title:
The Informational Content of the Limit Order Book: An Empirical Study of
  Prediction Markets

abstract:
  In this paper I empirically investigate prediction markets for binary
options. Advocates of prediction markets have suggested that asset prices are
consistent estimators of the "true" probability of a state of the world being
realized. I test whether the market reaches a "consensus." I find little
evidence for convergence in beliefs. I then determine whether an econometrician
using data beyond execution prices can leverage this data to estimate the
consensus belief. I use an incomplete specification of equilibrium outcomes to
derive bounds on beliefs from order submission decisions. Interval estimates of
mean beliefs cannot exclude aggregate beliefs equal to 0.5.


title:
Time dependent diffusive shock acceleration and its application to
  middle aged supernova remnants

abstract:
  Recent gamma-ray observations show that middle aged supernova remnants (SNRs)
interacting with molecular clouds (MCs) can be sources of both GeV and TeV
emission. Based on the MC association, two scenarios have been proposed to
explain the observed gamma-ray emission. In one, energetic cosmic ray (CR)
particles escape from the SNR and then illuminate nearby MCs, producing
gamma-ray emission, while the other involves direct interaction between the SNR
and MC. In the direct interaction scenario, re-acceleration of pre-existing CRs
in the ambient medium is investigated while particles injected from the thermal
pool are neglected in view of the slow shock speeds in middle aged SNRs.
However, standard diffusive shock acceleration (DSA) theory produces a steady
state particle spectrum that is too flat compared to observations, which
suggests that the high energy part of the observed spectrum has not yet reached
a steady state. We derive a time dependent DSA solution in the test particle
limit for re-acceleration of pre-existing CRs case and show that it is capable
of reproducing the observed gamma-ray emission in SNRs like IC 443 and W44, in
the context of a MC interaction model. We also provide a simple physical
picture to understand the time dependent DSA spectrum. A spatially averaged
diffusion coefficient around the SNR can be estimated through fitting the
gamma-ray spectrum. The spatially averaged diffusion coefficient in middle aged
SNRs like IC 443 and W44 is estimated to be ~ 10^25 cm^2/s at ~ 1GeV, which is
between the Bohm limit and interstellar value.


title: Hilbert and Thompson isometries on cones in JB-algebras

abstract:
  Hilbert's and Thompson's metric spaces on the interior of cones in
JB-algebras are important examples of symmetric Finsler spaces. In this paper
we characterize the Hilbert's metric isometries on the interiors of cones in
JBW-algebras, and the Thompson's metric isometries on the interiors of cones in
JB-algebras. These characterizations generalize work by Bosch\'e on the Hilbert
and Thompson isometries on symmetric cones, and work by Hatori and Moln\'ar on
the Thompson isometries on the cone of positive self-adjoint elements in a
unital $C^*$-algebra. To obtain the results we develop a variety of new
geometric and Jordan algebraic techniques.


title:
Hong-Ou-Mandel experiment for temporal investigation of single electron
  fractionalization

abstract:
  Coulomb interaction has a striking effect on electronic propagation in one
dimensional conductors. The interaction of an elementary excitation with
neighboring conductors favors the emergence of collective modes which
eventually leads to the destruction of the Landau quasiparticle. In this
process, an injected electron tends to fractionalize into separated pulses
carrying a fraction of the electron charge. Here we use two-particle
interferences in the electronic analog of the Hong-Ou-Mandel experiment in a
quantum Hall conductor at filling factor 2 to probe the fate of a single
electron emitted in the outer edge channel and interacting with the inner one.
By studying both channels, we analyze the propagation of the single electron
and the generation of interaction induced collective excitations in the inner
channel. These complementary information reveal the fractionalization process
in time domain and establish its relevance for the destruction of the
quasiparticle which degrades into the collective modes.


title:
Self-Sustained Recycling in the Inner Dust Ring of Pre-Transitional
  Disks

abstract:
  Observations of pre-transitional disks show a narrow inner dust ring and a
larger outer one. They are separated by a cavity with no or only little dust.
We propose an efficient recycling mechanism for the inner dust ring which keeps
it in a steady-state. No major particle sources are needed for replenishment.
Dust particles and pebbles drift outwards by radiation pressure and
photophoresis. The pebbles grow during outward drift until they reach a
balanced position where residual gravity compensates photophoresis. While still
growing larger they reverse their motion and drift inwards. Eventually, their
speed is fast enough that they get destroyed in collisions with other pebbles
and drift outwards again. We quantify the force balance and drift velocities
for the disks LkCa15 and HD135344B. We simulate single particle evolution and
show that this scenario is viable. Growth and drift timescales are on the same
order and a steady state can be established in the inner dust ring.


title:
Technical Report: Timing Abstraction of Perturbed LTI systems with
  $\mathcal{L}_2$-based Event-Triggering Mechanism

abstract:
  In networked control systems, the advent of event-triggering strategies in
the sampling process has resulted in the usage reduction of network capacities,
such as communication bandwidth. However, the aperiodic nature of sampling
periods generated by event-triggering strategies has hindered the
schedulability of such networks. In this study, we propose a framework to
construct a timed safety automaton that captures the sampling behavior of
perturbed LTI systems with an $\mathcal{L}_2$-based triggering mechanisms
proposed in the Literature. In this framework, the state-space is partitioned
into a finite number of convex polyhedral cones, each cone representing a
discrete mode in the abstracted automaton. Adopting techniques from stability
analysis of retarded systems accompanied with a polytopic embedding of time,
LMI conditions to characterize the sampling interval associated with each
region are derived. Then, using reachability analysis, the transitions in the
abstracted automaton are derived.


title:
Lyman-alpha spectral properties of five newly discovered Lyman continuum
  emitters

abstract:
  We have recently reported the discovery of five low redshift Lyman continuum
(LyC) emitters (LCEs, hereafter) with absolute escape fractions fesc(LyC)
ranging from 6 to 13%, higher than previously found, and which more than
doubles the number of low redshift LCEs.We use these observations to test
theoretical predictions about a link between the characteristics of the
Lyman-alpha (Lya) line from galaxies and the escape of ionising photons. We
analyse the Lya spectra of eight LCEs of the local Universe observed with the
Cosmic Origins Spectrograph onboard the Hubble Space Telescope (our five
leakers and three galaxies from the litterature), and compare their strengths
and shapes to the theoretical criteria and comparison samples of local
galaxies: the Lyman Alpha Reference Survey, Lyman Break Analogs, Green Peas,
and the high-redshift strong LyC leaker Ion2. Our LCEs are found to be strong
Lya emitters, with high equivalent widths, EW(Lya)> 70 {\AA}, and large Lya
escape fractions, fesc(Lya) > 20%. The Lya profiles are all double-peaked with
a small peak separation, in agreement with our theoretical expectations. They
also have no underlying absorption at the Lya position. All these
characteristics are very different from the Lya properties of typical
star-forming galaxies of the local Universe. A subset of the comparison samples
(2-3 Green Pea galaxies) share these extreme values, indicating that they could
also be leaking. We also find a strong correlation between the star formation
rate surface density and the escape fraction of ionising photons, indicating
that the compactness of star-forming regions plays a role in shaping low column
density paths in the interstellar medium of LCEs. The Lya properties of LCEs
are peculiar: Lya can be used as a reliable tracer of LyC escape from galaxies,
in complement to other indirect diagnostics proposed in the literature.


title: Boosting Nodes for Improving the Spread of Influence

abstract:
  Information diffusion in networks has received a lot of recent attention.
Most previous work addresses the influence maximization problem of selecting an
appropriate set of seed nodes to initiate the diffusion process so that the
largest number of nodes is reached. Since the seed selection problem is NP
hard, most solutions are sub-optimal. Furthermore, there may be settings in
which the seed nodes are predetermined. Thus, a natural question that arise is:
given a set of seed nodes, can we select a small set of nodes such that if we
improve their reaction to the diffusion process, the largest increase in
diffusion spread is achieved? We call this problem, the boost set selection
problem. In this paper, we formalize this problem, study its complexity and
propose appropriate algorithms. We also evaluate the effect of boosting in a
number of real networks and report the increase of influence spread achieved
for different seed sets, time limits in the diffusion process and other
diffusion parameters.


title: Generalized Sparse Covariance-based Estimation

abstract:
  In this work, we extend the sparse iterative covariance-based estimator
(SPICE), by generalizing the formulation to allow for different norm
constraints on the signal and noise parameters in the covariance model. For a
given norm, the resulting extended SPICE method enjoys the same benefits as the
regular SPICE method, including being hyper-parameter free, although the choice
of norms are shown to govern the sparsity in the resulting solution.
Furthermore, we show that solving the extended SPICE method is equivalent to
solving a penalized regression problem, which provides an alternative
interpretation of the proposed method and a deeper insight on the differences
in sparsity between the extended and the original SPICE formulation. We examine
the performance of the method for different choices of norms, and compare the
results to the original SPICE method, showing the benefits of using the
extended formulation. We also provide two ways of solving the extended SPICE
method; one grid-based method, for which an efficient implementation is given,
and a gridless method for the sinusoidal case, which results in a semi-definite
programming problem.


title: Breaking the sound barrier in AdS/CFT

abstract:
  It has been conjectured that the speed of sound in holographic models with UV
fixed points has an upper bound set by the value of the quantity in conformal
field theory. If true, this would set stringent constraints for the presence of
strongly coupled quark matter in the cores of physical neutron stars, as the
existence of two-solar-mass stars appears to demand a very stiff Equation of
State. In this article, we present a family of counterexamples to the speed of
sound conjecture, consisting of strongly coupled theories at finite density.
The theories we consider include ${\cal N}=4$ super Yang-Mills at finite
R-charge density and non-zero gaugino masses, while the holographic duals are
Einstein-Maxwell theories with a minimally coupled scalar in a charged black
hole geometry. We show that for a small breaking of conformal invariance, the
speed of sound approaches the conformal value from above at large chemical
potentials.


title: Radiation Hardening of LED Luminaires for Accelerator Tunnels

abstract:
  This paper summarises progress made towards the radiation hardening of LED
emergency luminaires for evacuation and emergency response within the
underground areas of the CERN accelerator complex. The objective has been to
radiation harden existing Commercial Off-The-Shelf (COTS) emergency luminaires
to maximise lighting performance, without compromising IEC 60598-2-22
compliance. A systems level approach has been adopted, leading to the
development of a diode bridge based AC/DC power converter. Modified COTS
luminaires including this converter design have been irradiated (to 100 kGy TID
using a Cobalt-60 source), with results of a subsequent photometric analysis
presented. Following encouraging tests results, a reference design for the
power converter has been released under the CERN Open Hardware License to
encourage manufacturer adoption. The paper concludes with areas of interest for
future research in further improving the radiation hardness of LED emergency
lighting for accelerators with detailed studies at the component level for high
power white LED devices and associated optical components.


title: On rational functions whose normalization has genus zero or one

abstract:
  We give a complete list of rational functions $A$ such that the genus $g$ of
the Galois closure of $\mathbb C(z)/\mathbb C(A)$ equals zero. We also provide
a geometric description of $A$ for which $g=1.$


title: Generalized Thermodynamics of Phase Equilibria in Scalar Active Matter

abstract:
  Motility-induced phase separation (MIPS) arises generically in fluids of
self-propelled particles when interactions lead to a kinetic slowdown at high
densities. Starting from a continuum description of scalar active matter, akin
to a generalized Cahn-Hilliard equation, we give a general prescription for the
mean densities of coexisting phases in flux-free steady states that amounts, at
a hydrodynamics scale, to extremizing an effective free energy. We illustrate
our approach on two well-known models: self-propelled particles interacting
either through a density-dependent propulsion speed or via direct pairwise
forces. Our theory accounts quantitatively for their phase diagrams, providing
a unified description of MIPS.


title: Designing Workflow Systems Using Building Blocks

abstract:
  We suggest there is a need for a fresh perspective on the design and
development of workflow systems and argue for a building blocks approach. We
outline a description of this approach and define the properties of software
building blocks. We discuss RADICAL-Cybertools as one implementation of the
building blocks concept, showing how they have been designed and developed in
accordance with this approach. Four case studies are presented, covering a
dozen science problems. We discuss how RADICAL-Cybertools have been used to
develop new workflow systems capabilities and integrated to enhance existing
ones, illustrating the applicability and potential of software building blocks.
In doing so, we have begun an investigation of an alternative approach to
thinking about the design and implementation of workflow systems.


title: A variation on the homological nerve theorem

abstract: An equivalent but useful version on the Homological Nerve Theorem is proved.


title:
Induced magnetism at the interfaces of a Fe/V superlattice investigated
  by resonant magnetic x-ray scattering

abstract:
  The induced magnetic moments in the V 3d electronic states of interface
atomic layers in a Fe(6ML)/V(7ML) superlattice was investigated by x-ray
resonant magnetic scattering. The first V atomic layer next to Fe was found to
be strongly antiferromagnetically polarized relatively to Fe and the magnetic
moments of the next few atomic layers in the interior V region decay
exponentially with increasing distance from the interface, while the magnetic
moments of the Fe atomic layers largely remain bulk-like. The induced V moments
decay more rapidly as observed by x-ray magnetic scattering than in standard
x-ray magnetic circular dichroism. The theoretical description of the induced
magnetic atomic layer profile in V was found to strongly rely on the interface
roughness within the superlattice period. These results provide new insight
into interface magnetism by taking advantage of the enhanced depth sensitivity
to the magnetic profile over a certain resonant energy bandwidth in the
vicinity of the Bragg angles.


title:
Real Space Investigation of order-disorder transition of vortex lattice
  in Co-intercalated 2H-NbSe2

abstract:
  The work presented in my doctoral thesis is an experimental investigation of
the nature of order to disorder transition of vortex lattice in a Type-II
superconductor namely Co-intercalated 2H-NbSe2 using scanning tunnelling
spectroscopy and complimentary ac susceptibility measurements. We have shown by
performing real space imaging across the magnetic field driven peak effect that
the vortex lattice in a 3-dimensional, weakly pinned Type-II superconductor
disorders through two distinct topological phase transitions. Clear evidence of
superheating and supercooling with different topological property of the
metastable states from the actual ground states indicated the nature of both
the phase transformations to be of first order. We have also demonstrated the
role of underlying crystalline lattice symmetry by showing that it aligns the
vortex lattice along preferential directions which is the lattice vectors of
the crystal lattice itself. This underlying coupling also has profound
implication in the order disorder transition indicating the significant role of
vortex lattice-crystal lattice interaction in vortex phase diagram which was
earlier being neglected.


title: A New Architecture for Optimization Modeling Frameworks

abstract:
  We propose a new architecture for optimization modeling frameworks in which
solvers are expressed as computation graphs in a framework like TensorFlow
rather than as standalone programs built on a low-level linear algebra
interface. Our new architecture makes it easy for modeling frameworks to
support high performance computational platforms like GPUs and distributed
clusters, as well as to generate solvers specialized to individual problems.
Our approach is particularly well adapted to first-order and indirect
optimization algorithms. We introduce cvxflow, an open-source convex
optimization modeling framework in Python based on the ideas in this paper, and
show that it outperforms the state of the art.


title:
Studies of inclusive four-jet production with two b-tagged jets in
  proton-proton collisions at 7 TeV

abstract:
  Measurements are presented of the cross section for the production of at
least four jets, of which at least two originate from b quarks, in
proton-proton collisions. Data collected with the CMS detector at the LHC at a
center-of-mass energy of 7 TeV are used, corresponding to an integrated
luminosity of 3 inverse picobarns. The cross section is measured as a function
of the jet transverse momentum for pt > 20 GeV, and of the jet pseudorapidity
for abs(eta) < 2.4 (b jets), 4.7 (untagged jets). The correlations in azimuthal
angle and pt between the jets are also studied. The inclusive cross section is
measured to be sigma(pp to 2 b + 2 j + X) = 69 +/- 3 (stat) +/- 24 (syst) nb.
The eta and pt distributions of the four jets and the correlations between them
are well reproduced by event generators that combine perturbative QCD
calculations at next-to-leading-order accuracy with contributions from parton
showers and multiparton interactions.


title: Transfer String Kernel for Cross-Context DNA-Protein Binding Prediction

abstract:
  Through sequence-based classification, this paper tries to accurately predict
the DNA binding sites of transcription factors (TFs) in an unannotated cellular
context. Related methods in the literature fail to perform such predictions
accurately, since they do not consider sample distribution shift of sequence
segments from an annotated (source) context to an unannotated (target) context.
We, therefore, propose a method called "Transfer String Kernel" (TSK) that
achieves improved prediction of transcription factor binding site (TFBS) using
knowledge transfer via cross-context sample adaptation. TSK maps sequence
segments to a high-dimensional feature space using a discriminative mismatch
string kernel framework. In this high-dimensional space, labeled examples of
the source context are re-weighted so that the revised sample distribution
matches the target context more closely. We have experimentally verified TSK
for TFBS identifications on fourteen different TFs under a cross-organism
setting. We find that TSK consistently outperforms the state-of the-art TFBS
tools, especially when working with TFs whose binding sequences are not
conserved across contexts. We also demonstrate the generalizability of TSK by
showing its cutting-edge performance on a different set of cross-context tasks
for the MHC peptide binding predictions.


title:
$\hat{G}$-local systems on smooth projective curves are potentially
  automorphic

abstract:
  Let $X$ be a smooth, projective, geometrically connected curve over a finite
field $\mathbb{F}_q$, and let $G$ be a split semisimple algebraic group over
$\mathbb{F}_q$. Its dual group $\hat{G}$ is a split reductive group over
$\mathbb{Z}$. Conjecturally, any $l$-adic $\hat{G}$-local system on $X$
(equivalently, any conjugacy class of continuous homomorphisms $\pi_1(X) \to
\hat{G}(\bar{\mathbb{Q}}_l)$) should be associated to an everywhere unramified
automorphic representation of the group $G$.
  We show that for any homomorphism $\pi_1(X) \to \hat{G}(\bar{\mathbb{Q}}_l)$
of Zariski dense image, there exists a finite Galois cover $Y \to X$ over which
the associated local system becomes automorphic.


title: Groups from class 2 algebras and the Weil character

abstract:
  We investigate the behaviour of the Weil character of the symplectic group on
restriction to subgroups arising from commutative nilpotent algebras of class
2. We give explicit descriptions of the decomposition of the Weil character
when restricted to the unipotent radical of the stabilizer of a maximal totally
isotropic subspace and to its centralizer.


title: Unitary Networks from the Exact Renormalization of Wave Functionals

abstract:
  The exact renormalization group (ERG) for $O(N)$ vector models (at large $N$)
on flat Euclidean space can be interpreted as the bulk dynamics corresponding
to a holographically dual higher spin gauge theory on $AdS_{d+1}$. This was
established in the sense that at large $N$ the generating functional of
correlation functions of single trace operators is reproduced by the on-shell
action of the bulk higher spin theory, which is most simply presented in a
first-order (phase space) formalism. In this paper, we extend the ERG formalism
to the wave functionals of arbitrary states of the $O(N)$ vector model at the
free fixed point. We find that the ERG flow of the ground state and a specific
class of excited states is implemented by the action of unitary operators which
can be chosen to be local. Consequently, the ERG equations provide a continuum
notion of a tensor network. We compare this tensor network with the
entanglement renormalization networks, MERA, and its continuum version, cMERA,
which have appeared recently in holographic contexts. In particular the ERG
tensor network appears to share the general structure of cMERA but differs in
important ways. We comment on possible holographic implications.


title:
Decoherence and relaxation of a single electron in a one dimensional
  conductor

abstract:
  We study the decoherence and relaxation of a single elementary electronic
excitation propagating in a one-dimensional chiral conductor. Using
two-particle interferences in the electronic analog of the Hong-Ou-Mandel
experiment, we analyze quantitatively the decoherence scenario of a single
electron propagating along a quantum Hall edge channel at filling factor 2. The
decoherence results from the emergence of collective neutral excitations
induced by Coulomb interaction and leading, in one dimension, to the
destruction of the elementary quasiparticle. This study establishes the
relevance of electron quantum optics setups to provide stringent tests of
strong interaction effects in one-dimensional conductors described by Luttinger
liquids paradigm.


title: Single beam collective effects in FCC-ee due to beam coupling impedance

abstract:
  The Future Circular Collider study, hosted by CERN to design post-LHC
particle accelerator options in a worldwide context, is focused on
proton-proton high-energy and electron-positron high-luminosity frontier
machines. This new accelerator complex represents a great challenge under
several aspects, which involve R&D on beam dynamics and new technologies. One
very critical point in this context is represented by collective effects,
generated by the interaction of the beam with self-induced electromagnetic
fields, called wake fields, which could produce beam instabilities, thus
reducing the machines performance and limiting the maximum stored current. It
is therefore very important to be able to predict these effects and to study in
detail potential solutions to counteract them. In this paper the resistive wall
and some other important geometrical sources of impedance for the FCC
electron-positron accelera- tor are identified and evaluated, and their impact
on the beam dynamics, which in some cases could lead to unwanted instabilities,
is discussed.


title:
Combining internally contracted states and matrix product states to
  perform multireference perturbation theory

abstract:
  We present two efficient and intruder-free methods for treating dynamic
correlation on top of general multi-configuration reference wave
functions---including such as obtained by the density matrix renormalization
group (DMRG) with large active spaces. The new methods are the second order
variant of the recently proposed multi-reference linearized coupled cluster
method (MRLCC) [S. Sharma, A. Alavi, J. Chem. Phys. 143, 102815 (2015)], and of
N-electron valence perturbation theory (NEVPT2), with expected accuracies
similar to MRCI+Q and (at least) CASPT2, respectively. Great efficiency gains
are realized by representing the first-order wave function with a combination
of internal contraction (IC) and matrix product state perturbation theory
(MPSPT). With this combination, only third order reduced density matrices
(RDMs) are required. Thus, we obviate the need for calculating (or estimating)
RDMs of fourth or higher order; these had so far posed a severe bottleneck for
dynamic correlation treatments involving the large active spaces accessible to
DMRG. Using several benchmark systems, including first and second row
containing small molecules, Cr$_2$, pentacene and oxo-Mn(Salen), we shown that
active spaces containing at least 30 orbitals can be treated using this method.
On a single node, MRLCC2 and NEVPT2 calculations can be performed with over 550
and 1100 virtual orbitals, respectively. We also critically examine the errors
incurred due to the three sources of errors introduced in the present
implementation - calculating second order instead of third order energy
corrections, use of internal contraction and approximations made in the
reference wavefunction due to DMRG.


title: A proof of the $4$-variable Catalan polynomial of the Delta conjecture

abstract:
  In The Delta Conjecture (arxiv:1509.07058), Haglund, Remmel and Wilson
introduced a four variable $q,t,z,w$ Catalan polynomial, so named because the
specialization of this polynomial at the values $(q,t,z,w) = (1,1,0,0)$ is
equal to the Catalan number $\frac{1}{n+1}\binom{2n}{n}$. We prove the
compositional version of this conjecture (which implies the non-compositional
version) that states that the coefficient of $s_{r,1^{n-r}}$ in the expression
$\Delta_{h_\ell} \nabla C_\alpha$ is equal to a weighted sum over decorated
Dyck paths.


title: LTE in Unlicensed Bands is neither Friend nor Foe to Wi-Fi

abstract:
  Proponents of deploying LTE in the 5 GHz band for providing additional
cellular network capacity have claimed that LTE would be a better neighbour to
Wi-Fi in the unlicensed band, than Wi-Fi is to itself. On the other side of the
debate, the Wi-Fi community has objected that LTE would be highly detrimental
to Wi-Fi network performance. However, there is a lack of transparent and
systematic engineering evidence supporting the contradicting claims of the two
camps, which is essential for ascertaining whether regulatory intervention is
in fact required to protect the Wi-Fi incumbent from the new LTE entrant. To
this end, we present a comprehensive coexistence study of Wi-Fi and
LTE-in-unlicensed, surveying a large parameter space of coexistence mechanisms
and a range of representative network densities and deployment scenarios. Our
results show that, typically, harmonious coexistence between Wi-Fi and LTE is
ensured by the large number of 5 GHz channels. For the worst-case scenario of
forced co-channel operation, LTE is sometimes a better neighbour to Wi-Fi -
when effective node density is low - but sometimes worse - when density is
high. We find that distributed interference coordination is only necessary to
prevent a "tragedy of the commons" in regimes where interference is very
likely. We also show that in practice it does not make a difference to the
incumbent what kind of coexistence mechanism is added to LTE-in-unlicensed, as
long as one is in place. We therefore conclude that LTE is neither friend nor
foe to Wi-Fi in the unlicensed bands in general. We submit that the systematic
engineering analysis exemplified by our case study is a best-practice approach
for supporting evidence-based rulemaking by the regulator.


title: WaveNet: A Generative Model for Raw Audio

abstract:
  This paper introduces WaveNet, a deep neural network for generating raw audio
waveforms. The model is fully probabilistic and autoregressive, with the
predictive distribution for each audio sample conditioned on all previous ones;
nonetheless we show that it can be efficiently trained on data with tens of
thousands of samples per second of audio. When applied to text-to-speech, it
yields state-of-the-art performance, with human listeners rating it as
significantly more natural sounding than the best parametric and concatenative
systems for both English and Mandarin. A single WaveNet can capture the
characteristics of many different speakers with equal fidelity, and can switch
between them by conditioning on the speaker identity. When trained to model
music, we find that it generates novel and often highly realistic musical
fragments. We also show that it can be employed as a discriminative model,
returning promising results for phoneme recognition.


title:
Hyperspectral Unmixing with Endmember Variability using Partial
  Membership Latent Dirichlet Allocation

abstract:
  The application of Partial Membership Latent Dirichlet Allocation(PM-LDA) for
hyperspectral endmember estimation and spectral unmixing is presented. PM-LDA
provides a model for a hyperspectral image analysis that accounts for spectral
variability and incorporates spatial information through the use of
superpixel-based 'documents.' In our application of PM-LDA, we employ the
Normal Compositional Model in which endmembers are represented as Normal
distributions to account for spectral variability and proportion vectors are
modeled as random variables governed by a Dirichlet distribution. The use of
the Dirichlet distribution enforces positivity and sum-to-one constraints on
the proportion values. Algorithm results on real hyperspectral data indicate
that PM-LDA produces endmember distributions that represent the ground truth
classes and their associated variability.


title: Tensor diagrams and Chebyshev polynomials

abstract:
  In this paper, we describe a class of elements in the ring of
$\mathrm{SL}(V)$-invariant polynomial functions on the space of configurations
of vectors and linear forms of a 3-dimensional vector space $V.$ These elements
are related to one another by an induction formula using Chebyshev polynomials.
We also investigate the relation between these polynomials and G. Lusztig's
dual canonical basis in tensor products of representations of
$U_q(\mathfrak{sl}_3(\mathbb C)).$


title: On open and closed convex codes

abstract:
  Neural codes serve as a language for neurons in the brain. Convex codes,
which arise from the pattern of intersections of convex sets in Euclidean
space, are of particular relevance to neuroscience. Not every code is convex,
however, and the combinatorial properties of a code that determine its
convexity are still poorly understood. Here we find that a code that can be
realized by a collection of open convex sets may or may not be realizable by
closed convex sets, and vice versa, establishing that open convex and closed
convex codes are distinct classes. We also prove that max intersection-complete
codes (i.e. codes that contain all intersections of maximal codewords) are both
open convex and closed convex, and provide an upper bound for their minimal
embedding dimension. Finally, we show that the addition of non-maximal
codewords to an open convex code preserves convexity.


title: DOA estimation in structured phase-noisy environments: technical report

abstract:
  In this paper we focus on the problem of estimating the directions of arrival
(DOA) of a set of incident plane waves. Unlike many previous works, which
assume that the received observations are only affected by additive noise, we
consider the setup where some phase noise also corrupts the data (as for
example observed in atmospheric sound propagation or underwater acoustics). We
propose a new methodology to solve this problem in a Bayesian framework by
resorting to a variational mean-field approximation. Our simulation results
illustrate the benefits of carefully accounting for the phase noise in the DOA
estimation process.


title: $M(x)=o(x)$ Estimates for Beurling numbers

abstract:
  In classical prime number theory there are several asymptotic formulas said
to be "equivalent" to the PNT. One is the bound $M(x) = o(x)$ for the sum
function of the Moebius function. For Beurling generalized numbers, this
estimate is not an unconditional consequence of the PNT. Here we give two
conditions that yield the Beurling version of the $M(x)$ bound, and examples
illustrating failures when these conditions are not satisfied.


title: Families of Plausible Solutions to the Puzzle of Boyajian's Star

abstract:
  Good explanations for the unusual light curve of Boyajian's Star have been
hard to find. Recent results by Montet & Simon lend strength and plausibility
to the conclusion of Schaefer that in addition to short-term dimmings, the star
also experiences large, secular decreases in brightness on decadal timescales.
This, combined with a lack of long-wavelength excess in the star's spectral
energy distribution, strongly constrains scenarios involving circumstellar
material, including hypotheses invoking a spherical cloud of artifacts. We show
that the timings of the deepest dimmings appear consistent with being randomly
distributed, and that the star's reddening and narrow sodium absorption is
consistent with the total, long-term dimming observed. Following Montet &
Simon's encouragement to generate alternative hypotheses, we attempt to
circumscribe the space of possible explanations with a range of plausibilities,
including: a cloud in the outer solar system, structure in the ISM, natural and
artificial material orbiting Boyajian's Star, an intervening object with a
large disk, and variations in Boyajian's Star itself. We find the ISM and
intervening disk models more plausible than the other natural models.


title: The Elliptic Hall algebra and the deformed Khovanov Heisenberg category

abstract:
  We give an explicit description of the trace, or Hochschild homology, of the
quantum Heisenberg category defined by Licata and Savage. We also show that as
an algebra, it is isomorphic to "half" of a central extension of the elliptic
Hall algebra of Burban and Schiffmann, specialized at $\sigma = \bar\sigma^{-1}
= q$. A key step in the proof may be of independent interest: we show that the
sum (over $n$) of the Hochschild homologies of the positive affine Hecke
algebras $\mathrm{AH}_n^+$ is again an algebra, and that this algebra injects
into both the elliptic Hall algebra and the trace of the $q$-Heisenberg
category. Finally, we show that a natural action of the trace algebra on the
space of symmetric functions agrees with the specialization of an action
constructed by Schiffmann and Vasserot using Hilbert schemes.


title: Kohnert tableaux and a lifting of quasi-Schur functions

abstract:
  We introduce the quasi-key basis of the polynomial ring. We prove this basis
contains the quasi-Schur polynomials of of Haglund, Luoto, Mason and van
Willigenburg and that stable limits of quasi-key polynomials are quasi-Schur
functions, thus giving a lifting of the quasi-Schur basis of quasisymmetric
polynomials to the full polynomial ring. We introduce the combinatorial model
of Kohnert tableaux, and use this model to prove that key polynomials expand
positively in quasi-key polynomials which in turn expand positively in the
fundamental slide polynomials introduced earlier by the authors. We give simple
combinatorial formulas for these expansions in terms of Kohnert tableaux,
lifting the parallel expansions of a Schur function into quasi-Schur functions
into fundamental quasisymmetric functions. We further utilize Kohnert tableaux
to find the precise point at which the fundamental slide expansion of a key
polynomial stabilizes.


title:
Likelihood-free stochastic approximation EM for inference in complex
  models

abstract:
  A maximum likelihood methodology for the parameters of models with an
intractable likelihood is introduced. We produce a likelihood-free version of
the stochastic approximation expectation-maximization (SAEM) algorithm to
maximize the likelihood function of model parameters. While SAEM is best suited
for models having a tractable "complete likelihood" function, its application
to moderately complex models is a difficult or even impossible task. We show
how to construct a likelihood-free version of SAEM by using the "synthetic
likelihood" paradigm. Our method is completely plug-and-play, requires almost
no tuning and can be applied to both static and dynamic models. Four simulation
studies illustrate the method, including a stochastic differential equation
model, a stochastic Lotka-Volterra model and data from $g$-and-$k$
distributions. MATLAB code is available as supplementary material.


title:
Impact of axisymmetric mass models for dwarf spheroidal galaxies on
  indirect dark matter searches

abstract:
  Dwarf spheroidals are low-luminosity satellite galaxies of the Milky Way
highly dominated by dark matter (DM). Therefore, they are prime targets to
search for signals from dark matter annihilation using gamma-ray observations.
While the typical assumption is that the dark matter density profile of these
satellite galaxies can be described by a spherical symmetric
Navarro-Frenk-White (NFW) profile, recent observational data of stellar
kinematics suggest that the DM halos around these galaxies are better described
by axisymmetric profiles. Motivated by such evidence, we analyse about seven
years of PASS8 Fermi data for seven classical dwarf galaxies, including Draco,
adopting both the widely used NFW profile and observationally-motivated
axisymmetric density profiles. For four of the selected dwarfs (Sextans,
Carina, Sculptor and Fornax) axisymmetric mass models suggest a cored density
profile rather than the commonly adopted cusped profile. We found that upper
limits on the annihilation cross section for some of these dwarfs are
significantly higher than the ones achieved using an NFW profile. Therefore,
upper limits in the literature obtained using spherical symmetric cusped
profiles, such as the NFW, might be overestimated. Our results show that it is
extremely important to use observationally motivated density profiles going
beyond the usually adopted NFW in order to obtain accurate constraints on the
dark matter annihilation cross section.


title:
Exploiting Receptors Competition to Enhance Nanoparticles Binding
  Selectivity

abstract:
  Nanoparticles functionalized with multiple ligands can be programmed to bind
biological targets depending on the receptors they express, providing a general
mechanism exploited in various technologies, from selective drug-delivery to
biosensing. For binding to be highly selective, ligands should exclusively
interact with specific targeted receptors, because formation of bonds with
other, untargeted ones would lead to non-specific binding and potentially
harmful behaviour. This poses a particular problem for multivalent
nanoparticles, because even very weak bonds can collectively lead to strong
binding. A statistical mechanical model is used here to describe how
competition between different receptors together with multivalent effects can
be harnessed to design ligand-functionalized nanoparticles insensitive to the
presence of untargeted receptors, are insensitive to these problems, preventing
non-specific binding.


title: Basic models and questions in statistical network analysis

abstract:
  Extracting information from large graphs has become an important statistical
problem since network data is now common in various fields. In this minicourse
we will investigate the most natural statistical questions for three canonical
probabilistic models of networks: (i) community detection in the stochastic
block model, (ii) finding the embedding of a random geometric graph, and (iii)
finding the original vertex in a preferential attachment tree. Along the way we
will cover many interesting topics in probability theory such as P\'olya urns,
large deviation theory, concentration of measure in high dimension, entropic
central limit theorems, and more.

categories: math.ST cs.IT cs.SI math.IT math.PR stat.TH


title: Open Sets of Exponentially Mixing Anosov Flows

abstract:
  We prove that an Anosov flow with $\mathcal{C}^{1}$ stable bundle mixes
exponentially whenever the stable and unstable bundles are not jointly
integrable. This allows us to show that if a flow is sufficiently close to a
volume-preserving Anosov flow and $\operatorname{dim} \mathbb{E}_s = 1$,
$\operatorname{dim} \mathbb{E}_u \geq 2$ then the flow mixes exponentially
whenever the stable and unstable bundles are not jointly integrable.This
implies the existence of non-empty open sets of exponentially mixing Anosov
flows. As part of the proof of this result we show that $\mathcal{C}^{1+}$
uniformly-expanding suspension semiflows (in any dimension) mix exponentially
when the return time in not cohomologous to a piecewise constant.


title:
Characterization of CdTe Sensors with Schottky Contacts Coupled to
  Charge-Integrating Pixel Array Detectors for X-Ray Science

abstract:
  Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded
pixel-by-pixel to an underlying readout chip. This approach allows both the
sensor and the custom pixel electronics to be tailored independently to best
match the x-ray imaging requirements. Here we present characterizations of CdTe
sensors hybridized with two different charge-integrating readout chips, the
Keck PAD and the Mixed-Mode PAD (MM-PAD), both developed previously in our
laboratory. The charge-integrating architecture of each of these PADs extends
the instantaneous counting rate by many orders of magnitude beyond that
obtainable with photon counting architectures. The Keck PAD chip consists of
rapid, 8-frame, in-pixel storage elements with framing periods $<$150 ns. The
second detector, the MM-PAD, has an extended dynamic range by utilizing an
in-pixel overflow counter coupled with charge removal circuitry activated at
each overflow. This allows the recording of signals from the single-photon
level to tens of millions of x-rays/pixel/frame while framing at 1 kHz. Both
detector chips consist of a 128$\times$128 pixel array with (150 $\mu$m)$^2$
pixels.


title: H\"older-Besov boundedness for periodic pseudo-differential operators

abstract:
  In this work we give H\"older-Besov estimates for periodic Fourier
multipliers. We present a class of bounded pseudo-differential operators on
periodic Besov spaces with symbols of limited regularity.


title:
Frustrated Magnetism and Caloric Effects in Mn-antiperovskite Nitrides:
  $Ab~Initio$ Theory

abstract:
  We model changes of magnetic ordering in Mn-antiperovskite nitrides driven by
biaxial lattice strain at zero and at finite temperature. We employ a
non-collinear spin-polarised density functional theory to compare the response
of the geometrically frustrated exchange interactions to a tetragonal symmetry
breaking (the so called piezomagnetic effect) across a range of Mn$_3$AN (A =
Rh, Pd, Ag, Co, Ni, Zn, Ga, In, Sn) at zero temperature. Building on the
robustness of the effect we focus on Mn$_3$GaN and extend our study to finite
temperature using the disordered local moment (DLM) first-principles electronic
structure theory to model the interplay between the ordering of Mn magnetic
moments and itinerant electron states. We discover a rich temperature-strain
magnetic phase diagram with two previously unreported phases stabilised by
strains larger than 0.75\% and with transition temperatures strongly dependent
on strain. We propose an elastocaloric cooling cycle crossing two of the
available phase transitions to achieve simultaneously a large isothermal
entropy change (due to the first order transition) and a large adiabatic
temperature change (due to the second order transition).


title:
Evolution of clusters in energetic heavy ion bombarded amorphous
  graphite-III: Photo-emission and velocity analysis of sputtered carbon
  clusters

abstract:
  Diagnostics of the carbon atoms, ions, and clusters sputtered from a graphite
surface under 10 keV Xe ion bombardments reveals the presence of neutral carbon
clusters and positively charged species in the photo-emission spectra. The
observed absence of the positively charged clusters in the mass spectra by a
velocity analyzer is supplemented by the presence of the negatively charged
monatomic, diatomic, triatomic and quatratomic clusters.. The velocity spectra
are dominated by the negative C1, C2, C3 and C4. The latter two are observed
having much reduced peak intensities . These results may help us to understand
the contribution of neutral and charged species in the heavy-ion sputtering of
graphite and the energetics of soot formation. Xe is chosen being the heaviest
noble gas ion irradiating at not too high energy i.e 10 keV.


title: Learning Physics by Creating Problems: An Experiment

abstract:
  We investigated the effects of student-generated problems on exams. The
process was gradual with some training throughout the semester. Initial results
were highly positive with the students involved performing significantly
better, and showing statistically significant improvement (t = 5.04) compared
to the rest of the class, on average. Overall, performance improved when
students generated problems. Motivation was a limiting factor. There is
significant potential for improving student learning of physics and other
problem-based topics.


title:
Evolution of clusters in energetic heavy ion bombarded amorphous
  graphite-III: Energy spectra of charged clusters recoiling from Xe+
  irradiations

abstract:
  We report on a novel technique of heavy ion induced surface modification and
clustering mechanisms in amorphous graphite using Direct Recoil Spectrometry.
The charged clusters emanating as Direct Recoils from 50-150 keV Xe+ irradiated
graphite surface are detected in successive energy spectra at large recoil
angles. Ion beams irradiated surface is shown to provide an environment of
sputtered carbon atoms and clusters. The clustering occurs on the surface where
the most stable ones accumulate. The spectra have identified clustering
mechanisms operating in amorphous graphite under high fluence irradiations at
grazing incidence that are related to the reconstructed surface features. Heavy
ion irradiation induces the twin effects of producing a wide range of clusters
and simultaneously ejecting these as DRs.


title:
Optimal Encoding and Decoding for Point Process Observations: an
  Approximate Closed-Form Filter

abstract:
  The process of dynamic state estimation (filtering) based on point process
observations is in general intractable. Numerical sampling techniques are often
practically useful, but lead to limited conceptual insight about optimal
encoding/decoding strategies, which are of significant relevance to
Computational Neuroscience. We develop an analytically tractable Bayesian
approximation to optimal filtering based on point process observations, which
allows us to introduce distributional assumptions about sensor properties, that
greatly facilitate the analysis of optimal encoding in situations deviating
from common assumptions of uniform coding. Numerical comparison with particle
filtering demonstrate the quality of the approximation. The analytic framework
leads to insights which are difficult to obtain from numerical algorithms, and
is consistent with biological observations about the distribution of sensory
cells' tuning curve centers.


title: VVV High proper motion stars I. The catalogue of bright Ks < 13.5 stars

abstract:
  Knowledge of the stellar content near the Sun is important for a broad range
of topics ranging from the search for planets to the study of Milky Way
structure. The most powerful method for identifying potentially nearby stars is
proper motion (PM) surveys. All old optical surveys avoid, or are at least
substantially incomplete, near the Galactic plane. The depth and breadth of the
"Vista Variables in Via Lactea" (VVV) near-IR survey significantly improves
this situation. Taking advantage of the VVV survey database, we have measured
PMs in the densest regions of the MW bulge and southern plane in order to
complete the census of nearby objects. We have developed a custom PM pipeline
based on VVV catalogues from the Cambridge Astronomy Survey Unit (CASU), by
comparing the first epoch of JHKs with the multi-epoch Ks-bands acquired later.
Taking advantage of the large time baseline between the 2MASS and the VVV
observations, we also obtained 2MASS-VVV PMs. We present a near-IR proper
motion catalogue for the whole area of the VVV survey, which includes 3003
moving stellar sources. All of these have been visually inspected and are real
PM objects. Our catalogue is in very good agreement with the proper motion data
supplied in IR catalogues outside the densest zone of the MW. The majority of
the PM objects in our catalogue are nearby M-dwarfs, as expected. This new
database allow us to identify 57 common proper motion binary candidates, among
which are two new systems within ~30pc of the Sun.


title: Charge Order in NbSe$_2$

abstract:
  We develop in detail a model of the charge order in NbSe$_2$ deriving from a
strong electron-phonon coupling dependent on the ingoing and outgoing electron
momenta as well as the electronic orbitals scattered between. Including both
dependencies allows us to reproduce the full range of available experimental
observations on this material. The stability of both experimentally-observed
charge-ordered geometries (1Q and 3Q) is studied within this model as a
function of temperature and uniaxial strain. It is found that a small amount of
bulk strain suffices to stabilize the unidirectional order, and that in both
ordering geometries, lattice fluctuations arising from the strong
electron-phonon coupling act to suppress the onset temperature of charge order,
giving a pseudogap regime characterized by local order and strong phase
fluctuations.


title:
The location, clustering, and propagation of massive star formation in
  giant molecular clouds

abstract:
  Massive stars are key players in the evolution of galaxies, yet their
formation pathway remains unclear. In this work, we use data from several
galaxy-wide surveys to build an unbiased dataset of ~700 massive young stellar
objects (MYSOs), ~200 giant molecular clouds (GMCs), and ~100 young (<10 Myr)
optical stellar clusters (SCs) in the Large Magellanic Cloud. We employ this
data to quantitatively study the location and clustering of massive star
formation and its relation to the internal structure of GMCs. We reveal that
massive stars do not typically form at the highest column densities nor centers
of their parent GMCs at the ~6 pc resolution of our observations. Massive star
formation clusters over multiple generations and on size scales much smaller
than the size of the parent GMC. We find that massive star formation is
significantly boosted in clouds near SCs. Yet, whether a cloud is associated
with a SC does not depend on either the cloud's mass or global surface density.
These results reveal a connection between different generations of massive
stars on timescales up to 10 Myr. We compare our work with Galactic studies and
discuss our findings in terms of GMC collapse, triggered star formation, and a
potential dichotomy between low- and high-mass star formation.


title: Is the spin connection confined or condensed?

abstract:
  The spin connection enters the theory of gravity as a nonabelian gauge field
associated with local Lorentz transformations. Normally it is eliminated from
making an extra assumption - that of the metricity of the vierbein field.
However, treated by itself with the usual gauge action, it has a negative beta
function, implying that it is asymptotically free. I suggest that the spin
connection could be confined (or perhaps partially confined) in the same way as
other nonabelian gauge fields. This would remove the need to make the extra
assumption of metricity, as the spin connection would not be present in the low
energy theory, leaving the symmetry to be realized only using metric variables.


title: A conformal model of gravitons

abstract:
  In the description of general covariance, the vierbein and the Lorentz
connection can be treated as independent fundamental fields. With the usual
gauge Lagrangian, the Lorentz connection is characterized by an asymptotically
free running coupling. When running from high energy, the coupling gets large
at a scale which can be called the Planck mass. If the Lorentz connection is
confined at that scale, the low energy theory can have the Einstein Lagrangian
induced at low energy through dimensional transmutation. However, in general
there will be new divergences in such a theory and the Lagrangian basis should
be expanded. I construct a conformally invariant model with a larger basis size
which potentially may have the same property.


title: Bogomolov multipliers of $p$-groups of maximal class

abstract:
  Let $G$ be a $p$-group of maximal class and order $p^n$. We determine whether
or not the Bogomolov multiplier $B_0(G)$ is trivial in terms of the lower
central series of $G$ and $P_1 = C_G(\gamma_2(G) / \gamma_4(G))$. If in
addition $G$ has positive degree of commutativity and $P_1$ is metabelian, we
show how understanding $B_0(G)$ reduces to the simpler commutator structure of
$P_1$. This result covers all $p$-groups of maximal class of large enough order
and, furthermore, it allows us to give the first natural family of $p$-groups
containing an abundance of groups with nontrivial Bogomolov multipliers. We
also provide more general results on Bogomolov multipliers of $p$-groups of
arbitrary coclass $r$.


title: Evidence for a Conserved Quantity in Human Mobility

abstract:
  Recent seminal works on human mobility have shown that individuals constantly
exploit a small set of repeatedly visited locations. A concurrent literature
has emphasized the explorative nature of human behavior, showing that the
number of visited places grows steadily over time. How to reconcile these
seemingly contradicting facts remains an open question. Here, we analyze
high-resolution multi-year traces of $\sim$40,000 individuals from 4 datasets
and show that this tension vanishes when the long-term evolution of mobility
patterns is considered. We reveal that mobility patterns evolve significantly
yet smoothly, and that the number of familiar locations an individual visits at
any point is a conserved quantity with a typical size of $\sim$25 locations. We
use this finding to improve state-of-the-art modeling of human mobility.
Furthermore, shifting the attention from aggregated quantities to individual
behavior, we show that the size of an individual's set of preferred locations
correlates with the number of her social interactions. This result suggests a
connection between the conserved quantity we identify, which as we show can not
be understood purely on the basis of time constraints, and the `Dunbar number'
describing a cognitive upper limit to an individual's number of social
relations. We anticipate that our work will spark further research linking the
study of Human Mobility and the Cognitive and Behavioral Sciences.


title:
Fixed Point and Anomaly Mediation in Partially $N = 2$ Supersymmetric
  Standard Models

abstract:
  Motivated by the simple toroidal compactification of extra-dimensional SUSY
theories, we investigate on a partially $N=2$ supersymmetric (SUSY) extension
of the standard model which has an $N=2$ SUSY sector and an $N=1$ SUSY sector.
We point out that below the scale of the partially breaking of $N=2$ to $N=1$,
the ratio of Yukawa to gauge couplings embedded in the original $N=2$ gauge
interaction in the $N=2$ sector becomes greater due to a fixed point. Since at
the partially breaking scale the sfermion masses in the $N=2$ sector is
suppressed due to the $N=2$ non-renormalization theorem, the anomaly mediation
effect becomes important. If dominant, the anomaly induced masses for the
sfermions in the $N=2$ sector are almost UV-insensitive due to the fixed point.
Interestingly, these masses are always positive, i.e. no tachyonic slepton
problem. From an example model, we show interesting phenomena differing from
the ordinary MSSM. In particular, the dark matter can be a sbino, i.e. the
scalar component of the $N=2$ vector multiplet of $\rm U(1)_Y$. To obtain the
correct dark matter abundance, the mass of sbino, as well as the MSSM
sparticles in the $N=2$ sector which have a typical mass pattern of anomaly
mediation, is required to be small. Therefore, this scenario can be tested and
confirmed in the LHC and may be further confirmed by the measurement of the
$N=2$ Yukawa couplings in future colliders. This model can explain dark matter,
muon $g-2$ anomaly, gauge coupling unification and relaxes some ordinary
problems within the MSSM. Also, it is compatible with thermal leptogenesis.


title: The Microsoft 2016 Conversational Speech Recognition System

abstract:
  We describe Microsoft's conversational speech recognition system, in which we
combine recent developments in neural-network-based acoustic and language
modeling to advance the state of the art on the Switchboard recognition task.
Inspired by machine learning ensemble techniques, the system uses a range of
convolutional and recurrent neural networks. I-vector modeling and lattice-free
MMI training provide significant gains for all acoustic model architectures.
Language model rescoring with multiple forward and backward running RNNLMs, and
word posterior-based system combination provide a 20% boost. The best single
system uses a ResNet architecture acoustic model with RNNLM rescoring, and
achieves a word error rate of 6.9% on the NIST 2000 Switchboard task. The
combined system has an error rate of 6.2%, representing an improvement over
previously reported results on this benchmark task.


title:
Examining Representational Similarity in ConvNets and the Primate Visual
  Cortex

abstract:
  We compare several ConvNets with different depth and regularization
techniques with multi-unit macaque IT cortex recordings and assess the impact
of the same on representational similarity with the primate visual cortex. We
find that with increasing depth and validation performance, ConvNet features
are closer to cortical IT representations.


title: Neutrino energy reconstruction from one muon and one proton events

abstract:
  We propose a new method of selection of high purity charge current
quasielastic neutrino events with a good reconstruction of interacting neutrino
energy. Performance of the method was verified with several tests using GENIE,
NEUT and NuWro Monte Carlo events generators with carbon and argon targets. The
method can be useful in neutrino oscillation studies with a few GeV energy
beams.


title:
Performance of Large Area X-ray Proportional Counters in a Balloon
  Experiment

abstract:
  ASTROSAT is India's first satellite fully devoted to astronomical
observations covering a wide spectral band from optical to hard X-rays by a
complement of 4 co-aligned instruments and a Scanning Sky X-ray Monitor. One of
the instruments is Large Area X-ray Proportional Counter with 3 identical
detectors. In order to assess the performance of this instrument, a balloon
experiment with two prototype Large Area X-ray Proportional Counters (LAXPC)
was carried out on 2008 April 14. The design of these LAXPCs was similar to
those on the ASTROSAT except that their field of view (FOV) was 3$^{\circ}$
$\times$ 3$^{\circ}$ versus FOV of 1$^{\circ}$ $\times$ 1$^{\circ}$ for the
LAXPCs on the ASTROSAT. The LAXPCs are aimed at the timing and spectral studies
of X-ray sources in 3-80 keV region. In the balloon experiment, the LAXPC,
associated electronics and support systems were mounted on an oriented platform
which could be pre-programmed to track any source in the sky. A brief
description of the LAXPC design, laboratory tests, calibration and the detector
characteristics is presented here. The details of the experiment and background
counting rates of the 2 LAXPCs at the float altitude of about 41 km are
presented in different energy bands. The bright black hole X-ray binary Cygnus
X-1 (Cyg X-1) was observed in the experiment for $\sim$ 3 hours. Details of Cyg
X-1 observations, count rates measured from it in different energy intervals
and the intensity variations of Cyg X-1 detected during the observations are
presented and briefly discussed.


title: Fully-Trainable Deep Matching

abstract:
  Deep Matching (DM) is a popular high-quality method for quasi-dense image
matching. Despite its name, however, the original DM formulation does not yield
a deep neural network that can be trained end-to-end via backpropagation. In
this paper, we remove this limitation by rewriting the complete DM algorithm as
a convolutional neural network. This results in a novel deep architecture for
image matching that involves a number of new layer types and that, similar to
recent networks for image segmentation, has a U-topology. We demonstrate the
utility of the approach by improving the performance of DM by learning it
end-to-end on an image matching task.


title: Propagating q-field and q-ball solution

abstract:
  One possible solution of the cosmological constant problem involves a
so-called $q$-field, which self-adjusts so as to give a vanishing gravitating
vacuum energy density (cosmological constant) in equilibrium. We show that this
$q$-field can manifest itself in other ways. Specifically, we establish a
propagating mode ($q$-wave) in the nontrivial vacuum and find a particular
soliton-type solution in flat spacetime, which we call a $q$-ball by analogy
with the well-known $Q$-ball solution. Both $q$-waves and $q$-balls are
expected to play a role for the equilibration of the $q$-field in the very
early universe.


title:
Weighted Graph Theory Representation of Quantum Information Inspired by
  Lie Algebras

abstract:
  Borrowing ideas from the relation between simply laced Lie algebras and
Dynkin diagrams, a weighted graph theory representation of quantum information
is addressed. In this way, the density matrix of a quantum state can be
interpreted as a signless Laplacian matrix of an associated graph. Using
similarities with root systems of simply laced Lie algebras, one-qubit theory
is analyzed in some details and is found to be linked to a non-oriented
weighted graph having two vertices. Moreover, this one-qubit theory is
generalized to n-qubits. In this representation, quantum gates correspond to
graph weight operations preserving the probability condition. A speculation
from string theory, via D-brane quivers, is also given.


title:
Effects of individual attitudes and motion decisions in room evacuation
  models

abstract:
  In this work we present a model for the evacuation of pedestrians from an
enclosure considering a continuous space substrate and discrete time. We
analyze the influence of behavioral features that affect the use of the empty
space, that can be linked to the attitudes or characters of the pedestrians. We
study how the interaction of different behavioral profiles affects the needed
time to evacuate completely a room and the occurrence of clogging. We find that
neither fully egotistic nor fully cooperative attitudes are optimal from the
point of view of the crowd. In contrast, intermediate behaviors provide lower
evacuation times. This lead us to identify some phenomena closely analogous to
the {\em faster-is-slower} effect. The proposed model enables for the
introduction of Game Theory elements to solve conflicts between pedestrians
which try to occupy the same space. Moreover, it allows for distinguishing
between the role of the attitudes in the search for empty space and the
attitudes in the conflicts. In the present version we only focus on the first
of these instances.


title: A Multi-Scale Cascade Fully Convolutional Network Face Detector

abstract:
  Face detection is challenging as faces in images could be present at
arbitrary locations and in different scales. We propose a three-stage cascade
structure based on fully convolutional neural networks (FCNs). It first
proposes the approximate locations where the faces may be, then aims to find
the accurate location by zooming on to the faces. Each level of the FCN cascade
is a multi-scale fully-convolutional network, which generates scores at
different locations and in different scales. A score map is generated after
each FCN stage. Probable regions of face are selected and fed to the next
stage. The number of proposals is decreased after each level, and the areas of
regions are decreased to more precisely fit the face. Compared to passing
proposals directly between stages, passing probable regions can decrease the
number of proposals and reduce the cases where first stage doesn't propose good
bounding boxes. We show that by using FCN and score map, the FCN cascade face
detector can achieve strong performance on public datasets.


title:
Single-Peakedness and Total Unimodularity: New Polynomial-Time
  Algorithms for Multi-Winner Elections

abstract:
  The winner determination problems of many attractive multi-winner voting
rules are NP-complete. However, they often admit polynomial-time algorithms
when restricting inputs to be single-peaked. Commonly, such algorithms employ
dynamic programming along the underlying axis. We introduce a new technique:
carefully chosen integer linear programming (IP) formulations for certain
voting problems admit an LP relaxation which is totally unimodular if
preferences are single-peaked, and which thus admits an integral optimal
solution. This technique gives efficient algorithms for finding optimal
committees under Proportional Approval Voting (PAV) and the Chamberlin--Courant
rule with single-peaked preferences, as well as for certain OWA-based rules.
For PAV, this is the first technique able to efficiently find an optimal
committee when preferences are single-peaked. An advantage of our approach is
that no special-purpose algorithm needs to be used to exploit structure in the
input preferences: any standard IP solver will terminate in the first iteration
if the input is single-peaked, and will continue to work otherwise.


title: Stoner-type theory of Magnetism in Silicon MOSFETs

abstract:
  We consider quasi-two-dimensional gas of electrons in a typical Si-MOSFET,
assuming repulsive contact interaction between electrons. Magnetisation and
susceptibility are evaluated within the mean-field approach. Finite thickness
of the inversion layer results in an interaction-induced electron wave function
change, not found in both purely two-dimensional and three-dimensional (bulk)
cases. Taking this self-consistent change into account leads to an increased
susceptibility and ultimately to a ferromagnetic transition deep in the
high-density metallic regime. We further find that in the paramagnetic state,
magnetisation increases sublinearly with increasing in-plane magnetic field. In
the opposite limit of low carrier densities, the effects of long-range
interaction become important and can be included phenomenologically via
bandwidth renormalisation. Our treatment then suggests that with decreasing
density, the metal-insulator transition is preceded by a ferromagnetic
instability. Results are discussed in the context of the available experimental
data, and arguments for the validity of our mean-field scheme are presented.


title:
Observation of electronic bound states in charge-ordered
  YBa$_2$Cu$_3$O$_y$

abstract:
  Observing how electronic states in solids react to a local symmetry breaking
provides insight into their microscopic nature. A striking example is the
formation of bound states when quasiparticles are scattered off defects. This
is known to occur, under specific circumstances, in some metals and
superconductors but not, in general, in the charge-density-wave (CDW) state.
Here, we report the unforeseen observation of bound states when a magnetic
field quenches superconductivity and induces long-range CDW order in
YBa$_2$Cu$_3$O$_y$. Bound states indeed produce an inhomogeneous pattern of the
local density of states $N(E_F)$ that leads to a skewed distribution of Knight
shifts which is detected here through an asymmetric profile of $^{17}$O NMR
lines. We argue that the effect arises most likely from scattering off defects
in the CDW state, which provides a novel case of disorder-induced bound states
in a condensed-matter system and an insightful window into charge ordering in
the cuprates.


title: ZaliQL: A SQL-Based Framework for Drawing Causal Inference from Big Data

abstract:
  Causal inference from observational data is a subject of active research and
development in statistics and computer science. Many toolkits have been
developed for this purpose that depends on statistical software. However, these
toolkits do not scale to large datasets. In this paper we describe a suite of
techniques for expressing causal inference tasks from observational data in
SQL. This suite supports the state-of-the-art methods for causal inference and
run at scale within a database engine. In addition, we introduce several
optimization techniques that significantly speedup causal inference, both in
the online and offline setting. We evaluate the quality and performance of our
techniques by experiments of real datasets.


title:
Comment on "Why does deep and cheap learning work so well?"
  [arXiv:1608.08225]

abstract:
  In a recent paper, "Why does deep and cheap learning work so well?", Lin and
Tegmark claim to show that the mapping between deep belief networks and the
variational renormalization group derived in [arXiv:1410.3831] is invalid, and
present a "counterexample" that claims to show that this mapping does not hold.
In this comment, we show that these claims are incorrect and stem from a
misunderstanding of the variational RG procedure proposed by Kadanoff. We also
explain why the "counterexample" of Lin and Tegmark is compatible with the
mapping proposed in [arXiv:1410.3831].


title: HD 30963: a new HgMn star

abstract:
  Using high dispersion high quality spectra of HD 30963 obtained with the
echelle spectrograph SOPHIE at Observatoire de Haute Provence in November 2015,
we show that this star, hitherto classified as a B9 III superficially normal
star, is actually a new Chemically Peculiar star of the HgMn type. Spectrum
synthesis reveals large overabundances of Mn, Sr, Y, Zr , Pt and Hg and
pronounced underabundances of He and Ni which are characteristic of HgMn stars.
We therefore propose that this interesting object be reclassified as a B9 HgMn
star.


title: Logical Induction

abstract:
  We present a computable algorithm that assigns probabilities to every logical
statement in a given formal language, and refines those probabilities over
time. For instance, if the language is Peano arithmetic, it assigns
probabilities to all arithmetical statements, including claims about the twin
prime conjecture, the outputs of long-running computations, and its own
probabilities. We show that our algorithm, an instance of what we call a
logical inductor, satisfies a number of intuitive desiderata, including: (1) it
learns to predict patterns of truth and falsehood in logical statements, often
long before having the resources to evaluate the statements, so long as the
patterns can be written down in polynomial time; (2) it learns to use
appropriate statistical summaries to predict sequences of statements whose
truth values appear pseudorandom; and (3) it learns to have accurate beliefs
about its own current beliefs, in a manner that avoids the standard paradoxes
of self-reference. For example, if a given computer program only ever produces
outputs in a certain range, a logical inductor learns this fact in a timely
manner; and if late digits in the decimal expansion of $\pi$ are difficult to
predict, then a logical inductor learns to assign $\approx 10\%$ probability to
"the $n$th digit of $\pi$ is a 7" for large $n$. Logical inductors also learn
to trust their future beliefs more than their current beliefs, and their
beliefs are coherent in the limit (whenever $\phi \implies \psi$,
$\mathbb{P}_\infty(\phi) \le \mathbb{P}_\infty(\psi)$, and so on); and logical
inductors strictly dominate the universal semimeasure in the limit.
  These properties and many others all follow from a single logical induction
criterion, which is motivated by a series of stock trading analogies. Roughly
speaking, each logical sentence $\phi$ is associated with a stock that is worth
\$1 per share if [...]


title: Online Data Thinning via Multi-Subspace Tracking

abstract:
  In an era of ubiquitous large-scale streaming data, the availability of data
far exceeds the capacity of expert human analysts. In many settings, such data
is either discarded or stored unprocessed in datacenters. This paper proposes a
method of online data thinning, in which large-scale streaming datasets are
winnowed to preserve unique, anomalous, or salient elements for timely expert
analysis. At the heart of this proposed approach is an online anomaly detection
method based on dynamic, low-rank Gaussian mixture models. Specifically, the
high-dimensional covariances matrices associated with the Gaussian components
are associated with low-rank models. According to this model, most observations
lie near a union of subspaces. The low-rank modeling mitigates the curse of
dimensionality associated with anomaly detection for high-dimensional data, and
recent advances in subspace clustering and subspace tracking allow the proposed
method to adapt to dynamic environments. Furthermore, the proposed method
allows subsampling, is robust to missing data, and uses a mini-batch online
optimization approach. The resulting algorithms are scalable, efficient, and
are capable of operating in real time. Experiments on wide-area motion imagery
and e-mail databases illustrate the efficacy of the proposed approach.


title: Dilemma First Search for Effortless Optimization of NP-Hard Problems

abstract:
  To tackle the exponentiality associated with NP-hard problems, two paradigms
have been proposed. First, Branch & Bound, like Dynamic Programming, achieve
efficient exact inference but requires extensive information and analysis about
the problem at hand. Second, meta-heuristics are easier to implement but
comparatively inefficient. As a result, a number of problems have been left
unoptimized and plain greedy solutions are used. We introduce a theoretical
framework and propose a powerful yet simple search method called Dilemma First
Search (DFS). DFS exploits the decision heuristic needed for the greedy
solution for further optimization. DFS is useful when it is hard to design
efficient exact inference. We evaluate DFS on two problems: First, the Knapsack
problem, for which efficient algorithms exist, serves as a toy example. Second,
Decision Tree inference, where state-of-the-art algorithms rely on the greedy
or randomness-based solutions. We further show that decision trees benefit from
optimizations that are performed in a fraction of the iterations required by a
random-based search.


title: Testing the parton evolution with the use of two-body final states

abstract:
  We consider the production of $b\bar b$ quarks and Drell-Yan lepton pairs at
LHC conditions focusing attention on the total transverse momentum of the
produced pair and on the azimuthal angle between the momenta of the outgoing
particles. Plotting the corresponding distributions in bins of the final state
invariant mass, one can reconstruct the full map of the transverse momentum
dependent parton densities in a proton. We give examples of how can these
distributions can look like at the LHC energies.


title: Bounds on Separating Redundancy of Linear Codes and Rates of X-Codes

abstract:
  An error-erasure channel is a simple noise model that introduces both errors
and erasures. While the two types of errors can be corrected simultaneously
with error-correcting codes, it is also known that any linear code allows for
first correcting errors and then erasures in two-step decoding. In particular,
a carefully designed parity-check matrix not only allows for separating
erasures from errors but also makes it possible to efficiently correct
erasures. The separating redundancy of a linear code is the number of
parity-check equations in a smallest parity-check matrix that has the required
property for this error-erasure separation. In a sense, it is a parameter of a
linear code that represents the minimum overhead for efficiently separating
erasures from errors. While several bounds on separating redundancy are known,
there still remains a wide gap between upper and lower bounds except for a few
limited cases. In this paper, using probabilistic combinatorics and design
theory, we improve both upper and lower bounds on separating redundancy. We
also show a relation between parity-check matrices for error-erasure separation
and special matrices, called X-codes, for data compaction circuits in VLSI
testing. This leads to an exponentially improved bound on the size of an
optimal X-code.


title: Uniqueness of the Representation in Homogeneous Isotropic LQC

abstract:
  We show that the standard representation of homogeneous isotropic loop
quantum cosmology (LQC) is the GNS-representation that corresponds to the
unique state on the reduced quantum holonomy-flux $^*$-algebra that is
invariant under residual diffeomorphisms $-$ both when the standard algebra is
used as well as when one uses the extended algebra proposed by Fleischhack.
More precisely, we find that in both situations the GNS-Hilbert spaces
coincide, and that in the Fleischhack case the additional algebra elements are
just mapped to zero operators. In order for the residual diffeomorphisms to
have a well-defined action on the quantum algebra, we have let them act on the
fiducial cell as well as on the dynamical variables, thereby recovering
covariance. Consistency with Ashtekar and Campiglia in the Bianchi I case is
also shown.


title:
A comodule-bialgebra structure for word-series substitution and mould
  composition

abstract:
  An internal coproduct is described, which is compatible with Hoffman's
quasi-shuffle product. Hoffman's quasi-shuffle Hopf algebra, with
deconcatenation coproduct, is a comodule-Hopf algebra over the bialgebra thus
defined. The relation with J. Ecalle's mould calculus, i.e. mould composition
and contracting arborification, is precised.


title: Mathematical Study of Scattering Resonances

abstract:
  We provide an introduction to mathematical theory of scattering resonances
and survey some recent results.


title:
New LUX and PandaX-II Results Illuminating the Simplest Higgs-Portal
  Dark Matter Models

abstract:
  Direct searches for dark matter (DM) by the LUX and PandaX-II Collaborations
employing xenon-based detectors have recently come up with the most stringent
limits to date on the spin-independent elastic scattering of DM off nucleons.
For Higgs-portal scalar DM models, the new results have precluded any
possibility of accommodating low-mass DM as suggested by the DAMA and CDMS II
Si experiments utilizing other target materials, even after invoking
isospin-violating DM interactions with nucleons. In the simplest model, SM+D,
which is the standard model plus a real singlet scalar named darkon acting as
the DM candidate, the LUX and PandaX-II limits rule out DM masses roughly from
4 to 450 GeV, except a small range around the resonance point at half of the
Higgs mass where the interaction cross-section is near the neutrino-background
floor. In the THDM II+D, which is the type-II two-Higgs-doublet model combined
with a darkon, the region excluded in the SM+D by the direct searches can be
recovered due to suppression of the DM effective interactions with nucleons at
some values of the ratios of Higgs couplings to the up and down quarks, making
the interactions significantly isospin-violating. However, in either model, if
the 125-GeV Higgs boson is the portal between the dark and SM sectors, DM
masses less than 50 GeV or so are already ruled out by the LHC constraint on
the Higgs invisible decay. In the THDM II+D, if the heavier $CP$-even Higgs
boson is the portal, theoretical restrictions from perturbativity, vacuum
stability, and unitarity requirements turn out to be important instead and
exclude much of the region below 100 GeV. For larger DM masses, the THDM II+D
has plentiful parameter space that corresponds to interaction cross-sections
under the neutrino-background floor and therefore is likely to be beyond the
reach of future direct searches without directional sensitivity.


title: Generative Visual Manipulation on the Natural Image Manifold

abstract:
  Realistic image manipulation is challenging because it requires modifying the
image appearance in a user-controlled way, while preserving the realism of the
result. Unless the user has considerable artistic skill, it is easy to "fall
off" the manifold of natural images while editing. In this paper, we propose to
learn the natural image manifold directly from data using a generative
adversarial neural network. We then define a class of image editing operations,
and constrain their output to lie on that learned manifold at all times. The
model automatically adjusts the output keeping all edits as realistic as
possible. All our manipulations are expressed in terms of constrained
optimization and are applied in near-real time. We evaluate our algorithm on
the task of realistic photo manipulation of shape and color. The presented
method can further be used for changing one image to look like the other, as
well as generating novel imagery from scratch based on user's scribbles.


title: Laser assisted tunneling in a Tonks-Girardeau gas

abstract:
  We investigate the applicability of laser assisted tunneling in a strongly
interacting one-dimensional Bose gas (the Tonks-Girardeau gas) in optical
lattices. We find that the stroboscopic dynamics of the Tonks-Girardeau gas in
a continuous Wannier-Stark-ladder potential, supplemented with laser assisted
tunneling, effectively realizes the ground state of one-dimensional hard-core
bosons in a discrete lattice with nontrivial hopping phases. We compare
observables that are affected by the interactions, such as the momentum
distribution, natural orbitals and their occupancies, in the time-dependent
continuous system, to those of the ground state of the discrete system.
Stroboscopically, we find an excellent agreement, indicating that laser
assisted tunneling is a viable technique for realizing novel ground states and
phases with hard-core one-dimensional Bose gases.


title:
The panchromatic view of the Magellanic Clouds from Classical Cepheids.
  I. Distance, Reddening and Geometry of the Large Magellanic Cloud disk

abstract:
  We present a detailed investigation of the Large Magellanic Cloud (LMC) disk
using classical Cepheids. Our analysis is based on optical (I,V; OGLE-IV),
near-infrared (NIR: J,H,Ks) and mid-infrared (MIR: w1; WISE) mean magnitudes.
By adopting new templates to estimate the NIR mean magnitudes from single-epoch
measurements, we build the currently most accurate, largest and homogeneous
multi-band dataset of LMC Cepheids. We determine Cepheid individual distances
using optical and NIR Period-Wesenheit relations (PWRs), to measure the
geometry of the LMC disk and its viewing angles. Cepheid distances based on
optical PWRs are precise at 3%, but accurate to 7, while the ones based on NIR
PWRs are more accurate (to 3%), but less precise (2%-15%), given the higher
photometric error on the observed magnitudes. We found an inclination i=25.05
$\pm$ 0.02 (stat.) $\pm$ 0.55 (syst.) deg, and a position angle of the lines of
nodes P.A.=150.76 $\pm$ 0.02(stat.) $\pm$ 0.07(syst.) deg. These values agree
well with estimates based either on young (Red Supergiants) or on
intermediate-age (Asymptotic Giant Branch, Red Clump) stellar tracers, but they
significantly differ from evaluations based on old (RR Lyrae) stellar tracers.
This indicates that young/intermediate and old stellar populations have
different spatial distributions. Finally, by using the reddening-law fitting
approach, we provide a reddening map of the LMC disk which is ten times more
accurate and two times larger than similar maps in the literature. We also
found an LMC true distance modulus of $\mu_{0,LMC}=18.48 \pm 0.10$ (stat. and
syst.) mag, in excellent agreement with the currently most accurate measurement
(Pietrzynski et al. 2013).


title:
Inverse source problem for wave equation and GPR data interpretation
  problem

abstract:
  The inverse problem of identifying the unknown spacewise dependent source
F(x) in 1D wave equation is considered. Measured data are taken in the form
g(t) := u(0; t). The relationship between that problem and Ground Penetrating
Radar (GRR) data interpretation problem is shown. The non-iterative algorithm
for reconstructing the unknown source F(x) is developed. The algorithm is based
on the Fourier expansion of the source F(x) and the explicit representation of
the direct problem solution via the function F(x). Then the minimization
problem for discrete form of the Tikhonov functional is reduced to the linear
algebraic system and solved numerically. Calculations show that the proposed
algorithm allows to reconstruct the spacewise dependent source F(x) with enough
accuracy for noise free and noisy data.


title: Hadwiger's conjecture: finite vs infinite graphs

abstract:
  We study some versions of the statement of Hadwiger's conjecture for finite
as well as infinite graphs.


title:
Dynamics of test particles in the five-dimensional, charged, rotating
  EMCS spacetime

abstract:
  We derive the complete set of geodesic equations for massive and massless
test particles of a five-dimensional, charged, rotating black hole solution of
the Einstein-Maxwell-Chern-Simons field equations in five-dimensional minimal
gauged supergravity and present their analytical solutions in terms of
Weierstra{\ss}' elliptic functions. We study the polar and radial motion,
depending on the black hole and test particle parameters, and characterize the
test particle motion qualitatively by the means of effective potentials. We use
the analytical solutions in order to visualize the test particle motion by two-
and three-dimensional plots.


title:
Turbulence and Vorticity in Galaxy Clusters Generated by Structure
  Formation

abstract:
  Turbulence is a key ingredient for the evolution of the intracluster medium,
whose properties can be predicted with high resolution numerical simulations.
We present initial results on the generation of solenoidal and compressive
turbulence in the intracluster medium during the formation of a small-size
cluster using highly resolved, non-radiative cosmological simulations, with a
refined monitoring in time. In this first of a series of papers, we closely
look at one simulated cluster whose formation was distinguished by a merger
around $z \sim 0.3$. We separate laminar gas motions, turbulence and shocks
with dedicated filtering strategies and distinguish the solenoidal and
compressive components of the gas flows using Hodge-Helmholtz decomposition.
Solenoidal turbulence dominates the dissipation of turbulent motions ($\sim
95\%$) in the central cluster volume at all epochs. The dissipation via
compressive modes is found to be more important ($\sim 30 \%$ of the total)
only at large radii ($\geq 0.5 ~r_{\rm vir}$) and close to merger events. We
show that enstrophy (vorticity squared) is good proxy of solenoidal turbulence.
All terms ruling the evolution of enstrophy (i.e. baroclinic, compressive,
stretching and advective terms) are found to be significant, but in amounts
that vary with time and location. Two important trends for the growth of
enstrophy in our simulation are identified: first, enstrophy is continuously
accreted into the cluster from the outside, and most of that accreted enstrophy
is generated near the outer accretion shocks by baroclinic and compressive
processes. Second, in the cluster interior vortex stretching is dominant,
although the other terms also contribute substantially.


title:
Spatially resolved variations of the IMF mass normalisation in
  early-type galaxies as probed by molecular gas kinematics

abstract:
  We here present the first spatially-resolved study of the IMF in external
galaxies derived using a dynamical tracer of the mass-to-light ratio. We use
the kinematics of relaxed molecular gas discs in seven early-type galaxies
(ETGs) selected from the ATLAS3D survey to dynamically determine mass-to-light
ratio (M/L) gradients. These M/L gradients are not very strong in the inner
parts of these objects, and galaxies that do show variations are those with the
highest specific star formation rates. Stellar population parameters derived
from star formation histories are then used in order to estimate the stellar
initial mass function function (IMF) mismatch parameter, and shed light on its
variation within ETGs. Some of our target objects require a light IMF,
otherwise their stellar population masses would be greater than their dynamical
masses. In contrast, other systems seem to require heavier IMFs to explain
their gas kinematics. Our analysis again confirms that IMF variation seems to
be occurring within massive ETGs. We find good agreement between our IMF
normalisations derived using molecular gas kinematics and those derived using
other techniques. Despite this, we do not see find any correlation between the
IMF normalisation and galaxy dynamical properties or stellar population
parameters, either locally or globally. In the future larger studies which use
molecules as tracers of galaxy dynamics can be used to help us disentangle the
root cause of IMF variation.


title: Classical Holographic Codes

abstract:
  In this work, we introduce classical holographic codes. These can be
understood as concatenated probabilistic codes and can be represented as
networks uniformly covering hyperbolic space. In particular, classical
holographic codes can be interpreted as maps from bulk degrees of freedom to
boundary degrees of freedom. Interestingly, they are shown to exhibit features
similar to those expected from the AdS/CFT correspondence. Among these are a
version of the Ryu-Takayanagi formula and intriguing properties regarding bulk
reconstruction and boundary representations of bulk operations. We discuss the
relation of our findings with expectations from AdS/CFT and, in particular,
with recent results from quantum error correction.


title: Vacuum stability in an extended standard model with a leptoquark

abstract:
  We investigate the standard model (SM) with the extension of a charged scalar
having fractional electromagnetic charge of $-1/3$ unit and with lepton and
baryon number violating couplings at tree level. Without directly taking part
in the electro-weak (EW) symmetry breaking, this scalar can affect stability of
the EW vacuum via loop effects. The impact of such a scalar, i.e., a leptoquark
on the perturbativity of SM dimensionless couplings as well as on new physics
couplings has been studied at two-loop order. The vacuum stability of the Higgs
potential is checked using one-loop renormalization group (RG) improved
effective potential approach with two-loop beta function for all the couplings.
From the stability analysis various bounds are drawn on parameter space by
identifying the region corresponding to metastability and stability of the EW
vacuum. Later we also address the Higgs mass fine-tuning issue via Veltman
condition and the presence of such scalar increases the scale up to which the
theory can be considered as reasonably fine-tuned. All these constraints give a
very predictive parameter space for leptoquark couplings which can be tested at
present and future colliders. Especially, a leptoquark with mass
$\mathcal{O}\,$(TeV) can give rise to lepton-quark flavor violating signatures
via decaying into the $t\, \tau$ channel at tree level, which can be tested at
the LHC or future colliders.


title:
Observational Signatures of High-Redshift Quasars and Local Relics of
  Black Hole Seeds

abstract:
  Observational constraints on the birth and early evolution of massive black
holes (BHs) come from two extreme regimes. At high redshift, quasars signal the
rapid growth of billion-solar-mass BHs and indicate that these objects began
remarkably heavy and/or accreted mass at rates above the Eddington limit. At
low redshift, the smallest nuclear BHs known are found in dwarf galaxies and
provide the most concrete limits on the mass of BH seeds. Here we review
current observational work in these fields that together are critical for our
understanding of the origin of massive BHs in the Universe.


title:
Topological Magnon Insulator in NonCoplanar Kagom\'e Antiferromagnets:
  Supplemental Material of arXiv:1608.04561

abstract:
  Topological magnon insulators in insulating Kagom\'e ferromagnets have been
extensively studied in a series of papers. It has been established that
Dzyaloshinskii-Moriya interaction (DMI) is the key ingredient to observe a
nontrivial topological magnon with edge modes. However, insulating
antiferromagnets on the Kagom\'e lattice are frustrated systems considered as a
playground for studying quantum spin liquid physics. In these systems the DMI
can induce a coplanar but noncollinear magnetic orders with a $\mathbf{q}=0$
propagating wavevector. We show that topological magnon bands are absent in
this coplanar spin texture in sharp contrast to collinear ferromagnets with
DMI. Hence, geometrically frustrated Kagom\'e antiferromagnets can be deemed
topologically trivial. The presence of an out-of-plane magnetic field in these
frustrated magnets induces noncoplanar spin textures exhibiting a nonzero spin
scalar chirality. We show that the field-induced spin chirality provides
topological magnon bands in Kagom\'e antiferromagnets without the need of DMI
and survives in the chiral spin liquid phase of frustrated magnets. Possible
experimentally material includes iron jarosite KFe$_3$(OH)$_{6}$(SO$_{4}$)$_2$.


title: Current noise from a magnetic moment in a helical edge

abstract:
  We calculate the two-terminal current noise generated by a magnetic moment
coupled to a helical edge of a two-dimensional topological insulator. When the
system is symmetric with respect to in-plane spin rotation, the noise is
dominated by the Nyquist component even in the presence of a voltage bias $V$.
The corresponding noise spectrum $S(V,\omega)$ is determined by a modified
fluctuation-dissipation theorem with the differential conductance $G(V,\omega)$
in place of the linear one. The differential noise $\partial S/ \partial V$,
commonly measured in experiments, is strongly dependent on frequency on a small
scale $\tau_{K}^{-1}\ll T$ set by the Korringa relaxation rate of the local
moment. This is in stark contrast with the case of conventional mesoscopic
conductors where $\partial S/ \partial V$ is frequency-independent and defined
by the shot noise. In a helical edge, a violation of the spin-rotation symmetry
leads to the shot noise, which becomes important only at a high bias.
Uncharacteristically for a fermion system, this noise in the backscattered
current is super-Poissonian.


title:
On the Gravitational Wave Background from Black Hole Binaries after the
  First LIGO Detections

abstract:
  The detection of gravitational waves from the merger of binary black holes by
the LIGO Collaboration has opened a new window to astrophysics. With the
sensitivities of ground based detectors in the coming years we can only detect
the local black hole binary mergers. The integrated merger rate can instead be
probed by the gravitational-wave background, the incoherent superposition of
the released energy in gravitational waves during binary-black-hole
coalescence. Through that, the properties of the binary black holes can be
studied. In this work we show that by measuring the energy density
$\Omega_{GW}$ (in units of the cosmic critical density) of the
gravitational-wave background, we can search for the rare $\sim 100 M_{\odot}$
massive black holes formed in the Universe. In addition, we can answer how
often the least massive BHs of mass $> 3 M_{\odot}$ form. Finally, if there are
multiple channels for the formation of binary black holes and if any of them
predicts a narrow mass range for the black holes, then the
gravitational-wave-background spectrum may have features that with the future
Einstein Telescope can be detected.