title: Nucleosynthesis in the first massive stars

abstract:
  The nucleosynthesis in the first massive stars may be constrained by
observing the surface composition of long-lived very iron-poor stars born
around 10 billion years ago from material enriched by their ejecta. Many
interesting clues on physical processes having occurred in the first stars can
be obtained just based on nuclear aspects. Two facts are particularly clear, 1)
in these first massive stars, mixing must have occurred between the H-burning
and the He-burning zone during their nuclear lifetimes; 2) only the outer
layers of these massive stars have enriched the material from which the very
iron-poor stars, observed today in the halo, have formed. These two basic
requirements can be obtained by rotating stellar models at very low
metallicity. In the present paper, we discuss the arguments supporting this
view and illustrates the sensitivity of the results concerning the [Mg/Al]
ratio on the rate of the reaction Na(23)(p,\gamma)Mg(24).


title:
Game-theoretic Interpretation of Type Theory Part II: Uniqueness of
  Identity Proofs and Univalence

abstract:
  In the present paper, based on the previous work (Part I), we present a game
semantics for the intensional variant of intuitionistic type theory that
refutes the principle of uniqueness of identity proofs and validates the
univalence axiom, though we do not interpret non-trivial higher propositional
equalities. Specifically, following the historic groupoid interpretation by
Hofmann and Streicher, we equip predicative games in Part I with a groupoid
structure, which gives rise to the notion of (predicative) gamoids. Roughly,
gamoids are "games with (computational) equalities specified", which interpret
subtleties in Id-types. We then formulate a category with families of
predicative gamoids, equipped with dependent product, dependent sum, and
Id-types as well as universes, which forms a concrete instance of the groupoid
model. We believe that this work is an important stepping-stone towards a
complete interpretation of homotopy type theory.


title: Fast and Robust Hand Tracking Using Detection-Guided Optimization

abstract:
  Markerless tracking of hands and fingers is a promising enabler for
human-computer interaction. However, adoption has been limited because of
tracking inaccuracies, incomplete coverage of motions, low framerate, complex
camera setups, and high computational requirements. In this paper, we present a
fast method for accurately tracking rapid and complex articulations of the hand
using a single depth camera. Our algorithm uses a novel detection-guided
optimization strategy that increases the robustness and speed of pose
estimation. In the detection step, a randomized decision forest classifies
pixels into parts of the hand. In the optimization step, a novel objective
function combines the detected part labels and a Gaussian mixture
representation of the depth to estimate a pose that best fits the depth. Our
approach needs comparably less computational resources which makes it extremely
fast (50 fps without GPU support). The approach also supports varying static,
or moving, camera-to-scene arrangements. We show the benefits of our method by
evaluating on public datasets and comparing against previous work.


title: Some results related to the continuity problem

abstract:
  The continuity problem, i.e., the question whether effective maps between
effectively given topological spaces are effectively continuous, is
reconsidered. In earlier work it was shown that this is always the case, if the
effective map also has a witness for noninclusion. The extra condition does not
have an obvious topological interpretation. As is shown in the present paper,
it appears naturally where in the classical proof that sequentially continuous
maps are continuous the Axiom of Choice is used. The question is therefore
whether the witness condition appears in the general continuity theorem only
for this reason, i.e., whether effective operators are effectively sequentially
continuous. For two large classes of spaces covering all important applications
it is shown that this is indeed the case. The general question, however,
remains open.
  Spaces in this investigation are in general $\textit{not}$ required to be
Hausdorff. They only need to satisfy the weaker $T_0$ separation condition.


title:
The axiom of choice, co-comprehension schema and redundancies in
  triposes

abstract:
  We study the role of the axiom of choice and co-comprehention in second order
encoding of first order predicates logic


title:
Applications of the Variational Monte Carlo Method to the Ground States
  of the Lithium Atom and its Ions up to Z = 10 in the Presence of Magnetic
  Field

abstract:
  The variational Monte Carlo method is applied to investigate the ground state
energy of the lithium atom and its ions up to Z=10 in the presence of an
external magnetic field regime with {\gamma}=0 ~ 100 a.u. Our calculations are
based on using three forms of compact and accurate trial wave functions, which
were put forward in calculating energies in the absence of magnetic field. The
obtained results are in good agreement with the most recent accurate values and
also with the exact values.


title: Coin Betting and Parameter-Free Online Learning

abstract:
  In the recent years, a number of parameter-free algorithms have been
developed for online linear optimization over Hilbert spaces and for learning
with expert advice. These algorithms achieve optimal regret bounds that depend
on the unknown competitors, without having to tune the learning rates with
oracle choices.
  We present a new intuitive framework to design parameter-free algorithms for
\emph{both} online linear optimization over Hilbert spaces and for learning
with expert advice, based on reductions to betting on outcomes of adversarial
coins. We instantiate it using a betting algorithm based on the
Krichevsky-Trofimov estimator. The resulting algorithms are simple, with no
parameters to be tuned, and they improve or match previous results in terms of
regret guarantee and per-round complexity.


title: Learning may need only a few bits of synaptic precision

abstract:
  Learning in neural networks poses peculiar challenges when using discretized
rather then continuous synaptic states. The choice of discrete synapses is
motivated by biological reasoning and experiments, and possibly by hardware
implementation considerations as well. In this paper we extend a previous large
deviations analysis which unveiled the existence of peculiar dense regions in
the space of synaptic states which accounts for the possibility of learning
efficiently in networks with binary synapses. We extend the analysis to
synapses with multiple states and generally more plausible biological features.
The results clearly indicate that the overall qualitative picture is unchanged
with respect to the binary case, and very robust to variation of the details of
the model. We also provide quantitative results which suggest that the
advantages of increasing the synaptic precision (i.e.~the number of internal
synaptic states) rapidly vanish after the first few bits, and therefore that,
for practical applications, only few bits may be needed for near-optimal
performance, consistently with recent biological findings. Finally, we
demonstrate how the theoretical analysis can be exploited to design efficient
algorithmic search strategies.


title:
Bad irreducible subgroups and singular locus for character varieties in
  $PSL(p,\mathbb{C})$

abstract:
  We describe the centralizer of irreducible representations from a finitely
generated group $\Gamma$ to $PSL(p,\mathbb{C})$ where $p$ is a prime number.
This leads to a description of the singular locus (the set of conjugacy classes
of representations whose centralizer strictly contains the center of the
ambient group) of the irreducible part of the character variety
$\chi^i(\Gamma,PSL(p,\mathbb{C}))$. When $\Gamma$ is a free group of rank
$l\geq 2$ or the fundamental group of a closed Riemann surface of genus $g\geq
2$, we give a complete description of this locus and prove that this locus is
exactly the set of algebraic singularities of the irreducible part of the
character variety.


title: On homotopy types of Euclidean Rips complexes

abstract:
  The Rips complex at scale r of a set of points X in a metric space is the
abstract simplicial complex whose faces are determined by finite subsets of X
of diameter less than r. We prove that for X in the Euclidean 3-space R^3 the
natural projection map from the Rips complex of X to its shadow in R^3 induces
a surjection on fundamental groups. This partially answers a question of
Chambers, de Silva, Erickson and Ghrist who studied this projection for subsets
of R^2. We further show that Rips complexes of finite subsets of R^n are
universal, in that they model all homotopy types of simplicial complexes
PL-embeddable in R^n. As an application we get that any finitely presented
group appears as the fundamental group of a Rips complex of a finite subset of
R^4. We furthermore show that if the Rips complex of a finite point set in R^2
is a normal pseudomanifold of dimension at least two then it must be the
boundary of a crosspolytope.


title: On the interpretation and applicability of $\kappa$-distributions

abstract:
  The generally accepted representation of $\kappa$-distributions in space
plasma physics allows for two different alternatives, namely assuming either
the temperature or the thermal velocity to be $\kappa$-independent. The present
paper aims to clarify the issue concerning which of the two possible choices
and the related physical interpretation is the correct one. A quantitative
comparison of the consequences of the use of both distributions for specific
physical systems leads to their correct interpretation. It is found that both
alternatives can be realized, but are valid for principally different physical
systems. The investigation demonstrates that, before employing one of the two
alternatives, one should be conscious about the nature of the physical system
one intends to describe, otherwise one would possibly obtain unphysical
results.


title:
Deep Gaussian Processes for Regression using Approximate Expectation
  Propagation

abstract:
  Deep Gaussian processes (DGPs) are multi-layer hierarchical generalisations
of Gaussian processes (GPs) and are formally equivalent to neural networks with
multiple, infinitely wide hidden layers. DGPs are nonparametric probabilistic
models and as such are arguably more flexible, have a greater capacity to
generalise, and provide better calibrated uncertainty estimates than
alternative deep models. This paper develops a new approximate Bayesian
learning scheme that enables DGPs to be applied to a range of medium to large
scale regression problems for the first time. The new method uses an
approximate Expectation Propagation procedure and a novel and efficient
extension of the probabilistic backpropagation algorithm for learning. We
evaluate the new method for non-linear regression on eleven real-world
datasets, showing that it always outperforms GP regression and is almost always
better than state-of-the-art deterministic and sampling-based approximate
inference methods for Bayesian neural networks. As a by-product, this work
provides a comprehensive analysis of six approximate Bayesian methods for
training neural networks.


title: Parastrophes of quasigroups

abstract:
  Parastrophes (conjugates) of a quasigroup can be divided into separate
classes containing isotopic parastrophes. We prove that the number of such
classes is always 1, 2, 3 or 6. Next we characterize quasigroups having a fixed
number of such classes.


title:
Cylindrical estimates for mean curvature flow of hypersurfaces in
  CROSSes

abstract:
  We consider the mean curvature flow of a closed hypersurface in the complex
or quaternionic projective space. Under a suitable pinching assumption on the
initial data, we prove apriori estimates on the principal curvatures which
imply that the asymptotic profile near a singularity is either strictly convex
or cylindrical. This result generalizes to a large class of symmetric ambient
spaces the estimates obtained in the previous works on the mean curvature flow
of hypersurfaces in Euclidean space and in the sphere.


title: The equilibrium classical scatter spectrum of waves

abstract:
  Regardless of the unspecific notions of photons as light complexes, radiation
bundles or wave packets, the radiation from a single state transition is at
most a single continuous wave train that starts and ends with the transition.
The radiation equilibrium spectrum must be the superposition sum of the spectra
of such wave trains. A classical equipartition of wave trains cannot diverge
since they would be finite in number, whereas standing wave modes are by
definition infinite, which had doomed Rayleigh's theory, and concern only the
total radiation. Wave trains are the microscopic entities of radiation
interacting with matter, that correspond to molecules in kinetic theory. Their
quantization came from matter transitions in Einstein's 1917 derivation of
Planck's law. The spectral scatter of wave trains by Doppler shifts, which
cause the wavelength displacements in Wien's law used for the frequency
dependence in Einstein's derivation, is shown to yield the shape of the Planck
spectrum. A Lorentz transform property of Doppler shifts discovered by Einstein
is further shown equivalently necessary and sufficient to have corrected
Rayleigh's theory.


title: A Graph-Theoretic Approach to Efficient Voice-Leading

abstract:
  We study the Neo-Riemannian principle of parsimonious voice-leading using
tools and techniques from classical graph theory and the modern field of
complex networks. We quantify the relative importance of particular chords
within this framework. The graph-theoretic notion of eccentricity suggests that
when working in a harmonic scheme dictated by any common musical scale, no
triad is any more isolated than any other. Complex network theory refines this
idea, and in this context provides measures of how important particular triads
might be for the flow of chord progressions through the harmonic network. We
review and compare several different such measures of centrality and
communicability.


title: Practical Fault-Tolerant Data Aggregation

abstract:
  During Financial Cryptography 2012 Chan et al. presented a novel
privacy-protection fault-tolerant data aggregation protocol. Comparing to
previous work, their scheme guaranteed provable privacy of individuals and
could work even if some number of users refused to participate. In our paper we
demonstrate that despite its merits, their method provides unacceptably low
accuracy of aggregated data for a wide range of assumed parameters and cannot
be used in majority of real-life systems. To show this we use both precise
analytic and experimental methods. Additionally, we present a precise data
aggregation protocol that provides provable level of security even facing
massive failures of nodes. Moreover, the protocol requires significantly less
computation (limited exploiting of heavy cryptography) than most of currently
known fault tolerant aggregation protocols and offers better security
guarantees that make it suitable for systems of limited resources (including
sensor networks). To obtain our result we relax however the model and allow
some limited communication between the nodes.


title:
Quantile-based bias correction and uncertainty quantification of extreme
  event attribution statements

abstract:
  Extreme event attribution characterizes how anthropogenic climate change may
have influenced the probability and magnitude of selected individual extreme
weather and climate events. Attribution statements often involve quantification
of the fraction of attributable risk (FAR) or the risk ratio (RR) and
associated confidence intervals. Many such analyses use climate model output to
characterize extreme event behavior with and without anthropogenic influence.
However, such climate models may have biases in their representation of extreme
events. To account for discrepancies in the probabilities of extreme events
between observational datasets and model datasets, we demonstrate an
appropriate rescaling of the model output based on the quantiles of the
datasets to estimate an adjusted risk ratio. Our methodology accounts for
various components of uncertainty in estimation of the risk ratio. In
particular, we present an approach to construct a one-sided confidence interval
on the lower bound of the risk ratio when the estimated risk ratio is infinity.
We demonstrate the methodology using the summer 2011 central US heatwave and
output from the Community Earth System Model. In this example, we find that the
lower bound of the risk ratio is relatively insensitive to the magnitude and
probability of the actual event.


title: Measuring Electromagnetic Vector Potential via Weak Value

abstract:
  Electromagnetic vector potential has physical significance in quantum
mechanics as revealed by the Aharonov-Bohm effect for charged particles.
However, till date it is thought that we cannot measure the vector potential
directly as this is not a gauge invariant quantity. Contrary to this belief,
here we show that one can indeed measure the electromagnetic vector potential
using the notion of weak value. We show that it is simply the difference
between the weak value of the canonical momentum of a charged particle in the
presence and absence of magnetic field. This suggests that the vector potential
is not only a physical entity but can be measured directly in the experiment.


title: Versatile Approach to the Spin Dynamics in Correlated Electron Systems

abstract:
  Time-dependent spin phenomena in condensed matter are most often either
described in the weakly correlated limit of metallic Stoner/Slater-like
magnetism via band theory or in the strongly correlated limit of
Heisenberg-like interacting spins in an insulator. However many experimental
studies, e.g. of (de)magnetization processes, focus on itinerant local-moment
materials such as transition metals and various of their compounds. We here
present a general theoretical framework that is capable of addressing
correlated spin dynamics, also in the presence of a vanishing charge gap. A
real-space implementation of the time-dependent rotational-invariant slave
boson methodology allows to treat non-equilibrium spins numerically fast and
efficiently beyond linear response as well as beyond the band-theoretical or
Heisenberg limit.


title:
Tricritical points in a compact $U(1)$ lattice gauge theory at strong
  coupling

abstract:
  Pure {\it compact} $U(1)$ lattice gauge theory exhibits a phase transition at
gauge coupling $g \sim {\cal{O}}(1)$ separating a familiar weak coupling
Coulomb phase, having free massless photons, from a strong coupling phase.
However, the phase transition was found to be of first order, ruling out any
nontrivial theory resulting from a continuum limit from the strong coupling
side. In this work, a compact $U(1)$ lattice gauge theory is studied with
addition of a dimension-two mass counterterm and a higher derivative (HD) term
that ensures a unique vacuum and produces a covariant gauge-fixing term in the
naive continuum limit. For a reasonably large coefficient of the HD term, now
there exists a continuous transition from a regular ordered phase to a
spatially modulated ordered phase. For weak gauge couplings, a continuum limit
from the regular ordered phase results in a familiar theory consisting of free
massless photons. For strong gauge couplings with $g\ge {\cal{O}}(1)$, this
transition changes from first order to continuous as the coefficient of the HD
term is increased, resulting in tricritical points which appear to be a
candidate in this theory for a possible nontrivial continuum limit.


title: Interaction-Enhanced Imaging of Rydberg P states

abstract:
  The Interaction Enhanced Imaging technique allows to detect the spatial
distribution of strongly interacting impurities embedded within a gas of
background atoms used as a contrast medium. Here we present a detailed study of
this technique, applied to detect Rydberg $P$ states. We experimentally realize
fast and efficient three-photon excitation of $P$ states, optimized according
to the results of a theoretical effective two-level model. Few Rydberg
$P$-state atoms, prepared in a small cloud with dimensions comparable to the
blockade radius, are detected with a good sensitivity by averaging over 50
shots. The main aspects of the technique are described with a hard-sphere
model, finding good agreement with experimental data. This work paves the way
to a non-destructive optical detection of single Rydberg atoms with high
spatial and temporal resolution.


title:
Very large domain wall velocities in Pt/Co/Gd trilayers with
  Dzyaloshinskii-Moriya interaction

abstract:
  We carried out measurements of domain wall (DW) velocities driven by magnetic
field pulses in symmetric Pt/Co/Pt and asymmetric Pt/Co/AlOx, Pt/Co/GdOx and
Pt/Co/Gd trilayers with ultrathin Co layers and perpendicular magnetic
anisotropy. In agreement with theoretical models, the maximum observed velocity
is much larger in the asymmetric samples, where the interfacial
Dzyaloshinskii-Moriya interaction (DMI) stabilises chiral N\'eel walls, than in
the symmetric stack. In addition, in Pt/Co/Gd very large DW speeds (up to 600
m/s) are obtained, 2.5 times larger than in samples with oxidised Gd. Magnetic
measurements reveal that this may be explained by the anti-parallel coupling
between the magnetic moments of Gd and Co at the Gd/Co interface, leading to a
decrease of the total magnetisation. In quantitative agreement with analytical
models, in all samples the maximum observed DW speed scales as D=Ms, where D is
the strength of the DMI and Ms the spontaneous magnetisation.


title: Complexity classification of two-qubit commuting hamiltonians

abstract:
  We classify two-qubit commuting Hamiltonians in terms of their computational
complexity. Suppose one has a two-qubit commuting Hamiltonian H which one can
apply to any pair of qubits, starting in a computational basis state. We prove
a dichotomy theorem: either this model is efficiently classically simulable or
it allows one to sample from probability distributions which cannot be sampled
from classically unless the polynomial hierarchy collapses. Furthermore, the
only simulable Hamiltonians are those which fail to generate entanglement. This
shows that generic two-qubit commuting Hamiltonians can be used to perform
computational tasks which are intractable for classical computers under
plausible assumptions. Our proof makes use of new postselection gadgets and Lie
theory.


title:
Decoupled Dynamics Distributed Control for Strings of Nonlinear
  Autonomous Agents

abstract:
  We introduce a distributed control architecture for a class of heterogeneous,
nonlinear dynamical agents moving in the "string" formation, while guaranteeing
trajectory tracking, collision avoidance and the preservation of the
formation's topology. Each autonomous agent uses information and relative
measurements only with respect to its predecessor in the string. The
performance of the scheme is independent of the number of agents in the network
and also on the agent's relative position in the network. The scalability is a
consequence of the "decoupling" of a certain bounded approximation of the
closed--loop equations, which allows the regulation and controller design (at
each agent) to be done individually, in a completely decentralized manner. A
practical method for compensating communication induced delays is also
presented. Numerical examples illustrate the effectiveness and the main
features of the proposed approach.


title: On the Schr\"odinger-Maxwell system involving sublinear terms

abstract:
  In this paper we study the coupled Schr\"odinger-Maxwell system $$\left\{
\begin{array}{lll} -\triangle u+u +\phi u=\lambda \alpha(x) f(u)& {\rm in} &
\mathbb R^3,\\ -\triangle \phi =u^2 & {\rm in} & \mathbb R^3,
\end{array}\right. $$ where $\alpha\in L^\infty(\mathbb R^3)\cap
L^{6/(5-q)}(\mathbb R^3)$ for some $q\in (0,1)$, and the continuous function
$f:\mathbb{R}\to\mathbb{R}$ is superlinear at zero and sublinear at infinity,
e.g., $f(s) = \min(|s|^r,|s|^p)$ with $0<r<1<p.$ Depending on the range of
$\lambda>0$, non-existence and multiplicity results are obtained.


title:
Multiple solutions for a Neumann system involving subquadratic
  nonlinearities

abstract:
  In this paper we consider the model semilinear Neumann system $$\left\{
\begin{array}{lll} -\Delta u+a(x)u=\lambda c(x) F_u(u,v)& {\rm in} & \Omega,\\
-\Delta v+b(x)v=\lambda c(x) F_v(u,v)& {\rm in} & \Omega,\\ \frac{\partial
u}{\partial \nu}=\frac{\partial v}{\partial \nu}=0 & {\rm on} & \partial\Omega,
\end{array}\right.$$ where $\Omega\subset \mathbb R^N$ is a smooth open bounded
domain, $\nu$ denotes the outward unit normal to $\partial \Omega$,
$\lambda\geq 0$ is a parameter, $a,b,c\in L_+^\infty(\Omega)\setminus\{0\},$
and $F\in C^1(\mathbb{R}^2,\mathbb{R})\setminus\{0\}$ is a nonnegative function
which is subquadratic at infinity. Two nearby numbers are determined in
explicit forms, $\underline \lambda$ and $\overline \lambda$ with $
0<\underline\lambda\leq \overline \lambda$, such that for every $0\leq
\lambda<\underline \lambda$, system $(N_\lambda)$ has only the trivial pair of
solution, while for every $\lambda>\overline \lambda$, system $(N_\lambda)$ has
at least two distinct nonzero pairs of solutions.


title: On Binomial Identities in Arbitrary Bases

abstract:
  We extend the digital binomial identity as given by Nguyen el al. to an
identity in an arbitrary base $b$, by introducing the $b-$ary binomial
coefficients. We then study the properties of these coefficients such as
orthogonality, a link to Lucas' theorem and the corresponding $b-$ary Pascal
triangles.


title:
Non-equilibrium itinerant-electron magnetism: a time-dependent
  mean-field theory

abstract:
  We study the dynamical magnetic susceptibility of a strongly correlated
electronic system in the presence of a time-dependent hopping field, deriving a
generalized Bethe-Salpeter equation which is valid also out of equilibrium.
Focusing on the single-orbital Hubbard model within the time-dependent
Hartree-Fock approximation, we solve the equation in the non-equilibrium
adiabatic regime, obtaining a closed expression for the transverse magnetic
susceptibility. From this, we provide a rigorous definition of non-equilibrium
(time-dependent) magnon frequencies and exchange parameters, expressed in terms
of non-equilibrium single-electron Green functions and self-energies. In the
particular case of equilibrium, we recover previously known results.


title: Generalization of the possible algebraic basis of $q$-triplets

abstract:
  The so called $q$-triplets were conjectured in 2004 and then found in nature
in 2005. A relevant further step was achieved in 2005 when the possibility was
advanced that they could reflect an entire infinite algebra based on
combinations of the self-dual relations $q \to 2-q$ ({\it additive duality})
and $q \to 1/q$ ({\it multiplicative duality}). The entire algebra collapses
into the single fixed point $q=1$, corresponding to the Boltzmann-Gibbs entropy
and statistical mechanics. For $q \ne 1$, an infinite set of indices $q$
appears, corresponding in principle to an infinite number of physical
properties of a given complex system describable in terms of the so called
$q$-statistics. The basic idea that is put forward is that, for a given
universality class of systems, a small number (typically one or two) of
independent $q$ indices exist, the infinite others being obtained from these
few ones by simply using the relations of the algebra. The $q$-triplets appear
to constitute a few central elements of the algebra. During the last decade, an
impressive amount of $q$-triplets have been exhibited in analytical,
computational, experimental and observational results in natural, artificial
and social systems. Some of them do satisfy the available algebra constructed
solely with the additive and multiplicative dualities, but some others seem to
violate it. In the present work we generalize those two dualities with the hope
that a wider set of systems can be handled within. The basis of the
generalization is given by the {\it selfdual} relation $q \to q_a(q) \equiv
\frac{(a+2) -aq}{a-(a-2)q} \,\, (a \in {\cal R})$. We verify that $q_a(1)=1$,
and that $q_2(q)=2-q$ and $q_0(q)=1/q$. To physically motivate this
generalization, we briefly review illustrative applications of $q$-statistics,
in order to exhibit possible candidates where the present generalized algebras
could be useful.


title: On Metric Multi-Covering Problems

abstract:
  In the metric multi-cover problem (MMC), we are given two point sets $Y$
(servers) and $X$ (clients) in an arbitrary metric space $(X \cup Y, d)$, a
positive integer $k$ that represents the coverage demand of each client, and a
constant $\alpha \geq 1$. Each server can have a single ball of arbitrary
radius centered on it. Each client $x \in X$ needs to be covered by at least
$k$ such balls centered on servers. The objective function that we wish to
minimize is the sum of the $\alpha$-th powers of the radii of the balls.
  In this article, we consider the MMC problem as well as some non-trivial
generalizations, such as (a) the non-uniform MMC, where we allow
client-specific demands, and (b) the $t$-MMC, where we require the number of
open servers to be at most some given integer $t$. For each of these problems,
we present an efficient algorithm that reduces the problem to several instances
of the corresponding $1$-covering problem, where the coverage demand of each
client is $1$. Our reductions preserve optimality up to a multiplicative
constant factor.
  Applying known constant factor approximation algorithms for $1$-covering, we
obtain the first constant approximations for the MMC and these generalizations.


title: Probing Local Structure in Glass by the Application of Shear

abstract:
  The glass transition remains one of the great unsolved mysteries of
contemporary condensed matter physics. When crystallization is bypassed by
rapid cooling, a supercooled liquid, retaining amorphous particle arrangment,
results. The physical phenomenology of supercooled liquids is as vast as it is
interesting. Most significant, the viscosity of the supercooled liquid displays
an incredible increase over a narrow temperature range. Eventually, the
supercooled liquid ceases to flow, becomes a glass, and gains rigidity and
solid-like behaviors. Understanding what underpins the monumental growth of
viscosity, and how rigidity results without long range order is a long-sought
goal. Many theories of the glassy slowdown require the growth of static
lengthscale related to structure with lowering of the temperature. To that end,
we have proposed a new, natural lengthscale- "the shear penetration depth".
This lengthscale quantifies the structural connectivity of the supercooled
liquid. The shear penetration depth is defined as the distance up to which a
shear perturbation applied to the boundary propagates into the liquid. We
provide numerical data, based on the simulations of $NiZr_2$, illustrating that
this length scale exhibits dramatic growth and eventual divergence upon
approach to the glass transition. We further discuss this in relation to
percolating structural connectivity and a new theory of the glass transition.


title:
Tilt Angle and Footpoint Separation of Small and Large Bipolar Sunspot
  Regions Observed with HMI

abstract:
  We investigate bipolar sunspot regions and how tilt angle and footpoint
separation vary during emergence and decay. The Helioseismic and Magnetic
Imager on board the Solar Dynamic Observatory collects data at a higher cadence
than historical records and allows for a detailed analysis of regions over
their lifetimes. We sample the umbral tilt angle, footpoint separation, and
umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager
- Debrecen Data (HMIDD) with an hourly cadence. We use the time when the umbral
area peaks as time zero to distinguish between the emergence and decay periods
of each region and we limit our analysis of tilt and separation behavior over
time to within +/-96 hours of time zero. Tilt angle evolution is distinctly
different for regions with small (~30 MSH), midsize (~50 MSH), and large (~110
MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions in
separating the groups. At the peak umbral area, we determine median tilt angles
for small (7.6 degrees), midsize (5.9 degrees) and large (9.3 degrees) regions.
Within +/-48 hours of the time of peak umbral area, large regions steadily
increase in tilt angle, midsize regions are nearly constant, and small regions
show evidence of negative tilt during emergence. A period of growth in
footpoint separation occurs over a 72-hr period for all of the regions from
roughly 40 to 70 Mm. The smallest bipoles (< 9 MSH) are outliers in that they
do not obey Joy's law and have a much smaller footpoint separation. We confirm
Munoz-Jaramillo et al. (2015) results that the sunspots appear to be two
distinct populations.


title: Cohomological framework for contextual quantum computations

abstract:
  We describe a cohomological framework for measurement based quantum
computation, in which symmetry plays a central role. Therein, the essential
information about the computational output is contained in topological
invariants, namely elements of two cohomology groups. One of those invariants
applies to the deterministic case, and the other to the general probabilistic
case. The same invariants also witness quantumness in the form of
contextuality. In result, they give rise to fundamental algebraic structures
underlying quantum computation.


title:
Pan-STARRS and PESSTO search for an optical counterpart to the LIGO
  gravitational wave source GW150914

abstract:
  We searched for an optical counterpart to the first gravitational wave source
discovered by LIGO (GW150914), using a combination of the Pan-STARRS1
wide-field telescope and the PESSTO spectroscopic follow-up programme. As the
final LIGO sky maps changed during analysis, the total probability of the
source being spatially coincident with our fields was finally only 4.2 per
cent. Therefore we discuss our results primarily as a demonstration of the
survey capability of Pan-STARRS and spectroscopic capability of PESSTO. We
mapped out 442 square degrees of the northern sky region of the initial map. We
discovered 56 astrophysical transients over a period of 41 days from the
discovery of the source. Of these, 19 were spectroscopically classified and a
further 13 have host galaxy redshifts. All transients appear to be fairly
normal supernovae and AGN variability and none is obviously linked with
GW150914. We illustrate the sensitivity of our survey by defining parameterised
lightcurves with timescales of 4, 20 and 40 days and use the sensitivity of the
Pan-STARRS1 images to set limits on the luminosities of possible sources. The
Pan-STARRS1 images reach limiting magnitudes of i = 19.2, 20.0 and 20.8
respectively for the three timescales. For long timescale parameterised
lightcurves (with FWHM=~40d) we set upper limits of M_i <= -17.2 -0.9/+1.4 if
the distance to GW150914 is D = 400 +/- 200Mpc. The number of type Ia SN we
find in the survey is similar to that expected from the cosmic SN rate,
indicating a reasonably complete efficiency in recovering supernova like
transients out to D = 400 +/- 200 Mpc.


title: Nash-type equilibria on Riemannian manifolds: a variational approach

abstract:
  Motivated by Nash equilibrium problems on 'curved' strategy sets, the concept
of Nash-Stampacchia equilibrium points is introduced via variational
inequalities on Riemannian manifolds. Characterizations, existence, and
stability of Nash-Stampacchia equilibria are studied when the strategy sets are
compact/noncompact geodesic convex subsets of Hadamard manifoleds, exploiting
two well-known geometrical features of these spaces both involving the metric
projection map. These properties actually characterize the {non-positivity} of
the sectional curvature of complete and simply connected Riemannian spaces,
delimiting the Hadamard manifolds as the optimal geometrical framework of
Nash-Stampacchia equilibrium problems. Our analytical approach exploits various
elements from set-valued and variational analysis, dynamical systems, and
non-smooth calculus on Riemannian manifolds. Examples are presented on the
Poincar\'e upper-plane model and on the open convex cone of symmetric positive
definite matrices endowed with the trace-type Killing form.


title:
The 80 Ms follow-up of the X-ray afterglow of GRB 130427A challenges the
  standard forward shock model

abstract:
  GRB 130427A was the brightest gamma-ray burst detected in the last 30 years.
With an equivalent isotropic energy output of $8.5\times10^{53}$ erg and
redshift $z=0.34$, it uniquely combined very high energetics with a relative
proximity to Earth. As a consequence, its X-ray afterglow has been detected by
sensitive X-ray observatories such as XMM-Newton and Chandra for a
record-breaking baseline longer than 80 million seconds. We present the X-ray
light-curve of this event over such an interval. The light-curve shows a simple
power-law decay with a slope $\alpha = 1.309 \pm 0.007$ over more than three
decades in time (47 ks - 83 Ms). We discuss the consequences of this result for
a few models proposed so far to interpret GRB 130427A, and more in general the
significance of this outcome in the context of the standard forward shock
model. We find that this model has difficulty in explaining our data, in both
cases of constant density and stellar wind circumburst media, and requires
far-fetched values for the physical parameters involved.


title: Twistor Spaces of Riemannian Manifolds with Even Clifford Structures

abstract:
  In this paper we introduce the twistor space of a Riemannian manifold with an
even Clifford structure. This notion generalizes the twistor space of
quaternion-Hermitian manifolds and weak-Spin(9) structures. We also construct
almost complex structures on the twistor space for parallel even Clifford
structures and check their integrability. Moreover, we prove that in some cases
one can give K\"ahler and Nearly-K\"ahler metrics to these spaces.


title:
Updates on the Studies of $N^*$ Structure with CLAS and the Prospects
  with CLAS12

abstract:
  The recent results on $\gamma_vpN^*$ electrocouplings from analyses of the
data on exclusive meson electroproduction off protons measured with the CLAS
detector at Jefferson Lab are presented. The impact of these results on the
exploration of the excited nucleon state structure and non-perturbative strong
interaction dynamics behind its formation is outlined. The future extension of
these studies in the experiments with the CLAS12 detector in the upgraded
Hall-B at JLab will provide for the first time $\gamma_vpN^*$ electrocouplings
of all prominent resonances at the still unexplored distance scales that
correspond to extremely low (0.05 GeV$^2 < Q^2 <$ 0.5 GeV$^2$) and the highest
photon virtualities (5.0 GeV$^2 < Q^2 <$ 12.0 GeV$^2$) ever achieved in the
exclusive electroproduction measurements. The expected results will address the
most important open problems of the Standard Model: on the nature of more than
98\% of hadron mass, quark-gluon confinement and emergence of the excited
nucleon state structure from the QCD Lagrangian, as well as allowing a search
for the new states of hadron matter predicted from the first principles of QCD,
the so-called hybrid baryons.


title: Rashba splitting of Cooper pairs

abstract:
  We investigate theoretically the properties of a weak link between two
superconducting leads, which has the form of a non-superconducting nanowire
with a strong Rashba spin-orbit coupling caused by an electric field. In the
Coulomb blockade regime of single-electron tunneling, we find that such a weak
link acts as a "spin splitter" of the spin states of Cooper pairs tunneling
through the link, to an extent that depends on the direction of the electric
field. We show that the Josephson current is sensitive to interference between
the resulting two transmission channels, one where the spins of both members of
a Cooper pair are preserved and one where they are both flipped. As a result,
the current is a periodic function of the strength of the spin-orbit
interaction and of the bending angle of the nanowire (when mechanically bent);
an identical effect appears due to strain-induced spin-orbit coupling. In
contrast, no spin-orbit induced interference effect can influence the current
through a single weak link connecting two normal metals.


title:
Spin-dependent recombination in GaAs(1-x)N(x) alloys at oblique magnetic
  field

abstract:
  We have studied experimentally and theoretically the optical orientation and
spin-dependent Shockley-Read-Hall recombination in a semiconductor in a
magnetic field at an arbitrary angle between the field and circularly polarized
exciting beam. The experiments are performed at room temperature in GaAsN
alloys where deep paramagnetic centers are responsible for the spin-dependent
recombination. The observed magnetic-field dependences of the circular
polarization r(B) and intensity J(B) of photoluminescence can be approximately
described as a superposition of two Lorentzian contours, normal and inverted,
with their half-widths differing by an order of magnitude. The normal (narrow)
Lorentzian contour is associated with depolarization of the transverse (to the
field) component of spin polarization of the localized electrons, whereas the
inverted (broad) Lorentzian is due to suppression of the hyperfine interaction
of the localized electron with the defect nucleus. The ratio between the height
of one Lorentzian and depth of the other is governed by the field tilt angle.
In contrast to the hyperfine interaction of a shallow-donor-bound electron with
a large number of nuclei of the crystal lattice, in the optical orientation of
the electron-nuclear system under study no additional narrow peak appears in
the oblique field. This result demonstrates that in the GaAsN alloys the
hyperfine interaction of the localized electron with the single nucleus of the
paramagnetic center remains strong even at room temperature. For a theoretical
description of the experiment, we have extended the theory of spin-dependent
recombination via deep paramagnetic centers with the nuclear angular momentum I
= 1/2 developed previously for the particular case of the longitudinal field.
The calculated curves r(B), J(B) agree with the approximate description of the
experimental dependences as a sum of two Lorentzians.


title: Construction of Categorical Bundles from Local Data

abstract:
  A categorical principal bundle is a structure comprised of categories that is
analogous to a classical principal bundle; examples arise from geometric
contexts involving bundles over path spaces. We show how a categorical
principal bundle can be constructed from local data specified through
transition functors and natural transformations.


title:
A Vlasov-Poisson plasma with unbounded mass and velocities confined in a
  cylinder by a magnetic mirror

abstract:
  We study the time evolution of a single species positive plasma, confined in
a cylinder and having infinite charge. We extend the result of a previous work
by the same authors, for a plasma density having compact support in the
velocities, to the case of a density having unbounded support and gaussian
decay in the velocities.


title:
Surface family with a common natural asymptotic lift of a timelike curve
  in Minkowski 3-space

abstract:
  In the present paper, we find a surface family possessing the natural lift of
a given timelike curve as a asymptotic in Minkowski 3-space. We express
necessary and sufficient conditions for the given curve such that its natural
lift is a asymptotic on any member of the surface family. Finally, we
illustrate the method with some examples.


title: Deterministic Local Expansion of W States

abstract:
  In large quantum systems multipartite entanglement can be found in many
inequivalent classes under local operations and classical communication.
Preparing states of arbitrary size in different classes is important for
performing a wide range of quantum protocols. W states, in particular,
constitute a class with a variety of quantum networking protocols. However, all
known schemes for preparing W states are probabilistic, with resource
requirements increasing at least sub-exponentially. We propose a deterministic
scheme for preparing W states that requires no prior entanglement and can be
performed locally. We introduce an all-optical setup that can efficiently
prepare W states of arbitrary size. Our scheme advances the use of W states in
real-world quantum networks and could be extended to other physical systems.


title: Matrix approach to hypercomplex Appell polynomials

abstract:
  Recently the authors presented a matrix representation approach to real
Appell polynomials essentially determined by a nilpotent matrix with natural
number entries. It allows to consider a set of real Appell polynomials as
solution of a suitable first order initial value problem. The paper aims to
confirm that the unifying character of this approach can also be applied to the
construction of homogeneous Appell polynomials that are solutions of a
generalized Cauchy-Riemann system in Euclidean spaces of arbitrary dimension.
The result contributes to the development of techniques for polynomial
approximation and interpolation in non-commutative Hypercomplex Function
Theories with Clifford algebras.


title:
Parameter Estimation with Dzyaloshinskii-Moriya Interaction under
  External Magnetic Fields

abstract:
  We study the effects of external magnetic fields on the precision of
parameter estimation with thermal entanglement of two spins in XX model, in the
presence of Dzyaloshinskii-Moriya (DM) interaction. Calculating the quantum
Fisher information, we show that homogeneous magnetic field B, inhomogeneous
magnetic field b or DM interaction D increases the precision of parameter
estimation, overwhelming the destructive effects of thermalization. We also
show that for the model in consideration, the effects of b and D are the same.
However, the existence of both b and B (or both D and B) decreases the
precision. We find that in order to increase the precision in parameter
estimation tasks, applying b in the ferromagnetic case and B in the
antiferromagnetic case should be preferred.


title: A tunable low-drift laser stabilized to an atomic reference

abstract:
  We present a laser system with a linewidth and long-term frequency stability
at the 50 kHz level. It is based on a Ti:Sapphire laser emitting radiation at
882 nm which is referenced to an atomic transition. For this, the length of an
evacuated transfer cavity is stabilized to a reference laser at 780 nm locked
to the $^{85}$Rb D$_2$-line via modulation transfer spectroscopy. Gapless
frequency tuning of the spectroscopy laser is realized using the sideband
locking technique to the transfer cavity. In this configuration, the linewidth
of the spectroscopy laser is derived from the transfer cavity, while the
long-term stability is derived from the atomic resonance. Using an optical
frequency comb, the frequency stability and linewidth of both lasers are
characterized by comparison against an active hydrogen maser frequency standard
and an ultra-narrow linewidth laser, respectively. The laser system presented
here will be used for spectroscopy of the $1s^{2}2s^{2}2p\ ^{2}P_{1/2} -\
^{2}P_{3/2}$ transition in sympathetically cooled Ar$^{13+}$ ions at 441nm
after frequency doubling.


title: Models of LHC Diphoton Excesses Valid up to the Planck scale

abstract:
  We discuss a possibility to explain the LHC diphoton excesses at $750$GeV by
the new scalar $X$ that couples to the gauge bosons through the loop of new
massive particles with Standard Model charges. We assume that the new particles
decay into the Standard Model particles at the tree level. We systematically
examine the models that preserve the vacuum stability and the perturbativity up
to the Planck scale. When we take scalars for the new particles, we find that
only a few diquark and dilepton models can explain the observed diphoton cross
section without conflicting the experimental mass bounds. When we take
vector-like fermions for the new particles, we find rather different situations
depending on whether their couplings to $X$ are scalar or pseudoscalar type. In
the former case, a few models are allowed if we introduce only one species of
fermions. The more fermions we introduce, the more models are allowed. In the
later case, the most of the models are allowed because of the large coupling
between $X$ and photon. It is interesting that the allowed mass regions of the
scalar particles might be reached by the next lepton colliders.


title: Optimal conditional expectation at the video poker game Jacks or Better

abstract:
  There are 134,459 distinct initial hands at the video poker game Jacks or
Better, taking suit exchangeability into account. A computer program can
determine the optimal strategy (i.e., which cards to hold) for each such hand,
but a complete list of these strategies would require a book-length manuscript.
Instead, a hand-rank table, which fits on a single page and reproduces the
optimal strategy perfectly, was found for Jacks or Better as early as the mid
1990s. Is there a systematic way to derive such a hand-rank table? We show that
there is indeed, and it involves finding the exact optimal conditional expected
return, given the initial hand. In the case of Jacks or Better (paying 800, 50,
25, 9, 6, 4, 3, 2, 1, 0), this is a random variable with 1,153 distinct values,
of which 766 correspond to garbage hands for which it is optimal to draw five
new cards. We describe the hands corresponding to each of the remaining 387
values of the optimal conditional expected return (sorted from largest to
smallest) and show how this leads readily to an optimal strategy hand-rank
table for Jacks or Better. Of course, the method applies to other video poker
games as well.


title:
The heat kernel of a Schr\"odinger operator with inverse square
  potential

abstract:
  We consider the Schr{\"o}dinger operator H = --$\Delta$ + V (|x|) with radial
potential V which may have singularity at 0 and a quadratic decay at infinity.
First, we study the structure of positive harmonic functions of H and give
their precise behavior. Second, under quite general conditions we prove an
upper bound for the correspond heat kernel p(x, y, t) of the type 0 \textless{}
p(x, y, t) $\le$ C t -- N 2 U (min{|x|, $\sqrt$ t})U (min{|y|, $\sqrt$ t}) U
($\sqrt$ t) 2 exp -- |x -- y| 2 Ct for all x, y $\in$ R N and t \textgreater{}
0, where U is a positive harmonic function of H. Third, if U 2 is an A 2 weight
on R N , then we prove a lower bound of a similar type.


title: Limited operators and differentiability

abstract:
  We characterize the limited operators by differentiability of convex
continuous functions. Given Banach spaces $Y$ and $X$ and a linear continuous
operator $T: Y \longrightarrow X$, we prove that $T$ is a limited operator if
and only if, for every convex continuous function $f: X \longrightarrow \R$ and
every point $y\in Y$, $f\circ T$ is Fr\'echet differentiable at $y\in Y$
whenever $f$ is G\^ateaux differentiable at $T(y)\in X$.


title: Rings satisfying *-property

abstract:
  In this paper we will investigate commutative rings which have the $\ast
$-property. We say that a ring $R$ satisfy $\ast-$property if for any family of
ideals $\left\{ I_{\alpha}\right\} _{\alpha\in S}$ of $R$ in which $S$ is an
index set, there exists a finite subset\ $S^{\prime}$ of $S$ such that the
radical of the intersection of the family of ideals $\left\{ I_{\alpha}\right\}
_{\alpha\in S}$ is equal to the intersection of the radicals of ideals $\left\{
I_{\alpha}\right\} _{\alpha\in S^{\prime}}$ . We will show that any integral
domain which satisfy $\ast-$property is a field. Furthermore, these rings are
zero-dimensional. After this we give relations between these rings and Artinian
rings.


title: Quantum thermal transistor

abstract:
  We demonstrate that a thermal transistor can be made up with a quantum system
of 3 interacting subsystems , coupled to a thermal reservoir each. This thermal
transistor is analogous to an electronic bipolar one with the ability to
control the thermal currents at the collector and at the emitter with the
imposed thermal current at the base. This is achieved determining the heat
fluxes by means of the strong-coupling formalism. For the case of 3 interacting
spins, in which one of them is coupled to the other 2, that are not directly
coupled, it is shown that high amplification can be obtained in a wide range of
energy parameters and temperatures. The proposed quantum transistor could, in
principle, be used to develop devices such as a thermal modulator and a thermal
amplifier in nano systems.


title:
Velocity Autocorrelation Function of Magnetized Two-Dimensional
  One-Component Plasma

abstract:
  The velocity autocorrelation function (VAF) for a two-dimensional
one-component plasma (OCP) is investigated by employing molecular dynamics
techniques. The VAF exhibits well defined oscillations whose frequency is
independent of the dimensionless coupling parameter Gamma. However, the
presence of a uniform perpendicular external magnetic field increases the
height of the first peak. Molecular dynamics computer simulation results are
presented for a two-dimensional OCP in a perpendicular magnetic field as a
function of the Plasma parameter. Our simulation results clearly indicate that
at high temperature, the magnetic field affects the VAF in a substantial way.


title: Wasserstein contraction properties for hypoelliptic diffusions

abstract:
  Gradient bounds had proved to be a very efficient tool for the control of the
rate of convergence to equilibrium for parabolic evolution equations. Among the
gradient bounds methods, the celebrated Bakry-\'Emery criterion is a powerful
way prove to convergence to equilibrium with an exponential rate. To be
satisfied, this criterion requires some form of ellipticity of the diffusion
operator. In the past few years, there have been several works extending the
Bakry-\'Emery methodology to hypoelliptic operators. Inspired by these methods,
we describe a rather simple generalization of the criterion that applies to a
large class of hypoelliptic/hypocoercive operators. We are particularly
interested in convergence to equilibrium in the Wasserstein distance and obtain
several new results in that direction.


title: Metric projections versus non-positive curvature

abstract:
  In this paper two metric properties on geodesic length spaces are introduced
by means of the metric projection, studying their validity on Alexandrov and
Busemann NPC spaces. In particular, we prove that both properties characterize
the non-positivity of the sectional curvature on Riemannian manifolds. Further
results are also established on reversible/non-reversible Finsler-Minkowski
spaces.


title: Phemenological Modeling of Eclipsing Binary Stars

abstract:
  We review the method NAV (New Algol Variable) first introduced in
2012Ap.....55..536A, which uses the locally-dependent shapes of eclipses in an
addition to the trigonometric polynomial of the second order (which typically
describes the "out-of-eclipse" part of the light curve with effects of
reflection, ellipticity and O'Connell). Eclipsing binary stars are believed to
show distinct eclipses only if belonging to the EA type. With a decreasing
eclipse width, the statistically optimal value of the trigonometric polynomial
s (2003ASPC..292..391A) drastically increases from ~2 for elliptic (EL)
variables without eclipses, ~6-8 for EW and up to ~30-50 for some EA with
narrow eclipses. In this case of large number of parameters, the smoothing
curve becomes very noisy and apparent waves (the Gibbs phenomenon) may be seen.
The NAV set of the parameters may be used for classification in the GCVS, VSX
and similar catalogs. The maximal number of parameters is m=12, which
corresponds to s=5, if correcting both the period and the initial epoch. We
have applied the method to few stars, also in a case of multi-color photometry
(2015JASS...32..127A), when it is possible to use the phenomenological
parameters from the NAV fit to estimate physical parameters using statistical
dependencies. We conclude that the NAV approximation is better than the TP one
even for the case of EW-type stars with much wider eclipses. It may also be
used to determine timings (see 2005ASPC..335...37A for a review of methods) or
to determine parameters in the case of variable period, using a complete light
curve modeling the phase variations. The method is illustrated on 2MASS
J11080447-6143290 (EA-type), USNO-B1.0 1265-0306001 and USNO-B1.0 1266-0313413
(EW-type) and compared to various other methods from the literature.


title:
INTEGRAL upper limits on gamma-ray emission associated with the
  gravitational wave event GW150914

abstract:
  Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory
(INTEGRAL), we put upper limits on the gamma-ray and hard X-ray prompt emission
associated with the gravitational wave event GW150914, discovered by the
LIGO/Virgo collaboration. The omni-directional view of the INTEGRAL/SPI-ACS has
allowed us to constrain the fraction of energy emitted in the hard X-ray
electromagnetic component for the full high-probability sky region of LIGO
trigger. Our upper limits on the hard X-ray fluence at the time of the event
range from $F_{\gamma}=2 \times 10^{-8}$ erg cm$^{-2}$ to $F_{\gamma}=10^{-6}$
erg cm$^{-2}$ in the 75 keV - 2 MeV energy range for typical spectral models.
Our results constrain the ratio of the energy promptly released in gamma-rays
in the direction of the observer to the gravitational wave energy
E$_\gamma/$E$_\mathrm{GW}<10^{-6}$. We discuss the implication of gamma-ray
limits on the characteristics of the gravitational wave source, based on the
available predictions for prompt electromagnetic emission.


title: Spectral Alignment of Graphs

abstract:
  Graph alignment refers to the problem of finding a bijective mapping across
vertices of two graphs such that, if two nodes are connected in the first
graph, their images are connected in the second graph. This problem arises in
many fields such as computational biology, social sciences, and computer vision
and is often cast as a quadratic assignment problem (QAP). Most standard graph
alignment methods consider an optimization that maximizes the number of matches
between the two graphs, ignoring the effect of mismatches. We propose a
generalized graph alignment formulation that considers both matches and
mismatches in a standard QAP formulation. This modification can have a major
impact in aligning graphs with different sizes and heterogenous edge densities.
Moreover, we propose two methods for solving the generalized graph alignment
problem based on spectral decomposition of matrices. We compare the performance
of proposed methods with some existing graph alignment algorithms including
Natalie2, GHOST, IsoRank, NetAlign, Klau's approach as well as a semidefinite
programming-based method over various synthetic and real graph models. Our
proposed method based on simultaneous alignment of multiple eigenvectors leads
to consistently good performance in different graph models. In particular, in
the alignment of regular graph structures which is one of the most difficult
graph alignment cases, our proposed method significantly outperforms other
methods.


title: Feynman Diagrams for Beginners

abstract:
  We give a short introduction to Feynman diagrams, with many exercises. Text
is targeted at students who had little or no prior exposure to quantum field
theory. We present condensed description of single-particle Dirac equation,
free quantum fields and construction of Feynman amplitude using Feynman
diagrams. As an example, we give a detailed calculation of cross-section for
annihilation of electron and positron into a muon pair. We also show how such
calculations are done with the aid of computer.


title:
Dark Memory and Accelerator-Rich System Optimization in the Dark Silicon
  Era

abstract:
  The key challenge to improving performance in the age of Dark Silicon is how
to leverage transistors when they cannot all be used at the same time. In
modern SOCs, these transistors are often used to create specialized
accelerators which improve energy efficiency for some applications by 10-1000X.
While this might seem like the magic bullet we need, for most CPU applications
more energy is dissipated in the memory system than in the processor: these
large gains in efficiency are only possible if the DRAM and memory hierarchy
are mostly idle. We refer to this desirable state as Dark Memory, and it only
occurs for applications with an extreme form of locality.
  To show our findings, we introduce Pareto curves in the energy/op and
mm$^2$/(ops/s) metric space for compute units, accelerators, and on-chip
memory/interconnect. These Pareto curves allow us to solve the power,
performance, area constrained optimization problem to determine which
accelerators should be used, and how to set their design parameters to optimize
the system. This analysis shows that memory accesses create a floor to the
achievable energy-per-op. Thus high performance requires Dark Memory, which in
turn requires co-design of the algorithm for parallelism and locality, with the
hardware.


title:
Parametric Bounded L\"ob's Theorem and Robust Cooperation of Bounded
  Agents

abstract:
  L\"ob's theorem and G\"odel's theorems make predictions about the behavior of
systems capable of self-reference with unbounded computational resources with
which to write and evaluate proofs. However, in the real world, systems capable
of self-reference will have limited memory and processing speed, so in this
paper we introduce an effective version of L\"ob's theorem which is applicable
given such bounded resources. These results have powerful implications for the
game theory of bounded agents who are able to write proofs about themselves and
one another, including the capacity to out-perform classical Nash equilibria
and correlated equilibria, attaining mutually cooperative program equilibrium
in the Prisoner's Dilemma. Previous cooperative program equilibria studied by
Tennenholtz (2004) and Fortnow (2009) have depended on tests for program
equality, a fragile condition, whereas "L\"obian" cooperation is much more
robust and agnostic of the opponent's implementation.


title:
Suppressing diborane production during the hydrogen release of metal
  borohydrides: The example of alloyed Al(BH$_4$)$_3$

abstract:
  Aluminum borohydride (Al(BH$_4$)$_3$) is an example of a promising hydrogen
storage material with exceptional hydrogen densities by weight and volume and a
low hydrogen desorption temperature. But, unfortunately, its production of
diborane (B$_2$H$_6$) gases upon heating to release the hydrogen restricts its
practical use. To elucidate this issue, we investigate the properties of a
number of metal borohydrides with the same problem and find that the
electronegativity of the metal cation is not the best descriptor of diborane
production. We show that, instead, the closely related formation enthalpy is a
better descriptor and we find that diborane production is an exponential
function thereof. We conclude that diborane production is sufficiently
suppressed for formation enthalpies of $-$80 kJ/mol BH$_4$ or lower, providing
specific design guidelines to tune existing metal borohydrides or synthesize
new ones. We then use first-principles methods to study the effects of Sc
alloying in Al(BH$_4$)$_3$. Our results for the thermodynamic properties of the
Al$_{1-x}$Sc$_x$(BH$_4$)$_3$ alloy clearly show the stabilizing effect of Sc
alloying and thus the suppression of diborane production. We conclude that
stabilizing Al(BH$_4$)$_3$ and similar borohydrides via alloying or other means
is a promising route to suppress diborane production and thus develop viable
hydrogen storage materials.


title:
An Evolutionary Strategy based on Partial Imitation for Solving
  Optimization Problems

abstract:
  In this work we introduce an evolutionary strategy to solve combinatorial
optimization tasks, i.e. problems characterized by a discrete search space. In
particular, we focus on the Traveling Salesman Problem (TSP), i.e. a famous
problem whose search space grows exponentially, increasing the number of
cities, up to becoming NP-hard. The solutions of the TSP can be codified by
arrays of cities, and can be evaluated by fitness, computed according to a cost
function (e.g. the length of a path). Our method is based on the evolution of
an agent population by means of an imitative mechanism, we define `partial
imitation'. In particular, agents receive a random solution and then,
interacting among themselves, may imitate the solutions of agents with a higher
fitness. Since the imitation mechanism is only partial, agents copy only one
entry (randomly chosen) of another array (i.e. solution). In doing so, the
population converges towards a shared solution, behaving like a spin system
undergoing a cooling process, i.e. driven towards an ordered phase. We
highlight that the adopted `partial imitation' mechanism allows the population
to generate solutions over time, before reaching the final equilibrium. Results
of numerical simulations show that our method is able to find, in a finite
time, both optimal and suboptimal solutions, depending on the size of the
considered search space.


title: Evolution of the jet opening angle distribution in holographic plasma

abstract:
  We use holography to analyze the evolution of an ensemble of jets, with an
initial probability distribution for their energy and opening angle as in
proton-proton (pp) collisions, as they propagate through an expanding cooling
droplet of strongly coupled plasma as in heavy ion collisions. We identify two
competing effects: (i) each individual jet widens as it propagates; (ii) the
opening angle distribution for jets emerging from the plasma within any
specified range of energies has been pushed toward smaller angles, comparing to
pp jets with the same energies. The second effect arises because small-angle
jets suffer less energy loss and because jets with a higher initial energy are
less probable in the ensemble. We illustrate both effects in a simple
two-parameter model, and find that their consequence in sum is that the opening
angle distribution for jets in any range of energies contains fewer narrow and
wide jets. Either effect can dominate in the mean opening angle, for not
unreasonable values of the parameters. So, the mean opening angle for jets with
a given energy can easily shift toward smaller angles, as experimental data may
indicate, even while every jet in the ensemble broadens.


title: On constraining the speed of gravitational waves following GW150914

abstract:
  We point out that the observed time delay between the detection of the signal
at the Hanford and Livingston LIGO sites from the gravitational wave event
GW150914 places an upper bound on the speed of propagation of gravitational
waves, $c_{gw}\lesssim 1.7$ in the units of speed of light. Combined with the
lower bound from the absence of gravitational Cherenkov losses by cosmic rays
that rules out most of subluminal velocities, this gives a model-independent
double-sided constraint $1\lesssim c_{gw}\lesssim 1.7$. We compare this result
to model-specific constraints from pulsar timing and cosmology.


title:
Heat flux in the presence of a gravitational field in a simple dilute
  fluid: an approach based in general relativistic kinetic theory to first
  order in the gradients

abstract:
  Richard C. Tolman analyzed the relation between a temperature gradient and a
gravitational field in an equilibrium situation. In 2012, Tolman\textquoteright
s law was generalized to a non-equilibrium situation for a simple dilute
relativistic fluid. The result in that scenario, obtained by introducing the
gravitational force through the molecular acceleration, couples the heat flux
with the metric coefficients and the gradients of the state variables. In the
present paper it is shown, by \textquotedblleft suppressing\textquotedblright{}
the molecular acceleration in Boltzmann\textquoteright s equation, that a
gravitational field drives a heat flux. This procedure corresponds to the
description of particle motion through geodesics, in which a Newtonian limit to
the Schwarzschild metric is assumed. The effect vanishes in the
non-relativistic regime, as evidenced by the direct evaluation of the
corresponding limit.


title: Renormalised conical zeta values

abstract:
  Conical zeta values associated with rational convex polyhedral cones
generalise multiple zeta values. We renormalise conical zeta values at poles by
means of a generalisation of Connes and Kreimer's Algebraic Birkhoff
Factorisation. This paper serves as a motivation for and an application of this
generalised renormalisation scheme. The latter also yields an Euler-Maclaurin
formula on rational convex polyhedral lattice cones which relates exponential
sums to exponential integrals. When restricted to Chen cones, it reduces to
Connes and Kreimer's Algebraic Birkhoff Decomposition for maps with values in
the algebra of ordinary meromorphic functions in one variable.


title:
Smart-aggregation imaging for single molecule localization with SPAD
  cameras

abstract:
  SPAD cameras offer single photon detection sensitivity, high frame rates and
zero readout noise. They are a core technology for widefield FLIM, but have
further potential in ultra-fast imaging applications. However, in practice
sensitivity falls behind that of EMCCD and sCMOS devices due to the lower
photon detection efficiency of SPAD arrays. This paper considers the
application of a binary SPAD camera to the capture of blinking molecules as
part of a superresolution (dSTORM/PALM) experiment. Simulation and experimental
studies demonstrate that the effective sensitivity of the camera can be
improved significantly by aggregation of signal only binary frames. The
simulations also indicate that with future advances in SPAD camera technology,
SPAD devices could in time outperform existing scientific cameras when
capturing fast temporal dynamics.


title:
Factorization theorem, gluon poles and new contributions in
  semi-inclusive processes

abstract:
  We discuss the role of gluon poles and the gauge invariance for the hadron
tensors of Drell-Yan and direct photon production processes with the
transversely polarized hadron.


title: Distributed Average Consensus with Bounded Quantizer and Unbounded Input

abstract:
  This paper considers distributed average consensus using finite-bit bounded
quantizer with possibly unbounded data. Under the framework of the alternating
direction method of multipliers (ADMM), we develop distributed averaging
algorithms where each node iteratively updates using only the local information
and finitely quantized outputs from its neighbors. It is shown that all the
agent variables either converge to the same quantization level or cycle around
the data average after finite iterations. An error bound for the consensus
value is established, which turns out to be the same as that of using the
unbounded rounding quantizer provided that an algorithm parameter (i.e., ADMM
step size) is small enough. We also analyze the effect of the algorithm
parameter and propose an adaptive parameter selection strategy that only
requires knowledge of the number of agents in order to accelerate the algorithm
with certain consensus accuracy guarantee. Finally, simulations are performed
to illustrate the effectiveness of the proposed algorithms.


title: Experimental Demonstration of Self-Guided Quantum Tomography

abstract:
  Robust, accurate and efficient quantum tomography is key for future quantum
technologies. Traditional methods are impractical for even medium sized systems
and are not robust against noise and errors. Here we report on an experimental
demonstration of self-guided quantum tomography; an autonomous, fast, robust
and precise technique for measuring quantum states with significantly less
computational resources than standard techniques. The quantum state is
iteratively learned by treating tomography as a projection measurement
optimization problem. We experimentally demonstrate robustness against both
statistical noise and experimental errors on both single qubit and entangled
two-qubit states. Our demonstration provides a method of full quantum state
characterization in current and near-future experiments where standard
techniques are unfeasible.


title: Density matrix embedding theory for interacting electron-phonon systems

abstract:
  We describe the extension of the density matrix embedding theory (DMET)
framework to coupled interacting fermion-boson systems. This provides a
frequency-independent, entanglement embedding formalism to treat bulk
fermion-boson problems. We illustrate the concepts within the context of the
one-dimensional Hubbard-Holstein model, where the phonon bath states are
obtained from the Schmidt decomposition of a self-consistently adjusted
coherent state. We benchmark our results against accurate density matrix
renormalization group calculations.


title:
Linking the dielectric Debye process in 2-ethyl-1-hexanol to its density
  fluctuations

abstract:
  We provide the first evidence that the puzzling dielectric Debye process
observed in mono-alcohols is coupled to density fluctuations. The results open
up for an explanation of the Debye process within the framework of conventional
liquid-state theory. The spectral shape of dynamical bulk modulus of
2-ethyl-1-hexanol is nearly identical to that of the shear modulus, and thus
the supramolecular structures believed to be responsible for the slow
dielectric Debye process are manifested in the bulk modulus in the same way as
in the shear modulus.


title: Effective potentials in a bidimensional vibrated granular gas

abstract:
  We present a numerical study of the spatial correlations of a
quasi-two-dimensional granular fluid kept in a non-static steady state via
vertical shaking. The simulations explore a wide range of packing fractions,
vertical accelerations and restitution coefficients, always staying below the
crystallization limit. From the simulations we obtain the relevant Pair
Distribution Functions (PDFs), and effective potentials for the interparticle
interaction are extracted from these PDFs via the Ornstein-Zernike equation
with the Percus-Yevick closure. The correlations in the granular structures
originating from these effective potentials are checked against the originating
PDF using standard Monte Carlo simulations, and we find in general an excellent
agreement. The resulting effective potentials show an increase of the spatial
correlation at contact with the decreasing values of the restitution
coefficient, and a general tendency of the potentials to display deeper wells
for more dissipative dynamics. An exception to this general trend appears for
certain combinations of density and forcing, where resonant bouncing increases
correlations.


title:
A Dark Energy Camera Search for an Optical Counterpart to the First
  Advanced LIGO Gravitational Wave Event GW150914

abstract:
  We report initial results of a deep search for an optical counterpart to the
gravitational wave event GW150914, the first trigger from the Advanced LIGO
gravitational wave detectors. We used the Dark Energy Camera (DECam) to image a
102 deg$^2$ area, corresponding to 38% of the initial trigger high-probability
sky region and to 11% of the revised high-probability region. We observed in i
and z bands at 4-5, 7, and 24 days after the trigger. The median $5\sigma$
point-source limiting magnitudes of our search images are i=22.5 and z=21.8
mag. We processed the images through a difference-imaging pipeline using
templates from pre-existing Dark Energy Survey data and publicly available
DECam data. Due to missing template observations and other losses, our
effective search area subtends 40 deg$^{2}$, corresponding to 12% total
probability in the initial map and 3% of the final map. In this area, we search
for objects that decline significantly between days 4-5 and day 7, and are
undetectable by day 24, finding none to typical magnitude limits of i=
21.5,21.1,20.1 for object colors (i-z)=1,0,-1, respectively. Our search
demonstrates the feasibility of a dedicated search program with DECam and bodes
well for future research in this emerging field.


title:
A Dark Energy Camera Search for Missing Supergiants in the LMC After the
  Advanced LIGO Gravitational Wave Event GW150914

abstract:
  The collapse of the core of a star is expected to produce gravitational
radiation. While this process will usually produce a luminous supernova, the
optical signatue could be subluminous and a direct collapse to a black hole,
with the star just disappearing, is possible. The gravitational wave event
GW150914 reported by the LIGO Virgo Collaboration (LVC) on 2015 September 16,
was detected by a burst analysis and whose high probability spatial
localization included the Large Magellanic Cloud. Shortly after the
announcement of the event, we used the Dark Energy Camera to observe 102
deg$^2$ of the localization area, including a 38 deg$^2$ area centered on the
LMC. Using a catalog of 152 LMC luminous red supergiants, candidates to undergo
a core collapse without a visible supernova, we find that the positions of 144
of these are inside our images, and that all are detected - none have
disappeared. There are other classes of candidates: we searched existing
catalogs of red supergiants, yellow supergiants, Wolf-Rayet stars, and luminous
blue variable stars, recovering all that were inside the imaging area. Based on
our observations, we conclude that it is unlikely that GW150914 was caused by
the core collapse of a supergiant in the LMC, consistent with the LIGO
Collaboration analyses of the gravitational wave form as best described by a
binary black hole merger. We discuss how to generalize this search for future
very nearby core collapse candidates.


title:
Multi-band optical variability of three TeV Blazars on Diverse
  Timescales

abstract:
  We present our optical photometric observations of three TeV blazars, PKS
1510-089, PG 1553+113 and Mrk 501 taken using two telescopes in India, one in
Bulgaria, one in Greece and one in Serbia during 2012 - 2014. These
observations covered a total of 95 nights with a total of 202 B filter frames,
247 images in V band, 817 in R band while 229 images were taken in the I
filter. This work is focused on multi-band flux and colour variability studies
of these blazars on diverse timescales which are useful in understanding the
emission mechanisms. We studied the variability characteristics of above three
blazars and found all to be active over our entire observational campaigns. We
also searched for any correlation between the brightness of the sources and
their colour indices. During the times of variability, no significant evidence
for the sources to display spectral changes correlated with magnitude was found
on timescales of a few months. We briefly discuss the possible physical
mechanisms most likely responsible for the observed flux variability.


title:
Universal fidelity near quantum and topological phase transitions in
  finite 1D systems

abstract:
  We study the quantum fidelity (groundstate overlap) near quantum phase
transitions of the Ising universality class in one dimensional (1D) systems of
finite size L. Prominent examples occur in magnetic systems (e.g. spin-Peierls,
the anisotropic XY model), and in 1D topological insulators of any
topologically nontrivial Altland-Zirnbauer-Kitaev universality class. The
rescaled fidelity susceptibility is a function of the only dimensionless
parameter LM, where 2M is the gap in the fermionic spectrum. We present
analytic expressions for the fidelity susceptibility for periodic and open
boundaries conditions with zero, one or two edgestates. The latter are shown to
have a crucial impact and alter the susceptibility both quantitatively and
qualitatively. We support our analytical solutions with numerical data.


title: Third Order Fermionic and Fourth Order Bosonic Operators

abstract:
  This paper continues the work of our previous paper [8], where we generalize
kth-powers of the Euclidean Dirac operator D_x to higher spin spaces in the
case the target space is a degree one homogeneous polynomial space. In this
paper, we reconsider the generalizations of D_x^3 and D_x^4 to higher spin
spaces in the case the target space is a degree k homogeneous polynomial space.
Constructions of 3rd and 4th order conformally invariant operators in higher
spin spaces are given; these are the 3rd order fermionic and 4th order bosonic
operators. Fundamental solutions and intertwining operators of both operators
are also presented here. These results can be easily generalized to cylinders
and Hopf manifolds as in [7].


title: Probing the Scale of New Physics by Advanced LIGO/VIRGO

abstract:
  We show that if the new physics beyond the Standard Model is associated with
a first-order phase transition around $10^7-10^8$ GeV, the energy density
stored in the resulting stochastic gravitational waves and the corresponding
peak frequency are within the projected final sensitivity of the advanced
LIGO/VIRGO detectors. We discuss some possible new physics scenarios that could
arise at such energies, and in particular, the consequences for Peccei-Quinn
and supersymmetry breaking scales.


title: Implications of the 750 GeV Diphoton Excess in Gaugino Mediation

abstract:
  The 750 GeV diphoton excess reported by ATLAS and CMS indicates the presence
of several pairs of the vector-like matter multiplets around TeV scale. If that
is the case, radiative corrections from the $SU(3)$ gauge interaction
significantly change from those of MSSM, and the infrared-free nature of the
gauge interaction leads to characteristic SUSY mass spectra: a ratio of a
squark mass to the gluino mass, and scalar trilinear couplings are enhanced at
the low-energy scale. Consequently, even in gaugino mediation models, the Higgs
boson mass of 125 GeV is explained with the fairly light gluino of 2-3 TeV,
which can be accessible at the LHC.


title:
Do ultrafast exciton-polaron decoherence dynamics govern photocarrier
  generation efficiencies in polymer solar cells?

abstract:
  All-organic-based photovoltaic solar cells have attracted considerable
attention because of their low-cost processing and short energy payback time.
In such systems the primary dissociation of an optical excitation into a pair
of photocarriers has been recently shown to be extremely rapid and efficient,
but the physical reason for this remains unclear. Here, two-dimensional
photocurrent excitation spectroscopy, a novel non-linear optical spectroscopy,
is used to probe the ultrafast coherent decay of photoexcitations into
charge-producing states in a polymer:fullerene based solar cell. The
two-dimensional photocurrent spectra are interpreted by introducing a
theoretical model for the description of the coupling of the electronic states
of the system to an external environment and to the applied laser fields. The
experimental data show no cross-peaks in the two-dimensional photocurrent
spectra, as predicted by the model for coherence times between the exciton and
the photocurrent producing states of 20\,fs or less.


title: Flavor and CP symmetries for leptogenesis and 0nubb decay

abstract:
  We perform a comprehensive analysis of the phenomenology of leptonic low and
high energy CP phases in a scenario with three heavy right-handed neutrinos in
which a flavor and a CP symmetry are non-trivially broken. All CP phases as
well as lepton mixing angles are determined by the properties of the flavor and
CP symmetry and one free real parameter. We focus on the generation of the
baryon asymmetry Y_B of the Universe via unflavored leptogenesis and the
predictions of m_ee, the quantity measurable in neutrinoless double beta decay.
We show that the sign of Y_B can be fixed and the allowed parameter range of
m_ee can be strongly constrained. We argue on general grounds that the CP
asymmetries epsilon_i are dominated by the contribution associated with one
Majorana phase and that in cases in which only the Dirac phase is non-trivial
the sign of Y_B depends on further parameters. In addition, we comment on the
case of flavored leptogenesis where in general the knowledge of the CP phases
and light neutrino mass spectrum is also not sufficient in order to fix the
sign of the CP asymmetries. As examples we discuss the series of flavor groups
Delta (3 n^2) and Delta (6 n^2), n >= 2 integer, and several classes of CP
transformations.


title: Fundamental Limits of Cache-Aided Interference Management

abstract:
  We consider a system comprising a library of $N$ files (e.g., movies) and a
wireless network with $K_T$ transmitters, each equipped with a local cache of
size of $M_T$ files, and $K_R$ receivers, each equipped with a local cache of
size of $M_R$ files. Each receiver will ask for one of the $N$ files in the
library, which needs to be delivered. The objective is to design the cache
placement (without prior knowledge of receivers' future requests) and the
communication scheme to maximize the throughput of the delivery. In this
setting, we show that the sum degrees-of-freedom (sum-DoF) of
$\min\left\{\frac{K_T M_T+K_R M_R}{N},K_R\right\}$ is achievable, and this is
within a factor of 2 of the optimum, under one-shot linear schemes. This result
shows that (i) the one-shot sum-DoF scales linearly with the aggregate cache
size in the network (i.e., the cumulative memory available at all nodes), (ii)
the transmitters' and receivers' caches contribute equally in the one-shot
sum-DoF, and (iii) caching can offer a throughput gain that scales linearly
with the size of the network.
  To prove the result, we propose an achievable scheme that exploits the
redundancy of the content at transmitters' caches to cooperatively zero-force
some outgoing interference and availability of the unintended content at
receivers' caches to cancel (subtract) some of the incoming interference. We
develop a particular pattern for cache placement that maximizes the overall
gains of cache-aided transmit and receive interference cancellations. For the
converse, we present an integer optimization problem which minimizes the number
of communication blocks needed to deliver any set of requested files to the
receivers. We then provide a lower bound on the value of this optimization
problem, hence leading to an upper bound on the linear one-shot sum-DoF of the
network, which is within a factor of 2 of the achievable sum-DoF.


title: Pursuits in Structured Non-Convex Matrix Factorizations

abstract:
  Efficiently representing real world data in a succinct and parsimonious
manner is of central importance in many fields. We present a generalized greedy
pursuit framework, allowing us to efficiently solve structured matrix
factorization problems, where the factors are allowed to be from arbitrary sets
of structured vectors. Such structure may include sparsity, non-negativeness,
order, or a combination thereof. The algorithm approximates a given matrix by a
linear combination of few rank-1 matrices, each factorized into an outer
product of two vector atoms of the desired structure. For the non-convex
subproblems of obtaining good rank-1 structured matrix atoms, we employ and
analyze a general atomic power method. In addition to the above applications,
we prove linear convergence for generalized pursuit variants in Hilbert spaces
- for the task of approximation over the linear span of arbitrary dictionaries
- which generalizes OMP and is useful beyond matrix problems. Our experiments
on real datasets confirm both the efficiency and also the broad applicability
of our framework in practice.


title:
Submesoscale circulation in the Northern Gulf of Mexico: Deep phenomena
  and dispersion over the continental slope

abstract:
  This study examines the mesoscale and submesoscale circulations along the
continental slope in the northern Gulf of Mexico at depths greater than 1000 m.
The investigation is performed using a regional model run at two horizontal
grid resolutions, 5 km and 1.6 km, over a three year period from January 2010
to December 2012. Ageostrophic submesoscale eddies, and vorticity filaments
populate the continental slope, and they are stronger and more abundant in the
simulation at higher resolution, as to be expected. They are formed from
horizontal shear layers at the edges of highly intermittent,
bottom-intensified, along-slope boundary currents and in the cores of those
currents when they are confined on steep slopes. The horizontal resolution
influences the representation of the lateral and vertical transport of
neutrally buoyant tracers. This is exemplified by a passive dye deployed near
the Macondo Prospect, where the Deepwater Horizon rig exploded in 2010, and at
the largest known natural hydrocarbon seep in the northern Gulf, few hundred
kilometers to the west of the rig wellhead. The first site is characterized by
weak mean currents and, in the high resolution run, by intense submesoscale
eddies that form to the west of the Macondo Prospect. GC600, on the other hand,
is surrounded by a complicated bathymetry, and its flow is highly variable. The
trapping exerted by the submesoscale eddies and vorticity filaments near the
rig constrain the spreading in the vicinity of the Macondo Prospect, and as a
result, patchiness in the passive tracer distributions differs in the two
integrations, despite similar diffusivities expressing the average spreading
rate. The tracer released at GC600, on the other hand, is dispersed more
effectively in the first six months in the higher resolution case due to
enhanced near-bottom turbulent mixing.


title:
Adaptive Multi-polling Scheduler for QoS Support of Video Transmission
  in IEEE 802.11e WLANs

abstract:
  The 802.11E Task Group has been established to enhance Quality of Service
(QoS) provision for time-bounded services in the current IEEE 802.11 Medium
Access Control (MAC) protocol. The QoS is introduced throughout Hybrid
Coordination Function Controlled Channel Access (HCCA) for the rigorous QoS
provision. In HCCA, the station is allocated a fixed Transmission Opportunity
(TXOP) based on its TSPEC parameters so that it is efficient for Constant Bit
Rate streams. However, as the profile of Variable Bit Rate (VBR) traffics is
inconstant, they are liable to experience a higher delay especially in bursty
traffic case. In this paper, we present a dynamic TXOP assignment algorithm
called Adaptive Multi-polling TXOP scheduling algorithm (AMTXOP) for supporting
the video traffics transmission over IEEE 802.11e wireless networks. This
scheme invests a piggybacked information about the size of the subsequent video
frames of the uplink streams to assist the Hybrid Coordinator accurately assign
the TXOP according to actual change in the traffic profile. The proposed
scheduler is powered by integrating multi-polling scheme to further reduce the
delay and polling overhead. Extensive simulation experiments have been carried
out to show the efficiency of the AMTXOP over the existing schemes in terms of
the packet delay and the channel utilization.


title: Consistent and fault-tolerant SDN with unmodified switches

abstract:
  In a reliable SDN environment, different controllers coordinate different
switches and backup controllers can be set in place to tolerate faults. This
approach increases the challenge to maintain a consistent network view. If this
global view is not consistent with the actual network state, applications will
operate on a stale state and potentially lead to incorrect behavior.
  Faced with this problem, we propose a fault-tolerant SDN controller that is
able to maintain a consistent network view by using transactional semantics on
both control and data plane state. Different from previous proposals, our
solution does not require changes to OpenFlow or to switches, increasing the
chances of quicker adoption.


title: The M\"ossbauer rotor experiment and the general theory of relativity

abstract:
  This paper is a rebuttal to Eur. Phys. Jour. Plus 130, 191 (2015), which
claims that the results in arXiv:1502.04911 (Ann. Phys. 355, 360 (2015)) are
incorrect. For this reason, some of the results in arXiv:1502.04911 have been
reviewed and clarified. The results in this paper are dedicated to the 100th
anniversary of Albert Einstein's presentation of the complete General Theory of
Relativity to the Prussian Academy.


title: Determinantal invariant gravity

abstract:
  Einstein-Hilbert action with a determinantal invariant has been considered.
The obtained field equation contains the \texttt{inverse Ricci tensor},
$\Re_{\alpha\beta}$. The linearized solution of invariant has been examined,
and constant curvature space-time metric solution of the field equation gives
different curvature constant for each values of $\sigma$. $\sigma=0$ gives a
trivial solution for constant curvature, $R_{0}$.


title: Controlling multistability by discontinuous dissipative coupling

abstract:
  In this paper we present an influence of discontinuous coupling on the
dynamics of multistable systems. Our model consists of two periodically forced
oscillators that can interact via soft impacts. The controlling parameters are
the distance between the oscillators and the difference in the phase of the
harmonic excitation. When the distance is large two systems do not collide and
a number of different possible solutions can be observed in both of them. When
decreasing of the distance, one can observe some transient impacts and then the
systems settle down on non-impacting attractor. It is shown that with the
properly chosen distance and difference in the phase of the harmonic
excitation, the number of possible solutions of the coupled systems can be
reduced. The proposed method is robust and applicable in many different
systems.


title:
Source of the Kerr-Newman Solution as a Supersymmetric Domain-Wall
  Bubble: 50 years of the problem

abstract:
  We consider the chiral field model of the source of the Kerr-Newman (KN)
solution and obtain that it represents a supersymmetric spinning soliton,
bounded by the chiral domain wall (DW) of the ellipsoidal form. The known
method for transformation of the planar DW to Bogomolnyi form we generalize to
the curved DW-bubble adapted to the Kerr coordinate system and obtain the
supersymmetric BPS-saturated source of the KN solution, having some remarkable
features, in particular, the quantum angular momentum. The main new result is
that the source forms a breather, i.e. the DW-antiDW combination. Taking into
account that the KN solution describes the spinning particles with gyromagnetic
ratio g = 2, as that of the Dirac electron, we touch the problem of the
compatibility of the spinning particles with gravity.


title:
RadioNet3 Study Group White Paper on: The Future Organisation and
  Coordination of Radio Astronomy in Europe

abstract:
  The QueSERA Study Group (QSG) have been tasked by the RadioNet Board to
produce a White Paper on the future organisation and coordination of radio
astronomy in Europe. This White Paper describes the options discussed by the
QSG, and our conclusions on how to move forward. We propose, that as a first
step, RadioNet-work, be established as an entity that persists between EC
contracts, and that takes responsibility for preparing or coordinating
responses to EC opportunities specific to the field of radio astronomy research
infrastructures. RadioNet-work should provide a safety net that ensures that
cooperation and collaboration between the various radio astronomy partners in
Europe is maintained with or without EC funding.


title: Complex Symmetric Composition Operators on $H^2$

abstract:
  In this paper, we find complex symmetric composition operators on the
classical Hardy space whose symbols are linear-fractional but not automorphic.
In doing so, we answer a recent question of Noor, and partially answer the
original problem posed by Garcia and Hammond.


title:
Quasinormal and hyponormal weighted composition operators on $H^2$ and
  $A^2_{\alpha}$ with linear fractional compositional symbol

abstract:
  In this paper, we study quasinormal and hyponormal composition operators \W
with linear fractional compositional symbol $\ph$ on the Hardy and weighted
Bergman spaces. We characterize the quasinormal composition operators induced
on $H^{2}$ and $A_{\alpha}^{2}$ by these maps and many such weighted
composition operators, showing that they are necessarily normal in all known
cases. We eliminate several possibilities for hyponormal weighted composition
operators but also give new examples of hyponormal weighted composition
operators on $H^2$ which are not quasinormal.


title: Cannibal Dark Matter

abstract:
  A thermally decoupled hidden sector of particles, with a mass gap,
generically enters a phase of cannibalism in the early Universe. The Standard
Model sector becomes exponentially colder than the hidden sector. We propose
the Cannibal Dark Matter framework, where dark matter resides in a
cannibalizing sector with a relic density set by 2-to-2 annihilations.
Observable signals of Cannibal Dark Matter include a boosted rate for indirect
detection, new relativistic degrees of freedom, and warm dark matter.


title: Network Gravity

abstract:
  We introduce the construction of a new framework for probing discrete
emergent geometry and boundary-boundary observables based on a fundamentally
a-dimensional underlying network structure. Using a gravitationally motivated
action with Forman weighted combinatorial curvatures and simplicial volumes
relying on a decomposition of an abstract simplicial complex into realized
embeddings of proper skeletons, we demonstrate properties such as a minimal
volume-scale cutoff, the necessity of a positive-definite cosmological
constant-like term as a regulator for non-degenerate geometries, and naturally
emergent simplicial structures from Metropolis network evolution simulations
with no restrictions on attachment rules or regular building blocks. We see
emergent properties which echo results from both the spinfoam formalism and
causal dynamical triangulations in quantum gravity, and provide analytical and
numerical results to support the analogy. We conclude with a summary of open
questions and intent for future work in developing the program.