracle-optimal width. In high dimensions, we establish nearly
identical results without oracle-optimality. In simulations, our proposal
outperforms traditional and recent methods in the invalid IV literature. We
also apply our method to re-analyze the causal effect of education on earnings.


title:
LIGO GW150914 and GW151226 Gravitational Wave Detection and Generalized
  Gravitation Theory (MOG)

abstract:
  The nature of gravitational waves in a generalized gravitation theory is
investigated. The linearized field equations and the metric tensor quadrupole
moment power and the decrease in radius of an inspiralling binary system of two
compact objects are derived. The generalized Kerr metric describing a spinning
black hole is determined by its mass $M$ and the spin parameter $a=cS/GM^2$.
The LIGO-Virgo collaboration data is fitted with smaller binary black hole
masses in agreement with the current electromagnetic, observed X-ray binary
upper bound for a black hole mass, $M\lesssim 10M_\odot$.


title:
Explicit Non-Malleable Extractors, Multi-Source Extractors and Almost
  Optimal Privacy Amplification Protocols

abstract:
  We make progress in the following three problems: 1. Constructing optimal
seeded non-malleable extractors; 2. Constructing optimal privacy amplification
protocols with an active adversary, for any security parameter; 3. Constructing
extractors for independent weak random sources, when the min-entropy is
extremely small (i.e., near logarithmic).
  For the first two problems, the best known non-malleable extractors by
Chattopadhyay, Goyal and Li [CGL16], and by Cohen [Coh16a,Coh16b] all require
seed length and min-entropy at least $\log^2 (1/\epsilon)$, where $\epsilon$ is
the error of the extractor. As a result, the best known explicit privacy
amplification protocols with an active adversary, which achieve 2 rounds of
communication and optimal entropy loss in [Li15c,CGL16], can only handle
security parameter up to $s=\Omega(\sqrt{k})$, where $k$ is the min-entropy of
the shared secret weak random source. For larger $s$ the best known protocol
with optimal entropy loss in [Li15c] requires $O(s/\sqrt{k})$ rounds of
communication.
  In this paper we give an explicit non-malleable extractor that only requires
seed length and min-entropy $\log^{1+o(1)} (n/\epsilon)$, which also yields a
2-round privacy amplification protocol with optimal entropy loss for security
parameter up to $s=k^{1-\alpha}$ for any constant $\alpha>0$.
  For the third problem, previously the best known extractor which supports the
smallest min-entropy due to Li [Li13a], requires min-entropy $\log^{2+\delta}
n$ and uses $O(1/\delta)$ sources, for any constant $\delta>0$. A very recent
result by Cohen and Schulman [CS16] improves this, and constructed explicit
extractors that use $O(1/\delta)$ sources for min-entropy $\log^{1+\delta} n$,
any constant $\delta>0$. In this paper we further improve their result, and
give an explicit extractor that uses $O(1)$ (an absolute constant) sources for
min-entropy $\log^{1+o(1)} n$.


title: Dynamics of a double-stranded DNA segment in a shear flow

abstract:
  We study the dynamics of a double-stranded DNA (dsDNA) segment, as a
semiflexible polymer, in a shear flow, the strength of which is customarily
expressed in terms of the dimensionless Weissenberg number Wi. Polymer chains
in shear flows are well-known to undergo tumbling motion. When the chain
lengths are much smaller than the persistence length, one expects a
(semiflexible) chain to tumble as a rigid rod. At low Wi, a polymer segment
shorter than the persistence length does indeed tumble as a rigid rod. However,
for higher Wi the chain does not tumble as a rigid rod, even if the polymer
segment is shorter than the persistence length. In particular, from time to
time the polymer segment may assume a buckled form, a phenomenon commonly known
as Euler buckling. Using a bead-spring Hamiltonian model for extensible dsDNA
fragments, we first analyze Euler buckling in terms of the oriented
deterministic state (ODS), which is obtained as the steady-state solution of
the dynamical equations by turning off the stochastic (thermal) forces at a
fixed orientation of the chain. The ODS exhibits symmetry breaking at a
critical Weissenberg number Wi$_{\text c}$, analogous to a pitchfork
bifurcation in dynamical systems. We then follow up the analysis with
simulations and demonstrate symmetry breaking in computer experiments,
characterized by a unimodal to bimodal transformation of the probability
distribution of the second Rouse mode with increasing Wi. Our simulations
reveal that shear can cause strong deformation for a chain that is shorter than
its persistence length, similar to recent experimental observations.


title:
Finite temperature fermion condensate, charge and current densities in a
  (2+1)-dimensional conical space

abstract:
  We evaluate the fermion condensate and the expectation values of the charge
and current densities for a massive fermionic field in (2+1)-dimensional
conical spacetime with a magnetic flux located at the cone apex. The
consideration is done for both irreducible representations of the Clifford
algebra. The expectation values are decomposed into the vacuum expectation
values and contributions coming from particles and antiparticles. All these
contributions are periodic functions of the magnetic flux with the period equal
to the flux quantum. Related to the non-invariance of the model under the
parity and time-reversal transformations, the fermion condensate and the charge
density have indefinite parity with respect to the change of the signs of the
magnetic flux and chemical potential. The expectation value of the radial
current density vanishes. The azimuthal current density is the same for both
the irreducible representations of the Clifford algebra. It is an odd function
of the magnetic flux and an even function of the chemical potential. The
behavior of the expectation values in various asymptotic regions of the
parameters are discussed in detail. In particular, we show that for points near
the cone apex the vacuum parts dominate. For a massless field with zero
chemical potential the fermion condensate and charge density vanish. Simple
expressions are derived for the part in the total charge induced by the planar
angle deficit and magnetic flux. Combining the results for separate irreducible
representations, we also consider the fermion condensate, charge and current
densities in parity and time-reversal symmetric models. Possible applications
to graphitic nanocones are discussed.


title:
PAC-Bayesian bounds for the Gram matrix and least squares regression
  with a random design

abstract:
  The topics dicussed in this paper take their origin inthe estimation of the
Gram matrix of a random vector from a sample made of n independent copies. They
comprise the estimation of the covariance matrix and the study of least squares
regression with a random design. We propose four types of results, based on
non-asymptotic PAC-Bayesian generalization bounds: a new robust estimator of
the Gram matrix and of the covariance matrix, new results on the empirical Gram
matrix, new robust least squares estimators and new results on the ordinary
least squares estimator, including its exact rate of convergence under
polynomial moment assumptions.


title: Restricted rational Cherednik algebras

abstract:
  We give an overview of the representation theory of restricted rational
Cherednik algebras. These are certain finite-dimensional quotients of rational
Cherednik algebras at t=0. Their representation theory is connected to the
geometry of the Calogero-Moser space, and there is a lot of evidence that they
contain certain information about Hecke algebras even though the precise
connection is so far unclear. We outline the basic theory along with some open
problems and conjectures, and give explicit results in the cyclic and dihedral
cases.


title:
Convergence of an approximation for rotationally symmetric two-phase
  lipid bilayer membranes

abstract:
  We consider a diffuse interface approximation for the lipid phases of
rotationally symmetric two-phase bilayer membranes and rigorously derive its
$\Gamma$-limit. In particular, we prove that limit vesicles are $C^1$ across
interfaces, which justifies a regularity assumption that is widely made in
formal asymptotic and numerical studies. Moreover, a limit membrane may consist
of several topological spheres, which are connected at the axis of revolution
and resemble complete buds of the vesicle.


title:
The merging galaxy cluster A520 --- a broken-up cool core, a dark
  subcluster, and an X-ray channel

abstract:
  We present results from a deep Chandra X-ray observation of a merging galaxy
cluster A520. A high-resolution gas temperature map, after the subtraction of
the cluster-scale emission, reveals a long trail of dense, cool clumps ---
apparently the fragments of a cool core that has been completely stripped from
the infalling subcluster by ram pressure. In this scenario, we can assume that
the clumps are still connected by the magnetic field lines. The observed
temperature variations imply that thermal conductivity is suppressed by a
factor >100 across the presumed direction of the magnetic field (as found in
other clusters), and is also suppressed -along- the field lines by a factor of
several. Two massive clumps in the periphery of A520, visible in the weak
lensing mass map and the X-ray image, have apparently been completely stripped
of gas during the merger, but then re-accreted the surrounding high-entropy gas
upon exit from the cluster. An X-ray hydrostatic mass estimate for one of the
clumps (that has simple geometry) agrees with the lensing mass. Its current gas
mass to total mass ratio is very low, 1.5-3%, which makes it a "dark
subcluster". We also found a curious low X-ray brightness channel (likely a
low-density sheet in projection) going across the cluster along the direction
of an apparent secondary merger. The channel may be caused by plasma depletion
in a region of an amplified magnetic field (with plasma $\beta\sim 10-20$). The
shock in A520 will be studied in a separate paper.


title: Divisor Goldbach Conjecture and its Partition Number

abstract:
  Based on the Goldbach conjecture and arithmetic fundamental theorem, the
Goldbach conjecture was extended to more general situations, i.e., any positive
integer can be written as summation of some specific prime numbers, which
depends on the divisible factor of this integer, that is:
  For any positive integer $n~(n>2)$, if there exists an integer $m$, such that
$m|n~( 1 < m < n )$, then $n=\sum_{i=1}^m p_i $, where $ p_i~(i=1,2 ,3...m)$ is
prime number.
  In addition, for more prime summands, the combinatorial counting is also
discussed. For some special cases, some brief proofs are given. By the use of
computer, the preliminary numerical verification was given, there is no an
anti-example to be found.


title:
The clustering of massive Primordial Black Holes as Dark Matter:
  measuring their mass distribution with Advanced LIGO

abstract:
  The recent detection by Advanced LIGO of gravitational waves (GW) from the
merging of a binary black hole system sets new limits on the merging rates of
massive primordial black holes (PBH) that could be a significant fraction or
even the totality of the dark matter in the Universe. aLIGO opens the way to
the determination of the distribution and clustering of such massive PBH. If
PBH clusters have a similar density to the one observed in ultra-faint dwarf
galaxies, we find merging rates comparable to aLIGO expectations. Massive PBH
dark matter predicts the existence of thousands of those dwarf galaxies where
star formation is unlikely because of gas accretion onto PBH, which would
possibly provide a solution to the missing satellite and too-big-to-fail
problems. Finally, we study the possibility of using aLIGO and future GW
antennas to measure the abundance and mass distribution of PBH in the range [5
- 200] Msun to 10\% accuracy.


title: Convergence of Ricci flows with bounded scalar curvature

abstract:
  In this paper we prove convergence and compactness results for Ricci flows
with bounded scalar curvature and entropy. More specifically, we show that
Ricci flows with bounded scalar curvature converge smoothly away from a
singular set of codimension $\geq 4$. We also establish a general form of the
Hamilton-Tian Conjecture, which is even true in the Riemannian case.
  These results are based on a compactness theorem for Ricci flows with bounded
scalar curvature, which states that any sequence of such Ricci flows converges,
after passing to a subsequence, to a metric space that is smooth away from a
set of codimension $\geq 4$. In the course of the proof, we will also establish
$L^{p < 2}$-curvature bounds on time-slices of such flows.


title: Structure theory of singular spaces

abstract:
  In this paper we generalize the theory of Cheeger, Colding and Naber to
certain singular spaces that arise as limits of sequences of Riemannian
manifolds. This theory will have applications in the analysis of Ricci flows of
bounded curvature, which we will describe in a subsequent paper.


title: The sharp threshold for the Duarte model

abstract:
  The class of critical bootstrap percolation models in two dimensions was
recently introduced by Bollob\'as, Smith and Uzzell, and the critical threshold
for percolation was determined up to a constant factor for all such models by
the authors of this paper. Here we develop and refine the techniques introduced
in that paper in order to determine a sharp threshold for the Duarte model.
This resolves a question of Mountford from 1995, and is the first result of its
type for a model with drift.


title:
A Universal Coding Scheme for Remote Generation of Continuous Random
  Variables

abstract:
  We consider a setup in which Alice selects a pdf $f$ from a set of prescribed
pdfs $\mathscr{P}$ and sends a prefix-free codeword $W$ to Bob in order to
allow him to generate a single instance of the random variable $X\sim f$. We
describe a universal coding scheme for this setup and establish an upper bound
on the expected codeword length when the pdf $f$ is bounded, orthogonally
concave (which includes quasiconcave pdf), and has a finite first absolute
moment. A dyadic decomposition scheme is used to express the pdf as a mixture
of uniform pdfs over hypercubes. Alice randomly selects a hypercube according
to its weight, encodes its position and size into $W$, and sends it to Bob who
generates $X$ uniformly over the hypercube. Compared to previous results on
channel simulation, our coding scheme applies to any continuous distribution
and does not require two-way communication or shared randomness. We apply our
coding scheme to classical simulation of quantum entanglement and obtain a
better bound on the average codeword length than previously known.


title:
Constraints on decaying early modified gravity from cosmological
  observations

abstract:
  Most of the information on our cosmos stems from either late-time
observations or the imprint of early-time inhomogeneities on the cosmic
microwave background. We explore to what extent early modifications of gravity,
which become significant after recombination but then decay towards the
present, can be constrained by current cosmological observations. For the
evolution of the gravitational modification, we adopt the decaying mode of a
hybrid-metric Palatini $f(\mathcal{R})$ gravity model which is designed to
reproduce the standard cosmological background expansion history and due to the
decay of the modification is naturally compatible with Solar-System tests. We
embed the model in the effective field theory description of Horndeski
scalar-tensor gravity with an early-time decoupling of the gravitational
modification. Since the quasistatic approximation for the perturbations in the
model breaks down at high redshifts, where modifications remain relevant, we
introduce a computationally efficient correction to describe the evolution of
the scalar field fluctuation in this regime. We compare the decaying early-time
modification against geometric probes and recent Planck measurements and find
no evidence for such effects in the observations. Current data constrains the
scalar field value at $|f_{\mathcal{R}}(z=z_{\rm on})| \lesssim 10^{-2}$ for
modifications introduced at redshifts $z_{\rm on}\sim(500-1000)$ with
present-day value $|f_{\mathcal{R}0}|\lesssim10^{-8}$. Finally, we comment on
constraints that will be achievable with future 21~cm surveys and gravitational
wave experiments.


title: Bitcoin Mining Decentralization via Cost Analysis

abstract:
  Bitcoin mining presents a significant economic incentive for efficient
hashing and broadcast of data, both parameters stemming from the Proofs of Work
used to advance the network. This incentive has led to the development of
Bitcoin specific application specific integrated circuits and centralized
mining pools, undermining the decentralized motivations behind Bitcoin's
design. In addition, the imminent block reward halving threatens the
profitability of mining at any scale. Some work has been done in formal models
for miner profitability, but existing models do not account for conditions such
as the pricing of off-peak power and diverse investment strategies regarding
sunken costs. There is also a lack of formal study of how the profit model
changes as mining scales from the individual to the industrial level. Given the
lack of analysis of these conditions, there are alternative models for
profitable or net zero mining that operate at smaller, and therefore more
desirable, scale.


title: Commutative deductive systems of pseudo BCK-algebras

abstract:
  In this paper we generalize the axiom systems given by M. Pa{\l}asi\'nski, B.
Wo\'zniakowska and by W.H. Cornish for commutative BCK-algebras to the case of
commutative pseudo BCK-algebras. A characterization of commutative pseudo
BCK-algebras is also given. We define the commutative deductive systems of
pseudo BCK-algebras and we generalize some results proved by Yisheng Huang for
commutative ideals of BCI-algebras to the case of commutative deductive systems
of pseudo BCK-algebras. We prove that a pseudo BCK-algebra $A$ is commutative
if and only if all the deductive systems of $A$ are commutative. We show that a
normal deductive system $H$ of a pseudo BCK-algebra $A$ is commutative if and
only if $A/H$ is a commutative pseudo BCK-algebra. We introduce the notions of
state operators and state-morphism operators on pseudo BCK-algebras, and we
apply these results on commutative deductive systems to investigate the
properties of these operators.


title:
Variational Study of $\lambda$- and $N$-Atomic Configurations
  Interacting with an Electromagnetic Field of $2$ Modes

abstract:
  A study of the $\lambda$- and $N$-atomic configurations under dipolar
interaction with $2$ modes of electromagnetic radiation is presented. The
corresponding quantum phase diagrams are obtained by means of a variational
procedure. Both configurations exhibit normal and collective (super-radiant)
regimes. While the latter in the $\lambda$-configuration divides itself into
$2$ subregions, corresponding to each of the modes, that in the
$N$-configuration may be divided into $2$ or $3$ subregions depending on
whether the field modes divide the atomic system into $2$ separate subsystems
or not.
  Our variational procedure compares well with the exact quantum solution. The
properties of the relevant field and matter observables are obtained.


title: An easy upper bound for Ramsey numbers

abstract:
  It is observed that the conjugacy growth series of the infinite finitary
symmetric group with respect to the generating set of transpositions is the
generating series of the partition function. Other conjugacy growth series are
computed, for other generating sets, for restricted permutational wreath
products of finite groups by the finitary symmetric group, and for alternating
groups. Similar methods are used to compute usual growth polynomials and
conjugacy growth polynomials for finite symmetric groups and alternating
groups, with respect to various generating sets of transpositions. Computations
suggest a class of finite graphs, that we call partition-complete, which
generalizes the class of semi-hamiltonian graphs, and which is of independent
interest. Numerical evidences indicate that the coefficients of a series
related to the finitary alternating group seem to satisfy congruence relations
reminiscent of Ramanujan's congruences for the partition function.


title:
Three-Dimensional Multi-Tethered Satellite Formation with the Elements
  Moving Along Lissajous Curves

abstract:
  This note presents a novel approach to maintain three-dimensional
multi-tethered satellite formation in space. For a formation consisting of a
main body connected by tethers with several deputy satellites (the so-called
"hub-and-spoke" configuration) we demonstrate that under proper choice of the
system's parameters the deputy satellites can move along Lissajous curves in
the plane normal to the local vertical with all tethers stretched, the total
force due to the tension forces acting on the main satellite is balanced in a
way allowing it to be in relative equilibrium strictly below or strictly above
the system's center of mass. We analyze relations between the system's
essential parameters and obtain conditions under which the proposed motion does
take place. We also study analytically the motion stability for different
configurations and whether the deputy satellites can collide or the tethers can
entangle. Our theoretical findings are corroborated and validated by numerical
experiments.


title:
On SYM theory and all order Bulk Singularity Structures of BPS Strings
  in type II theory

abstract:
  The complete forms of the S-matrix elements of a transverse scalar field, two
world volume gauge fields, and a Potential $C_{n-1}$ Ramond-Ramond (RR) form
field are investigated. In order to find an infinite number of $t,s,
(t+s+u)$-channel bulk singularity structures of this particular mixed
open-closed amplitude, we employ all the conformal field theory techniques to
$<V_{C^{-2}}V_{\phi ^{0}} V_{A^{0}} V_{A^{0}}>$, exploring all the entire
correlation functions and all order $\alpha'$ contact interactions to these
supersymmetric Yang-Mills (SYM) couplings. Singularity and contact term
comparisons with the other symmetric analysis, $<V_{C^{-1}}V_{\phi ^{0}}
V_{A^{-1}} V_{A^{0}}>$ and $<V_{C^{-1}}V_{\phi ^{-1}} V_{A^{0}} V_{A^{0}}>$ are
also carried out in detail. Various couplings from pull-Back of branes, Myers
terms and several generalized Bianchi identities should be taken into account
to be able to reconstruct all order $\alpha'$ bulk singularities of type IIB
(IIA) superstring theory. Finally, we make a comment on how to derive without
any ambiguity all order $\alpha'$ contact terms of this S-matrix which carry
momentum of RR in transverse directions.


title:
Numerical study of fermion and boson models with infinite-range random
  interactions

abstract:
  We present numerical studies of fermion and boson models with random
all-to-all interactions (the SYK models). The high temperature expansion and
exact diagonalization of the $N$-site fermion model are used to compute the
entropy density: our results are consistent with the numerical solution of
$N=\infty$ saddle point equations, and the presence of a non-zero entropy
density in the limit of vanishing temperature. The exact diagonalization
results for the fermion Green's function also appear to converge well to the
$N=\infty$ solution. For the hard-core boson model, the exact diagonalization
study indicates spin glass order. Some results on the entanglement entropy and
the out-of-time-order correlators are also presented.


title:
Necessary and sufficient conditions for multipartite Bell violations
  with only one trusted device

abstract:
  We study multipartite Bell nonlocality in a framework native of multipartite
Einstein-Podolsky-Rosen (EPR) steering scenarios with a single trusted
measurement device. We derive a closed-form necessary and sufficient criterion
for systems composed of a qubit and N-1 untrusted black-box measurement devices
to violate -- under general dichotomic measurements on the qubit -- a generic
Bell inequality from a broad family of linear inequalities with arbitrarily
many outputs for the N-1 untrusted devices and inputs for all N parties. The
optimal quantum measurements for maximal violation are also obtained. For two
users, and two inputs and two outputs per user, our criterion becomes necessary
and sufficient for Bell nonlocality. Furthermore, in that setting, its form
generalizes recently obtained steering inequalities, which allows us to provide
useful feedback from nonlocality to the detection of steering. Our findings
constitute a practical tool for the study of the interplay between EPR steering
and Bell nonlocality, with potential applications in multipartite information
processing.


title:
LHC constraints and prospects for $S_1$ scalar leptoquark explaining the
  $\bar B \to D^{(*)} \tau \bar\nu$ anomaly

abstract:
  Recently, deviations in flavor observables of B -> D(*) tau nu have been
shown between the predictions in the Standard Model and the experimental
results reported by BaBar, Belle, and LHCb collaborations. One of the solutions
to this anomaly is obtained in a class of leptoquark model with a scalar
leptoquark boson S_1, which is a SU(3)_c triplet and SU(2)_L singlet particle
with -1/3 hypercharge interacting with a quark-lepton pair. With well-adjusted
couplings, this model can explain the anomaly and be compatible with all flavor
constraints. In such a case, the S_1 boson can be pair-produced at CERN's Large
Hadron Collider (LHC) and subsequently decay as S_1 -> t tau, b nu, c tau. This
paper explores the current 8 and 13 TeV constraints, as well as the detailed
prospects at 14 TeV, of this flavor-motivated S_1 model. From the current
available 8 and 13 TeV LHC searches, we obtain constraints on the S_1 boson
mass for M_{S_1} < 400 GeV - 640 GeV depending on values of the leptoquark
couplings to fermions. Then we study future prospects for this scenario at the
14 TeV LHC using detailed cut analyses and evaluate exclusion/discovery
potentials for the flavor-motivated S_1 leptoquark model from searches for the
(b nu) (b nu) and (c tau) (c tau) final states. In the latter case, we consider
several scenarios for the identification of charm jets. As a result, we find
that the S_1 leptoquark origin of the B -> D(*) tau nu anomaly can be probed
with mass less than around 600/800 GeV at the 14 TeV LHC with 300/3000 fb^-1 of
accumulated data.


title:
On the Feasibility of Characterizing Free-floating Planets with Current
  and Future Space-based Microlensing Surveys

abstract:
  Simultaneous space- and ground-based microlensing surveys, such as K2's
Campaign 9 (K2C9) and $WFIRST$, facilitate measuring the masses and distances
of free-floating planet (FFP) candidates. FFPs are identified as single-lens
events with a short timescale, of-order 1 day. Measuring the mass of the
lensing object requires determining the finite size of the source star $\rho$,
as well as the microlens parallax $\pi_{\rm E}$. A planet that is bound to but
widely separated from a host star can produce a light curve similar to that of
an FFP. This tension can be resolved with high-resolution imaging of the
microlensing target to search for the lens flux $F_l$ from a possible host
star. Here we investigate the accessible parameter space for each of these
components --- $\pi_{\rm E}$, $\rho$, and $F_l$ --- considering different
satellites for a range of FFP masses, Galactic distances, and source star
properties. We find that at the beginning of K2C9, when its projected
separation from the Earth (as viewed from the center of its survey field) is
$\lesssim$0.2 AU, it will be able to measure $\pi_{\rm E}$ for Jupiter-mass FFP
candidates at distances larger than $\sim$2 kpc and to Earth-mass lenses at
$\sim$8 kpc. At the end of its campaign, when $D_\perp = 0.81$ AU, it is
sensitive to planetary-mass lenses for distances $\gtrsim$3.5 kpc, and even
then only to those with mass $\gtrsim$M$_{\rm Jup}$. From lens flux constraints
we find that it will be possible to exclude all stellar-mass host stars (down
to the deuterium-burning limit) for events within $\sim$2 kpc. Together these
indicate that the ability to characterize FFPs detected during K2C9 is
optimized for events occurring toward the beginning of the campaign. $WFIRST$,
on the other hand, will be able to detect and characterize FFPs with masses at
least as low as super-Earths throughout the Galaxy during its entire
microlensing survey.


title: A Holographic Entanglement Entropy Conjecture for General Spacetimes

abstract:
  We present a natural generalization of holographic entanglement entropy
proposals beyond the scope of AdS/CFT by anchoring extremal surfaces to
holographic screens. Holographic screens are a natural extension of the AdS
boundary to arbitrary spacetimes and are preferred codimension 1 surfaces from
the viewpoint of the covariant entropy bound. A broad class of screens have a
unique preferred foliation into codimension 2 surfaces called leaves. Our
proposal is to find the areas of extremal surfaces achored to the boundaries of
regions in leaves. We show that the properties of holographic screens are
sufficient to prove, under generic conditions, that extremal surfaces anchored
in this way always lie within a causal region associated with a given leaf.
Within this causal region, a maximin construction similar to that of Wall
proves that our proposed quantity satisfies standard properties of entanglement
entropy like strong subadditivity. We conjecture that our prescription computes
entanglement entropies in quantum states that holographically define arbitrary
spacetimes, including those in a cosmological setting with no obvious boundary
on which to anchor extremal surfaces.


title: The 750 GeV diphoton resonance as an sgoldstino: a reappraisal

abstract:
  Among the various explanations of the possible 750 GeV diphoton resonance,
the possibility of it being an sgoldstino is an attractive one, as it is
related to the spontaneous breaking of global supersymmetry. We discuss this
possibility in this paper and point out the various theoretical issues
associated with it. In particular, we indicate the difficulties of this
explanation in realistic models of gauge mediated supersymmetry breaking.


title: Unitarity methods for Mellin moments of Drell-Yan cross sections

abstract:
  We develop a method for computing Mellin moments of single inclusive cross
sections such as Drell-Yan production directly from forward scattering
diagrams, by invoking unitarity in the form of cutting equations. We provide a
diagram-independent prescription for eliminating contributions from unwanted
cuts at the level of an expansion in the reciprocal omega=1/z variable. The
modified sum over powers of omega produces the result from physical cuts only,
with the nth coefficient precisely equal to the nth Mellin moment of the cross
section. We demonstrate and validate our method for representative one- and
two-loop diagrams.


title: Cosmological $N$-body simulations with suppressed variance

abstract:
  We present and test a method that dramatically reduces variance arising from
the sparse sampling of wavemodes in cosmological simulations. The method uses
two simulations which are fixed (the initial Fourier mode amplitudes are fixed
to the ensemble average power spectrum) and paired (with initial modes exactly
out of phase). We measure the power spectrum, monopole and quadrupole
redshift-space correlation functions, halo mass function and reduced bispectrum
at $z=1$. By these measures, predictions from a fixed pair can be as precise on
non-linear scales as an average over 50 traditional simulations. The fixing
procedure introduces a non-Gaussian correction to the initial conditions; we
give an analytic argument showing why the simulations are still able to predict
the mean properties of the Gaussian ensemble. We anticipate that the method
will drive down the computational time requirements for accurate large-scale
explorations of galaxy bias and clustering statistics, enabling more precise
comparisons with theoretical models, and facilitating the use of numerical
simulations in cosmological data interpretation.


title:
Constraining Globular Cluster Age Uncertainties Using the IR
  Color-Magnitude Diagram

abstract:
  Globular Clusters (GCs) in the Milky Way are the primary laboratories for
establishing the ages of the oldest stellar populations and for measuring the
color-magnitude relation of stars. In infrared (IR) color-magnitude diagrams
(CMDs), the stellar main sequence (MS) exhibits a "kink", due to opacity
effects in M dwarfs, such that lower mass and cooler dwarfs become bluer in the
IR color baseline. This diagnostic offers a new opportunity to model GC CMDs
and to reduce uncertainties on cluster properties (e.g., their derived ages).
In this context, we analyzed Hubble Space Telescope Wide Field Camera 3 IR
archival observations of four GCs - 47Tuc, M4, NGC2808, and NGC6752 - for which
the data are deep enough to fully sample the low-mass MS, reaching at least ~ 2
mag below the "kink". We derived the fiducial lines for each cluster and
compared them with a grid of isochrones over a large range of parameter space,
allowing age, metallicity, distance, and reddening to vary within reasonable
selected ranges. The derived ages for the four clusters are respectively 11.6,
11.5, 11.2, and 12.1 Gyr and their random uncertainties are \sigma ~ 0.7 - 1.1
Gyr. Our results suggest that the near-IR MS "kink", combined with the MS
turn-off, provides a valuable tool to measure GC ages and offers a promising
opportunity to push the absolute age of GCs to sub-Gyr accuracy with the next
generation IR telescopes such as the James Webb Space Telescope and the
Wide-Field Infrared Survey Telescope.


title: X-ray analysis of the galaxy group UGC03957 beyond R200 with Suzaku

abstract:
  We investigated the gas properties of the galaxy group UGC03957 up to
$1.4R_{200} \approx 1.4$Mpc in four azimuthal directions with the Suzaku
satellit and performed a spectral analysis of five Suzaku observations of
UGC03957 with 138ks good exposure time in total and five Chandra snapshot
observations for point source detection. We found a temperature drop of a
factor of ${\sim} 3$ from the center to the outskirts that is consistent with
previous results for galaxy clusters. The metal abundance profile shows a flat
behavior towards large radii, which is a hint for galactic winds as the primary
ICM enrichment process. The entropy profile is consistent with numerical
simulations after applying a gas mass fraction correction. Previous analyses
for clusters and groups often showed an entropy flattening or even a drop
around ${\sim} R_{200}$, which can be an indication of clumping or
non-equilibrium states in the outskirts. Such entropy behavior is absent in
UGC03957. The gas mass fraction is well below the cosmic mean but rises above
this value beyond $R_{200}$, which could be a hint for deviations from
hydrostatic equilibrium at these large radii. We determined the relative number
of different supernovae types and found that the abundance pattern can be
described by a relative contribution of 80% - 100% of core-collapse supernovae.
This result is in agreement with previous measurements for galaxy groups.


title: Glue Spin of the Proton

abstract:
  We report the progress on the lattice QCD calculation of the glue spin
contribution to proton spin. This calculation is carried out with valence
overlap fermion on 2+1 flavor DWF gauge configurations at two lattice spacings
with the momentum of the frame in the kinematic range $0\leq p^2 \leq 2$
GeV$^2$. A mild frame dependence is observed. The matching and mixing with
large-momentum effective field theory are in progress. The unrenormalized
result at $p^2=4$ GeV$^2$ with $O(a^2)$ correction gives $S_G$ = 0.13(3).


title:
Impact of the first-forbidden $\beta$ decay on the production of $A \sim
  195$ r-process peak

abstract:
  We investigated the effects of first-forbidden transitions in $\beta$ decays
on the production of the r-process $A \sim 195$ peak. The theoretical
calculated $\beta$-decay rates with $\beta$-delayed neutron emission were
examined using several astrophysical conditions. As the first-borbidden decay
is dominant in $N \sim 126$ neutron-rich nuclei, their inclusion shortens
$\beta$-decay lifetimes and shifts the abundance peak towards higher masses.
Additionally, the inclusion of the $\beta$-delayed neutron emission results in
a wider abundance peak, and smoothens the mass distribution by removing the
odd-even mass staggering. The effects are commonly seen in the results of all
adopted astrophysical models. Nevertheless there are quantitative differences,
indicating that remaining uncertainty in the determination of half-lives for
$N=126$ nuclei is still significant in order to determine the production of the
r-process peak.


title: Quantum Holonomies from Spectral Networks and Framed BPS States

abstract:
  We propose a method for determining the spins of BPS states supported on line
defects in 4d $\mathcal{N}=2$ theories of class S. Via the 2d-4d
correspondence, this translates to the construction of quantum holonomies on a
punctured Riemann surface $\mathcal{C}$. Our approach combines the technology
of spectral networks, which decomposes flat $GL(K,\mathbb{C})$-connections on
$\mathcal{C}$ in terms of flat abelian connections on a $K$-fold cover of
$\mathcal{C}$, and the skein algebra in the 3-manifold $\mathcal{C}\times
[0,1]$, which expresses the representation theory of the quantum group
$U_q(gl_K)$. With any path on $\mathcal{C}$, the quantum holonomy associates a
positive Laurent polynomial in the quantized Fock-Goncharov coordinates of
higher Teichm\"uller space. This confirms various positivity conjectures in
physics and mathematics.


title: High-Density Effects in X-ray Reflection Models from Accretion Disks

abstract:
  Current models of the spectrum of X-rays reflected from accretion disks
around black holes and other compact objects are commonly calculated assuming
that the density of the disk atmosphere is constant within several Thomson
depths from the irradiated surface. An important simplifying assumption of
these models is that the ionization structure of the gas is completely
specified by a single, fixed value of the ionization parameter $\xi$, which is
the ratio of the incident flux to the gas density. The density is typically
fixed at $n_e=10^{15}$ cm$^{-3}$. Motivated by observations, we consider higher
densities in the calculation of the reflected spectrum. We show by computing
model spectra for $n_e \gtrsim 10^{17}$ cm$^{-3}$ that high-density effects
significantly modify reflection spectra. The main effect is to boost the
thermal continuum at energies $\lesssim 2$ keV. We discuss the implications of
these results for interpreting observations of both AGN and black hole
binaries. We also discuss the limitations of our models imposed by the quality
of the atomic data currently available.


title: Maximum Entropy Production and Non-Gaussian Climate Variability

abstract:
  Earth's atmosphere is in a state far from thermodynamic equilibrium. For
example, the large scale equator-to-pole temperature gradient is maintained by
tropical heating, polar cooling, and a midlatitude meridional eddy heat flux
predominantly driven by baroclinically unstable weather systems. Based on basic
thermodynamic principles, it can be shown that the meridional heat flux, in
combination with the meridional temperature gradient, acts to maximize entropy
production of the atmosphere. In fact, maximum entropy production (MEP) has
been successfully used to explain the observed mean state of the atmosphere and
other components of the climate system. However, one important feature of the
large scale atmospheric circulation is its often non-Gaussian variability about
the mean. This paper presents theoretical and observational evidence that some
processes in the midlatitude atmosphere are significantly non-Gaussian to
maximize entropy production. First, after introducing the basic theory, it is
shown that the skewness of sea surface winds, damped by nonlinear surface drag,
are consistent with the MEP principle. Then it is pointed out that the observed
wavenumber spectrum of long planetary waves in the midlatitudes can be roughly
explained by maximizing the meridional eddy heat flux (and related entropy
production) of unstable baroclinic Eady waves. Finally observational evidence
is presented that the meridional eddy heat flux is increased by non-Gaussian
variability in meridional wind and temperatures anomalies.


title: Optimally controlling the human connectome: the role of network topology

abstract:
  To meet ongoing cognitive demands, the human brain must seamlessly transition
from one brain state to another, in the process drawing on different cognitive
systems. How does the brain's network of anatomical connections help facilitate
such transitions? Which features of this network contribute to making one
transition easy and another transition difficult? Here, we address these
questions using network control theory. We calculate the optimal input signals
to drive the brain to and from states dominated by different cognitive systems.
The input signals allow us to assess the contributions made by different brain
regions. We show that such contributions, which we measure as energy, are
correlated with regions' weighted degrees. We also show that the network
communicability, a measure of direct and indirect connectedness between brain
regions, predicts the extent to which brain regions compensate when input to
another region is suppressed. Finally, we identify optimal states in which the
brain should start (and finish) in order to minimize transition energy. We show
that the optimal target states display high activity in hub regions,
implicating the brain's rich club. Furthermore, when rich club organization is
destroyed, the energy cost associated with state transitions increases
significantly, demonstrating that it is the richness of brain regions that
makes them ideal targets.


title: From maximal to minimal supersymmetry in string loop amplitudes

abstract:
  We calculate one-loop string amplitudes of open and closed strings with
N=1,2,4 supersymmetry in four and six dimensions, by compactification on
Calabi-Yau and K3 orbifolds. In particular, we develop a method to combine
contributions from all spin structures for an arbitrary number of legs at
minimal supersymmetry. Each amplitude is cast into a compact form by
reorganizing the kinematic building blocks and casting the worldsheet integrals
in a basis. Infrared regularization plays an important role to exhibit the
expected factorization limits. We comment on implications for the one-loop
string effective action.


title: On a isoperimetric-isodiametric inequality

abstract:
  The Euclidean mixed isoperimetric-isodiametric inequality states that the
round ball maximizes the volume under constraint on the product between
boundary area and radius. The goal of the paper is to investigate such mixed
isoperimetric-isodiametric inequalities in Riemannian manifolds. We first prove
that the same inequality, with the sharp Euclidean constants, holds on
Cartan-Hadamard spaces as well as on minimal submanifolds of $\mathbb{R}^n$.
The equality cases are also studied and completely characterized; in
particular, the latter gives a new link with free boundary minimal submanifolds
in a Euclidean ball. We also consider the case of manifolds with non-negative
Ricci curvature and prove a new comparison result stating that metric balls in
the manifold have product of boundary area and radius bounded by the Euclidean
counterpart and equality holds if and only if the ball is actually Euclidean.
We then pass to consider the problem of the existence and the regularity of
optimal shapes (i.e. regions minimizing the product of boundary area and radius
under the constraint of having fixed enclosed volume), called here
isoperimetric-isodiametric regions. We give examples of spaces where there
exists no isoperimetric-isodiametric region and we prove that on the other hand
on compact spaces and on $C^0$-locally-asymptotic Euclidean manifolds with
non-negative Ricci curvature there exists an isoperimetric-isodiametric region
for every positive volume (this last class of spaces includes a large family of
metrics playing a key role in general relativity and Ricci flow: the so called
Hawking gravitational instantons and the Bryant-type Ricci solitons). We
finally prove that the boundary of the isoperimetric-isodiametric regions
satisfy the optimal $C^{1,1}$ regularity outside of a closed subset of
Hausdorff co-dimension $8$.


title:
Four-dimentional Gradient Shrinking Solitons with Positive Isotropic
  Curvature

abstract:
  We show that a four-dimensional complete gradient shrinking Ricci soliton
with positive isotropic curvature is either a quotient of S^4 or a quotient of
S^3 cross R. This gives a clean classification result removing the earlier
additional assumptions in [13] by Wallach and the second author.


title:
Thresholded Multivariate Principal Component Analysis for Multi-channel
  Profile Monitoring

abstract:
  Monitoring multichannel profiles has important applications in manufacturing
systems improvement, but it is non-trivial to develop efficient statistical
methods due to two main challenges. First, profiles are high-dimensional
functional data with intrinsic inner- and inter-channel correlations, and one
needs to develop a dimension reduction method that can deal with such intricate
correlations for the purpose of effective monitoring. The second, and probably
more fundamental, challenge is that the functional structure of multi-channel
profiles might change over time, and thus the dimension reduction method should
be able to automatically take into account the potential unknown change. To
tackle these two challenges, we propose a novel thresholded multivariate
principal component analysis (PCA) method for multi-channel profile monitoring.
Our proposed method consists of two steps of dimension reduction: It first
applies the functional PCA to extract a reasonable large number of features
under the normal operational (in-control) state, and then use the
soft-thresholding techniques to further select significant features capturing
profile information in the out-of-control state. The choice of tuning parameter
for soft-thresholding is provided based on asymptotic analysis, and extensive
simulation studies are conducted to illustrate the efficacy of our proposed
thresholded PCA methodology.


title:
Transferable tight binding model for strained group IV and III-V
  materials and heterostructures

abstract:
  It is critical to capture the effect due to strain and material interface for
device level transistor modeling. We introduced a transferable sp3d5s* tight
binding model with nearest neighbor interactions for arbitrarily strained group
IV and III-V materials. The tight binding model is parameterized with respect
to Hybrid functional(HSE06) calculations for varieties of strained systems. The
tight binding calculations of ultra small superlattices formed by group IV and
group III-V materials show good agreement with the corresponding HSE06
calculations. The application of tight binding model to superlattices
demonstrates that transferable tight binding model with nearest neighbor
interactions can be obtained for group IV and III-V materials.


title:
LiNbO3 ridge waveguides realized by precision dicing on silicon for high
  efficiency second harmonic generation

abstract:
  Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on
silicon substrates. Components are carved with only use of a precision dicing
machine without need for grinding or polishing steps. They show efficient
second harmonic generation at telecommunication wavelengths with normalized
conversion reaching 204%/W in a 15 mm long device. Influence of geometrical non
uniformities of waveguides due to fabrication process is asserted. Components
characteristics are studied notably their robustness and tunability versus
temperature.


title:
Underwater acoustic wave generation by filamentation of terawatt
  ultrashort laser pulses

abstract:
  Acoustic signals generated by filamentation of ultrashort TW laser pulses in
water are characterized experimentally. Measurements reveal a strong influence
of input pulse duration on the shape and intensity of the acoustic wave.
Numerical simulations of the laser pulse nonlinear propagation and the
subsequent water hydrodynamics and acoustic wave generation show that the
strong acoustic emission is related to the mechanism of superfilamention in
water. The elongated shape of the plasma volume where energy is deposited
drives the far-field profile of the acoustic signal, which takes the form of a
radially directed pressure wave with a single oscillation and a very broad
spectrum.


title: Mbps Experimental Acoustic Through-Tissue Communications: MEAT-COMMS

abstract:
  Methods for digital, phase-coherent acoustic communication date to at least
the work of Stojanjovic, et al [20], and the added robustness afforded by
improved phase tracking and compensation of Johnson, et al [21]. This work
explores the use of such methods for communications through tissue for
potential biomedical applications, using the tremendous bandwidth available in
commercial medical ultrasound transducers. While long-range ocean acoustic
experiments have been at rates of under 100kbps, typically on the order of 1-
10kbps, data rates in excess of 120Mb/s have been achieved over cm-scale
distances in ultrasonic testbeds [19]. This paper describes experimental
transmission of digital communication signals through samples of real pork
tissue and beef liver, achieving data rates of 20-30Mbps, demonstrating the
possibility of real-time video-rate data transmission through tissue for inbody
ultrasonic communications with implanted medical devices.


title: Search for Optical Pulsations in PSR J0337+1715

abstract:
  We report on a search for optical pulsations from PSR J0337+1715 at its
observed radio pulse period. PSR J0337+1715 is a millisecond pulsar (2.7 ms
spin period) in a triple hierarchical system with two white dwarfs, and has a
known optical counterpart with g-band magnitude 18. The observations were done
with the Array Camera for Optical to Near-IR Spectrophotometry (ARCONS) at the
200" Hale telescope at Palomar Observatory. No significant pulsations were
found in the range 4000-11000 angstroms, and we can limit pulsed emission in
g-band to be fainter than 25 mag.


title: Trace Identities for the Topological Vertex

abstract:
  The topological vertex is a universal series which can be regarded as an
object in combinatorics, representation theory, geometry, or physics. It
encodes the combinatorics of 3D partitions, the action of vertex operators on
Fock space, the Donaldson-Thomas theory of toric Calabi-Yau threefolds, or the
open string partition function of $\mathbb{C}^3$.
  We prove several identities in which a sum over terms involving the
topological vertex is expressed as a closed formula, often a product of simple
terms, closely related to Fourier expansions of Jacobi forms. We use purely
combinatorial and representation theoretic methods to prove our formulas, but
we discuss applications to the Donaldson-Thomas invariants of elliptically
fibered Calabi-Yau threefolds at the end of the paper.


title:
On 3d Bulk Geometry of Virasoro Coadjoint Orbits: Orbit invariant
  charges and Virasoro hair on locally AdS3 geometries

abstract:
  Expanding upon [arXiv:1404.4472, 1511.06079], we provide further detailed
analysis of Ba\~nados geometries, the most general solutions to the AdS3
Einstein gravity with Brown-Henneaux boundary conditions. We analyze in some
detail the causal, horizon and boundary structure, and geodesic motion on these
geometries, as well as the two class of symplectic charges one can associate
with these geometries: charges associated with the exact symmetries and the
Virasoro charges. We elaborate further the one-to-one relation between the
coadjoint orbits of two copies of Virasoro group and Ba\~nados geometries. We
discuss that the information about the Ba\~nados goemetries fall into two
categories: "orbit invariant" information and "Virasoro hairs". The former are
geometric quantities while the latter are specified by the non-local surface
integrals. We elaborate on multi-BTZ geometries which have some number of
disconnected pieces at the horizon bifurcation curve. We study multi-BTZ black
hole thermodynamics and discuss that the thermodynamic quantities are orbit
invariants. We also comment on the implications of our analysis for a 2d CFT
dual which could possibly be dual to AdS3 Einstein gravity.


title: Fast Low-Complexity Decoders for Low-Rate Polar Codes

abstract:
  Polar codes are capacity-achieving error-correcting codes with an explicit
construction that can be decoded with low-complexity algorithms. In this work,
we show how the state-of-the-art low-complexity decoding algorithm can be
improved to better accommodate low-rate codes. More constituent codes are
recognized in the updated algorithm and dedicated hardware is added to
efficiently decode these new constituent codes. We also alter the polar code
construction to further decrease the latency and increase the throughput with
little to no noticeable effect on error-correction performance. Rate-flexible
decoders for polar codes of length 1024 and 2048 are implemented on FPGA. Over
the previous work, they are shown to have from 22% to 28% lower latency and 26%
to 34% greater throughput when decoding low-rate codes. On 65 nm ASIC CMOS
technology, the proposed decoder for a (1024, 512) polar code is shown to
compare favorably against the state-of-the-art ASIC decoders. With a clock
frequency of 400 MHz and a supply voltage of 0.8 V, it has a latency of 0.41
$\mu$s and an area efficiency of 1.8 Gbps/mm$^2$ for an energy efficiency of 77
pJ/info. bit. At 600 MHz with a supply of 1 V, the latency is reduced to 0.27
$\mu$s and the area efficiency increased to 2.7 Gbps/mm$^2$ at 115 pJ/info.
bit.


title:
New Sufficient Conditions for Multiple-Access Channel with Correlated
  Sources

abstract:
  The problem of three-user Multiple-Access Channel (MAC) with correlated
sources is investigated. An extension to the Cover-El Gamal-Salehi (CES) scheme
is introduced. We use a combination of this scheme with linear codes and
propose a new coding strategy. We derive new sufficient conditions to transmit
correlated sources reliably. We consider an example of three-user MAC with
binary inputs. Using this example, we show strict improvements over the CES
scheme.


title:
Local Analogs for High-redshift Galaxies: Resembling the Physical
  Conditions of the Interstellar Medium in High-redshift Galaxies

abstract:
  We present a sample of local analogs for high-redshift galaxies selected in
the Sloan Digital Sky Survey (SDSS). The physical conditions of the
interstellar medium (ISM) in these local analogs resemble those in
high-redshift galaxies. These galaxies are selected based on their positions in
the [OIII]/H$\beta$ versus [NII]/H$\alpha$ nebular emission-line diagnostic
diagram. We show that these local analogs share similar physical properties
with high-redshift galaxies, including high specific star formation rates
(sSFRs), flat UV continuums and compact galaxy sizes. In particular, the
ionization parameters and electron densities in these analogs are comparable to
those in $z\simeq2-3$ galaxies, but higher than those in normal SDSS galaxies
by $\simeq$0.6~dex and $\simeq$0.9~dex, respectively. The mass-metallicity
relation (MZR) in these local analogs shows $-0.2$~dex offset from that in SDSS
star-forming galaxies at the low mass end, which is consistent with the MZR of
the $z\sim2-3$ galaxies. We compare the local analogs in this study with those
in other studies, including Lyman break analogs (LBA) and green pea (GP)
galaxies. The analogs in this study share a similar star formation surface
density with LBAs, but the ionization parameters and electron densities in our
analogs are higher than those in LBAs by factors of 1.5 and 3, respectively.
The analogs in this study have comparable ionization parameter and electron
density to the GP galaxies, but our method can select galaxies in a wider
redshift range. We find the high sSFR and SFR surface density can increase the
electron density and ionization parameters, but still cannot fully explain the
difference in ISM condition between nearby galaxies and the local
analogs/high-redshift galaxies.


title:
Scaling laws of coronal loops compared to a 3D MHD model of an Active
  Region

abstract:
  Context. The structure and heating of coronal loops are investigated since
decades. Established scaling laws relate fundamental quantities like the loop
apex temperature, pressure, length, and the coronal heating. Aims. We test such
scaling laws against a large-scale 3D MHD model of the Solar corona, which
became feasible with nowadays high-performance computing. Methods. We drive an
active region simulation a with photospheric observations and found strong
similarities to the observed coronal loops in X-rays and EUV wavelength. A 3D
reconstruction of stereoscopic observations showed that our model loops have a
realistic spatial structure. We compare scaling laws to our model data
extracted along an ensemble of field lines. Finally, we fit a new scaling law
that represents well hot loops and also cooler structures, which was not
possible before only based on observations. Results. Our model data gives some
support for scaling laws that were established for hot and EUV-emissive coronal
loops. For the RTV scaling law we find an offset to our model data, which can
be explained by 1D considerations of a static loop with a constant heat input
and conduction. With a fit to our model data we set up a new scaling law for
the coronal heat input along magnetic field lines. Conclusions. RTV-like
scaling laws were fitted to hot loops and therefore do not predict well the
coronal heat input for cooler structures that are hardly observable. The basic
differences between 1D and self-consistent 3D modeling account for deviations
between our and earlier scaling laws. We also conclude that a heating mechanism
by MHD-turbulent dissipation within a braided flux tube would heat the corona
stronger than consistent with our model corona.


title:
Spinning dust emission from ultrasmall silicates: emissivity and
  polarization spectrum

abstract:
  Anomalous microwave emission (AME) is an important Galactic foreground of
Cosmic Microwave Background (CMB) radiation. It is believed that the AME arises
from rotational emission by spinning polycyclic aromatic hydrocarbons (PAHs) in
the interstellar medium (ISM). In this paper, we assume that a population of
ultrasmall silicate grains may exist in the ISM, and quantify rotational
emissivity from these tiny particles and its polarization spectrum. We found
that spinning silicate nanoparticles can produce strong rotational emission
when those small grains follow a log-normal size distribution. The polarization
fraction of spinning dust emission from tiny silicates increases with
decreasing the dipole moment per atom ($\beta$) and can reach $P\sim 20\%$ for
$\beta\sim 0.1$D at grain temperature of 60 K. We identify a parameter space
$(\beta,Y_{Si})$ for silicate nanoparticles in which its rotational emission
can adequately reproduce both the observed AME and the polarization of the AME,
without violating the observational constraints by the ultraviolet extinction
and polarization of starlight. Our results reveal that rotational emission from
spinning silicate may be an important source of the AME.