title:
Platinum/Yttrium Iron Garnet Inverted Structures for Spin Current
  Transport

abstract:
  30-80 nm thick yttrium iron garnet (YIG) films are grown by pulsed laser
deposition on a 5 nm thick sputtered Pt atop gadolinium gallium garnet
substrate (GGG) (110). Upon post-growth rapid thermal annealing, single crystal
YIG(110) emerges as if it were epitaxially grown on GGG(110) despite the
presence of the intermediate Pt film. The YIG surface shows atomic steps with
the root-mean-square roughness of 0.12 nm on flat terraces. Both Pt/YIG and
GGG/Pt interfaces are atomically sharp. The resulting YIG(110) films show clear
in-plane uniaxial magnetic anisotropy with a well-defined easy axis along <001>
and a peak-to-peak ferromagnetic resonance linewidth of 7.5 Oe at 9.32 GHz,
similar to YIG epitaxilly grown on GGG. Both spin Hall magnetoresistance and
longitudinal spin Seebeck effects in the inverted bilayers indicate excellent
Pt/YIG interface quality.


title: Sparse Quadrature for High-Dimensional Integration with Gaussian Measure

abstract:
  In this work we analyze the dimension-independent convergence property of an
abstract sparse quadrature scheme for numerical integration of functions of
high-dimensional parameters with Gaussian measure. Under certain assumptions of
the exactness and the boundedness of univariate quadrature rules as well as the
regularity of the parametric functions with respect to the parameters, we
obtain the convergence rate $O(N^{-s})$, where $N$ is the number of indices,
and $s$ is independent of the number of the parameter dimensions. Moreover, we
propose both an a-priori and an a-posteriori schemes for the construction of a
practical sparse quadrature rule and perform numerical experiments to
demonstrate their dimension-independent convergence rates.


title:
Topological Semimetals with Triply Degenerate Nodal Points in
  \theta-phase Tantalum Nitride

abstract:
  Using first-principles calculation and symmetry analysis, we propose that
\theta-TaN is a topological semimetal having a new type of point nodes, i.e.,
triply degenerate nodal points. Each node is a band crossing between degenerate
and non-degenerate bands along the high-symmetry line in the Brillouin zone,
and is protected by crystalline symmetries. Such new type of nodes will always
generate singular touching points between different Fermi surfaces and 3D spin
texture around them. Breaking the crystalline symmetry by external magnetic
field or strain leads to various of topological phases. By studying the Landau
levels under a small field along $c$-axis, we demonstrate that the system has a
new quantum anomaly that we call "helical anomaly".


title:
Pluto's global surface composition through pixel-by-pixel Hapke modeling
  of New Horizons Ralph/LEISA data

abstract:
  On July 14th 2015, NASA's New Horizons mission gave us an unprecedented
detailed view of the Pluto system. The complex compositional diversity of
Pluto's encounter hemisphere was revealed by the Ralph/LEISA infrared
spectrometer on board of New Horizons. We present compositional maps of Pluto
defining the spatial distribution of the abundance and textural properties of
the volatiles methane and nitrogen ices and non-volatiles water ice and tholin.
These results are obtained by applying a pixel-by-pixel Hapke radiative
transfer model to the LEISA scans. Our analysis focuses mainly on the large
scale latitudinal variations of methane and nitrogen ices and aims at setting
observational constraints to volatile transport models. Specifically, we find
three latitudinal bands: the first, enriched in methane, extends from the pole
to 55deg N, the second dominated by nitrogen, continues south to 35deg N, and
the third, composed again mainly of methane, reaches 20deg N. We demonstrate
that the distribution of volatiles across these surface units can be explained
by differences in insolation over the past few decades. The latitudinal pattern
is broken by Sputnik Planitia, a large reservoir of volatiles, with nitrogen
playing the most important role. The physical properties of methane and
nitrogen in this region are suggestive of the presence of a cold trap or
possible volatile stratification. Furthermore our modeling results point to a
possible sublimation transport of nitrogen from the northwest edge of Sputnik
Planitia toward the south.


title: Bounds on trilinear and quadrilinear exponential sums

abstract:
  We use an estimate of Aksoy Yazici, Murphy, Rudnev and Shkredov (2016) on the
number of solutions of certain equations involving products and differences of
sets in prime finite fields to give an explicit upper bound on trilinear
exponential sums which improves the previous bound of Bourgain and Garaev
(2009). We also obtain explicit bounds for quadrilinear exponential sums.


title: Score matching estimators for directional distributions

abstract:
  One of the major problems for maximum likelihood estimation in the
well-established directional models is that the normalising constants can be
difficult to evaluate. A new general method of "score matching estimation" is
presented here on a compact oriented Riemannian manifold. Important
applications include von Mises-Fisher, Bingham and joint models on the sphere
and related spaces. The estimator is consistent and asymptotically normally
distributed under mild regularity conditions. Further, it is easy to compute as
a solution of a linear set of equations and requires no knowledge of the
normalizing constant. Several examples are given, both analytic and numerical,
to demonstrate its good performance.


title: Conformal Patterson-Walker metrics

abstract:
  The classical Patterson-Walker construction of a split-signature
(pseudo-)Riemannian structure from a given torsion-free affine connection is
generalized to a construction of a split-signature conformal structure from a
given projective class of connections. A characterization of the induced
structures is obtained. We achieve a complete description of Einstein metrics
in the conformal class formed by the Patterson-Walker metric. Finally, we
describe all symmetries of the conformal Patterson-Walker metric. In both cases
we obtain descriptions in terms of geometric data on the original structure.


title: Beyond the black box

abstract:
  We describe the role the open-source software community plays in fixing bugs
through a case study of a problem with integer determinant computations in
SageMath.


title: On the Krein-Milman-Ky Fan theorem for convex compact metrizable sets

abstract:
  The Krein-Milman theorem (1940) states that every convex compact subset of a
Hausdorfflocally convex topological space, is the closed convex hull of its
extreme points. In 1963, Ky Fan extended the Krein-Milman theorem to the
general framework of $\Phi$-convexity. Under general conditions on the class of
functions $\Phi$, the Krein-Milman-Ky Fan theorem asserts then, that every
compact $\Phi$-convex subset of a Hausdorff space, is the $\Phi$-convex hull of
its $\Phi$-extremal points. We prove in this paper that, in the metrizable case
the situation is rather better. Indeed, we can replace the set of
$\Phi$-extremal points by the smaller subset of $\Phi$-exposed points. We
establish under general conditions on the class of functions $\Phi$, that every
$\Phi$-convex compact metrizable subset of a Hausdorff space, is the
$\Phi$-convex hull of its $\Phi$-exposed points. As a consequence we obtain
that each convex weak compact metrizable (resp. convex weak$^*$ compact
metrizable) subset of a Banach space (resp. of a dual Banach space), is the
closed convex hull of its exposed points (resp. the weak$^*$ closed convex hull
of its weak$^*$ exposed points). This result fails in general for compact
$\Phi$-convex subsets that are not metrizable.


title:
Comparison of Coherent Smith-Purcell radiation and Coherent Transition
  Radiation

abstract:
  Smith-Purcell radiation and Transition Radiation are two radiative phenomenon
that occur in charged particles accelerators. For both the emission can be
significantly enhanced with sufficiently short pulses and both can be used to
measure the form factor of the pulse. We compare the yield of these phenomenon
in different configurations and look at their application as bunch length
monitors, including background filtering and rejection. We apply these
calculations to the specific case of the CLIO Free Electron laser.


title:
Asymptotic Stabilizability of Underactuated Hamiltonian Systems With Two
  Degrees of Freedom

abstract:
  For an underactuated (simple) Hamiltonian system with two degrees of freedom
and one degree of underactuation, a rather general condition that ensures its
stabilizability, by means of the existence of a (simple) Lyapunov function, was
found in a recent paper by D.E. Chang within the context of the energy shaping
method. Also, in the same paper, some additional assumptions were presented in
order to ensure also asymptotic stabilizability. In this paper we extend these
results by showing that above mentioned condition is not only sufficient, but
also a necessary one. And, more importantly, we show that no additional
assumption is needed to ensure asymptotic stabilizability.


title:
Unit Consistency, Generalized Inverses, and Effective System Design
  Methods

abstract:
  This paper examines the potential role of unit consistency as a system design
principle. Unit-consistent generalized matrix inverses and unit-invariant
matrix decompositions are derived in support of this principle. Applications of
the methods described are illustrated with examples relating to nonlinear
system identification and robustness to multiplicative noise for image database
retrieval.


title: Rotating Thin-Shell Wormhole

abstract:
  We construct a rotating thin-shell wormhole using a Myers-Perry black hole in
five dimensions, using the Darmois-Israel junction conditions. The stability of
the wormhole is analyzed under perturbations. We find that exotic matter is
required at the throat of the wormhole to keep it stable. Our analysis shows
that stability of the rotating thin-shell wormhole is possible if suitable
parameter values are chosen.


title: Classifying spaces for families of subgroups for systolic groups

abstract:
  We determine the large scale geometry of the minimal displacement set of a
hyperbolic isometry of a systolic complex. As a consequence, we describe the
centraliser of such an isometry in a systolic group. Using these results, we
construct a low-dimensional classifying space for the family of virtually
cyclic subgroups of a group acting properly on a systolic complex. Its
dimension coincides with the topological dimension of the complex if the latter
is at least four. We show that graphical small cancellation complexes are
classifying spaces for proper actions and that the groups acting on them
properly admit three-dimensional classifying spaces with virtually cyclic
stabilisers. This is achieved by constructing a systolic complex equivariantly
homotopy equivalent to a graphical small cancellation complex. On the way we
develop a systematic approach to graphical small cancellation complexes.
Finally, we construct low-dimensional models for the family of virtually
abelian subgroups for systolic, graphical small cancellation, and some CAT(0)
groups.


title: Localization of wave packets in one-dimensional random potentials

abstract:
  We study the expansion of an initially strongly confined wave packet in a
one-dimensional weak random potential with short correlation length. At long
times, the expansion of the wave packet comes to a halt due to destructive
interferences leading to Anderson localization. We develop an analytical
description for the disorder-averaged localized density profile. For this
purpose, we employ the diagrammatic method of Berezinskii which we extend to
the case of wave packets, present an analytical expression of the Lyapunov
exponent which is valid for small as well as for high energies and, finally,
develop a self-consistent Born approximation in order to analytically calculate
the energy distribution of our wave packet. By comparison with numerical
simulations, we show that our theory describes well the complete localized
density profile, not only in the tails, but also in the center.


title: On the equivalence between $\Theta_{n}$-spaces and iterated Segal spaces

abstract:
  We give a new proof of the equivalence between two of the main models for
$(\infty,n)$-categories, namely the $n$-fold Segal spaces of Barwick and the
$\Theta_{n}$-spaces of Rezk, by proving that these are algebras for the same
monad on the $\infty$-category of $n$-globular spaces. The proof works for a
broad class of $\infty$-categories that includes all $\infty$-topoi.


title:
Perturbation Series in Light-Cone Diagrams of Green Function of String
  Field

abstract:
  In this paper, we proved the correspondence between Feynman diagrams in
space-time and light-cone diagrams in world-sheet by using only path integral
representation on free Green function in the first quantization theory. We also
obtained general representation on perturbation series of light-cone diagrams
describing split and join of strings.


title:
Lepton mixing patterns from the group $\Sigma(36\times3)$ with a
  generalized CP transformation

abstract:
  The group $\Sigma(36\times3)$ with the generalized CP transformation is
introduced to predict the mixing pattern of leptons. Various combinations of
abelian residual flavor symmetries with CP transformations are surveyed. Six
mixing patterns could accommodate the fit data of neutrinos oscillation at
$3\sigma$ level. Among them, two patterns predict the nontrivial Dirac CP
phase, around $\pm 57^{\circ}$ or $\pm 123^{\circ}$, which is in accordance
with the result of the literature and the recent fit data. Furthermore, one
pattern could satisfy the experimental constraints at $1\sigma$ level.


title:
SU Lyncis, a hard X-ray bright M giant: Clues point to a large hidden
  population of symbiotic stars

abstract:
  Symbiotic star surveys have traditionally relied almost exclusively on low
resolution optical spectroscopy. However, we can obtain a more reliable
estimate of their total Galactic population by using all available signatures
of the symbiotic phenomenon. Here we report the discovery of a hard X-ray
source, 4PBC J0642.9+5528, in the Swift hard X-ray all-sky survey, and identify
it with a poorly studied red giant, SU Lyn, using pointed Swift observations
and ground-based optical spectroscopy. The X-ray spectrum, the optical to UV
spectrum, and the rapid UV variability of SU Lyn are all consistent with our
interpretation that it is a symbiotic star containing an accreting white dwarf.
The symbiotic nature of SU Lyn went unnoticed until now, because it does not
exhibit emission lines strong enough to be obvious in low resolution spectra.
We argue that symbiotic stars without shell-burning have weak emission lines,
and that the current lists of symbiotic stars are biased in favor of
shell-burning systems. We conclude that the true population of symbiotic stars
has been underestimated, potentially by a large factor.


title:
Architectural Impact on Performance of In-memory Data Analytics: Apache
  Spark Case Study

abstract:
  While cluster computing frameworks are continuously evolving to provide
real-time data analysis capabilities, Apache Spark has managed to be at the
forefront of big data analytics for being a unified framework for both, batch
and stream data processing. However, recent studies on micro-architectural
characterization of in-memory data analytics are limited to only batch
processing workloads. We compare micro-architectural performance of batch
processing and stream processing workloads in Apache Spark using hardware
performance counters on a dual socket server. In our evaluation experiments, we
have found that batch processing are stream processing workloads have similar
micro-architectural characteristics and are bounded by the latency of frequent
data access to DRAM. For data accesses we have found that simultaneous
multi-threading is effective in hiding the data latencies. We have also
observed that (i) data locality on NUMA nodes can improve the performance by
10% on average and(ii) disabling next-line L1-D prefetchers can reduce the
execution time by up-to 14\% and (iii) multiple small executors can provide
up-to 36\% speedup over single large executor.


title:
An optimization problem in heat conduction with minimal temperature
  constraint, interior heating and exterior insulation

abstract:
  We show the existence and optimal regularity of the optimal temperature
configuration in a problem in heat conduction with minimal temperature
constraint, interior heating and exterior insulation. Regularity of the two
free boundaries is also studied.


title:
Numerical assessments of ocean energy extraction from western boundary
  currents using a quasi-geostrophic ocean circulation model

abstract:
  A single-layer, quasi-geostrophic (QG), large-scale ocean circulation model
is developed in this paper to study available ocean current energy potentials
harnessed by using the ocean current turbines. Power extraction is modeled by
adding a parameterized Rayleigh friction term in the barotropic vorticity
equation. Numerical assessments are performed by simulating a set of
mid-latitude ocean basins in the beta plane, which are standard prototypes of
more realistic ocean dynamics considering inter-decadal variability in
turbulent equilibrium. A sensitivity analysis with respect to the turbine
parameters is performed for various physical conditions. Results show that the
proposed model captures the quasi-stationary ocean dynamics and provides the
four-gyre circulation patterns in time mean. After an initial spin-up process,
the proposed model reaches a statistically steady state at an average maximum
speed between 1.5 m/s and 2.5 m/s, which is close to the observed maximum zonal
velocities in the western boundary currents. The probability density function
of the available power over a long time period is computed for a wide range of
parameters. Numerical results shows that 10 GW mean power can be extracted from
the turbines distributed over a length scale of 100 km along the western
boundaries. However, it is demonstrated that bigger turbine areas would alter
the flow patterns and energetics due to excessive dissipation. An increase in
the turbine area results in an increase in the available power ranging from 8
to 22 GW depending on the values of turbine modeling parameters. This first
step in the numerical assessment of the proposed QG model shows that the
present framework could represent a viable tool for evaluating energy
potentials in a highly turbulent flow regime.


title: Mastering hysteresis in magnetocaloric materials

abstract:
  Hysteresis is more than just an interesting oddity, which occurs in materials
with a first-order transition. It is a real obstacle on the path from existing
lab-scale prototypes of magnetic refrigerators towards commercialization of
this potentially disruptive cooling technology. Indeed, the reversibility of
the magnetocaloric effect, being essential for magnetic heat pumps, strongly
depends on the width of the thermal hysteresis and therefore it is necessary to
understand the mechanisms causing hysteresis and to find solutions how to
minimize losses associated with thermal hysteresis in order to maximize the
efficiency of magnetic cooling devices. In this work, we discuss fundamental
aspects, which can contribute to thermal hysteresis and we are developing
strategies for at least partially overcoming the hysteresis problem in some
selected classes of magnetocaloric materials with large application potential.
Doing so, we refer to the most relevant classes of magnetic refrigerants
La-Fe-Si-, Heusler- and Fe2P-type compounds.


title: Quadratic forms and semiclassical eigenfunction hypothesis for flat tori

abstract:
  Let $Q(X)$ be any integral primitive positive definite quadratic form with
discriminant $D$ and in $k$ variables where $k\geq4$. We give an upper bound on
the number of integral solutions of $Q(X)=n$ for any integer $n$ in terms of
$n$, $k$ and $D$. As a corollary, we give a definite answer to a conjecture of
Rudnick and Lester on the small scale equidistribution of orthonormal basis of
eigenfunctions restricted to an individual eigenspace on the flat torus
$\mathbb{T}^d$ for $d\geq 5$. Another application of our main theorem gives a
sharp upper bound on $A_{d}(n,t)$, the number of representation of the positive
definite quadratic form $Q(x,y)=nx^2+2txy+ny^2$ as a sum of squares of $d\geq
5$ linear forms where $n- n^{\frac{1}{(d-1)}-o(1)}< t < n$. This upper bound
allows us to study the local statistics of integral points on sphere.


title: On the L\^e-Milnor fibration for real analytic maps

abstract:
  In this paper, we study the topology of real analytic map-germs with isolated
critical value $f: (\mathbb{R}^m,0) \to (\mathbb{R}^n,0)$, with $1 <n <m$. We
compare the topology of $f$ with the topology of the compositions $\pi_i^*
\circ f$, where $\pi_i^*: \mathbb{R}^n \to \mathbb{R}^{n-1}$ are the
projections $(t_1, \dots, t_n) \mapsto (t_1, \dots, t_{i-1}, t_{i+1}, \dots,
t_n)$, for $i=1, \dots, n$. As a main result, we give necessary and sufficient
conditions for $f$ to have a L\^e-Milnor fibration in the tube.


title: RITM: Revocation in the Middle

abstract:
  Although TLS is used on a daily basis by many critical applications, the
public-key infrastructure that it relies on still lacks an adequate revocation
mechanism. An ideal revocation mechanism should be inexpensive, efficient,
secure, and privacy-preserving. Moreover, rising trends in pervasive encryption
pose new scalability challenges that a modern revocation system should address.
In this paper, we investigate how network nodes can deliver
certificate-validity information to clients. We present RITM, a framework in
which middleboxes (as opposed to clients, servers, or certification
authorities) store revocation-related data. RITM provides a secure
revocation-checking mechanism that preserves user privacy. We also propose to
take advantage of content-delivery networks (CDNs) and argue that they would
constitute a fast and cost-effective way to disseminate revocations.
Additionally, RITM keeps certification authorities accountable for the
revocations that they have issued, and it minimizes overhead at clients and
servers, as they have to neither store nor download any messages. We also
describe feasible deployment models and present an evaluation of RITM to
demonstrate its feasibility and benefits in a real-world deployment.


title: Fully Dynamic Maximal Matching in Constant Update Time

abstract:
  Baswana, Gupta and Sen [FOCS'11] showed that fully dynamic maximal matching
can be maintained in general graphs with logarithmic amortized update time.
More specifically, starting from an empty graph on $n$ fixed vertices, they
devised a randomized algorithm for maintaining maximal matching over any
sequence of $t$ edge insertions and deletions with a total runtime of $O(t \log
n)$ in expectation and $O(t \log n + n \log^2 n)$ with high probability.
Whether or not this runtime bound can be improved towards $O(t)$ has remained
an important open problem. Despite significant research efforts, this question
has resisted numerous attempts at resolution even for basic graph families such
as forests.
  In this paper, we resolve the question in the affirmative, by presenting a
randomized algorithm for maintaining maximal matching in general graphs with
\emph{constant} amortized update time. The optimal runtime bound $O(t)$ of our
algorithm holds both in expectation and with high probability.
  As an immediate corollary, we can maintain 2-approximate vertex cover with
constant amortized update time. This result is essentially the best one can
hope for (under the unique games conjecture) in the context of dynamic
approximate vertex cover, culminating a long line of research.
  Our algorithm builds on Baswana et al.'s algorithm, but is inherently
different and arguably simpler. As an implication of our simplified approach,
the space usage of our algorithm is linear in the (dynamic) graph size, while
the space usage of Baswana et al.'s algorithm is always at least $\Omega(n \log
n)$.
  Finally, we present applications to approximate weighted matchings and to
distributed networks.


title: Spontaneous pulsing states in an active particle system

abstract:
  We study a two-lane two-species exclusion process inspired by Lin et al. (C.
Lin et al. J. Stat. Mech., 2011), that exhibits a non-equilibrium pulsing
phase. Particles move on two parallel one-dimensional tracks, with one open and
one reflecting boundary. The particle type defines the hopping direction. When
only particles hopping towards the open end are allowed to change lane, the
system exhibits a phase transition from a low density phase to a pulsing phase
depending on the ratio between particle injection and type-changing rate. This
phase transition can be observed in the stochastic model as well as in a
mean-field description. In the low density phase, the density profile can be
predicted analytically. The pulsing phase is characterised by a fast filling of
the system and - once filled - by a slowly backwards moving front separating a
decreasing dense region and an expanding low density region. The hopping of the
front on the discrete lattice is found to create density oscillations, both, in
time and space. By means of a stability analysis we can predict the structure
of the dense region during the emptying process, characterised by exponentially
damped perturbations, both at the open end and near the moving front.


title: New Limits on Double Electron Capture of $^{40}$Ca and $^{180}$W

abstract:
  We analyzed low-background data from the CRESST-II experiment with a total
net exposure of 730 kg days to extract limits on double electron capture
processes. We established new limits for $^{40}$Ca with
$T_{1/2}^{2v2K}>9.9\times10^{21}$ y and $T_{1/2}^{0v2EC}>1.4\times10^{22}$ y
and for $^{180}$W with T$_{1/2}^{2v2K}>3.1\times10^{19}$ y and
$T_{1/2}^{0v2EC}>9.4\times10^{18}$ y at 90% CL. Depending on the process, these
values improve the currently best limits by a factor of $\sim$1.4-30.


title:
Limit distribution of Translated pieces of possibly irrational leaves in
  S-arithmetic homogeneous spaces

abstract:
  The purpose of this article is to describe and characterize the limit
distributions of translates of a bounded open "piece of orbit" of a reductive
subgroup on a space of S-arithmetic lattices. This is accomplished under a mild
assumption of "analytic stability" on the sequence of translates. It is
important to note however that it is not necessary to assume that the reductive
subgroup or its centralizer are algebraic. Moreover, it is also not necessary
to assume that the initial orbit is of finite measure or even closed. This
article thus provides important generalizations on previously known results and
opens ways to new applications in number theory, two of which are briefly
mentioned.


title:
Asymptotics of three-body bound state radial wave functions of halo
  nuclei involving two charged particles

abstract:
  Asymptotic expressions for the radial and full wave functions of a three{body
bound halo nuclear system with two charged particles in relative coordinates
are obtained in explicit form, when the relative distance between two particles
tends to infinity. The obtained asymptotic forms are applied to the analysis of
the asymptotic behavior of the three-body (pn?) wave functions for the halo
($E^*=3.562$ MeV, $J^{\pi}=0^+$, $T=1$) state of $^6$Li derived by D. Baye
within the Lagrange-mesh method for two forms of the $\alpha N$ -potential. The
agreement between the calculated wave function and the asymptotic formula is
excellent for distances up to 30 fm. Information about the values of the
three-body asymptotic normalization functions is extracted. It is shown that
the extracted values of the three-body asymptotic normalization function are
sensitive to the form of the $\alpha N$ -potential. The mirror symmetry is
revealed for the three-body asymptotic normalization functions derived for the
isobaric ($^6$He, $^6$Li) pair.


title:
Scoping of material response under DEMO neutron irradiation: comparison
  with fission and influence of nuclear library selection

abstract:
  Predictions of material activation inventories will be a key input to
virtually all aspects of the operation, safety and environmental assessment of
future fusion nuclear plants. Additionally, the neutron-induced transmutation
(change) of material composition (inventory) with time, and the creation and
evolution of configurational damage from atomic displacements, require precise
quantification because they can lead to significant changes in material
properties, and thus influence reactor-component lifetime. A comprehensive
scoping study has been performed to quantify the activation, transmutation
(depletion and build-up) and immediate damage response under neutron
irradiation for all naturally occurring elements from hydrogen to bismuth. The
resulting database provides a global picture of the response of a material,
covering the majority of nuclear technological space, but focussing
specifically on typical conditions expected for a demonstration fusion power
plant (DEMO). Results from fusion are compared against typical fission
conditions for selected fusion relevant materials, demonstrating that the
latter cannot be relied upon to give accurate scalable experimental predictions
of material response in a future fusion reactor. Results from different nuclear
data libraries are also compared, highlighting the variations and deficiencies.


title:
Influence of halide composition on the structural, electronic, and
  optical properties of mixed CH$_3$NH$_3$Pb(I$_{1-x}$Br$_x$)$_3$ perovskites
  calculated using the virtual crystal approximation method

abstract:
  We investigate the structural, electronic and optical properties of mixed
bromide-iodide lead perovskite solar cell CH$_3$NH$_3$Pb(I$_{1-x}$Br$_x$)$_3$
by means of the virtual crystal approximation (VCA) within density functional
theory (DFT). Optimizing the atomic positions and lattice parameters increasing
the bromide content $x$ from 0.0 to 1.0, we fit the calculated lattice
parameter and energy band gap to the linear and quadratic function of Br
content, respectively, which are in good agreement with the experiment,
respecting the Vegard's law. With the calculated exciton binding energy and
light absorption coefficient, we make sure that VCA gives consistent results
with the experiment, and the mixed halide perovskites are suitable for
generating the charge carriers by light absorption and conducting the carriers
easily due to their strong photon absorption coefficient, low exciton bindign
energy, and high carrier mobility at low Br contents. Furthermore analyzing the
bonding lengths between Pb and X (I$_{1-x}$Br$_x$: virtual atom) as well as C
and N, we stress that the stability of perovskite solar cell is definitely
improved at $x$=0.2.


title:
Ab initio thermodynamic study of SnO$_2$(110) surface in an O$_2$ and NO
  environment: a fundamental understanding of gas sensing mechanism for NO and
  NO$_2$

abstract:
  For the purpose of elucidating the gas sensing mechanism of SnO$_2$ for NO
and NO$_2$ gases, we calculate the phase diagram of SnO$_2$(110) surface in
contact with an O$_2$ and NO gas environment by means of {\it ab initio}
thermodynamic method. Firstly we build a range of surface slab models of oxygen
pre-adsorbed SnO$_2$(110) surfaces using (1$\times$1) and (2$\times$1) surface
unit cells and calculate their Gibbs free energies considering only oxygen
chemical potential. The fully reduced surface containing the bridging and
in-plane oxygen vacancies in the oxygen-poor condition, while the fully
oxidized surface containing the bridging oxygen and oxygen dimer in the
oxygen-rich condition, and the stoichiometric surface in between, were proved
to be most stable. Using the selected plausible NO-adsorbed surfaces, we then
determine the surface phase diagram of SnO$_2$(110) surfaces in
($\Delta\mu_\text{O}$, $\Delta\mu_\text{NO}$) space. In the NO-rich condition,
the most stable surfaces were those formed by NO adsorption on the most stable
surfaces in contact with only oxygen gas. Through the analysis of electronic
charge transferring and density of states during NO$_x$ adsorption on the
surface, we provide a meaningful understanding about the gas sensing mechanism.


title:
Experimental study on the influence of binders on plastic deformation
  during sintering of cubic boron nitride powder under high pressure and high
  temperature

abstract:
  In this work, sintered polycrystalline cubic boron nitride (cBN) compacts,
with titanium carbonitride (TiC0.7N0.3) and titanium nitride (TiN),
respectively, as binders, were prepared at temperature of 1450{\deg}C and
pressure of 5.5 GPa during 3 minutes, and the influence of binders on the
plastic deformation of cBN powder due to the sintering process was
experimentally investigated by X-ray diffraction (XRD) analysis. It was shown
that the sintered compact with titanium carbonitride as a binder displays more
intense plastic deformation of cBN grains than that with titanium nitride
binder. This result indicated that if the binders are different, then products
formed during sintering of cBN powders under high pressure and high temperature
(HP-HT) are different so that the stress concentration at the cBN grain
boundaries and a pinning effect, reducing the mobility of the dislocations and
preventing annealing, are different in two cases.


title:
Detection of epileptic seizure in EEG signals using linear least squares
  preprocessing

abstract:
  An epileptic seizure is a transient event of abnormal excessive neuronal
discharge in the brain. This unwanted event can be obstructed by detection of
electrical changes in the brain that happen before the seizure takes place. The
automatic detection of seizures is necessary since the visual screening of EEG
recordings is a time consuming task and requires experts to improve the
diagnosis. Four linear least squares-based preprocessing models are proposed to
extract key features of an EEG signal in order to detect seizures. The first
two models are newly developed. The original signal (EEG) is approximated by a
sinusoidal curve. Its amplitude is formed by a polynomial function and compared
with the pre developed spline function.Different statistical measures namely
classification accuracy, true positive and negative rates, false positive and
negative rates and precision are utilized to assess the performance of the
proposed models. These metrics are derived from confusion matrices obtained
from classifiers. Different classifiers are used over the original dataset and
the set of extracted features. The proposed models significantly reduce the
dimension of the classification problem and the computational time while the
classification accuracy is improved in most cases. The first and third models
are promising feature extraction methods. Logistic, LazyIB1, LazyIB5 and J48
are the best classifiers. Their true positive and negative rates are $1$ while
false positive and negative rates are zero and the corresponding precision
values are $1$. Numerical results suggest that these models are robust and
efficient for detecting epileptic seizure.


title:
Array Program Transformation with Loo.py by Example: High-Order Finite
  Elements

abstract:
  To concisely and effectively demonstrate the capabilities of our program
transformation system Loo.py, we examine a transformation path from two
real-world Fortran subroutines as found in a weather model to a single
high-performance computational kernel suitable for execution on modern GPU
hardware. Along the transformation path, we encounter kernel fusion,
vectorization, prefetch- ing, parallelization, and algorithmic changes achieved
by mechanized conversion between imperative and functional/substitution- based
code, among a number more. We conclude with performance results that
demonstrate the effects and support the effectiveness of the applied
transformations.


title: The colored HOMFLYPT function is $q$-holonomic

abstract:
  We prove that the HOMFLYPT polynomial of a link, colored by partitions with a
fixed number of rows is a $q$-holonomic function. Specializing to the case of
knots colored by a partition with a single row, it proves the existence of an
$(a,q)$ super-polynomial of knots in 3-space, as was conjectured by string
theorists. Our proof uses skew Howe duality that reduces the evaluation of web
diagrams and their ladders to a Poincare-Birkhoff-Witt computation of an
auxiliary quantum group of rank the number of strings of the ladder diagram.


title: Two-dimensional moduli spaces of irregular Higgs bundles

abstract:
  We give a complete description of the two-dimensional moduli spaces of stable
Higgs bundles of rank 2 over complex projective line with one irregular
singular point, having a regular leading-order term, and endowed with a generic
compatible parabolic structure such that the parabolic degree of the Higgs
bundle is 0. Our method relies on elliptic fibrations of the rational elliptic
surface, an equivalence of categories between irregular Higgs bundles and some
sheaves on a ruled surface, and an analysis of stability conditions.


title: Detecting "Smart" Spammers On Social Network: A Topic Model Approach

abstract:
  Spammer detection on social network is a challenging problem. The rigid
anti-spam rules have resulted in emergence of "smart" spammers. They resemble
legitimate users who are difficult to identify. In this paper, we present a
novel spammer classification approach based on Latent Dirichlet
Allocation(LDA), a topic model. Our approach extracts both the local and the
global information of topic distribution patterns, which capture the essence of
spamming. Tested on one benchmark dataset and one self-collected dataset, our
proposed method outperforms other state-of-the-art methods in terms of averaged
F1-score.


title: Radio Galaxies Dominate the High-Energy Diffuse Gamma-Ray Background

abstract:
  It has been suggested that unresolved radio galaxies and radio quasars
(sometimes referred to as misaligned active galactic nuclei) could be
responsible for a significant fraction of the observed diffuse gamma-ray
background. In this study, we use the latest data from the Fermi Gamma-Ray
Space Telescope to characterize the gamma-ray emission from a sample of 51
radio galaxies. In addition to those sources that had previously been detected
using Fermi data, we report here the first statistically significant detection
of gamma-ray emission from the radio galaxies 3C 212, 3C 411, and B3 0309+411B.
Combining this information with the radio fluxes, radio luminosity function,
and redshift distribution of this source class, we find that radio galaxies
dominate the diffuse gamma-ray background, generating $77.2^{+25.4}_{-9.4}\%$
of this emission at energies above $\sim$1 GeV. We discuss the implications of
this result and point out that it provides support for scenarios in which
IceCube's high-energy astrophysical neutrinos also originate from the same
population of radio galaxies.


title: Probing the diamagnetic term in light-matter interaction

abstract:
  We address the quantum estimation of the diamagnetic, or $A^2$, term in an
effective model of light-matter interaction featuring two coupled oscillators.
First, we calculate the quantum Fisher information of the diamagnetic parameter
in the interacting ground state. Then, we find that typical measurements on the
transverse radiation field, such as homodyne detection or photon counting,
permit to estimate the diamagnetic coupling constant with near-optimal
efficiency in a wide range of model parameters. Should the model admit a
critical point, we also find that both measurements would become asymptotically
optimal in its vicinity. Finally, we discuss binary discrimination strategies
between the two most debated hypotheses involving the diamagnetic term in
circuit QED. While we adopt a terminology appropriate to the Coulomb gauge, our
results are also relevant for the electric dipole gauge. In that case, our
calculations would describe the estimation of the so-called transverse $P^2$
term. The derived metrological benchmarks are general and relevant to any
implementation of the model, cavity and circuit QED being two relevant
examples.

categories: quant-ph cond-mat.other math-ph math.MP physics.atom-ph physics.optics


title:
Graph Decompositions Analysis and Comparison for Cohesive Subgraphs
  Detection

abstract:
  Massive networks have shown that the determination of dense subgraphs, where
vertices interact a lot, is necessary in order to visualize groups of common
interest, and therefore be able to decompose a big graph into smaller
structures. Many decompositions have been built over the years as part of
research in the graph mining field, and the topic is becoming a trend in the
last decade because of the increasing size of social networks and databases.
Here, we analyse some of the decompositions methods and also present a novel
one, the Vertex Triangle k-core. We then compare them and test them against
each other. Moreover, we establish different kind of measures for comparing the
accuracy of the decomposition methods. We apply these decompositions to real
world graphs, like the Collaboration network of arXiv graph, and found some
interesting results.


title:
Individual structural connectivity defines propagation networks in
  partial epilepsy

abstract:
  Neural network oscillations are a fundamental mechanism for cognition,
perception and consciousness. Consequently, perturbations of network activity
play an important role in the pathophysiology of brain disorders. When
structural information from non-invasive brain imaging is merged with
mathematical modeling, then generative brain network models constitute
in-silico platforms for the exploration of causal mechanisms of brain function
and clinical hypothesis testing. We here demonstrate along the example of
drug-resistant epilepsy that patient-specific virtual brain models derived from
diffusion MRI have sufficient predictive power to improve diagnosis and surgery
outcome. In partial epilepsy, seizures originate in a local network, the
so-called epileptogenic zone, before recruiting other close or distant brain
regions. We create personalized large-scale brain networks for 15 patients and
simulate the individual seizure propagation patterns. Model validation is
performed against the presurgical stereotactic electroencephalography (SEEG)
data and the standard-of-care clinical evaluation. We demonstrate that the
individual brain models account for the temporal variability in patient seizure
propagation patterns and explain the variability in postsurgical success. Our
results show that individual variations in structural connectivity, when linked
with mathematical dynamic models, have the capacity to explain changes in
spatiotemporal organization of brain dynamics as observed in network-based
brain disorders, thus opening up avenues towards discovery of novel clinical
interventions.


title:
Anomalous conductivity, Hall factor, magnetoresistance, and thermopower
  of accumulation layer in $\text{SrTiO}_3$

abstract:
  We study the low temperature conductivity of the electron accumulation layer
induced by the very strong electric field at the surface of $\text{SrTiO}_3$
sample. Due to the strongly nonlinear lattice dielectric response, the
three-dimensional density of electrons $n(x)$ in such a layer decays with the
distance from the surface $x$ very slowly as $n(x) \propto 1/x^{12/7}$. We show
that when the mobility is limited by the surface scattering the contribution of
such a tail to the conductivity diverges at large $x$ because of growing time
electrons need to reach the surface. We explore truncation of this divergence
by the finite sample width, by the bulk scattering rate, or by the crossover to
the bulk linear dielectric response with the dielectric constant $\kappa$. As a
result we arrive at the anomalously large mobility, which depends not only on
the rate of the surface scattering, but also on the physics of truncation.
Similar anomalous behavior is found for the Hall factor, the magnetoresistance,
and the thermopower.


title: Failures of the Integral Hasse Principle for Affine Quadric Surfaces

abstract:
  Quadric hypersurfaces are well-known to satisfy the Hasse principle. However,
this is no longer true in the case of the Hasse principle for integral points,
where counter-examples are known to exist in dimension 1 and 2. This work
explores the frequency that such counter-examples arise in a family of affine
quadric surfaces defined over the integers.


title: Bypassing the energy-time uncertainty in time-resolved photoemission

abstract:
  The energy-time uncertainty is an intrinsic limit for time-resolved
experiments imposing a tradeoff between the duration of the light pulses used
in experiments and their frequency content. In standard time-resolved
photoemission, this limitation maps directly onto a tradeoff between the time
resolution of the experiment and the energy resolution that can be achieved on
the electronic spectral function. Here we propose a protocol to disentangle the
energy and time resolutions in photoemission. We demonstrate that dynamical
information on all time scales can be retrieved from time-resolved
photoemission experiments using suitably shaped light pulses of quantum or
classical nature. As a paradigmatic example, we study the dynamical buildup of
the Kondo peak, a narrow feature in the electronic response function arising
from the screening of a magnetic impurity by the conduction electrons. After a
quench, the electronic screening builds up on timescales shorter than the
inverse width of the Kondo peak and we demonstrate that the proposed
experimental scheme could be used to measure the intrinsic time scales of such
electronic screening. The proposed approach provides an experimental framework
to access the nonequilibrium response of collective electronic properties
beyond the spectral uncertainty limit and will enable the direct measurement of
phenomena such as excited Higgs modes and, possibly, the retarded interactions
in superconducting systems.


title: Moduli Vacuum Misalignment and Precise Predictions in String Inflation

abstract:
  The predictions for all the cosmological observables of any inflationary
model depend on the number of e-foldings which is sensitive to the
post-inflationary history of the universe. In string models the generic
presence of light moduli leads to a late-time period of matter domination which
lowers the required number of e-foldings and, in turn, modifies the exact
predictions of any inflationary model. In this paper we compute exactly the
shift of the number of e-foldings in Kaehler moduli inflation which is
determined by the magnitude of the moduli initial displacement caused by vacuum
misalignment and the moduli decay rates. We find that the preferred number of
e-foldings gets reduced from 50 to 45, causing a modification of the spectral
index at the percent level. Our results illustrate the importance of
understanding the full post-inflationary evolution of the universe in order to
derive precise predictions in string inflation. To perform this task it is
crucial to work in a setting where there is good control over moduli
stabilisation.


title:
A characterization of singular packing subspaces with an application to
  limit-periodic operators

abstract:
  A new characterization of the singular packing subspaces of general bounded
self-adjoint operators is presented, which is used to show that the set of
operators whose spectral measures have upper packing dimension equal to one is
a $G_\delta$ (in suitable metric spaces). As an application, it is proven that,
generically (in space of continuous sampling functions), spectral measures of
the limit-periodic Schr\"odinger operators have upper packing dimensions equal
to one. Consequently, in a generic set, these operators are quasiballistic.


title:
Searching for an oscillating massive scalar field as a dark matter
  candidate using atomic hyperfine frequency comparisons

abstract:
  We use six years of accurate hyperfine frequency comparison data of the dual
rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a
massive scalar dark matter candidate. Such a scalar field can induce harmonic
variations of the fine structure constant, of the mass of fermions and of the
quantum chromodynamic mass scale, which will directly impact the
rubidium/caesium hyperfine transition frequency ratio. We find no signal
consistent with a scalar dark matter candidate but provide improved constraints
on the coupling of the putative scalar field to standard matter. Our limits are
complementary to previous results that were only sensitive to the fine
structure constant, and improve them by more than an order of magnitude when
only a coupling to electromagnetism is assumed.


title: Bounds for convection between rough boundaries

abstract:
  We consider Rayleigh-B\'enard convection in a layer of fluid between rough
no-slip boundaries where the top and bottom boundary heights are functions of
the horizontal coordinates with square-integrable gradients. We use the
background method to derive an upper bound on mean heat flux across the layer
for all admissible boundary geometries. This flux, normalized by the
temperature difference between the boundaries, can grow with the Rayleigh
number ($Ra$) no faster than ${\cal O}(Ra^{1/2})$ as $Ra \rightarrow \infty$.
Our analysis yields a family of similar bounds, depending on how various
estimates are tuned, but every version depends explicitly on the boundary
geometry. In one version the coefficient of the ${\cal O}(Ra^{1/2})$ leading
term is $0.242 + 2.925\Vert\nabla h\Vert^2$, where $\Vert\nabla h\Vert^2$ is
the mean squared magnitude of the boundary height gradients. Application to a
particular geometry is illustrated for sinusoidal boundaries.


title: Robust Joint Alignment of Multiple Versions of a Piece of Music

abstract:
  Large music content libraries often comprise multiple versions of a piece of
music. To establish a link between different versions, automatic music
alignment methods map each position in one version to a corresponding position
in another version. Due to the leeway in interpreting a piece, any two versions
can differ significantly, for example, in terms of local tempo, articulation,
or playing style. For a given pair of versions, these differences can be
significant such that even state-of-the-art methods fail to identify a correct
alignment. In this paper, we present a novel method that increases the
robustness for difficult to align cases. Instead of aligning only pairs of
versions as done in previous methods, our method aligns multiple versions in a
joint manner. This way, the alignment can be computed by comparing each version
not only with one but with several versions, which stabilizes the comparison
and leads to an increase in alignment robustness. Using recordings from the
Mazurka Project, the alignment error for our proposed method was 14% lower on
average compared to a state-of-the-art method, with significantly less outliers
(standard deviation 53% lower).


title: Equivariant Gr\"obner bases of symmetric toric ideals

abstract:
  It has been shown previously that a large class of monomial maps equivariant
under the action of an infinite symmetric group have finitely generated kernels
up to the symmetric action. We prove that these symmetric toric ideals also
have finite Gr\"obner bases up to symmetry for certain monomial orders. An
algorithm is presented for computing equivariant Gr\"obner bases that
terminates whenever a finite basis exists, improving on previous algorithms
that only guaranteed termination in rings Noetherian up to symmetry. This
algorithm can be used to compute equivariant Gr\"obner bases of the above toric
ideals, given the monomial map.


title: Ergodicity in randomly perturbed quantum systems

abstract:
  The theoretical cornerstone of statistical mechanics is the ergodic
assumption that all accessible configurations of a physical system are equally
likely. Here we show how such property arises when an open quantum system is
continuously perturbed by an external environment effectively observing the
system at random times while the system dynamics approaches the quantum Zeno
regime. In this context, by large deviation theory we analytically show how the
most probable value of the probability for the system to be in a given state
eventually deviates from the non-stochastic case when the Zeno condition is not
satisfied. We experimentally test our results with ultra-cold atoms prepared on
an atom chip.


title:
Tailoring the core electron density in modulation-doped Core-Multi-Shell
  nanowires

abstract:
  We show how a proper radial modulation of the composition of core-multi-shell
nanowires critically enhances the control of the free-carrier density in the
high-mobility core with respect to core-single-shell structures, thus
overcoming the technological difficulty of fine tuning the remote doping
density. We calculate the electron population of the different nanowire layers
as a function of the doping density and of several geometrical parameters by
means of a self-consistent Schr\"odinger-Poisson approach: Free carriers tend
to localize in the outer shell and screen the core from the electric field of
the dopants.


title:
Large difference between the magnetic properties of Ba and Ti co-doped
  BiFeO$_3$ bulk materials and their corresponding nanoparticles prepared by
  ultrasonication

abstract:
  The ceramic pellets of the nominal compositions
Bi$_{0.7}$Ba$_{0.3}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.20) were prepared
initially by standard solid state reaction technique. The pellets were then
ground into micrometer-sized powders and mixed with isopropanol in an
ultrasonic bath to prepare nanoparticles. The X-ray diffraction patterns
demonstrate the presence of a significant number of impurity phases in bulk
powder materials. Interestingly, these secondary phases were completely removed
due to the sonication of these bulk powder materials for 60 minutes. The field
and temperature dependent magnetization measurements exhibited significant
difference between the magnetic properties of the bulk materials and their
corresponding nanoparticles. We anticipate that the large difference in the
magnetic behavior may be associated with the presence and absence of secondary
impurity phases in the bulk materials and their corresponding nanoparticles,
respectively. The leakage current density of the bulk materials was also found
to suppress in the ultrasonically prepared nanoparticles compared to that of
bulk counterparts.


title: Quasi-efficient domination in grids

abstract:
  Domination of grids has been proved to be a demanding task and with the
addition of independence it becomes more challenging. It is known that no grid
with $m,n \geq 5$ has an efficient dominating set, also called perfect code,
that is, an independent vertex set such that each vertex not in it has exactly
one neighbor in that set. So it is interesting to study the existence of
independent dominating sets for grids that allow at most two neighbors, such
sets are called independent $[1,2]$-sets. In this paper we prove that every
grid has an independent $[1,2]$-set, and we develop a dynamic programming
algorithm using min-plus algebra that computes $i_{[1,2]}(P_m\Box P_n)$, the
minimum cardinality of an independent $[1,2]$-set for the grid graph
$P_m\square P_n$. We calculate $i_{[1,2]}(P_m\Box P_n)$ for $2\leq m\leq 13,
n\geq m$ using this algorithm, meanwhile the parameter for grids with $14\leq
m\leq n$ is obtained through a quasi-regular pattern that, in addition,
provides an independent $[1,2]$-set of minimum size.


title: Spin evolution of cold atomic gases in SU(2)$\otimes $U(1) fields

abstract:
  We consider response function and spin evolution in spin-orbit coupled cold
atomic gases in a synthetic gauge magnetic field influencing solely the orbital
motion of atoms. We demonstrate that various regimes of spin-orbit coupling
strength, magnetic field, and disorder can be treated within a single approach
based on the representation of atomic motion in terms of auxiliary collective
classical trajectories. Our approach allows for a unified description of
fermionic and bosonic gases.


title: 2D ion crystals in radiofrequency traps for quantum simulation

abstract:
  The computational difficulty of solving fully quantum many-body spin problems
is a significant obstacle to understanding the behavior of strongly correlated
quantum matter. Experimental ion-trap quantum simulation is a promising
approach for studying these lattice spin models, but has so far been limited to
one-dimensional systems. This work argues that such quantum simulation
techniques are extendable to a 2D ion crystal confined in a radiofrequency (rf)
trap. Using appropriately chosen parameters, driven ion motion due to the rf
fields can be made small and will not limit the types of quantum spin models
that can be experimentally encoded. The rf-driven motion is calculated to
modestly reduce the stability region of a 2D crystal and must be considered
when designing the 2D trap. The system will be scalable to 100+ quantum
particles, far beyond the realm of classical intractability, while maintaining
the traditional ion-trap strengths of individual-ion control, long quantum
coherence times, and site-resolved projective spin measurements.


title: A Probabilistic Adaptive Search System for Exploring the Face Space

abstract:
  Face recall is a basic human cognitive process performed routinely, e.g.,
when meeting someone and determining if we have met that person before.
Assisting a subject during face recall by suggesting candidate faces can be
challenging. One of the reasons is that the search space - the face space - is
quite large and lacks structure. A commercial application of face recall is
facial composite systems - such as Identikit, PhotoFIT, and CD-FIT - where a
witness searches for an image of a face that resembles his memory of a
particular offender. The inherent uncertainty and cost in the evaluation of the
objective function, the large size and lack of structure of the search space,
and the unavailability of the gradient concept makes this problem inappropriate
for traditional optimization methods. In this paper we propose a novel
evolutionary approach for searching the face space that can be used as a facial
composite system. The approach is inspired by methods of Bayesian optimization
and differs from other applications in the use of the skew-normal distribution
as its acquisition function. This choice of acquisition function provides
greater granularity, with regularized, conservative, and realistic results.


title:
High Baryon Densities in Heavy Ion Collisions at Energies Attainable at
  the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider

abstract:
  In very high energy collisions nuclei are practically transparent to each
other but produce very hot, nearly baryon-free, matter in the so-called central
rapidity region. The energy in the central rapidity region comes from the
kinetic energy of the colliding nuclei. We calculate the energy and rapidity
loss of the nuclei using the color glass condensate model. This model also
predicts the excitation energy of the nuclear fragments. Using a space-time
picture of the collision we calculate the baryon and energy densities of the
receding baryonic fireballs. For central collisions of gold nuclei at the
highest energy attainable at the Relativistic Heavy Ion Collider, for example,
we find baryon densities more than ten times that of atomic nuclei over a large
volume.


title: Polarized 3 parton production in inclusive DIS at small x

abstract:
  Azimuthal angular correlations between produced hadrons/jets in high energy
collisions are a sensitive probe of the dynamics of QCD at small x. Here we
derive the triple differential cross section for inclusive production of 3
polarized partons in DIS at small x using the spinor helicity formalism. The
target proton or nucleus is described using the Color Glass Condensate (CGC)
formalism. The resulting expressions are used to study azimuthal angular
correlations between produced partons in order to probe the gluon structure of
the target hadron or nucleus. Our analytic expressions can also be used to
calculate the real part of the Next to Leading Order (NLO) corrections to
di-hadron production in DIS by integrating out one of the three final state
partons.


title:
Indication of band flattening at the Fermi level in a strongly
  correlated electron system

abstract:
  Using ultra-high quality SiGe/Si/SiGe quantum wells at millikelvin
temperatures, we experimentally compare the energy-averaged effective mass,
$m$, with that at the Fermi level, $m_F$, and verify that the behaviours of
these measured values are qualitatively different. With decreasing electron
density (or increasing interaction strength), the mass at the Fermi level
monotonically increases in the entire range of electron densities, while the
energy-averaged mass saturates at low densities. The qualitatively different
behaviour reveals a precursor to the interaction-induced single-particle
spectrum flattening at the Fermi level in this electron system.


title:
The local dayside reconnection rate for oblique interplanetary magnetic
  fields

abstract:
  We present an analysis of local properties of magnetic reconnection at the
dayside magnetopause for various interplanetary magnetic field (IMF)
orientations in global magnetospheric simulations. This has heretofore not been
practical because it is difficult to locate where reconnection occurs for
oblique IMF, but new techniques make this possible. The approach is to identify
magnetic separators, the curves separating four regions of differing magnetic
topology, which map the reconnection X-line. The electric field parallel to the
X-line is the local reconnection rate. We compare results to a simple model of
local two-dimensional asymmetric reconnection. To do so, we find the plasma
parameters that locally drive reconnection in the magnetosheath and
magnetosphere in planes perpendicular to the X-line at a large number of points
along the X-line. The global magnetohydrodynamic simulations are from the
three-dimensional Block-Adaptive, Tree Solarwind Roe-type Upwind Scheme
(BATS-R-US) code with a uniform resistivity, although the techniques described
here are extensible to any global magnetospheric simulation model. We find that
the predicted local reconnection rates scale well with the measured values for
all simulations, being nearly exact for due southward IMF. However, the
absolute predictions differ by an undetermined constant of proportionality,
whose magnitude increases as the IMF clock angle changes from southward to
northward. We also show similar scaling agreement in a simulation with oblique
southward IMF and a dipole tilt. The present results will be an important
component of a full understanding of the local and global properties of dayside
reconnection.


title: A Modest View of Bell's Theorem

abstract:
  In the 80 years since the seminal Einstein, Podolsky, and Rosen (EPR) paper,
physicists and philosophers have mused about the `spooky action at a distance'
aspect of quantum mechanics that so bothered Einstein. In his formal analysis
of EPR-type entangled quantum states, Bell (1964) concluded that any hidden
variable theory designed to reproduce the predictions of quantum mechanics must
necessarily be nonlocal and allow superluminal interactions. This doesn't
immediately imply that nonlocality is a characteristic feature of quantum
mechanics let alone a fundamental property of nature; however, many physicists
and philosophers of science do harbor this belief. Experts in the field often
use the term `nonlocality' to designate particular non-classical aspects of
quantum entanglement and do not confuse the term with superluminal
interactions. However, many physicists seem to take the term more literally. I
endeavor to disabuse the latter of this notion by emphasizing that the
correlations of Bell-type entanglement are a result of ordinary quantum
superposition with no need to introduce nonlocality. The conclusion of the EPR
paper wasn't that quantum mechanics is nonlocal but rather that it is an
incomplete description of reality. For different reasons, many physicists,
including me, agree with Einstein that quantum mechanics is necessarily an
incomplete description of reality.


title: Simultaneous observation of gravitational and electromagnetic waves

abstract:
  Assuming that the short gamma-ray burst detected by the Fermi Gamma-Ray Space
Telescope about 0.4 seconds after the gravitational waves observed by the LIGO
and VIRGO Collaborations originated from the same black hole merger event, we
perform a model-independent analysis of different quantum gravity scenarios
based on (modified) dispersion relations (typical of quantum gravity models)
for the graviton and the photon. We find that only scenarios where at least one
of the two particles is luminal (the other being sub- or super-luminal) are
allowed, while scenarios where none of the two particles is luminal are ruled
out. Moreover, the physical request of having acceptable values for the quantum
gravity scale imposes stringent bounds on the difference between the velocities
of electromagnetic and gravitational waves, much more stringent than any
previously known bound.


title: Automorphisms of Ideals of Polynomial Rings

abstract:
  Let $R$ be a commutative integral domain with unit, $f$ be a nonconstant
monic polynomial in $R[t]$, and $I_f \subset R[t]$ be the ideal generated by
$f$. In this paper we study the group of $R$-algebra automorphisms of the
$R$-algebra without unit $I_f$. We show that, if $f$ has only one root
(possibly with multiplicity), then $Aut (I_f) \cong R^\times$. We also show
that, under certain mild hypothesis, if $f$ has at least two different roots in
the algebraic closure of the quotient field of $R$, then $Aut(I_f)$ is a cyclic
group and its order can be completely determined by analyzing the roots of $f$.


title:
Hot planetary winds near a star: dynamics, wind-wind interactions, and
  observational signatures

abstract:
  Signatures of "evaporative" winds from exo-planets on short (hot) orbits
around their host star have been observed in a number of systems. In this paper
we present global AMR simulations that track the launching of the winds, their
expansion through the circumstellar environment, and their interaction with a
stellar wind. We focus on purely hydrodynamic flows including the anisotropy of
the wind launching and explore the orbital/fluid dynamics of the resulting
flows in detail. In particular we find that a combination of the tidal and
Coriolis forces strongly distorts the planetary "Parker" wind creating
"up-orbit" and "down-orbit" streams. We characterize the flows in terms of
their orbital elements which change depending on their launch position on the
planet. We find that the anisotropy in the atmospheric temperature leads to
significant backflow on to the planet. The planetary wind interacts strongly
with the stellar wind creating instabilities that cause eventual deposition of
planetary gas onto the star. We present synthetic observations of both transit
and absorption line-structure for our simulations. For our initial conditions,
we find that the orbiting wind material produces absorption signatures at
significant distances from the planet and substantial orbit to orbit
variability. Ly-{\alpha} absorption shows red and blueshifted features out to
70 km/s. Finally, using semi-analytic models we constrain the effect of
radiation pressure, given the approximation of uniform stellar absorption.


title:
Exact two-body quantum dynamics of an electron-hole pair in
  semiconductor coupled quantum wells: a time-dependent approach

abstract:
  We simulate the time-dependent coherent dynamics of a spatially indirect
exciton (an electron-hole pair with the two particles confined in different
layers) in a GaAs coupled quantum well system. We use a unitary wave-packet
propagation method taking into account in full the four degrees of freedom of
the two particles in a two-dimensional system, including both the long-range
Coulomb attraction and arbitrary two-dimensional electrostatic potentials
affecting the electron and/or the hole separately. The method has been
implemented for massively parallel architectures to cope with the huge
numerical problem, showing good scaling properties and allowing evolution for
tens of picoseconds. We have investigated both transient time phenomena and
asymptotic time transmission and reflection coefficients for potential profiles
consisting of i) extended barriers and wells and ii) a single-slit geometry. We
found clear signatures of the internal two-body dynamics, with transient
phenomena in the picosecond time-scale which might be revealed by optical
spectroscopy. Exact results have been compared with mean-field approaches
which, neglecting dynamical correlations by construction, turn out to be
inadequate to describe the electron-hole pair evolution in realistic
experimental conditions.


title:
Universality of smoothness of Density of States in arbitrary
  higher-dimensional disorder under non-local interactions I. From
  Vi\'ete--Euler identity to Anderson localization

abstract:
  It is shown that in a large class of disordered systems with non-degenerate
disorder, in presence of non-local interactions, the Integrated Density of
States (IDS) is at least H\"older continuous in one dimension and universally
infinitely differentiable in higher dimensions. This result applies also to the
IDS in any finite volume subject to the random potential induced by an ambient,
infinitely extended disordered media. Dimension one is critical: in the
Bernoulli case, within the class of exponential interactions, the IDS measure
undergoes continuity phase transitions, from absolutely continuous to singular
continuous behaviour (the singularity in the latter case was known before). The
continuity transitions do not occur for sub-exponential or slower decaying
interactions, nor for $d\ge 2$. Technically, the case of polynomial decay is
the simplest one.
  The proposed approach provides a complement to the classical Wegner estimate
which says, essentially, that the IDS in the short-range models is at least as
regular as the marginal distribution of the disorder. In the models with
non-local interaction the IDS is actually much more regular than the underlying
disorder, which can even be discrete, due to the smoothing effect of multiple
convolutions. In turn, smoothness of the IDS is responsable for a mechanism
complementing the usual Lifshitz tails phenomenon.
  It is also shown that the disorder can take various forms (e.g., substitution
or random displacements) and need not be stochastically stationary (as in
Delone--Anderson or trim\-med/crooked Hamiltonians, for example); this does not
affect the main phenomena observed already in the simplest setting.
  Long-range models have an amazingly large number of connections to several
classical problems of harmonic analysis, probability theory, dynamical systems
and number theory.


title:
Rydberg atom mediated non-destructive readout of collective rotational
  states in polar molecule arrays

abstract:
  We analyze in detail the possibility to use charge-dipole interaction between
a single polar molecule or a 1D molecular array and a single Rydberg atom to
read out rotational populations. The change in the Rydberg electron energy is
conditioned on the rotational state of the polar molecules, allowing for
realization of a CNOT quantum gate between the molecules and the atom.
Subsequent readout of the atomic fluorescence results in a non-destructive
measurement of the rotational state. We study the interaction between a 1D
array of polar molecules and an array or a cloud of atoms in a Rydberg
superatom (blockaded) state and calculate the resolved energy shifts of Rb(60s)
with KRb and RbYb molecules, with N=1, 3, 5 molecules. We show that collective
molecular rotational states can be read out using the conditioned Rydberg
energy shifts.


title: Global properties of proton-proton collisions at $\sqrt{s}$ = 100 TeV

abstract:
  The global properties of the final states produced in hadronic interactions
of protons at centre-of-mass energies of future hadron colliders (such as
FCC-hh at CERN, and SppC in China), are studied. The predictions of various
Monte Carlo (MC) event generators used in collider physics (PYTHIA 6, PYTHIA 8,
and PHOJET) and in ultrahigh-energy cosmic-rays studies (EPOS, and QGSJET) are
compared. Despite their different underlying modeling of hadronic interactions,
their predictions for proton-proton (p-p) collisions at $\sqrt{s}$ = 100 TeV
are quite similar. The average of all MC predictions (except PHOJET) for the
different observables are: (i) p-p inelastic cross sections $\sigma_{\rm inel}$
= 105 $\pm$ 2 mb; (ii) total charged multiplicity $\rm N_{_{\rm ch}}$ = 150
$\pm$ 20; (iii) charged particle pseudorapidity density at midrapidity $\rm
dN_{ch}/d\eta|_{\eta=0} = 9.6 \pm 0.2$; (iv) energy density at midrapidity $\rm
dE/d\eta|_{\eta=0} = 13.6 \pm 1.5$ GeV, and $\rm dE/d\eta|_{\eta=5} = 670 \pm
70$ GeV at the edge of the central region; and (v) average transverse momenta
at midrapidities $\rm < p_{T}> = 0.76 \pm 0.07$ GeV/c. At midrapidity, EPOS and
QGSJET-II predict larger per-event multiplicity probabilities at very low ($\rm
N_{\rm ch}<3$) and very high ($\rm N_{\rm ch}>100$) particle multiplicities,
whereas PYTHIA 6 and 8 feature higher yields in the intermediate region $\rm
N_{\rm ch}\approx$ 30--80. These results provide useful information for the
estimation of the detector occupancies and energy deposits from pileup
collisions at the expected large FCC-hh/SppC luminosities.


title: Stark broadening of B IV spectral lines

abstract:
  Stark broadening parameters for 157 multiplets of helium like boron (B IV)
have been calculated using the impact semiclassical perturbation formalism.
Obtained results have been used to investigate the regularities within spectral
series. An example of the influence of Stark broadening on B IV lines in DO
white dwarfs is given.


title: Mac Williams identities and polarized Riemann-Roch conditions

abstract:
  The present note establishes the equivalence of Mac Williams identities for
an additive code C and its dual to Polarized Riemann-Roch Conditions on their
Zeta-functions. In such a way, the duality of additive codes appears to be a
polarized form of the Serre duality on a smooth irreducible projective curve.


title:
Lepton flavor violating processes in the minimal 3-3-1 model with
  singlet sterile neutrinos

abstract:
  We consider the minimal 3-3-1 model with three sterile neutrinos transforming
as singlet under the $SU(3)_L\otimes U(1)_X$ symmetry. This model, with or
without sterile neutrinos, predicts flavor violating interactions in both quark
and lepton sectors, since all the charged fermions mass matrices can not be
assumed diagonal in any case. Here we accommodate the lepton masses and the
Pontecorvo-Maki-Nakawaga-Sakata matrix at the same time, and as consequence the
Yukawa couplings and the unitary matrices which diagonalize the mass matrices
are not free parameters anymore. We study some phenomenological consequences,
i.e., $l_i\to l_jl_k \bar{l}_k$ and $l_i\to l_j\gamma$ which are induced by
neutral and doubly charged particles present in the model. In particular we
find that if the decay $\mu\to ee\bar{e}$ is observed in the future, the only
particle in the model that could explain this decay is the doubly charged
vector bilepton.


title: Debris disks and the search for life in the universe

abstract:
  Circumstellar debris disks are the extrasolar analogues of the asteroid belt
and the Kuiper belt. They consist of comets and leftover planetesimals that
continuously collide and produce circumstellar dust that can be observed as
infrared excess or in resolved imaging. As an obvious outcome of the planet
formation process, debris disks can help us constrain planet formation theories
and learn about the history of our own solar system. This thesis presents
observational studies of secondary gas in debris disks. It also discusses the
astrobiological potential of debris disks created during impact events onto
exoplanets.


title:
Calculation of differential cross section for dielectronic recombination
  with two-electron uranium

abstract:
  Calculation of the differential cross section for the dielectronic
recombination with two-electron uranium within the framework of QED is
presented. The polarization of the emitted photon is investigated. The
contributions of the Breit interaction and the interference of the photon
multipoles are studied.


title:
On the spectral Hausdorff dimension of 1D discrete Schr\"odinger
  operators under power decaying perturbations

abstract:
  We show that spectral Hausdorff dimensional properties of discrete
Schr\"oodinger operators with (1) Sturmian potentials of bounded density and
(2) a class of sparse potentials are preserved under suitable polynomial
decaying perturbations, when the spectrum of these perturbed operators have
some singular continuous component.


title:
Rational points and zero-cycles on rationally connected varieties over
  number fields

abstract:
  We report on progress in the qualitative study of rational points on
rationally connected varieties over number fields, also examining integral
points, zero-cycles, and non-rationally connected varieties. One of the main
objectives is to highlight and explain the many recent interactions with
analytic number theory.


title:
Numerical methods for interface coupling of compressible and almost
  incompressible media

abstract:
  Many experiments in biomedical applications and other disciplines use a shock
tube. These experiments often involve placing an experimental sample within a
fluid-filled container, which is then placed inside the shock tube. The shock
tube produces an initial shock that propagates through gas before hitting the
container with the sample. In order to gain insight into the shock dynamics
that is hard to obtain by experimental means, computational simulations of the
shock wave passing from gas into a thin elastic solid and into a nearly
incompressible fluid are developed. It is shown that if the solid interface is
very thin, it can be neglected, simplifying the model. The model uses Euler
equations for compressible fluids coupled with a Tammann equation of state
(EOS) to model both compressible gas and almost incompressible materials. A
three-dimensional (2D axisymmetric) model of these equations is solved using
high-resolution shock-capturing methods, with newly developed Riemann solvers
and limiters. The methods are extended to work on a mapped grid to allow more
complicated interface geometry, and they are adapted to work with adaptive mesh
refinement (AMR) for higher resolution and faster computations. The Clawpack
software is used to implement the method. These methods were initially inspired
by shock tube experiments to study the injury mechanisms of traumatic brain
injury (TBI).


title:
On maximal hypersurfaces in Lorentz manifolds admitting a parallel
  lightlike vector field

abstract:
  We study constant mean curvature spacelike hypersurfaces and in particular
maximal hypersurfaces immersed in pp-wave spacetimes satisfying the timelike
convergence condition. We prove the non-existence of compact spacelike
hypersurfaces whose constant mean curvature is non-zero and also that every
compact maximal hypersurface is totally geodesic. Moreover, we give an
extension of the classical Calabi-Bernstein theorem to this class of pp-wave
spacetimes.


title: The number of solutions for random regular NAE-SAT

abstract:
  Recent work has made substantial progress in understanding the transitions of
random constraint satisfaction problems. In particular, for several of these
models, the exact satisfiability threshold has been rigorously determined,
confirming predictions of statistical physics. Here we revisit one of these
models, random regular k-NAE-SAT: knowing the satisfiability threshold, it is
natural to study, in the satisfiable regime, the number of solutions in a
typical instance. We prove here that these solutions have a well-defined free
energy (limiting exponential growth rate), with explicit value matching the
one-step replica symmetry breaking prediction. The proof develops new
techniques for analyzing a certain "survey propagation model" associated to
this problem. We believe that these methods may be applicable in a wide class
of related problems.


title: Operads in It{\^o} calculus

abstract: We discuss algebraic and geometric properties of the It{\^o} calculus


title: The D3-probe-D7 brane holographic fractional topological insulator

abstract:
  The D3-probe-D7 brane system, oriented so as to have 2+1-dimensional Poincare
symmetry, is argued to be the holographic representation of a strongly
correlated fractional topological insulator which exhibits a zero-field
quantized Hall effect with half-units of Hall conductivity. The phase diagram
of the system with charge density and external magnetic field is found and, as
well as charge gapped quantum Hall states, it exhibits metallic and
semi-metallic phases with interesting behaviours. The relationship of this to
other models of fractional topological insulators is discussed.


title:
Generalized Fick Jacobs Approach for describing Adsorption Desorption
  Kinetics in Irregular Pores under Non Equilibrium Conditions

abstract:
  We present a study exploring the range of applicability of a generalized Fick
Jacobs equation in the case when diffusive mass transport of a fluid along a
pore includes chemical reactions in the bulk and pore surface. The study
contemplates nonequilibrium boundary conditions and makes emphasis on the
comparison between the predictions coming from the projected Fick Jacobs
description and the corresponding predictions of the original two dimensional
mass balance equation, establishing a simple cuantitative criterion of validity
of the projected description. For the adsorption desorption process, we
demonstrate that the length and the local curvature of the pore are the
relevant geometric quantities for its description, allowing for giving very
precise predictions of the mass concentration along the pore. Some schematic
cases involving adsorption and chemical reaction are used to quantify with
detail the concentration profiles in transient and stationary states involving
equilibrium and nonequilibrium situations. Our approach provides novel and
important insights in the study of diffusion and adsorption in confined
geometries.


title: Highlights from BNL and RHIC 2015

abstract:
  Highlights of news from Brookhaven National Laboratory (BNL) and results from
the Relativistic Heavy Ion Collider (RHIC) in the period July 2014-June 2015
are presented. The news this year was mostly very positive. The major event at
BNL was the startup and dedication of the new NSLS II, "the World's brightest
Synchrotron Light Source". The operation of RHIC was outstanding with a
polarized p+p run at $\sqrt{s}=200$ GeV with integrated luminosity that
exceeded the sum of all previous p+p integrated luminosity at this $\sqrt{s}$.
For the first time at RHIC asymmetric p+Au and p+Al runs were made but the p+Al
run caused damage in the PHENIX forward detectors from quenches that were
inadequately shielded for this first p+A run. This was also the 10th
anniversary of the 2005 announcement of the Perfect Liquid Quark Gluon Plasma
at RHIC and a review is presented of the discoveries leading to this claim. A
new result on net-charge fluctuations (with no particle identification) from
PHENIX based on previous scans over beam energy to look for a QCD critical
point is discussed which combined with Lattice QCD calculations and smaller
errors on the higher cumulants than previous measurements led to calculations
of the baryon chemical potential and freezeout temperature in agreement with
the best accepted analysis from baryon/anti-baryon ratio measurements.


title: Burgess-like subconvexity for $\mathrm{GL}_1$

abstract:
  We generalize our previous method on subconvexity problem for $\mathrm{GL}_2
\times \mathrm{GL}_1$ with cuspidal representations to Eisenstein series, and
deduce a Burgess-like subconvex bound for Hecke characters, i.e., the bound
$|L(1/2,\chi)| \ll_{\mathbf{F},\epsilon}
\mathbf{C}(\chi)^{1/4-(1-2\theta)/16+\epsilon}$ for varying Hecke characters
$\chi$ over a number field $\mathbf{F}$ with analytic conductor
$\mathbf{C}(\chi)$. As a main tool, we apply the extended theory of regularized
integral due to Zagier developed in a previous paper to obtain the relevant
triple product formulas of Eisenstein series.


title:
Handover Management in Dense Cellular Networks: A Stochastic Geometry
  Approach

abstract:
  Cellular operators are continuously densifying their networks to cope with
the ever-increasing capacity demand. Furthermore, an extreme densification
phase for cellular networks is foreseen to fulfill the ambitious fifth
generation (5G) performance requirements. Network densification improves
spectrum utilization and network capacity by shrinking base stations' (BSs)
footprints and reusing the same spectrum more frequently over the spatial
domain. However, network densification also increases the handover (HO) rate,
which may diminish the capacity gains for mobile users due to HO delays. In
highly dense 5G cellular networks, HO delays may neutralize or even negate the
gains offered by network densification. In this paper, we present an analytical
paradigm, based on stochastic geometry, to quantify the effect of HO delay on
the average user rate in cellular networks. To this end, we propose a flexible
handover scheme to reduce HO delay in case of highly dense cellular networks.
This scheme allows skipping the HO procedure with some BSs along users'
trajectories. The performance evaluation and testing of this scheme for only
single HO skipping shows considerable gains in many practical scenarios.


title:
KADABRA is an ADaptive Algorithm for Betweenness via Random
  Approximation

abstract:
  We present KADABRA, a new algorithm to approximate betweenness centrality in
directed and undirected graphs, which significantly outperforms all previous
approaches on real-world complex networks. The efficiency of the new algorithm
relies on two new theoretical contributions, of independent interest. The first
contribution focuses on sampling shortest paths, a subroutine used by most
algorithms that approximate betweenness centrality. We show that, on realistic
random graph models, we can perform this task in time $|E|^{\frac{1}{2}+o(1)}$
with high probability, obtaining a significant speedup with respect to the
$\Theta(|E|)$ worst-case performance. We experimentally show that this new
technique achieves similar speedups on real-world complex networks, as well.
The second contribution is a new rigorous application of the adaptive sampling
technique. This approach decreases the total number of shortest paths that need
to be sampled to compute all betweenness centralities with a given absolute
error, and it also handles more general problems, such as computing the $k$
most central nodes. Furthermore, our analysis is general, and it might be
extended to other settings.


title:
Temperature Dependence of Viscosity in Normal Fluid $^3$He Below 800mK
  Determined by a Micro-electro-mechanical Oscillator

abstract:
  A micro-electro-mechanical system vibrating in its shear mode was used to
study the viscosity of normal liquid $^3$He from 20mK to 770mK at 3bar, 21bar,
and 29bar. The damping coefficient of the oscillator was determined by
frequency sweeps through its resonance at each temperature. Using a slide film
damping model, the viscosity of the fluid was obtained. Our viscosity values
are compared with previous measurements and with calculated values from Fermi
liquid theory. The crossover from the classical to the Fermi liquid regime is
manifest in the temperature dependence of viscosity. In the Fermi liquid
regime, the temperature dependence of viscosity changes from $T^{-1}$ to
$T^{-2}$ on cooling, indicating a transition from the Stokes flow to the
Couette flow regime.


title:
Spatially resolved integral field spectroscopy of the ionized gas in
  IZw18

abstract:
  We present a detailed 2D study of the ionized ISM of IZw18 using new PMAS-IFU
optical observations. IZw18 is a high-ionization galaxy which is among the most
metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark
for understanding the properties most closely resembling those prevailing at
distant starbursts. Our IFU-aperture (~ 1.4 kpc x 1.4 kpc) samples the entire
IZw18 main body and an extended region of its ionized gas. Maps of relevant
emission lines and emission line ratios show that higher-excitation gas is
preferentially located close to the NW knot and thereabouts. We detect a
Wolf-Rayet feature near the NW knot. We derive spatially resolved and
integrated physical-chemical properties for the ionized gas in IZw18. We find
no dependence between the metallicity-indicator R23 and the ionization
parameter (as traced by [OIII]/[OII]) across IZw18. Over ~ 0.30 kpc^2, using
the [OIII]4363 line, we compute Te[OIII] values (~ 15000 - 25000 K), and oxygen
abundances are derived from the direct determinations of Te[OIII]. More than
70% of the higher-Te[OIII] (> 22000 K) spaxels are HeII4686-emitting spaxels
too. From a statistical analysis, we study the presence of variations in the
ISM physical-chemical properties. A galaxy-wide homogeneity, across hundreds of
parsecs, is seen in O/H. Based on spaxel-by-spaxel measurements, the
error-weighted mean of 12 + log(O/H) = 7.11 +/- 0.01 is taken as the
representative O/H for IZw18. Aperture effects on the derivation of O/H are
discussed. Using our IFU data we obtain, for the first time, the IZw18
integrated spectrum.


title:
Brauer-Severi motives and Donaldson-Thomas invariants of quantized
  3-folds

abstract:
  Motives of Brauer-Severi schemes of Cayley-smooth algebras associated to
homogeneous superpotentials are used to compute inductively the motivic
Donaldson-Thomas invariants of the corresponding Jacobian algebras. This
approach can be used to test the conjectural exponential expressions for these
invariants, proposed in arXiv:1510.08116. As an example we confirm the second
term of the conjectured expression for the motivic series of the homogenised
Weyl algebra.


title: Potential Jupiter-Family Comet Contamination of the Main Asteroid Belt

abstract:
  We present the results of "snapshot" numerical integrations of test particles
representing comet-like and asteroid-like objects in the inner solar system
aimed at investigating the short-term dynamical evolution of objects close to
the dynamical boundary between asteroids and comets as defined by the Tisserand
parameter with respect to Jupiter, T_J (i.e., T_J=3). As expected, we find that
T_J for individual test particles is not always a reliable indicator of initial
orbit types. Furthermore, we find that a few percent of test particles with
comet-like starting elements (i.e., similar to Jupiter-family comets) reach
main-belt-like orbits (at least temporarily) during our 2 Myr integrations,
even without the inclusion of non-gravitational forces, apparently via a
combination of gravitational interactions with the terrestrial planets and
temporary trapping by mean-motion resonances with Jupiter. We estimate that the
fraction of real Jupiter-family comets occasionally reaching main-belt-like
orbits on Myr timescales could be on the order of ~0.1-1%, although the
fraction that remain on such orbits for appreciable lengths of time is
certainly far lower. Thus, the number of JFC-like interlopers in the main-belt
population at any given time is likely to be small, but still non-zero, a
finding with significant implications for efforts to use main-belt comets to
trace the primordial distribution of volatile material in the inner solar
system. The test particles with comet-like starting orbital elements that
transition onto main-belt-like orbits in our integrations appear to be largely
prevented from reaching low eccentricity, low inclination orbits. We therefore
find that low-eccentricity, low-inclination main-belt comets may provide a more
reliable means for tracing the primordial ice content of the main asteroid belt
than the main-belt comet population as a whole.


title: Polynomial-time kernel reductions

abstract:
  In the framework of computational complexity and in an effort to define a
more natural reduction for problems of equivalence, we investigate the recently
introduced kernel reduction, a reduction that operates on each element of a
pair independently. This paper details the limitations and uses of kernel
reductions. We show that kernel reductions are weaker than many-one reductions
and provide conditions under which complete problems exist. Ultimately, the
number and size of equivalence classes can dictate the existence of a kernel
reduction. We leave unsolved the unconditional existence of a complete problem
under polynomial-time kernel reductions for the standard complexity classes.


title: On the (in)validity of the NLS-KdV system in the study of water waves

abstract:
  It is universally accepted that the cubic, nonlinear Schrodinger equation
(NLS) models the dynamics of narrow-bandwidth wave packets consisting of short
dispersive waves, while the Kortewegde Vries equation (KdV) models the
propagation of long waves in dispersive media. A system that couples the two
equations seems attractive to model the interaction of long and short waves and
such a system has been studied over the last few decades. However, questions
about the validity of the system in the study of water waves were raised in our
previous work where we presented our analysis using the fifth-order KdV as the
starting point. In this paper, these questions are settled unequivocally as we
show that the NLS-KdV system or even the linear Schrodinger-KdV system cannot
be resulted from the full Euler equations formulated in the study of water
waves.


title: An upper boundary in the mass-metallicity plane of exo-Neptunes

abstract:
  With the progress of detection techniques, the number of low-mass and
small-size exoplanets is increasing rapidly. However their characteristics and
formation mechanisms are not yet fully understood. The metallicity of the host
star is a critical parameter in such processes and can impact the occurence
rate or physical properties of these planets. While a frequency-metallicity
correlation has been found for giant planets, this is still an ongoing debate
for their smaller counterparts. Using the published parameters of a sample of
157 exoplanets lighter than 40 Mearth, we explore the mass-metallicity space of
Neptunes and Super-Earths. We show the existence of a maximal mass that
increases with metallicity, that also depends on the period of these planets.
This seems to favor in situ formation or alternatively a metallicity-driven
migration mechanism. It also suggests that the frequency of Neptunes (between
10 and 40 Mearth) is, like giant planets, correlated with the host star
metallicity, whereas no correlation is found for Super-Earths (<10 Mearth).


title:
Comparing Fifty Natural Languages and Twelve Genetic Languages Using
  Word Embedding Language Divergence (WELD) as a Quantitative Measure of
  Language Distance

abstract:
  We introduce a new measure of distance between languages based on word
embedding, called word embedding language divergence (WELD). WELD is defined as
divergence between unified similarity distribution of words between languages.
Using such a measure, we perform language comparison for fifty natural
languages and twelve genetic languages. Our natural language dataset is a
collection of sentence-aligned parallel corpora from bible translations for
fifty languages spanning a variety of language families. Although we use
parallel corpora, which guarantees having the same content in all languages,
interestingly in many cases languages within the same family cluster together.
In addition to natural languages, we perform language comparison for the coding
regions in the genomes of 12 different organisms (4 plants, 6 animals, and two
human subjects). Our result confirms a significant high-level difference in the
genetic language model of humans/animals versus plants. The proposed method is
a step toward defining a quantitative measure of similarity between languages,
with applications in languages classification, genre identification, dialect
identification, and evaluation of translations.


title:
Unprecedented Fine Structure of a Solar Flare Revealed by the 1.6~m New
  Solar Telescope

abstract:
  Solar flares signify the sudden release of magnetic energy and are sources of
so called space weather. The fine structures (below 500 km) of flares are
rarely observed and are accessible to only a few instruments world-wide. Here
we present observation of a solar flare using exceptionally high resolution
images from the 1.6~m New Solar Telescope (NST) equipped with high order
adaptive optics at Big Bear Solar Observatory (BBSO). The observation reveals
the process of the flare in unprecedented detail, including the flare ribbon
propagating across the sunspots, coronal rain (made of condensing plasma)
streaming down along the post-flare loops, and the chromosphere's response to
the impact of coronal rain, showing fine-scale brightenings at the footpoints
of the falling plasma. Taking advantage of the resolving power of the NST, we
measure the cross-sectional widths of flare ribbons, post-flare loops and
footpoint brighenings, which generally lie in the range of 80-200 km, well
below the resolution of most current instruments used for flare studies.
Confining the scale of such fine structure provides an essential piece of
information in modeling the energy transport mechanism of flares, which is an
important issue in solar and plasma physics.