title: Stellar Streams and Clouds in the Galactic Halo

abstract:
  Recent years have seen the discovery of an ever growing number of stellar
debris streams and clouds. These structures are typically detected as extended
and often curvilinear overdensities of metal-poor stars that stand out from the
foreground disk population. The streams typically stretch tens of degrees or
more across the sky, even encircling the Galaxy, and range in heliocentric
distance from 3 to 100 kpc. This chapter summarizes the techniques used for
finding such streams and provides tables giving positions, distances,
velocities, and metallicities, where available, for all major streams and
clouds that have been detected as of January 2015. Sky maps of the streams are
also provided. Properties of individual tidal debris structures are discussed.


title: Homotopically Invisible Singular Curves

abstract:
  Given a smooth manifold $M$ and a totally nonholonomic distribution
$\Delta\subset TM$ of rank $d$, we study the effect of singular curves on the
topology of the space of horizontal paths joining two points on $M$. Singular
curves are critical points of the endpoint map $F:\gamma\mapsto\gamma(1)$
defined on the space $\Omega$ of horizontal paths starting at a fixed point
$x$. We consider a subriemannian energy $J:\Omega(y)\to\mathbb R$, where
$\Omega(y)=F^{-1}(y)$ is the space of horizontal paths connecting $x$ with $y$,
and study those singular paths that do not influence the homotopy type of the
Lebesgue sets $\{\gamma\in\Omega(y)\,|\,J(\gamma)\le E\}$. We call them
homotopically invisible. It turns out that for $d\geq 3$ generic subriemannian
structures have only homotopically invisible singular curves. Our results can
be seen as a first step for developing the calculus of variations on the
singular space of horizontal curves (in this direction we prove a subriemannian
Minimax principle and discuss some applications).


title: Categorical actions and crystals

abstract:
  This is an expository article developing some aspects of the theory of
categorical actions of Kac-Moody algebras in the spirit of works of
Chuang-Rouquier, Khovanov-Lauda, Webster, and many others.


title: Tachyons in Classical de Sitter Vacua

abstract:
  We revisit the possibility of de Sitter vacua and slow-roll inflation in type
II string theory at the level of the classical two-derivative supergravity
approximation. Previous attempts at explicit constructions were plagued by
ubiquitous tachyons with a large $\eta$ parameter whose origin has not been
fully understood so far. In this paper, we determine and explain the tachyons
in two setups that are known to admit unstable dS critical points: an SU(3)
structure compactification of massive type IIA with O6-planes and an SU(2)
structure compactification of type IIB with O5/O7-planes. We explicitly show
that the tachyons are always close to, but never fully aligned with the
sgoldstino direction in the considered examples and argue that this behavior is
explained by a generalized version of a no-go theorem by Covi et al, which
holds in the presence of large mixing in the mass matrix between the sgoldstino
and the orthogonal moduli. This observation may also provide a useful stability
criterion for general dS vacua in supergravity and string theory.


title:
Inflight Radiometric Calibration of New Horizons' Multispectral Visible
  Imaging Camera (MVIC)

abstract:
  We discuss two semi-independent calibration techniques used to determine the
in-flight radiometric calibration for the New Horizons' Multi-spectral Visible
Imaging Camera (MVIC). The first calibration technique compares the observed
stellar flux to modeled values. The difference between the two provides a
calibration factor that allows the observed flux to be adjusted to the expected
levels for all observations, for each detector. The second calibration
technique is a channel-wise relative radiometric calibration for MVIC's blue,
near-infrared and methane color channels using observations of Charon and
scaling from the red channel stellar calibration. Both calibration techniques
produce very similar results (better than 7% agreement), providing strong
validation for the techniques used. Since the stellar calibration can be
performed without a color target in the field of view and covers all of MVIC's
detectors, this calibration was used to provide the radiometric keywords
delivered by the New Horizons project to the Planetary Data System (PDS). These
keywords allow each observation to be converted from counts to physical units;
a description of how these keywords were generated is included. Finally,
mitigation techniques adopted for the gain drift observed in the near-infrared
detector and one of the panchromatic framing cameras is also discussed.


title:
The identification of post-starburst galaxies at z~1 using
  multiwavelength photometry: a spectroscopic verification

abstract:
  Despite decades of study, we still do not fully understand why some massive
galaxies abruptly switch off their star formation in the early Universe, and
what causes their rapid transition to the red sequence. Post-starburst galaxies
provide a rare opportunity to study this transition phase, but few have
currently been spectroscopically identified at high redshift ($z>1$). In this
paper we present the spectroscopic verification of a new photometric technique
to identify post-starbursts in high-redshift surveys. The method classifies the
broad-band optical-near--infrared spectral energy distributions (SEDs) of
galaxies using three spectral shape parameters (super-colours), derived from a
principal component analysis of model SEDs. When applied to the multiwavelength
photometric data in the UKIDSS Ultra Deep Survey (UDS), this technique
identified over 900 candidate post-starbursts at redshifts $0.5<z<2.0$. In this
study we present deep optical spectroscopy for a subset of these galaxies, in
order to confirm their post-starburst nature. Where a spectroscopic assessment
was possible, we find the majority (19/24 galaxies; ~80 per cent) exhibit the
strong Balmer absorption (H $\delta$ equivalent width $W_{\lambda}$ >5 Ang.)
and Balmer break, characteristic of post-starburst galaxies. We conclude that
photometric methods can be used to select large samples of recently-quenched
galaxies in the distant Universe.


title:
Chromatic line-profile tomography to reveal exoplanetary atmospheres:
  application to HD 189733b

abstract:
  Transmission spectroscopy can be used to constrain the properties of
exoplanetary atmospheres. During a transit, the light blocked from the
atmosphere of the planet leaves an imprint in the light coming from the star.
This has been shown for many exoplanets with different techniques, with both
photometry and spectroscopy. We aim at testing chromatic line-profile
tomography as a new tool to investigate exoplanetary atmospheres. The signal
imprinted on the cross-correlation function (CCF) by a planet transiting its
star is dependent on the planet-to-star radius ratio. We want to verify if the
precision reachable on the CCF obtained from a subset of the spectral orders of
the HARPS spectrograph is enough to discriminate the radius of a planet at
different wavelengths. Methods. We analyze HARPS archival data of three
transits of HD 189733b. We divide the HARPS spectral range in 7 broadbands,
calculating for each band the ratio between the area of the out-of-transit CCF
and the area of the signal imprinted by the planet on it during the full part
of the transit. We take into account the effect of the limb darkening using the
theoretical coefficients of a linear law. Averaging the results of three
different transits allows us to obtain a good quality broadband transmission
spectrum of HD 189733b, with a precision greater than that of the chromatic RM
effect. Results. We proved chromatic line-profile tomography to be an
interesting way to reveal broadband transmission spectra of exoplanets: our
analysis of the atmosphere of HD 189733b is in agreement with other ground- and
space-based observations. The independent analysis of different transits puts
in evidence the probability that stellar activity plays a role in the extracted
transmission spectrum. Care has thus to be taken when claiming for Rayleigh
scattering in the atmosphere of exoplanets orbiting active stars using only one
transit.


title: Publication statistics on Sun and heliosphere

abstract:
  The professional literature provides one means to review the evolution and
geographic distribution of the scientific communities engaged in solar and
heliospheric physics. With help of the Astrophysics Data System (NASA/ADS), I
trace the growth of the research community over the past century from a few
dozen researchers early in the 20-th Century to over 4,000 names with over
refereed 2,000 publications in recent years, with 90% originating from 20
countries, being published in 90 distinct journals. Overall, the lead authors
of these publications have their affiliations for 45% in Europe, 29% in the
Americas, 24% in Australasia, and 2% in Africa and Arab countries. Publications
most frequently appear (in decreasing order) in the Astrophysical Journal, the
Journal of Geophysical Research (Space Physics), Solar Physics, Astronomy and
Astrophysics, and Advances in Space Research (adding up to 59% of all
publications in 2015).


title: Quantum metrology with full and fast quantum control

abstract:
  We establish general limits on how precise a parameter, e.g. frequency or the
strength of a magnetic field, can be estimated with the aid of full and fast
quantum control. We consider uncorrelated noisy evolutions of N qubits and show
that fast control allows to fully restore the Heisenberg scaling (~1/N^2) for
all rank-one Pauli noise except dephasing. For all other types of noise the
asymptotic quantum enhancement is unavoidably limited to a constant-factor
improvement over the standard quantum limit (~1/N) even when allowing for the
full power of fast control. The latter holds both in the single-shot and
infinitely-many repetitions scenarios. However, even in this case allowing for
fast quantum control helps to increase the improvement factor. Furthermore, for
frequency estimation with finite resource we show how a parallel scheme
utilizing any fixed number of entangled qubits but no fast quantum control can
be outperformed by a simple, easily implementable, sequential scheme which only
requires entanglement between one sensing and one auxiliary qubit.


title: On two-time distribution functions in (1+1) random directed polymers

abstract:
  The asymptotic analytic expression for the two-time free energy distribution
function in (1+1) random directed polymers is derived in the limit when the two
times are close to each other


title: Color Instabilities in the Quark-Gluon Plasma

abstract:
  When the quark-gluon plasma (QGP) - a system of deconfined quarks and gluons
- is in a nonequilibrium state, it is usually unstable with respect to color
collective modes. The instabilities, which are expected to strongly influence
dynamics of the QGP produced in relativistic heavy-ion collisions, are
extensively discussed under the assumption that the plasma is weakly coupled.
We begin by presenting the theoretical approaches to study the QGP, which
include: field theory methods based on the Keldysh-Schwinger formalism,
classical and kinetic theories, and fluid techniques. The dispersion equations,
which give the spectrum of plasma collective excitations, are analyzed in
detail. Particular attention is paid to a momentum distribution of plasma
constituents which is obtained by deforming an isotropic momentum distribution.
Mechanisms of chromoelectric and chromomagnetic instabilities are explained in
terms of elementary physics. The Nyquist analysis, which allows one to
determine the number of solutions of a dispersion equation without explicitly
solving it, and stability criteria are also discussed. We then review various
numerical approaches - purely classical or quantum - to simulate the temporal
evolution of an unstable quark-gluon plasma. The dynamical role of
instabilities in the processes of plasma equilibration is analyzed.


title:
Spin crossover in (Mg,Fe$^{3+}$)(Si,Fe$^{3+}$)O$_3$ bridgmanite: effects
  of disorder, iron concentration, and temperature

abstract:
  The spin crossover of iron in Fe$^{3+}$-bearing bridgmanite, the most
abundant mineral of the Earth's lower mantle, is by now a well-established
phenomenon, though several aspects of this crossover remain unclear. Here we
investigate effects of disorder, iron concentration, and temperature on this
crossover using ab initio LDA + U$_{sc}$ calculations. The effect of
concentration and disorder are addressed using complete statistical samplings
of coupled substituted configurations in super-cells containing up to 80 atoms.
Vibrational/thermal effects on the crossover are addressed within the
quasiharmonic approximation. The effect of disorder seems quite small, while
increasing iron concentration results in considerable increase in crossover
pressure. Our calculated compression curves for iron-free, Fe$^{2+}$-, and
Fe$^{3+}$-bearing bridgmanite compare well with the latest experimental
measurements. The comparison also suggests that in a close system, Fe$^{2+}$
present in the sample may transform into Fe$^{3+}$ by introduction of Mg and O
vacancies with increasing pressure. As in the spin crossover in ferropericlase,
this crossover in bridgmanite is accompanied by a clear volume reduction and an
anomalous softening of the bulk modulus throughout the crossover pressure
range. These effects reduce significantly with increasing temperature. Though
the concentration of [Fe$^{3+}$]$_{Si}$ in bridgmanite may be small, related
elastic anomalies may impact the interpretation of radial and lateral velocity
structures of the Earth's lower mantle.


title: The stationary measure for diagonal quantum walk with one defect

abstract:
  This study is motivated by the previous work [14]. We treat 3 types of the
one-dimensional quantum walks (QWs), whose time evolutions are described by
diagonal unitary matrix, and diagonal unitary matrices with one defect. In this
paper, we call the QW defined by diagonal unitary matrices, "the diagonal QW",
and we consider the stationary distributions of generally 2-state diagonal QW
with one defect, 3-state space-homogeneous diagonal QW, and 3-state diagonal QW
with one defect. One of the purposes of our study is to characterize the QWs by
the stationary measure, which may lead to answer the basic and natural
question, "What the stationary measure is for one-dimensional QWs ?". In order
to analyze the stationary distribution, we focus on the corresponding
eigenvalue problems and the definition of the stationary measure.


title: The While language

abstract:
  This article presents a formalisation of a simple imperative programming
language. The objective is to study and develop "hands-on" a formal
specifcation of a programming language, namely its syntax, operational
semantics and type system. To have an executable version of the language, we
implemented in Racket its operational semantics and type system.


title:
Optomechanical measurement of photon spin angular momentum and optical
  torque in integrated photonic devices

abstract:
  Photons carry linear momentum, and spin angular momentum when circularly or
elliptically polarized. During light-matter interaction, transfer of linear
momentum leads to optical forces, while angular momentum transfer induces
optical torque. Optical forces including radiation pressure and gradient forces
have long been utilized in optical tweezers and laser cooling. In nanophotonic
devices optical forces can be significantly enhanced, leading to unprecedented
optomechanical effects in both classical and quantum regimes. In contrast, to
date, the angular momentum of light and the optical torque effect remain
unexplored in integrated photonics. Here, we demonstrate the measurement of the
spin angular momentum of photons propagating in a birefringent waveguide and
the use of optical torque to actuate rotational motion of an optomechanical
device. We show that the sign and magnitude of the optical torque are
determined by the photon polarization states that are synthesized on the chip.
Our study reveals the mechanical effect of photon's polarization degree of
freedom and demonstrates its control in integrated photonic devices. Exploiting
optical torque and optomechanical interaction with photon angular momentum can
lead to torsional cavity optomechanics and optomechanical photon spin-orbit
coupling, as well as applications such as optomechanical gyroscope and
torsional magnetometry.


title:
Quantum mechanical violation of macrorealism for large spin and its
  robustness against coarse-grained measurements

abstract:
  For multilevel spin systems, robustness of the quantum mechanical (QM)
violation of macrorealism (MR) with respect to coarse grained measurements is
investigated using three different necessary conditions of MR, namely, the
Leggett-Garg inequality (LGI), Wigner's form of the Leggett-Garg inequality
(WLGI) and the condition of no-signalling in time (NSIT). It is shown that for
dichotomic sharp measurements, in the asymptotic limit of spin, the algebraic
maxima of the QM violations of all these three necessary conditions of MR are
attained. Importantly, the QM violations of all these persist in that limit
even for \textit{arbitrary} unsharp measurements, i.e. for any non zero value
of the sharpness parameter characterizing the degree of fuzziness of the
relevant measurements. We also find that when different measurement outcomes
are clubbed into two groups for the sake of dichotomising the outcomes, the
asymmetry/symmetry in the number of outcomes in the two groups, signifying the
degree of coarse graining of measurements, has a crucial role in discerning
quantum violation of MR. The results clearly demonstrate that classicality does
not emerges in the asymptotic limit of spin, whatever be the unsharpness and
degree of coarse graining of the measurements.


title: RNA Folding Pathways in Stop Motion

abstract:
  We introduce a method for predicting RNA folding pathways, with an
application to the most important RNA tetraloops. The method is based on the
idea that ensembles of three-dimensional fragments extracted from
high-resolution crystal structures are heterogeneous enough to describe
metastable as well as intermediate states. These ensembles are first validated
by performing a quantitative comparison against available solution NMR data of
a set of RNA tetranucleotides. Notably, the agreement is better with respect to
the one obtained by comparing NMR with extensive all-atom molecular dynamics
simulations. We then propose a procedure based on diffusion maps and Markov
models that makes it possible to obtain reaction pathways and their relative
probabilities from fragment ensembles. This approach is applied to study the
helix-to-loop folding pathway of all the tetraloops from the GNRA and UNCG
families. The results give detailed insights into the folding mechanism that
are compatible with available experimental data and clarify the role of
intermediate states observed in previous simulation studies. The method is
computationally inexpensive and can be used to study arbitrary conformational
transitions.

categories: q-bio.BM physics.bio-ph physics.chem-ph physics.comp-ph


title:
The diversity of Type II supernova versus the similarity in their
  progenitors

abstract:
  High-quality collections of Type II supernova (SN) light curves are scarce
because they evolve for hundreds of days, making follow-up observations time
consuming and often extending over multiple observing seasons. In light of
these difficulties, the diversity of SNe II is not fully understood. Here we
present ultraviolet and optical photometry of 12 SNe II monitored by the Las
Cumbres Observatory Global Telescope Network (LCOGT) during 2013-2014, and
compare them with previously studied SNe having well-sampled light curves. We
explore SN II diversity by searching for correlations between the slope of the
linear light-curve decay after maximum light (historically used to divide SNe
II into IIL and IIP) and other measured physical properties. While SNe IIL are
found to be on average more luminous than SNe IIP, SNe IIL do not appear to
synthesize more 56Ni than SNe IIP. Finally, optical nebular spectra obtained
for several SNe in our sample are found to be consistent with models of red
supergiant progenitors in the 12-16 Msun range. Consequently, SNe IIL appear
not to account for the deficit of massive red supergiants as SN II progenitors.


title: On the parametric behavior of A-hypergeometric series

abstract:
  We describe the parametric behavior of the series solutions of an
A-hypergeometric system. More precisely, we construct explicit stratifications
of the parameter space such that, on each stratum, the series solutions of the
system are holomorphic.


title:
Theoretical Physics Implications of the Binary Black-Hole Mergers
  GW150914 and GW151226

abstract:
  The gravitational wave observations GW150914 and GW151226 by Advanced LIGO
provide the first opportunity to learn about physics in the extreme gravity
environment of coalescing binary black holes. The LIGO Scientific Collaboration
and the Virgo Collaboration have verified that this observation is consistent
with General Relativity. This paper expands their analysis to a larger class of
anomalies, highlighting the inferences that can be drawn on non-standard
theoretical physics mechanisms. We find that these events constrain a plethora
of mechanisms associated with the generation and propagation of gravitational
waves, including the activation of scalar fields, gravitational leakage into
large extra dimensions, the variability of Newton's constant, a modified
dispersion relation, gravitational Lorentz violation and the strong equivalence
principle. Though other observations limit many of these mechanisms already,
GW150914 and GW151226 are unique in that they are direct probes of dynamical
strong-field gravity and of gravitational wave propagation. We also show that
GW150914 constrains inferred properties of exotic compact object alternatives
to Kerr black holes. We argue, however, that the true potential for GW150914 to
both rule out exotic objects and constrain physics beyond General Relativity is
severely limited by the lack of understanding of the merger regime in almost
all relevant modified gravity theories. This event thus significantly raises
the bar that these theories have to pass, both in terms of having a sound
theoretical underpinning, and being able to solve the equations of motion for
binary merger events. We conclude with a discussion of the additional
inferences that can be drawn if the lower-confidence observation of an
electromagnetic counterpart to GW150914 holds true; this would provide dramatic
constraints on the speed of gravity and gravitational Lorentz violation.


title: Simulating radially outward winds within a turbulent gas clump

abstract:
  By using the particle-based code Gadget2, we follow the evolution of a gas
clump, in which a gravitational collapse is initially induced. The particles
representing the gas clump have initially a velocity according to a turbulent
spectrum built in a Fourier space of 64$^3$ grid elements. In a very early
stage of evolution of the clump, a set of gas particles representing the wind,
suddenly move outwards from the clump's center. We consider only two kinds of
winds, namely: one with spherical symmetry and a second one being a bipolar
collimated jet. In order to assess the dynamical change in the clump due to
interaction with the winds, we show iso-velocity and iso-density plots for all
our simulations.


title: Bisous model - detecting filamentary patterns in point processes

abstract:
  The cosmic web is a highly complex geometrical pattern, with galaxy clusters
at the intersection of filaments and filaments at the intersection of walls.
Identifying and describing the filamentary network is not a trivial task due to
the overwhelming complexity of the structure, its connectivity and the
intrinsic hierarchical nature. To detect and quantify galactic filaments we use
the Bisous model, which is a marked point process built to model
multi-dimensional patterns. The Bisous filament finder works directly with the
galaxy distribution data and the model intrinsically takes into account the
connectivity of the filamentary network. The Bisous model generates the visit
map (the probability to find a filament at a given point) together with the
filament orientation field. Using these two fields, we can extract filament
spines from the data. Together with this paper we publish the computer code for
the Bisous model that is made available in GitHub. The Bisous filament finder
has been successfully used in several cosmological applications and further
development of the model will allow to detect the filamentary network also in
photometric redshift surveys, using the full redshift posterior. We also want
to encourage the astro-statistical community to use the model and to connect it
with all other existing methods for filamentary pattern detection and
characterisation.


title:
Effects of Antenna Beam Chromaticity on Redshifted 21~cm Power Spectrum
  and Implications for Hydrogen Epoch of Reionization Array

abstract:
  Unaccounted for systematics from foregrounds and instruments can severely
limit the sensitivity of current experiments from detecting redshifted 21~cm
signals from the Epoch of Reionization (EoR). Upcoming experiments are faced
with a challenge to deliver more collecting area per antenna element without
degrading the data with systematics. This paper and its companions show that
dishes are viable for achieving this balance using the Hydrogen Epoch of
Reionization Array (HERA) as an example. Here, we specifically identify
spectral systematics associated with the antenna power pattern as a significant
detriment to all EoR experiments which causes the already bright foreground
power to leak well beyond ideal limits and contaminate the otherwise clean EoR
signal modes. A primary source of this chromaticity is reflections in the
antenna-feed assembly and between structures in neighboring antennas. Using
precise foreground simulations taking wide-field effects into account, we
provide a framework to set cosmologically-motivated design specifications on
these reflections to prevent further EoR signal degradation. We show HERA will
not be impeded by such spectral systematics and demonstrate that even in a
conservative scenario that does not perform removal of foregrounds, HERA will
detect EoR signal in line-of-sight $k$-modes, $k_\parallel \gtrsim
0.2\,h$~Mpc$^{-1}$, with high significance. All baselines in a 19-element HERA
layout are capable of detecting EoR over a substantial observing window on the
sky.


title: Proposal for an experiment to demonstrate the block universe

abstract:
  While the concept of the block universe has a most respectable scientific
provenance, many physicists nevertheless do not accept that future events are
just as embedded in spacetime as are those of the present and the past. This
paper proposes an experiment to demonstrate the block universe using
interplanetary distances and high relative speeds such as those accessible
through the NASA Mars Reconnaissance Orbiter. The proposed experiment hinges on
signals exchanged between Earth and the Orbiter which reveal a time interval of
some tens of milliseconds in the future of the Earth which is already in the
past of the Orbiter. Since this experiment can be performed at any time, and
since the magnitude of the time interval can in principle be increased in
proportion to the distances and speeds over which it is performed, an observer
can always be found for whom the past is in the future of another observer. The
only explanation that fits these observations is a block universe in which all
events in the past, present and future of any observer are equally enfolded
into spacetime.


title: Mechanical wave momentum from the first principles

abstract:
  For steady-state and some other types of mechanical waves of an arbitrary
form, intensity and nature, propagating in a free uniform waveguide, we present
the following. Relations for the axial momentum as it directly follows from the
conservation laws. The mass associated with the wave. The connection between
the wave energy and momentum. The structure of a binary wave which possesses a
self-equilibrated momentum, in particular, a transverse-longitudinal wave
formed upon excitation of flexural waves. Conditions under which longitudinal
sinusoidal waves can carry momentum and the physical meaning of the so-called
"wave momentum".


title: Betting and Belief: Prediction Markets and Attribution of Climate Change

abstract:
  Despite much scientific evidence, a large fraction of the American public
doubts that greenhouse gases are causing global warming. We present a
simulation model as a computational test-bed for climate prediction markets.
Traders adapt their beliefs about future temperatures based on the profits of
other traders in their social network. We simulate two alternative climate
futures, in which global temperatures are primarily driven either by carbon
dioxide or by solar irradiance. These represent, respectively, the scientific
consensus and a hypothesis advanced by prominent skeptics. We conduct
sensitivity analyses to determine how a variety of factors describing both the
market and the physical climate may affect traders' beliefs about the cause of
global climate change. Market participation causes most traders to converge
quickly toward believing the "true" climate model, suggesting that a climate
market could be useful for building public consensus.


title:
A duality of the classical action yields a reflection symmetry of the
  quantum energy spectrum

abstract:
  The concept of duality reflects a link between two seemingly different
physical objects. An example in quantum mechanics is a situation where the
spectra (or their parts) of two Hamiltonians go into each other under a certain
transformation. We term this phenomenon as the energy-spectrum reflection
symmetry.
  We develop an approach to this class of problems, based on the global
properties of the Riemann surface of the quantum momentum function, a natural
quantum-mechanical analogue to the classical momentum. In contrast to the
algebraic method, which we also briefly review, our treatment provides an
explanation to the long-noticed matching of the perturbative and WKB expansions
of dual energy levels. Our technique also reveals the classical origins of
duality.


title:
Remote preparation of three-photon entangled states via single-photon
  measurement

abstract:
  Remote state preparation (RSP) provides an indirect way of manipulating
quantum information based on the nonlocal effect of quantum measurement.
Although RSP has been demonstrated in recent years to remotely prepare
multi-photon states, quantum measurement on the same number of photons was
required, i.e., to prepare N-photon states via RSP, quantum measurement on the
other N-photons was required, hence significantly limiting practicality and
applicability of RSP. Here we report the first experimental demonstration of
remote preparation of three-photon entangled states by measuring only a
single-photon entangled with the three photons. We further generalize our
protocol to prepare multi-photon entangled states with arbitrary photon number
and purity via single-photon measurement. As our RSP scheme relies on the
nonlinearity induced by single-photon measurement, it enables quantum state
engineering of multi-photon entangled states beyond the linear optical limit.
Our results are expected to have significant impacts on quantum metrology and
quantum information processing.


title: A "cousin" of a theorem of Cs\'aki and Fischer

abstract:
  A 1963 theorem of P. Cs\'aki and J. Fischer deals with the "maximal
correlation coefficient" in the context of independent pairs of $\sigma$-fields
on a probability space. Here a somewhat restricted "cousin" of their result is
presented for the same context, but involving in part an analogous measure of
dependence based only on correlations of indicator functions. It was first
proved by the author in an unpublished 1978 Ph.D. thesis. An example is
constructed to show a limitation of this "cousin". Also, this "cousin" is used
to trivially embellish a very sharp 2013 example of R. Peyre in connection with
the comparison of these two measures of dependence.


title:
Existence of weak solutions for compressible Navier-Stokes equations
  with entropy transport

abstract:
  We consider the compressible Navier-Stokes system with variable entropy. The
pressure is a nonlinear function of the density and the entropy/potential
temperature which, unlike in the Navier-Stokes-Fourier system, satisfies only
the transport equation. We provide existence results within three alternative
weak formulations of the corresponding classical problem. Our constructions
hold for the optimal range of the adiabatic coefficients from the point of view
of the nowadays existence theory.


title: Stochastic theory of quantum mechanics and the Schr\"odinger equation

abstract:
  We have advocated in a previous paper (Godart M. arXiv: 1206.2917v2[quant-ph]
) a version of the stochastic theory of quantum mechanics. It is indirectly
based on a method proposed by Nelson to associate a Markov process with any
solution of the Schroedinger equation. The debate began very soon on the
question to know if the new theory based on that stochastic procees was
equivalent to the orthodox Copenhagen version. We conclude in this paper that
the answer is in the negative in agreement with the opinion of several
physicists. We show however that the elementary solutions of the Schroedinger
equation can be recovered formally from the stochastic theory in a great number
of particular cases. We confirm also that this equation is no longer valid when
a magnetic field is at work and that it must then give way to some other
equation.


title:
Direct measurement of the electron energy relaxation dynamics in
  metallic wires

abstract:
  We present measurements of the dynamical response of thermal noise to an ac
excitation in conductors at low temperature. From the frequency dependence of
this response function - the noise thermal impedance - in the range 1 kHz-1 GHz
we obtain direct determinations of the inelastic relaxation times relevant in
metallic wires at low temperature: the electron-phonon scattering time and the
diffusion time of electrons along the wires. Combining these results with that
of resistivity provides a measurement of heat capacity of samples made of thin
film. The simplicity and reliability of this technique makes it very promising
for future applications in other systems.


title:
FAST: A Framework to Accelerate Super-Resolution Processing on
  Compressed Videos

abstract:
  State-of-the-art super-resolution (SR) algorithms require significant
computational resources to achieve real-time throughput (e.g., 60Mpixels/s for
HD video). This paper introduces FAST (Free Adaptive Super-resolution via
Transfer), a framework to accelerate any SR algorithm applied to compressed
videos. FAST exploits the temporal correlation between adjacent frames such
that SR is only applied to a subset of frames; SR pixels are then transferred
to the other frames. The transferring process has negligible computation cost
as it uses information already embedded in the compressed video (e.g., motion
vectors and residual). Adaptive processing is used to retain accuracy when the
temporal correlation is not present (e.g., occlusions). FAST accelerates
state-of-the-art SR algorithms by up to 15x with a visual quality loss of
0.2dB. FAST is an important step towards real-time SR algorithms for ultra-HD
displays and energy constrained devices (e.g., phones and tablets).


title:
MIMO Radar Target Localization and Performance Evaluation under SIRP
  Clutter

abstract:
  Multiple-input multiple-output (MIMO) radar has become a thriving subject of
research during the past decades. In the MIMO radar context, it is sometimes
more accurate to model the radar clutter as a non-Gaussian process, more
specifically, by using the spherically invariant random process (SIRP) model.
In this paper, we focus on the estimation and performance analysis of the
angular spacing between two targets for the MIMO radar under the SIRP clutter.
First, we propose an iterative maximum likelihood as well as an iterative
maximum a posteriori estimator, for the target's spacing parameter estimation
in the SIRP clutter context. Then we derive and compare various
Cram\'er-Rao-like bounds (CRLBs) for performance assessment. Finally, we
address the problem of target resolvability by using the concept of angular
resolution limit (ARL), and derive an analytical, closed-form expression of the
ARL based on Smith's criterion, between two closely spaced targets in a MIMO
radar context under SIRP clutter. For this aim we also obtain the non-matrix,
closed-form expressions for each of the CRLBs. Finally, we provide numerical
simulations to assess the performance of the proposed algorithms, the validity
of the derived ARL expression, and to reveal the ARL's insightful properties.


title: Multipreconditioned GMRES for Shifted Systems

abstract:
  An implementation of GMRES with multiple preconditioners (MPGMRES) is
proposed for solving shifted linear systems with shift-and-invert
preconditioners. With this type of preconditioner, the Krylov subspace can be
built without requiring the matrix-vector product with the shifted matrix.
Furthermore, the multipreconditioned search space is shown to grow only
linearly with the number of preconditioners. This allows for a more efficient
implementation of the algorithm. The proposed implementation is tested on
shifted systems that arise in computational hydrology and the evaluation of
different matrix functions. The numerical results indicate the effectiveness of
the proposed approach.


title: Chiral heat wave and mixed waves in kinetic theory

abstract:
  We study collective excitations in hot rotating chiral media in presence of
magnetic field in kinetic theory, namely Chiral Heat Wave and its' mixings with
Chiral Vortical Wave and Chiral Magnetic Wave. Our results for velocities of
these waves have slight alterations from those obtained earlier. We explain the
origin of these alterations and also give the most general expressions for the
velocities of all these waves in hydrodynamic approach.


title: Block copolymer knots

abstract:
  An extensive study of single block copolymer knots containing two kinds of
monomers $A$ and $B$ is presented. The knots are in a solution and their
monomers are subjected to short range interactions that can be attractive or
repulsive. In view of possible applications in medicine and the construction of
intelligent materials, it is shown that several features of copolymer knots can
be tuned by changing the monomer configuration. A very fast and abrupt swelling
with increasing temperature is obtained in certain multiblock copolymers, while
the size and the swelling behavior at high temperatures may be controlled in
diblock copolymers. Interesting new effects appear in the thermal diagrams of
copolymer knots when their length is increased.


title:
Utility of a Behavlets approach to a Decision theoretic predictive
  player model

abstract:
  We present the second in a series of three academic essays which deal with
the question of how to build a generalized player model. We begin with a
proposition: a general model of players requires parameters for the subjective
experience of play, including at least three areas: a) player psychology, b)
game structure, and c) actions of play. Based on this proposition, we pose
three linked research questions, which make incomplete progress toward a
generalized player model: RQ1 what is a necessary and sufficient foundation to
a general player model?; RQ2 can such a foundation improve performance of a
computational intelligence-based player model?; and RQ3 can such a player model
improve efficacy of adaptive artificial intelligence in games? We set out the
arguments for each research question in each of the three essays, presented as
three preprints. The second essay, in this preprint, illustrates how our
'Behavlets' method can improve the performance and accuracy of a predictive
player model in the well-known Pac-Man game, by providing a simple foundation
for areas a) to c) above. We then propose a plan for future work to address RQ2
by conclusively testing the Behavlets approach. This plan builds on the work
proposed in the first preprint essay to address RQ1, and in turn provides
support for work on RQ3. The Behavlets approach was described previously;
therefore if citing this work please use the correct citation: Cowley B,
Charles D. Behavlets: a Method for Practical Player Modelling using
Psychology-Based Player Traits and Domain Specific Features. User Modelling and
User-Adapted Interaction. 2016 Feb 8; online (Special Issue on Personality in
Personalized Systems):1-50.


title: Refining the Hierarchies of Classes of Geometric Intersection Graphs

abstract:
  We analyse properties of geometric intersection graphs to show the strict
containment between some natural classes of geometric intersection graphs. In
particular, we show the following properties:
  - A graph $G$ is outerplanar if and only if the 1-subdivision of $G$ is
outer-segment.
  - For each integer $k\ge 1$, the class of intersection graphs of segments
with $k$ different lengths is a strict subclass of the class of intersection
graphs of segments with $k+1$ different lengths.
  - For each integer $k\ge 1$, the class of intersection graphs of disks with
$k$ different sizes is a strict subclass of the class of intersection graphs of
disks with $k+1$ different sizes.
  - The class of outer-segment graphs is a strict subclass of the class of
outer-string graphs.


title:
Convergence to the Stochastic Burgers Equation from a degenerate
  microscopic dynamics

abstract:
  In this paper we prove the convergence to the stochastic Burgers equation
from one-dimensional interacting particle systems, whose dynamics allow the
degeneracy of the jump rates. To this aim, we provide a new proof of the second
order Boltzmann-Gibbs principle introduced in [Gon\c{c}alves, Jara 2014]. The
main technical difficulty is that our models exhibit configurations that do not
evolve under the dynamics - the blocked configurations - and are locally
non-ergodic. Our proof does not impose any knowledge on the spectral gap for
the microscopic models. Instead, it relies on the fact that, under the
equilibrium measure, the probability to find a blocked configuration in a
finite box is exponentially small in the size of the box. Then, a dynamical
mechanism allows to exchange particles even when the jump rate for the direct
exchange is zero.


title: Local Search Yields a PTAS for k-Means in Doubling Metrics

abstract:
  The most well known and ubiquitous clustering problem encountered in nearly
every branch of science is undoubtedly $k$-means: given a set of data points
and a parameter $k$, select $k$ centres and partition the data points into $k$
clusters around these centres so that the sum of squares of distances of the
points to their cluster centre is minimized. Typically these data points lie
$\mathbb{R}^d$ for some $d\geq 2$.
  $k$-means and the first algorithms for it were introduced in the 1950's.
Since then, hundreds of papers have studied this problem and many algorithms
have been proposed for it. The most commonly used algorithm is known as
Lloyd-Forgy, which is also referred to as "the" $k$-means algorithm, and
various extensions of it often work very well in practice. However, they may
produce solutions whose cost is arbitrarily large compared to the optimum
solution. Kanungo et al. [2004] analyzed a simple local search heuristic to get
a polynomial-time algorithm with approximation ratio $9+\epsilon$ for any fixed
$\epsilon>0$ for $k$-means in Euclidean space.
  Finding an algorithm with a better approximation guarantee has remained one
of the biggest open questions in this area, in particular whether one can get a
true PTAS for fixed dimension Euclidean space. We settle this problem by
showing that a simple local search algorithm provides a PTAS for $k$-means in
$\mathbb{R}^d$ for any fixed $d$. More precisely, for any error parameter
$\epsilon>0$, the local search algorithm that considers swaps of up to
$\rho=d^{O(d)}\cdot{\epsilon}^{-O(d/\epsilon)}$ centres at a time finds a
solution using exactly $k$ centres whose cost is at most a
$(1+\epsilon)$-factor greater than the optimum.
  Finally, we provide the first demonstration that local search yields a PTAS
for the uncapacitated facility location problem and $k$-median with non-uniform
opening costs in doubling metrics.


title:
Stochastic transients as a source of quasi-periodic processes in the
  solar atmosphere

abstract:
  Solar dynamics and turbulence occur at all heights of the solar atmosphere
and could be described as stochastic processes. We propose that finite lifetime
transients recurring at a certain place could trigger quasi-periodic processes
in the associated structures. In this study, we developed a mathematical model
for finite lifetime and randomly occurring transients, and found that
quasi-periodic processes, with period longer than the time scale of the
transients, are detectable intrinsically in form of trains. We simulate their
propagation in an empirical solar atmospheric model with chromosphere,
transition region and corona. We found that, due to the filtering effect of the
chromospheric cavity, only the resonance period of the acoustic resonator is
able to propagate to the upper atmosphere, such a scenario is applicable to
slow magnetoacoustic waves in sunspots and active regions. If the thermal
structure of the atmosphere is less wild and acoustic resonance does not take
effect, the long period oscillations could propagate to the upper atmosphere.
Such case would be more likely to occur at polar plumes.


title: RemIX: A Distributed Internet Exchange for Remote and Rural Networks

abstract:
  The concept of the IXP, an Ethernet fabric central to the structure of the
global Internet, is largely absent from the development of community-driven
collaborative network infrastructure. The reasons for this are two-fold. IXPs
exist in central, typically urban, environments where strong network
infrastructure ensures high levels of connectivity. Between rural and remote
regions, where networks are separated by distance and terrain, no such
infrastructure exists. In this paper we present RemIX a distributed IXPs
architecture designed for the community network environment. We examine this
praxis using an implementation in Scotland, with suggestions for future
development and research.


title: Isomorphismes entre des espaces de mesures \`a valeurs vectorielles

abstract:
  Let $(\Omega_1, \mathcal{F}_1, \mu_1)$, $(\Omega_2, \mathcal{F}_2, \mu_2)$ be
two probabilty spaces, $1\leq p\leq +\infty$ and $X$ a Banach space. In this
work we show that $L^p(\mu_1, X)$, $VB^p (\mu_1,X),$ $cabv(\mu_{1},X)$ are
isomorphic to $L^p(\mu_2, X),$ $VB^p(\mu_2, X)$, $cabc(\mu_2, X)$ respectively,
if $L^1(\mu_1)$ is strongly isomorphic to $L^1(\mu_2)$.


title:
Are all Secant Varieties of Segre Products Arithmetically
  Cohen-Macaulay?

abstract:
  When present, the Cohen-Macaulay property can be useful for finding the
minimal defining equations of an algebraic variety. It is conjectured that all
secant varieties of Segre products of projective spaces are arithmetically
Cohen-Macaulay. A summary of the known cases where the conjecture is true is
given. An inductive procedure based on the work of Landsberg and Weyman
(LW-lifting) is described and used to obtain resolutions of orbits of secant
varieties from those of smaller secant varieties. A new computation of the
minimal free resolution of the variety of border rank 4 tensors of format $3
\times 3 \times 4$ is given together with its equivariant presentation.
LW-lifting is used to prove several cases where secant varieties are
arithmetically Cohen-Macaulay and arithmetically Gorenstein.


title: Detecting weak changes in dynamic events over networks

abstract:
  Large volume of networked streaming event data are becoming increasingly
available in a wide variety of applications, such as social network analysis,
Internet traffic monitoring and healthcare analytics. Streaming event data are
discrete observation occurred in continuous time, and the precise time interval
between two events carries a great deal of information about the dynamics of
the underlying systems. How to promptly detect changes in these dynamic systems
using these streaming event data? In this paper, we propose a novel
change-point detection framework for multi-dimensional event data over
networks. We cast the problem into sequential hypothesis test, and derive the
likelihood ratios for point processes, which are computed efficiently via an
EM-like algorithm that is parameter-free and can be computed in a distributed
fashion. We derive a highly accurate theoretical characterization of the
false-alarm-rate, and show that it can achieve weak signal detection by
aggregating local statistics over time and networks. Finally, we demonstrate
the good performance of our algorithm on numerical examples and real-world
datasets from twitter and Memetracker.


title:
Maximum Likelihood and Maximum A Posteriori Direction-of-Arrival
  Estimation in the Presence of SIRP Noise

abstract:
  The maximum likelihood (ML) and maximum a posteriori (MAP) estimation
techniques are widely used to address the direction-of-arrival (DOA) estimation
problems, an important topic in sensor array processing. Conventionally the ML
estimators in the DOA estimation context assume the sensor noise to follow a
Gaussian distribution. In real-life application, however, this assumption is
sometimes not valid, and it is often more accurate to model the noise as a
non-Gaussian process. In this paper we derive an iterative ML as well as an
iterative MAP estimation algorithm for the DOA estimation problem under the
spherically invariant random process noise assumption, one of the most popular
non-Gaussian models, especially in the radar context. Numerical simulation
results are provided to assess our proposed algorithms and to show their
advantage in terms of performance over the conventional ML algorithm.


title: Adaptive Computation Time for Recurrent Neural Networks

abstract:
  This paper introduces Adaptive Computation Time (ACT), an algorithm that
allows recurrent neural networks to learn how many computational steps to take
between receiving an input and emitting an output. ACT requires minimal changes
to the network architecture, is deterministic and differentiable, and does not
add any noise to the parameter gradients. Experimental results are provided for
four synthetic problems: determining the parity of binary vectors, applying
binary logic operations, adding integers, and sorting real numbers. Overall,
performance is dramatically improved by the use of ACT, which successfully
adapts the number of computational steps to the requirements of the problem. We
also present character-level language modelling results on the Hutter prize
Wikipedia dataset. In this case ACT does not yield large gains in performance;
however it does provide intriguing insight into the structure of the data, with
more computation allocated to harder-to-predict transitions, such as spaces
between words and ends of sentences. This suggests that ACT or other adaptive
computation methods could provide a generic method for inferring segment
boundaries in sequence data.


title: SMASH: Physics-guided Reconstruction of Collisions from Videos

abstract:
  Collision sequences are commonly used in games and entertainment to add drama
and excitement. Authoring even two body collisions in the real world can be
difficult, as one has to get timing and the object trajectories to be correctly
synchronized. After tedious trial-and-error iterations, when objects can
actually be made to collide, then they are difficult to capture in 3D. In
contrast, synthetically generating plausible collisions is difficult as it
requires adjusting different collision parameters (e.g., object mass ratio,
coefficient of restitution, etc.) and appropriate initial parameters. We
present SMASH to directly read off appropriate collision parameters directly
from raw input video recordings. Technically we enable this by utilizing laws
of rigid body collision to regularize the problem of lifting 2D trajectories to
a physically valid 3D reconstruction of the collision. The reconstructed
sequences can then be modified and combined to easily author novel and
plausible collisions. We evaluate our system on a range of synthetic scenes and
demonstrate the effectiveness of our method by accurately reconstructing
several complex real world collision events.


title: When Shock Waves Collide

abstract:
  Supersonic outflows from objects as varied as stellar jets, massive stars and
novae often exhibit multiple shock waves that overlap one another. When the
intersection angle between two shock waves exceeds a critical value, the system
reconfigures its geometry to create a normal shock known as a Mach stem where
the shocks meet. Mach stems are important for interpreting emission-line images
of shocked gas because a normal shock produces higher postshock temperatures
and therefore a higher-excitation spectrum than an oblique one does. In this
paper we summarize the results of a series of numerical simulations and
laboratory experiments designed to quantify how Mach stems behave in supersonic
plasmas that are the norm in astrophysical flows. The experiments test
analytical predictions for critical angles where Mach stems should form, and
quantify how Mach stems grow and decay as intersection angles between the
incident shock and a surface change. While small Mach stems are destroyed by
surface irregularities and subcritical angles, larger ones persist in these
situations, and can regrow if the intersection angle changes to become more
favorable. The experimental and numerical results show that although Mach stems
occur only over a limited range of intersection angles and size scales, within
these ranges they are relatively robust, and hence are a viable explanation for
variable bright knots observed in HST images at the intersections of some bow
shocks in stellar jets.


title:
Lipschitz continuity and convexity preserving for solutions of
  semilinear evolution equations in the Heisenberg group

abstract:
  In this paper we study viscosity solutions of semilinear parabolic equations
in the Heisenberg group. We show uniqueness of viscosity solutions with
exponential growth at space infinity. We also study Lipschitz and horizontal
convexity preserving properties under appropriate assumptions. Counterexamples
show that in general such properties that are well-known for semilinear and
fully nonlinear parabolic equations in the Euclidean spaces do not hold in the
Heisenberg group.


title:
Experimental Evaluation of a Reconfigurable Antenna System for Blind
  Interference Alignment

abstract:
  In recent years, several experimental studies have come out to validate the
theoretical findings of interference alignment (IA), but only a handful of
studies have focused on blind interference alignment. Unlike IA and other
interference mitigation techniques, blind IA does not require channel state
information at the transmitter (CSIT). The key insight is that the transmitter
uses the knowledge of channel coherence intervals and receivers utilize
reconfigurable antennas to create channel fluctuations exploited by the
transmitter. In this work, we present a novel experimental evaluation of a
reconfigurable antenna system for achieving blind IA. We present a blind IA
technique based on reconfigurable antennas for a 2-user multipleinput
single-output (MISO) broadcast channel implemented on a software defined radio
platform where each of the receivers is equipped with a reconfigurable antenna.
We further compare this blind IA implementation with traditional TDMA scheme
for benchmarking purposes. We show that the achievable rates for blind IA can
be realized in practice using measured channels under practical channel
conditions. Additionally, the average error vector magnitude and bit error rate
(BER) performances are evaluated.


title: Towards Practical Bayesian Parameter and State Estimation

abstract:
  Joint state and parameter estimation is a core problem for dynamic Bayesian
networks. Although modern probabilistic inference toolkits make it relatively
easy to specify large and practically relevant probabilistic models, the silver
bullet---an efficient and general online inference algorithm for such
problems---remains elusive, forcing users to write special-purpose code for
each application. We propose a novel blackbox algorithm -- a hybrid of particle
filtering for state variables and assumed density filtering for parameter
variables. It has following advantages: (a) it is efficient due to its online
nature, and (b) it is applicable to both discrete and continuous parameter
spaces . On a variety of toy and real models, our system is able to generate
more accurate results within a fixed computation budget. This preliminary
evidence indicates that the proposed approach is likely to be of practical use.


title:
An a posteriori error analysis for an optimal control problem involving
  the fractional Laplacian

abstract:
  In a previous work, we introduced a discretization scheme for a constrained
optimal control problem involving the fractional Laplacian. For such a control
problem, we derived optimal a priori error estimates that demand the convexity
of the domain and some compatibility conditions on the data. To relax such
restrictions, in this paper, we introduce and analyze an efficient and, under
certain assumptions, reliable a posteriori error estimator. We realize the
fractional Laplacian as the Dirichlet-to-Neumann map for a nonuniformly
elliptic problem posed on a semi--infinite cylinder in one more spatial
dimension. This extra dimension further motivates the design of an posteriori
error indicator. The latter is defined as the sum of three contributions, which
come from the discretization of the state and adjoint equations and the control
variable. The indicator for the state and adjoint equations relies on an
anisotropic error estimator in Muckenhoupt weighted Sobolev spaces. The
analysis is valid in any dimension. On the basis of the devised a posteriori
error estimator, we design a simple adaptive strategy that exhibits optimal
experimental rates of convergence.


title: Evaluation of reactor neutrino flux: issues and uncertainties

abstract:
  Evaluation of the reactor $\bar{\nu}_e$ flux and spectrum is an essential
ingredient of their application in the neutrino oscillation studies. Two
anomalies, i.e. discrepancies between the observed and expected count rates,
are widely discussed at the resent time. The total rate is $\sim$ 6\% lower
than the expectation at all distances $>$ 10 m from the reactor. And there is a
shoulder (often referred to as "bump") at neutrino energies 5-7 MeV, not
predicted in the calculated spectrum. I review the ways the flux and spectrum
is evaluated and concentrate on the error budget. I argue that far reaching
conclusions based on these anomalies should await a thorough understanding of
the uncertainties of the spectrum, and point out possible standard physics
sources of the anomalies.


title:
The GALAH Survey: Relative throughputs of the 2dF fibre positioner and
  the HERMES spectrograph from stellar targets

abstract:
  We present an analysis of the relative throughputs of the 3.9-metre
Anglo-Australian Telescope's 2dF/HERMES system, based upon spectra acquired
during the first two years of the GALAH survey. Averaged spectral fluxes of
stars were compared to their photometry to determine the relative throughputs
of fibres for a range of fibre position and atmospheric conditions. We find
that overall the throughputs of the 771 usable fibres have been stable over the
first two years of its operation. About 2.5 per cent of fibres have throughputs
much lower than the average. There are also a number of yet unexplained
variations between the HERMES bandpasses, and mechanically & optically linked
fibre groups known as retractors or slitlets related to regions of the focal
plane. These findings do not impact the science that HERMES will produce.


title:
Cannibals in the thick disk: the young $\alpha-$rich stars as evolved
  blue stragglers

abstract:
  Spectro-seismic measurements of red giants enabled the recent discovery of
stars in the thick disk that are more massive than 1.4 M_sun. While it has been
claimed that most of these stars are younger than the rest of the typical thick
disk stars, we show evidence that they might be products of mass transfer in
binary evolution, notably evolved blue stragglers. We took new measurements of
the radial velocities in a sample of 26 stars from APOKASC, including 13
"young" stars and 13 "old" stars with similar stellar parameters but with
masses below 1.2 M_sun and found that more of the "young" stars appear to be in
binary systems with respect to the "old" stars. Furthermore, we show that the
"young" stars do not follow the expected trend of [C/H] ratios versus mass for
individual stars. However, with a population synthesis of low-mass stars
including binary evolution and mass transfer, we can reproduce the observed
[C/N] ratios versus mass. Our study shows how asteroseismology of solar-type
red giants provides us with a unique opportunity to study the evolution of
field blue stragglers after they have left the main-sequence.


title:
Measurement of $C\!P$ observables in $B^\pm \rightarrow D K^\pm$ and
  $B^\pm \rightarrow D \pi^\pm$ with two- and four-body $D$ decays

abstract:
  Measurements of $C\!P$ observables in $B^\pm \rightarrow D K^\pm$ and $B^\pm
\rightarrow D \pi^\pm$ decays are presented where the $D$ meson is
reconstructed in the final states $K^\pm\pi^\mp$, $\pi^\pm K^\mp$, $K^+K^-$,
$\pi^+\pi^-$, $K^\pm\pi^\mp \pi^+ \pi^-$, $\pi^\pm K^\mp \pi^+ \pi^-$ and
$\pi^+ \pi^- \pi^+ \pi^-$. This analysis uses a sample of charged $B$ mesons
from $pp$ collisions collected by the LHCb experiment in 2011 and 2012,
corresponding to an integrated luminosity of 3.0 fb$^{-1}$. Various
\CP-violating effects are reported and together these measurements provide
important input for the determination of the unitarity triangle angle $\gamma$.
The analysis of the four-pion $D$ decay mode is the first of its kind.


title: Computing black hole partition functions from quasinormal modes

abstract:
  We propose a method of computing one-loop determinants in black hole
spacetimes (with emphasis on asymptotically anti-de Sitter black holes) that
may be used for numerics when completely-analytic results are unattainable. The
method utilizes the expression for one-loop determinants in terms of
quasinormal frequencies determined by Denef, Hartnoll and Sachdev in
\cite{Denef:2009kn}. A numerical evaluation must face the fact that the sum
over the quasinormal modes, indexed by momentum and overtone numbers, is
divergent. A necessary ingredient is then a regularization scheme to handle the
divergent contributions of individual fixed-momentum sectors to the partition
function. To this end, we formulate an effective two-dimensional problem in
which a natural refinement of standard heat kernel techniques can be used to
account for contributions to the partition function at fixed momentum. We test
our method in a concrete case by reproducing the scalar one-loop determinant in
the BTZ black hole background. We then discuss the application of such
techniques to more complicated spacetimes.


title: To Observe or Not to Observe: Queuing Game Framework for Urban Parking

abstract:
  We model parking in urban centers as a set of parallel queues and overlay a
game theoretic structure that allows us to compare the user-selected (Nash)
equilibrium to the socially optimal equilibrium. We model arriving drivers as
utility maximizers and consider the game in which observing the queue length is
free as well as the game in which drivers must pay to observe the queue length.
In both games, drivers must decide between balking and joining. We compare the
Nash induced welfare to the socially optimal welfare. We find that gains to
welfare do not require full information penetration---meaning, for social
welfare to increase, not everyone needs to pay to observe. Through simulation,
we explore a more complex scenario where drivers decide based the queueing game
whether or not to enter a collection of queues over a network. We examine the
occupancy-congestion relationship, an important relationship for determining
the impact of parking resources on overall traffic congestion. Our simulated
models use parameters informed by real-world data collected by the Seattle
Department of Transportation.


title: Computing Educator Attitudes about Motivation

abstract:
  While motivation is of great interest to computing educators, relatively
little work has been done on understanding faculty attitudes toward student
motivation. Two previous qualitative studies of instructor attitudes found
results identical to those from other disciplines, but neither study considered
whether instructors perceive student motivation to be more important in certain
computing classes. In this work we present quantitative results about the
perceived importance of student motivation in computing courses on the part of
computing educators. Our survey results show that while a majority of
respondents believe student motivation is necessary in all computing courses,
the structure and audience in certain computing classes elevate the importance
of student motivation.


title:
Shortest path and maximum flow problems in planar flow networks with
  additive gains and losses

abstract:
  In contrast to traditional flow networks, in additive flow networks, to every
edge e is assigned a gain factor g(e) which represents the loss or gain of the
flow while using edge e. Hence, if a flow f(e) enters the edge e and f(e) is
less than the designated capacity of e, then f(e) + g(e) = 0 units of flow
reach the end point of e, provided e is used, i.e., provided f(e) != 0. In this
report we study the maximum flow problem in additive flow networks, which we
prove to be NP-hard even when the underlying graphs of additive flow networks
are planar. We also investigate the shortest path problem, when to every edge e
is assigned a cost value for every unit flow entering edge e, which we show to
be NP-hard in the strong sense even when the additive flow networks are planar.


title: Rates and singlet/triplet ratios from TADF transients

abstract:
  Thermally activated delayed fluorescence has been reported in a number of
OLED emitter materials engineered to have low singlet-triplet energy gaps. Here
we derive closed solutions for steady state and transient behaviors, and apply
these results to obtain the singlet and triplet relaxation, forward and reverse
crossing rates and the gap energy and reverse crossing prefactor from delayed
and prompt relaxation rates measured over a series of temperatures. The primary
rates are then used to calculate the fluorescent/phosphorescent ratio and the
singlet/triplet population ratio. The method avoids the need for gated yield
measurements. Good fits are obtained using previously published data for 4CzIPN
and m-MTDATA:t-Bu-PBD and the results appear to be consistent with reported
quantities were available, and with reported behaviors of OLEDS that use these
materials.


title:
Simultaneous Metal-Insulator and Antiferromagnetic Transitions in
  Orthorhombic Perovskite Iridate Sr0.94Ir0.78O2.68 Single Crystals

abstract:
  The orthorhombic perovskite SrIrO3 is a semimetal, an intriguing exception in
iridates where the strong spin-orbit interaction coupled with electron
correlations tends to impose a novel insulating state. We report results of our
investigation of bulk single-crystal Sr0.94Ir0.78O2.68 or Ir-deficient,
orthorhombic perovskite SrIrO3. It retains the same crystal structure as
stoichiometric SrIrO3 but exhibits a sharp, simultaneous antiferromagnetic
(AFM) and metal-insulator (MI) transition at 185 K. Above it, the basal-plane
resistivity features an extended regime of almost linear-temperature dependence
up to 800 K but the strong electronic anisotropy renders an insulating behavior
in the out-of-plane resistivity. The Hall resistivity undergoes an abrupt sign
change and grows below 40 K, which along with the Sommerfeld constant of 20
mJ/mole K2 suggests a multiband effect. All results including our
first-principles calculations underscore a delicacy of the metallic state in
SrIrO3 that is in close proximity to an AFM insulating state. The contrasting
ground states in isostructural Sr0.94Ir0.78O2.68 and SrIrO3 illustrate a
critical role of even slight lattice distortions in rebalancing the ground
state in the iridates. Finally, the observed simultaneous AFM and MI
transitions reveal a direct correlation between the magnetic transition and
formation of a charge gap in the iridate, which is conspicuously absent in
Sr2IrO4.


title:
Online Rules for Control of False Discovery Rate and False Discovery
  Exceedance

abstract:
  Multiple hypothesis testing is a core problem in statistical inference and
arises in almost every scientific field. Given a set of null hypotheses
$\mathcal{H}(n) = (H_1,\dotsc, H_n)$, Benjamini and Hochberg introduced the
false discovery rate (FDR), which is the expected proportion of false positives
among rejected null hypotheses, and proposed a testing procedure that controls
FDR below a pre-assigned significance level. Nowadays FDR is the criterion of
choice for large scale multiple hypothesis testing. In this paper we consider
the problem of controlling FDR in an "online manner". Concretely, we consider
an ordered --possibly infinite-- sequence of null hypotheses $\mathcal{H} =
(H_1,H_2,H_3,\dots )$ where, at each step $i$, the statistician must decide
whether to reject hypothesis $H_i$ having access only to the previous
decisions. This model was introduced by Foster and Stine. We study a class of
"generalized alpha-investing" procedures and prove that any rule in this class
controls online FDR, provided $p$-values corresponding to true nulls are
independent from the other $p$-values. (Earlier work only established mFDR
control.) Next, we obtain conditions under which generalized alpha-investing
controls FDR in the presence of general $p$-values dependencies. Finally, we
develop a modified set of procedures that also allow to control the false
discovery exceedance (the tail of the proportion of false discoveries).
Numerical simulations and analytical results indicate that online procedures do
not incur a large loss in statistical power with respect to offline approaches,
such as Benjamini-Hochberg.

categories: math.ST cs.LG stat.AP stat.ME stat.ML stat.TH


title:
Diffusion Approximations for Controlled Weakly Interacting Large Finite
  State Systems with Simultaneous Jumps

abstract:
  We consider a rate control problem for an $N$-particle weakly interacting
finite state Markov process. The process models the state evolution of a large
collection of particles and allows for multiple particles to change state
simultaneously. Such models have been proposed for large communication systems
(e.g. ad hoc wireless networks) but are also suitable for other settings such
as chemical-reaction networks. An associated diffusion control problem is
presented and we show that the value function of the $N$-particle controlled
system converges to the value function of the limit diffusion control problem
as $N\to\infty$. The diffusion coefficient in the limit model is typically
degenerate, however under suitable conditions there is an equivalent
formulation in terms of a controlled diffusion with a uniformly non-degenerate
diffusion coefficient. Using this equivalence, we show that near optimal
continuous feedback controls exist for the diffusion control problem. We then
construct near asymptotically optimal control policies for the $N$-particle
system based on such continuous feedback controls. Results from some numerical
experiments are presented.


title:
Dataflow Matrix Machines as a Generalization of Recurrent Neural
  Networks

abstract:
  Dataflow matrix machines are a powerful generalization of recurrent neural
networks. They work with multiple types of arbitrary linear streams, multiple
types of powerful neurons, and allow to incorporate higher-order constructions.
We expect them to be useful in machine learning and probabilistic programming,
and in the synthesis of dynamic systems and of deterministic and probabilistic
programs.


title: Thermoelectric signals of state transition in polycrystalline SmB6

abstract:
  Topological Kondo insulator SmB6 has attracted quite a lot of attentions from
condensed matter physics community. A number of unique electronic properties,
including low- temperature resistivity anomaly, 1D electronic transport and 2D
Fermi surfaces have been observed in SmB6. Here, we report on thermoelectric
transport properties of polycrystalline SmB6 over a broad temperature from 300
K to 2 K. An anomalous transition in the temperature-dependent Seebeck
coefficient S from S(T) ~ T-1 to S(T) ~ T was observed around 12 K. Such a
transition demonstrates a transition of conductivity from 3D metallic bulk
states to 2D metallic surface states with insulating bulk states. Our results
suggest that the thermotransport measurements could be used for the
characterization of state transition in topological insulators.


title: Singular Vectors of Orthogonally Decomposable Tensors

abstract:
  Orthogonal decomposition of tensors is a generalization of the singular value
decomposition of matrices. In this paper, we study the spectral theory of
orthogonally decomposable tensors. For such a tensor, we give a description of
its singular vector tuples as a variety in a product of projective spaces.


title:
Uniform convergence over time of a nested particle filtering scheme for
  recursive parameter estimation in state--space Markov models

abstract:
  We analyse the performance of a recursive Monte Carlo method for the Bayesian
estimation of the static parameters of a discrete--time state--space Markov
model. The algorithm employs two layers of particle filters to approximate the
posterior probability distribution of the model parameters. In particular, the
first layer yields an empirical distribution of samples on the parameter space,
while the filters in the second layer are auxiliary devices to approximate the
(analytically intractable) likelihood of the parameters. This approach relates
the this algorithm to the recent sequential Monte Carlo square (SMC$^2$)
method, which provides a {\em non-recursive} solution to the same problem. In
this paper, we investigate the approximation, via the proposed scheme, of
integrals of real bounded functions with respect to the posterior distribution
of the system parameters. Under assumptions related to the compactness of the
parameter support and the stability and continuity of the sequence of posterior
distributions for the state--space model, we prove that the $L_p$ norms of the
approximation errors vanish asymptotically (as the number of Monte Carlo
samples generated by the algorithm increases) and uniformly over time. We also
prove that, under the same assumptions, the proposed scheme can asymptotically
identify the parameter values for a class of models. We conclude the paper with
a numerical example that illustrates the uniform convergence results by
exploring the accuracy and stability of the proposed algorithm operating with
long sequences of observations.


title: On the generalized Approximate Weak Chebyshev Greedy Algorithm

abstract:
  In this paper we study greedy approximation in Banach spaces. We discuss a
modification of the Weak Chebyshev Greedy Algorithm, in which steps of the
algorithm can be executed imprecisely. Such inaccuracies are represented by
both absolute and relative errors, which provides more flexibility for
numerical applications. We obtain the conditions on the error parameters that
guarantee convergence of the algorithm in all uniformly smooth Banach spaces
and prove that these conditions are sharp. Additionally, we discuss the
conditions that need to be imposed on a Banach space to guarantee convergence
of the Chebyshev Greedy Algorithm, and construct a smooth Banach space in which
the algorithm diverges.


title: Fourier Transform of Electric Signal using Kundt's Tube

abstract:
  An experiment to demonstrate the Fourier transform of an electric signal
using the Kundt's tube is described. The results of finding the component
frequencies and an approximation to the amplitudes of two sinusoidal signals
which compose an input electric signal is presented. Undergraduate students are
expected to more easily relate to the meaning of a Fourier transform through
such mechanical demonstrations.


title:
Observational Constraints on Planet Nine: Astrometry of Pluto and Other
  Trans-Neptunian Objects

abstract:
  We use astrometry of Pluto and other TNOs to constrain the sky location,
distance, and mass of the possible additional planet (Planet Nine) hypothesized
by Batygin and Brown (2016). We find that over broad regions of the sky, the
inclusion of a massive, distant planet degrades the fits to the observations.
However, in other regions, the fits are significantly improved by the addition
of such a planet. Our best fits suggest a planet that is either more massive or
closer than argued for by Batygin and Brown (2016) based on the orbital
distribution of distant trans-neptunian objects (or by Fienga et al. (2016)
based on range measured to the Cassini spacecraft). The trend to favor larger
and closer perturbing planets is driven by the residuals to the astrometry of
Pluto, remeasured from photographic plates using modern stellar catalogs (Buie
and Folkner 2015), which show a clear trend in declination, over the course of
two decades, that drive a preference for large perturbations. Although this
trend may be the result of systematic errors of unknown origin in the
observations, a possible resolution is that the declination trend may be due to
perturbations from a body, additional to Planet Nine , that is closer to Pluto,
but less massive than, Planet Nine .


title: Routing under Balance

abstract:
  We introduce the notion of balance for directed graphs: a weighted directed
graph is $\alpha$-balanced if for every cut $S \subseteq V$, the total weight
of edges going from $S$ to $V\setminus S$ is within factor $\alpha$ of the
total weight of edges going from $V\setminus S$ to $S$. Several important
families of graphs are nearly balanced, in particular, Eulerian graphs (with
$\alpha = 1$) and residual graphs of $(1+\epsilon)$-approximate undirected
maximum flows (with $\alpha=O(1/\epsilon)$).
  We use the notion of balance to give a more fine-grained understanding of
several well-studied routing questions that are considerably harder in directed
graphs. We first revisit oblivious routings in directed graphs. Our main
algorithmic result is an oblivious routing scheme for single-source instances
that achieve an $O(\alpha \cdot \log^3 n / \log \log n)$ competitive ratio. In
the process, we make several technical contributions which may be of
independent interest. In particular, we give an efficient algorithm for
computing low-radius decompositions of directed graphs parameterized by
balance. We also define and construct low-stretch arborescences, a
generalization of low-stretch spanning trees to directed graphs.
  On the negative side, we present new lower bounds for oblivious routing
problems on directed graphs. We show that the competitive ratio of oblivious
routing algorithms for directed graphs is $\Omega(n)$ in general; this result
improves upon the long-standing best known lower bound of $\Omega(\sqrt{n})$
given by Hajiaghayi, Kleinberg, Leighton and R\"acke in 2006. We also show that
our restriction to single-source instances is necessary by showing an
$\Omega(\sqrt{n})$ lower bound for multiple-source oblivious routing in
Eulerian graphs.
  We also give a fast algorithm for the maximum flow problem in balanced
directed graphs.


title:
Computational Method for the Retarded Potential in the Real-Time
  Simulation of Quantum Electrodynamics

abstract:
  We discuss the method to compute the integrals which appear in the retarded
potential term for a real-time simulation based on QED (Quantum
Electrodynamics). We show that the oscillatory integrals over the infinite
interval involved in them can be efficiently performed by the method developed
by Ooura and Mori based on the double exponential (DE) formula.


title:
Effective p-wave interaction and topological superfluids in s-wave
  quantum gases

abstract:
  P-wave interaction in cold atoms may give rise to exotic topological
superfluids. However, the realization of p-wave interaction in cold atom system
is experimentally challenging. Here we propose a simple scheme to synthesize
effective $p$-wave interaction in conventional $s$-wave interacting quantum
gases. The key idea is to load atoms into spin-dependent optical lattice
potential. Using two concrete examples involving spin-1/2 fermions, we show how
the original system can be mapped into a model describing spinless fermions
with nearest neighbor p-wave interaction, whose ground state can be a
topological superfluid that supports Majorana fermions under proper conditions.
Our proposal has the advantage that it does not require spin-orbit coupling or
loading atoms onto higher orbitals, which is the key in earlier proposals to
synthesize effective $p$-wave interaction in $s$-wave quantum gases, and may
provide a completely new route for realizing $p$-wave topological superfluids.


title: A framework for event co-occurrence detection in event streams

abstract:
  This paper shows that characterizing co-occurrence between events is an
important but non-trivial and neglected aspect of discovering potential causal
relationships in multimedia event streams. First an introduction to the notion
of event co-occurrence and its relation to co-occurrence pattern detection is
given. Then a finite state automaton extended with a time model and event
parameterization is introduced to convert high level co-occurrence pattern
definition to its corresponding pattern matching automaton. Finally a
processing algorithm is applied to count the occurrence frequency of a
collection of patterns with only one pass through input event streams. The
method proposed in this paper can be used for detecting co-occurrences between
both events of one event stream (Auto co-occurrence), and events from multiple
event streams (Cross co-occurrence). Some fundamental results concerning the
characterization of event co-occurrence are presented in form of a visual co-
occurrence matrix. Reusable causality rules can be extracted easily from
co-occurrence matrix and fed into various analysis tools, such as
recommendation systems and complex event processing systems for further
analysis.


title:
Combinatorial descriptions of the crystal structure on certain PBW bases
  (extended abstract)

abstract:
  Lusztig's theory of PBW bases gives a way to realize the infinity crystal for
any simple complex Lie algebra where the underlying set consists of Kostant
partitions. In fact, there are many different such realizations, one for each
reduced expression for the longest element of the Weyl group. There is an
algorithm to calculate the actions of the crystal operators, but it can be
quite complicated. For ADE types, we give conditions on the reduced expression
which ensure that the corresponding crystal operators are given by simple
combinatorial bracketing rules. We then give at least one reduced expression
satisfying our conditions in every type except $E_8$, and discuss the resulting
combinatorics. Finally, we describe the relationship with more standard
tableaux combinatorics in types A and D.


title:
A combinatorial algorithm for constrained assortment optimization under
  nested logit model

abstract:
  We consider the assortment optimization problem with disjoint-cardinality
constraints under two-level nested logit model. To solve this problem, we first
identify a candidate set with $O(mn^2)$ assortments and show that at least one
optimal assortment is included in this set. Based on this observation, a fast
algorithm, which runs in $O(m n^2 \log mn)$ time, is proposed to find an
optimal assortment.


title:
The identification of the dominant donors in low temperature grown InPBi
  materials

abstract:
  Combined with magnetotransport measurements and first-principles
calculations, we systematically investigated the effects of Bi incorporation on
the electrical properties of the undoped InP1-xBix epilayers with 0<x<2.41%.
The Hall-bar measurements reveal a dominant n-type conductivity of the InPBi
samples. The electron concentrations are found to decrease firstly as x
increases up to x=1.83%, and then increase again with further increasing Bi
composition, whiles the electron mobility shows an inverse variation to the
electron concentration. First-principle calculations suggest that both the
phosphorus antisites and vacancy defects are the dominant donors responsible
for the high electron concentration. And their defect concentrations show
different behaviors as Bi composition x increases, resulting in a nonlinear
relationship between electron concentration and Bi composition in InPBi alloys.


title: Rich Image Captioning in the Wild

abstract:
  We present an image caption system that addresses new challenges of
automatically describing images in the wild. The challenges include high
quality caption quality with respect to human judgments, out-of-domain data
handling, and low latency required in many applications. Built on top of a
state-of-the-art framework, we developed a deep vision model that detects a
broad range of visual concepts, an entity recognition model that identifies
celebrities and landmarks, and a confidence model for the caption output.
Experimental results show that our caption engine outperforms previous
state-of-the-art systems significantly on both in-domain dataset (i.e. MS COCO)
and out of-domain datasets.


title:
Tree formulas, mean first passage times and Kemeny's constant of a
  Markov chain

abstract:
  In this paper, we aim to provide probabilistic and combinatorial insights
into tree formulas for the Green function and hitting probabilities of Markov
chains on a finite state space. These tree formulas are closely related to
loop-erased random walks by Wilson's algorithm for random spanning trees, and
to mixing times by the Markov chain tree theorem. Let $m_{ij}$ be the mean
first passage time from $i$ to $j$ for an irreducible chain with finite state
space $S$ and transition matrix $(p_{ij}; i, j \in S)$. It is well-known that
$m_{jj} = 1/\pi_j = \Sigma^{(1)}/\Sigma_j$, where $\pi$ is the stationary
distribution for the chain, $\Sigma_j$ is the tree sum, over $n^{n-2}$ trees
$\textbf{t}$ spanning $S$ with root $j$ and edges $i \rightarrow k$ directed to
$j$, of the tree product $\prod_{i \rightarrow k \in \textbf{t} }p_{ik}$, and
$\Sigma^{(1)}:= \sum_{j \in S} \Sigma_j$. Chebotarev and Agaev derived further
results from {\em Kirchhoff's matrix tree theorem}. We deduce that for $i \ne
j$, $m_{ij} = \Sigma_{ij}/\Sigma_j$, where $\Sigma_{ij}$ is the sum over the
same set of $n^{n-2}$ spanning trees of the same tree product as for
$\Sigma_j$, except that in each product the factor $p_{kj}$ is omitted where $k
= k(i,j,\textbf{t})$ is the last state before $j$ in the path from $i$ to $j$
in $\textbf{t}$. It follows that Kemeny's constant $\sum_{j \in S}
m_{ij}/m_{jj}$ equals to $ \Sigma^{(2)}/\Sigma^{(1)}$, where $\Sigma^{(r)}$ is
the sum, over all forests $\textbf{f}$ labeled by $S$ with $r$ trees, of the
product of $p_{ij}$ over edges $i \rightarrow j$ of $\textbf{t}$. We show that
these results can be derived without appeal to the matrix tree theorem. A list
of relevant literature is also reviewed.


title: On Real and Complex Cubic Curves

abstract:
  An expository description of smooth cubic curves in the real or complex
projective plane.


title:
Phase sensitivity at the Heisenberg limit in an SU(1,1) interferometer
  via parity detection

abstract:
  We theoretically investigate the phase sensitivity with parity detection on
an SU(1,1) interferometer with a coherent state combined with a squeezed vacuum
state. This interferometer is formed with two parametric amplifiers for beam
splitting and recombination instead of beam splitters. We show that the
sensitivity of estimation phase approaches Heisenberg limit and give the
corresponding optimal condition. Moreover, we derive the quantum Cram\'er-Rao
bound of the SU(1,1) interferometer.


title:
Optimization of the collimation system for CSNS/RCS with the robust
  conjugate direction search algorithm

abstract:
  The Robust Conjugate Direction Search (RCDS) method is used to optimize the
collimation system for Rapid Cycling Synchrotron (RCS) of the Chinese
Spallation Neutron Source (CSNS). The parameters of secondary collimators are
optimized for a better performance of the collimation system. To improve the
efficiency of the optimization, the Objective Ring Beam Injection and Tracking
(ORBIT) parallel module combined with MATLAB parallel computing is used, which
can run multiple ORBIT instances simultaneously. This study presents a way to
figure out an optimal parameter combination of the secondary collimators for a
machine model in preparation for CSNS/RCS commissioning.


title:
A Stochastic Differential Equation Framework for Guiding Online User
  Activities in Closed Loop

abstract:
  Recently, there is a surge of interest in using point processes to model
continuous-time user activities. This framework has resulted in novel models
and improved performance in diverse applications. However, most previous works
focus on the "open loop" setting where learned models are used for predictive
tasks. Typically, we are interested in the "closed loop" setting where a policy
needs to be learned to incorporate user feedbacks and guide user activities to
desirable states. Although point processes have good predictive performance, it
is not clear how to use them for the challenging closed loop activity guiding
task. In this paper, we propose a framework to reformulate point processes into
stochastic differential equations, which allows us to extend methods from
stochastic optimal control to address the activity guiding problem. We also
design an efficient algorithm, and show that our method guides user activities
to desired states more effectively than the state of the art.


title:
Variable p norm constrained LMS algorithm based on gradient of root
  relative deviation.pdf

abstract:
  A new Lp-norm constraint least mean square (Lp-LMS) algorithm with new
strategy of varying p is presented, which is applied to system identification
in this letter. The parameter p is iteratively adjusted by the gradient method
applied to the root relative deviation of the estimated weight vector.
Numerical simulations show that this new algorithm achieves lower steady-state
error as well as equally fast convergence compared with the traditional Lp-LMS
and LMS algorithms in the application setting of sparse system identification
in the presence of noise.


title:
Line tension and morphology of a droplet and a bubble attached to the
  inner wall of a spherical cavity

abstract:
  The effects of line tension on the morphology of a lens-shaped droplet and
bubble placed on the inner wall of a spherical cavity are studied. The contact
angle between the lens-shaped droplet and the concave spherical substrate is
expressed by the generalized Young's formula. The equator of the spherical
substrate is found to play a crucial role. Neither a droplet with its contact
line on the upper hemisphere of the substrate nor one with its contact line on
the lower hemisphere can transform into each other continuously. On a
hydrophobic substrate, the contact angle jumps discontinuously to
$180^{\circ}$, and the droplet is detached from the substrate to form a
spherical droplet when the line tension is positive and large. This is similar
to the drying transition on a flat substrate. On the other hand, on a
hydrophilic substrate, the contact angle jumps discontinuously to $0^{\circ}$
when the line tension is positive and large. Then, the droplet spread over the
whole inner wall to leave a spherical bubble. Therefore, not only the drying
transition but also the wetting transition is induced by positive line tension
on a concave spherical substrate. There also exist stable as well as metastable
droplets, whose phase diagrams can be complex. When the line tension is
negative and its magnitude increases, the contact line approaches the equator
infinitesimally from either above or below. However, it cannot cross the
equator of a spherical cavity continuously. The droplet with a contact line
that coincides with the equator is a singular droplet. The contact line is
pinned and cannot move, irrespective of the magnitude of the line tension.


title:
Liquid Surface X-ray Studies of Gold Nanoparticle-Phospholipid Films at
  the Air/Water Interface

abstract:
  Amphiphilic phospholipids and nanoparticles functionalized with hydrophobic
capping ligands have previously been extensively investigated for their
capacity to self-assemble into Langmuir monolayers at the air/water interface.
However, understanding of composite films consisting of both nanoparticles and
phospholipids, and by extension, the complex interactions arising between
nanomaterials and biological membranes, remains limited. In this work,
dodecanethiol-capped gold nanoparticles (Au-NPs) with an average core diameter
of 6 nm were incorporated into 1,2-dipalmitoyl-sn-glycero-3-phosphocholine
(DPPC) monolayers in area ratios ranging from 0.1 to 20% area coverage at a
surface pressure of 30 mN/m. High resolution liquid surface X-ray scattering
studies revealed a phase separation of the DPPC and Au-NP components of the
composite film, as confirmed with atomic force microscopy after the film was
transferred to a substrate. At low Au-NP content, the structural organization
of the phase-separated film is best described as a DPPC film containing
isolated islands of Au-NPs. However, increasing the Au-NP content beyond 5%
area coverage transforms the structural organization of the composite film to a
long-range interconnected network of Au-NP strands surrounding small seas of
DPPC, where the density of the Au-NP network increases with increasing Au-NP
content. The observed phase separation and structural organization of the
phospholipid and nanoparticle components in these Langmuir monolayers are
useful for understanding interactions of nanoparticles with biological
membranes.


title: Recurrent Batch Normalization

abstract:
  We propose a reparameterization of LSTM that brings the benefits of batch
normalization to recurrent neural networks. Whereas previous works only apply
batch normalization to the input-to-hidden transformation of RNNs, we
demonstrate that it is both possible and beneficial to batch-normalize the
hidden-to-hidden transition, thereby reducing internal covariate shift between
time steps. We evaluate our proposal on various sequential problems such as
sequence classification, language modeling and question answering. Our
empirical results show that our batch-normalized LSTM consistently leads to
faster convergence and improved generalization.


title: Uniform mixing and completely positive sofic entropy

abstract:
  Let $G$ be a countable discrete sofic group. We define a concept of uniform
mixing for measure-preserving $G$-actions and show that it implies completely
positive sofic entropy. When $G$ contains an element of infinite order, we use
this to produce an uncountable family of pairwise nonisomorphic $G$-actions
with completely positive sofic entropy. None of our examples is a factor of a
Bernoulli shift.


title: Palmprint Recognition Using Deep Scattering Convolutional Network

abstract:
  Palmprint recognition has drawn a lot of attention during the recent years.
Many algorithms have been proposed for palmprint recognition in the past,
majority of them being based on features extracted from the transform domain.
Many of these transform domain features are not translation or rotation
invariant, and therefore a great deal of preprocessing is needed to align the
images. In this paper, a powerful image representation, called scattering
network/transform, is used for palmprint recognition. Scattering network is a
convolutional network where its architecture and filters are predefined wavelet
transforms. The first layer of scattering network captures similar features to
SIFT descriptors and the higher-layer features capture higher-frequency content
of the signal which are lost in SIFT and other similar descriptors. After
extraction of the scattering features, their dimensionality is reduced by
applying principal component analysis (PCA) which reduces the computational
complexity of the recognition task. Two different classifiers are used for
recognition: multi-class SVM and minimum-distance classifier. The proposed
scheme has been tested on a well-known palmprint database and achieved accuracy
rate of 99.95% and 100% using minimum distance classifier and SVM respectively.


title: Abstract graph-like space and vector-valued metric graphs

abstract:
  In this note we present some abstract ideas how one can construct spaces from
building blocks according to a graph. The coupling is expressed via boundary
pairs, and can be applied to very different spaces such as discrete graphs,
quantum graphs or graph-like manifolds. We show a spectral analysis of
graph-like spaces, and consider as a special case vector-valued quantum graphs.
Moreover, we provide a prototype of a convergence theorem for shrinking
graph-like spaces with Dirichlet boundary conditions. (Dedicated to Pavel
Exner's 70th birthday)