title: Perspective on the cosmic-ray electron spectrum above TeV

abstract:
  The AMS-02 has measured the cosmic ray electron (plus positron) spectrum up
to ~TeV with an unprecedent precision. The spectrum can be well described by a
power law without any obvious features above 10 GeV. The satellite instrument
Dark Matter Particle Explorer (DAMPE), which was launched a year ago, will
measure the electron spectrum up to 10 TeV with a high energy resolution. The
cosmic electrons beyond TeV may be attributed to few local cosmic ray sources,
such as supernova remnants. Therefore, spectral features, such as cutoff and
bumps, can be expected at high energies. In this work we give a careful study
on the perspective of the electron spectrum beyond TeV. We first examine our
astrophysical source models on the latest leptonic data of AMS-02 to give a
self-consistent picture. Then we focus on the discussion about the candidate
sources which could be electron contributors above TeV. Depending on the
properties of the local sources (especially on the nature of Vela), DAMPE may
detect interesting features in the electron spectrum above TeV in the future.


title: Geometric and viscosity solutions for the Cauchy Problem of first Order

abstract:
  There are two kinds of solutions of the Cauchy problem of first order, the
viscosity solution and the more geometric minimax solution and in general they
are different. The aim of this article is to show how they are related:
iterating the minimax procedure during shorter and shorter time intervals one
approaches the viscosity solution. This can be considered as an extension to
the contact framework of the result of Q.Wei in the symplectic case.


title: Extreme statistics of non-intersecting Brownian paths

abstract:
  We consider finite collections of $N$ non-intersecting Brownian paths on the
line and on the half-line with both absorbing and reflecting boundary
conditions (corresponding to Brownian excursions and reflected Brownian
motions) and compute in each case the joint distribution of the maximal height
of the top path and the location at which this maximum is attained. The
resulting formulas are analogous to the ones obtained in [MFQR13] for the joint
distribution of $\mathcal{M}={\rm
max}_{x\in\mathbb{R}}\{\mathcal{A}_2(x)-x^2\}$ and $\mathcal{T}={\rm
argmax}_{x\in\mathbb{R}}\{\mathcal{A}_2(x)-x^2\}$, where $\mathcal{A}_2$ is the
Airy$_2$ process, and we use them to show that in the three cases the joint
distribution converges, as $N\to\infty$, to the joint distribution of
$\mathcal{M}$ and $\mathcal{T}$. In the case of non-intersecting Brownian
bridges on the line, we also establish small deviation inequalities for the
argmax which match the tail behavior of $\mathcal{T}$. Our proofs are based on
the method introduced in [CQR13,BCR15] for obtaining formulas for the
probability that the top line of these line ensembles stays below a given
curve, which are given in terms of the Fredholm determinant of certain
"path-integral" kernels.


title: Integrating out resonances in strongly-coupled electroweak scenarios

abstract:
  Accepting that there is a mass gap above the electroweak scale, the
Electroweak Effective Theory (EWET) is an appropriate tool to describe this
situation. Since the EWET couplings contain information on the unknown
high-energy dynamics, we consider a generic strongly-coupled scenario of
electroweak symmetry breaking, where the known particle fields are coupled to
heavier states. Then, and by integrating out these heavy fields, we study the
tracks of the lightest resonances into the couplings. The determination of the
low-energy couplings (LECs) in terms of resonance parameters can be made more
precise by considering a proper short-distance behaviour on the Lagrangian with
heavy states, since the number of resonance couplings is then reduced. Notice
that we adopt a generic non-linear realization of the electroweak symmetry
breaking with a singlet Higgs.


title: Scheduling of EV Battery Swapping, II: Distributed Solutions

abstract:
  In Part I of this paper we formulate an optimal scheduling problem for
battery swapping that assigns to each electric vehicle (EV) a best station to
swap its depleted battery based on its current location and state of charge.
The schedule aims to minimize a weighted sum of total travel distance and
generation cost over both station assignments and power flow variables, subject
to EV range constraints, grid operational constraints and AC power flow
equations. We propose there a centralized solution based on the second-order
cone programming (SOCP) relaxation of optimal power flow (OPF) and generalized
Benders decomposition that is suitable when global information is available. In
this paper we propose two distributed solutions based on the alternating
direction method of multipliers (ADMM) and dual decomposition respectively that
are suitable for cases where the distribution grid, battery stations and EVs
are managed by separate entities. Our algorithms allow these entities to make
individual decisions but coordinate through privacy-preserving information
exchanges to jointly solve an approximate version of the joint battery swapping
scheduling and OPF problem. We evaluate our algorithms through simulations.


title:
Configuration Spaces of Equal Spheres Touching a Given Sphere: The
  Twelve Spheres Problem

abstract:
  The problem of twelve spheres is to understand, as a function of $r \in
(0,r_{max}(12)]$, the configuration space of $12$ non-overlapping equal spheres
of radius $r$ touching a central unit sphere. It considers to what extent, and
in what fashion, touching spheres can be varied, subject to the constraint of
always touching the central sphere. Such constrained motion problems are of
interest in physics and materials science, and the problem involves topology
and geometry. This paper reviews the history of work on this problem, presents
some new results, and formulates some conjectures. It also presents general
results on configuration spaces of $N$ spheres of radius $r$ touching a central
unit sphere, with emphasis on $3 \le N \le 14$. The problem of determining the
maximal radius $r_{max}(N)$ is a version of the Tammes problem, to which
L\'aszl\'o Fejes T\'oth made significant contributions.


title:
Asteroseismology of ZZ Ceti stars with fully evolutionary white dwarf
  models: I. The impact of the uncertainties from prior evolution on the period
  spectrum

abstract:
  ZZ Ceti stars are pulsating white dwarfs with a carbon-oxygen core build up
during the core helium burning and thermally pulsing Asymptotic Giant Branch
phases. Through the interpretation of their pulsation periods by means of
asteroseismology, details about their origin and evolution can be inferred. The
whole pulsation spectrum exhibited by ZZ Ceti stars strongly depends on the
inner chemical structure. At present, there are several processes affecting the
chemical profiles that are still not accurately determined. We present a study
of the impact of the current uncertainties of the white dwarf formation and
evolution on the expected pulsation properties of ZZ Ceti stars. Our analysis
is based on a set of carbon-oxygen core white dwarf models with masses $0.548$
and $0.837 M_{\sun}$ derived from full evolutionary computations from the ZAMS
to the ZZ Ceti domain. We have considered models in which we varied the number
of thermal pulses, the amount of overshooting, and the
$^{12}$C$(\alpha,\gamma)^{16}$O reaction rate within their uncertainties. We
explore the impact of these major uncertainties in prior evolution on the
chemical structure and the expected pulsation spectrum. We find that these
uncertainties yield significant changes in the $g$-mode pulsation periods. We
conclude that the uncertainties in the white dwarf progenitor evolution should
be be taken into account in detailed asterseismological analysis of these
pulsating stars.


title: Monochromatic trees in random graphs

abstract:
  Bal and DeBiasio [Partitioning random graphs into monochromatic components,
Electron. J. Combin. 24 (2017), Paper 1.18] put forward a conjecture concerning
the threshold for the following Ramsey-type property for graphs $G$: every
$k$-colouring of the edge set of $G$ yields $k$ pairwise vertex disjoint
monochromatic trees that partition the whole vertex set of $G$. We determine
the threshold for this property for two colours.


title: A Generalized Construction of Calabi-Yau Models and Mirror Symmetry

abstract:
  We extend the construction of Calabi-Yau manifolds to hypersurfaces in
non-Fano toric varieties, requiring the use of certain Laurent defining
polynomials, and explore the phases of the corresponding gauged linear sigma
models. The associated non-reflexive and non-convex polytopes provide a
generalization of Batyrev's original work, allowing us to construct novel pairs
of mirror models. We showcase our proposal for this generalization by examining
Calabi-Yau hypersurfaces in Hirzebruch n-folds, focusing on n=3,4 sequences,
and outline the more general class of so-defined geometries.


title: Stochastic phenomena in a fiber Raman amplifier

abstract:
  The interplay of such cornerstones of modern nonlinear fiber optics as a
nonlinearity, stochasticity and polarization leads to variety of the noise
induced instabilities including polarization attraction and escape phenomena
harnessing of which is a key to unlocking the fiber optic systems
specifications required in high resolution spectroscopy, metrology, biomedicine
and telecommunications. Here, by using direct stochastic modeling, the mapping
of interplay of the Raman scattering-based nonlinearity, the random
birefringence of a fiber, and the pump-to-signal intensity noise transfer has
been done in terms of the fiber Raman amplifier parameters, namely polarization
mode dispersion, the relative intensity noise of the pump laser, fiber length,
and the signal power. The obtained results reveal conditions for emergence of
the random birefringence-induced resonance-like enhancement of the gain
fluctuations (stochastic anti-resonance) accompanied by pulse broadening and
rare events in the form of low power output signals having probability heavily
deviated from the Gaussian distribution.


title:
Opportunistic Scheduling for Network Coded Data in Wireless Multicast
  Networks

abstract:
  In this paper queue stability in a single-hop wireless multicast networks
over erasure channels is analyzed. First, a queuing model consisting of several
sub-queues is introduced. Under the queueing stability constraint, we adopt
Lyapunov optimization model and define decision variables to derive a network
coding based packet scheduling algorithm, which has significantly less
complexity and shorter queue size compared with the existing solutions.
Further, the proposed algorithm is modified to meet the requirements of
time-critical data. Finally, the simulation results verify the effectiveness of
our proposed algorithm.


title: Euler Characteristic of Springer fibers

abstract:
  For Weyl groups of classical types, we present formulas to calculate the
restriction of Springer representations to a maximal parabolic subgroup of the
same type. As a result, we give recursive formulas for Euler characteristics of
Springer fibers for classical types. We also give tables of those for
exceptional types.


title:
Potential kernels, probabilities of hitting a ball, harmonic functions
  and the boundary Harnack inequality for unimodal L\'evy processes

abstract:
  In the first part of this article, we prove two-sided estimates of hitting
probabilities of balls, the potential kernel and the Green function for a ball
for general isotropic unimodal L\'evy processes. Our bounds are sharp under the
absence of the Gaussian component and a mild regularity condition on the
density of the L\'{e}vy measure: its radial profile needs to satisfy a
scaling-type condition, which is equivalent to $O$-regular variation at zero
and at infinity with lower indices greater than $-d - 2$. We also prove a
supremum estimate and a regularity result for functions harmonic with respect
to a general isotropic unimodal L\'evy process.
  In the second part we apply the recent results on the boundary Harnack
inequality and Martin representation of harmonic functions for the class of
isotropic unimodal L\'evy processes characterised by a localised version of the
scaling-type condition mentioned above. As a sample application, we provide
sharp two-sided estimates of the Green function of a half-space.
  Our results are expressed in terms of Pruitt's functions $K(r)$ and $L(r)$,
measuring local activity and the amount of large jumps of the L\'evy process,
respectively.


title:
Influential Node Detection in Implicit Social Networks using Multi-task
  Gaussian Copula Models

abstract:
  Influential node detection is a central research topic in social network
analysis. Many existing methods rely on the assumption that the network
structure is completely known \textit{a priori}. However, in many applications,
network structure is unavailable to explain the underlying information
diffusion phenomenon. To address the challenge of information diffusion
analysis with incomplete knowledge of network structure, we develop a
multi-task low rank linear influence model. By exploiting the relationships
between contagions, our approach can simultaneously predict the volume (i.e.
time series prediction) for each contagion (or topic) and automatically
identify the most influential nodes for each contagion. The proposed model is
validated using synthetic data and an ISIS twitter dataset. In addition to
improving the volume prediction performance significantly, we show that the
proposed approach can reliably infer the most influential users for specific
contagions.


title: J/psi+Z production at the LHC

abstract:
  We briefly review recent results which we have obtained in the study of
J/psi+Z production at the LHC. Considering our NLO computation in the Colour
Evaporation Model (CEM) as an upper theory limit for the
single-parton-scattering contributions, we claim that the existing data set
from ATLAS points at a dominant double-parton-scattering contribution with an
effective cross section smaller than that for jet-related observables. As a
side product of our analysis, we have computed, for the first time, the
one-loop QCD corrections to the J/psi P_T-differential cross section in the
CEM.


title:
Stone-Wales defects in nitrogen-doped C$_{20}$ fullerenes: Insight from
  $\textit{ab initio}$ calculations

abstract:
  Density functional theory is applied to study the mechanism of the
Stone-Wales defect formation in pure and nitrogen-doped dodecahedral C$_{20}$
fullerenes. The molecular structures of initial and defected cages as well as
transition states dividing them are obtained. Depending on the number of
nitrogen atoms and their relative position in the cage, Stone-Wales defect is
formed through the single additional intermediate state or directly. The
activation energy barrier of the defect formation reduces from 4.93 eV in pure
C$_{20}$ to 2.98 eV in single-doped C$_{19}$N, and reaches $\sim$ 2 eV under
further doping. All nitrogen-doped fullerenes considered possess high kinetic
stability at room temperature. However, they become much less stable at
temperatures of about 750 K that are typical for the fullerene annealing
process.


title: Computing $J$-ideals of a matrix over a principal ideal domain

abstract:
  Given a square matrix $B$ over a principal ideal domain $D$ and an ideal $J$
of $D$, the $J$-ideal of $B$ consists of the polynomials $f\in D[X]$ such that
all entries of $f(B)$ are in $J$. It has been shown that in order to determine
all $J$-ideals of $B$ it suffices to compute a generating set of the
$(p^t)$-ideal of $B$ for finitely many prime powers $p^t$. Moreover, it is
known that $(p^t)$-ideals are generated by polynomials of the form
$p^{t-s}\nu_s$ where $\nu_s$ is a monic polynomial of minimal degree in the
$(p^s)$-ideal of $B$ for some $s\le t$. However, except for the case of
diagonal matrices, it was not known how to determine these polynomials
explicitly. We present an algorithm which allows to compute the polynomials
$\nu_s$ for general square matrices. Exploiting one of McCoy's theorems we
first compute some set of generators of the $(p^s)$-ideal of $B$ which then can
be used to determine $\nu_s$. This algorithmic computation significantly
extends our understanding of the $J$-ideals of $B$.


title:
Capacity limit for faster-than-Nyquist non-orthogonal frequency-division
  multiplexing signaling

abstract:
  Faster-than-Nyquist (FTN) signal achieves higher spectral efficiency and
capacity compared to Nyquist signal due to its smaller pulse interval or
narrower subcarrier spacing. Shannon limit typically defines the upper-limit
capacity of Nyquist signal. To the best of our knowledge, the mathematical
expression for the capacity limit of FTN non-orthogonal frequency-division
multiplexing (NOFDM) signal is first demonstrated in this paper. The
mathematical expression shows that FTN NOFDM signal has the potential to
achieve a higher capacity limit compared to Nyquist signal. In this paper, we
demonstrate the principle of FTN NOFDM by taking fractional cosine
transform-based NOFDM (FrCT-NOFDM) for instance. FrCT-NOFDM is first proposed
and implemented by both simulation and experiment. When the bandwidth
compression factor $\alpha$ is set to $0.8$ in FrCT-NOFDM, the subcarrier
spacing is equal to $40\%$ of the symbol rate per subcarrier, thus the
transmission rate is about $25\%$ faster than Nyquist rate. FTN NOFDM with
higher capacity would be promising in the future communication systems,
especially in the bandwidth-limited applications.


title: Superposition and time delay are incompatible between them

abstract:
  We analyse the properties of wave functions $\psi(x,t;y,s)$ that depend at
once on two time-position vectors $(x,t)$ and $(y,s)$ with different time
entries $t\neq{s}$. In particular, we prove that the existence of such wave
functions is indeed incompatible with the superposition property and the
technique of separation of variables.


title: A splitting approach for freezing waves

abstract:
  We present a numerical method which is able to approximate traveling waves
(e.g. viscous profiles) in systems with hyperbolic and parabolic parts by a
direct long-time forward simulation. A difficulty with long-time simulations of
traveling waves is that the solution leaves any bounded computational domain in
finite time. To handle this problem one should go into a suitable co-moving
frame. Since the velocity of the wave is typically unknown, we use the method
of freezing [Beyn, Th\"ummler 2004], see also [Beyn, Otten, Rottmann-Matthes
2014], which transforms the original partial differential equation (PDE) into a
partial differential algebraic equation (PDAE) and calculates a suitable
co-moving frame on the fly. The efficient numerical approximation of this
freezing PDAE is a challenging problem and we introduce a new numerical
discretization, suitable for problems that consist of hyperbolic conservation
laws which are (nonlinearly) coupled to parabolic equations. The idea of our
scheme is to use the operator splitting approach. The benefit of splitting
methods in this context lies in the possibility to solve hyperbolic and
parabolic parts with different numerical algorithms.
  We test our method at the (viscous) Burgers' equation. Numerical experiments
show linear and quadratic convergence rates for the approximation of the
numerical steady state obtained by a long-time simulation for Lie- and
Strang-splitting, respectively. Due to these affirmative results we expect our
scheme to be suitable also for freezing waves in hyperbolic-parabolic coupled
PDEs.


title: Cognitive hierarchy theory and two-person games

abstract:
  The outcome of many social and economic interactions, such as stock-market
transactions, is strongly determined by the predictions that agents make about
the behavior of other individuals. Cognitive Hierarchy Theory provides a
framework to model the consequences of forecasting accuracy that has proven to
fit data from certain types of game theory experiments, such as Keynesian
Beauty Contests and Entry Games. Here, we focus on symmetric
two-players-two-actions games and establish an algorithm to find the players'
strategies according to the Cognitive Hierarchy Approach. We show that the
Snowdrift Game exhibits a pattern of behavior whose complexity grows as the
cognitive levels of players increases. In addition to finding the solutions up
to the third cognitive level, we demonstrate, in this theoretical frame, two
new properties of snowdrift games: i) any snowdrift game can be characterized
by only a parameter -- its class, ii) they are anti-symmetric with respect to
the diagonal of the pay-off's space. Finally, we propose a model based on an
evolutionary dynamics that captures the main features of the Cognitive
Hierarchy Theory.


title: Testing local Lorentz invariance with short-range gravity

abstract:
  The Newton limit of gravity is studied in the presence of Lorentz-violating
gravitational operators of arbitrary mass dimension. The linearized modified
Einstein equations are obtained and the perturbative solutions are constructed
and characterized. We develop a formalism for data analysis in laboratory
experiments testing gravity at short range and demonstrate that these tests
provide unique sensitivity to deviations from local Lorentz invariance.


title:
Sync-DRAW: Automatic Video Generation using Deep Recurrent Attentive
  Architectures

abstract:
  This paper introduces a novel approach for generating videos called
Synchronized Deep Recurrent Attentive Writer (Sync-DRAW). Sync-DRAW can also
perform text-to-video generation which, to the best of our knowledge, makes it
the first approach of its kind. It combines a Variational Autoencoder~(VAE)
with a Recurrent Attention Mechanism in a novel manner to create a temporally
dependent sequence of frames that are gradually formed over time. The recurrent
attention mechanism in Sync-DRAW attends to each individual frame of the video
in sychronization, while the VAE learns a latent distribution for the entire
video at the global level. Our experiments with Bouncing MNIST, KTH and UCF-101
suggest that Sync-DRAW is efficient in learning the spatial and temporal
information of the videos and generates frames with high structural integrity,
and can generate videos from simple captions on these datasets. (Accepted as
oral paper in ACM-Multimedia 2017)


title: Removal Lemmas with Polynomial Bounds

abstract:
  A common theme in many extremal problems in graph theory is the relation
between local and global properties of graphs. One of the most celebrated
results of this type is the Ruzsa-Szemer\'edi triangle removal lemma, which
states that if a graph is $\varepsilon$-far from being triangle free, then most
subsets of vertices of size $C(\varepsilon)$ are not triangle free.
Unfortunately, the best known upper bound on $C(\varepsilon)$ is given by a
tower-type function, and it is known that $C(\varepsilon)$ is not polynomial in
$\varepsilon^{-1}$. The triangle removal lemma has been extended to many other
graph properties, and for some of them the corresponding function
$C(\varepsilon)$ is polynomial. This raised the natural question, posed by
Goldreich in 2005 and more recently by Alon and Fox, of characterizing the
properties for which one can prove removal lemmas with polynomial bounds.
  Our main results in this paper are new sufficient and necessary criteria for
guaranteeing that a graph property admits a removal lemma with a polynomial
bound. Although both are simple combinatorial criteria, they imply almost all
prior positive and negative results of this type. Moreover, our new sufficient
conditions allow us to obtain polynomially bounded removal lemmas for many
properties for which the previously known bounds were of tower-type. In
particular, we show that every {\em semi-algebraic} graph property admits a
polynomially bounded removal lemma. This confirms a conjecture of Alon.


title: Memory Controller Design Under Cloud Workloads

abstract:
  This work studies the behavior of state-of-the-art memory controller designs
when executing scale-out workloads. It considers memory scheduling techniques,
memory page management policies, the number of memory channels, and the address
mapping scheme used. Experimental measurements demonstrate: 1)~Several recently
proposed memory scheduling policies are not a good match for these scale-out
workloads. 2)~The relatively simple First-Ready-First-Come-First-Served
(FR-FCFS) policy performs consistently better, and 3)~for most of the studied
workloads, the even simpler First-Come-First-Served scheduling policy is within
1\% of FR-FCFS. 4)~Increasing the number of memory channels offers negligible
performance benefits, e.g., performance improves by 1.7\% on average for
4-channels vs. 1-channel. 5)~77\%-90\% of DRAM rows activations are accessed
only once before closure. These observation can guide future development and
optimization of memory controllers for scale-out workloads.


title: Toric Geometry of the Regular Convex Polyhedra

abstract:
  In this article, we describe symplectic and complex toric spaces associated
to the five regular convex polyhedra. The regular tetrahedron and the cube are
rational and simple, the regular octahedron is not simple, the regular
dodecahedron is not rational and the regular icosahedron is neither simple nor
rational. We remark that the last two cases cannot be treated via standard
toric geometry.


title:
Research into the Potential to Adapt and Establish of the invasive Asian
  Tiger Mosquito Aedes (Stegomyia) albopictus (SKUSE)

abstract:
  There is general agreement that the former (breeding) macrohabitat of the
Asian tiger mosquito, Aedes albopictus (synonym: Stegomyia albopicta) has been
described as phytotelmata in the forested areas of Southeast Asia, however,
this has changed in the last four decades as it has adapted to more urban areas
and antrotelmata. Capable of producing eggs with a certain dry resistance as
well as cold hardiness, populations of Ae. albopictus became distributed around
the globe. The invasion of the Ae. albopictus across all over the world is
thought to be the most rapid spread of any insect species in the last four
decades in tropical, subtropical and temperate climate zones. In addition, Ae.
albopictus is a potential vector for at least 27 viruses as well as for several
parasites and plays a major role in the global transmission of dengue virus and
chikungunya virus; and its contribution to the rapid spread of zika virus is
currently under investigation. Therefore, this species is considered a serious
threat to public health worldwide. This work broaches the issue of three
investigations about the potential to adapt and establish stabile populations
of the invasive Asian tiger mosquito Ae. albopictus. As a result of these
investigations, a high potential for this species to become a threat to public
health in many more countries, especially in temperate climatic zones, can be
seen. Due to the fact on the one hand that Ae. albopictus can gain fitness
advantages due to misapplied vector control measures and on the other hand of
the high epigenetically adaptation potential, it is in summary recommended to
focus further research on the development of vaccinations for viruses and other
pathogens. By doing so, citizens will be protected without putting ecosystems
and their services in danger and it is the even more economic solution.


title: The Computational Complexity of Portal and Other 3D Video Games

abstract:
  We classify the computational complexity of the popular video games Portal
and Portal 2. We isolate individual mechanics of the game and prove
NP-hardness, PSPACE-completeness, or (pseudo)polynomiality depending on the
specific game mechanics allowed. One of our proofs generalizes to prove
NP-hardness of many other video games such as Half-Life 2, Halo, Doom, Elder
Scrolls, Fallout, Grand Theft Auto, Left 4 Dead, Mass Effect, Deus Ex, Metal
Gear Solid, and Resident Evil.
  These results build on the established literature on the complexity of video
games.


title: A derived category approach to Kempf's vanishing theorem

abstract:
  We give a proof of the Andersen-Haboush identity that implies Kempf's
vanishing theorem. Our argument is based on the structure of derived categories
of coherent sheaves on flag varieties over $\mathbb Z$.


title: Magnetic Coordinate Systems

abstract:
  Geospace phenomena such as the aurora, plasma motion, ionospheric currents
and associated magnetic field disturbances are highly organized by Earth's main
magnetic field. This is due to the fact that the charged particles that
comprise space plasma can move almost freely along magnetic field lines, but
not across them. For this reason it is sensible to present such phenomena
relative to Earth's magnetic field. A large variety of magnetic coordinate
systems exist, designed for different purposes and regions, ranging from the
magnetopause to the ionosphere. In this paper we review the most common
magnetic coordinate systems and describe how they are defined, where they are
used, and how to convert between them. The definitions are presented based on
the spherical harmonic expansion coefficients of the International Geomagnetic
Reference Field (IGRF) and, in some of the coordinate systems, the position of
the Sun which we show how to calculate from the time and date. The most
detailed coordinate systems take the full IGRF into account and define magnetic
latitude and longitude such that they are constant along field lines. These
coordinate systems, which are useful at ionospheric altitudes, are
non-orthogonal. We show how to handle vectors and vector calculus in such
coordinates, and discuss how systematic errors may appear if this is not done
correctly.


title:
Measurement of light and charge yield of low-energy electronic recoils
  in liquid xenon

abstract:
  The dependence of the light and charge yield of liquid xenon on the applied
electric field and recoil energy is important for dark matter detectors using
liquid xenon time projections chambers. Few measurements have been made of this
field dependence at recoil energies less than 10 keV. In this paper we present
results of such measurements using a specialized detector. Recoil energies are
determined via the Compton coincidence technique at four drift fields relevant
for liquid xenon dark matter detectors: 0.19, 0.48, 1.02, and 2.32 kV/cm. Mean
recoil energies down to 1 keV were measured with unprecedented precision. We
find that the charge and light yield are anti-correlated above 3 keV, and that
the field dependence becomes negligible below 6 keV. However, below 3 keV we
find a charge yield significantly higher than expectation and a reconstructed
energy deviating from linearity.


title:
Gravitational Threshold Corrections in Non-Supersymmetric Heterotic
  Strings

abstract:
  We compute one-loop quantum corrections to gravitational couplings in the
effective action of four-dimensional heterotic strings where supersymmetry is
spontaneously broken by Scherk-Schwarz fluxes. We show that in both heterotic
and type II theories of this class, no moduli dependent corrections to the
Planck mass are generated. We explicitly compute the one-loop corrections to
the $\mathcal R^2$ coupling and find that, despite the absence of
supersymmetry, its contributions may still be organised into representations of
subgroups of the modular group, and admit a universal form, determined uniquely
by the multiplicities of the ground states of the theory. Moreover, similarly
to the case of gauge couplings, also the gravitational sector may become
strongly coupled in models which dynamically induce large volume for the extra
dimensions.


title:
On the critical branching random walk I: Branching capacity and visiting
  probability

abstract:
  We extend the theory of discrete capacity to critical branching random walk.
We introduce branching capacity for any finite subset of $\Z^d, d\geq5$.
Analogous to the regular discrete capacity, branching capacity is closely
related to the asymptotics of the probability of visiting a fixed finite set by
a critical branching random walk starting from a distant point and the
conditional distribution of the hitting point.


title: An effective universality theorem for the Riemann zeta-function

abstract:
  Let $0<r<1/4$, and $f$ be a non-vanishing continuous function in $|z|\leq r$,
that is analytic in the interior. Voronin's universality theorem asserts that
translates of the Riemann zeta function $\zeta(3/4 + z + it)$ can approximate
$f$ uniformly in $|z| < r$ to any given precision $\varepsilon$, and moreover
that the set of such $t \in [0, T]$ has measure at least $c(\varepsilon) T$ for
some $c(\varepsilon) > 0$, once $T$ is large enough. This was refined by Bagchi
who showed that the measure of such $t \in [0,T]$ is $(c(\varepsilon) + o(1))
T$, for all but at most countably many $\varepsilon > 0$. Using a completely
different approach, we obtain the first effective version of Voronin's Theorem,
by showing that in the rate of convergence one can save a small power of the
logarithm of $T$. Our method is flexible, and can be generalized to other
$L$-functions in the $t$-aspect, as well as to families of $L$-functions in the
conductor aspect.


title:
Weak lensing magnification in the Dark Energy Survey Science
  Verification Data

abstract:
  In this paper the effect of weak lensing magnification on galaxy number
counts is studied by cross-correlating the positions of two galaxy samples,
separated by redshift, using data from the Dark Energy Survey Science
Verification dataset. The analysis is carried out for two
photometrically-selected galaxy samples, with mean photometric redshifts in the
$0.2 < z < 0.4$ and $0.7 < z < 1.0$ ranges, in the riz bands. A signal is
detected with a $3.5\sigma$ significance level in each of the bands tested, and
is compatible with the magnification predicted by the $\Lambda$CDM model. After
an extensive analysis, it cannot be attributed to any known systematic effect.
The detection of the magnification signal is robust to estimated uncertainties
in the outlier rate of the pho- tometric redshifts, but this will be an
important issue for use of photometric redshifts in magnification mesurements
from larger samples. In addition to the detection of the magnification signal,
a method to select the sample with the maximum signal-to-noise is proposed and
validated with data.


title: Low Energy Supergravity Revisited (I)

abstract:
  General forms of the K\"ahler and superpotenials that lead to consistent low
energy broken Supersymmetry originating from $N=1$ Supergravity have been
classified and used for model building since more than three decades. We point
out the incompleteness of this classification when hidden sector vacuum
expectation values are of the order of the Planck mass. Focusing in this paper
mainly on the case of minimal K\"ahler potential, we adopt a rigorous approach
that retrieves on the one hand the known forms, and demonstrate on the other
hand the existence of a whole set of new forms for the superpotential of which
we give a complete classification. The latter forms involve a new type of
chiral superfields having the unusual property of belonging neither to the
hidden sector nor to the conventional observable sector. Comparing the obtained
forms with the conventional ones, we argue how new possibilities for model
building can arise, and discuss the gravity mediation of soft as well as
additional hard (but parametrically small) Supersymmetry breaking, in the
presence of the new type of chiral superfields. In the simplest case, we study
the vacuum structure, characterize the masses and couplings of the scalar
components to the hidden and observable sectors and discuss briefly the
physical role they could play. In the generic case, we estimate the magnitude
and possible consequences of the hard breaking of Supersymmetry in terms of the
interplay between hidden and visible sectors mass scales.


title:
The observer-assisted method for adjusting hyper-parameters in deep
  learning algorithms

abstract:
  This paper presents a concept of a novel method for adjusting
hyper-parameters in Deep Learning (DL) algorithms. An external agent-observer
monitors a performance of a selected Deep Learning algorithm. The observer
learns to model the DL algorithm using a series of random experiments.
Consequently, it may be used for predicting a response of the DL algorithm in
terms of a selected quality measurement to a set of hyper-parameters. This
allows to construct an ensemble composed of a series of evaluators which
constitute an observer-assisted architecture. The architecture may be used to
gradually iterate towards to the best achievable quality score in tiny steps
governed by a unit of progress. The algorithm is stopped when the maximum
number of steps is reached or no further progress is made.


title:
Kinematics of Current Region Fragmentation in Semi-Inclusive Deeply
  Inelastic Scattering

abstract:
  Different kinematical regimes of semi-inclusive deeply inelastic scattering
(SIDIS) processes correspond to different underlying partonic pictures, and it
is important to understand the transition between them. This is particularly
the case when there is sensitivity to intrinsic transverse momentum, in which
case kinematical details can become especially important. We address the
question of how to identify the current fragmentation region --- the
kinematical regime where a factorization picture with fragmentation functions
is appropriate. We distinguish this from soft and target fragmentation regimes.
Our criteria are based on the kinematic regions used in derivations of
factorization theorems. We argue that, when hard scales are of order a few
GeVs, there is likely significant overlap between different rapidity regions
that are normally understood to be distinct. We thus comment on the need to
take this into account with more unified descriptions of SIDIS, which should
span all rapidities for the produced hadron. Finally, we propose general
criteria for estimating the proximity to the current region at large Q.


title: Linking Numbers in Three-Manifolds

abstract:
  Let $M$ be a connected, closed, oriented three-manifold and $K$, $L$ two
rationally null-homologous oriented simple closed curves in $M$. We give an
explicit algorithm for computing the linking number between $K$ and $L$ in
terms of a presentation of $M$ as an irregular dihedral $3$-fold cover of $S^3$
branched along a knot $\alpha\subset S^3$. Since every closed, oriented
three-manifold admits such a presentation, our results apply to all
(well-defined) linking numbers in all three-manifolds. Furthermore, ribbon
obstructions for a knot $\alpha$ can be derived from dihedral covers of
$\alpha$. The linking numbers we compute are necessary for evaluating one such
obstruction. This work is a step toward testing potential counter-examples to
the Slice-Ribbon Conjecture, among other applications.


title:
Comparing Apples and Oranges: Two Examples of the Limits of Statistical
  Inference, With an Application to Google Advertising Markets

abstract:
  We show how the classic Cramer-Rao bound limits how accurately one can
simultaneously estimate values of a large number of Google Ad campaigns (or
similarly limit the measurement rate of many confounding A/B tests).


title: Metal-Rich SX Phe stars in the Kepler Field

abstract:
  A spectroscopic and photometric analysis has been carried out for thirty-two
candidate SX_Phe variable blue straggler stars in the Kepler-field (Balona &
Nemec 2012). Radial velocities (RVs), space motions (U,V,W), projected rotation
velocities (v sin i), spectral types, and atmospheric characteristics (T_eff,
log g, [Fe/H], xi_t, zeta_RT, etc.) are presented for 30 of the 32 stars.
Although several stars are metal-weak with extreme halo orbits, the mean [Fe/H]
of the sample is near solar, thus the stars are more metal-rich than expected
for a typical sample of Pop.II stars, and more like halo metal-rich A-type
stars (Perry 1969). Two thirds of the stars are fast rotators with v sin i > 50
km/s, including four stars with v sin i > 200 km/s. Three of the stars have
(negative) RVs > 250 km/s, five have retrograde space motions, and 21 have
total speeds (relative to the LSR) > 400 km/s. All but one of the 30 stars have
positions in a Toomre diagram consistent with the kinematics of bona fide halo
stars (the exception being a thick-disk star). Observed Roemer time delays,
pulsation frequency modulations and light curves suggest that at least one
third of the stars are in binary (or triple) systems with orbital periods
ranging from 2.3 days to more than four years.


title: PCA from noisy, linearly reduced data: the diagonal case

abstract:
  Suppose we observe data of the form $Y_i = D_i (S_i + \varepsilon_i) \in
\mathbb{R}^p$ or $Y_i = D_i S_i + \varepsilon_i \in \mathbb{R}^p$,
$i=1,\ldots,n$, where $D_i \in \mathbb{R}^{p\times p}$ are known diagonal
matrices, $\varepsilon_i$ are noise, and we wish to perform principal component
analysis (PCA) on the unobserved signals $S_i \in \mathbb{R}^p$. The first
model arises in missing data problems, where the $D_i$ are binary. The second
model captures noisy deconvolution problems, where the $D_i$ are the Fourier
transforms of the convolution kernels. It is often reasonable to assume the
$S_i$ lie on an unknown low-dimensional linear space; however, because many
coordinates can be suppressed by the $D_i$, this low-dimensional structure can
be obscured.
  We introduce diagonally reduced spiked covariance models to capture this
setting. We characterize the behavior of the singular vectors and singular
values of the data matrix under high-dimensional asymptotics where
$n,p\to\infty$ such that $p/n\to\gamma>0$. Our results have the most general
assumptions to date even without diagonal reduction. Using them, we develop
optimal eigenvalue shrinkage methods for covariance matrix estimation and
optimal singular value shrinkage methods for data denoising.
  Finally, we characterize the error rates of the empirical Best Linear
Predictor (EBLP) denoisers. We show that, perhaps surprisingly, their optimal
tuning depends on whether we denoise in-sample or out-of-sample, but the
optimally tuned mean squared error is the same in the two cases.


title: Complexity Hierarchies and Higher-order Cons-free Term Rewriting

abstract:
  Constructor rewriting systems are said to be cons-free if, roughly,
constructor terms in the right-hand sides of rules are subterms of the
left-hand sides; the computational intuition is that rules cannot build new
data structures. In programming language research, cons-free languages have
been used to characterize hierarchies of computational complexity classes; in
term rewriting, cons-free first-order TRSs have been used to characterize the
class PTIME.
  We investigate cons-free higher-order term rewriting systems, the complexity
classes they characterize, and how these depend on the type order of the
systems. We prove that, for every K $\geq$ 1, left-linear cons-free systems
with type order K characterize E$^K$TIME if unrestricted evaluation is used
(i.e., the system does not have a fixed reduction strategy).
  The main difference with prior work in implicit complexity is that (i) our
results hold for non-orthogonal term rewriting systems with no assumptions on
reduction strategy, (ii) we consequently obtain much larger classes for each
type order (E$^K$TIME versus EXP$^{K-1}$TIME), and (iii) results for cons-free
term rewriting systems have previously only been obtained for K = 1, and with
additional syntactic restrictions besides cons-freeness and left-linearity.
  Our results are among the first implicit characterizations of the hierarchy E
= E$^1$TIME $\subsetneq$ E$^2$TIME $\subsetneq$ ... Our work confirms prior
results that having full non-determinism (via overlapping rules) does not
directly allow for characterization of non-deterministic complexity classes
like NE. We also show that non-determinism makes the classes characterized
highly sensitive to minor syntactic changes like admitting product types or
non-left-linear rules.


title:
Univariate log-concave density estimation with symmetry or modal
  constraints

abstract:
  We study nonparametric maximum likelihood estimation of a log-concave density
function $f_0$ which is known to satisfy further constraints, where either (a)
the mode $m$ of $f_0$ is known, or (b) $f_0$ is known to be symmetric about a
fixed point $m$. We develop asymptotic theory for both constrained log-concave
maximum likelihood estimators (MLE's), including consistency, global rates of
convergence, and local limit distribution theory. In both cases, we find the
MLE's pointwise limit distribution at $m$ (either the known mode or the known
center of symmetry) and at a point $x_0 \ne m$. Software to compute the
constrained estimators is available in the R package \verb+logcondens.mode+.
  The symmetry-constrained MLE is particularly useful in contexts of location
estimation. The mode-constrained MLE is useful for mode-regression. The
mode-constrained MLE can also be used to form a likelihood ratio test for the
location of the mode of $f_0$. These problems are studied in separate papers.
In particular, in a separate paper we show that, under a curvature assumption,
the likelihood ratio statistic for the location of the mode can be used for
hypothesis tests or confidence intervals that do not depend on either tuning
parameters or nuisance parameters.


title: An Artificial Agent for Robust Image Registration

abstract:
  3-D image registration, which involves aligning two or more images, is a
critical step in a variety of medical applications from diagnosis to therapy.
Image registration is commonly performed by optimizing an image matching metric
as a cost function. However, this task is challenging due to the non-convex
nature of the matching metric over the plausible registration parameter space
and insufficient approaches for a robust optimization. As a result, current
approaches are often customized to a specific problem and sensitive to image
quality and artifacts. In this paper, we propose a completely different
approach to image registration, inspired by how experts perform the task. We
first cast the image registration problem as a "strategy learning" process,
where the goal is to find the best sequence of motion actions (e.g. up, down,
etc.) that yields image alignment. Within this approach, an artificial agent is
learned, modeled using deep convolutional neural networks, with 3D raw image
data as the input, and the next optimal action as the output. To cope with the
dimensionality of the problem, we propose a greedy supervised approach for an
end-to-end training, coupled with attention-driven hierarchical strategy. The
resulting registration approach inherently encodes both a data-driven matching
metric and an optimal registration strategy (policy). We demonstrate, on two
3-D/3-D medical image registration examples with drastically different nature
of challenges, that the artificial agent outperforms several state-of-art
registration methods by a large margin in terms of both accuracy and
robustness.


title: Spins of prime ideals and the negative Pell equation $x^2 - 2py^2 = -1$

abstract:
  Let $p\equiv 1\bmod 4$ be a prime number. We use a number field variant of
Vinogradov's method to prove density results about the following four
arithmetic invariants: (i) $16$-rank of the class group $\mathrm{Cl}(-4p)$ of
the imaginary quadratic number field $\mathbb{Q}(\sqrt{-4p})$; (ii) $8$-rank of
the ordinary class group $\mathrm{Cl}(8p)$ of the real quadratic field
$\mathbb{Q}(\sqrt{8p})$; (iii) the solvability of the negative Pell equation
$x^2 - 2py^2 = -1$ over the integers; (iv) $2$-part of the
Tate-\v{S}afarevi\v{c} group of the congruent number elliptic curve $E_p: y^2 =
x^3-p^2x$. Our results are conditional on a standard conjecture about short
character sums.


title:
SLA Violation Prediction In Cloud Computing: A Machine Learning
  Perspective

abstract:
  Service level agreement (SLA) is an essential part of cloud systems to ensure
maximum availability of services for customers. With a violation of SLA, the
provider has to pay penalties. In this paper, we explore two machine learning
models: Naive Bayes and Random Forest Classifiers to predict SLA violations.
Since SLA violations are a rare event in the real world (~0.2 %), the
classification task becomes more challenging. In order to overcome these
challenges, we use several re-sampling methods. We find that random forests
with SMOTE-ENN re-sampling have the best performance among other methods with
the accuracy of 99.88 % and F_1 score of 0.9980.


title:
More than trees, do we need a complex perspective for sustainable forest
  management?

abstract:
  Forests are complex systems, and it is necessary to include this
characteristic in every forest definition, in order to consider the restriction
that this imposes in terms of prediction and control. This lost of
predictability and controllability should be incorporated in every
Environmental Impact Assessment or management program. We present two
case-studies located in Mexico and one in the US to illustrate three relevant
indicators of complexity. First, we introduce an informational framework to
measure the Zoquiapan forest systemic complexity. Then, we analyze complexity
changes among different types of forest and management systems, related with
spatial distributions, using data from a floristic study in the Montes Azules
National Park. Finally, we analyze time series of $CO_{2}$ fluctuations taken
from AMERIFLUX data bases. Our results show firstly that it is possible to
measure the systemic complexity of different forests, characteized by a
criticality state (1/f noise) which has been proposed as a finger print of
complexity. And secondly, that this characteristic can be used as a proxy of
their state of conservation, where the lowest complexity values are found in
perturbed areas showing the relevance of the concept and its measurement for
forest conservation and management.


title: Difference Hierarchies for $nT$ $\tau$-Functions

abstract:
  We introduce hierarchies of difference equations (referred to as
$nT$-systems) associated to the action of a (centrally extended, completed)
infinite matrix group $GL_{\infty}^{(n)}$ on $n$-component fermionic Fock
space. The solutions are given by matrix elements ($\tau$-functions) for this
action. We show that the $\tau$-functions of type $nT$ satisfy bilinear
equations of length $3,4,\dots,n+1$. The $2T$-system is, after a change of
variables, the usual $3$ term $T$-system of type $A$.
  Restriction from $GL_{\infty}^{(n)}$ to a subgroup isomorphic to the loop
group $LGL_{n}$, defines $nQ$-systems, studied earlier by the present authors
for $n=2,3$.


title:
Quantum actions on discrete quantum spaces and a generalization of
  Clifford's theory of representations

abstract:
  To any action of a compact quantum group on a von Neumann algebra which is a
direct sum of factors we associate an equivalence relation corresponding to the
partition of a space into orbits of the action. We show that in case all
factors are finite-dimensional (i.e. when the action is on a discrete quantum
space) the relation has finite orbits. We then apply this to generalize the
classical theory of Clifford, concerning the restrictions of representations to
normal subgroups, to the framework of quantum subgroups of discrete quantum
groups, itself extending the context of closed normal quantum subgroups of
compact quantum groups. Finally, a link is made between our equivalence
relation in question and another equivalence relation defined by R.Vergnioux.


title: Cospan construction of the graph category of Borisov and Manin

abstract:
  It is shown how the graph category of Borisov and Manin can be constructed
from (a variant of) the graph category of Joyal and Kock, essentially by
reversing the generic morphisms. More precisely, the morphisms in the
Borisov-Manin category are exhibited as cospans of reduced covers and
refinement morphisms.


title: UV dimensional reduction to two from group valued momenta

abstract:
  We describe a new model of deformed relativistic kinematics based on the
group manifold $U(1) \times SU(2)$ as a four-momentum space. We discuss the
action of the Lorentz group on such space and and illustrate the deformed
composition law for the group-valued momenta. Due to the geometric structure of
the group, the deformed kinematics is governed by {\it two} energy scales
$\lambda$ and $\kappa$. A relevant feature of the model is that it exhibits a
running spectral dimension $d_s$ with the characteristic short distance
reduction to $d_s =2$ found in most quantum gravity scenarios.


title: Generalized Wilson-Fisher critical points from the conformal OPE

abstract:
  We study possible smooth deformations of Generalized Free Conformal Field
Theories in arbitrary dimensions by exploiting the singularity structure of the
conformal blocks dictated by the null states. We derive in this way, at the
first non trivial order in the $\epsilon$-expansion, the anomalous dimensions
of an infinite class of scalar local operators, without using the equations of
motion. In the cases where other computational methods apply, the results
agree.


title:
Anderson localization for weakly interacting multi-particle models in
  the continuum

abstract:
  For the weakly interacting one-dimensional multi-particle Anderson model in
the continuum space of configurations, we prove the spectral exponential and
the strong dynamical localization. The results require the interaction
amplitude to be sufficiently small. The general strategy uses the multi-scale
analysis bounds. Actually, we show that the multi-scale analysis bounds of the
single particle model remain stable when passing to multi-particle systems,
provided that the inter-particle interaction is sufficiently small. The common
probability distribution of the i.i.d. random external potential in the
Anderson model, is only needed to be log-H\"older continuous.


title:
The Right Invariant Nonlinear Complementary Filter for Low Cost Attitude
  and Heading Estimation of Platforms

abstract:
  This paper presents a novel filter with low computational demand to address
the problem of orientation estimation of a robotic platform. This is
conventionally addressed by extended Kalman filtering of measurements from a
sensor suit which mainly includes accelerometers, gyroscopes, and a digital
compass. Low cost robotic platforms demand simpler and computationally more
efficient methods to address this filtering problem. Hence nonlinear observers
with constant gains have emerged to assume this role. The nonlinear
complementary filter is a popular choice in this domain which does not require
covariance matrix propagation and associated computational overhead in its
filtering algorithm. However, the gain tuning procedure of the complementary
filter is not optimal, where it is often hand picked by trial and error. This
process is counter intuitive to system noise based tuning capability offered by
a stochastic filter like the Kalman filter. This paper proposes the right
invariant formulation of the complementary filter, which preserves Kalman like
system noise based gain tuning capability for the filter. The resulting filter
exhibits efficient operation in elementary embedded hardware, intuitive system
noise based gain tuning capability and accurate attitude estimation. The
performance of the filter is validated using numerical simulations and by
experimentally implementing the filter on an ARDrone 2.0 micro aerial vehicle
platform.


title:
Wavelet-Bayesian inference of cosmic strings embedded in the cosmic
  microwave background

abstract:
  Cosmic strings are a well-motivated extension to the standard cosmological
model and could induce a subdominant component in the anisotropies of the
cosmic microwave background (CMB), in addition to the standard inflationary
component. The detection of strings, while observationally challenging, would
provide a direct probe of physics at very high energy scales. We develop a new
framework for cosmic string inference, constructing a Bayesian analysis in
wavelet space where the string-induced CMB component has distinct statistical
properties to the standard inflationary component. Our wavelet-Bayesian
framework provides a principled approach to compute the posterior distribution
of the string tension $G\mu$ and the Bayesian evidence ratio comparing the
string model to the standard inflationary model. Furthermore, we present a
technique to recover an estimate of any string-induced CMB map embedded in
observational data. Using Planck-like simulations we demonstrate the
application of our framework and evaluate its performance. The method is
sensitive to $G\mu \sim 5 \times 10^{-7}$ for Nambu-Goto string simulations
that include an integrated Sachs-Wolfe (ISW) contribution only and do not
include any recombination effects, before any parameters of the analysis are
optimised. The sensitivity of the method compares favourably with other
techniques applied to the same simulations.


title: Inference for the mode of a log-concave density

abstract:
  We study a likelihood ratio test for the location of the mode of a
log-concave density. Our test is based on comparison of the log-likelihoods
corresponding to the unconstrained maximum likelihood estimator of a
log-concave density and the constrained maximum likelihood estimator where the
constraint is that the mode of the density is fixed, say at $m$. The
constrained estimation problem is studied in detail in Doss and Wellner [2018].
Here the results of that paper are used to show that, under the null hypothesis
(and strict curvature of $-\log f$ at the mode), the likelihood ratio statistic
is asymptotically pivotal: that is, it converges in distribution to a limiting
distribution which is free of nuisance parameters, thus playing the role of the
$\chi_1^2$ distribution in classical parametric statistical problems. By
inverting this family of tests we obtain new (likelihood ratio based)
confidence intervals for the mode of a log-concave density $f$. These new
intervals do not depend on any smoothing parameters. We study the new
confidence intervals via Monte Carlo methods and illustrate them with two real
data sets. The new intervals seem to have several advantages over existing
procedures. Software implementing the test and confidence intervals is
available in the R package \verb+logcondens.mode+.


title:
Non-Convex Projected Gradient Descent for Generalized Low-Rank Tensor
  Regression

abstract:
  In this paper, we consider the problem of learning high-dimensional tensor
regression problems with low-rank structure. One of the core challenges
associated with learning high-dimensional models is computation since the
underlying optimization problems are often non-convex. While convex relaxations
could lead to polynomial-time algorithms they are often slow in practice. On
the other hand, limited theoretical guarantees exist for non-convex methods. In
this paper we provide a general framework that provides theoretical guarantees
for learning high-dimensional tensor regression models under different low-rank
structural assumptions using the projected gradient descent algorithm applied
to a potentially non-convex constraint set $\Theta$ in terms of its
\emph{localized Gaussian width}. We juxtapose our theoretical results for
non-convex projected gradient descent algorithms with previous results on
regularized convex approaches. The two main differences between the convex and
non-convex approach are: (i) from a computational perspective whether the
non-convex projection operator is computable and whether the projection has
desirable contraction properties and (ii) from a statistical upper bound
perspective, the non-convex approach has a superior rate for a number of
examples. We provide three concrete examples of low-dimensional structure which
address these issues and explain the pros and cons for the non-convex and
convex approaches. We supplement our theoretical results with simulations which
show that, under several common settings of generalized low rank tensor
regression, the projected gradient descent approach is superior both in terms
of statistical error and run-time provided the step-sizes of the projected
descent algorithm are suitably chosen.


title:
Robust predictions for an oscillatory bispectrum in Planck 2015 data
  from transient reductions in the speed of sound of the inflaton

abstract:
  We update the search for features in the Cosmic Microwave Background (CMB)
power spectrum due to transient reductions in the speed of sound, using Planck
2015 CMB temperature and polarisation data. We enlarge the parameter space to
much higher oscillatory frequencies of the feature, and define a robust prior
independent of the ansatz for the reduction, guaranteed to reproduce the
assumptions of the theoretical model and exhaustive in the regime in which the
feature is easily distinguishable from the baseline cosmology. We find a fit to
the $\ell\approx20$--$40$ minus/plus structure in Planck TT power spectrum, as
well as features spanning along the higher $\ell$'s ($\ell\approx100$--$1500$).
For the last ones, we compute the correlated features that we expect to find in
the CMB bispectrum, and asses their signal-to-noise and correlation to the
ISW-lensing secondary bispectrum. We compare our findings to the shape-agnostic
oscillatory template tested in Planck 2015, and we comment on some tantalising
coincidences with some of the traits described in Planck's 2015 bispectrum
data.


title: Joint Causal Inference from Multiple Contexts

abstract:
  The gold standard for discovering causal relations is by means of
experimentation. Over the last decades, alternative methods have been proposed
that can infer causal relations between variables from certain statistical
patterns in purely observational data. We introduce Joint Causal Inference
(JCI), a novel approach to causal discovery from multiple data sets from
different contexts that elegantly unifies both approaches. JCI is a causal
modeling framework rather than a specific algorithm, and it can be implemented
using any causal discovery algorithm that can take into account certain
background knowledge. JCI can deal with different types of interventions (e.g.,
perfect, imperfect, stochastic, etc.) in a unified fashion, and does not
require knowledge of intervention targets or types in case of interventional
data. We explain how several well-known causal discovery algorithms can be seen
as addressing special cases of the JCI framework, and we also propose novel
implementations that extend existing causal discovery methods for purely
observational data to the JCI setting. We evaluate different JCI
implementations on synthetic data and on flow cytometry protein expression data
and conclude that JCI implementations can considerably outperform
state-of-the-art causal discovery algorithms.


title:
Junction termination extension (JTE) with variation lateral doping (VLD)
  optimization method

abstract:
  A simple and effective method for the junction termination design was
suggested. Optimization method uses lateral charge function F(x) which depends
from two arguments and can be changed in wide range of shapes. To demonstrate
method effectiveness, design and optimization example for the HV diode (1800 V)
edge termination was shown. Achieved breakdown voltage is 93% of the
corresponding 1D structure breakdown voltage.


title:
Minimization of errors in narrowband laser phase noise measurements
  based on reference measurement channels

abstract:
  We propose a novel scheme for laser phase noise measurements with minimized
sensitivity to external fluctuations including interferometer vibration,
temperature instability, other low-frequency noise, and relative intensity
noise. In order to minimize the effect of these external fluctuations, we
employ simultaneous measurement of two spectrally separated channels in the
scheme. We present an algorithm for selection of the desired signal to extract
the phase noise. Experimental results demonstrate potential of the suggested
scheme for a wide range of technological applications.


title:
Simultaneous bistability of qubit and resonator in circuit quantum
  electrodynamics

abstract:
  We explore the joint activated dynamics exhibited by two quantum degrees of
freedom: a cavity mode oscillator which is strongly coupled to a
superconducting qubit in the strongly coherently driven dispersive regime.
Dynamical simulations and complementary measurements show a range of parameters
where both the cavity and the qubit exhibit sudden simultaneous switching
between two metastable states. This manifests in ensemble averaged amplitudes
of both the cavity and qubit exhibiting a partial coherent cancellation.
Transmission measurements of driven microwave cavities coupled to transmon
qubits show detailed features which agree with the theory in the regime of
simultaneous switching.


title:
Non-Rayleigh distribution of reflected intensity from photonic crystals
  with disorder

abstract:
  Structural disorder results in multiple scattering in real photonic crystals,
which have been widely used for applications and studied for fundamental
interests. The interaction of light with such complex photonic media is
expected to show interplay between disorder and order. For a completely
disordered medium, the intensity statistics is well-known to obey Rayleigh
statistics with a negative exponential distribution function, corresponding to
absence of correlations. Intensity statistics is unexplored however for complex
media with both order and disorder. We study experimentally the intensity
statistics of light reflected from photonic crystals with various degree of
disorder. We observe deviations from the Rayleigh distribution and the
deviations increase with increasing long-range order.


title: Valley-Selective Landau-Zener Oscillations in Semi-Dirac p-n Junctions

abstract:
  We study transport across p-n junctions of gapped two-dimensional semi-Dirac
materials: nodal semimetals whose energy bands disperse quadratically and
linearly along distinct crystal axes. The resulting electronic properties ---
relevant to materials such as TiO$_2$/VO$_2$ multilayers and
$\alpha$-(BEDT-TTF)$_2$I$_3$ salts --- continuously interpolate between those
of mono- and bi-layer graphene as a function of propagation angle. We
demonstrate that tunneling across the junction depends on the orientation of
the tunnel barrier relative to the crystalline axes, leading to strongly
non-monotonic current-voltage characteristics, including negative differential
conductance in some regimes. In multi-valley systems these features provide a
natural route to engineering valley-selective transport.


title:
Achieving "space of physics journals": topological structure and the
  Journal Impact Factor

abstract:
  The empirical distribution function of citations to journal articles (EDF for
short) can become the fundamental tool for analyzing the scientific journals.
Endeavors at making bibliometric analysis independent of the intuition of
average citation levels have led us to the study of qualitative properties of
physics journals in the functional space of EDFs. We show that the structure of
this space establishes the connections and relationships that determine the
essential features of physics journals. The research provides an analysis of
240 physics journals indexed in Journal Citation Reports 2015. The relevance of
EDFs clustering is discussed. Our findings reveal four-cluster space of physics
journals. The space brings to light the essential distinctions between physics
journals and shows different level of influence of scientific publishers
belonging to different types (professional physics societies, transnational and
local publishers). The study of EDFs grouped by publishers reveals two binary
oppositions that structure relations between them: "global\,--- local"
publishers and "high cited\,--- low cited" publishers.


title: The quaternion over the ring of Colombeau's full generalized numbers

abstract:
  In this paper, we extend the results obtained by Cortes-Ferrero-Juriaans
(2009) for the quaternion over the ring Colombeau's simplified generalized
numbers, denoted by $\overline{\mathbb{H}}_s$, to the quaternion over the ring
of Colombeau's full generalized numbers, denoted by $\overline{\mathbb{H}}$. In
this paper, we introduce and investigate the topological algebra of the
quaternion over the ring of Colombeau's full generalized numbers. This is an
important object to study if one wants to build the algebraic theory of
Colombeau's full generalized numbers $\overline{\mathbb{K}}$ studied by
Aragona-Garcia-Juriaans (2013). We study some ring theoretical properties of
$\overline{\mathbb{H}}$, we classify the dense ideals of
$\overline{\mathbb{K}}$ in the algebraic sense, and as a consequence, it has a
maximal ring of quotients which is Von Neumann regular.


title:
Inference for log Gaussian Cox processes using an approximate marginal
  posterior

abstract:
  The log Gaussian Cox process is a flexible class of point pattern models for
capturing spatial and spatio-temporal dependence for point patterns. Model
fitting requires approximation of stochastic integrals which is implemented
through discretization of the domain of interest. With fine scale
discretization, inference based on Markov chain Monte Carlo is computationally
heavy because of the cost of repeated iteration or inversion or Cholesky
decomposition (cubic order) of high dimensional covariance matrices associated
with latent Gaussian variables. Furthermore, hyperparameters for latent
Gaussian variables have strong dependence with sampled latent Gaussian
variables. Altogether, standard Markov chain Monte Carlo strategies are
inefficient and not well behaved.
  In this paper, we propose an efficient computational strategy for fitting and
inferring with spatial log Gaussian Cox processes. The proposed algorithm is
based on a pseudo-marginal Markov chain Monte Carlo approach. We estimate an
approximate marginal posterior for parameters of log Gaussian Cox processes and
propose comprehensive model inference strategy. We provide details for all of
the above along with some simulation investigation for the univariate and
multivariate settings. As an example, we present an analysis of a point pattern
of locations of three tree species, exhibiting positive and negative
interaction between different species.


title: Zoom-Simulations of Protoplanetary Disks starting from GMC scales

abstract:
  We investigate the formation of protoplanetary disks around nine solar mass
stars formed in the context of a (40 pc)$^3$ Giant Molecular Cloud model, using
RAMSES adaptive-mesh refinement simulations extending over a scale range of
about 4 million, from an outer scale of 40 pc down to cell sizes of 2 AU. Our
most important result is that the accretion process is heterogeneous in
multiple ways; in time, in space, and among protostars of otherwise similar
mass. Accretion is heterogeneous in time, in the sense that accretion rates
vary during the evolution, with generally decreasing profiles, whose slopes
vary over a wide range, and where accretion can increase again if a protostar
enters a region with increased density and low speed. Accretion is
heterogeneous in space, because of the mass distribution, with mass approaching
the accreting star-disk system in filaments and sheets. Finally, accretion is
heterogeneous among stars, since the detailed conditions and dynamics in the
neighborhood of each star can vary widely. We also investigate the sensitivity
of disk formation to physical conditions, and test their robustness by varying
numerical parameters. We find that disk formation is robust even when choosing
the least favorable sink particle parameters, and that turbulence cascading
from larger scales is a decisive factor in disk formation. We also investigate
the transport of angular momentum, finding that the net inward mechanical
transport is compensated for mainly by an outward directed magnetic transport,
with a contribution from gravitational torques usually subordinate to the
magnetic transport.


title: Characterizing dw1335-29, a recently discovered dwarf satellite of M83

abstract:
  The number, distribution, and properties of dwarf satellites are crucial
probes of the physics of galaxy formation at low masses and the response of
satellite galaxies to the tidal and gas dynamical effects of their more massive
parent.To make progress, it is necessary to augment and solidify the census of
dwarf satellites of galaxies outside the Local Group. M\"uller et al. (2015)
presented 16 dwarf galaxy candidates near M83, but lacking reliable distances,
it is unclear which candidates are M83 satellites. Using red giant branch stars
from the HST/GHOSTS survey in conjunction with ground-based images from
VLT/VIMOS, we confirm that one of the candidates, dw1335-29-- with a projected
distance of 26 kpc from M83 and a distance modulus of $(m - M)_0 =
28.5^{+0.3}_{-0.1}$ -- is a satellite of M83. We estimate an absolute magnitude
$M_V = -10.1 \pm{0.4}$, an ellipticity of $0.40^{+0.14}_{-0.22}$, a half light
radius of $656^{+121}_{-170 }$ pc, and [Fe/H] = $-1.3^{+0.3}_{-0.4}$. Owing to
dw1335-29's somewhat irregular shape and possible young stars, we classify this
galaxy as a dwarf irregular or transition dwarf. This is curious, as with a
projected distance of 26 kpc from M83, dw1335-29 is expected to lack recent
star formation. Further study of M83's dwarf population will reveal if star
formation in its satellites is commonplace (suggesting a lack of a hot gas
envelope for M83 that would quench star formation) or rare (suggesting that
dw1335-29 has a larger M83-centric distance, and is fortuitously projected to
small radii).


title:
Upper limits for Mass and Radius of objects around Proxima Cen from
  SPHERE/VLT

abstract:
  The recent discovery of an earth-like planet around Proxima Centauri has
drawn much attention to this star and its environment. We performed a series of
observations of Proxima Centauri using SPHERE, the planet finder instrument
installed at the ESO Very Large Telescope UT3, using its near infrared modules,
IRDIS and IFS. No planet was directly detected but we set upper limits on the
mass up to 7 au exploiting the AMES-COND models. Our IFS observations reveal
that no planet more massive than ~6-7 M Jup can be present within 1 au. The
dual band imaging camera IRDIS also enables us to probe larger separations than
the other techniques like the radial velocity or astrometry. We obtained mass
limits of the order of 4 M Jup at separations of 2 au or larger representing
the most stringent mass limits at separations larger than 5 au available at the
moment. We also did an attempt to estimate the radius of possible planets
around Proxima using the reflected light. Since the residual noise for this
observations are dominated by photon noise and thermal background, longer
exposures in good observing conditions could further improve the achievable
contrast limit.


title: Memory-Usage Advantageous Block Recursive Matrix Inverse

abstract:
  The inversion of extremely high order matrices has been a challenging task
because of the limited processing and memory capacity of conventional
computers. In a scenario in which the data does not fit in memory, it is worth
to consider exchanging less memory usage for more processing time in order to
enable the computation of the inverse which otherwise would be prohibitive. We
propose a new algorithm to compute the inverse of block partitioned matrices
with a reduced memory footprint. The algorithm works recursively to invert one
block of a $k \times k$ block matrix $M$, with $k \geq 2$, based on the
successive splitting of $M$. It computes one block of the inverse at a time, in
order to limit memory usage during the entire processing. Experimental results
show that, despite increasing computational complexity, matrices that otherwise
would exceed the memory-usage limit can be inverted using this technique.


title: The Ziegler spectrum of the D-infinity plane singularity

abstract:
  We will describe the Cohen--Macaulay part of the Ziegler spectrum of the
D-infinity plane singularity S and calculate the nilpotency index of the
radical of the category of finitely generated Cohen--Macaulay S-modules.


title:
Rudolf Haag's legacy of Local Quantum Physics and reminiscences about a
  cherished teacher and friend

abstract:
  After some personal recollectioms about Rudolf Haag and his thoughts which
led him to "Local Quantum Physics", the present work recalls his ideas about
scattering theory, the relation between local observables and localized fields
and his contributions to the physical aspects of modular operator theory which
paved the way for an intrisic understanding of quantum causal localization in
which fields "coordinatize" the local algebras. The paper ends with the
presentation of string-local fields whose construction and use in a new
renormalization theory for higher spin fields is part of an ongoing
reformulation of gauge theory in the conceptual setting of Haag's LQP.


title: Kelvin-Helmholtz instability of AB interface in superfluid 3He

abstract:
  The Kelvin-Helmholtz instability is well-known in classical hydrodynamics,
where it explains the sudden emergence of interfacial surface waves as a
function of the velocity of flow parallel to the interface. It can be carried
over to the inviscid two-fluid dynamics of superfluids, to study different
types of interfaces and phase boundaries in quantum fluids. We report
measurements on the stability of the phase boundary separating the two bulk
phases of superfluid 3He in rotating flow, while the boundary is localized with
the gradient of the magnetic field to a position perpendicular to the rotation
axis. The results demonstrate that the classic stability condition, when
modified for the superfluid environment, is obeyed down to 0.4 Tc, if a large
fraction of the magnetic polarization of the B-phase is attributed to a
parabolic reduction of the interfacial surface tension with increasing magnetic
field.


title:
Plug & Play Generative Networks: Conditional Iterative Generation of
  Images in Latent Space

abstract:
  Generating high-resolution, photo-realistic images has been a long-standing
goal in machine learning. Recently, Nguyen et al. (2016) showed one interesting
way to synthesize novel images by performing gradient ascent in the latent
space of a generator network to maximize the activations of one or multiple
neurons in a separate classifier network. In this paper we extend this method
by introducing an additional prior on the latent code, improving both sample
quality and sample diversity, leading to a state-of-the-art generative model
that produces high quality images at higher resolutions (227x227) than previous
generative models, and does so for all 1000 ImageNet categories. In addition,
we provide a unified probabilistic interpretation of related activation
maximization methods and call the general class of models "Plug and Play
Generative Networks". PPGNs are composed of 1) a generator network G that is
capable of drawing a wide range of image types and 2) a replaceable "condition"
network C that tells the generator what to draw. We demonstrate the generation
of images conditioned on a class (when C is an ImageNet or MIT Places
classification network) and also conditioned on a caption (when C is an image
captioning network). Our method also improves the state of the art of
Multifaceted Feature Visualization, which generates the set of synthetic inputs
that activate a neuron in order to better understand how deep neural networks
operate. Finally, we show that our model performs reasonably well at the task
of image inpainting. While image models are used in this paper, the approach is
modality-agnostic and can be applied to many types of data.


title:
Activity measurement of 60Fe through the decay of 60mCo and confirmation
  of its half-life

abstract:
  The half-life of the neutron-rich nuclide, {\fesixty} has been in dispute in
recent years. A measurement in 2009 published a value of $(2.62 \pm
0.04)\times10^{6}$ years, almost twice that of the previously accepted value
from 1984 of $(1.49 \pm 0.27)\times10^{6}$ years. This longer half-life was
confirmed in 2015 by a second measurement, resulting in a value of $(2.50 \pm
0.12)\times10^{6}$ years. All three half-life measurements used the grow-in of
the $\gamma$-ray lines in {\nisixty} from the decay of the ground state of
$^{60}\text{Co}$ (t$_{1/2}$=5.27 years) to determine the activity of a sample
with a known number of {\fesixty} atoms. In contrast, the work presented here
measured the {\fesixty} activity directly via the 58.6 keV $\gamma$-ray line
from the short-lived isomeric state of $^{60}\text{Co}$ (t$_{1/2}$=10.5
minutes), thus being independent of any possible contamination from long-lived
$^{60\text{g}}\text{Co}$. A fraction of the material from the 2015 experiment
with a known number of {\fesixty} atoms was used for the activity measurement,
resulting in a half-life value of $(2.72 \pm 0.16)\times10^{6}$ years,
confirming again the longer half-life. In addition, {\fesixty}/{\fe} isotopic
ratios of samples with two different dilutions of this material were measured
with Accelerator Mass Spectrometry (AMS) to determine the number of {\fesixty}
atoms. Combining this with our activity measurement resulted in a half-life
value of $(2.69 \pm 0.28)\times 10^{6}$ years, again agreeing with the longer
half-life.


title: On the number of maximum independent sets in Doob graphs

abstract:
  The Doob graph $D(m,n)$ is a distance-regular graph with the same parameters
as the Hamming graph $H(2m+n,4)$. The maximum independent sets in the Doob
graphs are analogs of the distance-$2$ MDS codes in the Hamming graphs. We
prove that the logarithm of the number of the maximum independent sets in
$D(m,n)$ grows as $2^{2m+n-1}(1+o(1))$. The main tool for the upper estimation
is constructing an injective map from the class of maximum independent sets in
$D(m,n)$ to the class of distance-$2$ MDS codes in $H(2m+n,4)$.


title: Constructing stable 3D hydrodynamical models of giant stars

abstract:
  Hydrodynamical simulations of stellar interactions require stable models of
stars as initial conditions. Such initial models, however, are difficult to
construct for giant stars because of the wide range in spatial scales of the
hydrostatic equilibrium and in dynamical timescales between the core and the
envelope of the giant. They are needed for, e.g., modeling the common envelope
phase where a giant envelope encompasses both the giant core and a companion
star. Here, we present a new method of approximating and reconstructing giant
profiles from a stellar evolution code to produce stable models for
multi-dimensional hydrodynamical simulations. We determine typical stellar
stratification profiles with the 1D stellar evolution code MESA. After an
appropriate mapping, hydrodynamical simulations are conducted using the
moving-mesh code AREPO. The giant profiles are approximated by replacing the
core of the giant with a point mass and by constructing a suitable continuation
of the profile to the center. Different reconstruction methods are tested that
can specifically control the convective behaviour of the model. After mapping
to a grid, a relaxation procedure that includes damping of spurious velocities
yields stable models in three-dimensional hydrodynamical simulations. Initially
convectively stable configurations lead to stable hydrodynamical models while
for stratifications that are convectively unstable in the stellar evolution
code, simulations recover the convective behaviour of the initial model and
show large convective plumes with Mach numbers up to 0.8. Examples are shown
for a $2M_\odot$ red giant and a $0.67M_\odot$ asymptotic giant branch star. A
detailed analysis shows that the improved method reliably provides stable
models of giant envelopes that can be used as initial conditions for subsequent
hydrodynamical simulations of stellar interactions involving giant stars.


title:
Package-X 2.0: A Mathematica package for the analytic calculation of
  one-loop integrals

abstract:
  This article summarizes new features and enhancements of the first major
update of Package-X. Package-X 2.0 can now generate analytic expressions for
arbitrarily high rank dimensionally regulated tensor integrals with up to four
distinct propagators, each with arbitrary integer weight, near an arbitrary
even number of spacetime dimensions, giving UV divergent, IR divergent, and
finite parts at (almost) any real-valued kinematic point. Additionally, it can
generate multivariable Taylor series expansions of these integrals around any
non-singular kinematic point to arbitrary order. All special functions and
abbreviations output by Package-X 2.0 supports Mathematica's arbitrary
precision evaluation capabilities to deal with issues of numerical stability.
Finally, tensor algebraic routines of Package-X have been polished and extended
to support open fermion chains both on and off shell. The documentation
(equivalent to over 100 printed pages) is accessed through Mathematica's
Wolfram Documentation Center and contains information on all Package-X symbols,
with over 300 basic usage examples, 3 project-scale tutorials, and instructions
on linking to FeynCalc and LoopTools.


title:
ALMA Observations Show Major Mergers Among the Host Galaxies of
  Fast-growing, High-redshift Supermassive Black Holes

abstract:
  We present new ALMA band-7 data for a sample of six luminous quasars at
z~4.8, powered by fast-growing supermassive black holes (SMBHs) with rather
uniform properties: the typical accretion rates and black hole masses are
L/L_Edd~0.7 and M_BH~10^9 M_sol. Our sample consists of three "FIR-bright"
sources, which were individually detected in previous Herschel/SPIRE
observations, with star formation rates of SFR>1000 M_sol/yr, and three
"FIR-faint" sources for which Herschel stacking analysis implies a typical SFR
of ~400 M_sol/yr. The dusty interstellar medium in the hosts of all six quasars
is clearly detected in the ALMA data and resolved on scales of ~2 kpc, in both
continuum (\lambda_rest ~150 um) and [C II]157.74 um line emission. The
continuum emission is in good agreement with the expectations from the Herschel
data, confirming the intense SF activity in the quasar hosts. Importantly, we
detect companion sub-millimeter galaxies (SMGs) for three sources -- one
FIR-bright and two FIR-faint, separated by ~14-45 kpc and <450 km/s from the
quasar hosts. The [C II]-based dynamical mass estimates for the interacting
SMGs are within a factor of ~3 of the quasar hosts' masses, while the continuum
emission implies SFR(quasar)~(2-11)xSFR(SMG). Our ALMA data therefore clearly
support the idea that major mergers are important drivers for rapid early SMBH
growth. However, the fact that not all high-SFR quasar hosts are accompanied by
interacting SMGs and the gas kinematics as observed by ALMA suggest that other
processes may be fueling these systems. Our analysis thus demonstrates the
diversity of host galaxy properties and gas accretion mechanisms associated
with early and rapid SMBH growth.


title: Can tidal disruption events produce the IceCube neutrinos?

abstract:
  Powerful jets and outflows generated in tidal disruption events (TDEs) around
supermassive black holes have been suggested to be possible sites producing
high-energy neutrinos, but it is unclear whether such environment can provide
the bulk of the neutrinos detected by the IceCube Observatory. In this work, by
considering realistic limits on the non-thermal emission power of a TDE jet and
the birth rate of the TDEs with jets pointing towards us, we show that it is
hard to use the jetted TDE population to explain the flux and the isotropic
arrival directions of the observed TeV-PeV neutrinos. Therefore, TDEs cannot be
the dominant sources, unless those without aligned jets can produce wide-angle
emission of neutrino particles. Supposing that is the case, we list a few
recent jetted and non-jetted TDEs that have the best chance to be detected by
IceCube, based on their energetics, distances, and directions. A spatial and
temporal association of these predicted events with the IceCube data should
provide a decisive test on the full TDE population as origins of the IceCube
neutrinos.


title: Beauty-full Tetraquarks

abstract:
  In this article we present a calculation of the $bb\bar{b}\bar{b}$ tetraquark
ground-state energy using a diffusion Monte Carlo method to solve the
non-relativistic many-body system. The static potential for the four quark
system is chosen to align with the flux-tube picture of QCD. Using this
approach, we find that the $0^{++}$ state has a mass of $18.69\pm
0.03~\mbox{GeV}$, which is around 100 MeV below twice the $\eta_b$ mass. This
bound state can behave as a four-lepton resonance via its decay to
$\Upsilon(1S) \Upsilon(1S)^* \rightarrow \ell^+ \ell^- \ell^+ \ell^-$.


title:
The Stellar Initial Mass Function in Early-Type Galaxies From Absorption
  Line Spectroscopy. IV. A Super-Salpeter IMF in the center of NGC 1407 from
  Non-Parametric Models

abstract:
  It is now well-established that the stellar initial mass function (IMF) can
be determined from the absorption line spectra of old stellar systems, and this
has been used to measure the IMF and its variation across the early-type galaxy
population. Previous work focused on measuring the slope of the IMF over one or
more stellar mass intervals, implicitly assuming that this is a good
description of the IMF and that the IMF has a universal low-mass cutoff. In
this work we consider more flexible IMFs, including two-component power-laws
with a variable low-mass cutoff and a general non-parametric model. We
demonstrate with mock spectra that the detailed shape of the IMF can be
accurately recovered as long as the data quality are high (S/N$\gtrsim300$) and
cover a wide wavelength range (0.4um-1.0um). We apply these flexible IMF models
to a high S/N spectrum of the center of the massive elliptical galaxy NGC 1407.
Fitting the spectrum with non-parametric IMFs, we find that the IMF in the
center shows a continuous rise extending toward the hydrogen-burning limit,
with a behavior that is well-approximated by a power-law with an index of -2.7.
These results provide strong evidence for the existence of extreme
(super-Salpeter) IMFs in the cores of massive galaxies.


title:
Spinning Kerr black holes with stationary massive scalar clouds: The
  large-coupling regime

abstract:
  We study analytically the Klein-Gordon wave equation for stationary massive
scalar fields linearly coupled to spinning Kerr black holes. In particular,
using the WKB approximation, we derive a compact formula for the discrete
spectrum of scalar field masses which characterize the stationary composed
Kerr-black-hole-massive-scalar-field configurations in the large-coupling
regime $M\mu\gg1$ (here $M$ and $\mu$ are respectively the mass of the central
black hole and the proper mass of the scalar field). We confirm our
analytically derived formula for the Kerr-scalar-field mass spectrum with
numerical data that recently appeared in the literature.


title: Formation of Majorana fermions in finite-size graphene strips

abstract:
  We investigate the formation of Majorana fermions in finite-size graphene
strips with open boundary conditions in both directions, in the presence of an
in-plane magnetic field and in the proximity of a superconducting substrate. We
show that for long enough strips the Majorana states can form in the presence
of a Rashba-like spin-orbit coupling, as well as in the presence of an
inhomogeneous magnetic field. We find that, unlike infinite graphene ribbons in
which Majorana states arise solely close to the bottom of the band and the Van
Hove singularities, for finite-size systems this can happen also at much
smaller doping values, close to the Dirac points, and depends strongly on the
type of the short edges of the systems (e.g. armchair vs. zigzag), as well as
on the width of the ribbons.


title: Competing phases in spin ladders with ring exchange and frustration

abstract:
  The ground state properties of spin-1/2 ladders are studied, emphasizing the
role of frustration and ring exchange coupling. We present a unified field
theory for ladders with general coupling constants and geometry. Rich phase
diagrams can be deduced by using a renormalization group calculation for
ladders with in--chain next nearest neighbor interactions and plaquette ring
exchange coupling. In addition to established phases such as Haldane, rung
singlet, and dimerized phases, we also observe a surprising instability towards
an incommensurate phase for weak interchain couplings, which is characterized
by an exotic coexistence of self-consistent ferromagnetic and
anti-ferromagnetic order parameters.


title: Code properties from holographic geometries

abstract:
  Almheiri, Dong, and Harlow [arXiv:1411.7041] proposed a highly illuminating
connection between the AdS/CFT holographic correspondence and operator algebra
quantum error correction (OAQEC). Here we explore this connection further. We
derive some general results about OAQEC, as well as results that apply
specifically to quantum codes which admit a holographic interpretation. We
introduce a new quantity called `price', which characterizes the support of a
protected logical system, and find constraints on the price and the distance
for logical subalgebras of quantum codes. We show that holographic codes
defined on bulk manifolds with asymptotically negative curvature exhibit
`uberholography', meaning that a bulk logical algebra can be supported on a
boundary region with a fractal structure. We argue that, for holographic codes
defined on bulk manifolds with asymptotically flat or positive curvature, the
boundary physics must be highly nonlocal, an observation with potential
implications for black holes and for quantum gravity in AdS space at distance
scales small compared to the AdS curvature radius.


title: Non-Local Coulomb Drag in Weyl Semimetals

abstract:
  Non-locality is one of the most striking signatures of the topological nature
of Weyl semimetals. We propose to probe the non-locality in these materials via
a measurement of a magnetic field dependent Coulomb drag between two sheets of
graphene which are separated by a three-dimensional slab of Weyl semimetal. We
predict a new mechanism of Coulomb drag, based on cyclotron orbits that are
split between opposite surfaces of the semi-metal. In the absence of impurity
scattering between different Weyl nodes, this mechanism does not decay with the
thickness of the semi-metal.


title:
Two is better than one: joint statistics of density and velocity in
  concentric spheres as a cosmological probe

abstract:
  The analytical formalism to obtain the probability distribution functions
(PDFs) of spherically-averaged cosmic densities and velocity divergences in the
mildly non-linear regime is presented. A large-deviation principle is applied
to those cosmic fields assuming their most likely dynamics in spheres is set by
the spherical collapse model. We validate our analytical results using
state-of-the-art dark matter simulations with a phase-space resolved velocity
field finding a 2% percent level agreement for a wide range of velocity
divergences and densities in the mildly nonlinear regime (~10Mpc/h at redshift
zero), usually inaccessible to perturbation theory. From the joint PDF of
densities and velocity divergences measured in two concentric spheres, we
extract with the same accuracy velocity profiles and conditional velocity PDF
subject to a given over/under-density which are of interest to understand the
non-linear evolution of velocity flows. Both PDFs are used to build a simple
but accurate maximum likelihood estimators for the redshift evolution of the
variance of both the density and velocity divergence fields, which have smaller
relative errors than their sample variances when non-linearities appear. Given
the dependence of the velocity divergence on the growth rate, there is a
significant gain in using the full knowledge of both PDFs to derive constraints
on the equation of state of dark energy. Thanks to the insensitivity of the
velocity divergence to bias, its PDF can be used to obtain unbiased constraints
on the growth of structures ($\sigma_8$,f) or it can be combined with the
galaxy density PDF to extract bias parameters.


title: Gravitational waves and large field inflation

abstract:
  According to the famous Lyth bound, one can confirm large field inflation by
finding tensor modes with sufficiently large tensor-to-scalar ratio $r$. Here
we will try to answer two related questions: Is it possible to rule out all
large field inflationary models by not finding tensor modes with $r$ above some
critical value, and what can we say about the scale of inflation by measuring
$r$? However, in order to answer these questions one should distinguish between
two different definitions of the large field inflation and three different
definitions of the scale of inflation. We will examine these issues using the
theory of cosmological $\alpha$-attractors as a convenient testing ground.