title: First Season MWA EoR Power Spectrum Results at Redshift 7

abstract:
  The Murchison Widefield Array (MWA) has collected hundreds of hours of Epoch
of Reionization (EoR) data and now faces the challenge of overcoming foreground
and systematic contamination to reduce the data to a cosmological measurement.
We introduce several novel analysis techniques such as cable reflection
calibration, hyper-resolution gridding kernels, diffuse foreground model
subtraction, and quality control methods. Each change to the analysis pipeline
is tested against a two dimensional power spectrum figure of merit to
demonstrate improvement. We incorporate the new techniques into a deep
integration of 32 hours of MWA data. This data set is used to place a
systematic-limited upper limit on the cosmological power spectrum of $\Delta^2
\leq 2.7 \times 10^4$ mK$^2$ at $k=0.27$ h~Mpc$^{-1}$ and $z=7.1$, consistent
with other published limits, and a modest improvement (factor of 1.4) over
previous MWA results. From this deep analysis we have identified a list of
improvements to be made to our EoR data analysis strategies. These improvements
will be implemented in the future and detailed in upcoming publications.


title: Equivalent Equations of Motion for Gravity and Entropy

abstract:
  We demonstrate an equivalence between the wave equation obeyed by the
entanglement entropy of CFT subregions and the linearized bulk Einstein
equation in Anti-de Sitter pace. In doing so, we make use of the formalism of
kinematic space [arXiv:1505.05515] and fields on this space, introduced in
[arXiv:1604.03110]. We show that the gravitational dynamics are equivalent to a
gauge invariant wave-equation on kinematic space and that this equation arises
in natural correspondence to the conformal Casimir equation in the CFT.


title: 880 $\mu$m SMA polarization observations of the quasar 3C 286

abstract:
  For decades, the bright radio quasar 3C 286 has been widely recognized as one
of the most reliable polarization calibrators at centimeter wavelengths because
of its unchanging polarization position angle and high polarization percentage.
However, it has become clear in recent years that the polarization position
angle of 3C 286 changes with increasing frequency, increasing from
~33$^{\circ}$ at $\lambda \gtrsim 3$ cm to ~38$^{\circ}$ at $\lambda \approx 1$
mm. With the advent of high-sensitivity polarization observations by current
and future (sub)millimeter telescopes, knowledge of the position angle of 3C
286 at higher frequencies is critical for calibration. We report the first
polarization observations of 3C 286 at submillimeter wavelengths, taken at 880
$\mu$m (340 GHz) with the Submillimeter Array. We find a polarization position
angle and percentage of $37.4 \pm 1.5^{\circ}$ and $15.7 \pm 0.8$%,
respectively, consistent with previous measurements at 1 mm.


title: An Index for Ray Operators in 5d $E_n$ SCFTs

abstract:
  We construct an index for BPS operators supported on a ray in five
dimensional superconformal field theories with exceptional global symmetries.
We compute the $E_n$ representations (for $n=2,\dots,7$) of operators of low
spin, thus verifying that while the expression for the index is only
SO$(2n-2)\times$U(1) invariant, the index itself exhibits the full $E_n$
symmetry (at least up to the order we expanded). The ray operators we studied
in 5d can be viewed as generalizations of operators constructed in a Yang-Mills
theory with fundamental matter by attaching an open Wilson line to a quark. For
$n\le 7$, in contrast to local operators, they carry nontrivial charge under
the $\mathbb{Z}_{9-n}\subset E_n$ center of the global symmetry. The
representations that appear in the ray operator index are therefore different,
for $n\le 7$, from those appearing in the previously computed superconformal
index. For $3\le n\le 7$, we find that the leading term in the index is a
character of a minuscule representation of $E_n$. We also discuss the case
$n=8$, which presents a unique technical challenge, and remains an open
problem.


title:
Spin Seebeck effect and thermoelectric phenomena in superconducting
  hybrids with magnetic textures or spin-orbit coupling

abstract:
  We theoretically consider the spin Seebeck effect, the charge Seebeck
coefficient, and the thermoelectric figure of merit in superconducting hybrid
structures including either magnetic textures or intrinsic spin-orbit coupling.
We demonstrate that large magnitudes for all these quantities are obtainable in
Josephson-based systems with either zero or a small externally applied magnetic
field. This provides an alternative to the thermoelectric effects generated in
high-field ($\sim 1$ T) superconducting hybrid systems, which were recently
experimentally demonstrated. The systems studied contain either textured
ferromagnets, spin-active interfaces, or spin-orbit coupling. We present a
framework for calculating the linear thermoelectric response for both spin and
charge of a system upon applying temperature and voltage gradients based on
quasiclassical theory which allows for arbitrary spin-dependent textures and
fields to be conveniently incorporated.


title: C/O and Mg/Si Ratios of Stars in the Solar Neighborhood

abstract:
  The carbon to oxygen ratio in a protoplanetary disk can have a dramatic
influence on the compositions of any terrestrial planets formed. In regions of
high C/O, planets form primarily from carbonates and in regions of low C/O, the
ratio of magnesium to silicon determines the types of silicates which dominate
the compositions. We present C/O and Mg/Si ratios for 849 F, G, and K dwarfs in
the solar neighborhood. We find that the frequency of carbon-rich dwarfs in the
solar neighborhood is < 0.13% and that 156 known planet hosts in the sample
follow a similar distribution as all of the stars as a whole. The cosmic
distribution of Mg/Si for these same stars is broader than the C/O distribution
and peaks near 1.0 with $\sim 60$% of systems having $1 \leq$ Mg/Si $< 2$,
leading to rocky planet compositions similar to the Earth. This leaves 40% of
systems that can have planets that are silicate rich and may have very
different compositions than our own.


title: Surprises with Nonrelativistic Naturalness

abstract:
  We explore the landscape of technical naturalness for nonrelativistic
systems, finding surprises which challenge and enrich our relativistic
intuition already in the simplest case of a single scalar field. While the
immediate applications are expected in condensed matter and perhaps in
cosmology, the study is motivated by the leading puzzles of fundamental physics
involving gravity: The cosmological constant problem and the Higgs mass
hierarchy problem.

categories: hep-th astro-ph.CO cond-mat.supr-con gr-qc hep-ph


title:
A new quadruple gravitational lens from the Hyper Suprime-Cam Survey:
  the puzzle of HSC~J115252+004733

abstract:
  We report the serendipitous discovery of a quadruply lensed source at $z_{\rm
s}=3.76$, HSC~J115252+004733, from the Hyper Suprime-Cam (HSC) Survey. The
source is lensed by an early-type galaxy at $z_{\rm l}=0.466$ and a satellite
galaxy. Here, we investigate the properties of the source by studying its size
and luminosity from the imaging and the luminosity and velocity width of the
Ly-$\alpha$ line from the spectrum. Our analyses suggest that the source is
most probably a low-luminosity active galactic nucleus (LLAGN) but the
possibility of it being a compact bright galaxy (e.g., a Lyman-$\alpha$ emitter
or Lyman Break Galaxy) cannot be excluded. The brighter pair of lensed images
appears point-like except in the HSC $i$-band (with a seeing $\sim0.5"$). The
extended emission in the $i$-band image could be due to the host galaxy
underneath the AGN, or alternatively, due to a highly compact lensed galaxy
(without AGN) which appears point-like in all bands except in $i$-band. We also
find that the flux ratio of the brighter pair of images is different in the
Ks-band compared to optical wavelengths. Phenomena such as differential
extinction and intrinsic variability cannot explain this chromatic variation.
While microlensing from stars in the foreground galaxy is less likely to be the
cause, it cannot be ruled out completely. If the galaxy hosts an AGN, then this
represents the highest redshift quadruply imaged AGN known to date, enabling
study of a distant LLAGN. Discovery of this unusually compact and faint source
demonstrates the potential of the HSC survey.


title:
Radial Distribution Of ISM Gas-phase Metallicity In CLASH Clusters at
  z~0.35: A New Outlook On Environmental Impact On Galaxy Evolution

abstract:
  We present the first observation of cluster-scale radial metallicity
gradients from star-forming galaxies. We use the DEIMOS spectrograph on the
Keck II telescope to observe two CLASH clusters at z~0.35: MACS1115+0129 and
RXJ1532+3021. Based on our measured interstellar medium (ISM) properties of
star-forming galaxies out to a radius of 2.5 Mpc from the cluster centre, we
find that the galaxy metallicity decreases as a function of projected
cluster-centric distance (-0.15+/-0.08 dex/Mpc) in MACS1115+01. On the
mass-metallicity relation (MZR), star-forming galaxies in MACS1115+01 are
offset to higher metallicity (~0.2 dex) than the local SDSS galaxies at a fixed
mass range. In contrast, the MZR of RXJ1532+30 is consistent with the local
comparison sample. RXJ1532+30 exhibits a bimodal radial metallicity
distribution, with one branch showing a similar negative gradient as
MACS1115+01 (-0.14+/-0.05 dex/Mpc) and the other branch showing a positive
radial gradient. The positive gradient branch in RXJ1532+30 is likely caused by
either interloper galaxies or an in-plane merger, indicating that cluster-scale
abundance gradients probe cluster substructures and thus the dynamical state of
a cluster. Most strikingly, we discover that neither the radial metallicity
gradient nor the offset from the MZR is driven by the stellar mass. We compare
our observations with Rhapsody-G cosmological hydrodynamical zoom-in
simulations of relaxed galaxy clusters and find that the simulated galaxy
cluster also exhibits a negative abundance gradient, albeit with a shallower
slope (-0.04+/-0.03 dex/Mpc). Our observations suggest that the negative radial
gradient originates from ram-pressure stripping and/or strangulation processes
in the cluster environments.


title: Efficiency of gas cooling and accretion at the disc-corona interface

abstract:
  In star-forming galaxies, stellar feedback can have a dual effect on the
circumgalactic medium both suppressing and stimulating gas accretion. The
trigger of gas accretion can be caused by disc material ejected into the halo
in the form of fountain clouds and by its interaction with the surrounding hot
corona. Indeed, at the disc-corona interface, the mixing between the
cold/metal-rich disc gas (T <~ 10^4 K) and the hot coronal gas (T >~ 10^6 K)
can dramatically reduce the cooling time of a portion of the corona and produce
its condensation and accretion. We studied the interaction between fountain
clouds and corona in different galactic environments through parsec-scale
hydrodynamical simulations, including the presence of thermal conduction, a key
mechanism that influences gas condensation. Our simulations showed that the
coronal gas condensation strongly depends on the galactic environment, in
particular it is less efficient for increasing virial temperature/mass of the
haloes where galaxies reside and it is fully ineffective for objects with
virial masses larger than 10^13 Msun. This result implies that the coronal gas
cools down quickly in haloes with low-intermediate virial mass (Mvir <~ 3 x
10^12 Msun) but the ability to cool the corona decreases going from late-type
to early-type disc galaxies, potentially leading to the switching off of
accretion and the quenching of star formation in massive systems.


title:
Proxima Centauri as a Benchmark for Stellar Activity Indicators in the
  Near Infrared

abstract:
  A new generation of dedicated Doppler spectrographs will attempt to detect
low-mass exoplanets around mid-late M stars at near infrared (NIR) wavelengths,
where those stars are brightest and have the most Doppler information content.
A central requirement for the success of these instruments is to properly
measure the component of radial velocity (RV) variability contributed by
stellar magnetic activity and to account for it in exoplanet models of RV data.
The wavelength coverage for many of these new instruments will not include the
Ca II H&K or H-alpha lines, the most frequently used absorption-line tracers of
magnetic activity. Thus, it is necessary to define and characterize NIR
activity indicators for mid-late M stars in order to provide simultaneous
activity metrics for NIR RV data. We have used the high-cadence UVES
observations of the M5.5 dwarf Proxima Centauri from Fuhrmeister et al. (2011)
to compare the activity sensitivity of 8 NIR atomic lines to that of H-alpha.
We find that equivalent width-type measurements of the NIR K I doublet and the
Ca II NIR triplet are excellent proxies for the canonical optical tracers. The
Ca II triplet will be acquired by most of the new and upcoming NIR Doppler
spectrographs, offering a common, reliable indicator of activity.


title:
Holographic equivalence between the first law of entanglement entropy
  and the linearized gravitational equations

abstract:
  We use the intertwining properties of integral transformations to provide a
compact proof of the holographic equivalence between the first law of
entanglement entropy and the linearized gravitational equations, in the context
of the AdS/CFT-correspondence. We build upon the framework developed by
Faulkner et al. [1] using the the Wald formalism, and exploit the symmetries of
the vacuum modular Hamiltonian of ball-shaped boundary regions.


title: Dicke phase transition without total spin conservation

abstract:
  We develop a new fermionic path-integral formalism to analyze the phase
diagram of open nonequilibrium systems. The formalism is applied to analyze an
ensemble of two-level atoms interacting with a single-mode optical cavity,
described by the Dicke model. While this model is often used as the
paradigmatic example of a phase transition in driven-dissipative systems,
earlier theoretical studies were limited to the special case when the total
spin of the atomic ensemble is conserved. This assumption is not justified in
most experimental realizations. Our new approach allows us to analyze the
problem in a more general case, including the experimentally relevant case of
dissipative processes that act on each atom individually and do not conserve
the total spin. We obtain a general expression for the position of the
transition, which contains as special cases the two previously known regimes:
i) non-equilibrium systems with losses and conserved spin and ii) closed
systems in thermal equilibrium and with the Gibbs ensemble averaging over the
values of the total spin. We perform a detailed study of different types of
baths and point out the possibility of a surprising non-monotonous dependence
of the transition on the baths' parameters.


title:
On the resonant detonation of sub-Chandrasekhar mass white dwarfs during
  binary inspiral

abstract:
  White dwarfs (WDs) are believed to detonate via explosive Carbon-fusion in a
Type Ia Supernova when their temperature and/or density reach the point where
Carbon is ignited in a runaway reaction. Observations of the Type Ia supernova
(SN) rate imply all WD binaries that merge through the emission of
gravitational radiation within a Hubble time should result in SNe, regardless
of total mass. Here we investigate the conditions under which a single WD in a
binary system might extract energy from its orbit, depositing enough energy
into a resonant mode such that it detonates before merger. We show that,
ignoring non-linear effects, in a WD binary in tidal lock at small binary
separations, the sustained tidal forcing of a low-order quadrupolar g-mode or a
harmonic of a low-order quadrupolar p-mode could in principle drive the average
temperature of Carbon nuclei in the mode over the runaway fusion threshold. If
growing mode energy is thermalized at a core/atmosphere boundary, rapid Helium
burning and inward-travelling p-waves may result in core detonation.
Thermalization at a boundary in the core can also result in detonation. If
energy can be efficiently transferred from the orbit to modes as the WD binary
passes through resonances, the WD merger timescale will be shortened by Myr-Gyr
compared to expected timescales from GW-emission alone and GW detectors will
observe deviations from predicted chirp profiles in resolved WD binaries.
Future work in this area should focus on whether tidal locking in WD binaries
is naturally driven towards low-order mode frequencies.


title:
Dwarf nova-type cataclysmic variable stars are significant radio
  emitters

abstract:
  We present 8--12\,GHz radio light curves of five dwarf nova (DN) type
Cataclysmic Variable stars (CVs) in outburst (RX And, U Gem and Z Cam), or
superoutburst (SU UMa and YZ Cnc), increasing the number of radio-detected DN
by a factor of two. The observed radio emission was variable on time-scales of
minutes to days, and we argue that it is likely to be synchrotron emission.
This sample shows no correlation between the radio luminosity and optical
luminosity, orbital period, CV class, or outburst type; however higher-cadence
observations are necessary to test this, as the measured luminosity is
dependent on the timing of the observations in these variable objects. The
observations show that the previously detected radio emission from SS Cyg is
not unique in type, luminosity (in the plateau phase of the outburst), or
variability time-scales. Our results prove that DN, as a class, are radio
emitters in outburst.


title: Neural networks for the prediction organic chemistry reactions

abstract:
  Reaction prediction remains one of the major challenges for organic
chemistry, and is a pre-requisite for efficient synthetic planning. It is
desirable to develop algorithms that, like humans, "learn" from being exposed
to examples of the application of the rules of organic chemistry. We explore
the use of neural networks for predicting reaction types, using a new reaction
fingerprinting method. We combine this predictor with SMARTS transformations to
build a system which, given a set of reagents and re- actants, predicts the
likely products. We test this method on problems from a popular organic
chemistry textbook.


title:
Variability study of the High Mass X-ray Binary IGR J18027--2016 with
  {\it Swift}--XRT

abstract:
  We report the results from pulsations and spectral analysis of a large number
of observations of the HMXB pulsar IGR J18027--2016 with {\it Swift}--XRT,
carried out at different orbital phases. In some orbital phases, as seen in
different XRT observations, the X-ray intensity is found to vary by a large
factor, of about $\sim$50. In all the observations with sufficient number of
source X-ray photons, pulsations have been detected around the previously known
pulse period of $\sim$140 sec, When detected, the pulse profiles do not show
any significant variation over a flux difference of a factor of $\sim$3. The
absorption column density is found to be large before and after the eclipse. We
discuss various possible reasons for intensity and spectral variations in IGR
J18027--2016, such as clumpy wind and hydrodynamic instabilities.


title: Infusing Collaborative Recommenders with Distributed Representations

abstract:
  Recommender systems assist users in navigating complex information spaces and
focus their attention on the content most relevant to their needs. Often these
systems rely on user activity or descriptions of the content. Social annotation
systems, in which users collaboratively assign tags to items, provide another
means to capture information about users and items. Each of these data sources
provides unique benefits, capturing different relationships.
  In this paper, we propose leveraging multiple sources of data: ratings data
as users report their affinity toward an item, tagging data as users assign
annotations to items, and item data collected from an online database. Taken
together, these datasets provide the opportunity to learn rich distributed
representations by exploiting recent advances in neural network architectures.
We first produce representations that subjectively capture interesting
relationships among the data. We then empirically evaluate the utility of the
representations to predict a user's rating on an item and show that it
outperforms more traditional representations. Finally, we demonstrate that
traditional representations can be combined with representations trained
through a neural network to achieve even better results.


title:
A Bottom Line for the LHC Data by Leveraging Pileup as a Zero Bias
  Trigger

abstract:
  Due to a limited bandwidth and a large proton-proton interaction
cross-section relative to the rate of interesting physics processes, most
events produced at the Large Hadron Collider (LHC) are discarded in real time.
A sophisticated trigger system must quickly decide which events should be kept
and is very efficient for a broad range of processes. However, there are many
processes that cannot be accommodated by this trigger system. Furthermore,
there may be models of physics beyond the Standard Model (BSM) constructed
after data taking that could have been triggered, but no trigger was
implemented at run time. Both of these cases can be covered by exploiting
pileup interactions as an effective zero bias sample. At the end of
High-Luminosity LHC operations, this zero bias dataset will have accumulated
about 1/fb of data from which a bottom line cross-section limit of O(1) fb can
be set for BSM models already in the literature and those yet to come.


title: Perturbation of Compact Planetary Systems by Distant Giant Planets

abstract:
  We examine the effect of secular perturbations by giant planets on systems of
multiple, lower mass planets orbiting Sun-like stars. We simulate the effects
of forcing both eccentricity and inclination, separately and together. We
compare our results to the statistics of the observed Kepler data and examine
whether these results can be used to explain the observed excess of single
transiting planets. We cannot explain the observed excess by pumping only
inclination without driving most systems over the edge of dynamical
instability. Thus, we expect the underlying planetary population for systems
with a single transitting planet to contain an intrinsically low multiplicity
population. We can explain the Kepler statistics and occurrence rates for R< 2
Rearth planets with a perturber population consistent with that inferred from
radial velocity surveys, but require too many giant planets if we wish to
explain all planets with R < 4 Rearth. These numbers can be brought into
agreement if we posit the existence of an equivalent size population of planets
below the RV detection limit (of characteristic mass 0.1 Mjupiter). This
population would need to be dynamically hot to produce sufficiently strong
perturbations and would leave the imprint of high obliquities amongst the
surviving planets. Thus, an extensive sample of obliquities for low mass
planets can help to indicate the presence of such a population. (...) Some of
our simulations also produce planetary systems with planets that survive in the
habitable zone but have no planets interior to them -- much as in the case of
our Solar System. This suggests that such a configuration may not be altogether
rare, but may occur around a few percent of FGK stars.


title:
Magnetostructural martensitic transformations with large volume changes
  and magneto-strains in all-d-metal Heusler alloys

abstract:
  The all-d-metal Mn2-based Heusler ferromagnetic shape memory alloys
Mn50Ni40-xCoxTi10 (x = 8 and 9.5) are realized. With a generic comparison
between d-metal Ti and main-group elements in lowering the transformation
temperature, the magnetostructural martensitic transformations are established
by further introducing Co to produce local ferromagnetic Mn-Co-Mn
configurations. A 5-fold modulation and (3, -2) stacking of [00 10] of
martensite are determined by XRD and HRTEM analysis. Based on the
transformation, a large magneto-strain of 6900 ppm and a large volume change of
-2.54% are observed in polycrystalline samples, which makes the all-d-metal
magnetic martensitic alloys of interest for magnetic/pressure multi-field
driven applications.


title: Disordered Chern insulator with a two step Floquet drive

abstract:
  We explore the physics of a Chern insulator subjected to a two step Floquet
drive. We analytically obtain the phase diagram and show that the system can
exhibit different topological phases characterized by presence and chirality of
edge-modes in the two bulk gaps of the Floquet quasienergy spectrum, around $0$
and $\pi$. We find that the phase of the system depends on the mean but not on
the amplitude of the drive. The bulk topological invariants characterizing the
phases can be extracted by mapping the unitary evolution within a time period
to an energetically trivial but topologically non-trivial time evolution. An
extensive numerical study of the bulk topological invariants in the presence of
quenched disorder reveals new transitions induced by strong disorder (i) from
the different topological to trivial insulator phases and (ii) from a trivial
to a topological Anderson insulator phase at intermediate disorder strengths.
Careful analysis of level statistics of the quasienergy spectrum indicates a
`levitation-annihilation' mechanism near these transitions.

categories: cond-mat.dis-nn cond-mat.mes-hall cond-mat.quant-gas quant-ph


title: Explaining the mechanism of random lasing based sensing

abstract:
  Here we report a random lasing based sensor which shows pH sensitivity
exceeding by 2-orders of magnitude that of a conventional fluorescence sensor.
We explain the sensing mechanism as related to gain modifications and lasing
threshold nonlinearities. A dispersive diffusive lasing theory matches well the
experimental results, and allow us to predict the optimal sensing conditions
and a maximal sensitivity as large as 200 times that of an identical
fluorescence-based sensor. The simplicity of operation and high sensitivity
make it promising for future biosensing applications.


title:
Spin Resolved Scattering and Spin-Orbital Entanglement in Mesoscopic
  Conductors

abstract:
  In this article, we have discussed about the scattering of charge and spin in
spin-resolved mesoscopic systems. We have proposed a method to generate and
detect the entanglement of electronic spin and electronic orbital degrees of
freedom. It is observed that in a spin-resolved mesoscopic system, all form of
entanglement existing between different electronic degrees of freedom can be
generated. A method to detect Bell's inequality violation in terms of zero
frequency current cross-correlators has been mentioned. Further, we have also
studied the effect of quantum interference between spin flip and non-spin flip
scattering matrices in determining the current and noise. We have obtained the
expression for shot noise of spin and charge current when an arbitrarily
polarised charge current is scattered at the spin resolved potential.


title:
Anchoring historical sequences using a new source of astro-chronological
  tie-points

abstract:
  The discovery of past spikes in atmospheric radiocarbon activity, caused by
major solar energetic particle events, has opened up new possibilities for
high-precision chronometry. The two spikes, or Miyake Events, have now been
widely identified in tree-rings that grew in the years 775 and 994 CE.
Furthermore, all other plant material that grew in these years would also have
incorporated the anomalously high concentrations of radiocarbon. Crucially,
some plant-based artefacts, such as papyrus documents, timber beams and linen
garments, can also be allocated to specific positions within long, currently
unfixed, historical sequences. Thus, Miyake Events represent a new source of
tie-points that could provide the means for anchoring early chronologies to the
absolute timescale. Here, we explore this possibility, outlining the most
expeditious approaches, the current challenges and obstacles, and how they
might best be overcome.


title: Search for EeV Protons of Galactic Origin

abstract:
  Cosmic rays in the energy range $10^{18.0}$ - $10^{18.5}$ eV are thought to
have a light, probably protonic, composition. To study their origin one can
search for anisotropy in their arrival directions. Extragalactic cosmic rays
should be isotropic, but galactic cosmic rays of this type should be seen
mostly along the galactic plane, and there should be a shortage of events
coming from directions near the galactic anticenter. This is due to the fact
that, under the influence of the galactic magnetic field, the transition from
ballistic to diffusive behavior is well advanced, and this qualitative picture
persists over the whole energy range. Guided by models of the galactic magnetic
field that indicate that the enhancement along the galactic plane should have a
standard deviation of about 20$^\circ$ in galactic latitude, and the deficit in
the galactic anticenter direction should have a standard deviation of about
50$^\circ$ in galactic longitude, we use the data of the Telescope Array
surface detector in $10^{18.0}$ to $10^{18.5}$ eV energy range to search for
these effects. The data are isotropic. Neither an enhancement along the
galactic plane nor a deficit in the galactic anticenter direction is found.
Using these data we place an upper limit on the fraction of EeV cosmic rays of
galactic origin at 1.3% at 95% confidence level.


title:
Finite-size and composition-driven topological phase transition in
  (Bi$_{1-x}$In$_x$)$_2$Se$_3$ thin films

abstract:
  In a topological insulator (TI), if its spin-orbit coupling (SOC) strength is
gradually reduced, the TI eventually transforms into a trivial insulator beyond
a critical point of SOC, at which point the bulk gap closes: this is the
standard description of the topological phase transition (TPT). However, this
description of TPT, driven solely by the SOC (or something equivalent) and
followed by closing and reopening of the bulk band gap, is valid only for
infinite-size samples, and little is known how TPT occurs for finite-size
samples. Here, using both systematic transport measurements on
interface-engineered(Bi$_{1-x}$In$_x$)$_2$Se$_3$ thin films and theoretical
simulations (with animations in Supporting Information) we show that
description of TPT in finite-size samples needs to be substantially modified
from the conventional picture of TPT due to surface-state hybridization and
bulk confinement effects. We also show that the finite-size TPT is composed of
two separate transitions, topological-normal transition (TNT) and
metal-insulator transition (MIT) by providing a detailed phase diagram in the
two-dimensional phase space of sample size and SOC strength.


title:
The initial-boundary value problem for Schr\"odinger-Korteweg-de Vries
  system on the half-line

abstract:
  We prove local well-posedness for the initial-boundary value problem (IBVP)
associated to the Schr\"odinger-Korteweg de Vries system on right and left
half-lines. The results are obtained in the low regularity setting by using two
analytic families of boundary forcing operators, being one of these family
developed by Holmer to study the IBVP associated to the Korteweg-de Vries
equation (Communications in Partial Differential Equations, 31 (2006)) and the
other family one was recently introduced by Cavalcante (Differential and
Integral Equations (2017)) in the context of nonlinear Schr\"odinger with
quadratic nonlinearities.


title:
Regression Modeling and File Matching Using Possibly Erroneous Matching
  Variables

abstract:
  Many analyses require linking records from two databases comprising
overlapping sets of individuals. In the absence of unique identifiers, the
linkage procedure often involves matching on a set of categorical variables,
such as demographics, common to both files. Typically, however, the resulting
matches are inexact: some cross-classifications of the matching variables do
not generate unique links across files. Further, the variables used for
matching can be subject to reporting errors, which introduce additional
uncertainty in analyses. We present a Bayesian file matching methodology
designed to estimate regression models and match records simultaneously when
categorical variables used for matching are subject to errors. The method
relies on a hierarchical model that includes (1) the regression of interest
involving variables from the two files given a vector indicating the links, (2)
a model for the linking vector given the true values of the variables used for
matching, (3) a model for reported values of the variables used for matching
given their true values, and (4) a model for the true values of the variables
used for matching. We describe algorithms for sampling from the posterior
distribution of the model. We illustrate the methodology using artificial data
and data from education records in the state of North Carolina.


title:
Job Placement Advisor Based on Turnaround Predictions for HPC Hybrid
  Clouds

abstract:
  Several companies and research institutes are moving their CPU-intensive
applications to hybrid High Performance Computing (HPC) cloud environments.
Such a shift depends on the creation of software systems that help users decide
where a job should be placed considering execution time and queue wait time to
access on-premise clusters. Relying blindly on turnaround prediction techniques
will affect negatively response times inside HPC cloud environments. This paper
introduces a tool to make job placement decisions in HPC hybrid cloud
environments taking into account the inaccuracy of execution and waiting time
predictions. We used job traces from real supercomputing centers to run our
experiments, and compared the performance between environments using real
speedup curves. We also extended a state-of-the-art machine learning based
predictor to work with data from the cluster scheduler. Our main findings are:
(i) depending on workload characteristics, there is a turning point where
predictions should be disregarded in favor of a more conservative decision to
minimize job turnaround times and (ii) scheduler data plays a key role in
improving predictions generated with machine learning using job trace
data---our experiments showed around 20% prediction accuracy improvements.


title: Disorder Induced Phase Transitions of Type-II Weyl Semimetal

abstract:
  Weyl semimetals are a newly discovered class of materials that host
relativistic massless Weyl fermions as their low-energy bulk excitations. Among
this new class of materials, there exist two general types of semimetals that
are of particular interest: type-I Weyl semimetals, that have broken inversion
or time-reversal symmetry symmetry, and type-II Weyl semimetals, that
additionally breaks Lorentz invariance. In this work, we use Born approximation
to analytically demonstrate that the type-I Weyl semimetals may undergo a
quantum phase transition to type-II Weyl semimetals in the presence of the
finite charge and magnetic disorder when non-zero tilt exist. The phase
transition occurs when the disorder renormalizes the topological mass, thereby
reducing the Fermi velocity near the Weyl cone below the tilt of the cone. We
also confirm the presence of the disorder induced phase transition in Weyl
semimetals using exact diagonalization of a three-dimensional tight-binding
model to calculate the resultant phase diagram of the type-I Weyl semimetal.


title: Response to Wiseman, Rieffel, and Cavalcanti on Bell's 1964 Paper

abstract:
  Wiseman has claimed that Bell was wrong in stating that determinism was
inferred rather than assumed in the summary of the EPR argument in his 1964
paper. The reply of Wiseman and his co-authors to my comment misstates my
reasons for disputing this point, and fails to address the central criticism
that their claim is based on a seriously flawed formalization of Bell's
argument deriving from an unreasonably strong interpretation of the the terms,
'influence', 'affect', and 'depend on'.


title:
Simon's fundamental rich-get-richer model entails a dominant first-mover
  advantage

abstract:
  Herbert Simon's classic rich-get-richer model is one of the simplest
empirically supported mechanisms capable of generating heavy-tail size
distributions for complex systems. Simon argued analytically that a population
of flavored elements growing by either adding a novel element or randomly
replicating an existing one would afford a distribution of group sizes with a
power-law tail. Here, we show that, in fact, Simon's model does not produce a
simple power law size distribution as the initial element has a dominant
first-mover advantage, and will be overrepresented by a factor proportional to
the inverse of the innovation probability. The first group's size discrepancy
cannot be explained away as a transient of the model, and may therefore be many
orders of magnitude greater than expected. We demonstrate how Simon's analysis
was correct but incomplete, and expand our alternate analysis to quantify the
variability of long term rankings for all groups. We find that the expected
time for a first replication is infinite, and show how an incipient group must
break the mechanism to improve their odds of success. We present an example of
citation counts for a specific field that demonstrates a first-mover advantage
consistent with our revised view of the rich-get-richer mechanism. Our findings
call for a reexamination of preceding work invoking Simon's model and provide
an expanded understanding going forward.


title:
Age-dependent Branching Processes and Applications to the
  Luria-Delbr\"uck Experiment

abstract:
  Microbial populations adapt to their environment by acquiring advantageous
mutations, but in the early twentieth century, questions about how these
organisms acquire mutations arose. The experiment of Salvador Luria and Max
Delbr\"uck that won them a Nobel Prize in 1969 confirmed that mutations don't
occur out of necessity, but instead can occur many generations before there is
a selective advantage, and thus organisms follow Darwinian evolution instead of
Lamarckian. Since then, new areas of research involving microbial evolution
have spawned as a result of their experiment. Determining the mutation rate of
a cell is one such area. Probability distributions that determine the number of
mutants in a large population have been derived by D. E. Lea, C. A. Coulson,
and J. B. S. Haldane. However, not much work has been done when time of cell
division is dependent on the cell age, and even less so when cell division is
asymmetric, which is the case in most microbial populations. Using probability
generating function methods, we rigorously construct a probability distribution
for the cell population size given a life-span distribution for both mother and
daughter cells, and then determine its asymptotic growth rate. We use this to
construct a probability distribution for the number of mutants in a large cell
population, which can be used with likelihood methods to estimate the cell
mutation rate.


title: LFADS - Latent Factor Analysis via Dynamical Systems

abstract:
  Neuroscience is experiencing a data revolution in which many hundreds or
thousands of neurons are recorded simultaneously. Currently, there is little
consensus on how such data should be analyzed. Here we introduce LFADS (Latent
Factor Analysis via Dynamical Systems), a method to infer latent dynamics from
simultaneously recorded, single-trial, high-dimensional neural spiking data.
LFADS is a sequential model based on a variational auto-encoder. By making a
dynamical systems hypothesis regarding the generation of the observed data,
LFADS reduces observed spiking to a set of low-dimensional temporal factors,
per-trial initial conditions, and inferred inputs. We compare LFADS to existing
methods on synthetic data and show that it significantly out-performs them in
inferring neural firing rates and latent dynamics.


title: Isomorphism of uniform algebras on the 2-torus

abstract:
  For $\alpha$ a positive irrational, let $\mathcal{A}_{\alpha}$ be the
subalgebra of continuous functions on the two-torus whose Fourier transform
vanishes at $(m, n)$ if $m + \alpha n < 0.$ These algebras were studied by
Wermer and others, who proved properties such as maximality and characterized
the Gelfand space. One of the major themes of current work in operator algebras
is classification, but none of the properties which were investigated earlier
distinguished between $\mathcal{A}_{\alpha}$ and $\mathcal{A}_{\beta},$ if
$\beta $ is another positive irrational. We address this question. We also
determine the automorphism group of $\mathcal{A}_{\alpha}.$


title:
$\mathrm{FI}_G$-modules, orbit configuration spaces, and complex
  reflection groups

abstract:
  The category $\mathrm{FI}_G$ was first defined and explored by Sam-Snowden.
Here, we develop more of the machinery of $\mathrm{FI}_G$-modules and find
numerous examples to apply it to, extending the work of Church-Ellenberg-Farb
and Wilson.
  In particular we develop a notion of character polynomials for
$\mathrm{FI}_G$-modules with $G$ finite, a notion of representation stability
which we call $K_0$-stability even when $G$ is infinite virtually polycyclic,
and apply the notion of finite presentation degree when $G$ is a general
infinite group. We use this to analyze numerous families of $(G^n \rtimes
S_n)$-modules, such as:
  -the cohomology and homotopy groups of orbit configuration spaces
  -the diagonal coinvariant algebra of complex reflection groups
  -the homology of affine pure braid groups of type $\widetilde{A}_n$ and
$\widetilde{C}_n$
  -the cohomology of Fouxe-Rabinowitsch groups
  and many more examples.


title: Privacy Amplification Against Active Quantum Adversaries

abstract:
  Privacy amplification is the task by which two cooperating parties transform
a shared weak secret, about which an eavesdropper may have side information,
into a uniformly random string uncorrelated from the eavesdropper. Privacy
amplification against passive adversaries, where it is assumed that the
communication is over a public but authenticated channel, can be achieved in
the presence of classical as well as quantum side information by a
single-message protocol based on strong extractors.
  In 2009 Dodis and Wichs devised a two-message protocol to achieve privacy
amplification against active adversaries, where the public communication
channel is no longer assumed to be authenticated, through the use of a
strengthening of strong extractors called non-malleable extractors which they
introduced. Dodis and Wichs only analyzed the case of classical side
information.
  We consider the task of privacy amplification against active adversaries with
quantum side information. Our main result is showing that the Dodis-Wichs
protocol remains secure in this scenario provided its main building block, the
non-malleable extractor, satisfies a notion of quantum-proof non-malleability
which we introduce. We show that an adaptation of a recent construction of
non-malleable extractors due to Chattopadhyay et al. is quantum proof, thereby
providing the first protocol for privacy amplification that is secure against
active quantum adversaries. Our protocol is quantitatively comparable to the
near-optimal protocols known in the classical setting.


title:
A Comparison of Flare Forecasting Methods, I: Results from the
  "All-Clear" Workshop

abstract:
  Solar flares produce radiation which can have an almost immediate effect on
the near-Earth environment, making it crucial to forecast flares in order to
mitigate their negative effects. The number of published approaches to flare
forecasting using photospheric magnetic field observations has proliferated,
with varying claims about how well each works. Because of the different
analysis techniques and data sets used, it is essentially impossible to compare
the results from the literature. This problem is exacerbated by the low event
rates of large solar flares. The challenges of forecasting rare events have
long been recognized in the meteorology community, but have yet to be fully
acknowledged by the space weather community. During the interagency workshop on
"all clear" forecasts held in Boulder, CO in 2009, the performance of a number
of existing algorithms was compared on common data sets, specifically
line-of-sight magnetic field and continuum intensity images from MDI, with
consistent definitions of what constitutes an event. We demonstrate the
importance of making such systematic comparisons, and of using standard
verification statistics to determine what constitutes a good prediction scheme.
When a comparison was made in this fashion, no one method clearly outperformed
all others, which may in part be due to the strong correlations among the
parameters used by different methods to characterize an active region. For
M-class flares and above, the set of methods tends towards a weakly positive
skill score (as measured with several distinct metrics), with no participating
method proving substantially better than climatological forecasts.


title:
Analysis of the Herschel/HEXOS Spectral Survey Towards Orion South: A
  massive protostellar envelope with strong external irradiation

abstract:
  We present results from a comprehensive submillimeter spectral survey toward
the source Orion South, based on data obtained with the HIFI instrument aboard
the \textit{Herschel Space Observatory}, covering the frequency range 480 to
1900 GHz. We detect 685 spectral lines with S/N $>$ 3$\sigma$, originating from
52 different molecular and atomic species. We model each of the detected
species assuming conditions of Local Thermodynamic Equilibrium. This analysis
provides an estimate of the physical conditions of Orion South (column density,
temperature, source size, \& V$_{LSR}$). We find evidence for three different
cloud components: a cool (T$_{ex} \sim 20-40$ K), spatially extended ($> 60"$),
and quiescent ($\Delta V_{FWHM} \sim 4$ km s $^{-1}$) component; a warmer
(T$_{ex} \sim 80-100$ K), less spatially extended ($\sim 30"$), and dynamic
($\Delta V_{FWHM} \sim 8$ km s $^{-1}$) component, which is likely affected by
embedded outflows; and a kinematically distinct region (T$_{ex}$ $>$ 100 K;
V$_{LSR}$ $\sim$ 8 km s $^{-1}$), dominated by emission from species which
trace ultraviolet irradiation, likely at the surface of the cloud. We find
little evidence for the existence of a chemically distinct "hot core"
component, likely due to the small filling factor of the hot core or hot cores
within the \textit{Herschel} beam. We find that the chemical composition of the
gas in the cooler, quiescent component of Orion South more closely resembles
that of the quiescent ridge in Orion-KL. The gas in the warmer, dynamic
component, however, more closely resembles that of the Compact Ridge and
Plateau regions of Orion-KL, suggesting that higher temperatures and shocks
also have an influence on the overall chemistry of Orion South.


title:
Cohesive energy and structural parameters of binary oxides of groups IIA
  and IIIB from diffusion quantum Monte Carlo

abstract:
  We have applied the diffusion quantum Monte Carlo (DMC) method to calculate
the cohesive energy and the structural parameters of the binary oxides CaO,
SrO, BaO, Sc2O3, Y2O3 and La2O3. The aim of our calculations is to
systematically quantify the accuracy of the DMC method to study this type of
metal oxides. The DMC results were compared with local, semi-local and hybrid
Density Functional Theory (DFT) approximations as well as with experimental
measurements. The DMC method yields cohesive energies for these oxides with a
mean absolute deviation from experimental measurements of 0.18(2) eV, while
with local, semi-local and hybrid DFT approximations the deviation is 3.06,
0.94 and 1.23 eV, respectively. For lattice constants, the mean absolute
deviation in DMC, local, semi-local and hybrid DFT approximations, are
0.017(1), 0.07, 0.05 and 0.04 {\AA}, respectively. DMC is highly accurate
method, outperforming the DFT approximations in describing the cohesive
energies and structural parameters of these binary oxides.


title: A characterization of finite $p$-groups by their Schur multiplier

abstract:
  Let $G$ be a finite $p$-group of order $p^n$ and $M(G)$ be its Schur
multiplier. It is well known result by Green that $|M(G)|=
p^{\frac{1}{2}n(n-1)-t(G)}$ for some $t(G) \geq 0$. In this article we classify
non-abelian $p$-groups $G$ of order $p^n$ for $t(G)=\log_p(|G|)+1$.


title:
Observation of the quantum-anomalous-Hall insulator to Anderson
  insulator quantum phase transition and its scaling behavior

abstract:
  Fundamental insight into the nature of the quantum phase transition from a
superconductor to an insulator in two dimensions, or from one plateau to the
next or to an insulator in quantum Hall effect, has been revealed through the
study of its scaling behavior. Here, we report on the experimental observation
of a quantum phase transition from a quantum-anomalous-Hall (QAH) insulator to
an Anderson insulator in a magnetic topological insulator by tuning the
chemical potential. Our experiment demonstrates the existence of scaling
behavior from which we extract the critical exponent for this quantum phase
transition. We expect that our work will motivate much further investigation of
many properties of quantum phase transition in this new context.


title:
Positron excess in the center of the Milky Way from short-lived
  $\beta^+$ emitting isotopes

abstract:
  Observations of the INTEGRAL satellite revealed the presence of yet
unexplained excess in the central region of the Galaxy at the energies around
511 keV. These gamma-rays are produced in the process of positron annihilation,
the needed rate is around $10^{42}~\mathrm{s^{-1}}$. In this short paper it is
shown that \pos -emitting isotopes that are formed in interactions of
subrelativistic cosmic rays (CRs) with light nuclei (CNONe) can account for a
considerable fraction -- up to several tens of percent -- of $e^{+}$ production
rate in the central region.


title: A PTAS for the Steiner Forest Problem in Doubling Metrics

abstract:
  We achieve a (randomized) polynomial-time approximation scheme (PTAS) for the
Steiner Forest Problem in doubling metrics. Before our work, a PTAS is given
only for the Euclidean plane in [FOCS 2008: Borradaile, Klein and Mathieu]. Our
PTAS also shares similarities with the dynamic programming for sparse instances
used in [STOC 2012: Bartal, Gottlieb and Krauthgamer] and [SODA 2016: Chan and
Jiang]. However, extending previous approaches requires overcoming several
non-trivial hurdles, and we make the following technical contributions.
  (1) We prove a technical lemma showing that Steiner points have to be "near"
the terminals in an optimal Steiner tree. This enables us to define a heuristic
to estimate the local behavior of the optimal solution, even though the Steiner
points are unknown in advance. This lemma also generalizes previous results in
the Euclidean plane, and may be of independent interest for related problems
involving Steiner points.
  (2) We develop a novel algorithmic technique known as "adaptive cells" to
overcome the difficulty of keeping track of multiple components in a solution.
Our idea is based on but significantly different from the previously proposed
"uniform cells" in the FOCS 2008 paper, whose techniques cannot be readily
applied to doubling metrics.


title:
Longest monotone subsequences and rare regions of pattern-avoiding
  permutations

abstract:
  We consider the distributions of the lengths of the longest monotone and
alternating subsequences in classes of permutations of size $n$ that avoid a
specific pattern or set of patterns, with respect to the uniform distribution
on each such class. We obtain exact results for any class that avoids two
patterns of length 3, as well as results for some classes that avoid one
pattern of length 4 or more. In our results, the longest monotone subsequences
have expected length proportional to $n$ for pattern-avoiding classes, in
contrast with the $\sqrt n$ behaviour that holds for unrestricted permutations.
  In addition, for a pattern $\tau$ of length $k$, we scale the plot of a
random $\tau$-avoiding permutation down to the unit square and study the "rare
region," which is the part of the square that is exponentially unlikely to
contain any points. We prove that when $\tau_1>\tau_k$, the complement of the
rare region is a closed set that contains the main diagonal of the unit square.
For the case $\tau_1=k,$ we also show that the lower boundary of the part of
the rare region above the main diagonal is a curve that is Lipschitz continuous
and strictly increasing on $[0,1]$.


title:
A solution to Tingley's problem for isometries between the unit spheres
  of compact C$^*$-algebras and JB$^*$-triples

abstract:
  Let $f: S(E) \to S(B)$ be a surjective isometry between the unit spheres of
two weakly compact JB$^*$-triples not containing direct summands of rank
smaller than or equal to 3. Suppose $E$ has rank greater than or equal to 5.
Applying techniques developed in JB$^*$-triple theory, we prove that $f$ admits
an extension to a surjective real linear isometry $T: E\to B$. Among the
consequences, we show that every surjective isometry between the unit spheres
of two compact C$^*$-algebras $A$ and $B$ (and in particular when $A=K(H)$ and
$B=K(H')$) extends to a surjective real linear isometry from $A$ into $B$.
These results provide new examples of infinite dimensional Banach spaces where
Tingley's problem admits a positive answer.


title: Functional Multiplex PageRank

abstract:
  Recently it has been recognized that many complex social, technological and
biological networks have a multilayer nature and can be described by multiplex
networks. Multiplex networks are formed by a set of nodes connected by links
having different connotations forming the different layers of the multiplex.
Characterizing the centrality of the nodes in a multiplex network is a
challenging task since the centrality of the node naturally depends on the
importance associated to links of a certain type. Here we propose to assign to
each node of a multiplex network a centrality called Functional Multiplex
PageRank that is a function of the weights given to every different pattern of
connections (multilinks) existent in the multiplex network between any two
nodes. Since multilinks distinguish all the possible ways in which the links in
different layers can overlap, the Functional Multiplex PageRank can describe
important non-linear effects when large relevance or small relevance is
assigned to multilinks with overlap. Here we apply the Functional Page Rank to
the multiplex airport networks, to the neuronal network of the nematode
c.elegans, and to social collaboration and citation networks between
scientists. This analysis reveals important differences existing between the
most central nodes of these networks, and the correlations between their so
called "pattern to success".


title:
Relaxation of Microwave Nonlinearity in a Cuprate Superconducting
  Resonator

abstract:
  The 2nd and 3rd order nonlinear microwave response of a superconducting
YBa2Cu3O7 thin film resonator was synchronously measured using three input
tones. This technique permits the local measurement, and hence mapping, of
intermodulation distortion (IMD) inside the resonator. 2nd and 3rd order IMD
measured with a fixed probe relaxed in remarkably different ways after the
removal of a static magnetic field. The 2nd order IMD relaxed by two different
magnetic processes, a fast process that appears related to bulk remanent
magnetization, and a slow process that fits the description of Bean and
Livingston. The 3rd order IMD relaxes by only one process which is distinct
from the two processes controlling 2nd order relaxation.


title:
Revisiting nested group testing procedures: new results, comparisons,
  and robustness

abstract:
  Group testing has its origin in the identification of syphilis in the US army
during World War II. Much of the theoretical framework of group testing was
developed starting in the late 1950s, with continued work into the 1990s.
Recently, with the advent of new laboratory and genetic technologies, there has
been an increasing interest in group testing designs for cost saving purposes.
In this paper, we compare different nested designs, including Dorfman, Sterrett
and an optimal nested procedure obtained through dynamic programming. To
elucidate these comparisons, we develop closed-form expressions for the optimal
Sterrett procedure and provide a concise review of the prior literature for
other commonly used procedures. We consider designs where the prevalence of
disease is known as well as investigate the robustness of these procedures when
it is incorrectly assumed. This article provides a technical presentation that
will be of interest to researchers as well as from a pedagogical perspective.
Supplementary material for this article is available online.


title:
Quadratic Zeeman effect and spin-lattice relaxation of Tm$^{3+}$:YAG at
  high magnetic fields

abstract:
  Anisotropy of the quadratic Zeeman effect for the $^3{\rm H}_6 \rightarrow \,
^3{\rm H}_4$ transition at 793 nm wavelength in $^{169}$Tm$^{3+}$-doped
Y$_3$Al$_5$O$_{12}$ is studied, revealing shifts ranging from near zero up to +
4.69 GHz/T$^2$ for ions in magnetically inequivalent sites. This large range of
shifts is used to spectrally resolve different subsets of ions and study
nuclear spin relaxation as a function of temperature, magnetic field strength,
and orientation in a site-selective manner. A rapid decrease in spin lifetime
is found at large magnetic fields, revealing the weak contribution of
direct-phonon absorption and emission to the nuclear spin-lattice relaxation
rate. We furthermore confirm theoretical predictions for the phonon coupling
strength, finding much smaller values than those estimated in the limited
number of past studies of thulium in similar crystals. Finally, we observe a
significant -- and unexpected -- magnetic field dependence of the two-phonon
Orbach spin relaxation process at higher field strengths, which we explain
through changes in the electronic energy-level splitting arising from the
quadratic Zeeman effect.


title:
Nano-scale Inhomogeneous Superconductivity in Fe(Te1-xSex) Probed by
  Nanostructure-transport

abstract:
  Among iron based superconductors, the layered iron chalcogenide Fe(Te1-xSex)
is structurally the simplest and has attracted considerable attentions. It has
been speculated from bulk studies that nanoscale inhomogeneous
superconductivity may inherently exist in this system. However, this has not
been directly observed from nanoscale transport measurements. In this work,
through simple micromechanical exfoliation and high precision low-energy ion
milling thinning, we prepared Fe(Te0.5Se0.5) nano-flake with various thickness
and systematically studied the correlation between the thickness and
superconducting phase transition. Our result revealed a systematic evolution of
superconducting transition with thickness. When the thickness of Fe(Te0.5Se0.5)
flake is reduced down to 12nm, i.e. the characteristic length of Te/Se
fluctuation, the superconducting current path and the metallicity of normal
state in Fe(Te0.5Se0.5) atomic sheets is suppressed. This observation provides
the first direct transport evidence for the nano-scale inhomogeneous nature of
superconductivity in Fe(Te1-xSex).


title: Spin transport in half-metallic ferromagnets

abstract:
  We theoretically investigate spin transport in half-metallic ferromagnets at
finite temperatures. The side-jump and skew-scattering contributions to spin
Hall conductivity are derived using the Kubo formula. The electron-magnon
interaction causes a finite density of states in the energy gap of the
minority-spin band and induces spin Hall conductivity. We show that spin Hall
conductivity is proportional to $T^{3/2}$, with $T$ being temperature and is
sensitive to $T$. We propose that spin Hall conductivity may be a tool to study
the minority-spin state.


title: A biological tissue-inspired tunable photonic fluid

abstract:
  Inspired by how cells pack in dense biological tissues, we design 2D and 3D
amorphous materials which possess a complete photonic band gap. A physical
parameter based on how cells adhere with one another and regulate their shapes
can continuously tune the photonic band gap size as well as the bulk mechanical
properties of the material. The material can be tuned to go through a
solid-fluid phase transition characterized by a vanishing shear modulus.
Remarkably, the photonic band gap persists in the fluid phase, giving rise to a
photonic fluid that is robust to flow and rearrangements. Experimentally this
design should lead to the engineering of self-assembled non-rigid photonic
structures with photonic band gaps that can be controlled in real time via
mechanical and thermal tuning.

categories: cond-mat.soft cond-mat.dis-nn physics.bio-ph physics.optics


title: A logical qubit in a linear array of semiconductor quantum dots

abstract:
  We design and analyze a logical qubit composed of a linear array of electron
spins in semiconductor quantum dots. To avoid the difficulty of fully
controlling a two-dimensional array of dots, we adapt spin control and error
correction to a one-dimensional line of silicon quantum dots. Control speed and
efficiency are maintained via a scheme in which electron spin states are
controlled globally using broadband microwave pulses for magnetic resonance
while two-qubit gates are provided by local electrical control of the exchange
interaction between neighboring dots. Error correction with two-, three-, and
four-qubit codes is adapted to a linear chain of qubits with nearest-neighbor
gates. We estimate an error correction threshold of 1e-4. Furthermore, we
describe a sequence of experiments to validate the methods on near-term devices
starting from four coupled dots.


title:
Event-driven Trajectory Optimization for Data Harvesting in Multi-Agent
  Systems

abstract:
  We propose a new event-driven method for on-line trajectory optimization to
solve the data harvesting problem: in a two-dimensional mission space, N mobile
agents are tasked with the collection of data generated at M stationary sources
and delivery to a base with the goal of minimizing expected collection and
delivery delays. We define a new performance measure that addresses the event
excitation problem in event-driven controllers and formulate an optimal control
problem. The solution of this problem provides some insights on its structure,
but it is computationally intractable, especially in the case where the data
generating processes are stochastic. We propose an agent trajectory
parameterization in terms of general function families which can be
subsequently optimized on line through the use of Infinitesimal Perturbation
Analysis (IPA). Properties of the solutions are identified, including
robustness with respect to the stochastic data generation process and
scalability in the size of the event set characterizing the underlying hybrid
dynamical system. Explicit results are provided for the case of elliptical and
Fourier series trajectories and comparisons with a state-of-the-art graph-based
algorithm are given.


title:
Measurements of Terahertz Radiation Generated using a Metallic,
  Corrugated Pipe

abstract:
  A method for producing narrow-band THz radiation proposes passing an
ultra-relativistic beam through a metallic pipe with small periodic
corrugations. We present results of a measurement of such an arrangement at
Brookhaven's Accelerator Test Facility (ATF). Our pipe was copper and was 5 cm
long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a
corrugation depth (peak-to-peak) of 60 um. In the experiment we measured both
the effect on the beam of the structure wakefield and the spectral properties
of the radiation excited by the beam. We began by injecting a relatively long
beam compared to the wavelength of the radiation, but with short rise time, to
excite the structure, and then used a downstream spectrometer to infer the
radiation wavelength. This was followed by injecting a shorter bunch, and then
using an interferometer (also downstream of the corrugated pipe) to measure the
spectrum of the induced THz radiation. For the THz pulse we obtain and compare
with calculations: the central frequency, the bandwidth, and the spectral
power---compared to a diffraction radiation background signal.


title:
Large-scale Continuous Gesture Recognition Using Convolutional Neural
  Networks

abstract:
  This paper addresses the problem of continuous gesture recognition from
sequences of depth maps using convolutional neutral networks (ConvNets). The
proposed method first segments individual gestures from a depth sequence based
on quantity of movement (QOM). For each segmented gesture, an Improved Depth
Motion Map (IDMM), which converts the depth sequence into one image, is
constructed and fed to a ConvNet for recognition. The IDMM effectively encodes
both spatial and temporal information and allows the fine-tuning with existing
ConvNet models for classification without introducing millions of parameters to
learn. The proposed method is evaluated on the Large-scale Continuous Gesture
Recognition of the ChaLearn Looking at People (LAP) challenge 2016. It achieved
the performance of 0.2655 (Mean Jaccard Index) and ranked $3^{rd}$ place in
this challenge.


title:
Quantization and Feedback of Spatial Covariance Matrix for Massive MIMO
  Systems with Cascaded Precoding

abstract:
  In this paper, we investigate the quantization and the feedback of downlink
spatial covariance matrix for massive multiple-input multiple-output (MIMO)
systems with cascaded precoding. Massive MIMO has gained a lot of attention
recently because of its ability to significantly improve the network
performance. To reduce the overhead of downlink channel estimation and uplink
feedback in frequency-division duplex massive MIMO systems, cascaded precoding
has been proposed, where the outer precoder is implemented using traditional
limited feedback while the inner precoder is determined by the spatial
covariance matrix of the channels. In massive MIMO systems, it is difficult to
quantize the spatial covariance matrix because of its large size caused by the
huge number of antennas. In this paper, we propose a spatial spectrum based
approach for the quantization and the feedback of the spatial covariance
matrix. The proposed inner precoder can be viewed as modulated discrete prolate
spheroidal sequences and thus achieve much smaller spatial leakage than the
traditional discrete Fourier transform submatrix based precoding. Practical
issues for the application of the proposed approach are also addressed in this
paper.


title: Levelwise modules over separable monads on stable derivators

abstract:
  We show that given a separable cocontinuous monad on a stable derivator, the
levelwise Eilenberg-Moore categories of modules glue together to a stable
derivator. As an application, we give examples of derivators that satisfy all
the axioms for stability except the strongness one.


title:
Design and Analysis of Downlink Channel Estimation Based on Parametric
  Model for Massive MIMO in FDD Systems

abstract:
  This paper investigates downlink channel estimation in frequency-division
duplex (FDD)-based massive multiple-input multiple-output (MIMO) systems. To
reduce the overhead of downlink channel estimation and uplink feedback in FDD
systems, cascaded precoding has been used in massive MIMO such that only a
low-dimensional effective channel needs to be estimated and fed back. On the
other hand, traditional channel estimations can hardly achieve the minimum
mean-square-error (MMSE) performance due to lack of the a priori knowledge of
the channels. In this paper, we design and analyze a strategy for downlink
channel estimation based on the parametric model in massive MIMO with cascaded
precoding. For a parametric model, channel frequency responses are expressed
using the path delays and the associated complex amplitudes. The path delays of
uplink channels are first estimated and quantized at the base station, then fed
forward to the user equipment (UE) through a dedicated feedforward link. In
this manner, the UE can obtain the a priori knowledge of the downlink channel
in advance since it has been demonstrated that the downlink and the uplink
channels can have identical path delays. Our analysis and simulation results
show that the proposed approach can achieve near-MMSE performance.


title:
The Chemical Abundance Structure of the Inner Milky Way: A Signature of
  "Upside-Down" Disk Formation?

abstract:
  We present a model for the [alpha/Fe]-[Fe/H] distribution of stars in the
inner Galaxy, R=3-5 kpc, measured as a function of vertical distance |z| from
the midplane by Hayden et al. (2015, H15). Motivated by an "upside-down"
scenario for thick disk formation, in which the thickness of the star-forming
gas layer contracts as the stellar mass of the disk grows, we combine one-zone
chemical evolution with a simple prescription in which the scale-height of the
stellar distribution drops linearly from z_h=0.8 kpc to z_h=0.2 kpc over a
timescale t_c, remaining constant thereafter. We assume a linear-exponential
star-formation history, SFR ~ te^{-t/t_sf}. With a star-formation efficiency
timescale of 2 Gyr, an outflow mass-loading factor of 1.5, t_sf=3 Gyr, and
t_c=2.5 Gyr, the model reproduces the observed locus of inner disk stars in
[alpha/Fe]-[Fe/H] and the metallicity distribution functions (MDFs) measured by
H15 at |z|=0-0.5 kpc, 0.5-1 kpc, and 1-2 kpc. Substantial changes to model
parameters lead to disagreement with the H15 data; for example, models with
t_c=1 Gyr or t_sf=1 Gyr fail to match the observed MDF at high-|z| and low-|z|,
respectively. The inferred scale-height evolution, with z_h(t) dropping on a
timescale t_c ~ t_sf at large lookback times, favors upside-down formation over
dynamical heating of an initially thin stellar population as the primary
mechanism regulating disk thickness. The failure of our short-t_c models
suggests that any model in which thick disk formation is a discrete event will
not reproduce the continuous dependence of the MDF on |z| found by H15. Our
scenario for the evolution of the inner disk can be tested by future
measurements of the |z|-distribution and the age-metallicity distribution at
R=3-5 kpc.


title: Entwicklung eines Gasmoderators f\"ur Positronen

abstract:
  (Translated Title: Development of a positron gas moderator) In this work a
positron moderator that is based on inelastic positron scattering in nitrogen
gas has been developed and set-up. A positron beam enters a gas cell through a
small aperture. In the cell the positrons lose kinetic energy through
collisions with the nitrogen molecules. By means of an electric field the
positrons are then focused towards an exit where their kinetic energy is
analysed. During measurements at the NEPOMUC beam moderated positrons could be
observed.
  -----
  Im Rahmen dieser Diplomarbeit wurde das Konzept eines Moderators f\"ur
Positronen untersucht, welches auf der Abbremsung und dem Drift von Positronen
in gasf\"ormigem Stickstoff beruht. Dazu wurde ein Versuchsaufbau konstruiert,
aufgebaut und in Betrieb genommen. Ein Positronenstrahl wird durch eine kleine
Blende in eine Gaszelle eingekoppelt, dort durch St\"o{\ss}e mit den
Gasmolek\"ulen abgebremst, durch ein elektrisches Feld auf den Ausgang
fokussiert und dahinter analysiert. Durch ausf\"uhrliche Simulationen mit dem
Programm Simion 3D konnte das elektrische Feld im Inneren der Gaszelle
optimiert werden. Zur Untersuchung der Energie der moderierten Positronen wurde
ein Bremsspannungsanalysator angefertigt und am Ausgang der Zelle installiert.
Die Lokalisierung der im Versuchsaufbau zerstrahlenden Positronen wurde durch
zwei in Koinzidenz geschaltete Gammadetektoren erm\"oglicht, welche gegen\"uber
liegend l\"angs des Moderators auf Schienen verfahrbar waren.


title:
Time-Resolved Imaging of Negative Differential Resistance on the Atomic
  Scale

abstract:
  Negative differential resistance remains an attractive but elusive
functionality, so far only finding niche applications. Atom scale entities have
shown promising properties, but viability of device fabrication requires fuller
understanding of electron dynamics than has been possible to date. Using an
all-electronic time-resolved scanning tunneling microscopy technique and a
Green's function transport model, we study an isolated dangling bond on a
hydrogen terminated silicon surface. A robust negative differential resistance
feature is identified as a many body phenomenon related to occupation dependent
electron capture by a single atomic level. We measure all the time constants
involved in this process and present atomically resolved, nanosecond timescale
images to simultaneously capture the spatial and temporal variation of the
observed feature.


title:
A new scheme based on the Hermite expansion to construct lattice
  Boltzmann models associated with arbitrary specific heat ratio

abstract:
  A new lattice Boltzmann scheme associated with flexible specific heat ratio
is proposed. The new free degree is introduced via the internal energy
associated with the internal structure. The evolution equation of the
distribution function is reduced to two evolution equations. One is connected
to the density and velocity, the other is of the energy. A two-dimensional
lattice Boltzmann model and a three-dimensional lattice Boltzmann model are
derived via the Hermite expansion. The two lattice Boltzmann models are applied
to simulating the shock tube of one dimension. Good agreement between the
numerical results and the analytical solutions are obtained.


title: Sharp bounds for the cubic Parsell-Vinogradov system in two dimensions

abstract:
  We prove a sharp decoupling for a certain two dimensional surface in R^9. As
an application, we obtain the full range of expected estimates for the cubic
Parsell-Vinogradov system in two dimensions.


title: A New Parallelization Method for K-means

abstract:
  K-means is a popular clustering method used in data mining area. To work with
large datasets, researchers propose PKMeans, which is a parallel k-means on
MapReduce. However, the existing k-means parallelization methods including
PKMeans have many limitations. PKMeans can't finish all its iterations in one
MapReduce job, so it has to repeat cascading MapReduce jobs in a loop until
convergence. On the most popular MapReduce platform, Hadoop, every MapReduce
job introduces significant I/O overheads and extra execution time at stages of
job start-up and shuffling. Even worse, it has been proved that in the worst
case, k-means needs $2^{{\Omega}(n)}$ MapReduce jobs to converge, where n is
the number of data instances, which means huge overheads for large datasets.
Additionally, in PKMeans, at most one reducer can be assigned to and update
each centroid, so PKMeans can only make use of limited number of parallel
reducers. In this paper, we propose an improved parallel method for k-means,
IPKMeans, which has a parallel preprocessing stage using k-d tree and can
finish k-means in one single MapReduce job with much more reducers working in
parallel and lower I/O overheads than PKMeans and has a fast post-processing
stage generating the final result. In our method, both k-d tree and the new
improved parallel k-means are implemented using MapReduce and tested on Hadoop.
Our experiments show that with same dataset and initial centroids, our method
has up to 2/3 lower I/O overheads and consumes less amount of time than PKMeans
to get a very close clustering result.


title: Asymptotic behaviour of a random walk killed on a finite set

abstract:
  We study asymptotic behavior, for large time $n$, of the transition
probability of a two-dimensional random walk killed when entering into a
non-empty finite subset $A$. We show that it behaves like $4 \tilde u_A(x)
\tilde u_{-A}(-y) (\lg n)^{-2} p^n(y- x)$ for large $n$, uniformly in the
parabolic regime $|x|\vee |y| =O(\sqrt n)$, where $p^n(y-x)$ is the transition
kernel of the random walk (without killing) and $\tilde u_A$ is the unique
harmonic function in the 'exterior of $A$' satisfying the boundary condition
$\tilde u_A(x) \sim \lg |x|$ at infinity.


title: Five dimensions of reasoning in the wild

abstract:
  Reasoning does not work well when done in isolation from its significance,
both to the needs and interests of an agent and with respect to the wider
world. Moreover, those issues may best be handled with a new sort of data
structure that goes beyond the knowledge base and incorporates aspects of
perceptual knowledge and even more, in which a kind of anticipatory action may
be key.


title:
Characterizing Bipartite Graphs which Admit k-NU Polymorphisms via
  Absolute Retracts

abstract:
  We first introduce the class of bipartite absolute retracts with respect to
tree obstructions with at most $k$ leaves. Then, using the theory of
homomorphism duality, we show that this class of absolute retracts coincides
exactly with the bipartite graphs which admit a $(k+1)$-ary near-unanimity (NU)
polymorphism. This result mirrors the case for reflexive graphs and generalizes
a known result for bipartite graphs admitting a $3$-NU polymorphism.


title:
Bijectivity and trapping regions for complex continued fraction
  transformation

abstract:
  This paper provides some preliminary results on the dynamics of certain
complex continued fractions. After establishing some general number theoretic
results, we explore the dynamics of the natural extension map associated to a
specific complex continued fraction algorithm (the "diamond" algorithm). We
prove that this map has a bijectivity domain that is a subset of a trapping
region for the map and, moreover, that both these sets have a "finite product
structure" arising from a finite partition specific to the particular
algorithm.


title:
Metal-Insulator Transition and Pseudogap in
  Bi$_{1.76}$Pb$_{0.35}$Sr$_{1.89}$CuO$_{6+\delta}$ High-$T_c$ Cuprates

abstract:
  It is inferred from bulk-sensitive muon Knight shift measurement for a
Bi$_{1.76}$Pb$_{0.35}$Sr$_{1.89}$CuO$_{6+\delta}$ single-layer cuprate that
metal-insulator (MI) transition (in the low temperature limit, $T\rightarrow0$)
occurs at the critical hole concentration $p=p_{\rm MI}=0.09(1)$, where the
electronic density of states (DOS) at the Fermi level is reduced to zero by the
pseudogap irrespective of the N\'eel order or spin glass magnetism.
Superconductivity also appears for $p>p_{\rm MI}$, suggesting that this feature
is controlled by the MI transition. More interestingly, the magnitude of the
DOS reduction induced by the pseudogap remains unchanged over a wide doping
range ($0.1\le p\le0.2$), indicating that the pseudogap remains as a hallmark
of the MI transition for $p>p_{\rm MI}$.


title: Hausdorff closed limits and rigidity in Lorentzian geometry

abstract:
  We begin with a basic exploration of the (point-set topological) notion of
Hausdorff closed limits in the spacetime setting. Specifically, we show that
this notion of limit is well suited to sequences of achronal sets, and use this
to generalize the `achronal limits' introduced in [12]. This, in turn, allows
for a broad generalization of the notion of Lorentzian horosphere introduced in
[12]. We prove a new rigidity result for such horospheres, which in a sense
encodes various spacetime splitting results, including the basic Lorentzian
splitting theorem. We use this to give a partial proof of the Bartnik splitting
conjecture, under a new condition involving past and future Cauchy horospheres,
which is weaker than those considered in [10] and [12]. We close with some
observations on spacetimes with spacelike causal boundary, including a rigidity
result in the positive cosmological constant case.


title: Meissner Polyhedra

abstract:
  In this paper we develop a concrete way to construct bodies of constant width
in dimension three. They are constructed from special embeddings of self-dual
graphs.


title:
Design considerations of high-performance InGaAs/InP single-photon
  avalanche diodes for quantum key distribution

abstract:
  InGaAs/InP single-photon avalanche diodes (SPADs) are widely used in
practical applications requiring near-infrared photon counting such as quantum
key distribution (QKD). Photon detection efficiency and dark count rate are the
intrinsic parameters of InGaAs/InP SPADs, due to the fact that their
performances cannot be improved using different quenching electronics given the
same operation conditions. After modeling these parameters and developing a
simulation platform for InGaAs/InP SPADs, we investigate the semiconductor
structure design and optimization. The parameters of photon detection
efficiency and dark count rate highly depend on the variables of absorption
layer thickness, multiplication layer thickness, excess bias voltage and
temperature. By evaluating the decoy-state QKD performance, the variables for
SPAD design and operation can be globally optimized. Such optimization from the
perspective of specific applications can provide an effective approach to
design high-performance InGaAs/InP SPADs.


title:
Modeling of photon and pair production due to quantum electrodynamics
  effects in particle-in-cell simulation

abstract:
  We develop the particle-in-cell (PIC) code KLAPS to include the photon
generation via the Compton scattering and electron-positron creation via the
Breit-Wheeler process due to quantum electrodynamics (QED) effects. We compare
two sets of existing formulas for the photon generation and different Monte
Carlo algorithms. Then we benchmark the PIC simulation results.


title:
Capillary fracture of ultrasoft gels: heterogeneity and delayed
  nucleation

abstract:
  A droplet of surfactant spreading on an ultrasoft ($E \lesssim 100$ Pa) gel
substrate will produce capillary fractures at the gel surface; these fractures
originate at the contact-line and propagate outwards in a starburst pattern.
There is an inherent variability in both the number of fractures formed and the
time delay before fractures form. In the regime where single fractures form, we
observe a Weibull-like distribution of delay times, consistent with a
thermally-activated process. The shape parameter is close to 1 for softer gels
(a Poisson process), and larger for stiffer gels (indicative of aging). For
single fractures, the characteristic delay time is primarily set by the
elastocapillary length of the system, calculated from the differential in
surface tension between the droplet and the substrate, rather than the elastic
modulus as for stiffer systems. For multiple fractures, all fractures appear
simultaneously and long delay times are suppressed. The delay time distribution
provides a new technique for probing the energy landscape and fracture
toughness of ultrasoft materials.


title:
Vibration Mitigation in Partially Liquid-Filled Vessel using Passive
  Energy Absorbers

abstract:
  This paper treats possible solutions for vibration mitigation in
reduced-order model of partially-filled liquid tank under impulsive forcing.
Such excitation may lead to hydraulic impacts applied on the tank inner walls.
Finite stiffness of the tank walls is taken into account. We explore both
linear (Tuned Mass Damper) and nonlinear (Nonlinear Energy Sink) passive
vibration absorbers; mitigation performances are examined numerically. The
liquid sloshing mass is modeled by equivalent massspring-dashpot system, which
can both perform small-amplitude linear oscillations and impact the vessel
walls. We use parameters of the equivalent mass-spring-dashpot system for
well-explored case of cylindrical tanks. The hydraulic impacts are modeled by
high-power potential and dissipation functions. Critical location in the tank
structure is determined and expression of the corresponding local mechanical
stress is derived. We use finite-elemet approach to assess the natural
frequencies for specific system parameters and to figure out possibilities for
internal resonances. Numerical evaluation criteria are suggested to determine
the energy absorption performance.


title:
Thermal stability and irreversibility of skyrmion-lattice phases in
  Cu$_2$OSeO$_3$

abstract:
  Small angle neutron scattering measurements have been performed to study the
thermodynamic stability of skyrmion-lattice phases in Cu$_2$OSeO$_3$. We found
that the two distinct skyrmion-lattice phases [SkX(1) and SkX(2) phases] can be
stabilized through different thermal histories; by cooling from the
paramagnetic phase under finite magnetic field, the SkX(2) phase is selected.
On the other hand, the 30$^{\circ}$-rotated SkX(1) phase becomes dominant by
heating the sample from the ordered conical phase under finite field. This
difference in stabilization is surprisingly similar to the irreversibility
observed in spin glasses. The zero-field cooling results in the co-existence of
the two phases. It is further found that once one of the skyrmion-lattice
phases is formed, it is hardly destabilized. This indicates unusual thermal
stability of the two skyrmion-lattice phases originating from an unexpectedly
large energy barrier between them.


title:
Decorated defect condensate, a window to unconventional quantum phase
  transitions in Weyl semimetals

abstract:
  We investigate the unconventional quantum phase transitions in Weyl
semimetals. The emergent boson fields, coupling with the Weyl fermion
bilinears, contain a Wess-Zumino-Witten term or topological $\Theta$ term
inherited from the momentum space monopoles carried by Weyl points. Three types
of unconventional quantum critical points will be studied in order: (1) The
transition between two distinct symmetry breaking phases whose criticality is
beyond Landau's paradigm. (2) The transition between a symmetry breaking state
to a topological ordered state. (3) The transition between $3d$ topological
order phase to trivial disordered phase whose criticality could be traced back
to a $Z_2$ symmetry breaking transition in $4d$. The essence of these
unconventional critical points lies in the fact that the topological defect of
an order parameter carries either a nontrivial quantum number or a topological
term so the condensation of the defects would either break some symmetry or
give rise to a topological order phase with nontrivial braiding statistics.


title: Strict Local Martingales via Filtration Enlargement

abstract:
  A strict local martingale is a local martingale that is not a martingale. We
investigate how such a process might arise from a true martingale as a result
of an enlargement of the filtration. We study and implement a particular type
of enlargement, initial expansion of filtration, for various stochastic
differential equations and provide sufficient conditions in each of these cases
such that initial expansion can create a strict local martingale under an
equivalent probability measure. Such situations arise in the theory of
Mathematical Finance.


title: Ultrasonic elastic responses in monopole lattice

abstract:
  The latest experimental advances have extended the scenario of coupling
mechanical degrees of freedom in chiral magnets (MnSi/MnGe) to the
topologically nontrivial skyrmion crystal and even monopole lattices. Equipped
with a spin-wave theory highlighting the topological features, we devise an
interacting model for acoustic phonons and magnons to explain the experimental
findings in a monopole lattice with a topological phase transition, i.e.,
annihilation of monopole-antimonopole pairs. We reproduce the anisotropic
magnetoelastic modulations of elastic moduli: drastic ultrasonic softening
around the phase transition and a multi-peak-and-trench fine structure for
sound waves parallel and orthogonal to the magnetic field, respectively.
Comparison with experiments indicates that the magnetoelastic coupling induced
by Dzyaloshinskii-Moriya interaction is comparable to that induced by the
exchange interaction. Other possibilities such as elastic hardening are also
predicted. The study implies that the monopole defects and their motion in MnGe
play a crucial role.


title:
A Complete Solution to Optimal Control and Stabilization for Mean-field
  Systems: Part I, Discrete-time Case

abstract:
  Different from most of the previous works, this paper provides a thorough
solution to the fundamental problems of linear-quadratic (LQ) control and
stabilization for discrete-time mean-field systems under basic assumptions.
Firstly, the sufficient and necessary condition for the solvability of
mean-field LQ control problem is firstly presented in analytic expression based
on the maximum principle developed in this paper, which is compared with the
results obtained in literatures where only operator type solvability conditions
were given. The optimal controller is given in terms of a coupled Riccati
equation which is derived from the solution to forward and backward stochastic
difference equation (FBSDE). Secondly, the sufficient and necessary
stabilization conditions are explored. It is shown that, under exactly
observability assumption, the mean-field system is stabilizable in mean square
sense if and only if a coupled algebraic Riccati equation (ARE) has a unique
solution $P$ and $\bar{P}$ satisfying $P>0$ and $P+\bar{P}>0$. Furthermore,
under the exactly detectability assumption, which is a weaker assumption than
exactly observability, we show that the mean-field system is stabilizable in
mean square sense if and only if the coupled ARE has a unique solution $P$ and
$\bar{P}$ satisfying $P\geq 0$ and $P+\bar{P}\geq 0$. The key techniques
adopted in this paper are the maximum principle and the solution to the FBSDE
obtained in this paper. The derived results in this paper forms the basis to
solve the mean-field control problem for continuous-time systems and other
related problems.


title: Holographic s-wave and p-wave Josephson junction with backreaction

abstract:
  In this paper, we study the holographic models of s-wave and p-wave
Josephoson junction away from probe limit in (3+1)-dimensional spacetime,
respectively. With the backreaction of the matter, we obtained the anisotropic
black hole solution with the condensation of matter fields. We observe that the
critical temperature of Josephoson junction decreases with increasing
backreaction. In addition to this, the tunneling current and condenstion of
Josephoson junction become smaller as backreaction grows larger, but the
relationship between current and phase difference still holds for sine
function. Moreover, condenstion of Josephoson junction deceases with increasing
width of junction exponentially.


title:
Transport properties in the photonic super-honeycomb lattice - a hybrid
  fermionic and bosonic system

abstract:
  We report on transport properties of the super-honeycomb lattice, the band
structure of which possesses a flat band and Dirac cones, according to the
tight-binding approximation. This super-honeycomb model combines the honeycomb
lattice and the Lieb lattice and displays the properties of both. The
super-honeycomb lattice also represents a hybrid fermionic and bosonic system,
which is rarely seen in nature. By choosing the phases of input beams properly,
the flat-band mode of the super-honeycomb will be excited and the input beams
will exhibit strong localization during propagation. On the other hand, if the
modes of Dirac cones of the super-honeycomb lattice are excited, one will
observe conical diffraction. Furthermore, if the input beam is properly chosen
to excite a sublattice of the super-honeycomb lattice and the modes of Dirac
cones with different pseudospins, e.g., the three-beam interference pattern,
the pseudospin-mediated vortices will be observed.


title:
Accelerated Alternating Direction Method of Multipliers: an Optimal
  $O(1/K)$ Nonergodic Analysis

abstract:
  The Alternating Direction Method of Multipliers (ADMM) is widely used for
linearly constrained convex problems. It is proven to have an $o(1/\sqrt{K})$
nonergodic convergence rate and a faster $O(1/K)$ ergodic rate after ergodic
averaging, which may destroy the sparsity and low-rankness in sparse and
low-rank learning, where $K$ is the number of iterations. In this paper, we
modify the accelerated ADMM proposed in [Y. Ouyang, Y. Chen, G. Lan, and E.
Pasiliao, An Accelerated Linearized Alternating Direction Method of
Multipliers, SIAM J. on Imaging Sciences, 2015, 1588-1623] and give an $O(1/K)$
nonergodic convergence rate analysis, which satisfies $|F(x^K)-F(x^*)|\leq
O(1/K)$, $\|Ax^K-b\|\leq O(1/K)$ and $x^K$ has a more favorable sparseness and
low-rankness than the ergodic result. As far as we know, this is the first
$O(1/K)$ nonergodic convergent ADMM type method for general linearly
constrained convex problems. Moreover, we show that the lower complexity bound
of ADMM type methods for the separable linearly constrained nonsmooth convex
problems is $O(1/K)$, which means that our method is optimal.


title:
Generalized Shock Model Based On The Frequency of Shocks: A Simple
  Approach

abstract:
  In a $\delta-$shock model, a system subject to randomly occurring shocks, the
system fails when the time between two successive shocks lies below a threshold
$\delta$. In this note, we study the generalization of this model where such
$\delta-$shocks are accumulated and the system fails on the occurrence of
$k^{th}$ such a $\delta-$shock. The probability distribution of the system
failure time and the statistical characteristics are explicitly obtained.
Normal approximation to the failure time distribution is proposed.


title: Segmenting a Surface Mesh into Pants Using Morse Theory

abstract:
  A pair of pants is a genus zero orientable surface with three boundary
components. A pants decomposition of a surface is a finite collection of
unordered pairwise disjoint simple closed curves embedded in the surface that
decompose the surface into pants. In this paper we present two Morse theory
based algorithms for pants decomposition of a surface mesh. Both algorithms
operates on a choice of an appropriate Morse function on the surface. The first
algorithm uses this Morse function to identify handles that are glued
systematically to obtain a pant decomposition. The second algorithm uses the
Reeb graph of the Morse function to obtain a pant decomposition. Both
algorithms work for surfaces with or without boundaries. Our preliminary
implementation of the two algorithms shows that both algorithms run in much
less time than an existing state-of-the-art method, and the Reeb graph based
algorithm achieves the best time efficiency. Finally, we demonstrate the
robustness of our algorithms against noise.


title:
An experiment of X-ray photon-photon elastic scattering with a Laue-case
  beam collider

abstract:
  We report a search for photon-photon elastic scattering in vacuum in the
X-ray region at an energy in the center of mass system of \omega_{cms} =6.5 keV
for which the QED cross section is \sigma_{QED} =2.5 \times 10^{-47} m^2. An
X-ray beam provided by the SACLA X-ray Free Electron Laser is split and the two
beamlets are made to collide at right angle, with a total integrated luminosity
of (1.24 \pm 0.08) \times 10^{28} m^{-2}. No signal X rays from the elastic
scattering that satisfy the correlation between energy and scattering angle
were detected. We obtain a 95% C.L. upper limit for the scattering cross
section of 1.9 \times 10^{-27} m^2 at \omega_{cms}=6.5 keV. The upper limit is
the lowest upper limit obtained so far by keV experiments.


title: Michelson interferometer for measuring temperature

abstract:
  We investigate that temperature can be measured by a modified Michelson
interferometer, where at least one reflected mirror is replaced by a
thermalized sample. Both of two mirrors replaced by the corresponding two
thermalized samples can help to approximatively improve the resolution of
temperature up to twice than only one mirror replaced by a thermalized sample.
For further improving the precision, a nonlinear medium can be employed. The
Michelson interferometer is embedded in a gas displaying Kerr nonlinearity. We
obtain the analytical equations and numerically calculate the precision with
parameters within the reach of current technology, proving that the precision
of temperature can be greatly enhanced by using a nonlinear medium. Our results
show that one can create an accurate thermometer by measuring the photons in
the Michelson interferometer, with no need for directly measuring the
population of thermalized sample.


title: Photo-acoustic tomography in a rotating measurement setting

abstract:
  Photo-acoustic tomography (PAT) aims to leverage the photo-acoustic coupling
between optical absorption of light sources and ultrasound (US) emission to
obtain high contrast reconstructions of optical parameters with the high
resolution of sonic waves. Quantitative PAT often involves a two-step
procedure: first the map of sonic emission is reconstructed from US boundary
measurements; and second optical properties of biological tissues are
evaluated. We consider here a practical measurement setting in which such a
separation does not apply. We assume that the optical source and an array of
ultrasonic transducers are mounted on a rotating frame (in two or three
dimensions) so that the light source rotates at the same time as the US
measurements are acquired. As a consequence, we no longer have the option to
reconstruct a map of sonic emission corresponding to a given optical
illumination. We propose here a framework where the two steps are combined into
one and an absorption map is directly reconstructed from the available
ultrasound measurements.


title: Equivariant Hilbert Series of Monomial Orbits

abstract:
  The equivariant Hilbert series of an ideal generated by an orbit of a
monomial under the action of the monoid $\mbox{Inc}(\mathbb{N})$ of strictly
increasing functions is determined. This is used to find the dimension and
degree of such an ideal. The result also suggests that the description of the
denominator of an equivariant Hilbert series of an arbitrary
$\mbox{Inc}(\mathbb{N})$-invariant ideal as given by Nagel and R\"omer is
rather efficient.