title:
Interacting fermions in rotation: chiral symmetry restoration, moment of
  inertia and thermodynamics

abstract:
  We study rotating fermionic matter at finite temperature in the framework of
the Nambu-Jona-Lasinio model. In order to respect causality the rigidly
rotating system must be bound by a cylindrical boundary with appropriate
boundary conditions that confine the fermions inside the cylinder. We show the
finite geometry with the MIT boundary conditions affects strongly the phase
structure of the model leading to three distinct regions characterized by
explicitly broken (gapped), partially restored (nearly gapless) and
spontaneously broken (gapped) phases at, respectively, small, moderate and
large radius of the cylinder. The presence of the boundary leads to specific
steplike irregularities of the chiral condensate as functions of coupling
constant, temperature and angular frequency. These steplike features have the
same nature as the Shubnikov-de Haas oscillations with the crucial difference
that they occur in the absence of both external magnetic field and Fermi
surface. At finite temperature the rotation leads to restoration of
spontaneously broken chiral symmetry while the vacuum at zero temperature is
insensitive to rotation ("cold vacuum cannot rotate"). As the temperature
increases the critical angular frequency decreases and the transition becomes
softer. A phase diagram in angular frequency-temperature plane is presented. We
also show that at fixed temperature the fermion matter in the chirally restored
(gapless) phase has a higher moment of inertia compared to the one in the
chirally broken (gapped) phase.

categories: hep-th cond-mat.other cond-mat.quant-gas hep-ph


title:
Kondo screening and beyond: an x-ray absorption and dichroism study of
  CePt$_5$/Pt(111)

abstract:
  We use x-ray absorption spectroscopy as well as its linear and circular
magnetic dichroisms to characterize relevant interactions and energy scales in
the surface intermetallic CePt$_5$/Pt(111). The experiments provide insight
into crystal field splitting, effective paramagnetic moments, their Kondo
screening and mutual interactions and thus into many aspects which typically
determine the low temperature behavior of correlated rare earth compounds.
Exploiting the tuneability of Ce valence through the thickness dependent
epitaxial strain at the CePt$_5$/Pt(111) interface, we are able to
systematically investigate the impact of hybridization strength on these
interactions. Considerable Kondo screening is indeed observed at all CePt$_5$
thicknesses, and found to be strongest in case of strongest hybridization.
While the magnetic response is commensurate with an impurity Kondo scale of
$T_K \gtrsim 10^2$ K for specimen temperatures $T \gtrsim 30$ K, this is no
longer the case at lower temperature. Its detailed study by XMCD at one
specific thickness of CePt$_5$ reveals an anomaly of the susceptibility at $T^*
\approx 25$ K instead, which we tentatively associate with the onset of lattice
coherence. At lowest temperature we observe paramagnetic saturation with a
small Ce $4f$ saturation magnetization. Within the framework of itinerant $4f$
electrons, saturation is due to a field induced Lifshitz transition involving a
very heavy band with correspondingly small degeneracy temperature of $T_F
\approx 7$ K. This small energy scale results in the persistence of Curie-Weiss
behavior across the entire range of experimentally accessible temperatures ($T
\gtrsim 2$ K). Our work highlights the potential of magnetic circular dichroism
studies in particular for Kondo and heavy fermion materials, which so far has
remained largely unexplored.


title: Recent Cross Section Work From NOvA

abstract:
  The NOvA experiment is an off-axis long-baseline neutrino oscillation
experiment seeking to measure $\nu_{\mu}$ disappearance and $\nu_{e}$
appearance in a $\nu_{\mu}$ beam originating at Fermilab. In addition to
measuring the unoscillated neutrino spectra for the purposes of predicting the
oscillated neutrino spectrum in the far detector, the 293-ton near detector
also enables high-statistics investigation into neutrino scattering in numerous
reaction channels. We discuss the various near detector analyses currently in
progress, including inclusive measurements of both electron and muon neutrino
charged-current interactions and efforts to constrain the off-axis NuMI flux
using the elastic scattering of neutrinos from atomic electrons.


title: Waldspurger formula over function fields

abstract:
  In this paper, we derive a function field version of the Waldspurger formula
for the central critical values of the Rankin-Selberg L-functions. This formula
states that the central critical L-values in question can be expressed as the
"ratio" of the global toric period integral to the product of the local toric
period integrals. Consequently, this result provides a necessary and sufficient
criterion for the non-vanishing of these central critical L-values, and
supports the Gross-Prasad conjecture for $SO(3)$ over function fields.


title:
Low-energy spin excitations in Li(0.8)Fe(0.2)ODFeSe superconductor
  studied with inelastic neutron scattering

abstract:
  We report an inelastic neutron scattering study of single crystals of
(Li$_{0.8}$Fe$_{0.2}$)ODFeSe. Temperature-dependent low-energy spin excitations
are observed near $\mathbf{Q}=$ (0.5, 0.27, 0.5) and equivalent wave vectors
symmetrically surrounding $\mathbf{Q}=$ (0.5, 0.5, 0.5) in the 1-Fe Brillouin
zone, consistent with a Fermi-surface-nesting description. The excitations are
broadly distributed in energy, ranging from 16 to 35 meV. Upon cooling below
the superconducting critical temperature ($T_\mathrm{c}$), magnetic response
below twice the superconducting gap $2\Delta_\mathrm{SC}$ exhibits an abrupt
enhancement, consistent with the notion of spin resonance, whereas the response
at higher energies increases more gradually with only a weak anomaly at
$T_\mathrm{c}$. Our results suggest that (Li$_{0.8}$Fe$_{0.2}$)ODFeSe might be
on the verge of a crossover between different Cooper-pairing channels with
distinct symmetries.


title: Path-complete positivity of switching systems

abstract:
  The notion of path-complete positivity is introduced as a way to generalize
the property of positivity from one LTI system to a family of switched LTI
systems whose switching rule is constrained by a finite automaton. The
generalization builds upon the analogy between stability and positivity, the
former referring to the contraction of a norm, the latter referring to the
contraction of a cone (or, equivalently, a projective norm). We motivate and
investigate the potential of path-positivity and we propose an algorithm for
the automatic verification of positivity.


title:
How primordial is the structure of comet 67P/C-G? Combined collisional
  and dynamical models suggest a late formation

abstract:
  There is an active debate about whether the properties of comets as observed
today are primordial or, alternatively, if they are a result of collisional
evolution or other processes. We investigate the effects of collisions on a
comet with a structure like 67P/C-G. We develop scaling laws for the critical
specific impact energies required for a significant shape alteration. These are
then used in simulations of the combined dynamical and collisional evolution of
comets in order to study the survival probability of a primordially formed
object with a shape like 67P/C-G. The effects of impacts on comet 67P/C-G are
studied using a SPH shock physics code. The resulting critical specific impact
energy defines a minimal projectile size which is used to compute the number of
shape-changing collisions in a set of dynamical simulations. These simulations
follow the dispersion of the trans-Neptunian disk during the giant planet
instability, the formation of a scattered disk, and produce 87 objects that
penetrate into the inner solar system with orbits consistent with the observed
JFC population. The collisional evolution before the giant planet instability
is not considered here. Hence, our study is conservative in its estimation of
the number of collisions. We find that in any scenario considered here, comet
67P/C-G would have experienced a significant number of shape-changing
collisions, if it formed primordially. This is also the case for generic
bi-lobe shapes. Our study also shows that impact heating is very localized and
that collisionally processed bodies can still have a high porosity. Our study
indicates that the observed bi-lobe structure of comet 67P/C-G may not be
primordial, but might have originated in a rather recent event, possibly within
the last 1 Gy. This may be the case for any kilometer-sized two-component
cometary nuclei.


title: Curvature estimates for stable free boundary minimal hypersurfaces

abstract:
  In this paper, we prove uniform curvature estimates for immersed stable free
boundary minimal hypersurfaces which satisfy a uniform area bound. Our result
is a natural generalization of the celebrated Schoen-Simon-Yau interior
curvature estimates up to the free boundary. A direct corollary of our
curvature estimates is a smooth compactness theorem which is an essential
ingredient in the min-max theory of free boundary minimal hypersurfaces
developed by the last two authors. We also prove a monotonicity formula for
free boundary minimal submanifolds in Riemannian manifolds for any dimension
and codimension. For the case of $3$-manifolds with boundary, we prove a
stronger curvature estimate for properly embedded stable free boundary minimal
surfaces without any assumption on the area bound. This generalizes Schoen's
interior curvature estimates to the free boundary setting. Our proof uses the
theory of minimal laminations developed by Colding and Minicozzi.


title:
Spaser and optical amplification conditions in gold-coated active
  nanoparticles

abstract:
  Due to their many potential applications, there is an increasing interest in
studying hybrid systems composed of optically active media and plasmonic
metamaterials. In this work we focus on a particular system which consists of
an optically active silica core covered by a gold shell. We find that the
spaser (surface plasmon amplification by stimulated emission of radiation)
conditions can be found at the poles of the scattering cross section of the
system, a result that remains valid beyond the geometry studied. We explored a
wide range of parameters that cover most of the usual experimental conditions
in terms of the geometry of the system and the wavelength of excitation. We
show that the conditions of spaser generation necessarily require full loss
compensation, but the opposite is not necessarily true. Our results, which are
independent of the detailed response of the active medium, provide the gain
needed and the wavelength of the spasers that can be produced by a particular
geometry, discussing also the possibility of turning the system into optical
amplifiers and SERS (surface enhanced Raman spectroscopy) substrates with huge
enhancements. We believe that our results can find numerous applications. In
particular, they can be useful for experimentalists studying similar systems in
both, tuning the experimental conditions and interpreting the results.


title: The falsification of Chiral Nuclear Forces

abstract:
  Predictive power in theoretical nuclear physics has been a major concern in
the study of nuclear structure and reactions. The Effective Field Theory (EFT)
based on chiral expansions provides a model independent hierarchy for many body
forces at long distances but their predictive power may be undermined by the
regularization scheme de- pendence induced by the counterterms and encoding the
short distances dynamics which seem to dominate the uncertainties. We analyze
several examples including zero energy NN scattering or perturbative
counterterm-free peripheral scattering where one would ex- pect these methods
to work best and unveil relevant systematic discrepancies when a fair
comparison to the Granada-2013 NN-database and partial wave analysis is
undertaken.


title: Heavy traffic analysis of roving server networks

abstract:
  This paper studies the heavy-traffic (HT) behaviour of queueing networks with
a single roving server. External customers arrive at the queues according to
independent renewal processes and after completing service, a customer either
leaves the system or is routed to another queue. This type of customer routing
in queueing networks arises very naturally in many application areas (in
production systems, computer- and communication networks, maintenance, etc.).
In these networks, the single most important characteristic of the system
performance is oftentimes the path time, i.e. the total time spent in the
system by an arbitrary customer traversing a specific path. The current paper
presents the first HT asymptotic for the path-time distribution in queueing
networks with a roving server under general renewal arrivals. In particular, we
provide a strong conjecture for the system's behaviour under HT extending the
conjecture of Coffman et al. [E.G. Coffman Jr., A.A. Puhalskii, M.I. Reiman
1995 and 1998] to the roving server setting of the current paper. By combining
this result with novel light-traffic asymptotics we derive an approximation of
the mean path-time for arbitrary values of the load and renewal arrivals. This
approximation is not only highly accurate for a wide range of parameter
settings, but is also exact in various limiting cases.


title: A Continuous Threshold Expectile Model

abstract:
  Expectile regression is a useful tool for exploring the relation between the
response and the explanatory variables beyond the conditional mean. This
article develops a continuous threshold expectile regression for modeling data
in which the effect of a covariate on the response variable is linear but
varies below and above an unknown threshold in a continuous way. Based on a
grid search approach, we obtain estimators for the threshold and the regression
coefficients via an asymmetric least squares regression method. We derive the
asymptotic properties for all the estimators and show that the estimator for
the threshold achieves root-n consistency. We also develop a weighted CUSUM
type test statistic for the existence of a threshold in a given expectile, and
derive its asymptotic properties under both the null and the local alternative
models. This test only requires fitting the model under the null hypothesis in
the absence of a threshold, thus it is computationally more efficient than the
likelihood-ratio type tests. Simulation studies show desirable finite sample
performance in both homoscedastic and heteroscedastic cases. The application of
our methods on a Dutch growth data and a baseball pitcher salary data reveals
interesting insights.


title:
Causal optimal transport and its links to enlargement of filtrations and
  continuous-time stochastic optimization

abstract:
  The martingale part in the semimartingale decomposition of a Brownian motion
with respect to an enlargement of its filtration, is an anticipative mapping of
the given Brownian motion. In analogy to optimal transport theory, we define
causal transport plans in the context of enlargement of filtrations, as the
Kantorovich counterparts of the aforementioned non-adapted mappings. We provide
a necessary and sufficient condition for a Brownian motion to remain a
semimartingale in an enlarged filtration, in terms of certain minimization
problems over sets of causal transport plans. The latter are also used in order
to give robust transport-based estimates for the value of having additional
information, as well as model sensitivity with respect to the reference
measure, for the classical stochastic optimization problems of utility
maximization and optimal stopping. Our results have natural extensions to the
case of general multidimensional continuous semimartingales.


title: A causal viscous cosmology without singularities

abstract:
  An isotropic and homogeneous cosmological model with a source of dark energy
is studied. That source is simulated with a viscous relativistic fluid with
minimal causal correction. In this model the restrictions on the parameters
coming from the following conditions are analized: a) energy density without
singularities along time, b) scale factor increasing with time, c) universe
accelerated at present time, d) state equation for dark energy with "w" bounded
and close to -1. It is found that those conditions are satified for the
following two cases. i) When the transport coefficient ({\tau}_{{\Pi}}),
associated to the causal correction, is negative, with the aditional
restriction {\zeta}|{\tau}_{{\Pi}}|>2/3, where {\zeta} is the relativistic bulk
viscosity coefficient. The state equation is in the "phantom" energy sector.
ii) For {\tau}_{{\Pi}} positive, in the "k-essence" sector. It is performed an
exact calculation for the case where the equation of state is constant, finding
that option (ii) is favored in relation to (i), because in (ii) the entropy is
always increasing, while this does no happen in (i).


title:
Min-max theory for free boundary minimal hypersurfaces I - regularity
  theory

abstract:
  In 1960s, Almgren initiated a program to find minimal hypersurfaces in
compact manifolds using min-max method. This program was largely advanced by
Pitts and Schoen-Simon in 1980s when the manifold has no boundary. In this
paper, we finish this program for general compact manifold with nonempty
boundary. As a result, we prove the existence of a smooth embedded minimal
hypersurface with free boundary in any compact smooth Euclidean domain. An
application of our general existence result combined with the work of Marques
and Neves shows that for any compact Riemannian manifolds with nonnegative
Ricci curvature and convex boundary, there exist infinitely many embedded
minimal hypersurfaces with free boundary which are properly embedded.


title:
Non-zero helicity extinction in light scattered from achiral (or chiral)
  small particles located at points of null incident helicity density

abstract:
  Based on a recent unified formulation on dichorism and extinction of helicity
on scattering by a small particle, dipolar in the wide sense, magnetodielectric
or not, chiral or achiral, we show that such extinction is enhanced not only at
resonances of the polarizabilities, but also due to interference between left
and right circularly polarized components of the incident wave, which
contributes with appropriate parameters of the illuminating field, even if the
particle is achiral and is placed at points of the incident field at which the
local incident helicity density is zero.
  This phenomenon goes beyond standard circular dichroism (CD), and we analyze
it in detail on account of the values of the several quantities, both of the
incident light and the particle, involved in the process. In addition, this
interference produces a term in the helicity extinction that remarkably yields
information on the real parts of the electric and/or magnetic polarizabilities,
which are not provided by CD, of which that helicity extinction phenomenon may
be considered a generalization.


title:
Analysis of Static Cellular Cooperation between Mutually Nearest
  Neighboring Nodes

abstract:
  Cooperation in cellular networks is a promising scheme to improve system
performance. Existing works consider that a user dynamically chooses the
stations that cooperate for his/her service, but such assumption often has
practical limitations. Instead, cooperation groups can be predefined and
static, with nodes linked by fixed infrastructure. To analyze such a potential
network, we propose a grouping method based on node proximity. With the
Mutually Nearest Neighbour Relation, we allow the formation of singles and
pairs of nodes. Given an initial topology for the stations, two new point
processes are defined, one for the singles and one for the pairs. We derive
structural characteristics for these processes and analyse the resulting
interference fields. When the node positions follow a Poisson Point Process
(PPP) the processes of singles and pairs are not Poisson. However, the
performance of the original model can be approximated by the superposition of
two PPPs. This allows the derivation of exact expressions for the coverage
probability. Numerical evaluation shows coverage gains from different signal
cooperation that can reach up to 15% compared to the standard noncooperative
coverage. The analysis is general and can be applied to any type of cooperation
in pairs of transmitting nodes.


title:
Formation of bi-lobed shapes by sub-catastrophic collisions: A late
  origin of comet 67P/C-G's structure

abstract:
  The origin of the particular shape of a small body like comet
67P/Churyumov-Gerasimenko (67P/C-G) is a topic of active research. How and when
it acquired its peculiar characteristics has distinct implications on the
origin of the solar system and its dynamics. We investigate how shapes like the
one of comet 67P/C-G can result from a new type of low-energy, sub-catastrophic
impacts involving elongated, rotating bodies. We focus on parameters
potentially leading to bi-lobed structures. We also estimate the probability
for such structures to survive subsequent impacts. We use a smooth particle
hydrodynamics (SPH) shock physics code to model the impacts, the subsequent
reaccumulation of material and the reconfiguration into a stable final shape.
The energy increase as well as the degree of compaction of the resulting bodies
are tracked in the simulations. Our modelling results suggest that the
formation of bi-lobed structures like 67P/C-G is a natural outcome of the low
energy, sub-catastrophic collisions considered here. Sub-catastrophic impacts
have the potential to alter the shape of a small body significantly, without
leading to major heating or compaction. The currently observed shapes of
cometary nuclei, such as 67P/C-G, maybe a result of such a last major shape
forming impact.


title:
A Lightweight, Non-intrusive Approach for Orchestrating
  Autonomously-managed Network Elements

abstract:
  Software-Defined Networking enables the centralized orchestration of data
traffic within a network. However, proposed solutions require a high degree of
architectural penetration. The present study targets the orchestration of
network elements that do not wish to yield much of their internal operations to
an external controller. Backpressure routing principles are used for deriving
flow routing rules that optimally stabilize a network, while maximizing its
throughput. The elements can then accept in full, partially or reject the
proposed routing rule-set. The proposed scheme requires minimal, relatively
infrequent interaction with a controller, limiting its imposed workload,
promoting scalability. The proposed scheme exhibits attracting network
performance gains, as demonstrated by extensive simulations and proven via
mathematical analysis.


title: Color-avoiding percolation

abstract:
  Many real world networks have groups of similar nodes which are vulnerable to
the same failure or adversary. Nodes can be colored in such a way that colors
encode the shared vulnerabilities. Using multiple paths to avoid these
vulnerabilities can greatly improve network robustness. Color-avoiding
percolation provides a theoretical framework for analyzing this scenario,
focusing on the maximal set of nodes which can be connected via multiple
color-avoiding paths. In this paper we extend the basic theory of
color-avoiding percolation that was published in [Krause et. al., Phys. Rev. X
6 (2016) 041022]. We explicitly account for the fact that the same particular
link can be part of different paths avoiding different colors. This fact was
previously accounted for with a heuristic approximation. We compare this
approximation with a new, more exact theory and show that the new theory is
substantially more accurate for many avoided colors. Further, we formulate our
new theory with differentiated node functions, as senders/receivers or as
transmitters. In both functions, nodes can be explicitly trusted or avoided.
With only one avoided color we obtain standard percolation. With one by one
avoiding additional colors, we can understand the critical behavior of color
avoiding percolation. For heterogeneous color frequencies, we find that the
colors with the largest frequencies control the critical threshold and
exponent. Colors of small frequencies have only a minor influence on color
avoiding connectivity, thus allowing for approximations.


title: A catalog of UGC isolated galaxy pairs with accurate radial velocities

abstract:
  The present paper is devoted to the construction of a catalog of isolated
galaxy pairs from the Uppsala Galaxy Catalog (UGC), using accurate radial
velocities. The UGC lists 12921 galaxies to declination larger than -2 deg 30
min and is complete to an apparent diameter of 1 arcmin. The criteria used to
define the isolated galaxy pairs are the following: 1) Velocity criterion:
radial velocity difference between the members lower than 500 km/s; 2)
Interdistance criterion: projected distance between the members smaller than 1
Mpc; 3) Reciprocity criterion: each member is the closest galaxy to the other
one, which excludes multiplets; 4) Isolation information: the catalog lists the
ratio between the projected distance to the closest UGC galaxy (having a
velocity difference smaller than 500 km/s) and the pair members interdistance,
thus allowing one to choose any isolation criterion (beyond the chosen limit
2.5). In addition, we have accounted for the small diameter bias by searching
for CGCG galaxies in the pair environment and used the same isolation
criterion. A peculiar investigation has allowed to gather very accurate radial
velocities for pair members, from high quality HI and optical measurements
(median uncertainty on velocity differences 10 km/s). Our final catalog
contains 1005 galaxy pairs. Then we give some global properties of the pair
catalog. We display the histograms of the radial velocity differences between
the pair members and of their projected interdistances (median 0.29 Mpc).
Finally, we provide an estimate of the contamination by cosmological false
"pairs", which is about 10 percent up to a velocity difference of 380 km/s,
beyond which all pairs are probably false.


title:
Protocol for a Systematic Mapping Study on Collaborative Model-Driven
  Software Engineering

abstract:
  Nowadays, collaborative modeling performed by multiple stakeholders is
gaining a growing interest in both academia and practice. However, it poses a
set of research challenges, such as large and complex models management,
support for multi-user modeling environments, and synchronization mechanisms
like models migration and merging, conflicts management, models versioning and
rollback support. A body of knowledge in the scientific literature about
collaborative model-driven software engineering (MDSE) exists. Still, those
studies are scattered across different independent research areas, such as
software engineering, model-driven engineering languages and systems, model
integrated computing, etc., and a study classifying and comparing the various
approaches and methods for collaborative MDSE is still missing. Under this
perspective, a systematic mapping study (SMS) can help researchers and
practitioners in (i) having a complete, comprehensive and valid picture of the
state of the art about collaborative MDSE, and (ii) identifying potential gaps
in current research and future research directions.


title:
Detecting topological exceptional points in a parity-time symmetric
  system with cold atoms

abstract:
  We reveal a novel topological property of the exceptional points in a
two-level parity-time symmetric system and then propose a scheme to detect the
topological exceptional points in the system, which is embedded in a larger
Hilbert space constructed by a four-level cold atomic system. We show that a
tunable parameter in the presented system for simulating the non-Hermitian
Hamiltonian can be tuned to swept the eigenstates through the exceptional
points in parameter space. The non-trivial Berry phases of the eigenstates
obtained in this loop from the exceptional points can be measured by the atomic
interferometry. Since the proposed operations and detection are experimentally
feasible, our scheme may pave a promising way to explore the novel properties
of non-Hermitian systems.


title: Nanograin densities outside Saturn's A-ring

abstract:
  The observed disparity between the radial dependence of the ion and electron
densities measured by the Cassini plasma and radio science instruments are used
to show that the region between the outer edge of Saturn's main rings and its
tenuous G-ring is permeated with small charged grains (nanograins). These
grains emanate from the edge of the A-ring and from the tenuous F-ring and
G-ring. This is a region of Saturn's magnetosphere that is relatively
unexplored, but will be a focus of Cassini's F-ring orbits prior to the end of
mission in September 2017. Confirmation of the grain densities predicted here
will enhance our ability to describe the formation and destruction of material
in this important region of Saturn's magnetosphere.


title: On the quantization of continuous non-ultralocal integrable systems

abstract:
  We discuss the quantization of non-ultralocal integrable models directly in
the continuous case, using the example of the Alday-Arutyunov-Frolov model. We
show that by treating fields as distributions and regularizing the operator
product, it is possible to avoid all the singularities, and allow to obtain
results consistent with perturbative calculations. We illustrate these results
by considering the reduction to the massive free fermion model and extracting
the quantum Hamiltonian as well as other conserved charges directly from the
regularized trace identities. Moreover, we show that our regularization
recovers Maillet's prescription in the classical limit.


title:
Scale-selective dissipation in energy-conserving finite element schemes
  for two-dimensional turbulence

abstract:
  We analyse the multiscale properties of energy-conserving upwind-stabilised
finite element discretisations of the two-dimensional incompressible Euler
equations. We focus our attention on two particular methods: the Lie derivative
discretisation introduced in Natale and Cotter (2016a) and the Streamline
Upwind/Petrov-Galerkin (SUPG) discretisation of the vorticity advection
equation. Such discretisations provide control on enstrophy by modelling
different types of scale interactions. We quantify the performance of the
schemes in reproducing the non-local energy backscatter that characterises
two-dimensional turbulent flows.


title: A Comparative Look into Public IXP Datasets

abstract:
  Internet eXchange Points (IXPs) are core components of the Internet
infrastructure where Internet Service Providers (ISPs) meet and exchange
traffic. During the last few years, the number and size of IXPs have increased
rapidly, driving the flattening and shortening of Internet paths. However,
understanding the present status of the IXP ecosystem and its potential role in
shaping the future Internet requires rigorous data about IXPs, their presence,
status, participants, etc. In this work, we do the first cross-comparison of
three well-known publicly available IXP databases, namely of PeeringDB,
Euro-IX, and PCH. A key challenge we address is linking IXP identifiers across
databases maintained by different organizations. We find different AS-centric
versus IXP-centric views provided by the databases as a result of their data
collection approaches. In addition, we highlight differences and similarities
w.r.t. IXP participants, geographical coverage, and co-location facilities. As
a side-product of our linkage heuristics, we make publicly available the union
of the three databases, which includes 40.2 % more IXPs and 66.3 % more IXP
participants than the commonly-used PeeringDB. We also publish our analysis
code to foster reproducibility of our experiments and shed preliminary insights
into the accuracy of the union dataset.


title:
On discriminants, Tjurina modifications and the geometry of
  determinantal singularities

abstract:
  We describe a method for computing discriminants for a large class of
families of isolated determinantal singularities -- more precisely, for
subfamilies of ${\mathcal G}$-versal families. The approach intrinsically
provides a decomposition of the discriminant into two parts and allows the
computation of the determinantal and the non-determinantal loci of the family
without extra effort; only the latter manifests itself in the Tjurina
transform. This knowledge is then applied to the case of Cohen-Macaulay
codimension 2 singularities putting several known, but previously unexplained
observations into context and explicitly constructing a counterexample to
Wahl's conjecture on the relation of Milnor and Tjurina numbers for surface
singularities.


title:
Analytic Poisson brackets on rational functions on the Riemann sphere
  and their generalization

abstract:
  We consider a hierarchy of Poisson structures defined on rational functions
on the Riemann sphere. This hierarchy is originated in the theory of the
integrable Camassa-Holm equation associated with the Krein's string spectral
problem. Previously the proof of Jacobi identity was obtained by reducing the
bracket to canonical Darboux coordinates. The main result of this note is a
direct proof of the Jacobi identity. It turns out that the direct proof of the
Jacobi identity is far from trivial. We also give an example of another
hierarchy of Poisson brackets and construct Darboux coordinates for it.


title: On a transport problem and monoids of non-negative integers

abstract:
  A problem about how to transport profitably a group of cars leads us to study
the set $T$ formed by the integers $n$ such that the system of inequalities,
with non-negative integer coefficients,
  $$a_1x_1 +\cdots+ a_px_p + \alpha \leq n \leq b_1x_1 +\cdots+ b_px_p -
\beta$$ has at least one solution in ${\mathbb N}^p$. We will see that
$T\cup\{0\}$ is a submonoid of $({\mathbb N},+)$. Moreover, we show algorithmic
processes to compute $T$.


title:
Control Exchange Points: Providing QoS-enabled End-to-End Services via
  SDN-based Inter-domain Routing Orchestration

abstract:
  This paper presents the vision of the Control Exchange Point (CXP)
architectural model. The model is motivated by the inflexibility and
ossification of today's inter-domain routing system, which renders critical
QoS-constrained end-to-end (e2e) network services difficult or simply
impossible to provide. CXPs operate on slices of ISP networks and are built on
basic Software Defined Networking (SDN) principles, such as the clean
decoupling of the routing control plane from the data plane and the consequent
logical centralization of control. The main goal of the architectural model is
to provide e2e services with QoS constraints across domains. This is achieved
through defining a new type of business relationship between ISPs, which
advertise partial paths (so-called pathlets) with specific properties, and the
orchestrating role of the CXPs, which dynamically stitch them together and
provision e2e QoS. Revenue from value-added services flows from the clients of
the CXP to the ISPs participating in the service. The novelty of the approach
is the combination of SDN programmability and dynamic path stitching techniques
for inter-domain routing, which extends the value proposition of SDN over
multiple domains. We first describe the challenges related to e2e service
provision with the current inter-domain routing and peering model, and then
continue with the benefits of our approach. Subsequently, we describe the CXP
model in detail and report on an initial feasibility analysis.


title: RSB Decoupling Property of MAP Estimators

abstract:
  The large-system decoupling property of a MAP estimator is studied when it
estimates the i.i.d. vector $\boldsymbol{x}$ from the observation
$\boldsymbol{y}=\mathbf{A}\boldsymbol{x}+\boldsymbol{z}$ with $\mathbf{A}$
being chosen from a wide range of matrix ensembles, and the noise vector
$\boldsymbol{z}$ being i.i.d. and Gaussian. Using the replica method, we show
that the marginal joint distribution of any two corresponding input and output
symbols converges to a deterministic distribution which describes the
input-output distribution of a single user system followed by a MAP estimator.
Under the $b$RSB assumption, the single user system is a scalar channel with
additive noise where the noise term is given by the sum of an independent
Gaussian random variable and $b$ correlated interference terms. As the $b$RSB
assumption reduces to RS, the interference terms vanish which results in the
formerly studied RS decoupling principle.


title: On significance of VLBI/Gaia position offsets

abstract:
  We have cross matched the Gaia Data Release 1 secondary dataset that contains
positions of 1.14 billion objects against the most complete to date catalogue
of VLBI positions of 11.4 thousand sources, almost exclusively active galactic
nuclei. We found 6,064 matches, i.e. 53% radio objects. The median uncertainty
of VLBI positions is a factor of 4 smaller than the median uncertainties of
their optical counterparts. Our analysis shows that the distribution of
normalized arc lengths significantly deviates from Rayleigh shape with an
excess of objects with small normalized arc lengths and with a number of
outliers. We found that 6% matches have radio optical offsets significant at
99% confidence level. Therefore, we conclude there exists a population of
objects with genuine offsets between centroids of radio and optical emission.


title:
Recollision as a probe of magnetic field effects in non-sequential
  double ionization

abstract:
  Fully accounting for non-dipole effects in the electron dynamics, double
ionization is studied for He driven by a near-infrared laser field and for Xe
driven by a mid-infrared laser field. Using a three-dimensional semiclassical
model, the average sum of the electron momenta along the propagation direction
of the laser field is computed. This sum is found to be an order of magnitude
larger than twice the average electron momentum along the propagation direction
of the laser field in single ionization. Moreover, the average sum of the
electron momenta in double ionization is found to be maximum at intensities
smaller than the intensities satisfying previously predicted criteria for the
onset of magnetic field effects. It is shown that strong recollisions are the
reason for this unexpectedly large value of the sum of the momenta along the
direction of the magnetic component of the Lorentz force.


title:
VLBI-Gaia offsets favor parsec-scale jet direction in Active Galactic
  Nuclei

abstract:
  The data release 1 (DR1) of milliarcsecond-scale accurate optical positions
of stars and galaxies was recently published by the space mission Gaia. We
study the offsets of highly accurate absolute radio (very long baseline
interferometry, VLBI) and optical positions of active galactic nuclei (AGN) to
see whether or not a signature of wavelength-dependent parsec-scale structure
can be seen. We analyzed VLBI and Gaia positions and determined the direction
of jets in 2957 AGNs from their VLBI images. We find that there is a
statistically significant excess of sources with VLBI-to-Gaia position offset
in directions along and opposite to the jet. Offsets along the jet vary from
zero to tens of mas. Offsets in the opposite direction do not exceed 3 mas. The
presense of strong, extended parsec-scale optical jet structures in many AGNs
is required to explain all observed VLBI-Gaia offsets along the jet direction.
The offsets in the opposite direction shorter than 1 mas can be explained
either by a non-point-like VLBI jet structure or a "core-shift" effect due to
synchrotron opacity.


title:
Ab initio Description of Optoelectronic Properties at Defective
  Interfaces in Solar Cells

abstract:
  In order to optimize the optoelectronic properties of novel solar cell
architectures, such as the amorphous-crystalline interface in silicon
heterojunction devices, we calculate and analyze the local microscopic
structure at this interface and in bulk a-Si:H, in particular with respect to
the impact of material inhomogeneities. The microscopic information is used to
extract macroscopic material properties, and to identify localized defect
states, which govern the recombination properties encoded in quantities such as
capture cross sections used in the Shockley-Read-Hall theory. To this end,
atomic configurations for a-Si:H and a-Si:H/c-Si interfaces are generated using
molecular dynamics. Density functional theory calculations are then applied to
these configurations in order to obtain the electronic wave functions. These
are analyzed and characterized with respect to their localization and their
contribution to the (local) density of states. GW calculations are performed
for the a-Si:H configuration in order to obtain a quasi-particle corrected
absorption spectrum. The results suggest that the quasi-particle corrections
can be approximated through a scissors shift of the Kohn-Sham energies.


title:
Physical characterization of Galactic O-type stars targeted by the IACOB
  and OWN surveys

abstract:
  We present first results from the quantitative spectroscopic analysis of 266
Galactic O-type stars targeted by the IACOB and OWN surveys (implying the
largest sample of stars of this type analyzed homogeneously). We also evaluate
what is the present situation regarding available information about distances,
as provided by the Hipparcos and Gaia missions.


title: A Lyapunov Analysis of Momentum Methods in Optimization

abstract:
  Momentum methods play a significant role in optimization. Examples include
Nesterov's accelerated gradient method and the conditional gradient algorithm.
Several momentum methods are provably optimal under standard oracle models, and
all use a technique called estimate sequences to analyze their convergence
properties. The technique of estimate sequences has long been considered
difficult to understand, leading many researchers to generate alternative,
"more intuitive" methods and analyses. We show there is an equivalence between
the technique of estimate sequences and a family of Lyapunov functions in both
continuous and discrete time. This connection allows us to develop a simple and
unified analysis of many existing momentum algorithms, introduce several new
algorithms, and strengthen the connection between algorithms and
continuous-time dynamical systems.


title: Time-dependent potential through an Ansatz for the Kohn-Sham orbitals

abstract:
  Given the time-evolution of an electron charge density, the local potential
in Kohn-Sham time-dependent density functional theory (KS-TDDFT) can be modeled
as a sum of instantaneous and dynamic contributions by assuming a certain form
of the time-dependent Kohn-Sham (TD-KS) orbitals. The instantaneous part is
obtained numerically using methods from ground-state density functional theory
(DFT) and the dynamic part is expressed in terms of a velocity potential that
depends on the electron current density. The suggested form of the TD-KS
orbitals satisfies several known constraints (orthonormality,
N-representability, J-representability), and the domain of validity is shown to
depend on the evolution of the instantaneous quantities. Through this
decomposition, we can relate time-dependent and ground -state
V-representability. The resulting potentials are shown numerically to
approximate the exact time-dependent Kohn-Sham potentials for a set of 3
non-singlet two-particle systems (a Kohn-mode, a Coulomb explosion, and a
double quantum well) where the exact solutions and reference densities are
known or obtained through configuration interaction (CI) approaches.


title: Estimating motion with principal component regression strategies

abstract:
  In this paper, two simple principal component regression methods for
estimating the optical flow between frames of video sequences according to a
pel-recursive manner are introduced. These are easy alternatives to dealing
with mixtures of motion vectors in addition to the lack of prior information on
spatial-temporal statistics (although they are supposed to be normal in a local
sense). The 2D motion vector estimation approaches take into consideration
simple image properties and are used to harmonize regularized least square
estimates. Their main advantage is that no knowledge of the noise distribution
is necessary, although there is an underlying assumption of localized
smoothness. Preliminary experiments indicate that this approach provides robust
estimates of the optical flow.


title:
The asteroseismic surface effect from a grid of 3D convection
  simulations. I. Frequency shifts from convective expansion of stellar
  atmospheres

abstract:
  We analyse the effect on adiabatic stellar oscillation frequencies of
replacing the near-surface layers in 1D stellar structure models with averaged
3D stellar surface convection simulations. The main difference is an expansion
of the atmosphere by 3D convection, expected to explain a major part of the
asteroseismic surface effect; a systematic overestimation of p-mode frequencies
due to inadequate surface physics.
  We employ pairs of 1D stellar envelope models and 3D simulations from a
previous calibration of the mixing-length parameter, alpha. That calibration
constitutes the hitherto most consistent matching of 1D models to 3D
simulations, ensuring that their differences are not spurious, but entirely due
to the 3D nature of convection. The resulting frequency shift is identified as
the structural part of the surface effect. The important, typically
non-adiabatic, modal components of the surface effect are not included in the
present analysis, but relegated to future papers.
  Evaluating the structural surface effect at the frequency of maximum mode
amplitude, $\nu_{\rm max}$, we find shifts from $\delta\nu$=-0.8 microHz for
giants at $\log g$=2.2 to -35 microHz for a ($T_{\rm eff}=6901$ K, $\log
g$=4.29) dwarf. The fractional effect $\delta\nu(\nu_{\rm max})/\nu_{\rm max}$,
ranges from -0.1% for a cool dwarf (4185 K, 4.74) to -6% for a warm giant (4962
K, 2.20).


title: Gradients of Counterfactuals

abstract:
  Gradients have been used to quantify feature importance in machine learning
models. Unfortunately, in nonlinear deep networks, not only individual neurons
but also the whole network can saturate, and as a result an important input
feature can have a tiny gradient. We study various networks, and observe that
this phenomena is indeed widespread, across many inputs.
  We propose to examine interior gradients, which are gradients of
counterfactual inputs constructed by scaling down the original input. We apply
our method to the GoogleNet architecture for object recognition in images, as
well as a ligand-based virtual screening network with categorical features and
an LSTM based language model for the Penn Treebank dataset. We visualize how
interior gradients better capture feature importance. Furthermore, interior
gradients are applicable to a wide variety of deep networks, and have the
attribution property that the feature importance scores sum to the the
prediction score.
  Best of all, interior gradients can be computed just as easily as gradients.
In contrast, previous methods are complex to implement, which hinders practical
adoption.


title: Amann-Zehnder type results for p-Laplace problems

abstract:
  The existence of a nontrivial solution is proved for a class of quasilinear
elliptic equations involving, as principal part, either the p-Laplace operator
or the operator related to the p-area functional, and a nonlinearity with
p-linear growth at infinity. To this aim, Morse theory techniques are combined
with critical groups estimates.


title: On the Regularity of Hamiltonian Stationary Lagrangian manifolds

abstract:
  We prove a Morrey-type theorem for Hamiltonian stationary submanifolds of
$\mathbb{C}^{n}$. Namely, if $L$ $\subset$ $\mathbb{C}^{n}$ is a $C^{1}$
Lagrangian submanifold with weakly harmonic Lagrangian phase $\theta,$ then $L$
must be smooth. In the process we also discuss a local version of the equation,
which is a nonlinear fourth order double divergence equation of the potential
function whose gradient graph defines the Hamiltonian stationary submanifolds
locally, and we establish full regularity and removability of singular sets of
capacity zero for weak solutions with $C^{1,1}$ norm below a dimensional
constant.


title: Stitching Inter-Domain Paths over IXPs

abstract:
  Modern Internet applications, from HD video-conferencing to health monitoring
and remote control of power-plants, pose stringent demands on network latency,
bandwidth and availability. An approach to support such applications and
provide inter-domain guarantees, enabling new avenues for innovation, is using
centralized inter-domain routing brokers. These entities centralize routing
control for mission-critical traffic across domains, working in parallel to
BGP. In this work, we propose using IXPs as natural points for stitching
inter-domain paths under the control of inter-domain routing brokers. To
evaluate the potential of this approach, we first map the global substrate of
inter-IXP pathlets that IXP members could offer, based on measurements for 229
IXPs worldwide. We show that using IXPs as stitching points has two useful
properties. Up to 91 % of the total IPv4 address space can be served by such
inter-domain routing brokers when working in concert with just a handful of
large IXPs and their associated ISP members. Second, path diversity on the
inter-IXP graph increases by up to 29 times, as compared to current BGP
valley-free routing. To exploit the rich path diversity, we introduce
algorithms that inter-domain routing brokers can use to embed paths, subject to
bandwidth and latency constraints. We show that our algorithms scale to the
sizes of the measured graphs and can serve diverse simulated path request
mixes. Our work highlights a novel direction for SDN innovation across domains,
based on logically centralized control and programmable IXP fabrics.


title:
Orbital selective pairing and gap structures of iron-based
  superconductors

abstract:
  We discuss the influence on spin-fluctuation pairing theory of orbital
selective strong correlation effects in Fe-based superconductors, particularly
Fe chalcogenide systems. We propose that a key ingredient for an improved
itinerant pairing theory is orbital selectivity, i.e., incorporating the
reduced coherence of quasiparticles occupying specific orbital states. This
modifies the usual spin-fluctuation via suppression of pair scattering
processes involving those less coherent states and results in orbital selective
Cooper pairing of electrons in the remaining states. We show that this paradigm
yields remarkably good agreement with the experimentally observed anisotropic
gap structures in both bulk and monolayer FeSe, as well as LiFeAs, indicating
that orbital selective Cooper pairing plays a key role in the more strongly
correlated iron-based superconductors.


title: Multispectral Deep Neural Networks for Pedestrian Detection

abstract:
  Multispectral pedestrian detection is essential for around-the-clock
applications, e.g., surveillance and autonomous driving. We deeply analyze
Faster R-CNN for multispectral pedestrian detection task and then model it into
a convolutional network (ConvNet) fusion problem. Further, we discover that
ConvNet-based pedestrian detectors trained by color or thermal images
separately provide complementary information in discriminating human instances.
Thus there is a large potential to improve pedestrian detection by using color
and thermal images in DNNs simultaneously. We carefully design four ConvNet
fusion architectures that integrate two-branch ConvNets on different DNNs
stages, all of which yield better performance compared with the baseline
detector. Our experimental results on KAIST pedestrian benchmark show that the
Halfway Fusion model that performs fusion on the middle-level convolutional
features outperforms the baseline method by 11% and yields a missing rate 3.5%
lower than the other proposed architectures.


title: Isomorphisms of non noetherian down-up algebras

abstract:
  We solve the isomorphism problem for non noetherian down-up algebras
$A(\alpha,0,\gamma)$ by lifting isomorphisms between some of their non
commutative quotients. The quotients we consider are either quantum polynomial
algebras in two variables for $\gamma = 0$ or quantum versions of the Weyl
algebra $A_1$ for non zero $\gamma$. In particular we obtain that no other
down-up algebra is isomorphic to the monomial algebra $A(0,0,0)$. We prove in
the second part of the article that this is the only monomial algebra within
the family of down-up algebras. Our method uses homological invariants that
determine the shape of the possible quivers and we apply the abelianization
functor to complete the proof.


title: On interestingness measures of formal concepts

abstract:
  Formal concepts and closed itemsets proved to be of big importance for
knowledge discovery, both as a tool for concise representation of association
rules and a tool for clustering and constructing domain taxonomies and
ontologies. Exponential explosion makes it difficult to consider the whole
concept lattice arising from data, one needs to select most useful and
interesting concepts. In this paper interestingness measures of concepts are
considered and compared with respect to various aspects, such as efficiency of
computation and applicability to noisy data and performing ranking correlation.


title: Multipartite Entanglement and Firewalls

abstract:
  Black holes offer an exciting area to explore the nature of quantum gravity.
The classic work on Hawking radiation indicates that black holes should decay
via quantum effects, but our ideas about how this might work at a technical
level are incomplete. Recently Almheiri-Marolf-Polchinski-Sully (AMPS) have
noted an apparent paradox in reconciling fundamental properties of quantum
mechanics with standard beliefs about black holes. One way to resolve the
paradox is to postulate the existence of a "firewall" inside the black hole
horizon which prevents objects from falling smoothly toward the singularity. A
fundamental limitation on the behavior of quantum entanglement known as
"monogamy" plays a key role in the AMPS argument. Our goal is to study and
apply many-body entanglement theory to consider the entanglement among
different parts of Hawking radiation and black holes. Using the multipartite
entanglement measure called negativity, we identify an example which could
change the AMPS accounting of quantum entanglement and perhaps eliminate the
need for a firewall. Specifically, we constructed a toy model for black hole
decay which has different entanglement behavior than that assumed by AMPS. We
discuss the additional steps that would be needed to bring lessons from our toy
model to our understanding of realistic black holes.


title:
Deep Unsupervised Clustering with Gaussian Mixture Variational
  Autoencoders

abstract:
  We study a variant of the variational autoencoder model (VAE) with a Gaussian
mixture as a prior distribution, with the goal of performing unsupervised
clustering through deep generative models. We observe that the known problem of
over-regularisation that has been shown to arise in regular VAEs also manifests
itself in our model and leads to cluster degeneracy. We show that a heuristic
called minimum information constraint that has been shown to mitigate this
effect in VAEs can also be applied to improve unsupervised clustering
performance with our model. Furthermore we analyse the effect of this heuristic
and provide an intuition of the various processes with the help of
visualizations. Finally, we demonstrate the performance of our model on
synthetic data, MNIST and SVHN, showing that the obtained clusters are
distinct, interpretable and result in achieving competitive performance on
unsupervised clustering to the state-of-the-art results.


title: On a Counting Theorem of Skriganov

abstract:
  We prove a counting theorem concerning the number of lattice points for the
dual lattices of weakly admissible lattices in an inhomogeneously expanding
box, which generalises a counting theorem of Skriganov. The error term is
expressed in terms of a certain function $\nu(\Gamma^\perp,\cdot)$ of the dual
lattice $\Gamma^\perp$, and we carefully analyse the relation of this quantity
with $\nu(\Gamma,\cdot)$. In particular, we show that
$\nu(\Gamma^\perp,\cdot)=\nu(\Gamma,\cdot)$ for any unimodular lattice of rank
2, but that for higher ranks it is in general not possible to bound one
function in terms of the other. Finally, we apply our counting theorem to
establish asymptotics for the number of Diophantine approximations with bounded
denominator as the denominator bound gets large.


title:
Eigensystem multiscale analysis for Anderson localization in energy
  intervals

abstract:
  We present an eigensystem multiscale analysis for proving localization (pure
point spectrum with exponentially decaying eigenfunctions, dynamical
localization) for the Anderson model in an energy interval. In particular, it
yields localization for the Anderson model in a nonempty interval at the bottom
of the spectrum. This eigensystem multiscale analysis in an energy interval
treats all energies of the finite volume operator at the same time,
establishing level spacing and localization of eigenfunctions with eigenvalues
in the energy interval in a fixed box with high probability. In contrast to the
usual strategy, we do not study finite volume Green's functions. Instead, we
perform a multiscale analysis based on finite volume eigensystems (eigenvalues
and eigenfunctions). In any given scale we only have decay for eigenfunctions
with eigenvalues in the energy interval, and no information about the other
eigenfunctions. For this reason, going to a larger scale requires new arguments
that were not necessary in our previous eigensystem multiscale analysis for the
Anderson model at high disorder, where in a given scale we have decay for all
eigenfunctions.


title:
A combinatorial approach to integrals of Kahan-Hirota-Kimura
  discretizations

abstract:
  We consider an Ansatz for the study of the existence of formal integrals of
motion for Kahan-Hirota-Kimura discretizations. In this context, we give a
combinatorial proof of the formula of Celledoni-McLachlan-Owren-Quispel for an
integral of motion of the discretization in the case of cubic Hamiltonian
systems on symplectic vector spaces and Poisson vector spaces with constant
Poisson structure.


title: Space weather research and forecast in USA

abstract:
  In the United States, scientific research in space weather is funded by
several Government Agencies including the National Science Foundation (NSF) and
the National Aeronautics and Space Agency (NASA). For commercial purposes,
space weather forecast is made by the Space Weather Prediction Center (SWPC) of
the National Oceanic and Atmospheric Administration (NOAA). Observations come
from the network of groundbased observatories funded via various sources, as
well as from the instruments on spacecraft. Numerical models used in forecast
are developed in the framework of individual research projects. Later, the most
promising models are selected for additional testing at SWPC. In order to
increase the application of models in research and education, NASA in
collaboration with other agencies created Community Coordinated Modeling Center
(CCMC). In mid-1990, US scientific community presented compelling evidence for
developing the National Program on Space Weather, and in 1995, such program has
been formally created. In 2015, the National Council on Science and Technology
issued two documents: the National Space Weather Strategy [1] and the Action
Plan [2]. In the near future, these two documents will define the development
of Space Weather research and forecasting activity in USA. Both documents
emphasize the need for close international collaboration in area of space
weather.


title:
Conditional Square Functions, the Sine-Cosine Decomposition for Hardy
  Martingales and Dyadic Perturbation

abstract:
  We prove that the $\cal P$ norm estimate between a Hardy martingale and its
cosine part are stable under dyadic perturbations, and show how dyadic
stability of the $\cal P$ norm estimate is used in the proof that $L^1$ embeds
into $L^1/H^1$.


title: Sentence Ordering and Coherence Modeling using Recurrent Neural Networks

abstract:
  Modeling the structure of coherent texts is a key NLP problem. The task of
coherently organizing a given set of sentences has been commonly used to build
and evaluate models that understand such structure. We propose an end-to-end
unsupervised deep learning approach based on the set-to-sequence framework to
address this problem. Our model strongly outperforms prior methods in the order
discrimination task and a novel task of ordering abstracts from scientific
articles. Furthermore, our work shows that useful text representations can be
obtained by learning to order sentences. Visualizing the learned sentence
representations shows that the model captures high-level logical structure in
paragraphs. Our representations perform comparably to state-of-the-art
pre-training methods on sentence similarity and paraphrase detection tasks.


title: Spectral Statistics of Lattice Graph Percolation Models

abstract:
  In graph signal processing, the graph adjacency matrix or the graph Laplacian
commonly define the shift operator. The spectral decomposition of the shift
operator plays an important role in that the eigenvalues represent frequencies
and the eigenvectors provide a spectral basis. This is useful, for example, in
the design of filters. However, the graph or network may be uncertain due to
stochastic influences in construction and maintenance, and, under such
conditions, the eigenvalues of the shift matrix become random variables. This
paper examines the spectral distribution of the eigenvalues of random networks
formed by including each link of a D-dimensional lattice supergraph
independently with identical probability, a percolation model. Using the
stochastic canonical equation methods developed by Girko for symmetric matrices
with independent upper triangular entries, a deterministic distribution is
found that asymptotically approximates the empirical spectral distribution of
the scaled adjacency matrix for a model with arbitrary parameters. The main
results characterize the form of the solution to an important system of
equations that leads to this deterministic distribution function and
significantly reduce the number of equations that must be solved to find the
solution for a given set of model parameters. Simulations comparing the
expected empirical spectral distributions and the computed deterministic
distributions are provided for sample parameters.


title:
Synchrony in a Boolean network model of the L-arabinose operon in
  Escherichia coli

abstract:
  The lactose operon in Escherichia coli was the first known gene regulatory
network, and it is frequently used as a prototype for new modeling paradigms.
Historically, many of these modeling frameworks use differential equations.
More recently, Stigler and Veliz-Cuba proposed a Boolean network model that
captures the bistability of the system and all of the biological steady states.
In this paper, we model the well-known arabinose operon in E. coli with a
Boolean network. This has several complex features not found in the lac operon,
such as a protein that is both an activator and repressor, a DNA looping
mechanism for gene repression, and the lack of inducer exclusion by glucose.
For 11 out of 12 choices of initial conditions, we use computational algebra
and Sage to verify that the state space contains a single fixed point that
correctly matches the biology. The final initial condition, medium levels of
arabinose and no glucose, successfully predicts the system's bistability.
Finally, we compare the state space under synchronous and asynchronous update,
and see that the former has several artificial cycles that go away under a
general asynchronous update.


title:
Dissecting the Evolution of Dark Matter Subhaloes in the Bolshoi
  Simulation

abstract:
  We present a comprehensive analysis of the evolution of dark matter subhaloes
in the cosmological Bolshoi simulation. We identify a complete set of 12 unique
evolution channels by which subhaloes evolve in between simulation outputs, and
study their relative importance and demographics. We show that instantaneous
masses and maximum circular velocities of individual subhaloes are extremely
noisy, despite the use of a sophisticated, phase-space-based halo finder. We
also show that subhaloes experience frequent penetrating encounters with other
subhaloes (on average about one per dynamical time), and that subhaloes whose
apo-center lies outside the virial radius of their host (the 'ejected' or
'backsplash' haloes) experience tidal forces that modify their orbits. This
results in an average fractional subhalo exchange rate among host haloes of
roughly 0.01 per Gyr (at the present time). In addition, we show that there are
three distinct disruption channels; one in which subhaloes drop below the mass
resolution limit of the simulation, one in which subhaloes merge with their
host halo largely driven by dynamical friction, and one in which subhaloes
abruptly disintegrate. We estimate that roughly 80 percent of all subhalo
disruption in the Bolshoi simulation is numerical, rather than physical. This
over-merging is a serious road-block for the use of numerical simulations to
interpret small scale clustering, or for any other study that is sensitive to
the detailed demographics of dark matter substructure.


title:
\emph{Ab initio} Quantum Monte Carlo simulation of the warm dense
  electron gas

abstract:
  Warm dense matter is one of the most active frontiers in plasma physics due
to its relevance for dense astrophysical objects as well as for novel
laboratory experiments in which matter is being strongly compressed e.g. by
high-power lasers. Its description is theoretically very challenging as it
contains correlated quantum electrons at finite temperature---a system that
cannot be accurately modeled by standard analytical or ground state approaches.
Recently several breakthroughs have been achieved in the field of fermionic
quantum Monte Carlo simulations. First, it was shown that exact simulations of
a finite model system ($30 \dots 100$ electrons) is possible that avoid any
simplifying approximations such as fixed nodes [Schoof {\em et al.}, Phys. Rev.
Lett. {\bf 115}, 130402 (2015)]. Second, a novel way to accurately extrapolate
these results to the thermodynamic limit was reported by Dornheim {\em et al.}
[Phys. Rev. Lett. {\bf 117}, 156403 (2016)]. As a result, now thermodynamic
results for the warm dense electron gas are available that have an
unprecedented accuracy on the order of $0.1\%$. Here we present an overview on
these results and discuss limitations and future directions.


title: GSM based CommSense system to measure and estimate environmental changes

abstract:
  Facilitating the coexistence of radar systems with communication systems has
been a major area of research in radar engineering. The current work presents a
new way to sense the environment using the channel equalization block of
existing communication systems. We have named this system CommSense. In the
current paper we demonstrate the feasibility of the system using Global System
for Mobile Communications (GSM) signals. The implementation has been done using
open-source Software Defined Radio (SDR) environment. In the preliminary
results obtained in our work we show that it is possible to distinguish
environmental changes using the proposed system. The major advantage of the
system is that it is inexpensive as channel estimation is an inherent block in
any communication system and hence the added cost to make it work as an
environment sensor is minimal. The major challenge, on which we are continuing
our work, is how to characterize the features in the environmental changes.
This is an acute challenge given the fact that the bandwidth available is
narrow and the system is inherently a forward looking radar. However the
initial results, as shown in this paper, are encouraging and we intend to use
an application specific instrumentation (ASIN) scheme to distinguish the
environmental changes.


title:
Tradeoff Caching Strategy of Outage Probability and Fronthaul Usage in
  Cloud-RAN

abstract:
  In this paper, optimal content caching strategy is proposed to jointly
minimize the cell average outage probability and fronthaul usage in cloud radio
access network (Cloud-RAN). At first, an accurate closed form expression of the
outage probability conditioned on the user's location is presented, and the
cell average outage probability is obtained through the composite Simpson's
integration. The caching strategy for jointly optimizing the cell average
outage probability and fronthaul usage is then formulated as a weighted sum
minimization problem, which is a nonlinear 0-1 integer NP-hard problem. In
order to deal with the NP-hard problem, two heuristic algorithms are proposed
in this paper. Firstly, a genetic algorithm (GA) based approach is proposed.
Numerical results show that the performance of the proposed GA-based approach
with significantly reduced computational complexity is close to the optimal
performance achieved by exhaustive search based caching strategy. Secondly, in
order to further reduce the computational complexity, a mode selection approach
is proposed. Numerical results show that this approach can achieve near-optimal
performance over a wide range of the weighting factors through a single
computation.


title: A submillimeter study of the IR dust bubble S 21 and its environs

abstract:
  Based on the molecular emission in the $^{12}$CO(2-1) and $^{13}$CO(2-1)
lines, and the continuum emission in the MIR and FIR towards the S21 IR dust
bubble, we analyze the physical characteristics of the gas and dust linked to
the nebula and the presence of young stellar objects (YSOs) in its environs.
The line emission reveals a clumpy molecular shell, 1.4 pc in radius,
encircling S21. The total molecular mass in the shell amounts to 2900 solar
masses and the original ambient density, 2.1 x 10$^3$ cm$^{-3}$, indicating
that the bubble is evolving in a high density interstellar medium. The image at
24 $\mu$m shows warm dust inside the bubble, while the emission in the range
250 to 870 $\mu$m reveal cold dust in its outskirts, coincident with the
molecular gas. The detection of radio continuun emission indicates that the
bubble is a compact HII region. A search for YSOs using photometric criteria
allowed to identify many candidates projected onto the molecular clumps. We
analize if the collect and collapse process has triggered a new generation of
stars.


title: Synopsis of a Unified Theory for All Forces and Matter

abstract:
  Assuming the Kaluza-Klein gravity interacting with elementary matter fermions
in a (9+1)-dimensional spacetime ($\mathcal{M}_{9+1}$), we propose an
information-complete unified theory for all forces and matter. Due to
entanglement-driven symmetry breaking, the SO(9,1) symmetry of
$\mathcal{M}_{9+1}$ is broken to $SO(3,1)\times SO(6)$, where SO(3,1) [SO(6)]
is associated with gravity (gauge fields of matter fermions) in
(3+1)-dimensional spacetime ($\mathcal{M}_{3+1}$). The informational
completeness demands that matter fermions must appear in three families, each
having 16 independent matter fermions. Meanwhile, the fermion family space is
equipped with elementary SO(3) gauge fields in $\mathcal{M}_{9+1}$, giving rise
to the Higgs mechanism in $\mathcal{M}_{3+1}$ through the gauge-Higgs
unification. After quantum compactification of six extra dimensions, a
trinity---the quantized gravity, the three-family fermions of total number 48,
and their SO(6) and SO(3) gauge fields---naturally arises in an effective
theory in $\mathcal{M}_{3+1}$. Possible routes of our theory to the Standard
Model are briefly discussed.


title: On the Complexity of Local Distributed Graph Problems

abstract:
  This paper is centered on the complexity of graph problems in the
well-studied LOCAL model of distributed computing, introduced by Linial [FOCS
'87]. It is widely known that for many of the classic distributed graph
problems (including maximal independent set (MIS) and $(\Delta+1)$-vertex
coloring), the randomized complexity is at most polylogarithmic in the size $n$
of the network, while the best deterministic complexity is typically
$2^{O(\sqrt{\log n})}$. Understanding and narrowing down this exponential gap
is considered to be one of the central long-standing open questions in the area
of distributed graph algorithms. We investigate the problem by introducing a
complexity-theoretic framework that allows us to shed some light on the role of
randomness in the LOCAL model. We define the SLOCAL model as a sequential
version of the LOCAL model. Our framework allows us to prove completeness
results with respect to the class of problems which can be solved efficiently
in the SLOCAL model, implying that if any of the complete problems can be
solved deterministically in $\log^{O(1)} n$ rounds in the LOCAL model, we can
deterministically solve all efficient SLOCAL-problems (including MIS and
$(\Delta+1)$-coloring) in $\log^{O(1)} n$ rounds in the LOCAL model. We show
that a rather rudimentary looking graph coloring problem is complete in the
above sense: Color the nodes of a graph with colors red and blue such that each
node of sufficiently large polylogarithmic degree has at least one neighbor of
each color. The problem admits a trivial zero-round randomized solution. The
result can be viewed as showing that the only obstacle to getting efficient
determinstic algorithms in the LOCAL model is an efficient algorithm to
approximately round fractional values into integer values.


title: Quantum State Reduction

abstract:
  We propose an energy-driven stochastic master equation for the density matrix
as a dynamical model for quantum state reduction. In contrast, most previous
studies of state reduction have considered stochastic extensions of the
Schr\"odinger equation, and have introduced the density matrix as the
expectation of the random pure projection operator associated with the evolving
state vector. After working out properties of the reduction process we
construct a general solution to the energy-driven stochastic master equation.
The solution is obtained by the use of nonlinear filtering theory and takes the
form of a completely positive stochastic map.


title:
Optimization and parallelization of B-spline based orbital evaluations
  in QMC on multi/many-core shared memory processors

abstract:
  B-spline based orbital representations are widely used in Quantum Monte Carlo
(QMC) simulations of solids, historically taking as much as 50% of the total
run time. Random accesses to a large four-dimensional array make it challenging
to efficiently utilize caches and wide vector units of modern CPUs. We present
node-level optimizations of B-spline evaluations on multi/many-core shared
memory processors. To increase SIMD efficiency and bandwidth utilization, we
first apply data layout transformation from array-of-structures to
structure-of-arrays (SoA). Then by blocking SoA objects, we optimize cache
reuse and get sustained throughput for a range of problem sizes. We implement
efficient nested threading in B-spline orbital evaluation kernels, paving the
way towards enabling strong scaling of QMC simulations. These optimizations are
portable on four distinct cache-coherent architectures and result in up to 5.6x
performance enhancements on Intel Xeon Phi processor 7250P (KNL), 5.7x on Intel
Xeon Phi coprocessor 7120P, 10x on an Intel Xeon processor E5v4 CPU and 9.5x on
BlueGene/Q processor. Our nested threading implementation shows nearly ideal
parallel efficiency on KNL up to 16 threads. We employ roofline performance
analysis to model the impacts of our optimizations. This work combined with our
current efforts of optimizing other QMC kernels, result in greater than 4.5x
speedup of miniQMC on KNL.


title:
Mosaic: Designing Online Creative Communities for Sharing
  Works-in-Progress

abstract:
  Online creative communities allow creators to share their work with a large
audience, maximizing opportunities to showcase their work and connect with fans
and peers. However, sharing in-progress work can be technically and socially
challenging in environments designed for sharing completed pieces. We propose
an online creative community where sharing process, rather than showcasing
outcomes, is the main method of sharing creative work. Based on this, we
present Mosaic---an online community where illustrators share work-in-progress
snapshots showing how an artwork was completed from start to finish. In an
online deployment and observational study, artists used Mosaic as a vehicle for
reflecting on how they can improve their own creative process, developed a
social norm of detailed feedback, and became less apprehensive of sharing early
versions of artwork. Through Mosaic, we argue that communities oriented around
sharing creative process can create a collaborative environment that is
beneficial for creative growth.


title: Endo-parameters for p-adic classical groups

abstract:
  For a classical group over a non-archimedean local field of odd residual
characteristic p, we prove that two cuspidal types, defined over an
algebraically closed field C of characteristic different from p, intertwine if
and only if they are conjugate. This completes work of the first and third
authors who showed that every irreducible cuspidal C-representation of a
classical group is compactly induced from a cuspidal type. We generalize
Bushnell and Henniart's notion of endo-equivalence to semisimple characters of
general linear groups and to self-dual semisimple characters of classical
groups, and introduce (self-dual) endo-parameters. We prove that these
parametrize intertwining classes of (self-dual) semisimple characters and
conjecture that they are in bijection with wild Langlands parameters,
compatibly with the local Langlands correspondence.


title: Computing the Laplace eigenvalue and level of Maass cusp forms

abstract:
  Let $f$ be a primitive Maass cusp form for a congruence subgroup $\Gamma_0(D)
\subset $ SL($2,\mathbb{Z}$) and $\lambda_f(n)$ its $n$-th Fourier coefficient.
In this paper it is shown that with knowledge of only finitely many
$\lambda_f(n)$ one can often solve for the level $D$, and in some cases,
estimate the Laplace eigenvalue to arbitrarily high precision. This is done by
analyzing the resonance and rapid decay of smoothly weighted sums of
$\lambda_f(n)e(\alpha n^{\beta})$ for $X \leq n \leq 2X$ and any choice of
$\alpha \in \mathbb{R}$, and $\beta>0$. The methods include the Voronoi
summation formula, asymptotic expansions of Bessel functions, weighted
stationary phase, and computational software. These algorithms manifest the
belief that the resonance and rapid decay nature uniquely characterizes the
underlying cusp form. They also demonstrate that the Fourier coefficients of a
cusp form contain all arithmetic information of the form.


title: Testbeam results of irradiated ams H18 HV-CMOS pixel sensor prototypes

abstract:
  HV-CMOS pixel sensors are a promising option for the tracker upgrade of the
ATLAS experiment at the LHC, as well as for other future tracking applications
in which large areas are to be instrumented with radiation-tolerant silicon
pixel sensors. We present results of testbeam characterisations of the
$4^{\mathrm{th}}$ generation of Capacitively Coupled Pixel Detectors (CCPDv4)
produced with the ams H18 HV-CMOS process that have been irradiated with
different particles (reactor neutrons and 18 MeV protons) to fluences between
$1\cdot 10^{14}$ and $5\cdot 10^{15}$ 1-MeV-n$_\textrm{eq}$/cm$^2$. The sensors
were glued to ATLAS FE-I4 pixel readout chips and measured at the CERN SPS H8
beamline using the FE-I4 beam telescope. Results for all fluences are very
encouraging with all hit efficiencies being better than 97% for bias voltages
of $85\,$V. The sample irradiated to a fluence of $1\cdot 10^{15}$
n$_\textrm{eq}$/cm$^2$ - a relevant value for a large volume of the upgraded
tracker - exhibited 99.7% average hit efficiency. The results give strong
evidence for the radiation tolerance of HV-CMOS sensors and their suitability
as sensors for the experimental HL-LHC upgrades and future large-area
silicon-based tracking detectors in high-radiation environments.


title: The Sandwich Theorem for Sublinear and Superlinear Functionals

abstract:
  The Hahn-Banach theorem is an extension theorem for linear functionals which
preserves certain properties. Specifically, if a linear functional is defined
on a subspace of a real vector space which is dominated by a sublinear
functional on the entire space, then this functional can be extended to a
linear functional on the entire space which is still dominated by a sublinear
functional. In this paper, we generalize this result to show that a linear
functional defined on a subspace of a real vector space which is dominated by a
sublinear functional and also dominates a superlinear functional on the entire
space can be extended to a linear functional on the entire space which is also
dominated by a sublinear functional and dominates a superlinear functional.


title: Analytic solution of an oscillatory migratory alpha^2 stellar dynamo

abstract:
  Analytic solutions of the mean-field induction equation predict a
nonoscillatory dynamo for homogeneous helical turbulence or constant alpha
effect in unbounded or periodic domains. Oscillatory dynamos are generally
thought impossible for constant alpha. We present an analytic solution for a
one-dimensional bounded domain resulting in oscillatory solutions for constant
alpha, but different (Dirichlet and von Neumann or perfect conductor and
vacuum) boundary conditions on the two boundaries. We solve a second order
complex equation and superimpose two independent solutions to obey both
boundary conditions. The solution has time-independent energy density. On one
end where the function value vanishes, the second derivative is finite, which
would not be correctly reproduced with sine-like expansion functions where a
node coincides with an inflection point. The field always migrates away from
the perfect conductor boundary toward the vacuum boundary, independently of the
sign of alpha. The obtained solution may serve as a benchmark for numerical
dynamo experiments and as a pedagogical illustration that oscillatory migratory
dynamos are possible with constant alpha.


title:
$Z^\prime$-portal right-handed neutrino dark matter in the minimal
  U(1)$_X$ extended Standard Model

abstract:
  We consider a concise dark matter (DM) scenario in the context of a
non-exotic U(1) extension of the Standard Model (SM), where a new U(1)$_X$
gauge symmetry is introduced along with three generation of right-handed
neutrinos (RHNs) and an SM gauge singlet Higgs field. The model is a
generalization of the minimal gauged U(1)$_{B-L}$ (baryon number minus lepton
number) extension of the SM, in which the extra U(1)$_X$ gauge symmetry is
expressed as a linear combination of the SM U(1)$_Y$ and U(1)$_{B-L}$ gauge
symmetries. We introduce a $Z_2$-parity and assign an odd-parity only for one
RHN among all particles, so that this $Z_2$-odd RHN plays a role of DM. The
so-called minimal seesaw mechanism is implemented in this model with only two
$Z_2$-even RHNs. In this context, we investigate physics of the RHN DM,
focusing on the case that this DM particle communicates with the SM particles
through the U(1)$_X$ gauge boson ($Z^\prime$ boson). This "$Z^\prime$-portal
RHN DM" scenario is controlled by only three free parameters: the U(1)$_X$
gauge coupling ($\alpha_X$), the $Z^\prime$ boson mass ($m_{Z^\prime}$), and
the U(1)$_X$ charge of the SM Higgs doublet ($x_H$). We consider various
phenomenological constraints to identify a phenomenologically viable parameter
space. The most important constraints are the observed DM relic abundance and
the latest LHC Run-2 results on the search for a narrow resonance with the
di-lepton final state. We find that these are complementary with each other and
narrow the allowed parameter region, leading to the lower mass bound of
$m_{Z^\prime} \gtrsim 2.7$ TeV.


title:
Einstein's Equations for Spin $2$ Mass $0$ from Noether's Converse
  Hilbertian Assertion

abstract:
  An overlap between the general relativist and particle physicist views of
Einstein gravity is uncovered. Noether's 1918 paper developed Hilbert's and
Klein's reflections on the conservation laws. Energy-momentum is just a term
proportional to the field equations and a 'curl' term with identically zero
divergence. Noether proved a \emph{converse} "Hilbertian assertion": such
"improper" conservation laws imply a generally covariant action.
  Later and independently, particle physicists derived the nonlinear Einstein
equations assuming the absence of negative-energy degrees of freedom ("ghosts")
for stability, along with universal coupling: all energy-momentum including
gravity's serves as a source for gravity. Those assumptions (all but) imply
(for 0 graviton mass) that the energy-momentum is only a term proportional to
the field equations and a symmetric "curl," which implies the coalescence of
the flat background geometry and the gravitational potential into an effective
curved geometry. The flat metric, though useful in Rosenfeld's stress-energy
definition, disappears from the field equations. Thus the particle physics
derivation uses a reinvented Noetherian converse Hilbertian assertion in
Rosenfeld-tinged form.
  The Rosenfeld stress-energy is identically the canonical stress-energy plus a
Belinfante curl and terms proportional to the field equations, so the flat
metric is only a convenient mathematical trick without ontological commitment.
Neither generalized relativity of motion, nor the identity of gravity and
inertia, nor substantive general covariance is assumed. The more compelling
criterion of lacking ghosts yields substantive general covariance as an output.
Hence the particle physics derivation, though logically impressive, is neither
as novel nor as ontologically laden as it has seemed.


title: Weak Brill-Noether for rational surfaces

abstract:
  A moduli space of sheaves satisfies weak Brill-Noether if the general sheaf
in the moduli space has no cohomology. Goettsche and Hirschowitz prove that on
the projective plane every moduli space of Gieseker semistable sheaves of rank
at least two and Euler characteristic zero satisfies weak Brill-Noether. In
this paper, we give sufficient conditions for weak Brill-Noether to hold on
rational surfaces. We completely characterize Chern characters on Hirzebruch
surfaces for which weak Brill-Noether holds. We also prove that on a del Pezzo
surface of degree at least 4 weak Brill-Noether holds if the first Chern class
is nef.


title:
$k$-connectivity of inhomogeneous random key graphs with unreliable
  links

abstract:
  We consider secure and reliable connectivity in wireless sensor networks that
utilize a heterogeneous random key predistribution scheme. We model the
unreliability of wireless links by an on-off channel model that induces an
Erd\H{o}s-R\'enyi graph, while the heterogeneous scheme induces an
inhomogeneous random key graph. The overall network can thus be modeled by the
intersection of both graphs. We present conditions (in the form of zero-one
laws) on how to scale the parameters of the intersection model so that with
high probability i) all of its nodes are connected to at least $k$ other nodes;
i.e., the minimum node degree of the graph is no less than $k$ and ii) the
graph is $k$-connected, i.e., the graph remains connected even if any $k-1$
nodes leave the network. We also present numerical results to support these
conditions in the finite-node regime. Our results are shown to complement and
generalize several previous work in the literature.


title: From Dynamics to Contact and Symplectic Topology and Back

abstract:
  This is a light survey article about the origins of contact and symplectic
topology in dynamics and the more recent developments in the field. In lieu of
formulas, numerous anecdotes are given.


title: D-wave charmed and bottomed baryons from QCD sum rules

abstract:
  We study the $D$-wave charmed baryons of $SU(3)$ flavor $\mathbf{\bar3}_F$
using the method of QCD sum rule in the framework of heavy quark effective
theory (HQET). We find that the $\Lambda_c(2880)$, $\Xi_c(3055)$ and
$\Xi_c(3080)$ can be well described by the $D$-wave $SU(3)$ $\mathbf{\bar 3}_F$
charmed baryon multiplets of $J^P=3/2^+$ and $5/2^+$, which contain two
$\lambda$-mode orbital excitations, i.e., the $\Lambda_c(2880)$ has
$J^P=5/2^+$, and the $\Xi_c(3055)$ and $\Xi_c(3080)$ have $J^P = 3/2^+$ and
$5/2^+$, respectively. Our results also suggest that the $\Lambda_c(2880)$ has
a partner state, the $\Lambda_c(3/2^+)$ of $J^P=3/2^+$. Its mass is around
$2.81 ^{+0.33}_{-0.18}$ GeV, and the mass difference between it and the
$\Lambda_c(2880)$ is $28^{+45}_{-24}$ MeV. We also evaluate the masses of their
bottom partners.


title:
Effect of pulsed hollow electron-lens operation on the proton beam core
  in LHC

abstract:
  Collimation with hollow electron beams is currently one of the most promising
concepts for active halo control in the HL-LHC. In order to further increase
the diffusion rates for a fast halo removal as e.g. desired before the squeeze,
the electron lens (e-lens) can be operated in pulsed mode. In case of profile
imperfections in the electron beam the pulsing of the e-lens induces noise on
the proton beam which can, depending on the frequency content and strength,
lead to emittance growth. In order to study the sensitivity to the pulsing
pattern and the amplitude, a beam study (machine development MD) at the LHC has
been proposed for August 2016 and we present in this note the preparatory
simulations and estimates.


title: On classical upper bounds for slice genera

abstract:
  We introduce a new link invariant called the algebraic genus, which gives an
upper bound for the topological slice genus of links. In fact, the algebraic
genus is an upper bound for another version of the slice genus proposed here:
the minimal genus of a surface in the four-ball whose complement has infinite
cyclic fundamental group. We characterize the algebraic genus in terms of
cobordisms in three-space, and explore the connections to other knot invariants
related to the Seifert form, the Blanchfield form, knot genera and unknotting.
Employing Casson-Gordon invariants, we discuss the algebraic genus as a
candidate for the optimal upper bound for the topological slice genus that is
determined by the S-equivalence class of Seifert matrices.


title: A simpler algorithm to mark the unknown eigenstates

abstract:
  For an unknown eigenstate $|\psi\rangle$ of a unitary operator $U$, suppose
we have an estimate of the corresponding eigenvalue which is separated from all
other eigenvalues by a minimum gap of magnitude $\Delta$. In the
eigenstate-marking problem (EMP), the goal is to implement a selective phase
transformation of the $|\psi\rangle$ state (known as \emph{marking} the
$|\psi\rangle$ state in the language of the quantum search algorithms). The EMP
finds important applications in the construction of several quantum algorithms.
The best known algorithm for the EMP combines the ideas of the phase estimation
algorithm and the majority-voting. It uses $\Theta(\frac{1}{\Delta}\ln
\frac{1}{\epsilon})$ applications of $U$ where $\epsilon$ is the tolerable
error. It needs $\Theta\left(\ln \frac{1}{\Delta}\right)$ ancilla qubits for
the phase estimation and another $\Theta\left(\ln \frac{1}{\epsilon}\right)$
ancilla qubits for the majority-voting.
  In this paper, we show that the majority-voting is not a crucial requirement
for the EMP and the same purpose can also be achieved using the fixed-point
quantum search algorithm which does not need any ancilla qubits. In the case of
majority-voting, these ancilla qubits were needed to do controlled
transformations which are harder to implement physically. Using fixed-point
quantum search, we get rid off these $\Theta\left(\ln
\frac{1}{\epsilon}\right)$ ancilla qubits and same number of controlled
transformations. Thus we get a much simpler algorithm for marking the unknown
eigenstates. However, the required number of applications of $U$ increases by
the factor of $\Theta \left(\ln \frac{1}{\epsilon}\right)$. This tradeoff can
be beneficial in typical situations where spatial resources are more
constrained or where the controlled transformations are very expensive.


title: Spectral diffusion and scaling of many-body delocalization transitions

abstract:
  We analyze the role of spectral diffusion in the problem of many-body
delocalization in quantum dots and in extended systems. The spectral diffusion
parametrically enhances delocalization, modifying the scaling of the
delocalization threshold with the interaction coupling constant.


title:
Mechanical Novel: Crowdsourcing Complex Work through Reflection and
  Revision

abstract:
  Crowdsourcing systems accomplish large tasks with scale and speed by breaking
work down into independent parts. However, many types of complex creative work,
such as fiction writing, have remained out of reach for crowds because work is
tightly interdependent: changing one part of a story may trigger changes to the
overall plot and vice versa. Taking inspiration from how expert authors write,
we propose a technique for achieving interdependent complex goals with crowds.
With this technique, the crowd loops between reflection, to select a high-level
goal, and revision, to decompose that goal into low-level, actionable tasks. We
embody this approach in Mechanical Novel, a system that crowdsources short
fiction stories on Amazon Mechanical Turk. In a field experiment, Mechanical
Novel resulted in higher-quality stories than an iterative crowdsourcing
workflow. Our findings suggest that orienting crowd work around high-level
goals may enable workers to coordinate their effort to accomplish complex work.


title: Unsupervised Pretraining for Sequence to Sequence Learning

abstract:
  This work presents a general unsupervised learning method to improve the
accuracy of sequence to sequence (seq2seq) models. In our method, the weights
of the encoder and decoder of a seq2seq model are initialized with the
pretrained weights of two language models and then fine-tuned with labeled
data. We apply this method to challenging benchmarks in machine translation and
abstractive summarization and find that it significantly improves the
subsequent supervised models. Our main result is that pretraining improves the
generalization of seq2seq models. We achieve state-of-the art results on the
WMT English$\rightarrow$German task, surpassing a range of methods using both
phrase-based machine translation and neural machine translation. Our method
achieves a significant improvement of 1.3 BLEU from the previous best models on
both WMT'14 and WMT'15 English$\rightarrow$German. We also conduct human
evaluations on abstractive summarization and find that our method outperforms a
purely supervised learning baseline in a statistically significant manner.


title: Controlling friction in a manganite surface by resistive switching

abstract:
  We report a significant change in friction of a $\rm La_{0.55}Ca_{0.45}MnO_3$
thin film measured as a function of the materials resistive state under
ultrahigh vacuum conditions at room temperature by friction force microscopy.
While friction is high in the insulating state, it clearly changes to lower
values if the probed local region is switched to the conducting state via
nanoscale resistance switching. Thus we demonstrate active control of friction
without having to change the temperature or pressure. Upon switching back to an
insulating state the friction increases again. The results are discussed in the
framework of electronic friction effects and electrostatic interactions.


title: Generalize Heisenberg Groups and Self-Duality

abstract:
  This paper compares two generalizations of Heisenberg groups and studies
their connection to one of the major open problems in the field of locally
compact abelian groups, namely the description of the self-dual locally compact
abelian groups ([12]). The first generalization is presented by the so called
generalized Heisenberg groups $\mathbb{H}(\omega)$, defined in analogy with the
classical Heisenberg group and the second one is inspired by the construction
proposed by Mumford in [16] and named after him as Weyl-Mumford groups (WM
groups). These two families can be defined also in the framework of topological
groups. We investigate the relationship between locally compact WM groups,
locally compact Generalized Heisenberg with center isomorphic to $\mathbb{T}$
and symplectic self-dualities.


title: Nonclassical Berry-Esseen inequalities and accuracy of the bootstrap

abstract:
  We study accuracy of bootstrap procedures for estimation of quantiles of a
smooth function of a sum of independent sub-Gaussian random vectors. We
establish higher-order approximation bounds with error terms depending on a
sample size and a dimension explicitly. These results lead to improvements of
accuracy of a weighted bootstrap procedure for general log-likelihood ratio
statistics. The key element of our proofs of the bootstrap accuracy is a
multivariate higher-order Berry-Esseen inequality. We consider a problem of
approximation of distributions of two sums of zero mean independent random
vectors, such that summands with the same indices have equal moments up to at
least the second order. The derived approximation bound is uniform on the sets
of all Euclidean balls. The presented approach extends classical Berry-Esseen
type inequalities to higher-order approximation bounds. The theoretical results
are illustrated with numerical experiments.