title:
On the Link Between Energy Equipartition and Radial Variation in the
  Stellar Mass Function of Star Clusters

abstract:
  We make use of $N$-body simulations to determine the relationship between two
observable parameters that are used to quantify mass segregation and energy
equipartition in star clusters. Mass segregation can be quantified by measuring
how the slope of a cluster's stellar mass function $\alpha$ changes with
clustercentric distance r, and then calculating $\delta_\alpha = \frac{d
\alpha(r)}{d ln(r/r_m)}$ where $r_m$ is the cluster's half-mass radius. The
degree of energy equipartition in a cluster is quantified by $\eta$, which is a
measure of how stellar velocity dispersion $\sigma$ depends on stellar mass m
via $\sigma(m) \propto m^{-\eta}$. Through a suite of $N$-body star cluster
simulations with a range of initial sizes, binary fractions, orbits, black hole
retention fractions, and initial mass functions, we present the co-evolution of
$\delta_\alpha$ and $\eta$. We find that measurements of the global $\eta$ are
strongly affected by the radial dependence of $\sigma$ and mean stellar mass
and the relationship between $\eta$ and $\delta_\alpha$ depends mainly on the
cluster's initial conditions and the tidal field. Within $r_m$, where these
effects are minimized, we find that $\eta$ and $\delta_\alpha$ initially share
a linear relationship. However, once the degree of mass segregation increases
such that the radial dependence of $\sigma$ and mean stellar mass become a
factor within $r_m$, or the cluster undergoes core collapse, the relationship
breaks down. We propose a method for determining $\eta$ within $r_m$ from an
observational measurement of $\delta_\alpha$. In cases where $\eta$ and
$\delta_\alpha$ can be measured independently, this new method offers a way of
measuring the cluster's dynamical state.


title: Construction of all N=4 conformal supergravities

abstract:
  All N=4 conformal supergravities in four space-time dimensions are
constructed. These are the only N=4 supergravity theories whose actions are
invariant under off-shell supersymmetry. They are encoded in terms of a
holomorphic function that is homogeneous of zeroth degree in scalar fields that
parametrize an SU(1,1)/U(1) coset space. When this function equals a constant
the Lagrangian is invariant under continuous SU(1,1) transformations. The
construction of these higher-derivative invariants also opens the door to
various applications for non-conformal theories.


title:
Odd-parity superconductivity near inversion breaking quantum critical
  point in one dimension

abstract:
  We study how an inversion-breaking quantum critical point affects the ground
state of a one-dimensional electronic liquid with repulsive interaction and
spin-orbit coupling. We find that regardless of the interaction strength, the
critical fluctuations always lead to a gap in the electronic spin-sector. The
origin of the gap is a two-particle backscattering process, which becomes
relevant due to renormalization of the Luttinger parameter near the critical
point. The resulting spin-gapped state is a one-dimensional version of spin
triplet superconductivity. Interestingly, in the case of a ferromagnetic
critical point the Luttinger parameter is renormalized in the opposite manner,
such that the system remains non-superconducting.


title: The-wiZZ: Clustering redshift estimation for everyone

abstract:
  We present The-wiZZ, an open source and user-friendly software for estimating
the redshift distributions of photometric galaxies with unknown redshifts by
spatially cross-correlating them against a reference sample with known
redshifts. The main benefit of The-wiZZ is in separating the angular pair
finding and correlation estimation from the computation of the output
clustering redshifts allowing anyone to create a clustering redshift for their
sample without the intervention of an "expert". It allows the end user of a
given survey to select any sub-sample of photometric galaxies with unknown
redshifts, match this sample's catalog indices into a value-added data file,
and produce a clustering redshift estimation for this sample in a fraction of
the time it would take to run all the angular correlations needed to produce a
clustering redshift. We show results with this software using photometric data
from the Kilo-Degree Survey (KiDS) and spectroscopic redshifts from the Galaxy
and Mass Assembly (GAMA) survey and the Sloan Digital Sky Survey (SDSS). The
results we present for KiDS are consistent with the redshift distributions used
in a recent cosmic shear analysis from the survey. We also present results
using a hybrid machine learning-clustering redshift analysis that enables the
estimation of clustering redshifts for individual galaxies. The-wiZZ can be
downloaded at http://github.com/morriscb/The-wiZZ/.


title:
Conductance spectroscopy of nontopological-topological superconductor
  junctions

abstract:
  We calculate the zero-temperature differential conductance $dI/dV$ of a
voltage-biased one-dimensional junction between a nontopological and a
topological superconductor for arbitrary junction transparency using the
scattering matrix formalism. We consider two representative models for the
topological superconductors: (i) spinful $p$-wave and (ii) $s$-wave with
spin-orbit coupling and spin splitting. We verify that in the tunneling limit
(small junction transparencies) where only single Andreev reflections
contribute to the current, the conductance for voltages below the
nontopological superconductor gap $\Delta_s$ is zero and there are two
symmetric conductance peaks appearing at $eV = \pm \Delta_s$ with the quantized
value $(4-\pi)2e^2/h$ due to resonant Andreev reflection from the Majorana zero
mode. However, when the junction transparency is not small, there is a finite
conductance for $e|V| < \Delta_s$ arising from multiple Andreev reflections.
The conductance at $eV = \pm \Delta_s$ in this case is no longer quantized. In
general, the conductance is particle-hole asymmetric except for sufficiently
small transparencies. We further show that, for certain values of parameters,
the tunneling conductance from a zero-energy conventional Andreev bound state
can be made to mimic the conductance from a true Majorana mode.


title: Detection of phase transition via convolutional neural network

abstract:
  We design a Convolutional Neural Network (CNN) which studies correlation
between discretized inverse temperature and spin configuration of 2D Ising
model and show that it can find a feature of the phase transition without
teaching any a priori information for it. We also define a new order parameter
via the CNN and show that it provides well approximated critical inverse
temperature. In addition, we compare the activation functions for convolution
layer and find that the Rectified Linear Unit (ReLU) is important to detect the
phase transition of 2D Ising model.


title:
$\boldsymbol{\mu^-}$- $\boldsymbol{e^+}$ conversion in upcoming LFV
  experiments

abstract:
  We present an illustrative discussion of the physics potential of $\mu^-$-
$e^+$ conversion. We point out that this process, although much less frequently
studied than the related but much more popular processes of $\mu^-$- $e^-$
conversion and neutrinoless double beta decay, in fact is a promising
alternative possibility to detect both lepton flavour and number violation.
However, for this goal to be reached, a combined effort of experiments and
theory, both in nuclear and particle physics, is necessary to advance. The aim
of this paper is to be an "appetiser" to trigger such an initiative.


title:
Floquet prethermalization and regimes of heating in a periodically
  driven, interacting quantum system

abstract:
  We study the regimes of heating in the periodically driven $O(N)$-model,
which represents a generic model for interacting quantum many-body systems. By
computing the absorbed energy with a non-equilibrium Keldysh Green's function
approach, we establish three dynamical regimes: at short times a
single-particle dominated regime, at intermediate times a stable Floquet
prethermal regime in which the system ceases to absorb, and at parametrically
late times a thermalizing regime. Our simulations suggest that in the
thermalizing regime the absorbed energy grows algebraically in time with an the
exponent that approaches the universal value of $1/2$, and is thus
significantly slower than linear Joule heating. Our results demonstrate the
parametric stability of prethermal states in a generic many-body system driven
at frequencies that are comparable to its microscopic scales. This paves the
way for realizing exotic quantum phases, such as time crystals or interacting
topological phases, in the prethermal regime of interacting Floquet systems.


title:
PRIMUS+DEEP2: The Dependence of Galaxy Clustering on Stellar Mass and
  Specific Star Formation Rate at 0.2 < z < 1.2

abstract:
  We present results on the clustering properties of galaxies as a function of
both stellar mass and specific star formation rate (sSFR) using data from the
PRIMUS and DEEP2 galaxy redshift surveys spanning 0.2 < z < 1.2. We use
spectroscopic redshifts of over 100,000 galaxies covering an area of 7.2 deg^2
over five separate fields on the sky, from which we calculate cosmic variance
errors. We find that the galaxy clustering amplitude is as strong of a function
of sSFR as of stellar mass, and that at a given sSFR, it does not significantly
depend on stellar mass within the range probed here. We further find that
within the star-forming population and at a given stellar mass, galaxies above
the main sequence of star formation with higher sSFR are less clustered than
galaxies below the main sequence with lower sSFR. We also find that within the
quiescent population, galaxies with higher sSFR are less clustered than
galaxies with lower sSFR, at a given stellar mass. We show that the galaxy
clustering amplitude smoothly increases with both increasing stellar mass and
decreasing sSFR, implying that galaxies likely evolve across the main sequence,
not only along it, before galaxies eventually become quiescent. These results
imply that the stellar mass to halo mass relation, which connects galaxies to
dark matter halos, likely depends on sSFR.


title: Cosmology with AGN dust time lags -- Simulating the new VEILS survey

abstract:
  The time lag between optical and near-infrared continuum emission in active
galactic nuclei (AGN) shows a tight correlation with luminosity and has been
proposed as a standardisable candle for cosmology. In this paper, we explore
the use of these AGN hot-dust time lags for cosmological model fitting under
the constraints of the new VISTA Extragalactic Infrared Legacy Survey VEILS.
This new survey will target a 9 deg^2 field observed in J- and Ks-band with a
14-day cadence and will run for three years. The same area will be covered
simultaneously in the optical griz bands by the Dark Energy Survey, providing
complementary time-domain optical data. We perform realistic simulations of the
survey setup, showing that we expect to recover dust time lags for about 450
objects out of a total of 1350 optical type 1 AGN, spanning a redshift range of
0.1 < z < 1.2. We use the lags recovered from our simulations to calculate
precise distance moduli, establish a Hubble diagram, and fit cosmological
models. Assuming realistic scatter in the distribution of the dust around the
AGN as well as in the normalisation of the lag-luminosity relation, we are able
to constrain {\Omega}_{\Lambda} in {\Lambda}CDM with similar accuracy as
current supernova samples. We discuss the benefits of combining AGN and
supernovae for cosmology and connect the present work to future attempts to
reach out to redshifts of z > 4.


title:
A zero-sum stochastic differential game with impulses, precommitment,
  and unrestricted cost functions

abstract:
  We study a zero-sum stochastic differential game (SDG) in which one
controller plays an impulse control while their opponent plays a stochastic
control. We consider an asymmetric setting in which the impulse player commits
to, at the start of the game, performing less than q impulses (q can be chosen
arbitrarily large). In order to obtain the uniform continuity of the value
functions, previous works involving SDGs with impulses assume the cost of an
impulse to be decreasing in time. Our work avoids such restrictions by
requiring impulses to occur at rational times. We establish that the resulting
game admits a value, and in turn, the existence and uniqueness of viscosity
solutions to an associated Hamilton-Jacobi-Bellman-Isaacs quasi-variational
inequality.


title:
Two Distinct-Absorption X-Ray Components from Type IIn Supernovae:
  Evidence for Asphericity in the Circumstellar Medium

abstract:
  We present multi-epoch X-ray spectral observations of three Type IIn
supernovae (SNe) 2005kd, 2006jd, and 2010jl, acquired with Chandra, XMM-Newton,
Suzaku, and Swift. Previous extensive X-ray studies of SN 2010jl have revealed
that X-ray spectra are dominated by thermal emission, which likely arises from
a hot plasma heated by a forward shock propagating into a massive circumstellar
medium (CSM). Interestingly, an additional soft X-ray component was required to
reproduce the spectra at a period of ~1-2 yr after the SN explosion. Although
this component is likely associated with the SN, its origin remained an open
question. We find a similar, additional soft X-ray component from the other two
SNe IIn as well. Given this finding, we present a new interpretation for the
origin of this component; it is thermal emission from a forward shock
essentially identical to the hard X-ray component, but directly reaches us from
a void of the dense CSM. Namely, the hard and soft components are responsible
for the heavily- and moderately-absorbed components, respectively. The
co-existence of the two components with distinct absorptions as well as the
delayed emergence of the moderately-absorbed X-ray component would be evidence
for asphericity of the CSM. We show that the X-ray spectral evolution can be
qualitatively explained by considering a torus-like geometry for the dense CSM.
Based on our X-ray spectral analyses, we estimate the radius of the torus-like
CSM to be on the order of ~5 times 10^{16} cm.


title: Beyond the Maltese cross: geometry of turbulence between 0.2 and 1 AU

abstract:
  The spectral anisotropy of turbulent structures has been measured in the
solar wind since 1990, relying on the assumption of axisymmetry about the mean
magnetic field, B0. However, several works indicate that this hypothesis might
be partially wrong, thus raising two questions: (i) is it correct to interpret
measurements at 1 AU (the so-called Maltese cross) in term of a sum of slab and
2D turbulence? (ii) what information is really contained in the Maltese cross?
  We solve direct numerical simulations of the MHD equations including the
transverse stretching exerted by the solar wind flow and study the genuine 3D
anisotropy of turbulence as well as that one resulting from the assumption of
axisymmetry about B0. We show that the evolution of the turbulent spectrum from
0.2 to 1 AU depends strongly on its initial anisotropy. An axisymmetric
spectrum with respect to B0 keeps its axisymmetry, i.e., resists stretching
perpendicular to radial, while an isotropic spectrum becomes essentially
axisymmetric with respect to the radial direction.
  We conclude that close to the Sun, slow-wind turbulence has a spectrum that
is axisymmetric around B0 and the measured 2D component at 1 AU describes the
real shape of turbulent structures. On the contrary, fast-wind turbulence has a
more isotropic spectrum at the source and becomes radially symmetric at 1 AU.
Such structure is hidden by the symmetrization applied to the data that instead
returns a slab geometry.


title:
Dynamical Mass Measurement of the Young Spectroscopic Binary V343 Normae
  AaAb Resolved With the Gemini Planet Imager

abstract:
  We present new spatially resolved astrometry and photometry from the Gemini
Planet Imager of the inner binary of the young multiple star system V343
Normae, which is a member of the beta Pictoris moving group. V343 Normae
comprises a K0 and mid-M star in a ~4.5 year orbit (AaAb) and a wide 10" M5
companion (B). By combining these data with archival astrometry and radial
velocities we fit the orbit and measure individual masses for both components
of M_Aa = 1.10 +/- 0.10 M_sun and M_Ab = 0.290 +/- 0.018 M_sun. Comparing to
theoretical isochrones, we find good agreement for the measured masses and JHK
band magnitudes of the two components consistent with the age of the beta Pic
moving group. We derive a model-dependent age for the beta Pic moving group of
26 +/- 3 Myr by combining our results for V343 Normae with literature
measurements for GJ 3305, which is another group member with resolved binary
components and dynamical masses.


title:
Matrix models for multilevel Heckman-Opdam and multivariate Bessel
  measures

abstract:
  We study multilevel matrix ensembles at general beta by identifying them with
a class of processes defined via the branching rules for multivariate Bessel
and Heckman-Opdam hypergeometric functions. For beta = 1, 2, we express the
joint multilevel density of the eigenvalues of a generalized beta-Wishart
matrix as a multivariate Bessel ensemble, generalizing a result of
Dieker-Warren. In the null case, we prove the conjecture of Borodin-Gorin that
the joint multilevel density of the beta-Jacobi ensemble is given by a
principally specialized Heckman-Opdam measure.


title: The First Six Outbursting Cool DA White Dwarf Pulsators

abstract:
  Extensive observations from the Kepler spacecraft have recently revealed a
new outburst phenomenon operating in cool pulsating DA (hydrogen atmosphere)
white dwarfs (DAVs). With the introduction of two new outbursting DAVs from K2
Fields 7 (EPIC 229228364) and 8 (EPIC 220453225) in these proceedings, we
presently know of six total members of this class of object. We present the
observational commonalities of the outbursting DAVs: (1) outbursts that
increase the mean stellar flux by up to 15%, last many hours, and recur
irregularly on timescales of days; (2) effective temperatures that locate them
near the cool edge of the DAV instability strip; and (3) rich pulsation spectra
with modes that are observed to wander in amplitude/frequency.


title: A generalization of the Grid Theorem

abstract:
  A graph has tree-width at most $k$ if it can be obtained from a set of graphs
each with at most $k+1$ vertices by a sequence of clique sums. We refine this
definition by, for each non-negative integer $\theta$, defining the
$\theta$-tree-width of a graph to be at most $k$ if it can be obtained from a
set of graphs each with at most $k+1$ vertices by a sequence of clique sums on
cliques of size less than $\theta$. We find the unavoidable minors for the
graphs with large $\theta$-tree-width and we obtain Robertson and Seymour's
Grid Theorem as a corollary.


title: The rate of stellar encounters along a migrating orbit of the Sun

abstract:
  The frequency of Galactic stellar encounters the Solar system experienced
depends on the local density and velocity dispersion along the orbit of the Sun
in the Milky Way galaxy. We aim at determining the effect of the radial
migration of the solar orbit on the rate of stellar encounters. As a first step
we integrate the orbit of the Sun backwards in time in an analytical potential
of the Milky Way. We use the present-day phase-space coordinates of the Sun,
according to the measured uncertainties. The resulting orbits are inserted in
an N-body simulation of the Galaxy, where the stellar velocity dispersion is
calculated at each position along the orbit of the Sun. We compute the rate of
Galactic stellar encounters by employing three different solar orbits
---migrating from the inner disk, without any substantial migration, and
migrating from the outer disk. We find that the rate for encounters within
$4\times10^5$ AU from the Sun is approximately 21, 39 and 63 Myr$^{-1}$,
respectively. The stronger encounters establish the outer limit of the
so-called parking zone, which is the region in the plane of the orbital
eccentricities and semi-major axes where the planetesimals of the Solar system
have been perturbed only by interactions with stars belonging to the Sun's
birth cluster. We estimate the outer edge of the parking zone at semi-major
axes of 250--1300 AU (the outward and inward migrating orbits reaching the
smallest and largest values, respectively), which is one order of magnitude
smaller than the determination made by Portegies Zwart & J\'ilkov\'a (2015). We
further discuss the effect of stellar encounters on the stability of the
hypothetical Planet 9.


title:
Spitzer Observations of Long Term Infrared Variability Among Young
  Stellar Objects in Chamaeleon I

abstract:
  Infrared variability is common among young stellar objects, with surveys
finding daily to weekly fluctuations of a few tenths of a magnitude.
Space-based observations can produce highly sampled infrared light curves, but
are often limited to total baselines of about a month due to the orientation of
the spacecraft. Here we present observations of the Chameleon I cluster whose
low declination makes it observable by the Spitzer space telescope over a 200
day period. We observe 30 young stellar objects with a daily cadence to better
sample variability on timescales of months. We find such variability is common,
occurring in ~80% of the detected cluster members. The change in [3.6]-[4.5]
color over 200 days for many of the sources falls between that expected for
extinction and fluctuations in disk emission. With our high cadence and long
baseline we can derive power spectral density curves covering two orders of
magnitude in frequency and find significant power at low frequencies, up to the
boundaries of our 200 day survey. Such long timescales are difficult to explain
with variations driven by the interaction between the disk and stellar magnetic
field, which has a dynamical timescale of days to weeks. The most likely
explanation is either structural or temperature fluctuations spread throughout
the inner ~0.5 au of the disk, suggesting that the intrinsic dust structure is
highly dynamic.


title:
Reaching Higher Densities for Laboratory White Dwarf Photospheres to
  Measure Spectroscopic Line Profiles

abstract:
  As part of our laboratory investigation of the theoretical line profiles used
in white dwarf atmosphere models, we extend the electron-density ($n_{\rm e}$)
range measured by our experiments to higher densities (up to
$n_{e}\sim80\times10^{16}$ cm$^{-3}$). Whereas inferred parameters using the
hydrogen-$\beta$ spectral line agree among different line-shape models for
$n_{\rm e}\lesssim30\times10^{16}$ cm$^{-3}$, we now see divergence between
models. These are densities beyond the range previously benchmarked in the
laboratory, meaning theoretical profiles in this regime have not been fully
validated. Experimentally exploring these higher densities enables us to test
and constrain different line-profile models, as the differences in their
relative H-Balmer line shapes are more pronounced at such conditions. These
experiments also aid in our study of occupation probabilities because we can
measure these from relative line strengths.


title: BiTeCl and BiTeBr: a comparative high-pressure optical study

abstract:
  We here report a detailed high-pressure infrared transmission study of BiTeCl
and BiTeBr. We follow the evolution of two band transitions: the optical
excitation $\beta$ between two Rashba-split conduction bands, and the
absorption $\gamma$ across the band gap. In the low pressure range, $p< 4$~GPa,
for both compounds $\beta$ is approximately constant with pressure and $\gamma$
decreases, in agreement with band structure calculations. In BiTeCl, a clear
pressure-induced phase transition at 6~GPa leads to a different ground state.
For BiTeBr, the pressure evolution is more subtle, and we discuss the
possibility of closing and reopening of the band gap. Our data is consistent
with a Weyl phase in BiTeBr at 5$-$6~GPa, followed by the onset of a structural
phase transition at 7~GPa.


title:
Global asymptotic stability of a PID control system with Coulomb
  friction

abstract:
  We propose a model for representing a point mass subject to Coulomb friction
in feedback with a PID controller, based on a differential inclusion comprising
all the possible magnitudes of static friction during the stick phase. For this
model we study the set of all equilibria and we establish its global asymptotic
stability using a discontinuous Lyapunov-like function, and a suitable
LaSalle's invariance principle. We finally use well-posedness of the proposed
model to establish useful robustness results, including an ISS property from a
suitable input in a perturbed context. Simulation results are also given to
illustrate our statements.


title:
Boxes, Boosts, and Energy Duality: Understanding the Galactic-Center
  Gamma-Ray Excess through Dynamical Dark Matter

abstract:
  Many models currently exist which attempt to interpret the excess of gamma
rays emanating from the Galactic Center in terms of annihilating or decaying
dark matter. These models typically exhibit a variety of complicated cascade
mechanisms for photon production, leading to a non-trivial kinematics which
obscures the physics of the underlying dark sector. In this paper, by contrast,
we observe that the spectrum of the gamma-ray excess may actually exhibit an
intriguing "energy-duality" invariance under $E_\gamma \rightarrow
E_\ast^2/E_\gamma$ for some $E_\ast$. As we shall discuss, such an energy
duality points back to a remarkably simple alternative kinematics which in turn
is realized naturally within the Dynamical Dark Matter framework. Observation
of this energy duality could therefore provide considerable information about
the properties of the dark sector from which the Galactic-Center gamma-ray
excess might arise, and highlights the importance of acquiring more complete
data for the Galactic-Center excess in the energy range around 1 GeV.

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


title: Sub-Doppler Laser Cooling using Electromagnetically Induced Transparency

abstract:
  We propose a sub-Doppler laser cooling mechanism that takes advantage of the
unique spectral features and extreme dispersion generated by the phenomenon of
electromagnetically induced transparency (EIT). EIT is a destructive quantum
interference phenomenon experienced by atoms with multiple internal quantum
states when illuminated by laser fields with appropriate frequencies. By
detuning the lasers slightly from the "dark resonance", we observe that, within
the transparency window, atoms can be subject to a strong viscous force, while
being only slightly heated by the diffusion caused by spontaneous photon
scattering. In contrast to other laser cooling schemes, such as polarization
gradient cooling or EIT-sideband cooling, no external magnetic field or strong
external confining potential is required. Using a semiclassical approximation,
we derive analytically quantitative expressions for the steady-state
temperature, which is confirmed by full quantum mechanical numerical
simulations. We find that the lowest achievable temperatures approach the
single-photon recoil energy. In addition to dissipative forces, the atoms are
subject to a stationary conservative potential, leading to the possibility of
spatial confinement. We find that under typical experimental parameters this
effect is weak and stable trapping is not possible.


title: HyperNetworks

abstract:
  This work explores hypernetworks: an approach of using a one network, also
known as a hypernetwork, to generate the weights for another network.
Hypernetworks provide an abstraction that is similar to what is found in
nature: the relationship between a genotype - the hypernetwork - and a
phenotype - the main network. Though they are also reminiscent of HyperNEAT in
evolution, our hypernetworks are trained end-to-end with backpropagation and
thus are usually faster. The focus of this work is to make hypernetworks useful
for deep convolutional networks and long recurrent networks, where
hypernetworks can be viewed as relaxed form of weight-sharing across layers.
Our main result is that hypernetworks can generate non-shared weights for LSTM
and achieve near state-of-the-art results on a variety of sequence modelling
tasks including character-level language modelling, handwriting generation and
neural machine translation, challenging the weight-sharing paradigm for
recurrent networks. Our results also show that hypernetworks applied to
convolutional networks still achieve respectable results for image recognition
tasks compared to state-of-the-art baseline models while requiring fewer
learnable parameters.


title:
Effect of long-range interactions on the phase transition of Axelrod's
  model

abstract:
  Axelrod's model with $F=2$ cultural features, where each feature can assume
$k$ states drawn from a Poisson distribution of parameter $q$, exhibits a
continuous nonequilibrium phase transition in the square lattice. Here we use
extensive Monte Carlo simulations and finite size scaling to study the critical
behavior of the order parameter $\rho$, which is the fraction of sites that
belong to the largest domain of an absorbing configuration averaged over many
runs. We find that it vanishes as $\rho \sim \left (q_c^0 - q \right)^\beta$
with $\beta \approx 0.25$ at the critical point $q_c^0 \approx 3.10$ and that
the exponent that measures the width of the critical region is $\nu^0 \approx
2.1$. In addition, we find that introduction of long-range links by rewiring
the nearest-neighbors links of the square lattice with probability $p$ turns
the transition discontinuous, with the critical point $q_c^p$ increasing from
$3.1$ to $27.17$, approximately, as $p$ increases from $0$ to $1$. The
sharpness of the threshold, as measured by the exponent $\nu^p \approx 1$ for
$p>0$, increases with the square root of the number of nodes of the resulting
small-world network.


title: Rapid TeV Flaring in Markarian 501

abstract:
  We investigate rapid TeV flaring in markarian 501 in the frame of a
time-dependent one-zone synchrotron self-Compton (SSC) model. Inthis model,
electrons are accelerated to extra-relativistic energy through the stochastic
particle acceleration and evolve with the time, nonthermal photons are produced
by both synchrotron and inverse Comtpon scattering off synchrotron photons.
Moreover, nonthermal photons during a pre-flare are produced by the
relativistic electrons in the steady state and those during a flare are
produced by the electrons whose injection rate is changed at some time
interval. We apply the model to the rapid flare of Markarian 501 on July 9,
2005 and obtain the multi-wavelength spectra during the pre-flare and during
the flare. Our results show that the time-dependent properties of flares can be
reproduced by varying the injection rate of electrons and a clear canonical
anti-clockwise-loop can be given.


title: William Pendry Bidelman (1918-2011)

abstract:
  William P. Bidelman--Editor of Publications of the Astronomical Society of
the Pacific from 1956 to 1961--passed away on 2011 May 3, at the age of 92. He
was one of the last of the masters of visual stellar spectral classification
and the identification of peculiar stars. I review his contributions to these
subjects, including the discoveries of barium stars, hydrogen-deficient stars,
high-galactic-latitude supergiants, stars with anomalous carbon content, and
exotic chemical abundances in peculiar A and B stars. Bidelman was legendary
for his encyclopedic knowledge of the stellar literature. He had a profound and
inspirational influence on many colleagues and students. Some of the bizarre
stellar phenomena he discovered remain unexplained to the present day.


title: A Bilocal Model for the Relativistic Spinning Particle

abstract:
  In this work we show that a relativistic spinning particle can be described
at the classical and the quantum level as being composed of two physical
constituents which are entangled and separated by a fixed distance. This
bilocal model for spinning particles allows for a natural description of
particle interactions as a local interaction at each of the constituents. This
form of the interaction vertex provides a resolution to a long standing issue
on the nature of relativistic interactions for spinning objects in the context
of the worldline formalism. It also potentially brings a dynamical explanation
for why massive fundamental objects are naturally of lowest spin. We analyze
first a non-relativistic system where spin is modeled as an entangled state of
two particles with the entanglement encoded into a set of constraints. It is
shown that these constraints can be made relativistic and that the resulting
description is isomorphic to the usual description of the phase space of
massive relativistic particles with the restriction that the quantum spin has
to be an integer.


title: Efficient Evaluation of Massive Mellin--Barnes Integrals

abstract:
  We show how to evaluate one-dimensional Minkowski-region Mellin-Barnes
representations arising from massive loop integrals, by modifying the contours
of integration. We implement an exact solution to the differential equation
determining the contours of stationary phase. We also present several simple
approximations to these contours. Our approach points the way to more efficient
computations of massless and massive Mellin-Barnes integrals in both Euclidean
and Minkowski regions.


title:
Energy budget of forming clumps in numerical simulations of collapsing
  clouds

abstract:
  We analyze the physical properties and energy balance of density enhancements
in two SPH simulations of the formation, evolution, and collapse of giant
molecular clouds. In the simulations, no feedback is included, so all motions
are due either to the initial, decaying turbulence, or to gravitational
contraction. We define clumps as connected regions above a series of density
thresholds. The resultingfull set of clumps follows the generalized
energy-equipartition relation $\sigma_{v}/R^{1/2} \propto \Sigma^{1/2}$, where
$\sigma_{v}$ is the velocity dispersion, $R$ is the "radius", and $\Sigma$ is
the column density. We interpret this as a natural consequence of gravitational
contraction at all scales, rather than virial equilibrium. Nevertheless, clumps
with low $\Sigma$ tend to show a large scatter around equipartition. In more
than half of the cases, this scatter is dominated by external turbulent
compressions that {\it assemble} the clumps, rather than by small-scale random
motions that would disperse them. The other half does actually disperse.
Moreover, clump sub-samples selected by means of different criteria exhibit
different scalings. Sub-samples with narrow $\Sigma$ ranges follow Larson-like
relations, although characterized by their respective value of $\Sigma$.
Finally, we find that: i) clumps lying in filaments tend to appear sub-virial;
ii) high-density cores ($n \ge 10^5$ cm$^3$) that exhibit moderate kinetic
energy excesses often contain sink ("stellar") particles, and the excess
disappears when the stellar mass is taken into account in the energy balance;
iii) cores with kinetic energy excess but no stellar particles are truly in a
state of dispersal.


title: On Large N Expansion of the Sphere Free Energy

abstract:
  We propose formulas for the $1/N$ correction to the sphere free energy of
theories with 4-fermion interactions, which are conformal for $d>2$. We also
propose a formula for the scalar $O(N)$ model. Expanding these formulas in
small $\epsilon$ near various integer dimensions we find a perfect agreement
with results obtained using $\epsilon$-expansion technique. In $d=3$, the large
$N$ results with the $1/N$ correction included are in good agreement with the
Pade resummed $\epsilon$-expansion.


title:
Formation of Tidal Captures and Gravitational Wave Inspirals in
  Binary-Single Interactions

abstract:
  We perform the first systematic study on how dynamical stellar tides and
general relativistic (GR) effects affect the dynamics and outcomes of
binary-single interactions. For this, we have constructed an N-body code that
includes tides in the affine approximation, where stars are modeled as
self-similar ellipsoidal polytropes, and GR corrections using the commonly-used
post-Newtonian formalism. Using this numerical formalism, we are able resolve
the leading effect from tides and GR across several orders of magnitude in both
stellar radius and initial target binary separation. We find that the main
effect from tides is the formation of two-body tidal captures that form during
the chaotic and resonant evolution of the triple system. The two stars
undergoing the capture spiral in and merge. The inclusion of tides can thus
lead to an increase on the stellar coalescence rate. We also develop an
analytical framework for calculating the cross section of tidal inspirals
between any pair of objects with similar mass. From our analytical and
numerical estimates we find that the rate of tidal inspirals relative to
collisions increases as the initial semi-major axis of the target binary
increases and the radius of the interacting tidal objects decreases. The
largest effect is therefore found for triple systems hosting white dwarfs and
neutron stars. In this case, we find the rate of highly eccentric white dwarf -
neutron star mergers to likely be dominated by tidal inspirals. While tidal
inspirals occur rarely, we note that they can give rise to a plethora of
thermonuclear transients such as Ca-rich transients.


title: Discrete Mixed Volume and Hodge-Deligne Numbers

abstract:
  Generalizing the famous Bernstein-Kushnirenko Theorem, Khovanskii proved in
1978 a combinatorial formula for the arithmetic genus of the compactification
of a generic complete intersection associated to a family of lattice polytopes.
Recently, an analogous combinatorial formula, called the discrete mixed volume,
was introduced by Bihan and shown to be nonnegative. By making a footnote of
Khovanskii in his paper explicit, we interpret this invariant as the (motivic)
arithmetic genus of the non-compact generic complete intersection associated to
the family of lattice polytopes.


title:
Analysis of Massive Heterogeneous Temporal-Spatial Data with 3D
  Self-Organizing Map and Time Vector

abstract:
  Self-organizing map(SOM) have been widely applied in clustering, this paper
focused on centroids of clusters and what they reveal. When the input vectors
consists of time, latitude and longitude, the map can be strongly linked to
physical world, providing valuable information. Beyond basic clustering, a
novel approach to address the temporal element is developed, enabling 3D SOM to
track behaviors in multiple periods concurrently. Combined with adaptations
targeting to process heterogeneous data relating to distribution in time and
space, the paper offers a fresh scope for business and services based on
temporal-spatial pattern.


title:
Second-harmonic generation in periodically-poled thin film lithium
  niobate wafer-bonded on silicon

abstract:
  Second-order optical nonlinear effects (second-harmonic and sum-frequency
generation) are demonstrated in the telecommunication band by periodic poling
of thin films of lithium niobate wafer-bonded on silicon substrates and
rib-loaded with silicon nitride channels to attain ridge waveguide with
cross-sections of ~ 2 {\mu}m2. The compactness of the waveguides results in
efficient second-order nonlinear devices. A nonlinear conversion of 8% is
obtained with a pulsed input in 4 mm long waveguides. The choice of silicon
substrate makes the platform potentially compatible with silicon photonics, and
therefore may pave the path towards on-chip nonlinear and quantum-optic
applications.


title: Cycle Spaces of Digraphs

abstract:
  The cycle space of a graph corresponds to the kernel of an incidence matrix.
We investigate an analogous subspace for digraphs. In the case of digraphs of
graphs, where every edge is replaced by two oppositely directed arcs, we give a
combinatorial description of a basis of such a space. We are motivated by a
connection to the transition matrices of discrete-time quantum walks.


title: Sums of CR functions from competing CR structures

abstract:
  In this paper we characterize sums of CR functions from competing CR
structures in two scenarios. In one scenario the structures are conjugate and
we are adding to the theory of pluriharmonic boundary values. In the second
scenario the structures are related by projective duality considerations. In
both cases we provide explicit vector field-based characterizations for
two-dimensional circular domains satisfying natural convexity conditions.


title:
Nonanalyticity of the induced Carroll-Field-Jackiw term at finite
  temperature

abstract:
  In this paper, we discuss the behavior of the Carroll-Field-Jackiw (CFJ)
coefficient $k^{\mu}$ arising due to integration over massive fermions, and the
modification suffered by its topological structure in the finite temperature
case. Our study is based on the imaginary time formalism and summation over the
Matsubara frequencies. We demonstrate that the self-energy of photon is
non-analytic for the small $k^{\mu}$ limit, i.e., the static limit $(k_0=0,\vec
k\rightarrow 0)$ and the long wavelength limit $(k_0\rightarrow 0,\vec k= 0)$
do not commute, while the tensorial structure of the CFJ term holds in both
limits.


title: New exotic minimal sets from pseudo-suspensions of Cantor systems

abstract:
  We develop a technique, pseudo-suspension, that applies to invariant sets of
homeomorphisms of a class of annulus homeomorphisms we describe,
Handel-Anosov-Katok (HAK) homeomorphisms, that generalize the homeomorphism
first described by Handel. Given a HAK homeomorphism and a homeomorphism of the
Cantor set, the pseudo-suspension yields a homeomorphism of a new space that
admits a homeomorphism that combines features of both of the original
homeomorphisms. This allows us to answer a well known open question by
providing examples of hereditarily indecomposable continua that admit
homeomorphisms of intermediate complexity. Additionally, we show that such
examples occur as minimal sets of volume preserving smooth diffeomorphisms of
4-dimensional manifolds. We also use our techniques to exhibit the first
examples of minimal, uniformly rigid and weakly mixing homeomorphisms in
dimension $1$, and these can also be realized as invariant sets of smooth
diffeomorphisms of a 4-manifold. Until now the only known examples of spaces
that admit minimal, uniformly rigid and weakly mixing homeomorphisms were
modifications of those given by Glasner and Maon in dimension at least $2$.


title: Sharp Dirac's Theorem for DP-Critical Graphs

abstract:
  Correspondence coloring, or DP-coloring, is a generalization of list coloring
introduced recently by Dvo\v{r}\'{a}k and Postle. In this paper we establish a
version of Dirac's theorem on the minimum number of edges in critical graphs in
the framework of DP-colorings. A corollary of our main result answers a
question posed by Kostochka and Stiebitz on classifying list-critical graphs
that satisfy Dirac's bound with equality.


title: Nonlinear (Super)Symmetries and Amplitudes

abstract:
  There is an increasing interest in nonlinear supersymmetries in cosmological
model building. Independently, elegant expressions for the all-tree amplitudes
in models with nonlinear symmetries, like D3 brane
Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the
generalized background field method we show how, in general, nonlinear
symmetries of the action, bosonic and fermionic, constrain amplitudes beyond
soft limits. The same identities control, for example, bosonic E_{7(7)} scalar
sector symmetries as well as the fermionic goldstino symmetries.
  We present a universal derivation of the vanishing amplitudes in the single
(bosonic or fermionic) soft limit. We explain why, universally, the double-soft
limit probes the coset space algebra. We also provide identities describing the
multiple-soft limit. We discuss loop corrections to N\geq 5 supergravity, to
the D3 brane, and the UV completion of constrained multiplets in string theory.


title: Efficient Sorting of Free Electron Orbital Angular Momentum

abstract:
  We propose a method for sorting electrons by orbital angular momentum (OAM).
Several methods now exist to prepare electron wavefunctions in OAM states, but
no technique has been developed for efficient, parallel measurement of pure and
mixed electron OAM states. The proposed technique draws inspiration from the
recent demonstration of the sorting of OAM through modal transformation. We
show that the same transformation can be performed with electrostatic electron
optical elements. Specifically, we show that a charged needle and an array of
electrodes perform the transformation and phase correction necessary to sort
orbital angular momentum states. This device may enable the analysis of the
spatial mode distribution of inelastically scattered electrons.


title:
Rotated $\mu$\,--\,$\tau$ Symmetry for One Generic Neutrino Mixing
  Angle: An analytical Study

abstract:
  We find a realization of the $Z_2$-symmetry in the neutrino mass matrix which
expresses a rotation of the $\mu-\tau$ symmetry and is able to impose a generic
smallest mixing angle, in contrast to a zero-value predicted by the usual
non-rotated form of the $\mu-\tau$ symmetry. We extend this symmetry for the
lepton sector within type-I seesaw scenario, and show it can accommodate the
mixing angles, the mass hierarchies and the lepton asymmetry in the universe.
We then study the effects of perturbing the specific form of the neutrino mass
matrix imposed by the symmetry and compute the resulting mixing and mass
spectrum. We trace back this "low-scale" perturbation to a "high-scale"
perturbation, and find realizations of this latter one arising from exact
symmetries with an enriched matter content.


title: Evolution of Gas Giant Entropy During Formation by Runaway Accretion

abstract:
  We calculate the evolution of gas giant planets during the runaway gas
accretion phase of formation, to understand how the luminosity of young giant
planets depends on the accretion conditions. We construct steady-state envelope
models, and run time-dependent simulations of accreting planets with the
Modules for Experiments in Stellar Astrophysics (MESA) code. We show that the
evolution of the internal entropy depends on the contrast between the internal
adiabat and the entropy of the accreted material, parametrized by the shock
temperature $T_0$ and pressure $P_0$. At low temperatures ($T_0\lesssim
300$--$1000\ {\rm K}$, depending on model parameters), the accreted material
has a lower entropy than the interior. The convection zone extends to the
surface and can drive a large luminosity, leading to rapid cooling and cold
starts. For higher temperatures, the accreted material has a larger entropy
than the interior, giving a radiative zone that stalls cooling. For $T_0\gtrsim
2000\ {\rm K}$, the surface--interior entropy contrast cannot be accommodated
by the radiative envelope, and the accreted matter accumulates with high
entropy, forming a hot start. The final state of the planet depends on the
shock temperature, accretion rate, and starting entropy at the onset of runaway
accretion. Cold starts with $L\lesssim 5\times 10^{-6}\ L_\odot$ require low
accretion rates and starting entropy, and that the temperature of the accreting
material is maintained close to the nebula temperature. If instead the
temperature is near the value required to radiate the accretion luminosity,
$4\pi R^2\sigma T_0^4\sim (GM\dot M/R)$, as suggested by previous work on
radiative shocks in the context of star formation, gas giant planets form in a
hot start with $L\sim 10^{-4}\ L_\odot$.


title:
Origin of Soft Limits from Nonlinear Supersymmetry in Volkov-Akulov
  Theory

abstract:
  We apply the background field technique, recently developed for a general
class of nonlinear symmetries, at tree level, to the Volkov-Akulov theory with
spontaneously broken N=1 supersymmetry. We find that the background field
expansion in terms of the free fields to the lowest order reproduces the
nonlinear supersymmetry transformation rules. The double soft limit of the
background field is, in agreement with the new general identities, defined by
the algebra of the nonlinear symmetries.


title:
Acousto-optic and opto-acoustic modulation in piezo-optomechanical
  circuits

abstract:
  Acoustic wave devices provide a promising chip-scale platform for efficiently
coupling radio frequency (RF) and optical fields. Here, we use an integrated
piezo-optomechanical circuit platform that exploits both the piezoelectric and
photoelastic coupling mechanisms to link 2.4 GHz RF waves to 194 THz (1550 nm)
optical waves, through coupling to propagating and localized 2.4 GHz acoustic
waves. We demonstrate acousto-optic modulation, resonant in both the optical
and mechanical domains, in which waveforms encoded on the RF carrier are mapped
to the optical field. We also show opto-acoustic modulation, in which the
application of optical pulses gates the transmission of propagating acoustic
waves. The time-domain characteristics of this system under both pulsed RF and
pulsed optical excitation are considered in the context of the different
physical pathways involved in driving the acoustic waves, and modeled through
the coupled mode equations of cavity optomechanics.


title: Measuring an electron beam's orbital angular momentum spectrum

abstract:
  Quantum complementarity states that particles, e.g. electrons, can exhibit
wave-like properties such as diffraction and interference upon propagation.
\textit{Electron waves} defined by a helical wavefront are referred to as
twisted electrons~\cite{uchida:10,verbeeck:10,mcmorran:11}. These electrons are
also characterised by a quantized and unbounded magnetic dipole moment parallel
to their propagation direction, as they possess a net charge of
$-|e|$~\cite{bliokh:07}. When interacting with magnetic materials, the
wavefunctions of twisted electrons are inherently
modified~\cite{lloyd:12b,schattschneider:14a,asenjo:14}. Such variations
therefore motivate the need to analyze electron wavefunctions, especially their
wavefronts, in order to obtain information regarding the material's
structure~\cite{harris:15}. Here, we propose, design, and demonstrate the
performance of a device for measuring an electron's azimuthal wavefunction,
i.e. its orbital angular momentum (OAM) content. Our device consists of
nanoscale holograms designed to introduce astigmatism onto the electron
wavefunctions and spatially separate its phase components. We sort pure and
superposition OAM states of electrons ranging within OAM values of $-10$ and
$10$. We employ the device to analyze the OAM spectrum of electrons having been
affected by a micron-scale magnetic dipole, thus establishing that, with a
midfield optical configuration, our sorter can be an instrument for nano-scale
magnetic spectroscopy.


title: Quantum Cascade Lasers: Electrothermal Simulation

abstract:
  Book chapter on multiscale electrothermal simulation of midinfrared quantum
cascade lasers. To appear in Handbook of Optoelectronic Device Modeling and
Simulation, Taylor and Francis Books, 2017. Editor: Joachim Piprek.


title: Electron-phonon interaction in an $N$-atomic 1-D periodic chain

abstract:
  The study of electron-phonon interaction as a prominent inelastic effect is
of great importance. In the present work, we have studied the inelastic effects
due to the first order electron-phonon interactions on electronic properties of
mono-atomic periodic chain, using the exact diagonalization technique. Hence,
only acoustic modes are considered. To avoid the approximate results arising
from Keldysh formalism and on-site electron-phonon interaction assumption, we
have used the Green's function technique together with Fr\"{o}hlich Hamiltonian
for the interaction part. Finally, as an example, we apply our method to the
case of $N=6$ which could be considered as a Benzene-like molecule.


title: A simplicial construction of G-equivariant Floer homology

abstract:
  For G a Lie group acting on a symplectic manifold $(M,\omega)$ preserving a
pair of Lagrangians $L_0$, $L_1$, under certain hypotheses not including
equivariant transversality we construct a G-equivariant Floer cohomology of
$L_0$ and $L_1$.


title:
Analysis of the p-adic q-Volkenborn Integrals: an approach to
  Apostol-type special numbers and polynomials

abstract:
  By applying the p-adic q-Volkenborn Integrals including the bosonic and the
fermionic p-adic integrals on p-adic integers, we define generating functions,
attached to the Dirichlet character, for the generalized Apostol-Bernoulli
numbers and polynomials, the generalized Apostol-Euler numbers and polynomials,
generalized Apostol-Daehee numbers and polynomials, and also generalized
Apostol-Changhee numbers and polynomials. We investigate some properties of
these numbers and polynomials with their generating functions. By using these
generating functions and their functional equation, we give some identities and
relations including the generalized Apostol-Daehee and Apostol-Changhee numbers
and polynomials, the Stirling numbers, the Bernoulli numbers of the second
kind, Frobenious-Euler polynomials, the generalized Bernoulli numbers and the
generalized Euler numbers and the Frobenious-Euler polynomials. By using the
bosonic and the fermionic p-adic integrals, we derive integral represantations
for the generalized Apostol-type Daehee numbers and the generalized
Apostol-type Changhee numbers.


title: Independent sets near the lower bound in bounded degree graphs

abstract:
  By Brook's Theorem, every n-vertex graph of maximum degree at most Delta >= 3
and clique number at most Delta is Delta-colorable, and thus it has an
independent set of size at least n/Delta. We give an approximate
characterization of graphs with independence number close to this bound, and
use it to show that the problem of deciding whether such a graph has an
indepdendent set of size at least n/Delta+k has a kernel of size O(k).


title: The origin and 9:7 MMR dynamics of the Kepler-29 system

abstract:
  We analyse the Transit Timing Variation (TTV) measurements of a~system of two
super-Earths detected as Kepler-29, in order to constrain the planets' masses
and orbital parameters. A dynamical analysis of the best-fitting configurations
constrains the masses to be $\sim 6$ and $\sim 5$ Earth masses for the inner
and the outer planets, respectively. The analysis also reveals that the system
is likely locked in the 9:7~mean motion resonance. However, a variety of
orbital architectures regarding eccentricities and the relative orientation of
orbits is permitted by the observations as well as by stability constraints. We
attempt to find configurations preferred by the planet formation scenarios as
an additional, physical constraint. We show that configurations with low
eccentricities and anti-aligned apsidal lines of the orbits are a natural and
most likely outcome of the convergent migration. However, we show that
librations of the critical angles are not necessary for the Kepler-29 system to
be dynamically resonant, and such configurations may be formed on the way of
migration as well. We argue, on the other hand, that aligned configurations
with $e \gtrsim 0.03$ may be not consistent with the migration scenario.


title: Rotating Solutions in Critical Lovelock Gravities

abstract:
  For appropriate choices of the coupling constants, the equations of motion of
Lovelock gravities up to order n in the Riemann tensor can be factorized such
that the theories admits a single (A)dS vacuum. In this paper we construct two
classes of exact rotating metrics in such critical Lovelock gravities of order
n in d=2n+1 dimensions. In one class, the n angular momenta in the n orthogonal
spatial 2-planes are equal, and hence the metric is of cohomogeneity one. We
construct these metrics in a Kerr-Schild form, but they can then be recast in
terms of Boyer-Lindquist coordinates. The other class involves metrics with
only a single non-vanishing angular momentum. Again we construct them in a
Kerr-Schild form, but in this case it does not seem to be possible to recast
them in Boyer-Lindquist form. Both classes of solutions have naked curvature
singularities, arising because of the over rotation of the configurations.


title:
Discrepancies between Asymptotic and Exact Spectral Gap Analyses of
  Quantum Adiabatic Barrier Tunneling

abstract:
  We study the asymptotic behavior of the spectral gap of simple barrier
tunneling problems, which are related to using quantum annealing to find the
global optimum of cost functions defined over n bits. Specifically we look at
the problem of having an n qubit system tunnel through a barrier of width and
height proportional to n^a. We show that with these quantum annealing problems,
the asymptotic, $n\to\infty$, behavior of the spectral gap does not accurately
describe the behavior of the gap at finite n until extremely large values of n
(n>10^{12}). We prove that this deficiency of the asymptotic expression is a
feature of simple one-dimensional tunneling problems themselves, casting doubt
on whether asymptotic analysis is an appropriate tool for studying tunneling
problems in quantum annealing for reasonably sized systems.


title:
Topological superfluid in a Fermi-Bose mixture with a high critical
  temperature

abstract:
  We show that a two-dimensional (2D) spin-polarised Fermi gas immersed in a 3D
Bose-Einstein condensate (BEC) constitutes a very promising system to realise a
$p_x+ip_y$ superfluid. The fermions attract each other via an induced
interaction mediated by the bosons, and the resulting pairing is analysed with
retardation effects fully taken into account. This is further combined with
Berezinskii-Kosterlitz-Thouless (BKT) theory to obtain reliable results for the
superfluid critical temperature. We show that both the strength and the range
of the induced interaction can be tuned experimentally, which can be used to
make the critical temperature approach the maximum value allowed by general BKT
theory. Moreover, this is achieved while keeping the Fermi-Bose interaction
weak so that three-body losses are small. Our results show that realising a
topological superfluid with atomic Fermi-Bose mixtures is within experimental
reach.


title:
All-optical spin switching: A new frontier in femtomagnetism -- A short
  review and a simple theory

abstract:
  Using an ultrafast laser pulse to manipulate the spin degree of freedom has
broad technological appeal. It allows one to control the spin dynamics on a
femtosecond time scale. The discipline, commonly called femtomagnetism, started
with the pioneering experiment by Beaurepaire and coworkers in 1996, who showed
subpicosecond demagnetization occurs in magnetic Ni thin films. This finding
has motivated extensive research worldwide. All-optical helicity-dependent spin
switching (AOS) represents a new frontier in femtomagnetism, where a single
ultrafast laser pulse can permanently switch spin without any assistance from a
magnetic field. This review summarizes some of the crucial aspects of this new
discipline: key experimental findings, leading mechanisms, controversial
issues, and possible future directions. The emphasis is on our latest
investigation. We first develop the all-optical spin switching rule that
determines how the switchability depends on the light helicity. This rule
allows one to understand microscopically how the spin is reversed and why the
circularly polarized light appears more powerful than the linearly polarized
light. Then we invoke our latest spin-orbit coupled harmonic oscillator model
to simulate single spin reversal. We consider both cw excitation and pulsed
laser excitation. The results are in a good agreement with the experimental
result. We then extend the code to include the exchange interaction among
different spin sites. We show where the "inverse Faraday field" comes from and
how the laser affects the spin reversal nonlinearly. Our hope is that this
review will motivate new experimental and theoretical investigations and
discussions.


title:
Probing the QCD phase diagram with dileptons - a study using
  coarse-grained transport dynamics

abstract:
  Dilepton production in heavy-ion collisions at various energies is studied
using coarse-grained transport simulations. Microscopic output from the
Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model is hereby put on a
grid of space-time cells which allows to extract the local temperature and
chemical potential in each cell via an equation of state. The dilepton emission
is then calculated applying in-medium spectral functions from hadronic
many-body theory and partonic production rates based on lattice calculations.
The comparison of the resulting spectra with experimental data shows that the
dilepton excess beyond the decay contributions from a hadronic cocktail
reflects the trajectory of the fireball in the $T-\mu_{\mathrm{B}}$ plane of
the QCD phase diagram.


title:
A central limit theorem for costs in Bulinskaya's inventory management
  problem when deliveries face delays

abstract:
  It is common in inventory theory to consider policies that minimize the
expected cost of ordering and holding goods or materials. Nevertheless, the
realized cost is a random variable, and, as the Saint Petersburg Paradox
reminds us, the expected value does not always capture the full economic
reality of a decision problem. Here we take the classic inventory model of
Bulinskaya (1964), and, by proving an appropriate central limit theorem, we
show in a reasonably rich (and practical) sense that the mean-optimal policies
are economically appropriate. The motivation and the tools are applicable to a
large class of Markov decision problems.


title: Minimal hypersurfaces and bordism of positive scalar curvature metrics

abstract:
  Let $(Y,g)$ be a compact Riemannian manifold of positive scalar curvature
(psc). It is well-known, due to Schoen-Yau, that any closed stable minimal
hypersurface of $Y$ also admits a psc-metric. We establish an analogous result
for stable minimal hypersurfaces with free boundary. Furthermore, we combine
this result with tools from geometric measure theory and conformal geometry to
study psc-bordism. For instance, assume $(Y_0,g_0)$ and $(Y_1,g_1)$ are closed
psc-manifolds equipped with stable minimal hypersurfaces $X_0 \subset Y_0$ and
$X_1\subset Y_1$. Under natural topological conditions, we show that a
psc-bordism $(Z,\bar g) : (Y_0,g_0)\rightsquigarrow (Y_1,g_1)$ gives rise to a
psc-bordism between $X_0$ and $X_1$ equipped with the psc-metrics given by the
Schoen-Yau construction.


title:
Recurrent Convolutional Networks for Pulmonary Nodule Detection in CT
  Imaging

abstract:
  Computed tomography (CT) generates a stack of cross-sectional images covering
a region of the body. The visual assessment of these images for the
identification of potential abnormalities is a challenging and time consuming
task due to the large amount of information that needs to be processed. In this
article we propose a deep artificial neural network architecture, ReCTnet, for
the fully-automated detection of pulmonary nodules in CT scans. The
architecture learns to distinguish nodules and normal structures at the pixel
level and generates three-dimensional probability maps highlighting areas that
are likely to harbour the objects of interest. Convolutional and recurrent
layers are combined to learn expressive image representations exploiting the
spatial dependencies across axial slices. We demonstrate that leveraging
intra-slice dependencies substantially increases the sensitivity to detect
pulmonary nodules without inflating the false positive rate. On the publicly
available LIDC/IDRI dataset consisting of 1,018 annotated CT scans, ReCTnet
reaches a detection sensitivity of 90.5% with an average of 4.5 false positives
per scan. Comparisons with a competing multi-channel convolutional neural
network for multi-slice segmentation and other published methodologies using
the same dataset provide evidence that ReCTnet offers significant performance
gains.


title:
Rotationally-invariant mapping of scalar and orientational metrics of
  neuronal microstructure with diffusion MRI

abstract:
  We develop a general analytical and numerical framework for estimating intra-
and extra-neurite water fractions and diffusion coefficients, as well as
neurite orientational dispersion, in each imaging voxel. By employing a set of
rotational invariants and their expansion in the powers of diffusion weighting,
we analytically uncover the nontrivial topology of the parameter estimation
landscape, showing that multiple branches of parameters describe the
measurement almost equally well, with only one of them corresponding to the
biophysical reality. A comprehensive acquisition shows that the branch choice
varies across the brain. Our framework reveals hidden degeneracies in MRI
parameter estimation for neuronal tissue, provides microstructural and
orientational maps in the whole brain without constraints or priors, and
connects modern biophysical modeling with clinical MRI.


title:
Universal power-law scaling of water diffusion in human brain defines
  what we see with MRI

abstract:
  Development of successful therapies for neurological disorders depends on our
ability to diagnose and monitor the progression of underlying pathologies at
the cellular level. Physics and physiology limit the resolution of human MRI to
millimeters, three orders of magnitude coarser than the cell dimensions of
microns. A promising way to access cellular structure is provided by
diffusion-weighted MRI (dMRI), a modality which exploits the sensitivity of the
MRI signal to micron-level Brownian motion of water molecules strongly hindered
by cell walls. By analyzing diffusion of water molecules in human subjects,
here we demonstrate that biophysical modeling has the potential to break the
intrinsic MRI resolution limits. The observation of a universal power-law
scaling of the dMRI signal identifies the contribution from water specifically
confined inside narrow impermeable axons, validating the overarching assumption
behind models of diffusion in neuronal tissue. This scaling behavior
establishes dMRI as an in vivo instrument able to quantify intra-axonal
properties orders of magnitude below the nominal MRI resolution, spurring our
understanding of brain anatomy and function.


title:
Photo-thermal Self-oscillations in Cavity-Coupled Carbon Nanotube
  pn-Devices

abstract:
  We observe photothermal self-oscillations in individual, suspended,
quasi-metallic carbon nanotube (CNT) pn devices irradiated with focused CW
633nm light. Here, the bottom of the trench forms an optical cavity with an
anti-node at lambda/4. Oscillations arise from the optical heating of the
nanotube, which causes thermal contraction of the nanotube (negative thermal
expansion coefficient). This, in turn, moves the CNT out of the anti-node
(maximum field intensity), where the nanotube cools to a lower temperature. It
then expands and returns to the maximum field intensity anti-node where it is
optically heated once again. The oscillations are observed through a change of
the tunneling current in the CNT device. A pn-junction, established by two
electrostatic gates positioned beneath the nanotube, results in Zener
tunneling, which depends strongly on temperature. A Zener tunneling model with
oscillating temperature shows good agreement with our measured I-V curves,
providing further evidence that these oscillations are photothermal in nature.


title: Exchangeable Trait Allocations

abstract:
  Trait allocations are a class of combinatorial structures in which data may
belong to multiple groups and may have different levels of belonging in each
group. Often the data are also exchangeable, i.e., their joint distribution is
invariant to reordering. In clustering---a special case of trait
allocation---exchangeability implies the existence of both a de Finetti
representation and an exchangeable partition probability function (EPPF),
distributional representations useful for computational and theoretical
purposes. In this work, we develop the analogous de Finetti representation and
exchangeable trait probability function (ETPF) for trait allocations, along
with a characterization of all trait allocations with an ETPF. Unlike previous
feature allocation characterizations, our proofs fully capture
single-occurrence "dust" groups. We further introduce a novel constrained
version of the ETPF that we use to establish an intuitive connection between
the probability functions for clustering, feature allocations, and trait
allocations. As an application of our general theory, we characterize the
distribution of all edge-exchangeable graphs, a class of recently-developed
models that captures realistic sparse graph sequences.


title:
Evidence for the Secondary Emission as the Origin of Hard Spectra in TeV
  Blazars

abstract:
  We develop a model for a possible origin of hard very high energy spectra
from a distant blazar. In the model, both the primary photons produced in the
source and secondary photons produced outside the source contribute to the
observed high energy $\gamma$-rays emission. That is, the primary photons are
produced in the source through the synchrotron self-Compton (SSC) process, and
the secondary photons are produced outside the source through high energy
protons interaction with the background photons along the line of sight. We
apply the model to a characteristic case was the very high energy (VHE)
$\gamma$-ray emissions in distant blazar 1ES 1101-232. Assuming a suitable
electron and proton spectra, we obtain excellent fits to observed spectra of
distant blazar 1ES 1101-232. This indicated that the surprisingly low
attenuation of high energy $\gamma$-rays, especially for the shape of the very
high energy $\gamma$-rays tail of the observed spectra, can be explained by
secondary $\gamma$-rays produced in interactions of cosmic-ray protons with
background photons in the intergalactic space.


title: Which semifields are exact?

abstract:
  Every (left) linear function on a subspace of a finite-dimensional vector
space over a (skew) field can be extended to a (left) linear function on the
whole space. This paper explores the extent to what this basic fact of linear
algebra is applicable to more general structures. Semifields with a similar
property imposed on linear functions are called (left) exact, and we present a
complete description of such semifields. Namely, we show that a semifield $S$
is left exact if and only if $S$ is either a skew field or an idempotent
semiring. In particular, our result is new even for the tropical semiring and
gives a solution to the problem posed by Wilding. Also, we point out several
problems that require further investigation.


title: High-contrast self-imaging with ordered optical elements

abstract:
  Creating arbitrary light patterns finds applications in various domains
including lithography, beam shaping, metrology, sensing and imaging. We study
the formation of high-contrast light patterns that are obtained by transmission
through an ordered optical element based on self-imaging.By applying the
phase-space method, we explain phenomena such as the Talbot and the angular
Talbot effects. We show that the image contrast is maximum when the source is
either a plane wave or a point source, and it has a minimum for a source with
finite spatial extent. We compare these regimes and address some of their
fundamental differences. Specifically, we prove that increasing the source
divergence reduces the contrast for the plane wave illumination but increases
it for the point source. Also, we show that to achieve high contrast with a
point source, tuning the source size and its distance to the element is
crucial.We furthermore indicate and explore the possibility of realizing highly
complex light patterns by using a periodic transmission element. These patterns
can have more spots in the far field than the number of diffraction orders of
the periodic element. We predict that the ultimate image contrast is smaller
for a point source compared to a plane wave. Our simulations confirm that the
smallest achievable spot size in the image is imposed by diffraction regardless
of the imaging regime. Our research can be applied to similar domains e.g.
quantum systems.


title: Fractional Laplacians and extension problems: the higher rank case

abstract:
  The aim of this paper is two-fold: first, we look at the fractional Laplacian
and the conformal fractional Laplacian from the general framework of
representation theory on symmetric spaces and, second, we construct new
boundary operators with good conformal properties that generalize the
fractional Laplacian using an extension problem in which the boundary is of
codimension two.


title:
Fusing Similarity Models with Markov Chains for Sparse Sequential
  Recommendation

abstract:
  Predicting personalized sequential behavior is a key task for recommender
systems. In order to predict user actions such as the next product to purchase,
movie to watch, or place to visit, it is essential to take into account both
long-term user preferences and sequential patterns (i.e., short-term dynamics).
Matrix Factorization and Markov Chain methods have emerged as two separate but
powerful paradigms for modeling the two respectively. Combining these ideas has
led to unified methods that accommodate long- and short-term dynamics
simultaneously by modeling pairwise user-item and item-item interactions.
  In spite of the success of such methods for tackling dense data, they are
challenged by sparsity issues, which are prevalent in real-world datasets. In
recent years, similarity-based methods have been proposed for
(sequentially-unaware) item recommendation with promising results on sparse
datasets. In this paper, we propose to fuse such methods with Markov Chains to
make personalized sequential recommendations. We evaluate our method, Fossil,
on a variety of large, real-world datasets. We show quantitatively that Fossil
outperforms alternative algorithms, especially on sparse datasets, and
qualitatively that it captures personalized dynamics and is able to make
meaningful recommendations.


title: On $D_\ell$-extensions of odd prime degree $\ell$

abstract:
  Generalizing the work of A. Morra and the authors, we give explicit formulas
for the Dirichlet series generating function of $D_{\ell}$-extensions of odd
prime degree $\ell$ with given quadratic resolvent. Over the course of our
proof, we explain connections between our formulas and the Ankeny-Artin-Chowla
conjecture, the Ohno-Nakagawa relation for binary cubic forms, and other
topics. We also obtain improved upper bounds for the number of such extensions
(over Q) of bounded discriminant.


title:
MPI-FAUN: An MPI-Based Framework for Alternating-Updating Nonnegative
  Matrix Factorization

abstract:
  Non-negative matrix factorization (NMF) is the problem of determining two
non-negative low rank factors $W$ and $H$, for the given input matrix $A$, such
that $A \approx W H$. NMF is a useful tool for many applications in different
domains such as topic modeling in text mining, background separation in video
analysis, and community detection in social networks. Despite its popularity in
the data mining community, there is a lack of efficient parallel algorithms to
solve the problem for big data sets.
  The main contribution of this work is a new, high-performance parallel
computational framework for a broad class of NMF algorithms that iteratively
solves alternating non-negative least squares (NLS) subproblems for $W$ and
$H$. It maintains the data and factor matrices in memory (distributed across
processors), uses MPI for interprocessor communication, and, in the dense case,
provably minimizes communication costs (under mild assumptions). The framework
is flexible and able to leverage a variety of NMF and NLS algorithms, including
Multiplicative Update, Hierarchical Alternating Least Squares, and Block
Principal Pivoting. Our implementation allows us to benchmark and compare
different algorithms on massive dense and sparse data matrices of size that
spans for few hundreds of millions to billions. We demonstrate the scalability
of our algorithm and compare it with baseline implementations, showing
significant performance improvements. The code and the datasets used for
conducting the experiments are available online.


title:
Ultrafast Polaron Dynamics in Layered and Perovskite Manganites: 2D and
  3D Polarons

abstract:
  We have studied the sub-picosecond quasiparticle dynamics in the perovskite
manganite La0.7Ca0.3MnO3 and the layered manganite La1.4Sr1.6Mn2O7 using
ultrafast optical spectroscopy. We found that for T > TC, initial relaxation
proceeds on the time scale of several hundred femtoseconds and corresponds to
the redressing of a photoexcited electron to its polaronic ground state. The
temperature and dimensionality dependence of this polaron redressing time
provides insight into the relationship between polaronic motion and spin
dynamics on a sub-picosecond time scale. We also observe a crossover to a more
conventional electron-phonon relaxation in the ferromagnetic metallic phase
below Tc.


title:
Similarity Mapping with Enhanced Siamese Network for Multi-Object
  Tracking

abstract:
  Multi-object tracking has recently become an important area of computer
vision, especially for Advanced Driver Assistance Systems (ADAS). Despite
growing attention, achieving high performance tracking is still challenging,
with state-of-the- art systems resulting in high complexity with a large number
of hyper parameters. In this paper, we focus on reducing overall system
complexity and the number hyper parameters that need to be tuned to a specific
environment. We introduce a novel tracking system based on similarity mapping
by Enhanced Siamese Neural Network (ESNN), which accounts for both appearance
and geometric information, and is trainable end-to-end. Our system achieves
competitive performance in both speed and accuracy on MOT16 challenge, compared
to known state-of-the-art methods.


title: Your Computer is Leaking

abstract:
  This presentation focuses on differences between quantum computing and
quantum cryptography. Both are discussed related to classical computer systems
in terms of vulnerability. Research concerning quantum cryptography is analyzed
in terms of work done by the University of Cambridge in partnership with a
division of Toshiba, and also attacks demonstrated by Swedish researchers
against QKD of energy-time entangled systems. Quantum computing is covered in
terms of classical cryptography related to weaknesses presented by Shor's
algorithm. Previous classical vulnerabilities also discussed were conducted by
Israeli researchers as a side-channel attack using parabolic curve microphones,
which has since been patched.


title:
Proposal for a Leaky-Integrate-Fire Spiking Neuron based on
  Magneto-Electric Switching of Ferro-magnets

abstract:
  The efficiency of the human brain in performing classification tasks has
attracted considerable research interest in brain-inspired neuromorphic
computing. Hardware implementations of a neuromorphic system aims to mimic the
computations in the brain through interconnection of neurons and synaptic
weights. A leaky-integrate-fire (LIF) spiking model is widely used to emulate
the dynamics of neuronal action potentials. In this work, we propose a spin
based LIF spiking neuron using the magneto-electric (ME) switching of
ferro-magnets. The voltage across the ME oxide exhibits a typical
leaky-integrate behavior, which in turn switches an underlying ferro-magnet.
Due to the effect of thermal noise, the ferro-magnet exhibits probabilistic
switching dynamics, which is reminiscent of the stochasticity exhibited by
biological neurons. The energy-efficiency of the ME switching mechanism coupled
with the intrinsic non-volatility of ferro-magnets result in lower energy
consumption, when compared to a CMOS LIF neuron. A device to system-level
simulation framework has been developed to investigate the feasibility of the
proposed LIF neuron for a hand-written digit recognition problem


title: Three-loop vacuum integrals with arbitrary masses

abstract:
  Three-loop vacuum integrals are an important building block for the
calculation of a wide range of three-loop corrections. Until now, only results
for integrals with one and two independent mass scales are known, but in the
electroweak Standard Model and many extensions thereof, one often encounters
more mass scales of comparable magnitude. For this reason, a numerical approach
for the evaluation of three-loop vacuum integrals with arbitrary mass pattern
is proposed here. Concretely, one can identify a basic set of three master
integral topologies. With the help of dispersion relations, each of these can
be transformed into one-dimensional or, for the most complicated case,
two-dimensional integrals in terms of elementary functions, which are suitable
for efficient numerical integration.


title: The gap of Fredkin quantum spin chain is polynomially small

abstract:
  We prove a new result on the spectral gap and mixing time of a Markov chain
with Glauber dynamics on the space of Dyck paths (i.e., Catalan paths) and
their generalization, which we call colored Dyck paths. The proof uses the
comparison theorem of Diaconis and Saloff-Coste and our previous results.
  Let $2n$ be the number of spins. We prove that the gap of the Fredkin quantum
spin chain Hamiltonian [6, 20], is $\Theta(n^{-c})$ with $c\ge2$. Our results
on the spectral gap of the Markov chain are used to prove a lower bound of
$O(n^{-15/2})$ on the energy of first excited state above the ground state of
the Fredkin quantum spin chain. We prove an upper bound of $O(n^{-2})$ using
the universality of Brownian motion and convergence of Dyck random walks to
Brownian excursions. Lastly, the 'unbalanced' ground state energies are proved
to be polynomially small in $n$ by mapping the Hamiltonian to an effective
hopping Hamiltonian with next nearest neighbor interactions and analytically
solving its ground state.

categories: quant-ph cond-mat.stat-mech cond-mat.str-el math-ph math.CO math.MP


title:
Exploiting Energy Accumulation Against Co-channel Interference in
  Wireless Energy Harvesting MIMO Relaying

abstract:
  This paper investigates a three-node multiple-input multiple-output relay
system suffering from co-channel interference (CCI) at the multi-antenna relay.
Contrary to the conventional relay networks, we consider the scenario that the
relay is an energy harvesting (EH) node and has no embedded energy supply. But
it is equipped with a rechargeable battery such that it can harvest and
accumulate the harvested energy from RF signals sent by the source and
co-channel interferers to support its operation. Leveraging the inherent
feature of the considered system, we develop a novel accumulate-then-forward
(ATF) protocol to eliminate the harmful effect of CCI. In the proposed ATF
scheme, at the beginning of each transmission block, the relay can choose
either EH operation to harvest energy from source and CCI or information
decoding (ID) operation to decode and forward source's information while
suffering from CCI. Specifically, ID operation is activated only when the
accumulated energy at the relay can support an outage-free transmission in the
second hop. Otherwise, EH operation is invoked at the relay to harvest and
accumulate energy. By modeling the finite-capacity battery of relay as a
finite-state Markov Chain (MC), we derive a closed-form expression for the
system throughput of the proposed ATF scheme over mixed Nakagami-m and Rayleigh
fading channels. Numerical results validate our theoretical analysis, and show
that the proposed ATF scheme with energy accumulation significantly outperforms
the existing one without energy accumulation.


title: Universum Learning for Multiclass SVM

abstract:
  We introduce Universum learning for multiclass problems and propose a novel
formulation for multiclass universum SVM (MU-SVM). We also propose a span bound
for MU-SVM that can be used for model selection thereby avoiding resampling.
Empirical results demonstrate the effectiveness of MU-SVM and the proposed
bound.


title: Microstructural Characteristics of Reaction-Bonded B4C/SiC Composite

abstract:
  A detailed microstructural investigation was performed to understand
structural characteristics of a reaction-bonded B$_4$C/SiC ceramic composite.
The state-of-the-art focused ion beam & scanning electron microscopy (FIB/SEM)
and transmission electron microscopy (TEM) revealed that the as-fabricated
product consisted of core-rim structures with {\alpha}-SiC and $B_4$C cores
surrounded by \beta-SiC and $B_4$C, respectively. In addition, plate-like
\beta-SiC was detected within the $B_4$C rim. A phase formation mechanism was
proposed and the analytical elucidation is anticipated to shed light on
potential fabrication optimization and the property improvement of ceramic
composites.


title:
Cartan Covers and Doubling Bernstein Type Inequalities on Analytic
  Subsets of $\mathbb{C}^2$

abstract:
  We prove a version of the doubling Bernstein inequalities for the trace of an
analytic function of two variables on an analytic subset of $\mathbb{C}^2$. The
estimate applies to the whole analytic set in question including its singular
points. The proof relies on a version of the Cartan estimate for maps in
$\mathbb{C}^2$ which we establish in this work.


title: Reevaluation of thermonuclear reaction rate of 50Fe(p,gamma)51Co

abstract:
  The thermonuclear rate of the 50Fe(p,gamma)51Co reaction in the Type I X-ray
bursts (XRBs) temperature range has been reevaluated based on a recent precise
mass measurement at CSRe lanzhou, where the proton separation energy
Sp=142+/-77 keV has been determined firstly for the 51Co nucleus. Comparing to
the previous theoretical predictions, the experimental Sp value has much
smaller uncertainty. Based on the nuclear shell model and mirror nuclear
structure information, we have calculated two sets of thermonuclear rates for
the 50Fe(p,gamma)51Co reaction by utilizing the experimental Sp value. It shows
that the statistical-model calculations are not ideally applicable for this
reaction primarily because of the low density of low-lying excited states in
51Co. In this work, we recommend that a set of new reaction rate based on the
mirror structure of 51Cr should be incorporated in the future astrophysical
network calculations.


title: Quantum simulation of driven para-Bose oscillators

abstract:
  Quantum mechanics allows paraparticles with mixed Bose-Fermi statistics that
have not been experimentally confirmed. We propose a trapped-ion scheme whose
effective dynamics are equivalent to a driven para-Bose oscillator of even
order. Our mapping suggest highly entangled vibrational and internal ion states
as the laboratory equivalent of quantum simulated parabosons. Furthermore, we
show the generation and reconstruction of coherent oscillations and para-Bose
analogs of Gilmore-Perelomov coherent states from population inversion
measurements in the laboratory frame. Our proposal, apart from demonstrating an
analog quantum simulator of para-Bose oscillators, provides a quantum state
engineering tool that foreshadows the potential use of paraparticle dynamics in
the design of quantum information systems.


title: On private information retrieval array codes

abstract:
  Given a database, the private information retrieval (PIR) protocol allows a
user to make queries to several servers and retrieve a certain item of the
database via the feedbacks, without revealing the privacy of the specific item
to any single server. Classical models of PIR protocols require that each
server stores a whole copy of the database. Recently new PIR models are
proposed with coding techniques arising from distributed storage system. In
these new models each server only stores a fraction $1/s$ of the whole
database, where $s>1$ is a given rational number. PIR array codes are recently
proposed by Fazeli, Vardy and Yaakobi to characterize the new models. Consider
a PIR array code with $m$ servers and the $k$-PIR property (which indicates
that these $m$ servers may emulate any efficient $k$-PIR protocol). The central
problem is to design PIR array codes with optimal rate $k/m$. Our contribution
to this problem is three-fold. First, for the case $1<s\le 2$, although PIR
array codes with optimal rate have been constructed recently by Blackburn and
Etzion, the number of servers in their construction is impractically large. We
determine the minimum number of servers admitting the existence of a PIR array
code with optimal rate for a certain range of parameters. Second, for the case
$s>2$, we derive a new upper bound on the rate of a PIR array code. Finally,
for the case $s>2$, we analyze a new construction by Blackburn and Etzion and
show that its rate is better than all the other existing constructions.


title: Finite multiple zeta values associated with 2-colored rooted trees

abstract:
  We define finite multiple zeta values (FMZVs) associated with some
combinatorial objects, which we call 2-colored rooted trees, and prove that
FMZVs associated with 2-colored rooted trees satisfying certain mild
assumptions can be written explicitly as $\mathbb{Z}$-linear combinations of
the usual FMZVs. Our result can be regarded as a generalization of Kamano's
recent work on finite Mordell-Tornheim multiple zeta values. As an application,
we will give a new proof of the shuffle relation of FMZVs, which was first
proved by Kaneko and Zagier.


title:
A possible formation channel for blue hook stars in globular cluster -
  II. Effects of metallicity, mass ratio, tidal enhancement efficiency and
  helium abundance

abstract:
  Employing tidally enhanced stellar wind, we studied in binaries the effects
of metallicity, mass ratio of primary to secondary, tidal enhancement
efficiency and helium abundance on the formation of blue hook (BHk) stars in
globular clusters (GCs). A total of 28 sets of binary models combined with
different input parameters are studied. For each set of binary model, we
presented a range of initial orbital periods that is needed to produce BHk
stars in binaries. All the binary models could produce BHk stars within
different range of initial orbital periods. We also compared our results with
the observation in the Teff-logg diagram of GC NGC 2808 and {\omega} Cen. Most
of the BHk stars in these two GCs locate well in the region predicted by our
theoretical models, especially when C/N-enhanced model atmospheres are
considered. We found that mass ratio of primary to secondary and tidal
enhancement efficiency have little effects on the formation of BHk stars in
binaries, while metallicity and helium abundance would play important roles,
especially for helium abundance. Specifically, with helium abundance increasing
in binary models, the space range of initial orbital periods needed to produce
BHk stars becomes obviously wider, regardless of other input parameters
adopted. Our results were discussed with recent observations and other
theoretical models.


title: Inference of epidemiological parameters from household stratified data

abstract:
  We consider a continuous-time Markov chain model of SIR disease dynamics with
two levels of mixing. For this so-called stochastic households model, we
provide two methods for inferring the model parameters---governing
within-household transmission, recovery, and between-household
transmission---from data of the day upon which each individual became
infectious and the household in which each infection occurred, as would be
available from first few hundred studies. Each method is a form of Bayesian
Markov Chain Monte Carlo that allows us to calculate a joint posterior
distribution for all parameters and hence the household reproduction number and
the early growth rate of the epidemic. The first method performs exact Bayesian
inference using a standard data-augmentation approach; the second performs
approximate Bayesian inference based on a likelihood approximation derived from
branching processes. These methods are compared for computational efficiency
and posteriors from each are compared. The branching process is shown to be an
excellent approximation and remains computationally efficient as the amount of
data is increased.


title:
Empirical Evaluation of RNN Architectures on Sentence Classification
  Task

abstract:
  Recurrent Neural Networks have achieved state-of-the-art results for many
problems in NLP and two most popular RNN architectures are Tail Model and
Pooling Model. In this paper, a hybrid architecture is proposed and we present
the first empirical study using LSTMs to compare performance of the three RNN
structures on sentence classification task. Experimental results show that the
Max Pooling Model or Hybrid Max Pooling Model achieves the best performance on
most datasets, while Tail Model does not outperform other models.


title:
DPHMM: Customizable Data Release with Differential Privacy via Hidden
  Markov Model

abstract:
  Hidden Markov model (HMM) has been well studied and extensively used. In this
paper, we present DPHMM ({Differentially Private Hidden Markov Model}), an HMM
embedded with a private data release mechanism, in which the privacy of the
data is protected through a graph. Specifically, we treat every state in Markov
model as a node, and use a graph to represent the privacy policy, in which
"indistinguishability" between states is denoted by edges between nodes. Due to
the temporal correlations in Markov model, we show that the graph may be
reduced to a subgraph with disconnected nodes, which become unprotected and
might be exposed. To detect such privacy risk, we define sensitivity hull and
degree of protection based on the graph to capture the condition of information
exposure. Then to tackle the detected exposure, we study how to build an
optimal graph based on the existing graph. We also implement and evaluate the
DPHMM on real-world datasets, showing that privacy and utility can be better
tuned with customized policy graph.


title:
Zero-sum stochastic differential games without the Isaacs condition:
  random rules of priority and intermediate Hamiltonians

abstract:
  For a zero-sum stochastic game which does not satisfy the Isaacs condition,
we provide a value function representation for an Isaacs-type equation whose
Hamiltonian lies in between the lower and upper Hamiltonians, as a convex
combination of the two. For the general case (i.e. the convex combination is
time and state dependent) our representation amounts to a random change of the
rules of the game, to allow each player at any moment to see the other player's
action or not, according to a coin toss with probabilities of heads and tails
given by the convex combination appearing in the PDE. If the combination is
state independent, then the rules can be set all in advance, in a deterministic
way. This means that tossing the coin along the game, or tossing it repeatedly
right at the beginning leads to the same value. The representations are
asymptotic, over time discretizations. Space discretization is possible as
well, leading to similar results.


title: Improving Grid Based Bayesian Methods

abstract:
  In some cases, computational benefit can be gained by exploring the hyper
parameter space using a deterministic set of grid points instead of a Markov
chain. We view this as a numerical integration problem and make three unique
contributions. First, we explore the space using low discrepancy point sets
instead of a grid. This allows for accurate estimation of marginals of any
shape at a much lower computational cost than a grid based approach and thus
makes it possible to extend the computational benefit to a hyper parameter
space with higher dimensionality (10 or more). Second, we propose a new, quick
and easy method to estimate the marginal using a least squares polynomial and
prove the conditions under which this polynomial will converge to the true
marginal. Our results are valid for a wide range of point sets including grids,
random points and low discrepancy points. Third, we show that further accuracy
and efficiency can be gained by taking into consideration the functional
decomposition of the integrand and illustrate how this can be done using
anchored f-ANOVA on weighted spaces.


title: Conservation of Charge and Conservation of Current

abstract:
  Conservation of current and conservation of charge are nearly the same thing:
when enough is known about charge movement, conservation of current can be
derived from conservation of charge, in ideal dielectrics, for example.
Conservation of current is enforced implicitly in ideal dielectrics by theories
that conserve charge. But charge movement in real materials like semiconductors
or ionic solutions is never ideal. We present an apparently universal
derivation of conservation of current and advocate using that conservation law
explicitly as a distinct part of theories and calculations of charge movement
in complex fluids and environments. Classical models using ordinary
differential equations rarely satisfy conservation of current, including the
chemical kinetic models implementing the law of mass action and Markov models.
These models must be amended if they are to conserve current. Strict
enforcement of conservation of current is likely to aid numerical analysis by
preventing artifactual accumulation of charge.


title:
Global conservative solution for the periodic $\mu$-Camassa-Holm
  equation

abstract:
  In this paper we mainly investigate the periodic $\mu$-Camassa-Holm equation.
We show the existence of global conservative solutions to the Cauchy problem of
the periodic $\mu$-Camassa-Holm equation. The result is obtained by introducing
a coordinate transformation into Lagrangian coordinates. Our solutions depend
continuously on the initial data and has a semigroup property.