title: Unstable `black branes' from scaled membranes at large $D$

abstract:
  It has recently been demonstrated that the dynamics of black holes at large
$D$ can be recast as a set of non gravitational membrane equations. These
membrane equations admit a simple static solution with shape $S^{D-p-2} \times
R^{p,1}$. In this note we study the equations for small fluctuations about this
solution in a limit in which amplitude and length scale of the fluctuations are
simultaneously scaled to zero as $D$ is taken to infinity. We demonstrate that
the resultant nonlinear equations, which capture the Gregory- Laflamme
instability and its end point, exactly agree with the effective dynamical
`black brane' equations of Emparan Suzuki and Tanabe. Our results thus identify
the `black brane' equations as a special limit of the membrane equations and so
unify these approaches to large $D$ black hole dynamics.


title:
MApping the Most Massive Overdensities (MAMMOTH) II -- Discovery of an
  Extremely Massive Overdensity BOSS1441 at $z=2.32$

abstract:
  Cosmological simulations suggest a strong correlation between high
optical-depth Ly$\alpha$ absorbers, which arise from the intergalactic medium
(IGM), and 3-D mass overdensities on scales of $10-30$ $h^{-1}$ comoving Mpc.
By examining the absorption spectra of $\sim$ 80,000 QSO sight-lines over a
volume of 0.1 Gpc$^3$ in the Sloan Digital Sky Survey III (SDSS-III), we have
identified an extreme overdensity, BOSS1441, which contains a rare group of
strong Ly$\alpha$ absorbers at $z=2.32\pm 0.02$. This absorber group is
associated with six QSOs at the same redshift on a 30 comoving Mpc scale. Using
Mayall/MOSAIC narrowband and broadband imaging, we detect Ly$\alpha$ emitters
(LAEs) down to $0.7\times L_{\rm{Ly\alpha}}^*$, and reveal a large-scale
structure of Ly$\alpha$ emitters (LAEs) in this field. Our follow-up Large
Binocular Telescope (LBT) observations have spectroscopically confirmed 19
galaxies in the density peak. We show that BOSS1441 has an LAE overdensity of
$10.8\pm 2.6$ on a 15 comoving Mpc scale which could collapse to a massive
cluster with $M\gtrsim10^{15}$ M$_\odot$ at $z\sim0$. This overdensity is among
the most massive large-scale structures at $z\sim2$ discovered to date.


title:
The RAVE-on catalog of stellar atmospheric parameters and chemical
  abundances for chemo-dynamic studies in the Gaia era

abstract:
  The orbits, atmospheric parameters, chemical abundances, and ages of
individual stars in the Milky Way provide the most comprehensive illustration
of galaxy formation available. The Tycho-Gaia Astrometric Solution (TGAS) will
deliver astrometric parameters for the largest ever sample of Milky Way stars,
though its full potential cannot be realized without the addition of
complementary spectroscopy. Among existing spectroscopic surveys, the RAdial
Velocity Experiment (RAVE) has the largest overlap with TGAS ($\gtrsim$200,000
stars). We present a data-driven re-analysis of 520,781 RAVE spectra using The
Cannon. For red giants, we build our model using high-fidelity APOGEE stellar
parameters and abundances for stars that overlap with RAVE. For main-sequence
and sub-giant stars, our model uses stellar parameters from the K2/EPIC. We
derive and validate effective temperature $T_{\rm eff}$, surface gravity
$\log{g}$, and chemical abundances of up to seven elements (O, Mg, Al, Si, Ca,
Fe, Ni). We report a total of 1,685,851 elemental abundances with a typical
precision of 0.07 dex, a substantial improvement over previous RAVE data
releases. The synthesis of RAVE-on and TGAS is the most powerful data set for
chemo-dynamic analyses of the Milky Way ever produced.


title: Chemical Diversity in the Ultra-faint Dwarf Galaxy Tucana II

abstract:
  We present the first detailed chemical abundance study of the ultra-faint
dwarf galaxy Tucana II based on high-resolution Magellan/MIKE spectra of four
red giant stars. The metallicity of these stars ranges from [Fe/H] = -3.2 to
-2.6, and all stars are low in neutron-capture abundances ([Sr/Fe] and [Ba/Fe]
< -1). However, a number of anomalous chemical signatures are present. Three
stars are carbon-enhanced, including the most metal-rich star. This star
([Fe/H]=-2.6) shows [Na,$\alpha$,Sc/Fe] < 0, suggesting an extended star
formation history with contributions from AGB stars and Type Ia supernovae. The
other carbon-enhanced stars have [Fe/H] < -3 and may be consistent with
enrichment by faint supernovae, if such supernovae can produce neutron-capture
elements. A fourth star with [Fe/H] = -3 is carbon-normal, and exhibits
distinct light element abundance ratios from the carbon-enhanced stars. The
carbon-normal star implies that at least two distinct nucleosynthesis sources,
both possibly associated with Population III stars, contributed to the early
chemical enrichment of this galaxy. Despite its very low luminosity, Tucana II
shows a diversity of chemical signatures that preclude it from being a simple
"one-shot" first galaxy, but still provide a window to star and galaxy
formation in the early universe.


title: Minimal motor for powering particle motion from spin imbalance

abstract:
  We introduce a minimalistic quantum motor for coupled energy and particle
transport. The system is composed of two spins, each coupled to a different
bath and to a particle which can move on a ring consisting of three sites. We
show that the energy flowing from the baths to the system can be partially
converted to perform work against an external driving, even in the presence of
moderate dissipation. We also analytically demonstrate the necessity of
coupling between the spins. We suggest an experimental realization of our model
using trapped ions or quantum dots.


title: The origin of the eccentricity of the hot Jupiter in CI Tau

abstract:
  Following the recent discovery of the first radial velocity planet in a star
still possessing a protoplanetary disc (CI Tau), we examine the origin of the
planet's eccentricity (e $\sim 0.3$). We show through long timescale ($10^5$
orbits) simulations that the planetary eccentricity can be pumped by the disc,
even when its local surface density is well below the threshold previously
derived from short timescale integrations. We show that the disc may be able to
excite the planet's orbital eccentricity in $<$ a Myr for the system parameters
of CI Tau. We also perform two planet scattering experiments and show that
alternatively the observed planet may plausibly have acquired its eccentricity
through dynamical scattering of a migrating lower mass planet, which has either
been ejected from the system or swallowed by the central star. In the latter
case the present location and eccentricity of the observed planet can be
recovered if it was previously stalled within the disc's magnetospheric cavity.


title:
Reorienting MHD Colliding Flows: A Shock Physics Mechanism for
  Generating Filaments Normal to Magnetic Fields

abstract:
  We present numerical simulations of reorienting oblique shocks that form in
the collision layer between magnetized colliding flows. Reorientation aligns
parsec-scale post-shock filaments normal to the background magnetic field. We
find that reorientation begins with pressure gradients between the collision
region and the ambient medium. This drives a lateral expansion of post-shock
gas, which reorients the growing filament from the outside-in (i.e. from the
flow-ambient boundary, toward the colliding flows axis). The final structures
of our simulations resemble polarization observations of filaments in Taurus
and Serpens South, as well as the integral-shaped filament in Orion A. Given
the ubiquity of colliding flows in the interstellar medium, shock reorientation
may be relevant to the formation of filaments normal to magnetic fields.


title: Predicted Information Content of Gaia-Hipparcos

abstract:
  The Gaia-Tycho release, scheduled for 14 September, is forecast to yield
parallax errors of $\sigma(\pi)\sim 300\,\mu$as for about 2 million Tycho
stars. We show analytically that the actual performance should be $$
\sigma(\pi) = {\rm max}(\sigma_{1991}/96,20\,\mu{\rm as}) $$ where
$\sigma_{1991}$ is the positional error from the Hipparcos mission. For typical
Tycho stars, $\sigma_{1991}\sim 30\,$mas, so this reproduces the usual claims.
However, for the 100,000 star Hipparcos subset of this sample, $\sigma_{1991}$
is a factor 15 or more smaller. These much lower Hipparcos positional errors
apply even to stars at the Hipparcos-Tycho limit, $V\sim 12$. This is
especially important for RR Lyrae stars, as well as other special classes, that
were systematically included in the Hipparcos catalog down to this limit
because of their exceptional scientific importance. This predicted performance
will provide an early test of the Gaia algorithms.


title:
MUSE Deep-Fields: The Lya Luminosity Function in the Hubble Deep Field
  South at 2.91 < z < 6.64

abstract:
  We present the first estimate of the Ly{\alpha} luminosity function using
blind spectroscopy from the Multi Unit Spectroscopic Explorer, MUSE, in the
Hubble Deep Field South. Using automatic source-detection software, we assemble
a homogeneously-detected sample of 59 Ly{\alpha} emitters covering a flux range
of -18.0 < log10 (F) < -16.3 (erg s^-1 cm^-2), corresponding to luminosities of
41.4 < log10 (L) < 42.8 (erg s^-1). As recent studies have shown, Ly{\alpha}
fluxes can be underestimated by a factor of two or more via traditional
methods, and so we undertake a careful assessment of each object's Ly{\alpha}
flux using a curve-of-growth analysis to account for extended emission. We
describe our self-consistent method for determining the completeness of the
sample, and present an estimate of the global Ly{\alpha} luminosity function
between redshifts 2.91 < z < 6.64 using the 1/Vmax estimator. We find the
luminosity function is higher than many number densities reported in the
literature by a factor of 2 - 3, although our result is consistent at the
1{\sigma} level with most of these studies. Our observed luminosity function is
also in good agreement with predictions from semi-analytic models, and shows no
evidence for strong evolution between the high- and low-redshift halves of the
data. We demonstrate that one's approach to Ly{\alpha} flux estimation does
alter the observed luminosity function, and caution that accurate flux
assessments will be crucial in measurements of the faint end slope. This is a
pilot study for the Ly{\alpha} luminosity function in the MUSE deep-fields, to
be built on with data from the Hubble Ultra Deep Field which will increase the
size of our sample by almost a factor of 10.


title:
LOSS Revisited - I: Unraveling correlations between supernova rates and
  galaxy properties, as measured in a reanalysis of the Lick Observatory
  Supernova Search

abstract:
  Most types of supernovae (SNe) have yet to be connected with their progenitor
stellar systems. Here, we reanalyze the 10-year SN sample collected during
1998-2008 by the Lick Observatory Supernova Search (LOSS) in order to constrain
the progenitors of SNe Ia and stripped-envelope SNe (SE SNe, i.e., SNe~IIb, Ib,
Ic, and broad-lined Ic). We matched the LOSS galaxy sample with spectroscopy
from the Sloan Digital Sky Survey and measured SN rates as a function of galaxy
stellar mass, specific star formation rate, and oxygen abundance (metallicity).
We find significant correlations between the SN rates and all three galaxy
properties. The SN Ia correlations are consistent with other measurements, as
well as with our previous explanation of these measurements in the form of a
combination of the SN Ia delay-time distribution and the correlation between
galaxy mass and age. The ratio between the SE SN and SN II rates declines
significantly in low-mass galaxies. This rules out single stars as SE~SN
progenitors, and is consistent with predictions from binary-system progenitor
models. Using well-known galaxy scaling relations, any correlation between the
rates and one of the galaxy properties examined here can be expressed as a
correlation with the other two. These redundant correlations preclude us from
establishing causality - that is, from ascertaining which of the galaxy
properties (or their combination) is the physical driver for the difference
between the SE SN and SN II rates. We outline several methods that have the
potential to overcome this problem in future works.


title:
Revisiting the Lick Observatory Supernova Search Volume-Limited Sample:
  Updated Classifications and Revised Stripped-Envelope Supernova Fractions

abstract:
  We re-examine the classifications of supernovae (SNe) presented in the Lick
Observatory Supernova Search (LOSS) volume-limited sample with a focus on the
stripped-envelope SNe. The LOSS volume-limited sample, presented by Leaman et
al. (2011) and Li et al. (2011b), was calibrated to provide meaningful
measurements of SN rates in the local universe; the results presented therein
continue to be used for comparisons to theoretical and modeling efforts. Many
of the objects from the LOSS sample were originally classified based upon only
a small subset of the data now available, however, and recent studies have both
updated some subtype distinctions and improved our ability to perform robust
classications, especially for stripped-envelope SNe. We re-examine the
spectroscopic classifications of all events in the LOSS volume-limited sample
(180 SNe and SN impostors) and update them if necessary. We discuss the
populations of rare objects in our sample including broad-lined Type Ic SNe,
Ca-rich SNe, SN 1987A-like events (we identify SN 2005io as SN 1987A-like here
for the first time), and peculiar subtypes. The relative fractions of Type Ia
SNe, Type II SNe, and stripped-envelope SNe in the local universe are not
affected, but those of some subtypes are. Most significantly, after discussing
the often unclear boundary between SNe Ib and Ic when only noisy spectra are
available, we find a higher SN Ib fraction and a lower SN Ic fraction than
calculated by Li et al. (2011b): spectroscopically normal SNe Ib occur in the
local universe $1.7 \pm 0.9$ times more often than do normal SNe Ic.


title:
LOSS Revisited - II: The relative rates of different types of supernovae
  vary between low- and high-mass galaxies

abstract:
  In Paper I of this series, we showed that the ratio between stripped-envelope
(SE) supernova (SN) and Type II SN rates reveals a significant SE SN deficiency
in galaxies with stellar masses $\lesssim 10^{10}~{\rm M}_\odot$. Here, we test
this result by splitting the volume-limited subsample of the Lick Observatory
Supernova Search (LOSS) SN sample into low- and high-mass galaxies and
comparing the relative rates of various SN types found in them. The LOSS
volume-limited sample contains 180 SNe and SN impostors and is complete for SNe
Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients
were recently reclassified by us in Shivvers et al. (2017). We find that the
relative rates of some types of SNe differ between low- and high-mass galaxies:
SNe Ib and Ic are underrepresented by a factor of ~3 in low-mass galaxies.
These galaxies also contain the only examples of SN 1987A-like SNe in the
sample and host about 9 times as many SN impostors. Normal SNe Ia seem to be
~30\% more common in low-mass galaxies, making these galaxies better sources
for homogeneous SN Ia cosmology samples. The relative rates of SNe IIb are
consistent in both low- and high-mass galaxies. The same is true for broad-line
SNe Ic, although our sample includes only two such objects. The results
presented here are in tension with a similar analysis from the Palomar
Transient Factory, especially as regards SNe IIb.


title:
The Effects of Physically Unrelated Near Neighbors on the Galaxy-Galaxy
  Lensing Signal

abstract:
  The effects of near neighbors on the galaxy-galaxy lensing signal are
investigated using a suite of Monte Carlo simulations. The redshifts,
luminosities, and relative coordinates for the simulated lenses were obtained
from a set of galaxies with known spectroscopic redshifts and known
luminosities. As expected, when all lenses are assigned a single, fixed
redshift, the mean tangential shear is identically equal to the excess surface
mass density, scaled by the critical surface mass density: $\gamma_T =
\Delta\Sigma \times \Sigma_c^{-1}$. When the lenses are assigned their observed
redshifts and $\Sigma_c$ is taken to be the critical surface mass density of
the central lens, the relationship $\gamma_T = \Delta\Sigma \times
\Sigma_c^{-1}$ is violated because $\gtrsim 90$% of the near neighbors are
located at redshifts significantly different from the central lenses. For a
given central lens, physically unrelated near neighbors give rise to a ratio of
$\gamma_T$ to $\Delta\Sigma \times \Sigma_c^{-1}$ that spans a wide range of
$\sim 0.5$ to $\sim 1.5$ at projected distances $r_p \sim 1$ Mpc. The magnitude
and sense of the discrepancy between $\gamma_T$ and $\Delta\Sigma \times
\Sigma_c^{-1}$ are functions of both $r_p$ and the velocity dispersions of the
central lenses, $\sigma_v$. At large $r_p$, the difference between $\gamma_T$
and $\Delta\Sigma \times \Sigma_c^{-1}$ is, on average, much greater for
low-$\sigma_v$ central lenses than it is for high-$\sigma_v$ central lenses.


title:
Density wave instabilities and surface state evolution in interacting
  Weyl semimetals

abstract:
  We investigate the interplay of many-body and band structure effects of
interacting Weyl semimetals (WSM). Attractive and repulsive Hubbard
interactions are studied within a model for a time-reversal-breaking WSM with
tetragonal symmetry, where we can approach the limit of weakly coupled planes
and coupled chains by varying the hopping amplitudes. Using a slab geometry, we
employ the variational cluster approach to describe the evolution of WSM Fermi
arc surface states as a function of interaction strength. We find spin and
charge density wave instabilities which can gap out Weyl nodes. We identify
scenarios where the bulk Weyl nodes are gapped while the Fermi arcs still
persist, hence realizing a quantum anomalous Hall state.


title:
Exact Growth of Entanglement and Dynamical Phase Transition in Global
  Fermionic Quench

abstract:
  Critical quantum quench of free Dirac fermions in an infinite system is
examined carefully. A much broader analysis, with more emphasis on free scalar
fields, has been done in hep-th/1512.0218. For specially prepared squeezed
states of the massive theory, quenched states obtained are Calabrese-Cardy(CC)
states and generalized Calabrese-Cardy(gCC) states with higher-spin charges.
Exact time dependence of correlators are computed showing thermalization
explicitly. We also calculate the exact monotonic growth of entanglement
entropy in CC states. In case of gCC states, for a particular charge, we show
that there is a dynamical phase transition from monotonic to non-monotonic
entanglement entropy growth when the effective chemical potential is increased
beyond a critical value.


title:
The Superluminous Transient ASASSN-15lh as a Tidal Disruption Event from
  a Kerr Black Hole

abstract:
  When a star passes within the tidal radius of a supermassive black hole, it
will be torn apart. For a star with the mass of the Sun ($M_\odot$) and a
non-spinning black hole with a mass $<10^8 M_\odot$, the tidal radius lies
outside the black hole event horizon and the disruption results in a luminous
flare. Here we report observations over a period of 10 months of a transient,
hitherto interpreted as a superluminous supernova. Our data show that the
transient rebrightened substantially in the ultraviolet and that the spectrum
went through three different spectroscopic phases without ever becoming
nebular. Our observations are more consistent with a tidal disruption event
than a superluminous supernova because of the temperature evolution, the
presence of highly ionised CNO gas in the line of sight and our improved
localisation of the transient in the nucleus of a passive galaxy, where the
presence of massive stars is highly unlikely. While the supermassive black hole
has a mass $> 10^8 M_\odot$, a star with the same mass as the Sun could be
disrupted outside the event horizon if the black hole were spinning rapidly.
The rapid spin and high black hole mass can explain the high luminosity of this
event.


title:
Algorithmic construction of the subdifferential from directional
  derivatives

abstract:
  The subdifferential of a function is a generalization for nonsmooth functions
of the concept of gradient. It is frequently used in variational analysis,
particularly in the context of nonsmooth optimization. The present work
proposes algorithms to reconstruct a polyhedral subdifferential of a function
from the computation of finitely many directional derivatives. We provide upper
bounds on the required number of directional derivatives when the space is
$\R^1$ and $\R^2$, as well as in $\R^n$ where subdifferential is known to
possess at most three vertices.


title:
Behavior of aqueous Tetrabutylammonium bromide - a combined approach of
  microscopic simulation and neutron scattering

abstract:
  Aqueous solution of tetrabutylammonium bromide is studied by quasi-elastic
neutron scattering, to give information on the dynamic modes involving the ions
present. Using a careful combination of two techniques, time-of-flight (TOF)
and neutron spin echo (NSE), we de- couple the dynamic information in both the
coherently and incoherently scattered signal from this system. We take
advantage of the different intensity ratio of the two signals, as detected by
each of the techniques, to achieve this decoupling. By using heavy water as the
sol- vent, the tetrabutylammonium cation is the only hydrogen-containing
species in the system and gives rise to a significant incoherent scattered
intensity. The dynamic analysis of the incoherent signal (measured by TOF)
leads to a translational diffusion coefficient of the cation as that is in good
agreement with previous NMR, neutron scattering and tracer diffusion
measurements. The dynamic analysis of the coherent signal observed at
wave-vectors < 0.6 angstrom^(-1) (measured by NSE) leads to a significantly
slower diffusive mode, by a factor of 2. This study explains that apparent
difference and the reasons for that.


title:
Effect of lithographically-induced strain relaxation on the magnetic
  domain configuration in microfabricated epitaxially grown Fe81Ga19

abstract:
  We investigate the role of lithographically-induced strain relaxation in a
micron-scaled device fabricated from epitaxial thin films of the
magnetostrictive alloy Fe81Ga19. The strain relaxation due to lithographic
patterning induces a magnetic anisotropy that competes with the
magnetocrystalline and shape induced anisotropies to play a crucial role in
stabilising a flux-closing domain pattern. We use magnetic imaging,
micromagnetic calculations and linear elastic modelling to investigate a region
close to the edges of an etched structure. This highly-strained edge region has
a significant influence on the magnetic domain configuration due to an induced
magnetic anisotropy resulting from the inverse magnetostriction effect. We
investigate the competition between the strain-induced and shape-induced
anisotropy energies, and the resultant stable domain configurations, as the
width of the bar is reduced to the nanoscale range. Understanding this
behaviour will be important when designing hybrid magneto-electric spintronic
devices based on highly magnetostrictive materials.


title: An architecture for ethical robots

abstract:
  Robots are becoming ever more autonomous. This expanding ability to take
unsupervised decisions renders it imperative that mechanisms are in place to
guarantee the safety of behaviours executed by the robot. Moreover, smart
autonomous robots should be more than safe; they should also be explicitly
ethical -- able to both choose and justify actions that prevent harm. Indeed,
as the cognitive, perceptual and motor capabilities of robots expand, they will
be expected to have an improved capacity for making moral judgements. We
present a control architecture that supplements existing robot controllers.
This so-called Ethical Layer ensures robots behave according to a predetermined
set of ethical rules by predicting the outcomes of possible actions and
evaluating the predicted outcomes against those rules. To validate the proposed
architecture, we implement it on a humanoid robot so that it behaves according
to Asimov's laws of robotics. In a series of four experiments, using a second
humanoid robot as a proxy for the human, we demonstrate that the proposed
Ethical Layer enables the robot to prevent the human from coming to harm.


title: Image Denoising Via Collaborative Support-Agnostic Recovery

abstract:
  In this paper, we propose a novel image denoising algorithm using
collaborative support-agnostic sparse reconstruction. An observed image is
first divided into patches. Similarly structured patches are grouped together
to be utilized for collaborative processing. In the proposed collaborative
schemes, similar patches are assumed to share the same support taps. For sparse
reconstruction, the likelihood of a tap being active in a patch is computed and
refined through a collaboration process with other similar patches in the same
group. This provides very good patch support estimation, hence enhancing the
quality of image restoration. Performance comparisons with state-of-the-art
algorithms, in terms of SSIM and PSNR, demonstrate the superiority of the
proposed algorithm.


title:
A Low-Frequency Tone Sweep Method for in-Service Fault Location in
  Sub-Carrier Multiplexed Optical Fiber Networks

abstract:
  We demonstrate an optical fiber fault location method based on the frequency
response of the modulated fiber optical backscattered signal in a steady state
low-frequency step regime. Careful calibration and measurement allows for the
reconstruction of the fiber transfer function, which, associated to its
mathematical model, is capable of extracting the fiber characteristics. The
technique is capable of identifying non-reflective fault events in an optical
fiber link and is perfectly compatible with previous methods that focus on the
reflective events. The fact that the recuperation of the complex signal is
performed in the frequency domain and not via a Fourier Transform enables the
measurements to overcome the spatial resolution limitation of Fourier Transform
incoherent-OFDR measurements even with frequency sweep ranges down to
100-100000 Hz. This result is backed up by a less than 10 meters difference in
fault location when compared to standard OTDR measurements.


title: High flux lithium antineutrino source with variable hard spectrum

abstract:
  The work is devoted to development of hard electron antineutrino source with
variable and regulated (controlled) spectrum. The high flux antineutrino source
with hard antineutrino spectrum based on neutron activation of 7Li and
subsequent fast beta-decay (T 1/2 = 0.84 s) of the 8Li isotope with emission of
antineutrino with energy up to 13 MeV - is discussed. Creation of the intensive
isotope neutrino source of hard spectrum will allow to increase the detection
statistics of neutrino interaction and it is especially urgent for oscillation
experiments. The scheme of the proposed neutrino source is based on the
continuous transport of the created 8Li to the neutrino detector, which moved
away from the place of neutron activation. Analytical expressions for lithium
antineutrino flux is obtained. The discussed source will ensure to increase the
cross section for reactions with deuteron from several times to tens compare to
the reactor antineutrino spectrum. An another unique feature of the
installation is the possibility to vary smoothly the hardness of the
antineutrino spectrum.


title:
A global solution curve for a class of free boundary value problems
  arising in plasma physics

abstract:
  We study the existence and multiplicity of solutions and the global solution
curve of the following free boundary value problem, arising in plasma physics,
see R. Temam [18], and H. Berestycki and H. Brezis [3]: find a function $u(x)$
and a constant $b$, satisfying \[ \Delta u+g(x,u)=p(x) \;\; \mbox{in $D$} \] \[
  u \,| \, _{\partial D}=b, \;\;\;\; \int_{\partial D} \frac{\partial
u}{\partial n} \, ds=0 \,. \] Here $D \subset R^n$, is a bounded domain, with a
smooth boundary. This problem can be seen as a PDE generalization of the
periodic problem for one-dimensional pendulum-like equations. We use
continuation techniques. Our approach is suitable for numerical computations.


title:
Cold neutral atoms via charge exchange from excited state positronium: a
  proposal

abstract:
  We present a method for generating cold neutral atoms via charge exchange
reactions between trapped ions and Rydberg positronium. The high charge
exchange reaction cross section leads to efficient neutralisation of the ions
and since the positronium-ion mass ratio is small, the neutrals do not gain
appreciable kinetic energy in the process. When the original ions are cold the
reaction produces neutrals that can be trapped or further manipulated with
electromagnetic fields. Because a wide range of species can be targeted we
envisage that our scheme may enable experiments at low temperature that have
been hitherto intractable due to a lack of cooling methods. We present an
estimate for achievable temperatures, neutral number and density in an
experiment where the neutrals are formed at a milli-Kelvin temperature from
either directly or sympathetically cooled ions confined on an ion chip. The
neutrals may then be confined by their magnetic moment in a co-located magnetic
minimum well also formed on the chip. We discuss general experimental
requirements.


title: Estimates of cluster masses in screened modified gravity

abstract:
  We use cosmological hydrodynamical simulations to study the effect of
screened modified gravity models on the mass estimates of galaxy clusters. In
particular, we focus on two novel aspects: (i) we study modified gravity models
in which baryons and dark matter are coupled with different strengths to the
scalar field, and, (ii) we put the simulation results into the greater context
of a general screened-modified gravity parametrization. We have compared the
mass of clusters inferred via lensing versus the mass inferred via kinematical
measurements as a probe of violations of the equivalence principle at Mpc
scales. We find that estimates of cluster masses via X-ray observations is
mainly sensitive to the coupling between the scalar degree of freedom and
baryons - while the kinematical mass is mainly sensitive to the coupling to
dark matter. Therefore, the relation between the two mass estimates is a probe
of a possible non-universal coupling between the scalar field, the standard
model fields, and dark matter. Finally, we used observational data of kinetic,
thermal and lensing masses to place constraints on deviations from general
relativity on cluster scales for a general parametrization of screened modified
gravity theories which contains $f(R)$ and Symmetron models. We find that while
the kinematic mass can be used to place competitive constraints, using thermal
measurements is challenging as a potential non-thermal contribution is
degenerate with the imprint of modified gravity.


title:
Extract fetal ECG from single-lead abdominal ECG by de-shape short time
  Fourier transform and nonlocal median

abstract:
  The multiple fundamental frequency detection problem and the source
separation problem from a single-channel signal containing multiple oscillatory
components and a nonstationary noise are both challenging tasks. To extract the
fetal electrocardiogram (ECG) from a single-lead maternal abdominal ECG, we
face both challenges. In this paper, we propose a novel method to extract the
fetal ECG signal from the single channel maternal abdominal ECG signal, without
any additional measurement. The algorithm is composed of three main
ingredients. First, the maternal and fetal heart rates are estimated by the
de-shape short time Fourier transform, which is a recently proposed nonlinear
time-frequency analysis technique; second, the beat tracking technique is
applied to accurately obtain the maternal and fetal R peaks; third, the
maternal and fetal ECG waveforms are established by the nonlocal median. The
algorithm is evaluated on a simulated fetal ECG signal database ({\em fecgsyn}
database), and tested on two real databases with the annotation provided by
experts ({\em adfecgdb} database and {\em CinC2013} database). In general, the
algorithm could be applied to solve other detection and source separation
problems, and reconstruct the time-varying wave-shape function of each
oscillatory component.

categories: q-bio.QM physics.data-an stat.AP stat.ME stat.ML


title: A classical and a relativistic law of motion for SN1987A

abstract:
  In this paper we derive some first order differential equations which model
the classical and the relativistic thin layer approximations in the presence of
a circumstellar medium with a density which is decreasing in the distance $z$
from the equatorial plane. The circumstellar medium is assumed to follow a
density profile with $z$ of hyperbolic type, power law type, exponential type
or Gaussian type. The first order differential equations are solved
analytically, or numerically, or by a series expansion, or by Pad\'e
approximants. The initial conditions are chosen in order to model the temporal
evolution of SN 1987A over 23 years. The free parameters of the theory are
found by maximizing the observational reliability which is based on an observed
section of SN 1987A.


title:
Investigating the X-ray and Gamma-ray Properties of the Galactic
  Supernova Remnants Kes 69, 3C 396, 3C 400.2

abstract:
  Kes 69, 3C 396, and 3C 400.2 are mixed-morphology (MM) Galactic supernova
remnants (SNRs), where Kes 69 and 3C 396 are interacting with molecular clouds
(MCs). Previous X-ray studies showed that the emission from these SNRs is
thermal. It has been suggested that MM SNRs interacting with MCs are potential
candidates for recombining plasma (RP) in X-rays and hadronic gamma-ray
emission. Recently, Chandra observations revealed signs of RP in 3C 400.2. Our
preliminary analyses show that the X-ray emission of NW and SE region of 3C
400.2 arises from recombining plasma. We detected GeV gamma-ray emission from
Kes 69 and 3C 396 above 5$\sigma$.


title:
Can AGN and galaxy clusters explain the surface brightness fluctuations
  of the cosmic X-ray background?

abstract:
  Fluctuations of the surface brightness of cosmic X-ray background (CXB) carry
unique information about faint and low luminosity source populations, which is
inaccessible for conventional large-scale structure (LSS) studies based on
resolved sources. We used Chandra data of the XBOOTES field
($\sim9\,\mathrm{deg^2}$) to conduct the most accurate measurement to date of
the power spectrum of fluctuations of the unresolved CXB on the angular scales
of $\sim3\,$arcsec $-$ $\sim17\,$arcmin. We find that at sub-arcmin angular
scales, the power spectrum is consistent with the AGN shot noise, without much
need for any significant contribution from their one-halo term. This is
consistent with the theoretical expectation that low-luminosity AGN reside
alone in their dark matter halos. However, at larger angular scales we detect a
significant LSS signal above the AGN shot noise. Its power spectrum, obtained
after subtracting the AGN shot noise, follows a power law with the slope of
$-0.8\pm0.1$ and its amplitude is much larger than what can be plausibly
explained by the two-halo term of AGN. We demonstrate that the detected LSS
signal is produced by unresolved clusters and groups of galaxies. For the flux
limit of the XBOOTES survey, their flux-weighted mean redshift equals
$\left<z\right>\sim0.3$, and the mean temperature of their intracluster medium
(ICM), $\left<T\right>\approx 1.4$ keV, corresponds to the mass of $M_{500}
\sim 10^{13.5}\,\mathrm{M}_\odot$. The power spectrum of CXB fluctuations
carries information about the redshift distribution of these objects and the
spatial structure of their ICM on the linear scales of up to $\sim$Mpc, i.e. of
the order of the virial radius.


title:
NuSTAR observations of the supergiant X-ray pulsar IGR J18027-2016:
  accretion from the stellar wind and possible cyclotron absorption line

abstract:
  We report on the first focused hard X-ray view of the absorbed supergiant
system IGRJ18027-2016 performed with the NuSTAR observatory. The pulsations are
clearly detected with a period of $P_{spin}=139.866(1)$ s and a pulse fraction
of about 50-60% at energies from 3 to 80 keV. The source demonstrates an
approximately constant X-ray luminosity on a time scale of more than dozen
years with an average spin-down rate of $dP/dt\simeq6\times10^{-10}$ s/s. This
behaviour of the pulsar can be explained in terms of the wind accretion model
in the settling regime. The detailed spectral analysis at energies above 10 keV
was performed for the first time and revealed a possible cyclotron absorption
feature at energy ~23 keV. This energy corresponds to the magnetic field
$B\simeq3\times10^{12}$ G at the surface of the neutron star, which is typical
for X-ray pulsars.


title: Stealing Machine Learning Models via Prediction APIs

abstract:
  Machine learning (ML) models may be deemed confidential due to their
sensitive training data, commercial value, or use in security applications.
Increasingly often, confidential ML models are being deployed with publicly
accessible query interfaces. ML-as-a-service ("predictive analytics") systems
are an example: Some allow users to train models on potentially sensitive data
and charge others for access on a pay-per-query basis.
  The tension between model confidentiality and public access motivates our
investigation of model extraction attacks. In such attacks, an adversary with
black-box access, but no prior knowledge of an ML model's parameters or
training data, aims to duplicate the functionality of (i.e., "steal") the
model. Unlike in classical learning theory settings, ML-as-a-service offerings
may accept partial feature vectors as inputs and include confidence values with
predictions. Given these practices, we show simple, efficient attacks that
extract target ML models with near-perfect fidelity for popular model classes
including logistic regression, neural networks, and decision trees. We
demonstrate these attacks against the online services of BigML and Amazon
Machine Learning. We further show that the natural countermeasure of omitting
confidence values from model outputs still admits potentially harmful model
extraction attacks. Our results highlight the need for careful ML model
deployment and new model extraction countermeasures.


title: X-ray narrow emission lines from the nuclear region of NGC 1365

abstract:
  NGC 1365 is a Seyfert 2 galaxy with a starburst ring in its nuclear region.
In this work we look at the XMM Reflection Grating Spectrometer (RGS) data from
four 2012-13, three 2007 and two 2004 observations of NGC 1365. We characterise
the narrow-line emitting gas visible by XMM RGS and make comparisons between
the 2012-13 spectra and those from 2004-07, already published. This source is
usually absorbed within the soft X-ray band, with a typical neutral column
density of >1.5 x 10$^{23}$ cm$^{-2}$, and only 1 observation of the 9 we
investigate shows low enough absorption for the continuum to emerge in the soft
X-rays. We stack all observations from 2004-07, and separately three of the
four observations from 2012-13, analysing the less absorbed observation
separately. We first model the spectra using gaussian profiles representing the
narrow line emission. We fit physically motivated models to the 2012-13 stacked
spectra, with collisionally ionised components representing the starburst
emission and photoionised line emission models representing the AGN line
emission. The collisional and photoionised emission line models are fitted
together on top of a physical continuum and absorption model. The X-ray narrow
emission line spectrum of NGC 1365 is well represented by a combination of two
collisionally ionised and three photoionised phases of emitting gas, all with
higher than solar nitrogen abundances. This physical model was fitted to the
2012-13 stacked spectrum, and yet also fits well to the 2004-07 stacked
spectrum, without changing any characteristics of the emitting gas phases. Our
2004-07 results are consistent with previous emission line work using these
data, with 5 additional emission lines detected in both this and the 2012-13
stacked spectra. We also estimate the distance of the X-ray line-emitting
photoionised gas from the central source to be <300 pc.


title: Pinpoint Influential Posts and Authors

abstract:
  This research presents an analytical model that aims to pin-point influential
posts across a social web comprised of a corpus of posts. The model employs the
Latent Dirichlet Al-location algorithm to associate posts with topics, and the
TF-IDF metric to identify the key posts associated with each top-ic. The model
was demonstrated in the domain of customer relationship by enabling careful
monitoring of evolving "storms" created by individuals which tend to impact
large audiences (either positively or negatively). Future research should be
engaged in order to extend the scope of the corpus by including additional
relevant publicly available sources.


title:
Freeway Lane Management Approach in Mixed Traffic Environment with
  Connected Autonomous Vehicles

abstract:
  Connected autonomous vehicles (CAV) technologies are about to be in the
market in the near future. This requires transportation facilities ready to
operate in a mixed traffic environment where a portion of vehicles are CAVs and
the remaining are manual vehicles. Since CAVs are able to run with less spacing
and headway compared with manual vehicles or mixed traffic, allocating a number
of freeway lanes exclusive to CAVs may improve the overall performance of
freeways. In this paper, we propose an analytical managed lane model to
evaluate the freeway flow in mixed traffic and to determine the optimal number
of lanes to be allocated to CAVs. The proposed model is investigated in two
different operation environments: single-lane and managed lane environments. We
further define three different CAV technology scenarios: neutral, conservative,
and aggressive. In the single-lane problem, the influence of CAV penetration
rates on mixed traffic capacity is examined in each scenario. In the managed
lanes problem, we propose a method to determine the optimal number of dedicated
lanes for CAVs under different settings. A number of numerical examples with
different geometries and demand levels are investigated for all three
scenarios. A sensitivity analysis on the penetration rates is conducted. The
results show that more aggressive CAV technologies need less specific allocated
lanes because they can follow the vehicles with less time and space headways.


title: Control Flow Change in Assembly as a Classifier in Malware Analysis

abstract:
  As currently classical malware detection methods based on signatures fail to
detect new malware, they are not always efficient with new obfuscation
techniques. Besides, new malware is easily created and old malware can be
recoded to produce new one. Therefore, classical Antivirus becomes consistently
less effective in dealing with those new threats. Also malware gets hand
tailored to bypass network security and Antivirus. But as analysts do not have
enough time to dissect suspected malware by hand, automated approaches have
been developed. To cope with the mass of new malware, statistical and machine
learning methods proved to be a good approach classifying programs, especially
when using multiple approaches together to provide a likelihood of software
being malicious. In normal approach, some steps have been taken, mostly by
analyzing the opcodes or mnemonics of disassembly and their distribution. In
this paper, we focus on the control flow change (CFC) itself and finding out if
it is significant to detect malware. In the scope of this work, only relative
control flow changes are contemplated, as these are easier to extract from the
first chosen disassembler library and are within a range of 256 addresses.
These features are analyzed as a raw feature, as n-grams of length 2, 4 and 6
and the even more abstract feature of the occurrences of the n-grams is used.
Statistical methods were used as well as the Naive-Bayes algorithm to find out
if there is significant data in CFC. We also test our approach with real-world
datasets.


title: The Role of Context Selection in Object Detection

abstract:
  We investigate the reasons why context in object detection has limited
utility by isolating and evaluating the predictive power of different context
cues under ideal conditions in which context provided by an oracle. Based on
this study, we propose a region-based context re-scoring method with dynamic
context selection to remove noise and emphasize informative context. We
introduce latent indicator variables to select (or ignore) potential contextual
regions, and learn the selection strategy with latent-SVM. We conduct
experiments to evaluate the performance of the proposed context selection
method on the SUN RGB-D dataset. The method achieves a significant improvement
in terms of mean average precision (mAP), compared with both appearance based
detectors and a conventional context model without the selection scheme.


title: Fullerenes, Polytopes and Toric Topology

abstract:
  The lectures are devoted to a remarkable class of $3$-dimensional polytopes,
which are mathematical models of the important object of quantum physics,
quantum chemistry and nanotechnology -- fullerenes. The main goal is to show
how results of toric topology help to build combinatorial invariants of
fullerenes. Main notions are introduced during the lectures. The lecture notes
are addressed to a wide audience.


title: Bayesian Quantile Regression Using Random B-spline Series Prior

abstract:
  We consider a Bayesian method for simultaneous quantile regression on a real
variable. By monotone transformation, we can make both the response variable
and the predictor variable take values in the unit interval. A representation
of quantile function is given by a convex combination of two monotone
increasing functions $\xi_1$ and $\xi_2$ not depending on the prediction
variables. In a Bayesian approach, a prior is put on quantile functions by
putting prior distributions on $\xi_1$ and $\xi_2$. The monotonicity constraint
on the curves $\xi_1$ and $\xi_2$ are obtained through a spline basis expansion
with coefficients increasing and lying in the unit interval. We put a Dirichlet
prior distribution on the spacings of the coefficient vector. A finite random
series based on splines obeys the shape restrictions. We compare our approach
with a Bayesian method using Gaussian process prior through an extensive
simulation study and some other Bayesian approaches proposed in the literature.
An application to a data on hurricane activities in the Atlantic region is
given. We also apply our method on region-wise population data of USA for the
period 1985--2010.


title: Discovery of a Redback Millisecond Pulsar Candidate: 3FGL J0212.1+5320

abstract:
  We present a multi-wavelength study of the unidentified Fermi object, 3FGL
J0212.1+5320. Within the 95% error ellipse, Chandra detects a bright X-ray
source (i.e., F(0.5-7keV) = 1.4e-12 erg/cm^2/s), which has a low-mass optical
counterpart (M < 0.4 Msun and T ~ 6000 K). A clear ellipsoidal modulation is
shown in optical/infrared at 20.87 hours. The gamma-ray properties of 3FGL
J0212.1+5320 are all consistent with that of a millisecond pulsar, suggesting
that it is a gamma-ray redback millisecond pulsar binary with a low-mass
companion filling > 64% of the Roche-lobe. If confirmed, it will be a redback
binary with one of the longest orbital periods known. Spectroscopic data taken
in 2015 from the Lijiang observatory show no evidence of strong emission lines,
revealing that the accretion is currently inactive (the rotation-powered pulsar
state). This is consistent with the low X-ray luminosities (Lx ~ 10^32 erg/s)
and the possible X-ray modulation seen by Chandra and Swift. Considering that
the X-ray luminosity and the high X-ray-to-gamma-ray flux ratio (8%) are both
comparable to that of the two known gamma-ray transitional millisecond pulsars,
we suspect that 3FGL J0212.1+5320 could be a potential target to search for
future transition to the accretion active state.


title: Kaon experiments at CERN: recent results and prospects

abstract:
  The NA48/2 and NA62-$R_K$ experiments at the CERN SPS collected large samples
of charged kaon decays in flight in 2003--07. The data analysis is still
on-going (with over 20 publications produced so far); the recent results from
these experiments are presented. A new upper limit on the rate of a lepton
number violating decay $K^\pm\to\pi^\mp\mu^\pm\mu^\pm$ is reported:
$\mathcal{B} < 8.6\times 10^{-11}$ at 90\% CL. Searches for heavy sterile
neutrino $N_4$ and neutral scalar resonances ($\chi$) in $K^\pm\to\pi\mu\mu$
decays are reported. Upper limits on the products $\mathcal{B}(K^\pm\to\mu^\pm
N_4)\mathcal{B}(N_4\to\pi^\mp\mu^\pm)$ and $\mathcal{B}(K^\pm\to\pi^\pm
\chi)\mathcal{B}(\chi\to\mu^+\mu^-)$ are set in the range $10^{-10}$ to
$10^{-9}$ for resonance lifetimes up to 100~ps. A preliminary measurement of
the electromagnetic transition form factor slope of the $\pi^0$ from
$1.05\times 10^6$ fully reconstructed $\pi^0\to\gamma e^+e^-$ decays is
presented: the obtained result $a = (3.70 \pm 0.53_\text{stat} \pm
0.36_\text{syst})\times 10^{-2}$ represents the first observation of a non-zero
slope in the time-like region of momentum transfer.


title:
Toward a new tool to extract the Evidence from a Memory Card of Mobile
  phones

abstract:
  Today, a mobile phone is not just a phone but it is a computer that you can
also use for calling someone. Besides, in criminal investigations the
importance of evidence from the mobile phone is increasing as more and more
phones are seized at the Digital Forensic Department of the police. Indeed, the
amount of memory cards of these mobile phones that need to be investigated
separately is also increasing. Possible reasons are that the mobile phone
investigation software does not support the specific mobile phone or the
specific, for that investigation, artefacts. Sometimes the software
investigates just the internal memory of the mobile phone and not the data
which is written on the memory card. Fact is also that although the mobile
phone was investigated by the dedicated software, the possibility that the
associated memory card contains additional important information is evident.
The current procedure to get all of the usable information from a memory card
of a mobile phone is very time-consuming process and not user friendly. In this
paper, we present a new single tool to simplify the investigation of a memory
card from a mobile phone. We also test our tool with WhatsApp application
installed on the memory card from different mobile phones.


title: Forensics Acquisition of IMVU: A Case Study

abstract:
  There are many applications available for personal computers and mobile
devices that facilitate users in meeting potential partners. There is, however,
a risk associated with the level of anonymity on using instant message
applications, because there exists the potential for predators to attract and
lure vulnerable users. Today Instant Messaging within a Virtual Universe (IMVU)
combines custom avatars, chat or instant message (IM), community, content
creation, commerce, and anonymity. IMVU is also being exploited by criminals to
commit a wide variety of offenses. However, there are very few researches on
digital forensic acquisition of IMVU applications. In this paper, we discuss
first of all on challenges of IMVU forensics. We present a forensic acquisition
of an IMVU 3D application as a case study. We also describe and analyse our
experiments with this application.


title: On a generalization of the three spectral inverse problem

abstract:
  We consider a generalization of the three spectral inverse problem, that is,
for given spectrum of the Dirichlet-Dirichlet problem (the Sturm-Liouville
problem with Dirichlet conditions at both ends) on the whole interval $[0,a]$,
parts of spectra of the Dirichlet-Neumann and Dirichlet-Dirichlet problems on
$[0,a/2]$ and parts of spectra of the Dirichlet-Newman and Dirichlet-Dirichlet
problems on $[a/2,a]$, we find the potential of the Sturm-Liouville equation.


title: Puzzles in modern biology. I. Male sterility, failure reveals design

abstract:
  Many human males produce dysfunctional sperm. Various plants frequently abort
pollen. Hybrid matings often produce sterile males. Widespread male sterility
is puzzling. Natural selection prunes reproductive failure. Puzzling failure
implies something that we do not understand about how organisms are designed.
Solving the puzzle reveals the hidden processes of design.


title: An Empirical Study of Cycle Toggling Based Laplacian Solvers

abstract:
  We study the performance of linear solvers for graph Laplacians based on the
combinatorial cycle adjustment methodology proposed by
[Kelner-Orecchia-Sidford-Zhu STOC-13]. The approach finds a dual flow solution
to this linear system through a sequence of flow adjustments along cycles. We
study both data structure oriented and recursive methods for handling these
adjustments.
  The primary difficulty faced by this approach, updating and querying long
cycles, motivated us to study an important special case: instances where all
cycles are formed by fundamental cycles on a length $n$ path. Our methods
demonstrate significant speedups over previous implementations, and are
competitive with standard numerical routines.


title: Hydrodynamic Predictions for Pb+Pb Collisions at 5.02 A TeV

abstract:
  Predictions and comparisons of hadronic flow observables for Pb+Pb collisions
at 2.76 A TeV and 5.02 A TeV are presented using a hydrodynamics + hadronic
cascade hybrid approach. Initial conditions are generated via a new formulation
of the IP-Glasma model and then evolved using relativistic viscous
hydrodynamics and finally fed into transport cascade in the hadronic phase. The
results of this work show excellent agreement with the recent charged hadron
anisotropic flow measurements from the ALICE collaboration of Pb+Pb collisions
at 5.02 A TeV. Event-by-event distributions of charged hadron v n , flow
event-plane correlations, and flow factorization breaking ratios are compared
with existing measurements at 2.76 A TeV, and are predicted at 5.02 A TeV.
Further predictions of identified hadron observables (for both light and
multi-strange hadrons), such as p T -spectra and anisotropic flow coefficients,
are presented.


title:
Puzzles in modern biology. II. Language, cancer and the recursive
  processes of evolutionary innovation

abstract:
  Human language emerged abruptly. Diverse body forms evolved suddenly.
Seed-bearing plants spread rapidly. How do complex evolutionary innovations
arise so quickly? Resolving alternative claims remains difficult. The great
events of the past happened a long time ago. Cancer provides a model to study
evolutionary innovation. A tumor must evolve many novel traits to become an
aggressive cancer. I use what we know or could study about cancer to describe
the key processes of innovation. In general, evolutionary systems form a
hierarchy of recursive processes. Those recursive processes determine the rates
at which innovations are generated, spread and transmitted. I relate the
recursive processes to abrupt evolutionary innovation.


title: A Large Scale Corpus of Gulf Arabic

abstract:
  Most Arabic natural language processing tools and resources are developed to
serve Modern Standard Arabic (MSA), which is the official written language in
the Arab World. Some Dialectal Arabic varieties, notably Egyptian Arabic, have
received some attention lately and have a growing collection of resources that
include annotated corpora and morphological analyzers and taggers. Gulf Arabic,
however, lags behind in that respect. In this paper, we present the Gumar
Corpus, a large-scale corpus of Gulf Arabic consisting of 110 million words
from 1,200 forum novels. We annotate the corpus for sub-dialect information at
the document level. We also present results of a preliminary study in the
morphological annotation of Gulf Arabic which includes developing guidelines
for a conventional orthography. The text of the corpus is publicly browsable
through a web interface we developed for it.


title:
Extremely fast orbital decay of the black hole X-ray binary Nova Muscae
  1991

abstract:
  We present new medium-resolution spectroscopic observations of the black hole
X-ray binary Nova Muscae 1991 taken with X-Shooter spectrograph installed at
the 8.2m-VLT telescope. These observations allow us to measure the time of
inferior conjunction of the secondary star with the black hole in this system
that, together with previous measurements, yield an orbital period decay of
$\dot P=-20.7\pm12.7$ ms yr$^{-1}$ ($-24.5\pm15.1$ $\mu $s per orbital cycle).
This is significantly faster than those previously measured in the other black
hole X-ray binaries A0620-00 and XTE J1118+480. No standard black hole X-ray
binary evolutionary model is able to explain this extremely fast orbital decay.
At this rate, the secondary star would reach the event horizon (as given by the
Schwarzschild radius of about 32 km) in roughly 2.7 Myr. This result has
dramatic implications on the evolution and lifetime of black hole X-ray
binaries.


title: Open Microwave Cavity for use in a Purcell Enhancement Cooling Scheme

abstract:
  A microwave cavity is described which can be used to cool lepton plasmas for
potential use in synthesis of antihydrogen. The cooling scheme is an
incarnation of the Purcell Effect: when plasmas are coupled to a microwave
cavity, the plasma cooling rate is resonantly enhanced through increased
spontaneous emission of cyclotron radiation. The cavity forms a three electrode
section of a Penning-Malmberg trap and has a bulged cylindrical geometry with
open ends aligned with the magnetic trapping axis. This allows plasmas to be
injected and removed from the cavity without the need for moving parts while
maintaining high quality factors for resonant modes. The cavity includes unique
surface preparations for adjusting the cavity quality factor and achieving
anti-static shielding using thin layers of nichrome and colloidal graphite
respectively. Geometric design considerations for a cavity with strong cooling
power and low equilibrium plasma temperatures are discussed. Cavities of this
weak-bulge design will be applicable to many situations where an open geometry
is required.


title:
Event-triggered second-moment stabilization of linear systems under
  packet drops

abstract:
  This paper deals with the stabilization of linear systems with process noise
under packet drops between the sensor and the controller. Our aim is to ensure
exponential convergence of the second moment of the plant state to a given
bound in finite time. Motivated by considerations about the efficient use of
the available resources, we adopt an event-triggering approach to design the
transmission policy. In our design, the sensor's decision to transmit or not
the state to the controller is based on an online evaluation of the future
satisfaction of the control objective. The resulting event-triggering policy is
hence specifically tailored to the control objective. We formally establish
that the proposed event-triggering policy meets the desired objective and
quantify its efficiency by providing an upper bound on the fraction of expected
number of transmissions in an infinite time interval. Simulations for scalar
and vector systems illustrate the results.


title: Pointwise convergence of solution to Schrodinger equation on manifolds

abstract:
  Let $(M^n,g)$ be a Riemannian manifold without boundary. We study the amount
of initial regularity is required so that the solution to free Schr\"{o}dinger
equation converges pointwisely to its initial data. Assume the initial data is
in $H^\alpha(M)$. For Hyperbolic Space, standard Sphere and the 2 dimensional
Torus, we prove that $\alpha>\frac{1}{2}$ is enough. For general compact
manifolds, due to lacking of local smoothing effect, it is hard to beat the
bound $\alpha>1$ from interpolation. We managed to go below 1 for dimension
$\leq 3$. The more interesting thing is that, for 1 dimensional compact
manifold, $\alpha>\frac{1}{3}$ is sufficient.


title: Numerical Characterization of In Vivo Wireless Communication Channels

abstract:
  In this paper, we numerically investigated the in vivo wireless communication
channel for the human male torso at 915 MHz. The results show that in vivo
channel is different from the classical communication channel, and location
dependency is very critical for link budget calculations. A statistical path
loss model based on the angle, depth and body region is introduced for near and
far field regions. Furthermore, multipath characteristics are investigated
using a power delay profile as well.


title: Android and Wireless data-extraction using Wi-Fi

abstract:
  Today, mobile phones are very popular, fast growing technology. Mobile phones
of the present day are more and more like small computers. The so-called
"smartphones" contain a wealth of information each. This information has been
proven to be very useful in crime investigations, because relevant evidence can
be found in data retrieved from mobile phones used by criminals. In traditional
methods, the data from mobile phones can be extracted using an USB-cable.
However, for some reason this USB-cable connection cannot be made, the data
should be extracted in an alternative way. In this paper, we study the
possibility of extracting data from mobile devices using a Wi-Fi connection. We
describe our approach on mobile devices containing the Android Operating
System. Through our experiments, we also give recommendation on which
application and protocol can be used best to retrieve data.


title: Arithmetic functions in short intervals and the symmetric group

abstract:
  We consider the variance of sums of arithmetic functions over random short
intervals in the function field setting. Based on the analogy between
factorizations of random elements of $\mathbb{F}_q[T]$ into primes and the
factorizations of random permutations into cycles, we give a simple but general
formula for these variances in the large $q$ limit for arithmetic functions
that depend only upon factorization structure. From this we derive new
estimates, quickly recover some that are already known, and make new
conjectures in the setting of the integers.
  In particular we make the combinatorial observation that any function of this
sort can be decomposed into a sum of functions $u$ and $v$, depending on the
size of the short interval, with $u$ making a negligible contribution to the
variance, and $v$ asymptotically contributing diagonal terms only.
  This variance evaluation is closely related to the appearance of random
matrix statistics in the zeros of families of L-functions and sheds light on
the arithmetic meaning of this phenomenon.


title: Real-time Cooperative Communication for Automation over Wireless

abstract:
  High-performance industrial automation systems rely on tens of simultaneously
active sensors and actuators and have stringent communication latency and
reliability requirements. Current wireless technologies like WiFi, Bluetooth,
and LTE are unable to meet these requirements, forcing the use of wired
communication in industrial control systems. This paper introduces a wireless
communication protocol that capitalizes on multiuser diversity and cooperative
communication to achieve the ultra-reliability with a low-latency constraint.
  Our protocol is analyzed using the communication-theoretic
delay-limited-capacity framework and compared to baseline schemes that
primarily exploit frequency diversity. For a scenario inspired by an industrial
printing application with thirty nodes in the control loop, 20B messages
transmitted between pairs of nodes and a cycle time of $2$ ms, an idealized
protocol can achieve a cycle failure probability (probability that any packet
in a cycle is not successfully delivered) lower than $10^{-9}$ with nominal SNR
below 5 dB in a 20MHz wide channel.


title: Persistency of Genuine Correlations Under Particle Loss

abstract:
  In a recent work
[\href{http://journals.aps.org/pra/abstract/10.1103/PhysRevA.86.042113}{Phys.
Rev. A 86, 042113 (2012)}] the question of persistency of entanglement and
nonlocality of multi-party systems under particle loss has been addressed. This
question is of immense importance considering the practical realization of the
information theoretic tasks which make use of the power of quantum
correlations. But in multipartite scenario more interesting cases arise since
subsystems can also possess genuineness in correlation which is prevalently
inequivalent to the bipartite scenario. In this work, we investigate the
persistency of such genuine correlations under particle loss. Keeping in mind
the practical importance, considerable attention has been devoted to find the
multipartite states which exhibit maximal persistency of genuine correlations.


title: Definable Coherent Ultrapowers and Elementary Extensions

abstract:
  We develop the notion of coherent ultrafilters (extenders without normality
or well-foundedness). We then use definable coherent ultraproducts to
characterize any extension of a model $M$ in any fragment of
$\mathbb{L}_{\infty, \omega}$ that defines Skolem functions by a sufficiently
complete (but in $ZFC$) coherent ultrafilter. We apply this method to various
elementary classes and AECs.


title:
Brownian regularity for the Airy line ensemble, and multi-polymer
  watermelons in Brownian last passage percolation

abstract:
  The Airy line ensemble is a positive-integer indexed system of random
continuous curves whose finite dimensional distributions are given by the
multi-line Airy process. It is a natural object in the KPZ universality class:
for example, its highest curve, the Airy$_2$ process, describes after the
subtraction of a parabola the limiting law of the scaled energy of a geodesic
running from the origin to a variable point on an anti-diagonal line in such
problems as Poissonian last passage percolation. The ensemble of curves
resulting from the Airy line ensemble after the subtraction of the same
parabola enjoys a simple and explicit spatial Markov property, the Brownian
Gibbs property. In this paper, we employ the Brownian Gibbs property to make a
close comparison between the Airy line ensemble's curves after affine shift and
Brownian bridge, proving the finiteness of a superpolynomially growing moment
bound on Radon-Nikodym derivatives. We also determine the value of a natural
exponent describing in Brownian last passage percolation the decay in
probability for the existence of several near geodesics that are disjoint
except for their common endpoints, where the notion of `near' refers to a small
deficit in scaled geodesic energy, with the parameter specifying this nearness
tending to zero. To prove both results, we introduce a technique that may be
useful elsewhere for finding upper bounds on probabilities of events concerning
random systems of curves enjoying the Brownian Gibbs property. Several results
in this article play a fundamental role in a further study of Brownian last
passage percolation in three companion papers, [Ham17a,b,c], in which geodesic
coalescence and geodesic energy profiles are investigated in scaled
coordinates.


title:
Generalized curvature for certain Radon-like operators of intermediate
  dimension

abstract:
  This paper establishes $L^p$-improving estimates for a variety of Radon-like
transforms which integrate functions over submanifolds of intermediate
dimension. In each case, the results rely on a unique notion of curvature which
relates to, but is distinct from, Phong-Stein rotational curvature. The results
obtained are sharp up to the loss of endpoints. The methods used are a new
adaptation of the familiar method of inflation developed by Christ and others.
Unlike most previous instances of this method, the present application does not
require any particular linear algebraic relations to hold for the dimension and
codimension.


title:
Anderson localization for one-frequency quasi-periodic block Jacobi
  operators

abstract:
  We consider a one-frequency, quasi-periodic, block Jacobi operator, whose
blocks are generic matrix-valued analytic functions. We establish Anderson
localization for this type of operator under the assumption that the coupling
constant is large enough but independent of the frequency. This generalizes a
result of J. Bourgain and S. Jitomirskaya on localization for band lattice,
quasi-periodic Schroedinger operators.


title: Learning-Based View Synthesis for Light Field Cameras

abstract:
  With the introduction of consumer light field cameras, light field imaging
has recently become widespread. However, there is an inherent trade-off between
the angular and spatial resolution, and thus, these cameras often sparsely
sample in either spatial or angular domain. In this paper, we use machine
learning to mitigate this trade-off. Specifically, we propose a novel
learning-based approach to synthesize new views from a sparse set of input
views. We build upon existing view synthesis techniques and break down the
process into disparity and color estimation components. We use two sequential
convolutional neural networks to model these two components and train both
networks simultaneously by minimizing the error between the synthesized and
ground truth images. We show the performance of our approach using only four
corner sub-aperture views from the light fields captured by the Lytro Illum
camera. Experimental results show that our approach synthesizes high-quality
images that are superior to the state-of-the-art techniques on a variety of
challenging real-world scenes. We believe our method could potentially decrease
the required angular resolution of consumer light field cameras, which allows
their spatial resolution to increase.


title: Rigidity for convex-cocompact actions on rank-one symmetric spaces

abstract:
  When a discrete group admits a convex-cocompact action on a non-compact
rank-one symmetric space, there is a natural lower bound for the Hausdorff
dimension of the limit set, given by the Ahlfors regular conformal dimension of
the boundary of the group. We show that equality is achieved precisely when the
group stabilizes an isometric copy of some non-compact rank-one symmetric space
on which it acts with compact quotient. This generalizes a theorem of
Bonk-Kleiner, who proved it in the case of real hyperbolic space.
  To prove our main theorem, we study tangents of Lipschitz differentiability
spaces that are embedded in a Carnot group. We show that almost all tangents
are isometric to Carnot subgroups, at least when they are rectifiably
connected. This extends a theorem of Cheeger, who proved it for PI spaces that
are embedded in Euclidean space.


title: An Integrated Classification Model for Financial Data Mining

abstract:
  Nowadays, financial data analysis is becoming increasingly important in the
business market. As companies collect more and more data from daily operations,
they expect to extract useful knowledge from existing collected data to help
make reasonable decisions for new customer requests, e.g. user credit category,
churn analysis, real estate analysis, etc. Financial institutes have applied
different data mining techniques to enhance their business performance.
However, simple ap-proach of these techniques could raise a performance issue.
Besides, there are very few general models for both understanding and
forecasting different finan-cial fields. We present in this paper a new
classification model for analyzing fi-nancial data. We also evaluate this model
with different real-world data to show its performance.


title:
Flow tracing as a tool set for the analysis of networked large-scale
  renewable electricity systems

abstract:
  The method of flow tracing follows the power flow from net-generating sources
through the network to the net-consuming sinks, which allows to assign the
usage of the underlying transmission infrastructure to the system participants.
This article presents a reformulation that is applicable to arbitrary
compositions of inflow appearing naturally in models of large-scale electricity
systems with a high share of renewable power generation. We propose an
application which allows to associate power flows on the grid to specific
regions or generation technologies, and emphasizes the capability of this
technique to disentangle the spatio-temporal patterns of physical imports and
exports occurring in such systems. The analytical potential of this method is
showcased for a scenario based on the IEEE 118 bus network.


title:
Single Shot Digital Holography Using Iterative Reconstruction with
  Alternating Updates of Amplitude and Phase

abstract:
  We present an image recovery approach to improve amplitude and phase
reconstruction from single shot digital holograms, using iterative
reconstruction with alternating updates. This approach allows the flexibility
to apply different priors to amplitude and phase, improves phase reconstruction
in image areas with low amplitudes, and does not require phase unwrapping for
regularization. Phantom simulations and experimental measurements of a grating
sample both demonstrate that the proposed method helps to reduce noise and
resolve finer features. The improved image reconstruction from this technique
will benefit the many applications of digital holography.


title: The Frequency Of Binary Star Interlopers Amongst Transitional Discs

abstract:
  Using Non-Redundant Mask interferometry (NRM), we searched for binary
companions to objects previously classified as Transitional Disks (TD). These
objects are thought to be an evolutionary stage between an optically thick disk
and optically thin disk. We investigate the presence of a stellar companion as
a possible mechanism of material depletion in the inner region of these disks,
which would rule out an ongoing planetary formation process in distances
comparable to the binary separation. For our detection limits, we implement a
new method of completeness correction using a combination of randomly sampled
binary orbits and Bayesian inference. The selected sample of 24 TDs belong to
the nearby and young star forming regions: Ophiuchus ($\sim$ 130 pc),
Taurus-Auriga ($\sim$ 140 pc) and IC348 ( $\sim$ 220 pc). These regions are
suitable to resolve faint stellar companions with moderate to high confidence
levels at distances as low as 2 au from the central star. With a total of 31
objects, including 11 known TDs and circumbinary disks from the literature, we
have found that a fraction of 0.38 $\pm$ 0.09 of the SEDs of these objects are
likely due to the tidal interaction between a close binary and its disk, while
the remaining SEDs are likely the result of other internal processes such as
photoevaporation, grain growth, planet disk interactions. In addition, we
detected four companions orbiting outside the area of the truncation radii and
we propose that the IR excesses of these systems are due to a disk orbiting a
secondary companion


title:
A Dirichlet Process Mixture Model for Clustering Longitudinal Gene
  Expression Data

abstract:
  Subgroup identification (clustering) is an important problem in biomedical
research. Gene expression profiles are commonly utilized to define subgroups.
Longitudinal gene expression profiles might provide additional information on
disease progression than what is captured by baseline profiles alone. Moreover,
the longitudinal gene expression data allows for intra-individual variability
to be accounted for when grouping patients. Therefore, subgroup identification
could be more accurate and effective with the aid of longitudinal gene
expression data. However, existing statistical methods are unable to fully
utilize these data for patient clustering. In this article, we introduce a
novel subgroup identification method in the Bayesian setting based on
longitudinal gene expression profiles. This method, called BClustLonG, adopts a
linear mixed-effects framework to model the trajectory of genes over time while
clustering is jointly conducted based on the regression coefficients obtained
from all genes. In order to account for the correlations among genes and
alleviate the high dimensionality challenges, we adopt a factor analysis model
for the regression coefficients. The Dirichlet process prior distribution is
utilized for the means of the regression coefficients to induce clustering.
Through extensive simulation studies, we show that BClustLonG has improved
performance over other clustering methods. When applied to a dataset of
severely injured (burn or trauma) patients, our model is able to distinguish
burn patients from trauma patients and identify interesting subgroups in trauma
patients.


title:
Renormalization Group Transformation for Hamiltonian Dynamical Systems
  in Biological Networks

abstract:
  We apply the renormalization group theory to the dynamical systems with the
simplest example of basic biological motifs. This includes the interpretation
of complex networks as the perturbation to simple network. This is the first
step to build our original framework to infer the properties of biological
networks, and the basis work to see its effectiveness to actual complex
systems.


title: Network Map Reduce

abstract:
  Networking data analytics is increasingly used for enhanced network
visibility and controllability. We draw the similarities between the Software
Defined Networking (SDN) architecture and the MapReduce programming model.
Inspired by the similarity, we suggest the necessary data plane innovations to
make network data plane devices function as distributed mappers and optionally,
reducers. A streaming network data MapReduce architecture can therefore
conveniently solve a series of network monitoring and management problems.
Unlike the traditional networking data analytical system, our proposed system
embeds the data analytics engine directly in the network infrastructure. The
affinity leads to a concise system architecture and better cost performance
ratio. On top of this architecture, we propose a general MapReduce-like
programming model for real-time and one-pass networking data analytics, which
involves joint in-network and out-of-network computing. We show this model can
address a wide range of interactive queries from various network applications.
This position paper strives to make a point that the white-box trend does not
necessarily lead to simple and dumb networking devices. Rather, the defining
characteristics of the next generation white-box are open and programmable, so
that the network devices can be made smart and versatile to support new
services and applications.


title: Distance-Correlation based Gene Set Analysis in Longitudinal Studies

abstract:
  Longitudinal gene expression profiles of patients are collected in some
clinical studies to monitor disease progression and understand disease
etiology. The identification of gene sets that have coordinated changes with
relevant clinical outcomes over time from these data could provide significant
insights into the molecular basis of disease progression and hence may lead to
better treatments. In this article, we propose a Distance-Correlation based
Gene Set Analysis (dcGSA) method for longitudinal gene expression data. dcGSA
is a non-parametric approach, statistically robust, and can capture both linear
and nonlinear relationships between gene sets and clinical outcomes. In
addition, dcGSA is able to identify related gene sets in cases where the
effects of gene sets on clinical outcomes differ across patients due to the
patient heterogeneity, alleviate the confounding effects of some unobserved
covariates, and allow the assessment of associations between gene sets and
multiple related outcomes simultaneously. Through extensive simulation studies,
we demonstrate that dcGSA is more powerful of detecting relevant genes than
other commonly used gene set analysis methods. When dcGSA is applied to
multiple real datasets of different characteristics, we are able to identify
more disease related gene sets than other methods.


title:
A Bayesian Semiparametric Factor Analysis Model for Subtype
  Identification

abstract:
  Disease subtype identification (clustering) is an important problem in
biomedical research. Gene expression profiles are commonly utilized to infer
disease subtypes, which often lead to biologically meaningful insights into
disease. Despite many successes, existing clustering methods may not perform
well when genes are highly correlated and many uninformative genes are included
for clustering due to the high dimensionality. In this article, we introduce a
novel subtype identification method in the Bayesian setting based on gene
expression profiles. This method, called BCSub, adopts an innovative
semiparametric Bayesian factor analysis model to reduce the dimension of the
data to a few factor scores for clustering. Specifically, the factor scores are
assumed to follow the Dirichlet process mixture model in order to induce
clustering. Through extensive simulation studies, we show that BCSub has
improved performance over commonly used clustering methods. When applied to two
gene expression datasets, our model is able to identify subtypes that are
clinically more relevant than those identified from the existing methods.


title:
Placement Delivery Array Design through Strong Edge Coloring of
  Bipartite Graphs

abstract:
  The technique of coded caching proposed by Madddah-Ali and Niesen is a
promising approach to alleviate the load of networks during busy times.
Recently, placement delivery array (PDA) was presented to characterize both the
placement and delivery phase in a single array for the centralized coded
caching algorithm. In this paper, we interpret PDA from a new perspective,
i.e., the strong edge coloring of bipartite graph. We prove that, a PDA is
equivalent to a strong edge colored bipartite graph. Thus, we can construct a
class of PDAs from existing structures in bipartite graphs. The class includes
the scheme proposed by Maddah-Ali \textit{et al.} and a more general class of
PDAs proposed by Shangguan \textit{et al.} as special cases. Moreover, it is
capable of generating a lot of PDAs with flexible tradeoff between the
sub-packet level and load.


title:
Joint Models for Time-to-Event Data and Longitudinal Biomarkers of High
  Dimension

abstract:
  Joint models for longitudinal biomarkers and time-to-event data are widely
used in longitudinal studies. Many joint modeling approaches have been proposed
to deal with different types of longitudinal biomarkers and survival outcomes.
However, most existing joint modeling methods cannot deal with a large number
of longitudinal biomarkers simultaneously, such as the longitudinally collected
gene expression profiles. In this article, we propose a new joint modeling
method under the Bayesian framework, which is able to deal with longitudinal
biomarkers of high dimension. Specifically, we assume that only a few
unobserved latent variables are related to the survival outcome and the latent
variables are inferred using a factor analysis model, which greatly reduces the
dimensionality of the biomarkers and also accounts for the high correlations
among the biomarkers. Through extensive simulation studies, we show that our
proposed method has improved prediction accuracy over other joint modeling
methods. We illustrate the usefulness of our method on a dataset of idiopathic
pulmonary fibrosis patients in which we are interested in predicting the
patients' time-to-death using their gene expression profiles.


title: MP3: A More Efficient Private Presence Protocol

abstract:
  This paper proposes MP3, the second privacy-preserving presence protocol that
leaks no information about the graph structure of the social network. Several
cryptographic techniques are applied to improve the existing DP5 protocol---the
first privacy-preserving presence protocol---while maintaining the same level
of privacy. The key contribution of this paper is the use of a dynamic
broadcast encryption scheme to reduce the size of the presence database. This
enables cheaper registration and lookup required for the protocol. As compared
to DP5, MP3 requires on the order of ten times less bandwidth of the servers
during registration, and requires on the order of two times less bandwidth for
lookup, for a small number of users ($N=10000$). Furthermore, these savings
asymptotically increase with the number of users. The client-side latency is
also improved significantly in MP3, as compared with DP5. We provide an
evaluation of the performance and scalability of both protocols.


title: Group schemes of square free order

abstract:
  Every finite flat finitely presented group scheme G of square free order over
a scheme S can be written as an extension of a finite etale S-group scheme G"
by a commutative finite flat finitely presented S-group scheme G' that is a
direct sum of group schemes of prime order. Such an extension splits over a
finite etale surjective base change.


title: A Magnetic Ribbon Model for Star-Forming Filaments

abstract:
  We develop a magnetic ribbon model for molecular cloud filaments. These
result from turbulent compression in a molecular cloud in which the background
magnetic field sets a preferred direction. We argue that this is a natural
model for filaments and is based on the interplay between turbulence, strong
magnetic fields, and gravitationally-driven ambipolar diffusion, rather than
pure gravity and thermal pressure. An analytic model for the formation of
magnetic ribbons that is based on numerical simulations is used to derive a
lateral width of a magnetic ribbon. This differs from the thickness along the
magnetic field direction, which is essentially the Jeans scale. We use our
model to calculate a synthetic observed relation between apparent width in
projection versus observed column density. The relationship is relatively flat,
similar to observations, and unlike the simple expectation based on a Jeans
length argument.


title:
Creation and evolution of particle numberasymmetry in an expanding
  universe

abstract:
  We introduce a model which may generate particle number asymmetry in an
expanding Universe. The model includes CP violating and particle number
violating interactions. The model consists of a real scalar field and a complex
scalar field. Starting with an initial condition specified by a density matrix,
we show how the asymmetry is created through the interaction and how it evolves
at later time. We compute the asymmetry using non-equilibrium quantum field
theory and as a first test of the model, we study how the asymmetry evolves in
the flat limit.


title:
Theoretical Approach to Electroresistance in Ferroelectric Tunnel
  Junctions

abstract:
  In this paper, a theoretical approach, comprising the non-equilibrium Green's
function method for electronic transport and Landau-Khalatnikov equation for
electric polarization dynamics, is presented to describe polarization-dependent
tunneling electroresistance (TER) in ferroelectric tunnel junctions. Using
appropriate contact, interface, and ferroelectric parameters, measured
current-voltage characteristic curves in both inorganic
(Co/BaTiO$_{3}$/La$_{0.67}$Sr$_{0.33}$MnO$_{3}$) and organic (Au/PVDF/W)
ferroelectric tunnel junctions can be well described by the proposed approach.
Furthermore, under this theoretical framework, the controversy of opposite TER
signs observed experimentally by different groups in
Co/BaTiO$_{3}$/La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ systems is addressed by
considering the interface termination effects using the effective contact
ratio, defined through the effective screening length and dielectric response
at the metal/ferroelectric interfaces. Finally, our approach is extended to
investigate the role of a CoO$_{x}$ buffer layer at the Co/BaTiO$_{3}$
interface in a ferroelectric tunnel memristor. It is shown that, to have a
significant memristor behavior, not only the interface oxygen vacancies but
also the CoO$_{x}$ layer thickness may vary with the applied bias.


title:
High-Dimension, Low Sample Size Asymptotics of Canonical Correlation
  Analysis

abstract:
  An asymptotic behavior of canonical correlation analysis is studied when
dimension d grows and the sample size n is fxed. In particular, we are
interested in the conditions for which CCA works or fails in the HDLSS
situation. This technical report investigates those conditions in a rather
simplified setting where there exists one pair of directions in two sets of
random variables with non-zero correlation between two sets of scores on them.
Proofs and an extensive simulation study supports the findings.


title:
Episodic Exploration for Deep Deterministic Policies: An Application to
  StarCraft Micromanagement Tasks

abstract:
  We consider scenarios from the real-time strategy game StarCraft as new
benchmarks for reinforcement learning algorithms. We propose micromanagement
tasks, which present the problem of the short-term, low-level control of army
members during a battle. From a reinforcement learning point of view, these
scenarios are challenging because the state-action space is very large, and
because there is no obvious feature representation for the state-action
evaluation function. We describe our approach to tackle the micromanagement
scenarios with deep neural network controllers from raw state features given by
the game engine. In addition, we present a heuristic reinforcement learning
algorithm which combines direct exploration in the policy space and
backpropagation. This algorithm allows for the collection of traces for
learning using deterministic policies, which appears much more efficient than,
for example, {\epsilon}-greedy exploration. Experiments show that with this
algorithm, we successfully learn non-trivial strategies for scenarios with
armies of up to 15 agents, where both Q-learning and REINFORCE struggle.


title: Simultaneous independent image display technique on multiple 3D objects

abstract:
  We propose a new system to visualize depth-dependent patterns and images on
solid objects with complex geometry using multiple projectors. The system,
despite consisting of conventional passive LCD projectors, is able to project
different images and patterns depending on the spatial location of the object.
The technique is based on the simple principle that multiple patterns projected
from multiple projectors interfere constructively with each other when their
patterns are projected on the same object. Previous techniques based on the
same principle can only achieve 1) low resolution volume colorization or 2)
high resolution images but only on a limited number of flat planes. In this
paper, we discretize a 3D object into a number of 3D points so that high
resolution images can be projected onto the complex shapes. We also propose a
dynamic ranges expansion technique as well as an efficient optimization
procedure based on epipolar constraints.
  Such technique can be used to the extend projection mapping to have spatial
dependency, which is desirable for practical applications. We also demonstrate
the system potential as a visual instructor for object placement and
assembling. Experiments prove the effectiveness of our method.


title: Knowledge management and measurement in Public Sector Organizations

abstract:
  Knowledge Management (KM) is a strategic component that enables development,
growth and continuous improvement of Public Sector Organizations (PSO). This
thesis is bounded to this specific context. Indeed, we critically and
comprehensively study the factors that characterize KM strategies and those
that foster its development and success in PSO, then finally we propose metrics
to measure and evaluate, in order to continuous and systematically improve KM
practices in PSO. Main problems are related to the lack of academic literature
that explains the elements that KM address in the given context. In addition,
it is identified as a problem the lack of criteria for measuring and evaluating
KM in PSO, from a different viewpoint than business perspective. The
contribution of this thesis is that it provides valuable elements for an
academic debate on the previous factors, strategies and metrics to promote KM
initiatives in PSO. To achieve the research objective of this thesis we
performed a comprehensive systematic literature review in order to discover
what the KM critical success factors are, and also we integrated and proposed
some metrics to evaluate and assess the performance of KM in PSO. We conducted
an in-depth study among different Public Sector Organizations in order to learn
what are the critical success factors that must be first considered before
implement KM initiatives. based on this. Finally, based on this methodological
proposal and as a result of this research, we were able to analyze and explain
the critical success factors, we identified some strategies to encourage the
success of KM and integrated a proposal of metrics, from different approaches,
for KM in PSO.


title: Recent Results on Radiative and Electroweak Penguin B Decays at Belle

abstract:
  We report on recent results on radiative and electroweak penguin B decays at
Belle at KEKB accelerator.


title:
Iteratively Reweighted Least Squares Algorithms for L1-Norm Principal
  Component Analysis

abstract:
  Principal component analysis (PCA) is often used to reduce the dimension of
data by selecting a few orthonormal vectors that explain most of the variance
structure of the data. L1 PCA uses the L1 norm to measure error, whereas the
conventional PCA uses the L2 norm. For the L1 PCA problem minimizing the
fitting error of the reconstructed data, we propose an exact reweighted and an
approximate algorithm based on iteratively reweighted least squares. We provide
convergence analyses, and compare their performance against benchmark
algorithms in the literature. The computational experiment shows that the
proposed algorithms consistently perform best.


title: On the Value of the Reconnection Rate

abstract:
  Numerical simulations have consistently shown that the reconnection rate in
certain collisionless regimes can be fast, on the order of $0.1 v_A B_u$, where
$v_A$ and $B_u$ are the Alfv\'en speed and the reconnecting magnetic field
upstream of the ion diffusion region. This particular value has been reported
in myriad numerical simulations under disparate conditions. However, despite
decades of research, the reasons underpinning this specific value remain
mysterious. Here, we present an overview of this problem and discuss the
conditions under which the "0.1 value" is attained. Furthermore, we explain why
this problem should be interpreted in terms of the ion diffusion region length.

categories: physics.plasm-ph astro-ph.HE astro-ph.SR physics.space-ph


title:
Visualization of Au Nanoparticles Buried in a Polymer Matrix by Scanning
  Thermal Noise Microscopy

abstract:
  We demonstrated visualization of Au nanoparticles buried 300 nm into a
polymer matrix by measurement of the thermal noise spectrum of a
microcantilever with a tip in contact to the polymer surface. The subsurface Au
nanoparticles were detected as the variation in the contact stiffness and
damping reflecting the viscoelastic properties of the polymer surface. The
variation in the contact stiffness well agreed with the effective stiffness of
a simple one-dimensional model, which is consistent with the fact that the
maximum depth range of the technique is far beyond the extent of the contact
stress field.


title:
Efficient computation of longest single-arm-gapped palindromes in a
  string

abstract:
  In this paper, we introduce new types of approximate palindromes called
single-arm-gapped palindromes (shortly SAGPs). A SAGP contains a gap in either
its left or right arm, which is in the form of either $wguc u^R w^R$ or $wuc
u^Rgw^R$, where $w$ and $u$ are non-empty strings, $w^R$ and $u^R$ are
respectively the reversed strings of $w$ and $u$, $g$ is a string called a gap,
and $c$ is either a single character or the empty string. Here we call $wu$ and
$u^R w^R$ the arm of the SAGP, and $|uv|$ the length of the arm. We classify
SAGPs into two groups: those which have $ucu^R$ as a maximal palindrome
(type-1), and the others (type-2). We propose several algorithms to compute
type-1 SAGPs with longest arms occurring in a given string, based on suffix
arrays. Then, we propose a linear-time algorithm to compute all type-1 SAGPs
with longest arms, based on suffix trees. Also, we show how to compute type-2
SAGPs with longest arms in linear time. We also perform some preliminary
experiments to show practical performances of the proposed methods.


title: Latin squares with no transversals

abstract:
  A $k$-plex in a latin square of order $n$ is a selection of $kn$ entries that
includes $k$ representatives from each row and column and $k$ occurrences of
each symbol. A $1$-plex is also known as a transversal.
  It is well known that if $n$ is even then $B_n$, the addition table for the
integers modulo $n$, possesses no transversals. We show that there are a great
many latin squares that are similar to $B_n$ and have no transversal. As a
consequence, the number of species of transversal-free latin squares is shown
to be at least $n^{n^{3/2}(1/2-o(1))}$ for even $n\rightarrow\infty$.
  We also produce various constructions for latin squares that have no
transversal but do have a $k$-plex for some odd $k>1$. We prove a 2002
conjecture of the second author that for all even orders $n>4$ there is a latin
square of order $n$ that contains a $3$-plex but no transversal. We also show
that for odd $k$ and $m\geq 2$, there exists a latin square of order $2km$ with
a $k$-plex but no $k'$-plex for odd $k'<k$.