title:
Superconvergence properties of an upwind-biased discontinuous Galerkin
  method

abstract:
  In this paper we investigate the superconvergence properties of the
discontinuous Galerkin method based on the upwind-biased flux for linear
time-dependent hyperbolic equations. We prove that for even-degree polynomials,
the method is locally $\mathcal{O}(h^{k+2})$ superconvergent at roots of a
linear combination of the left- and right-Radau polynomials. This linear
combination depends on the value of $\theta$ used in the flux. For odd-degree
polynomials, the scheme is superconvergent provided that a proper global
initial interpolation can be defined. We demonstrate numerically that, for
decreasing $\theta$, the discretization errors decrease for even polynomials
and grow for odd polynomials. We prove that the use of Smoothness-Increasing
Accuracy-Conserving (SIAC) filters is still able to draw out the
superconvergence information and create a globally smooth and superconvergent
solution of $\mathcal{O}(h^{2k+1})$ for linear hyperbolic equations. Lastly, we
briefly consider the spectrum of the upwind-biased DG operator and demonstrate
that the price paid for the introduction of the parameter $\theta$ is limited
to a contribution to the constant attached to the post-processed error term.


title: On error sums formed by rational approximations with split denominators

abstract:
  In this paper we consider error sums of the form \[\sum_{m=0}^{\infty}
\varepsilon_m\Big( \,b_m\alpha - \frac{a_m}{c_m}\,\Big) \,,\] where $\alpha$ is
a real number, $a_m$, $b_m$, $c_m$ are integers, and $\varepsilon_m=1$ or
$\varepsilon_m ={(-1)}^m$. In particular, we investigate such sums for \[\alpha
\in \big\{ \pi, e,e^{1/2},e^{1/3},\dots, \log (1+t), \zeta(2), \zeta(3) \big\}
\] and exhibit some connections between rational coefficients occurring in
error sums for Ap\'ery's continued fraction for $\zeta(2)$ and well-known
integer sequences. The concept of the paper generalizes the theory of ordinary
error sums, which are given by $b_m=q_m$ and $a_m/c_m=p_m$ with the convergents
$p_m/q_m$ from the continued fraction expansion of $\alpha$.


title:
NuSTAR, Swift, and GROND observations of the flaring MeV blazar: PMN
  J0641$-$0320

abstract:
  MeV blazars are a sub--population of the blazar family, exhibiting
larger--than--average jet powers, accretion luminosities and black hole masses.
Because of their extremely hard X--ray continua, these objects are best studied
in the X-ray domain. Here, we report on the discovery by the $Fermi$ Large Area
Telescope and subsequent follow-up observations with $NuSTAR$, $Swift$ and
GROND of a new member of the MeV blazar family: PMN J0641$-$0320. Our optical
spectroscopy provides confirmation that this is a flat--spectrum radio quasar
located at a redshift of $z=1.196$. Its very hard $NuSTAR$ spectrum (power--law
photon index of $\sim$1 up to $\sim$80 keV) indicates that the emission is
produced via inverse Compton scattering off photons coming from outside the
jet.The overall spectral energy distribution of PMN J0641$-$0320 is typical of
powerful blazars and by reproducing it with a simple one-zone leptonic emission
model we find the emission region to be located either inside the broad line
region or within the dusty torus.


title: Dynamics of a bacterial flagellum under reverse rotation

abstract:
  To initiate tumbling of an E. coli, one of the helical flagella reverses its
sense of rotation. It then transforms from its normal form first to the
transient semicoiled state and subsequently to the curly-I state. The dynamics
of polymorphism is effectively modeled by describing flagellar elasticity
through an extended Kirchhoff free energy. However, the complete landscape of
the free energy remains undetermined because the ground state energies of the
polymorphic forms are not known. We investigate how variations in these ground
state energies affect the dynamics of a reversely rotated flagellum of a
swimming bacterium. We find that the flagellum exhibits a number of distinct
dynamical states and comprehensively summarize them in a state diagram. As a
result, we conclude that tuning the landscape of the extended Kirchhoff free
energy alone cannot generate the intermediate full-length semicoiled state.
However, our model suggests an ad hoc method to realize the sequence of
polymorphic states as observed for a real bacterium. Since the elastic
properties of bacterial flagella are similar, our findings can easily be
extended to other peritrichous bacteria.


title:
Inverse magnetic catalysis and confinement within a contact interaction
  model for quarks

abstract:
  We evaluate the impact of an external magnetic field on the chiral symmetry
and confinement-deconfinement transition temperatures by using a vector-vector
contact interaction model for quarks regularized so as to include an explicit
confining scale in the corresponding gap equation. Exploring the evolution of
the chiral condensate and the confining scale with temperature $T$ and magnetic
field strength $eB$ ($e$ represents the fundamental electric charge), we
determine the pseudo-critical temperatures for the chiral ($T_c^\chi$) and
deconfinement ($T_c^c$) transitions from their inflection points, respectively.
By construction, $T_c^\chi= T_c^c$ in the chiral limit. Within a mean field
approximation, we observe the magnetic catalysis phenomenon, characterized by a
rising behavior of $T_c^\chi$ and $T_c^c$ with growing $eB$. Considering a
lattice inspired running coupling which monotonically decreases with $eB$,
inverse magnetic catalysis takes place in our model. We explore the role of the
magnetic field in the traits of the confinement-deconfinement transition
described by the model. Our findings are also in agreement with predictions
derived from effective models of strong interactions.


title: Tree invariants and Milnor linking numbers with indeterminacy

abstract:
  The paper concerns the tree invariants of string links, introduced by
Kravchenko and Polyak and closely related to the classical Milnor linking
numbers also known as $\bar{\mu}$--invariants. We prove that, analogously as
for $\bar{\mu}$--invariants, certain residue classes of tree invariants yield
link homotopy invariants of closed links. The proof is arrow diagramatic and
provides a more geometric insight into the indeterminacy through certain tree
stacking operations. Further, we show that the indeterminacy of tree invariants
is consistent with the original Milnor's indeterminacy. For practical purposes,
we also provide a recursive procedure for computing arrow polynomials of tree
invariants.


title: Investigations of Higher Order Links

abstract:
  The following is an amalgamation of four preprints and some computer programs
which together represent the current state of our investigations of higher
order links. This investigation was motivated by questions discussed and raised
in the first author's paper "New States of Matter Suggested by New Topological
Structures". An important motivation has been to suggest the synthesis of new
types of molecules (see the relevant articles listed in the bibliography). This
discussion is not final, but we think that the results and methods are worth
making public and would be useful for other investigators.


title: Whittaker functions and Demazure characters

abstract:
  In this paper, we consider how to express an Iwahori--Whittaker function
through Demazure characters. Under some interesting combinatorial conditions,
we obtain an explicit formula and thereby a generalization of the
Casselman--Shalika formula. Under the same conditions, we compute the
transition matrix between two natural bases for the space of Iwahori fixed
vectors of an induced representation of a p-adic group; this generalizes a
result of Bump--Nakasuji.


title:
Thick Disks, and an Outflow, of Dense Gas in the Nuclei of Nearby
  Seyfert Galaxies

abstract:
  We discuss the dense molecular gas in central regions of nearby Seyfert
galaxies, and report new arcsec resolution observations of HCN(1-0) and
HCO$^+$(1-0) for 3 objects. In NGC 3079 the lines show complex profiles as a
result of self-absorption and saturated continuum absorption. H$^{13}$CN
reveals the continuum absorption profile, with a peak close to the galaxy's
systemic velocity that traces disk rotation, and a second feature with a blue
wing extending to $-350$km s$^{-1}$ that most likely traces a nuclear outflow.
The morphological and spectral properties of the emission lines allow us to
constrain the dense gas dynamics. We combine our kinematic analysis for these 3
objects, as well as another with archival data, with a previous comparable
analysis of 4 other objects, to create a sample of 8 Seyferts. In 7 of these,
the emission line kinematics imply thick disk structures on radial scales of
$\sim$100pc, suggesting such structures are a common occurrence. We find a
relation between the circumnuclear LHCN and Mdyn that can be explained by a gas
fraction of 10% and a conversion factor {\alpha}HCN $\sim$ 10 between gas mass
and HCN luminosity. Finally, adopting a different perspective to probe the
physical properties of the gas around AGN, we report on an analysis of
molecular line ratios which indicates that the clouds in this region are not
self-gravitating.


title:
Developing a Repeating Model Using the Structured Spreadsheet Modelling
  and Implementation Methodology

abstract:
  Spreadsheets often have variables and formulas that are similar, differing
only by the fact that they refer to different instances of an entity. For
example, the calculation of the sales revenues of the South and East regions
are Revenues South = Price * Quantity Sold South and Revenues East = Price *
Quantity Sold East. In this paper, we present a conceptual modelling approach
that takes advantage of these similarities and leads the spreadsheet developer
to the formula Revenues = Price * Quantity. We then present simple but strict
rules to implement the spreadsheet.


title: Web Item Reviewing Made Easy By Leveraging Available User Feedback

abstract:
  The widespread use of online review sites over the past decade has motivated
businesses of all types to possess an expansive arsenal of user feedback to
mark their reputation. Though a significant proportion of purchasing decisions
are driven by average rating, detailed reviews are critical for activities like
buying expensive digital SLR camera. Since writing a detailed review for an
item is usually time-consuming, the number of reviews available in the Web is
far from many. Given a user and an item our goal is to identify the top-$k$
meaningful phrases/tags to help her review the item easily. We propose
general-constrained optimization framework based on three measures - relevance
(how well the result set of tags describes an item), coverage (how well the
result set of tags covers the different aspects of an item), and polarity (how
well sentiment is attached to the result set of tags). By adopting different
definitions of coverage, we identify two concrete problem instances that enable
a wide range of real-world scenarios. We develop practical algorithms with
theoretical bounds to solve these problems efficiently. We conduct experiments
on synthetic and real data crawled from the web to validate the effectiveness
of our solutions.


title:
On the bicycle transformation and the filament equation: results and
  conjectures

abstract:
  The paper concerns a simple model of bicycle kinematics: a bicycle is
represented by an oriented segment of constant length in n-dimensional space
that can move in such a way that the velocity of its rear end is aligned with
the segment (the rear wheel is fixed on the bicycle frame). Starting with a
closed trajectory of the rear end, one obtains the two respective trajectories
of the front end, corresponding to the opposite directions of motion. These two
curves are said to be in the bicycle correspondence. Conjecturally, this
correspondence is completely integrable; we present a number of results
substantiating this conjecture. In dimension three, the bicycle correspondence
is the Backlund transformation for the filament equation; we discuss
bi-Hamiltonian features of the bicycle correspondence and its integrals.


title:
Millimeter Wave Vehicular Communication to Support Massive Automotive
  Sensing

abstract:
  As driving becomes more automated, vehicles are being equipped with more
sensors generating even higher data rates. Radars (RAdio Detection and Ranging)
are used for object detection, visual cameras as virtual mirrors, and LIDARs
(LIght Detection and Ranging) for generating high resolution depth associated
range maps, all to enhance the safety and efficiency of driving. Connected
vehicles can use wireless communication to exchange sensor data, allowing them
to enlarge their sensing range and improve automated driving functions.
Unfortunately, conventional technologies, such as dedicated short-range
communication (DSRC) and 4G cellular communication, do not support the
gigabit-per-second data rates that would be required for raw sensor data
exchange between vehicles. This paper makes the case that millimeter wave
(mmWave) communication is the only viable approach for high bandwidth connected
vehicles. The motivations and challenges associated with using mmWave for
vehicle-to-vehicle and vehicle-to-infrastructure applications are highlighted.
A high-level solution to one key challenge - the overhead of mmWave beam
training - is proposed. The critical feature of this solution is to leverage
information derived from the sensors or DSRC as side information for the mmWave
communication link configuration. Examples and simulation results show that the
beam alignment overhead can be reduced by using position information obtained
from DSRC.


title:
Module structure of the center of the universal central extension of a
  genus zero Krichever-Novikov algebra

abstract:
  We describe how the center of the universal central extension of the genus
zero Krichever-Novikov current algebra decomposes as a direct sum of
irreducible modules for automorphism group of the coordinate ring of this
algebra.


title:
Causes for Query Answers from Databases, Datalog Abduction and
  View-Updates: The Presence of Integrity Constraints

abstract:
  Causality has been recently introduced in databases, to model, characterize
and possibly compute causes for query results (answers). Connections between
queryanswer causality, consistency-based diagnosis, database repairs (wrt.
integrity constraint violations), abductive diagnosis and the view-update
problem have been established. In this work we further investigate connections
between query-answer causality and abductive diagnosis and the view-update
problem. In this context, we also define and investigate the notion of
query-answer causality in the presence of integrity constraints.


title:
Frozen Gaussian approximation with surface hopping for mixed
  quantum-classical dynamics: A mathematical justification of fewest switches
  surface hopping algorithms

abstract:
  We develop a surface hopping algorithm based on frozen Gaussian approximation
for semiclassical matrix Schr\"odinger equations, in the spirit of Tully's
fewest switches surface hopping method. The algorithm is asymptotically derived
from the Schr\"odinger equation with rigorous approximation error analysis. The
resulting algorithm can be viewed as a path integral stochastic representation
of the semiclassical matrix Schr\"odinger equations. Our results provide
mathematical understanding to and shed new light on the important class of
surface hopping methods in theoretical and computational chemistry.


title: Wheeled Robots playing Chain Catch: Strategies and Evaluation

abstract:
  Robots playing games that humans are adept in is a challenge. We studied
robotic agents playing Chain Catch game as a Multi-Agent System (MAS). Our game
starts with a traditional Catch game similar to Pursuit evasion, and further
extends it to form a growing chain of predator agents to chase remaining preys.
Hence Chain Catch is a combination of two challenges - pursuit domain and
robotic chain formation. These are games that require team of robotic agents to
cooperate among themselves and to compete with other group of agents through
quick decision making. In this paper, we present a Chain Catch simulator that
allows us to incorporate game rules, design strategies and simulate the game
play. We developed cost model driven strategies for each of Escapee, Catcher
and Chain. Our results show that Sliding slope strategy is the best strategy
for Escapees whereas Tagging method is the best method for chain s movement in
Chain Catch. We also use production quality robots to implement the game play
in a physical environment and analyze game strategies on real robots. Our real
robots implementation in different scenarios shows that game strategies work as
expected and a complete chain formation takes place successfully in each game.


title:
Undermining and Strengthening Social Networks through Network
  Modification

abstract:
  Social networks have well documented effects at the individual and aggregate
level. Consequently it is often useful to understand how an attempt to
influence a network will change its structure and consequently achieve other
goals. We develop a framework for network modification that allows for
arbitrary objective functions, types of modification (e.g. edge weight
addition, edge weight removal, node removal, and covariate value change), and
recovery mechanisms (i.e. how a network responds to interventions). The
framework outlined in this paper helps both to situate the existing work on
network interventions but also opens up many new possibilities for intervening
in networks. In particular use two case studies to highlight the potential
impact of empirically calibrating the objective function and network recovery
mechanisms as well as showing how interventions beyond node removal can be
optimised. First, we simulate an optimal removal of nodes from the Noordin
terrorist network in order to reduce the expected number of attacks (based on
empirically predicting the terrorist collaboration network from multiple types
of network ties). Second, we simulate optimally strengthening ties within
entrepreneurial ecosystems in six developing countries. In both cases we
estimate ERGM models to simulate how a network will endogenously evolve after
intervention.


title: The Singularity May Never Be Near

abstract:
  There is both much optimism and pessimism around artificial intelligence (AI)
today. The optimists are investing millions of dollars, and even in some cases
billions of dollars into AI. The pessimists, on the other hand, predict that AI
will end many things: jobs, warfare, and even the human race. Both the
optimists and the pessimists often appeal to the idea of a technological
singularity, a point in time where machine intelligence starts to run away, and
a new, more intelligent species starts to inhabit the earth. If the optimists
are right, this will be a moment that fundamentally changes our economy and our
society. If the pessimists are right, this will be a moment that also
fundamentally changes our economy and our society. It is therefore very
worthwhile spending some time deciding if either of them might be right.


title:
Simultaneous Evidence for Pauli Paramagnetic Effects and Multiband
  Superconductivity in KFe$_2$As$_2$ by Small-Angle Neutron Scattering Studies
  of the Vortex Lattice

abstract:
  We study the intrinsic anisotropy of the superconducting state in
KFe$_2$As$_2$, using small-angle neutron scattering to image the vortex lattice
as the applied magnetic field is rotated towards the FeAs crystalline planes.
The anisotropy is found to be strongly field dependent, indicating multiband
superconductivity. Furthermore, the high field anisotropy significantly exceeds
that of the upper critical field, providing further support for Pauli limiting
in KFe$_2$As$_2$ for field applied in the basal plane. The effect of Pauli
paramagnetism on the unpaired quasiparticles in the vortex cores is directly
evident from the ratio of scattered intensities due to the longitudinal and
transverse vortex lattice field modulation.


title: The L-Functions Have Only Simple Non Trivial Zeros

abstract:
  By using an analogy with the case of very close zeros symmetric with respect
to the critical line of the Davenport and Heilbronn function, we study the
conformal mapping of L-functions in a neighborhood of a hypothetical double
zero and conclude that such a zero cannot exist.
  Keywords: Riemann Hypothesis, non trivial zeros, Ghisa's strips, Ghisa's
fundamental domains, Ghisa's intertwined curves
  2010 Mathematics Subject Classification: 30C35; 11M26


title: Creating Airy beams employing a transmissive spatial light modulator

abstract:
  We present a detailed study of two novel methods for shaping the light
optical wavefront by employing a transmissive spatial light modulator (SLM).
Conventionally, optical Airy beams are created by employing SLMs in the
so-called all phase mode. In the first method, a numerically simulated lens
phase distribution is loaded directly onto the SLM, together with the cubic
phase distribution. An Airy beam is generated at the focal plane of the
numerical lens. We provide for the first time a quantitative properties of the
formed Airy beam. We derive the formula for deflection of the intensity maximum
of the so formed Airy beam, which is different to the quadratic deflection
typical of Airy beams. We cross-validate the derived formula by both
simulations and experiment. The second method is based on the fact that a
system consisting of a transmissive SLM sandwiched between two polarisers can
create a transmission function with negative values. This observation alone has
the potential for various other wavefront modulations where the transmission
function requires negative values. As an example for this method, we
demonstrate that a wavefront can be modulated by passing the SLM system with
transmission function with negative values by loading an Airy function
distribution directly onto SLM. Since the Airy function is a real-valued
function but also with negative values, an Airy beam can be generated by direct
transfer of the Airy function distribution onto such an SLM system. In this
way, an Airy beam is generated immediately behind the SLM. As both new methods
do not employ a physical lens, the two setups are more compact than
conventional setups for creating Airy beams. We compare the performance of the
two novel methods and the properties of the created Airy beams.


title: Analysis of animal accelerometer data using hidden Markov models

abstract:
  Use of accelerometers is now widespread within animal biotelemetry as they
provide a means of measuring an animal's activity in a meaningful and
quantitative way where direct observation is not possible. In sequential
acceleration data there is a natural dependence between observations of
movement or behaviour, a fact that has been largely ignored in most analyses.
Analyses of acceleration data where serial dependence has been explicitly
modelled have largely relied on hidden Markov models (HMMs). Depending on the
aim of an analysis, either a supervised or an unsupervised learning approach
can be applied. Under a supervised context, an HMM is trained to classify
unlabelled acceleration data into a finite set of pre-specified categories,
whereas we will demonstrate how an unsupervised learning approach can be used
to infer new aspects of animal behaviour. We will provide the details necessary
to implement and assess an HMM in both the supervised and unsupervised context,
and discuss the data requirements of each case. We outline two applications to
marine and aerial systems (sharks and eagles) taking the unsupervised approach,
which is more readily applicable to animal activity measured in the field. HMMs
were used to infer the effects of temporal, atmospheric and tidal inputs on
animal behaviour. Animal accelerometer data allow ecologists to identify
important correlates and drivers of animal activity (and hence behaviour). The
HMM framework is well suited to deal with the main features commonly observed
in accelerometer data. The ability to combine direct observations of animals
activity and combine it with statistical models which account for the features
of accelerometer data offer a new way to quantify animal behaviour, energetic
expenditure and deepen our insights into individual behaviour as a constituent
of populations and ecosystems.


title: On noise-induced synchronization and consensus

abstract:
  In this paper, we present new results for the synchronization and consensus
of networks described by Ito stochastic differential equations. From the
methodological viewpoint, our results are based on the use of stochastic
Lyapunov functions. This approach allowed us to consider networks where nodes
dynamics can be nonlinear and non-autonomous and where noise is not just
additive but rather its diffusion can be nonlinear and depend on the network
state. We first present a sufficient condition on the coupling strength and
topology ensuring that a network synchronizes (fulfills consensus) despite
noise. Then, we show that noise can be useful, and present a result showing how
to design noise so that it induces synchronization/consensus. Motivated by our
current research in Smart Cities and Internet of Things, we also illustrate the
effectiveness of our approach by showing how our results can be used to
analyze/control the onset of synchronization in noisy networks and to study
collective decision processes.


title: FLASH: Fast Bayesian Optimization for Data Analytic Pipelines

abstract:
  Modern data science relies on data analytic pipelines to organize
interdependent computational steps. Such analytic pipelines often involve
different algorithms across multiple steps, each with its own hyperparameters.
To achieve the best performance, it is often critical to select optimal
algorithms and to set appropriate hyperparameters, which requires large
computational efforts. Bayesian optimization provides a principled way for
searching optimal hyperparameters for a single algorithm. However, many
challenges remain in solving pipeline optimization problems with
high-dimensional and highly conditional search space. In this work, we propose
Fast LineAr SearcH (FLASH), an efficient method for tuning analytic pipelines.
FLASH is a two-layer Bayesian optimization framework, which firstly uses a
parametric model to select promising algorithms, then computes a nonparametric
model to fine-tune hyperparameters of the promising algorithms. FLASH also
includes an effective caching algorithm which can further accelerate the search
process. Extensive experiments on a number of benchmark datasets have
demonstrated that FLASH significantly outperforms previous state-of-the-art
methods in both search speed and accuracy. Using 50% of the time budget, FLASH
achieves up to 20% improvement on test error rate compared to the baselines.
FLASH also yields state-of-the-art performance on a real-world application for
healthcare predictive modeling.


title:
Optimal control of infinite dimensional bilinear systems: Application to
  the heat and wave equations

abstract:
  In this paper we consider second order optimality conditions for a bilinear
optimal control problem governed by a strongly continuous semigroup operator,
the control entering linearly in the cost function. We derive first and second
order optimality conditions, taking advantage of the Goh transform. We then
apply the results to the heat and wave equations.


title: Stochastic areas, Winding numbers and Hopf fibrations

abstract:
  We define and study stochastic areas processes associated with Brownian
motions on the complex symmetric spaces $\mathbb{CP}^n$ and $\mathbb{CH}^n$.
The characteristic functions of those processes are computed and limit theorems
are obtained. In the case $n=1$, we also study windings of the Brownian motion
on those spaces and compute the limit distributions. For $\mathbb{CP}^n$ the
geometry of the Hopf fibration plays a central role, whereas for
$\mathbb{CH}^n$ it is the anti-de Sitter fibration.


title: Refined descendant invariants of toric surfaces

abstract:
  We construct refined tropical enumerative genus zero invariants of toric
surfaces that specialize to the tropical descendant genus zero invariants
introduced by Markwig and Rau when the quantum parameter tends to $1$. In the
case of trivalent tropical curves our invariants turn to be the
Goettsche-Schroeter refined broccoli invariants. We show that this is the only
possible refinement of the Markwig-Rau descendant invariants that generalizes
the Goettsche-Schroeter refined broccoli invariants. We discuss also the
computational aspect (a lattice path algorithm) and exhibit some examples.


title:
The Hydrodynamic Feedback of Cosmic Reionization on Small-Scale
  Structures and Its Impact on Photon Consumption during the Epoch of
  Reionization

abstract:
  Density inhomogeneity in the intergalactic medium (IGM) can boost the
recombination rate of ionized gas substantially, affecting the growth of HII
regions during reionization. Previous attempts to quantify this effect
typically failed to resolve down to the Jeans scale in the pre-ionization IGM,
which is important in establishing this effect, along with the hydrodynamical
back-reaction of reionization on it. Towards that end, we perform a set of
fully-coupled, radiation-hydrodynamics simulations from cosmological initial
conditions, extending the mass resolution of previous work to the scale of
minihalos. Pre-reionization structure is evolved until a redshift $z_i$ at
which the ionizing radiation from external sources arrives to sweep an R-type
ionization front supersonically across the volume in a few Myr, until it is
trapped on the surfaces of minihalos and converted to D-type, after which the
minihalo gas is removed by photoevaporative winds. Small-scale density
structures during this time lead to a high ($>$10) clumping factor for ionized
gas, which hugely boosts the recombination rate until the structures are
disrupted by the hydrodynamic feedback after $\sim 10-100~\rm{Myr}$. For
incoming stellar radiation with intensity $J_{21}$ in a $200~h^{-1}~\rm{kpc}$
box with the mean density contrast $\bar\delta$, the number of extra
recombinations per H atom, on top of what is expected from homogeneously
distributed gas, is given by
$0.32[J_{21}]^{0.12}[(1+z_i)/11]^{-1.7}[1+\bar\delta]^{2.5}$. In models in
which most of the volume is ionized toward the end of reionization, this can
add more than one recombination per H atom to the ionizing photon budget to
achieve reionization.


title:
On the number of distinct quadratic fields generated by the Shanks
  sequence

abstract:
  Let $g>1$ be an integer and $f(X)\in{\mathbb Z}[X]$ a polynomial of positive
degree with no multiple roots, and put $u(n)=f(g^n)$. In this note, we study
the sequence of quadratic fields ${\mathbb Q}(\sqrt{u(n)}\,)$ as $n$ varies
over the consecutive integers $M+1,\ldots,M+N$. Fields of this type include
Shanks fields and their generalizations. Using the square sieve together with
new bounds on character sums, we improve an upper bound of Luca and Shparlinski
(2009) on the number of $n \in \{M+1,\ldots,M+N\}$ with ${\mathbb
Q}(\sqrt{u(n)}\,) = {\mathbb Q}(\sqrt{s}\,)$ for a given squarefree integer
$s$.


title: Abel pairs and modular curves

abstract:
  In this article we consider rational functions on algebraic curves, which
have one zero and one pole (and call pair of such function and curve Abel
pair). We investigate moduli spaces of such functions on curves of genus one;
the number of Belyi pairs among them is calculated for fields $\mathbb C$ and
$\overline{\mathbb F_p}$. This result could be fruitfully used for
investigation of Hurwitz's space and modular curves for fields of finite
characteristic.


title: Inequalities for critical exponents in $d$-dimensional sandpiles

abstract:
  Consider the Abelian sandpile measure on $\mathbb{Z}^d$, $d \ge 2$, obtained
as the $L \to \infty$ limit of the stationary distribution of the sandpile on
$[-L,L]^d \cap \mathbb{Z}^d$. When adding a grain of sand at the origin, some
region, called the avalanche cluster, topples during stabilization. We prove
bounds on the behaviour of various avalanche characteristics: the probability
that a given vertex topples, the radius of the toppled region, and the number
of vertices toppled. Our results yield rigorous inequalities for the relevant
critical exponents. In $d = 2,$ we show that for any $1 \le k < \infty$, the
last $k$ waves of the avalanche have an infinite volume limit, satisfying a
power law upper bound on the tail of the radius distribution.


title:
Analysis and Simulation on a Model for the Evolution of Tumors under the
  Influence of Nutrient and Drug Application

abstract:
  We investigate the evolution of tumor growth relying on a nonlinear model of
partial differential equations which incorporates mechanical laws for tissue
compression combined with rules for nutrients availability and drug
application. Rigorous analysis and simulations are presented which show the
role of nutrient and drug application in the progression of tumors. We
construct an explicit convergent numerical scheme to approximate solutions of
the nonlinear system of partial differential equations. Extensive numerical
tests show that solutions exhibit a necrotic core when the nutrient level falls
below a critical level in accordance with medical observations. The same
numerical experiment is performed in the case of drug application for the
purpose of comparison. Depending on the balance between nutrient and drug both
shrinkage and growth of tumors can occur. The role of inhomogeneous boundary
conditions, vascularization and anisotropies in the development of tumor shape
irregularities are discussed.


title: Coulomb breakup of 22C in a four-body model

abstract:
  Breakup cross sections are determined for the Borromean nucleus 22C by using
a four-body eikonal model, including Coulomb corrections. Bound and continuum
states are constructed within a 20C + n + n three-body model in hyperspherical
coordinates. We compute continuum states with the correct asymptotic behavior
through the R-matrix method. For the n+ n potential, we use the Minnesota
interaction. As there is no precise experimental information on 21C, we define
different parameter sets for the 20C + n potentials. These parameter sets
provide different scattering lengths, and resonance energies of an expected
3/2+ excited state. Then we analyze the 22C ground-state energy and rms radius,
as well as E1 strength distributions and breakup cross sections. The E1
strength distribution presents an enhancement at low energies. Its amplitude is
associated with the low binding energy, rather than with a three-body
resonance. We show that the shape of the cross section at low energies is
sensitive to the ground-state properties. In addition, we suggest the existence
of a low-energy 2+ resonance, which should be observable in breakup
experiments.


title:
Orbital-selective Mott phases of a one-dimensional three-orbital Hubbard
  model studied using computational techniques

abstract:
  A recently introduced one-dimensional three-orbital Hubbard model displays
orbital-selective Mott phases with exotic spin arrangements such as spin block
states [J. Rinc\'on {\em et al.}, Phys. Rev. Lett. \textbf{112}, 106405
(2014)]. In this publication we show that the Constrained-Path Quantum Monte
Carlo (CPQMC) technique can accurately reproduce the phase diagram of this
multiorbital one-dimensional model, paving the way to future CPQMC studies in
systems with more challenging geometries, such as ladders and planes. The
success of this approach relies on using the Hartree-Fock technique to prepare
the trial states needed in CPQMC. We also study a simplified version of the
model where the pair-hopping term is neglected and the Hund coupling is
restricted to its Ising component. The corresponding phase diagrams are shown
to be only mildly affected by the absence of these technically
difficult-to-implement terms. This is confirmed by additional Density Matrix
Renormalization Group and Determinant Quantum Monte Carlo calculations carried
out for the same simplified model, with the latter displaying only mild Fermion
sign problems. We conclude that these methods are able to capture
quantitatively the rich physics of the several orbital-selective Mott phases
(OSMP) displayed by this model, thus enabling computational studies of the OSMP
regime in higher dimensions, beyond static or dynamic mean field
approximations.


title: Donaldson-Thomas trasnsformations of moduli spaces of G-local systems

abstract:
  Kontsevich and Soibelman defined Donaldson-Thomas invariants of a 3d
Calabi-Yau category equipped with a stability condition. Any cluster variety
gives rise to a family of such categories. Their DT invariants are encapsulated
in a single formal automorphism of the cluster variety, called the
DT-transformation.
  Let S be an oriented surface with punctures, and a finite number of special
points on the boundary considered modulo isotopy. It give rise to a moduli
space X(m, S), closely related to the moduli space of PGL(m)-local systems on
S, which carries a canonical cluster Poisson variety structure. For each
puncture of S, there is a birational Weyl group action on the space X(m, S). We
prove that it is given by cluster Poisson transformations. We prove a similar
result for the involution * of the space X(m,S) provided by dualising a local
system on S.
  We calculate the DT-transformation of the moduli space X(m,S), with few
exceptions. Namely, let C(m,S) be the transformation of the space X(m,S) given
by the product of three commuting maps: the involution *, the product, over all
punctures of S, of the longest element of the Weyl group action corresponding
to the puncture, and the "shift of the special points on the boundary by one"
map. Using a characterisation of a class of DT-transformations due to Keller,
we prove that C(m,S) = DT.
  We prove that, burring few exceptions, the Weyl group and the involution *
act by cluster transformations of the dual moduli space A(m, S). So the formula
C(m,S) = DT is valid for the space A(m,S).
  Our main result, combined with the work of Gross, Hacking, Keel and
Kontsevich, deliver a canonical basis in the space of regular functions on the
cluster variety X(m,S), and in the upper cluster algebra with principal
coefficients related to the pair (SL(m), S), with few exceptions.


title: A PI degree theorem for quantum deformations

abstract:
  Let $F$ be an algebraically closed field. We show that if a quantum formal
deformation $A$ of a commutative domain $A_0$ over $F$ is a PI algebra, then
$A$ is commutative if ${\rm char}(F)=0$, and has PI degree a power of $p$ if
${\rm char}(F)=p>0$. This implies the same result for filtered deformations
(i.e., filtered algebras $A$ such that ${\rm gr}(A)=A_0$).


title: Doppler shift picture of the Dzyaloshinskii--Moriya interaction

abstract:
  We present a physical picture for the emergence of the Dzyaloshinskii--Moriya
(DM) interaction based on the idea of the Doppler shift by an intrinsic spin
current induced by spin--orbit interaction under broken inversion symmetry. The
picture is confirmed by a rigorous effective Hamiltonian theory, which reveals
that the DM coefficient is given by the magnitude of the intrinsic spin
current. The expression is directly applicable to first principles calculations
and clarifies the relation between the interaction and the electronic band
structures. Quantitative agreement with experimental results is obtained for
the skyrmion compounds Mn$_{1-x}$Fe$_x$Ge and Fe$_{1-x}$Co$_x$Ge.


title:
Spatially-Resolved Spectroscopy of a Balmer-Dominated Shock in the
  Cygnus Loop: An Extremely Thin Cosmic-Ray Precursor?

abstract:
  We present high-resolution long-slit spectroscopy of a Balmer-dominated shock
in the northeastern limb of the Cygnus Loop with the Subaru high dispersion
spectrograph. By setting the slit angle along the shock normal, we investigate
variations of the flux and profile of the H-alpha line from preshock to
postshock regions with a spatial resolution of about 4 times 10^{15} cm. The
H-alpha line profile can be represented by a narrow (28.9+/-0.7 km/s) Gaussian
in a diffuse region ahead of the shock, i.e., a photoionization precursor, and
narrow (33.1+/-0.2 km/s) plus broad (130-230 km/s) Gaussians at the shock
itself. We find that the width of the narrow component abruptly increases up to
33.1+/-0.2 km/s, or 38.8+/-0.4 km/s if we eliminate projected emission
originating from the photoionization precursor, in an unresolved thin layer (<
4 times 10^{15} cm at a distance of 540 pc) at the shock. We show that the
sudden broadening can be best explained by heating via damping of Alfven waves
in a thin cosmic-ray precursor, although other possibilities are not fully
ruled out. The thickness of the cosmic-ray precursor in the Cygnus Loop (a soft
gamma-ray emitter) is an order of magnitude thinner than that in Tycho's Knot g
(a hard gamma-ray emitter), which may be caused by different energy
distribution of accelerated particles between the two sources. In this context,
systematic studies might reveal a positive correlation between the thickness of
the cosmic-ray precursor and the hardness of the cosmic-ray energy
distribution.


title: Social planning for social HRI

abstract:
  Making a computational agent 'social' has implications for how it perceives
itself and the environment in which it is situated, including the ability to
recognise the behaviours of others. We point to recent work on social planning,
i.e. planning in settings where the social context is relevant in the
assessment of the beliefs and capabilities of others, and in making appropriate
choices of what to do next.


title:
Computational Narrative Intelligence: A Human-Centered Goal for
  Artificial Intelligence

abstract:
  Narrative intelligence is the ability to craft, tell, understand, and respond
affectively to stories. We argue that instilling artificial intelligences with
computational narrative intelligence affords a number of applications
beneficial to humans. We lay out some of the machine learning challenges
necessary to solve to achieve computational narrative intelligence. Finally, we
argue that computational narrative is a practical step towards machine
enculturation, the teaching of sociocultural values to machines.


title: Characteristic subspaces and hyperinvariant frames

abstract:
  Let $f$ be an endomorphism of a finite dimensional vector space $V$ over a
field $K$. An $f$-invariant subspace of $V$ is called hyperinvariant
(respectively characteristic) if it is invariant under all endomorphisms
(respectively automorphisms) that commute with $f$. We assume $|K| = 2$, since
all characteristic subspaces are hyperinvariant if $|K| > 2$. The
hyperinvariant hull $W^h$ of a subspace $ W$ of $ V$ is defined to be the
smallest hyperinvariant subspace of $V$ that contains $ W$, the hyperinvariant
kernel $W_H$ of $ W$ is the largest hyperinvariant subspace of $V$ that is
contained in $W$, and the pair $( W_H, W^h) $ is the hyperinvariant frame of
$W$. In this paper we study hyperinvariant frames of characteristic
non-hyperinvariant subspaces $W$. We show that all invariant subspaces in the
interval $[ W_H, W^h ]$ are characteristic. We use this result for the
construction of characteristic non-hyperinvariant subspaces.


title: Two-weight entropy Boundedness of Multilinear Fractional Type Operators

abstract:
  This paper will be devoted to study the two-weight norm inequalities of the
multilinear fractional maximal operator $\mathcal{M}_{\alpha}$ and the
multilinear fractional integral operator $\mathcal{I}_{\alpha}$. The entropy
conditions in the multilinear setting will be introduced and the entropy bounds
for $\mathcal{M}_\alpha$ and $\mathcal{I}_\alpha$ will be given.


title:
The response of linear inhomogeneous systems to coupled fields: Bounds
  and perturbation expansions

abstract:
  We consider the response of a multicomponent body to $n$ fields, such as
electric fields, magnetic fields, temperature gradients, concentration
gradients, etc., where each component, which is possibly anisotropic, may cross
couple the various fields with different fluxes, such as electrical currents,
electrical displacement currents, magnetic induction fields, energy fluxes,
particle fluxes, etc. We obtain the form of the perturbation expansions of the
fields and response tensor in powers of matrices which measure the difference
between each component tensor and a homogeneous reference tensor ${\bf L}_0$.
For the case of a statistically homogeneous or periodic composite the expansion
coefficients can be expressed in terms of positive semidefinite normalization
matrices alternating with positive semidefinite weight matrices, which at each
given level sum to the identity matrix. In an appropriate basis the projection
operators onto the relevant subspaces can be expressed in block tridiagonal
form, where the blocks are functions of these weight and normalization
matrices. This leads to continued fraction expansions for the effective tensor,
and by truncating the continued fraction at successive levels one obtains a
nested sequence of bounds on the effective tensor incorporating successively
more weight and normalization matrices. The weight matrices and normalization
matrices can be calculated from the series expansions of the fields which solve
the conductivity problem alone, without any couplings to other fields, and then
they can be used to obtain the solution for the fields and effective tensor in
coupled field problems in composites.


title: IOTSim: a Cloud based Simulator for Analysing IoT Applications

abstract:
  A disruptive technology that is influencing not only computing paradigm but
every other business is the rise of big data. Internet of Things (IoT)
applications are considered to be a major source of big data. Such IoT
applications are in general supported through clouds where data is stored and
processed by big data processing systems. In order to improve the efficiency of
cloud infrastructure so that they can efficiently support IoT big data
applications, it is important to understand how these applications and the
corresponding big data processing systems will perform in cloud computing
environments. However, given the scalability and complex requirements of big
data processing systems, an empirical evaluation on actual cloud infrastructure
can hinder the development of timely and cost effective IoT solutions.
Therefore, a simulator supporting IoT applications in cloud environment is
highly demanded, but such work is still in its infancy. To fill this gap, we
have designed and implemented IOTSim which supports and enables simulation of
IoT big data processing using MapReduce model in cloud computing environment. A
real case study validates the efficacy of the simulator.


title:
Distributed Private Online Learning for Social Big Data Computing over
  Data Center Networks

abstract:
  With the rapid growth of Internet technologies, cloud computing and social
networks have become ubiquitous. An increasing number of people participate in
social networks and massive online social data are obtained. In order to
exploit knowledge from copious amounts of data obtained and predict social
behavior of users, we urge to realize data mining in social networks. Almost
all online websites use cloud services to effectively process the large scale
of social data, which are gathered from distributed data centers. These data
are so large-scale, high-dimension and widely distributed that we propose a
distributed sparse online algorithm to handle them. Additionally,
privacy-protection is an important point in social networks. We should not
compromise the privacy of individuals in networks, while these social data are
being learned for data mining. Thus we also consider the privacy problem in
this article. Our simulations shows that the appropriate sparsity of data would
enhance the performance of our algorithm and the privacy-preserving method does
not significantly hurt the performance of the proposed algorithm.


title:
Thermal conductivity spectrum calculation from first-principles-based
  harmonic phonon theory

abstract:
  In recent years, nanostructuring of dielectric and semiconducting crystals
has enhanced controllability of their thermal conductivity. To carry out
computational material search for nanostructured materials with desirable
thermal conductivity, a key property is the thermal conductivity spectrum of
the original single crystal, which determines the appropriate length scale of
nanostructures and mutual adaptability of different kinds of nanostructures.
Although the first-principles phonon transport calculations have become
accessible, the anharmonic lattice dynamics calculations are still heavy to
scan many materials. To this end, we have developed an empirical model that
describes the thermal conductivity spectrum in terms only of harmonic phonon
properties and bulk thermal conductivity. The model was tested for several
crystals with different structures and thermal conductivities, and was
confirmed to reproduce the overall profiles of thermal conductivity spectra and
their anharmonic calculations.


title:
Probing the R-parity violating supersymmetric effects in the exclusive
  b\to c\ell^-\bar{\nu}_\ell decays

abstract:
  Motivated by recent results from the LHCb, BABAR and Belle collaborations on
B\to D^{(*)}\ell^-\bar{\nu}_\ell decays, which significantly deviate from the
Standard Model and hint the possible new physics beyond the Standard Model, we
probe the R-parity violating supersymmetric effects in B^-_c\to
\ell^-\bar{\nu}_\ell and B\to D^{(*)}\ell^-\bar{\nu}_\ell decays. We find that
(i) \mathcal{B}(B^-_c\to e^- \bar{\nu}_e) and
\mathcal{B}(B^-_c\to\mu^-\bar{\nu}_\mu) are sensitive to the constrained
slepton exchange couplings; (ii) the normalized forward-backward asymmetries of
B\to De^-\bar{\nu}_{e} decays have been greatly affected by the constrained
slepton exchange couplings, and their signs could be changed; (iii) all
relevant observables in the exclusive b\to c\tau^-\bar{\nu}_\tau decays and the
ratios \mathcal{R}(D^{(*)}) are sensitive to the slepton exchange coupling,
\mathcal{R}(D^*) could be enhanced by the constrained slepton exchange coupling
to reach each 95\% confidence level experimental range from BABAR, Belle and
LHCb, but it could not reach the lower limit of the 95\% confidence level
experimental average. Our results in this work could be used to probe R-parity
violating effects, and will correlate with searches for direct supersymmetric
signals at the running LHCb and the forthcoming Belle-II.


title: Global Finite-Time Attitude Tracking via Quaternion Feedback

abstract:
  This paper addresses the attitude tracking of a rigid body using a quaternion
description. Global finite-time attitude controllers are designed with three
types of measurements, namely, full states, attitude plus constant-biased
angular velocity, and attitude only. In all three scenarios hybrid control
techniques are utilized to overcome the well-known topological constraint on
the attitude manifold, while coupled nonsmooth feedback inputs are designed via
homogeneous theory to achieve finite-time stability. Specially, a finite-time
bias observer is derived in the second scenario and a quaternion filter is
constructed to provide damping in the absence of velocity feedback. The
proposed methods ensure bounded control torques a priori and, in particular,
include several existing attitude controllers as special cases.


title: Solar jet-coronal hole collision and a related coronal mass ejection

abstract:
  Jets are defined as impulsive, well-collimated upflows, occurring in
different layers of the solar atmosphere with different scales. Their
relationship with coronal mass ejections (CMEs), another type of solar
impulsive events, remains elusive. Using the high-quality imaging data of
AIA/SDO, here we show a well-observed coronal jet event, in which part of the
jets, with the embedding coronal loops, runs into a nearby coronal hole (CH)
and gets bounced towards the opposite direction. This is evidenced by the
flat-shape of the jet front during its interaction with the CH and the V-shaped
feature in the time-slice plot of the interaction region. About a half-hour
later, a CME initially with a narrow and jet-like front is observed by the
LASCO C2 coronagraph, propagating along the direction of the post-collision
jet. We also observe some 304 A dark material flowing from the jet-CH
interaction region towards the CME. We thus suggest that the jet and the CME
are physically connected, with the jet-CH collision and the large- scale
magnetic topology of the CH being important to define the eventual propagating
direction of this particular jet-CME eruption.


title: K-theoretic quasimap invariants and their wall-crossing

abstract:
  For each positive rational number $\epsilon$, we define $K$-theoretic
$\epsilon$-stable quasimaps to certain GIT quotients $W\sslash G$. For
$\epsilon>1$, this recovers the $K$-theoretic Gromov-Witten theory of $W\sslash
G$ introduced in more general context by Givental and Y.-P. Lee.
  For arbitrary $\epsilon_1$ and $\epsilon_2$ in different stability chambers,
these $K$-theoretic quasimap invariants are expected to be related by
wall-crossing formulas. We prove wall-crossing formulas for genus zero
$K$-theoretic quasimap theory when the target $W\sslash G$ admits a torus
action with isolated fixed points and isolated one-dimensional orbits.


title: Scalar model of SU(N) glueball \`a la Heisenberg

abstract:
  Nonperturbative model of glueball is studied. The model is based on the
nonperturbative quantization technique suggested by Heisenberg. 2- and 4-point
Green functions for a gauge potential are expressed in terms of two scalar
fields. The first scalar field describes quantum fluctuations of the subgroup
$SU(n) \subset SU(N)$, and the second one describes quantum fluctuations of the
coset $SU(N) / SU(n)$. An effective Lagrangian for the scalar fields is
obtained. The coefficients for all terms in the Lagrangian are calculated, and
it is shown that they depend on $\dim SU(n), \dim SU(N)$. It is demonstrated
that a spherically symmetric solution describing the glueball does exist.


title:
Calorimetric Measurements of Magnetic-Field-Induced Inhomogeneous
  Superconductivity Above The Paramagnetic Limit

abstract:
  We report the first magneto-caloric and calorimetric observations of a
magnetic-field-induced phase transition within a superconducting state to the
long-sought exotic "FFLO" superconducting state first predicted over 50 years
ago. Through the combination of bulk thermodynamic calorimetric and
magnetocaloric measurements in the organic superconductor $\kappa$ -
(BEDT-TTF)$_2$Cu(NCS)$_2$, as a function of temperature, magnetic field
strength, and magnetic field orientation, we establish for the first time that
this field-induced first-order phase transition at the paramagnetic limit $H_p$
for traditional superconductivity is to a higher entropy superconducting phase
uniquely characteristic of the FFLO state. We also establish that this
high-field superconducting state displays the bulk paramagnetic ordering of
spin domains required of the FFLO state. These results rule out the alternate
possibility of spin-density wave (SDW) ordering in the high field
superconducting phase. The phase diagram determined from our measurements ---
including the observation of a phase transition into the FFLO phase at $H_p$
--- is in good agreement with recent NMR results and our own earlier
tunnel-diode magnetic penetration depth experiments, but is in disagreement
with the only previous calorimetric report.


title: Multiple-choice test of energy and momentum concepts

abstract:
  We investigate student understanding of energy and momentum concepts at the
level of introductory physics by designing and administering a 25-item multiple
choice test and conducting individual interviews. We find that most students
have difficulty in qualitatively interpreting basic principles related to
energy and momentum and in applying them in physical situations.


title:
Directly Coupled Observers for Quantum Harmonic Oscillators with
  Discounted Mean Square Cost Functionals and Penalized Back-action

abstract:
  This paper is concerned with quantum harmonic oscillators consisting of a
quantum plant and a directly coupled coherent quantum observer. We employ
discounted quadratic performance criteria in the form of exponentially weighted
time averages of second-order moments of the system variables. A coherent
quantum filtering (CQF) problem is formulated as the minimization of the
discounted mean square of an estimation error, with which the dynamic variables
of the observer approximate those of the plant. The cost functional also
involves a quadratic penalty on the plant-observer coupling matrix in order to
mitigate the back-action of the observer on the covariance dynamics of the
plant. For the discounted mean square optimal CQF problem with penalized
back-action, we establish first-order necessary conditions of optimality in the
form of algebraic matrix equations. By using the Hamiltonian structure of the
Heisenberg dynamics and related Lie-algebraic techniques, we represent this set
of equations in a more explicit form in the case of equally dimensioned plant
and observer.


title:
Assessing Student Expertise in Introductory Physics with Isomorphic
  Problems, Part I: Performance on Non-intuitive Problem Pair from Introductory
  Physics

abstract:
  Investigations related to expertise in problem solving and ability to
transfer learning from one context to another are important for developing
strategies to help students perform more expert-like tasks. Here we analyze
written responses to a pair of non-intuitive isomorphic problems given to
introductory physics students and discussions with a subset of students about
them. Students were asked to explain their reasoning for their written
responses. We call the paired problems isomorphic because they require the same
physics principle to solve them. However, the initial conditions are different
and the frictional force is responsible for increasing the linear speed of an
object in one of the problems while it is responsible for decreasing the linear
speed in the other problem. We categorize student responses and evaluate
student performance within the context of their evolving expertise. We compare
and contrast the patterns of student categorization for the two isomorphic
problems. We discuss why certain incorrect responses were better than others
and shed light on the evolution of students' expertise. We compare the
performance of students who worked on both isomorphic problems with those who
worked only on one of the problems to understand whether students recognized
their underlying similarity and whether isomorphic pairs gave students
additional insight in solving each problem.


title:
Some Proof Derivations and Further Simulation Results for "Semidefinite
  Relaxation and Approximation Analysis of a Beamformed Alamouti Scheme for
  Relay Beamforming Networks"

abstract:
  This is a companion technical report of the main manuscript "Semidefinite
Relaxation and Approximation Analysis of a Beamformed Alamouti Scheme for Relay
Beamforming Networks". The report serves to give detailed derivations of Lemma
1-2 in the main manuscript, which are too long to be included in the latter. In
addition, more simulation results are presented to verify the viability of the
BF Alamouti AF schemes developed in the main manuscript.


title:
Topological Dirac Nodal Lines and Surface Charges in fcc Alkaline Earth
  Metals

abstract:
  In nodal-line semimetals, the gaps close along loops in ${\bf k}$ space,
which are not at high-symmetry points. Typical mechanisms for the emergence of
nodal lines involve mirror symmetry and the $\pi$ Berry phase. Here, we show
via ab initio calculations that fcc calcium (Ca), strontium (Sr) and ytterbium
(Yb) have topological nodal lines with the $\pi$ Berry phase near the Fermi
level, when spin-orbit interaction is neglected. In particular, Ca becomes a
nodal-line semimetal at high pressure. Owing to nodal lines, the Zak phase
becomes either $\pi$ or 0 depending on the wavavector ${\bf k}$, and the $\pi$
Zak phase leads to surface polarization charge. Carriers eventually screen it,
leaving behind large surface dipoles. In materials with nodal lines, both the
large surface polarization charge and the emergent drumhead surface states
enhance Rashba splitting when heavy adatoms are present, as we have shown to
occur in Bi/Sr(111) and in Bi/Ag(111).


title:
Dynamic density and spin responses of a superfluid Fermi gas in the
  BCS-BEC crossover: Path integral formulation and pair fluctuation theory

abstract:
  We present a standard field theoretical derivation of the dynamic density and
spin linear response functions of a dilute superfluid Fermi gas in the BCS-BEC
crossover in both three and two dimensions. The derivation of the response
functions is based on the elegant functional path integral approach which
allows us to calculate the density-density and spin-spin correlation functions
by introducing the external sources for the density and the spin density. Since
the generating functional cannot be evaluated exactly, we consider two gapless
approximations which ensure a gapless collective mode (Goldstone mode) in the
superfluid state: the BCS-Leggett mean-field theory and the
Gaussian-pair-fluctuation (GPF) theory. In the mean-field theory, our results
of the response functions agree with the known results from the random phase
approximation. We further consider the pair fluctuation effects and establish a
theoretical framework for the dynamic responses within the GPF theory. We show
that the GPF response theory naturally recover three kinds of famous
diagrammatic contributions: the Self-Energy contribution, the Aslamazov-Lakin
contribution, and the Maki-Thompson contribution. We also show that unlike the
equilibrium state, in evaluating the response functions, the linear
(first-order) terms in the external sources as well as the induced order
parameter perturbations should be treated carefully. In the superfluid state,
there is an additional order parameter contribution which ensures that in the
static and long wavelength limit, the density response function recovers the
result of the compressibility (compressibility sum rule). We expect that the
$f$-sum rule is manifested by the full number equation which includes the
contribution from the Gaussian pair fluctuations.

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


title:
Inverse Magnetic Catalysis in Nambu--Jona-Lasinio Model beyond Mean
  Field

abstract:
  We study inverse magnetic catalysis in the Nambu--Jona-Lasinio model beyond
mean field approximation. The feed-down from mesons to quarks is embedded in an
effective coupling constant at finite temperature and magnetic field. While the
magnetic catalysis is still the dominant effect at low temperature, the meson
dressed quark mass drops down with increasing magnetic field at high
temperature due to the dimension reduction of the Goldstone mode in the
Pauli-Villars regularization scheme.


title:
Malignant field signature analysis in biopsy samples at diagnosis
  identifies lethal disease in patients with localized Gleason 6 and 7 prostate
  cancer

abstract:
  Overtreatment of early-stage low-risk prostate cancer (PC) patients
represents a significant problem in disease management and has socio-economic
implications. Development of genetic and molecular markers of clinically
significant disease in patients diagnosed with low grade localized PC would
have a major impact in disease management. A gene expression signature (GES) is
reported for lethal PC in biopsy specimens obtained at the time of diagnosis
from patients with Gleason 6 and Gleason 7 tumors in a Swedish watchful waiting
cohort with up to 30 years follow-up. A 98-genes GES identified 89 and 100
percent of all death events 4 years after diagnosis in G7 and G6 patients,
respectively; at 6 years follow-up, 83 and 100 percent of all deaths events
were captured. Remarkably, the 98-genes GES appears to perform successfully in
patients stratification with as little as 2% of cancer cells in a specimen,
strongly indicating that it captures a malignant field effect in prostates
harboring cancer cells of different degrees of aggressiveness. In G6 and G7
tumors from PC patients of age 65 or younger, GES identified 86 percent of all
death events during the entire follow-up period. In G6 and G7 tumors from PC
patients of age 70 or younger, GES identified 90 percent of all death events 6
years after diagnosis. Classification performance of the reported in this study
98-genes GES of lethal PC appeared suitable to meet design and feasibility
requirements of a prospective 4 to 6 years clinical trial, which is essential
for regulatory approval of diagnostic and prognostic tests in clinical setting.
Prospectively validated GES of lethal PC in biopsy specimens of G6 and G7
tumors will help physicians to identify, at the time of diagnosis, patients who
should be considered for exclusion from active surveillance programs and who
would most likely benefit from immediate curative interventions.


title: On $dS_4$ extremal surfaces and entanglement entropy in some ghost CFTs

abstract:
  In arXiv:1501.03019 [hep-th], the areas of certain complex extremal surfaces
in de Sitter space were found to have resemblance with entanglement entropy in
appropriate dual Euclidean non-unitary CFTs, with the area being real and
negative in $dS_4$. In this paper, we study some toy models of 2-dim ghost
conformal field theories with negative central charge with a view to exploring
this further from the CFT point of view. In particular we consider $bc$-ghost
systems with central charge $c=-2$ and study the replica formulation for
entanglement entropy for a single interval, and associated issues arising in
this case, notably pertaining to (i) the $SL(2)$ vacuum coinciding with the
ghost ground state, and (ii) the background charge inherent in these systems
which leads to particular forms for the norms of states (involving zero modes).
This eventually gives rise to negative entanglement entropy. We also discuss a
(logarithmic) CFT of anti-commuting scalars, with similarities in some
features. Finally we discuss a simple toy model of two "ghost-spins" which
mimics some of these features.


title:
Evaluation of Generalized Degrees of Freedom for Sparse Estimation by
  Replica Method

abstract:
  We develop a method to evaluate the generalized degrees of freedom (GDF),
which is a key quantity of a model selection criterion, for linear regression
with sparse regularization. Using the replica method, GDF is expressed by the
variables that characterize the saddle point of the free energy without
depending on the form of the regularization. Within the framework of replica
symmetric (RS) analysis, GDF is provided with a physical meaning as the
effective density of non-zero components. The validity of our method in the RS
phase is supported by the consistency of our results with previous mathematical
results. The analytical results in the RS phase are numerically achieved by the
belief propagation algorithm.


title:
Non-reciprocal Radio Frequency Transduction in a Parametric Mechanical
  Artificial Lattice

abstract:
  Generating non-reciprocal radio frequency transduction plays important roles
in a wide range of research and applications, and an aspiration is to integrate
this functionality into micro-circuit without introducing magnetic field,
which, however, remains challenging. By designing a 1D artificial lattice
structure with neighbor-interaction engineered parametrically, we predicted a
non-reciprocity transduction with giant unidirectionality. We then
experimentally demonstrated the phenomenon on a nano-electromechanical chip
fabricated by conventional complementary metal-silicon processing. A
unidirectionality with isolation as high as 24dB is achieved and several
different transduction schemes are realized by programming the control voltages
topology. Apart from being used as a radio frequency isolator, the system
provides a way to build practical on-chip programmable device for many
researches and applications in radio frequency domain.

categories: cond-mat.mes-hall cond-mat.mtrl-sci physics.optics quant-ph


title:
Fuzzy Opinion Networks: A Mathematical Framework for the Evolution of
  Opinions and Their Uncertainties Across Social Networks

abstract:
  We propose a new mathematical framework for the evolution and propagation of
opinions, called Fuzzy Opinion Network, which is the connection of a number of
Gaussian Nodes, possibly through some weighted average, time-delay or logic
operators, where a Gaussian Node is a Gaussian fuzzy set with the center and
the standard deviation being the node inputs and the fuzzy set itself being the
node output. In this framework an opinion is modeled as a Gaussian fuzzy set
with the center representing the opinion itself and the standard deviation
characterizing the uncertainty about the opinion. We study the basic
connections of Fuzzy Opinion Networks, including basic center, basic standard
deviation (sdv), basic center-sdv, chain-in-center and chain-in-sdv
connections, and we analyze a number of dynamic connections to show how
opinions and their uncertainties propagate and evolve across different network
structures and scenarios. We explain what insights we might gain from these
mathematical results about the formation and evolution of human opinions.


title: Orthogonal AMP

abstract:
  Approximate message passing (AMP) is a low-cost iterative signal recovery
algorithm for linear system models. When the system transform matrix has
independent identically distributed (IID) Gaussian entries, the performance of
AMP can be asymptotically characterized by a simple scalar recursion called
state evolution (SE). However, SE may become unreliable for other matrix
ensembles, especially for ill-conditioned ones. This imposes limits on the
applications of AMP.
  In this paper, we propose an orthogonal AMP (OAMP) algorithm based on
de-correlated linear estimation (LE) and divergence-free non-linear estimation
(NLE). The Onsager term in standard AMP vanishes as a result of the
divergence-free constraint on NLE. We develop an SE procedure for OAMP and show
numerically that the SE for OAMP is accurate for general unitarily-invariant
matrices, including IID Gaussian matrices and partial orthogonal matrices. We
further derive optimized options for OAMP and show that the corresponding SE
fixed point coincides with the optimal performance obtained via the replica
method. Our numerical results demonstrate that OAMP can be advantageous over
AMP, especially for ill-conditioned matrices


title:
The need for effective information security awareness practices in Oman
  higher educational institutions

abstract:
  The revolution of internet technology and its usage have led a significant
increase in the number of online transactions and electronic data transfer,
parallely increased the number of cybercrime incidents around the world. Steady
economic growth in the Sultanate of Oman accelerated the volume of online
utilization for e-commerce, banking, communication, education and so forth.
Normally attackers target the users who ignore security practices due to the
lack of information security awareness. Unawareness of information security
practices, user negligence, lack of awareness programs and trainings are the
root cause for information security threats. Earlier studies reveal there is a
considerable and continuous cybercrime incident in Oman which compromises the
security policy of the organizations, affecting the business continuity and the
economic growth. In this study, a survey was performed among the educational
institutions in Oman to investigate the level of information security awareness
and based on the study, a security awareness model is proposed to enable
information security practices in the educational institutions.


title: Ghost inflation and de Sitter entropy

abstract:
  In the setup of ghost condensation model the generalized second law of black
hole thermodynamics can be respected under a radiatively stable assumption that
couplings between the field responsible for ghost condensate and matter fields
such as those in the Standard Model are suppressed by the Planck scale. Since
not only black holes but also cosmology are expected to play important roles
towards our better understanding of gravity, we consider a cosmological setup
to test the theory of ghost condensation. In particular we shall show that the
de Sitter entropy bound proposed by Arkani-Hamed, et.al. is satisfied if ghost
inflation happened in the early epoch of our universe and if there remains a
tiny positive cosmological constant in the future infinity. We then propose a
notion of cosmological Page time after inflation.


title: Waiting times and stopping probabilities for patterns in Markov chains

abstract:
  Suppose that $\mathcal C$ is a finite collection of patterns. Observe a
Markov chain until one of the patterns in $\mathcal C$ occurs as a run. This
time is denoted by $\tau$. In this paper, we aim to give an easy way to
calculate the mean waiting time $E(\tau)$ and the stopping probabilities
$P(\tau=\tau_A)$ with $A\in\mathcal C$, where $\tau_A$ is the waiting time
until the pattern $A$ appears as a run.


title:
Orbital Feshbach Resonance: A "Wide" Narrow Resonance for Higher
  Transition Temperature Fermi Superfluid

abstract:
  In this letter we show that the recently theoretically predicted and
experimentally observed "orbital Feshbach resonance" in alkali-earth-like
Yb-173 atom is a narrow resonance in energy, while it is hundreds Gauss wide in
term of magnetic field strength, taking the advantage that the magnetic moment
difference between the open and closed channels is quite small. Therefore this
is an ideal platform for the experimental realization of a strongly interacting
Fermi superfluid with narrow resonance. We show that the transition temperature
for the Fermi superfluid in this system, especially at the BCS side of the
resonance, is even higher than that in a wide resonance, which is also due to
the narrow character of this resonance. Our results will encourage experimental
efforts to realize Fermi superfluid in the alkali-earth-like Yb-173 system, the
properties of which will be complementary to extensively studied Fermi
superfluids nearby a wide resonance in alkali K-40 and Li-6 systems.


title:
Spectroscopic Survey of {\gamma} Doradus Stars I. Comprehensive
  atmospheric parameters and abundance analysis of {\gamma} Doradus stars

abstract:
  We present a spectroscopic survey of known and candidate $\gamma$\,Doradus
stars. The high-resolution, high signal-to-noise spectra of 52 objects were
collected by five different spectrographs. The spectral classification,
atmospheric parameters (\teff, $\log g$, $\xi$), $v\sin i$ and chemical
composition of the stars were derived. The stellar spectral and luminosity
classes were found between G0-A7 and IV-V, respectively. The initial values for
\teff\ and \logg\ were determined from the photometric indices and spectral
energy distribution. Those parameters were improved by the analysis of hydrogen
lines. The final values of \teff, \logg\ and $\xi$ were derived from the iron
lines analysis. The \teff\ values were found between 6000\,K and 7900\,K, while
\logg\,values range from 3.8 to 4.5\,dex. Chemical abundances and $v\sin i$
values were derived by the spectrum synthesis method. The $v\sin i$ values were
found between 5 and 240\,km\,s$^{-1}$. The chemical abundance pattern of
$\gamma$\,Doradus stars were compared with the pattern of non-pulsating stars.
It turned out that there is no significant difference in abundance patterns
between these two groups. Additionally, the relations between the atmospheric
parameters and the pulsation quantities were checked. A strong correlation
between the $v\sin i$ and the pulsation periods of $\gamma$\,Doradus variables
was obtained. The accurate positions of the analysed stars in the H-R diagram
have been shown. Most of our objects are located inside or close to the blue
edge of the theoretical instability strip of $\gamma$\,Doradus.


title:
Evidence of diffusive fractal aggregation of TiO2 nanoparticles by
  femtosecond laser ablation at ambient conditions

abstract:
  The specific mechanisms which leads to the formation of fractal
nanostructures by pulsed laser deposition remain elusive despite intense
research efforts, motivated mainly by the technological interest in obtaining
tailored nanostructures with simple and scalable production methods. Here we
focus on fractal nanostructures of titanium dioxide, $TiO_2$, a strategic
material for many applications, obtained by femtosecond laser ablation at
ambient conditions. We model the fractal formation through extensive Monte
Carlo simulations based on a set of minimal assumptions: irreversible sticking
and size independent diffusion. Our model is able to reproduce the fractal
dimensions and the area distributions of the nanostructures obtained in the
experiments for different densities of the ablated material. The comparison of
theory and experiment show that such fractal aggregates are formed after
landing of the ablated material on the substrate surface by a diffusive
mechanism. Finally we discuss the role of the thermal conductivity of the
substrate and the laser fluence on the properties of the fractal
nanostructures. Our results represent an advancement towards controlling the
production of fractal nanostructures by pulsed laser deposition.


title:
Uniform Hypergraph Partitioning: Provable Tensor Methods and Sampling
  Techniques

abstract:
  In a series of recent works, we have generalised the consistency results in
the stochastic block model literature to the case of uniform and non-uniform
hypergraphs. The present paper continues the same line of study, where we focus
on partitioning weighted uniform hypergraphs---a problem often encountered in
computer vision. This work is motivated by two issues that arise when a
hypergraph partitioning approach is used to tackle computer vision problems:
(i) The uniform hypergraphs constructed for higher-order learning contain all
edges, but most have negligible weights. Thus, the adjacency tensor is nearly
sparse, and yet, not binary. (ii) A more serious concern is that standard
partitioning algorithms need to compute all edge weights, which is
computationally expensive for hypergraphs. This is usually resolved in practice
by merging the clustering algorithm with a tensor sampling strategy---an
approach that is yet to be analysed rigorously. We build on our earlier work on
partitioning dense unweighted uniform hypergraphs (Ghoshdastidar and Dukkipati,
ICML, 2015), and address the aforementioned issues by proposing provable and
efficient partitioning algorithms. Our analysis justifies the empirical success
of practical sampling techniques. We also complement our theoretical findings
by elaborate empirical comparison of various hypergraph partitioning schemes.


title: Backreacted Axion Field Ranges in String Theory

abstract:
  String theory axions are interesting candidates for fields whose potential
might be controllable over super-Planckian field ranges and therefore as
possible candidates for inflatons in large field inflation. Axion monodromy
scenarios are setups where the axion shift symmetry is broken by some effect
such that the axion can traverse a large number of periods potentially leading
to super-Planckian excursions. We study such scenarios in type IIA string
theory where the axion shift symmetry is broken by background fluxes. In
particular we calculate the backreaction of the energy density induced by the
axion vacuum expectation value on its own field space metric. We find universal
behaviour for all the compactifications studied where up to a certain critical
axion value there is only a small backreaction effect. Beyond the critical
value the backreaction is strong and implies that the proper field distance as
measured by the backreacted metric increases at best logarithmically with the
axion vev, thereby placing strong limitations on extending the field distance
any further. The critical axion value can be made arbitrarily large by the
choice of fluxes. However the backreaction of these fluxes on the axion field
space metric ensures a precise cancellation such that the proper field distance
up to the critical axion value is flux independent and remains sub-Planckian.
We also study an axion alignment scenario for type IIA compactifications on a
twisted torus with four fundamental axions mixing to leave an axion with an
effective decay constant which is flux dependent. There is a choice of fluxes
for which the alignment parameter is unconstrained by tadpoles and can in
principle lead to a parametrically enhanced effective decay constant. However
we show that these fluxes backreact on the fundamental decay constants so as to
precisely cancel any enhancement.


title: Multi-Task Learning with Labeled and Unlabeled Tasks

abstract:
  In multi-task learning, a learner is given a collection of prediction tasks
and needs to solve all of them. In contrast to previous work, which required
that annotated training data is available for all tasks, we consider a new
setting, in which for some tasks, potentially most of them, only unlabeled
training data is provided. Consequently, to solve all tasks, information must
be transferred between tasks with labels and tasks without labels. Focusing on
an instance-based transfer method we analyze two variants of this setting: when
the set of labeled tasks is fixed, and when it can be actively selected by the
learner. We state and prove a generalization bound that covers both scenarios
and derive from it an algorithm for making the choice of labeled tasks (in the
active case) and for transferring information between the tasks in a principled
way. We also illustrate the effectiveness of the algorithm by experiments on
synthetic and real data.


title:
Electrical control of intervalley scattering in graphene via the charge
  state of defects

abstract:
  We study the intervalley scattering in defected graphene by low-temperature
transport measurements. The scattering rate is strongly suppressed when defects
are charged. This finding highlights "screening" of the short-range part of a
potential by the long-range part. Experiments on calcium-adsorbed graphene
confirm the role of a long-range Coulomb potential. This effect is applicable
to other multivalley systems, provided that the charge state of a defect can be
electrically tuned. Our result provides a means to electrically control valley
relaxation and has important implications in valley dynamics in valleytronic
materials.


title: On squares in special sets of finite fields

abstract:
  We consider the linear vector space formed by the elements of the finite
fields $\mathbb{F}_q$ with $q=p^r$ over $\mathbb{F}_p$. Let
$\{a_1,\ldots,a_r\}$ be a basis of this space. Then the elements $x$ of
$\mathbb{F}_q$ have a unique representation in the form $\sum_{j=1}^r c_ja_j$
with $c_j\in\mathbb{F}_p$. Let $D_1,\ldots,D_r$ be subsets of $\mathbb{F}_p$.
We consider the set $W=W(D_1,\ldots,D_r)$ of elements of $\mathbb{F}_q$ such
that $c_j \in D_j$ for all $j=1,\ldots,r$. We give an estimate for the number
of squares in the set $W$ which implies an asymptotic formula for this quantity
in the case when the sets $D_1,\ldots,D_r$ are "large on average" and a
sufficient condition for the existence of squares in the set $W$.


title: Light-Front Dynamics and the 3He Spectral Function

abstract:
  Two topics are presented. The first one is a novel approach for a Poincare'
covariant description of nuclear dynamics based on light-front Hamiltonian
dynamics. The key quantity is the light-front spectral function, where both
normalization and momentum sum rule can be satisfied at the same time.
Preliminary results are discussed for an initial analysis of the role of
relativity in the EMC effect in 3He. A second issue, very challenging, is
considered in a non-relativistic framework, namely a distorted spin-dependent
spectral function for 3He in order to take care of the final state interaction
between the observed pion and the remnant in semi-inclusive deep inelastic
electron scattering off polarized 3He. The generalization of the analysis
within the light-front dynamics is outlined.


title:
Machine learning meets network science: dimensionality reduction for
  fast and efficient embedding of networks in the hyperbolic space

abstract:
  Complex network topologies and hyperbolic geometry seem specularly connected,
and one of the most fascinating and challenging problems of recent complex
network theory is to map a given network to its hyperbolic space. The
Popularity Similarity Optimization (PSO) model represents - at the moment - the
climax of this theory. It suggests that the trade-off between node popularity
and similarity is a mechanism to explain how complex network topologies emerge
- as discrete samples - from the continuous world of hyperbolic geometry. The
hyperbolic space seems appropriate to represent real complex networks. In fact,
it preserves many of their fundamental topological properties, and can be
exploited for real applications such as, among others, link prediction and
community detection. Here, we observe for the first time that a
topological-based machine learning class of algorithms - for nonlinear
unsupervised dimensionality reduction - can directly approximate the network's
node angular coordinates of the hyperbolic model into a two-dimensional space,
according to a similar topological organization that we named angular
coalescence. On the basis of this phenomenon, we propose a new class of
algorithms that offers fast and accurate coalescent embedding of networks in
the hyperbolic space even for graphs with thousands of nodes.


title: Resolved observations of transition disks

abstract:
  Resolved observations are bringing new constraints on the origin of radial
gaps in protoplanetary disks. The kinematics, sampled in detail in one
case-study, are indicative of non-Keplerian flows, corresponding to warped
structures and accretion which may both play a role in the development of
cavities. Disk asymmetries seen in the radio continuum are being interpreted in
the context of dust segregation via aerodynamic trapping. We summarise recent
observational progress, and also describe prospects for improvements in the
near term.


title: Construction of two-bubble solutions for energy-critical wave equations

abstract:
  We construct pure two-bubbles for some energy-critical wave equations, that
is solutions which in one time direction approach a superposition of two
stationary states both centered at the origin, but asymptotically decoupled in
scale. Our solution exists globally, with one bubble at a fixed scale and the
other concentrating in infinite time, with an error tending to 0 in the energy
space. We treat the cases of the power nonlinearity in space dimension 6, the
radial Yang-Mills equation and the equivariant wave map equation with
equivariance class k > 2. The concentrating speed of the second bubble is
exponential for the first two models and a power function in the last case.


title: A family of wave equations with some remarkable properties

abstract:
  We consider a family of homogeneous nonlinear dispersive equations with two
arbitrary parameters. Conservation laws are established from the point
symmetries and imply that the whole family admits square integrable solutions.
Recursion operators are found to two members of the family investigated. For
one of them, a Lax pair is also obtained, proving its complete integrability.
From the Lax pair we construct a Miura-type transformation relating the
original equation to the KdV equation. This transformation, on the other hand,
enables us to obtain solutions of the equation from the kernel of a
Schr\"odinger operator with potential parametrized by the solutions of the KdV
equation. In particular, this allows us to exhibit a kink solution to the
completely integrable equation from the 1-soliton solution of the KdV equation.
Finally, peakon-type solutions are also found for a certain choice of the
parameters, although for this particular case the equation is reduced to a
homogeneous second order nonlinear evolution equation.


title:
Size of Shell Universe in Light of Fermi GBM Transient Associated with
  GW150914

abstract:
  The possible gamma ray burst occurred in location and temporal consistence
with gravitational wave event GW150914, as reported by Fermi Gamma-ray Burst
Monitor (GBM), offers a new way of constraining models with extra dimensions.
Using the time delay in arrival of the gamma ray transient observed by Fermi
GBM relative to the gravitational waves event triggered by the LIGO detectors
we investigate the size of the spherical brane-universe expanding in
multi-dimensional space-time. It is shown that a joint observation of
gravitational waves in association with gamma ray burst can provide a very
stringent bound on the spatial curvature of the brain.


title:
Search for a gamma-ray line feature from a group of nearby Galaxy
  clusters with Fermi LAT Pass 8 data

abstract:
  Galaxy clusters are the largest gravitationally bound objects in the universe
and may be suitable targets for indirect dark matter searches. With 85 months
of Fermi-LAT Pass 8 publicly available data, we analyze the gamma-ray emission
in the directions of 16 nearby Galaxy Clusters with an unbinned likelihood
analysis. No globally statistically-significant $\gamma-$ray line feature is
identified and a tentative line signal may be present at $\sim 43$ GeV. The
95\% confidence level upper limits on the velocity-averaged cross section of
dark matter particles annihilating into double $\gamma-$rays (i.e., $\langle
\sigma v \rangle_{\chi\chi\rightarrow \gamma\gamma}$) are derived. Unless very
optimistic boost factors of dark matter annihilation in these Galaxy Clusters
have been assumed, such constraints are much weaker than the bounds set by the
Galactic $\gamma-$ray data.


title: Harmonic-Counting Measures and Spectral Theory of Lens Spaces

abstract:
  In this article, associated with each lattice $T\subseteq \mathbb{Z}^n$ the
concept of a harmonic-counting measure $\nu_T$ on a sphere $S^{n-1}$ is
introduced and it is applied to determine the asymptotic behavior of the
eigenfunctions of the Laplace-Beltrami operator on a lens space. In fact, the
asymptotic behavior of the cardinality of the set of independent eigenfunctions
associated with the elements of $T$ which lie in a cone is determined when $T$
is the lattice of a lens space.


title: Robust Resource Allocation for Full-Duplex Cognitive Radio Systems

abstract:
  In this paper, we investigate resource allocation algorithm design for
full-duplex (FD) cognitive radio systems. The secondary network employs a FD
base station for serving multiple half-duplex downlink and uplink users
simultaneously. We study the resource allocation design for minimizing the
maximum interference leakage to primary users while providing quality of
service for secondary users. The imperfectness of the channel state information
of the primary users is taken into account for robust resource allocation
algorithm design. The algorithm design is formulated as a non-convex
optimization problem and solved optimally by applying semidefinite programming
(SDP) relaxation. Simulation results not only show the significant reduction in
interference leakage compared to baseline schemes, but also confirm the
robustness of the proposed algorithm.


title:
Is a bivariate polynomial with plus minus 1 coefficients irreducible?
  Very likely!

abstract:
  We prove that a random bivariate polynomial with plus minus 1 coefficients is
irreducible with high probability.


title: Multi-task and Lifelong Learning of Kernels

abstract:
  We consider a problem of learning kernels for use in SVM classification in
the multi-task and lifelong scenarios and provide generalization bounds on the
error of a large margin classifier. Our results show that, under mild
conditions on the family of kernels used for learning, solving several related
tasks simultaneously is beneficial over single task learning. In particular, as
the number of observed tasks grows, assuming that in the considered family of
kernels there exists one that yields low approximation error on all tasks, the
overhead associated with learning such a kernel vanishes and the complexity
converges to that of learning when this good kernel is given to the learner.


title:
Arithmetic formulas for the Fourier coefficients of Hauptmoduln of level
  2, 3, and 5

abstract:
  We give arithmetic formulas for the coefficients of Hauptmoduln of higher
levels as analogues of Kaneko's result. We also obtain their asymptotic
formulas by employing Murty-Sampath's method.


title:
Quantitative discrimination between oil and water in drilled bore cores
  via fast-neutron resonance transmission radiography

abstract:
  A novel method based on Fast Neutron Resonance Transmission Radiography is
proposed for non-destructive, quantitative determination of the weight
percentages of oil and water in cores taken from subterranean or underwater
geological formations. The ability of the method to distinguish water from oil
stems from the unambiguously-specific energy dependence of the neutron
cross-sections for the principal elemental constituents. Monte-Carlo
simulations and initial results of experimental investigations indicate that
the technique may provide a rapid, accurate and non-destructive method for
quantitative evaluation of core fluids in thick intact cores, including those
of tight shales for which the use of conventional core analytical approaches
appears to be questionable.


title: Non-degeneracy conditions for braided finite tensor categories

abstract:
  For a braided finite tensor category $\mathcal{C}$ with unit object $1 \in
\mathcal{C}$, Lyubashenko considered a certain Hopf algebra $\mathbb{F} \in
\mathcal{C}$ endowed with a Hopf pairing $\omega: \mathbb{F} \otimes \mathbb{F}
\to 1$ to define the notion of a `non-semisimple' modular tensor category. We
say that $\mathcal{C}$ is non-degenerate if the Hopf pairing $\omega$ is
non-degenerate. In this paper, we show that $\mathcal{C}$ is non-degenerate if
and only if it is factorizable in the sense of Etingof, Nikshych and Ostrik, if
and only if its M\"uger center is trivial, if and only if the linear map
$\Omega: \mathrm{Hom}_{\mathcal{C}}(1, \mathbb{F}) \to
\mathrm{Hom}_{\mathcal{C}}(\mathbb{F}, 1)$ induced by the pairing $\omega$ is
invertible. As an application, we prove that the category of Yetter-Drinfeld
modules over a Hopf algebra in $\mathcal{C}$ is non-degenerate if and only if
$\mathcal{C}$ is.


title: On the curvature estimates for Hessian equations

abstract:
  The curvature estimates of $k$ curvature equations for general right hand
side is a longstanding problem. In this paper, we totally solve the $n-1$ case
and we also discuss some applications for our estimate.


title: On the Thermodynamic Limit of Bogoluibov's Theory of Bose Gas

abstract:
  Assuming that Bogoluibov's theory of weakly interacting dilute Bose gas
defines a self-consistent model Hamiltonian, we investigate its thermodynamic
limit as we take the volume to infinity, the infinite volume is taken via a
sequence of scaled convex regions with piecewise smooth boundary and the
volumes staying proportional to the cube of the diameter of the region. To get
a strict bound on the behavior of the thermodynamic limit, we use the recent
formulation of Bogoluibov's theory of condensation in terms of heat kernels for
a given domain as well as an estimate of the difference of traces between the
heat kernel with Neumann boundary conditions on this domain and the infinite
space result. We cannot control the limiting process by the area term, however
we can come arbitrarily close to it.


title:
Spaces of completions of elementary theories and convergence laws for
  random hypergraphs

abstract:
  Consider the binomial model $G^{d+1}(n,p)$ of the random $(d+1)$-uniform
hypergraph on $n$ vertices, where each edge is present, independently of one
another, with probability $p:\mathbb{N}\to[0,1]$. We prove that, for all
logarithmo-exponential $p\ll n^{-d+\epsilon}$, the probabilities of all
elementary properties of hypergraphs converge, with particular emphasis in the
ranges $p(n)\sim C/n^d$ and $p(n) \sim C\log(n)/n^d$. The exposition is unified
by constructing, for each such function $p$, the topological space of all
completions of its almost sure theory. This space turns out to be compact,
metrizable and totally disconnected, but further properties depend on the range
of $p$. The convergence of the probabilities of elementary properties is
associated with a borelian probability measure on the space.


title:
Comparison of local spherical characters and the Ichino-Ikeda conjecture
  for unitary groups

abstract:
  In this paper, we prove a conjecture of Wei Zhang on comparison of certain
local spherical characters from which we draw some consequences for the
Ichino-Ikeda conjecture for unitary groups.