title:
Two-Bit Messages are Sufficient to Implement Atomic Read/Write Registers
  in Crash-prone Systems

abstract:
  Atomic registers are certainly the most basic objects of computing science.
Their implementation on top of an n-process asynchronous message-passing system
has received a lot of attention. It has been shown that t \textless{} n/2
(where t is the maximal number of processes that may crash) is a necessary and
sufficient requirement to build an atomic register on top of a crash-prone
asynchronous message-passing system. Considering such a context, this paper
presents an algorithm which implements a single-writer multi-reader atomic
register with four message types only, and where no message needs to carry
control information in addition to its type. Hence, two bits are sufficient to
capture all the control information carried by all the implementation messages.
Moreover, the messages of two types need to carry a data value while the
messages of the two other types carry no value at all. As far as we know, this
algorithm is the first with such an optimality property on the size of control
information carried by messages. It is also particularly efficient from a time
complexity point of view.


title: Troublesome aspects of the Renyi-MaxEnt treatment

abstract:
  We study in great detail the possible existence of a Renyi-associated
thermodynamics, with negative results. In particular, we uncover a hidden
relation in the Renyi's variational problem (MaxEnt). This relation connects
the two associated Lagrange multipliers (Canonical Ensemble) with the mean
energy $<U>$ and the Renyi parameter $\alpha$. As a consequence of such
relation, we obtain anomalous Renyi-MaxEnt thermodynamic results.


title: Practical Black-Box Attacks against Machine Learning

abstract:
  Machine learning (ML) models, e.g., deep neural networks (DNNs), are
vulnerable to adversarial examples: malicious inputs modified to yield
erroneous model outputs, while appearing unmodified to human observers.
Potential attacks include having malicious content like malware identified as
legitimate or controlling vehicle behavior. Yet, all existing adversarial
example attacks require knowledge of either the model internals or its training
data. We introduce the first practical demonstration of an attacker controlling
a remotely hosted DNN with no such knowledge. Indeed, the only capability of
our black-box adversary is to observe labels given by the DNN to chosen inputs.
Our attack strategy consists in training a local model to substitute for the
target DNN, using inputs synthetically generated by an adversary and labeled by
the target DNN. We use the local substitute to craft adversarial examples, and
find that they are misclassified by the targeted DNN. To perform a real-world
and properly-blinded evaluation, we attack a DNN hosted by MetaMind, an online
deep learning API. We find that their DNN misclassifies 84.24% of the
adversarial examples crafted with our substitute. We demonstrate the general
applicability of our strategy to many ML techniques by conducting the same
attack against models hosted by Amazon and Google, using logistic regression
substitutes. They yield adversarial examples misclassified by Amazon and Google
at rates of 96.19% and 88.94%. We also find that this black-box attack strategy
is capable of evading defense strategies previously found to make adversarial
example crafting harder.


title: Defining Cross-Cloud Systems

abstract:
  Recent years have seen an increasing number of cross-cloud architectures,
i.e. systems that span across cloud provisioning boundaries. However, the cloud
computing world still lacks any standards in terms of programming interfaces,
which has a knock-on effect on the costs associated with interoperability and
severely limits the flexibility and portability of applications and virtual
infrastructures. This paper outlines the different types of cross-cloud
systems, and the associated design decisions.


title: A family of projectively natural polygon iterations

abstract:
  The pentagram map was invented by Richard Schwartz in his search for a
projective-geometric analogue of the midpoint map. It turns out that the
dynamical behavior of the pentagram map is totally different from that of the
midpoint map. Recently, Schwartz has constructed a related map, the projective
heat map, which empirically exhibits similar dynamics as the midpoint map. In
this paper, we will demonstrate that there is a one-parameter family of maps
which behaves a lot like Schwartz's projective heat map.


title: On dual pairs in Dirac Geometry

abstract:
  In this note we discuss dual pairs in Dirac geometry. We show that this
notion appears naturally when studying the problem of pushing forward a Dirac
structure along a surjective submersion, and we prove a Dirac-theoretic version
of Libermann's theorem from Poisson geometry. Our main result is an explicit
construction of strong self-dual pairs for Dirac structures. This theorem not
only recovers the global construction of symplectic realizations from
[Crainic-Marcut 2011], but allows for a more conceptual understanding of it,
yielding a simpler and more natural proof. As an application of the main
theorem, we present a different approach to the recent normal form theorem
around Dirac transversals from [Bursztyn-Lima-Meinrenken 2016].


title: Compressed Online Dictionary Learning for Fast fMRI Decomposition

abstract:
  We present a method for fast resting-state fMRI spatial decomposi-tions of
very large datasets, based on the reduction of the temporal dimension before
applying dictionary learning on concatenated individual records from groups of
subjects. Introducing a measure of correspondence between spatial
decompositions of rest fMRI, we demonstrates that time-reduced dictionary
learning produces result as reliable as non-reduced decompositions. We also
show that this reduction significantly improves computational scalability.


title:
Chemistry and Kinematics of Red Supergiant Stars in the Young Massive
  Cluster NGC 2100

abstract:
  We have obtained K-band Multi-Object Spectrograph (KMOS) near-IR spectroscopy
for 14 red supergiant stars (RSGs) in the young massive star cluster NGC 2100
in the Large Magellanic Cloud (LMC). Stellar parameters including metallicity
are estimated using the J-band analysis technique, which has been rigorously
tested in the Local Universe. We find an average metallicity for NGC 2100 of
[Z]=$-$0.43$\pm$0.10 dex, in good agreement with estimates from the literature
for the LMC. Comparing our results in NGC 2100 with those for a Galactic
cluster (at Solar-like metallicity) with a similar mass and age we find no
significant difference in the location of RSGs in the Hertzsprung--Russell
diagram. We combine the observed KMOS spectra to form a simulated
integrated-light cluster spectrum and show that, by analysing this spectrum as
a single RSG, the results are consistent with the average properties of the
cluster. Radial velocities are estimated for the targets and the dynamical
properties are estimated for the first time within this cluster. The data are
consistent with a flat velocity dispersion profile, and with an upper limit of
3.9 km/s, at the 95% confidence level, for the velocity dispersion of the
cluster. However, the intrinsic velocity dispersion is unresolved and could,
therefore, be significantly smaller than the upper limit reported here. An
upper limit on the dynamical mass of the cluster is derived as $M_{dyn}$ $\le$
$15.2\times10^{4}M_{\odot}$ assuming virial equilibrium.


title:
Extended formalism for simulating compound refractive lens-based x-ray
  microscopes

abstract:
  We present a comprehensive formalism for the simulation and optimisation of
CRLs in both condensing and full-field imaging configurations. The approach
extends ray transfer matrix analysis to account for x-ray attenuation by the
lens material. Closed analytical expressions for critical imaging parameters
such as numerical aperture, vignetting, chromatic aberration and focal length
are provided for both thin- and thick-lens imaging geometries.


title:
Integrated Interleaved Codes as Locally Recoverable Codes: Properties
  and Performance

abstract:
  Considerable interest has been paid in recent literature to codes combining
local and global properties for erasure correction. Applications are in cloud
type of implementations, in which fast recovery of a failed storage device is
important, but additional protection is required in order to avoid data loss,
and in RAID type of architectures, in which total device failures coexist with
silent failures at the page or sector level in each device. Existing solutions
to these problems require in general relatively large finite fields. The
techniques of Integrated Interleaved Codes (which are closely related to
Generalized Concatenated Codes) are proposed to reduce significantly the size
of the finite field, and it is shown that when the parameters of these codes
are judiciously chosen, their performance may be competitive with the one of
codes optimizing the minimum distance.


title: Sur le p-rang du groupe des classes de Q(N^1/p)

abstract:
  Let N and p be two prime numbers > 3 such that p divides N-1. We estimate the
p-rank of the class group of Q(N^(1/p)) in terms of the discrete logarithm,
with values un F_p, of certain units. Using the Gross--Koblitz formula and
identities on the N-adic Gamma function, we explicitly compute these
logarithms. A special case (for which we don't have an elementary proof) of our
formula is the following: assume there are some integers $a$, $b$ such that N =
(a^p+b^p)/(a+b). Then (a+b)*\prod_{k=1}^{(N-1)/2} k^{8k} is a p-th power modulo
N. Furthermore we give a new proof which doesn't use modular forms of a result
of Calegari and Emerton.


title: Decoy Bandits Dueling on a Poset

abstract:
  We adress the problem of dueling bandits defined on partially ordered sets,
or posets. In this setting, arms may not be comparable, and there may be
several (incomparable) optimal arms. We propose an algorithm, UnchainedBandits,
that efficiently finds the set of optimal arms of any poset even when pairs of
comparable arms cannot be distinguished from pairs of incomparable arms, with a
set of minimal assumptions. This algorithm relies on the concept of decoys,
which stems from social psychology. For the easier case where the
incomparability information may be accessible, we propose a second algorithm,
SlicingBandits, which takes advantage of this information and achieves a very
significant gain of performance compared to UnchainedBandits. We provide
theoretical guarantees and experimental evaluation for both algorithms.


title: Monopole holes in a partially ordered spin liquid

abstract:
  If spin liquids have been famously defined by what they are not, i.e.
ordered, the past years have seen the frontier between order and spin liquid
starting to fade, with a growing number of materials whose low-temperature
physics cannot be explained without co-existence of (partial) magnetic order
and spin fluctuations. Here we study an example of such co-existence in the
presence of magnetic dipolar interactions, related to spin ice, where the order
is long range and the fluctuations support a Coulomb gauge field. Topological
defects are effectively coupled via energetic and entropic Coulomb
interactions, the latter one being stronger than for the spin-ice ground state.
Depending on whether these defects break the divergence-free condition of the
Coulomb gauge field or the long-range order, they are respectively categorized
as monopoles - as in spin ice - or monopole holes, in analogy with electron
holes in semiconductors. The long-range order plays the role of a
fully-occupied valence band, while the Coulomb spin liquid can be seen as an
empty conducting band. These results are discussed in the context of other
lattices and models which support a similar co-existence of Coulomb gauge field
and long-range order. We conclude this work by explaining how dipolar
interactions lift the spin liquid degeneracy at very low energy scale by
maximizing the number of flippable plaquettes, in light of the equivalent
quantum dimer model.


title: Markov loops, coverings and fields

abstract:
  We investigate the relations between the Poissonnian loop ensembles , their
occupation fields, non ramified Galois coverings of a graph, the associated
gauge fields, and random Eulerian networks.


title:
Indirect excitons in a potential energy landscape created by a
  perforated electrode

abstract:
  We report on the principle and realization of an excitonic device: a ramp
that directs the transport of indirect excitons down a potential energy
gradient created by a perforated electrode at constant voltage. The device
provides an experimental proof of principle for controlling exciton transport
with electrode density gradients. We observed that the exciton transport
distance along the ramp increases with increasing exciton density. This effect
is explained in terms of disorder screening by repulsive exciton-exciton
interactions.


title: Strategic disclosure of opinions on a social network

abstract:
  We study the strategic aspects of social influence in a society of agents
linked by a trust network, introducing a new class of games called games of
influence. A game of influence is an infinite repeated game with incomplete
information in which, at each stage of interaction, an agent can make her
opinions visible (public) or invisible (private) in order to influence other
agents' opinions. The influence process is mediated by a trust network, as we
assume that the opinion of a given agent is only affected by the opinions of
those agents that she considers trustworthy (i.e., the agents in the trust
network that are directly linked to her). Each agent is endowed with a goal,
expressed in a suitable temporal language inspired from linear temporal logic
(LTL). We show that games of influence provide a simple abstraction to explore
the effects of the trust network structure on the agents' behaviour, by
considering solution concepts from game-theory such as Nash equilibrium, weak
dominance and winning strategies.


title:
Residual equilibrium schemes for time dependent partial differential
  equations

abstract:
  Many applications involve partial differential equations which admits
nontrivial steady state solutions. The design of schemes which are able to
describe correctly these equilibrium states may be challenging for numerical
methods, in particular for high order ones. In this paper, inspired by
micro-macro decomposition methods for kinetic equations, we present a class of
schemes which are capable to preserve the steady state solution and achieve
high order accuracy for a class of time dependent partial differential
equations including nonlinear diffusion equations and kinetic equations.
Extension to systems of conservation laws with source terms are also discussed.


title:
Birationality of moduli spaces of twisted $\mathrm{U}(p,q)$-Higgs
  bundles

abstract:
  A $\mathrm{U}(p,q)$-Higgs bundle on a Riemann surface (twisted by a line
bundle) consists of a pair of holomorphic vector bundles, together with a pair
of (twisted) maps between them. Their moduli spaces depend on a real parameter
$\alpha$. In this paper we study wall crossing for the moduli spaces of
$\alpha$-polystable twisted $\mathrm{U}(p,q)$-Higgs bundles. Our main result is
that the moduli spaces are birational for a certain range of the parameter and
we deduce irreducibility results using known results on Higgs bundles. Quiver
bundles and the Hitchin-Kobayashi correspondence play an essential role.


title:
Is the corporate elite disintegrating? Interlock boards and the Mizruchi
  hypothesis

abstract:
  This paper proposes an approach for comparing interlocked board networks over
time to test for statistically significant change. In addition to contributing
to the conversation about whether the Mizruchi hypothesis (that a
disintegration of power is occurring within the corporate elite) holds or not,
we propose novel methods to handle a longitudinal investigation of a series of
social networks where the nodes undergo a few modifications at each time point.
Methodologically, our contribution is twofold: we extend a Bayesian model
hereto applied to compare two time periods to a longer time period, and we
define and employ the concept of a hull of a sequence of social networks, which
makes it possible to circumvent the problem of changing nodes over time.


title:
Generalization of the Kimeldorf-Wahba correspondence for constrained
  interpolation

abstract:
  In this paper, we extend the correspondence between Bayes' estimation and
optimal interpolation in a Reproducing Kernel Hilbert Space (RKHS) to the case
of linear inequality constraints such as boundedness, monotonicity or
convexity. In the unconstrained interpolation case, the mean of the posterior
distribution of a Gaussian Process (GP) given data interpolation is known to be
the optimal interpolation function minimizing the norm in the RKHS associated
to the GP. In the constrained case, we prove that the Maximum A Posteriori
(MAP) or Mode of the posterior distribution is the optimal constrained
interpolation function in the RKHS. So, the general correspondence is achieved
with the MAP estimator and not the mean of the posterior distribution. A
numerical example is given to illustrate this last result.


title: On the notion of "von Neumann vicious circle" coined by John Backus

abstract:
  "The von Neumann vicious circle" means that non-von Neumann computer
architectures cannot be developed because of the lack of widely available and
effective non-von Neumann languages. New languages cannot be created because of
lack of conceptual foundations for non-von Neumann architectures. The reason is
that programming languages are high-level abstract isomorphic copies of von
Neumann computer architectures. This constitutes the current paradigm in
Computer Science. The paradigm is equivalent to the predominant view that
computations on higher order objects (functionals) can be done only
symbolically, i.e. by term rewriting. The paper is a short introduction to the
papers arXiv:1501.03043 and arXiv:1510.02787 trying to break the paradigm by
introducing a framework that may be seen as a higher order functional HDL
(Hardware Description Language).


title:
Testing the asymptotic relation for period spacings from mixed modes of
  red giants observed with the Kepler mission

abstract:
  Dipole mixed pulsation modes of consecutive radial order have been detected
for thousands of low-mass red-giant stars with the NASA space telescope Kepler.
Such modes have the potential to reveal information on the physics of the deep
stellar interior. Different methods have been proposed to derive an observed
value for the gravity-mode period spacing, the most prominent one relying on a
relation derived from asymptotic pulsation theory applied to the gravity-mode
character of the mixed modes. Our aim is to compare results based on this
asymptotic relation with those derived from an empirical approach for three
pulsating red-giant stars. We developed a data-driven method to perform
frequency extraction and mode identification. Next, we used the identified
dipole mixed modes to determine the gravity-mode period spacing by means of an
empirical method and by means of the asymptotic relation. In our methodology,
we consider the phase offset, $\epsilon_{\mathrm{g}}$, of the asymptotic
relation as a free parameter. Using the frequencies of the identified dipole
mixed modes for each star in the sample, we derived a value for the
gravity-mode period spacing using the two different methods. These differ by
less than 5%. The average precision we achieved for the period spacing derived
from the asymptotic relation is better than 1%, while that of our data-driven
approach is 3%. Good agreement is found between values for the period spacing
derived from the asymptotic relation and from the empirical method.
  Full abstract in PDF file.


title:
Regularity properties of fiber derivatives associated with higher-order
  mechanical systems

abstract:
  The aim of this work is to study fiber derivatives associated to Lagrangian
and Hamiltonian functions describing the dynamics of a higher-order autonomous
dynamical system. More precisely, given a function in $T^*T^{(k-1)}Q$, we find
necessary and sufficient conditions for such a function to describe the
dynamics of a kth-order autonomous dynamical system, thus being a kth-order
Hamiltonian function. Then, we give a suitable definition of (hyper)regularity
for these higher-order Hamiltonian functions in terms of their fiber
derivative. In addition, we also study an alternative characterization of the
dynamics in Lagrangian submanifolds in terms of the solutions of the
higher-order Euler-Lagrange equations.


title:
Impact of Directionality on Interference Mitigation in Full-Duplex
  Cellular Network

abstract:
  In this paper, we consider two fundamental full-duplex (FD) architectures,
two-node and three-node, in the context of cellular networks where the
terminals employ directional antennas. The simultaneous transmission and
reception of data in non-orthogonal channels makes FD radio a potential
solution for the currently limited spectrum. However, its implementation
generates high levels of interference either in the form of loopback
interference (LI) from the output to the input antenna of a transceiver or in
the form of co-channel interference in large-scale multicell networks due to
the large number of active links. Using a stochastic geometry model, we
investigate how directional antennas can control and mitigate the co-channel
interference. Furthermore, we provide a model which characterizes the way
directional antennas manage the LI in order to passively suppress it. Our
results show that both architectures can benefit significantly by the
employment of directional antennas. Finally, we consider the case where both
architectures are employed in the network and derive the optimal values for the
density fraction of each architecture which maximize the success probability
and the network throughput.


title: Monotone Subsequences in High-Dimensional Permutations

abstract:
  This paper is part of the ongoing effort to study high-dimensional
permutations. We prove the analogue to the Erd\H{o}s-Szekeres theorem: For
every $k\ge1$, every order-$n$ $k$-dimensional permutation contains a monotone
subsequence of length $\Omega_{k}\left(\sqrt{n}\right)$, and this is tight. On
the other hand, and unlike the classical case, the longest monotone subsequence
in a random $k$-dimensional permutation of order $n$ is asymptotically almost
surely $\Theta_{k}\left(n^{\frac{k}{k+1}}\right)$.


title:
Multimodal Remote Sensing Image Registration with Accuracy Estimation at
  Local and Global Scales

abstract:
  This paper focuses on potential accuracy of remote sensing images
registration. We investigate how this accuracy can be estimated without ground
truth available and used to improve registration quality of mono- and
multi-modal pair of images. At the local scale of image fragments, the
Cramer-Rao lower bound (CRLB) on registration error is estimated for each local
correspondence between coarsely registered pair of images. This CRLB is defined
by local image texture and noise properties. Opposite to the standard approach,
where registration accuracy is only evaluated at the output of the registration
process, such valuable information is used by us as an additional input
knowledge. It greatly helps detecting and discarding outliers and refining the
estimation of geometrical transformation model parameters. Based on these
ideas, a new area-based registration method called RAE (Registration with
Accuracy Estimation) is proposed. In addition to its ability to automatically
register very complex multimodal image pairs with high accuracy, the RAE method
provides registration accuracy at the global scale as covariance matrix of
estimation error of geometrical transformation model parameters or as
point-wise registration Standard Deviation. This accuracy does not depend on
any ground truth availability and characterizes each pair of registered images
individually. Thus, the RAE method can identify image areas for which a
predefined registration accuracy is guaranteed. The RAE method is proved
successful with reaching subpixel accuracy while registering eight complex
mono/multimodal and multitemporal image pairs including optical to optical,
optical to radar, optical to Digital Elevation Model (DEM) images and DEM to
radar cases. Other methods employed in comparisons fail to provide in a stable
manner accurate results on the same test cases.


title:
Ground-based Observations of the Solar Sources of Space Weather (Invited
  Review)

abstract:
  Monitoring of the Sun and its activity is a task of growing importance in the
frame of space weather research and awareness. Major space weather disturbances
at Earth have their origin in energetic outbursts from the Sun: solar flares,
coronal mass ejections and associated solar energetic particles. In this review
we discuss the importance and complementarity of ground-based and space-based
observations for space weather studies. The main focus is drawn on ground-based
observations in the visible range of the spectrum, in particular in the
diagnostically manifold H$\alpha$ spectral line, which enables us to detect and
study solar flares, filaments, filament eruptions, and Moreton waves. Existing
H$\alpha$ networks such as the GONG and the Global High-Resolution H$\alpha$
Network are discussed. As an example of solar observations from space weather
research to operations, we present the system of real-time detection of
H$\alpha$ flares and filaments established at Kanzelh\"ohe Observatory (KSO;
Austria) in the frame of the ESA Space Situational Awareness programme. During
the evaluation period 7/2013 - 11/2015, KSO provided 3020 hours of real-time
H$\alpha$ observations at the SWE portal. In total, 824 H$\alpha$ flares were
detected and classified by the real-time detection system, including 174 events
of H$\alpha$ importance class 1 and larger. For the total sample of events,
95\% of the automatically determined flare peak times lie within $\pm$5 min of
the values given in the official optical flares reports (by NOAA and KSO), and
76\% of the start times. The heliographic positions determined are better than
$\pm$5$^\circ$. The probability of detection of flares of importance 1 or
larger is 95\%, with a false alarm rate of 16\%. These numbers confirm the high
potential of automatic flare detection and alerting from ground-based
observatories.


title: PAC Reinforcement Learning with Rich Observations

abstract:
  We propose and study a new model for reinforcement learning with rich
observations, generalizing contextual bandits to sequential decision making.
These models require an agent to take actions based on observations (features)
with the goal of achieving long-term performance competitive with a large set
of policies. To avoid barriers to sample-efficient learning associated with
large observation spaces and general POMDPs, we focus on problems that can be
summarized by a small number of hidden states and have long-term rewards that
are predictable by a reactive function class. In this setting, we design and
analyze a new reinforcement learning algorithm, Least Squares Value Elimination
by Exploration. We prove that the algorithm learns near optimal behavior after
a number of episodes that is polynomial in all relevant parameters, logarithmic
in the number of policies, and independent of the size of the observation
space. Our result provides theoretical justification for reinforcement learning
with function approximation.


title: Entanglement properties of Floquet Chern insulators

abstract:
  Results are presented for the entanglement entropy and spectrum of
half-filled graphene following the switch on of a circularly polarized laser.
The laser parameters are chosen to correspond to several different Floquet
Chern insulator phases. The entanglement properties of the unitarily evolved
wavefunctions are compared with the state where one of the Floquet bands is
completely occupied. The true states show a volume law for the entanglement,
whereas the Floquet states show an area law. Qualitative differences are found
in the entanglement properties of the off-resonant and on-resonant laser. Edge
states are found in the entanglement spectrum corresponding to certain physical
edge states expected in a Chern insulator. However, some edge states that would
be expected from the Floquet band structure are missing from the entanglement
spectrum. An analytic theory is developed for the long time structure of the
entanglement spectrum. It is argued that only edge states corresponding to
off-resonant processes appear in the entanglement spectrum.


title: Hypergeometric Orthogonal Polynomials with respect to Newtonian Bases

abstract:
  We introduce the notion of "hypergeometric" polynomials with respect to
Newtonian bases. These polynomials are eigenfunctions ($L P_n(x) = \lambda_n
P_n(x)$) of some abstract operator $L$ which is 2-diagonal in the Newtonian
basis $\varphi_n(x)$: $L \varphi_n(x) = \lambda_n \varphi_n(x) + \tau_n(x)
\varphi_{n-1}(x)$ with some coefficients $\lambda_n$, $\tau_n$. We find the
necessary and sufficient conditions for the polynomials $P_n(x)$ to be
orthogonal. For the special cases where the sets $\lambda_n$ correspond to the
classical grids, we find the complete solution to these conditions and observe
that it leads to the most general Askey-Wilson polynomials and their special
and degenerate classes.


title:
Spin lifetimes exceeding 12 nanoseconds in graphene non-local spin valve
  devices

abstract:
  We show spin lifetimes of 12.6 ns and spin diffusion lengths as long as 30.5
\mu m in single layer graphene non-local spin transport devices at room
temperature. This is accomplished by the fabrication of Co/MgO-electrodes on a
Si/SiO$_2$ substrate and the subsequent dry transfer of a graphene-hBN-stack on
top of this electrode structure where a large hBN flake is needed in order to
diminish the ingress of solvents along the hBN-to-substrate interface.
Interestingly, long spin lifetimes are observed despite the fact that both
conductive scanning force microscopy and contact resistance measurements reveal
the existence of conducting pinholes throughout the MgO spin
injection/detection barriers. The observed enhancement of the spin lifetime in
single layer graphene by a factor of 6 compared to previous devices exceeds
current models of contact-induced spin relaxation which paves the way towards
probing intrinsic spin properties of graphene.


title:
Local and Global Convergence of a General Inertial Proximal Splitting
  Scheme

abstract:
  This paper is concerned with convex composite minimization problems in a
Hilbert space. In these problems, the objective is the sum of two closed,
proper, and convex functions where one is smooth and the other admits a
computationally inexpensive proximal operator. We analyze a general family of
inertial proximal splitting algorithms (GIPSA) for solving such problems. We
establish finiteness of the sum of squared increments of the iterates and
optimality of the accumulation points. Weak convergence of the entire sequence
then follows if the minimum is attained. Our analysis unifies and extends
several previous results.
  We then focus on $\ell_1$-regularized optimization, which is the ubiquitous
special case where the nonsmooth term is the $\ell_1$-norm. For certain
parameter choices, GIPSA is amenable to a local analysis for this problem. For
these choices we show that GIPSA achieves finite "active manifold
identification", i.e. convergence in a finite number of iterations to the
optimal support and sign, after which GIPSA reduces to minimizing a local
smooth function. Local linear convergence then holds under certain conditions.
We determine the rate in terms of the inertia, stepsize, and local curvature.
Our local analysis is applicable to certain recent variants of the Fast
Iterative Shrinkage-Thresholding Algorithm (FISTA), for which we establish
active manifold identification and local linear convergence. Our analysis
motivates the use of a momentum restart scheme in these FISTA variants to
obtain the optimal local linear convergence rate.


title: A finite-temperature Hartree-Fock code for shell-model Hamiltonians

abstract:
  The codes HFgradZ.py and HFgradT.py find axially symmetric minima of a
Hartree-Fock energy functional for a Hamiltonian supplied in a shell-model
basis. The functional to be minimized is the Hartree-Fock energy for
zero-temperature properties or the Hartree-Fock grand potential for
finite-temperature properties. Various constraints may be imposed on the
minima.


title: The future of gamma-ray astronomy

abstract:
  The field of gamma-ray astronomy has experienced impressive progress over the
last decade. Thanks to the advent of a new generation of imaging air Cherenkov
telescopes (H.E.S.S., MAGIC, VERITAS) and thanks to the launch of the Fermi-LAT
satellite, several thousand gamma-ray sources are known today, revealing an
unexpected ubiquity of particle acceleration processes in the Universe. Major
scientific challenges are still ahead, such as the identification of the nature
of Dark Matter, the discovery and understanding of the sources of cosmic rays,
or the comprehension of the particle acceleration processes that are at work in
the various objects. This paper presents some of the instruments and mission
concepts that will address these challenges over the next decades.


title: Protostellar Disk Formation Enabled by Removal of Small Dust Grains

abstract:
  It has been shown that a realistic level of magnetization of dense molecular
cloud cores can suppress the formation of a rotationally supported disk (RSD)
through catastrophic magnetic braking in the axisymmetric ideal MHD limit. In
this study, we present conditions for the formation of RSDs through non-ideal
MHD effects computed self-consistently from an equilibrium chemical network. We
find that removing from the standard MRN distribution the large population of
very small grains (VSGs) of ~10 $\AA$ to few 100 $\AA$ that dominate the
coupling of the bulk neutral matter to the magnetic field increases the
ambipolar diffusivity by ~1--2 orders of magnitude at densities below 10$^{10}$
cm$^{-3}$. The enhanced ambipolar diffusion (AD) in the envelope reduces the
amount of magnetic flux dragged by the collapse into the circumstellar
disk-forming region. Therefore, magnetic braking is weakened and more angular
momentum can be retained. With continuous high angular momentum inflow, RSDs of
tens of AU are able to form, survive, and even grow in size, depending on other
parameters including cosmic-ray ionization rate, magnetic field strength, and
rotation speed. Some disks become self-gravitating and evolve into rings in our
2D (axisymmetric) simulations, which have the potential to fragment into
(close) multiple systems in 3D. We conclude that disk formation in magnetized
cores is highly sensitive to chemistry, especially to grain sizes. A moderate
grain coagulation/growth to remove the large population of VSGs, either in the
prestellar phase or during free-fall collapse, can greatly promote AD and help
formation of tens of AU RSDs.


title: A Review on Quantum Search Algorithms

abstract:
  The use of superposition of states in quantum computation, known as quantum
parallelism, has significant advantage in terms of speed over the classical
computation. It can be understood from the early invented quantum algorithms
such as Deutsch's algorithm, Deutsch-Jozsa algorithm and its variation as
Bernstein-Vazirani algorithm, Simon algorithm, Shor's algorithms etc. Quantum
parallelism also significantly speeds up the database search algorithm, which
is important in computer science because it comes as a subroutine in many
important algorithms. Quantum database search of Grover achieves the task of
finding the target element in an unsorted database in a time quadratically
faster than the classical computer. We review the Grover quantum search
algorithms for a singe and multiple target elements in a database. The partial
search algorithm of Grover and Radhakrishnan and its optimization by Korepin,
called GRK algorithm are also discussed.


title:
Non selfadjoint operator algebras: dynamics, classification and
  C*-envelopes

abstract:
  This paper is an expanded version of the lectures I delivered at the Indian
Statistical Institute, Bangalore, during the OTOA 2014 conference.


title: On the classification of GRBs and their occurrence rates

abstract:
  There is mounting evidence for the binary nature of the progenitors of
gamma-ray bursts (GRBs). For a long GRB, the induced gravitational collapse
(IGC) paradigm proposes as progenitor, or "in-state", a tight binary system
composed of a carbon-oxygen core (CO$_{core}$) undergoing a supernova (SN)
explosion which triggers hypercritical accretion onto a neutron star (NS)
companion. For a short GRB, a NS-NS merger is traditionally adopted as the
progenitor. We divide long and short GRBs into two sub-classes, depending on
whether or not a black hole (BH) is formed in the merger or in the
hypercritical accretion process exceeding the NS critical mass. For long
bursts, when no BH is formed we have the sub-class of X-ray flashes (XRFs),
with isotropic energy $E_{iso}\lesssim10^{52}$ erg and rest-frame spectral peak
energy $E_{p,i}\lesssim200$ keV. When a BH is formed we have the sub-class of
binary-driven hypernovae (BdHNe), with $E_{iso}\gtrsim10^{52}$ erg and
$E_{p,i}\gtrsim200$ keV. In analogy, short bursts are similarly divided into
two sub-classes. When no BH is formed, short gamma-ray flashes (S-GRFs) occur,
with $E_{iso}\lesssim10^{52}$ erg and $E_{p,i}\lesssim2$ MeV. When a BH is
formed, the authentic short GRBs (S-GRBs) occur, with $E_{iso}\gtrsim10^{52}$
erg and $E_{p,i}\gtrsim2$ MeV. We give examples and observational signatures of
these four sub-classes and their rate of occurrence. From their respective
rates it is possible that "in-states" of S-GRFs and S-GRBs originate from the
"out-states" of XRFs. We indicate two additional progenitor systems: white
dwarf-NS and BH-NS. These systems have hybrid features between long and short
bursts. In the case of S-GRBs and BdHNe evidence is given of the coincidence of
the onset of the high energy GeV emission with the birth of a Kerr BH.


title:
A dynamical systems approach for the contact-line singularity in
  thin-film flows

abstract:
  We are interested in a complete characterization of the contact-line
singularity of thin-film flows for zero and nonzero contact angles. By treating
the model problem of source-type self-similar solutions, we demonstrate that
this singularity can be understood by the study of invariant manifolds of a
suitable dynamical system. In particular, we prove regularity results for
singular expansions near the contact line for a wide class of mobility
exponents and for zero and nonzero dynamic contact angles. Key points are the
reduction to center manifolds and identifying resonance conditions at
equilibrium points. The results are extended to radially-symmetric source-type
solutions in higher dimensions. Furthermore, we give dynamical systems proofs
for the existence and uniqueness of self-similar droplet solutions in the
nonzero dynamic contact-angle case.


title:
Non-equilibrium simulations of thermally induced electric fields in
  water

abstract:
  Using non-equilibrium molecular dynamics simulations, it has been recently
demonstrated that water molecules align in response to an imposed temperature
gradient, resulting in an effective electric field. Here, we investigate how
thermally induced fields depend on the underlying treatment of long-ranged
interactions. For the short-ranged Wolf method and Ewald summation, we find the
peak strength of the field to range between $2 \times 10^7$ and $5 \times
10^7~\text{V/m}$ for a temperature gradient of $5.2~\text{K/}\unicode{x212B}$.
Our value for the Wolf method is therefore an order of magnitude lower than the
literature value [J. Chem. Phys. 139, 014504 (2013) and 143, 036101 (2015)]. We
show that this discrepancy can be traced back to the use of an incorrect kernel
in the calculation of the electrostatic field. More seriously, we find that the
Wolf method fails to predict correct molecular orientations, resulting in
dipole densities with opposite sign to those computed using Ewald summation. By
considering two different multipole expansions, we show that, for inhomogeneous
polarisations, the quadrupole contribution can be significant and even outweigh
the dipole contribution to the field. Finally, we propose a more accurate way
of calculating the electrostatic potential and the field. In particular, we
show that averaging the microscopic field analytically to obtain the
macroscopic Maxwell field reduces the error bars by up to an order of
magnitude. As a consequence, the simulation times required to reach a given
statistical accuracy decrease by up to two orders of magnitude.


title:
Linear models for the impact of order flow on prices I. Propagators:
  Transient vs. History Dependent Impact

abstract:
  Market impact is a key concept in the study of financial markets and several
models have been proposed in the literature so far. The Transient Impact Model
(TIM) posits that the price at high frequency time scales is a linear
combination of the signs of the past executed market orders, weighted by a
so-called propagator function. An alternative description -- the History
Dependent Impact Model (HDIM) -- assumes that the deviation between the
realised order sign and its expected level impacts the price linearly and
permanently. The two models, however, should be extended since prices are a
priori influenced not only by the past order flow, but also by the past
realisation of returns themselves. In this paper, we propose a two-event
framework, where price-changing and non price-changing events are considered
separately. Two-event propagator models provide a remarkable improvement of the
description of the market impact, especially for large tick stocks, where the
events of price changes are very rare and very informative. Specifically the
extended approach captures the excess anti-correlation between past returns and
subsequent order flow which is missing in one-event models. Our results
document the superior performances of the HDIMs even though only in minor
relative terms compared to TIMs. This is somewhat surprising, because HDIMs are
well grounded theoretically, while TIMs are, strictly speaking, inconsistent.


title:
Probabilistic modeling and global sensitivity analysis for $CO_2$
  storage in geological formations: a spectral approach

abstract:
  This work focuses on the simulation of $CO_2$ storage in deep underground
formations under uncertainty and seeks to understand the impact of
uncertainties in reservoir properties on $CO_2$ leakage. To simulate the
process, a non-isothermal two-phase two-component flow system with equilibrium
phase exchange is used. Since model evaluations are computationally intensive,
instead of traditional Monte Carlo methods, we rely on polynomial chaos (PC)
expansions for representation of the stochastic model response. A non-intrusive
approach is used to determine the PC coefficients. We establish the accuracy of
the PC representations within a reasonable error threshold through systematic
convergence studies. In addition to characterizing the distributions of model
observables, we compute probabilities of excess $CO_2$ leakage. Moreover, we
consider the injection rate as a design parameter and compute an optimum
injection rate that ensures that the risk of excess pressure buildup at the
leaky well remains below acceptable levels. We also provide a comprehensive
analysis of sensitivities of $CO_2$ leakage, where we compute the contributions
of the random parameters, and their interactions, to the variance by computing
first, second, and total order Sobol' indices.


title:
Low-Rank Positive Semidefinite Matrix Recovery from Corrupted Rank-One
  Measurements

abstract:
  We study the problem of estimating a low-rank positive semidefinite (PSD)
matrix from a set of rank-one measurements using sensing vectors composed of
i.i.d. standard Gaussian entries, which are possibly corrupted by arbitrary
outliers. This problem arises from applications such as phase retrieval,
covariance sketching, quantum space tomography, and power spectrum estimation.
We first propose a convex optimization algorithm that seeks the PSD matrix with
the minimum $\ell_1$-norm of the observation residual. The advantage of our
algorithm is that it is free of parameters, therefore eliminating the need for
tuning parameters and allowing easy implementations. We establish that with
high probability, a low-rank PSD matrix can be exactly recovered as soon as the
number of measurements is large enough, even when a fraction of the
measurements are corrupted by outliers with arbitrary magnitudes. Moreover, the
recovery is also stable against bounded noise. With the additional information
of an upper bound of the rank of the PSD matrix, we propose another non-convex
algorithm based on subgradient descent that demonstrates excellent empirical
performance in terms of computational efficiency and accuracy.


title:
Divergent integrals, residues of Dolbeault forms, and asymptotic Riemann
  mappings

abstract:
  We describe the asymptotic behaviour and the dependence on the regularization
of logarithmically divergent integrals of products of meromorphic and
antimeromorphic forms on complex manifolds. Our formula is expressed in terms
of residues of Dolbeault forms, a notion introduced in this paper. The proof is
based on a result on the asymptotic behaviour of Riemann mappings of small
domains.


title: On Determining if Tree-based Networks Contain Fixed Trees

abstract:
  We address an open question of Francis and Steel about phylogenetic networks
and trees. They give a polynomial time algorithm to decide if a phylogenetic
network, N, is tree-based and pose the problem: given a fixed tree T and
network N, is N based on T? We show that it is NP-hard to decide, by reduction
from 3-Dimensional Matching (3DM), and further, that the problem is fixed
parameter tractable.


title: Toom-Cook Multiplication: Some Theoretical and Practical Aspects

abstract:
  Toom-Cook multiprecision multiplication is a well-known multiprecision
multiplication method, which can make use of multiprocessor systems. In this
paper the Toom-Cook complexity is derived, some explicit proofs of the
Toom-Cook interpolation method are given, the even-odd method for interpolation
is explained, and certain aspects of a 32-bit C++ and assembler implementation,
which is in development, are discussed. A performance graph of this
implementation is provided. The Toom-Cook method can also be used to
multithread other types of multiplication, which is demonstrated for 32-bit GMP
FFT multiplication.


title:
Rashba versus Kohn-Luttinger: Evolution of p-wave superconductivity in
  magnetized two-dimensional Fermi gas subject to spin-orbit interaction

abstract:
  We study how the Rashba spin-orbit interaction influences unconventional
superconductivity in a two dimensional electron gas partially spin-polarized by
a magnetic field. Somewhat surprisingly, we find that for all field
orientations, only the larger Fermi surface is superconducting. When the
magnetic field is oriented out-of-plane the system realizes a topological
$p+ip$ pairing state. When the field is rotated in-plane the order parameter
develops nodes along the field direction and finite center-of-mass-momentum
pairing is realized. We demonstrate that the pairing symmetry of the system can
be easily probed experimentally due to the dependence of various thermodynamic
quantities on the magnetic field geometry, and calculate the electronic
specific heat as an example.


title:
Rare region induced avoided quantum criticality in disordered
  three-dimensional Dirac and Weyl semimetals

abstract:
  We numerically study the effect of short ranged potential disorder on
massless noninteracting three-dimensional Dirac and Weyl fermions, with a focus
on the question of the proposed quantum critical point separating the semimetal
and diffusive metal phases. We determine the properties of the eigenstates of
the disordered Dirac Hamiltonian ($H$) and exactly calculate the density of
states (DOS) near zero energy, using a combination of Lanczos on $H^2$ and the
kernel polynomial method on $H$. We establish the existence of two distinct
types of low energy eigenstates contributing to the disordered density of
states in the weak disorder semimetal regime. These are (i) typical eigenstates
that are well described by linearly dispersing perturbatively dressed Dirac
states, and (ii) nonperturbative rare eigenstates that are weakly-dispersive
and quasi-localized in the real space regions with the largest (and rarest)
local random potential. Using twisted boundary conditions, we are able to
systematically find and study these two types of eigenstates. We find that the
Dirac states contribute low energy peaks in the finite-size DOS that arise from
the clean eigenstates which shift and broaden in the presence of disorder. On
the other hand, we establish that the rare quasi-localized eigenstates
contribute a nonzero background DOS which is only weakly energy-dependent near
zero energy and is exponentially small at weak disorder. We find that the
expected semimetal to diffusive metal quantum critical point is converted to an
{\it avoided} quantum criticality that is "rounded out" by nonperturbative
effects, with no signs of any singular behavior in the DOS near the Dirac
energy. We discuss the implications of our results for disordered Dirac and
Weyl semimetals, and reconcile the large body of existing numerical work
showing quantum criticality with the existence of the rare region effects.


title:
The IMP game: Learnability, approximability and adversarial learning
  beyond $\Sigma^0_1$

abstract:
  We introduce a problem set-up we call the Iterated Matching Pennies (IMP)
game and show that it is a powerful framework for the study of three problems:
adversarial learnability, conventional (i.e., non-adversarial) learnability and
approximability. Using it, we are able to derive the following theorems. (1) It
is possible to learn by example all of $\Sigma^0_1 \cup \Pi^0_1$ as well as
some supersets; (2) in adversarial learning (which we describe as a
pursuit-evasion game), the pursuer has a winning strategy (in other words,
$\Sigma^0_1$ can be learned adversarially, but $\Pi^0_1$ not); (3) some
languages in $\Pi^0_1$ cannot be approximated by any language in $\Sigma^0_1$.
  We show corresponding results also for $\Sigma^0_i$ and $\Pi^0_i$ for
arbitrary $i$.


title:
The physical and circuit-theoretic significance of the Memristor : Full
  version

abstract:
  It is observed that the inductive and capacitive features of the memristor
reflect (and are a quintessence of) such features of any resistor. The very
presence of the voltage and current state variables, associated by their
electrodynamics sense with electrical and magnetic fields, in the resistive
characteristic v = f(i), forces any resister to accumulate some magnetic and
electrostatic fields and energies around itself, i.e. L and C elements are
always present. From the circuit-theoretic point of view, the role of the
memristor is seen, first of all, in the elimination of the use of a unique
v(i). This makes circuits with hysteresis characteristics relevant, and also
suggests that the concept of memristor should influence the basic problem of
definition of nonlinearity. Since the memristor mainly originates from the
resistor, it was found necessary to overview some unusual cases of resistive
circuits. The present opinion is that the framework of basic circuit theory and
its connection with applications should be logically expanded in order to
naturally include the new element.


title:
On measures which generate the scalar product in a space of rational
  functions

abstract:
  Let $z_1,z_2,\,\ldots\,,z_n$ be pairwise different points of the unit disc
and $\mathscr{L}(z_1,z_2,\,\ldots\,z_n)$ be the linear space generated by the
rational fractions $\frac{1}{t-z_1} , \frac{1}{t-z_2} , \cdots\ ,
\frac{1}{t-z_n}\cdot$ Every non-negative measure $\sigma$ on the unit circle
$\mathbb{T}$ generates the scalar product
\[\langle\,f\,,\,g\,\rangle_{\!_{L^2_\sigma}}
=\int\limits_{\mathbb{T}}f(t)\,\bar{g(t)}\,\sigma(dt), \quad
\forall\,f,g\,\in\,L^2_\sigma.\] The measures $\sigma$ are described which
satisfy the condition \[\langle\,f\,,\,g\,\rangle_{\!_{L^2_\sigma}}=
\langle\,f\,,\,g\,\rangle_{\!_{L^2_m}},\quad
\forall\,f,g\in\mathscr{L}(z_1,z_2,\,\ldots\,z_n),\] where $m$ is the
normalized Lebesgue measure on $\mathbb{T}$.


abstract:
  A simple model of Bose-Einstein condensation of interacting particles is
proposed. It is shown that in the condensate state the dependence of
thermodynamic quantities on the interaction constant does not allow an
expansion in powers of the coupling constant. Therefore it is impossible to
pass to the Einstein model of condensation in an ideal Bose gas by means of a
limiting passage, setting the interaction constant to zero. The account for the
interaction between particles eliminates difficulties in the description of
condensation available in the model of an ideal gas, which are connected with
fulfillment of thermodynamic relations and an infinite value of the particle
number fluctuation in the condensate phase.


title: Independent sets and cuts in large-girth regular graphs

abstract:
  We present a local algorithm producing an independent set of expected size
$0.44533n$ on large-girth 3-regular graphs and $0.40407n$ on large-girth
4-regular graphs. We also construct a cut (or bisection or bipartite subgraph)
with $1.34105n$ edges on large-girth 3-regular graphs. These decrease the gaps
between the best known upper and lower bounds from $0.0178$ to $0.01$, from
$0.0242$ to $0.0123$ and from $0.0724$ to $0.0616$, respectively. We are using
local algorithms, therefore, the method also provides upper bounds for the
fractional coloring numbers of $1 / 0.44533 \approx 2.24554$ and $1 / 0.40407
\approx 2.4748$ and fractional edge coloring number $1.5 / 1.34105 \approx
1.1185$. Our algorithms are applications of the technique introduced by Hoppen
and Wormald.


title:
Generalizations of Kaplansky Theorem for some (p,k)-Quasihyponormal
  Operators

abstract:
  In the present paper, we generalized some notions of bounded operators to un-
bounded operators on Hilbert space such as k-quasihyponormal and k-paranormal
unbounded operators. Furthermore, we extend the Kaplansky theorem for normal
operators to some (p; k)-quasihyponormal operators. Namely the (p;
k)-quasihyponormality of the product AB and BA for two operators.


title:
The SOPHIE search for northern extrasolar planets IX. Populating the
  brown dwarf desert

abstract:
  Radial velocity planet search surveys of nearby Solar-type stars have shown a
strong deficit of brown dwarf companions within $\sim5\,\mathrm{AU}$. There is
presently no comprehensive explanation of this lack of brown dwarf companions,
therefore, increasing the sample of such objects is crucial to understand their
formation and evolution. Based on precise radial velocities obtained using the
SOPHIE spectrograph at Observatoire de Haute-Provence we characterise the
orbital parameters of $15$ companions to solar-type stars and constrain their
true mass using astrometric data from the Hipparcos space mission. The nine
companions not shown to be stellar in nature have minimum masses ranging from
~$13$ to $70\,\mathrm{M}_{\mathrm{Jup}}$, and are well distributed across the
planet/brown dwarf mass regime, making them an important contribution to the
known population of massive companions around solar-type stars. We characterise
six companions as stellar in nature with masses ranging from a minimum mass of
$76 \pm 4\,\mathrm{M}_{\mathrm{Jup}}$ to a mass of $0.35 \pm
0.03\,\mathrm{M_\odot}$. The orbital parameters of two previously known
sub-stellar candidates are improved.


title:
Evolution of the cosmic matter density field with a primordial magnetic
  field

abstract:
  A cosmological magnetic field affects the time evolution of the cosmic matter
density field. The squared Alfven velocity of the cosmic fluid is proportional
to an ensemble average energy density of a primordial magnetic field (PMF), and
it prevents the matter density field from collapsing in the horizon scale. The
matter-radiation equality time also is delayed by the presence of an ensemble
average energy density of a PMF. The ensemble average energy density of the PMF
also affects the matter power spectrum (MPS) through the Meszaros effect and
the potential decay. Since the ensemble average energy density of the PMF is
not a first order perturbation but a zero order source in the linear
perturbation equations for the cosmology, to correctly understand the overall
effects of the PMF on the MPS, we should significantly revise previous
approaches to research for the MPS with the PMF by considering both the effects
of the zero and first order sources from the PMF in the linear perturbation
theory. We apply the effects of the zero order sources from the PMF to
theoretical computations of the MPS for the first time. We also analyze the
overall PMF effects on the MPS. The CMB polarizations are affected the weak
lensing. The weak lensing is determined by the MPS. Therefore, we have to
consider the zero order sources of the PMF to gain a correct understanding not
only of the MPS but also the CMB polarization.


title:
Lambda does not Lens: Deflection of Light in the Schwarzschild-de Sitter
  Spacetime

abstract:
  Debate persists as to whether the cosmological constant $\Lambda$ can
directly modify the power of a gravitational lens. With the aim of
reestablishing a consensus on this issue, I conduct a comprehensive analysis of
gravitational lensing in the Schwarzschild--de Sitter spacetime, wherein the
effects of $\Lambda$ should be most apparent. The effective lensing law is
found to be in precise agreement with the $\Lambda=0$ result:
$\alpha_\mathrm{eff} = 4m/b_\mathrm{eff}+15\pi m^2/4b_\mathrm{eff}^2
+O(m^3/b_\mathrm{eff}^3)$, where the effective bending angle
$\alpha_\mathrm{eff}$ and impact parameter $b_\mathrm{eff}$ are defined by the
angles and angular diameter distances measured by a comoving cosmological
observer. [These observers follow the timelike geodesic congruence which (i)
respects the continuous symmetries of the spacetime and (ii) approaches local
isotropy most rapidly at large distance from the lens.] The effective lensing
law can be derived using lensed or unlensed angular diameter distances,
although the inherent ambiguity of unlensed distances generates an additional
uncertainty $O(m^5/\Lambda b_\mathrm{eff}^7)$. I conclude that the cosmological
constant does not interfere with the standard gravitational lensing formalism.


title:
The Time-Domain Spectroscopic Survey: Understanding the Optically
  Variable Sky with SEQUELS in SDSS-III

abstract:
  The Time-Domain Spectroscopic Survey (TDSS) is an SDSS-IV eBOSS subproject
primarily aimed at obtaining identification spectra of ~220,000
optically-variable objects systematically selected from SDSS/Pan-STARRS1
multi-epoch imaging. We present a preview of the science enabled by TDSS, based
on TDSS spectra taken over ~320 deg^2 of sky as part of the SEQUELS survey in
SDSS-III, which is in part a pilot survey for eBOSS in SDSS-IV. Using the
15,746 TDSS-selected single-epoch spectra of photometrically variable objects
in SEQUELS, we determine the demographics of our variability-selected sample,
and investigate the unique spectral characteristics inherent in samples
selected by variability. We show that variability-based selection of quasars
complements color-based selection by selecting additional redder quasars, and
mitigates redshift biases to produce a smooth quasar redshift distribution over
a wide range of redshifts. The resulting quasar sample contains systematically
higher fractions of blazars and broad absorption line quasars than from
color-selected samples. Similarly, we show that M-dwarfs in the TDSS-selected
stellar sample have systematically higher chromospheric active fractions than
the underlying M-dwarf population, based on their H-alpha emission. TDSS also
contains a large number of RR Lyrae and eclipsing binary stars with
main-sequence colors, including a few composite-spectrum binaries. Finally, our
visual inspection of TDSS spectra uncovers a significant number of peculiar
spectra, and we highlight a few cases of these interesting objects. With a
factor of ~15 more spectra, the main TDSS survey in SDSS-IV will leverage the
lessons learned from these early results for a variety of time-domain science
applications.


title:
Dark matter fraction of low-mass cluster members probed by galaxy-scale
  strong lensing

abstract:
  We present a strong lensing system, composed of 4 multiple images of a source
at z = 2.387, created by two lens galaxies, G1 and G2, belonging to the galaxy
cluster MACS J1115.9+0129 at z = 0.353. We use observations taken as part of
the Cluster Lensing and Supernova survey with Hubble, CLASH, and its
spectroscopic follow-up programme at the Very Large Telescope, CLASH-VLT, to
estimate the total mass distributions of the two galaxies and the cluster
through strong gravitational lensing models. We find that the total projected
mass values within the half-light radii, R_{e}, of the two lens galaxies are
M_{T,G1}(< R_{e,G1}) = (3.6 +/- 0.4) x 10^{10}M_{Sun} and M_{T,G2}(< R_{e,G2})
= (4.2 +/- 1.6) x 10^{10}M_{Sun}. The effective velocity dispersion values of
G1 and G2 are (122 +/- 7) km/s and (137 +/- 27) km/s, respectively. We remark
that these values are relatively low when compared to those of ~200-300 km/s,
typical of lens galaxies found in the field by previous surveys. By fitting the
spectral energy distributions of G1 and G2, we measure projected luminous over
total mass fractions within R_{e} of 0.11 +/- 0.03, for G1, and 0.73 +/- 0.32,
for G2. The fact that the less massive galaxy, G1, is dark-matter dominated in
its inner regions raises the question of whether the dark matter fraction in
the core of early-type galaxies depends on their mass. Further investigating
strong lensing systems will help us understand the influence that dark matter
has on the structure and evolution of the inner regions of galaxies.


title:
Dust Destruction by the Reverse Shock in the Cassiopeia A Supernova
  Remnant

abstract:
  Core collapse supernovae (CCSNe) are important sources of interstellar dust,
potentially capable of producing one solar mass of dust in their explosively
expelled ejecta. However, unlike other dust sources, the dust has to survive
the passage of the reverse shock, generated by the interaction of the supernova
blast wave with its surrounding medium. Knowledge of the net amount of dust
produced by CCSNe is crucial for understanding the origin and evolution of dust
in the local and high-redshift universe. Our aim is to identify the dust
destruction mechanisms in the ejecta, and derive the net amount of dust that
survives the passage of the reverse shock. We use analytical models for the
evolution of a supernova blast wave and of the reverse shock, with special
application to the clumpy ejecta of the remnant of Cassiopeia A. We assume that
the dust resides in cool oxygen-rich clumps that are uniformly distributed
within the remnant and surrounded by a hot X-ray emitting plasma, and that the
dust consists of silicates (MgSiO3) and amorphous carbon grains. The passage of
the reverse shock through the clumps gives rise to a relative gas-grain motion
and also destroys the clumps. Inside the ejecta clouds, dust is processed via
kinetic sputtering, which is terminated either when the grains escape the
clumps, or when the clumps are destroyed by the reverse shock. In either case,
grain destruction proceeds thereafter by thermal sputtering in the hot ambient
gas. We find that 11.8% and 15.9% of, respectively, the silicate and carbon
dust survives the passage of the reverse shock by the time the shock has
reached the center of the remnant. These fractions depend on the morphology of
the ejecta and the medium into which the remnant is expanding, as well as the
composition and size distribution of the grains that formed in the ejecta.
Results will therefore differ for different types of supernovae.


title: Star Formation in Luminous Quasars at 2<z<3

abstract:
  We investigate the relation between star formation rates ($\dot{M}_{s}$) and
AGN properties in optically selected type 1 quasars at $2<z<3$ using data from
Herschel and the SDSS. We find that $\dot{\rm{M}}_s$ remains approximately
constant with redshift, at $300\pm100~\rm{M}_{\odot}$yr$^{-1}$. Conversely,
$\dot{\rm{M}}_s$ increases with AGN luminosity, up to a maximum of
$\sim600~\rm{M}_{\odot}$yr$^{-1}$, and with CIV FWHM. In context with previous
results, this is consistent with a relation between $\dot{\rm{M}}_s$ and black
hole accretion rate ($\dot{\rm{M}}_{bh}$) existing in only parts of the
$z-\dot{\rm{M}}_{s}-\dot{\rm{M}}_{bh}$ plane, dependent on the free gas
fraction, the trigger for activity, and the processes that may quench star
formation. The relations between $\dot{\rm{M}}_s$ and both AGN luminosity and
CIV FWHM are consistent with star formation rates in quasars scaling with black
hole mass, though we cannot rule out a separate relation with black hole
accretion rate. Star formation rates are observed to decline with increasing
CIV equivalent width. This decline can be partially explained via the Baldwin
effect, but may have an additional contribution from one or more of three
factors; $M_i$ is not a linear tracer of L$_{2500}$, the Baldwin effect changes
form at high AGN luminosities, and high CIV EW values signpost a change in the
relation between $\dot{\rm{M}}_s$ and $\dot{\rm{M}}_{bh}$. Finally, there is no
strong relation between $\dot{\rm{M}}_s$ and Eddington ratio, or the asymmetry
of the CIV line. The former suggests that star formation rates do not scale
with how efficiently the black hole is accreting, while the latter is
consistent with CIV asymmetries arising from orientation effects.


title:
The CALYMHA survey: Ly$\alpha$ escape fraction and its dependence on
  galaxy properties at $z=2.23$

abstract:
  We present the first results from our CAlibrating LYMan-$\alpha$ with
H$\alpha$ (CALYMHA) pilot survey at the Isaac Newton Telescope. We measure
Ly$\alpha$ emission for 488 H$\alpha$ selected galaxies at $z=2.23$ from HiZELS
in the COSMOS and UDS fields with a specially designed narrow-band filter
($\lambda_c$ = 3918 {\AA}, $\Delta\lambda$= 52 {\AA}). We find 17 dual
H$\alpha$-Ly$\alpha$ emitters ($f_{\rm Ly\alpha} >5\times10^{-17}$ erg s$^{-1}$
cm$^{-2}$, of which 5 are X-ray AGN). For star-forming galaxies, we find a
range of Ly$\alpha$ escape fractions (f$_{\rm esc}$, measured with 3$"$
apertures) from $2$\%$-30$\%. These galaxies have masses from $3\times10^8$
M$_{\odot}$ to 10$^{11}$ M$_{\odot}$ and dust attenuations E$(B-V)=0-0.5$.
Using stacking, we measure a median escape fraction of $1.6\pm0.5$\%
($4.0\pm1.0$\% without correcting H$\alpha$ for dust), but show that this
depends on galaxy properties. The stacked f$_{\rm esc}$ tends to decrease with
increasing SFR and dust attenuation. However, at the highest masses and dust
attenuations, we detect individual galaxies with f$_{\rm esc}$ much higher than
the typical values from stacking, indicating significant scatter in the values
of f$_{\rm esc}$. Relations between f$_{\rm esc}$ and UV slope are bimodal,
with high f$_{\rm esc}$ for either the bluest or reddest galaxies. We speculate
that this bimodality and large scatter in the values of f$_{\rm esc}$ is due to
additional physical mechanisms such as outflows facilitating f$_{\rm esc}$ for
dusty/massive systems. Ly$\alpha$ is significantly more extended than H$\alpha$
and the UV. f$_{\rm esc}$ continues to increase up to at least 20 kpc
(3$\sigma$, 40 kpc [2$\sigma$]) for typical SFGs and thus the aperture is the
most important predictor of f$_{\rm esc}$.


title:
A Slippery Slope: Systematic Uncertainties in the Line Width Baryonic
  Tully-Fisher Relation

abstract:
  The baryonic Tully-Fisher relation (BTFR) is a valuable observational tool
and a critical test of galaxy formation theory. We explore the systematic
uncertainty in the slope and the scatter of the observed line width BTFR
utilizing homogeneously measured, unresolved HI observations for 930 isolated
galaxies. We measure a fiducial relation of $\log_{10}{M_{\rm baryon}} =
3.24\log_{10}{V_{\rm rot}}+3.21$ with observed scatter of 0.25 dex with
$10^{7.4} < M_{\rm baryon} < 10^{11.3}M_{\odot}$ where $V_{\rm rot}$ is
measured from 20\% HI line widths. We vary the definitions of $M_{\rm baryon}$
and $V_{\rm rot}$, the sample selection, and the linear fitting algorithm. We
obtain slopes ranging from 2.64 to 3.53 and scatter measurements ranging from
0.14 to 0.41~dex, indicating a systematic uncertainty of 0.25 in the BTFR slope
derived from unresolved HI line widths. We compare our fiducial slope to
literature measurements, where reported slopes range from 3.0 to 4.3 and
scatter is either unmeasured, immeasurable or as large as 0.4~dex. Measurements
derived from unresolved HI line widths tend to produce slopes of 3.3, while
measurements derived from asymptotic rotation curves tend to produce slopes of
3.9. The largest factor affecting the BTFR slope is the definition of $V_{\rm
rot}$. The sample definition, the mass range, and the linear fitting algorithm
also significantly affect the measured BTFR. We find that galaxies in our
sample with $V_{\rm rot} < 100~\rm{km~s^{-1}}$ are consistent with the line
width BTFR of more massive galaxies, but these galaxies drive most of the
observed scatter. It is critical when comparing predictions to an observed BTFR
that the $V_{\rm rot}$ definition, the sample selection and the fitting
algorithm are similarly defined. We recommend direct statistical comparisons
between data sets with commensurable properties as opposed to comparing BTFR
power-law fits.


title:
In hot water: effects of temperature-dependent interiors on the radii of
  water-rich super-Earths

abstract:
  Observational advancements are leading to increasingly precise measurements
of super-Earth masses and radii. Such measurements are used in internal
structure models to constrain interior compositions of super-Earths. It is now
critically important to quantify the effect of various model assumptions on the
predicted radii. In particular, models often neglect thermal effects, a choice
justified by noting that the thermal expansion of a solid Earth-like planet is
small. However, the thermal effects for water-rich interiors may be
significant. We have systematically explored the extent to which thermal
effects can influence the radii of water-rich super-Earths over a wide range of
masses, surface temperatures, surface pressures and water mass fractions. We
developed temperature-dependent internal structure models of water-rich
super-Earths that include a comprehensive temperature-dependent water equation
of state. We found that thermal effects induce significant changes in their
radii. For example, for super-Earths with 10 per cent water by mass, the radius
increases by up to 0.5$\,$R$_\oplus$ when the surface temperature is increased
from 300 to 1000$\,$K, assuming a surface pressure of 100$\,$bar and an
adiabatic temperature gradient in the water layer. The increase is even larger
at lower surface pressures and/or higher surface temperatures, while changing
the water fraction makes only a marginal difference. These effects are
comparable to current super-Earth radial measurement errors, which can be
better than 0.1$\,$R$_\oplus$. It is therefore important to ensure that the
thermal behaviour of water is taken into account when interpreting super-Earth
radii using internal structure models.


title: Clouds in Super-Earth Atmospheres: Chemical Equilibrium Calculations

abstract:
  Recent studies have unequivocally proven the existence of clouds in
super-Earth atmospheres (Kreidberg et al. 2014). Here we provide a theoretical
context for the formation of super-Earth clouds by determining which
condensates are likely to form under the assumption of chemical equilibrium. We
study super-Earth atmospheres of diverse bulk composition, which are assumed to
form by outgassing from a solid core of chondritic material, following Schaefer
& Fegley (2010). The super-Earth atmospheres that we study arise from planetary
cores made up of individual types of chondritic meteorites. They range from
highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are
both subsolar and super-solar, thereby spanning a range of atmospheric
composition that is appropriate for low-mass exoplanets. Given the atomic
makeup of these atmospheres, we minimize the global Gibbs free energy of
formation for over 550 gases and condensates to obtain the molecular
composition of the atmospheres over a temperature range of 350-3,000 K. Clouds
should form along the temperature-pressure boundaries where the condensed
species appear in our calculation. We find that the composition of condensate
clouds depends strongly on both the H:O and C:O ratios. For the super-Earth
archetype GJ 1214b, KCl and ZnS are the primary cloud-forming condensates at
solar composition, in agreement with previous work (Morley et al. 2013;
Miller-Ricci Kempton et al. 2012). However, for oxidizing atmospheres, K2SO4
and ZnO condensates are favored instead, and for carbon-rich atmospheres with
super-solar C:O ratios, graphite clouds appear. For even hotter planets, clouds
form from a wide variety of rock-forming and metallic species.


title:
Using gas clouds to probe the accretion flow around SgrA*: G2's delayed
  pericenter passage

abstract:
  We study the dynamical evolution of the putative gas clouds G1 and G2
recently discovered in the Galactic center. Following earlier studies
suggesting that these two clouds are part of a larger gas streamer, we combine
their orbits into a single trajectory. Since the gas clouds experience a drag
force from background gas, this trajectory is not exactly Keplerian. By
assuming the G1 and G2 clouds trace this trajectory, we fit for the drag force
they experience and thus extract information about the accretion flow at a
distance of thousands of Schwarzschild radii from the black hole. This range of
radii is important for theories of black hole accretion, but is currently
unconstrained by observations.
  In this paper we extend our previous work by accounting for radial forces due
to possible inflow or outflow of the background gas. Such radial forces drive
precession in the orbital plane, allowing a slightly better fit to the G1 and
G2 data. This precession delays the pericenter passage of G2 by 4-5 months
relative to estimates derived from a Keplerian orbital fit; if it proves
possible to identify the pericenter time observationally, this enables an
immediate test of whether G1 and G2 are gas clouds part of a larger gas
streamer. If G2 is indeed a gas cloud, its closest approach likely occurred in
late summer 2014, after many of the observing campaigns monitoring G2's
anticipated pericenter passage ended. We discuss how this affects
interpretation of the G2 observations.


title:
Sub-mm Emission Line Deep Fields: CO and [CII] Luminosity Functions out
  to z = 6

abstract:
  Now that ALMA is reaching its full capabilities, observations of sub-mm
emission line deep fields become feasible. We couple a semi-analytic model of
galaxy formation with a radiative transfer code to make predictions for the
luminosity function of CO J=1-0 up to CO J=6-5 and [CII] at redshifts z=0-6. We
find that: 1) our model correctly reproduces the CO and [CII] emission of low-
and high-redshift galaxies and reproduces the available constraints on the CO
luminosity function at z<2.75; 2) we find that the CO and [CII] luminosity
functions of galaxies increase from z = 6 to z = 4, remain relatively constant
till z = 1 and rapidly decrease towards z = 0. The galaxies that are brightest
in CO and [CII] are found at z~2; 3) the CO J=3-2 emission line is most
favourable to study the CO luminosity and global H2 mass content of galaxies,
because of its brightness and observability with currently available sub-mm and
radio instruments; 4) the luminosity functions of high-J CO lines show stronger
evolution than the luminosity functions of low-J CO lines; 5) our model barely
reproduces the available constraints on the CO and [CII] luminosity function of
galaxies at z>1.5 and the CO luminosity of individual galaxies at intermediate
redshifts. We argue that this is driven by a lack of cold gas in galaxies at
intermediate redshifts as predicted by cosmological simulations of galaxy
formation.


title:
Comparing Young Massive Clusters and their Progenitor Clouds in the
  Milky Way

abstract:
  Young massive clusters (YMCs) have central stellar mass surface densities
exceeding $10^{4} M_{\odot} pc^{-2}$. It is currently unknown whether the stars
formed at such high (proto)stellar densities. We compile a sample of gas clouds
in the Galaxy which have sufficient gas mass within a radius of a few parsecs
to form a YMC, and compare their radial gas mass distributions to the stellar
mass distribution of Galactic YMCs. We find that the gas in the progenitor
clouds is distributed differently than the stars in YMCs. The mass surface
density profiles of the gas clouds are generally shallower than the stellar
mass surface density profiles of the YMCs, which are characterised by prominent
dense core regions with radii ~ 0.1 pc, followed by a power-law tail. On the
scale of YMC core radii, we find that there are no known clouds with
significantly more mass in their central regions when compared to Galactic
YMCs. Additionally, we find that models in which stars form from very dense
initial conditions require surface densities that are generally higher than
those seen in the known candidate YMC progenitor clouds. Our results show that
the quiescent, less evolved clouds contain less mass in their central regions
than in the highly star-forming clouds. This suggests an evolutionary trend in
which clouds continue to accumulate mass towards their centres after the onset
of star formation. We conclude that a conveyor-belt scenario for YMC formation
is consistent with the current sample of Galactic YMCs and their progenitor
clouds.


title: GPD phenomenology and DVCS fitting - Entering the high-precision era

abstract:
  We review the phenomenological framework for accessing Generalized Parton
Distributions (GPDs) using measurements of Deeply Virtual Compton Scattering
(DVCS) from a proton target. We describe various GPD models and fitting
procedures, emphasizing specific challenges posed both by the internal
structure and properties of the GPD functions and by their relation to
observables. Bearing in mind forthcoming data of unprecedented accuracy, we
give a set of recommendations to better define the pathway for a precise
extraction of GPDs from experiment.


title: Expanding the landscape of $\mathcal{N}$=2 rank 1 SCFTs

abstract:
  We refine our previous proposal for systematically classifying 4d rank-1
$\mathcal N=2$ SCFTs by constructing their possible Coulomb branch geometries.
Four new recently discussed rank-1 theories, including novel $\mathcal{N}=3$
SCFTs, sit beautifully in our refined classification framework. By arguing for
the consistency of their RG flows we can make a strong case for the existence
of at least four additional rank-1 SCFTs, nearly doubling the number of known
rank-1 SCFTs.
  The refinement consists of relaxing the assumption that the flavor symmetries
of the SCFTs have no discrete factors. This results in an enlarged (but finite)
set of possible rank-1 SCFTs. Their existence can be further constrained using
consistency of their central charges and RG flows.


title: Testing Quasar Unification: Radiative Transfer in Clumpy Winds

abstract:
  Various unification schemes interpret the complex phenomenology of quasars
and luminous active galactic nuclei (AGN) in terms of a simple picture
involving a central black hole, an accretion disc and an associated outflow.
Here, we continue our tests of this paradigm by comparing quasar spectra to
synthetic spectra of biconical disc wind models, produced with our
state-of-the-art Monte Carlo radiative transfer code. Previously, we have shown
that we could produce synthetic spectra resembling those of observed broad
absorption line (BAL) quasars, but only if the X-ray luminosity was limited to
$10^{43}$ erg s$^{-1}$. Here, we introduce a simple treatment of clumping, and
find that a filling factor of $\sim0.01$ moderates the ionization state
sufficiently for BAL features to form in the rest-frame UV at more realistic
X-ray luminosities. Our fiducial model shows good agreement with AGN X-ray
properties and the wind produces strong line emission in, e.g., Ly \alpha\ and
CIV 1550\AA\ at low inclinations. At high inclinations, the spectra possess
prominent LoBAL features. Despite these successes, we cannot reproduce all
emission lines seen in quasar spectra with the correct equivalent-width ratios,
and we find an angular dependence of emission-line equivalent width despite the
similarities in the observed emission line properties of BAL and non-BAL
quasars. Overall, our work suggests that biconical winds can reproduce much of
the qualitative behaviour expected from a unified model, but we cannot yet
provide quantitative matches with quasar properties at all viewing angles.
Whether disc winds can successfully unify quasars is therefore still an open
question.


title: Collective neutrino flavor conversion: Recent developments

abstract:
  Neutrino flavor evolution in core-collapse supernovae, neutron-star mergers,
or the early universe is dominated by neutrino-neutrino refraction, often
spawning "self-induced flavor conversion", i.e., shuffling of flavor among
momentum modes. This effect is driven by collective run-away modes of the
coupled "flavor oscillators" and can spontaneously break the initial symmetries
such as axial symmetry, homogeneity, isotropy, and even stationarity. Moreover,
the growth rates of unstable modes can be of the order of the neutrino-neutrino
interaction energy instead of the much smaller vacuum oscillation frequency:
self-induced flavor conversion does not always require neutrino masses. We
illustrate these newly found phenomena in terms of simple toy models. What
happens in realistic astrophysical settings is up to speculation at present.


title: Experimental Test of Nonlocal Causality

abstract:
  Explaining observations in terms of causes and effects is central to all of
empirical science. Correlations between entangled quantum particles, however,
seem to defy such an explanation. To recover a causal picture in this case,
some of the fundamental assumptions of causal explanations have to give way.
Here we consider a broad class of models where one of these assumptions, Bell's
local causality, is relaxed by allowing a direct influence from one measurement
outcome to the other. We use interventional and observational data from a
photonic experiment to bound the strength of this causal influence in a
two-party Bell scenario and test a novel Bell-type inequality for the
considered models. Our results demonstrate the incompatibility of quantum
mechanics with an important class of nonlocal causal models, which includes
Bell's original model as a special case. Recovering a classical causal picture
of quantum correlations thus requires an even more counter-intuitive
modification of our classical notion of cause and effect.


title:
$\mathbf{\gamma_{v} NN^{\ast}}$ Electrocouplings in Dyson-Schwinger
  Equations

abstract:
  A symmetry preserving framework for the study of continuum Quantum
Chromodynamics (QCD) is obtained from a truncated solution of the QCD equations
of motion or QCD's Dyson-Schwinger equations (DSEs). A nonperturbative solution
of the DSEs enables the study of, e.g., hadrons as composites of dressed-quarks
and dressed-gluons, the phenomena of confinement and dynamical chiral symmetry
breaking (DCSB), and therefrom an articulation of any connection between them.
It is within this context that we present a unified study of Nucleon, Delta and
Roper elastic and transition electromagnetic form factors, and compare
predictions made using a framework built upon a Faddeev equation kernel and
interaction vertices that possess QCD-like momentum dependence with results
obtained using a symmetry-preserving treatment of a vector$\,\otimes\,$vector
contact-interaction. The comparison emphasises that experiment is sensitive to
the momentum dependence of the running coupling and masses in QCD and
highlights that the key to describing hadron properties is a veracious
expression of dynamical chiral symmetry breaking in the bound-state problem.


title: Exponential growth of colored HOMFLY-PT homology

abstract:
  We define reduced colored sl(N) link homologies and use deformation spectral
sequences to characterize their dependence on color and rank. We then define
reduced colored HOMFLY-PT homologies and prove that they arise as large N
limits of sl(N) homologies. Together, these results allow proofs of many
aspects of the physically conjectured structure of the family of type A link
homologies. In particular, we verify a conjecture of Gorsky, Gukov and
Sto\v{s}i\'c about the growth of colored HOMFLY-PT homologies.


title:
Spatially-Resolved Star Formation Main Sequence of Galaxies in the
  CALIFA Survey

abstract:
  The "main sequence of galaxies" $-$ defined in terms of the total star
formation rate $\psi$ vs. the total stellar mass $M_*$ $-$ is a well-studied
tight relation that has been observed at several wavelengths and at different
redshifts. All earlier studies have derived this relation from integrated
properties of galaxies. We recover the same relation from an analysis of
spatially-resolved properties, with integral field spectroscopic (IFS)
observations of 306 galaxies from the CALIFA survey. We consider the SFR
surface density in units of log(M$_{\odot}$ yr$^{-1}$ Kpc$^{-2}$) and the
stellar mass surface density in units of log(M$_{\odot}$ Kpc$^{-2}$) in
individual spaxels which probe spatial scales of 0.5-1.5 Kpc. This local
relation exhibits a high degree of correlation with small scatter ($\sigma =
0.23$ dex), irrespective of the dominant ionisation source of the host galaxy
or its integrated stellar mass. We highlight: $(i)$ the integrated star
formation main sequence formed by galaxies whose dominant ionisation process is
related to star formation, for which we find a slope of 0.81 $\pm 0.02$; (ii)
the spatially-resolved relation obtained with the spaxel analysis, we find a
slope of 0.72 $\pm 0.04$; (iii) for the integrated main sequence we identified
also a sequence formed by galaxies that are dominated by an old stellar
population, which we have called the retired galaxies sequence.


title: A Cosmic Void Catalog of SDSS DR12 BOSS Galaxies

abstract:
  We present a cosmic void catalog using the large-scale structure galaxy
catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy
catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is
the final catalog of SDSS-III. We take into account the survey boundaries,
masks, and angular and radial selection functions, and apply the ZOBOV void
finding algorithm to the galaxy catalog. We identify a total of 10,643 voids.
After making quality cuts to ensure that the voids represent real underdense
regions, we obtain 1,228 voids with effective radii spanning the range
20-100Mpc/h and with central densities that are, on average, 30% of the mean
sample density. We release versions of the catalogs both with and without
quality cuts. We discuss the basic statistics of voids, such as their size and
redshift distributions, and measure the radial density profile of the voids via
a stacking technique. In addition, we construct mock void catalogs from 1000
mock galaxy catalogs, and find that the properties of BOSS voids are in good
agreement with those in the mock catalogs. We compare the stellar mass
distribution of galaxies living inside and outside of the voids, and find no
significant difference. These BOSS and mock void catalogs are useful for a
number of cosmological and galaxy environment studies.


title:
VEV of Baxter's Q-operator in N=2 gauge theory and the BPZ differential
  equation

abstract:
  In this short notes using AGT correspondence we express simplest fully
degenerate primary fields of Toda field theory in terms an analogue of Baxter's
$Q$-operator naturally emerging in ${\cal N}=2$ gauge theory side. This
quantity can be considered as a generating function of simple trace chiral
operators constructed from the scalars of the ${\cal N}=2$ vector multiplets.
In the special case of Liouville theory, exploring the second order
differential equation satisfied by conformal blocks including a degenerate at
the second level primary field (BPZ equation) we derive a mixed
difference-differential relation for $Q$-operator. Thus we generalize the
$T$-$Q$ difference equation known in Nekrasov-Shatashvili limit of the
$\Omega$-background to the generic case.


title:
How Environment Affects Galaxy Metallicity through Stripping and
  Formation History: Lessons from the Illustris Simulation

abstract:
  Recent studies have found higher galaxy metallicities in richer environments.
It is not yet clear, however, whether metallicity-environment dependencies are
merely an indirect consequence of environmentally dependent formation
histories, or of environment related processes directly affecting metallicity.
Here, we present a first detailed study of metallicity-environment correlations
in a cosmological hydrodynamical simulation, in particular the Illustris
simulation. Illustris galaxies display similar relations to those observed.
Utilizing our knowledge of simulated formation histories, and leveraging the
large simulation volume, we construct galaxy samples of satellites and centrals
that are matched in formation histories. This allows us to find that ~1/3 of
the metallicity-environment correlation is due to different formation histories
in different environments. This is a combined effect of satellites (in
particular, in denser environments) having on average lower z=0 star formation
rates (SFRs), and of their older stellar ages, even at a given z=0 SFR. Most of
the difference, ~2/3, however, is caused by the higher concentration of
star-forming disks of satellite galaxies, as this biases their SFR-weighted
metallicities toward their inner, more metal-rich parts. With a newly defined
quantity, the 'radially averaged' metallicity, which captures the metallicity
profile but is independent of the SFR profile, the metallicities of satellites
and centrals become environmentally independent once they are matched in
formation history. We find that circumgalactic metallicity (defined as rapidly
inflowing gas around the virial radius), while sensitive to environment, has no
measurable effect on the metallicity of the star-forming gas inside the
galaxies.


title:
Type II supernovae progenitor and ejecta properties from the total
  emitted light, ET

abstract:
  It was recently shown that the bolometric light curves of type II supernovae
(SNe) allow an accurate and robust measurement of the product of the radiation
energy in the ejecta, $E_r$, and the time since the explosion, $t$, at early
phases ($t\lesssim 10d$) of the homologous expansion. This observable, denoted
here $ET \equiv E_rt$ is constant during that time and depends only on the
progenitor structure and explosion energy. We use a 1D hydrodynamic code to
find $ET$ of simulated explosions of 145 red supergiant progenitors obtained
using the stellar evolution code MESA, and relate this observable to the
properties of the progenitor and the explosion energy. We show that $ET$ probes
only the properties of the envelope (velocity, mass and initial structure),
similarly to other observables that rely on the photospheric phase emission.
Nevertheless, for explosions where the envelope dominates the ejected mass,
$M_{env}/M_{ej} \gtrsim 0.6$, $ET$ is directly related to the explosion energy
$E_{exp}$ and ejected mass $M_{ej}$ through the relation $ET \approx 0.15
E_{exp}^{1/2} R_* M_{ej}^{1/2}$, where $R_*$ is the progenitor radius, to an
accuracy better than $30\%$. We also provide relations between $ET$ and the
envelope properties that are accurate (to within 20\%) for all the progenitors
in our sample, including those that lost most of their envelope. We show that
when the envelope velocity can be reasonably measured by line shifts in
observed spectra, the envelope is directly constrained from the bolometric
light curve (independent of $E_{exp}$). We use that to compare observations of
11 SNe with measured $ET$ and envelope velocity to our sample of numerical
progenitors. This comparison suggests that many SNe progenitors have radii that
are $\lesssim 500~R_\odot$. In the framework of our simulations this indicates,
most likely, a rather high value of the mixing length parameter.


title:
Young Galaxy Candidates in the Hubble Frontier Fields - III.
  MACSJ0717.5+3745

abstract:
  In this paper we present the results of our search for and study of $z
\gtrsim 6$ galaxy candidates behind the third Frontier Fields (FF) cluster,
MACSJ0717.5+3745, and its parallel field, combining data from Hubble and
Spitzer. We select 39 candidates using the Lyman Break technique, for which the
clear non-detection in optical make the extreme mid-$z$ interlopers hypothesis
unlikely. We also take benefit from $z \gtrsim 6$ samples selected using
previous Frontier Fields datasets of Abell 2744 and MACS0416 to improve the
constraints on the properties of very high-redshift objects. We compute the
redshift and the physical properties, such emission lines properties, star
formation rate, reddening, and stellar mass for all Frontier Fields objects
from their spectral energy distribution using templates including nebular
emission lines. We study the relationship between several physical properties
and confirm the trend already observed in previous surveys for evolution of
star formation rate with galaxy mass, and between the size and the UV
luminosity of our candidates. The analysis of the evolution of the UV
Luminosity Function with redshift seems more compatible with an evolution of
density. Moreover, no robust $z\ge$8.5 object is selected behind the cluster
field, and few $z$$\sim$9 candidates have been selected in the two previous
datasets from this legacy survey, suggesting a strong evolution in the number
density of galaxies between $z$$\sim$8 and 9. Thanks to the use of the lensing
cluster, we study the evolution of the star formation rate density produced by
galaxies with L$>$0.03L$^{\star}$, and confirm the strong decrease observed
between $z$$\sim$8 and 9.


title: Gravitational perturbations of the Higgs field

abstract:
  We study the possible effects of classical gravitational backgrounds on the
Higgs field through the modifications induced in the one-loop effective
potential and the vacuum expectation value of the energy-momentum tensor. We
concentrate our study on the Higgs self-interaction contribution in a perturbed
FRW metric. For weak and slowly varying gravitational fields, a complete set of
mode solutions for the Klein-Gordon equation is obtained to leading order in
the adiabatic approximation. Dimensional regularization has been used in the
integral evaluation and a detailed study of the integration of nonrational
functions in this formalism has been presented. As expected, the regularized
effective potential contains the same divergences as in flat spacetime, which
can be renormalized without the need of additional counterterms. We find that,
in contrast with other regularization methods, even though metric perturbations
affect the mode solutions, they do not contribute to the leading adiabatic
order of the potential. We also obtain explicit expressions of the complete
energy-momentum tensor for general nonminimal coupling in terms of the
perturbed modes. The corresponding leading adiabatic contributions are also
obtained.


title: Wigner crystal phases in bilayer graphene

abstract:
  It is generally believed that a Wigner Crystal in single layer graphene can
not form because the magnitudes of the Coulomb interaction and the kinetic
energy scale similarly with decreasing electron density. However, this scaling
argument does not hold for the low energy states in bilayer graphene. We
consider the formation of a Wigner Crystal in weakly doped bilayer graphene
with an energy gap opened by a perpendicular electric field. We argue that in
this system the formation of the Wigner Crystal is not only possible, but
different phases of the crystal with very peculiar properties may exist here
depending on the system parameters.