title: On the Charm Contribution to the Atmospheric Neutrino Flux

abstract:
  We revisit the estimate of the charm particle contribution to the atmospheric
neutrino flux that is expected to dominate at high energies because long-lived
high-energy pions and kaons interact in the atmosphere before decaying into
neutrinos. We focus on the production of forward charm particles which carry a
large fraction of the momentum of the incident proton. In the case of strange
particles, such a component is familiar from the abundant production of $K^{+}
\Lambda$ pairs. These forward charm particles can dominate the high-energy
atmospheric neutrino flux in underground experiments. Modern collider
experiments have no coverage in the very large rapidity region where charm
forward pair production dominates. Using archival accelerator data as well as
IceCube measurements of atmospheric electron and muon neutrino fluxes, we
obtain an upper limit on forward $\bar{D}^0 \Lambda_c$ pair production and on
the associated flux of high-energy atmospheric neutrinos. We conclude that the
prompt flux may dominate the much-studied central component and represent a
significant contribution to the TeV atmospheric neutrino flux. Importantly, it
cannot accommodate the PeV flux of high-energy cosmic neutrinos, nor the excess
of events observed by IceCube in the 30--200 TeV energy range indicating either
structure in the flux of cosmic accelerators, or a presence of more than one
component in the cosmic flux observed.


title: Classical sheaf cohomology rings on Grassmannians

abstract:
  Let the vector bundle $\mathcal{E}$ be a deformation of the tangent bundle
over the Grassmannian $G(k,n)$. We compute the ring structure of sheaf
cohomology valued in exterior powers of $\mathcal{E}$, also known as the
polymology. This is the first part of a project studying the quantum sheaf
cohomology of Grassmannians with deformations of the tangent bundle, a
generalization of ordinary quantum cohomology rings of Grassmannians. A
companion physics paper [arXiv:1512.08586] describes physical aspects of the
theory, including a conjecture for the quantum sheaf cohomology ring, and
numerous examples.


title: Topological Casimir effect in a quantum LC circuit: real-time dynamics

abstract:
  We study novel contributions to the partition function of the Maxwell system
defined on a small compact manifold ${\mathbb{M}}$ with nontrivial mappings
$\pi_1[U(1)]\cong\mathbb{Z}$. These contributions cannot be described in terms
of conventional physical propagating photons with two transverse polarizations,
and instead emerge as a result of tunneling transitions between topologically
different but physically identical vacuum winding states.\exclude{These new
terms give an extra contribution to the Casimir pressure, yet to be measured.}
We argue that if the same system is considered in the background of a small
external time-dependent E\&M field, then real physical photons will be emitted
from the vacuum, similar to the dynamical Casimir effect (DCE) where photons
are radiated from the vacuum due to time-dependent boundary conditions. The
fundamental technical difficulty for such an analysis is that the radiation of
physical photons on mass shell is inherently a real-time Minkowskian phenomenon
while the vacuum fluctuations interpolating between topological $|k\rangle$
sectors rest upon a Euclidean instanton formulation. We overcome this obstacle
by introducing auxiliary topological fields which allows for a simple
analytical continuation between Minkowski and Euclidean descriptions, and
develop a quantum mechanical technique to compute these effects.
  We also propose an experimental realization of such small effects using a
microwave cavity with appropriate boundary conditions. Finally, we comment on
the possible cosmological implications of this effect.


title: Separating the Universe into the Real and Fake

abstract:
  The separate universe technique provides a means of establishing consistency
relations between short wavelength observables and the long wavelength matter
density fluctuations within which they evolve by absorbing the latter into the
cosmological background. We extend it to cases where non-gravitational forces
introduce a Jeans scale in other species like dynamical dark energy or massive
neutrinos. The technique matches the synchronous gauge matter density
fluctuations to the local expansion using the acceleration equation and
accounts for the temporal nonlocality and scale dependence of the long
wavelength response of small scale matter observables, e.g. the nonlinear power
spectrum, halo abundance and the implied halo bias, and $N$-point correlation
functions. Above the Jeans scale, the local Friedmann equation relates the
expansion to real energy densities and a curvature that is constant in comoving
coordinates. Below the Jeans scale, the curvature evolves and acts like a fake
density component. In all cases, the matter evolution on small scales is
correctly modeled as we illustrate using scalar field dark energy with
adiabatic or isocurvature initial conditions across the Jeans scale set by its
finite sound speed.


title: Anomaly-induced dynamical refringence in strong-field QED

abstract:
  We investigate the impact of the Adler-Bell-Jackiw anomaly on the
nonequilibrium evolution of strong-field quantum electrodynamics (QED) using
real-time lattice gauge theory techniques. For field strengths exceeding the
Schwinger limit for pair production, we encounter a highly absorptive medium
with anomaly-induced dynamical refractive properties. In contrast to earlier
expectations based on equilibrium properties, where net anomalous effects
vanish because of the trivial vacuum structure, we find that out-of-equilibrium
conditions can have dramatic consequences for the presence of quantum currents
with distinctive macroscopic signatures. We observe an intriguing tracking
behavior, where the system spends longest times near collinear field
configurations with maximum anomalous current. Apart from the potential
relevance of our findings for future laser experiments, similar phenomena
related to the chiral magnetic effect are expected to play an important role
for strong QED fields during initial stages of heavy-ion collision experiments.


title:
Wavelet reconstruction of E and B modes for CMB polarisation and cosmic
  shear analyses

abstract:
  We present new methods for mapping the curl-free (E-mode) and divergence-free
(B-mode) components of spin 2 signals using spin directional wavelets. Our
methods are equally applicable to measurements of the polarisation of the
cosmic microwave background (CMB) and the shear of galaxy shapes due to weak
gravitational lensing. We derive pseudo and pure wavelet estimators, where E-B
mixing arising due to incomplete sky coverage is suppressed in wavelet space
using scale- and orientation-dependent masking and weighting schemes. In the
case of the pure estimator, ambiguous modes (which have vanishing curl and
divergence simultaneously on the incomplete sky) are also cancelled. On
simulations, we demonstrate the improvement (i.e., reduction in leakage)
provided by our wavelet space estimators over standard harmonic space
approaches. Our new methods can be directly interfaced in a coherent and
computationally-efficient manner with component separation or feature
extraction techniques that also exploit wavelets.


title: Detecting gravitational-wave memory with LIGO: implications of GW150914

abstract:
  It may soon be possible for Advanced LIGO to detect hundreds of binary black
hole mergers per year. We show how the accumulation of many such measurements
will allow for the detection of gravitational-wave memory: a permanent
displacement of spacetime that comes from strong-field, general relativistic
effects. We estimate that Advanced LIGO operating at design sensitivity may be
able to make a signal-to-noise ratio 3(5) detection of memory with ~35 (90)
events with masses and distance similar to GW150914. We highlight the
importance of incorporating higher-order gravitational-wave modes for parameter
estimation of binary black hole mergers, and describe how our methods can also
be used to detect higher-order modes themselves before Advanced LIGO reaches
design sensitivity.


title:
Dissecting Jets and Missing Energy Searches Using $n$-body Extended
  Simplified Models

abstract:
  Simplified Models are a useful way to characterize new physics scenarios for
the LHC. Particle decays are often represented using non-renormalizable
operators that involve the minimal number of fields required by symmetries.
Generalizing to a wider class of decay operators allows one to model a variety
of final states. This approach, which we dub the $n$-body extension of
Simplified Models, provides a unifying treatment of the signal phase space
resulting from a variety of signals. In this paper, we present the first
application of this framework in the context of multijet plus missing energy
searches. The main result of this work is a global performance study with the
goal of identifying which set of observables yields the best discriminating
power against the largest Standard Model backgrounds for a wide range of signal
jet multiplicities. Our analysis compares combinations of one, two and three
variables, placing emphasis on the enhanced sensitivity gain resulting from
non-trivial correlations. Utilizing boosted decision trees, we compare and
classify the performance of missing energy, energy scale and energy structure
observables. We demonstrate that including an observable from each of these
three classes is required to achieve optimal performance. This work
additionally serves to establish the utility of $n$-body extended Simplified
Models as a diagnostic for unpacking the relative merits of different search
strategies, thereby motivating their application to new physics signatures
beyond jets and missing energy.


title: Spin-SILC: CMB polarisation component separation with spin wavelets

abstract:
  We present Spin-SILC, a new foreground component separation method that
accurately extracts the cosmic microwave background (CMB) polarisation $E$ and
$B$ modes from raw multifrequency Stokes $Q$ and $U$ measurements of the
microwave sky. Spin-SILC is an internal linear combination method that uses
spin wavelets to analyse the spin-2 polarisation signal $P = Q + iU$. The
wavelets are additionally directional (non-axisymmetric). This allows different
morphologies of signals to be separated and therefore the cleaning algorithm is
localised using an additional domain of information. The advantage of spin
wavelets over standard scalar wavelets is to simultaneously and
self-consistently probe scales and directions in the polarisation signal $P = Q
+ iU$ and in the underlying $E$ and $B$ modes, therefore providing the ability
to perform component separation and $E$-$B$ decomposition concurrently for the
first time. We test Spin-SILC on full-mission Planck simulations and data and
show the capacity to correctly recover the underlying cosmological $E$ and $B$
modes. We also demonstrate a strong consistency of our CMB maps with those
derived from existing component separation methods. Spin-SILC can be combined
with the pseudo- and pure $E$-$B$ spin wavelet estimators presented in a
companion paper to reliably extract the cosmological signal in the presence of
complicated sky cuts and noise. Therefore, it will provide a
computationally-efficient method to accurately extract the CMB $E$ and $B$
modes for future polarisation experiments.


title: A Sampling Kaczmarz-Motzkin Algorithm for Linear Feasibility

abstract:
  We combine two iterative algorithms for solving large-scale systems of linear
inequalities, the relaxation method of Agmon, Motzkin et al. and the randomized
Kaczmarz method. In doing so, we obtain a family of algorithms that generalize
and extend both techniques. We prove several convergence results, and our
computational experiments show our algorithms often outperform the original
methods.


title: Green's Function for the Quartic Oscillator

abstract:
  In this paper, a quantum mechanical Green's function $G_{qo}(y_b,t_b;$
$y_a,t_a)$ for the quartic oscillator is presented. This result is built upon
two previous papers: first [1], detailing the linearization of the quartic
oscillator $(qo)$ to the harmonic oscillator $(ho)$, second [2], the
integration of the classical action function for the quartic oscillator. Here
an equivalent form for the quartic oscillator action function $S_{qo}(y_b,t_b;$
$y_a,t_a)$ in terms of harmonic oscillator variables is derived in order to
facilitate the derivation of the quartic oscillator Green's Function amplitude.
Thus, the papers [1] and [2] and this paper, taken together, result in the
incorporation of the quartic oscillator into the non-relativistic quantum
mechanical physics literature consisting of those single particle systems whose
properties are described in terms of trig functions, their quadratures or both.


title: Uncertainty relations and approximate quantum error correction

abstract:
  The uncertainty principle can be understood as constraining the probability
of winning a game in which Alice measures one of two conjugate observables,
such as position or momentum, on a system provided by Bob, and he is to guess
the outcome. Two variants are possible: either Alice tells Bob which observable
she measured, or he has to furnish guesses for both cases. Here I derive new
uncertainty relations for both, formulated directly in terms of Bob's guessing
probabilities. For the former these relate to the entanglement that can be
recovered by action on Bob's system alone. This gives a condition for
approximate quantum error correction in terms of the recoverability of
"amplitude" and "phase" information, implicitly used in the recent construction
of efficient quantum polar codes. I also find a tight relation on the guessing
probabilities for the latter game, which has application to wave-particle
duality relations.


title:
SimInf: An R package for Data-driven Stochastic Disease Spread
  Simulations

abstract:
  We present the R package SimInf which provides an efficient and very flexible
framework to conduct data-driven epidemiological modeling in realistic large
scale disease spread simulations. The framework integrates infection dynamics
in subpopulations as continuous-time Markov chains using the Gillespie
stochastic simulation algorithm and incorporates available data such as births,
deaths and movements as scheduled events at predefined time-points. Using C
code for the numerical solvers and OpenMP to divide work over multiple
processors ensures high performance when simulating a sample outcome. One of
our design goal was to make SimInf extendable and enable usage of the numerical
solvers from other R extension packages in order to facilitate complex
epidemiological research. In this paper, we provide a technical description of
the framework and demonstrate its use on some basic examples. We also discuss
how to specify and extend the framework with user-defined models.


title:
Ubiquitous giant Ly $\alpha$ nebulae around the brightest quasars at
  $z\sim3.5$ revealed with MUSE

abstract:
  Direct Ly $\alpha$ imaging of intergalactic gas at $z\sim2$ has recently
revealed giant cosmological structures around quasars, e.g. the Slug Nebula
(Cantalupo et al. 2014). Despite their high luminosity, the detection rate of
such systems in narrow-band and spectroscopic surveys is less than 10%,
possibly encoding crucial information on the distribution of gas around quasars
and the quasar emission properties. In this study, we use the MUSE
integral-field instrument to perform a blind survey for giant Ly $\alpha$
nebulae around 17 bright radio-quiet quasars at $3<z<4$ that does not suffer
from most of the limitations of previous surveys. After data reduction and
analysis performed with specifically developed tools, we found that each quasar
is surrounded by giant Ly $\alpha$ nebulae with projected sizes larger than 100
physical kpc and, in some cases, extending up to 320 kpc. The circularly
averaged surface brightness profiles of the nebulae appear very similar to each
other despite their different morphologies and are consistent with power laws
with slopes $\approx-1.8$. The similarity between the properties of all these
nebulae and the Slug Nebula suggests a similar origin for all systems and that
a large fraction of gas around bright quasars could be in a relatively "cold"
(T$\sim$10$^4$K) and dense phase. In addition, our results imply that such gas
is ubiquitous within at least 50 kpc from bright quasars at $3<z<4$
independently of the quasar emission opening angle, or extending up to 200 kpc
for quasar isotropic emission.


title: Emergent Order in the Kagome Ising Magnet Dy3Mg2Sb3O14

abstract:
  The kagome lattice -- a two-dimensional (2D) arrangement of corner-sharing
triangles -- is at the forefront of the search for exotic states generated by
magnetic frustration. Such states have been observed experimentally for
Heisenberg and planar spins. In contrast, frustration of Ising spins on the
kagome lattice has previously been restricted to nano-fabricated systems and
spin-ice materials under applied magnetic field. Here, we show that the layered
Ising magnet Dy3Mg2Sb3O14 hosts an emergent order predicted theoretically for
individual kagome layers of in-plane Ising spins. Neutron-scattering and bulk
thermomagnetic measurements, supported by Monte Carlo simulations, reveal a
phase transition at T* = 0.3 K from a disordered spin-ice like regime to an
"emergent charge ordered" state in which emergent charge degrees of freedom
exhibit three-dimensional order while spins remain partially disordered. Our
results establish Dy3Mg2Sb3O14 as a tuneable system to study interacting
emergent charges arising from kagome Ising frustration.


title: Coded Caching for Networks with the Resolvability Property

abstract:
  Coded caching is a recently proposed technique for dealing with large scale
content distribution over the Internet. As in conventional caching, it
leverages the presence of local caches at the end users. However, it considers
coding in the caches and/or coded transmission from the central server and
demonstrates that huge savings in transmission rate are possible when the
server and the end users are connected via a single shared link. In this work,
we consider a more general topology where there is a layer of relay nodes
between the server and the users, e.g., combination networks studied in network
coding are an instance of these networks. We propose novel schemes for a class
of such networks that satisfy a so-called resolvability property and
demonstrate that the performance of our scheme is strictly better than
previously proposed schemes.


title: Solutions of quasianalytic equations

abstract:
  The article develops techniques for solving equations G(x,y)=0, where
G(x,y)=G(x_1,...,x_n,y) is a function in a given quasianalytic class (for
example, a quasianalytic Denjoy-Carleman class, or the class of infinitely
differentiable functions definable in a polynomially-bounded o-minimal
structure). We show that, if G(x,y)=0 has a formal power series solution y=H(x)
at some point a, then H is the Taylor expansion at a of a quasianalytic
solution y=h(x), where h(x) is allowed to have a certain controlled loss of
regularity, depending on G. Several important questions on quasianalytic
functions, concerning division, factorization, Weierstrass preparation, etc.,
fall into the framework of this problem (or are closely related), and are also
discussed.


title: Sporadic SICs and the Normed Division Algebras

abstract:
  Recently, Zhu classified all the SIC-POVMs whose symmetry groups act doubly
transitively. Lattices of integers in the complex numbers, the quaternions and
the octonions yield the key parts of these symmetry groups.


title: Drive Dependence of the Skyrmion Hall Effect in Disordered Systems

abstract:
  Using a particle-based simulation model, we show that quenched disorder
creates a drive-dependent skyrmion Hall effect as measured by the change in the
ratio $R=V_{\perp}/V_{||}$ of the skyrmion velocity perpendicular ($V_{\perp}$)
and parallel ($V_{||}$) to an external drive. $R$ is zero at depinning and
increases linearly with increasing drive, in agreement with recent experimental
observations. At sufficiently high drives where the skyrmions enter a free flow
regime, $R$ saturates to the disorder-free limit. This behavior is robust for a
wide range of disorder strengths and intrinsic Hall angle values, and occurs
whenever plastic flow is present. For systems with small intrinsic Hall angles,
we find that the Hall angle increases linearly with external drive, as also
observed in experiment. In the weak pinning regime where the skyrmion lattice
depins elastically, $R$ is nonlinear and the net direction of the skyrmion
lattice motion can rotate as a function of external drive.


title:
Investigation of the Thermoelectric Properties of ZnV$_{2}$O$_{4}$
  Compound in High Temperature Region

abstract:
  In the present work, we report the experimental thermopower ($\alpha$) data
for ZnV$_{2}$O$_{4}$ compound in the high temperature range 300-600 K. The
value of $\alpha$ is found to be $\sim$184 and $\sim$126 $\mu$V/K at $\sim$300
and $\sim$600 K, respectively. The temperature dependent behavior of $\alpha$
is almost linear in the measured temperature range. To understand the large and
positive $\alpha$ value observed in this compound, we have also investigated
the electronic and thermoelectric properties by combining the
\textit{ab-initio} electronic structures calculations with Boltzmann transport
theory. Within the local spin density approximation plus Hubbard U, the
anti-ferromagnetic ground state calculation gives an energy gap $\sim$0.33 eV
for U=3.7 eV, which is in accordance with the experimental results. The
effective mass for holes in the valance band is found nearly four times that of
electrons in conduction band. The large effective mass of holes are mainly
responsible for the observed positive and large $\alpha$ value in this
compound. There is reasonably good matching between calculated and experimental
$\alpha$ data in the temperature range 300-410 K. The power factor calculation
shows that thermoelectric properties in high temperature region can be enhanced
by tuning the sample synthesis conditions and suitable doping. The estimated
value of \textit{figure-of-merit}, ZT, at different absolute temperature
suggest that ZnV$_{2}$O$_{4}$ compound can be a good thermoelectric material in
high temperature range.


title: Data mining : past present and future - a typical survey on data streams

abstract:
  Data Stream Mining is one of the area gaining lot of practical significance
and is progressing at a brisk pace with new methods, methodologies and findings
in various applications related to medicine, computer science, bioinformatics
and stock market prediction, weather forecast, text, audio and video processing
to name a few. Data happens to be the key concern in data mining. With the huge
online data generated from several sensors, Internet Relay Chats, Twitter, Face
book, Online Bank or ATM Transactions, the concept of dynamically changing data
is becoming a key challenge, what we call as data streams. In this paper, we
give the algorithm for finding frequent patterns from data streams with a case
study and identify the research issues in handling data streams.


title: Scattering Matrix and Analytic Torsion

abstract:
  For a compact manifold, which has a part isometric to a cylinder of finite
length, we consider an adiabatic limit procedure, in which the length of the
cylinder tends to infinity. We study the asymptotic of the spectrum of
Hodge-Laplacian and the asymptotic of the $L^2$-metric on de Rham cohomology.
As an application, we give a pure analytic proof of the gluing formula for
analytic torsion.


title:
High spatial resolution optical imaging of the multiple T Tauri system
  LkH{\alpha} 262/LkH{\alpha} 263

abstract:
  We report high spatial resolution i' band imaging of the multiple T Tauri
system LkH$\alpha$ 262/LkH$\alpha$ 263 obtained during the first commissioning
period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel
Telescope, using its Lucky Imaging mode. AOLI images have provided photometry
for each of the two components LkH$\alpha$ 263 A and B (0.41 arcsec separation)
and marginal evidence for an unresolved binary or a disc in LkH$\alpha$ 262.
The AOLI data combined with previously available and newly obtained optical and
infrared imaging show that the three components of LkH$\alpha$ 263 are
co-moving, that there is orbital motion in the AB pair, and, remarkably, that
LkH$\alpha$ 262-263 is a common proper motion system with less than 1 mas/yr
relative motion. We argue that this is a likely five-component gravitationally
bounded system. According to BT-settl models the mass of each of the five
components is close to 0.4 M$_{\odot}$ and the age is in the range 1-2 Myr. The
presence of discs in some of the components offers an interesting opportunity
to investigate the formation and evolution of discs in the early stages of
multiple very low-mass systems. In particular, we provide tentative evidence
that the disc in 263C could be coplanar with the orbit of 263AB.


title: Unsplittable classes of separable permutations

abstract:
  A permutation class is splittable if it is contained in the merge of two of
its proper subclasses. We characterise the unsplittable subclasses of the class
of separable permutations both structurally and in terms of their bases.


title: To the Thomson cross-section of light scattered by moving particle

abstract:
  In this paper in a framework of classical electrodynamics, we re-derived in a
simple way the formula for the light scattering by moving particle with
arbitrary angle of collision.


title: Performance Comparison of CP-OFDM and OQAM-OFDM Based WiFi Systems

abstract:
  In this contribution, a direct comparison of the Offset-QAM-OFDM (OQAM-OFDM)
and the Cyclic Prefix OFDM (CP-OFDM) scheme is given for an 802.11a based
system. Therefore, the chosen algorithms and choices of design are described
and evaluated as a whole system in terms of bit and frame error rate (BER/FER)
performance as well as spectral efficiency and complexity in the presence of
multipath propagation for different modulation orders. The results show that
the OQAM-OFDM scheme exhibits similar BER and FER performance at a 24% higher
spectral efficiency and achievable throughput at the cost of an up to five
times increased computational complexity.


title: A Fast Lightweight Time-Series Store for IoT Data

abstract:
  With the advent of the Internet-of-Things (IoT), handling large volumes of
time-series data has become a growing concern. Data, generated from millions of
Internet-connected sensors, will drive new IoT applications and services. A key
requirement is the ability to aggregate, preprocess, index, store and analyze
data with minimal latency so that time-to-insight can be reduced. In the
future, we expect real-time data collection and analysis to be performed both
on small devices (e.g., in hubs and appliances) as well in server-based
infrastructure. The ability to localize sensitive data to the home, and thus
preserve privacy, is a key driver for small-device deployment.
  In this paper, we present an efficient architecture for time-series data
management that provides a high data ingestion rate, while still being
sufficiently lightweight that it can be deployed in embedded environments or
small virtual machines. Our solution strives to minimize overhead and explores
what can be done without complex indexing schemes that typically, for
performance reasons, must be held in main memory. We combine a simple in-memory
hierarchical index, log-structured store and in-flight sort, with a
high-performance data pipeline architecture that is optimized for multicore
platforms. We show that our solution is able to handle streaming insertions at
over 4 million records per second (on a single x86 server) while still
retaining SQL query performance better than or comparable to existing RDBMS.


title: Sampling Requirements for Stable Autoregressive Estimation

abstract:
  We consider the problem of estimating the parameters of a linear univariate
autoregressive model with sub-Gaussian innovations from a limited sequence of
consecutive observations. Assuming that the parameters are compressible, we
analyze the performance of the $\ell_1$-regularized least squares as well as a
greedy estimator of the parameters and characterize the sampling trade-offs
required for stable recovery in the non-asymptotic regime. In particular, we
show that for a fixed sparsity level, stable recovery of AR parameters is
possible when the number of samples scale sub-linearly with the AR order. Our
results improve over existing sampling complexity requirements in AR estimation
using the LASSO, when the sparsity level scales faster than the square root of
the model order. We further derive sufficient conditions on the sparsity level
that guarantee the minimax optimality of the $\ell_1$-regularized least squares
estimate. Applying these techniques to simulated data as well as real-world
datasets from crude oil prices and traffic speed data confirm our predicted
theoretical performance gains in terms of estimation accuracy and model
selection.

categories: cs.IT cs.DM math.IT math.OC stat.ME stat.ML


title: Compound chondrule formation via collision of supercooled droplets

abstract:
  We present a novel model showing that compound chondrules are formed by
collisions of supercooled droplets. This model reproduces two prominent
observed features of compound chondrules: the nonporphyritic texture and the
size ratio between two components.


title: Threshold Selection for Total Variation Denoising

abstract:
  Total variation (TV) denoising is a nonparametric smoothing method that has
good properties for preserving sharp edges and contours in objects with spatial
structures like natural images. The estimate is sparse in the sense that TV
reconstruction leads to a piecewise constant function with a small number of
jumps. A threshold parameter controls the number of jumps and the quality of
the estimation. In practice, this threshold is often selected by minimizing a
goodness-of-fit criterion like cross-validation, which can be costly as it
requires solving the high-dimensional and non-differentiable TV optimization
problem many times. We propose instead a two step adaptive procedure via a
connection to large deviation of stochastic processes. We also give conditions
under which TV denoising achieves exact segmentation. We then apply our
procedure to denoise a collection of 1D and 2D test signals verifying the
effectiveness of our approach in practice.


title:
A Systematic Survey of Protoclusters at $z\sim3\mathrm{-}6$ in the
  CFHTLS Deep Fields

abstract:
  We present the discovery of three protoclusters at $z\sim3\mathrm{-}4$ with
spectroscopic confirmation in the Canada-France-Hawaii Telescope (CFHT) Legacy
Survey Deep Fields. In these fields, we investigate the large-scale projected
sky distribution of $z\sim3\mathrm{-}6$ Lyman break galaxies and identify 21
protocluster candidates from regions that are overdense at more than $4\sigma$
overdensity significance. Based on cosmological simulations, it is expected
that more than $76\%$ of these candidates will evolve into a galaxy cluster of
at least a halo mass of $10^{14}\,\mathrm{M_\odot}$ at $z=0$. We perform
follow-up spectroscopy for eight of the candidates using Subaru/FOCAS,
KeckII/DEIMOS, and Gemini-N/GMOS. In total we target 462 dropout candidates and
obtain 138 spectroscopic redshifts. We confirm three real protoclusters at
$z=3\mathrm{-}4$ with more than five members spectroscopically identified, and
find one to be an incidental overdense region by mere chance alignment. The
other four candidate regions at $z\sim5\mathrm{-}6$ require more spectroscopic
follow-up in order to be conclusive. A $z=3.67$ protocluster, which has eleven
spectroscopically confirmed members, shows a remarkable core-like structure
composed of a central small region ($<0.5\,\mathrm{physical\>Mpc}$) and an
outskirts region ($\sim1.0\,\mathrm{physical\>Mpc}$). The Ly$\alpha$ equivalent
widths of members of the protocluster are significantly smaller than those of
field galaxies at the same redshift while there is no difference in the UV
luminosity distributions. These results imply that some environmental effects
start operating as early as at $z\sim4$ along with the growth of the
protocluster structure.


title:
Second Order Correctness of Perturbation Bootstrap M-Estimator of
  Multiple Linear Regression Parameter

abstract:
  Consider the multiple linear regression model $y_{i} = \boldsymbol{x}'_{i}
\boldsymbol{\beta} + \epsilon_{i}$, where $\epsilon_i$'s are independent and
identically distributed random variables, $\mathbf{x}_i$'s are known design
vectors and $\boldsymbol{\beta}$ is the $p \times 1$ vector of parameters. An
effective way of approximating the distribution of the M-estimator
$\boldsymbol{\bar{\beta}}_n$, after proper centering and scaling, is the
Perturbation Bootstrap Method. In this current work, second order results of
this non-naive bootstrap method have been investigated. Second order
correctness is important for reducing the approximation error uniformly to
$o(n^{-1/2})$ to get better inferences. We show that the classical studentized
version of the bootstrapped estimator fails to be second order correct. We
introduce an innovative modification in the studentized version of the
bootstrapped statistic and show that the modified bootstrapped pivot is second
order correct (S.O.C.) for approximating the distribution of the studentized
M-estimator. Additionally, we show that the Perturbation Bootstrap continues to
be S.O.C. when the errors $\epsilon_i$'s are independent, but may not be
identically distributed. These findings establish perturbation Bootstrap
approximation as a significant improvement over asymptotic normality in the
regression M-estimation.


title:
The Dorsal Striatum and the Dynamics of the Consensus Connectomes in the
  Frontal Lobe of the Human Brain

abstract:
  In the applications of the graph theory it is unusual that one considers
numerous, pairwise different graphs on the very same set of vertices. In the
case of human braingraphs or connectomes, however, this is the standard
situation: the nodes correspond to anatomically identified cerebral regions,
and two vertices are connected by an edge if a diffusion MRI-based workflow
identifies a fiber of axons, running between the two regions, corresponding to
the two vertices. Therefore, if we examine the braingraphs of $n$ subjects,
then we have $n$ graphs on the very same, anatomically identified vertex set.
It is a natural idea to describe the $k$-frequently appearing edges in these
graphs: the edges that are present between the same two vertices in at least
$k$ out of the $n$ graphs. Based on the NIH-funded large Human Connectome
Project's public data release, we have reported the construction of the
Budapest Reference Connectome Server \url{http://connectome.pitgroup.org} that
generates and visualizes these $k$-frequently appearing edges. We call the
graphs of the $k$-frequently appearing edges "$k$-consensus connectomes" since
an edge could be included only if it is present in at least $k$ graphs out of
$n$. Considering the whole human brain, we have reported a surprising property
of these consensus connectomes earlier. In the present work we are focusing on
the frontal lobe of the brain, and we report here a similarly surprising
dynamical property of the consensus connectomes when $k$ is gradually changed
from $k=n$ to $k=1$: the connections between the nodes of the frontal lobe are
seemingly emanating from those nodes that were connected to sub-cortical
structures of the dorsal striatum: the caudate nucleus, and the putamen. We
hypothesize that this dynamic behavior copies the axonal fiber development of
the frontal lobe.


title:
2-Approximation Algorithms for Perishable Inventory Control When FIFO Is
  an Optimal Issuing Policy

abstract:
  We consider a periodic-review, fixed-lifetime perishable inventory control
problem where demand is a general stochastic process. The optimal solution for
this problem is intractable due to "curse of dimensionality". In this paper, we
first present a computationally efficient algorithm that we call the
marginal-cost dual-balancing policy for perishable inventory control problem.
We then prove that a myopic policy under the so-called marginal-cost accounting
scheme provides a lower bound on the optimal ordering quantity. By combining
the specific lower bound we derive and any upper bound on the optimal ordering
quantity with the marginal-cost dual-balancing policy, we present a more
general class of algorithms that we call the truncated-balancing policy. We
prove that when first-in-first-out (FIFO) is an optimal issuing policy, both of
our proposed algorithms admit a worst-case performance guarantee of two, i.e.
the expected total cost of our policy is at most twice that of an optimal
ordering policy. We further present sufficient conditions that ensure the
optimality of FIFO issuing policy. Finally, we conduct numerical analyses based
on real data and show that both of our algorithms perform much better than the
worst-case performance guarantee, and the truncated-balancing policy has a
significant performance improvement over the balancing policy.


title: Convex variational methods for multiclass data segmentation on graphs

abstract:
  Graph-based variational methods have recently shown to be highly competitive
for various classification problems of high-dimensional data, but are
inherently difficult to handle from an optimization perspective. This paper
proposes a convex relaxation for a certain set of graph-based multiclass data
segmentation problems, featuring region homogeneity terms, supervised
information and/or certain constraints or penalty terms acting on the class
sizes. Particular applications include semi-supervised classification of
high-dimensional data and unsupervised segmentation of unstructured 3D point
clouds. Theoretical analysis indicates that the convex relaxation closely
approximates the original NP-hard problems, and these observations are also
confirmed experimentally. An efficient duality based algorithm is developed
that handles all constraints on the labeling function implicitly. Experiments
on semi-supervised classification indicate consistently higher accuracies than
related local minimization approaches, and considerably so when the training
data are not uniformly distributed among the data set. The accuracies are also
highly competitive against a wide range of other established methods on three
benchmark datasets. Experiments on 3D point clouds acquired by a LaDAR in
outdoor scenes, demonstrate that the scenes can accurately be segmented into
object classes such as vegetation, the ground plane and human-made structures.


title:
Soft X-ray irradiance measured by the Solar Aspect Monitor on the Solar
  Dynamic Observatory Extreme ultraviolet Variability Experiment

abstract:
  The Solar Aspect Monitor (SAM) is a pinhole camera on the Extreme-ultraviolet
Variability Experiment (EVE) aboard the Solar Dynamics Observatory (SDO). SAM
projects the solar disk onto the CCD through a metallic filter designed to
allow only solar photons shortward of 7 nm to pass. Contamination from
energetic particles and out-of-band irradiance is, however, significant in the
SAM observations. We present a technique for isolating the 0.01--7 nm
integrated irradiance from the SAM signal to produce the first results of
broadband irradiance for the time period from May 2010 to May 2014. The results
of this analysis agree with a similar data product from EVE's EUV
SpectroPhotometer (ESP) to within 25%. We compare our results with measurements
from the Student Nitric Oxide Explorer (SNOE) Solar X-ray Photometer (SXP) and
the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Solar
EUV Experiment (SEE) at similar levels of solar activity. We show that the
full-disk SAM broadband results compare well to the other measurements of the
0.01--7 nm irradiance. We also explore SAM's capability toward resolving
spatial contribution from regions of solar disk in irradiance and demonstrate
this feature with a case study of several strong flares that erupted from
active regions on March 11, 2011.


title: Efficient quantum transport in disordered interacting many-body networks

abstract:
  The coherent transport of $n$ fermions in disordered networks of $l$
single-particle states connected by $k$-body interactions is studied. These
networks are modeled by embedded Gaussian random matrix ensemble (EGE). The
conductance bandwidth as well as the ensemble-averaged total current attain
their maximal values if the system is highly filled $n \sim l-1$ and $k\sim
n/2$. For the cases $k=1$ and $k=n$ the bandwidth is minimal. We show that for
all parameters the transport is enhanced significantly whenever centrosymmetric
ensemble (csEGE) are considered. In this case the transmission shows numerous
resonances of perfect transport. Analyzing the transmission by spectral
decomposition, we find that centrosymmetry induces strong correlations and
enhances the extrema of the distributions. This suppresses destructive
interference effects in the system and thus, causes backscattering-free
transmission resonances which enhance the overall transport. The distribution
of the total current for the csEGE has a very large dominating peak for
$n=l-1$, close to the highest observed currents.


title: Elliptic scattering equations

abstract:
  Recently the CHY approach has been extended to one loop level using elliptic
functions and modular forms over a Jacobian variety. Due to the difficulty in
manipulating these kind of functions, we propose an alternative prescription
that is totally algebraic. This new proposal is based on an elliptic algebraic
curve embedded in a $\mathbb{C}P^2$ space. We show that for the simplest
integrand, namely the ${\rm n-gon}$, our proposal indeed reproduces the
expected result. By using the recently formulated $\Lambda-$algorithm, we found
a novel recurrence relation expansion in terms of tree level off-shell
amplitudes. Our results connect nicely with recent results on the one-loop
formulation of the scattering equations. In addition, this new proposal can be
easily stretched out to hyperelliptic curves in order to compute higher genus.


title: Differential Invariants of Self-Dual conformal structures

abstract:
  We compute the quotient of the self-duality equation for conformal metrics by
the action of the diffeomorphism group. We also determine Hilbert polynomial,
counting the number of independent scalar differential invariants depending on
the jet-order, and the corresponding Poincar\'e function. We describe the field
of rational differential invariants separating generic orbits of the
diffeomorphism pseudogroup action, resolving the local recognition problem for
self-dual conformal structures.


title:
High efficiency energy extraction from a relativistic electron beam in a
  strongly tapered undulator

abstract:
  We present results of an experiment where, using a 200 GW CO2 laser seed, a
65 MeV electron beam was decelerated down to 35 MeV in a 54 cm long strongly
tapered helical magnetic undulator, extracting over 30$\%$ of the initial
electron beam energy to coherent radiation. These results demonstrate
unparalleled electro-optical conversion efficiencies for a relativistic beam in
an undulator field and represent an important step in the development of high
peak and average power coherent radiation sources.


title: Actuator line modeling of vertical-axis turbines

abstract:
  To bridge the gap between high and low fidelity numerical modeling tools for
vertical-axis (or cross-flow) turbines (VATs or CFTs), an actuator line model
(ALM) was developed and validated for both a high and a medium solidity
vertical-axis turbine at rotor diameter Reynolds numbers $Re_D \sim 10^6$. The
ALM is a combination of classical blade element theory and Navier--Stokes based
flow models, and in this study both $k$--$\epsilon$ Reynolds-averaged
Navier--Stokes (RANS) and Smagorinsky large eddy simulation (LES) turbulence
models were tested using the open-source OpenFOAM computational fluid dynamics
framework. The RANS models were able to be run on coarse grids while still
providing good convergence behavior in terms of the mean power coefficient, and
also approximately four orders of magnitude reduction in computational expense
compared with 3-D blade-resolved RANS simulations. Submodels for dynamic stall,
end effects, added mass, and flow curvature were implemented, resulting in
reasonable performance predictions for the high solidity rotor, more
discrepancies for the medium solidity rotor, and overprediction for both cases
at high tip speed ratio. The wake results showed that the ALM was able to
capture some of the important flow features that contribute to VAT's relatively
fast wake recovery---a large improvement over the conventional actuator disk
model. The mean flow field was better realized with the LES, which still
represented a computational savings of two orders of magnitude compared with
3-D blade-resolved RANS, though vortex breakdown and subsequent turbulence
generation appeared to be underpredicted, which necessitates further
investigation of optimal subgrid scale modeling.


title: Invariant Clusters for Hybrid Systems

abstract:
  In this paper, we propose an approach to automatically compute invariant
clusters for semialgebraic hybrid systems. An invariant cluster for an ordinary
differential equation (ODE) is a multivariate polynomial invariant g(u,x)=0,
parametric in u, which can yield an infinite number of concrete invariants by
assigning different values to u so that every trajectory of the system can be
overapproximated precisely by a union of concrete invariants. For semialgebraic
systems, which involve ODEs with multivariate polynomial vector flow, invariant
clusters can be obtained by first computing the remainder of the Lie derivative
of a template multivariate polynomial w.r.t. its Groebner basis and then
solving the system of polynomial equations obtained from the coefficients of
the remainder. Based on invariant clusters and sum-of-squares (SOS)
programming, we present a new method for the safety verification of hybrid
systems. Experiments on nonlinear benchmark systems from biology and control
theory show that our approach is effective and efficient.


title:
Boltzmann meets Nash: Energy-efficient routing in optical networks under
  uncertainty

abstract:
  Motivated by the massive deployment of power-hungry data centers for service
provisioning, we examine the problem of routing in optical networks with the
aim of minimizing traffic-driven power consumption. To tackle this issue,
routing must take into account energy efficiency as well as capacity
considerations; moreover, in rapidly-varying network environments, this must be
accomplished in a real-time, distributed manner that remains robust in the
presence of random disturbances and noise. In view of this, we derive a pricing
scheme whose Nash equilibria coincide with the network's socially optimum
states, and we propose a distributed learning method based on the Boltzmann
distribution of statistical mechanics. Using tools from stochastic calculus, we
show that the resulting Boltzmann routing scheme exhibits remarkable
convergence properties under uncertainty: specifically, the long-term average
of the network's power consumption converges within $\varepsilon$ of its
minimum value in time which is at most $\tilde O(1/\varepsilon^2)$,
irrespective of the fluctuations' magnitude; additionally, if the network
admits a strict, non-mixing optimum state, the algorithm converges to it -
again, no matter the noise level. Our analysis is supplemented by extensive
numerical simulations which show that Boltzmann routing can lead to a
significant decrease in power consumption over basic, shortest-path routing
schemes in realistic network conditions.


title:
Orbit-spin coupling and the interannual variability of global-scale dust
  storm occurrence on Mars

abstract:
  A new physical hypothesis predicts that a weak coupling of the orbital and
rotational motions of extended bodies may give rise to a modulation of
circulatory flows within their atmospheres. Driven cycles of intensification
and relaxation of large-scale circulatory flows are predicted, with the phasing
of these changes linked directly to the rate of change of the orbital angular
momentum with respect to inertial frames. We test the hypothesis that
global-scale dust storms (GDS) on Mars may occur when periods of circulatory
intensification (associated with positive and negative extrema of the waveform)
coincide with the southern summer dust storm season on Mars. The orbit-spin
coupling hypothesis additionally predicts that the intervening transitional
periods, which are characterized by the disappearance and subsequent sign
change of this waveform, may be unfavorable for the occurrence of GDS, when
they occur during the southern summer dust storm season. These hypotheses are
confirmed through comparisons between calculated dynamical time series of the
time rate of change of orbital angular momentum and historic observations. All
of the nine known global-scale dust storms on Mars took place during Mars years
when circulatory intensification during the dust storm season is predicted
under the orbit-spin coupling hypothesis. No historic global-scale dust storms
were recorded during transitional intervals. Orbit-spin coupling accelerations
evidently contribute to the interannual variability of the Mars atmosphere.


title: Extreme Asymmetry in the Disk of V1247 Ori

abstract:
  We present the first near-infrared scattered-light detection of the
transitional disk around V1247 Ori, which was obtained using high-resolution
polarimetric differential imaging observations with Subaru/HiCIAO. Our imaging
in the H band reveals the disk morphology at separations of ~0.14"-0.86"
(54-330 au) from the central star. The polarized intensity (PI) image shows a
remarkable arc-like structure toward the southeast of the star, whereas the
fainter northwest region does not exhibit any notable features. The shape of
the arm is consistent with an arc of 0.28" $\pm$ 0.09" in radius (108 au from
the star), although the possibility of a spiral arm with a small pitch angle
cannot be excluded. V1247 Ori features an exceptionally large azimuthal
contrast in scattered, polarized light; the radial peak of the southeastern arc
is about three times brighter than the northwestern disk measured at the same
distance from the star. Combined with the previous indication of an
inhomogeneous density distribution in the gap at $\lesssim$46 au, the notable
asymmetry in the outer disk suggests the presence of unseen companions and/or
planet-forming processes ongoing in the arc.


title:
Measurements of nanoresonator-qubit interactions in a hybrid quantum
  electromechanical system

abstract:
  Experiments to probe the basic quantum properties of motional degrees of
freedom of mechanical systems have developed rapidly over the last decade. One
promising approach is to use hybrid electromechanical systems incorporating
superconducting qubits and microwave circuitry. However, a critical challenge
facing the development of these systems is to achieve strong coupling between
mechanics and qubits while simultaneously reducing coupling of both the qubit
and mechanical mode to the environment. Here we report measurements of a
qubit-coupled mechanical resonator system consisting of an ultra-high-frequency
nanoresonator and a long coherence-time superconducting transmon qubit,
embedded in superconducting coplanar waveguide cavity. It is demonstrated that
the nanoresonator and transmon have commensurate energies and transmon
coherence times are one order of magnitude larger than for all previously
reported qubit-coupled nanoresonators. Moreover, we show that numerical
simulations of this new hybrid quantum system are in good agreement with
spectroscopic measurements and suggest that the nanoresonator in our device
resides at low thermal occupation number, near its ground state, acting as a
dissipative bath seen by the qubit. We also outline how this system could soon
be developed as a platform for implementing more advanced experiments with
direct relevance to quantum information processing and quantum thermodynamics,
including the study of nanoresonator quantum noise properties, reservoir
engineering, and nanomechanical quantum state generation and detection.


title: Connectivity Functions and Polymatroids

abstract:
  A {\em connectivity function on} a set $E$ is a function
$\lambda:2^E\rightarrow \mathbb R$ such that $\lambda(\emptyset)=0$, that
$\lambda(X)=\lambda(E-X)$ for all $X\subseteq E$ and that $\lambda(X\cap
Y)+\lambda(X\cup Y)\leq \lambda(X)+\lambda(Y)$ for all $X,Y \subseteq E$.
Graphs, matroids and, more generally, polymatroids have associated connectivity
functions. We introduce a notion of duality for polymatroids and prove that
every connectivity function is the connectivity function of a self-dual
polymatroid. We also prove that every integral connectivity function is the
connectivity function of a half-integral self-dual polymatroid.


title:
Cosmological dynamics of spatially flat Einstein-Gauss-Bonnet models in
  various dimensions. Vacuum case

abstract:
  In this paper we perform a systematic study of vacuum spatially flat
((3+D)+1)-dimensional Einstein-Gauss-Bonnet cosmological models. We consider
models which topologically are the product of two flat isotropic subspaces with
different scale factors. One of these subspaces is 3D and represents our space
and the other is D-dimensional and represents extra dimensions. We consider no
ansatz of the scale factors, which makes our results quite general. With both
Einstein-Hilbert and Gauss-Bonnet contributions in play, the cases with D=1,
D=2, D=3 and $D\geqslant 4$ have different dynamics due to different structure
of the equations of motion. We analytically study equations of motion in all
cases and describe all possible regimes. It appears that the only regimes with
nonsingular future asymptotes are the Kasner regime in GR as well as
exponential regimes. As of the past asymptotes, for a smooth transition only
Kasner regime in Gauss-Bonnet is an option. With that at hand, we are down only
to two viable regimes -- "pure" Kasner regime (transition from high- to
low-energy Kasner regime) and a transition from high-energy Kasner to
anisotropic exponential solution. It appears that these regimes take place for
different signs of the Gauss-Bonnet coupling $\alpha$: "pure" Kasner regime
occur for $\alpha > 0$ at low D and $\alpha < 0$ for high D; anisotropic
exponential regime is reached only for $\alpha > 0$. So if we restrain
ourselves with $\alpha > 0$ solutions, the only late-time regimes are Kasner
for D=1, 2 and anisotropic exponential for $D\geqslant 2$. Also, low-energy
Kasner regimes ($a(t)\propto t^p$) have expansion rates for (3+1)-dimensional
subspace ("our Universe") ranging from p=0.5 (D=1) to $p=1/\sqrt{3} \approx
0.577$ ($D\to\infty$), which contradicts with dust-dominated Friedmann
prediction (p=2/3).


title: Electron interference in ballistic graphene nanoconstrictions

abstract:
  We have realized nanometer size constrictions in ballistic graphene
nanoribbons grown on sidewalls of SiC mesa structures. The high quality of our
devices allows the observation of a number of electronic quantum interference
phenomena. The transmissions of Fabry-Perot like resonances were probed by
in-situ transport measurements at various temperatures. The energies of the
resonances are determined by the size of the constrictions which can be
controlled precisely using STM lithography. The temperature and size dependence
of the measured conductances are in quantitative agreement with tight-binding
calculations. The fact that these interference effects are visible even at room
temperature makes the reported devices attractive as building blocks for future
carbon based electronics.


title:
Explicit high-order symplectic integrators for charged particles in
  general electromagnetic fields

abstract:
  This article considers non-relativistic charged particle dynamics in both
static and non-static electromagnetic fields, which are governed by
nonseparable, possibly time-dependent Hamiltonians. For the first time,
explicit symplectic integrators of arbitrary high-orders are constructed for
accurate and efficient simulations of such mechanical systems. Performances
superior to the standard non-symplectic method of Runge-Kutta are demonstrated
on two examples: the first is on the confined motion of a particle in a static
toroidal magnetic field used in tokamak; the second is on how time-periodic
perturbations to a magnetic field inject energy into a particle via parametric
resonance at a specific frequency.


title: Movement Coordination in Human-Robot Teams: A Dynamical Systems Approach

abstract:
  In order to be effective teammates, robots need to be able to understand
high-level human behavior to recognize, anticipate, and adapt to human motion.
We have designed a new approach to enable robots to perceive human group motion
in real-time, anticipate future actions, and synthesize their own motion
accordingly. We explore this within the context of joint action, where humans
and robots move together synchronously. In this paper, we present an
anticipation method which takes high-level group behavior into account. We
validate the method within a human-robot interaction scenario, where an
autonomous mobile robot observes a team of human dancers, and then successfully
and contingently coordinates its movements to "join the dance". We compared the
results of our anticipation method to move the robot with another method which
did not rely on high-level group behavior, and found our method performed
better both in terms of more closely synchronizing the robot's motion to the
team, and also exhibiting more contingent and fluent motion. These findings
suggest that the robot performs better when it has an understanding of
high-level group behavior than when it does not. This work will help enable
others in the robotics community to build more fluent and adaptable robots in
the future.


title:
Fluid-structure interaction simulation of floating structures
  interacting with complex, large-scale ocean waves and atmospheric turbulence

abstract:
  We develop a numerical method for simulating coupled interactions of complex
floating structures with large-scale ocean waves and atmospheric turbulence. We
employ an efficient large-scale model to develop offshore wind and wave
environmental conditions, which are then incorporated into a high resolution
two-phase flow solver with fluid-structure interaction (FSI). The large-scale
wind-wave interaction model is based on the two-fluid dynamically-coupled
approach of Yang and Shen (2011), which employs a high-order spectral method
for simulating the water motion and a viscous solver with undulatory boundaries
for the air motion. The two-phase flow FSI solver, developed by Calderer, Kang,
and Sotiropoulos (2014), is based on the level set method and is capable of
simulating the coupled dynamic interaction of arbitrarily complex bodies with
airflow and waves. The large-scale wave field solver is coupled with the
near-field FSI solver by feeding into the latter waves via the pressure-forcing
method of Guo and Shen (2009), which has been extended herein for the level set
method. We validate the model for both simple wave trains and three-dimensional
directional waves and compare the results with experimental and theoretical
solutions. Finally, we demonstrate the capabilities of the new computational
framework by carrying out large-eddy simulation of a floating offshore wind
turbine interacting with realistic ocean wind and waves.


title:
On the Incorporation of Metallicity Data into Star Formation History
  Measurements from Resolved Stellar Populations

abstract:
  The combination of spectroscopic stellar metallicities and resolved star
color-magnitude diagrams (CMDs) has the potential to constrain the entire star
formation and chemical enrichment history (SFH) of a galaxy better than fitting
CMDs alone (as is most common in SFH studies using resolved stellar
populations). In this paper, two approaches for incorporating external
metallicity information into color-magnitude diagram fitting techniques are
presented. Overall, the joint fitting of metallicity and CMD information can
increase the precision on measured age-metallicity relationships and star
formation rates by ~10% over CMD fitting alone. However, systematics in stellar
isochrones and mismatches between spectroscopic and photometric metallicity
determinations can reduce the accuracy of the recovered SFHs. I present a
simple mitigation of these systematics that can reduce the amplitude of these
systematics to the level obtained from CMD fitting alone, while ensuring the
age-metallicity relationship is consistent with spectroscopic metallicities. As
is the case in CMD-fitting analysis, improved stellar models and calibrations
between spectroscopic and photometric metallicities are currently the primary
impediment to gains in SFH precision from jointly fitting stellar metallicities
and CMDs.


title: Linear and nonlinear responses to harmonic force in rotating flow

abstract:
  For understanding the dissipation in a rotating flow when resonance occurs,
we study the rotating flow driven by the harmonic force in a periodic box. Both
the linear and nonlinear regimes are studied. The various parameters such as
the force amplitude $a$, the force frequency $\omega$, the force wavenumber
$k$, and the Ekman number $E$ are investigated. In the linear regime, the
dissipation at the resonant frequency scales as $E^{-1}k^{-2}$, and it is much
stronger than the dissipation at the non-resonant frequencies on the large
scales and at the low Ekman numbers. In the nonlinear regime, at the resonant
frequency the effective dissipation (dissipation normalised with the square of
force amplitude) is lower than in the linear regime and it decreases with the
increasing force amplitude. This nonlinear suppression effect is significant
near the resonant frequency but negligible far away from the resonant
frequency. Opposite to the linear regime, in the nonlinear regime at the
resonant frequency the lower Ekman number leads to the lower dissipation
because of the stronger nonlinear effect. This work implies that the previous
linear calculations overestimated the tidal dissipation, which is important for
understanding the tides in stars and giant planets.

categories: astro-ph.SR astro-ph.EP physics.flu-dyn physics.geo-ph


title: The existence of stable BGK waves

abstract:
  The 1D Vlasov-Poisson system is the simplest kinetic model for describing an
electrostatic collisonless plasma, and the BGK waves are its famous exact
steady solutions. They play an important role on the long time dynamics of a
collisionless plasma as potential "final states" or "attractors", thanks to
many numerical simulations and observations. Despite their importance, the
existence of stable BGK waves has been an open problem since their discovery in
1958. In this paper, first linearly stable BGK waves are constructed near
homogeneous states.


title:
Pointwise nonlinear stability of nonlocalized modulated periodic
  reaction-diffusion waves

abstract:
  In this paper, extending previous results of \cite{J1}, we obtain pointwise
nonlinear stability of periodic traveling reaction-diffusion waves, assuming
spectral linearized stability, under nonlocalized perturbations. More
precisely, we establish pointwise estimate of nonlocalized modulational
perturbation under a small initial perturbation consisting of a nonlocalized
modulation plus a localized perturbation decaying algebraically.


title: On a Parabolic-Hyperbolic Filter for Multicolor Image Noise Reduction

abstract:
  We propose a novel PDE-based anisotropic filter for noise reduction in
multicolor images. It is a generalization of Nitzberg & Shiota's (1992) model
being a hyperbolic relaxation of the well-known parabolic Perona & Malik's
filter (1990). First, we consider a `spatial' molifier-type regularization of
our PDE system and exploit the maximal $L^{2}$-regularity theory for
non-autonomous forms to prove a well-posedness result both in weak and strong
settings. Again, using the maximal $L^{2}$-regularity theory and Schauder's
fixed point theorem, respective solutions for the original quasilinear problem
are obtained and the uniqueness of solutions with a bounded gradient is proved.
Finally, the long-time behavior of our model is studied.


title:
A multi-transition molecular line study of infrared dark cloud
  G331.71+00.59

abstract:
  Using archive data from the Millimeter Astronomy Legacy Team Survey at 90 GHz
(MALT90), carried out using the Mopra 22-m telescope, we made the first
multi-transition molecular line study of infrared dark cloud (IRDC) MSXDC
G331.71+00.59. Two molecular cores were found embedded in this IRDC. Each of
these cores is associated with a known extended green object (EGO), indicating
places of massive star formation. The HCO+ (1-0) and HNC (1-0) transitions show
prominent blue or red asymmetric structures, suggesting outflow and inflow
activities of young stellar objects (YSOs). Other detected molecular lines
include H13CO+ (1-0), C2H (1-0), HC3N (10-9), HNCO(404-303) and SiO (2-1),
which are typical of hot cores and outflows. We regard the two EGOs as evolving
from the IRDC to hot cores. Using public GLIMPS data, we investigate the
spectral energy distribution of EGO G331.71+0.60. Our results support this EGO
being a massive YSO driving the outflow. G331.71+0.58 may be at an earlier
evolutionary stage.


title: A multiwavelength study of the star forming H II region Sh2-82

abstract:
  Based on a multiwavelength study, the interstellar medium and young stellar
objects (YSOs) around the HII region Sh2-82 have been analyzed. Two molecular
clumps were found from the archival data of the Galactic Ring Survey, and using
the Two Micron All-Sky Survey catalog, we found two corresponding young
clusters embedded in the molecular clumps. The very good relations between CO
emission, infrared shells and YSOs suggest that it is probably a triggered star
formation region from the expansion of Sh2-82. We further used the data from
the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire from Spitzer to
study the YSOs within the two clumps, confirming star formation in this region.
By spectral energy distribution fits to each YSO candidate with infrared
excess, we derived the slope of the initial mass function. Finally, comparing
the HII region's dynamical age and the fragmentation time of the molecular
shell, we discard the "collect and collapse" process as being the triggering
mechanism for YSO formation. Sh2-82 can be a mixture of other processes such as
radiative-driven implosion and/or collisions with pre-existing clumps.


title: How else can we detect Fast Radio Bursts?

abstract:
  We discuss possible electromagnetic signals accompanying Fast Radio Bursts
(FRBs) that are expected in the scenario where FRBs originate in neutron star
magnetospheres. For models involving Crab-like giant pulses, no appreciable
contemporaneous emission is expected at other wavelengths. Magnetar giant
flares, driven by the reconfiguration of the magnetosphere, however, can
produce both contemporaneous bursts at other wavelengths as well as
afterglow-like emission. We conclude that the best chances are: (i) prompt
short GRB-like emission; (ii) a contemporaneous optical flash that can reach
naked eye peak luminosity (but only for a few milliseconds); (iii) a high
energy afterglow emission. Case (i) could be tested by coordinated radio and
high-energy experiments. Case (ii) could be seen in a coordinated radio-optical
surveys, \eg\ by the Palomar Transient Factory in a 60-second frame as a
transient object of $m=15-20$ magnitude with an expected optical detection rate
of about 0.1~hr$^{-1}$, an order of magnitude higher than in radio. Shallow,
but large-area sky surveys such as ASAS-SN and EVRYSCOPE could also detect
prompt optical flashes from the more powerful Lorimer-burst clones. The best
constraints on the optical-to-radio power for this kind of emission could be
provided by future observations with facilities like LSST. Case (iii) might be
seen in relatively rare cases that the relativistically ejected magnetic blob
is moving along the line of sight.


title: Monochromatic sums and products in $\mathbb{N}$

abstract:
  An old question in Ramsey theory asks whether any finite coloring of the
natural numbers admits a monochromatic pair $\{x+y,xy\}$. We answer this
question affirmatively in a strong sense by exhibiting a large new class of
non-linear patterns which can be found in a single cell of any finite partition
of $\mathbb{N}$. Our proof involves a correspondence principle which transfers
the problem into the language of topological dynamics. As a corollary of our
main theorem we obtain partition regularity for new types of equations, such as
$x^2-y^2=z$ and $x^2+2y^2-3z^2=w$.


title: Cantor type functions in non-integer bases

abstract:
  Cantor's ternary function is generalized to arbitrary base-change functions
in non-integer bases. Some of them share the curious properties of Cantor's
function, while others behave quite differently.


title:
The unexpected thermal conductivity from graphene disk, carbon nanocone
  to carbon nanotube

abstract:
  Graphene and single-wall carbon nanotube (SWCNT) have attracted great
attention because of their ultra-high thermal conductivity. However, there are
few works exploring the relations of their thermal conductivity quantitatively.
The carbon nanocone (CNC) is a graded structure fall in between graphene disk
(GD) and SWCNT. We perform non-equilibrium molecular dynamics (NEMD) simulation
to study the thermal conductivity of CNC with different apex angles, and then
compare them with that of GD and SWCNT. Our results show that, different from
the homogeneous thermal conductivity in SWCNT, the CNC also has a natural
graded thermal conductivity which is similar to the GD. Unexpectedly, the
graded rate keeps almost the same when the apex angle decreases from 180{\deg}
(GD) to 19{\deg}, but then suddenly declines to zero when the apex angle
decreases from 19{\deg} to 0{\deg} (SWCNT). What is more interesting, the
graded effect is not diminished when the interatomic force constant is weakened
and mean free path is shorten. That is, besides nanoscale, the graded effect
can be observed in macroscale graphene or CNC structures.


title:
Studying Critical String Emerging from Non-Abelian Vortex in Four
  Dimensions

abstract:
  Recently a special vortex string was found [5] in a class of soliton vortices
supported in four-dimensional Yang-Mills theories that under certain conditions
can become infinitely thin and can be interpreted as a critical ten-dimensional
string. The appropriate bulk Yang-Mills theory has the U(2) gauge group and the
Fayet-Iliopoulos term. It supports semilocal non-Abelian vortices with the
world-sheet theory for orientational and size moduli described by the weighted
CP(2,2) model. The full target space is R_4\times Y_6 where Y_6 is a
non-compact Calabi-Yau space.
  We study the above vortex string from the standpoint of string theory,
focusing on the massless states in four dimensions. In the generic case all
massless modes are non-normalizable, hence, no massless gravitons or vector
fields are predicted in the physical spectrum. However, at the selfdual point
(at strong coupling) weighted CP(2,2) admits deformation of the complex
structure, resulting in a single massless hypermultiplet in the bulk. We
interpret it as a composite "baryon."


title: Topological Interference Management with Reconfigurable Antennas

abstract:
  We study the symmetric degrees-of-freedom (DoF) of partially connected
interference networks under linear coding strategies at transmitters without
channel state information beyond topology. We assume that the receivers are
equipped with reconfigurable antennas that can switch among their preset modes.
In such a network setting, we characterize the class of network topologies in
which half linear symmetric DoF is achievable. Moreover, we derive a general
upper bound on the linear symmetric DoF for arbitrary network topologies. We
also show that this upper bound is tight if the transmitters have at most two
co-interferers.


title: The Gyori-Lovasz theorem

abstract:
  Gyori and Lovasz independently proved the following beautiful theorem. Let
$k\ge2$ be an integer, let $G$ be a $k$-connected graph on $n$ vertices, let
$v_1,v_2,\ldots,v_k$ be distinct vertices of $G$ and let $n_1,n_2,\ldots,n_k$
be positive integers with $n_1+n_2+\cdots+n_k=n$. Then $G$ has disjoint
connected subgraphs $G_1,G_2,\ldots,G_k$ such that for $i=1,2,\ldots,k$ the
graph $G_i$ has $n_i$ vertices and $v_i\in V(G_i)$. We give a self-contained
exposition of Gyori's proof.


title: Linear and non-linear perturbations in dark energy models

abstract:
  In this work we discuss observational aspects of three time-dependent
parameterisations of the dark energy equation of state $w(z)$. In order to
determine the dynamics associated with these models, we calculate their
background evolution and perturbations in a scalar field representation. After
performing a complete treatment of linear perturbations, we also show that the
non-linear contribution of the selected $w(z)$ parameterisations to the matter
power spectra is almost the same for all scales, with no significant difference
from the predictions of the standard $\Lambda$CDM model.


title:
Improvement in a phenomenological formula for ground state binding
  energies

abstract:
  The phenomenological formula for ground state binding energy derived earlier
(International Journal of Modern Physics E {\bf 20} (2011) 179) has been
modified. The parameters have been obtained by fitting the latest available
tabulation of experimental values. The major modifications include a new term
for pairing and introduction of a new neutron magic number at $N=160$. The new
formula reduced the root mean square deviation to 363 keV, a substantial
improvement over the previous version of the formula.


title: Structure of $^{78}$Ni from first principles computations

abstract:
  Doubly magic nuclei have a simple structure and are the cornerstones for
entire regions of the nuclear chart. Theoretical insights into the supposedly
doubly magic $^{78}$Ni and its neighbors are challenging because of the extreme
neutron-to-proton ratio and the proximity of the continuum. We predict the
$J^\pi=2_1^+$ state in $^{78}$Ni from a correlation with the $J^\pi=2_1^+$
state in $^{48}$Ca using chiral nucleon-nucleon and three-nucleon interactions.
Our results confirm that $^{78}$Ni is doubly magic, and the predicted low-lying
states of $^{79,80}$Ni open the way for shell-model studies of many more rare
isotopes.


title: Modeling Rich Contexts for Sentiment Classification with LSTM

abstract:
  Sentiment analysis on social media data such as tweets and weibo has become a
very important and challenging task. Due to the intrinsic properties of such
data, tweets are short, noisy, and of divergent topics, and sentiment
classification on these data requires to modeling various contexts such as the
retweet/reply history of a tweet, and the social context about authors and
relationships. While few prior study has approached the issue of modeling
contexts in tweet, this paper proposes to use a hierarchical LSTM to model rich
contexts in tweet, particularly long-range context. Experimental results show
that contexts can help us to perform sentiment classification remarkably
better.


title:
Two-dimensional spin-imbalanced Fermi gases at non-zero temperature:
  Phase separation of a non-condensate

abstract:
  We study a trapped two-dimensional spin-imbalanced Fermi gas over a range of
temperatures. In the moderate temperature regime, associated with current
experiments, we find reasonable semi-quantitative agreement with the measured
density profiles as functions of varying spin imbalance and interaction
strength. Our calculations show that, in contrast to the three-dimensional
case, the phase separation which appears as a spin balanced core, can be
associated with non-condensed fermion pairs. We present predictions at lower
temperatures where a quasi-condensate will first appear, based on the pair
momentum distribution and following the protocols of Jochim and collaborators.
While these profiles also indicate phase separation, they exhibit distinctive
features which may aid in identifying the condensation regime.


title: Towards Understanding Generics in Mainstream OOP

abstract:
  This article reports on steps towards building a simple and accurate
domain-theoretic model of generic nominally-typed OOP.


title:
On The Birch and Swinnerton-Dyer Conjecture for CM Elliptic Curves over
  $\BQ$

abstract:
  For CM elliptic curve over rational field with analytic rank one, for any
potential good ordinary prime p, not dividing the number of roots of unity in
the complex multiplication field, we show the p-part of its Shafarevich-Tate
group has order predicted by the Birch and Swinnerton-Dyer conjecture.


title:
Componentwise accurate Brownian motion computations using Cyclic
  Reduction

abstract:
  Markov-modulated Brownian motion is a popular tool to model continuous-time
phenomena in a stochastic context. The main quantity of interest is the
invariant density, which satisfies a differential equation associated with the
quadratic matrix polynomial $P(z) = Vz^2-Dz +Q$, where the matrices $V$ and $D$
are diagonal and $Q$ is the transition matrix of a discrete-time Markov chain.
Its solution is typically constructed by computing an invariant pair of $P(z)$
associated with its eigenvalues in the left half-plane, or by solving the
matrix equation $X^2V-XD+Q=0$. We show that these tasks can be solved using a
componentwise accurate algorithm based on Cyclic Reduction, generalizing the
recently appeared algorithms for the linear case ($V=0$). We give a proof of
the numerical stability of our algorithm in the componentwise sense; the same
proof applies to Cyclic Reduction in a more general M-matrix setting which
appears in other applications such as the modelling of QBD processes.


title: Spectral Properties of Hypergraph Laplacian and Approximation Algorithms

abstract:
  The celebrated Cheeger's Inequality establishes a bound on the edge expansion
of a graph via its spectrum. This inequality is central to a rich spectral
theory of graphs, based on studying the eigenvalues and eigenvectors of the
adjacency matrix (and other related matrices) of graphs. It has remained open
to define a suitable spectral model for hypergraphs whose spectra can be used
to estimate various combinatorial properties of the hypergraph.
  In this paper we introduce a new hypergraph Laplacian operator generalizing
the Laplacian matrix of graphs. In particular, the operator is induced by a
diffusion process on the hypergraph, such that within each hyperedge, measure
flows from vertices having maximum weighted measure to those having minimum.
Since the operator is non-linear, we have to exploit other properties of the
diffusion process to recover a spectral property concerning the "second
eigenvalue" of the resulting Laplacian. Moreover, we show that higher order
spectral properties cannot hold in general using the current framework.
  We consider a stochastic diffusion process, in which each vertex also
experiences Brownian noise from outside the system. We show a relationship
between the second eigenvalue and the convergence behavior of the process.
  We show that various hypergraph parameters like multi-way expansion and
diameter can be bounded using this operator's spectral properties. Since higher
order spectral properties do not hold for the Laplacian operator, we instead
use the concept of procedural minimizers to consider higher order Cheeger-like
inequalities. For any positive integer $k$, we give a polynomial time algorithm
to compute an $O(\log r)$-approximation to the $k$-th procedural minimizer,
where $r$ is the maximum cardinality of a hyperedge. We show that this
approximation factor is optimal under the SSE hypothesis for constant values of
$k$.


title:
Macroscopic limits of pathway-based kinetic models for E.coli chemotaxis
  in large gradient environments

abstract:
  It is of great biological interest to understand the molecular origins of
chemotactic behavior of E. coli by developing population-level models based on
the underlying signaling pathway dynamics. We derive macroscopic models for
E.coli chemotaxis that match quantitatively with the agent-based model (SPECS)
for all ranges of the spacial gradient, in particular when the chemical
gradient is large such that the standard Keller-Segel model is no longer valid.
These equations are derived both formally and rigorously as asymptotic limits
for pathway-based kinetic equations. We also present numerical results that
show good agreement between the macroscopic models and SPECS. Our work provides
an answer to the question of how to determine the population-level diffusion
coefficient and drift velocity from the molecular mechanisms of chemotaxis, for
both shallow gradients and large gradients environments.


title: Matrix-Variate Regressions and Envelope Models

abstract:
  Modern technology often generates data with complex structures in which both
response and explanatory variables are matrix-valued. Existing methods in the
literature are able to tackle matrix-valued predictors but are rather limited
for matrix-valued responses. In this article, we study matrix-variate
regressions for such data, where the response Y on each experimental unit is a
random matrix and the predictor X can be either a scalar, a vector, or a
matrix, treated as non-stochastic in terms of the conditional distribution Y|X.
We propose models for matrix-variate regressions and then develop envelope
extensions of these models. Under the envelope framework, redundant variation
can be eliminated in estimation and the number of parameters can be notably
reduced when the matrix-variate dimension is large, possibly resulting in
significant gains in efficiency. The proposed methods are applicable to high
dimensional settings.


title:
Weak and Strong Solutions to the Inverse-Square Brachistochrone Problem
  on Circular and Annular Domains

abstract:
  In this paper we study the brachistochrone problem in an inverse-square
gravitational field on the unit disk. We show that the time optimal solutions
consist of either smooth strong solutions to the Euler-Lagrange equation or
weak solutions formed by appropriately patched together strong solutions. This
combination of weak and strong solutions completely foliates the unit disk. We
also consider the problem on annular domains and show that the time optimal
paths foliate the annulus. These foliations on the annular domains converge to
the foliation on the unit disk in the limit of vanishing inner radius.


title: A diabatic definition of geometric phase effects

abstract:
  Electronic wave-functions in the adiabatic representation acquire nontrivial
geometric phases (GPs) when corresponding potential energy surfaces undergo
conical intersection (CI). These GPs have profound effects on the nuclear
quantum dynamics and cannot be eliminated in the adiabatic representation
without changing the physics of the system. To define dynamical effects arising
from the GP presence the nuclear quantum dynamics of the CI containing system
is compared with that of the system with artificially removed GP. We explore a
new construction of the system with removed GP via a modification of the
diabatic representation for the original CI containing system. Using an
absolute value function of diabatic couplings we remove the GP while preserving
adiabatic potential energy surfaces and CI. We assess GP effects in dynamics of
a two-dimensional linear vibronic coupling model both for ground and excited
state dynamics. Results are compared with those obtained with a conventional
removal of the GP by ignoring double-valued boundary conditions of the real
electronic wave-functions. Interestingly, GP effects appear similar in two
approaches only for the low energy dynamics. In contrast with the conventional
approach, a new approach does not have substantial GP effects in the ultra-fast
excited state dynamics.


title: Fully dynamic data structure for LCE queries in compressed space

abstract:
  A Longest Common Extension (LCE) query on a text $T$ of length $N$ asks for
the length of the longest common prefix of suffixes starting at given two
positions. We show that the signature encoding $\mathcal{G}$ of size $w =
O(\min(z \log N \log^* M, N))$ [Mehlhorn et al., Algorithmica 17(2):183-198,
1997] of $T$, which can be seen as a compressed representation of $T$, has a
capability to support LCE queries in $O(\log N + \log \ell \log^* M)$ time,
where $\ell$ is the answer to the query, $z$ is the size of the Lempel-Ziv77
(LZ77) factorization of $T$, and $M \geq 4N$ is an integer that can be handled
in constant time under word RAM model. In compressed space, this is the fastest
deterministic LCE data structure in many cases. Moreover, $\mathcal{G}$ can be
enhanced to support efficient update operations: After processing $\mathcal{G}$
in $O(w f_{\mathcal{A}})$ time, we can insert/delete any (sub)string of length
$y$ into/from an arbitrary position of $T$ in $O((y+ \log N\log^* M)
f_{\mathcal{A}})$ time, where $f_{\mathcal{A}} = O(\min \{ \frac{\log\log M
\log\log w}{\log\log\log M}, \sqrt{\frac{\log w}{\log\log w}} \})$. This yields
the first fully dynamic LCE data structure. We also present efficient
construction algorithms from various types of inputs: We can construct
$\mathcal{G}$ in $O(N f_{\mathcal{A}})$ time from uncompressed string $T$; in
$O(n \log\log n \log N \log^* M)$ time from grammar-compressed string $T$
represented by a straight-line program of size $n$; and in $O(z f_{\mathcal{A}}
\log N \log^* M)$ time from LZ77-compressed string $T$ with $z$ factors. On top
of the above contributions, we show several applications of our data structures
which improve previous best known results on grammar-compressed string
processing.


title: New Lessons from the HI Size-Mass Relation of Galaxies

abstract:
  We revisit the HI size-mass (D$_{\rm HI}$-M$_{\rm HI}$) relation of galaxies
with a sample of more than 500 nearby galaxies covering over five orders of
magnitude in HI mass and more than ten $B$-band magnitudes. The relation is
remarkably tight with a scatter $\sigma \sim$0.06 dex, or 14%. The scatter does
not change as a function of galaxy luminosity, HI richness or morphological
type. The relation is linked to the fact that dwarf and spiral galaxies have a
homogenous radial profile of HI surface density in the outer regions when the
radius is normalised by D$_{\rm HI}$. The early-type disk galaxies typically
have shallower HI radial profiles, indicating a different gas accretion
history. We argue that the process of atomic-to-molecular gas conversion or
star formation cannot explain the tightness of the D$_{\rm HI}$-M$_{\rm HI}$
relation. This simple relation puts strong constraints on simulation models for
galaxy formation.


title:
Hardy's uncertainty principle and unique continuation property for
  stochastic heat equations

abstract:
  The goal of this paper is to prove a uniqueness result for a stochastic heat
equation with a randomly perturbed potential, which can be considered as a
variant of Hardy's uncertainty principle for stochastic heat evolutions.


title:
SCOUT: simultaneous time segmentation and community detection in dynamic
  networks

abstract:
  Many evolving complex systems can be modeled via dynamic networks. An
important problem in dynamic network research is community detection, which
identifies groups of topologically related nodes. Typically, this problem is
approached by assuming either that each time point has a distinct community
organization or that all time points share one community organization. In
reality, the truth likely lies between these two extremes, since some time
periods can have community organization that evolves while others can have
community organization that stays the same. To find the compromise, we consider
community detection in the context of the problem of segment detection, which
identifies contiguous time periods with consistent network structure.
Consequently, we formulate a combined problem of segment community detection
(SCD), which simultaneously partitions the network into contiguous time
segments with consistent community organization and finds this community
organization for each segment. To solve SCD, we introduce SCOUT, an
optimization framework that explicitly considers both segmentation quality and
partition quality. SCOUT addresses limitations of existing methods that can be
adapted to solve SCD, which typically consider only one of segmentation quality
or partition quality. In a thorough evaluation, SCOUT outperforms the existing
methods in terms of both accuracy and computational complexity.


title: Interpolation of Varieties of Minimal Degree

abstract:
  It is well known that one can find a rational normal curve in $\mathbb P^n$
through $n+3$ general points. We prove a generalization of this to higher
dimensional varieties, showing that smooth varieties of minimal degree can be
interpolated through points and linear spaces.


title:
Lessons from the Onset of a Common Envelope Episode: the Remarkable M31
  2015 Luminous Red Nova Outburst

abstract:
  This paper investigates the recent stellar merger transient M31LRN 2015 in
the Andromeda galaxy. We analyze published optical photometry and spectroscopy
along with a Hubble Space Telescope detection of the color and magnitude of the
pre-outburst source. The transient outburst is consistent with dynamically
driven ejecta at the onset of a common envelope episode, which eventually leads
to the complete merger of a binary system. The light curve appears to contain
two components: first $\sim10^{-2} M_\odot$ of fast ejecta driven by shocks at
the onset of common envelope, and later, $\sim0.3 M_\odot$ of further ejecta as
the secondary becomes more deeply engulfed within the primary. Just prior to
merger, we find that the primary star is a $3-5.5 M_\odot$ sub-giant branch
primary star with radius of $30-40R_\odot$. Its position in the color-magnitude
diagram shows that it is growing in radius, consistent with a picture where it
engulfs its companion. By matching the properties of the primary star to the
transient outburst, we show that the optical transient lasts less than ten
orbits of the original binary, which had a pre-merger period of $\sim 10$ days.
We consider the possible orbital dynamics leading up to the merger, and argue
that if the system merged due to the Darwin tidal instability it implies a
lower mass main sequence companion of $0.1-0.6M_\odot$. This analysis
represents a promising step toward a more detailed understanding of flows in
common envelope episodes through direct observational constraints.


title:
Remarks on the H\"older-continuity of solutions to parabolic equations
  with conic singularities

abstract:
  This is a note on \cite{LSU} and \cite{FS}. Using their work line by line, we
prove the H\"older-continuity of solutions to linear parabolic equations of
mixed type, assuming the coefficient of $\frac{\partial}{\partial t}$ has
time-derivative bounded from above. On a K\"ahler manifold, this H\"older
estimate works when the metrics possess conic singularities along a normal
crossing divisor.


title:
First-principles evaluation of intrinsic, side-jump, and skew-scattering
  parts of anomalous Hall conductivities in disordered alloys

abstract:
  We develop a first-principles procedure for the individual evaluation of the
intrinsic, side-jump, and skew-scattering contributions to the anomalous Hall
conductivity $\sigma_{xy}$. This method is based on the different microscopic
conductive processes of each origin of $\sigma_{xy}$ in the Kubo--Bastin
formula. We also present an approach for implementing this scheme in the
tight-binding linear muffin-tin orbital (TB-LMTO) method with the coherent
potential approximation (CPA). The validity of this calculation method is
demonstrated for disordered FePt and FePd alloys. We find that the estimated
value of each origin of $\sigma_{xy}$ exhibits reasonable dependencies on the
electron scattering in these disordered alloys.


title:
Controlling the Numerical Cerenkov Instability in PIC simulations using
  a customized finite difference Maxwell solver and a local FFT based current
  correction

abstract:
  In this paper we present a customized finite-difference-time-domain (FDTD)
Maxwell solver for the particle-in-cell (PIC) algorithm. The solver is
customized to effectively eliminate the numerical Cerenkov instability (NCI)
which arises when a plasma (neutral or non-neutral) relativistically drifts on
a grid when using the PIC algorithm. We control the EM dispersion curve in the
direction of the plasma drift of a FDTD Maxwell solver by using a customized
higher order finite difference operator for the spatial derivative along the
direction of the drift ($\hat 1$ direction). We show that this eliminates the
main NCI modes with moderate $\vert k_1 \vert$, while keeps additional main NCI
modes well outside the range of physical interest with higher $\vert k_1
\vert$. These main NCI modes can be easily filtered out along with first
spatial aliasing NCI modes which are also at the edge of the fundamental
Brillouin zone. The customized solver has the possible advantage of improved
parallel scalability because it can be easily partitioned along $\hat 1$ which
typically has many more cells than other directions for the problems of
interest. We show that FFTs can be performed locally to current on each
partition to filter out the main and first spatial aliasing NCI modes, and to
correct the current so that it satisfies the continuity equation for the
customized spatial derivative. This ensures that Gauss' Law is satisfied. We
present simulation examples of one relativistically drifting plasmas, of two
colliding relativistically drifting plasmas, and of nonlinear laser wakefield
acceleration (LWFA) in a Lorentz boosted frame that show no evidence of the NCI
can be observed when using this customized Maxwell solver together with its NCI
elimination scheme.


title:
The Commutativity Problem of the MapReduce Framework: A Transducer-based
  Approach

abstract:
  MapReduce is a popular programming model for data parallel computation. In
MapReduce, the reducer produces an output from a list of inputs. Due to the
scheduling policy of the platform, the inputs may arrive at the reducers in
different order. The commutativity problem of reducers asks if the output of a
reducer is independent of the order of its inputs. Although the problem is
undecidable in general, the MapReduce programs in practice are usually used for
data analytics and thus require very simple control flow. By exploiting the
simplicity, we propose a programming language for reducers where the
commutativity problem is decidable. The main idea of the reducer language is to
separate the control and data flow of programs and disallow arithmetic
operations in the control flow. The decision procedure for the commutativity
problem is obtained through a reduction to the equivalence problem of streaming
numerical transducers (SNTs), a novel automata model over infinite alphabets
introduced in this paper. The design of SNTs is inspired by streaming
transducers (Alur and Cerny, POPL 2011). Nevertheless, the two models are
intrinsically different since the outputs of SNTs are integers while those of
streaming transducers are data words. The decidability of the equivalence of
SNTs is achieved with an involved combinatorial analysis of the evolvement of
the values of the integer variables during the runs of SNTs.


title:
The Gender Balance of the Australian Space Research Community: A
  Snapshot From The 15th ASRC, 2015

abstract:
  In recent years, the striking gender imbalance in the physical sciences has
been a topic for much debate. National bodies and professional societies in the
astronomical and space sciences are now taking active steps to understand and
address this imbalance. In order to begin this process in the Australian Space
Research community, we must first understand the current state of play. In this
work, we therefore present a short 'snapshot' of the current gender balance in
our community, as observed at the 15th Australian Space Research Conference.
  We find that, at this year's conference, male attendees outnumbered female
attendees by a ratio of 3:1 (24% female). This gender balance was repeated in
the distribution of conference talks and plenary presentations (25 and 22%
female, respectively). Of the thirteen posters presented at the conference,
twelve were presented by men (92%), a pattern repeated in the awards for the
best student presentations (seven male recipients vs one female). The program
and organising committees for the meeting fairly represented the gender balance
of the conference attendees (28% and 30% female, respectively). These figures
provide a baseline for monitoring future progress in increasing the
participation of women in the field. They also suggest that the real barrier is
not speaking, but in enabling conference attendance and retaining female
scientists through their careers - in other words, addressing and repairing the
'leaky pipeline'.


title: Rainbow Rindler metric and Unruh effect

abstract:
  The energy of a particle moving on a spacetime, in principle, can affect the
background metric. The modifications to it depend on the ratio of energy of the
particle and the Planck energy, known as rainbow gravity. Here we find the
explicit expressions for the coordinate transformations from rainbow Minkowski
spacetime to accelerated frame. The corresponding metric is also obtained which
we call as rainbow-Rindler metric. So far we are aware of, no body has done it
in a concrete manner. Here this is found from the first principle and hence all
the parameters are properly identified. The advantage of this is that the
calculated Unruh temperature is compatible with the Hawking temperature of the
rainbow black hole horizon, obtained earlier. Since the accelerated frame has
several importance in revealing various properties of gravity, we believe that
the present result will not only fill that gap, but also help to explore
different aspects of rainbow gravity paradigm.