title:
Testing the relativistic precession model using low frequency and kHz
  quasi-periodic oscillations in neutron star low mass X-ray binaries with
  known spin

abstract:
  We analyze all available RXTE data on a sample of 13 low mass X-ray binaries
with known neutron star spin that are not persistent pulsars. We carefully
measure the correlations between the centroid frequencies of the quasi-periodic
oscillations (QPOs). We compare these correlations to the prediction of the
relativistic precession model (RPM) that, due to frame dragging, a QPO will
occur at the Lense-Thirring precession frequency $\nu_{LT}$ of a test particle
orbit whose orbital frequency is the upper kHz QPO frequency $\nu_u$. Contrary
to the most prominent previous studies, we find two different oscillations in
the range predicted for $\nu_{LT}$ that are simultaneously present over a wide
range of $\nu_u$. Additionally, one of the low frequency noise components
evolves into a (third) QPO in the $\nu_{LT}$ range when $\nu_u$ exceeds 600 Hz.
The frequencies of these QPOs all correlate to $\nu_u$ following power laws
with indices between 0.4$-$3.3, significantly exceeding the predicted value of
2.0 in 80$\%$ of the cases (at 3 to >20$\sigma$). Also, there is no evidence
that the neutron star spin frequency affects any of these three QPO frequencies
as would be expected for frame dragging. Finally, the observed QPO frequencies
tend to be higher than the $\nu_{LT}$ predicted for reasonable neutron star
specific moment of inertia. In the light of recent successes of precession
models in black holes, we briefly discuss ways in which such precession can
occur in neutron stars at frequencies different from test particle values and
consistent with those observed. A precessing torus geometry and other torques
than frame dragging may allow precession to produce the observed frequency
correlations, but can only explain one of the three QPOs in the $\nu_{LT}$
range.


title:
A Brownian Particle and Fields I: Construction of Kinematics and
  Dynamics

abstract:
  Tracking a real trajectory of a quantum particle still has been treated as
the interpretation problem. It shall be expressed by a Brownian (stochastic)
motion suggested by E. Nelson, however, the well-defined mechanism of field
generation from a stochastic particle hasn't been proposed yet. For the
improvement of this, I propose the extension of Nelson's quantum dynamics, for
describing a relativistic scalar electron with its radiation equivalent to the
Klein-Gordon particle and field system.


title: X-ray Scintillation in Lead Halide Perovskite Crystals

abstract:
  Current technologies for X-ray detection rely on scintillation from expensive
inorganic crystals grown at high-temperature, which so far has hindered the
development of large-area scintillator arrays. Thanks to the presence of heavy
atoms, solution-grown hybrid lead halide perovskite single crystals exhibit
short X-ray absorption length and excellent detection efficiency. Here we
compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and
MAPbBr3 and two-dimensional (2D) (EDBE)PbCl4 hybrid perovskite crystals. X-ray
excited thermoluminescence measurements indicate the absence of deep traps and
a very small density of shallow trap states, which lessens after-glow effects.
All perovskite single crystals exhibit high X-ray excited luminescence yields
of >120,000 photons/MeV at low temperature. Although thermal quenching is
significant at room temperature, the large exciton binding energy of 2D
(EDBE)PbCl4 significantly reduces thermal effects compared to 3D perovskites,
and moderate light yield of 9,000 photons/MeV can be achieved even at room
temperature. This highlights the potential of 2D metal halide perovskites for
large-area and low-cost scintillator devices for medical, security and
scientific applications.

categories: physics.ins-det cond-mat.mtrl-sci physics.chem-ph physics.optics


title: ALPS II technical overview and status report

abstract:
  The Any Light Particle Search II (ALPS II) is an experiment that utilizes the
concept of resonant enhancement to improve on the sensitivity of traditional
light shining through a wall style experiments. These experiments attempt to
detect photons passing through an opaque wall by converting to relativistic
weakly interacting sub-eV particles and then reconverting back to photons. ALPS
II at DESY in Hamburg, Germany will use dually resonant optical cavities before
and after the wall to increase the probability of this interaction occurring.
This paper gives a technical overview and status report of the experiment.


title: Concentration of the velocity distribution of pulsed neutron beams

abstract:
  The velocity of neutrons from a pulsed neutron source is well-defined as a
function of their arrival time. Electromagnetic neutron accelerator/decelerator
synchronized with the neutron time-of-flight is capable of selectively changing
the neutron velocity and concentrating the velocity distribution. Possible
enhancement of the neutron intensity at a specific neutron velocity by orders
of magnitude is discussed together with an experimental design.

categories: physics.ins-det hep-ex nucl-ex physics.acc-ph


title: Dielectric Haloscopes: A New Way to Detect Axion Dark Matter

abstract:
  We propose a new strategy to search for dark matter axions in the mass range
of 40--400 $\mu$eV by introducing dielectric haloscopes, which consist of
dielectric disks placed in a magnetic field. The changing dielectric media
cause discontinuities in the axion-induced electric field, leading to the
generation of propagating electromagnetic waves to satisfy the continuity
requirements at the interfaces. Large-area disks with adjustable distances
boost the microwave signal (10--100 GHz) to an observable level and allow one
to scan over a broad axion mass range. A sensitivity to QCD axion models is
conceivable with 80 disks of 1 m$^2$ area contained in a $10$ Tesla field.

categories: physics.ins-det astro-ph.CO astro-ph.HE hep-ex hep-ph


title:
The SHARDDS survey: first resolved image of the HD114082 debris disk in
  Lower Centaurus Crux with SPHERE

abstract:
  We present the first resolved image of the debris disk around the 16+/-8 Myr
old star, HD 114082. The observation was made in the H-band using the SPHERE
instrument. The star is at a distance of 92+/-6 pc in the Lower Centaurus Crux
association. Using a Markov Chain Monte Carlo analysis, we determined that the
debris is likely in the form of a dust ring with an inner edge of 27.7+2.8/-3.5
au, position angle -74+0.5/-1.5 deg, and an inclination with respect to the
line of sight of 6.7+3.8/-0.4 deg. The disk imaged in scattered light has a
surface density declining with radius like ~r^(-4), steeper than expected for
grain blowout by radiation pressure. We find only marginal evidence (2 sigma)
of eccentricity, and rule out planets more massive than 1.0 Mjup orbiting
within 1 au of the ring's inner edge, since such a planet would have disrupted
the disk. The disk has roughly the same fractional disk luminosity
(Ldisk/L*=3.3x10^(-3)) as HR4796A and Beta Pictoris, however it was not
detected by previous instrument facilities most likely because of its small
angular size (radius~0.4"), low albedo (~0.2) and low scattering efficiency far
from the star due to high scattering anisotropy. With the arrival of extreme
adaptive optics systems like SPHERE and GPI, the morphology of smaller, fainter
and more distant debris disks are being revealed, providing clues to
planet-disk interactions in young protoplanetary systems.


title:
VALES: II. The physical conditions of interstellar gas in normal
  star-forming galaxies up to z=0.2 revealed by ALMA

abstract:
  We use new Band-3 CO(1-0) observations taken with the Atacama Large
Millimeter/submillimeter Array (ALMA) to study the physical conditions in the
interstellar gas of a sample of 27 dusty main-sequence star-forming galaxies at
0.03<$z$<0.2 present in the Valpara\'iso ALMA Line Emission Survey (VALES). The
sample is drawn from far-IR bright galaxies over $\sim$160 deg$^{2}$ in the
Herschel Astrophysical Terahertz Large Area Survey (HATLAS), which is covered
by Herschel [CII] 158 $\mu$m spectroscopy and far-infrared (FIR) photometry.
The [CII] and CO lines are both detected at >5$\sigma$ in 26 sources. We find
an average [CII] to CO(1-0) luminosity ratio of 3500$\pm$1200 for our sample
that is consistent with previous studies. Using the [CII], CO and FIR
measurements as diagnostics of the physical conditions of the interstellar
medium, we compare these observations to the predictions of a photodissociation
region (PDR) model to determine the gas density, surface temperature, pressure,
and the strength of the incident far-ultraviolet (FUV) radiation field,
$G_{0}$, normalised to the Habing Field. The majority of our sample exhibit
hydrogen densities of 4 < $\log n/\mathrm{cm}^{3}$ < 5.5 and experience an
incident FUV radiation field with strengths of 2 < $\log G_0$ < 3 when adopting
standard adjustments. A comparison to galaxy samples at different redshifts
indicates that the average strength of the FUV radiation field appears constant
up to redshift $z\sim$6.4, yet the neutral gas density increases with redshift
by a factor of $\sim$100, that persists regardless of various adjustments to
our observable quantities. This evolution could provide an explanation for the
observed evolution of the star formation rate density with cosmic time, yet
could arise from a combination of observational biases when using different
suites of emission lines as diagnostic tracers of PDR gas.


title:
The outflow of gas from the Centaurus A circumnuclear disk: atomic
  spectral line maps from Herschel-PACS and APEX

abstract:
  The physical state of the gas in the central 500 pc of NGC~5128 (the radio
galaxy Centaurus A - Cen A), was investigated using the far-infrared
fine-structure lines of carbon, oxygen, and nitrogen, as well as the CO(4-3)
molecular line. The circumnuclear disk (CND) is traced by emission from dust
and the neutral gas ([CI] and CO). A gas outflow with a line-of-sight velocity
of 60 km/s is evident in both species. The center of the CND is bright in [OI],
[OIII], and [CII]; [OI]63mu emission dominates that of [CII] even though it is
absorbed with optical depths of 1.0-1.5. The outflow is well-traced by the
[NII] and [NIII] lines and also seen in the [CII] and [OIII] lines that peak in
the center. Ionized gas densities are moderate in the CND and low everywhere
else. Neutral gas densities range from 4000 per cm3 (outflow, extended thin
disk ETD) to 20 000 per cm3 (CND). The CND radiation field is weak compared to
the ETD starburst field. The outflow has a much stronger radiation field. The
total mass of all the CND gas is 9 x 10^(7) M(o) and the mass of the outflowing
gas is only 15%-30% of that. The outflow most likely originates from the
shock-dominated CND cavity surrounding the central black hole. With a factor of
three uncertainty, the mass outflow rate is about 2 M(o)/yr, a thousand times
higher than the accretion rate of the black hole. Without replenishment, the
CND will be depleted in 15-120 million years. However, the outflow velocity is
well below the escape velocity.


title:
The VIMOS Ultra-Deep Survey: A major merger origin for the high fraction
  of galaxies at $2<z<6$ with two bright clump

abstract:
  (Abridged) The properties of stellar clumps in star forming galaxies and
their evolution over the redshift range $2\lesssim z \lesssim 6$ are presented
and discussed in the context of the build-up of massive galaxies at early
cosmic times. We use HST/ACS images of galaxies with spectroscopic redshifts
from the VIMOS Ultra Deep Survey (VUDS) to identify clumps within a 20 kpc
radius. We find that the population of galaxies with more than one clump is
dominated by galaxies with two clumps, representing $\sim21-25$\% of the
population, while the fraction of galaxies with 3, or 4 and more, clumps is
8-11 and 7-9\%, respectively. The fraction of clumpy galaxies is in the range
$\sim35-55\%$ over $2<z<6$, increasing at higher redshifts, indicating that the
fraction of irregular galaxies remains high up to the highest redshifts. The
large and bright clumps (M$_{\star}\sim10^9$ up to $\sim10^{10}$M$_\odot$) are
found to reside predominantly in galaxies with two clumps. Smaller and lower
luminosity clumps ($\log_{10}\left(M_{\star}/\mathrm{M_\odot}\right)<9$) are
found in galaxies with three clumps or more. We interpret these results as
evidence for two different modes of clump formation working in parallel. The
small low luminosity clumps are likely the result of disc fragmentation, with
violent disc instabilities (VDI) forming several long-lived clumps in-situ, as
suggested from simulations. A fraction of these clumps is also likely coming
from minor mergers. The clumps in the dominating population of galaxies with
two clumps are significantly more massive and have properties akin to those in
merging pairs observed at similar redshifts; they appear as more massive than
the most massive clumps observed in VDI numerical simulations.


title:
Isophote Shapes of Early-Type Galaxies in Massive Clusters at $z\sim1$
  and 0

abstract:
  We compare the isophote shape parameter $a_{4}$ of early-type galaxies (ETGs)
between $z\sim1$ and 0 as a proxy for dynamics to investigate the epoch at
which the dynamical properties of ETGs are established, using cluster ETG
samples with stellar masses of $\log(M_{*}/M_{\odot})\geq10.5$ which have
spectroscopic redshifts. We have 130 ETGs from the Hubble Space Telescope
Cluster Supernova Survey for $z\sim1$ and 355 ETGs from the Sloan Digital Sky
Survey for $z\sim0$. We have developed an isophote shape analysis method which
can be used for high-redshift galaxies and has been carefully compared with
published results. We have applied the same method for both the $z\sim1$ and
$0$ samples. We find similar dependence of the $a_{4}$ parameter on the mass
and size at $z\sim1$ and 0; the main population of ETGs changes from disky to
boxy at a critical stellar mass of $\log(M_{*}/M_{\odot})\sim11.5$ with the
massive end dominated by boxy. The disky ETG fraction decreases with increasing
stellar mass both at $z\sim1$ and $0$, and is consistent between these
redshifts in all stellar mass bins when the Eddington bias is taken into
account. Although uncertainties are large, the results suggest that the
isophote shapes and probably dynamical properties of ETGs in massive clusters
are already in place at $z>1$ and do not significantly evolve in $z<1$, despite
significant size evolution in the same galaxy population. The constant disky
fraction favors less violent processes than mergers as a main cause of the size
and morphological evolution of intermediate mass ETGs in $z<1$.


title: The bound fraction of young star clusters

abstract:
  The residual gas within newly formed star clusters is expelled through
stellar feedback on timescales ~ 1 Myr. The subsequent expansion of the cluster
results in an unbinding of a fraction of stars before the remaining cluster
members can re-virialize and form a surviving cluster. We investigate the bound
fraction after gas expulsion as a function of initial cluster mass in stars and
gauge the influence of primordial mass segregation, stellar evolution and the
tidal field at the solar distance. We also assess the impact of the
star-formation efficiency and gas expulsion velocity. We perform N-body
simulations using Sverre Aarseth's NBODY7 code, starting with compact clusters
in their embedded phase and approximate the gas expulsion by means of an
exponentially depleting external gravitational field. We follow the process of
re-virialization through detailed monitoring of different Lagrange radii over
several Myr, examining initial half-mass radii of 0.1 pc, 0.3 pc and 0.5 pc and
initial masses usually ranging from $5\times10^3 M_\odot$ to $5\times10^4
M_\odot$. The adopted star-formation efficiency of 0.33 in the cluster volume
results in a distinct sensitivity to the gas expulsion velocity over a wide
mass range, while a variation of the star-formation efficiency can make the
cluster robust to the rapidly decreasing external potential. We confirm that
primordial mass segregation leads to a smaller bound fraction, its influence
possibly decreasing with mass. Stellar evolution has a higher impact on lower
mass clusters, but heating through dynamical friction could expand the cluster
to a similar extent. The examined clusters expand well within their tidal radii
and would survive gas expulsion even in a strong tidal field.


title: Excluded-volume effects for a hadron gas in Yang-Mills theory

abstract:
  When the multiplicities of particles produced in heavy-ion collisions are
fitted to the hadron-resonance-gas model, excluded-volume effects play a
significant role. In this work, we study the impact of such effects on the
equation of state of pure Yang-Mills theory at low temperatures, comparing the
predictions of the statistical model with lattice results. In particular, we
present a detailed analysis of the SU(2) and SU(3) Yang-Mills theories: we find
that, for both of them, the best fits to the equilibrium thermodynamic
quantities are obtained when one assumes that the volume of different glueball
states is inversely proportional to their mass. The implications of these
findings for QCD are discussed.


title: Precision Corrections to Fine Tuning in SUSY

abstract:
  Requiring that the contributions of supersymmetric particles to the Higgs
mass are not highly tuned places upper limits on the masses of superpartners --
in particular the higgsino, stop, and gluino. We revisit the details of the
tuning calculation and introduce a number of improvements, including RGE
resummation, two-loop effects, a proper treatment of UV vs. IR masses, and
threshold corrections. This improved calculation more accurately connects the
tuning measure with the physical masses of the superpartners at LHC-accessible
energies. After these refinements, the tuning bound on the stop is now also
sensitive to the masses of the 1st and 2nd generation squarks, which limits how
far these can be decoupled in Effective SUSY scenarios. We find that, for a
fixed level of tuning, our bounds can allow for heavier gluinos and stops than
previously considered. Despite this, the natural region of supersymmetry is
under pressure from the LHC constraints, with high messenger scales
particularly disfavored.


title:
A Second Higgs Doublet in the Early Universe: Baryogenesis and
  Gravitational Waves

abstract:
  We show that simple Two Higgs Doublet models still provide a viable
explanation for the matter-antimatter asymmetry of the Universe via electroweak
baryogenesis, even after taking into account the recent order-of-magnitude
improvement on the electron-EDM experimental bound by the ACME Collaboration.
Moreover we show that, in the region of parameter space where baryogenesis is
possible, the gravitational wave spectrum generated at the end of the
electroweak phase transition is within the sensitivity reach of the future
space-based interferometer LISA.


title: Forecasting Tidal Disruption Events by Binary Black Hole Roulettes

abstract:
  We discuss the gravitational wave emission and the orbital evolution of a
hierarchical triple system composed of an inner binary black hole (BBH) and an
outer tertiary. Depending on the kick velocity at the merger, the merged BBH
could tidally disrupt the tertiary. Even though the fraction of BBH mergers
accompanied by such disruptions is expected to be much smaller than unity, the
existence of a tertiary and its basic parameters (e.g. semimajor axis,
projected mass) can be examined for more than 1000 BBHs with the space GW
detector LISA and its follow-on missions. This allows us to efficiently
prescreen the targets for the follow-up searches for the tidal disruption
events (TDEs). The TDE probability would be significantly higher for triple
systems with aligned orbital- and spin-angular momenta, compared with random
configurations.


title: Galaxy Clusters in the Context of Superfluid Dark Matter

abstract:
  It has recently been proposed, by assuming that dark matter is a superfluid,
that MOND-like effects can be achieved on small scales whilst preserving the
success of $\Lambda$CDM on large scales. Here we aim to provide the first set
of spherical models of galaxy clusters in the context of superfluid dark
matter. We first outline the theoretical structure of the superfluid core and
the surrounding "normal phase" dark halo of quasi-particles in thermal
equlibrium. The latter should encompass the largest part of galaxy clusters.
Here, we set the SfDM transition at the radius where the density and pressure
of the superfluid and normal phase coincides, neglecting the effect of phonons
in the suprefluid core. We then apply the theory to a sample of galaxy
clusters, and directly compare the SfDM predicted mass profiles to data. We
find that the superfluid formulation can reproduce the X-ray dynamical mass
profile of clusters. The SfDM fits however display slight under-predictions of
the gravity in the central regions which might be partly related to our
neglecting of the effect of phonons in these regions. We conclude that this
superfluid formulation is successful in describing galaxy clusters, but further
work will be needed to determine whether the parameter choice is consistent
with galaxies. Our model could be made more realistic by exploring
non-sphericity and the SfDM transition condition we impose.


title: Holographic Dynamics from Multiscale Entanglement Renormalization Ansatz

abstract:
  The Multiscale Entanglement Renormalization Ansatz (MERA) is a tensor network
based variational ansatz that is capable of capturing many of the key physical
properties of strongly correlated ground states such as criticality and
topological order. MERA also shares many deep relationships with the AdS/CFT
(gauge-gravity) correspondence by realizing a UV complete holographic duality
within the tensor networks framework. Motivated by this, we have re-purposed
the MERA tensor network as an analysis tool to study the real-time evolution of
the 1D transverse Ising model in its low energy excited state sector. We
performed this analysis by allowing the ancilla qubits of the MERA tensor
network to acquire quantum fluctuations, which yields a unitary transform
between the physical (boundary) and ancilla qubit (bulk) Hilbert spaces. This
then defines a reversible quantum circuit which is used as a `holographic
transform' to study excited states and their real-time dynamics from the point
of the bulk ancillae. In the gapped paramagnetic phase of the transverse field
Ising model, we demonstrate the holographic duality between excited states
induced by single spin-flips (Ising `magnons') acting on the ground state and
single ancilla qubit spin-flips. The single ancillae qubit excitation is shown
to be stable in the bulk under real-time evolution and hence defines a stable
holographic quasiparticle which we have named the `hologron'. The `dictionary'
between the bulk and boundary is determined and realizes many features of the
holographic correspondence in a non-CFT limit of the boundary theory. As an
added spin-off, this dictionary together with the extension to multi-hologron
sectors gives us a systematic way to construct quantitatively accurate low
energy effective Hamiltonians.


title: Quantum gravity and Standard-Model-like fermions

abstract:
  We discover that chiral symmetry does not act as an infrared attractor of the
renormalization group flow under the impact of quantum gravity fluctuations.
Thus, observationally viable quantum gravity models must respect chiral
symmetry. In our truncation, asymptotically safe gravity does, as a chiral
fixed point exists. A second non-chiral fixed point with massive fermions
provides a template for models with dark matter. This fixed point disappears
for more than 10 fermions, suggesting that an asymptotically safe ultraviolet
completion for the standard model plus gravity enforces chiral symmetry.


title: Reconciling Large And Small-Scale Structure In Twin Higgs Models

abstract:
  We study extensions of the Twin Higgs model that solve the Hierarchy problem
and simultaneously address problems of the large- and small-scale structures of
the Universe. Besides naturally providing dark matter (DM) candidates as the
lightest charged twin fermions, the twin sector contains a light photon and
neutrinos, which can modify structure formation relative to the prediction from
the $\Lambda$CDM paradigm. We focus on two scenarios. First, we study a
Fraternal Twin Higgs model in which the spin-3/2 baryon
$\hat{\Omega}\sim(\hat{b}\hat{b}\hat{b})$ and the lepton twin tau $\hat{\tau}$
contribute to the dominant and subcomponent dark matter densities. A
non-decoupled scattering between the twin tau and twin neutrino arising from a
gauged twin lepton number symmetry provides a drag force that damps the density
inhomogeneity of a dark matter subcomponent. Next, we consider the possibility
of having the twin hydrogen atom $\hat{H}$ as the dominant DM component. After
recombination, a small fraction of the twin protons and leptons remains ionized
during structure formation, and their scattering to twin neutrinos through a
gauged U$(1)_{B-L}$ force provides the mechanism that damps the density
inhomogeneity. Both scenarios realize the Partially Acoustic dark matter
(PAcDM) scenario and explain the $\sigma_8$ discrepancy between the CMB and
weak lensing results. Moreover, the self-scattering neutrino behaves as a dark
fluid that enhances the size of the Hubble rate $H_0$ to accommodate the local
measurement result while satisfying the CMB constraint. For the small-scale
structure, the scattering of $\hat{\Omega}$'s and $\hat{H}$'s through the twin
photon exchange generates a self-interacting dark matter (SIDM) model that
solves the mass deficit problem from dwarf galaxy to galaxy cluster scales.


title:
CHEERS Results from NGC 3393, II: Investigating the Extended Narrow Line
  Region using Deep Chandra Observations and Hubble Narrow Line Imaging

abstract:
  The CHandra Extended Emission Line Region Survey (CHEERS) is an X-ray study
of nearby active galactic nuclei (AGN) designed to take full advantage of
Chandra's unique angular resolution by spatially resolving feedback signatures
and effects. In the second paper of a series on CHEERS target NGC 3393, we
examine deep high-resolution Chandra images and compare them with Hubble narrow
line images of [O III], [S II] and H$\alpha$, as well as previously-unpublished
mid-ultraviolet (MUV) images. The X-rays provide unprecedented evidence that
the S-shaped arms which envelope the nuclear radio outflows extend only
$\lesssim$0.2'' ($\lesssim50 pc$) across. The high-resolution multiwavelength
data suggest that the ENLR is a complex multi-phase structure in the
circumnuclear ISM. Its ionization structure is highly stratified with respect
to outflow-driven bubbles in the bicone and varies dramatically on scales of
~10 pc. Multiple findings show likely contributions from shocks to the feedback
in regions where radio outflows from the AGN most directly influence the ISM.
These findings include H$\alpha$ evidence for gas compression and extended MUV
emission, and are in agreement with existing STIS kinematics. Extended
filamentary structure in the X-rays and optical suggests the presence of an
undetected plasma component, whose existence could be tested with deeper radio
observations.


title: On top quark mass effects to $gg\to ZH$ at NLO

abstract:
  We compute next-to-leading order QCD corrections to the process $gg\to ZH$.
In the effective-theory approach we confirm the results in the literature. We
consider top quark mass corrections via an asymptotic expansion and show that
there is a good convergence below the top quark threshold which describes
approximately {\num a quarter} of the total cross section. Our corrections are
implemented in the publicly available {\tt C++} program {\tt ggzh}.


title:
New constraints on the average escape fraction of Lyman continuum
  radiation in z~4 galaxies from the VIMOS Ultra Deep Survey (VUDS)

abstract:
  Determining the average fraction of Lyman continuum (LyC) photons escaping
high redshift galaxies is essential for understanding how reionization
proceeded in the z>6 Universe. We want to measure the LyC signal from a sample
of sources in the Chandra Deep Field South (CDFS) and COSMOS fields for which
ultra-deep VIMOS spectroscopy as well as multi-wavelength Hubble Space
Telescope (HST) imaging are available.
  We select a sample of 46 galaxies at $z\sim 4$ from the VIMOS Ultra Deep
Survey (VUDS) database, such that the VUDS spectra contain the LyC part of the
spectra, that is, the rest-frame range $880-910\AA$. Taking advantage of the
HST imaging, we apply a careful cleaning procedure and reject all the sources
showing nearby clumps with different colours, that could potentially be
lower-redshift interlopers. After this procedure, the sample is reduced to 33
galaxies. We measure the ratio between ionizing flux (LyC at $895\AA$) and
non-ionizing emission (at $\sim 1500 \AA$) for all individual sources. We also
produce a normalized stacked spectrum of all sources. Assuming an intrinsic
average $L_{\nu}(1470)/L_{\nu}(895)$ of 3, we estimate the individual and
average relative escape fraction. We do not detect ionizing radiation from any
individual source, although we identify a possible LyC emitter with very high
Ly$\alpha$ equivalent width (EW). From the stacked spectrum and assuming a mean
transmissivity for the sample, we measure a relative escape fraction
$f_{esc}^{rel}=0.09\pm0.04$. We also look for correlations between the limits
in the LyC flux and source properties and find a tentative correlation between
LyC flux and the EW of the Ly$\alpha$ emission line.
  Our results imply that the LyC flux emitted by $V=25-26$ star-forming
galaxies at z$\sim$4 is at most very modest, in agreement with previous upper
limits from studies based on broad and narrow band imaging.


title: Towards a measurement of the spectral runnings

abstract:
  Single-field slow-roll inflation predicts a nearly scale-free power spectrum
of perturbations, as observed at the scales accessible to current cosmological
experiments. This spectrum is slightly red, showing a tilt $(1-n_s)\sim 0.04$.
A direct consequence of this tilt are nonvanishing runnings $\alpha_s=\mathrm d
n_s/\mathrm d\log k$, and $\beta_s=\mathrm d\alpha_s/\mathrm d\log k$, which in
the minimal inflationary scenario should reach absolute values of $10^{-3}$ and
$10^{-5}$, respectively. In this work we calculate how well future surveys can
measure these two runnings. We consider a Stage-4 (S4) CMB experiment and show
that it will be able to detect significant deviations from the inflationary
prediction for $\alpha_s$, although not for $\beta_s$. Adding to the S4 CMB
experiment the information from a WFIRST-like or a DESI-like survey improves
the sensitivity to the runnings by $\sim$ 20\%, and 30\%, respectively. A
spectroscopic survey with a billion objects, such as the SKA, will add enough
information to the S4 measurements to allow a detection of $\alpha_s=10^{-3}$,
required to probe the single-field slow-roll inflationary paradigm. We show
that only a very-futuristic interferometer targeting the dark ages will be
capable of measuring the minimal inflationary prediction for $\beta_s$. The
results of other probes, such as a stochastic background of gravitational waves
observable by LIGO, the Ly-$\alpha$ forest, and spectral distortions, are shown
for comparison. Finally, we study the claims that large values of $\beta_s$, if
extrapolated to the smallest scales, can produce primordial black holes of tens
of solar masses, which we show to be easily testable by the S4 CMB experiment.


title:
AGN-enhanced outflows of low-ionization gas in star-forming galaxies at
  1.7<z<4.6

abstract:
  Fast and energetic winds are invoked by galaxy formation models as essential
processes in the evolution of galaxies. These outflows can be powered either by
star-formation and/or AGN activity, but the relative dominance of the two
mechanisms is still under debate. We use spectroscopic stacking analysis to
study the properties of the low-ionization phase of the outflow in a sample of
1330 star-forming galaxies (SFGs) and 79 X-ray detected (42<log(L_X)<45 erg/s)
Type 2 AGN at 1.7<z<4.6 selected from a compilation of deep optical
spectroscopic surveys, mostly zCOSMOS-Deep and VUDS. We measure mean velocity
offsets of -150 km/s in the SFGs while in the AGN sample the velocity is much
higher (-950 km/s), suggesting that the AGN is boosting the outflow up to
velocities that could not be reached only with the star- formation
contribution. The sample of X-ray AGN has on average a lower SFR than non-AGN
SFGs of similar mass: this, combined with the enhanced outflow velocity in AGN
hosts, is consistent with AGN feedback in action. We further divide our sample
of AGN into two X-ray luminosity bins: we measure the same velocity offsets in
both stacked spectra, at odds with results reported for the highly ionized
phase in local AGN, suggesting that the two phases of the outflow may be mixed
only up to relatively low velocities, while the highest velocities can be
reached only by the highly ionized phase.


title: On a Dynamical Mordell-Lang Conjecture for Coherent Sheaves

abstract:
  We introduce a dynamical Mordell-Lang-type conjecture for coherent sheaves.
When the sheaves are structure sheaves of closed subschemes, our conjecture
becomes a statement about unlikely intersections. We prove an analogue of this
conjecture for affinoid spaces, which we then use to prove our conjecture in
the case of surfaces. These results rely on a module-theoretic variant of
Strassman's theorem that we prove in the appendix.


title: The Origin of the Heaviest Metals in Most Ultra-Faint Dwarf Galaxies

abstract:
  The heaviest metals found in stars in most ultra-faint dwarf (UFD) galaxies
in the Milky Way halo are generally underabundant by an order of magnitude or
more when compared with stars in the halo field. Among the heavy elements
produced by n-capture reactions, only Sr and Ba can be detected in red giant
stars in most UFD galaxies. This limited chemical information is unable to
identify the nucleosynthesis process(es) responsible for producing the heavy
elements in UFD galaxies. Similar [Sr/Ba] and [Ba/Fe] ratios are found in three
bright halo field stars, BD-18 5550, CS 22185-007, and CS 22891-200. Previous
studies of high-quality spectra of these stars report detections of additional
n-capture elements, including Eu. The [Eu/Ba] ratios in these stars span +0.41
to +0.86. These ratios and others among elements in the rare earth domain
indicate an r-process origin. These stars have some of the lowest levels of
r-process enhancement known, with [Eu/H] spanning -3.95 to -3.32, and they may
be considered nearby proxies for faint stars in UFD galaxies. Direct
confirmation, however, must await future observations of additional heavy
elements in stars in the UFD galaxies themselves.


title: Quantized circular photogalvanic effect in Weyl semimetals

abstract:
  The circular photogalvanic effect (CPGE) is the part of a photocurrent that
switches depending on the sense of circular polarization of the incident light.
It has been consistently observed in systems without inversion symmetry and
depends on non-universal material details. Here we find that in a class of Weyl
semimetals (e.g. SrSi$_2$) and three-dimensional Rashba materials (e.g. doped
Te) without inversion and mirror symmetries, the injection contribution to the
CPGE trace is effectively quantized in terms of the fundamental constants $e,
h, c$ and $\epsilon_0$ with no material-dependent parameters. This is so
because the CPGE directly measures the topological charge of Weyl points, and
non-quantized corrections from disorder and additional bands can be small over
a significant range of incident frequencies. Moreover, the magnitude of the
CPGE induced by a Weyl node is relatively large, which enables the direct
detection of the monopole charge with current techniques.


title: Blue diffuse dwarf galaxies: a clearer picture

abstract:
  The search for chemically unevolved galaxies remains prevalent in the nearby
Universe, mostly because these systems provide excellent proxies for exploring
in detail the physics of high-z systems. The most promising candidates are
extremely metal-poor galaxies (XMPs), i.e., galaxies with <1/10 solar
metallicity. However, due to the bright emission line based search criteria
traditionally used to find XMPs, we may not be sampling the full XMP
population. In 2014 we reoriented this search using only morphological
properties and uncovered a population of ~150 `blue diffuse dwarf (BDD)
galaxies', and published a sub-sample of 12 BDD spectra. Here we present
optical spectroscopic observations of a larger sample of 51 BDDs, along with
their SDSS photometric properties. With our improved statistics, we use
direct-method abundances to confirm that BDDs are chemically unevolved
(7.43<12+log(O/H)<8.01), with ~20% of our sample classified as being XMP
galaxies, and find they are actively forming stars at rates of 1-33x10^-2
M_sol/yr in HII regions randomly embedded in a blue, low-surface brightness
continuum. Stellar masses are calculated from population synthesis models and
estimated to be in the range log(M_star/M_sol) ~5-9. Unlike other
low-metallicity star-forming galaxies, BDDs are in agreement with the
mass-metallicity relation at low masses, suggesting they are not accreting
large amounts of pristine gas relative to their stellar mass. BDD galaxies
appear to be a population of actively star-forming dwarf irregular (dIrr)
galaxies who fall within the class of low-surface brightness dIrr galaxies.
Their ongoing star-formation and irregular morphology make them excellent
analogues for galaxies in the early Universe.


title: Renormalized stress-energy tensor for stationary black holes

abstract:
  We continue the presentation of the pragmatic mode-sum regularization (PMR)
method for computing the renormalized stress-energy tensor (RSET). We show in
detail how to employ the $t$-splitting variant of the method, which was first
presented for $\left\langle\phi^{2}\right\rangle_{ren}$, to compute the RSET in
a stationary, asymptotically-flat background. This variant of the PMR method
was recently used to compute the RSET for an evaporating spinning black hole.
As an example for regularization, we demonstrate here the computation of the
RSET for a minimally-coupled, massless scalar field on Schwarzschild background
in all three vacuum states. We discuss future work and possible improvements of
the regularization schemes in the PMR method.


title:
Universal quantum gates for Quantum Computation on magnetic systems
  ruled by Heisenberg-Ising interactions

abstract:
  The gate version of quantum computation exploits several quantum key
resources as superposition and entanglement to reach an outstanding
performance. In the way, this theory was constructed adopting certain supposed
processes imitating classical computer gates. As for optical as well as
magnetic systems, those gates are obtained as quantum evolutions. Despite, in
certain cases they are attained as an asymptotic series of evolution effects.
The current work exploits the direct sum of the evolution operator on a
non-local basis for the driven bipartite Heisenberg-Ising model to construct a
set of equivalent universal gates as straight evolutions for this interaction.
The prescriptions to get these gates are reported as well as a general
procedure to evaluate their performance.


title:
Sampling algorithms for validation of supervised learning models for
  Ising-like systems

abstract:
  In this paper, we build and explore supervised learning models of
ferromagnetic system behavior, using Monte-Carlo sampling of the spin
configuration space generated by the 2D Ising model. Given the enormous size of
the space of all possible Ising model realizations, the question arises as to
how to choose a reasonable number of samples that will form physically
meaningful and non-intersecting training and testing datasets. Here, we propose
a sampling technique called ID-MH that uses the Metropolis-Hastings algorithm
creating Markov process across energy levels within the predefined
configuration subspace. We show that application of this method retains phase
transitions in both training and testing datasets and serves the purpose of
validation of a machine learning algorithm. For larger lattice dimensions,
ID-MH is not feasible as it requires knowledge of the complete configuration
space. As such, we develop a new "block-ID" sampling strategy: it decomposes
the given structure into square blocks with lattice dimension no greater than 5
and uses ID-MH sampling of candidate blocks. Further comparison of the
performance of commonly used machine learning methods such as random forests,
decision trees, k nearest neighbors and artificial neural networks shows that
the PCA-based Decision Tree regressor is the most accurate predictor of
magnetizations of the Ising model. For energies, however, the accuracy of
prediction is not satisfactory, highlighting the need to consider more
algorithmically complex methods (e.g., deep learning).


title:
Constraints on dark matter scenarios from measurements of the galaxy
  luminosity function at high redshifts

abstract:
  We use state-of-art measurements of the galaxy luminosity function (LF) at
z=6, 7 and 8 to derive constraints on warm dark matter (WDM), late-forming dark
matter (LFDM) and ultra-light axion dark matter (ULADM) models alternative to
the cold dark matter (CDM) paradigm. To this purpose we have run a suite of
high-resolution N-body simulations to accurately characterise the low mass-end
of the halo mass function and derive DM model predictions of the high-z
luminosity function. In order to convert halo masses into UV-magnitudes we
introduce an empirical approach based on halo abundance matching which allows
us to model the LF in terms of the amplitude and scatter of the ensemble
average star formation rate halo mass relation of each DM model, $\langle {\rm
SFR}({\rm M_{ h}},z)\rangle$. We find that independent of the DM scenario the
average SFR at fixed halo mass increases from z=6 to 8, while the scatter
remains constant. At halo mass ${\rm M_{h}}\gtrsim 10^{12}\,{\rm M}_\odot$
h$^{-1}$ the average SFR as function of halo mass follows a double power law
trend that is common to all models, while differences occur at smaller masses.
In particular, we find that models with a suppressed low-mass halo abundance
exhibit higher SFR compared to the CDM results. Using deviance statistics we
obtain a lower limit on the WDM thermal relic particle mass, $m_{\rm
WDM}\gtrsim 1.5$ keV at $2\sigma$. In the case of LFDM models, the phase
transition redshift parameter is bounded to $z_t\gtrsim 8\cdot 10^5$ at
$2\sigma$. We find ULADM best-fit models with axion mass $m_a\gtrsim 1.6\cdot
10^{-22}$ eV to be well within $2\sigma$ of the deviance statistics. We remark
that measurements at $z=6$ slightly favour a flattening of the LF at faint
UV-magnitudes. This tends to prefer some of the non-CDM models in our
simulation suite, although not at a statistically significant level to
distinguish them from CDM.


title:
Parallel pumping for magnon spintronics: Amplification and manipulation
  of magnon spin currents on the micron-scale

abstract:
  Magnonics and magnon spintronics aim at the utilization of spin waves and
magnons, their quanta, for the construction of wave-based logic networks via
the generation of pure all-magnon spin currents and their interfacing with
electrical charge transport. The promise of efficient parallel data processing
and low power consumption renders this field one of the most promising research
areas in spintronics. In this context, the process of parallel parametric
amplification, i.e., the conversion of microwave photons into magnons at one
half of the microwave frequency, has proven to be a versatile tool. Its
beneficial and unique properties, such as frequency and mode-selectivity, the
possibility to excite spin waves in a wide wavevector range and the creation of
phase-correlated wave pairs, render it one of the key methods of spin-wave
generation and amplification.
  The application of parallel parametric amplification to micro- and
nanostructures is an important step towards the realization of magnonic
networks. This is motivated not only by the fact that amplifiers are an
important tool for the construction of any extended logic network but also by
the unique properties of parallel parametric amplification, such as a
phase-dependent amplification. Recently, the successful application of parallel
parametric amplification to metallic microstructures has been reported. It has
been demonstrated that parametric amplification provides an excellent tool to
generate and to amplify spin waves in these systems. In particular, the
amplification greatly benefits from the discreteness of the spin-wave spectra.
This opens up new, interesting routes of spin-wave amplification and
manipulation. In this Review, we give an overview over the recent developments
and achievements in this field.


title:
Nonuniform dependence on initial data for compressible gas dynamics: The
  Cauchy problem on $\mathbb{R}^2$

abstract:
  The Cauchy problem for the two dimensional compressible Euler equations with
data in the Sobolev space $H^s(\mathbb R^2)$ is known to have a unique solution
of the same Sobolev class for a short time, and the data-to-solution map is
continuous. We prove that the data-to-solution map on the plane is not
uniformly continuous on any bounded subset of Sobolev class functions.


title: Absence of many-body localization in a continuum

abstract:
  We show that many-body localization, which exists in tight-binding models, is
unstable in a continuum. Irrespective of the dimensionality of the system,
many-body localization does not survive the unbounded growth of the
single-particle localization length with increasing energy that is
characteristic of the continuum limit. The system remains delocalized down to
arbitrarily small temperature $T$, although its dynamics slows down as $T$
decreases. Remarkably, the conductivity vanishes with decreasing $T$ faster
than in the Arrhenius law. The system can be characterized by an effective
$T$-dependent single-particle mobility edge which diverges in the limit of
$T\to 0$. Delocalization is driven by interactions between hot electrons above
the mobility edge and the "bath" of thermal electrons in the vicinity of the
Fermi level.


title:
Answering Image Riddles using Vision and Reasoning through Probabilistic
  Soft Logic

abstract:
  In this work, we explore a genre of puzzles ("image riddles") which involves
a set of images and a question. Answering these puzzles require both
capabilities involving visual detection (including object, activity
recognition) and, knowledge-based or commonsense reasoning. We compile a
dataset of over 3k riddles where each riddle consists of 4 images and a
groundtruth answer. The annotations are validated using crowd-sourced
evaluation. We also define an automatic evaluation metric to track future
progress. Our task bears similarity with the commonly known IQ tasks such as
analogy solving, sequence filling that are often used to test intelligence.
  We develop a Probabilistic Reasoning-based approach that utilizes
probabilistic commonsense knowledge to answer these riddles with a reasonable
accuracy. We demonstrate the results of our approach using both automatic and
human evaluations. Our approach achieves some promising results for these
riddles and provides a strong baseline for future attempts. We make the entire
dataset and related materials publicly available to the community in
ImageRiddle Website (http://bit.ly/22f9Ala).


title: Geometrical Aspects of Venus Transit

abstract:
  We obtained two astronomical values, the Earth-Venus distance and Venus
diameter, by means of a geometrical treatment of photos taken of Venus transit
in June of 2012. Here we presented the static and translational modelsthat were
elaborated taking into account the Earth and Venus orbital movements. An
additional correction was also added by considering the Earth rotation
movement. The results obtained were compared with the values of reference from
literature, showing very good concordance.


title: Associative Memories to Accelerate Approximate Nearest Neighbor Search

abstract:
  Nearest neighbor search is a very active field in machine learning for it
appears in many application cases, including classification and object
retrieval. In its canonical version, the complexity of the search is linear
with both the dimension and the cardinal of the collection of vectors the
search is performed in. Recently many works have focused on reducing the
dimension of vectors using quantization techniques or hashing, while providing
an approximate result. In this paper we focus instead on tackling the cardinal
of the collection of vectors. Namely, we introduce a technique that partitions
the collection of vectors and stores each part in its own associative memory.
When a query vector is given to the system, associative memories are polled to
identify which one contain the closest match. Then an exhaustive search is
conducted only on the part of vectors stored in the selected associative
memory. We study the effectiveness of the system when messages to store are
generated from i.i.d. uniform $\pm$1 random variables or 0-1 sparse i.i.d.
random variables. We also conduct experiment on both synthetic data and real
data and show it is possible to achieve interesting trade-offs between
complexity and accuracy.


title:
Random walks on homogeneous spaces and diophantine approximation on
  fractals

abstract:
  We extend results of Y. Benoist and J.-F. Quint concerning random walks on
homogeneous spaces of simple Lie groups to the case where the measure defining
the random walk generates a semigroup which is not necessarily Zariski dense,
but satisfies some expansion properties for the adjoint action. Using these
dynamical results, we study diophantine properties of typical points on some
self-similar fractals in R^d. As examples, we show that for any self-similar
fractal K in R^d satisfying the open set condition (for instance any translate
or dilate of Cantor's middle thirds set or of a Koch snowflake), almost every
point with respect to the natural measure on K is not badly approximable.
Furthermore, almost every point on the fractal is of generic type, which
implies (in the one dimensional case) that its continued fraction expansion
contains all finite words with the frequencies predicted by Gauss measure. We
prove analogous results for matrix multiplication, and for the case of fractals
defined by Mobius transformation.


title: 511 keV Line Emission from Nearby Spherical Dwarf Galaxies

abstract:
  The observed galactic 511 keV line has been interpreted in a number of papers
as a possible signal of dark matter annihilation within the galactic bulge. If
this is the case then we should expect a similar spectral feature associated
with nearby dwarf galaxies which are dark matter dominated. It has recently
been argued [1] that the absence of such a signal excludes a dark matter
explanation as the major source for the galactic 511 keV line. In the model
presented here dark matter in the form of heavy quark nuggets produces the
galactic 511 keV emission line through interactions with the visible matter. It
is argued, however, that this type of interaction is not subject to the strong
dark matter annihilation constraints presented in [1].


title: D-finite Numbers

abstract:
  D-finite functions and P-recursive sequences are defined in terms of linear
differential and recurrence equations with polynomial coefficients. In this
paper, we introduce a class of numbers closely related to D-finite functions
and P-recursive sequences. It consists of the limits of convergent P-recursive
sequences. Typically, this class contains many well-known mathematical
constants in addition to the algebraic numbers. Our definition of the class of
D-finite numbers depends on two subrings of the field of complex numbers. We
investigate how different choices of these two subrings affect the class.
Moreover, we show that D-finite numbers are essentially limits of D-finite
functions at the point one, and evaluating D-finite functions at non-singular
algebraic points typically yields D-finite numbers. This result makes it easier
to recognize certain numbers to be D-finite.


title:
Practical heteroskedastic Gaussian process modeling for large simulation
  experiments

abstract:
  We present a unified view of likelihood based Gaussian progress regression
for simulation experiments exhibiting input-dependent noise. Replication plays
an important role in that context, however previous methods leveraging
replicates have either ignored the computational savings that come from such
design, or have short-cut full likelihood-based inference to remain tractable.
Starting with homoskedastic processes, we show how multiple applications of a
well-known Woodbury identity facilitate inference for all parameters under the
likelihood (without approximation), bypassing the typical full-data sized
calculations. We then borrow a latent-variable idea from machine learning to
address heteroskedasticity, adapting it to work within the same thrifty
inferential framework, thereby simultaneously leveraging the computational and
statistical efficiency of designs with replication. The result is an
inferential scheme that can be characterized as single objective function,
complete with closed form derivatives, for rapid library-based optimization.
Illustrations are provided, including real-world simulation experiments from
manufacturing and the management of epidemics.


title: Moderate deviations principle for systems of slow-fast diffusions

abstract:
  In this paper, we prove the moderate deviations principle (MDP) for a general
system of slow-fast dynamics. We provide a unified approach, based on weak
convergence ideas and stochastic control arguments, that cover both the
averaging and the homogenization regimes. We allow the coefficients to be in
the whole space and not just the torus and allow the noises driving the slow
and fast processes to be correlated arbitrarily. Similar to the large deviation
case, the methodology that we follow allows construction of provably efficient
Monte Carlo methods for rare events that fall into the moderate deviations
regime.


title:
Anisotropy induces non-Fermi-liquid behavior and nematic magnetic order
  in three-dimensional Luttinger semimetals

abstract:
  We illuminate the intriguing role played by spatial anisotropy in
three-dimensional Luttinger semimetals featuring quadratic band touching and
long-range Coulomb interactions. We observe the anisotropy to be subject to an
exceptionally slow renormalization group (RG) evolution so that it can be
considered approximately constant when computing the impact of quantum
fluctuations on the remaining couplings of the system. Using perturbative RG we
then study the competition of all local short-range interactions that are
generated from the long-range interactions for fixed anisotropy. Two main
effects come to light for sufficiently strong anisotropy. First, the
three-dimensional system features an Abrikosov non-Fermi liquid ground state.
Second, there appear qualitatively new fixed points which describe quantum
phase transitions into phases with nemagnetic orders - higher-rank tensor
orders that break time-reversal symmetry, and thus have both nematic and
magnetic character. In real materials these phases may be realized through
sufficiently strong microscopic short-range interactions. On the pyrochlore
lattice, the anisotropy-induced fixed points determine the onset of
all-in-all-out or spin ice ordering of local magnetic moments of the electrons.

categories: cond-mat.str-el cond-mat.stat-mech cond-mat.supr-con hep-th


title: WAY beyond conservation laws

abstract:
  The ability to measure every quantum observable is ensured by a fundamental
result in quantum measurement theory. Nevertheless, additive conservation laws
associated with physical symmetries, such as the angular momentum conservation,
may lead to restrictions on the measurability of the observables. Such
limitations are imposed by the theorem of Wigner, Araki and Yanase (WAY). In
this paper a new formulation of the WAY-theorem is presented rephrasing the
measurability limitations in terms of quantum incompatibility. This broader
mathematical basis enables us to both capture and generalise the WAY-theorem by
allowing to drop the assumptions of additivity and even conservation of the
involved quantities. Moreover, we extend the WAY-theorem to the general level
of positive operator valued measures.


title: Soft Gravitons and the Flat Space Limit of Anti-deSitter Space

abstract:
  We argue that flat space amplitudes for the process $ 2 \to n$ gravitons at
center of mass energies $\sqrt{s}$ much less than the Planck scale, will
coincide approximately with amplitudes calculated from correlators of a
boundary CFT for AdS space of radius $R\gg L_P$, only when $n < R/L_P$ . For
larger values of $n$ in AdS space, insisting that all the incoming energy
enters "the arena" [arXiv:hep-th/9901079], implies the production of black
holes, whereas there is no black hole production in the flat space amplitudes.
We also argue, from unitarity, that flat space amplitudes for all $n$ are
necessary to reconstruct the complicated singularity at zero momentum in the $2
\to 2$ amplitude, which can therefore not be reproduced as the limit of an AdS
calculation. Applying similar reasoning to amplitudes for real black hole
production in flat space, we argue that unitarity of the flat space S-matrix
cannot be assessed or inferred from properties of CFT correlators.


title: On the Query Complexity of Black-Peg AB-Mastermind

abstract:
  Mastermind game is a two players zero sum game of imperfect information. The
first player, called codemaker, chooses a secret code and the second player,
called codebreaker, tries to break the secret code by making as few guesses as
possible, exploiting information that is given by the codemaker after each
guess. In this paper, we consider the so called Black-Peg variant of
Mastermind, where the only information concerning a guess is the number of
positions in which the guess coincides with the secret code. More precisely, we
deal with a special version of the Black-Peg game with n holes and k<=n colors
where no repetition of colors is allowed. We present upper and lower bounds on
the number of guesses necessary to break the secret code. We first come back to
the upper bound results introduced by El Ouali and Sauerland (2013). For the
case k=n the secret code can be algorithmically identified within less than
(n-3)*ld(n)+5n/2 queries. That result improves the result of Ker-I Ko and
Shia-Chung Teng (1985) by almost a factor of 2. For the case k>n we prove an
upper bound for the problem of (n-1)*ld(n)+k+1. Furthermore we prove a new
lower bound for (a generalization of) the case k=n that improves the recent
result of Berger et al. (2016) from n-log(log(n)) to n. We also give a lower
bound of k queries for the case k>n.


title:
Multi-valley envelope function equations and effective potentials for P
  impurity in silicon

abstract:
  We propose a system of real-space envelope function equations without fitting
parameters for modeling the electronic spectrum and wave functions of a
phosphorus donor atom embedded in silicon. The approach relies on the
Burt-Foreman envelope function representation and leads to coupled
effective-mass Schroedinger equations containing smooth effective potentials.
These potentials result from the spatial filtering imposed on the exact
potential energy matrix elements in the envelope function representation. The
corresponding filter function is determined from the definition of the envelope
function. The resulting effective potentials and the system of envelope
functions jointly reproduce the valley-orbit coupling effect in the doped
silicon. Including the valley-orbit coupling not only of the 1s, but also for
2s atomic orbitals, as well as static dielectric screening is found crucial to
accurately reproduce experimental data. The measured binding energies are
recovered with a maximum relative error of 1.53 %. The computed wave functions
are in a good agreement with experimental measurements of the electron density
provided by scanning tunneling microscopy.


title:
Comparison of Bayesian and Frequentist Multiplicity Correction For
  Testing Mutually Exclusive Hypotheses Under Data Dependence

abstract:
  The problem of testing mutually exclusive hypotheses with dependent test
statistics is considered. Bayesian and frequentist approaches to multiplicity
control are studied and compared to help gain understanding as to the effect of
test statistic dependence on each approach. The Bayesian approach is shown to
have excellent frequentist properties and is argued to be the most effective
way of obtaining frequentist multiplicity control, without sacrificing power,
when there is considerable test statistic dependence.


title:
Wirelessly Powered Urban Crowd Sensing over Wearables: Trading Energy
  for Data

abstract:
  In this article, we put forward the mobile crowd sensing paradigm based on
ubiquitous wearable devices carried by human users. The key challenge for mass
user involvement into prospective urban crowd sending applications, such as
monitoring of large-scale phenomena (e.g., traffic congestion and air pollution
levels), is the appropriate sources of motivation. We thus advocate for the use
of wireless power transfer provided in exchange for sensed data to incentivize
the owners of wearables to participate in collaborative data collection. Based
on this construction, we develop the novel concept of wirelessly powered crowd
sensing and offer the corresponding network architecture considerations
together with a systematic review of wireless charging techniques to implement
it. Further, we contribute a detailed system-level feasibility study that
reports on the achievable performance levels for the envisioned setup. Finally,
the underlying energy-data trading mechanisms are discussed, and the work is
concluded with outlining open research opportunities.


title: Computing Absolutely Normal Numbers in Nearly Linear Time

abstract:
  A real number $x$ is absolutely normal if, for every base $b\ge 2$, every two
equally long strings of digits appear with equal asymptotic frequency in the
base-$b$ expansion of $x$. This paper presents an explicit algorithm that
generates the binary expansion of an absolutely normal number $x$, with the
$n$th bit of $x$ appearing after $n$polylog$(n)$ computation steps. This speed
is achieved by simultaneously computing and diagonalizing against a martingale
that incorporates Lempel-Ziv parsing algorithms in all bases.


title: Collisional super-Penrose process and Wald inequalities

abstract:
  We consider collision of two massive particles in the equatorial plane of an
axially symmetric stationary spacetime that produces two massless particles
afterwards. It is implied that the horizon is absent but there is a naked
singularity or another potential barrier that makes possible the head-on
collision. The relationship between the energy in the center of mass frame
$E_{c.m.}$ and the Killing energy $E$ measured at infinity is analyzed. It
follows immediately from the Wald inequalities that unbounded $E$ is possible
for unbounded $E_{c.m.}$ only. This can be realized if the spacetime is close
to the threshold of the horizon formation. Different types of spacetimes (black
holes, naked singularities, wormholes) correspond to different possible
relations between $E_{c.m.}$ and $E$. We develop a general approach that
enables us to describe the collision process in the frames of the stationary
observer and ZAMO (zero angular momentum observer). The escape cone and escape
fraction are derived. A simple explanation of the existence of the bright spot
is given. For the particular case of the Kerr metric, our results agree with
the previous ones found in M. Patil, T. Harada, K. Nakao, P.S. Joshi, and M.
Kimura, Phys. Rev. D 93, 104015 (2016).


title: Distortion and the automorphism group of a shift

abstract:
  The set of automorphisms of a one-dimensional \shift $(X, \sigma)$ forms a
countable, but often very complicated, group. For zero entropy shifts, it has
recently been shown that the automorphism group is more tame. We provide the
first examples of countable groups that cannot embed into the automorphism
group of any zero entropy \shiftno. In particular, we show that the
Baumslag-Solitar groups ${\rm BS}(1,n)$ and all other groups that contain
exponentially distorted elements cannot embed into ${\rm Aut}(X)$ when $h_{{\rm
top}}(X)=0$. We further show that distortion in nilpotent groups gives a
nontrivial obstruction to embedding such a group in any low complexity shift.


title: ANTARES: Progress towards building a `Broker' of time-domain alerts

abstract:
  The Arizona-NOAO Temporal Analysis and Response to Events System (ANTARES) is
a joint effort of NOAO and the Department of Computer Science at the University
of Arizona to build prototype software to process alerts from time-domain
surveys, especially LSST, to identify those alerts that must be followed up
immediately. Value is added by annotating incoming alerts with existing
information from previous surveys and compilations across the electromagnetic
spectrum and from the history of past alerts. Comparison against a knowledge
repository of properties and features of known or predicted kinds of variable
phenomena is used for categorization. The architecture and algorithms being
employed are described.


title:
Generative One-Class Models for Text-based Person Retrieval in Forensic
  Applications

abstract:
  Automatic forensic image analysis assists criminal investigation experts in
the search for suspicious persons, abnormal behaviors detection and identity
matching in images. In this paper we propose a person retrieval system that
uses textual queries (e.g., "black trousers and green shirt") as descriptions
and a one-class generative color model with outlier filtering to represent the
images both to train the models and to perform the search. The method is
evaluated in terms of its efficiency in fulfilling the needs of a forensic
retrieval system: limited annotation, robustness, extensibility, adaptability
and computational cost. The proposed generative method is compared to a
corresponding discriminative approach. Experiments are carried out using a
range of queries in three different databases. The experiments show that the
two evaluated algorithms provide average retrieval performance and adaptable to
new datasets. The proposed generative algorithm has some advantages over the
discriminative one, specifically its capability to work with very few training
samples and its much lower computational requirements when the number of
training examples increases.


title:
Squared Earth Mover's Distance-based Loss for Training Deep Neural
  Networks

abstract:
  In the context of single-label classification, despite the huge success of
deep learning, the commonly used cross-entropy loss function ignores the
intricate inter-class relationships that often exist in real-life tasks such as
age classification. In this work, we propose to leverage these relationships
between classes by training deep nets with the exact squared Earth Mover's
Distance (also known as Wasserstein distance) for single-label classification.
The squared EMD loss uses the predicted probabilities of all classes and
penalizes the miss-predictions according to a ground distance matrix that
quantifies the dissimilarities between classes. We demonstrate that on datasets
with strong inter-class relationships such as an ordering between classes, our
exact squared EMD losses yield new state-of-the-art results. Furthermore, we
propose a method to automatically learn this matrix using the CNN's own
features during training. We show that our method can learn a ground distance
matrix efficiently with no inter-class relationship priors and yield the same
performance gain. Finally, we show that our method can be generalized to
applications that lack strong inter-class relationships and still maintain
state-of-the-art performance. Therefore, with limited computational overhead,
one can always deploy the proposed loss function on any dataset over the
conventional cross-entropy.


title: Maximum a Posteriori Estimators as a Limit of Bayes Estimators

abstract:
  Maximum a posteriori and Bayes estimators are two common methods of point
estimation in Bayesian Statistics. It is commonly accepted that maximum a
posteriori estimators are a limiting case of Bayes estimators with 0-1 loss. In
this paper, we provide a counterexample which shows that in general this claim
is false. We then correct the claim that by providing a level-set condition for
posterior densities such that the result holds. Since both estimators are
defined in terms of optimization problems, the tools of variational analysis
find a natural application to Bayesian point estimation.


title:
Morphology of Fly Larval Class IV Dendrites Accords with a Random
  Branching and Contact Based Branch Deletion Model

abstract:
  Dendrites are branched neuronal processes that receive input signals from
other neurons or the outside world [1]. To maintain connectivity as the
organism grows, dendrites must also continue to grow. For example, the
dendrites in the peripheral nervous system continue to grow and branch to
maintain proper coverage of their receptor fields [2, 3, 4, 5]. One such neuron
is the Drosophila melanogaster class IV dendritic arborization neuron [6]. The
dendritic arbors of these neurons tile the larval surface [7], where they
detect localized noxious stimuli, such as jabs from parasitic wasps [8]. In the
present study, we used a novel measure, the hitting probability, to show that
the class IV neuron forms a tight mesh that covers the larval surface.
Furthermore, we found that the mesh size remains largely unchanged during the
larval stages, despite a dramatic increase in overall size of the neuron and
the larva. We also found that the class IV dendrites are dense (assayed with
the fractal dimension) and uniform (assayed with the lacunarity) throughout the
larval stages. To understand how the class IV neuron maintains its morphology
during larval development, we constructed a mathematical model based on random
branching and self-avoidance. We found that if the branching rate is uniform in
space and time and that if all contacting branches are deleted, we can
reproduce the branch length distribution, mesh size and density of the class IV
dendrites throughout the larval stages. Thus, a simple set of statistical rules
can generate and maintain a complex branching morphology during growth.


title:
Steklov zeta-invariants and a compactness theorem for isospectral
  families of planar domains

abstract:
  The inverse problem of recovering a smooth simply connected multisheet planar
domain from its Steklov spectrum is equivalent to the problem of determination,
up to a gauge transform, of a smooth positive function $a$ on the unit circle
from the spectrum of the operator $a\Lambda$, where $\Lambda$ is the
Dirichlet-to-Neumann operator of the unit disk. Zeta-invariants are defined by
$Z_m(a)={\rm Tr}[(a\Lambda)^{2m}-(aD)^{2m}]$ for every smooth function $a$. In
the case of a positive $a$, zeta-invariants are determined by the Steklov
spectrum. We obtain some estimate from below for $Z_m(a)$ in the case of a real
function $a$. On using the estimate, we prove the compactness of a Steklov
isospectral family of planar domains in the $C^\infty$-topology. We also
describe all real functions $a$ satisfying $Z_m(a)=0$.


title: Electromagnetic Duality and Entanglement Anomalies

abstract:
  Duality is an indispensable tool for describing the strong-coupling dynamics
of gauge theories. However, its actual realization is often quite subtle:
quantities such as the partition function can transform covariantly, with
degrees of freedom rearranged in a nonlocal fashion. We study this phenomenon
in the context of the electromagnetic duality of abelian $p$-forms. A careful
calculation of the duality anomaly on an arbitrary $D$-dimensional manifold
shows that the effective actions agree exactly in odd $D$, while in even $D$
they differ by a term proportional to the Euler number. Despite this anomaly,
the trace of the stress tensor agrees between the dual theories. We also
compute the change in the vacuum entanglement entropy under duality, relating
this entanglement anomaly to the duality of an "edge mode" theory in two fewer
dimensions. Previous work on this subject has led to conflicting results; we
explain and resolve these discrepancies.


title: Zariski Density and Computing in Arithmetic Groups

abstract:
  For $n > 2$, let $\Gamma$ denote either $SL(n, Z)$ or $Sp(n, Z)$. We give a
practical algorithm to compute the level of the maximal principal congruence
subgroup in an arithmetic group $H\leq \Gamma$. This forms the main component
of our methods for computing with such arithmetic groups $H$. More generally,
we provide algorithms for computing with Zariski dense groups in $\Gamma$. We
use our GAP implementation of the algorithms to solve problems that have
emerged recently for important classes of linear groups.


title:
Completeness of the Bethe Ansatz for an open $q$-boson system with
  integrable boundary interactions

abstract:
  We employ a discrete integral-reflection representation of the double affine
Hecke algebra of type $C^\vee C$ at the critical level q=1, to endow the open
finite $q$-boson system with integrable boundary interactions at the lattice
ends. It is shown that the Bethe Ansatz entails a complete basis of
eigenfunctions for the commuting quantum integrals in terms of Macdonald's
three-parameter hyperoctahedral Hall-Littlewood polynomials.


title:
"Influence Sketching": Finding Influential Samples In Large-Scale
  Regressions

abstract:
  There is an especially strong need in modern large-scale data analysis to
prioritize samples for manual inspection. For example, the inspection could
target important mislabeled samples or key vulnerabilities exploitable by an
adversarial attack. In order to solve the "needle in the haystack" problem of
which samples to inspect, we develop a new scalable version of Cook's distance,
a classical statistical technique for identifying samples which unusually
strongly impact the fit of a regression model (and its downstream predictions).
In order to scale this technique up to very large and high-dimensional
datasets, we introduce a new algorithm which we call "influence sketching."
Influence sketching embeds random projections within the influence computation;
in particular, the influence score is calculated using the randomly projected
pseudo-dataset from the post-convergence Generalized Linear Model (GLM). We
validate that influence sketching can reliably and successfully discover
influential samples by applying the technique to a malware detection dataset of
over 2 million executable files, each represented with almost 100,000 features.
For example, we find that randomly deleting approximately 10% of training
samples reduces predictive accuracy only slightly from 99.47% to 99.45%,
whereas deleting the same number of samples with high influence sketch scores
reduces predictive accuracy all the way down to 90.24%. Moreover, we find that
influential samples are especially likely to be mislabeled. In the case study,
we manually inspect the most influential samples, and find that influence
sketching pointed us to new, previously unidentified pieces of malware.


title: High-resolution X-ray spectroscopy: the coming-of-age

abstract:
  Since the launch of Chandra and XMM-Newton, high-resolution X-ray spectra of
cosmic sources of all kinds have become available. These spectra have resulted
in major scientific breakthroughs. However, due to the techniques used, in
general high-quality spectra can only be obtained for the brightest few sources
of each class. Moreover, except for the most compact extended sources, like
cool core clusters, grating spectra are limited to point sources. Hitomi made
another major step forward, in yielding for the first time a high-quality
spectrum of an extended source, and improved spectral sensitivity in the Fe-K
band. For point sources with the proposed Arcus mission, and for all sources
with the launch of Athena, X-ray spectroscopy will become mature. It allows us
to extend the investigations from the few handful of brightest sources of each
category to a large number of sources far away in space and time, or to get
high time-resolution, high-spectral resolution spectra of bright time variable
sources.


title: Odd Harmonics in Exoplanet Photometry: Weather or Artifact?

abstract:
  Photometry of short-period planetary systems allows astronomers to monitor
exoplanets, their host stars, and their mutual interactions. In addition to the
transits of a planet in front of its star and the eclipses of the planet by its
star, researchers have reported flux variations at the orbital frequency and
its harmonics: planetary reflection and/or emission and Doppler beaming of
starlight produce one peak per orbit, while ellipsoidal variations of a tidally
distorted star and/or planet produce two maxima per orbit. Researchers have
also reported significant photometric variability at three times the orbital
frequency, sometimes much greater than the predictions of tidal theory. The
reflected phase variations of a homogeneous planet contains power at even
orbital harmonics-important for studies of ellipsoidal variations-but cannot
contain odd orbital harmonics. We show that odd harmonics can, however, be
produced by an edge-on planet with a time-variable map, or an inclined planet
with a North-South (N-S) asymmetric map. Either of these scenarios entail
weather: short-period planets are expected to have zero obliquity and hence N-S
symmetric stellar forcing. North-South asymmetry in a giant planet would
therefore suggest stochastic localized features, such as weather. However, we
find that previous claims of large-amplitude odd modes in Kepler photometry are
artifacts of removing planetary transits rather than modeling them. The only
reliable claims of odd harmonics remain HAT-P-7b and Kepler-13Ab, for which the
third mode amplitude is 6-8% of the planetary flux. Although time-variable
albedo maps could in principle explain these odd harmonics, upper-limits on the
infrared variability of hot Jupiters make this hypothesis unlikely. We urge
theorists to study the effects of close-in planets on stellar atmospheres, as
this remains the only plausible hypothesis.


title:
Surface vibrational modes of the topological insulator Bi$_2$Se$_3$
  observed by Raman spectroscopy

abstract:
  We present polarization resolved Raman scattering study of surface vibration
modes in the topological insulator Bi$_2$Se$_3$ single crystal and thick films.
Besides the four Raman active bulk phonons, we observed four additional modes
with much weaker intensity and slightly lower energy than the bulk
counterparts. Using symmetry analysis, we assigned these additional modes to
out-of-plane surface phonons. Comparing with first principle calculations, we
conclude that the appearance of these modes is due to $c$-axis lattice
distortion and van der Waals gap expansion near the crystal surface. Two of the
surface modes at 60 and 173 cm$^{-1}$ are associated with Raman active $A_{1g}$
bulk phonon modes, the other two at 136 and 158 cm$^{-1}$ are associated with
infrared active bulk phonons with $A_{2u}$ symmetry. The latter become Raman
allowed due to reduction of crystalline symmetry from $D_{3d}$ in the bulk to
$C_{3v}$ on the crystal surface. In particular, the 158 cm$^{-1}$ surface
phonon mode shows a Fano lineshape under resonant excitation, suggesting
interference in the presence of electron-phonon coupling of the surface
excitations.


title: Generalized BackPropagation, \'{E}tude De Cas: Orthogonality

abstract:
  This paper introduces an extension of the backpropagation algorithm that
enables us to have layers with constrained weights in a deep network. In
particular, we make use of the Riemannian geometry and optimization techniques
on matrix manifolds to step outside of normal practice in training deep
networks, equipping the network with structures such as orthogonality or
positive definiteness. Based on our development, we make another contribution
by introducing the Stiefel layer, a layer with orthogonal weights. Among
various applications, Stiefel layers can be used to design orthogonal filter
banks, perform dimensionality reduction and feature extraction. We demonstrate
the benefits of having orthogonality in deep networks through a broad set of
experiments, ranging from unsupervised feature learning to fine-grained image
classification.


title: Flows generated by divergence free vector fields with compact support

abstract:
  We are concerned with the theory of existence and uniqueness of flows
generated by divergence free vector fields with compact support. Hence,
assuming that the velocity vector fields are measurable, bounded, and the flows
in the Euclidean space are measure preserving, we show two counterexamples of
uniqueness/existence for such flows. First we consider the autonomous case in
dimension 3, and then, the non autonomous one in dimension 2.


title: Electron Emission Projection Imager

abstract:
  A new projection type imaging system is presented. The system can directly
image the field emission site distribution on a cathode surface by making use
of anode screens in the standard parallel plate configuration. The lateral
spatial resolution of the imager is between 1 and 10 {\mu}m. The imaging
sensitivity to the field emission current can be better than the current
sensitivity of a typical electrometer, i.e. less than 1 nA.


title:
Cosmic X-ray surveys of Active Galactic Nuclei: synergy between X-ray
  and infrared observations

abstract:
  We briefly review the synergy between X-ray and infrared observations for
Active Galactic Nuclei (AGNs) detected in cosmic X-ray surveys, primarily with
XMM-Newton, Chandra, and NuSTAR. We focus on two complementary aspects of this
X-ray-infrared synergy (1) the identification of the most heavily obscured AGNs
and (2) the connection between star formation and AGN activity. We also briefly
discuss future prospects for X-ray-infrared studies over the next decade.


title: Going Beyond Variation of Sets

abstract:
  We study integralgeometric representations of variations of general sets $A$
in the Euclidean n-space without any regularity assumptions. If we assume, for
example, that just one partial derivative of its characteristic function
$\chi^A$ is a signed Borel measure with finite total variation, can we provide
a nice integralgeometric representation of this variation? This is a delicate
question, as the Gauss-Green type theorems of De Giorgi and Federer are not
available in this generality. We will show that a `measure-theoretic boundary'
plays its role in such representations similarly as for the sets of finite
variation. There is a variety of suitable notions of `measure-theoretic
boundary' and one can address the question to find notions of measure-theoretic
boundary that are as fine as possible.


title:
The Star Formation Histories of Disk Galaxies: the Live, the Dead, and
  the Undead

abstract:
  We reexamine the systematic properties of local galaxy populations, using
published surveys of star formation, structure, and gas content. After
recalibrating star formation measures, we are able to reliably measure specific
star formation rates well below the "main sequence" of star formation vs mass.
We find an unexpectedly large population of galaxies with star formation rates
intermediate between vigorously star-forming main sequence galaxies and passive
galaxies, and with gas content disproportionately high for their star formation
rates. Several lines of evidence suggest that these quiescent galaxies form a
distinct population rather than a low star formation tail of the main sequence.
We demonstrate that a tight main sequence, evolving with epoch, is a natural
outcome of most histories of star formation and has little astrophysical
significance, but that the quiescent population requires additional
astrophysics to explain its properties. Using a simple model for disk evolution
based on the observed dependence of star formation on gas content in local
galaxies, and assuming simple histories of cold gas inflow, we show that the
evolution of galaxies away from the main sequence can be attributed to the
depletion of gas due to star formation after a cutoff in gas inflow. The
quiescent population is composed of galaxies in which the density of disk gas
has fallen below a threshold for disk stability. The evolution of galaxies
beyond the quiescent state to gas exhaustion requires another process, probably
wind-driven mass loss. The SSFR distribution of the quiescent and passive
implies that the timescale of this process must be greater than a few Gyrs but
less than a few tens of Gyrs. The environmental dependence of the galaxy
populations is consistent with recent theory suggesting that cold gas inflows
into galaxies are truncated at earlier times in denser environments.


title:
The role of guide field in magnetic reconnection driven by island
  coalescence

abstract:
  A number of studies have considered how the rate of magnetic reconnection
scales in large and weakly collisional systems by the modelling of long
reconnecting current sheets. However, this set-up neglects both the formation
of the current sheet and the coupling between the diffusion region and a larger
system that supplies the magnetic flux. Recent studies of magnetic island
merging, which naturally include these features, have found that ion kinetic
physics is crucial to describe the reconnection rate and global evolution of
such systems. In this paper, the effect of a guide field on reconnection during
island merging is considered. In contrast to the earlier current sheet studies,
we identify a limited range of guide fields for which the reconnection rate,
outflow velocity, and pile-up magnetic field increase in magnitude as the guide
field increases. The Hall-MHD fluid model is found to reproduce kinetic
reconnection rates only for a sufficiently strong guide field, for which ion
inertia breaks the frozen-in condition and the outflow becomes Alfvenic in the
kinetic system. The merging of large islands occurs on a longer timescale in
the zero guide field limit, which may in part be due to a mirror-like
instability that occurs upstream of the reconnection region.


title:
Increasing the Interpretability of Recurrent Neural Networks Using
  Hidden Markov Models

abstract:
  As deep neural networks continue to revolutionize various application
domains, there is increasing interest in making these powerful models more
understandable and interpretable, and narrowing down the causes of good and bad
predictions. We focus on recurrent neural networks, state of the art models in
speech recognition and translation. Our approach to increasing interpretability
is by combining a long short-term memory (LSTM) model with a hidden Markov
model (HMM), a simpler and more transparent model. We add the HMM state
probabilities to the output layer of the LSTM, and then train the HMM and LSTM
either sequentially or jointly. The LSTM can make use of the information from
the HMM, and fill in the gaps when the HMM is not performing well. A small
hybrid model usually performs better than a standalone LSTM of the same size,
especially on smaller data sets. We test the algorithms on text data and
medical time series data, and find that the LSTM and HMM learn complementary
information about the features in the text.


title: Force-Based Atomistic/Continuum Blending for Multilattices

abstract:
  We formulate the blended force-based quasicontinuum (BQCF) method for
multilattices and develop rigorous error estimates in terms of the
approximation parameters: atomistic region, blending region and continuum
finite element mesh. Balancing the approximation parameters yields a convergent
atomistic/continuum multiscale method for multilattices with point defects,
including a rigorous convergence rate in terms of the computational cost. The
analysis is illustrated with numerical results for a Stone--Wales defect in
graphene.


title:
A Pointwise Characterisation of the PDE System of Vectorial Calculus of
  Variations in $L^\infty$

abstract:
  Let $n,N\in \mathbb{N}$ with $\Omega \subseteq \mathbb{R}^n$ open. Given $H
\in C^2(\Omega \times \mathbb{R}^N\times \mathbb{R}^{Nn}),$ we consider the
functional \[ \tag{1} \label{1}
  E_\infty (u,\mathcal{O})\, :=\, \underset{\mathcal{O}}{\mathrm{ess}\,\sup}\,
H (\cdot,u,\mathrm{D} u) ,\ \ \ u\in
W^{1,\infty}_\text{loc}(\Omega,\mathbb{R}^N),\ \ \ \mathcal{O} \Subset \Omega.
\] The associated PDE system which plays the role of Euler-Lagrange equations
in $L^\infty$ is \[ \label{2} \tag{2} \left\{ \begin{array}{r} H_{P}(\cdot, u,
\mathrm{D}u)\, \mathrm{D} \big(H(\cdot, u, \mathrm{D} u)\big) \, = \, 0, \ \ \
  H(\cdot, u, \mathrm{D} u) \, [\![H_{P}(\cdot, u, \mathrm{D} u)]\!]^\bot
\Big(\mathrm{Div}\big(H_{P}(\cdot, u, \mathrm{D} u)\big)- H_{\eta}(\cdot, u,
\mathrm{D} u)\Big)\, =\, 0, \end{array} \right. \] where $[\![A]\!]^\bot :=
\mathrm{Proj}_{R(A)^\bot}$. Herein we establish that generalised solutions to
\eqref{2} can be characterised as local minimisers of \eqref{1} for appropriate
classes of affine variations of the energy. Generalised solutions to \eqref{2}
are understood as $\mathcal{D}$-solutions, a general framework recently
introduced by one of the authors.


title: Nilpotent $n$-tuples in $SU(2)$

abstract:
  We describe the connected components of the space $\text{Hom}(\Gamma,SU(2))$
of homomorphisms for a discrete nilpotent group $\Gamma$. The connected
components arising from homomorphisms with non-abelian image turn out to be
homeomorphic to $\mathbb{RP}^3$. We give explicit calculations when $\Gamma$ is
a finitely generated free nilpotent group. In the second part of the paper we
study the filtration $B_{\text{com}}SU(2) = B(2,SU(2))\subset\cdots \subset
B(q,SU(2))\subset\cdots$ of the classifying space $BSU(2)$ (introduced by Adem,
Cohen and Torres-Giese), showing that for every $q\geq2$, the inclusions induce
a homology isomorphism with coefficients over a ring in which 2 is invertible.
Most of the computations are done for $SO(3)$ and $U(2)$ as well.


title: Helium in Double-Detonation Models of Type Ia Supernovae

abstract:
  The double-detonation explosion model has been considered a candidate for
explaining astrophysical transients with a wide range of luminosities. In this
model, a carbon-oxygen white dwarf star explodes following detonation of a
surface layer of helium. One potential signature of this explosion mechanism is
the presence of unburned helium in the outer ejecta, left over from the surface
helium layer. In this paper we present simple approximations to estimate the
optical depths of important He I lines in the ejecta of double-detonation
models. We use these approximations to compute synthetic spectra, including the
He I lines, for double-detonation models obtained from hydrodynamical explosion
simulations. Specifically, we focus on photospheric-phase predictions for the
near-infrared 10830 \AA~and 2 $\mu$m lines of He I. We first consider a double
detonation model with a luminosity corresponding roughly to normal SNe Ia. This
model has a post-explosion unburned He mass of 0.03 $M_{\odot}$ and our
calculations suggest that the 2 $\mu$m feature is expected to be very weak but
that the 10830 \AA~feature may have modest opacity in the outer ejecta.
Consequently, we suggest that a moderate-to-weak He I 10830 \AA~feature may be
expected to form in double-detonation explosions at epochs around maximum
light. However, the high velocities of unburned helium predicted by the model
($\sim 19,000$~km~s$^{-1}$) mean that the He I 10830 \AA~feature may be
confused or blended with the C I 10690~\AA~line forming at lower velocities. We
also present calculations for the He I 10830 \AA~and 2 $\mu$m lines for a lower
mass (low luminosity) double detonation model, which has a post-explosion He
mass of 0.077 $M_{\odot}$. In this case, both the He I features we consider are
strong and can provide a clear observational signature of the double-detonation
mechanism.


title:
SC-DCNN: Highly-Scalable Deep Convolutional Neural Network using
  Stochastic Computing

abstract:
  With recent advancing of Internet of Things (IoTs), it becomes very
attractive to implement the deep convolutional neural networks (DCNNs) onto
embedded/portable systems. Presently, executing the software-based DCNNs
requires high-performance server clusters in practice, restricting their
widespread deployment on the mobile devices. To overcome this issue,
considerable research efforts have been conducted in the context of developing
highly-parallel and specific DCNN hardware, utilizing GPGPUs, FPGAs, and ASICs.
Stochastic Computing (SC), which uses bit-stream to represent a number within
[-1, 1] by counting the number of ones in the bit-stream, has a high potential
for implementing DCNNs with high scalability and ultra-low hardware footprint.
Since multiplications and additions can be calculated using AND gates and
multiplexers in SC, significant reductions in power/energy and hardware
footprint can be achieved compared to the conventional binary arithmetic
implementations. The tremendous savings in power (energy) and hardware
resources bring about immense design space for enhancing scalability and
robustness for hardware DCNNs. This paper presents the first comprehensive
design and optimization framework of SC-based DCNNs (SC-DCNNs). We first
present the optimal designs of function blocks that perform the basic
operations, i.e., inner product, pooling, and activation function. Then we
propose the optimal design of four types of combinations of basic function
blocks, named feature extraction blocks, which are in charge of extracting
features from input feature maps. Besides, weight storage methods are
investigated to reduce the area and power/energy consumption for storing
weights. Finally, the whole SC-DCNN implementation is optimized, with feature
extraction blocks carefully selected, to minimize area and power/energy
consumption while maintaining a high network accuracy level.


title: Finding Alternate Features in Lasso

abstract:
  We propose a method for finding alternate features missing in the Lasso
optimal solution. In ordinary Lasso problem, one global optimum is obtained and
the resulting features are interpreted as task-relevant features. However, this
can overlook possibly relevant features not selected by the Lasso. With the
proposed method, we can provide not only the Lasso optimal solution but also
possible alternate features to the Lasso solution. We show that such alternate
features can be computed efficiently by avoiding redundant computations. We
also demonstrate how the proposed method works in the 20 newsgroup data, which
shows that reasonable features are found as alternate features.


abstract:
  We give a graph-sum algorithm that expresses any genus-$g$ Gromov-Witten
invariant of the symmetric product orbifold
$\mathrm{Sym}^d\mathbb{P}^r:=[(\mathbb{P}^r)^d/S_d]$ in terms of "Hurwitz-Hodge
integrals" -- integrals over (compactified) Hurwitz spaces. We apply the
algorithm to prove a partial mirror theorem for $\mathrm{Sym}^d\mathbb{P}^r$ in
genus zero. The theorem states that a generating function of Gromov-Witten
invariants of $\mathrm{Sym}^d\mathbb{P}^r$ is equal to an explicit power series
$I_{\mathrm{Sym}^d\mathbb{P}^r}.$ This is a first step towards proving Ruan's
Crepant Resolution Conjecture for the resolution
$\mathrm{Hilb}^{(d)}(\mathbb{P}^2)$ of the coarse moduli space of
$\mathrm{Sym}^d\mathbb{P}^2.$


title: Kelvin transformation and inverse multipoles in electrostatics

abstract:
  The inversion in the sphere or Kelvin transformation, which exchanges the
radial coordinate for its inverse, is used as a guide to relate distinct
electrostatic problems with dual features. The exact solution of some
nontrivial problems are obtained through the mapping from simple highly
symmetric systems. In particular, the concept of multipole expansion is
revisited from a point of view opposed to the usual one: the sources are
distributed in a region far from the origin while the electrostatic potential
is described at points close to it.


title: Extern Objects in P4: an ROHC Header Compression Scheme Case Study

abstract:
  P4 is an emergent packet-processing language with which the user can describe
how the packets are to be processed in a switching element. This paper presents
a way to implement complex operations that are not natively supported in P4. In
this work, we explored two different methods to add extensions to P4: i) using
new native primitives and ii) using extern instances. As a case study, an ROHC
entity was implemented and invoked in a P4 program. The tests showed similar
relative performance in both methods in terms of normalized packet latency.
  However, extern instances appear to be more suitable for target-specific
switching applications, where the manufacturer/vendor can specify its own
specific operations without changes in the P4 syntax and semantics. Extern
instances only require changes in the target-specific backend compiler while
keeping the P4 frontend compiler unchanged. The use of externs also results in
a more elegant code solution since they are implemented outside the
switch-core, thus reducing side effects risks that can be caused by a
modification in a switch pipeline implementation.


title: Parallelepipeds obtaining HBL lower bounds

abstract:
  This work studies the application of the discrete Holder-Brascamp-Lieb (HBL)
inequalities to the design of communication optimal algorithms. In particular,
it describes optimal tiling (blocking) strategies for nested loops that lack
data dependencies and exhibit linear memory access patterns. We attain known
lower bounds for communication costs by unraveling the relationship between the
HBL linear program, its dual, and tile selection. The methods used are
constructive and algorithmic. The case when all arrays have one index is
explored in depth, as a useful example in which a particularly efficient tiling
can be determined.