title:
Massive Multiple Access Based on Superposition Raptor Codes for M2M
  Communications

abstract:
  Machine-to-machine (M2M) wireless systems aim to provide ubiquitous
connectivity between machine type communication (MTC) devices without any human
intervention. Given the exponential growth of MTC traffic, it is of utmost
importance to ensure that future wireless standards are capable of handling
this traffic. In this paper, we focus on the design of a very efficient massive
access strategy for highly dense cellular networks with M2M communications.
Several MTC devices are allowed to simultaneously transmit at the same resource
block by incorporating Raptor codes and superposition modulation. This
significantly reduces the access delay and improves the achievable system
throughput. A simple yet efficient random access strategy is proposed to only
detect the selected preambles and the number of devices which have chosen them.
No device identification is needed in the random access phase which
significantly reduces the signalling overhead. The proposed scheme is analyzed
and the maximum number of MTC devices that can be supported in a resource block
is characterized as a function of the message length, number of available
resources, and the number of preambles. Simulation results show that the
proposed scheme can effectively support a massive number of MTC devices for a
limited number of available resources, when the message size is small.


title: Higher dimensional nonlinear massive gravity

abstract:
  Inspired by a recent ghost-free nonlinear massive gravity in four-dimensional
spacetime, we study its higher dimensional scenarios. As a result, we are able
to show the constant-like behavior of massive graviton terms for some
well-known metrics such as the Friedmann-Lemaitre-Robertson-Walker, Bianchi
type I, and Schwarzschild-Tangherlini-(A)dS metrics in a specific
five-dimensional nonlinear massive gravity under an assumption that its
fiducial metrics are compatible with physical ones. In addition, some simple
cosmological solutions of the five-dimensional massive gravity will be figured
out consistently.


title: Pre-reheating Magnetogenesis in the Kinetic Coupling Model

abstract:
  Recent blazar observations provide growing evidence for the presence of
magnetic fields in the extragalactic regions. While a natural speculation is to
associate the production to inflationary physics, it has been known that
magnetogenesis solely from inflation is quite challenging. We therefore study a
model in which a non-inflaton field $\chi$ coupled to the electromagnetic field
through its kinetic term, $-I^2(\chi) F^2 /4$, continues to move after
inflation until the completion of reheating. This leads to a post-inflationary
amplification of the electromagnetic field. We compute all the relevant
contributions to the curvature perturbation, including gravitational
interactions, and impose the constraints from the CMB scalar fluctuations on
the strength of magnetic fields. We, for the first time, explicitly verify both
the backreaction and CMB constraints in a simple yet successful magnetogenesis
scenario without invoking a dedicated low-scale inflationary model in the
weak-coupling regime of the kinetic coupling model.


title:
On the Detection of Non-Transiting Hot Jupiters in Multiple-Planet
  Systems

abstract:
  We outline a photometric method for detecting the presence of a
non-transiting short-period giant planet in a planetary system harboring one or
more longer period transiting planets. Within a prospective system of the type
that we consider, a hot Jupiter on an interior orbit inclined to the
line-of-sight signals its presence through approximately sinusoidal full-phase
photometric variations in the stellar light curve, correlated with
astrometrically induced transit timing variations for exterior transiting
planets. Systems containing a hot Jupiter along with a low-mass outer planet or
planets on inclined orbits are a predicted hallmark of in situ accretion for
hot Jupiters, and their presence can thus be used to test planetary formation
theories. We outline the prospects for detecting non-transiting hot Jupiters
using photometric data from typical \textit{Kepler} objects of interest (KOIs).
As a demonstration of the technique, we perform a brief assessment of
\textit{Kepler} candidates and identify a potential non-transiting hot Jupiter
in the KOI-1822 system. Candidate non-transiting hot Jupiters can be readily
confirmed with a small number of Doppler velocity observations, even for stars
with $V\gtrsim14$.


title: Rotating Restricted Schur Polynomials

abstract:
  Large $N$ but non-planar limits of ${\cal N}=4$ super Yang-Mills theory can
be described using restricted Schur polynomials. Previous investigations
demonstrate that the action of the one loop dilatation operator on restricted
Schur operators, with classical dimension of order $N$ and belonging to the
$su(2)$ sector, is largely determined by the $su(2)$ ${\cal R}$ symmetry
algebra as well as structural features of perturbative field theory. Studies
presented so far have used the form of ${\cal R}$ symmetry generators when
acting on small perturbations of half-BPS operators. In this article, as a
first step towards going beyond small perturbations of the half-BPS operators,
we explain how the exact action of symmetry generators on restricted Schur
polynomials can be determined.


title: The dimensions of spaces of Siegel cusp forms of general degree

abstract:
  In this paper, we give a dimension formula for spaces of Siegel cusp forms of
general degree with respect to neat arithmetic subgroups. The formula was
conjectured before by several researchers. The dimensions are expressed by
special values of Shintani zeta functions for spaces of symmetric matrices at
non-positive integers. This formula was given by Shintani for only a small part
of the geometric side of the trace formula. To be precise, it is the
contribution of unipotent elements corresponding to the partitions
$(2^j,1^{2n-2j})$, where $n$ denotes the degree and $0\leq j \leq n$. Hence,
our work is to show that all the other contributions vanish. In addition, one
finds that Shintani's formula means the dimension itself. Combining our formula
and an explicit formula of the Shintani zeta functions, which was discovered by
Ibukiyama and Saito, we can derive an explicit dimension formula for the
principal congruence subgroups of level greater than two. In this explicit
dimension formula, the dimensions are described by degree $n$, weight $k$,
level $N$, and the Bernoulli numbers $B_m$.


title:
Attraction properties for general urn processes and applications to a
  class of interacting reinforced particle systems

abstract:
  We study a system of interacting reinforced random walks defined on polygons.
At each stage, each particle chooses an edge to traverse which is incident to
its position. We allow the probability of choosing a given edge to depend on
the sum of, the number of times that particle traversed that edge, a quantity
which depends on the behaviour of the other particles, and possibly external
factors. We study localization properties of this system and our main tool is a
new result we establish for a very general class of urn models. More
specifically, we study attraction properties of urns composed of balls with two
distinct colors which evolve as follows. At each stage a ball is extracted. The
probability of picking a ball of a certain color evolves in time. This
evolution may depend not only on the composition of the urn but also on
external factors or internal ones depending on the history of the urn. A
particular example of the latter is when the reinforcement is a function of the
composition of the urn and the biggest run of consecutive picks with the same
color. The model that we introduce and study is very general, and we prove that
under mild conditions, one of the colors in the urn is picked only finitely
often.


title:
Coherent dynamics of mixed Frenkel and Charge Transfer Excitons in
  Dinaphtho[2,3-b:2'3'-f]thieno[3,2-b]-thiophene Thin Films: The Importance of
  Hole Delocalization

abstract:
  Charge transfer states in organic semiconductors play crucial roles in
processes such as singlet fission and exciton dissociation at donor/acceptor
interfaces. Recently, a time-resolved spectroscopy study of
dinaphtho[2,3-b:2'3'-f]thieno[3,2-b]-thiophene (DNTT) thin films provided
evidence for the formation of mixed Frenkel and charge-transfer excitons after
the photoexcitation. Here we investigate optical properties and excitation
dynamics of the DNTT thin films by combining ab initio calculations and a
stochastic Schrodinger equation. Our theory predicts that the low-energy
Frenkel exciton band consists of 8 to 47% CT character. The quantum dynamics
simulations show coherent dynamics of Frenkel and CT states in 50 fs after the
optical excitation. We demonstrate the role of charge delocalization and
localization in the mixing of CT states with Frenkel excitons as well as the
role of their decoherence.


title: Noise filtering of composite pulses for singlet-triplet qubits

abstract:
  Semiconductor quantum dot spin qubits are promising candidates for quantum
computing. In these systems, the dynamically corrected gates offer considerable
reduction of gate errors and are therefore of great interest both theoretically
and experimentally. They are, however, designed under the static-noise model
and may be considered as low-frequency filters. In this work, we perform a
comprehensive theoretical study of the response of a type of dynamically
corrected gates, namely the {\sc supcode} for singlet-triplet qubits, to
realistic $1/f$ noises with frequency spectra $1/\omega^\alpha$. Through
randomized benchmarking, we have found that {\sc supcode} offers improvement of
the gate fidelity for $\alpha\gtrsim1$ and the improvement becomes
exponentially more pronounced with the increase of the noise exponent in the
range $1\lesssim\alpha\leq3$ studied. On the other hand, for small $\alpha$,
{\sc supcode} will not offer any improvement. The $\delta J$-{\sc supcode},
specifically designed for systems where the nuclear noise is absent, is found
to offer additional error reduction than the full {\sc supcode} for charge
noises. The computed filter transfer functions of the {\sc supcode} gates are
also presented.


title:
Coupled k-space structure of $d$-wave superconducting and magnetic
  orders induced by paramagnetic pair-breaking effect

abstract:
  We theoretically investigate k-space structures of $d_{x^2-y^2}$-wave
superconducting (SC) and spin-density-wave (SDW) orders in their coexistent
phase induced by a paramagnetic pair-breaking (PPB) effect in relation to the
high field and low temperature (HFLT) SC phase in CeCoIn$_5$. It is shown that,
in k-space, the SDW order develops near the gap nodes where the SC order is
suppressed by PPB, and the nesting condition for the SDW ordering is satisfied.
By comparing the results in the $d_{x^2-y^2}$-wave SC model and those in an
artificial model with no sign change of the gap function in k-space with each
other, it is shown that the $d_{x^2-y^2}$-wave SC and SDW orders are enhanced
altogether in k-space due to the sign change of the $d_{x^2-y^2}$-wave gap
function there, and that this mutual enhancement largely stabilizes the
coexistence of these orders in real space. It is also discussed that the field
dependence of a SDW moment can be affected by the k-space structure of these
orders, which is dependent on the curvature of the Fermi surface.


title: A program logic for union bounds

abstract:
  We propose a probabilistic Hoare logic aHL based on the union bound, a tool
from basic probability theory. While the union bound is simple, it is an
extremely common tool for analyzing randomized algorithms. In formal
verification terms, the union bound allows flexible and compositional reasoning
over possible ways an algorithm may go wrong. It also enables a clean
separation between reasoning about probabilities and reasoning about events,
which are expressed as standard first-order formulas in our logic. Notably,
assertions in our logic are non-probabilistic, even though we can conclude
probabilistic facts from the judgments.
  Our logic can also prove accuracy properties for interactive programs, where
the program must produce intermediate outputs as soon as pieces of the input
arrive, rather than accessing the entire input at once. This setting also
enables adaptivity, where later inputs may depend on earlier intermediate
outputs. We show how to prove accuracy for several examples from the
differential privacy literature, both interactive and non-interactive.


title: Audio Recording Device Identification Based on Deep Learning

abstract:
  In this paper we present a research on identification of audio recording
devices from background noise, thus providing a method for forensics. The audio
signal is the sum of speech signal and noise signal. Usually, people pay more
attention to speech signal, because it carries the information to deliver. So a
great amount of researches have been dedicated to getting higher
Signal-Noise-Ratio (SNR). There are many speech enhancement algorithms to
improve the quality of the speech, which can be seen as reducing the noise.
However, noises can be regarded as the intrinsic fingerprint traces of an audio
recording device. These digital traces can be characterized and identified by
new machine learning techniques. Therefore, in our research, we use the noise
as the intrinsic features. As for the identification, multiple classifiers of
deep learning methods are used and compared. The identification result shows
that the method of getting feature vector from the noise of each device and
identifying them with deep learning techniques is viable, and well-preformed.


title:
Experimental quantum processing enhancement in modelling stochastic
  processes

abstract:
  Computer simulation of observable phenomena is an indispensable tool for
engineering new technology, understanding the natural world, and studying human
society. Yet the most interesting systems are often complex, such that
simulating their future behaviour demands storing immense amounts of
information regarding how they have behaved in the past. For increasingly
complex systems, simulation becomes increasingly difficult and is ultimately
constrained by resources such as computer memory. Recent theoretical work shows
quantum theory can reduce this memory requirement beyond ultimate classical
limits (as measured by a process' statistical complexity, C). Here we
experimentally demonstrate this quantum advantage in simulating stochastic
processes. Our quantum implementation observes a memory requirement of C_q =
0.05 $\pm$ 0.01, far below the ultimate classical limit of C = 1. Scaling up
this technique would substantially reduce the memory required in simulation of
more complex systems.


title:
Giant Voltage Manipulation of MgO-based Magnetic Tunnel Junctions via
  Localized Anisotropic Strain: a Potential Pathway to Ultra-Energy-Efficient
  Memory Technology

abstract:
  Strain-mediated voltage control of magnetization in
piezoelectric/ferromagnetic systems is a promising mechanism to implement
energy-efficient spintronic memory devices. Here, we demonstrate giant voltage
manipulation of MgO magnetic tunnel junctions (MTJ) on a
Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) piezoelectric substrate with (001)
orientation. It is found that the magnetic easy axis, switching field, and the
tunnel magnetoresistance (TMR) of the MTJ can be efficiently controlled by
strain from the underlying piezoelectric layer upon the application of a gate
voltage. Repeatable voltage controlled MTJ toggling between high/low-resistance
states is demonstrated. More importantly, instead of relying on the intrinsic
anisotropy of the piezoelectric substrate to generate the required strain, we
utilize anisotropic strain produced using local gating scheme, which is
scalable and amenable to practical memory applications. Additionally, the
adoption of crystalline MgO-based MTJ on piezoelectric layer lends itself to
high TMR in the strain-mediated MRAM devices.


title:
Atom-light superposition oscillation and Ramsey-like atom-light
  interferometer

abstract:
  Coherent wave splitting is crucial in interferometers. Normally, the waves
after this splitting are of the same type. But recent progress in interaction
between atom and light has led to the coherent conversion of photon to atomic
excitation. This makes it possible to split an incoming light wave into a
coherent superposition state of atom and light and paves the way for an
interferometer made of different types of waves. Here we report on a Rabi-like
coherent-superposition oscillation observed between atom and light and a
coherent mixing of light wave with excited atomic spin wave in a Raman process.
We construct a new kind of hybrid interferometer based on the atom-light
coherent superposition state. Interference fringes are observed in both optical
output intensity and atomic output in terms of the atomic spin wave strength
when we scan either or both of the optical and atomic phases. Such a hybrid
interferometer can be used to interrogate atomic states by optical detection
and will find its applications in precision measurement and quantum control of
atoms and light.


title: An extension of a theorem of Kaplansky

abstract:
  A theorem of Kaplansky asserts that a semigroup of matrices with entries from
a field whose members all have singleton spectra is triangularizable. Indeed,
Kaplansky's Theorem unifies well-known theorems of Kolchin and Levitzki on
simultaneous triangularizability of semigroups of unipotent and nilpotent
matrices, respectively. First, we present a new and simple proof of Kaplansky's
Theorem over fields of characteristic zero. Next, we show that this proof can
be adjusted to show that the counterpart of Kolchin's Theorem over division
rings of characteristic zero implies that of Kaplansky's Theorem over such
division rings. Also, we give a generalization of Kaplansky's Theorem over
general fields. We show that this extension of Kaplansky's Theorem holds over a
division ring $\Delta$ provided the counterpart of Kaplansky's Theorem holds
over $\Delta$.


title: Hole-doping-induced melting of spin-state ordering in PrBaCo2O5.5+x

abstract:
  The layered perovskite cobaltite RBaCo$_2$O$_{5.5}$ (R: rare-earth elements
or Yttrium) exhibits an abrupt temperature-induced metal$-$insulator transition
(MIT) and has been attributed to spin-state ordering (SSO) of Co$^{3+}$ ions.
Here we investigated the hole doping member of PrBaCo$_2$O$_{5.5+x}$ ($0 \le x
\le 0.24$) with multiple techniques. The analysis on crystal and magnetic
structures by electron and neutron diffraction confirm the SSO in the
insulating phase of undoped PrBaCo$_2$O$_{5.5}$, which is melted by increasing
the temperature across the MIT. In addition, we discovered that hole doping to
PrBaCo$_2$O$_{5.5}$ also melts the SSO in conjunction with an insulator-metal
transition. The experimental results from electron/neutron diffraction and soft
x-ray absorption spectroscopy (XAS) all lead to the conclusion that hole-doping
induced MIT occurs is in the same manner as the temperature-induced MIT.
Therefore, we propose a unified mechanism that dominates the temperature- and
hole-doping-induced MITs in the PrBaCo$_2$O$_{5.5+x}$ system. Specifically,
this mechanism involves symmetry breaking coupled with a SSO in the
paramagnetic phase.


title: On a conjecture of Braverman and Kazhdan

abstract:
  In this paper a proof of Conjecture 9.12 of Braverman and Kazhdan in their
article "gamma-functions of representations and lifting" on the acyclicity of
their l-adic gamma-sheaves over certain affine spaces is given for GL(n).


title: Using Isomorphic Problems to Learn Introductory Physics

abstract:
  In this study, we examine introductory physics students' ability to perform
analogical reasoning between two isomorphic problems which employ the same
underlying physics principles but have different surface features. Three
hundred and sixty two students from a calculus-based and an algebra-based
introductory physics course were given a quiz in the recitation in which they
had to first learn from a solved problem provided and take advantage of what
they learned from it to solve another problem (which we call the quiz problem)
which was isomorphic. Previous research suggests that the multiple-concept quiz
problem is challenging for introductory students. Students in different
recitation classes received different interventions in order to help them
discern and exploit the underlying similarities of the isomorphic solved and
quiz problems. We also conducted think-aloud interviews with four introductory
students in order to understand in-depth the difficulties they had and explore
strategies to provide better scaffolding. We found that most students were able
to learn from the solved problem to some extent with the scaffolding provided
and invoke the relevant principles in the quiz problem. However, they were not
necessarily able to apply the principles correctly. Research suggests that more
scaffolding is needed to help students in applying these principles
appropriately. We outline a few possible strategies for future investigation.


title:
Selective Bi-coordinate Method for Non-Stationary and Non-Smooth
  Resource Allocation Type Problems

abstract:
  We propose a method of bi-coordinate variations for non-stationary and
non-smooth optimization problems, which involve a single linear equality and
box constraints. Here only approximation sequences are known instead of exact
values of the cost function and parameters of the feasible set. It consists in
making descent steps with respect to only two selected coordinates satisfying
some special threshold rule. The method is simpler essentially than the usual
gradient or dual type ones and differs from the previous known bi-coordinate
ones suggested for the usual stationary and smooth problems. We establish its
convergence under rather mild assumptions. Computational tests also reveal
certain preferences of the proposed method over the known ones.


title: Arzel\`a-Ascoli theorem via Wallman compactification

abstract:
  In the paper, we recall the Wallman compactification of a Tychonoff space $T$
(denoted by $\text{Wall}(T)$) and the contribution made by Gillman and Jerison.
Motivated by the Gelfand-Naimark theorem, we investigate the homeomorphism
between $BC(T,\mathbb{R})$ and $BC(\text{Wall}(T),\mathbb{R})$. Along the way,
we attempt to justify the advantages of Wallman compactification over other
manifestations of Stone-\v{C}ech compactification. The main result of the paper
is a new form of Arzel\`a-Ascoli theorem, which introduces the concept of
equicontinuity along $\omega$-ultrafilters.


title:
Physical origin of Davydov splitting and resonant Raman spectroscopy of
  Davydov components in multilayer MoTe2

abstract:
  We systematically study the high-resolution and polarized Raman spectra of
multilayer (ML) MoTe2. The layer-breathing (LB) and shear (C) modes are
observed in the ultralow-frequency region, which are used to quantitatively
evaluate the interlayer coupling in ML MoTe2 based on the linear chain model,
in which only the nearest interlayer coupling is considered. The Raman spectra
on three different substrates verify the negligible substrate effect on the
phonon frequencies of ML MoTe2. Ten excitation energies are used to measure the
high-frequency modes of N-layer MoTe2 (NL MoTe2; N is an integer). Under the
resonant excitation condition, we observe N-dependent Davydov components in ML
MoTe2 , originating from the Raman-active A'1(A21g) modes at ~172 cm-1. More
than two Davydov components are observed in NL MoTe2 for N larger than 4 by
Raman spectroscopy. The N-dependent Davydov components are further investigated
based on the symmetry analysis. A van der Waals model only considering the
nearest interlayer coupling has been proposed to well understand the Davydov
splitting of high-frequency A'1(A21g) modes. The different resonant profiles
for the two Davydov components in 3L MoTe2 indicate that proper excitation
energy of ~1.8-2.2 eV must be chosen to observe the Davydov splitting in ML
MoTe2 . Our work presents a simple way to identify layer number of ultrathin
MoTe2 flakes by the corresponding number and peak position of Davydov
components. Our work also provides a direct evidence from Raman spectroscopy of
how the nearest van der Waals interactions significantly affect the frequency
of the high-frequency intralayer phonon modes in multilayer MoTe2 and expands
the understanding on the lattice vibrations and interlayer coupling of
transition metal dichalcogenides and other two-dimensional materials.


title: Arzel\`a-Ascoli theorem in uniform spaces

abstract:
  In the paper, we generalize the Arzel\`a-Ascoli theorem in the setting of
uniform spaces. At first, we recall well-known facts and theorems coming from
monographs of Kelley and Willard. The main part of the paper introduces the
notion of extension property which, similarly as equicontinuity, equates
different topologies on $C(X,Y)$. This property enables us to prove the
Arzel\`a-Ascoli theorem for uniform convergence. The paper culminates with
applications, which are motivated by Schwartz's distribution theory. Using the
Banach-Alaoglu-Bourbaki theorem, we establish relative compactness of subfamily
of $C(\mathbb{R},\mathcal{D}'(\mathbb{R}^n))$.


title: On a finite subsemigroup of semigroups in which x^r=x

abstract:
  In this paper, we consider the following problem: For every positive integer
$r \geq 2$, find all positive integers $n$ such that for every semigroup of
order $\geq n$ in which $x^r=x$ for every element $x$ has a subsemigroup of
order $n$.


title: Robust seismic velocity change estimation using ambient noise recordings

abstract:
  We consider the problem of seismic velocity change estimation using ambient
noise recordings. Motivated by [23] we study how the velocity change estimation
is affected by seasonal fluctuations in the noise sources. More precisely, we
consider a numerical model and introduce spatio-temporal seasonal fluctuations
in the noise sources. We show that indeed, as pointed out in [23], the
stretching method is affected by these fluctuations and produces misleading
apparent velocity variations which reduce dramatically the signal to noise
ratio of the method. We also show that these apparent velocity variations can
be eliminated by an adequate normalization of the cross-correlation functions.
Theoretically we expect our approach to work as long as the seasonal
fluctuations in the noise sources are uniform, an assumption which holds for
closely located seismic stations. We illustrate with numerical simulations and
real measurements that the proposed normalization significantly improves the
accuracy of the velocity change estimation.


title: Decay to equilibrium for energy-reaction-diffusion systems

abstract:
  We derive thermodynamically consistent models of reaction-diffusion equations
coupled to a heat equation. While the total energy is conserved, the total
entropy serves as a driving functional such that the full coupled system is a
gradient flow. The novelty of the approach is the Onsager structure, which is
the dual form of a gradient system, and the formulation in terms of the
densities and the internal energy. In these variables it is possible to assume
that the entropy density is strictly concave such that there is a unique
maximizer (thermodynamical equilibrium) given linear constraints on the total
energy and suitable density constraints.
  We consider two particular systems of this type, namely, a diffusion-reaction
bipolar energy transport system, and a drift-diffusion-reaction energy
transport system with confining potential. We prove corresponding
entropy-entropy production inequalities with explicitely calculable constants
and establish the convergence to thermodynamical equilibrium, at first in
entropy and further in $L^1$ using Cziszar-Kullback-Pinsker type inequalities.


title:
Effect of Scaffolding on Helping Introductory Physics Students Solve
  Quantitative Problems Involving Strong Alternative Conceptions

abstract:
  It is well-known that introductory physics students often have alternative
conceptions that are inconsistent with established physical principles and
concepts. Invoking alternative conceptions in quantitative problem-solving
process can derail the entire process. In order to help students solve
quantitative problems involving strong alternative conceptions correctly,
appropriate scaffolding support can be helpful. The goal of this study is to
examine how different scaffolding supports involving analogical problem solving
influence introductory physics students' performance on a target quantitative
problem in a situation where many students' solution process is derailed due to
alternative conceptions. Three different scaffolding supports were designed and
implemented in calculus-based and algebra-based introductory physics courses to
evaluate the level of scaffolding needed to help students learn from an
analogical problem that is similar in the underlying principles but for which
the problem solving process is not derailed by alternative conceptions. We
found that for the quantitative problem involving strong alternative
conceptions, simply guiding students to work through the solution of the
analogical problem first was not enough to help most students discern the
similarity between the two problems. However, if additional scaffolding
supports that directly helped students examine and repair their knowledge
elements involving alternative conceptions were provided, students were more
likely to discern the underlying similarities between the problems and avoid
getting derailed by alternative conceptions when solving the targeted problem.
We also found that some scaffolding supports were more effective in the
calculus-based course than in the algebra-based course. This finding emphasizes
the fact that appropriate scaffolding support must be determined via research
in order to be effective.


title:
Algebraic Birkhoff conjecture for billiards on Sphere and Hyperbolic
  plane

abstract:
  We consider a convex curve $\gamma$ lying on the Sphere or Hyperbolic plane.
We study the problem of existence of polynomial in velocities integrals for
Birkhoff billiard inside the domain bounded by $\gamma$. We extend the result
by S. Bolotin (1992) and get new obstructions on polynomial integrability in
terms of the dual curve $\Gamma$. We follow a method which was introduced by S.
Tabachnikov for Outer billiards in the plane and was applied later on in our
recent paper to Birkhoff billiards with the help of a new the so called Angular
billiard.


title:
Query Answering with Inconsistent Existential Rules under Stable Model
  Semantics

abstract:
  Traditional inconsistency-tolerent query answering in ontology-based data
access relies on selecting maximal components of an ABox/database which are
consistent with the ontology. However, some rules in ontologies might be
unreliable if they are extracted from ontology learning or written by
unskillful knowledge engineers. In this paper we present a framework of
handling inconsistent existential rules under stable model semantics, which is
defined by a notion called rule repairs to select maximal components of the
existential rules. Surprisingly, for R-acyclic existential rules with
R-stratified or guarded existential rules with stratified negations, both the
data complexity and combined complexity of query answering under the rule
{repair semantics} remain the same as that under the conventional query
answering semantics. This leads us to propose several approaches to handle the
rule {repair semantics} by calling answer set programming solvers. An
experimental evaluation shows that these approaches have good scalability of
query answering under rule repairs on realistic cases.


title:
Hyperbolic Self-Gravity Solver for Large Scale Hydrodynamical
  Simulations

abstract:
  A new computationally efficient method has been introduced to treat
self-gravity in mesh based hydrodynamical simulations. It is applied simply by
slightly modifying the Poisson equation into an inhomogeneous wave equation.
This roughly corresponds to the weak field limit of the Einstein equations in
general relativity, and as long as the gravitation propagation speed is taken
to be larger than the hydrodynamical characteristic speed, the results agree
with solutions for the Poisson equation. The solutions almost perfectly agree
if the domain is taken large enough, or appropriate boundary conditions are
given. Our new method can not only significantly reduce the computational time
compared with existent methods, but is also fully compatible with massive
parallel computation, nested grids and adaptive mesh refinement techniques, all
of which can accelerate the progress in computational astrophysics and
cosmology.


title:
Deformation of singular connections I: $G_{2}-$instantons with point
  singularities

abstract:
  In dimension 7, we establish a Fredholm theory for a Dirac-type operator
associated to a connection with point singularities. There are two
applications. $1$. over a closed 7-manifold, under some natural conditions, a
$G_{2}-$instanton and its point singularities can still be "seen" when the
$G_{2}-$structure is properly perturbed. $2$. over a ball in $\R^{7}$, for any
almost-Euclidean $G_{2}-$structure, there exists a $G_{2}-$monopole asymptotic
to an arbitrary Hermitian Yang-Mills connection on $S^{6}$.


title:
EEG-informed attended speaker extraction from recorded speech mixtures
  with application in neuro-steered hearing prostheses

abstract:
  OBJECTIVE: We aim to extract and denoise the attended speaker in a noisy,
two-speaker acoustic scenario, relying on microphone array recordings from a
binaural hearing aid, which are complemented with electroencephalography (EEG)
recordings to infer the speaker of interest. METHODS: In this study, we propose
a modular processing flow that first extracts the two speech envelopes from the
microphone recordings, then selects the attended speech envelope based on the
EEG, and finally uses this envelope to inform a multi-channel speech separation
and denoising algorithm. RESULTS: Strong suppression of interfering
(unattended) speech and background noise is achieved, while the attended speech
is preserved. Furthermore, EEG-based auditory attention detection (AAD) is
shown to be robust to the use of noisy speech signals. CONCLUSIONS: Our results
show that AAD-based speaker extraction from microphone array recordings is
feasible and robust, even in noisy acoustic environments, and without access to
the clean speech signals to perform EEG-based AAD. SIGNIFICANCE: Current
research on AAD always assumes the availability of the clean speech signals,
which limits the applicability in real settings. We have extended this research
to detect the attended speaker even when only microphone recordings with noisy
speech mixtures are available. This is an enabling ingredient for new
brain-computer interfaces and effective filtering schemes in neuro-steered
hearing prostheses. Here, we provide a first proof of concept for EEG-informed
attended speaker extraction and denoising.


title: Adaptive Least Mean Squares Estimation of Graph Signals

abstract:
  The aim of this paper is to propose a least mean squares (LMS) strategy for
adaptive estimation of signals defined over graphs. Assuming the graph signal
to be band-limited, over a known bandwidth, the method enables reconstruction,
with guaranteed performance in terms of mean-square error, and tracking from a
limited number of observations over a subset of vertices. A detailed mean
square analysis provides the performance of the proposed method, and leads to
several insights for designing useful sampling strategies for graph signals.
Numerical results validate our theoretical findings, and illustrate the
performance of the proposed method. Furthermore, to cope with the case where
the bandwidth is not known beforehand, we propose a method that performs a
sparse online estimation of the signal support in the (graph) frequency domain,
which enables online adaptation of the graph sampling strategy. Finally, we
apply the proposed method to build the power spatial density cartography of a
given operational region in a cognitive network environment.


title: Segre classes and Kempf-Laksov formula in algebraic cobordism

abstract:
  In this paper, we study Segre classes in algebraic cobordism. We also prove a
generalization of Kempf-Laksov formula for the degeneracy loci classes in the
algebraic cobordism of the Grassmannian bundle.


title: A theory of contemplation

abstract:
  In this paper you can explore the application of some notable Boolean-derived
methods, namely the Disjunctive Normal Form representation of logic table
expansions, and extend them to a real-valued logic model which is able to
utilize quantities on the range [0,1], [-1,1], [a,b], (x,y), (x,y,z), and etc.
so as to produce a logical programming of arbitrary range, precision, and
dimensionality, thereby enabling contemplation at a logical level in notions of
arbitrary data, colors, and spatial constructs, with an example of the
production of a game character's logic in mathematical form.


title: Observational Sequences of Randall-Sundrum Black Holes

abstract:
  We consider the spherically symmetric black hole solution of the
Randall-Sundrum (RS) model. This asymptotically-Schwarzschild solution was
found by Abdolrahimi, Cation, Page and Yaghoobpour-Tari (ACPY-solution). We
investigate the specific properties of the accretion disk around ACPY black
hole having astrophysical size and mass. The energy flux and temperature
distribution are obtained and compared with the Schwarzschild ones. We also
present the spectral energy distribution of the accretion disk around RS black
holes, when the transfer function is taken into account. Thus we confirm a full
agreement of the accretion rate in RS model with the GR predictions. Using
recent data on the high-mass X-ray binary Cygnus X-1 and on the Galactic centre
black hole candidate Sgr A* we model the accretion in the RS model.


title:
Quantum statistical gravity: time dilation due to local information in
  many-body quantum systems

abstract:
  We propose a generic mechanism for the emergence of a gravitational potential
that acts on all classical objects in a quantum system. Our conjecture is based
on the analysis of mutual information in many-body quantum systems. Since
measurements in quantum systems affect the surroundings through entanglement, a
measurement at one position reduces the entropy in its neighbourhood. This
reduction in entropy can be described by a local temperature, that is directly
related to the gravitational potential. A crucial ingredient in our argument is
that ideal classical mechanical motion occurs at constant probability. This
definition is motivated by the analysis of entropic forces in classical
systems, which can be formally rewritten in terms of a gravitational potential.


title:
Central Limit Theorems of a Recursive Stochastic Algorithm with
  Applications to Adaptive Designs

abstract:
  Stochastic approximation algorithms have been the subject of an enormous body
of literature, both theoretical and applied. Recently, Laruelle and Pag\`es
(2013) presented a link between the stochastic approximation and
response-adaptive designs in clinical trials based on randomized urn models
investigated in Bai and Hu (1999, 2005), and derived the asymptotic normality
or central limit theorem for the normalized procedure using a central limit
theorem for the stochastic approximation algorithm. However, the classical
central limit theorem for the stochastic approximation algorithm does not
include all cases of its regression function, creating a gap between the
results of Laruelle and Pag\`es (2013) and those of Bai and Hu (2005) for
randomized urn models. In this paper, we establish new central limit theorems
of the stochastic approximation algorithm under the popular Lindeberg condition
to fill this gap. Moreover, we prove that the process of the algorithms can be
approximated by a Gaussian process that is a solution of a stochastic
differential equation. In our application, we investigate a more involved
family of urn models and related adaptive designs in which it is possible to
remove the balls from the urn, and the expectation of the total number of balls
updated at each stage is not necessary a constant. The asymptotic properties
are derived under much less stringent assumptions than those in Bai and Hu
(1999, 2005) and Laruelle and Pag\`es (2013).


title:
Observation of Four-body Ring-exchange Interactions and Anyonic
  Fractional Statistics

abstract:
  Ring exchange is an elementary interaction for modeling unconventional
topological matters which hold promise for efficient quantum information
processing. We report the observation of four-body ring-exchange interactions
and the topological properties of anyonic excitations within an ultracold atom
system. A minimum toric code Hamiltonian in which the ring exchange is the
dominant term, was implemented by engineering a Hubbard Hamiltonian that
describes atomic spins in disconnected plaquette arrays formed by two
orthogonal superlattices. The ring-exchange interactions were resolved from the
dynamical evolutions in the spin orders, matching well with the predicted
energy gaps between two anyonic excitations of the spin system. A braiding
operation was applied to the spins in the plaquettes and an induced phase
$1.00(3)\pi$ in the four-spin state was observed, confirming
$\frac{1}{2}$-anynoic statistics. This work represents an essential step
towards studying topological matters with many-body systems and the
applications in quantum computation and simulation.


title:
Using an Isomorphic Problem Pair to Learn Introductory Physics:
  Transferring from a Two-step Problem to a Three-step Problem

abstract:
  In this study, we examine introductory physics students' ability to perform
analogical reasoning between two isomorphic problems which employ the same
underlying physics principles but have different surface features. Three
hundred and eighty two students from a calculus-based and an algebra-based
introductory physics course were asked to learn from a solved problem provided
and take advantage of what they learned from it to solve another isomorphic
problem (which we call the quiz problem). The solved problem provided has two
sub-problems while the quiz problem has three sub-problems, which is known to
be challenging for introductory students from previous research. In addition to
the solved problem, students also received extra scaffolding supports that were
intended to help them discern and exploit the underlying similarities of the
isomorphic solved and quiz problems. The results suggest that students had
great difficulty in transferring what they learned from a 2-step problem to a
3-step problem. Although most students were able to learn from the solved
problem to some extent with the scaffolding provided and invoke the relevant
principles in the quiz problem, they were not necessarily able to apply the
principles correctly. We also conducted think-aloud interviews with 6
introductory students in order to understand in-depth the difficulties they had
and explore strategies to provide better scaffolding. The interviews suggest
that students often superficially mapped the principles employed in the solved
problem to the quiz problem without necessarily understanding the governing
conditions underlying each principle and examining the applicability of the
principle in the new situation in an in-depth manner. Findings suggest that
more scaffolding is needed to help students in transferring from a two-step
problem to a three step problem and applying the physics principles
appropriately.


title:
Inferences on the Relations Between Central Black Hole Mass and Total
  Galaxy Stellar Mass in the high-redshift Universe

abstract:
  At the highest redshifts, z>6, several tens of luminous quasars have been
detected. The search for fainter AGN, in deep X-ray surveys, has proven less
successful, with few candidates to date. An extrapolation of the relationship
between black hole (BH) and bulge mass would predict that the sample of z>6
galaxies host relatively massive BHs (>1e6 Msun), if one assumes that total
stellar mass is a good proxy for bulge mass. At least a few of these BHs should
be luminous enough to be detectable in the 4Ms CDFS. The relation between BH
and stellar mass defined by local moderate-luminosity AGN in low-mass galaxies,
however, has a normalization that is lower by approximately an order of
magnitude compared to the BH-bulge mass relation. We explore how this scaling
changes the interpretation of AGN in the high-z Universe. Despite large
uncertainties, driven by those in the stellar mass function, and in the
extrapolation of local relations, one can explain the current non-detection of
moderate-luminosity AGN in Lyman Break Galaxies if galaxies below 1e11 Msun are
characterized by the low-normalization scaling, and, even more so, if their
Eddington ratio is also typical of moderate-luminosity AGN rather than luminous
quasars. AGN being missed by X-ray searches due to obscuration or instrinsic
X-ray weakness also remain a possibility.


title:
Average Distance in a General Class of Scale-Free Networks with
  Underlying Geometry

abstract:
  In Chung-Lu random graphs, a classic model for real-world networks, each
vertex is equipped with a weight drawn from a power-law distribution, and two
vertices form an edge independently with probability proportional to the
product of their weights. Chung-Lu graphs have average distance O(log log n)
and thus reproduce the small-world phenomenon, a key property of real-world
networks. Modern, more realistic variants of this model also equip each vertex
with a random position in a specific underlying geometry. The edge probability
of two vertices then depends, say, inversely polynomial on their distance.
  In this paper we study a generic augmented version of Chung-Lu random graphs.
We analyze a model where the edge probability of two vertices can depend
arbitrarily on their positions, as long as the marginal probability of forming
an edge (for two vertices with fixed weights, one fixed position, and one
random position) is as in Chung-Lu random graphs. The resulting class contains
Chung-Lu random graphs, hyperbolic random graphs, and geometric inhomogeneous
random graphs as special cases.
  Our main result is that every random graph model in this general class has
the same average distance as Chung-Lu random graphs, up to a factor 1+o(1).
This shows in particular that specific choices, such as the underlying geometry
being Euclidean or the dependence on the distance being inversely polynomial,
do not significantly influence the average distance. The proof also yields that
our model has a giant component and polylogarithmic diameter with high
probability.


title: Evidence of Formation of Superdense Nonmagnetic Cobalt

abstract:
  Magnetism of 3d transition metals at high density has always received wide
interest due to existence of magnetism at the core of the Earth. For
ferromagnetic cobalt, although there is a theoretical prediction that its
magnetic moment would vanish when the density increases to about 1.4 times the
normal value, so far there is no experimental evidence. We have discovered the
existence of ultrathin superdense nonmagnetic cobalt layers in a
polycrystalline cobalt thin film. The densities of these layers are about
1.3-1.4 times the normal density of Co. This has been revealed by X-ray
reflectometry experiments, which provide a depth profile of the electron
scattering length density, and corroborated by polarized neutron reflectometry
(PNR) experiments. The superdense Co layer has an fcc structure, unlike hcp
structure for bulk Co, as revealed by transmission electron microscopy. The
magnetic depth profile, obtained by PNR, shows that the superdense Co layers at
the film-substrate interface and near the top of the film are nonmagnetic. The
major part of the Co film has the usual density and magnetic moment.


title:
Improving Students' Understanding of Quantum Measurement Part 1:
  Investigation of Difficulties

abstract:
  We describe the difficulties that advanced undergraduate and graduate
students have with quantum measurement within the standard interpretation of
quantum mechanics. We explore the possible origins of these difficulties by
analyzing student responses to questions from both surveys and interviews.
Results from this research are applied to develop research-based learning
tutorials to improve students' understanding of quantum measurement.


title:
Far infrared and terahertz spectroscopy of ferroelectric soft modes in
  thin films: A review

abstract:
  Far-infrared and terahertz spectroscopy of ferroelectric soft and central
modes in thin films on substrates is reviewed. In addition to classical
displacive proper ferroelectrics, also incipient and relaxor ferroelectrics and
multiferroics are discussed. Special attention is paid to differences between
the soft-mode behavior in thin films and bulk materials (ceramics and single
crystals) and their influence on the low-frequency permittivity. Particularly
the effects of the thin film strains and depolarizing electric fields of the
probing waves on the grain boundaries are emphasized. The soft-mode
spectroscopy is shown to be a very sensitive tool to reveal the thin film
quality.


title:
A GPU-based Large-scale Monte Carlo Simulation Method for Systems with
  Long-range Interactions

abstract:
  In this work we present an efficient implementation of Canonical Monte Carlo
simulation for Coulomb many body systems on graphics processing units (GPU).
Our method takes advantage of the GPU Single Instruction, Multiple Data (SIMD)
architectures. It adopts the sequential updating scheme of Metropolis
algorithm, and makes no approximation in the computation of energy. It reaches
a remarkable 440-fold speedup, compared with the serial implementation on CPU.
We use this method to simulate primitive model electrolytes. We measure very
precisely all ion-ion pair correlation functions at high concentrations, and
extract renormalized Debye length, renormalized valences of constituent ions,
and renormalized dielectric constants. These results demonstrate unequivocally
physics beyond the classical Poisson-Boltzmann theory.


title: On the Gabor frame set for compactly supported continuous functions

abstract:
  We identify a class of continuous compactly supported functions for which the
known part of the Gabor frame set can be extended. At least for functions with
support on an interval of length two, the curve determining the set touches the
known obstructions. Easy verifiable sufficient conditions for a function to
belong to the class are derived, and it is shown that the B-splines $B_N, N\ge
2,$ as well as certain "continuous and truncated" versions of several classical
functions (e.g., the Gaussian and the two-sided exponential function) belong to
the class. The sufficient conditions for the frame property guarantees the
existence of a dual window with a prescribed size of the support.


title:
The Postulate of the Three Regimes of Economic Growth Contradicted by
  Data

abstract:
  Economic growth in Western Europe, Eastern Europe, Asia, countries of the
former USSR, Africa and Latin America were analysed. It is demonstrated that
the fundamental postulate of the Unified Growth Theory about the existence of
the three regimes of growth (Malthusian regime, post-Malthusian regime and
sustained-growth regime) is contradicted by data. These regimes did not exist.
In particular, there was no escape from the Malthusian trap because there was
no trap. Economic growth in all these regions was not stagnant but hyperbolic.
Unified Growth Theory is fundamentally incorrect. However, this theory is also
dangerously misleading because it claims a transition from the endless epoch of
stagnation to the new era of sustained economic growth, the interpretation
creating the sense of security and a promise of prosperity. The data show that
the opposite is true. Economic growth in the past was sustained and secure.
Now, it is supported by the increasing ecological deficit. The long-term
sustained and secure economic growth has yet to be created. It did not happen
automatically, as suggested incorrectly by the Unified Growth Theory.


title: An improved analysis of the ER-SpUD dictionary learning algorithm

abstract:
  In "dictionary learning" we observe $Y = AX + E$ for some
$Y\in\mathbb{R}^{n\times p}$, $A \in\mathbb{R}^{m\times n}$, and
$X\in\mathbb{R}^{m\times p}$. The matrix $Y$ is observed, and $A, X, E$ are
unknown. Here $E$ is "noise" of small norm, and $X$ is column-wise sparse. The
matrix $A$ is referred to as a {\em dictionary}, and its columns as {\em
atoms}. Then, given some small number $p$ of samples, i.e.\ columns of $Y$, the
goal is to learn the dictionary $A$ up to small error, as well as $X$. The
motivation is that in many applications data is expected to sparse when
represented by atoms in the "right" dictionary $A$ (e.g.\ images in the Haar
wavelet basis), and the goal is to learn $A$ from the data to then use it for
other applications.
  Recently, [SWW12] proposed the dictionary learning algorithm ER-SpUD with
provable guarantees when $E = 0$ and $m = n$. They showed if $X$ has
independent entries with an expected $s$ non-zeroes per column for $1 \lesssim
s \lesssim \sqrt{n}$, and with non-zero entries being subgaussian, then for
$p\gtrsim n^2\log^2 n$ with high probability ER-SpUD outputs matrices $A', X'$
which equal $A, X$ up to permuting and scaling columns (resp.\ rows) of $A$
(resp.\ $X$). They conjectured $p\gtrsim n\log n$ suffices, which they showed
was information theoretically necessary for {\em any} algorithm to succeed when
$s \simeq 1$. Significant progress was later obtained in [LV15].
  We show that for a slight variant of ER-SpUD, $p\gtrsim n\log(n/\delta)$
samples suffice for successful recovery with probability $1-\delta$. We also
show that for the unmodified ER-SpUD, $p\gtrsim n^{1.99}$ samples are required
even to learn $A, X$ with polynomially small success probability. This resolves
the main conjecture of [SWW12], and contradicts the main result of [LV15],
which claimed that $p\gtrsim n\log^4 n$ guarantees success whp.


title: Improving Students' Understanding of Quantum Measurement

abstract:
  We describe the difficulties advanced undergraduate and graduate students
have with quantum measurement. To reduce these difficulties, we have developed
research-based learning tools such as the Quantum Interactive Learning Tutorial
(QuILT) and peer instruction tools. A preliminary evaluation shows that these
learning tools are effective in improving students' understanding of concepts
related to quantum measurement.


title: Restricted deterministic Watson-Crick automata

abstract:
  In this paper, we introduce a new model of deterministic Watson-Crick
automaton namely restricted deterministic Watson- Crick automaton which is a
deterministic Watson-Crick automaton where the complementarity string in the
lower strand is restricted to a language L. We examine the computational power
of the restricted model with respect to L being in different language classes
such as regular, unary regular, finite, context free and context sensitive. We
also show that computational power of restricted deterministic Watson- Crick
automata with L in regular languages is same as that of deterministic
Watson-Crick automata and that the set of all languages accepted by restricted
deterministic Watson-Crick automata with L in unary regular languages is a
proper subset of context free languages.


title:
On partition of unities generated by entire functions and Gabor frames
  in $\ltrd$ and $\ell^2(\mzd)$

abstract:
  We characterize the entire functions $P$ of $d$ variables, $d\ge 2,$ for
which the $\mzd$-translates of $P\chi_{[0,N]^d}$ satisfy the partition of unity
for some $N\in \mn.$ In contrast to the one-dimensional case, these entire
functions are not necessarily periodic. In the case where $P$ is a
trigonometric polynomial, we characterize the maximal smoothness of
$P\chi_{[0,N]^d},$ as well as the function that achieves it. A number of
especially attractive constructions are achieved, e.g., of trigonometric
polynomials leading to any desired (finite) regularity for a fixed support
size. As an application we obtain easy constructions of matrix-generated Gabor
frames in $\ltrd,$ with small support and high smoothness. By sampling this
yields dual pairs of finite Gabor frames in $\ell^2(\mzd).$


title:
The effects of marine protected areas over time and species dispersal
  potential: A quantitative conservation conflict attempt

abstract:
  Protected areas are an important conservation measure. However, there are
controversial findings regarding whether closed areas are beneficial for
species and habitat conservation as well as landings. Species dispersal is
acknowledged as a key factor for the design and impacts of closed areas. A
series of agent based models using random diffusion to model fish dispersal
were run before and after habitat protection. All results were normalised
without the protected habitat in each scenario to detect the relative
difference after closing an area, all else being equal. Results show that
landings of species with short dispersal ranges will take longer to reach the
levels of pre Marine Protected Areas (MPAs) establishment than landings of
species with long dispersal ranges. Further the establishment of an MPA
generates a higher relative population source within the MPA for species with
low dispersal abilities than for species with high dispersal abilities. Results
derived here show that there exists a win-win feasible scenario that maximises
both fish biomass as well as fish catches.


title: Scaling behavior of quantum critical relaxation dynamics in a heat bath

abstract:
  We study the scaling behavior of the relaxation dynamics to thermal
equilibrium when a quantum system is near the quantum critical point. In
particular, we investigate systems whose relaxation dynamics is described by a
Lindblad master equation. We find that the universal scaling behavior not only
exhibits in the equilibrium stage at the long-time limit, but also manifests
itself in the non-equilibrium relaxation process. While the critical behavior
is dictated by the low-lying energy levels of the Hamiltonian, the dissipative
part in the Lindblad equation also plays important roles in two aspects: First,
the dissipative part makes the high energy levels decay fast after which the
universal behavior controlled by the low-lying modes emerges. Second, the
dissipation rate gives rise to a time scale that affects the scaling behavior.
We confirm our theory by solving the Lindblad equation for the one-dimensional
transverse-field Ising model.


title:
Testing the strong equivalence principle with the triple pulsar PSR
  J0337+1715

abstract:
  Three conceptually different masses appear in equations of motion for objects
under gravity, namely, the inertial mass, $m_{\cal I}$, the passive
gravitational mass, $m_{\cal P}$, and the active gravitational mass, $m_{\cal
A}$. It is assumed that, for any objects, $m_{\cal I} = m_{\cal P} = m_{\cal
A}$ in the Newtonian gravity, and $m_{\cal I} = m_{\cal P}$ in the Einsteinian
gravity, oblivious to objects' sophisticated internal structure. Empirical
examination of the equivalence probes deep into gravity theories. We study the
possibility of carrying out new tests based on pulsar timing of the stellar
triple system, PSR J0337+1715. Various machine-precision three-body simulations
are performed, from which, the equivalence-violating parameters are extracted
with Markov chain Monte Carlo sampling that takes full correlations into
account. We show that the difference in masses could be probed to
$3\times10^{-8}$, improving the current constraints from lunar laser ranging on
the post-Newtonian parameters that govern violations of $m_{\cal P}=m_{\cal I}$
and $m_{\cal A}=m_{\cal P}$ by thousands and millions, respectively. The test
of $m_{\cal P}=m_{\cal A}$ would represent the first test of Newton's third law
with compact objects.


title: Zero mass case for a fractional Berestycki-Lions type problem

abstract:
  In this work we study the following fractional scalar field equation
\begin{equation*}\label{P} \left\{ \begin{array}{ll} (-\Delta)^{s} u = g'(u)
\mbox{ in } \mathbb{R}^{N} \\ u> 0 \end{array} \right. \end{equation*} where
$N\geq 2$, $s\in (0,1)$, $(-\Delta)^{s}$ is the fractional Laplacian and the
nonlinearity $g\in C^{2}(\mathbb{R})$ is such that $g''(0)=0$. By using
variational methods, we prove the existence of a positive solution which is
spherically symmetric and decreasing in $r=|x|$.


title:
Teaching assistants' beliefs regarding example solutions in introductory
  physics

abstract:
  As part of a larger study to understand instructors' considerations regarding
the learning and teaching of problem solving in an introductory physics course,
we investigated beliefs of first-year graduate teaching assistants (TAs)
regarding the use of example solutions in introductory physics. In particular,
we examine how the goal of promoting expert-like problem solving is manifested
in the considerations of graduate TAs choices of example solutions. Twenty-four
first-year graduate TAs were asked to discuss their goals for presenting
example solutions to students. They were also provided with different example
solutions and asked to discuss their preferences for prominent solution
features. TAs' awareness, preferences and actual practices related to solution
features were examined in light of recommendations from the literature for the
modeling of expert-like problem solving approaches. The study concludes that
the goal of helping students develop an expert-like problem solving approach
underlies many TAs' considerations for the use of example solutions. TAs,
however, do not notice and do not use many features described in the research
literature as supportive of this goal. A possible explanation for this gap
between their belief and practices is that these features conflict with another
powerful set of values concerned with keeping students engaged, setting
adequate standards, as well as pragmatic considerations such as time
requirements and the assignment of grades.


title:
Some abstract versions of G\"odel's second incompleteness theorem based
  on non-classical logics

abstract:
  We study abstract versions of G\"odel's second incompleteness theorem and
formulate generalizations of L\"ob's derivability conditions that work for
logics weaker than the classical one. We isolate the role of contraction rule
in G\"odel's theorem and give a (toy) example of a system based on modal logic
without contraction invalidating G\"odel's argument.


title: Invariance Under Bounded Analytic Functions

abstract:
  In a recent paper, M. Raghupathi has extended the famous theorem of Beurling
to the context of subspaces that are invariant under the class of subalgebras
of $H^\infty$ of the form $IH^\infty$, where $I$ is an inner function. In this
paper, we provide analouges of the above mentioned $IH^\infty$ related
extension of Beurling's theorem to the context of uniform algebras, on compact
abelian groups with ordered duals, the Lebesgue space on the real line and in
the setting of the space $BMOA$. We also provide a significant simplification
of the proof of the Beurling's theorem in the setting of uniform algebras and a
new proof of the Helson-Lowdenslager theorem that generalizes Beurling's
theorem in the context of compact abelian groups with ordered duals.


title: A mystery of black-hole gravitational resonances

abstract:
  More than three decades ago, Detweiler provided an analytical formula for the
gravitational resonant frequencies of rapidly-rotating Kerr black holes. In the
present work we shall discuss an important discrepancy between the famous {\it
analytical} prediction of Detweiler and the recent {\it numerical} results of
Zimmerman et. al. In addition, we shall refute the claim that recently appeared
in the physics literature that the Detweiler-Teukolsky-Press resonance equation
for the characteristic gravitational eigenfrequencies of rapidly-rotating Kerr
black holes is not valid in the regime of damped quasinormal resonances with
$\Im\omega/T_{\text{BH}}\gg1$ (here $\omega$ and $T_{\text{BH}}$ are
respectively the characteristic quasinormal resonant frequency of the Kerr
black hole and its Bekenstein-Hawking temperature). The main goal of the
present paper is to highlight and expose this important {\it black-hole
quasinormal mystery} (that is, the intriguing discrepancy between the
analytical and numerical results regarding the gravitational quasinormal
resonance spectra of rapidly-rotating Kerr black holes).


title:
Dynamic Modelling of Health and its application to the large scale
  analysis of Body Mass Index, using data from consecutive set of surveys

abstract:
  The methods used so far for the analysis of time changes in population health
suffer from the lack of causality in their design. This results in problems
with their implementation and interpretation. Here the method is presented with
causality directly implemented in the design. This is done by, first, building
up a dynamic model of population, postulating existence of Driving Force acting
at subjects, while they move along their cohort lines, causing the changes of
their substantial health indicators , State Variables, at rate proportional to
this Force. The correspondent rates , named Cohort Trends, or C-trends,
describe health history in each birth cohort. Having initial value and C-trends
, the model allows to calculate health level (the means of State Variables) in
each birth cohort, and thus, in the whole population. The task for statistical
method is to identify the dynamic model (evaluate C-trends and Initial values)
using data from a set of consecutive independent cross-sectional surveys. This
is done by an iterative algorithm, running multiple regression procedure at
each step, until the specified smoothing conditions are fulfilled. The
algorithm can operate with surveys having different age ranges. The
illustrative example shows the results of analysis of Body Mass Index for men ,
using 7 surveys in period 1972-2002 with age ranges 25-64 and 25-74. Since
C-Trend is proxy for Driving Force, the year - age pattern of C-Trends provides
unbiased information for health authorities on efficiency of health promotion
actions or negative effects of uncontrolled harmful factors.


title:
On the Zariski multiplicity conjecture for weighted homogeneous and
  Newton non-degenerate line singularities

abstract:
  We present new families of weighted homogeneous and Newton non-degenerate
line singularities that satisfy the Zariski multiplicity conjecture.


title: High-energy electroproduction in an atomic field

abstract:
  The differential cross section of high-energy electroproduction in the
electric field of heavy atoms is derived. The result is obtained with the exact
account of the atomic field by means of the quasiclassical approximation to the
wave functions in the external field. The Coulomb corrections substantially
modify the differential cross section compared with the Born result. They lead
to the azimuth asymmetry in the differential cross section for the polarized
incoming electron. The Coulomb corrections to the total cross section are
obtained in the leading logarithmic approximation.


title:
New Boys and Girls in Phosphorene Family from Gene Recombination:
  Different from Parents, Excellent than Parents

abstract:
  Based on the crystal structures of the previously proposed low energy
phosphorene allotropes {\eta}-P and {\theta}-P (Nano. Lett. 2015, 15, 3557), we
propose five new structural stable phosphorene boys (XX-XY or XY-XY) and girls
(XX-XX) through gene (XY from {\eta}-P and XX from {\theta}-P) recombination
methods. All of these five new phosphorene allotropes are obviously different
from their parents, showing very different and fascinating two-dimensional
patterns between each other. The dynamical stabilities of these phosphorene
allotropes are confirmed positive and some of them are confirmed energetically
more favorable than their parents ({\eta}-P and {\theta}-P). Especially, the
XX-XX type girl G1-P is confirmed energetically more favorable than all the
previously proposed phosphorene allotropes, including black phosphorene
({\alpha}-P, ACS Nano, 2014, 8, 4033) and blue phosphorene ({\beta}-P, Phys.
Rev. Lett. 2014, 112, 176802), which is expected to be synthesized in future
experiment through vapor deposition. Our results show that such a new promising
phosphorene allotrope G1-P is an excellent candidate for potential applications
in nano-electronics according to its middle band gap about 1.58 eV from
DFT-HSE06 calculation.


title:
Note on four-particle form factors of operators $T_{2n}T_{-2n}$ in
  sinh-Gordon model

abstract:
  The diagonal matrix elements
$\langle\theta_1,\theta_2|T_{2n}T_{-2n}|\theta_1,\theta_2\rangle$ between
two-particle states in the sinh-Gordon model are computed analytically for all
integers $n>0$. This confirms the proposal by F. Smirnov and A. Zamolodchikov
for these matrix elements and demonstrates effectiveness of the algebraic
approach to form factors.


title:
Smooth actions of $Aff^+ (\mathbb R)$ on compact surfaces with no fixed
  point: an elementary construction

abstract:
  Any compact surface supports a continuous action of the orientation
preserving affine group of the real line which is fixed point free (Lima and
Plante). It is generally admitted that this action can be taken smooth although
it is not easy finding references for it. Here one gives a such action.


title: Optimal strategies for a time-dependent harvesting problem

abstract:
  We focus on an optimal control problem, introduced by Bressan and Shen as a
model for fish harvesting. We consider the time-dependent case and we establish
existence and uniqueness of an optimal strategy, and sufficient conditions for
optimality. We also consider a related differential game that models the
situation where there are several competing fish companies and we prove
existence of Nash equilibria. From the technical viewpoint, the most relevant
point is establishing the uniqueness result. This amounts to prove precise
a-priori estimates for solutions of suitable parabolic equations with
measure-valued coefficients. All the analysis is developed in the case when the
fishing domain is one-dimensional.


title: Periodicity and decidability of tilings of $\mathbb{Z}^{2}$

abstract:
  We prove that any finite set $F\subset {\mathbb{Z}^2}$ that tiles
${\mathbb{Z}^2}$ by translations also admits a periodic tiling. As a
consequence, the problem whether a given finite set $F$ tiles ${\mathbb{Z}^2}$
is decidable.


title:
A simple and straightforward technique for single shot measurement of
  terahertz profile

abstract:
  A new detection scheme capable of acquiring the entire spatiotemporal profile
of terahertz radiation in a single laser shot is being demonstrated. The design
allows temporal resolution of the order of transform-limited pulse duration of
the probe, which is an absolute benefit over the compromised resolution of
otherwise prevalent single-shot detection schemes based on spectral encoding of
terahertz waveform on a temporally chirped readout pulse. This makes the
technique perfectly suitable for sensitive spectroscopy studies. The single
shot detection technique presented here relies on space-to-time mapping of
terahertz temporal profile by use of a converging probe intensity front. The
present approach does not require any specialized optics and is implemented
using very straightforward alignment procedure. It has shown to reproduce the
temporal waveform of terahertz radiation faithfully.


title:
Simultaneous, inherently temperature and strain insensitive bio-sensors
  based on dual-resonance long-period gratings

abstract:
  Addressing the temperature and strain induced cross-talks simultaneously, we
propose an inherently strain and temperature insensitive fiber-optic
bio-sensor. The insensitivity has been achieved by properly adjusting the
dopants and their concentrations in the optical fiber core region, and by
optimizing the grating period and the strength of concatenated dual-resonance
long-period-gratings. The simulations have been carried out using the same
fiber parameters as used in our earlier experimental studies, which matched
excellently with the experimental results. The proposed sensor has a
theoretical refractive-index sensitivity of 4607 nm/RIU, which can be used to
detect changes as small as 2.2 x10^-7 in ambient refractive indices using a
detection system with spectral resolution of 1 pm. Our work finds application
in developing precision biosensors with inherent insensitivity towards
temperature and axial strain fluctuations. The sensor is currently under
fabrication at our lab.


title:
Channel Covariance Estimation in Massive MIMO Frequency Division Duplex
  Systems

abstract:
  Channel covariance is emerging as a critical ingredient of the acquisition of
instantaneous channel state information (CSI) in multi-user Massive MIMO
systems operating in frequency division duplex (FDD) mode. In this context,
channel reciprocity does not hold, and it is generally expected that covariance
information about the downlink channel must be estimated and fed back by the
user equipment (UE). As an alternative CSI acquisition technique, we propose to
infer the downlink covariance based on the observed uplink covariance. This
inference process relies on a dictionary of uplink/downlink covariance
matrices, and on interpolation in the corresponding Riemannian space; once the
dictionary is known, the estimation does not rely on any form of feedback from
the UE. In this article, we present several variants of the interpolation
method, and benchmark them through simulations.


title:
Multilinear fractional integral operators on non-homogeneous metric
  measure spaces

abstract:
  Let $(X,d,\mu)$ be a non-homogeneous metric measure space satisfying both the
geometrically doubling and the upper doubling measure conditions. In this
paper, the boundedness of multilinear fractional integral operator in this
setting is proved. Via a sharp maximal operator, the boundedness of commutators
generated by multilinear fractional integral operator with $RBMO(\mu)$ function
on non-homogeneous metric measure spaces in Lebesgue spaces is obtained.


title:
The $Re$-number dependence of the longitudinal dispersion in a turbulent
  channel flow

abstract:
  In Taylor's theory, the longitudinal dispersion in turbulent pipe flows
approaches, on long timescales, a diffusive behavior with a constant
diffusivity $K_L$, that depends \emph{empirically} on the Reynolds number $Re$.
We show that the dependence on $Re$ can be determined from the turbulent energy
spectrum. By using the intimate connection between the friction factor and
longitudinal dispersion in wall-bounded turbulence, we predict different
asymptotic scaling laws of $K_L(Re)$ depending on the different turbulent
cascades in two-dimensional turbulence. We also explore numerically the
$K_L(Re)$ dependence in turbulent channel flows with smooth and rough walls
using a lattice Boltzmann method.


title: Benchmarking Measures of Network Influence

abstract:
  Identifying key agents for the transmission of diseases (ideas, technology,
etc.) across social networks has predominantly relied on measures of centrality
on a static base network or a temporally flattened graph of agent interactions.
Various measures have been proposed as the best trackers of influence, such as
degree centrality, betweenness, and $k$-shell, depending on the structure of
the connectivity. We consider SIR and SIS propagation dynamics on a
temporally-extruded network of observed interactions and measure the
conditional marginal spread as the change in the magnitude of the infection
given the removal of each agent at each time: its temporal knockout (TKO)
score. We argue that the exhaustive approach of the TKO score makes it an
effective benchmark measure for evaluating the accuracy of other, often more
practical, measures of influence. We find that none of the common network
measures applied to the induced flat graphs are accurate predictors of network
propagation influence on the systems studied; however, temporal networks and
the TKO measure provide the requisite targets for the hunt for effective
predictive measures.


title:
On the gaps between non-zero Fourier coefficients of cusp forms of
  higher weight

abstract:
  We show that if a modular cuspidal eigenform $f$ of weight $2k$ is
$2$-adically close to an elliptic curve $E/\mathbb{Q}$, which has a cyclic
rational $4$-isogeny, then $n$-th Fourier coefficient of $f$ is non-zero in the
short interval $(X, X + cX^{\frac{1}{4}})$ for all $X \gg 0$ and for some $c >
0$. We use this fact to produce non-CM cuspidal eigenforms $f$ of level $N>1$
and weight $k > 2$ such that $i_f(n) \ll n^{\frac{1}{4}}$ for all $n \gg 0$.


title:
Convergence order of upwind type schemes for transport equations with
  discontinuous coefficients

abstract:
  An analysis of the error of the upwind scheme for transport equation with
discontinuous coefficients is provided. We consider here a velocity field that
is bounded and one-sided Lipschitz continuous. In this framework, solutions are
defined in the sense of measures along the lines of Poupaud and Rascle's work.
We study the convergence order of the upwind scheme in the Wasserstein
distances. More precisely, we prove that in this setting the convergence order
is 1/2. We also show the optimality of this result. In the appendix, we show
that this result also applies to other "diffusive" "first order" schemes and to
a forward semi-Lagrangian scheme.


title: Curvature induced out of plane spin accumulation

abstract:
  In this work we show that (real space) curvature in the geometry of curved
waveguides with Rashba spin orbit interaction (RSOI) can lead to out of plane
spin accumulations. We first derive the RSOI Hamiltonian on arbitrarily curved
surfaces. We then analyze the effects of curvature with two distinct methods.
We first apply an adiabatic approximation on gently curved, planar waveguides
lying flat on the $xy$ plane to show that analogous to the acceleration of the
charge carriers by an electric field, the change in momentum direction of the
charge carriers as they move along the waveguide leads to an out of plane spin
accumulation. We then use the Heisenberg equations of motion to establish the
relationships between spin currents and accumulations on non-planar waveguides.
These relations predict the existence of out of plane spin accumulation on
asymmetrically curved, non-planar waveguides. We finally solve for the
eigenstates on such waveguides numerically, and present numerical results to
verify our earlier analytic predictions.


title: On cyclability of digraphs

abstract:
  Given a directed graph $D$ of order $n\geq 4$ and a nonempty subset $Y$ of
vertices of $D$ such that in $D$ every vertex of $Y$ reachable from every other
vertex of $Y$. Assume that for every triple $x,y,z\in Y$ such that $x$ and $y$
are nonadjacent: If there is no arc from $x$ to $z$, then
$d(x)+d(y)+d^+(x)+d^-(z)\geq 3n-2$. If there is no arc from $z$ to $x$, then
$d(x)+d(y)+d^+(z)+d^-(x)\geq 3n-2$. We prove that there is a directed cycle in
$D$ which contains all the vertices of $Y$, except possibly one. This result is
best possible in some sense and gives a answer to a question of H. Li, Flandrin
and Shu (Discrete Mathematics, 307 (2007) 1291-1297).


title:
Value-at-Risk and backtesting with the APARCH model and the standardized
  Pearson type IV distribution

abstract:
  We examine the efficiency of the Asymmetric Power ARCH (APARCH) model in the
case where the residuals follow the standardized Pearson type IV distribution.
The model is tested with a variety of loss functions and the efficiency is
examined via application of several statistical tests and risk measures. The
results indicate that the APARCH model with the standardized Pearson type IV
distribution is accurate, within the general financial risk modeling
perspective, providing the financial analyst with an additional skewed
distribution for incorporation in the risk management tools.


title: Extensions of vector-valued functions with preservation of derivatives

abstract:
  Let $X$ and $Y$ be Banach or normed linear spaces and $F\subset X$ a closed
set. We apply our recent extension theorem for vector-valued Baire one
functions arXiv:1512.03717 to obtain an extension theorem for vector-valued
functions $f\colon F\to Y$ with pre-assigned derivatives, with preservation of
differentiability (at every point where the pre-assigned derivative is actually
a derivative), preservation of continuity, preservation of (pointwise)
Lipschitz property and (for finite dimensional domain $X$) preservation of
strict differentiability and global (eventually local) Lipschitz continuity.


title: Human-Data Interaction in Healthcare

abstract:
  In this paper, we focus on an emerging strand of IT-oriented research, namely
Human-Data Interaction (HDI) and how this can be applied to healthcare. HDI
regards both how humans create and use data by means of interactive systems,
which can both assist and constrain them, as well as to passively collect and
proactively generate data. Healthcare provides a challenging arena to test the
potential of HDI to provide a new, user-centered perspective on how data work
should be supported and assessed, especially in the light of the fact that data
are becoming increasingly big and that many tools are now available for the lay
people, including doctors and nurses, to interact with health-related data.


title: Hydro-elastic Complementarity in Black Branes at large D

abstract:
  We obtain the effective theory for the non-linear dynamics of black
branes---both neutral and charged, in asymptotically flat or Anti-deSitter
spacetimes---to leading order in the inverse-dimensional expansion. We find
that black branes evolve as viscous fluids, but when they settle down they are
more naturally viewed as solutions of an elastic soap-bubble theory. The two
views are complementary: the same variable is regarded in one case as the
energy density of the fluid, in the other as the deformation of the elastic
membrane. The large-D theory captures finite-wavelength phenomena beyond the
conventional reach of hydrodynamics. For asymptotically flat charged black
branes (either Reissner-Nordstrom or p-brane-charged black branes) it yields
the non-linear evolution of the Gregory-Laflamme instability at large D and its
endpoint at stable non-uniform black branes. For Reissner-Nordstrom AdS black
branes we find that sound perturbations do not propagate (have purely imaginary
frequency) when their wavelength is below a certain charge-dependent value. We
also study the polarization of black branes induced by an external electric
field.


title: Overview of Annotation Creation: Processes & Tools

abstract:
  Creating linguistic annotations requires more than just a reliable annotation
scheme. Annotation can be a complex endeavour potentially involving many
people, stages, and tools. This chapter outlines the process of creating
end-to-end linguistic annotations, identifying specific tasks that researchers
often perform. Because tool support is so central to achieving high quality,
reusable annotations with low cost, the focus is on identifying capabilities
that are necessary or useful for annotation tools, as well as common problems
these tools present that reduce their utility. Although examples of specific
tools are provided in many cases, this chapter concentrates more on abstract
capabilities and problems because new tools appear continuously, while old
tools disappear into disuse or disrepair. The two core capabilities tools must
have are support for the chosen annotation scheme and the ability to work on
the language under study. Additional capabilities are organized into three
categories: those that are widely provided; those that often useful but found
in only a few tools; and those that have as yet little or no available tool
support.


title:
FESTUNG: A MATLAB / GNU Octave toolbox for the discontinuous Galerkin
  method. Part II: Advection operator and slope limiting

abstract:
  This is the second in a series of papers on implementing a discontinuous
Galerkin (DG) method as an open source Matlab / GNU Octave toolbox. The
intention of this ongoing project is to offer a rapid prototyping package for
application development using DG methods. The implementation relies on fully
vectorized matrix / vector operations and is comprehensively documented.
Particular attention was paid to maintaining a direct mapping between
discretization terms and code routines as well as to supporting the full code
functionality in GNU Octave. The present work focuses on a two-dimensional
time-dependent linear advection equation with space / time-varying
coefficients, and provides a general order implementation of several slope
limiting schemes for the DG method.


title:
Discrete diffraction managed solitons: Threshold phenomena and rapid
  decay for general nonlinearities

abstract:
  We prove a threshold phenomenon for the existence/non-existence of energy
minimizing solitary solutions of the diffraction management equation for
strictly positive and zero average diffraction. Our methods allow for a large
class of nonlinearities, they are, for example, allowed to change sign, and the
weakest possible condition, it only has to be locally integrable, on the local
diffraction profile. The solutions are found as minimizers of a nonlinear and
nonlocal variational problem which is translation invariant. There exists a
critical threshold ?cr such that minimizers for this variational problem exist
if their power is bigger than ?cr and no minimizers exist with power less than
the critical threshold. We also give simple criteria for the finiteness and
strict positivity of the critical threshold. Our proof of existence of
minimizers is rather direct and avoids the use of Lions' concentration
compactness argument.
  Furthermore, we give precise quantitative lower bounds on the exponential
decay rate of the diffraction management solitons, which confirm the physical
heuristic prediction for the asymptotic decay rate. Moreover, for ground state
solutions, these bounds give a quantitative lower bound for the divergence of
the exponential decay rate in the limit of vanishing average diffraction. For
zero average diffraction, we prove quantitative bounds which show that the
solitons decay much faster than exponentially. Our results considerably extend
and strengthen the results of [15] and [16].


title: Ultrastrong coupling phenomena beyond the Dicke model

abstract:
  We study effective light-matter interactions in a circuit QED system
consisting of a single $LC$ resonator, which is coupled symmetrically to
multiple superconducting qubits. Starting from a minimal circuit model, we
demonstrate that in addition to the usual collective qubit-photon coupling the
resulting Hamiltonian contains direct qubit-qubit interactions, which have a
drastic effect on the ground and excited state properties of such circuits in
the ultrastrong coupling regime. In contrast to a superradiant phase transition
expected from the standard Dicke model, we find an opposite mechanism, which at
very strong interactions completely decouples the photon mode and projects the
qubits into a highly entangled ground state. These findings resolve previous
controversies over the existence of superradiant phases in circuit QED, but
they more generally show that the physics of two- or multi-atom cavity QED
settings can differ significantly from what is commonly assumed.


title: A two-step approach to account for unobserved spatial heterogeneity

abstract:
  Empirical analysis in economics often faces the difficulty that the data is
correlated and heterogeneous in some unknown form. Spatial parametric
approaches have been widely used to account for dependence structures, but the
problem of directly deal with spatially varying parameters has been largely
unexplored. The problem can be serious in all those cases in which we have no
prior information justified by the economic theory. In this paper we propose an
algorithm-based procedure which is able to endogenously identify structural
breaks in space. The proposed algorithm is illustrated by using two well known
house price data sets.


title:
On optimal strategies for utility maximizers in the Arbitrage Pricing
  Model

abstract:
  We consider a popular model of microeconomics with countably many assets: the
Arbitrage Pricing Model. We study the problem of optimal investment under an
expected utility criterion and look for conditions ensuring the existence of
optimal strategies. Previous results required a certain restrictive hypothesis
on the tails of asset return distributions. Using a different method, we manage
to remove this hypothesis, at the price of stronger assumptions on the moments
of asset returns.


title: Realizing homology classes up to cobordism

abstract:
  It is known that neither immersions nor maps with a fixed finite set of
multisingularities are enough to realize all mod 2 homology classes in
manifolds. In this paper we define the notion of realizing a homology class up
to cobordism; it is shown that for realization in this weaker sense immersions
are sufficient, but maps with a fixed finite set of multisingularities are
still insufficient.


title:
The simplest map with three-frequency quasi-periodicity and
  quasi-periodic bifurcations

abstract:
  We propose a new three-dimensional map that demonstrates the two- and
three-frequency quasi-periodicity. For this map all basic quasi-periodic
bifurcations are possible. The study was realized by using method of Lyapunov
charts completed by plots of Lyapunov exponents, phase portraits and
bifurcation trees illustrating the quasi-periodic bifurcations. The features of
the three-parameter structure associated with quasi-periodic Hopf bifurcation
are discussed. The comparison with non-autonomous model is carried out.


title:
Consistency of direct integral estimator for partially observed systems
  of ordinary differential equations linear in the parameters

abstract:
  Dynamic systems are ubiquitous in nature and are used to model many processes
in biology, chemistry, physics, medicine, and engineering. In particular,
systems of ordinary differential equations are commonly used for the
mathematical modelling of the rate of change of dynamic processes. In many
practical applications, the process can only be partially measured, a fact that
renders estimation of parameters of the system extremely challenging. Recently,
a 'direct integral estimator' for partially observed systems of ordinary
differential equations was introduced. The practical performance of the
integral estimator was demonstrated, but its theoretical properties were not
derived. In this paper we use the sieve framework to prove that the estimator
is consistent.


title: Modelling Spatial Regimes in Farms Technologies

abstract:
  We exploit the information derived from geographical coordinates to
endogenously identify spatial regimes in technologies that are the result of a
variety of complex, dynamic interactions among site-specific environmental
variables and farmer decision making about technology, which are often not
observed at the farm level. Controlling for unobserved heterogeneity is a
fundamental challenge in empirical research, as failing to do so can produce
model misspecification and preclude causal inference. In this article, we adopt
a two-step procedure to deal with unobserved spatial heterogeneity, while
accounting for spatial dependence in a cross-sectional setting. The first step
of the procedure takes explicitly unobserved spatial heterogeneity into account
to endogenously identify subsets of farms that follow a similar local
production econometric model, i.e. spatial production regimes. The second step
consists in the specification of a spatial autoregressive model with
autoregressive disturbances and spatial regimes. The method is applied to two
regional samples of olive growing farms in Italy. The main finding is that the
identification of spatial regimes can help drawing a more detailed picture of
the production environment and provide more accurate information to guide
extension services and policy makers.


title:
Stellar Dynamics around a Massive Black Hole III: Resonant Relaxation of
  Axisymmetric Discs

abstract:
  We study the Resonant Relaxation (RR) of an axisymmetric low mass (or
Keplerian) stellar disc orbiting a more massive black hole (MBH). Our recent
work on the general kinetic theory of RR is simplified in the standard manner
by ignoring the effects of `gravitational polarization', and applied to a
zero-thickness, flat, axisymmetric disc. The wake of a stellar orbit is
expressed in terms of the angular momenta exchanged with other orbits, and used
to derive a kinetic equation for RR under the combined actions of self-gravity,
1 PN and 1.5 PN relativistic effects of the MBH and an arbitrary external
axisymmetric potential. This is a Fokker-Planck equation for the stellar
distribution function (DF), wherein the diffusion coefficients are given
self-consistently in terms of contributions from apsidal resonances between
pairs of stellar orbits. The physical kinetics is studied for the two main
cases of interest. (1) `Lossless' discs in which the MBH is not a sink of
stars, and disc mass, angular momentum and energy are conserved: we prove that
general H-functions can increase or decrease during RR, but the Boltzmann
entropy is (essentially) unique in being a non-decreasing function of time.
Therefore secular thermal equilibria are maximum entropy states, with DFs of
the Boltzmann form; the two-Ring correlation function at equilibrium is
computed. (2) Discs that lose stars to the MBH through an `empty loss-cone': we
derive expressions for the MBH feeding rates of mass, angular momentum and
energy in terms of the diffusive flux at the loss-cone boundary.


title:
Conformal transformations in modified teleparallel theories of gravity
  revisited

abstract:
  It is well known that one cannot apply a conformal transformation to $f(T)$
gravity to obtain a minimally coupled scalar field model, and thus no Einstein
frame exists for $f(T)$ gravity. Furthermore nonminimally coupled "teleparallel
dark energy models" are not conformally equivalent to $f(T)$ gravity. However,
it can be shown that $f(T)$ gravity is conformally equivalent to a teleparallel
phantom scalar field model with a nonminimal coupling to a boundary term only.
In this work, we extend this analysis by considering a recently studied
extended class of models, known as $f(T,B)$ gravity, where $B$ is a boundary
term related to the divergence of a contraction of the torsion tensor. We find
that nonminimally coupled "teleparallel dark energy models" are conformally
equivalent to either an $f(T,B)$ or $f(B)$ gravity model. Finally conditions on
the functional form of $f(T,B)$ gravity are derived to allow it to be
transformed to particular nonminimally coupled scalar field models.


title:
Entity Embeddings with Conceptual Subspaces as a Basis for Plausible
  Reasoning

abstract:
  Conceptual spaces are geometric representations of conceptual knowledge, in
which entities correspond to points, natural properties correspond to convex
regions, and the dimensions of the space correspond to salient features. While
conceptual spaces enable elegant models of various cognitive phenomena, the
lack of automated methods for constructing such representations have so far
limited their application in artificial intelligence. To address this issue, we
propose a method which learns a vector-space embedding of entities from
Wikipedia and constrains this embedding such that entities of the same semantic
type are located in some lower-dimensional subspace. We experimentally
demonstrate the usefulness of these subspaces as (approximate) conceptual space
representations by showing, among others, that important features can be
modelled as directions and that natural properties tend to correspond to convex
regions.


title:
Topological 2-generation of automorphism groups of countable
  ultrahomogeneous graphs

abstract:
  A countable graph is ultrahomogeneous if every isomorphism between finite
induced subgraphs can be extended to an automorphism. Woodrow and Lachlan
showed that there are essentially four types of such countably infinite graphs:
the random graph; infinite disjoint unions of complete graphs $K_n$ with $n\in
\mathbb{N}$ vertices; the $K_n$-free graphs; finite unions of the infinite
complete graph $K_{\omega}$; and duals of such graphs. The groups
$\operatorname{Aut}(\Gamma)$ of automorphisms of such graphs $\Gamma$ have a
natural topology, which is compatible with multiplication and inversion, i.e.\
the groups $\operatorname{Aut}(\Gamma)$ are topological groups. We consider the
problem of finding minimally generated dense subgroups of the groups
$\operatorname{Aut}(\Gamma)$ where $\Gamma$ is ultrahomogeneous. We show that
if $\Gamma$ is ultrahomogeneous, then $\operatorname{Aut}(\Gamma)$ has
2-generated dense subgroups, and that under certain conditions given $f \in
\operatorname{Aut}(\Gamma)$ there exists $g\in \operatorname{Aut}(\Gamma)$ such
that the subgroup generated by $f$ and $g$ is dense. We also show that, roughly
speaking, $g$ can be chosen with a high degree of freedom. For example, if
$\Gamma$ is either an infinite disjoint unions of $K_n$ or a finite union of
$K_{\omega}$, then $g$ can be chosen to have any given finite set of orbit
representatives.


title: Nonlinear Spinor Fields in Bianchi type-V spacetime

abstract:
  A self-consistent system of nonlinear spinor and Bianchi type-V anisotropic
gravitational fields are investigated. It is found that the presence of
nontrivial non-diagonal components of the energy-momentum tensor of the spinor
field imposes some severe restrictions to the system. As a result two different
solutions are found. In one case the metric functions are similar to each
other, i.e., $a_1 \sim a_2 \sim a_3$ and the spinor mass and spinor field
nonlinearity do not disappear from the system. In this case the spacetime
expands with acceleration in case of a positive self-coupling constant
$\lambda$. A negative $\lambda$ gives rise to a cyclic or periodical mode of
expansion. In the second case the spinor mass and the spinor field nonlinearity
vanish and the Universe expands linearly with time.