title: An Integrated System at the Bleien Observatory for Mapping the Galaxy

abstract:
  We describe the design and performance of the hardware system at the Bleien
Observatory. The system is designed to deliver a map of the Galaxy for studying
the foreground contamination of low-redshift (z=0.13--0.43) H$_{\rm I}$
intensity mapping experiments as well as other astronomical Galactic studies.
This hardware system is composed of a 7m parabolic dish, a dual-polarization
corrugated horn feed, a pseudo correlation receiver, a Fast Fourier Transform
spectrometer, and an integrated control system that controls and monitors the
progress of the data collection. The main innovative designs in the hardware
are (1) the pseudo correlation receiver and the cold reference source within
(2) the high dynamic range, high frequency resolution spectrometer and (3) the
phase-switch implementation of the system. This is the first time these
technologies are used together for a L-band radio telescope to achieve an
electronically stable system, which is an essential first step for wide-field
cosmological measurements. This work demonstrates the prospects and challenges
for future H$_{\rm I}$ intensity mapping experiments.


title:
Investigating the structure and fragmentation of a highly filamentary
  IRDC

abstract:
  We present 3.7 arcsec (~0.05 pc) resolution 3.2 mm dust continuum
observations from the IRAM PdBI, with the aim of studying the structure and
fragmentation of the filamentary Infrared Dark Cloud G035.39-00.33. The
continuum emission is segmented into a series of 13 quasi-regularly spaced
(~0.18pc) cores, following the major axis of the IRDC. We compare the spatial
distribution of the cores with that predicted by theoretical work describing
the fragmentation of hydrodynamic fluid cylinders, finding a significant (a
factor of ~8) discrepancy between the two. Our observations are consistent with
the picture emerging from kinematic studies of molecular clouds suggesting that
the cores are harboured within a complex network of independent sub-filaments.
This result emphasizes the importance of considering the underlying physical
structure, and potentially, dynamically important magnetic fields, in any
fragmentation analysis. The identified cores exhibit a range in (peak)
beam-averaged column density ($3.6{\rm x}10^{23}{\rm cm}^{-2}<N_{H,c}<8.0{\rm
x}10^{23}{\rm cm}^{-2}$), mass ($8.1M_{\odot}<M_{c}<26.1M_{\odot}$), and number
density ($6.1{\rm x}10^{5}{\rm cm}^{-3}<n_{H, c, eq}<14.7{\rm x}10^{5}{\rm
cm}^{-3}$). Two of these cores, dark in the mid-infrared,
centrally-concentrated, monolithic (with no traceable substructure at our PdBI
resolution), and with estimated masses of the order ~20-25$M_{\odot}$, are good
candidates for the progenitors of intermediate-to-high-mass stars. Virial
parameters span a range $0.2<\alpha_{\rm vir}<1.3$. Without additional support,
possibly from dynamically important magnetic fields with strengths of the order
230$\mu$G<B<670$\mu$G, the cores are susceptible to gravitational collapse.
These results may imply a multilayered fragmentation process, which
incorporates the formation of sub-filaments, embedded cores, and the
possibility of further fragmentation.


title:
GMOSS: All-sky model of spectral radio brightness based on physical
  components and associated radiative processes

abstract:
  We present Global MOdel for the radio Sky Spectrum (GMOSS) -- a novel,
physically motivated model of the low-frequency radio sky from 22 MHz to 23
GHz. GMOSS invokes different physical components and associated radiative
processes to describe the sky spectrum over 3072 pixels of $5^{\circ}$
resolution. The spectra are allowed to be convex, concave or of more complex
form with contributions from synchrotron emission, thermal emission and
free-free absorption included. Physical parameters that describe the model are
optimized to best fit four all-sky maps at 150 MHz, 408 MHz, 1420 MHz and 23
GHz and two maps at 22 MHz and 45 MHz generated using the Global Sky Model of
de Oliveira-Costa et al. (2008). The fractional deviation of model to data has
a median value of $6\%$ and is less than $17\%$ for $99\%$ of the pixels.
Though aimed at modeling of foregrounds for the global signal arising from the
redshifted 21-cm line of Hydrogen during Cosmic Dawn and Epoch of Reionization
(EoR) - over redshifts $150\lesssim z \lesssim 6$, GMOSS is well suited for any
application that requires simulating spectra of the low-frequency radio sky as
would be observed by the beam of any instrument. The complexity in spectral
structure that naturally arises from the underlying physics of the model
provides a useful expectation for departures from smoothness in EoR foreground
spectra and hence may guide the development of algorithms for EoR signal
detection. This aspect is further explored in a subsequent paper.


title:
Kondo insulator SmB6 under strain: surface dominated conduction near
  room temperature

abstract:
  SmB6 is a strongly correlated mixed-valence Kondo insulator with a newly
discovered surface state, proposed to be of non-trivial topological origin.
However, the surface state dominates electrical conduction only below T* ~ 4 K
limiting its scientific investigation and device application. Here, we report
the enhancement of T * in SmB6 under the application of tensile strain. With
0.7% tensile strain we report surface dominated conduction at up to a
temperature of 240 K, persisting even after the strain has been removed. This
can be explained in the framework of strain-tuned temporal and spatial
fluctuations of f-electron configurations, which might be generally applied to
other mixed-valence materials. We note that this amount of strain can be indued
in epitaxial SmB6 films via substrate in potential device applications.


title:
DM Ori: A Young Star Occulted by a Disturbance in its Protoplanetary
  Disk

abstract:
  In some planet formation theories, protoplanets grow gravitationally within a
young star's protoplanetary disk, a signature of which may be a localized
disturbance in the disk's radial and/or vertical structure. Using time-series
photometric observations by the Kilodegree Extremely Little Telescope South
(KELT-South) project and the All-Sky Automated Survey for SuperNovae (ASAS-SN),
combined with archival observations, we present the discovery of two extended
dimming events of the young star, DM Ori. This young system faded by $\sim$1.5
mag from 2000 March to 2002 August and then again in 2013 January until 2014
September (depth $\sim$1.7 mag). We constrain the duration of the 2000-2002
dimming to be $<$ 860 days, and the event in 2013-2014 to be $<$ 585 days,
separated by $\sim$12.5 years. A model of the spectral energy distribution
(SED) indicates a large infrared excess consistent with an extensive
circumstellar disk. Using basic kinematic arguments, we propose that DM Ori is
likely being periodically occulted by a feature (possibly a warp or
perturbation) in its circumstellar disk. In this scenario, the occulting
feature is located $>$6 AU from the host star, moving at $\sim$14.6 km/s, and
is $\sim$4.9 AU in width. This localized structure may indicate a disturbance
such as may be caused by a protoplanet early in its formation.


title:
Upper limits on the rates of binary neutron star and
  neutron-star--black-hole mergers from Advanced LIGO's first observing run

abstract:
  We report here the non-detection of gravitational waves from the merger of
binary neutron star systems and neutron-star--black-hole systems during the
first observing run of Advanced LIGO. In particular we searched for
gravitational wave signals from binary neutron star systems with component
masses $\in [1,3] M_{\odot}$ and component dimensionless spins $< 0.05$. We
also searched for neutron-star--black-hole systems with the same neutron star
parameters, black hole mass $\in [2,99] M_{\odot}$ and no restriction on the
black hole spin magnitude. We assess the sensitivity of the two LIGO detectors
to these systems, and find that they could have detected the merger of binary
neutron star systems with component mass distributions of $1.35\pm0.13
M_{\odot}$ at a volume-weighted average distance of $\sim$ 70Mpc, and for
neutron-star--black-hole systems with neutron star masses of $1.4M_\odot$ and
black hole masses of at least $5M_\odot$, a volume-weighted average distance of
at least $\sim$ 110Mpc. From this we constrain with 90% confidence the merger
rate to be less than 12,600 Gpc$^{-3}$yr$^{-1}$ for binary-neutron star systems
and less than 3,600 Gpc$^{-3}$yr$^{-1}$ for neutron-star--black-hole systems.
We find that if no detection of neutron-star binary mergers is made in the next
two Advanced LIGO and Advanced Virgo observing runs we would place significant
constraints on the merger rates. Finally, assuming a rate of
$10^{+20}_{-7}$Gpc$^{-3}$yr$^{-1}$ short gamma ray bursts beamed towards the
Earth and assuming that all short gamma-ray bursts have binary-neutron-star
(neutron-star--black-hole) progenitors we can use our 90% confidence rate upper
limits to constrain the beaming angle of the gamma-ray burst to be greater than
${2.3^{+1.7}_{-1.1}}^{\circ}$ (${4.3^{+3.1}_{-1.9}}^{\circ}$).


title: Level/rank Duality and Chern-Simons-Matter Theories

abstract:
  We discuss in detail level/rank duality in three-dimensional Chern-Simons
theories and various related dualities in three-dimensional Chern-Simons-matter
theories. We couple the dual Lagrangians to appropriate background fields
(including gauge fields, spin$_c$ connections and the metric). The non-trivial
maps between the currents and the line operators in the dual theories is
accounted for by mixing of these fields. In order for the duality to be valid
we must add finite counterterms depending on these background fields. This
analysis allows us to resolve a number of puzzles with these dualities, to
provide derivations of some of them, and to find new consistency conditions and
relations between them. In addition, we find new level/rank dualities of
topological Chern-Simons theories and new dualities of Chern-Simons-matter
theories, including new boson/boson and fermion/fermion dualities.


title:
Brown dwarf disks with Herschel: Linking far-infrared and (sub)-mm
  fluxes

abstract:
  Brown dwarf disks are excellent laboratories to test our understanding of
disk physics in an extreme parameter regime. In this paper we investigate a
sample of 29 well-characterized brown dwarfs and very low mass stars, for which
Herschel far-infrared fluxes as well as (sub)-mm fluxes are available. We have
measured new Herschel PACS fluxes for 11 objects and complement these with
(sub)-mm data and Herschel fluxes from the literature. We analyze their
spectral energy distributions in comparison with results from radiative
transfer modeling. Fluxes in the far-infrared are strongly affected by the
shape and temperature of the disk (and hence stellar luminosity), whereas the
(sub)-mm fluxes mostly depend on disk mass. Nevertheless, there is a clear
correlation between far-infrared and (sub)-mm fluxes. We argue that the link
results from the combination of the stellar mass-luminosity relation and a
scaling between disk mass and stellar mass. We find strong evidence of dust
settling to the disk midplane. The spectral slopes between near- and
far-infrared are mostly between $-0.5$ and $-1.2$ in our sample, comparable to
more massive T Tauri stars, which may imply that the disk shapes are similar as
well, though highly-flared disks are rare among brown dwarfs. We find that dust
temperatures in the range of 7-15 K, calculated with
$T\approx25\,(L/L_\odot)^{0.25}$ K, are appropriate for deriving disk masses
from (sub)-mm fluxes for these low luminosity objects. About half of our sample
hosts disks with at least one Jupiter mass, confirming that many brown dwarfs
harbour sufficient material for the formation of Earth-mass planets in their
midst.


title:
High-efficiency WSi superconducting nanowire single-photon detectors for
  quantum state engineering in the near infrared

abstract:
  We report on high-efficiency superconducting nanowire single-photon detectors
based on amorphous WSi and optimized at 1064 nm. At an operating temperature of
1.8 K, we demonstrated a 93% system detection efficiency at this wavelength
with a dark noise of a few counts per second. Combined with cavity-enhanced
spontaneous parametric down-conversion, this fiber-coupled detector enabled us
to generate narrowband single photons with a heralding efficiency greater than
90% and a high spectral brightness of $0.6\times10^4$
photons/(s$\cdot$mW$\cdot$MHz). Beyond single-photon generation at large rate,
such high-efficiency detectors open the path to efficient multiple-photon
heralding and complex quantum state engineering.


title: Creation of Magnetic Monopoles in Classical Scattering

abstract:
  We consider the creation of 't Hooft-Polyakov magnetic monopoles by
scattering classical wave packets of gauge fields. An example with eight
clearly separated magnetic poles created with parity violating helical initial
conditions is shown. No clear separation of topological charge is observed with
corresponding parity symmetric initial conditions.


title: Stable phantom-energy wormholes admitting conformal motions

abstract:
  It has been argued that wormholes are as good a prediction of Einstein's
theory as black holes but the theoretical construction requires a reverse
strategy, specifying the desired geometric properties of the wormhole and
leaving open the determination of the stress-energy tensor. We begin by
confirming an earlier result by the author showing that a complete wormhole
solution can be obtained by adopting the equation of state $p=\omega\rho$ and
assuming that the wormhole admits a one-parameter group of conformal motions.
The main purpose of this paper is to use the assumption of conformal symmetry
to show that the wormhole is stable to linearized radial perturbations whenever
$-1.5<\omega <-1$.


title: Entanglement Entropy of Periodic Sublattices

abstract:
  We study the entanglement entropy (EE) of Gaussian systems on a lattice with
periodic boundary conditions, both in the vacuum and at nonzero temperatures.
By restricting the reduced subsystem to periodic sublattices, we can compute
the entanglement spectrum and EE exactly. We illustrate this for a free
(1+1)-dimensional massive scalar field at a fixed temperature. Consistent with
previous literature, we demonstrate that for a sufficiently large periodic
sublattice the EE grows extensively, even in the vacuum. Furthermore, the
analytic expression for the EE allows us probe its behavior both in the
massless limit and in the continuum limit at any temperature.


title: Stochastic Feynman Rules for Yang-Mills Theory on the Plane

abstract:
  We analyze quantum Yang-Mills theory on $\mathbb{R}^2$ using a novel
discretization method based on an algebraic analogue of stochastic calculus.
Such an analogue involves working with "Gaussian" free fields whose covariance
matrix is indefinite rather than positive definite. Specifically, we work with
Lie-algebra valued fields on a lattice and exploit an approximate
gauge-invariance that is restored when taking the continuum limit. This
analysis is applied to show the equivalence between Wilson loop expectations
computed using partial axial-gauge, complete axial-gauge, and the Migdal-Witten
lattice formulation. As a consequence, we obtain intriguing Lie-theoretic
identities involving heat kernels and iterated integrals.


title:
Bringing the 'perfect lens' into focus by near-perfect compensation of
  losses without gain media

abstract:
  In this paper, the optical properties and imaging performance of a non-ideal
Pendry's negative index flat lens with a practical value for loss are studied.
Analytical calculations of the optical properties of the lens are performed,
and those results are used to further study the lens and corresponding imaging
system numerically. The plasmon injection scheme for loss compensation in
negative index metamaterials is applied to the results from the imaging system,
resulting in a perfect reconstruction of a previously unresolved image that
demonstrates sub-diffraction-limit resolution.


title:
The Dynamical Generation of Current Sheets in Astrophysical Plasma
  Turbulence

abstract:
  Turbulence profoundly affects particle transport and plasma heating in many
astrophysical plasma environments, from galaxy clusters to the solar corona and
solar wind to Earth's magnetosphere. Both fluid and kinetic simulations of
plasma turbulence ubiquitously generate coherent structures, in the form of
current sheets, at small scales, and the locations of these current sheets
appear to be associated with enhanced rates of dissipation of the turbulent
energy. Therefore, illuminating the origin and nature of these current sheets
is critical to identifying the dominant physical mechanisms of dissipation, a
primary aim at the forefront of plasma turbulence research. Here we present
evidence from nonlinear gyrokinetic simulations that strong nonlinear
interactions between counterpropagating Alfven waves, or strong Alfven wave
collisions, are a natural mechanism for the generation of current sheets in
plasma turbulence. Furthermore, we conceptually explain this current sheet
development in terms of the nonlinear dynamics of Alfven wave collisions,
showing that these current sheets arise through constructive interference among
the initial Alfven waves and nonlinearly generated modes. The properties of
current sheets generated by a strong Alfven wave collisions are compared to
published observations of current sheets in the Earth's magnetosheath and the
solar wind, and the nature of these current sheets leads to the expectation
that Landau damping of the constituent Alfven waves plays a dominant role in
the damping of turbulently generated current sheets.


title:
Enhancing the resolution of hyperlens by the compensation of losses
  without gain media

abstract:
  We present a method to improve the resolution of available hyperlenses in the
literature. In this method, we combine the operation of hyperlens with the
recently proposed plasmon injection scheme for loss compensation in
metamaterials. Image of an object, which is otherwise not resolvable by the
hyperlens alone, was reconstructed up to the minimum feature size of one
seventh of the free-space wavelength.


title: Energy spectrum of a Langevin oscillator

abstract:
  We derive analytical solutions for the autocorrelation and cross-correlation
functions of the kinetic, potential and total energy of a Langevin oscillator.
These functions are presented in both the time and frequency domains and
validated by independent numerical simulations. The results are applied to
address the long-standing issue of temperature fluctuations in canonical
systems.


title: Some Types of Recurrence in Finsler geometry

abstract:
  The pullback approach to global Finsler geometry is adopted. Three classes of
recurrence in Finsler geometry are introduced and investigated: simple
recurrence, Ricci recurrence and concircular recurrence. Each of these classes
consists of four types of recurrence. The interrelationships between the
different types of recurrence are studied. The generalized concircular
recurrence, as a new concept, is singled out.


title: The Impacts of Learning Assistants on Student Learning of Physics

abstract:
  This study investigated whether and how Learning Assistant (LA) support is
linked to student outcomes in Physics courses nationwide. Paired student
concept inventory scores were collected over three semesters from 3,753
students, representing 69 courses, and 40 instructors, from 17 LA Alliance
member institutions. Each participating student completed an online concept
inventory at the beginning (pre) and end (post) of each term. The physics
concept inventories tested included the Force Concept Inventory (FCI),
Conceptual Survey of Electricity and Magnetism (CSEM), Force and Motion Concept
Evaluation (FMCE) and the Brief Electricity and Magnetism Assessment (BEMA).
Across instruments, Cohen's d effect sizes were 1.4 times higher, on average,
for courses supported by LAs compared to courses without LA support.
Preliminary findings indicate that physics students' outcomes may be most
effective when LA support is utilized in laboratory settings (1.9 times higher
than no LA support) in comparison to lecture (1.4 times higher), recitations
(1.5 times higher), or unknown uses (1.3 times higher). Additional research
will inform LA-implementation best practices across disciplines.


title: Scaling Sampling-based Motion Planning to Humanoid Robots

abstract:
  Planning balanced and collision-free motion for humanoid robots is
non-trivial, especially when they are operated in complex environments, such as
reaching targets behind obstacles or through narrow passages. We propose a
method that allows us to apply existing sampling--based algorithms to plan
trajectories for humanoids by utilizing a customized state space
representation, biased sampling strategies, and a steering function based on a
robust inverse kinematics solver. Our approach requires no prior offline
computation, thus one can easily transfer the work to new robot platforms. We
tested the proposed method solving practical reaching tasks on a 38
degrees-of-freedom humanoid robot, NASA Valkyrie, showing that our method is
able to generate valid motion plans that can be executed on advanced full-size
humanoid robots. We also present a benchmark between different motion planning
algorithms evaluated on a variety of reaching motion problems. This allows us
to find suitable algorithms for solving humanoid motion planning problems, and
to identify the limitations of these algorithms.


title: Lorentzian Condition in Holographic Cosmology

abstract:
  We derive a sufficient set of conditions on the Euclidean boundary theory in
dS/CFT for it to predict classical, Lorentzian bulk evolution at large spatial
volumes. Our derivation makes use of a canonical transformation to express the
bulk wave function at large volume in terms of the sources of the dual
partition function. This enables a sharper formulation of dS/CFT. The
conditions under which the boundary theory predicts classical bulk evolution
are stronger than the criteria usually employed in quantum cosmology. We
illustrate this in a homogeneous isotropic minisuperspace model of gravity
coupled to a scalar field in which we identify the ensemble of classical
histories explicitly.


title: Efficient Multi-Agent Global Navigation Using Interpolating Bridges

abstract:
  We present a novel approach for collision-free global navigation for
continuous-time multi-agent systems with general linear dynamics. Our approach
is general and can be used to perform collision-free navigation in 2D and 3D
workspaces with narrow passages and crowded regions. As part of
pre-computation, we compute multiple bridges in the narrow or tight regions in
the workspace using kinodynamic RRT algorithms. Our bridge has certain
geometric characteristics, that en- able us to calculate a collision-free
trajectory for each agent using simple interpolation at runtime. Moreover, we
combine interpolated bridge trajectories with local multi-agent navigation
algorithms to compute global collision-free paths for each agent. The overall
approach combines the performance benefits of coupled multi-agent algorithms
with the pre- computed trajectories of the bridges to handle challenging
scenarios. In practice, our approach can handle tens to hundreds of agents in
real-time on a single CPU core in 2D and 3D workspaces.


title: Amplification of the diamagnetic response in small Hubbard rings

abstract:
  In this paper, we present a study of the electric transport properties of
small discrete rings with $3\leq N\leq 6$ sites and $N_{e}<2N$ electrons, which
can be seen as a simplified version of real aromatic molecules. In particular,
the ring with six sites and six electrons is our prototype of the benzene
molecule. It is already known that the Hubbard model itself cannot account for
the anisotropy of the diamagnetic susceptibility of the aromatic molecules,
which is observed when they are subjected to an external magnetic field
perpendicular to their basal plane. Therefore, we propose an extension of the
Hubbard model, with an ad hoc extra interaction term, with two adjustable
parameters. Our results show that this extension of the Hubbard model is able
to amplify the persistent currents established in the ground state of our rings
and, moreover, promotes an enhancement of the magnetic susceptibility
anisotropy depending on the tuning of the adjustable parameters. In particular,
for the prototype of the benzene molecule, we recover the order of magnitude of
the diamagnetic anisotropy measured for this molecule.


title:
Generalization of the Ewens sampling formula to arbitrary fitness
  landscapes

abstract:
  In considering evolution of transcribed regions, regulatory modules, and
other genomic loci of interest, we are often faced with a situation in which
the number of allelic states greatly exceeds the population size. In this
limit, the population eventually adopts a steady state characterized by
mutation-selection-drift balance. Although new alleles continue to be explored
through mutation, the statistics of the population, and in particular the
probabilities of seeing specific allelic configurations in samples taken from a
population, do not change with time. In the absence of selection, probabilities
of allelic configurations are given by the Ewens sampling formula, widely used
in population genetics to detect deviations from neutrality. Here we develop an
extension of this formula to arbitrary, possibly epistatic, fitness landscapes.
Although our approach is general, we focus on the class of landscapes in which
alleles are grouped into two, three, or several fitness states. This class of
landscapes yields sampling probabilities that are computationally more
tractable, and can form a basis for the inference of selection signatures from
sequence data. We demonstrate that, for a sizeable range of mutation rates and
selection coefficients, the steady-state allelic diversity is not neutral.
Therefore, it may be used to infer selection coefficients, as well as other key
evolutionary parameters, using high-throughput sequencing of evolving
populations to collect data on locus polymorphisms. We also find that our
theory remains sufficiently accurate even if the assumptions such as the
infinite allele limit and the "full connectivity" assumption in which each
allele can mutate into any other allele are relaxed. Thus, our framework
establishes a theoretical foundation for inferring selection signatures from
samples of sequences produced by evolution on epistatic fitness landscapes.


title:
Measurement-only topological quantum computation without forced
  measurements

abstract:
  We investigate the measurement-only topological quantum computation (MOTQC)
approach proposed by Bonderson et al. [Phys. Rev. Lett. 101, 010501 (2008)]
where the braiding operation is shown to be equivalent to a series of
topological charge "forced measurements" of anyons. In a forced measurement,
the charge measurement is forced to yield the desired outcome (e.g. charge 0)
via repeatedly measuring charges in different bases. This is a probabilistical
process with a certain success probability for each trial. In practice, the
number of measurements needed will vary from run to run. We show that such an
uncertainty associated with forced measurements can be removed by simulating
the braiding operation using a fixed number of three measurements supplemented
by a correction operator. Furthermore, we demonstrate that in practice we can
avoid applying the correction operator in hardware by implementing it in
software. Our findings greatly simplify the MOTQC proposal and only require the
capability of performing charge measurements to implement topologically
protected transformations generated by braiding exchanges without physically
moving anyons.


title:
First lensed quasar systems from the VST-ATLAS survey: one quad, two
  doubles and two pairs of lensless twins

abstract:
  We have analyzed images from the VST ATLAS survey to identify candidate
gravitationally lensed quasar systems in a sample of WISE sources with W1 - W2
> 0.7. Results from followup spectroscopy with the Baade 6.5 m telescope are
presented for eight systems. One of these is a quadruply lensed quasar and two
are doubly lensed systems. Two are projected superpositions of two quasars at
different redshifts. In one system two quasars, though at the same redshift,
have very different emission line profiles, and constitute a physical binary.
In two systems the component spectra are consistent with the lensing
hypothesis, after allowing for micro-lensing. But as no lensing galaxy is
detected in these two, we classify them as lensless twins. More extensive
observations are needed to establish whether they are in fact lensed quasars or
physical binaries.


title:
Bringing short-lived dissipative Kerr soliton states in microresonators
  into a steady state

abstract:
  Dissipative Kerr solitons have recently been generated in optical
microresonators, enabling ultrashort optical pulses at microwave repetition
rates, that constitute coherent and numerically predictable Kerr frequency
combs. However, the seeding and excitation of the temporal solitons is
associated with changes in the intracavity power, that can lead to large
thermal resonance shifts during the excitation process and render the soliton
states in most commonly used resonator platforms short lived. Here we describe
a "power kicking" method to overcome this instability by modulating the power
of the pump laser. A fast modulation triggers the soliton formation, while a
slow adjustment of the power compensates the thermal effect during the
excitation laser scan. With this method also initially very short-lived (100ns)
soliton states , as encountered in SiN integrated photonic microresonators, can
be brought into a steady state in contrast to techniques reported earlier which
relied on an adjustment of the laser scan speed only. Once the soliton state is
in a steady state it can persist for hours and is thermally self-locked.


title:
"What's (the) Matter?", A Show on Elementary Particle Physics with 28
  Demonstration Experiments

abstract:
  We present the screenplay of a physics show on particle physics, by the
Physikshow of Bonn University. The show is addressed at non-physicists aged 14+
and communicates basic concepts of elementary particle physics including the
discovery of the Higgs boson in an entertaining fashion. It is also
demonstrates a successful outreach activity heavily relying on the university
physics students. This paper is addressed at anybody interested in particle
physics and/or show physics. This paper is also addressed at fellow physicists
working in outreach, maybe the experiments and our choice of simple
explanations will be helpful. Furthermore, we are very interested in related
activities elsewhere, in particular also demonstration experiments relevant to
particle physics, as often little of this work is published.
  Our show involves 28 live demonstration experiments. These are presented in
an extensive appendix, including photos and technical details. The show is set
up as a quest, where 2 students from Bonn with the aid of a caretaker travel
back in time to understand the fundamental nature of matter. They visit
Rutherford and Geiger in Manchester around 1911, who recount their famous
experiment on the nucleus and show how particle detectors work. They travel
forward in time to meet Lawrence at Berkeley around 1950, teaching them about
the how and why of accelerators. Next, they visit Wu at DESY, Hamburg, around
1980, who explains the strong force. They end up in the LHC tunnel at CERN,
Geneva, Switzerland in 2012. Two experimentalists tell them about colliders and
our heroes watch live as the Higgs boson is produced and decays. The show was
presented in English at Oxford University and University College London, as
well as Padua University and ICTP Trieste. It was 1st performed in German at
the Deutsche Museum, Bonn (5/'14). The show has eleven speaking parts and
involves in total 20 people.

categories: physics.pop-ph hep-ex hep-ph hep-th physics.ed-ph


title: Test Function Spaces for Geometric Finite Elements

abstract:
  We construct test function spaces for geometric finite elements. Geometric
finite elements (GFE) are generalizations of Lagrangian finite elements to
situations where the unknown function maps into a nonlinear space. Test
functions for such spaces arise as variations of GFE functions wherever the GFE
function space has a local manifold structure. For any given GFE function
$u_h$, the test functions form a linear space that depends on $u_h$. They
generalize Jacobi fields in the same way that the GFE interpolation functions
generalize geodesic curves. Having test function spaces allows to extend the
GFE method to boundary value problems that do not have a minimization
formulation.


title: The Structure of Plasma Heating in Gyrokinetic Alfv\'enic Turbulence

abstract:
  We analyze plasma heating in weakly collisional kinetic Alfv\'en wave (KAW)
turbulence using high resolution gyrokinetic simulations spanning the range of
scales between the ion and the electron gyroradii. Real space structures that
have a higher than average heating rate are shown not to be confined to current
sheets. This novel result is at odds with previous studies, which use the
electromagnetic work in the local electron fluid frame, i.e. $\mathbf{J}
\!\cdot\! (\mathbf{E} + \mathbf{v}_e\times\mathbf{B})$, as a proxy for
turbulent dissipation to argue that heating follows the intermittent spatial
structure of the electric current. Furthermore, we show that electrons are
dominated by parallel heating while the ions prefer the perpendicular heating
route. We comment on the implications of the results presented here.


title:
Spontaneous topological transitions of electromagnetic fields in
  spatially inhomogeneous CP-odd domains

abstract:
  Metastable CP-odd domains of the hot QCD matter are coupled to QED via the
chiral anomaly. The topology of electromagnetic field in these domains is
characterized by magnetic helicity. It is argued, using the
Maxwell-Chern-Simons model, that spatial inhomogeneity of the domains induces
spontaneous transitions of electromagnetic field between the opposite magnetic
helicity states.


title:
More on measurable algebras and Rademacher systems with applications to
  analysis of Riesz spaces

abstract:
  We find necessary and sufficient conditions on a family $\mathcal{R} =
(r_i)_{i \in I}$ in a Boolean algebra $\mathcal{B}$ under which there exists a
unique positive probability measure $\mu$ on $\mathcal{B}$ such that $\mu (
\bigcap_{k=1}^n \theta_k r_{i_k} ) = 2^{-n}$ for all finite collections of
distinct indices $i_1, \ldots, i_n \in I$ and all collections of signs
$\theta_1, \ldots, \theta_n \in \{-1,1\}$, where the product $\theta x$ of a
sign $\theta$ by an element $x \in \mathcal{B}$ is defined by setting $1 x = x$
and $-1 x = - x = \mathbf{1} \setminus x$. Such a family we call a complete
Rademacher family. We prove that Dedekind $\sigma$-complete Boolean algebras
admitting complete Rademacher systems of the same cardinality are isomorphic.
As a consequence, we obtain that a Dedekind $\sigma$-complete Boolean algebra
is homogeneous measurable if and only if it admits a complete Rademacher
family. This new way to define a measure on a Boolean algebra allows us to
define classical systems on an arbitrary Riesz space, such as Rademacher and
Haar. We define a complete Rademacher system of any cardinality and a countable
complete Haar system on an element $e > 0$ of a vector lattice $E$ in such a
way that if $e$ is an order unit of $E$ then the corresponding systems become
complete for the entire $E$. We prove that if $E$ is Dedekind complete then any
complete Haar system on $e$ is an order Schauder basis for the ideal $A_e$
generated by $e$. Finally, we develop a theory of integration in a Riesz space
of elements of the band $B_e$ generated by a fixed $e > 0$ with respect to the
measure on the Boolean algebra $\mathfrak{F}_e$ of fragments of $e$ generated
by a complete Rademacher family on $\mathfrak{F}_e$. Much space is devoted to
examples showing that our way of thinking is sharp (e.g., we show the
essentiality of each of the condition in the definition of a Rademacher
family).


title:
Collision-Free Poisson Motion Planning in Ultra High-Dimensional
  Molecular Conformation Spaces

abstract:
  The function of protein, RNA, and DNA is modulated by fast, dynamic exchanges
between three-dimensional conformations. Conformational sampling of
biomolecules with exact and nullspace inverse kinematics, using rotatable bonds
as revolute joints and non-covalent interactions as holonomic constraints, can
accurately characterize these native ensembles. However, sampling biomolecules
remains challenging owing to their ultra-high dimensional configuration spaces,
and the requirement to avoid (self-) collisions, which results in low
acceptance rates.
  Here, we present two novel mechanisms to overcome these limitations. First,
we introduced temporary constraints between near-colliding links. The resulting
constraint varieties instantaneously redirect the search for collision-free
conformations, and couple motions between distant parts of the linkage. Second,
we adapted a randomized Poisson-disk motion planner, which prevents local
oversampling and widens the search, to ultra-high dimensions. We evaluated our
algorithm on several model systems. Our contributions apply to general
high-dimensional motion planning problems in static and dynamic environments
with obstacles.


title: Phase Retrieval by Linear Algebra

abstract:
  The null vector method, based on a simple linear algebraic concept, is
proposed as a solution to the phase retrieval problem.
  In the case with complex Gaussian random measurement matrices, a
non-asymptotic error bound is derived, yielding an asymptotic regime of
accurate approximation comparable to that for the spectral vector method.


title:
Optically Detected Ferromagnetic Resonance in Metallic Ferromagnets via
  Nitrogen Vacancy Centers in Diamond

abstract:
  We report quantitative measurements of optically detected ferromagnetic
resonance (ODFMR) of ferromagnetic thin films that use nitrogen-vacancy (NV)
centers in diamonds to transduce FMR into a fluorescence intensity variation.
To uncover the mechanism responsible for these signals, we study ODFMR as we 1)
vary the separation of the NV centers from the ferromagnet (FM), 2) record the
NV center longitudinal relaxation time $T_1$ during FMR, and 3) vary the
material properties of the FM. Based on the results, we propose the following
mechanism for ODFMR. Decay and scattering of the driven, uniform FMR mode
results in spinwaves that produce fluctuating dipolar fields in a spectrum of
frequencies. When the spinwave spectrum overlaps the NV center ground-state
spin resonance frequencies, the dipolar fields from these resonant spinwaves
relax the NV center spins, resulting in an ODFMR signal. These results lay the
foundation for an approach to NV center spin relaxometry to study FM dynamics
without the constraint of directly matching the NV center spin-transition
frequency to the magnetic system of interest, thus enabling an alternate
modality for scanned-probe magnetic microscopy that can sense ferromagnetic
resonance with nanoscale resolution.


title:
Legendrian curves in $\mathbb C P^3$: cubics and curves on a quadric
  surface

abstract:
  We prove that the number of legendrian rational cubics in $\mathbb C P^3$
through three generic points and a line is three; also we classify all
legendrian curves on a quadric surface. Several computations are additionally
verified using Macaulay2 computer algebra system.


title:
High braking index pulsar PSR J1640-4631: low-mass neutron star with a
  large inclination angle?

abstract:
  Recent timing observation constrained the braking index of the X-ray pulsar
PSR J1640-4631 to be $n=3.15\pm0.03$, which is the highest value of all pulsars
with measured braking indices so far. In this Letter, we investigate whether
pulsar braking by combined between the magnetic dipole emission and the
gravitational radiation might have a braking index greater than three. For
conventional neutron star and low mass quark star candidates, the inferred
ellipticities derived by the observed braking index are obviously much larger
than the theoretical estimated maximum value. If PSR J1640-4631 is a low-mass
neutron star with a mass of $0.1~ \rm M_{\odot}$, the inferred ellipticity can
be approximately equal to the theoretical estimated maximum value. Because of
the radio-quiet nature of this source, we employ the vacuum gap model developed
by Ruderman and Sutherland to constrain the inclination angle to be
$87.2-90^{\circ}$. Based on this, we propose that a low-mass neutron star with
a large inclination angle can interpret the high braking index and the
radio-quiet nature of this source. Future observations such as gravitational
wave detection and long-term timing for this source are required to confirm or
confute our scenario.


title: Boson stars, neutron stars and black holes in five dimensions

abstract:
  Different types of gravitating compact objects occuring in d=5 space-time are
considered: boson stars, hairy black holes and perfect fluid solutions. All
these solutions of the Einstein equations coupled to matter have well
established counterparts in d=4; in particular neutron stars can be
modell{\S}ed more or less realistically by a perfect fluid. A special emphasis
is set on the possibility -and/or the necessity- for these solutions to have an
intrinsic angular momentum or spin. The influence of a cosmological constant on
their pattern is also studied.
  Several physical properties are presented from which common features to boson
and neutron stars clearly emerge.
  We finally point out qualitative differences of the gravitational interaction
supporting these classical lumps between four and five dimensions.


title:
Automatic Construction of Statechart-Based Anomaly Detection Models for
  Multi-Threaded Industrial Control Systems

abstract:
  Traffic of Industrial Control System (ICS) between the Human Machine
Interface (HMI) and the Programmable Logic Controller (PLC) is known to be
highly periodic. However, it is sometimes multiplexed, due to asynchronous
scheduling. Modeling the network traffic patterns of multiplexed ICS streams
using Deterministic Finite Automata (DFA) for anomaly detection typically
produces a very large DFA, and a high false-alarm rate. We introduce a new
modeling approach that addresses this gap. Our Statechart DFA modeling includes
multiple DFAs, one per cyclic pattern, together with a DFA-selector that
de-multiplexes the incoming traffic into sub-channels and sends them to their
respective DFAs. We demonstrate how to automatically construct the Statechart
from a captured traffic stream. Our unsupervised learning algorithm builds a
Discrete-Time Markov Chain (DTMC) from the stream. Next it splits the symbols
into sets, one per multiplexed cycle, based on symbol frequencies and node
degrees in the DTMC graph. Then it creates a sub-graph for each cycle, and
extracts Euler cycles for each sub-graph. The final Statechart is comprised of
one DFA per Euler cycle. The algorithms allow for non-unique symbols, that
appear in more than one cycle, and also for symbols that appear more than once
in a cycle. We evaluated our solution on traces from a production ICS using the
Siemens S7-0x72 protocol. We also stress-tested our algorithms on a collection
of synthetically-generated traces that simulated multiplexed ICS traces with
varying levels of symbol uniqueness and time overlap. The algorithms were able
to split the symbols into sets with 99.6% accuracy. The resulting Statechart
modeled the traces with a low median false-alarm rate of 0.483%. In all but the
most extreme scenarios the Statechart model drastically reduced both the
false-alarm rate and the learned model size in compare to a naive single-DFA
model


title: Representations of Spin(4), Spin(2,2) and Spin(3,1)

abstract:
  In this essay we present an outer product on R^6, and we show that R^6 with
this outer product can take three kinds of Lie brackets. We prove that R^6 with
these Lie brackets take the structures of so(4), so(2,2) and so(3,1). We also
deduce a 4-dimensional submanifold of R^6 with an almost complex structure.


title: Better upper bounds on the F\"uredi-Hajnal limits of permutations

abstract:
  A binary matrix is a matrix with entries from the set $\{0,1\}$. We say that
a binary matrix $A$ contains a binary matrix $S$ if $S$ can be obtained from
$A$ by removal of some rows, some columns, and changing some $1$-entries to
$0$-entries. If $A$ does not contain $S$, we say that $A$ avoids $S$. A
$k$-permutation matrix $P$ is a binary $k \times k$ matrix with exactly one
$1$-entry in every row and one $1$-entry in every column.
  The F\"uredi-Hajnal conjecture, proved by Marcus and Tardos, states that for
every permutation matrix $P$, there is a constant $c_P$ such that for every $n
\in \mathbb{N}$, every $n \times n$ binary matrix $A$ with at least $c_P n$
$1$-entries contains $P$.
  We show that $c_P \le 2^{O(k^{2/3}\log^{7/3}k / (\log\log k)^{1/3})}$
asymptotically almost surely for a random $k$-permutation matrix $P$. We also
show that $c_P \le 2^{(4+o(1))k}$ for every $k$-permutation matrix $P$,
improving the constant in the exponent of a recent upper bound on $c_P$ by Fox.
Moreover, we improve the upper bound on $c_P$ in terms of the Stanley-Wilf
limit $s_P$ to $c_P \le O\big(s_P^{2.75} \log s_P\big)$.
  We also consider a higher-dimensional generalization of the Stanley-Wilf
conjecture about the number of $d$-dimensional $n$-permutation matrices
avoiding a fixed $d$-dimensional $k$-permutation matrix, and prove almost
matching upper and lower bounds of the form $(2^k)^{O(n)} \cdot
(n!)^{d-1-1/(d-1)}$ and $n^{-O(k)} k^{\Omega(n)} \cdot (n!)^{d-1-1/(d-1)}$,
respectively.


title: The Gauss map of a complete minimal surface with finite total curvature

abstract:
  In [15] Robert Osserman proved that the image of the Gauss map of a complete,
non flat minimal surface in R^3 with finite total curvature miss at most 3
points. In this paper we prove that the Gauss map of such a minimal immersions
omit at most 2 points. This is a sharp result since the Gauss map of the
catenoid omits exactly two points. In fact we prove this result for a wider
class of isometric immersions, that share the basic differential topological
properties of the complete minimal surfaces of finite total curvature.


title:
"Pulling out" as a procedural resource when solving partial differential
  equations

abstract:
  We investigate how students solve partial differential equations and partial
derivatives in the context of quantum mechanics. We use the resources framework
to investigate students' discussion in a group problem-solving environment to
investigate the fine-grain elements of their problem solving. We analyze an
example of students' use of separation of variables to solve a partial
differential equation for a free particle problem. We identify a mathematical
action called "pulling out" as a procedural resource to help students with
separating the time part from the space part of the wave function in the course
of solving the time-dependent Schrodinger equation. We discuss how students use
"pulling out" as a procedural step in solving partial differential equations
and sense-making.


title:
Adaptive Closed Loop OFDM-Based Resource Allocation Method using Machine
  Learning and Genetic Algorithm

abstract:
  In this paper, the concept of Machine Learning (ML) is introduced to the
Orthogonal Frequency Division Multiple Access-based (OFDMA-based) scheduler.
Similar to the impact of the Channel Quality Indicator (CQI) on the scheduler
in the Long Term Evolution (LTE), ML is utilized to provide the scheduler with
pertinent information about the User Equipment (UE) traffic patterns, demands,
Quality of Service (QoS) requirements, instantaneous user throughput and other
network conditions. An adaptive ML-based framework is proposed in order to
optimize the LTE scheduler operation. The proposed technique targets multiple
objective scheduling strategies. The weights of the different objectives are
adjusted to optimize the resources allocation per transmission based on the UEs
demand pattern. In addition, it overcomes the trade-off problem of the
traditional scheduling methods. The technique can be used as a generic
framework with any scheduling strategy. In this paper, Genetic Algorithm-based
(GA-based) multi- objective scheduler is considered to illustrate the
efficiency of the proposed adaptive scheduling solution. Results show that
using the combination of clustering and classification algorithms along with
the GA optimizes the GA scheduler functionality and makes use of the ML process
to form a closed loop scheduling mechanism.


title:
Understanding Communication Patterns in MOOCs: Combining Data Mining and
  qualitative methods

abstract:
  Massive Open Online Courses (MOOCs) offer unprecedented opportunities to
learn at scale. Within a few years, the phenomenon of crowd-based learning has
gained enormous popularity with millions of learners across the globe
participating in courses ranging from Popular Music to Astrophysics. They have
captured the imaginations of many, attracting significant media attention -
with The New York Times naming 2012 "The Year of the MOOC." For those engaged
in learning analytics and educational data mining, MOOCs have provided an
exciting opportunity to develop innovative methodologies that harness big data
in education.

categories: cs.CY cs.SI physics.data-an physics.soc-ph


title: Quantum carpets: A probe to identify wave packet fractional revivals

abstract:
  Quantum carpets- in position and momentum space- woven by the
self-interference of de Broglie wave of an atom or an electron, trapped in an
infinitely deep potential well, are explained. The recurrence of self-similar
structures in designs of these carpets mimics the phenomena of quantum revivals
and fractional revivals. We identify fractional revivals of various order by
means of these space-time and momentum-time interference patterns.


title: A Hierarchy of Lower Bounds for Sublinear Additive Spanners

abstract:
  Spanners, emulators, and approximate distance oracles can be viewed as lossy
compression schemes that represent an unweighted graph metric in small space,
say $\tilde{O}(n^{1+\delta})$ bits. There is an inherent tradeoff between the
sparsity parameter $\delta$ and the stretch function $f$ of the compression
scheme, but the qualitative nature of this tradeoff has remained a persistent
open problem.
  In this paper we show that the recent additive spanner lower bound of Abboud
and Bodwin is just the first step in a hierarchy of lower bounds that fully
characterize the asymptotic behavior of the optimal stretch function $f$ as a
function of $\delta \in (0,1/3)$. Specifically, for any integer $k\ge 2$, any
compression scheme with size $O(n^{1+\frac{1}{2^k-1} - \epsilon})$ has a
sublinear additive stretch function $f$: $$f(d) = d +
\Omega(d^{1-\frac{1}{k}}).$$ This lower bound matches Thorup and Zwick's (2006)
construction of sublinear additive emulators. It also shows that Elkin and
Peleg's $(1+\epsilon,\beta)$-spanners have an essentially optimal tradeoff
between $\delta,\epsilon,$ and $\beta$, and that the sublinear additive
spanners of Pettie (2009) and Chechik (2013) are not too far from optimal.
  To complement these lower bounds we present a new construction of
$(1+\epsilon, O(k/\epsilon)^{k-1})$-spanners with size $O((k/\epsilon)^{h_k}
kn^{1+\frac{1}{2^{k+1}-1}})$, where $h_k < 3/4$. This size bound improves on
the spanners of Elkin and Peleg (2004), Thorup and Zwick (2006), and Pettie
(2009). According to our lower bounds neither the size nor stretch function can
be substantially improved.


title: On the detection of superdiffusive behaviour in time series

abstract:
  We present a new method for detecting superdiffusive behaviour and for
determining rates of superdiffusion in time series data. Our method applies
equally to stochastic and deterministic time series data (with no prior
knowledge required of the nature of the data) and relies on one realisation (ie
one sample path) of the process. Linear drift effects are automatically removed
without any preprocessing. We show numerical results for time series
constructed from i.i.d. $\alpha$-stable random variables and from deterministic
weakly chaotic maps. We compare our method with the standard method of
estimating the growth rate of the mean-square displacement as well as the
$p$-variation method, maximum likelihood, quantile matching and linear
regression of the empirical characteristic function.


title: A connected sum formula for involutive Heegaard Floer homology

abstract:
  We prove a connected sum formula for involutive Heegaard Floer homology, and
use it to study the involutive correction terms of connected sums. In
particular, we give an example of a three-manifold with $\underline{d}(Y) \neq
d(Y) \neq \overline{d}(Y)$. We also construct a homomorphism from the
three-dimensional homology cobordism group to an algebraically defined Abelian
group, consisting of certain complexes (equipped with a homotopy involution)
modulo a notion of local equivalence.


title:
Charge Neutral MoS2 Field Effect Transistors Through Oxygen Plasma
  Treatment

abstract:
  Lithographically fabricated MoS2 field effect transistors suffer from several
critical imperfections, including low sub-threshold swings, large turn-on gate
voltages (VT), and wide device-to-device variability. The large magnitude and
variability of VT stems from unclean interfaces, trapped charges in the
underlying substrate, and sulfur vacancies created during the mechanical
exfoliation process. In this study, we demonstrate a simple and reliable oxygen
plasma treatment, which mitigates the effects of unintentional doping created
by surface defect cites, such as S vacancies, and surface contamination. This
plasma treatment restores charge neutrality to the MoS2 and shifts the
threshold turn-on voltage towards 0V. Out of the 8 devices measured, all
exhibit a shift of the FET turn-on voltage from an average of -18.7V to -0.9V.
The oxygen plasma treatment passivates these defects, which reduces surface
scattering, causing increased mobility and improved subthreshold swing. For
as-prepared devices with low mobilities (~0.01cm2/V.s), we observe up to a
190-fold increase in mobility after exposure to the oxygen plasma. Perhaps the
most important aspect of this oxygen plasma treatment is that it reduces the
device-to-device variability, which is a crucial factor in realizing any
practical application of these devices.


title: Realistic DNA De-anonymization using Phenotypic Prediction

abstract:
  There are a number of vectors for attack when trying to link an individual to
a certain DNA sequence. Phenotypic prediction is one such vector; linking DNA
to an individual based on their traits. Current approaches are not overly
effective, due to a number of real world considerations. This report will
improve upon current phenotypic prediction, and suggest a number of methods for
defending against such an attack.


title:
Cascading Node Failure with Continuous States in Random Geometric
  Networks

abstract:
  The increasing complexity and interdependency of today's networks highlight
the importance of studying network robustness to failure and attacks. Many
large-scale networks are prone to cascading effects where a limited number of
initial failures (due to attacks, natural hazards or resource depletion)
propagate through a dependent mechanism, ultimately leading to a global failure
scenario where a substantial fraction of the network loses its functionality.
These cascading failure scenarios often take place in networks which are
embedded in space and constrained by geometry. Building on previous results on
cascading failure in random geometric networks, we introduce and analyze a
continuous cascading failure model where a node has an initial
continuously-valued state, and fails if the aggregate state of its neighbors
fall below a threshold. Within this model, we derive analytical conditions for
the occurrence and non-occurrence of cascading node failure, respectively.


title: Genomic data analysis in tree spaces

abstract:
  Recently, an elegant approach in phylogenetics was introduced by
Billera-Holmes-Vogtmann that allows a systematic comparison of different
evolutionary histories using the metric geometry of tree spaces. In many
problem settings one encounters heavily populated phylogenetic trees, where the
large number of leaves encumbers visualization and analysis in the relevant
evolutionary moduli spaces. To address this issue, we introduce tree
dimensionality reduction, a structured approach to reducing large phylogenetic
trees to a distribution of smaller trees. We prove a stability theorem ensuring
that small perturbations of the large trees are taken to small perturbations of
the resulting distributions.
  We then present a series of four biologically motivated applications to the
analysis of genomic data, spanning cancer and infectious disease. The first
quantifies how chemotherapy can disrupt the evolution of common leukemias. The
second examines a link between geometric information and the histologic grade
in relapsed gliomas, where longer relapse branches were specific to high grade
glioma. The third concerns genetic stability of xenograft models of cancer,
where heterogeneity at the single cell level increased with later mouse
passages. The last studies genetic diversity in seasonal influenza A virus. We
apply tree dimensionality reduction to 24 years of longitudinally collected
H3N2 hemagglutinin sequences, generating distributions of smaller trees
spanning between three and five seasons. A negative correlation is observed
between the influenza vaccine effectiveness during a season and the variance of
the distributions produced using preceding seasons' sequence data. We also show
how tree distributions relate to antigenic clusters and choice of influenza
vaccine. Our formalism exposes links between viral genomic data and clinical
observables such as vaccine selection and efficacy.


title:
Verso folio: Diversified Ranking for Large Graphs with Context-Aware
  Considerations

abstract:
  This work is pertaining to the diversified ranking of web-resources and
interconnected documents that rely on a network-like structure, e.g. web-pages.
A practical example of this would be a query for the k most relevant web-pages
that are also in the same time as dissimilar with each other as possible.
Relevance and dissimilarity are quantified using an aggregation of network
distance and context similarity. For example, for a specific configuration of
the problem, we might be interested in web-pages that are similar with the
query in terms of their textual description but distant from each other in
terms of the web-graph, e.g. many clicks away. In retrospect, a dearth of work
can be found in the literature addressing this problem taking the network
structure formed by the document links into consideration.
  In this work, we propose a hill-climbing approach that is seeded with a
document collection which is generated using greedy heuristics to diversify
initially. More importantly, we tackle the problem in the context of web-pages
where there is an underlying network structure connecting the available
documents and resources. This is a significant difference to the majority of
works that tackle the problem in terms of either content definitions, or the
graph structure of the data, but never addressing both aspects simultaneously.
To the best of our knowledge, this is the very first effort that can be found
to combine both aspects of this important problem in an elegant fashion by also
allowing a great degree of flexibility on how to configure the trade-offs of
(i) document relevance over result-items' dissimilarity, and (ii) network
distance over content relevance or dissimilarity. Last but not least, we
present an extensive evaluation of our methods that demonstrate the
effectiveness and efficiency thereof.


title:
Nielsen Identity and the Renormalization Group Functions in an Abelian
  Supersymmetric Chern-Simons Model in the Superfield Formalism

abstract:
  In this paper we study the Nielsen identity for the supersymmetric
Chern-Simons-matter model in the superfield formalism, in three spacetime
dimensions. The Nielsen identity is essential to understand the gauge
invariance of the symmetry breaking mechanism, and it is calculated by using
the BRST invariance of the model. We discuss the technical difficulties in
applying this identity to the complete effective superpotential, but we show
how we can study in detail the gauge independence of one part of the effective
superpotential, $K_{eff}$. We calculate the renormalization group functions of
the model for arbitrary gauge-fixing parameter, finding them to be independent
of the gauge choice. This result can be used to argue that $K_{eff}$ also does
not depend on the gauge parameter. We discuss the possibility of the extension
of these results to the complete effective superpotential.


title: Deriving covariant holographic entanglement

abstract:
  We provide a gravitational argument in favour of the covariant holographic
entanglement entropy proposal. In general time-dependent states, the proposal
asserts that the entanglement entropy of a region in the boundary field theory
is given by a quarter of the area of a bulk extremal surface in Planck units.
The main element of our discussion is an implementation of an appropriate
Schwinger-Keldysh contour to obtain the reduced density matrix (and its powers)
of a given region, as is relevant for the replica construction. We map this
contour into the bulk gravitational theory, and argue that the saddle point
solutions of these replica geometries lead to a consistent prescription for
computing the field theory Renyi entropies. In the limiting case where the
replica index is taken to unity, a local analysis suffices to show that these
saddles lead to the extremal surfaces of interest. We also comment on various
properties of holographic entanglement that follow from this construction.


title:
CLT for Lipschitz-Killing curvatures of excursion sets of Gaussian
  fields

abstract:
  Our interest in this paper is to explore limit theorems for various geometric
functionals of excursion sets of isotropic Gaussian random fields. In the past,
limit theorems have been proven for various geometric functionals of excursion
sets/sojourn times. Most recently a CLT for Euler-Poincar\'e characteristic of
the excursions set of a Gaussian random field has been proven under appropriate
conditions. In this paper, we shall obtain a central limit theorem for some
global geometric functionals, called the Lipschitz-Killing curvatures of
excursion sets of Gaussian random fields in an appropriate setting.


title: Offline Delay-Optimal Transmission for Energy Harvesting Nodes

abstract:
  This paper investigates the offline packet-delay-minimization problem for an
energy harvesting transmitter. To overcome the non-convexity of the problem, we
propose a C2-diffeomorphic transformation and provide the necessary and
sufficient condition for the transformed problem to a standard convex
optimization problem. Based on this condition, a simple choice of the
transformation is determined which allows an analytically tractable solution of
the original non-convex problem to be easily obtained once the transformed
convex problem is solved. We further study the structure of the optimal
transmission policy in a special case and find it to follow a
weighted-directional-water-filling structure. In particular, the optimal policy
tends to allocate more power in earlier time slots and less power in later time
slots. Our analytical insight is verified by simulation results.


title:
Goto's deformation theory of geometric structures, a Lie-theoretical
  description

abstract:
  In \cite{Goto}, Ryushi Goto has constructed the deformation space for a
manifold equipped with a collection of closed differential forms and showed
that in some important cases (Calabi-Yau, $G_2$- and $Spin(7)$-structures) this
deformation space is smooth. This result unifies the classical
Bogomolov-Tian-Todorov and Joyce theorems about unobstructedness of
deformations. Using the work of Fiorenza and Manetti, we show that this
deformation space could be obtained as the deformation space associated to a
certain $L_{\infty}$-algebra. We also show that for Calabi-Yau, $G_2$- and
$Spin(7)$-structures this $L_{\infty}$-algebra is homotopy abelian. This gives
a new proof of Goto's theorem.


title: The Rank Effect for Commodities

abstract:
  We uncover a large and significant low-minus-high rank effect for commodities
across two centuries. There is nothing anomalous about this anomaly, nor is it
clear how it can be arbitraged away. Using nonparametric econometric methods,
we demonstrate that such a rank effect is a necessary consequence of a
stationary relative asset price distribution. We confirm this prediction using
daily commodity futures prices and show that a portfolio consisting of
lower-ranked, lower-priced commodities yields 23% higher annual returns than a
portfolio consisting of higher-ranked, higher-priced commodities. These excess
returns have a Sharpe ratio nearly twice as high as the U.S. stock market yet
are uncorrelated with market risk. In contrast to the extensive literature on
asset pricing factors and anomalies, our results are structural and rely on
minimal and realistic assumptions for the long-run behavior of relative asset
prices.


title:
Theory of complex fluids in the warm-dense-matter regime, and
  application to an unusual phase-transitions in liquid carbon

abstract:
  Data from recent laser-shock experiments, density-functional theory (DFT)
with molecular-dynamics (MD), and path-integral Monte Carlo (PIMC) simulations
on carbon are compared with predictions from the neutral-pseudo-atom (NPA)+
hyper-netted-chain (HNC) approach for carbon, a complex liquid in the
warm-dense matter regime. The NPA results are in good agreement, not only with
high-density regimes that have been studies via PIMC, but even at low densities
and low temperatures where transient covalent bonding dominates ionic
correlations. Thus the `pre-peak' due to the C-C bond at $\sim$1.4-1.6 \AA$\,$
and other features found in the pair-distribution function from DFT+MD
simulations at 0.86 eV and 3.7 g/cm$^3$ etc., are recovered accurately in the
NPA+HNC calculations. Such C-C bonding peaks have not been captured via
average-atom ion-sphere (IS) models. Evidence for an unusual liquid $\to$ vapor
and metal$\to$ semi-metal transition occurring simultaneously is presented.
Here a strongly correlated metallic-liquid with transient C-C bonds, i.e.,
carbon at density $\sim$ 1.0 g/cm$^3$ and mean ionization $Z=4$ transits
abruptly to a disordered mono-atomic vapour at 7 eV, with $Z\simeq$ 3. Other
cases where $Z$ drops abruptly are also noted. The nature of $Z$, its
discontinuities, and the role of exchange correlation, are reviewed. The
limitations of IS models in capturing the physics of transient covalent bonding
in warm dense matter are discussed.


title:
Quantitative Factorization of weakly compact, Rosenthal, and
  $\xi$-Banach-Saks operators

abstract:
  We prove quantitative factorization results for several classes of operators,
including weakly compact, Rosenthal, and $\xi$-Banach-Saks operators.


title: Quantum Defect Theory for Orbital Feshbach Resonance

abstract:
  In the ultracold gases of alkali-earth (like) atoms, a new type of Feshbach
resonance, i.e., the orbital Feshbach resonance (OFR), has been proposed and
experimentally observed in ultracold $^{173}$Yb atoms. When the OFR of the
$^{173}$Yb atoms occurs, the energy gap between the open and closed channels is
smaller by two orders of magnitudes than the van der Waals energy. As a result,
quantitative accurate results for the low-energy two-body problems can be
obtained via multi-channel quantum defect theory (MQDT), which is based on the
exact solution of the Schr$\ddot{{\rm o}}$dinger equation with the van der
Waals potential. In this paper we use the MQDT to calculate the two-atom
scattering length, effective range, and the binding energy of two-body bound
states for the systems with OFR. With these results we further study the
clock-transition spectrum for the two-body bound states, which can be used to
experimentally measure the binding energy. Our results are helpful for the
quantitative theoretical and experimental researches for the ultracold gases of
alkali-earth (like) atoms with OFR.


title:
Tweet2Vec: Learning Tweet Embeddings Using Character-level CNN-LSTM
  Encoder-Decoder

abstract:
  We present Tweet2Vec, a novel method for generating general-purpose vector
representation of tweets. The model learns tweet embeddings using
character-level CNN-LSTM encoder-decoder. We trained our model on 3 million,
randomly selected English-language tweets. The model was evaluated using two
methods: tweet semantic similarity and tweet sentiment categorization,
outperforming the previous state-of-the-art in both tasks. The evaluations
demonstrate the power of the tweet embeddings generated by our model for
various tweet categorization tasks. The vector representations generated by our
model are generic, and hence can be applied to a variety of tasks. Though the
model presented in this paper is trained on English-language tweets, the method
presented can be used to learn tweet embeddings for different languages.


title:
Single Stage Prediction with Embedded Topic Modeling of Online Reviews
  for Mobile App Management

abstract:
  Mobile apps are one of the building blocks of the mobile digital economy. A
differentiating feature of mobile apps to traditional enterprise software is
online reviews, which are available on app marketplaces and represent a
valuable source of consumer feedback on the app. We create a supervised topic
modeling approach for app developers to use mobile reviews as useful sources of
quality and customer feedback, thereby complementing traditional software
testing. The approach is based on a constrained matrix factorization that
leverages the relationship between term frequency and a given response variable
in addition to co-occurrences between terms to recover topics that are both
predictive of consumer sentiment and useful for understanding the underlying
textual themes. The factorization is combined with ordinal regression to
provide guidance from online reviews on a single app's performance as well as
systematically compare different apps over time for benchmarking of features
and consumer sentiment. We apply our approach using a dataset of over 100,000
mobile reviews over several years for three of the most popular online travel
agent apps from the iTunes and Google Play marketplaces.


title: Quantum Advantage on Information Leakage for Equality

abstract:
  We prove a lower bound on the information leakage of any classical protocol
computing the equality function in the simultaneous message passing (SMP)
model. Our bound is valid in the finite length regime and is strong enough to
demonstrate a quantum advantage in terms of information leakage for practical
quantum protocols. We prove our bound by obtaining an improved finite size
version of the communication bound due to Babai and Kimmel, relating randomized
communication to deterministic communication in the SMP model. We then relate
information leakage to randomized communication through a series of reductions.
We first provide alternative characterizations for information leakage,
allowing us to link it to average length communication while allowing for
shared randomness (pairwise, with the referee). A Markov inequality links this
with bounded length communication, and a Newman type argument allows us to go
from shared to private randomness. The only reduction in which we incur more
than a logarithmic additive factor is in the Markov inequality; in particular,
our compression method is essentially tight for the SMP model with average
length communication.


title:
Energy dependence of $J/\psi$ production in Au+Au collisions at
  $\sqrt{s_{NN}} =$ 39, 62.4 and 200 GeV

abstract:
  The inclusive $J/\psi$ transverse momentum ($p_{T}$) spectra and nuclear
modification factors are reported at midrapidity ($|y|<1.0$) in Au+Au
collisions at $\sqrt{s_{NN}}=$ 39, 62.4 and 200 GeV taken by the STAR
experiment. A suppression of $J/\psi$ production, with respect to
{\color{black}the production in $p+p$ scaled by the number of binary
nucleon-nucleon collisions}, is observed in central Au+Au collisions at these
three energies. No significant energy dependence of nuclear modification
factors is found within uncertainties. The measured nuclear modification
factors can be described by model calculations that take into account both
suppression of direct $J/\psi$ production due to the color screening effect and
$J/\psi$ regeneration from recombination of uncorrelated charm-anticharm quark
pairs.


title:
Target and Beam-Target Spin Asymmetries in Exclusive Pion
  Electroproduction for $Q^2>1$ GeV$^2$. I. $e p \rightarrow e \pi^+ n$

abstract:
  Beam-target double-spin asymmetries and target single-spin asymmetries were
measured for the exclusive $\pi^+$ electroproduction reaction $\gamma^* p \to n
\pi^+$. The results were obtained from scattering of 6 GeV longitudinally
polarized electrons off longitudinally polarized protons using the CEBAF Large
Acceptance Spectrometer at Jefferson Lab. The kinematic range covered is
$1.1<W<3$ GeV and $1<Q^2<6$ GeV$^2$. Results were obtained for about 6000 bins
in $W$, $Q^2$, $\cos(\theta^*)$, and $\phi^*$. Except at forward angles, very
large target-spin asymmetries are observed over the entire $W$ region.
Reasonable agreement is found with phenomenological fits to previous data for
$W<1.6$ GeV, but very large differences are seen at higher values of $W$. A
GPD-based model is in poor agreement with the data. When combined with cross
section measurements, the present results provide powerful constraints on
nucleon resonance amplitudes at moderate and large values of $Q^2$, for
resonances with masses as high as 2.4 GeV.


title: Deepr: A Convolutional Net for Medical Records

abstract:
  Feature engineering remains a major bottleneck when creating predictive
systems from electronic medical records. At present, an important missing
element is detecting predictive regular clinical motifs from irregular episodic
records. We present Deepr (short for Deep record), a new end-to-end deep
learning system that learns to extract features from medical records and
predicts future risk automatically. Deepr transforms a record into a sequence
of discrete elements separated by coded time gaps and hospital transfers. On
top of the sequence is a convolutional neural net that detects and combines
predictive local clinical motifs to stratify the risk. Deepr permits
transparent inspection and visualization of its inner working. We validate
Deepr on hospital data to predict unplanned readmission after discharge. Deepr
achieves superior accuracy compared to traditional techniques, detects
meaningful clinical motifs, and uncovers the underlying structure of the
disease and intervention space.


title:
Analytic Expression for the Entanglement Entropy of a 2D Topological
  Superconductor

abstract:
  We study a model of two dimensional, topological superconductivity on a
square lattice. The model contains hopping, spin orbit coupling and a time
reversal symmetry breaking Zeeman term. This term, together with the chemical
potential act as knobs that induce transitions between trivial and topological
superconductivity. As previously found numerically, the transitions are seen in
the entanglement entropy as cusps as a function of model parameters. In this
work we study the entanglement entropy analytically by keeping only its most
important components. Our study is based on the intuition that the number of
Fermi surfaces in the system controls the topological invariant. With our
approximate expression for the entanglement entropy we are able to extract the
divergent entanglement entropy derivative close to the phase transition.


title:
Propensity score weighting for causal inference with multi-stage
  clustered data

abstract:
  Propensity score weighting is a tool for causal inference to adjust for
measured confounders. Survey data are often collected under complex sampling
designs such as multistage cluster sampling, which presents challenges for
propensity score modeling and estimation. In addition, for clustered data,
there may also be unobserved cluster effects related to both the treatment and
the outcome. When such unmeasured confounders exist and are omitted in the
propensity score model, the subsequent propensity score adjustment will be
biased. We propose a calibrated propensity score weighting adjustment for
multi-stage clustered data in the presence of unmeasured cluster-level
confounders. The propensity score is calibrated to balance design-weighted
covariate distributions and cluster effects between treatment groups. In
particular, we consider a growing number of calibration constraints increasing
with the number of clusters, which is necessary for removing asymptotic bias
that is associated with the unobserved cluster-level confounders. We show that
our estimator is robust in the sense that the estimator is consistent without
correct specification of the propensity score model. We extend the results to
the multiple treatments case. In simulation studies we show that the proposed
estimator is superior to other competitors. We estimate the effect of School
Body Mass Index Screening on prevalence of overweight and obesity for
elementary schools in Pennsylvania.


title: Minimum rank and zero forcing number for butterfly networks

abstract:
  The minimum rank of a simple graph $G$ is the smallest possible rank over all
symmetric real matrices $A$ whose nonzero off-diagonal entries correspond to
the edges of $G$. Using the zero forcing number, we prove that the minimum rank
of the butterfly network is $\frac19\left[(3r+1)2^{r+1}-2(-1)^r\right]$ and
that this is equal to the rank of its adjacency matrix.


title:
Numerical Fokker-Planck study of stochastic write error slope in spin
  torque switching

abstract:
  This paper analyzes write errors in spin torque switching due to thermal
fluctuations in a system with Perpendicular Magnetic Anisotropy (PMA). Prior
analytical and numerical methods are summarized, a physics based Fokker-Planck
Equation (FPE) chosen for its computational efficiency and broad applicability
to all switching regimes. The relation between write error slope and material
parameters is discussed in detail to enable better device engineering and
optimization. Finally a 2D FPE tool is demonstrated that extends the
applicability of FPE to write error in non PMA systems with built-in asymmetry.


title:
Universal spatiotemporal dynamics of spontaneous superfluidity breakdown
  in the presence of synthetic gauge fields

abstract:
  According to the famous Kibble-Zurek mechanism (KZM), the universality of
spontaneous defect generation in continuous phase transitions (CPTs) can be
understood by the critical slowing down. In most CPTs of atomic Bose-Einstein
condensates (BECs), the universality of spontaneous defect generations has been
explained by the divergent relaxation time associated with the nontrivial
gapless Bogoliubov excitations. However, for atomic BECs in synthetic gauge
fields, their spontaneous superfluidity breakdown is resulted from the
divergent correlation length associated with the zero Landau critical velocity.
Here, by considering an atomic BEC ladder subjected to a synthetic magnetic
field, we reveal that the spontaneous superfluidity breakdown obeys the KZM.
The Kibble-Zurek scalings are derived from the Landau critical velocity which
determines the correlation length. In further, the critical exponents are
numerically extracted from the critical spatial-temporal dynamics of the
bifurcation delay and the spontaneous vortex generation. Our study provides a
general way to explore and understand the spontaneous superfluidity breakdown
in CPTs from a single-well dispersion to a double-well one, such as, BECs in
synthetic gauge fields, spin-orbit coupled BECs, and BECs in shaken optical
lattices.


title: Salient Object Subitizing

abstract:
  We study the problem of Salient Object Subitizing, i.e. predicting the
existence and the number of salient objects in an image using holistic cues.
This task is inspired by the ability of people to quickly and accurately
identify the number of items within the subitizing range (1-4). To this end, we
present a salient object subitizing image dataset of about 14K everyday images
which are annotated using an online crowdsourcing marketplace. We show that
using an end-to-end trained Convolutional Neural Network (CNN) model, we
achieve prediction accuracy comparable to human performance in identifying
images with zero or one salient object. For images with multiple salient
objects, our model also provides significantly better than chance performance
without requiring any localization process. Moreover, we propose a method to
improve the training of the CNN subitizing model by leveraging synthetic
images. In experiments, we demonstrate the accuracy and generalizability of our
CNN subitizing model and its applications in salient object detection and image
retrieval.


title: On the Resistance of Nearest Neighbor to Random Noisy Labels

abstract:
  Nearest neighbor has always been one of the most appealing non-parametric
approaches in machine learning, pattern recognition, computer vision, etc.
Previous empirical studies partly shows that nearest neighbor is resistant to
noise, yet there is a lack of deep analysis. This work presents the
finite-sample and distribution-dependent bounds on the consistency of nearest
neighbor in the random noise setting. The theoretical results show that, for
asymmetric noises, k-nearest neighbor is robust enough to classify most data
correctly, except for a handful of examples, whose labels are totally misled by
random noises. For symmetric noises, however, k-nearest neighbor achieves the
same consistent rate as that of noise-free setting, which verifies the
resistance of k-nearest neighbor to random noisy labels. Motivated by the
theoretical analysis, we propose the Robust k-Nearest Neighbor (RkNN) approach
to deal with noisy labels. The basic idea is to make unilateral corrections to
examples, whose labels are totally misled by random noises, and classify the
others directly by utilizing the robustness of k-nearest neighbor. We verify
the effectiveness of the proposed algorithm both theoretically and empirically.


title:
Vanishing cycles of smoothable isolated Cohen-Macaulay codimension 2
  singularities of type 2

abstract:
  We extend the results from the previous paper by A. Fr\"uhbis-Kr\"uger and
the author [arXiv:1501.01915] to the vanishing topology of those singularities
in the title. Studying the case of possibly non-isolated singularities in the
Tjurina- transform, we reveal that in dimension 3 and 2 there always is exactly
one special vanishing cycle in degree 2 closely related to the determinantal
structure of the singularity.


title: Carbon-to-Oxygen Ratios in M dwarfs and Solar-type stars

abstract:
  Initial C/O ratios of circumstellar disks have been obtained in solar-type
stars by differential photospheric abundance analysis with respect to the Sun.
We present C/O ratios of M dwarfs obtained by absolute abundance analysis
derived from CO and H2O spectra in the K-band. We compare the distributions of
C/O ratios in M dwarfs and solar-type stars using the Kolmogorov-Smirnov test.
The C/O distribution of M dwarfs is consistent with low frequency of high C/O
ratios in solar-type stars.


title:
A bound for the index of a quadratic form after scalar extension to the
  function field of a quadric

abstract:
  Let $q$ be an anisotropic quadratic form defined over a general field $F$. In
this article, we formulate a new upper bound for the isotropy index of $q$
after scalar extension to the function field of an arbitrary quadric. On the
one hand, this bound offers a refinement of a celebrated bound established in
earlier work of Karpenko-Merkurjev and Totaro; on the other, it is a direct
generalization of Karpenko's theorem on the possible values of the first higher
isotropy index. We prove its validity in two important cases: (i) the case
where $\mathrm{char}(F) \neq 2$, and (ii) the case where $\mathrm{char}(F) = 2$
and $q$ is quasilinear (i.e., diagonalizable). The two cases are treated
separately using completely different approaches, the first being
algebraic-geometric, and the second being purely algebraic.


title:
On Tensor Products of a Minimal Affinization with an Extreme
  Kirillov-Reshetikhin Module for type A

abstract:
  For a quantum affine algebra of type A, we describe the composition series of
the tensor product of a general minimal affinization with a
Kirillov-Resehtikhin module associated to an extreme node of the Dynkin diagram
of the underlying simple Lie algebra.


title: Why is a flare-rich active region CME-poor?

abstract:
  Solar active regions (ARs) are the major sources of two kinds of the most
violent solar eruptions, namely flares and coronal mass ejections (CMEs). The
largest AR in the past 24 years, NOAA AR 12192, crossed the visible disk from
2014 October 17 to 30, unusually produced more than one hundred flares,
including 32 M-class and 6 X-class ones, but only one small CME. Flares and
CMEs are believed to be two phenomena in the same eruptive process. Why is such
a flare-rich AR so CME-poor? We compared this AR with other four ARs; two were
productive in both and two were inert. The investigation of the photospheric
parameters based on the SDO/HMI vector magnetogram reveals that the flare-rich
AR 12192, as the other two productive ARs, has larger magnetic flux, current
and free magnetic energy than the two inert ARs, but contrast to the two
productive ARs, it has no strong, concentrated current helicity along both
sides of the flaring neutral line, indicating the absence of a mature magnetic
structure consisting of highly sheared or twisted field lines. Furthermore, the
decay index above the AR 12192 is relatively low, showing strong constraint.
These results suggest that productive ARs are always large and have enough
current and free energy to power flares, but whether or not a flare is
accompanied by a CME is seemingly related to (1) if there is mature sheared or
twisted core field serving as the seed of the CME, (2) if the constraint of the
overlying arcades is weak enough.


title: Trigonal curves and algebro-geometric solutions to soliton hierarchies

abstract:
  Using linear combinations of Lax matrices of soliton hierarchies, we
introduce trigonal curves by their characteristic equations, and determine
Dubrovin type equations for zeros and poles of meromorphic functions defined as
ratios of the Baker-Akhiezer functions. We straighten out all flows in soliton
hierarchies under the Abel-Jacobi coordinates associated with Lax pairs, and
generate algebro-geometric solutions to soliton hierarchies in terms of the
Riemann theta functions, through observing asymptotic behaviors of the
Baker-Akhiezer functions. We analyze the four-component AKNS soliton hierarchy
in such a way that it leads to a general theory of trigonal curves applicable
to construction of algebro-geometric solutions of an arbitrary soliton
hierarchy.


title: Stellar equilibrium in Einstein-Chern-Simons gravity

abstract:
  We consider a spherically symmetric internal solution within the context of
Einstein-Chern-Simons gravity and derive a generalized five-dimensional
Tolman-Oppenheimer-Volkoff (TOV) equation. It is shown that the generalized TOV
equation leads, in a certain limit, to the standard five-dimensional TOV
equation


title:
K band SINFONI spectra of two $z \sim 5$ SMGs: upper limits to the
  un-obscured star formation from [O II] optical emission line searches

abstract:
  We present deep SINFONI K band integral field spectra of two submillimeter
(SMG) galaxy systems: BR 1202-0725 and J1000+0234, at $z=4.69$ and $4.55$
respectively. Spectra extracted for each object in the two systems do not show
any signature of the [O II]$\lambda\lambda$3726,29\AA$\,$ emission-lines,
placing upper flux limits of $3.9$ and $2.5 \times 10^{-18}\,$${\rm
erg\,s^{-1}\,\,cm^{-2} \,}$ for BR 1202-0725 and J1000+0234, respectively.
Using the relation between the star formation rate (SFR) and the luminosity of
the [O II] doublet from Kennicutt (1998), we estimate unobscured SFR upper
limits of $\sim$ $10-15\,\rm M_\odot\,yr^{-1} \,$ and $\sim$ $30-40\,\rm
M_\odot\,yr^{-1} \,$ for the objects of the two systems, respectively. For the
SMGs, these values are at least two orders of magnitude lower than those
derived from SED and IR luminosities. The differences on the SFR values would
correspond to internal extinction of, at least, $3.4 - 4.9$ and $2.1 - 3.6$ mag
in the visual for BR 1202-0725 and J1000+0234 SMGs, respectively. The upper
limit for the [O II]-derived SFR in one of the LAEs (Ly$\alpha2$) in the
BR1202-0725 system is at least one order of magnitude lower than the previous
SFR derived from infrared tracers, while both estimates are in good agreement
for Ly$\alpha$1. The lower limits to the internal extinction in these two
Lyman-alpha emitters (LAEs) are $0.6$ mag and $1.3$ mag, respectively. No
evidence for the previously claimed (Ohta et al. 2000) [O II] emission
associated with Ly$\alpha$1 is identified in our data, implying that residuals
of the K-band sky emission lines after subtraction in medium-band imaging data
could provide the adequate flux.


title:
Time-varying formation tracking of multiple manipulators via distributed
  finite-time control

abstract:
  Comparing with traditional fixed formation for a group of dynamical systems,
time-varying formation can produce the following benefits: i) covering the
greater part of complex environments; ii) collision avoidance. This paper
studies the time-varying formation tracking for multiple manipulator systems
(MMSs) under fixed and switching directed graphs with a dynamic leader, whose
acceleration cannot change too fast. An explicit mathematical formulation of
time-varying formation is developed based on the related practical
applications. A class of extended inverse dynamics control algorithms combining
with distributed sliding-mode estimators are developed to address the
aforementioned problem. By invoking finite-time stability arguments, several
novel criteria (including sufficient criteria, necessary and sufficient
criteria) for global finite-time stability of MMSs are established. Finally,
numerical experiments are presented to verify the effectiveness of the
theoretical results.


title: Interface-driven topological Hall effect in SrRuO$_3$-SrIrO$_3$ bilayer

abstract:
  Electron transport coupled with magnetism has attracted attention over the
years as exemplified in anomalous Hall effect due to a Berry phase in momentum
space. Another type of unconventional Hall effect -- topological Hall effect,
originating from the real-space Berry phase, has recently become of great
importance in the context of magnetic skyrmions. We have observed topological
Hall effect in bilayers consisting of ferromagnetic SrRuO$_3$ and paramagnetic
SrIrO$_3$ over a wide region of both temperature and magnetic field. The
topological term rapidly decreases with the thickness of SrRuO$_3$, ending up
with the complete disappearance at 7 unit cells of SrRuO$_3$. Combined with
model calculation, we concluded that the topological Hall effect is driven by
interface Dzyaloshinskii-Moriya interaction, which is caused by both the broken
inversion symmetry and the strong spin-orbit coupling of SrIrO$_3$. Such
interaction is expected to realize the N\'{e}el-type magnetic skyrmion, of
which size is estimated to be $\sim$10 nm from the magnitude of topological
Hall resistivity. The results established that the high-quality oxide interface
enables us to tune the chirality of the system; this can be a step towards the
future topological electronics.


title: Pilot Decontamination via PDP Alignment

abstract:
  In this paper, we look into the issue of intra-cell uplink (UL) pilot
orthogonalization and schemes for mitigating the inter-cell pilot contamination
with a realistic massive multi-input multi-output (MIMO) orthogonal
frequency-division multiplexing (OFDM) system model. First, we show how to
align the power-delay profiles (PDP) of different users served by one BS so
that the pilots sent within one common OFDM symbol are orthogonal. From the
derived aligning rule, we see much more users can be sounded in the same OFDM
symbol as their channels are sparse in time. Second, in the case of massive
MIMO, we show how PDP alignment can help to alleviate the pilot contamination
due to inter-cell interference. We demonstrate that, by utilizing the fact that
different paths in time are associated with different angles of arrival (AoA),
the pilot contamination can be significantly reduced through aligning the PDPs
of the users served by different BSs appropriately. Computer simulations
further convince us PDP aligning can serve as the new baseline design
philosophy for the UL pilots in massive MIMO.


title:
Numerical integration of massive two-loop Mellin-Barnes integrals in
  Minkowskian regions

abstract:
  Mellin-Barnes (MB) techniques applied to integrals emerging in particle
physics perturbative calculations are summarized. New versions of AMBRE
packages which construct planar and nonplanar MB representations are shortly
discussed. The numerical package MBnumerics.m is presented for the first time
which is able to calculate with a high precision multidimensional MB integrals
in Minkowskian regions. Examples are given for massive vertex integrals which
include threshold effects and several scale parameters.


title: Semantic Image Inpainting with Deep Generative Models

abstract:
  Semantic image inpainting is a challenging task where large missing regions
have to be filled based on the available visual data. Existing methods which
extract information from only a single image generally produce unsatisfactory
results due to the lack of high level context. In this paper, we propose a
novel method for semantic image inpainting, which generates the missing content
by conditioning on the available data. Given a trained generative model, we
search for the closest encoding of the corrupted image in the latent image
manifold using our context and prior losses. This encoding is then passed
through the generative model to infer the missing content. In our method,
inference is possible irrespective of how the missing content is structured,
while the state-of-the-art learning based method requires specific information
about the holes in the training phase. Experiments on three datasets show that
our method successfully predicts information in large missing regions and
achieves pixel-level photorealism, significantly outperforming the
state-of-the-art methods.


title: A Dynamical Analysis of the Kepler-80 System of Five Transiting Planets

abstract:
  Kepler has discovered hundreds of systems with multiple transiting exoplanets
which hold tremendous potential both individually and collectively for
understanding the formation and evolution of planetary systems. Many of these
systems consist of multiple small planets with periods less than ~50 days known
as Systems with Tightly-spaced Inner Planets, or STIPs. One especially
intriguing STIP, Kepler-80 (KOI-500), contains five transiting planets: f, d,
e, b, and c with periods of 1.0, 3.1, 4.6, 7.1, 9.5 days, respectively. We
provide measurements of transit times and a transit timing variation (TTV)
dynamical analysis. We find that TTVs cannot reliably detect eccentricities for
this system, though mass estimates are not affected. Restricting the
eccentricity to a reasonable range, we infer masses for the outer four planets
(d, e, b, and c) to be $6.75^{+0.69}_{-0.51}$, $4.13^{+0.81}_{-0.95}$,
$6.93^{+1.05}_{-0.70}$, and $6.74^{+1.23}_{-0.86}$ Earth masses, respectively.
The similar masses but different radii are consistent with terrestrial
compositions for d and e and $\sim$2% H/He envelopes for b and c. We confirm
that the outer four planets are in a rare dynamical configuration with four
interconnected three-body resonances that are librating with few degree
amplitudes. We present a formation model that can reproduce the observed
configuration by starting with a multi-resonant chain and introducing
dissipation. Overall, the information-rich Kepler-80 planets provide an
important perspective into exoplanetary systems.


title:
A new kind of 2D topological insulators BiCN with a giant gap and its
  substrate effects

abstract:
  Based on DFT calculation, we predict that BiCN, i.e., bilayer Bi films
passivated with -CN group, is a novel 2D Bi-based material with highly
thermodynamic stability, and demonstrate that it is also a new kind of 2D TI
with a giant SOC gap (? 1 eV) by direct calculation of the topological
invariant Z2 and obvious exhibition of the helical edge states. Monolayer h-BN
and MoS2 are identified as good candidate substrates for supporting the
nontrivial topological insulating phase of the 2D TI films, since the two
substrates can stabilize and weakly interact with BiCN via van derWaals
interaction and thus hardly affect the electronic properties, especially the
band topology. The topological properties are robust against the strain and
electric field. This may provide a promising platform for realization of novel
topological phases.