title: Dynamic shear jamming in dense granular suspensions under extension

abstract:
  Unlike dry granular materials, a dense granular suspension like cornstarch in
water can strongly resist extensional flows. At low extension rates, such a
suspension behaves like a viscous liquid, but rapid extension results in a
response where stresses far exceed the predictions of lubrication hydrodynamics
and capillarity. To understand this remarkable mechanical response, we
experimentally measure the normal force imparted by a large bulk of the
suspension on a plate moving vertically upward at a controlled velocity. We
observe that above a velocity threshold, the peak force increases by orders of
magnitude. Using fast ultrasound imaging we map out the local velocity profiles
inside the suspension which reveal the formation of a growing jammed region
under rapid extension. This region interacts with the rigid boundaries of the
container through strong velocity gradients, suggesting a direct connection to
the recently proposed shear-jamming mechanism.


title:
Search for heavy Majorana neutrinos in e+/- e+/- plus jets and e+/-
  mu+/- plus jets events in proton-proton collisions at sqrt(s) = 8 TeV

abstract:
  A search is performed for heavy Majorana neutrinos (N) decaying into a W
boson and a lepton using the CMS detector at the Large Hadron Collider. A
signature of two jets and either two same sign electrons or a same sign
electron-muon pair is searched for using 19.7 inverse femtobarns of data
collected during 2012 in proton-proton collisions at a centre-of-mass energy of
8 TeV. The data are found to be consistent with the expected standard model
(SM) background and, in the context of a Type-1 seesaw mechanism, upper limits
are set on the cross section times branching fraction for production of heavy
Majorana neutrinos in the mass range between 40 and 500 GeV. The results are
additionally interpreted as limits on the mixing between the heavy Majorana
neutrinos and the SM neutrinos. In the mass range considered, the upper limits
range between 0.00015 - 0.72 for |V[eN]|^2 and 6.6E-5 - 0.47 for |V[eN]
V*[muN]|^2 / ( |V[eN]|^2 + |V[muN]|^2 ), where V[lN] is the mixing element
describing the mixing of the heavy neutrino with the SM neutrino of flavour l.
These limits are the most restrictive direct limits for heavy Majorana neutrino
masses above 200 GeV.


title:
A QCD sum rule calculation of the $X^\pm(5568) \to B_{s}^0\pi^\pm$ decay
  width

abstract:
  To understand the nature of the $X(5568)$, recently observed in the mass
spectrum of the $B_{s}^0\pi^\pm$ system by the D0 Collaboration, we have
investigated, in a previous work, a scalar tetraquark (diquak-antidiquark)
structure for it, within the two-point QCD sum rules method. The result found
for its mass agrees well with the experimental value. Encouraged by this
finding we now extend our calculations to obtain the decay width of $X(5568)$
to $B_{s}^0\pi^\pm$ using the three-point QCD sum rule. We obtain a value of
$(20.4\pm8.7)\MeV$, which, on comparing with the experimental value of
$21.9\pm6.4 (\mbox{sta})^{+5.0}_{-2.5}(\mbox{syst}) \MeV/c^2$, reinforces the
scalar four quark nature of $X(5568)$.


title: Online Sparse Linear Regression

abstract:
  We consider the online sparse linear regression problem, which is the problem
of sequentially making predictions observing only a limited number of features
in each round, to minimize regret with respect to the best sparse linear
regressor, where prediction accuracy is measured by square loss. We give an
inefficient algorithm that obtains regret bounded by $\tilde{O}(\sqrt{T})$
after $T$ prediction rounds. We complement this result by showing that no
algorithm running in polynomial time per iteration can achieve regret bounded
by $O(T^{1-\delta})$ for any constant $\delta > 0$ unless $\text{NP} \subseteq
\text{BPP}$. This computational hardness result resolves an open problem
presented in COLT 2014 (Kale, 2014) and also posed by Zolghadr et al. (2013).
This hardness result holds even if the algorithm is allowed to access more
features than the best sparse linear regressor up to a logarithmic factor in
the dimension.


title: Fermionic higher-spin triplets in AdS

abstract:
  We derive a metric-like Lagrangian and equations of motion, in AdS space, for
multiplets of fermionic fields with spin ranged from 1/2 to s, from their
frame-like formulation.


title: Drift Robust Non-rigid Optical Flow Enhancement for Long Sequences

abstract:
  It is hard to densely track a nonrigid object in long term, which is a
fundamental research issue in the computer vision community. This task often
relies on estimating pairwise correspondences between images over time where
the error is accumulated and leads to a drift issue. In this paper, we
introduce a novel optimization framework with an Anchor Patch constraint. It is
supposed to significantly reduce overall errors given long sequences containing
non-rigidly deformable objects. Our framework can be applied to any dense
tracking algorithm, e.g. optical flow. We demonstrate the success of our
approach by showing significant error reduction on 6 popular optical flow
algorithms applied to a range of real-world nonrigid benchmarks. We also
provide quantitative analysis of our approach given synthetic occlusions and
image noise.


title: Blur Robust Optical Flow using Motion Channel

abstract:
  It is hard to estimate optical flow given a realworld video sequence with
camera shake and other motion blur. In this paper, we first investigate the
blur parameterization for video footage using near linear motion elements. we
then combine a commercial 3D pose sensor with an RGB camera, in order to film
video footage of interest together with the camera motion. We illustrates that
this additional camera motion/trajectory channel can be embedded into a hybrid
framework by interleaving an iterative blind deconvolution and warping based
optical flow scheme. Our method yields improved accuracy within three other
state-of-the-art baselines given our proposed ground truth blurry sequences;
and several other realworld sequences filmed by our imaging system.


title: Fluctuations as a test of chemical non-equilibrium at the LHC

abstract:
  It is shown that large chemical potential leads to the significant increase
of multiplicity fluctuations for bosons, and makes the fluctuations infinite in
the case of Bose-Einstein condensation. It allows to distinguish between the
models that explain the anomalous proton to pion ratio and the low transverse
momentum enhancement of pion spectra in Pb+Pb collisions at the LHC within
chemical equilibrium or non-equilibrium models. The effects of resonance
decays, finite size of the system, requirements to the event statistics,
different momentum cuts, and limited detector acceptance are considered. The
obtained results show the possibility to observe a substantial increase of the
normalized kurtosis for positively or negatively charged pions in the case of
non-equilibrium or partial pion condensation using currently measured data.


title:
Spin polarization of Majorana zero modes and topological quantum phase
  transition in semiconductor Majorana nanowires

abstract:
  A number of recent works have discussed the issue of spin polarization of a
Majorana zero mode in condensed matter systems. Here we show that the spin
polarization density of a Majorana zero mode, computed as an average of the
spin operator over its wave function, vanishes everywhere. A single
non-degenerate Majorana zero mode, therefore, does not couple to an applied
magnetic field, except via hybridization with higher energy excited states (if
present), which may perturb its wave function. If `spin' is defined by
considering only the particle components of the wave function, as has been done
in some recent works, Majorana zero modes do have a non-zero spatial profile of
this quantity, measurable in scanning tunneling microscopy (STM) experiments.
However, if such a quantity is measured in spin-resolved tunneling experiments
(without spatial resolution), we show that it cannot be used as a unique
signature of Majorana zero modes in the topologically non-trivial
superconducting phase. As a byproduct, we show that in spatially inhomogeneous
systems, accidental zero energy modes, which for all practical purposes behave
as Majorana zero modes (including giving rise to a zero bias conductance peak
of height 2e^2/h), can appear with increasing magnetic field even in the
absence of a topological quantum phase transition (TQPT). But only after gap
closing and the associated TQPT, the modes are localized near the system edges,
resulting in the maximum topological protection. In the light of these
considerations, demonstrating the nonlocal character of the
topologically-protected Majorana pair and its emergence {\em after} the systems
undergo a TQPT, become critical tasks for the ongoing experimental search for
Majorana bound states in condensed matter systems.


title: On the shape of dark matter halos from MultiDark Planck simulations

abstract:
  The halo shape plays a central role in determining important observational
properties of the haloes such as mass, concentration and lensing
cross-sections. The triaxiality of lensing galaxy clusters has a substantial
impact on the distribution of the largest Einstein radii, while weak lensing
techniques are sensitive to the intrinsic halo ellipticity. In this work, we
provide scaling relations for the shapes of dark matter haloes as a function of
mass (peak height) and redshift over more than four orders of magnitude in halo
masses, namely from $10^{11.5}$ to $10^{15.8}~h^{-1}~$M$_\odot$. We have
analysed four dark matter only simulations from the MultiDark cosmological
simulation suite with more than 56 billion particles within boxes of 4.0, 2.5,
1.0 and 0.4 $h^{-1}$Gpc size assuming \textit{Planck} cosmology. The dark
matter haloes have been identified in the simulations using the {\sc rockstar}
halo finder, which also determines the axis ratios in terms of the
diagonalization of the inertia tensor. In order to infer the shape for a
hypothetical halo of a given mass at a given redshift, we provide fitting
functions to the minor-to-major and intermediate-to-major axis ratios as a
function of the peak height.


title:
Active versus passive transformations in the presence of a magnetic
  field

abstract:
  It is shown that, when there is a magnetic field present, in the framework of
classical or quantum mechanics, the active translations differ from the passive
ones and that the canonical momentum is not the generator of them. It is also
shown that an infinitesimal generator of passive translations or rotations
exists only if the magnetic field is invariant under these transformations.


title:
First evidence of non-locality in real band-gap metamaterials:
  determining parameters in the relaxed micromorphic model

abstract:
  In this paper we propose the first estimate of some elastic parameters of the
relaxed micromorphic model on the basis of real experiments of transmission of
longitudinal plane waves across an interface separating a classical Cauchy
material (steel plate) and a phononic crystal (steel plate with fluid-filled
holes). A procedure is set up in order to identify the parameters of our model
by superimposing the experimentally-based profile of the reflection coefficient
(plotted as function of the frequency of the traveling waves) with the
analogous profile obtained via simulations based upon the relaxed micromorphic
model. We end up with the determination of 5 out of 6 constitutive parameters
which are featured by the relaxed micromorphic model in the isotropic case,
plus the determination of the micro-inertia parameter. The sixth elastic
parameter, namely the Cosserat couple modulus $\mu_{c}$, still remains
undetermined, since experimental data concerning the transmission properties of
the considered interface for transverse incident waves are not yet available. A
fundamental result of the present paper is the estimate of the non-locality
intrinsically associated to the underlying microstructure of the metamaterial.
As a matter of fact, we appraise that the characteristic length $L_{c}$
measuring the non-locality of the considered phononic crystal is of the order
of $1/3$ of the diameter of the considered fluid-filled holes.


title:
Geometrothermodynamics of black holes in Lorentz non-invariant massive
  gravity

abstract:
  We analyze a static and spherically symmetric hairy black hole solution in
non-invariant massive gravity. The formalism of geometrothermodynamics is used
to describe the thermodynamic characteristics of this black hole in a Legendre
invariant way. For a black hole in massive gravity, the geometry of the space
of equilibrium states is computed showing that it contains information about
the thermodynamic interaction, critical points and phase transitions structure.


title: In-Vehicle PLC: In-Car and In-Ship Channel Characterization

abstract:
  This paper deals with power line communication (PLC) in the context of
in-vehicle data networks. This technology can provide high-speed data
connectivity via the exploitation of the existing power network, with clear
potential benefits in terms of cost and weight reduction. The focus is on two
scenarios: an electric car and a cruise ship. An overview of the wiring
infrastructure and the network topology in these two scenarios is provided. The
main findings reported in the literature related to the channel characteristics
are reported. Noise is also assessed with emphasis to the electric car context.
Then, new results from the statistical analysis of measurements made in a
compact electric car and in a large cruise ship are shown. The channel
characteristics are analysed in terms of average channel gain, delay spread,
coherence bandwidth and achievable transmission rate. Finally, an overall
comparison is made, highlighting similarities and differences taking into
account also the conventional (combustion engine) car and the largely
investigated in-home scenario.


title: Auditing spreadsheets: With or without a tool?

abstract:
  Spreadsheets are known to be error-prone. Over the last decade, research has
been done to determine the causes of the high rate of errors in spreadsheets.
This paper examines the added value of a spreadsheet tool (PerfectXL) that
visualizes spreadsheet dependencies and determines possible errors in
spreadsheets by defining risk areas based on previous work. This paper will
firstly discuss the most common mistakes in spreadsheets. Then we will
summarize research on spreadsheet tools, focussing on the PerfectXL tool. To
determine the perceptions of the usefulness of a spreadsheet tool in general
and the PerfectXL tool in particular, we have shown the functionality of
PerfectXL to several auditors and have also interviewed them. The results of
these interviews indicate that spreadsheet tools support a more effective and
efficient audit of spreadsheets; the visualization feature in particular is
mentioned by the auditors as being highly supportive for their audit task,
whereas the risk feature was deemed of lesser value.


title: Problem Solving in Sprego

abstract:
  Sprego is a programming tool for novice and end-user programmers within
graphical spreadsheet environments. The main idea of Sprego is to use as few
general purpose functions as possible, and based on these functions we create
multilevel formulas to solve real world programmable spreadsheet problems.
Beyond providing the framework for the theoretic background and the tools which
support Sprego, in order to demonstrate the power which lies within it, we
present a converted authentic table and, based on this table, data retrieval
tasks, their algorithms, and coding in full details.


title: Spectral $\zeta$-invariants lifted to coverings

abstract:
  The canonical trace and the Wodzicki residue on classical pseudodifferential
operators on a closed manifold are characterised by their locality and shown to
be preserved under lifting to the universal covering as a result of their local
feature. As a consequence, we lift a class of spectral $\zeta$-invariants using
lifted defect formulae which express discrepancies of $\zeta$-regularised
traces in terms of Wodzicki residues. We derive Atiyah's $L^2$-index theorem as
an instance of the $\mathbb Z_2$-graded generalisation of the canonical lift of
spectral $\zeta$-invariants and we show that certain lifted spectral
$\zeta$-invariants for geometric operators are integrals of Pontryagin and
Chern forms.


title: Prevention versus treatment: A game-theoretic approach

abstract:
  Empirical studies show that preference for prevention versus treatment
remains a subject of debate. We build a paradigm model combining a utility game
for the individual-level dilemma of prevention versus treatment, and a
compartmental model for the epidemic dynamic. We assume that individuals arrive
to maximize the utility of voluntary prevention, as the epidemic reaches an
endemic level alleviated by prevention and treatment. We thus obtain an
expression for the asymptotic prevention coverage. Notably, we obtain that, if
the relative cost of prevention versus treatment is sufficiently low, epidemics
may be averted through the use of prevention alone.


title: Bayesian monitoring of emerging infectious diseases

abstract:
  We define data analyses to monitor a change in R, the average number of
secondary cases caused by a typical infected individual. The input dataset
consists of incident cases partitioned into outbreaks, each initiated from a
single index case. We split of the input dataset into two successive subsets,
to evaluate two successive R values, according to the Bayesian paradigm. We
used the Bayes factor between the model with two different R values and that
with a single R value to justify that the change in R is statistically
significant. We validated our approach using simulated data, generated using
known R. In particular, we found that claiming two distinct R values may depend
significantly on the number of outbreaks. We then reanalyzed data previously
studied by Jansen et al. [Jansen et al. Science 301 (5634), 804], concerning
the effective reproduction number for measles in the UK, during 1995-2002. Our
analyses showed that the 1995-2002 dataset should be divided into two separate
subsets for the periods 1995-1998 and 1999-2002. In contrast, Jansen et al.
take this splitting point as input of their analysis. Our estimated effective
reproduction numbers R are in good agreement with those found by Jansen et al.
In conclusion, our methodology for detecting temporal changes in R using
outbreak-size data worked satisfactorily with both simulated and real-world
data. The methodology may be used for updating R in real time, as surveillance
outbreak data become available.


title:
Compartmental analysis of dynamic nuclear medicine data: models and
  identifiability

abstract:
  Compartmental models based on tracer mass balance are extensively used in
clinical and pre-clinical nuclear medicine in order to obtain quantitative
information on tracer metabolism in the biological tissue. This paper is the
first of a series of two that deal with the problem of tracer coefficient
estimation via compartmental modelling in an inverse problem framework.
Specifically, here we discuss the identifiability problem for a general
n-dimension compartmental system and provide uniqueness results in the case of
two-compartment and three-compartment compartmental models. The second paper
will utilize this framework in order to show how non-linear regularization
schemes can be applied to obtain numerical estimates of the tracer coefficients
in the case of nuclear medicine data corresponding to brain, liver and kidney
physiology.


title: Refinements in the Jungle Universes

abstract:
  How can effective barotropic matter emerge from the interaction of
cosmological fluids in an isotropic and homogeneous cosmological model ?
  The dynamics of homogeneous and isotropic
Friedmann-Lema\^itre-Robertson-Walker universes is a natural special case of
generalized Lotka-Volterra systems where each of the universe's fluid
components can be seen as a competitive species in a predator-prey model.
(Jungle universe : arXiv:1306.1037)
  In addition to numerical simulations illustrating this behaviour among the
barotropic fluids filling the universe, we analytically pinpoint that effective
time-dependent barotropic indices can arise from a physical coupling between
those fluids whose dynamics could then look like that of another type of cosmic
fluid, such as a cosmological constant.
  Since the nature of dark energy is still unknown, this dynamical approach
could help understanding some of the properties of dark matter and dark energy
at large cosmological scales.


title:
Optimization and small-amplitude analysis of Purcell's three-link
  microswimmer model

abstract:
  This work studies the motion of Purcell's three-link microswimmer in viscous
flow, by using perturbation expansion of its dynamics under small-amplitude
strokes. Leading-order expressions and next-order correction terms for the
displacement of the swimmer are obtained for the cases of a square or circular
gait in the plane of joint angles. The correction terms demonstrate the
reversal in movement direction for large stroke amplitudes, which has
previously only been shown numerically. In addition, asymptotic expressions for
Lighthill's energetic efficiency are obtained for both gaits. These
approximations enable calculating optimal stroke amplitudes and swimmer's
geometry (i.e. ratio of links' lengths) for maximizing either the displacement
or Lighthill's efficiency.


title: Algebraic Theory of Measurement Processes in Quantum Systems

abstract:
  Here we deal in a pedagogical way with an approach to construct an algebraic
structure for the Quantum Mechanical measurement processes from the concept of
\emph{Measurement Symbol}. Such concept was conceived by Julian S. Schwinger
and constitutes a fundamental piece in his variational formalism and its
several applications.


title:
Insights from Synthetic Star-forming Regions: I. Reliable Mock
  Observations from SPH Simulations

abstract:
  Through synthetic observations of a hydrodynamical simulation of an evolving
star-forming region, we assess how the choice of observational techniques
affects the measurements of properties which trace star formation. Testing and
calibrating observational measurements requires synthetic observations which
are as realistic as possible. In this part of the paper series (Paper I), we
explore different techniques for how to map the distributions of densities and
temperatures from the particle-based simulations onto a Voronoi mesh suitable
for radiative transfer and consequently explore their accuracy. We further test
different ways to set up the radiative transfer in order to produce realistic
synthetic observations. We give a detailed description of all methods and
ultimately recommend techniques. We have found that the flux around 20 microns
is strongly overestimated when blindly coupling the dust radiative transfer
temperature with the hydrodynamical gas temperature. We find that when instead
assuming a constant background dust temperature in addition to the radiative
transfer heating, the recovered flux is consistent with actual observations. We
present around 5800 realistic synthetic observations for Spitzer and Herschel
bands, at different evolutionary time-steps, distances and orientations. In the
upcoming papers of this series (Paper II, Paper III and Paper IV), we will test
and calibrate measurements of the star-formation rate (SFR), gas mass and the
star-formation efficiency (SFE) using our realistic synthetic observations.


title:
Murchison Widefield Array Limits on Radio Emission from ANTARES Neutrino
  Events

abstract:
  We present a search, using the Murchison Widefield Array (MWA), for
electromagnetic counterparts to two candidate high energy neutrino events
detected by the ANTARES neutrino telescope in 2013 November and 2014 March.
These events were selected by ANTARES because they are consistent, within 0.4
degrees, with the locations of galaxies within 20 Mpc of Earth. Using MWA
archival data at frequencies between 118 and 182 MHz, taken ~20 days prior to,
at the same time as, and up to a year after the neutrino triggers, we look for
transient or strongly variable radio sources consistent with the neutrino
positions. No such counterparts are detected, and we set a 5 sigma upper limit
for low-frequency radio emission of ~1E37 erg/s for progenitors at 20 Mpc. If
the neutrino sources are instead not in nearby galaxies, but originate in
binary neutron star coalescences, our limits place the progenitors at z > 0.2.
While it is possible, due to the high background from atmospheric neutrinos,
that neither event is astrophysical, the MWA observations are nevertheless
among the first to follow up neutrino candidates in the radio, and illustrate
the promise of wide-field instruments like MWA to detect electromagnetic
counterparts to such events.


title: A shock front at the radio relic of Abell 2744

abstract:
  Radio relics are Mpc-scale diffuse radio sources at the peripheries of galaxy
clusters which are thought to trace outgoing merger shocks. We present
XMM-Newton and Suzaku observations of the galaxy cluster Abell 2744 (z=0.306),
which reveal the presence of a shock front 1.5 Mpc East of the cluster core.
The surface-brightness jump coincides with the position of a known radio relic.
Although the surface-brightness jump indicates a weak shock with a Mach number
$\mathcal{M}=1.7_{-0.3}^{+0.5}$, the plasma in the post-shock region has been
heated to a very high temperature ($\sim13$ keV) by the passage of the shock
wave. The low acceleration efficiency expected from such a weak shock suggests
that mildly relativistic electrons have been re-accelerated by the passage of
the shock front.


title:
Competing orders and topology in the global phase diagram of pyrochlore
  iridates

abstract:
  Strong electronic interactions and spin orbit coupling can be conducive for
realizing novel broken symmetry phases supporting quasiparticles with
nontrivial band topology. 227 pyrochlore iridates provide a suitable material
platform for studying such emergent phenomena where both topology and competing
orders play important roles. In contrast to the most members of this material
class, which are thought to display "all-in all-out" (AIAO) type magnetically
ordered low-temperature insulating ground states, Pr$_2$Ir$_2$O$_7$ remains
metallic while exhibiting "spin ice" (SI) correlations at low temperatures.
Additionally, this is the only 227 iridate compound, which exhibits a large
anomalous Hall effect (AHE) along [1,1,1] direction below 1.5 K, without
possessing any measurable magnetic moment. By focusing on the normal state of
227 iridates, described by a parabolic semimetal with quadratic band touching,
we use renormalization group analysis, mean-field theory, and phenomenological
Landau theory as three complementary methods to construct a global phase
diagram in the presence of generic local interactions among itinerant electrons
of Ir ions. While the global phase diagram supports several competing
multipolar orders, motivated by the phenomenology of 227 iridates we
particularly emphasize the competition between AIAO and SI orders and how it
can cause a mixed phase with "three-in one-out" (3I1O) spin configurations. In
terms of topological properties of Weyl quasiparticles of the 3I1O state, we
provide an explanation for the magnitude and the direction of the observed AHE
in Pr$_2$Ir$_2$O$_7$. We propose a strain induced enhancement of the onset
temperature for AHE in thin films of Pr$_2$Ir$_2$O$_7$ and additional
experiments for studying competing orders in the vicinity of the
metal-insulator transition.


title:
Computer-automated tuning of semiconductor double quantum dots into the
  single-electron regime

abstract:
  We report the computer-automated tuning of gate-defined semiconductor double
quantum dots in GaAs heterostructures. We benchmark the algorithm by creating
three double quantum dots inside a linear array of four quantum dots. The
algorithm sets the correct gate voltages for all the gates to tune the double
quantum dots into the single-electron regime. The algorithm only requires (1)
prior knowledge of the gate design and (2) the pinch-off value of the single
gate $T$ that is shared by all the quantum dots. This work significantly
alleviates the user effort required to tune multiple quantum dot devices.


title: Detecting Topological Order with Ribbon Operators

abstract:
  We introduce a numerical method for identifying topological order in
two-dimensional models based on one-dimensional bulk operators. The idea is to
identify approximate symmetries supported on thin strips through the bulk that
behave as string operators associated to an anyon model. We can express these
ribbon operators in matrix product form and define a cost function that allows
us to efficiently optimize over this ansatz class. We test this method on spin
models with abelian topological order by finding ribbon operators for
$\mathbb{Z}_d$ quantum double models with local fields and Ising-like terms. In
addition, we identify ribbons in the abelian phase of Kitaev's honeycomb model
which serve as the logical operators of the encoded qubit for the quantum
error-correcting code. We further identify the topologically encoded qubit in
the quantum compass model, and show that despite this qubit, the model does not
support topological order. Finally, we discuss how the method supports
generalizations for detecting nonabelian topological order.


title: The Scale of Reddening for Classical Cepheid Variables

abstract:
  Field reddenings are summarized for 68 Cepheids from published studies and
updated results presented here. The compilation forms the basis for a
comparison with other published reddening scales of Cepheids, including those
established from reddening-independent indices, photometry on the Lick
six-color system, Str\"{o}mgren system, Walraven system, Washington system,
Cape $BVI$ system, DDO system, and Geneva system, IRSB studies, and Cepheid
spectroscopy, both old and new. Reddenings tied to period-color relations are
the least reliable, as expected, while photometric color excesses vary in
precision, their accuracy depending on the methodology and calibration sample.
The tests provide insights into the accuracy and precision of published Cepheid
reddening scales, and lead to a new system of standardized reddenings
comprising a sample of 198 variables with an average uncertainty of $\pm0.028$
in E$_{B-V}$, the precision being less than $\pm0.01$ for many. The collected
color excesses are used to map the dispersion in intrinsic colors as a function
of pulsation period, the results contradicting current perceptions about the
period dependence of dispersion in Cepheid effective temperatures.


title: [CII] emission in z ~ 6 strongly lensed, star-forming galaxies

abstract:
  The far-infrared fine-structure line [CII] at 1900.5\,GHz is known to be one
of the brightest cooling lines in local galaxies, and therefore it has been
suggested to be an efficient tracer for star-formation in very high-redshift
galaxies. However, recent results for galaxies at $z>6$ have yielded numerous
non-detections in star-forming galaxies, except for quasars and submillimeter
galaxies. We report the results of ALMA observations of two lensed,
star-forming galaxies at $z = 6.029$ and $z=6.703$. The galaxy A383-5.1 (star
formation rate [SFR] of 3.2 M$_\odot$ yr$^{-1}$ and magnification of $\mu =
11.4\pm1.9$) shows a line detection with $L_{\rm [CII]} = 8.9\times10^{6}$
L$_\odot$, making it the lowest $L_{\rm [CII]}$ detection at $z>6$. For
MS0451-H (SFR = 0.4 M$_\odot$ yr$^{-1}$ and $\mu = 100\pm20$) we provide an
upper limit of $L_{\rm [CII]} < 3\times10^{5}$ L$_\odot$, which is 1\,dex below
the local SFR-$L_{\rm [CII]}$ relations. The results are consistent with
predictions for low-metallicity galaxies at $z>6$, however, other effects could
also play a role in terms of decreasing $L_{\rm [CII]}$. The detection of
A383-5.1 is encouraging and suggests that detections are possible, but much
fainter than initially predicted.


title:
What a Tangled Web We Weave: Hermus as the Northern Extension of the
  Phoenix Stream

abstract:
  We investigate whether the recently discovered Phoenix stream may be part of
a much longer structure that includes the previously discovered Hermus stream.
Using a simple model of the Galaxy with a disk, bulge, and a spherical dark
matter halo, we show that a nearly circular orbit, highly inclined with respect
to the disk, can be found that fits the positions, orientations, and distances
of both streams. While the two streams are somewhat misaligned in the sense
that they do not occupy the same plane, nodal precession due to the Milky Way
disk potential naturally brings the orbit into line with each stream in the
course of half an orbit. We consequently consider a common origin for the two
streams as plausible. Based on our best fitting orbit, we make predictions for
the positions, distances, radial velocities, and proper motions along each
stream. If our hypothesis is borne out by measurements, then at ~183 degrees
(~235 degrees with respect to the Galactic center) and ~76 kpc in length,
Phoenix-Hermus would become the longest cold stream yet found. This would make
it a particularly valuable new probe of the shape and mass of the Galactic halo
out to ~20 kpc.


title: ARPES study of the Kitaev Candidate $\alpha$-RuCl$_3$

abstract:
  $\alpha$-RuCl$_3$ has been hinted as a spin-orbital-assisted Mott insulator
in proximity to a Kitaev spin liquid state. Here we present ARPES measurements
on single crystal $\alpha$-RuCl$_3$ in both the pristine and electron-doped
states, and combine them with LDA+SOC+U calculations performed for the several
low-energy competing magnetically ordered states as well as the paramagnetic
state. A large Mott gap is found in the measured band structure of the pristine
compound that persists to more than 20 times beyond the magnetic ordering
temperature, though the paramagnetic calculation shows almost no gap. Upon
electron doping, spectral weight is transferred into the gap but the new states
still maintain a sizable gap from the Fermi edge. These findings are most
consistent with a Mott insulator with a somewhat exotic evolution out of the
Mott state with both temperature and doping, likely related to unusually strong
spin fluctuations.


title:
The effect of unresolved binaries on globular cluster proper-motion
  dispersion profiles

abstract:
  High-precision kinematic studies of globular clusters require an accurate
knowledge of all possible sources of contamination. Amongst other sources,
binary stars can introduce systematic biases in the kinematics. Using a set of
Monte Carlo cluster simulations with different concentrations and binary
fractions, we investigate the effect of unresolved binaries on proper-motion
dispersion profiles, treating the simulations like HST proper-motion samples.
Since globular clusters evolve towards a state of partial energy equipartition,
more massive stars lose energy and decrease their velocity dispersion. As a
consequence, on average, binaries have a lower velocity dispersion, since they
are more massive kinematic tracers. We show that, in the case of clusters with
high binary fraction (initial binary fraction of 50%) and high concentration
(i.e., closer to energy equipartition), unresolved binaries introduce a
color-dependent bias in the velocity dispersion of main-sequence stars of the
order of 0.1-0.3 km s$^{-1}$ (corresponding to $1-6$% of the velocity
dispersion), with the reddest stars having a lower velocity dispersion, due to
the higher fraction of contaminating binaries. This bias depends on the ability
to distinguish binaries from single stars, on the details of the
color-magnitude diagram and the photometric errors. We apply our analysis to
the HSTPROMO data set of NGC 7078 (M15) and show that no effect ascribable to
binaries is observed, consistent with the low binary fraction of the cluster.
Our work indicates that binaries do not significantly bias proper-motion
velocity-dispersion profiles, but should be taken into account in the error
budget of kinematic analyses.


title:
Subaru high-z exploration of low-luminosity quasars (SHELLQs). I.
  Discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9

abstract:
  We report the discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9.
This is the initial result from the Subaru High-z Exploration of Low-Luminosity
Quasars (SHELLQs) project, which exploits the exquisite multiband imaging data
produced by the Subaru Hyper Suprime-Cam (HSC) Strategic Program survey. The
candidate selection is performed by combining several photometric approaches
including a Bayesian probabilistic algorithm to reject stars and dwarfs. The
spectroscopic identification was carried out with the Gran Telescopio Canarias
and the Subaru Telescope for the first 80 deg2 of the survey footprint. The
success rate of our photometric selection is quite high, approaching 100 % at
the brighter magnitudes (zAB < 23.5 mag). Our selection also recovered all the
known high-z quasars on the HSC images. Among the 15 discovered objects, six
are likely quasars, while the other six with interstellar absorption lines and
in some cases narrow emission lines are likely bright Lyman-break galaxies. The
remaining three objects have weak continua and very strong and narrow Ly alpha
lines, which may be excited by ultraviolet light from both young stars and
quasars. These results indicate that we are starting to see the steep rise of
the luminosity function of z > 6 galaxies, compared with that of quasars, at
magnitudes fainter than M1450 ~ -22 mag or zAB ~24 mag. Follow-up studies of
the discovered objects as well as further survey observations are ongoing.


title: Entanglement-assisted capacities of compound quantum channels

abstract:
  We study universal quantum codes for entanglement-assisted quantum
communication over compound quantum channels. In this setting, sender and
receiver do not know the specific channel that will be used for communication,
but only know the set that the channel is selected from. We investigate
different variations of the problem: uninformed users, informed receiver,
informed sender, and feedback assistance. We derive single-letter formulas for
all corresponding channel capacities. Our proofs are based on one-shot
decoupling bounds and properties of smooth entropies.


title: Gauging and Decoupling in 3d $\mathcal{N}=2$ dualities

abstract:
  One interesting feature of 3d $\mathcal{N}=2$ theories is that
gauge-invariant operators can decouple by strong-coupling effects, leading to
emergent flavor symmetries in the IR. The details of such decoupling, however,
depends very delicately on the gauge group and matter content of the theory. We
here systematically study the IR behavior of 3d $\mathcal{N}=2$ SQCD with $N_f$
flavors, for gauge groups $\mathrm{SU}(N_c), \mathrm{USp}(2N_c)$ and
$\mathrm{SO}(N_c)$. We apply a combination of analytical and numerical methods,
both to small values of $N_c, N_f$ and also to the Veneziano limit, where $N_c$
and $N_f$ are taken to be large with their ratio $N_f/N_c$ fixed. We highlight
the role of the monopole operators and the interplay with Aharony-type
dualities. We also discuss the effect of gauging continuous as well as discrete
flavor symmetries, and the implications of our analysis to the classification
of $1/4$--BPS co-dimension 2 defects of 6d $(2,0)$ theories.


title:
The MOSDEF Survey: The strong agreement between H-alpha and UV-to-FIR
  star formation rates for z~2 star-forming galaxies

abstract:
  We present the first direct comparison between Balmer line and panchromatic
SED-based SFRs for z~2 galaxies. For this comparison we used 17 star-forming
galaxies selected from the MOSFIRE Deep Evolution Field (MOSDEF) survey, with
$3\sigma$ detections for H$\alpha$ and at least two IR bands (Spitzer/MIPS
24$\mu$m and Herschel/PACS 100 and 160$\mu$m, and in some cases Herschel/SPIRE
250, 350, and 500$\mu$m). The galaxies have total IR (8-1000$\mu$m)
luminosities of $\sim10^{11.4}-10^{12.4}\,\textrm{L}_\odot$ and star-formation
rates (SFRs) of $\sim30-250\,\textrm{M}_\odot\,\mathrm{yr^{-1}}$. We fit the
UV-to-far-IR SEDs with flexible stellar population synthesis (FSPS) models -
which include both stellar and dust emission - and compare the inferred SFRs
with the SFR(H$\alpha$,H$\beta$) values corrected for dust attenuation using
Balmer decrements. The two SFRs agree with a scatter of 0.17 dex. Our results
imply that the Balmer decrement accurately predicts the obscuration of the
nebular lines and can be used to robustly calculate SFRs for star-forming
galaxies at z~2 with SFRs up to $\sim200\,\textrm{M}_\odot\,\mathrm{yr^{-1}}$.
We also use our data to assess SFR indicators based on modeling the
UV-to-mid-IR SEDs or by adding SFR(UV) and SFR(IR), for which the latter is
based on the mid-IR only or on the full IR SED. All these SFRs show a poorer
agreement with SFR(H$\alpha$,H$\beta$) and in some cases large systematic
biases are observed. Finally, we show that the SFR and dust attenuation derived
from the UV-to-near-IR SED alone are unbiased when assuming a delayed
exponentially declining star-formation history.


title: Discriminating Topology in Galaxy Distributions using Network Analysis

abstract:
  (abridged) The large-scale distribution of galaxies is generally analyzed
using the two-point correlation function. However, this statistic does not
capture the topology of the distribution, and it is necessary to resort to
higher order correlations to break degeneracies. We demonstrate that an
alternate approach using network analysis can discriminate between
topologically different distributions that have similar two-point correlations.
We investigate two galaxy point distributions, one produced by a cosmological
simulation and the other by a L\'evy walk. For the cosmological simulation, we
adopt the redshift $z = 0.58$ slice from Illustris (Vogelsberger et al. 2014A)
and select galaxies with stellar masses greater than $10^8$$M_\odot$. The two
point correlation function of these simulated galaxies follows a single
power-law, $\xi(r) \sim r^{-1.5}$. Then, we generate L\'evy walks matching the
correlation function and abundance with the simulated galaxies. We find that,
while the two simulated galaxy point distributions have the same abundance and
two point correlation function, their spatial distributions are very different;
most prominently, \emph{filamentary structures}, absent in L\'evy fractals. To
quantify these missing topologies, we adopt network analysis tools and measure
diameter, giant component, and transitivity from networks built by a
conventional friends-of-friends recipe with various linking lengths. Unlike the
abundance and two point correlation function, these network quantities reveal a
clear separation between the two simulated distributions; therefore, the galaxy
distribution simulated by Illustris is not a L\'evy fractal quantitatively. We
find that the described network quantities offer an efficient tool for
discriminating topologies and for comparing observed and theoretical
distributions.


title: Transversal Clifford gates on folded surface codes

abstract:
  Surface and color codes are two forms of topological quantum error correction
in two spatial dimensions with complementary properties. Surface codes have
lower-depth error detection circuits and well-developed decoders to interpret
and correct errors, while color codes have transversal Clifford gates and
better code efficiency in the number of physical qubits needed to achieve a
given code distance. A formal equivalence exists between color codes and folded
surface codes, but it does not guarantee the transferability of any of these
favorable properties. However, the equivalence does imply the existence of
constant-depth circuit implementations of logical Clifford gates on folded
surface codes. We achieve and improve this result by constructing two families
of folded surface codes with transversal Clifford gates. This construction is
presented generally for qudits of any dimension. The specific application of
these codes to universal quantum computation based on qubit fusion is also
discussed.


title:
Fermi-liquid behavior and thermal conductivity of {\epsilon}-iron at
  Earth's core conditions

abstract:
  The electronic state and transport properties of hot dense iron are of the
utmost importance to geophysics. Combining the density functional and dynamical
mean field theories we study the impact of electron correlations on electrical
and thermal resistivity of hexagonal close-packed $\epsilon$-Fe at Earth's core
conditions. $\epsilon$-Fe is found to behave as a nearly perfect Fermi liquid.
The quadratic dependence of the scattering rate in Fermi liquids leads to a
modification of the Wiedemann-Franz law with suppression of the thermal
conductivity as compared to the electrical one. This significantly increases
the electron-electron thermal resistivity which is found to be of comparable
magnitude to the electron-phonon one. The implications of this effect on the
dynamics of Earth's core is discussed.


title:
Meromorphic vector fields with single-valued solutions on complex
  surfaces

abstract:
  We study ordinary differential equations in the complex domain given by
meromorphic vector fields on K\"ahler compact complex surfaces. We prove that
if such an equation has a maximal single valued solution with Zariski-dense
image (in particular, if it has an entire one) then, up to a bimeromorphic
transformation, either the vector field is holomorphic or it preserves a
fibration.


title: Towards Kaluza-Klein Dark Matter on Nilmanifolds

abstract:
  We present a first study of the field spectrum on a class of
negatively-curved compact spaces: nilmanifolds or twisted tori. This is a case
where analytical results can be obtained, allowing to check numerical methods.
We focus on the Kaluza-Klein expansion of a scalar field. The results are then
applied to a toy model where a natural Dark Matter candidate arises as a stable
massive state of the bulk scalar.


title: Near-infrared scintillation of liquid argon

abstract:
  Since the 1970s it has been known that noble gases scintillate in the near
infrared (NIR) region of the spectrum (0.7 $\mu$m < $\lambda$; < 1.5$\mu$m).
More controversial has been the question of the NIR light yield for condensed
noble gases. We first present the motivation for using the NIR scintillation in
liquid argon detectors, then briefly review early as well as more recent
efforts and finally show encouraging preliminary results of a test performed at
Fermilab.


title:
The chemically homogeneous evolutionary channel for binary black hole
  mergers: rates and properties of gravitational-wave events detectable by
  advanced LIGO

abstract:
  We explore the predictions for detectable gravitational-wave signals from
merging binary black holes formed through chemically homogeneous evolution in
massive short-period stellar binaries. We find that $\sim 500$ events per year
could be detected with advanced ground-based detectors operating at full
sensitivity. We analyze the distribution of detectable events, and conclude
that there is a very strong preference for detecting events with nearly equal
components (mass ratio $>0.66$ at 90\% confidence in our default model) and
high masses (total source-frame mass between $57$ and $103\, M_\odot$ at 90\%
confidence). We consider multiple alternative variations to analyze the
sensitivity to uncertainties in the evolutionary physics and cosmological
parameters, and conclude that while the rates are sensitive to assumed
variations, the mass distributions are robust predictions. Finally, we consider
the recently reported results of the analysis of the first 16 double-coincident
days of the O1 LIGO (Laser Interferometer Gravitational-wave Observatory)
observing run, and find that this formation channel is fully consistent with
the inferred parameters of the GW150914 binary black hole detection and the
inferred merger rate.


title:
Double Weyl points and Fermi arcs of topological semimetals in
  non-Abelian gauge potentials

abstract:
  We study the effect of a non-Abelian SU(2) gauge potential on the topological
semimetal induced by a magnetic field having {\pi}-flux per plaquette and
acting on fermions in a cubic lattice. The Abelian {\pi}-flux term gives rise
to a spectrum characterized by Weyl points. When the non-Abelian part is turned
on, due to the presence of a C4 rotation symmetry, the Weyl points assume a
quadratic dispersion along two directions and constitute double monopoles for
the Berry curvature. We examine both analytically and numerically the main
features of this system, focusing on its gapless surface modes, the so-called
Fermi arcs. We discuss the stability of the system under confining hard-wall
and harmonic potentials, relevant for the implementation in ultracold atom
settings, and the effect of rotation symmetry breaking.

categories: cond-mat.quant-gas cond-mat.str-el cond-mat.supr-con hep-th


title: What slows you down? Your network or your device?

abstract:
  This study takes a close look at mobile web performance. The two main
parameters determining web page load time are the network speed and the
computing power of the end-user device. Based on data from real users, this
paper quantifies the relative importance of network and device. The findings
suggest that increased processing power of latest generation smart phones and
optimized browsers have a significant impact on web performance; up to 56%
reduction in median page load time from one generation to the following. The
cellular networks, on the other hand, have become so mature that the median
page load time on one fiber-to-the-home network (using wifi for the last meter)
is only 18-28% faster than cellular and the median page load time on one DSL
network is 19% slower compared to a well-deployed cellular network.


title:
Chaotic motion and the evolution of morphological components in a
  time-dependent model of a barred galaxy within a dark matter halo

abstract:
  Studies of dynamical stability (chaotic versus regular motion) in galactic
dynamics often rely on static analytical models of the total gravitational
potential. Potentials based upon self-consistent N-body simulations offer more
realistic models, fully incorporating the time-dependent nature of the systems.
Here we aim at analysing the fractions of chaotic motion within different
morphological components of the galaxy. We wish to investigate how the presence
of chaotic orbits evolves with time, and how their spatial distribution is
associated with morphological features of the galaxy. We employ a
time-dependent analytical potential model that was derived from an N-body
simulation of a strongly barred galaxy. With this analytical potential we may
follow the dynamical evolution of ensembles of orbits. Using the Generalized
Alignment Index (GALI) chaos detection method, we study the fraction of chaotic
orbits, sampling the dynamics of both the stellar disc and of the dark matter
halo. Within the stellar disc, the global trend is for chaotic motion to
decrease in time, specially in the region of the bar. We scrutinized the
different changes of regime during the evolution (orbits that are permanently
chaotic, permanently regular, those that begin regular and end chaotic, and
those that begin chaotic and end regular), tracing the types of orbits back to
their common origins. Within the dark matter halo, chaotic motion also
decreases globally in time. The inner halo (r < 5 kpc) is where most chaotic
orbits are found and it is the only region where chaotic orbits outnumber
regular orbits, in the early evolution.


title:
The First Eigenvalue of the Kohn-Laplace Operator in the Heisenberg
  Group

abstract:
  In this paper, by extending the notions of harmonic transplantation and
harmonic radius in the Heisenberg group, we give an upper bound for the first
eigenvalue for the following Dirichlet problem: $$(P_{\Omega}) \left\{
\begin{array}{lllll} -\Delta_{\mathbb{H}^1} u & = & \lambda u & \mbox{in} &
\Omega u & = & 0 & \mbox{on} & \partial \Omega, \end{array} \right.$$ where $
\Omega $ is a regular bounded domain of $ \mathbb{H}^1$ with smooth boundary
and $\Delta_{\mathbb{H}^1}$ is the Kohn-Laplace operator. Using the results of
P.Pansu which give the relation between the volume of $\Omega$ and the
perimeter of its boundary. we prove the following $$ \lambda_{1}( \Omega ) \leq
C_{\Omega} \displaystyle \frac{ l_{11}^2 }{ \displaystyle \max_{ \xi \in \Omega
} r_{\Omega}^2(\xi)} $$ where $l_{11} $ is the first strictly positive zero of
the Bessel function of first kind and order 1, $ C_{\Omega} $ is a constant
depending of $ \Omega $ and $r_{\Omega}(\xi) $ is the harmonic radius of $
\Omega $ at a point $\xi$ of $\Omega.$


title:
Many-body localization phase transition: A simplified strong-randomness
  approximate renormalization group

abstract:
  We present a simplified strong-randomness renormalization group (RG) that
captures some aspects of the many-body localization (MBL) phase transition in
generic disordered one-dimensional systems. This RG can be formulated
analytically, and the critical fixed point distribution and critical exponents
(that satisfy the Chayes inequality) are obtained to numerical precision by
solving integro-differential equations. This reproduces many, but not all, of
the qualitative features of the MBL phase transition that are suggested by
previous numerical work and approximate RG studies: our RG might serve as a
"zeroth-order" approximation for future RG studies. One interesting feature
that we highlight is that the rare Griffiths regions are fractal. For thermal
Griffiths regions within the MBL phase, this feature might be qualitatively
correctly captured by our RG. If this is correct beyond our approximations,
then these Griffiths effects are stronger than has been previously assumed.


title: TTC: A high-performance Compiler for Tensor Transpositions

abstract:
  We present TTC, an open-source parallel compiler for multidimensional tensor
transpositions. In order to generate high-performance C++ code, TTC explores a
number of optimizations, including software prefetching, blocking,
loop-reordering, and explicit vectorization. To evaluate the performance of
multidimensional transpositions across a range of possible use-cases, we also
release a benchmark covering arbitrary transpositions of up to six dimensions.
Performance results show that the routines generated by TTC achieve close to
peak memory bandwidth on both the Intel Haswell and the AMD Steamroller
architectures, and yield significant performance gains over modern compilers.
By implementing a set of pruning heuristics, TTC allows users to limit the
number of potential solutions; this option is especially useful when dealing
with high-dimensional tensors, as the search space might become prohibitively
large. Experiments indicate that when only 100 potential solutions are
considered, the resulting performance is about 99% of that achieved with
exhaustive search.


title: Free fall and cellular automata

abstract:
  Three reasonable hypotheses lead to the thesis that physical phenomena can be
described and simulated with cellular automata. In this work, we attempt to
describe the motion of a particle upon which a constant force is applied, with
a cellular automaton, in Newtonian physics, in Special Relativity, and in
General Relativity. The results are very different for these three theories.


title:
Quantitative $h$-principle for isotropic embeddings and applications to
  $C^0$-symplectic geometry

abstract:
  We prove here a quantitative $h$-principle statement that applies to
isotropic embeddings of discs. We then apply it to get $C^0$-flexibility and
rigidity results in symplectic geometry. On the flexible side, we prove that a
symplectic homeomorphism might take a symplectic disc to a smooth isotropic
one. We also get a $C^0$-rigidity result for the action of a symplectic
homeomorphism on the reduction of a coisotropic submanifold.


title: C+/H2 Gas in Star-Forming Clouds and Galaxies

abstract:
  We present analytic theory for the total column density of singly ionized
carbon (C+) in the optically thick photon dominated regions (PDRs) of far-UV
irradiated (star-forming) molecular clouds. We derive a simple formula for the
C+ column as a function of the cloud (hydrogen) density, the far-UV field
intensity, and metallicity, encompassing the wide range of galaxy conditions.
When assuming the typical relation between UV and density in the cold neutral
medium, the C+ column becomes a function of the metallicity alone. We verify
our analysis with detailed numerical PDR models. For optically thick gas, most
of the C+ column is mixed with hydrogen that is primarily molecular (H2), and
this "C+/H2" gas layer accounts for almost all of the `CO-dark' molecular gas
in PDRs. The C+/H2 column density is limited by dust shielding and is inversely
proportional to the metallicity down to ~0.1 solar. At lower metallicities, H2
line blocking dominates and the C+/H2 column saturates. Applying our theory to
CO surveys in low redshift spirals we estimate the fraction of C+/H2 gas out of
the total molecular gas to be typically ~0.4. At redshifts 1<z<3 in massive
disc galaxies the C+/H2 gas represents a very small fraction of the total
molecular gas (<0.16). This small fraction at high redshifts is due to the high
gas surface densities when compared to local galaxies.


title: Constructing Reducible Brill--Noether Curves

abstract:
  It was recently determined exactly through how many general points a
nondegenerate curve with nonspecial hyperplane section can pass. This gives
rise to a method of constructing reducible curves $C_1 \cup_\Gamma C_2 \to
\mathbb{P}^r$ with general nodes: We take a finite set $\Gamma \subset
\mathbb{P}^r$ of general points, and find nondegenerate nonspecial curves $C_1$
and $C_2$ in $\mathbb{P}^r$ of specified degrees and genera which pass through
$\Gamma$, and glue together along $\Gamma$. The goal of this paper is to show
that, subject to certain mild assumptions, stable maps constructed in this
manner lie in the closure of the locus of nondegenerate stable maps from curves
of general moduli, i.e. are BN-curves.
  As explained in arXiv:1809.05980, these results play a key role in the
author's proof of the Maximal Rank Conjecture.


title:
An Effective Selection Method for Low-Mass Active Black Holes and First
  Spectroscopic Identification

abstract:
  We present a new method to effectively select objects which may be low-mass
active black holes (BHs) at galaxy centers using high-cadence optical imaging
data, and our first spectroscopic identification of an active 2.7x10^6 Msun BH
at z=0.164. This active BH was originally selected due to its rapid optical
variability, from a few hours to a day, based on Subaru Hyper Suprime-Cam~(HSC)
g-band imaging data taken with 1-hour cadence. Broad and narrow H-alpha and
many other emission lines are detected in our optical spectra taken with Subaru
FOCAS, and the BH mass is measured via the broad H-alpha emission line width
(1,880 km s^{-1}) and luminosity (4.2x10^{40} erg s^{-1}) after careful
correction for the atmospheric absorption around 7,580-7,720A. We measure the
Eddington ratio to be as low as 0.05, considerably smaller than those in a
previous SDSS sample with similar BH mass and redshift, which indicates one of
the strong potentials of our Subaru survey. The g-r color and morphology of the
extended component indicate that the host galaxy is a star-forming galaxy. We
also show effectiveness of our variability selection for low-mass active BHs.


title:
Measurement of the t-tbar production cross section in the e-mu channel
  in proton-proton collisions at sqrt(s) = 7 and 8 TeV

abstract:
  The inclusive cross section for top quark pair production is measured in
proton-proton collisions at sqrt(s) = 7 and 8 TeV, corresponding to 5.0 and
19.7 invers-femtobarns, respectively, with the CMS experiment at the LHC. The
cross sections are measured in the electron-muon channel using a binned
likelihood fit to multi-differential final state distributions related to
identified b quark jets and other jets in the event. The measured cross section
values are 173.6 +/- 2.1 (stat) +4.5-4.0 (syst) +/- 3.8 (lumi) pb at sqrt(s) =
7 TeV, and 244.9 +/- 1.4 (stat) +6.3-5.5 (syst) +/- 6.4 (lumi) pb at sqrt(s) =
8 TeV, in good agreement with QCD calculations at next-to-next-to-leading-order
accuracy. The ratio of the cross sections measured at 7 and 8 TeV is
determined, as well as cross sections in the fiducial regions defined by the
acceptance requirements on the two charged leptons in the final state. The
cross section results are used to determine the top quark pole mass via the
dependence of the theoretically predicted cross section on the mass, giving a
best result of 173.8 +1.7-1.8 GeV. The data at sqrt(s) = 8 TeV are also used to
set limits, for two neutralino mass values, on the pair production of
supersymmetric top squarks with masses close to the top quark mass.


title: Fourier expansion of disk automorphisms via scattering in layered media

abstract:
  A family of orthogonal polynomials on the disk (which we call scattering
polynomials) serves to formulate a remarkable Fourier expansion of the
composition of a sequence of Poincar\'e disk automorphisms. Scattering
polynomials are tied to an exotic riemannian structure on the disk that is
hybrid between hyperbolic and euclidean geometries, and the expansion therefore
links this exotic structure to the usual hyperbolic one. The resulting identity
is intimately connected with the scattering of plane waves in piecewise
constant layered media. Indeed, a recently established combinatorial analysis
of scattering sequences provides a key ingredient of the proof. At the same
time, the polynomial obtained by truncation of the Fourier expansion elegantly
encodes the structure of the nonlinear measurement operator associated with the
finite time duration scattering experiment.


title: Quantum Emission from Defects in Single Crystal Hexagonal Boron Nitride

abstract:
  Bulk hexagonal boron nitride (hBN) is a highly nonlinear natural hyperbolic
material that attracts major attention in modern nanophotonics applications.
However, studies of its optical properties in the visible part of the spectrum
and quantum emitters hosted by bulk hBN have not been reported to date. In this
work we study the emission properties of hBN crystals in the red spectral range
using sub-bandgap optical excitation. Quantum emission from defects is observed
at room temperature and characterized in detail. Our results advance the use of
hBN in quantum nanophotonics technologies and enhance our fundamental
understanding of its optical properties.


title:
Accurate computation of surface stresses and forces with immersed
  boundary methods

abstract:
  Many immersed boundary methods solve for surface stresses that impose the
velocity boundary conditions on an immersed body. These surface stresses may
contain spurious oscillations that make them ill-suited for representing the
physical surface stresses on the body. Moreover, these inaccurate stresses
often lead to unphysical oscillations in the history of integrated surface
forces such as the coefficient of lift. While the errors in the surface
stresses and forces do not necessarily affect the convergence of the velocity
field, it is desirable, especially in fluid-structure interaction problems, to
obtain smooth and convergent stress distributions on the surface. To this end,
we show that the equation for the surface stresses is an integral equation of
the first kind whose ill-posedness is the source of spurious oscillations in
the stresses. We also demonstrate that for sufficiently smooth delta functions,
the oscillations may be filtered out to obtain physically accurate surface
stresses. The filtering is applied as a post-processing procedure, so that the
convergence of the velocity field is unaffected. We demonstrate the efficacy of
the method by computing stresses and forces that converge to the physical
stresses and forces for several test problems.


title:
On the use of Slater-type spinor orbitals in Dirac-Hartree-Fock method.
  Results for hydrogen-like atoms with super$-$critical nuclear charge

abstract:
  This work presents the formalism for evaluating molecular SCF equations, as
adapted to four$-$component Dirac spinors, which in turn reduce to
Slater$-$type orbitals with non$-$integer principal quantum numbers in the
non$-$relativistic limit. The "catastrophe" which emerges for a charge numbers
$Z>137$, in solving the Dirac equation with a potential corresponding to a
point$-$charge is avoided through using Slater$-$type spinor orbitals in the
algebraic approximation. It is observed that, ground$-$state energy of
hydrogen$-$like atoms reaches the negative$-$energy continuum $\left(-mc^2
\right)$ while critical nuclear charge $Z_{c}$, about $Z_{c}=160$. The
difficulty associated with finding relations for molecular integrals over
Slater$-$type spinors which are not$-$analytic in the sense of complex analysis
at $r = 0$, is eliminated. Unique numerical accuracy is provided by solving the
molecular integrals through Laplace expansion of Coulomb interaction and
prolate spheroidal coordinates. New convergent series representation formulae
are derived. The technique draws on previous work by the author and the general
formalism is presented in this paper.


title: Towards Automated Android App Collusion Detection

abstract:
  Android OS supports multiple communication methods between apps. This opens
the possibility to carry out threats in a collaborative fashion, c.f. the
Soundcomber example from 2011. In this paper we provide a concise definition of
collusion and report on a number of automated detection approaches, developed
in co-operation with Intel Security.


title:
The Lyman Continuum Escape Fraction of The Cosmic Horseshoe: A Test of
  Indirect Estimates

abstract:
  High redshift star-forming galaxies are likely responsible for the
reionization of the Universe, yet direct detection of their escaping ionizing
(Lyman continuum) photons has proven to be extremely challenging. In this
study, we search for escaping Lyman continuum of the Cosmic Horseshoe, a
gravitationally lensed, star-forming galaxy at z=2.38 with a large
magnification of $\sim24$. Transmission at wavelengths of low ionization
interstellar absorption lines in the rest-frame ultraviolet suggest a patchy,
partially transparent interstellar medium. This makes it an ideal candidate for
direct detection of the Lyman continuum. We obtained a 10-orbit Hubble near-UV
image using the WFC3/UVIS F275W filter that probes wavelengths just below the
Lyman limit at the redshift of the Horseshoe in an attempt to detect escaping
Lyman continuum radiation. After fully accounting for the uncertainties in the
opacity of the intergalactic medium as well as accounting for the charge
transfer inefficiency in the WFC3 CCDs, we find a $3 \sigma$ upper-limit for
the relative escape fraction of $f_{esc,rel}<0.08$. This value is a factor of
five lower than the value (0.4) predicted by the 40\% transmission in the
low-ion absorption lines. We discuss the possible causes for this discrepancy
and consider the implications for future attempts at both direct Lyman
continuum detection as well as indirect estimates of the escape fraction.


title: On almost-planar graphs

abstract:
  A nonplanar graph G is called almost-planar if for every edge e of G, at
least one of G\e and G/e is planar. In 1990, Gubser characterized 3-connected
almost-planar graphs in his dissertation. However, his proof is so long that
only a small portion of it was published. The main purpose of this paper is to
provide a short proof of this result. We also discuss the structure of
almost-planar graphs that are not 3-connected.


title:
Large discrete jumps observed in the transition between Chern states in
  a ferromagnetic Topological Insulator

abstract:
  A striking prediction in topological insulators is the appearance of the
quantized Hall resistance when the surface states are magnetized. The surface
Dirac states become gapped everywhere on the surface, but chiral edge states
remain on the edges. In an applied current, the edge states produce a quantized
Hall resistance that equals the Chern number C = +1 or -1 (in natural units),
even in zero magnetic field. This quantum anomalous Hall effect was observed by
Chang et al. With reversal of the magnetic field, the system is trapped in a
metastable state because of magnetic anisotropy. Here we investigate how the
system escapes the metastable state at low temperatures (10-200 mK). When the
dissipation (measured by the longitudinal resistance) is ultralow, we find that
the system escapes by making a few, very rapid transitions, as detected by
large jumps in the Hall and longitudinal resistances. Using the field at which
the initial jump occurs to estimate the escape rate, we find that raising the
temperature strongly suppresses the rate. From a detailed map of the resistance
vs. gate voltage and temperature, we show that dissipation strongly affects the
escape rate. We compare the observations with dissipative quantum tunneling
predictions. In the ultralow dissipation regime, there exist two temperature
scales T1 = 70 mK and T2 = 145 mK between which jumps can be observed. The
jumps display a spatial correlation that extends over a large fraction of the
sample.


title:
Asymptotic properties of Jacobi matrices for a family of fractal
  measures

abstract:
  We study the properties and asymptotics of the Jacobi matrices associated
with equilibrium measures of the weakly equilibrium Cantor sets. These family
of Cantor sets were defined and different aspects of orthogonal polynomials on
them were studied recently. Our main aim is numerically examine some
conjectures concerning orthogonal polynomials which do not directly follow from
previous results. We also compare our results with more general conjectures
made for recurrence coefficients associated with fractal measures supported on
$\mathbb{R}$.


title:
The role of attitudinal factors in mathematical on-line assessments: a
  study of undergraduate STEM students

abstract:
  This study explores student attitudes to the use of substantive on-line
assessments that require mathematical answers. Our goal is to learn what are
the important aspects in a design of more effective e-assessments that support
learning of mathematical subjects in a higher education setting. To that end we
analyse the effects of a variety of attitudinal factors towards such
assessments amongst a cross-section of 1st year students in an English
University. These students were all previously exposed to on-line assessments
containing substantial mathematical work, including testing of and feedback on
the algebraic structure of their answers. They were provided with detailed
online feedback, and we therefore specifically examine the effect of formative
feedback on the usage of educational technology. Our results suggest that
students find on-line feedback more enjoyable and useful than traditional
feedback. 'Attitude' and 'Enjoyment' are the two most important factors
influencing their usage intention. Our results also show that, even for this
digital generation, confidence in using computers and the availability of
support for using information technology are important factors in making
effective use of on-line assessments.


title:
Fluids confined in wedges and by edges: virial series for the
  line-thermodynamic properties of hard spheres

abstract:
  This work is devoted to analyze the relation between the thermodynamic
properties of a confined fluid and the shape of its confining vessel. Recently,
new insights in this topic were found through the study of cluster integrals
for inhomogeneous fluids, that revealed the dependence on the vessel shape of
the low density behavior of the system. Here, the statistical mechanics and
thermodynamics of fluids confined in wedges or by edges is revisited, focusing
on their cluster integrals. In particular, the well known hard sphere fluid,
which was not studied in this framework so far, is analyzed under confinement
and its thermodynamic properties are analytically studied up to order two in
the density. Furthermore, the analysis is extended to the confinement produced
by a corrugated wall. These results rely on the obtained analytic expression
for the second cluster integral of the confined hard sphere system as a
function of the opening dihedral angle $0<\beta<2\pi$. It enables a unified
approach to both wedges and edges.


title:
Jet azimuthal angle correlations in the production of a Higgs boson pair
  plus two jets at hadron colliders

abstract:
  Azimuthal angle correlations of two jets in the process $pp\to HHjj$ are
studied. The loop induced $\mathcal{O}(\alpha_s^4 \alpha_{}^2)$ gluon fusion
(GF) sub-process and the $\mathcal{O}(\alpha_{}^4)$ weak boson fusion (WBF)
sub-process are considered. The GF sub-process exhibits strong correlations in
the azimuthal angles $\phi_{1,2}^{}$ of the two jets measured from the
production plane of the Higgs boson pair and the difference between these two
angles $\phi_1^{}-\phi_2^{}$, and a very small correlation in the sum of them
$\phi_1^{}+\phi_2^{}$. The impact of using a finite top mass $m_t^{}$ value on
the correlations is found crucial. The transverse momentum of the Higgs boson
can be used to enhance or suppress the correlations. The impact of a
non-standard value for the triple Higgs self-coupling on the correlations is
found much smaller than that on other observables, such as the invariant mass
of the two Higgs bosons. The peak shifts of the azimuthal angle distributions
reflect the magnitude of parity violation in the $gg\to HH$ amplitude and the
dependence of the distributions on parity violating phases is analytically
clarified. The WBF sub-process also produces correlated distributions and it is
found that they are not induced by the quantum effect of the intermediate weak
bosons but mainly by a kinematic effect. This kinematic effect is a
characteristic feature of the WBF sub-process and is not observed in the GF
sub-process. It is found that the correlations are different in the GF and in
the WBF sub-processes. As part of the process dependent information, they will
be helpful in the analyses of both the GF sub-process and the WBF sub-process
at the LHC.


title:
Kirillov-Frenkel character formula for Loop groups, radial part and
  Brownian sheet

abstract:
  We consider the coadjoint action of a Loop group of a compact group on the
dual of the corresponding centrally extended Loop algebra and prove that a
Brownian motion in a Cartan subalgebra conditioned to remain in an affine Weyl
chamber - which can be seen as a space time conditioned Brownian motion - is
distributed as the radial part process of a Brownian sheet on the underlying
Lie algebra.


title:
Aggregated evaluation of operation quality of complex hierarchical
  network systems

abstract:
  The main approaches for the formation of generalized conclusions about
operation quality of complex hierarchical network systems are analized.
Advantages and drawbacks of the "weakest" element method and a weighted linear
aggregation method are determined. Nonlinear aggregation method is proposed for
evaluating the quality of the systems, which consist of elements of the same
priority. Hybrid approaches to form generalized conclusions are developed based
on the main aggregation methods. It is shown that they allow to obtain more
reliable aggregation results.


title:
Optical Space Singularities: Ultrasonic Induced Artificial Black Holes
  in Phononic Crystals

abstract:
  Ultrasonic standing waves in a cylindrical enclosure can achieve very high
local pressures at the acoustic nodes (~1 MPa). When the acoustic wave passes
through a phononic crystal comprised of steel and glycerin, there are regions
of constructive interference resulting in even higher local pressures (~100
MPa). At these highly localized pressure points inside the crystal, the
equations describing the acoustics break down and the mathematics of
gravitational fields are more appropriate. These pressures are so high as to
create optical space singularities, analogous to cosmological phenomena. We
measure a redshift for light passing through this system and describe how the
optical space thus created can be described by elementary equations of a
non-rotating black hole.


title:
Symplectic singularity of curves with semigroups (4,5,6,7), (4,5,6) and
  (4,5,7)

abstract:
  We study the local symplectic algebra of curves with semigroups $(4,5,6,7)$,
$(4,5,6)$ and $(4,5,7)$. We use the method of algebraic restrictions to
parameterized curves as in \cite{D1}. A new discrete invariant for algebraic
restrictions to parameterized quasi-homogeneous curves is introduced. This
invariant together with the method of algebraic restriction can distinguish
different symplectic orbits of quasi-homogeneous curves.


title: Overlapping hot spots and charge modulation in cuprates

abstract:
  Particle-hole instabilities are studied within a two dimensional model of
fermions interacting with antiferromagnetic spin fluctuations (spin-fermion
model). In contrast to previous works, we assume that neighboring hot spots
overlap due to a shallow dispersion of the electron spectrum in the antinodal
region and include in the consideration effects of a remnant low energy and
momentum Coulomb interaction. It turns out that this modification of the model
drastically changes the behavior of the system. The leading particle-hole
instability at not very weak fermion-fermion interaction is no longer a charge
density wave with a modulation along the diagonals of the Brillouin zone
predicted previously but a Pomeranchuk-type deformation of the Fermi surface
breaking the C$_{4}$ symmetry of the system. This order does not prevent from
further phase transitions at lower temperatures. We show that, depending on
parameters of the interaction, either d-wave superconductivity or charge
density wave with modulations along the bonds of the $CuO$ lattice is possible.
The low momentum remnant Coulomb interaction enhances the d-form factor of the
charge density wave. Comparison with experimental data allows us to conclude
that in many cuprate compounds the conditions for the proposed scenario are
indeed fulfilled. Our results may explain important features of the charge
modulations observed recently.


title: Terminal Embeddings

abstract:
  In this paper we study {\em terminal embeddings}, in which one is given a
finite metric $(X,d_X)$ (or a graph $G=(V,E)$) and a subset $K \subseteq X$ of
its points are designated as {\em terminals}. The objective is to embed the
metric into a normed space, while approximately preserving all distances among
pairs that contain a terminal. We devise such embeddings in various settings,
and conclude that even though we have to preserve $\approx|K|\cdot |X|$ pairs,
the distortion depends only on $|K|$, rather than on $|X|$.
  We also strengthen this notion, and consider embeddings that approximately
preserve the distances between {\em all} pairs, but provide improved distortion
for pairs containing a terminal. Surprisingly, we show that such embeddings
exist in many settings, and have optimal distortion bounds both with respect to
$X \times X$ and with respect to $K \times X$.
  Moreover, our embeddings have implications to the areas of Approximation and
Online Algorithms. In particular, [ALN08] devised an $\tilde{O}(\sqrt{\log
r})$-approximation algorithm for sparsest-cut instances with $r$ demands.
Building on their framework, we provide an $\tilde{O}(\sqrt{\log
|K|})$-approximation for sparsest-cut instances in which each demand is
incident on one of the vertices of $K$ (aka, terminals). Since $|K| \le r$, our
bound generalizes that of [ALN08].


title: The galaxy luminosity function and the Local Hole

abstract:
  Whitbourn & Shanks (2014) have reported evidence for a local void underdense
by ~15% extending to 150-300h-1Mpc around our position in the Southern Galactic
Cap (SGC). Assuming a local luminosity function they modelled K- and r-limited
number counts and redshift distributions in the 6dFGS/2MASS and SDSS redshift
surveys and derived normalised n(z) ratios relative to the standard homogeneous
cosmological model. Here we test further these results using maximum likelihood
techniques that solve for the galaxy density distributions and the galaxy
luminosity function simultaneously. We confirm the results from the previous
analysis in terms of the number density distributions, indicating that our
detection of the 'Local Hole' in the SGC is robust to the assumption of either
our previous, or newly estimated, luminosity functions. However, there are
discrepancies with previously published K and r band luminosity functions. In
particular the r-band luminosity function has a steeper faint end slope than
the r0.1 results of Blanton et al. (2003) but is consistent with the r0.1
results of Montero-Dorta & Prada (2009); Loveday et al. (2012).


title: Finitness Principles for Smooth Selection

abstract:
  In this paper we prove finiteness principles for $C^{m}\left( \mathbb{R}^{n},
\mathbb{R}^{D}\right) $-selection, and for $C^{m-1,1}\left( \mathbb{R}^{n},
\mathbb{R}^{D}\right) $-selection, in particular providing a proof for a
conjecture of Brudyni-Shvartsman (1994) on Lipschitz selections for the case
when the domain is $X = \mathbb{R}^n$.


title:
Constant Approximation for Capacitated $k$-Median with $(1 +
  \epsilon)$-Capacity Violation

abstract:
  We study the Capacitated k-Median problem for which existing constant-factor
approximation algorithms are all pseudo-approximations that violate either the
capacities or the upper bound k on the number of open facilities. Using the
natural LP relaxation for the problem, one can only hope to get the violation
factor down to 2. Li [SODA'16] introduced a novel LP to go beyond the limit of
2 and gave a constant-factor approximation algorithm that opens $(1 + \epsilon
)k$ facilities.
  We use the configuration LP of Li [SODA'16] to give a constant-factor
approximation for the Capacitated k-Median problem in a seemingly harder
configuration: we violate only the capacities by $1 + \epsilon $. This result
settles the problem as far as pseudo-approximation algorithms are concerned.


title:
Dynamically encircling exceptional points in a waveguide: asymmetric
  mode switching from the breakdown of adiabaticity

abstract:
  Physical systems with loss or gain feature resonant modes that are decaying
or growing exponentially with time. Whenever two such modes coalesce both in
their resonant frequency and their rate of decay or growth, a so-called
"exceptional point" occurs, around which many fascinating phenomena have
recently been reported to arise. Particularly intriguing behavior is predicted
to appear when encircling an exceptional point sufficiently slowly, like a
state-flip or the accumulation of a geometric phase. Experiments dedicated to
this issue could already successfully explore the topological structure of
exceptional points, but a full dynamical encircling and the breakdown of
adiabaticity inevitably associated with it remained out of reach of any
measurement so far. Here we demonstrate that a dynamical encircling of an
exceptional point can be mapped onto the problem of scattering through a
two-mode waveguide, which allows us for the first time to access the elusive
effects occurring in this context. Specifically, we present experimental
results from a waveguide structure that steers incoming waves around an
exceptional point during the transmission process. In this way mode transitions
are induced that make this device perfectly suited as a robust and asymmetric
switch between different waveguide modes. Our work opens up new and exciting
avenues to explore exceptional point physics at the crossroads between
fundamental research and practical applications.


title:
Surprising coincidence of the apparent 2D metal-to-insulator transition
  data with Fermi-gas based model results

abstract:
  The melting condition for two-dimensional Wigner solid ( P.M. Platzman,
H.Fukuyama, 1974) is shown to contain an error of a factor of $\pi$. The
analysis of experimental data for apparent 2D metal-to-insulator transition
shows that the Wigner solidification (B.Tanatar, D.M.Ceperley, 1989) has been
never achieved. Within routine Fermi gas model both the metallic and insulating
behavior of different 2D system for actual range of carrier densities and
temperatures is explained.


title:
Shear viscosity of p-wave superfluid Fermi gas with weak interaction at
  low temperatures

abstract:
  The shear viscosity tensor of the superfluid Fermi gas in p-wave state with
weak interaction is calculated at low temperatures, by using the Boltzmann
equation approach. We consider the transition probabilities for the binary,
decay and coalescence processes. We show that only the binary processes are
dominated at low temperatures and the components of shear viscosity {\eta}_xy,
{\eta}_xx, {\eta}_yy are proportional to (1/T)^2, and {\eta}_xz, {\eta}_yz and
{\eta}_zz are proportional to (1/T)^4 and (1/T)^6, respectively.


title: Cryptosystems Using Automorphisms of Finitely Generated Free Groups

abstract:
  This paper introduces a newly developed private key cryptosystem and a public
key cryptosystem. In the first one, each letter is encrypted with a different
key. Therefore, it is a kind of a one-time pad. The second one is inspired by
the ElGamal cryptosystem. Both presented cryptosystems are based on
automorphisms of free groups. Given a free group $F$ of finite rank, the
automorphism group $Aut(F)$ can be generated by Nielsen transformations, which
are the basis of a linear technique to study free groups and general infinite
groups. Therefore Nielsen transformations are introduced.


title: A Multi-Grid Iterative Method for Photoacoustic Tomography

abstract:
  Inspired by the recent advances on minimizing nonsmooth or bound-constrained
convex functions on models using varying degrees of fidelity, we propose a line
search multigrid (MG) method for full-wave iterative image reconstruction in
photoacoustic tomography (PAT) in heterogeneous media. To compute the search
direction at each iteration, we decide between the gradient at the target
level, or alternatively an approximate error correction at a coarser level,
relying on some predefined criteria. To incorporate absorption and dispersion,
we derive the analytical adjoint directly from the first-order acoustic wave
system. The effectiveness of the proposed method is tested on a total-variation
penalized Iterative Shrinkage Thresholding algorithm (ISTA) and its accelerated
variant (FISTA), which have been used in many studies of image reconstruction
in PAT. The results show the great potential of the proposed method in
improving speed of iterative image reconstruction.


title: Interpolation of data by smooth non-negative functions

abstract:
  We prove a finiteness principle for interpolation of data by nonnegative Cm
functions. Our result raises the hope that one can start to understand
constrained interpolation problems in which e.g. the interpolating function F
is required to be nonnegative.


title:
Dark Matter as a consequence of electric charge non-conservation - will
  it remain dark forever?

abstract:
  It is conjectured that dark matter (DM) was produced before inflation from
neutral particles present after the Big Bang and survived inflation due to a
specific coupling with gravitation, while the charged particles existing after
the Big Bang disappeared during inflation in a process of charge
non-conservation. Ordinary matter was produced at a later stage at a lower
temperature following a symmetry restoring phase transition. In this way the
non-luminous character of dark matter and the existence of two types of matter,
ordinary and dark, get a natural explanation. Because of the high temperatures
preceding inflation, the masses of particles produced during that time are too
large to be detected by conventional particle physics methods and possibly will
never be detected.


title:
Measuring the extent of convective cores in low-mass stars using Kepler
  data: towards a calibration of core overshooting

abstract:
  Our poor understanding of the boundaries of convective cores generates large
uncertainties on the extent of these cores and thus on stellar ages. Our aim is
to use asteroseismology to consistently measure the extent of convective cores
in a sample of main-sequence stars whose masses lie around the mass-limit for
having a convective core. We first test and validate a seismic diagnostic that
was proposed to probe in a model-dependent way the extent of convective cores
using the so-called $r_{010}$ ratios, which are built with $l=0$ and $l=1$
modes. We apply this procedure to 24 low-mass stars chosen among Kepler targets
to optimize the efficiency of this diagnostic. For this purpose, we compute
grids of stellar models with both the CESAM2k and MESA evolution codes, where
the extensions of convective cores are modeled either by an instantaneous
mixing or as a diffusion process. Among the selected targets, we are able to
unambiguously detect convective cores in eight stars and we obtain seismic
measurements of the extent of the mixed core in these targets with a good
agreement between the CESAM2k and MESA codes. By performing optimizations using
the Levenberg-Marquardt algorithm, we then obtain estimates of the amount of
extra-mixing beyond the core that is required in CESAM2k to reproduce seismic
observations for these eight stars and we show that this can be used to propose
a calibration of this quantity. This calibration depends on the prescription
chosen for the extra-mixing, but we find that it should be valid also for the
code MESA, provided the same prescription is used. This study constitutes a
first step towards the calibration of the extension of convective cores in
low-mass stars, which will help reduce the uncertainties on the ages of these
stars.


title: Nucleon-deuteron scattering using the adiabatic projection method

abstract:
  In this paper we discuss the adiabatic projection method, a general framework
for scattering and reaction calculations on the lattice. We also introduce
several new techniques developed to study nucleus-nucleus scattering and
reactions on the lattice. We present technical details of the method for
large-scale problems. To estimate the systematic errors of the calculations we
consider simple two-particle scattering on the lattice. Then we benchmark the
accuracy and efficiency of the numerical methods by applying these to calculate
fermion-dimer scattering in lattice effective field theory with and without a
long-range Coulomb potential. The fermion-dimer calculations correspond to
neutron-deuteron and proton-deuteron scattering in the spin-quartet channel at
leading order in the pionless effective field theory.


title: The intercalation chemistry of layered iron chalcogenide superconductors

abstract:
  The iron chalcogenides FeSe and FeS are superconductors composed of
two-dimensional sheets held together by van der Waals interactions, which makes
them prime candidates for the intercalation of various guest species. We review
the intercalation chemistry of FeSe and FeS superconductors and discuss their
synthesis, structure, and physical properties. Before we review the latest work
in this area, we provide a brief background on the intercalation chemistry of
other inorganic materials that exhibit enhanced superconducting properties upon
intercalation, which include the transition metal dichalcogenides, fullerenes,
and layered cobalt oxides. From past studies of these intercalated
superconductors, we discuss the role of the intercalates in terms of charge
doping, structural distortions, and Fermi surface reconstruction. We also
briefly review the physical and chemical properties of the host
materials---mackinawite-type FeS and $\beta$-FeSe. The three types of
intercalates for the iron chalcogenides can be placed in three categories: 1.)
alkali and alkaline earth cations intercalated through the liquid ammonia
technique; 2.) cations intercalated with organic amines such as
ethylenediamine; and 3.) layered hydroxides intercalated during hydrothermal
conditions. A recurring theme in these studies is the role of the intercalated
guest in electron doping the chalcogenide host and in enhancing the
two-dimensionality of the electronic structure by spacing the FeSe layers
apart. We end this review discussing possible new avenues in the intercalation
chemistry of transition metal monochalcogenides, and the promise of these
materials as a unique set of new inorganic two-dimensional systems.


title:
Constants of motion for Isoperimetric Variational Problems with Time
  Delay

abstract:
  In the present work, we obtain the constants of motion for isoperimetric
variational problems with time delay. We consider a constrained optimization
problem where the Lagrangian function defining the functional depends on time
delayed arguments. We prove the isoperimetric Euler--Lagrange and
DuBois--Reymond type optimality conditions and, in order to investigate the
constants of motion for this problem, we obtain a nonsmooth extension of
Noether's symmetry theorem for isoperimetric variational problems with delayed
arguments.


title: Leptonic CP phases near the $\mu-\tau$ symmetric limit

abstract:
  The neutrino masses and mixings indicated by current neutrino oscillation
experiments suggest that the neutrino mass matrix possesses an approximate
$\mu-\tau$ exchange symmetry. In this study, we explore the neutrino parameter
space and show that if a small $\mu-\tau$ symmetry breaking is considered, the
Majorana $CP$ phases must be unequal and non-zero independently of the neutrino
mass scale. Moreover, a small $\mu-\tau$ symmetry breaking favors
quasi-degenerate masses. We also show that Majorana phases are strongly
correlated with the Dirac $CP$ violating phase. Within this framework, we
obtain robust predictions for the values of the Majorana phases when the
experimental indications for the Dirac $CP$ phase are used.


title:
Swarming in viscous fluids: three-dimensional patterns in swimmer- and
  force-induced flows

abstract:
  We derive from first principles a three-dimensional theory of self-propelled
particle swarming in a viscous fluid environment. Our model predicts emergent
collective behavior that depends critically on fluid opacity, mechanism of
self-propulsion, and type of particle-particle interaction. In "clear fluids"
swimmers have full knowledge of their surroundings and can adjust their
velocities with respect to the lab frame, while in "opaque fluids," they
control their velocities only in relation to the local fluid flow. We also show
that "social" interactions that affect only a particle's propensity to swim
towards or away from neighbors induces a flow field that is qualitatively
different from the long-ranged flow fields generated by direct "physical"
interactions. The latter can be short-ranged but lead to much longer-ranged
fluid-mediated hydrodynamic forces, effectively amplifying the range over which
particles interact. These different fluid flows conspire to profoundly affect
swarm morphology, kinetically stabilizing or destabilizing swarm configurations
that would arise in the absence of fluid. Depending upon the overall
interaction potential, the mechanism of swimming (e.g., pushers or pullers),
and the degree of fluid opaqueness, we discover a number of new collective
three-dimensional patterns including flocks with prolate or oblate shapes,
recirculating peloton-like structures, and jet-like fluid flows that entrain
particles mediating their escape from the center of mill-like structures. Our
results reveal how the interplay among general physical elements influence
fluid-mediated interactions and the self-organization, mobility, and stability
of new three-dimensional swarms and suggest how they might be used to
kinetically control their collective behavior.


title:
Enhanced high-temperature performance of GaN light-emitting diodes grown
  on silicon substrates

abstract:
  We compare the temperature dependence of optical and electrical
characteristics of commercially available GaN light-emitting diodes (LEDs)
grown on silicon and sapphire substrates. Contrary to conventional
expectations, LEDs grown on silicon substrates, commonly referred to as
GaN-on-Si LEDs, show less efficiency droop at higher temperatures even with
more threading dislocations. Analysis of the junction temperature reveals that
GaN-on-Si LEDs have a cooler junction despite sharing identical epitaxial
structures and packaging compared to LEDs grown on sapphire substrates. We also
observe a decrease in ideality factor with increase in ambient temperature for
GaN-on-Si LEDs, indicating an increase in ideal diode current with temperature.
Analysis of the strain and temperature coefficient measurements suggests that
there is an increase in hole transport efficiency within the active region for
GaN-on-Si LEDs compared to the LEDs grown on sapphire, which accounts for the
less temperature-dependent efficiency droop.


title: Distributed TensorFlow with MPI

abstract:
  Machine Learning and Data Mining (MLDM) algorithms are becoming increasingly
important in analyzing large volume of data generated by simulations,
experiments and mobile devices. With increasing data volume, distributed memory
systems (such as tightly connected supercomputers or cloud computing systems)
are becoming important in designing in-memory and massively parallel MLDM
algorithms. Yet, the majority of open source MLDM software is limited to
sequential execution with a few supporting multi-core/many-core execution.
  In this paper, we extend recently proposed Google TensorFlow for execution on
large scale clusters using Message Passing Interface (MPI). Our approach
requires minimal changes to the TensorFlow runtime -- making the proposed
implementation generic and readily usable to increasingly large users of
TensorFlow. We evaluate our implementation using an InfiniBand cluster and
several well knowndatasets. Our evaluation indicates the efficiency of our
proposed implementation.