title:
Determining the best attributes for surveillance video keywords
  generation

abstract:
  Automatic video keyword generation is one of the key ingredients in reducing
the burden of security officers in analyzing surveillance videos. Keywords or
attributes are generally chosen manually based on expert knowledge of
surveillance. Most existing works primarily aim at either supervised learning
approaches relying on extensive manual labelling or hierarchical probabilistic
models that assume the features are extracted using the bag-of-words approach;
thus limiting the utilization of the other features. To address this, we turn
our attention to automatic attribute discovery approaches. However, it is not
clear which automatic discovery approach can discover the most meaningful
attributes. Furthermore, little research has been done on how to compare and
choose the best automatic attribute discovery methods. In this paper, we
propose a novel approach, based on the shared structure exhibited amongst
meaningful attributes, that enables us to compare between different automatic
attribute discovery approaches.We then validate our approach by comparing
various attribute discovery methods such as PiCoDeS on two attribute datasets.
The evaluation shows that our approach is able to select the automatic
discovery approach that discovers the most meaningful attributes. We then
employ the best discovery approach to generate keywords for videos recorded
from a surveillance system. This work shows it is possible to massively reduce
the amount of manual work in generating video keywords without limiting
ourselves to a particular video feature descriptor.


title: Relaxation times and charge conductivity of silicene

abstract:
  We investigate the transport and single particle relaxation times of silicene
in the presence of neutral and charged impurities. The static charge
conductivity is studied using the semiclassical Boltzmann formalism when the
spin-orbit interaction is taken into account. The screening is modeled within
Thomas-Fermi and random phase approximations. We show that the transport
relaxation time is always longer than the single particle one. Easy electrical
controllability of both carrier density and band gap in this buckled
two-dimensional structure makes it a suitable candidate for several electronic
and optoelectronic applications. In particular, we observe that the dc charge
conductivity could be easily controlled through an external electric field, a
very promising feature for applications as electrical switches and transistors.
Our findings would be qualitatively valid for other buckled honeycomb lattices
of the same family, such as germanine and stanine.


title: A Survey of Semantic Segmentation

abstract:
  This survey gives an overview over different techniques used for pixel-level
semantic segmentation. Metrics and datasets for the evaluation of segmentation
algorithms and traditional approaches for segmentation such as unsupervised
methods, Decision Forests and SVMs are described and pointers to the relevant
papers are given. Recently published approaches with convolutional neural
networks are mentioned and typical problematic situations for segmentation
algorithms are examined. A taxonomy of segmentation algorithms is given.


title: Scrambling without chaos in RCFT

abstract:
  In this paper we investigate measures of chaos and entanglement in rational
conformal field theories in 1+1 dimensions. First, we derive a universal
formula for the late time value of the out-of-time-ordered correlators for this
class of theories. Our universal result can be expressed as a particular
combination of the modular S-matrix elements known as the anyon monodromy
scalar. Next, in the explicit setup of a $SU(N)_k$ Wess-Zumino-Witten model, we
compare the late time behavior of the out-of-time-ordered correlators and the
purity. Interestingly, in the large-c limit, the purity grows logarithmically
as in holographic theories; in contrast, the out-of-time-ordered correlators
remain, in general, non-vanishing.


title: Fractional Statistics and the Butterfly Effect

abstract:
  Fractional statistics and quantum chaos are both phenomena associated with
the non-local storage of quantum information. In this article, we point out a
connection between the butterfly effect in (1+1)-dimensional rational conformal
field theories and fractional statistics in (2+1)-dimensional topologically
ordered states. This connection comes from the characterization of the
butterfly effect by the out-of-time-order-correlator proposed recently. We show
that the late-time behavior of such correlators is determined by universal
properties of the rational conformal field theory such as the modular S-matrix
and conformal spins. Using the bulk-boundary correspondence between rational
conformal field theories and (2+1)-dimensional topologically ordered states, we
show that the late time behavior of out-of-time-order-correlators is
intrinsically connected with fractional statistics in the topological order. We
also propose a quantitative measure of chaos in a rational conformal field
theory, which turns out to be determined by the topological entanglement
entropy of the corresponding topological order.


title: Electronic Scattering Effects in Europium-Based Iron Pnictides

abstract:
  In a comprehensive study, we investigate the electronic scattering effects in
EuFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ by using Fourier-transform infrared
spectroscopy. In spite of the fact that Eu$^{2+}$ local moments order around
$T_\text{Eu} \approx 20$\,K, the overall optical response is strikingly similar
to the one of the well-known Ba-122 pnictides. The main difference lies within
the suppression of the lower spin-density-wave gap feature. By analysing our
spectra with a multi-component model, we find that the high-energy feature
around 0.7\,eV -- often associated with Hund's rule coupling -- is highly
sensitive to the spin-density-wave ordering, this further confirms its direct
relationship to the dynamics of itinerant carriers. The same model is also used
to investigate the in-plane anisotropy of magnetically detwinned
EuFe$_{2}$As$_{2}$ in the antiferromagnetically ordered state, yielding a
higher Drude weight and lower scattering rate along the crystallographic
$a$-axis. Finally, we analyse the development of the room temperature spectra
with isovalent phosphor substitution and highlight changes in the scattering
rate of hole-like carriers induced by a Lifshitz transition.


title: Approximate degeneracy of heavy-light mesons with the same $L$

abstract:
  Careful observation of the experimental spectra of heavy-light mesons tells
us that heavy-light mesons with the same angular momentum $L$ are almost
degenerate. The estimate is given how much this degeneracy is broken in our
relativistic potential model, and it is analytically shown that expectation
values of a commutator between the lowest order Hamiltonian and ${\vec L}^{~2}$
are of the order of $1/m_Q$ with a heavy quark mass $m_Q$. It turns out that
nonrelativistic approximation of heavy quark system has a rotational symmetry
and hence degeneracy among states with the same $L$. This feature can be tested
by measuring higher orbitally and radially excited heavy-light meson spectra
for $D/D_s/B/B_s$ in LHCb and forthcoming BelleII.


title:
Plethysm and cohomology representations of external and symmetric
  products

abstract:
  We prove refined generating series formulae for characters of (virtual)
cohomology representations of external products of suitable coefficients, e.g.,
(complexes of) constructible or coherent sheaves, or (complexes of) mixed Hodge
modules on spaces such as (possibly singular) complex quasi-projective
varieties. These formulae generalize our previous results for symmetric and
alternating powers of such coefficients, and apply also to other Schur
functors. The proofs of these results are reduced via an equivariant
K\"{u}nneth formula to a more general generating series identity for abstract
characters of tensor powers $\mathcal{V}^{\otimes n}$ of an element
$\mathcal{V}$ in a suitable symmetric monoidal category $A$. This abstract
approach applies directly also in the equivariant context for spaces with
additional symmetries (e.g., finite group actions, finite order automorphisms,
resp., endomorphisms), as well as for introducing an abstract plethysm calculus
for symmetric sequences of objects in $A$.


title:
Potential of mean force and transient states in polyelectrolyte
  complexation

abstract:
  The association between polyelectrolytes (PEs) of the same size but opposite
charge is systematically studied in terms of the potential of mean force (PMF)
along their center-of-mass reaction coordinate via coarse-grained,
implicit-solvent, explicit-salt computer simulations. The focus is set on the
onset and the intermediate, transient stages of complexation. At conditions
above the counterion-condensation threshold, the PE association process
exhibits a distinct sliding-rod-like behavior where the polymer chains approach
each other by first stretching out at a critical distance close to their
contour length, then 'shaking hand' and sliding along each other in a parallel
fashion, before eventually folding into a neutral complex. The essential part
of the PMF for highly charged PEs can be very well described by a simple theory
based on sliding charged `Debye--H\"uckel' rods with renormalized charges in
addition to an explicit entropy contribution owing to the release of condensed
counterions. Interestingly, at the onset of complex formation, the mean force
between the PE chains is found to be discontinuous, reflecting a bimodal
structural behavior that arises from the coexistence of interconnected-rod and
isolated-coil states. These two microstates of the PE complex are balanced by
subtle counterion release effects and separated by a free-energy barrier due to
unfavorable stretching entropy.


title:
Basic enumeration of graph compositions with a restricted number of
  components

abstract:
  The concept of graph compositions is related to several number theoretic
concepts, including partitions of positive integers and the cardinality of the
power set of finite sets. This paper examines graph compositions where the
total number of components is restricted and illustrates a connection between
graph compositions and Stirling numbers of the second kind.


title:
Chandra Observation of Abell 1142: A Cool-Core Cluster Lacking a Central
  Brightest Cluster Galaxy?

abstract:
  Abell~1142 is a low-mass galaxy cluster at low redshift containing two
comparable Brightest Cluster Galaxies (BCG) resembling a scaled-down version of
the Coma Cluster. Our Chandra analysis reveals an X-ray emission peak, roughly
100 kpc away from either BCG, which we identify as the cluster center. The
emission center manifests itself as a second beta-model surface brightness
component distinct from that of the cluster on larger scales. The center is
also substantially cooler and more metal rich than the surrounding intracluster
medium (ICM), which makes Abell 1142 appear to be a cool core cluster. The
redshift distribution of its member galaxies indicates that Abell 1142 may
contain two subclusters with each containing one BCG. The BCGs are merging at a
relative velocity of ~1200 km/s. This ongoing merger may have shock-heated the
ICM from ~ 2 keV to above 3 keV, which would explain the anomalous L_X--T_X
scaling relation for this system. This merger may have displaced the
metal-enriched "cool core" of either of the subclusters from the BCG. The
southern BCG consists of three individual galaxies residing within a radius of
5 kpc in projection. These galaxies should rapidly sink into the subcluster
center due to the dynamical friction of a cuspy cold dark matter halo.


title:
Semi-Markov Switching Vector Autoregressive Model-based Anomaly
  Detection in Aviation Systems

abstract:
  In this work we consider the problem of anomaly detection in heterogeneous,
multivariate, variable-length time series datasets. Our focus is on the
aviation safety domain, where data objects are flights and time series are
sensor readings and pilot switches. In this context the goal is to detect
anomalous flight segments, due to mechanical, environmental, or human factors
in order to identifying operationally significant events and provide insights
into the flight operations and highlight otherwise unavailable potential safety
risks and precursors to accidents. For this purpose, we propose a framework
which represents each flight using a semi-Markov switching vector
autoregressive (SMS-VAR) model. Detection of anomalies is then based on
measuring dissimilarities between the model's prediction and data observation.
The framework is scalable, due to the inherent parallel nature of most
computations, and can be used to perform online anomaly detection. Extensive
experimental results on simulated and real datasets illustrate that the
framework can detect various types of anomalies along with the key parameters
involved.


title:
Existence and regularity results for the inviscid primitive equations
  with lateral periodicity

abstract:
  The article is devoted to prove the existence and regularity of the solutions
of the $3D$ inviscid Linearized Primitive Equations (LPEs) in a channel with
lateral periodicity. This was assumed in a previous work \cite{HJT} which is
concerned with the boundary layers generated by the corresponding viscous
problem. Although the equations under investigation here are of hyperbolic
type, the standard methods do not apply because of the specificity of the
hyperbolic system. A set of \textit{non-local} boundary conditions for the
inviscid LPEs has to be imposed at the top and bottom of the channel making
thus the system well-posed.


title:
Diagrammatic Explanation of the Reverse Doppler Effect in Space-Time
  Modulated Photonic Crystals

abstract:
  An inverse Doppler shift occurs in a photonic crystal (PC) bounded by a
moving wall. The interpretation of this result has stirred some controversy. In
this paper, we address the problem using a diagrammatic approach. This visual
representation provides immediate insight into the phenomenon, and is a
powerful tool for the design of time-varying PCs.


title:
Cluster mean-field approach to the steady-state phase diagram of
  dissipative spin systems

abstract:
  We show that short-range correlations have a dramatic impact on the
steady-state phase diagram of quantum driven-dissipative systems. This effect,
never observed in equilibrium, follows from the fact that ordering in the
steady state is of dynamical origin, and is established only at very long
times, whereas in thermodynamic equilibrium it arises from the properties of
the (free) energy. To this end, by combining the cluster methods extensively
used in equilibrium phase transitions to quantum trajectories and
tensor-network techniques, we extend them to nonequilibrium phase transitions
in dissipative many-body systems. We analyze in detail a model of spin-1=2 on a
lattice interacting through an XYZ Hamiltonian, each of them coupled to an
independent environment that induces incoherent spin flips. In the steady-state
phase diagram derived from our cluster approach, the location of the phase
boundaries and even its topology radically change, introducing reentrance of
the paramagnetic phase as compared to the single-site mean field where
correlations are neglected. Furthermore, a stability analysis of the cluster
mean field indicates a susceptibility towards a possible incommensurate
ordering, not present if short-range correlations are ignored.


title:
Nonlinear electromagnetic formulation for particle simulation of lower
  hybrid waves in toroidal geometry

abstract:
  Electromagnetic particle simulation model has been formulated and verified
for nonlinear processes of lower hybrid (LH) waves in fusion plasmas. Electron
dynamics is described by the drift kinetic equation using either kinetic
momentum or canonical momentum. Ion dynamics is treated as the fluid system or
by the Vlasov equation. Compressible magnetic perturbation is retained to
simulate both the fast and slow LH waves. Numerical properties are greatly
improved by using electron continuity equation to enforce consistency between
electrostatic potential and vector potential, and by using the importance
sampling technique. The simulation model has been implemented in the
gyrokinetic toroidal code (GTC), and verified for the dispersion relation and
nonlinear particle trapping of the electromagnetic LH waves.


title: Conservation laws and symmetries in stochastic thermodynamics

abstract:
  Phenomenological nonequilibrium thermodynamics describes how fluxes of
conserved quantities such as matter, energy and charge flow from outer
reservoirs across a system, and how they irreversibly degrade from one form to
another. Stochastic thermodynamics is formulated in terms of probability fluxes
circulating in the system's configuration space. The consistency of the two
frameworks is granted by the condition of local detailed balance, which
specifies the amount of physical quantities exchanged with the reservoirs
during single transitions between configurations. We demonstrate that the
topology of the configuration space crucially determines the number of
independent thermodynamic affinities (forces) that the reservoirs generate
across the system, and provide a general algorithm that produces the
fundamental affinities and their conjugate currents contributing to the total
dissipation, based on the interplay between macroscopic conservations laws for
the currents and microscopic symmetries of the affinities.


title:
Scalar current of created pairs by Schwinger mechanism in de Sitter
  spacetime

abstract:
  We consider a charged scalar field in a $D$-dimensional de Sitter spacetime
and investigate pair creation by a Schwinger mechanism in a constant electric
field background. Using a semiclassical approximation the current of the
created pairs has been estimated. We find that the semiclassical current of the
created pairs in the strong electric field limit responds as $E^{\frac{D}{2}}$.
Going further but restricting to $D=3$ dimensional de Sitter spacetime, the
quantum expectation value of the spacelike component of the induced current has
been computed in the in-vacuum state by applying an adiabatic subtraction
scheme. We find that, in the strong electric field limit, the current responds
as $E^{\frac{3}{2}}$. In the weak electric field limit the current has a linear
response in $E$ and an inverse dependence on the mass of the scalar field. In
the case of a massless scalar field, the current varies with $E^{-1}$ which
leads to a phenomenon of infrared hyperconductivity. A new relation between
infrared hyperconductivity, tachyons, and conformality is discussed, and a
scheme to avoid an infrared hyperconductivity regime is proposed. In $D$
dimension, we eventually presented some first estimates of the backreaction of
the Schwinger pairs to the gravitational field, and we find a decrease of the
Hubble constant due to the pair creation.


title: Invisible QCD as Dark Energy

abstract:
  We account for the late time acceleration of the Universe by extending the
QCD color to a $SU(3)$ invisible sector (IQCD). If the Invisible Chiral
symmetry is broken in the early universe, a condensate of dark pions (dpions)
and dark gluons (dgluons) forms. The condensate naturally forms due to strong
dynamics similar to the Nambu--Jona-Lasinio mechanism. As the Universe evolves
from early times to present times the interaction energy between the dgluon and
dpion condensate dominates with a negative pressure equation of state and
causes late time acceleration. We conclude with a stability analysis of the
coupled perturbations of the dark pions and dark gluons.


title: Regularity of Maps between Sobolev Spaces

abstract:
  Let $F : H^q \to H^q$ be a $C^k$-map between Sobolev spaces, either on
$\mathbb R^d$ or on a compact manifold. We show that equivariance of $F$ under
the diffeomorphism group allows to trade regularity of $F$ as a nonlinear map
for regularity in the image space: for $0 \leq l \leq k$, the map $F: H^{q+l}
\to H^{q+l}$ is well-defined and of class $C^{k-l}$. This result is used to
study the regularity of the geodesic boundary value problem for Sobolev metrics
on the diffeomorphism group and the space of curves.


title:
SU(2) Gauge Theory with Two Fundamental Flavours: a Minimal Template for
  Model Building

abstract:
  We investigate the continuum spectrum of the SU(2) gauge theory with $N_f=2$
flavours of fermions in the fundamental representation. This model provides a
minimal template which is ideal for a wide class of Standard Model extensions
featuring novel strong dynamics that range from composite (Goldstone) Higgs
theories to several intriguing types of dark matter candidates, such as the
SIMPs. We improve our previous lattice analysis [1] by adding more data at
light quark masses, at two additional lattice spacings, by determining the
lattice cutoff via a Wilson flow measure of the $w_0$ parameter, and by
measuring the relevant renormalisation constants non-perturbatively in the
RI'-MOM scheme. Our results for the lightest isovector states in the vector and
axial channels, in units of the pseudoscalar decay constant, are
$m_V/F_{\rm{PS}}\sim 13.1(2.2)$ and $m_A/F_{\rm{PS}}\sim 14.5(3.6)$ (combining
statistical and systematic errors).
  In the context of the composite (Goldstone) Higgs models, our result for the
spin-one resonances are $m_V > 3.2(5)$ TeV and $m_A > 3.6(9)$ TeV, which are
above the current LHC constraints. In the context of dark matter models, for
the SIMP case our results indicate the occurrence of a compressed spectrum at
the required large dark pion mass, which implies the need to include the
effects of spin-one resonances in phenomenological estimates.


title: A short proof of Gr\"unbaum's Conjecture about affine invariant points

abstract:
  Let us denote by $\mathcal K_n$ the hyperspace of all convex bodies of
$\mathbb R^n$ equipped with the Hausdorff distance topology. An affine
invariant point $p$ is a continuous and Aff(n)-equivariant map $p:\mathcal
K_n\to \mathbb R^n$, where Aff(n) denotes the group of all nonsingular affine
maps of $\mathbb R^n$. For every $K\in\mathcal K_n$, let
$\mathfrak{P}_n(K)=\{p(K)\in\mathbb R^n\mid p\text{ is an affine invariant
point}\}$ and $\mathfrak{F}_n(K)=\{x\in\mathbb R^n\mid gx=x\text{ for every
}g\in Aff(n)\text{ such that }gK=K\}$. In 1963, B. Gr\"unbaum conjectured that
$\mathfrak{P}_n(K)=\mathfrak{F}_n(K)$ . After some partial results, the
conjecture was recently proven by O. Mordhorst. In this short note we give a
rather different, simpler and shorter proof of this conjecture, based merely on
the topology of the action of Aff(n) on $\mathcal K_n$.


title: Deep Learning in Finance

abstract:
  We explore the use of deep learning hierarchical models for problems in
financial prediction and classification. Financial prediction problems -- such
as those presented in designing and pricing securities, constructing
portfolios, and risk management -- often involve large data sets with complex
data interactions that currently are difficult or impossible to specify in a
full economic model. Applying deep learning methods to these problems can
produce more useful results than standard methods in finance. In particular,
deep learning can detect and exploit interactions in the data that are, at
least currently, invisible to any existing financial economic theory.


title: Nonlinear acousto-magneto-plasmonics

abstract:
  We review the recent progress in experimental and theoretical research of
interactions between the acoustic, magnetic and plasmonic transients in hybrid
metal-ferromagnet multilayer structures excited by ultrashort laser pulses. The
main focus is on understanding the nonlinear aspects of the acoustic dynamics
in materials as well as the peculiarities in the nonlinear optical and
magneto-optical response. For example, the nonlinear optical detection is
illustrated in details by probing the static magneto-optical second harmonic
generation in gold-cobalt-silver trilayer structures in Kretschmann geometry.
Furthermore, we show experimentally how the nonlinear reshaping of giant
ultrashort acoustic pulses propagating in gold can be quantified by
time-resolved plasmonic interferometry and how these ultrashort optical pulses
dynamically modulate the optical nonlinearities. The effective medium
approximation for the optical properties of hybrid multilayers facilitates the
understanding of novel optical detection techniques. In the discussion we
highlight recent works on the nonlinear magneto-elastic interactions, and
strain-induced effects in semiconductor quantum dots.


title: Dark Matter Search Results from the Commissioning Run of PandaX-II

abstract:
  We present the results of a search for WIMPs from the commissioning run of
the PandaX-II experiment located at the China Jinping underground Laboratory. A
WIMP search data set with an exposure of 306$\times$19.1 kg-day was taken,
while its dominant $^{85}$Kr background was used as the electron recoil
calibration. No WIMP candidates are identified, and a 90\% upper limit is set
on the spin-independent elastic WIMP-nucleon cross section with a lowest
excluded cross section of 2.97$\times$10$^{-45}$~cm$^2$ at a WIMP mass of
44.7~GeV/c$^2$.


title:
Automatic Building Extraction in Aerial Scenes Using Convolutional
  Networks

abstract:
  Automatic building extraction from aerial and satellite imagery is highly
challenging due to extremely large variations of building appearances. To
attack this problem, we design a convolutional network with a final stage that
integrates activations from multiple preceding stages for pixel-wise
prediction, and introduce the signed distance function of building boundaries
as the output representation, which has an enhanced representation power. We
leverage abundant building footprint data available from geographic information
systems (GIS) to compile training data. The trained network achieves superior
performance on datasets that are significantly larger and more complex than
those used in prior work, demonstrating that the proposed method provides a
promising and scalable solution for automating this labor-intensive task.


title:
Analytic properties and the asymptotic behavior of the area function of
  a Funk metric

abstract:
  In Minkowski geometry the unit ball is a compact convex body $K$ containing
the origin in its interior. The boundary of the body is formed by the unit
vectors. We also have a so-called Minkowski functional to measure the length of
vectors. By changing the origin in the interior of the body we have a smoothly
varying family of Minkowski functionals. This is called the Funk metric. Under
some regularity conditions the Minkowski functionals allow us to measure the
volume (area) of the indicatrix bodies (hypersurfaces). Some homogenity
properties provide the volume and the area to be proportional. The area as the
function of the base point varying in the interior of $K$ is strictly convex
[25]. This is called the area function of the Funk manifold. If the minimum is
attained at the origin then $K$ is said to be balanced. The idea comes from the
generalization of Brickell's theorem [6] for Finsler manifolds with balanced
indicatrices [25]. As a continuation of [25] we are going to investigate
analytic properties and the asymptotic behavior of the area function of a Funk
manifold. We prove that the area function is locally analytic and the area can
be arbitrary large near to the boundary of $K$. Therefore the minimum always
attained at a uniquely determined interior point of $K$. If we apply the result
to the indicatrices of a Finsler manifold point by point then the uniquely
defined minima of the area functions constitute a vector field. We prove that
it is differentiable. Therefore each indicatrix body can be translated in such
a way that the translated body is balanced and we always have an associated
Finsler manifold with balanced indicatrices. Finsler manifolds having balanced
indicatrices represent a class of Finsler spaces such that the so-called
Brickell's conjecture holds [6], see also [25].


title: Interactive Storytelling over Document Collections

abstract:
  Storytelling algorithms aim to 'connect the dots' between disparate documents
by linking starting and ending documents through a series of intermediate
documents. Existing storytelling algorithms are based on notions of coherence
and connectivity, and thus the primary way by which users can steer the story
construction is via design of suitable similarity functions. We present an
alternative approach to storytelling wherein the user can interactively and
iteratively provide 'must use' constraints to preferentially support the
construction of some stories over others. The three innovations in our approach
are distance measures based on (inferred) topic distributions, the use of
constraints to define sets of linear inequalities over paths, and the
introduction of slack and surplus variables to condition the topic distribution
to preferentially emphasize desired terms over others. We describe experimental
results to illustrate the effectiveness of our interactive storytelling
approach over multiple text datasets.


title: A new construction of Radon curves and related topics

abstract:
  We present a new construction of Radon curves which only uses convexity
methods. In other words, it does not rely on an auxiliary Euclidean background
metric (as in the classical works of J. Radon, W. Blaschke, G. Birkhoff, and M.
M. Day), and also it does not use typical methods from plane Minkowski Geometry
(as proposed by H. Martini and K. J. Swanepoel). We also discuss some
properties of normed planes whose unit circle is a Radon curve and give
characterizations of Radon curves only in terms of Convex Geometry.


title: Modelling homogeneous generative meta-programming

abstract:
  Homogeneous generative meta-programming (HGMP) enables the generation of
program fragments at compile-time or run-time. We present the first
foundational calculus which can model powerful HGMP languages such as Template
Haskell. The calculus is designed such that we can gradually enhance it with
the features needed to model many of the advanced features of real languages.
As a demonstration of the flexibility of our approach, we also provide a simple
type system for the calculus.


title: Smooth scheme morphisms: a fresh view

abstract:
  Relations between some kinds of formal and standard smoothness, for morphisms
of schemes, are clarified in surprisingly simple and direct ways, bypassing
much of the customarily employed machinery. Even the deep local-to-global
property of formal smoothness has a fairly elementary proof, under mild
additional hypotheses.


title:
A multivariate mixed hidden Markov model to analyze blue whale diving
  behaviour during controlled sound exposures

abstract:
  Characterization of multivariate time series of behaviour data from
animal-borne sensors is challenging. Biologists require methods to objectively
quantify baseline behaviour, then assess behaviour changes in response to
environmental stimuli. Here, we apply hidden Markov models (HMMs) to
characterize blue whale movement and diving behaviour, identifying latent
states corresponding to three main underlying behaviour states: shallow
feeding, travelling, and deep feeding. The model formulation accounts for
inter-whale differences via a computationally efficient discrete random effect,
and measures potential effects of experimental acoustic disturbance on
between-state transition probabilities. We identify clear differences in blue
whale disturbance response depending on the behavioural context during
exposure, with whales less likely to initiate deep foraging behaviour during
exposure. Findings are consistent with earlier studies using smaller samples,
but the HMM approach provides more nuanced characterization of behaviour
changes.


title:
Mean Field Equilibria for Competitive Exploration in Resource Sharing
  Settings

abstract:
  We consider a model of nomadic agents exploring and competing for
time-varying location-specific resources, arising in crowdsourced
transportation services, online communities, and in traditional location based
economic activity. This model comprises a group of agents, and a set of
locations each endowed with a dynamic stochastic resource process. Each agent
derives a periodic reward determined by the overall resource level at her
location, and the number of other agents there. Each agent is strategic and
free to move between locations, and at each time decides whether to stay at the
same node or switch to another one. We study the equilibrium behavior of the
agents as a function of dynamics of the stochastic resource process and the
nature of the externality each agent imposes on others at the same location. In
the asymptotic limit with the number of agents and locations increasing
proportionally, we show that an equilibrium exists and has a threshold
structure, where each agent decides to switch to a different location based
only on their current location's resource level and the number of other agents
at that location. This result provides insight into how system structure
affects the agents' collective ability to explore their domain to find and
effectively utilize resource-rich areas. It also allows assessing the impact of
changing the reward structure through penalties or subsidies.


title: Complex conjugation and Shimura varieties

abstract:
  In this paper we study the action of complex conjugation on Shimura varieties
and the problem of descending these to the maximal totally real field of the
reflex field. We prove the existence of such descent for many Shimura varieties
whose associated adjoint group has certain factors of type A or D. This
includes a large family of Shimura varieties of abelian type. Our
considerations and constructions are carried out purely at the level of Shimura
data and group theory.


title:
Did Jupiter's core form in the innermost parts of the Sun's
  protoplanetary disk?

abstract:
  Jupiter's core is generally assumed to have formed beyond the snow line. Here
we consider an alternative scenario, that Jupiter's core may have accumulated
in the innermost parts of the protoplanetary disk. A growing body of research
suggests that small particles ("pebbles") continually drift inward through the
disk. If a fraction of drifting pebbles is trapped at the inner edge of the
disk a several Earth-mass core can quickly grow. Subsequently, the core may
migrate outward beyond the snow line via planet-disk interactions. Of course,
to reach the outer Solar System Jupiter's core must traverse the terrestrial
planet-forming region.
  We use N-body simulations including synthetic forces from an underlying
gaseous disk to study how the outward migration of Jupiter's core sculpts the
terrestrial zone. If the outward migration is fast (Tmig~10^4 years), the core
simply migrates past resident planetesimals and planetary embryos. However, if
its migration is slower (Tmig~10^5 years) the core removes solids from the
inner disk by shepherding objects in mean motion resonances. In many cases the
disk interior to 0.5-1 AU is cleared of embryos and most planetesimals. By
generating a mass deficit close to the Sun, the outward migration of Jupiter's
core may thus explain the absence of terrestrial planets closer than Mercury.
Jupiter's migrating core often stimulates the growth of another large
(~Earth-mass) core -- that may provide a seed for Saturn's core -- trapped in
exterior resonance. The migrating core also may transport a fraction of
terrestrial planetesimals, such as the putative parent bodies of iron
meteorites, to the asteroid belt.


title:
Electronic isotope shift factors for the Cu $4s \; ^2S_{1/2} - 4p \;
  ^2P^o_{3/2}$ line

abstract:
  State-of-the-art relativistic multiconfiguration Dirac-Hartree-Fock
calculations have been performed to evaluate the electronic field and mass
isotope shift factors of the Cu~I resonance line at $\lambda = 324.8$~nm. A
linear correlation between the mass factors and the transition energy is found
for elaborate correlation models, allowing extrapolation to the observed
frequency limit. The relativistic corrections to the recoil operator reduces
the transition mass factor by 5~\%.


title:
On the noise induced by the measurement of the THz electrical current in
  quantum devices

abstract:
  From a quantum point of view, it is mandatory to include the measurement
process when predicting the time-evolution of a quantum system. In this paper,
a model to treat the measurement of the (TeraHertz) THz electrical current in
quantum devices is presented. The explicit interaction of a quantum system with
an external measuring apparatus is analyzed through the unambiguous notion of
the Bohmian conditional wave function, the wave function of a subsystem. It it
shown that such THz quantum measurement process can be modeled as a weak
measurement: The systems suffers a small perturbation due to the apparatus, but
the current is measured with a great uncertainty. This uncertainty implies that
a new source of noise appears at THz frequencies. Numerical (quantum Monte
Carlo) experiments are performed confirming the weak character of this
measurement. This work also indicates that at low frequencies this noise is
negligible and it can be ignored. From a classical point of view, the origin of
this noise due to the measurement at THz frequencies can be attributed to the
plasmonic effect of those electrons at the contacts (by interpreting the
contacts themselves as part of the measuring apparatus).


title: On the convergence of products of operator nets

abstract:
  The generalization of the Jessen-Marcinkiewicz-Zygmund-type theorem for the
abstract space with measure was obtained in current paper. Some applications to
classical harmonic analysis were reviewed.


title:
2-Bit Random Projections, NonLinear Estimators, and Approximate Near
  Neighbor Search

abstract:
  The method of random projections has become a standard tool for machine
learning, data mining, and search with massive data at Web scale. The effective
use of random projections requires efficient coding schemes for quantizing
(real-valued) projected data into integers. In this paper, we focus on a simple
2-bit coding scheme. In particular, we develop accurate nonlinear estimators of
data similarity based on the 2-bit strategy. This work will have important
practical applications. For example, in the task of near neighbor search, a
crucial step (often called re-ranking) is to compute or estimate data
similarities once a set of candidate data points have been identified by hash
table techniques. This re-ranking step can take advantage of the proposed
coding scheme and estimator.
  As a related task, in this paper, we also study a simple uniform quantization
scheme for the purpose of building hash tables with projected data. Our
analysis shows that typically only a small number of bits are needed. For
example, when the target similarity level is high, 2 or 3 bits might be
sufficient. When the target similarity level is not so high, it is preferable
to use only 1 or 2 bits. Therefore, a 2-bit scheme appears to be overall a good
choice for the task of sublinear time approximate near neighbor search via hash
tables.
  Combining these results, we conclude that 2-bit random projections should be
recommended for approximate near neighbor search and similarity estimation.
Extensive experimental results are provided.


title: On infinite groups admitting a faithful irreducible representation

abstract:
  Necessary and sufficient conditions for a group to possess a faithful
irreducible representation are investigated


title: Analytic queueing model for ambulance services

abstract:
  We present predictive tools to calculate the number of ambulances needed
according to demand of entrance calls and time of service. Our analysis
discriminates between emergency and non-urgent calls. First, we consider the
nonstationary regime where we apply previous results of first-passage time of
one dimensional random walks. Then, we reconsider the stationary regime with a
detailed discussion of the conditional probabilities and we discuss the key
performance indicators.


title: Rotating quark-gluon plasma in relativistic heavy ion collisions

abstract:
  We study the rotational collective motion of the quark-gluon plasma in
relativistic heavy ion collisions using the widely-adopted AMPT (A Multi-Phase
Transport) model. The global angular momentum, the average vorticity carried by
the quark-gluon plasma, and the locally defined vorticity fields are computed
for Au+Au collisions, with detailed information of their time evolution,
spatial distribution, as well as the dependence on beam energy and collision
centrality.


title:
Search for supersymmetry in the multijet and missing transverse momentum
  final state in pp collisions at 13 TeV

abstract:
  A search for new physics is performed based on all-hadronic events with large
missing transverse momentum produced in proton-proton collisions at sqrt(s) =
13 TeV. The data sample, corresponding to an integrated luminosity of 2.3
inverse femtobarns, was collected with the CMS detector at the CERN LHC in
2015. The data are examined in search regions of jet multiplicity, tagged
bottom quark jet multiplicity, missing transverse momentum, and the scalar sum
of jet transverse momenta. The observed numbers of events in all search regions
are found to be consistent with the expectations from standard model processes.
Exclusion limits are presented for simplified supersymmetric models of gluino
pair production. Depending on the assumed gluino decay mechanism, and for a
massless, weakly interacting, lightest neutralino, lower limits on the gluino
mass from 1440 to 1600 GeV are obtained, significantly extending previous
limits.


title:
Near-field signal acquisition for smartglasses using two acoustic
  vector-sensors

abstract:
  Smartglasses, in addition to their visual-output capabilities, often contain
acoustic sensors for receiving the user's voice. However, operation in noisy
environments may lead to significant degradation of the received signal. To
address this issue, we propose employing an acoustic sensor array which is
mounted on the eyeglasses frames. The signals from the array are processed by
an algorithm with the purpose of acquiring the user's desired near-filed speech
signal while suppressing noise signals originating from the environment. The
array is comprised of two AVSs which are located at the fore of the glasses'
temples. Each AVS consists of four collocated subsensors: one pressure sensor
(with an omnidirectional response) and three particle-velocity sensors (with
dipole responses) oriented in mutually orthogonal directions. The array
configuration is designed to boost the input power of the desired signal, and
to ensure that the characteristics of the noise at the different channels are
sufficiently diverse (lending towards more effective noise suppression). Since
changes in the array's position correspond to the desired speaker's movement,
the relative source-receiver position remains unchanged; hence, the need to
track fluctuations of the steering vector is avoided. Conversely, the spatial
statistics of the noise are subject to rapid and abrupt changes due to sudden
movement and rotation of the user's head. Consequently, the algorithm must be
capable of rapid adaptation. We propose an algorithm which incorporates
detection of the desired speech in the time-frequency domain, and employs this
information to adaptively update estimates of the noise statistics. Speech
detection plays a key role in ensuring the quality of the output signal. We
conduct controlled measurements of the array in noisy scenarios. The proposed
algorithm preforms favorably with respect to conventional algorithms.


title: A quantitative approach to weighted Carleson Condition

abstract:
  Quantitative versions of weighted estimates obtained by F. Ruiz and J.L.
Torrea in the 80's for the operator \[ \mathcal{M}f(x,t)=\sup_{x\in
Q,\,l(Q)\geq t}\frac{1}{|Q|}\int_{Q}|f(x)|dx \qquad x\in\mathbb{R}^{n}, \, t
\geq0 \] are obtained. As a consequence, some sufficient conditions for the
boundedness of $\mathcal{M}$ in the two weight setting in the spirit of the
results obtained by C. P\'erez and E. Rela and very recently by M.T. Lacey and
S. Spencer for the Hardy-Littlewood maximal operator are derived. As a
byproduct some new quantitative estimates for the Poisson integral are
obtained.


title:
A model-based approach to assess the effectiveness of pest biocontrol by
  natural enemies

abstract:
  Main goal: The aim of this note is to propose a modeling approach for
assessing the effectiveness of pest biocontrol by natural enemies in
diversified agricultural landscapes including several pesticide-based
management strategies. Our approach combines a stochastic landscape model with
a spatially-explicit model of population dynamics. It enables us to analyze the
effect of the landscape composition (proportion of semi-natural habitat,
non-treated crops, slightly treated crops and conventionally treated crops) on
the effectiveness of pest biocontrol. Effectiveness is measured through
environmental and agronomical descriptors, measuring respectively the impact of
the pesticides on the environment and the average agronomic productivity of the
whole landscape taking into account losses caused by pests.
  Conclusions: The effectiveness of the pesticide, the intensity of the
treatment and the pest intrinsic growth rate are found to be the main drivers
of landscape productivity. The loss in productivity due to a reduced use of
pesticide can be partly compensated by biocontrol. However, the model suggests
that it is not possible to maintain a constant level of productivity while
reducing the use of pesticides, even with highly efficient natural enemies.
Fragmentation of the semi-natural habitats and increased crop rotation tend to
slightly enhance the effectiveness of biocontrol but have a marginal effect
compared to the predation rate by natural enemies.
  This note was written in the framework of the ANR project PEERLESS
"Predictive Ecological Engineering for Landscape Ecosystem Services and
Sustainability"(ANR-12-AGRO-0006).


title:
Credit risk and companies' inter-organizational networks: Assessing
  impact of suppliers and buyers on CDS spreads

abstract:
  Companies do not operate in a vacuum. As companies move towards an
increasingly specialized production function and their reach is becoming truly
global, their aptitude in managing and shaping their inter-organizational
network is a determining factor in measuring their health. Current models of
company financial health often lack variables explaining the
inter-organizational network, and as such, assume that (1) all networks are the
same and (2) the performance of partners do not impact companies. This paper
aims to be a first step in the direction of removing these assumptions.
Specifically, the impact is illustrated by examining the effects of customer
and supplier concentrations and partners' credit risk on credit-default swap
(CDS) spreads while controlling for credit risk and size. We rely upon
supply-chain data from Bloomberg that provides insight into companies'
relationships. The empirical results show that a well diversified customer
network lowers CDS spread, while having stable partners with low default
probabilities increase spreads. The latter result suggests that successful
companies do not focus on building a stable eco-system around themselves, but
instead focus on their own profit maximization at the cost of the financial
health of their suppliers' and customers'. At a more general level, the results
indicate the importance of considering the inter-organizational networks, and
highlight the value of including network variables in credit risk models.


title: Recovering Structured Probability Matrices

abstract:
  We consider the problem of accurately recovering a matrix B of size M by M ,
which represents a probability distribution over M2 outcomes, given access to
an observed matrix of "counts" generated by taking independent samples from the
distribution B. How can structural properties of the underlying matrix B be
leveraged to yield computationally efficient and information theoretically
optimal reconstruction algorithms? When can accurate reconstruction be
accomplished in the sparse data regime? This basic problem lies at the core of
a number of questions that are currently being considered by different
communities, including building recommendation systems and collaborative
filtering in the sparse data regime, community detection in sparse random
graphs, learning structured models such as topic models or hidden Markov
models, and the efforts from the natural language processing community to
compute "word embeddings".
  Our results apply to the setting where B has a low rank structure. For this
setting, we propose an efficient algorithm that accurately recovers the
underlying M by M matrix using Theta(M) samples. This result easily translates
to Theta(M) sample algorithms for learning topic models and learning hidden
Markov Models. These linear sample complexities are optimal, up to constant
factors, in an extremely strong sense: even testing basic properties of the
underlying matrix (such as whether it has rank 1 or 2) requires Omega(M)
samples. We provide an even stronger lower bound where distinguishing whether a
sequence of observations were drawn from the uniform distribution over M
observations versus being generated by an HMM with two hidden states requires
Omega(M) observations. This precludes sublinear-sample hypothesis tests for
basic properties, such as identity or uniformity, as well as sublinear sample
estimators for quantities such as the entropy rate of HMMs.


title: A new look at the kinematics of the bulge from an N-body model

abstract:
  (Abridged) By using an N-body simulation of a bulge that was formed via a bar
instability mechanism, we analyse the imprints of the initial (i.e. before bar
formation) location of stars on the bulge kinematics, in particular on the
heliocentric radial velocity distribution of bulge stars. Four different
latitudes were considered: $b=-4^\circ$, $-6^\circ$, $-8^\circ$, and
$-10^\circ$, along the bulge minor axis as well as outside it, at
$l=\pm5^\circ$ and $l=\pm10^\circ$. The bulge X-shaped structure comprises
stars that formed in the disk at different locations. Stars formed in the outer
disk, beyond the end of the bar, which are part of the boxy peanut-bulge
structure may show peaks in the velocity distributions at positive and negative
heliocentric radial velocities with high absolute values that can be larger
than 100 $\rm km$ $\rm s^{-1}$, depending on the observed direction. In some
cases the structure of the velocity field is more complex and several peaks are
observed. Stars formed in the inner disk, the most numerous, contribute
predominantly to the X-shaped structure and present different kinematic
characteristics. Our results may enable us to interpret the cold high-velocity
peak observed in the APOGEE commissioning data, as well as the excess of
high-velocity stars in the near and far arms of the X-shaped structure at
$l$=$0^\circ$ and $b$=$-6^\circ$. When compared with real data, the kinematic
picture becomes more complex due to the possible presence in the observed
samples of classical bulge and/or thick disk stars. Overall, our results point
to the existence of complex patterns and structures in the bulge velocity
fields, which are generated by the bar. This suggests that caution should be
used when interpreting the bulge kinematics: the presence of substructures,
peaks and clumps in the velocity fields is not necessarily a sign of past
accretion events.


title:
Kramers turnover: from energy diffusion to spatial diffusion using
  metadynamics

abstract:
  We consider the rate of transition for a particle between two metastable
states coupled to a thermal environment for various magnitudes of the coupling
strength, using the recently proposed infrequent metadynamics approach (Tiwary
and Parrinello, Phys. Rev. Lett. 111, 230602 (2013)). We are interested in
understanding how this approach for obtaining rate constants performs as the
dynamics regime changes from energy diffusion to spatial diffusion.
Reassuringly, we find that the approach works remarkably well for various
coupling strengths in the strong coupling regime, and to some extent even in
the weak coupling regime.


title:
High-performance generation of the Hamiltonian and Overlap matrices in
  FLAPW methods

abstract:
  One of the greatest efforts of computational scientists is to translate the
mathematical model describing a class of physical phenomena into large and
complex codes. Many of these codes face the difficulty of implementing the
mathematical operations in the model in terms of low level optimized kernels
offering both performance and portability. Legacy codes suffer from the
additional curse of rigid design choices based on outdated performance metrics
(e.g. minimization of memory footprint). Using a representative code from the
Materials Science community, we propose a methodology to restructure the most
expensive operations in terms of an optimized combination of dense linear
algebra kernels. The resulting algorithm guarantees an increased performance
and an extended life span of this code enabling larger scale simulations.


title: The thermoelectric working fluid: thermodynamics and transport

abstract:
  Thermoelectric devices are heat engines, which operate as generators or
refrigerators using the conduction electrons as a working fluid. The
thermoelectric heat-to-work conversion efficiency has always been typically
quite low, but much effort continues to be devoted to the design of new
materials boasting improved transport properties that would make them of the
electron crystal-phonon glass type of systems. On the other hand, there are
comparatively few studies where a proper thermodynamic treatment of the
electronic working fluid is proposed. The present article aims to contribute to
bridge this gap by addressing both the thermodynamic and transport properties
of the thermoelectric working fluid covering a variety of models, including
interacting systems.


title: Systematic Target Function Annotation of Human Transcription Factors

abstract:
  Transcription factors (TFs), the key players in transcriptional regulation,
have attracted great experimental attention, yet the functions of most human
TFs remain poorly understood. Recent capabilities in genome-wide protein
binding profiling have stimulated systematic studies of the hierarchical
organization of human gene regulatory network and DNA-binding specificity of
TFs, shedding light on combinatorial gene regulation. We show here that these
data also enable a systematic annotation of the biological functions and
functional diversity of TFs. We compiled a human gene regulatory network for
384 TFs covering the 146,096 TF-target gene relationships, extracted from over
850 ChIP-seq experiments as well as the literature. By integrating this network
of TF-TF and TF-target gene relationships with 3,715 functional concepts from
six sources of gene function annotations, we obtained over 9,000 confident
functional annotations for 279 TFs. We observe extensive connectivity between
transcription factors and Mendelian diseases, GWAS phenotypes, and
pharmacogenetic pathways. Further, we show that transcription factors link
apparently unrelated functions, even when the two functions do not share common
genes. Finally, we analyze the pleiotropic functions of TFs and suggest that
increased number of upstream regulators contributes to the functional
pleiotropy of TFs. Our computational approach is complementary to focused
experimental studies on TF functions, and the resulting knowledge can guide
experimental design for discovering the unknown roles of TFs in human disease
and drug response.


title: Active galactic nuclei at gamma-ray energies

abstract:
  Active Galactic Nuclei can be copious extragalactic emitters of MeV-GeV-TeV
gamma rays, a phenomenon linked to the presence of relativistic jets powered by
a super-massive black hole in the center of the host galaxy. Most of gamma-ray
emitting active galactic nuclei, with more than 1500 known at GeV energies, and
more than 60 at TeV energies, are called "blazars". The standard blazar
paradigm features a jet of relativistic magnetized plasma ejected from the
neighborhood of a spinning and accreting super-massive black hole, close to the
observer direction. Two classes of blazars are distinguished from observations:
the flat-spectrum radio-quasar class (FSRQ) is characterized by strong external
radiation fields, emission of broad optical lines, and dust tori. The BL Lac
class (from the name of one of its members, BL Lacertae) corresponds to weaker
advection-dominated flows with gamma-ray spectra dominated by the inverse
Compton effect on synchrotron photons. This paradigm has been very successful
for modeling the broadband spectral energy distributions of blazars. However,
many fundamental issues remain, including the role of hadronic processes and
the rapid variability of those BL Lac objects whose synchrotron spectrum peaks
at UV or X-ray frequencies. A class of gamma-ray--emitting radio galaxies,
which are thought to be the misaligned counterparts of blazars, has emerged
from the results of the Fermi-Large Area Telescope and of ground-based
Cherenkov telescopes. Blazars and their misaligned ounterparts make up most of
the >100 MeV extragalactic gamma ray background (EGB), and are uspected of
being the sources of ultra-high energy cosmic rays. The future "Cherenkov
Telescope Array", in synergy with the Fermi-Large Area Telescope and a wide
range of telescopes in space and on he ground, will write the next chapter of
blazar physics.


title:
On the monoid of monotone injective partial selfmaps of
  $\mathbb{N}^{2}_{\leqslant}$ with cofinite domains and images

abstract:
  Let $\mathbb{N}^{2}_{\leqslant}$ be the set $\mathbb{N}^{2}$ with the partial
order defined as the product of usual order $\leq$ on the set of positive
integers $\mathbb{N}$. We study the semigroup
$\mathscr{P\!O}\!_{\infty}(\mathbb{N}^2_{\leqslant})$ of monotone injective
partial selfmaps of $\mathbb{N}^{2}_{\leqslant}$ having cofinite domain and
image. We describe properties of elements of the semigroup
$\mathscr{P\!O}\!_{\infty}(\mathbb{N}^2_{\leqslant})$ as monotone partial
bijections of $\mathbb{N}^{2}_{\leqslant}$ and show that the group of units of
$\mathscr{P\!O}\!_{\infty}(\mathbb{N}^2_{\leqslant})$ is isomorphic to the
cyclic group of order two. Also we describe the subsemigroup of idempotents of
$\mathscr{P\!O}\!_{\infty}(\mathbb{N}^2_{\leqslant})$ and the Green relations
on $\mathscr{P\!O}\!_{\infty}(\mathbb{N}^2_{\leqslant})$. In particular, we
show that $\mathscr{D}=\mathscr{J}$ in
$\mathscr{P\!O}\!_{\infty}(\mathbb{N}^2_{\leqslant})$.


title:
Vulnerability of linear systems against sensor attacks--a system's
  security index

abstract:
  The `security index' of a discrete-time LTI system under sensor attacks is
introduced as a quantitative measure on the security of an observable system.
We derive ideas from error control coding theory to provide sufficient
conditions for attack detection and correction.


title:
Weak separation in mixture models and implications for principal
  stratification

abstract:
  Principal stratification is a widely used framework for addressing
post-randomization complications. After using principal stratification to
define causal effects of interest, researchers are increasingly turning to
finite mixture models to estimate these quantities. Unfortunately, standard
estimators of mixture parameters, like the MLE, are known to exhibit
pathological behavior. We study this behavior in a simple but fundamental
example, a two-component Gaussian mixture model in which only the component
means and variances are unknown, and focus on the setting in which the
components are weakly separated. In this case, we show that the asymptotic
convergence rate of the MLE is quite poor, such as $O(n^{-1/6})$ or even
$O(n^{-1/8})$. We then demonstrate via theoretical arguments as well as
extensive simulations that, in finite samples, the MLE behaves like a threshold
estimator, in the sense that the MLE can give strong evidence that the means
are equal when the truth is otherwise. We also explore the behavior of the MLE
when the MLE is non-zero, showing that it is difficult to estimate both the
sign and magnitude of the means in this case. We provide diagnostics for all of
these pathologies and apply these ideas to re-analyzing two randomized
evaluations of job training programs, JOBS II and Job Corps. Our results
suggest that the corresponding maximum likelihood estimates should be
interpreted with caution in these cases.


title: Dynamics of Coulombic and Gravitational Periodic Systems

abstract:
  We study the dynamics and the phase-space structures of Coulombic and
self-gravitating versions of the classical one-dimensional 3-body system with
periodic boundary conditions. We demonstrate that such a 3-body system may be
reduced isomorphically to a spatially periodic system of a single particle
experiencing a two-dimensional potential on a rhombic plane. For the case of
both Coulombic and gravitational versions, exact expressions of the Hamiltonian
have been derived in rhombic coordinates. We simulate the phase-space evolution
through an event-driven algorithm that utilizes analytic solutions to the
equations of motion. The simulation results show that the motion exhibits
chaotic, quasiperiodic, and periodic behaviors in segmented regions of the
phase space. While there is no evidence of global chaos in either the Coulombic
or the gravitational system, the former exhibits a transition from a completely
non-chaotic phase space at low energies to a mixed behavior. Gradual yet
striking transitions from mild to intense chaos are indicated with changing
energy, a behavior that differentiates the spatially periodic systems studied
in this paper from the well-understood free-boundary versions of the 3-body
problem. Our treatment of the 3-body systems is the first one of its kind and
opens avenues for analysis of the dynamical properties exhibited by spatially
periodic versions of various classes of systems studied in plasma and
gravitational physics as well as in cosmology.


title: Degree bound for separating invariants of abelian groups

abstract:
  It is proved that the universal degree bound for separating polynomial
invariants of a finite abelian group (in non-modular characteristic) is
strictly smaller than the universal degree bound for generators of polynomial
invariants, unless the goup is cyclic or is the direct product of $r$ even
order cyclic groups where the number of two-element direct factors is not less
than the integer part of the half of $r$. A characterization of separating sets
of monomials is given in terms of zero-sum sequences over abelian groups.


title:
Initial Beam Association in Millimeter Wave Cellular Systems: Analysis
  and Design Insights

abstract:
  Enabling the high data rates of millimeter wave (mmWave) cellular systems
requires deploying large antenna arrays at both the basestations and mobile
users. The beamforming weights of these large arrays need to be tuned to
guarantee sufficient beamforming gains. Prior work on coverage and rate of
mmWave cellular networks focused mainly on the case when basestations and
mobile users beamfomring vectors are perfectly designed for maximum beamforming
gains. Designing beamforming/combining vectors, though, requires training which
may impact both the SINR coverage and rate of mmWave cellular systems. This
paper characterizes and evaluates the performance of mmWave cellular networks
while accounting for the beam training/association overhead. First, a model for
the initial beam association is developed based on beam sweeping and downlink
control pilot reuse. To incorporate the impact of beam training into system
performance, a new metric, called the effective reliable rate, is defined and
adopted. Using stochastic geometry, the effective reliable rate of mmWave
cellular networks is derived for two special cases: with near-orthogonal
control pilots and with full pilot reuse. Analytical and simulation results
provide insights into the answers of three important questions: (i) What is the
impact of beam association on mmWave network performance? (ii) Should
orthogonal or reused control pilots be employed in the initial beam association
phase? (iii) Should exhaustive or hierarchical search be adopted for the beam
training phase? The results show that unless the employed beams are very wide
or the system coherence block length is very small, exhaustive search with full
pilot reuse is nearly as good as perfect beam alignment.


title: Towards Unified Combinatorial Interaction Testing

abstract:
  We believe that we can exploit the benefits of combinatorial interaction
testing (CIT) on many "non-traditional" combinatorial spaces using many
"non-traditional" coverage criteria. However, this requires truly flexible CIT
approaches. To this end, we introduce Unified Combinatorial Interaction Testing
(U-CIT), which enables practitioners to define their own combinatorial spaces
and coverage criteria for testing, and present a unified construction approach
to compute specific instances of U-CIT objects. We, furthermore, argue that
most (if not all) existing CIT objects are a special case of U-CIT and
demonstrate the flexibility of U-CIT on a simple, yet realistic scenario.


title: Black Hole Information Loss: Some Food for Thoughts

abstract:
  We provide some thoughts on the black hole information loss paradox,
highlighting some important aspects of the problem that need to be addressed in
order to resolve the paradox.


title:
Light-Matter Interaction: Conversion of Optical Energy and Momentum to
  Mechanical Vibrations and Phonons

abstract:
  Reflection, refraction, and absorption of light by material media are, in
general, accompanied by a transfer of optical energy and momentum to the media.
Consequently, the eigen-modes of mechanical vibration (phonons) created in the
process must distribute the acquired energy and momentum throughout the
material medium. However, unlike photons, phonons do not carry momentum. What
happens to the material medium in its interactions with light, therefore,
requires careful consideration if the conservation laws are to be upheld. The
present paper addresses some of the mechanisms by which the electromagnetic
momentum of light is carried away by mechanical vibrations.


title: Gaussian elimination corrects pivoting mistakes

abstract:
  Gaussian elimination (GE) is the archetypal direct algorithm for solving
linear systems of equations and this has been its primary application for
thousands of years. In the last decade, GE has found another major use as an
iterative algorithm for low rank approximation. In this setting, GE is often
employed with complete pivoting and designed to allow for non-optimal pivoting,
i.e., pivoting mistakes, that could render GE numerically unstable when
implemented in floating point arithmetic. While it may appear that pivoting
mistakes could accumulate and lead to a large growth factor, we show that later
GE steps correct earlier pivoting mistakes, even while more are being made. In
short, GE is very robust to non-optimal pivots, allowing for its iterative
variant to flourish.


title:
On squares in subsets of finite fields with restrictions on coefficients
  of basis decomposition

abstract:
  We consider the linear vector space formed by the elements of the finite
fields $\mathbb{F}_q$ with $q=p^r$ over $\mathbb{F}_p$. Let ${a_1,\ldots,a_r}$
be a basis of this space. Then the elements $x$ of $\mathbb{F}_q$ have a unique
representation in the form $\sum_{j=1}^r c_ja_j$ with $c_j\in\mathbb{F}_p$. Let
$D$ be a subset of $\mathbb{F}_p$. We consider the set $W_D$ of elements of
$\mathbb{F}_q$ such that $c_j\in D$ for all $j=1,\ldots,r$. We give an estimate
for the number of squares in the set $W_D$ which implies a weaker sufficient
condition for the existence of squares in the set $W_D$ than in the recent
paper of C.Dartyge, C.Mauduit, A.S\'ark\"ozy.


title:
Detection of Cyber-Physical Faults and Intrusions from Physical
  Correlations

abstract:
  Cyber-physical systems are critical infrastructures that are crucial both to
the reliable delivery of resources such as energy, and to the stable
functioning of automatic and control architectures. These systems are composed
of interdependent physical, control and communications networks described by
disparate mathematical models creating scientific challenges that go well
beyond the modeling and analysis of the individual networks. A key challenge in
cyber-physical defense is a fast online detection and localization of faults
and intrusions without prior knowledge of the failure type. We describe a set
of techniques for the efficient identification of faults from correlations in
physical signals, assuming only a minimal amount of available system
information. The performance of our detection method is illustrated on data
collected from a large building automation system.

categories: cs.SY cs.SI physics.data-an physics.soc-ph stat.AP


title:
Large deviations for invariant measures of white-forced 2D Navier-Stokes
  equation

abstract:
  The paper is devoted to studying the asymptotics of the family
$(\mu^\varepsilon)$ of stationary measures of the Markov process generated by
the flow of stochastic 2D Navier-Stokes equation with smooth white noise. By
using the large deviations techniques, we prove that this family is
exponentially tight in $H^{1-\gamma}(D)$ for any $\gamma>0$ and vanishes
exponentially outside any neighborhood of the set $\cal O$ of $\omega$-limit
points of the deterministic equation. In particular, any of its weak limits is
concentrated on the closure $\bar{\cal O}$. A key ingredient of the proof is a
new formula that allows to recover the stationary measure $\mu$ of a Markov
process with good mixing properties, knowing only some local information about
$\mu$. In the case of trivial limiting dynamics, our result implies that the
family $(\mu^\varepsilon)$ obeys the large deviations principle.


title: Estimating Structured Vector Autoregressive Model

abstract:
  While considerable advances have been made in estimating high-dimensional
structured models from independent data using Lasso-type models, limited
progress has been made for settings when the samples are dependent. We consider
estimating structured VAR (vector auto-regressive models), where the structure
can be captured by any suitable norm, e.g., Lasso, group Lasso, order weighted
Lasso, sparse group Lasso, etc. In VAR setting with correlated noise, although
there is strong dependence over time and covariates, we establish bounds on the
non-asymptotic estimation error of structured VAR parameters. Surprisingly, the
estimation error is of the same order as that of the corresponding Lasso-type
estimator with independent samples, and the analysis holds for any norm. Our
analysis relies on results in generic chaining, sub-exponential martingales,
and spectral representation of VAR models. Experimental results on synthetic
data with a variety of structures as well as real aviation data are presented,
validating theoretical results.


title: Why should one compute periods of algebraic cycles?

abstract:
  In this article we show how the data of integrals of algebraic differential
forms over algebraic cycles can be used in order to prove that algebraic and
Hodge cycle deformations of a given algebraic cycle are equivalent. As an
example, we prove that most of the Hodge and algebraic cycles of the Fermat
sextic fourfold cannot be deformed in the underlying parameter space. We then
take a difference of two linear cycles inside the Fermat variety, and gather
evidences that the Hodge locus corresponding to this is smooth and reduced.
This implies the existence of new algebraic cycles in the Fermat variety whose
existence is predicted by the Hodge conjecture for all hypersurfaces, but not
the Fermat variety itself.


title: On the existence of infinite, non-trivial $F$-sets

abstract:
  In this paper we prove a conjecture of J. Andrade, S. J. Miller, K. Pratt and
M. Trinh, showing the existence of a non trivial infinite $F$-set over $\mathbb
F_q[x]$ for every fixed $q$. We also provide the proof of a refinement of the
conjecture, involving the notion of width of an $F$-set, which is a natural
number encoding the complexity of the set.


title: Nonparametric and Varying Coefficient Modal Regression

abstract:
  In this article, we propose a new nonparametric data analysis tool, which we
call nonparametric modal regression, to investigate the relationship among
interested variables based on estimating the mode of the conditional density of
a response variable Y given predictors X. The nonparametric modal regression is
distinguished from the conventional nonparametric regression in that, instead
of the conditional average or median, it uses the "most likely" conditional
values to measures the center. Better prediction performance and robustness are
two important characteristics of nonparametric modal regression compared to
traditional nonparametric mean regression and nonparametric median regression.
We propose to use local polynomial regression to estimate the nonparametric
modal regression. The asymptotic properties of the resulting estimator are
investigated. To broaden the applicability of the nonparametric modal
regression to high dimensional data or functional/longitudinal data, we further
develop a nonparametric varying coefficient modal regression. A Monte Carlo
simulation study and an analysis of health care expenditure data demonstrate
some superior performance of the proposed nonparametric modal regression model
to the traditional nonparametric mean regression and nonparametric median
regression in terms of the prediction performance.


title: Mixture of Regression Models with Single-Index

abstract:
  In this article, we propose a class of semiparametric mixture regression
models with single-index. We argue that many recently proposed
semiparametric/nonparametric mixture regression models can be considered
special cases of the proposed model. However, unlike existing semiparametric
mixture regression models, the new pro- posed model can easily incorporate
multivariate predictors into the nonparametric components. Backfitting
estimates and the corresponding algorithms have been proposed for to achieve
the optimal convergence rate for both the parameters and the nonparametric
functions. We show that nonparametric functions can be esti- mated with the
same asymptotic accuracy as if the parameters were known and the index
parameters can be estimated with the traditional parametric root n convergence
rate. Simulation studies and an application of NBA data have been conducted to
demonstrate the finite sample performance of the proposed models.


title: Remote Nanodiamond Magnetometry

abstract:
  Optical fibres have transformed the way people interact with the world and
now permeate many areas of science. Optical fibres are traditionally thought of
as insensitive to magnetic fields, however many application areas from mining
to biomedicine would benefit from fibre-based remote magnetometry devices. In
this work, we realise such a device by embedding nanoscale magnetic sensors
into tellurite glass fibres. Remote magnetometry is performed on magnetically
active defect centres in nanodiamonds embedded into the glass matrix. Standard
optical magnetometry techniques are applied to initialize and detect local
magnetic field changes with a measured sensitivity of 26 micron Tesla/square
root(Hz). Our approach utilizes straight-forward optical excitation, simple
focusing elements, and low power components. We demonstrate remote magnetometry
by direct reporting of the magnetic ground states of nitrogen-vacancy defect
centres in the optical fibres. In addition, we present and describe
theoretically an all-optical technique that is ideally suited to remote
fibre-based sensing. The implications of our results broaden the applications
of optical fibres, which now have the potential to underpin a new generation of
medical magneto-endoscopes and remote mining sensors.


title: Clustering subgaussian mixtures by semidefinite programming

abstract:
  We introduce a model-free relax-and-round algorithm for k-means clustering
based on a semidefinite relaxation due to Peng and Wei. The algorithm
interprets the SDP output as a denoised version of the original data and then
rounds this output to a hard clustering. We provide a generic method for
proving performance guarantees for this algorithm, and we analyze the algorithm
in the context of subgaussian mixture models. We also study the fundamental
limits of estimating Gaussian centers by k-means clustering in order to compare
our approximation guarantee to the theoretically optimal k-means clustering
solution.

categories: stat.ML cs.DS cs.IT cs.LG math.IT math.ST stat.TH


title: A Duality in Buchsbaum rings and triangulated manifolds

abstract:
  Let $\Delta$ be a triangulated homology ball whose boundary complex is
$\partial\Delta$. A result of Hochster asserts that the canonical module of the
Stanley--Reisner ring of $\Delta$, $\mathbb F[\Delta]$, is isomorphic to the
Stanley--Reisner module of the pair $(\Delta, \partial\Delta)$, $\mathbb
F[\Delta,\partial \Delta]$. This result implies that an Artinian reduction of
$\mathbb F[\Delta,\partial \Delta]$ is (up to a shift in grading) isomorphic to
the Matlis dual of the corresponding Artinian reduction of $\mathbb F[\Delta]$.
We establish a generalization of this duality to all triangulations of
connected orientable homology manifolds with boundary. We also provide an
explicit algebraic interpretation of the $h"$-numbers of Buchsbaum complexes
and use it to prove the monotonicity of $h"$-numbers for pairs of Buchsbaum
complexes as well as the unimodality of $h"$-vectors of barycentric
subdivisions of Buchsbaum polyhedral complexes. We close with applications to
the algebraic manifold $g$-conjecture.


title:
Fourier Coefficients for Theta Representations on Covers of General
  Linear Groups

abstract:
  We show that the theta representations on certain covers of general linear
groups support certain types of unique functionals. The proof involves two
types of Fourier coefficients. The first are semi-Whittaker coefficients, which
generalize coefficients introduced by Bump and Ginzburg for the double cover.
The covers for which these coefficients vanish identically (resp. do not vanish
for some choice of data) are determined in full. The second are the Fourier
coefficients associated with general unipotent orbits. In particular, we
determine the unipotent orbit attached, in the sense of Ginzburg, to the theta
representations.


title:
Explicit Equilibrium Solutions For the Aggregation Equation with
  Power-Law Potentials

abstract:
  Despite their wide presence in various models in the study of collective
behaviors, explicit swarming patterns are difficult to obtain. In this paper,
special stationary solutions of the aggregation equation with power-law kernels
are constructed by inverting Fredholm integral operators or by employing
certain integral identities. These solutions are expected to be the global
energy stable equilibria and to characterize the generic behaviors of
stationary solutions for more general interactions.


title: Some functionals on compact manifolds with boundary

abstract:
  We analyze critical points of two functionals of Riemannian metrics on
compact manifolds with boundary. These functionals are motivated by formulae of
the mass functionals of asymptotically flat and asymptotically hyperbolic
manifolds.


title:
An explicit formula for the Siegel series of a quadratic form over a
  non-archimedian local field

abstract:
  Let F be a non-archimedian local field of characteristic 0, and O the ring of
integres in F. We give an explicit formula for the Siegel series of a
half-integral matrix over O. This formula expresses the Siegel series of a
half-integral matrix $B$ explicitly in terms of the Gross-Keating invariant of
$B$ and its related invariants.


title:
Operad bimodules, and composition products on Andre-Quillen filtrations
  of algebras

abstract:
  If O is a reduced operad in symmetric spectra, an O-algebra I can be viewed
as analogous to the augmentation ideal of an augmented algebra. Implicit in the
literature on Topological Andre-Quillen homology is that such an I admits a
canonical (and homotopically meaningful) decreasing O-algebra filtration I >
I^2 > I^3 > ... satisfying various nice properties analogous to powers of an
ideal in a ring.
  In this paper, we are explicit about these constructions. With R a
commutative S-algebra, we study derived versions of the circle product M o_O I,
where M is an O-bimodule, and I is an O-algebra in R-modules. Letting M run
through a decreasing O-bimodule filtration of O itself then yields the
augmentation ideal filtration as above. The composition structure of the operad
induces algebra maps from (I^i)^j to I^{ij}, fitting nicely with previously
studied structure.
  As a formal consequence, an O-algebra map from I to J^d induces compatible
maps from I^n to J^{dn}, for all n. This is an essential tool in the first
author's study of Hurewicz maps for infinite loop spaces, and its utility is
illustrated here with a lifting theorem.


title: Magnetoelectric properties of 500 nm Cr2O3 films

abstract:
  The linear magnetoelectric effect was measured in 500 nm Cr2O3 films grown by
rf sputtering on Al2O3 substrates between top and bottom thin film Pt
electrodes. Magnetoelectric susceptibility was measured directly by applying an
AC electric field and measuring the induced AC magnetic moment using
superconducting quantum interference device magnetometry. A linear dependence
of the induced AC magnetic moment on the AC electric field amplitude was found.
The temperature dependence of the magnetoelectric susceptibility agreed
qualitatively and quantitatively with prior measurements of bulk single
crystals, but the characteristic temperatures of the film were lower than those
of single crystals. It was also possible to reverse the sign of the
magnetoelectric susceptibility by reversing the sign of the magnetic field
applied during cooling through the N\'eel temperature. A competition between
total magnetoelectric and Zeeman energies is proposed to explain the difference
between film and bulk Cr2O3 regarding the cooling field dependence of the
magnetoelectric effect.


title: A randomized algorithm for enumerating zonotope vertices

abstract:
  We propose a randomized algorithm for enumerating the vertices of a zonotope,
which is a low-dimensional linear projection of a hypercube. The algorithm
produces a pair of the zonotope's vertices by sampling a random linear
combination of the zonotope generators, where the combination's weights are the
signs of the product between the zonotope's generator matrix and random vectors
with normally distributed entries. We study the probability of recovering
particular vertices and relate it to the vertices' normal cones. This study
shows that if we terminate the randomized algorithm before all vertices are
recovered, then the convex hull of the resulting vertex set approximates the
zonotope. In high dimensions, we expect the enumeration algorithm to be most
appropriate as an approximation algorithm---particularly for cases when
existing methods are not practical.


title: Stochastic Matrix-Free Equilibration

abstract:
  We present a novel method for approximately equilibrating a matrix $A \in
{\bf R}^{m \times n}$ using only multiplication by $A$ and $A^T$. Our method is
based on convex optimization and projected stochastic gradient descent, using
an unbiased estimate of a gradient obtained by a randomized method. Our method
provably converges in expectation with an $O(1/t)$ convergence rate and
empirically gets good results with a small number of iterations. We show how
the method can be applied as a preconditioner for matrix-free iterative
algorithms such as LSQR and Chambolle-Cremers-Pock, substantially reducing the
iterations required to reach a given level of precision. We also derive a novel
connection between equilibration and condition number, showing that
equilibration minimizes an upper bound on the condition number over all choices
of row and column scalings.


title: Mock Threshold Graphs

abstract:
  Mock threshold graphs are a simple generalization of threshold graphs that,
like threshold graphs, are perfect graphs. Our main theorem is a
characterization of mock threshold graphs by forbidden induced subgraphs. Other
theorems characterize mock threshold graphs that are claw-free and that are
line graphs. We also discuss relations with chordality and well-quasi-ordering
as well as algorithmic aspects.


title:
The radio environment of the 21 Centimeter Array: RFI detection and
  mitigation

abstract:
  Detection and mitigation of radio frequency interference (RFI) is the first
and also the key step for data processing in radio observations, especially for
ongoing low frequency radio experiments towards the detection of the cosmic
dawn and epoch of reionization (EoR). In this paper we demonstrate the
technique and efficiency of RFI identification and mitigation for the 21
Centimeter Array (21CMA), a radio interferometer dedicated to the statistical
measurement of EoR. For terrestrial, man-made RFI, we concentrate mainly on a
statistical approach by identifying and then excising non-Gaussian signatures,
in the sense that the extremely weak cosmic signal is actually buried under
thermal and therefore Gaussian noise. We also introduce the so-called
visibility correlation coefficient instead of conventional visibility, which
allows a further suppression of rapidly time-varying RFI. Finally, we briefly
discuss removals of the sky RFI, the leakage of sidelobes from off-field strong
radio sources with time-invariant power and a featureless spectrum. It turns
out that state of the art technique should allow us to detect and mitigate RFI
to a satisfactory level in present low frequency interferometer observations
such as those acquired with the 21CMA, and the accuracy and efficiency can be
greatly improved with the employment of low-cost, high-speed computing
facilities for data acquisition and processing.


title: Radio Sources in the NCP Region Observed with the 21 Centimeter Array

abstract:
  We present a catalog of 624 radio sources detected around the North Celestial
Pole (NCP) with the 21 Centimeter Array (21CMA), a radio interferometer
dedicated to the statistical measurement of the epoch of reionization (EoR).
The data are taken from a 12 h observation made on 2013 April 13, with a
frequency coverage from 75 to 175 MHz and an angular resolution of ~ 4 arcmin.
The catalog includes flux densities at eight sub-bands across the 21CMA
bandwidth and provides the in-band spectral indices for the detected sources.
To reduce the complexity of interferometric imaging from the so-called "w" term
and ionospheric effects, the present analysis are restricted to the east-west
baselines within 1500 m only. The 624 radio sources are found within 5 degrees
around the NCP down to ~ 0.1 Jy. Our source counts are compared, and also
exhibit a good agreement, with deep low-frequency observations made recently
with the GMRT and MWA. In particular, for fainter radio sources below ~ 1 Jy,
we find a flattening trend of source counts towards lower frequencies. While
the thermal noise (~0.4 mJy) is well controlled to below the confusion limit,
the dynamical range (~10^4) and sensitivity of current 21CMA imaging is largely
limited by calibration and deconvolution errors, especially the grating lobes
of very bright sources, such as 3C061.1, in the NCP field which result from the
regular spacings of the 21CMA. We note that particular attention should be paid
to the extended sources, and their modeling and removals may constitute a large
technical challenge for current EoR experiments. Our analysis may serve as a
useful guide to design of next generation low-frequency interferometers like
the Square Kilometre Array.


title:
How far are the sources of IceCube neutrinos? Constraints from the
  diffuse TeV gamma-ray background

abstract:
  The nearly isotropic distribution of the TeV-PeV neutrinos recently detected
by IceCube suggests that they come from sources at distance beyond our Galaxy,
but how far they are is largely unknown due to lack of any associations with
known sources. In this paper, we propose that the cumulative TeV gamma-ray
emission accompanying the production of neutrinos can be used to constrain the
distance of these neutrino sources, since the opacity of TeV gamma rays due to
absorption by the extragalactic background light (EBL) depends on the distance
that these TeV gamma rays have travelled. As the diffuse extragalactic TeV
background measured by \emph{Fermi} is much weaker than the expected cumulative
flux associated with IceCube neutrinos, the majority of IceCube neutrinos, if
their sources are transparent to TeV gamma rays, must come from distances
larger than the horizon of TeV gamma rays. We find that above 80\% of the
IceCube neutrinos should come from sources at redshift $z>0.5$. Thus, the
chance for finding nearby sources correlated with IceCube neutrinos would be
small. We also find that, to explain the flux of neutrinos under the TeV
gamma-ray emission constraint, the redshift evolution of neutrino source
density must be at least as fast as the the cosmic star-formation rate.


title:
Dyson's spike for random Schroedinger operators and Novikov-Shubin
  invariants of groups

abstract:
  We study Schroedinger operators with random edge weights and their expected
spectral measures $\mu_H$ near zero. We prove that the measure exhibits a spike
of the form $\mu_H(-\varepsilon,\varepsilon) \sim \frac{C}{|
\log\varepsilon|^2}$ (first observed by Dyson), without assuming independence
or any regularity of edge weights. We also identify the limiting local
eigenvalue distribution, which is different from Poisson and the usual random
matrix statistics. We then use the result to compute Novikov-Shubin invariants
for various groups, including lamplighter groups and lattices in the Lie group
Sol.


title:
Sensitivity Conjecture and Log-rank Conjecture for functions with small
  alternating numbers

abstract:
  The Sensitivity Conjecture and the Log-rank Conjecture are among the most
important and challenging problems in concrete complexity. Incidentally, the
Sensitivity Conjecture is known to hold for monotone functions, and so is the
Log-rank Conjecture for $f(x \wedge y)$ and $f(x\oplus y)$ with monotone
functions $f$, where $\wedge$ and $\oplus$ are bit-wise AND and XOR,
respectively. In this paper, we extend these results to functions $f$ which
alternate values for a relatively small number of times on any monotone path
from $0^n$ to $1^n$. These deepen our understandings of the two conjectures,
and contribute to the recent line of research on functions with small
alternating numbers.


title: Composite (pseudo) scalar contributions to muon g-2

abstract:
  We have calculated the composite (pseudo) scalar contributions to the
anomalous magnetic moment of muons in models of walking technicolor. By the
axial or scale anomaly the light scalars such as techni-dilaton, techni-pions
or techni-eta have anomalous couplings to two-photons, which make them natural
candidates for the recent 750 GeV resonance excess, observed at LHC. Due to the
anomalous couplings, their contributions to muon (g-2) are less suppressed and
might explain the current deviation in muon (g-2) measurements from theory.


title:
Nested critical points for a directed polymer on a disordered diamond
  lattice

abstract:
  We consider a model for a directed polymer in a random environment defined on
a hierarchical diamond lattice in which i.i.d. random variables are attached to
the lattice bonds. Our focus is on scaling schemes in which a size parameter
$n$, counting the number of hierarchical layers of the system, becomes large as
the inverse temperature $\beta$ vanishes. When $\beta$ has the form
$\widehat{\beta}/\sqrt{n}$ for a parameter $\widehat{\beta}>0$, we show that
there is a cutoff value $0 < \kappa < \infty$ such that as $n \to \infty$ the
variance of the normalized partition function tends to zero for
$\widehat{\beta}\leq \kappa $ and grows without bound for $\widehat{\beta} >
\kappa $. We obtain a more refined description of the border between these two
regimes by setting the inverse temperature to $\kappa/\sqrt{n} + \alpha_n$
where $0 < \alpha_n \ll 1/\sqrt{n}$ and analyzing the asymptotic behavior of
the variance. We show that when $\alpha_n = \alpha (\log n-\log \log
n)/n^{3/2}$ (with a small modification to deal with non-zero third moment)
there is a similar cutoff value $\eta$ for the parameter $\alpha$ such that
when $\alpha < \eta$ the variance goes to zero and grows without bound when
$\alpha > \eta$. Extending the analysis yet again by probing around the inverse
temperature $\kappa/\sqrt{n} + \eta (\log n-\log \log n)/n^{3/2}$ we find an
infinite sequence of nested critical points for the variance behavior of the
normalized partition function. In the subcritical cases $\widehat{\beta} \leq
\kappa$ and $\alpha \leq \eta$ this analysis is extended to a central limit
theorem result for the fluctuations of the normalized partition function.


title:
Clustering of neural codewords revealed by a first-order phase
  transition

abstract:
  A network of neurons in the central nervous system collectively represents
information by its spiking activity states. Typically observed states, i.e.,
codewords, occupy only a limited portion of the state space due to constraints
imposed by network interactions. Geometrical organization of codewords in the
state space, critical for neural information processing, is poorly understood
due to its high dimensionality. Here, we explore the organization of neural
codewords using retinal data by computing the entropy of codewords as a
function of Hamming distance from a particular reference codeword.
Specifically, we report that the retinal codewords in the state space are
divided into multiple distinct clusters separated by entropy-gaps, and that
this structure is shared with well-known associative memory networks in a
recallable phase. Our analysis also elucidates a special nature of the
all-silent state. The all-silent state is surrounded by the densest cluster of
codewords and located within a reachable distance from most codewords. This
codeword-space structure quantitatively predicts typical deviation of a
state-trajectory from its initial state. Altogether, our findings reveal a
non-trivial heterogeneous structure of the codeword-space that shapes
information representation in a biological network.


title: Fayers' conjecture and the socles of cyclotomic Weyl modules

abstract:
  Gordon James proved that the socle of a Weyl module of a classical Schur
algebra is a sum of simple modules labelled by $p$-restricted partitions. We
prove an analogue of this result in the very general setting of "Schur pairs".
As an application we show that the socle of a Weyl module of a cyclotomic
$q$-Schur algebra is a sum of simple modules labelled by Kleshchev
multipartitions and we use this result to prove a conjecture of Fayers that
leads to an efficient LLT algorithm for the higher level cyclotomic Hecke
algebras of type $A$. Finally, we prove a cyclotomic analogue of the
Carter-Lusztig theorem.


title: Denoising and Covariance Estimation of Single Particle Cryo-EM Images

abstract:
  The problem of image restoration in cryo-EM entails correcting for the
effects of the Contrast Transfer Function (CTF) and noise. Popular methods for
image restoration include `phase flipping', which corrects only for the Fourier
phases but not amplitudes, and Wiener filtering, which requires the spectral
signal to noise ratio. We propose a new image restoration method which we call
`Covariance Wiener Filtering' (CWF). In CWF, the covariance matrix of the
projection images is used within the classical Wiener filtering framework for
solving the image restoration deconvolution problem. Our estimation procedure
for the covariance matrix is new and successfully corrects for the CTF. We
demonstrate the efficacy of CWF by applying it to restore both simulated and
experimental cryo-EM images. Results with experimental datasets demonstrate
that CWF provides a good way to evaluate the particle images and to see what
the dataset contains even without 2D classification and averaging.


title: Valley and spin pump by scattering at non-magnetic disorders

abstract:
  In solid, the crystalline structure can endow electron an internal degree of
freedom known as valley, which characterizes the degenerate energy minima in
momentum space. The recent success in optical pumping of valley polarization in
2D transition metal dichalcogenides (TMDs) has greatly promoted the concept of
valley-based informatics and electronics. However, between the demonstrated
valley polarization of transient electron-hole pair excitations and practical
valleytronic operations, there exist obvious gaps to fill, among which is the
valley pump of long-lived charge carriers. Here we discover that the quested
valley pump of electrons or holes can be realized simply by scattering at the
ubiquitous nonmagnetic disorders, not relying on any specific material
property. The mechanism is rooted in the nature of valley as a momentum space
index: the intervalley backscattering in general has valley contrasted rate due
to the distinct momentum transfers, causing a net transfer of population from
one valley to another. As examples, we numerically demonstrate the sizable
valley pump effects driven by charge current in nanoribbons of monolayer TMDs,
where the spin-orbit scattering by non-magnetic disorders also realizes spin
pump for the spin-valley locked holes. Our finding points to an unexpected new
opportunity towards valley-spintronics, turning disorders from a deleterious
factor to a resource of valley and spin polarization.