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Title: Parallel Implementation of Efficient Search Schemes for the Inference of Cancer Progression Models,
Abstract: The emergence and development of cancer is a consequence of the accumulation
over time of genomic mutations involving a specific set of genes, which
provides the cancer clones with a functional selective advantage. In this work,
we model the order of accumulation of such mutations during the progression,
which eventually leads to the disease, by means of probabilistic graphic
models, i.e., Bayesian Networks (BNs). We investigate how to perform the task
of learning the structure of such BNs, according to experimental evidence,
adopting a global optimization meta-heuristics. In particular, in this work we
rely on Genetic Algorithms, and to strongly reduce the execution time of the
inference -- which can also involve multiple repetitions to collect
statistically significant assessments of the data -- we distribute the
calculations using both multi-threading and a multi-node architecture. The
results show that our approach is characterized by good accuracy and
specificity; we also demonstrate its feasibility, thanks to a 84x reduction of
the overall execution time with respect to a traditional sequential
implementation. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: A note on the paper "Contraction mappings in $b$-metric spaces" by Czerwik,
Abstract: In this paper we correct an inaccuracy that appears in the proof of Theorem
1. in Czerwik's article "Contraction mappings in $b$-metric spaces.", Acta
Math. Inform. Univ. Ostraviensis, 1:5--11, 1993. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Playing Music in Just Intonation - A Dynamically Adapting Tuning Scheme,
Abstract: We investigate a dynamically adapting tuning scheme for microtonal tuning of
musical instruments, allowing the performer to play music in just intonation in
any key. Unlike other methods, which are based on a procedural analysis of the
chordal structure, the tuning scheme continually solves a system of linear
equations without making explicit decisions. In complex situations, where not
all intervals of a chord can be tuned according to just frequency ratios, the
method automatically yields a tempered compromise. We outline the
implementation of the algorithm in an open-source software project that we have
provided in order to demonstrate the feasibility of the tuning method. | [
0,
1,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: BLADYG: A Graph Processing Framework for Large Dynamic Graphs,
Abstract: Recently, distributed processing of large dynamic graphs has become very
popular, especially in certain domains such as social network analysis, Web
graph analysis and spatial network analysis. In this context, many
distributed/parallel graph processing systems have been proposed, such as
Pregel, GraphLab, and Trinity. These systems can be divided into two
categories: (1) vertex-centric and (2) block-centric approaches. In
vertex-centric approaches, each vertex corresponds to a process, and message
are exchanged among vertices. In block-centric approaches, the unit of
computation is a block, a connected subgraph of the graph, and message
exchanges occur among blocks. In this paper, we are considering the issues of
scale and dynamism in the case of block-centric approaches. We present bladyg,
a block-centric framework that addresses the issue of dynamism in large-scale
graphs. We present an implementation of BLADYG on top of akka framework. We
experimentally evaluate the performance of the proposed framework. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Electronic and atomic kinetics in solids irradiated with free-electron lasers or swift-heavy ions,
Abstract: In this brief review we discuss the transient processes in solids under
irradiation with femtosecond X-ray free-electron-laser (FEL) pulses and
swift-heavy ions (SHI). Both kinds of irradiation produce highly excited
electrons in a target on extremely short timescales. Transfer of the excess
electronic energy into the lattice may lead to observable target modifications
such as phase transitions and damage formation. Transient kinetics of material
excitation and relaxation under FEL or SHI irradiation are comparatively
discussed. The same origin for the electronic and atomic relaxation in both
cases is demonstrated. Differences in these kinetics introduced by the
geometrical effects ({\mu}m-size of a laser spot vs nm-size of an ion track)
and initial irradiation (photoabsorption vs an ion impact) are analyzed. The
basic mechanisms of electron transport and electron-lattice coupling are
addressed. Appropriate models and their limitations are presented.
Possibilities of thermal and nonthermal melting of materials under FEL and SHI
irradiation are discussed. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: A Functional Taxonomy of Music Generation Systems,
Abstract: Digital advances have transformed the face of automatic music generation
since its beginnings at the dawn of computing. Despite the many breakthroughs,
issues such as the musical tasks targeted by different machines and the degree
to which they succeed remain open questions. We present a functional taxonomy
for music generation systems with reference to existing systems. The taxonomy
organizes systems according to the purposes for which they were designed. It
also reveals the inter-relatedness amongst the systems. This design-centered
approach contrasts with predominant methods-based surveys and facilitates the
identification of grand challenges to set the stage for new breakthroughs. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Covariant representations for singular actions on C*-algebras,
Abstract: Singular actions on C*-algebras are automorphic group actions on C*-algebras,
where the group need not be locally compact, or the action need not be strongly
continuous. We study the covariant representation theory of such actions. In
the usual case of strongly continuous actions of locally compact groups on
C*-algebras, this is done via crossed products, but this approach is not
available for singular C*-actions (this was our path in a previous paper). The
literature regarding covariant representations for singular actions is already
large and scattered, and in need of some consolidation. We collect in this
survey a range of results in this field, mostly known. We improve some proofs
and elucidate some interconnections. These include existence theorems by
Borchers and Halpern, Arveson spectra, the Borchers-Arveson theorem, standard
representations and Stinespring dilations as well as ground states, KMS states
and ergodic states and the spatial structure of their GNS representations. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Astrophysical signatures of leptonium,
Abstract: More than 10^43 positrons annihilate every second in the centre of our Galaxy
yet, despite four decades of observations, their origin is still unknown. Many
candidates have been proposed, such as supernovae and low mass X-ray binaries.
However, these models are difficult to reconcile with the distribution of
positrons, which are highly concentrated in the Galactic bulge, and therefore
require specific propagation of the positrons through the interstellar medium.
Alternative sources include dark matter decay, or the supermassive black hole,
both of which would have a naturally high bulge-to-disc ratio.
The chief difficulty in reconciling models with the observations is the
intrinsically poor angular resolution of gamma-ray observations, which cannot
resolve point sources. Essentially all of the positrons annihilate via the
formation of positronium. This gives rise to the possibility of observing
recombination lines of positronium emitted before the atom annihilates. These
emission lines would be in the UV and the NIR, giving an increase in angular
resolution of a factor of 10^4 compared to gamma ray observations, and allowing
the discrimination between point sources and truly diffuse emission.
Analogously to the formation of positronium, it is possible to form atoms of
true muonium and true tauonium. Since muons and tauons are intrinsically
unstable, the formation of such leptonium atoms will be localised to their
places of origin. Thus observations of true muonium or true tauonium can
provide another way to distinguish between truly diffuse sources such as dark
matter decay, and an unresolved distribution of point sources. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Enhancing Stratified Graph Sampling Algorithms based on Approximate Degree Distribution,
Abstract: Sampling technique has become one of the recent research focuses in the
graph-related fields. Most of the existing graph sampling algorithms tend to
sample the high degree or low degree nodes in the complex networks because of
the characteristic of scale-free. Scale-free means that degrees of different
nodes are subject to a power law distribution. So, there is a significant
difference in the degrees between the overall sampling nodes. In this paper, we
propose an idea of approximate degree distribution and devise a stratified
strategy using it in the complex networks. We also develop two graph sampling
algorithms combining the node selection method with the stratified strategy.
The experimental results show that our sampling algorithms preserve several
properties of different graphs and behave more accurately than other
algorithms. Further, we prove the proposed algorithms are superior to the
off-the-shelf algorithms in terms of the unbiasedness of the degrees and more
efficient than state-of-the-art FFS and ES-i algorithms. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Landau Damping of Beam Instabilities by Electron Lenses,
Abstract: Modern and future particle accelerators employ increasingly higher intensity
and brighter beams of charged particles and become operationally limited by
coherent beam instabilities. Usual methods to control the instabilities, such
as octupole magnets, beam feedback dampers and use of chromatic effects, become
less effective and insufficient. We show that, in contrast, Lorentz forces of a
low-energy, a magnetically stabilized electron beam, or "electron lens", easily
introduces transverse nonlinear focusing sufficient for Landau damping of
transverse beam instabilities in accelerators. It is also important that,
unlike other nonlinear elements, the electron lens provides the frequency
spread mainly at the beam core, thus allowing much higher frequency spread
without lifetime degradation. For the parameters of the Future Circular
Collider, a single conventional electron lens a few meters long would provide
stabilization superior to tens of thousands of superconducting octupole
magnets. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Accelerated Gossip via Stochastic Heavy Ball Method,
Abstract: In this paper we show how the stochastic heavy ball method (SHB) -- a popular
method for solving stochastic convex and non-convex optimization problems
--operates as a randomized gossip algorithm. In particular, we focus on two
special cases of SHB: the Randomized Kaczmarz method with momentum and its
block variant. Building upon a recent framework for the design and analysis of
randomized gossip algorithms, [Loizou Richtarik, 2016] we interpret the
distributed nature of the proposed methods. We present novel protocols for
solving the average consensus problem where in each step all nodes of the
network update their values but only a subset of them exchange their private
values. Numerical experiments on popular wireless sensor networks showing the
benefits of our protocols are also presented. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Attention-Based Models for Text-Dependent Speaker Verification,
Abstract: Attention-based models have recently shown great performance on a range of
tasks, such as speech recognition, machine translation, and image captioning
due to their ability to summarize relevant information that expands through the
entire length of an input sequence. In this paper, we analyze the usage of
attention mechanisms to the problem of sequence summarization in our end-to-end
text-dependent speaker recognition system. We explore different topologies and
their variants of the attention layer, and compare different pooling methods on
the attention weights. Ultimately, we show that attention-based models can
improves the Equal Error Rate (EER) of our speaker verification system by
relatively 14% compared to our non-attention LSTM baseline model. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Experimental Investigation of Optimum Beam Size for FSO Uplink,
Abstract: In this paper, the effect of transmitter beam size on the performance of free
space optical (FSO) communication has been determined experimentally.
Irradiance profile for varying turbulence strength is obtained using optical
turbulence generating (OTG) chamber inside laboratory environment. Based on the
results, an optimum beam size is investigated using the semi-analytical method.
Moreover, the combined effects of atmospheric scintillation and beam wander
induced pointing errors are considered in order to determine the optimum beam
size that minimizes the bit error rate (BER) of the system for a fixed
transmitter power and link length. The results show that the optimum beam size
increases with the increase in zenith angle but has negligible effect with the
increase in fade threshold level at low turbulence levels and has a marginal
effect at high turbulence levels. Finally, the obtained outcome is useful for
FSO system design and BER performance analysis. | [
1,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: The role of surface water in the geometry of Mars' valley networks and its climatic implications,
Abstract: Mars' surface bears the imprint of valley networks formed billions of years
ago and their relicts can still be observed today. However, whether these
networks were formed by groundwater sapping, ice melt, or fluvial runoff has
been continuously debated. These different scenarios have profoundly different
implications for Mars' climatic history, and thus for its habitability in the
distant past. Recent studies on Earth revealed that channel networks in arid
landscapes with more surface runoff branch at narrower angles, while in humid
environments with more groundwater flow, branching angles are much wider. We
find that valley networks on Mars generally tend to branch at narrow angles
similar to those found in arid landscapes on Earth. This result supports the
inference that Mars once had an active hydrologic cycle and that Mars' valley
networks were formed primarily by overland flow erosion with groundwater
seepage playing only a minor role. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: An All-in-One Network for Dehazing and Beyond,
Abstract: This paper proposes an image dehazing model built with a convolutional neural
network (CNN), called All-in-One Dehazing Network (AOD-Net). It is designed
based on a re-formulated atmospheric scattering model. Instead of estimating
the transmission matrix and the atmospheric light separately as most previous
models did, AOD-Net directly generates the clean image through a light-weight
CNN. Such a novel end-to-end design makes it easy to embed AOD-Net into other
deep models, e.g., Faster R-CNN, for improving high-level task performance on
hazy images. Experimental results on both synthesized and natural hazy image
datasets demonstrate our superior performance than the state-of-the-art in
terms of PSNR, SSIM and the subjective visual quality. Furthermore, when
concatenating AOD-Net with Faster R-CNN and training the joint pipeline from
end to end, we witness a large improvement of the object detection performance
on hazy images. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Belitskii's canonical forms of linear dynamical systems,
Abstract: In the note, all indecomposable canonical forms of linear systems with
dimension less than or equal to $4$ are determined based on Belitskii's
algorithm. As an application, an effective way to calculate dimensions of
equivalence classes of linear systems is given by using Belitskii's canonical
forms. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: The Geometry of Nodal Sets and Outlier Detection,
Abstract: Let $(M,g)$ be a compact manifold and let $-\Delta \phi_k = \lambda_k \phi_k$
be the sequence of Laplacian eigenfunctions. We present a curious new
phenomenon which, so far, we only managed to understand in a few highly
specialized cases: the family of functions $f_N:M \rightarrow \mathbb{R}_{\geq
0}$ $$ f_N(x) = \sum_{k \leq N}{ \frac{1}{\sqrt{\lambda_k}}
\frac{|\phi_k(x)|}{\|\phi_k\|_{L^{\infty}(M)}}}$$ seems strangely suited for
the detection of anomalous points on the manifold. It may be heuristically
interpreted as the sum over distances to the nearest nodal line and potentially
hints at a new phenomenon in spectral geometry. We give rigorous statements on
the unit square $[0,1]^2$ (where minima localize in $\mathbb{Q}^2$) and on
Paley graphs (where $f_N$ recovers the geometry of quadratic residues of the
underlying finite field $\mathbb{F}_p$). Numerical examples show that the
phenomenon seems to arise on fairly generic manifolds. | [
0,
0,
1,
1,
0,
0
] | [
"Mathematics",
"Statistics"
] |
Title: Multimodal Clustering for Community Detection,
Abstract: Multimodal clustering is an unsupervised technique for mining interesting
patterns in $n$-adic binary relations or $n$-mode networks. Among different
types of such generalized patterns one can find biclusters and formal concepts
(maximal bicliques) for 2-mode case, triclusters and triconcepts for 3-mode
case, closed $n$-sets for $n$-mode case, etc. Object-attribute biclustering
(OA-biclustering) for mining large binary datatables (formal contexts or 2-mode
networks) arose by the end of the last decade due to intractability of
computation problems related to formal concepts; this type of patterns was
proposed as a meaningful and scalable approximation of formal concepts. In this
paper, our aim is to present recent advance in OA-biclustering and its
extensions to mining multi-mode communities in SNA setting. We also discuss
connection between clustering coefficients known in SNA community for 1-mode
and 2-mode networks and OA-bicluster density, the main quality measure of an
OA-bicluster. Our experiments with 2-, 3-, and 4-mode large real-world networks
show that this type of patterns is suitable for community detection in
multi-mode cases within reasonable time even though the number of corresponding
$n$-cliques is still unknown due to computation difficulties. An interpretation
of OA-biclusters for 1-mode networks is provided as well. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Identification of a space varying coefficient of a linear viscoelastic string of Maxwell-Boltzman type,
Abstract: In this paper we solve the problem of the identification of a coefficient
which appears in the model of a distributed system with persistent memory
encountered in linear viscoelasticity (and in diffusion processes with memory).
The additional data used in the identification are subsumed in the input output
map from the deformation to the traction on the boundary. We extend a dynamical
approach to identification introduced by Belishev in the case of purely elastic
(memoryless) bodies and based on a special equation due to Blagoveshchenskii.
So, in particular, we extend Blagoveshchenskii equation to our class of systems
with persistent memory. | [
1,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Efficient four-wave mixing at the nanofocus of integrated organic gap plasmon waveguides on silicon,
Abstract: Nonlinear optics, especially frequency mixing, underpins modern optical
technology and scientific exploration in quantum optics, materials and life
sciences, and optical communications. Since nonlinear effects are weak,
efficient frequency mixing must accumulate over large interaction lengths
restricting the integration of nonlinear photonics with electronics and
establishing limitations on mixing processes due to the requirement of phase
matching. In this work we report efficient four-wave mixing over micron-scale
interaction lengths at telecoms wavelengths. We use an integrated plasmonic gap
waveguide on silicon that strongly confines light within a nonlinear organic
polymer in the gap. Our approach is so effective because the gap waveguide
intensifies light by efficiently nanofocusing it to a mode cross-section of a
few tens of nanometres, generating a nonlinear response so strong that
efficient four-wave mixing accumulates in just a micron. This is significant as
our technique opens up nonlinear optics to a regime where phase matching and
dispersion considerations are relaxed, giving rise to the possibility of
compact, broadband, and efficient frequency mixing on a platform that can be
integrated with silicon photonics. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Does agricultural subsidies foster Italian southern farms? A Spatial Quantile Regression Approach,
Abstract: During the last decades, public policies become a central pillar in
supporting and stabilising agricultural sector. In 1962, EU policy-makers
developed the so-called Common Agricultural Policy (CAP) to ensure
competitiveness and a common market organisation for agricultural products,
while 2003 reform decouple the CAP from the production to focus only on income
stabilization and the sustainability of agricultural sector. Notwithstanding
farmers are highly dependent to public support, literature on the role played
by the CAP in fostering agricultural performances is still scarce and
fragmented. Actual CAP policies increases performance differentials between
Northern Central EU countries and peripheral regions. This paper aims to
evaluate the effectiveness of CAP in stimulate performances by focusing on
Italian lagged Regions. Moreover, agricultural sector is deeply rooted in
place-based production processes. In this sense, economic analysis which omit
the presence of spatial dependence produce biased estimates of the
performances. Therefore, this paper, using data on subsidies and economic
results of farms from the RICA dataset which is part of the Farm Accountancy
Data Network (FADN), proposes a spatial Augmented Cobb-Douglas Production
Function to evaluate the effects of subsidies on farm's performances. The major
innovation in this paper is the implementation of a micro-founded quantile
version of a spatial lag model to examine how the impact of the subsidies may
vary across the conditional distribution of agricultural performances. Results
show an increasing shape which switch from negative to positive at the median
and becomes statistical significant for higher quantiles. Additionally, spatial
autocorrelation parameter is positive and significant across all the
conditional distribution, suggesting the presence of significant spatial
spillovers in agricultural performances. | [
0,
0,
0,
1,
0,
0
] | [
"Statistics",
"Quantitative Finance"
] |
Title: Proton fire hose instabilities in the expanding solar wind,
Abstract: Using two-dimensional hybrid expanding box simulations we study the
competition between the continuously driven parallel proton temperature
anisotropy and fire hose instabilities in collisionless homogeneous plasmas.
For quasi radial ambient magnetic field the expansion drives
$T_{\mathrm{p}\|}>T_{\mathrm{p}\perp}$ and the system becomes eventually
unstable with respect to the dominant parallel fire hose instability. This
instability is generally unable to counteract the induced anisotropization and
the system typically becomes unstable with respect to the oblique fire hose
instability later on. The oblique instability efficiently reduces the
anisotropy and the system rapidly stabilizes while a significant part of the
generated electromagnetic fluctuations is damped to protons. As long as the
magnetic field is in the quasi radial direction, this evolution repeats itself
and the electromagnetic fluctuations accumulate. For sufficiently oblique
magnetic field the expansion drives $T_{\mathrm{p}\perp}>T_{\mathrm{p}\|}$ and
brings the system to the stable region with respect to the fire hose
instabilities. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Cold-Start Reinforcement Learning with Softmax Policy Gradient,
Abstract: Policy-gradient approaches to reinforcement learning have two common and
undesirable overhead procedures, namely warm-start training and sample variance
reduction. In this paper, we describe a reinforcement learning method based on
a softmax value function that requires neither of these procedures. Our method
combines the advantages of policy-gradient methods with the efficiency and
simplicity of maximum-likelihood approaches. We apply this new cold-start
reinforcement learning method in training sequence generation models for
structured output prediction problems. Empirical evidence validates this method
on automatic summarization and image captioning tasks. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Implicit Cooperative Positioning in Vehicular Networks,
Abstract: Absolute positioning of vehicles is based on Global Navigation Satellite
Systems (GNSS) combined with on-board sensors and high-resolution maps. In
Cooperative Intelligent Transportation Systems (C-ITS), the positioning
performance can be augmented by means of vehicular networks that enable
vehicles to share location-related information. This paper presents an Implicit
Cooperative Positioning (ICP) algorithm that exploits the Vehicle-to-Vehicle
(V2V) connectivity in an innovative manner, avoiding the use of explicit V2V
measurements such as ranging. In the ICP approach, vehicles jointly localize
non-cooperative physical features (such as people, traffic lights or inactive
cars) in the surrounding areas, and use them as common noisy reference points
to refine their location estimates. Information on sensed features are fused
through V2V links by a consensus procedure, nested within a message passing
algorithm, to enhance the vehicle localization accuracy. As positioning does
not rely on explicit ranging information between vehicles, the proposed ICP
method is amenable to implementation with off-the-shelf vehicular communication
hardware. The localization algorithm is validated in different traffic
scenarios, including a crossroad area with heterogeneous conditions in terms of
feature density and V2V connectivity, as well as a real urban area by using
Simulation of Urban MObility (SUMO) for traffic data generation. Performance
results show that the proposed ICP method can significantly improve the vehicle
location accuracy compared to the stand-alone GNSS, especially in harsh
environments, such as in urban canyons, where the GNSS signal is highly
degraded or denied. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: A Generalized Accelerated Composite Gradient Method: Uniting Nesterov's Fast Gradient Method and FISTA,
Abstract: We demonstrate that the augmented estimate sequence framework unites the most
popular primal first-order schemes for large-scale problems: the Fast Gradient
Method (FGM) and the Fast Iterative Shrinkage Thresholding Algorithm (FISTA).
We further showcase the flexibility of the augmented estimate sequence by
deriving a Generalized Accelerated Composite Gradient Method endowed with
monotonicity alongside a versatile line-search procedure. The new method
surpasses both FGM and FISTA in terms of robustness and usability. In
particular, it is guaranteed to converge without requiring any quantitative
prior information on the problem. Additional information, if available, leads
to an improvement in performance at least on par with the state-of-the-art. We
support our findings with simulation results. | [
0,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Lorentz covariant and gauge invariant description of orbital and spin angular momentum and the non-symmetric energy momentum tensor,
Abstract: Starting from covariant expressions, a gauge independent separation of
orbital and spin angular momentum for electrodynamics is presented. This
results from the non-symmetric canonical energy momentum tensor of the
electromagnetic field. The origin of the difficulty is discussed and a
covariant gauge invariant spin vector is derived. The paradox concerning the
spin angular momentum of a plane wave finds a natural solution. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Dirichlet's theorem and Jacobsthal's function,
Abstract: If $a$ and $d$ are relatively prime, we refer to the set of integers
congruent to $a$ mod $d$ as an `eligible' arithmetic progression. A theorem of
Dirichlet says that every eligible arithmetic progression contains infinitely
many primes; the theorem follows from the assertion that every eligible
arithmetic progression contains at least one prime. The Jacobsthal function
$g(n)$ is defined as the smallest positive integer such that every sequence of
$g(n)$ consecutive integers contains an integer relatively prime to $n$. In
this paper, we show by a combinatorial argument that every eligible arithmetic
progression with $d\le76$ contains at least one prime, and we show that certain
plausible bounds on the Jacobsthal function of primorials would imply that
every eligible arithmetic progression contains at least one prime. That is,
certain plausible bounds on the Jacobsthal function would lead to an elementary
proof of Dirichlet's theorem. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Large Scale Replication Projects in Contemporary Psychological Research,
Abstract: Replication is complicated in psychological research because studies of a
given psychological phenomenon can never be direct or exact replications of one
another, and thus effect sizes vary from one study of the phenomenon to the
next--an issue of clear importance for replication. Current large scale
replication projects represent an important step forward for assessing
replicability, but provide only limited information because they have thus far
been designed in a manner such that heterogeneity either cannot be assessed or
is intended to be eliminated. Consequently, the non-trivial degree of
heterogeneity found in these projects represents a lower bound on
heterogeneity. We recommend enriching large scale replication projects going
forward by em- bracing heterogeneity. We argue this is key for assessing
replicability: if effect sizes are sufficiently heterogeneous--even if the sign
of the effect is consistent--the phenomenon in question does not seem
particularly replicable and the theory underlying it seems poorly constructed
and in need of enrichment. Uncovering why and revising theory in light of it
will lead to improved theory that explains heterogeneity and in- creases
replicability. Given this, large scale replication projects can play an
important role not only in assessing replicability but also in advancing
theory. | [
0,
0,
0,
1,
0,
0
] | [
"Statistics",
"Quantitative Biology"
] |
Title: Labeled homology of higher-dimensional automata,
Abstract: We construct labeling homomorphisms on the cubical homology of
higher-dimensional automata and show that they are natural with respect to
cubical dimaps and compatible with the tensor product of HDAs. We also indicate
two possible applications of labeled homology in concurrency theory. | [
1,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Magnetic Actuation and Feedback Cooling of a Cavity Optomechanical Torque Sensor,
Abstract: We demonstrate the integration of a mesoscopic ferromagnetic needle with a
cavity optomechanical torsional resonator, and its use for quantitative
determination of the needle's magnetic properties, as well as amplification and
cooling of the resonator motion. With this system we measure torques as small
as 32 zNm, corresponding to sensing an external magnetic field of 0.12 A/m (150
nT). Furthermore, we are able to extract the magnetization (1710 kA/m) of the
magnetic sample, not known a priori, demonstrating this system's potential for
studies of nanomagnetism. Finally, we show that we can magnetically drive the
torsional resonator into regenerative oscillations, and dampen its mechanical
mode temperature from room temperature to 11.6 K, without sacrificing torque
sensitivity. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Bäcklund Transformations for the Boussinesq Equation and Merging Solitons,
Abstract: The Bäcklund transformation (BT) for the "good" Boussinesq equation and its
superposition principles are presented and applied. Unlike many other standard
integrable equations, the Boussinesq equation does not have a strictly
algebraic superposition principle for 2 BTs, but it does for 3. We present
associated lattice systems. Applying the BT to the trivial solution generates
standard solitons but also what we call "merging solitons" --- solutions in
which two solitary waves (with related speeds) merge into a single one. We use
the superposition principles to generate a variety of interesting solutions,
including superpositions of a merging soliton with $1$ or $2$ regular solitons,
and solutions that develop a singularity in finite time which then disappears
at some later finite time. We prove a Wronskian formula for the solutions
obtained by applying a general sequence of BTs on the trivial solution.
Finally, we show how to obtain the standard conserved quantities of the
Boussinesq equation from the BT, and how the hierarchy of local symmetries
follows in a simple manner from the superposition principle for 3 BTs. | [
0,
1,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Towards Evolutional Compression,
Abstract: Compressing convolutional neural networks (CNNs) is essential for
transferring the success of CNNs to a wide variety of applications to mobile
devices. In contrast to directly recognizing subtle weights or filters as
redundant in a given CNN, this paper presents an evolutionary method to
automatically eliminate redundant convolution filters. We represent each
compressed network as a binary individual of specific fitness. Then, the
population is upgraded at each evolutionary iteration using genetic operations.
As a result, an extremely compact CNN is generated using the fittest
individual. In this approach, either large or small convolution filters can be
redundant, and filters in the compressed network are more distinct. In
addition, since the number of filters in each convolutional layer is reduced,
the number of filter channels and the size of feature maps are also decreased,
naturally improving both the compression and speed-up ratios. Experiments on
benchmark deep CNN models suggest the superiority of the proposed algorithm
over the state-of-the-art compression methods. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Brunn-Minkowski inequalities in product metric measure spaces,
Abstract: Given one metric measure space $X$ satisfying a linear Brunn-Minkowski
inequality, and a second one $Y$ satisfying a Brunn-Minkowski inequality with
exponent $p\ge -1$, we prove that the product $X\times Y$ with the standard
product distance and measure satisfies a Brunn-Minkowski inequality of order
$1/(1+p^{-1})$ under mild conditions on the measures and the assumption that
the distances are strictly intrinsic. The same result holds when we consider
restricted classes of sets. We also prove that a linear Brunn-Minkowski
inequality is obtained in $X\times Y$ when $Y$ satisfies a Prékopa-Leindler
inequality.
In particular, we show that the classical Brunn-Minkowski inequality holds
for any pair of weakly unconditional sets in $\mathbb{R}^n$ (i.e., those
containing the projection of every point in the set onto every coordinate
subspace) when we consider the standard distance and the product measure of $n$
one-dimensional real measures with positively decreasing densities. This yields
an improvement of the class of sets satisfying the Gaussian Brunn-Minkowski
inequality.
Furthermore, associated isoperimetric inequalities as well as recently
obtained Brunn-Minkowski's inequalities are derived from our results. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Deep Learning with Low Precision by Half-wave Gaussian Quantization,
Abstract: The problem of quantizing the activations of a deep neural network is
considered. An examination of the popular binary quantization approach shows
that this consists of approximating a classical non-linearity, the hyperbolic
tangent, by two functions: a piecewise constant sign function, which is used in
feedforward network computations, and a piecewise linear hard tanh function,
used in the backpropagation step during network learning. The problem of
approximating the ReLU non-linearity, widely used in the recent deep learning
literature, is then considered. An half-wave Gaussian quantizer (HWGQ) is
proposed for forward approximation and shown to have efficient implementation,
by exploiting the statistics of of network activations and batch normalization
operations commonly used in the literature. To overcome the problem of gradient
mismatch, due to the use of different forward and backward approximations,
several piece-wise backward approximators are then investigated. The
implementation of the resulting quantized network, denoted as HWGQ-Net, is
shown to achieve much closer performance to full precision networks, such as
AlexNet, ResNet, GoogLeNet and VGG-Net, than previously available low-precision
networks, with 1-bit binary weights and 2-bit quantized activations. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Intense automorphisms of finite groups,
Abstract: Let $G$ be a group. An automorphism of $G$ is called intense if it sends each
subgroup of $G$ to a conjugate; the collection of such automorphisms is denoted
by $\mathrm{Int}(G)$. In the special case in which $p$ is a prime number and
$G$ is a finite $p$-group, one can show that $\mathrm{Int}(G)$ is the
semidirect product of a normal $p$-Sylow and a cyclic subgroup of order
dividing $p-1$. In this thesis we classify the finite $p$-groups whose groups
of intense automorphisms are not themselves $p$-groups. It emerges from our
investigation that the structure of such groups is almost completely determined
by their nilpotency class: for $p>3$, they share a quotient, growing with their
class, with a uniquely determined infinite $2$-generated pro-$p$ group. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Experimental Determination of the Structural Coefficient of Restitution of a Bouncing Asteroid Lander,
Abstract: The structural coefficient of restitution describes the kinetic energy
dissipation upon low-velocity (~0.1 m/s) impact of a small asteroid lander,
MASCOT, against a hard, ideally elastic plane surface. It is a crucial
worst-case input for mission analysis for landing MACOT on a 1km asteroid in
2018. We conducted pendulum tests and describe their analysis and the results. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Controller Synthesis for Discrete-Time Polynomial Systems via Occupation Measures,
Abstract: In this paper, we design nonlinear state feedback controllers for
discrete-time polynomial dynamical systems via the occupation measure approach.
We propose the discrete-time controlled Liouville equation, and use it to
formulate the controller synthesis problem as an infinite-dimensional linear
programming problem on measures, which is then relaxed as finite-dimensional
semidefinite programming problems on moments of measures and their duals on
sums-of-squares polynomials. Nonlinear controllers can be extracted from the
solutions to the relaxed problems. The advantage of the occupation measure
approach is that we solve convex problems instead of generally non-convex
problems, and the computational complexity is polynomial in the state and input
dimensions, and hence the approach is more scalable. In addition, we show that
the approach can be applied to over-approximating the backward reachable set of
discrete-time autonomous polynomial systems and the controllable set of
discrete-time polynomial systems under known state feedback control laws. We
illustrate our approach on several dynamical systems. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: A three-dimensional symmetry result for a phase transition equation in the genuinely nonlocal regime,
Abstract: We consider bounded solutions of the nonlocal Allen-Cahn equation $$
(-\Delta)^s u=u-u^3\qquad{\mbox{ in }}{\mathbb{R}}^3,$$ under the monotonicity
condition $\partial_{x_3}u>0$ and in the genuinely nonlocal regime in
which~$s\in\left(0,\frac12\right)$. Under the limit assumptions $$
\lim_{x_n\to-\infty} u(x',x_n)=-1\quad{\mbox{ and }}\quad \lim_{x_n\to+\infty}
u(x',x_n)=1,$$ it has been recently shown that~$u$ is necessarily $1$D, i.e. it
depends only on one Euclidean variable. The goal of this paper is to obtain a
similar result without assuming such limit conditions. This type of results can
be seen as nonlocal counterparts of the celebrated conjecture formulated by
Ennio De Giorgi. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: The growth of bismuth on Bi$_2$Se$_3$ and the stability of the first bilayer,
Abstract: Bi(0001) films with thicknesses up to several bilayers (BLs) are grown on
Se-terminated Bi$_2$Se$_3$(0001) surfaces, and low energy electron diffraction
(LEED), low energy ion scattering (LEIS) and atomic force microscopy (AFM) are
used to investigate the surface composition, topography and atomic structure.
For a single deposited Bi BL, the lattice constant matches that of the
substrate and the Bi atoms adjacent to the uppermost Se atoms are located at
fcc-like sites. When a 2nd Bi bilayer is deposited, it is incommensurate with
the substrate. As the thickness of the deposited Bi film increases further, the
lattice parameter evolves to that of bulk Bi(0001). After annealing a multiple
BL film at 120°C, the first commensurate Bi BL remains intact, but the
additional BLs aggregate to form thicker islands of Bi. These results show that
a single Bi BL on Bi$_2$Se$_3$ is a particularly stable structure. After
annealing to 490°C, all of the excess Bi desorbs and the Se-terminated
Bi$_2$Se$_3$ surface is restored. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Sampling-based vs. Design-based Uncertainty in Regression Analysis,
Abstract: Consider a researcher estimating the parameters of a regression function
based on data for all 50 states in the United States or on data for all visits
to a website. What is the interpretation of the estimated parameters and the
standard errors? In practice, researchers typically assume that the sample is
randomly drawn from a large population of interest and report standard errors
that are designed to capture sampling variation. This is common practice, even
in applications where it is difficult to articulate what that population of
interest is, and how it differs from the sample. In this article, we explore an
alternative approach to inference, which is partly design-based. In a
design-based setting, the values of some of the regressors can be manipulated,
perhaps through a policy intervention. Design-based uncertainty emanates from
lack of knowledge about the values that the regression outcome would have taken
under alternative interventions. We derive standard errors that account for
design-based uncertainty instead of, or in addition to, sampling-based
uncertainty. We show that our standard errors in general are smaller than the
infinite-population sampling-based standard errors and provide conditions under
which they coincide. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Scalable Joint Models for Reliable Uncertainty-Aware Event Prediction,
Abstract: Missing data and noisy observations pose significant challenges for reliably
predicting events from irregularly sampled multivariate time series
(longitudinal) data. Imputation methods, which are typically used for
completing the data prior to event prediction, lack a principled mechanism to
account for the uncertainty due to missingness. Alternatively, state-of-the-art
joint modeling techniques can be used for jointly modeling the longitudinal and
event data and compute event probabilities conditioned on the longitudinal
observations. These approaches, however, make strong parametric assumptions and
do not easily scale to multivariate signals with many observations. Our
proposed approach consists of several key innovations. First, we develop a
flexible and scalable joint model based upon sparse multiple-output Gaussian
processes. Unlike state-of-the-art joint models, the proposed model can explain
highly challenging structure including non-Gaussian noise while scaling to
large data. Second, we derive an optimal policy for predicting events using the
distribution of the event occurrence estimated by the joint model. The derived
policy trades-off the cost of a delayed detection versus incorrect assessments
and abstains from making decisions when the estimated event probability does
not satisfy the derived confidence criteria. Experiments on a large dataset
show that the proposed framework significantly outperforms state-of-the-art
techniques in event prediction. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Nano-optical imaging of monolayer MoSe2 using tip-enhanced photoluminescence,
Abstract: Band gap tuning in two-dimensional transitional metal dichalcogenides (TMDs)
is crucial in fabricating new optoelectronic devices. High resolution
photoluminescence (PL) microscopy is needed for accurate band gap
characterization. We performed tip-enhanced photoluminescence (TEPL)
measurements of monolayer MoSe2 with nanoscale spatial resolution, providing an
improved characterization of the band gap correlated with the topography
compared with the conventional far field spectroscopy. We also observed PL
shifts at the edges and investigated the spatial dependence of the TEPL
enhancement factors. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Online classification of imagined speech using functional near-infrared spectroscopy signals,
Abstract: Most brain-computer interfaces (BCIs) based on functional near-infrared
spectroscopy (fNIRS) require that users perform mental tasks such as motor
imagery, mental arithmetic, or music imagery to convey a message or to answer
simple yes or no questions. These cognitive tasks usually have no direct
association with the communicative intent, which makes them difficult for users
to perform. In this paper, a 3-class intuitive BCI is presented which enables
users to directly answer yes or no questions by covertly rehearsing the word
'yes' or 'no' for 15 s. The BCI also admits an equivalent duration of
unconstrained rest which constitutes the third discernable task. Twelve
participants each completed one offline block and six online blocks over the
course of 2 sessions. The mean value of the change in oxygenated hemoglobin
concentration during a trial was calculated for each channel and used to train
a regularized linear discriminant analysis (RLDA) classifier. By the final
online block, 9 out of 12 participants were performing above chance (p<0.001),
with a 3-class accuracy of 83.8+9.4%. Even when considering all participants,
the average online 3-class accuracy over the last 3 blocks was 64.1+20.6%, with
only 3 participants scoring below chance (p<0.001). For most participants,
channels in the left temporal and temporoparietal cortex provided the most
discriminative information. To our knowledge, this is the first report of an
online fNIRS 3-class imagined speech BCI. Our findings suggest that imagined
speech can be used as a reliable activation task for selected users for the
development of more intuitive BCIs for communication. | [
0,
0,
0,
0,
1,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Trace-free characters and abelian knot contact homology II,
Abstract: We calculate ghost characters for the (5,6)-torus knot, and using them we
show that the (5,6)-torus knot gives a counter-example of Ng's conjecture
concerned with the relationship between degree 0 abelian knot contact homology
and the character variety of the 2-fold branched covering of the 3-sphere
branched along the knot. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Surface Plasmon Excitation of Second Harmonic light: Emission and Absorption,
Abstract: We aim to clarify the role that absorption plays in nonlinear optical
processes in a variety of metallic nanostructures and show how it relates to
emission and conversion efficiency. We define a figure of merit that
establishes the structure's ability to either favor or impede second harmonic
generation. Our findings suggest that, despite the best efforts embarked upon
to enhance local fields and light coupling via plasmon excitation, nearly
always the absorbed harmonic energy far surpasses the harmonic energy emitted
in the far field. Qualitative and quantitative understanding of absorption
processes is crucial in the evaluation of practical designs of plasmonic
nanostructures for the purpose of frequency mixing. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Fault diagnosability of data center networks,
Abstract: The data center networks $D_{n,k}$, proposed in 2008, has many desirable
features such as high network capacity. A kind of generalization of
diagnosability for network $G$ is $g$-good-neighbor diagnosability which is
denoted by $t_g(G)$. Let $\kappa^g(G)$ be the $R^g$-connectivity. Lin et. al.
in [IEEE Trans. on Reliability, 65 (3) (2016) 1248--1262] and Xu et. al in
[Theor. Comput. Sci. 659 (2017) 53--63] gave the same problem independently
that: the relationship between the $R^g$-connectivity $\kappa^g(G)$ and
$t_g(G)$ of a general graph $G$ need to be studied in the future. In this
paper, this open problem is solved for general regular graphs. We firstly
establish the relationship of $\kappa^g(G)$ and $t_g(G)$, and obtain that
$t_g(G)=\kappa^g(G)+g$ under some conditions. Secondly, we obtain the
$g$-good-neighbor diagnosability of $D_{k,n}$ which are
$t_g(D_{k,n})=(g+1)(k-1)+n+g$ for $1\leq g\leq n-1$ under the PMC model and the
MM model, respectively. Further more, we show that $D_{k,n}$ is tightly super
$(n+k-1)$-connected for $n\geq 2$ and $k\geq 2$ and we also prove that the
largest connected component of the survival graph contains almost all of the
remaining vertices in $D_{k,n}$ when $2k+n-2$ vertices removed. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: A General Framework of Multi-Armed Bandit Processes by Arm Switch Restrictions,
Abstract: This paper proposes a general framework of multi-armed bandit (MAB) processes
by introducing a type of restrictions on the switches among arms evolving in
continuous time.
The Gittins index process is constructed for any single arm subject to the
restrictions on switches and then the optimality of the corresponding Gittins
index rule is established. The Gittins indices defined in this paper are
consistent with the ones for MAB processes in continuous time, integer time,
semi-Markovian setting as well as general discrete time setting, so that the
new theory covers the classical models as special cases and also applies to
many other situations that have not yet been touched in the literature. While
the proof of the optimality of Gittins index policies benefits from ideas in
the existing theory of MAB processes in continuous time, new techniques are
introduced which drastically simplify the proof. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics",
"Statistics"
] |
Title: Knowledge distillation using unlabeled mismatched images,
Abstract: Current approaches for Knowledge Distillation (KD) either directly use
training data or sample from the training data distribution. In this paper, we
demonstrate effectiveness of 'mismatched' unlabeled stimulus to perform KD for
image classification networks. For illustration, we consider scenarios where
this is a complete absence of training data, or mismatched stimulus has to be
used for augmenting a small amount of training data. We demonstrate that
stimulus complexity is a key factor for distillation's good performance. Our
examples include use of various datasets for stimulating MNIST and CIFAR
teachers. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Structural analysis of rubble-pile asteroids applied to collisional evolution,
Abstract: Solar system small bodies come in a wide variety of shapes and sizes, which
are achieved following very individual evolutional paths through billions of
years. This paper focuses on the reshaping process of rubble-pile asteroids
driven by meteorite impacts. In our study, numerous possible equilibrium
configurations are obtained via Monte Carlo simulation, and the structural
stability of these configurations is determined via eigen analysis of the
geometric constructions. The eigen decomposition reveals a connection between
the cluster's reactions and the types of external disturbance. Numerical
simulations are performed to verify the analytical results. The gravitational
N-body code pkdgrav is used to mimic the responses of the cluster under
intermittent non-dispersive impacts. We statistically confirm that the
stability index, the total gravitational potential and the volume of inertia
ellipsoid show consistent tendency of variation. A common regime is found in
which the clusters tend towards crystallization under intermittent impacts,
i.e., only the configurations with high structural stability survive under the
external disturbances. The results suggest the trivial non-disruptive impacts
might play an important role in the rearrangement of the constituent blocks,
which may strengthen these rubble piles and help to build a robust structure
under impacts of similar magnitude. The final part of this study consists of
systematic simulations over two parameters, the projectile momentum and the
rotational speed of the cluster. The results show a critical value exists for
the projectile momentum, as predicted by theory, below which all clusters
become responseless to external disturbances; and the rotation proves to be
significant for it exhibits an "enhancing" effect on loose-packed clusters,
which coincides with the observation that several fast-spinning asteroids have
low bulk densities. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: The Imani Periodic Functions: Genesis and Preliminary Results,
Abstract: The Leah-Hamiltonian, $H(x,y)=y^2/2+3x^{4/3}/4$, is introduced as a
functional equation for $x(t)$ and $y(t)$. By means of a nonlinear
transformation to new independent variables, we show that this functional
equation has a special class of periodic solutions which we designate the Imani
functions. The explicit construction of these functions is done such that they
possess many of the general properties of the standard trigonometric cosine and
sine functions. We conclude by providing a listing of a number of currently
unresolved issues relating to the Imani functions. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Robust Computation in 2D Absolute EIT (a-EIT) Using D-bar Methods with the `exp' Approximation,
Abstract: Objective: Absolute images have important applications in medical Electrical
Impedance Tomography (EIT) imaging, but the traditional minimization and
statistical based computations are very sensitive to modeling errors and noise.
In this paper, it is demonstrated that D-bar reconstruction methods for
absolute EIT are robust to such errors. Approach: The effects of errors in
domain shape and electrode placement on absolute images computed with 2D D-bar
reconstruction algorithms are studied on experimental data. Main Results: It is
demonstrated with tank data from several EIT systems that these methods are
quite robust to such modeling errors, and furthermore the artefacts arising
from such modeling errors are similar to those occurring in classic
time-difference EIT imaging. Significance: This study is promising for clinical
applications where absolute EIT images are desirable, but previously thought
impossible. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Physics",
"Statistics"
] |
Title: The intrinsic Baldwin effect in broad Balmer lines of six long-term monitored AGNs,
Abstract: We investigate the intrinsic Baldwin effect (Beff) of the broad H$\alpha$ and
H$\beta$ emission lines for six Type 1 active galactic nuclei (AGNs) with
different broad line characteristics: two Seyfert 1 (NGC 4151 and NGC 5548),
two AGNs with double-peaked broad line profiles (3C 390.3 and Arp 102B), one
narrow line Seyfert 1 (Ark 564), and one high-luminosity quasar with highly red
asymmetric broad line profiles (E1821+643). We found that a significant
intrinsic Beff was present in all Type 1 AGNs in our sample. Moreover, we do
not see strong difference in intrinsic Beff slopes in different types of AGNs
which probably have different physical properties, such as inclination, broad
line region geometry, or accretion rate. Additionally, we found that the
intrinsic Beff was not connected with the global one, which, instead, could not
be detected in the broad H$\alpha$ or H$\beta$ emission lines. In the case of
NGC 4151, the detected variation of the Beff slope could be due to the change
in the site of line formation in the BLR. Finally, the intrinsic Beff might be
caused by the additional optical continuum component that is not part of the
ionization continuum. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: A Novel Formal Agent-based Simulation Modeling Framework of an AIDS Complex Adaptive System,
Abstract: HIV/AIDS spread depends upon complex patterns of interaction among various
sub-sets emerging at population level. This added complexity makes it difficult
to study and model AIDS and its dynamics. AIDS is therefore a natural candidate
to be modeled using agent-based modeling, a paradigm well-known for modeling
Complex Adaptive Systems (CAS). While agent-based models are also well-known to
effectively model CAS, often times models can tend to be ambiguous and the use
of purely text-based specifications (such as ODD) can make models difficult to
be replicated. Previous work has shown how formal specification may be used in
conjunction with agent-based modeling to develop models of various CAS.
However, to the best of our knowledge, no such model has been developed in
conjunction with AIDS. In this paper, we present a Formal Agent-Based
Simulation modeling framework (FABS-AIDS) for an AIDS-based CAS. FABS-AIDS
employs the use of a formal specification model in conjunction with an
agent-based model to reduce ambiguity as well as improve clarity in the model
definition. The proposed model demonstrates the effectiveness of using formal
specification in conjunction with agent-based simulation for developing models
of CAS in general and, social network-based agent-based models, in particular. | [
1,
1,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Ion-impact-induced multifragmentation of liquid droplets,
Abstract: An instability of a liquid droplet traversed by an energetic ion is explored.
This instability is brought about by the predicted shock wave induced by the
ion. An observation of multifragmentation of small droplets traversed by ions
with high linear energy transfer is suggested to demonstrate the existence of
shock waves. A number of effects are analysed in effort to find the conditions
for such an experiment to be signifying. The presence of shock waves crucially
affects the scenario of radiation damage with ions since the shock waves
significantly contribute to the thermomechanical damage of biomolecules as well
as the transport of reactive species. While the scenario has been upheld by
analyses of biological experiments, the shock waves have not yet been observed
directly, regardless of a number of ideas of experiments to detect them were
exchanged at conferences. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Quantitative Biology"
] |
Title: The Lyman Continuum escape fraction of faint galaxies at z~3.3 in the CANDELS/GOODS-North, EGS, and COSMOS fields with LBC,
Abstract: The reionization of the Universe is one of the most important topics of
present day astrophysical research. The most plausible candidates for the
reionization process are star-forming galaxies, which according to the
predictions of the majority of the theoretical and semi-analytical models
should dominate the HI ionizing background at z~3. We aim at measuring the
Lyman continuum escape fraction, which is one of the key parameters to compute
the contribution of star-forming galaxies to the UV background. We have used
ultra-deep U-band imaging (U=30.2mag at 1sigma) by LBC/LBT in the
CANDELS/GOODS-North field, as well as deep imaging in COSMOS and EGS fields, in
order to estimate the Lyman continuum escape fraction of 69 star-forming
galaxies with secure spectroscopic redshifts at 3.27<z<3.40 to faint magnitude
limits (L=0.2L*, or equivalently M1500~-19). We have measured through stacks a
stringent upper limit (<1.7% at 1sigma) for the relative escape fraction of HI
ionizing photons from bright galaxies (L>L*), while for the faint population
(L=0.2L*) the limit to the escape fraction is ~10%. We have computed the
contribution of star-forming galaxies to the observed UV background at z~3 and
we have found that it is not enough to keep the Universe ionized at these
redshifts, unless their escape fraction increases significantly (>10%) at low
luminosities (M1500>-19). We compare our results on the Lyman continuum escape
fraction of high-z galaxies with recent estimates in the literature and discuss
future prospects to shed light on the end of the Dark Ages. In the future,
strong gravitational lensing will be fundamental to measure the Lyman continuum
escape fraction down to faint magnitudes (M1500~-16) which are inaccessible
with the present instrumentation on blank fields. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Asteroid 2017 FZ2 et al.: signs of recent mass-shedding from YORP?,
Abstract: The first direct detection of the asteroidal YORP effect, a phenomenon that
changes the spin states of small bodies due to thermal reemission of sunlight
from their surfaces, was obtained for (54509) YORP 2000 PH5. Such an alteration
can slowly increase the rotation rate of asteroids, driving them to reach their
fission limit and causing their disruption. This process can produce binaries
and unbound asteroid pairs. Secondary fission opens the door to the eventual
formation of transient but genetically-related groupings. Here, we show that
the small near-Earth asteroid (NEA) 2017 FZ2 was a co-orbital of our planet of
the quasi-satellite type prior to their close encounter on 2017 March 23.
Because of this flyby with the Earth, 2017 FZ2 has become a non-resonant NEA.
Our N-body simulations indicate that this object may have experienced
quasi-satellite engagements with our planet in the past and it may return as a
co-orbital in the future. We identify a number of NEAs that follow similar
paths, the largest named being YORP, which is also an Earth's co-orbital. An
apparent excess of NEAs moving in these peculiar orbits is studied within the
framework of two orbit population models. A possibility that emerges from this
analysis is that such an excess, if real, could be the result of mass shedding
from YORP itself or a putative larger object that produced YORP. Future
spectroscopic observations of 2017 FZ2 during its next visit in 2018 (and of
related objects when feasible) may be able to confirm or reject this
interpretation. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: On Increasing Self-Confidence in Non-Bayesian Social Learning over Time-Varying Directed Graphs,
Abstract: We study the convergence of the log-linear non-Bayesian social learning
update rule, for a group of agents that collectively seek to identify a
parameter that best describes a joint sequence of observations. Contrary to
recent literature, we focus on the case where agents assign decaying weights to
its neighbors, and the network is not connected at every time instant but over
some finite time intervals. We provide a necessary and sufficient condition for
the rate at which agents decrease the weights and still guarantees social
learning. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Optomechanical characterization of silicon nitride membrane arrays,
Abstract: We report on the optical and mechanical characterization of arrays of
parallel micromechanical membranes. Pairs of high-tensile stress, 100 nm-thick
silicon nitride membranes are assembled parallel with each other with
separations ranging from 8.5 to 200 $\mu$m. Their optical properties are
accurately determined using a combination of broadband and monochromatic
illuminations and the lowest vibrational mode frequencies and mechanical
quality factors are determined interferometrically. The results and techniques
demonstrated are promising for investigations of collective phenomena in
optomechanical arrays. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Towards the study of least squares estimators with convex penalty,
Abstract: Penalized least squares estimation is a popular technique in high-dimensional
statistics. It includes such methods as the LASSO, the group LASSO, and the
nuclear norm penalized least squares. The existing theory of these methods is
not fully satisfying since it allows one to prove oracle inequalities with
fixed high probability only for the estimators depending on this probability.
Furthermore, the control of compatibility factors appearing in the oracle
bounds is often not explicit. Some very recent developments suggest that the
theory of oracle inequalities can be revised in an improved way. In this paper,
we provide an overview of ideas and tools leading to such an improved theory.
We show that, along with overcoming the disadvantages mentioned above, the
methodology extends to the hilbertian framework and it applies to a large class
of convex penalties. This paper is partly expository. In particular, we provide
adapted proofs of some results from other recent work. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: A Multi-traffic Inter-cell Interference Coordination Scheme in Dense Cellular Networks,
Abstract: This paper proposes a novel semi-distributed and practical ICIC scheme based
on the Almost Blank SubFrame (ABSF) approach specified by 3GPP. We define two
mathematical programming problems for the cases of guaranteed and best-effort
traffic, and use game theory to study the properties of the derived ICIC
distributed schemes, which are compared in detail against unaffordable
centralized schemes. Based on the analysis of the proposed models, we define
Distributed Multi-traffic Scheduling (DMS), a unified distributed framework for
adaptive interference-aware scheduling of base stations in future cellular
networks which accounts for both guaranteed and best-effort traffic. DMS
follows a two-tier approach, consisting of local ABSF schedulers, which perform
the resource distribution between guaranteed and best effort traffic, and a
lightweight local supervisor, which coordinates ABSF local decisions. As a
result of such a two-tier design, DMS requires very light signaling to drive
the local schedulers to globally efficient operating points. As shown by means
of numerical results, DMS allows to (i) maximize radio resources reuse, (ii)
provide requested quality for guaranteed traffic, (iii) minimize the time
dedicated to guaranteed traffic to leave room for best-effort traffic, and (iv)
maximize resource utilization efficiency for best-effort traffic. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: First order magneto-structural transition and magnetocaloric effect in MnNiGe$_{0.9}$Ga$_{0.1}$,
Abstract: The first order magneto-structural transition ($T_t\simeq95$ K) and
magnetocaloric effect in MnNiGe$_{0.9}$Ga$_{0.1}$ are studied via powder x-ray
diffraction and magnetization measurements. Temperature dependent x-ray
diffraction measurements reveal that the magneto-structural transition remains
incomplete down to 23 K, resulting in a coexistence of antiferromagnetic and
ferromagnetic phases at low temperatures. The fraction of the high temperature
Ni$_2$In-type hexagonal ferromagnetic and low temperature TiNiSi-type
orthorhombic antiferromagnetic phases is estimated to be $\sim 40\%$ and $\sim
60\%$, respectively at 23 K. The ferromagnetic phase fraction increases with
increasing field which is found to be in non-equilibrium state and gives rise
to a weak re-entrant transition while warming under field-cooled condition. It
shows a large inverse magnetocaloric effect across the magneto-structural
transition and a conventional magnetocaloric effect across the second order
paramagnetic to ferromagnetic transition. The relative cooling power which
characterizes the performance of a magnetic refrigerant material is found to be
reasonably high compared to the other reported magnetocaloric alloys. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Parametric Gaussian Process Regression for Big Data,
Abstract: This work introduces the concept of parametric Gaussian processes (PGPs),
which is built upon the seemingly self-contradictory idea of making Gaussian
processes parametric. Parametric Gaussian processes, by construction, are
designed to operate in "big data" regimes where one is interested in
quantifying the uncertainty associated with noisy data. The proposed
methodology circumvents the well-established need for stochastic variational
inference, a scalable algorithm for approximating posterior distributions. The
effectiveness of the proposed approach is demonstrated using an illustrative
example with simulated data and a benchmark dataset in the airline industry
with approximately 6 million records. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Fixing and almost fixing a planar convex body,
Abstract: A set of points a 1 ,. .. , a n fixes a planar convex body K if the points
are on bdK, the boundary of K, and if any small move of K brings some point of
the set in intK, the interior of K. The points a 1 ,. .. , a n $\in$ bdK almost
fix K if, for any neighbourhoods V i of a i (i = 1,. .. , n), there are pairs
of points a i , a i $\in$ V i $\cap$ bdK such that a 1 , a 1 ,. .. , a n fix K.
This note compares several definitions of these notions and gives first order
conditions for a 1 ,. .. , a n $\in$ bdK to fix, and to almost fix, K. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: End-to-End Sound Source Separation Conditioned On Instrument Labels,
Abstract: Can we perform an end-to-end sound source separation (SSS) with a variable
number of sources using a deep learning model? This paper presents an extension
of the Wave-U-Net model which allows end-to-end monaural source separation with
a non-fixed number of sources. Furthermore, we propose multiplicative
conditioning with instrument labels at the bottleneck of the Wave-U-Net and
show its effect on the separation results. This approach can be further
extended to other types of conditioning such as audio-visual SSS and
score-informed SSS. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Evolutionary Generative Adversarial Networks,
Abstract: Generative adversarial networks (GAN) have been effective for learning
generative models for real-world data. However, existing GANs (GAN and its
variants) tend to suffer from training problems such as instability and mode
collapse. In this paper, we propose a novel GAN framework called evolutionary
generative adversarial networks (E-GAN) for stable GAN training and improved
generative performance. Unlike existing GANs, which employ a pre-defined
adversarial objective function alternately training a generator and a
discriminator, we utilize different adversarial training objectives as mutation
operations and evolve a population of generators to adapt to the environment
(i.e., the discriminator). We also utilize an evaluation mechanism to measure
the quality and diversity of generated samples, such that only well-performing
generator(s) are preserved and used for further training. In this way, E-GAN
overcomes the limitations of an individual adversarial training objective and
always preserves the best offspring, contributing to progress in and the
success of GANs. Experiments on several datasets demonstrate that E-GAN
achieves convincing generative performance and reduces the training problems
inherent in existing GANs. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Accurate parameter estimation for Bayesian Network Classifiers using Hierarchical Dirichlet Processes,
Abstract: This paper introduces a novel parameter estimation method for the probability
tables of Bayesian network classifiers (BNCs), using hierarchical Dirichlet
processes (HDPs). The main result of this paper is to show that improved
parameter estimation allows BNCs to outperform leading learning methods such as
Random Forest for both 0-1 loss and RMSE, albeit just on categorical datasets.
As data assets become larger, entering the hyped world of "big", efficient
accurate classification requires three main elements: (1) classifiers with
low-bias that can capture the fine-detail of large datasets (2) out-of-core
learners that can learn from data without having to hold it all in main memory
and (3) models that can classify new data very efficiently.
The latest Bayesian network classifiers (BNCs) satisfy these requirements.
Their bias can be controlled easily by increasing the number of parents of the
nodes in the graph. Their structure can be learned out of core with a limited
number of passes over the data. However, as the bias is made lower to
accurately model classification tasks, so is the accuracy of their parameters'
estimates, as each parameter is estimated from ever decreasing quantities of
data. In this paper, we introduce the use of Hierarchical Dirichlet Processes
for accurate BNC parameter estimation.
We conduct an extensive set of experiments on 68 standard datasets and
demonstrate that our resulting classifiers perform very competitively with
Random Forest in terms of prediction, while keeping the out-of-core capability
and superior classification time. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Modeling and Simulation of the Dynamics of the Quick Return Mechanism: A Bond Graph Approach,
Abstract: This paper applies the multibond graph approach for rigid multibody systems
to model the dynamics of general spatial mechanisms. The commonly used quick
return mechanism which comprises of revolute as well as prismatic joints has
been chosen as a representative example to demonstrate the application of this
technique and its resulting advantages. In this work, the links of the quick
return mechanism are modeled as rigid bodies. The rigid links are then coupled
at the joints based on the nature of constraint. This alternative method of
formulation of system dynamics, using Bond Graphs, offers a rich set of
features that include pictorial representation of the dynamics of translation
and rotation for each link of the mechanism in the inertial frame,
representation and handling of constraints at the joints, depiction of
causality, obtaining dynamic reaction forces and moments at various locations
in the mechanism and so on. Yet another advantage of this approach is that the
coding for simulation can be carried out directly from the Bond Graph in an
algorithmic manner, without deriving system equations. In this work, the
program code for simulation is written in MATLAB. The vector and tensor
operations are conveniently represented in MATLAB, resulting in a compact and
optimized code. The simulation results are plotted and discussed in detail. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Physics"
] |
Title: Local and non-local energy spectra of superfluid $^3$He turbulence,
Abstract: Below the phase transition temperature $Tc \simeq 10^{-3}$K He-3B has a
mixture of normal and superfluid components. Turbulence in this material is
carried predominantly by the superfluid component. We explore the statistical
properties of this quantum turbulence, stressing the differences from the
better known classical counterpart. To this aim we study the time-honored
Hall-Vinen-Bekarevich-Khalatnikov coarse-grained equations of superfluid
turbulence. We combine pseudo-spectral direct numerical simulations with
analytic considerations based on an integral closure for the energy flux. We
avoid the assumption of locality of the energy transfer which was used
previously in both analytic and numerical studies of the superfluid He-3B
turbulence. For T<0.37 Tc, with relatively weak mutual friction, we confirm the
previously found "subcritical" energy spectrum E(k), given by a superposition
of two power laws that can be approximated as $E(k)~ k^{-x}$ with an apparent
scaling exponent 5/3 <x(k)< 3. For T>0.37 Tc and with strong mutual friction,
we observed numerically and confirmed analytically the scale-invariant spectrum
$E(k)~ k^{-x}$ with a (k-independent) exponent x > 3 that gradually increases
with the temperature and reaches a value $x\simeq 9$ for $T\approx 0.72 Tc$. In
the near-critical regimes we discover a strong enhancement of intermittency
which exceeds by an order of magnitude the corresponding level in classical
hydrodynamic turbulence. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Towards Neural Phrase-based Machine Translation,
Abstract: In this paper, we present Neural Phrase-based Machine Translation (NPMT). Our
method explicitly models the phrase structures in output sequences using
Sleep-WAke Networks (SWAN), a recently proposed segmentation-based sequence
modeling method. To mitigate the monotonic alignment requirement of SWAN, we
introduce a new layer to perform (soft) local reordering of input sequences.
Different from existing neural machine translation (NMT) approaches, NPMT does
not use attention-based decoding mechanisms. Instead, it directly outputs
phrases in a sequential order and can decode in linear time. Our experiments
show that NPMT achieves superior performances on IWSLT 2014
German-English/English-German and IWSLT 2015 English-Vietnamese machine
translation tasks compared with strong NMT baselines. We also observe that our
method produces meaningful phrases in output languages. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Towards Accurate Multi-person Pose Estimation in the Wild,
Abstract: We propose a method for multi-person detection and 2-D pose estimation that
achieves state-of-art results on the challenging COCO keypoints task. It is a
simple, yet powerful, top-down approach consisting of two stages.
In the first stage, we predict the location and scale of boxes which are
likely to contain people; for this we use the Faster RCNN detector. In the
second stage, we estimate the keypoints of the person potentially contained in
each proposed bounding box. For each keypoint type we predict dense heatmaps
and offsets using a fully convolutional ResNet. To combine these outputs we
introduce a novel aggregation procedure to obtain highly localized keypoint
predictions. We also use a novel form of keypoint-based Non-Maximum-Suppression
(NMS), instead of the cruder box-level NMS, and a novel form of keypoint-based
confidence score estimation, instead of box-level scoring.
Trained on COCO data alone, our final system achieves average precision of
0.649 on the COCO test-dev set and the 0.643 test-standard sets, outperforming
the winner of the 2016 COCO keypoints challenge and other recent state-of-art.
Further, by using additional in-house labeled data we obtain an even higher
average precision of 0.685 on the test-dev set and 0.673 on the test-standard
set, more than 5% absolute improvement compared to the previous best performing
method on the same dataset. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Global band topology of simple and double Dirac-point (semi-)metals,
Abstract: We combine space group representation theory together with scanning of closed
subdomains of the Brillouin zone with Wilson loops to algebraically determine
global band structure topology. Considering space group #19 as a case study, we
show that the energy ordering of the irreducible representations at the
high-symmetry points $\{\Gamma,S,T,U\}$ fully determines the global band
topology, with all topological classes characterized through their simple and
double Dirac-points. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: Topological Perspectives on Statistical Quantities I,
Abstract: In statistics cumulants are defined to be functions that measure the linear
independence of random variables. In the non-communicative case the Boolean
cumulants can be described as functions that measure deviation of a map between
algebras from being an algebra morphism. In Algebraic topology maps that are
homotopic to being algebra morphisms are studied using the theory of $A_\infty$
algebras. In this paper we will explore the link between these two points of
views on maps between algebras that are not algebra maps. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Statistics"
] |
Title: Gee-Haw Whammy Diddle,
Abstract: Gee-Haw Whammy Diddle is a seemingly simple mechanical toy consisting of a
wooden stick and a second stick that is made up of a series of notches with a
propeller at its end. When the wooden stick is pulled over the notches, the
propeller starts to rotate. In spite of its simplicity, physical principles
governing the motion of the stick and the propeller are rather complicated and
interesting. Here we provide a thorough analysis of the system and parameters
influencing the motion. We show that contrary to the results published on this
topic so far, neither elliptic motion of the stick nor frequency
synchronization is needed for starting the motion of the propeller. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Connecting the dots between mechanosensitive channel abundance, osmotic shock, and survival at single-cell resolution,
Abstract: Rapid changes in extracellular osmolarity are one of many insults microbial
cells face on a daily basis. To protect against such shocks, Escherichia coli
and other microbes express several types of transmembrane channels which open
and close in response to changes in membrane tension. In E. coli, one of the
most abundant channels is the mechanosensitive channel of large conductance
(MscL). While this channel has been heavily characterized through structural
methods, electrophysiology, and theoretical modeling, our understanding of its
physiological role in preventing cell death by alleviating high membrane
tension remains tenuous. In this work, we examine the contribution of MscL
alone to cell survival after osmotic shock at single cell resolution using
quantitative fluorescence microscopy. We conduct these experiments in an E.
coli strain which is lacking all mechanosensitive channel genes save for MscL
whose expression is tuned across three orders of magnitude through
modifications of the Shine-Dalgarno sequence. While theoretical models suggest
that only a few MscL channels would be needed to alleviate even large changes
in osmotic pressure, we find that between 500 and 700 channels per cell are
needed to convey upwards of 80% survival. This number agrees with the average
MscL copy number measured in wild-type E. coli cells through proteomic studies
and quantitative Western blotting. Furthermore, we observe zero survival events
in cells with less than 100 channels per cell. This work opens new questions
concerning the contribution of other mechanosensitive channels to survival as
well as regulation of their activity. | [
0,
0,
0,
0,
1,
0
] | [
"Quantitative Biology"
] |
Title: Optical Mapping Near-eye Three-dimensional Display with Correct Focus Cues,
Abstract: We present an optical mapping near-eye (OMNI) three-dimensional display
method for wearable devices. By dividing a display screen into different
sub-panels and optically mapping them to various depths, we create a multiplane
volumetric image with correct focus cues for depth perception. The resultant
system can drive the eye's accommodation to the distance that is consistent
with binocular stereopsis, thereby alleviating the vergence-accommodation
conflict, the primary cause for eye fatigue and discomfort. Compared with the
previous methods, the OMNI display offers prominent advantages in adaptability,
image dynamic range, and refresh rate. | [
1,
1,
0,
0,
0,
0
] | [
"Physics",
"Computer Science"
] |
Title: Quantum anomalous Hall state from spatially decaying interactions on the decorated honeycomb lattice,
Abstract: Topological phases typically encode topology at the level of the single
particle band structure. But a remarkable class of models shows that quantum
anomalous Hall effects can be driven exclusively by interactions, while the
parent non-interacting band structure is topologically trivial. Unfortunately,
these models have so far relied on interactions that do not spatially decay and
are therefore unphysical. We study a model of spinless fermions on a decorated
honeycomb lattice. Using complementary methods, mean-field theory and exact
diagonalization, we find a robust quantum anomalous Hall phase arising from
spatially decaying interactions. Our finding paves the way for observing the
quantum anomalous Hall effect driven entirely by interactions. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Poisson--Gamma Dynamical Systems,
Abstract: We introduce a new dynamical system for sequentially observed multivariate
count data. This model is based on the gamma--Poisson construction---a natural
choice for count data---and relies on a novel Bayesian nonparametric prior that
ties and shrinks the model parameters, thus avoiding overfitting. We present an
efficient MCMC inference algorithm that advances recent work on augmentation
schemes for inference in negative binomial models. Finally, we demonstrate the
model's inductive bias using a variety of real-world data sets, showing that it
exhibits superior predictive performance over other models and infers highly
interpretable latent structure. | [
1,
0,
0,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Isoparameteric hypersurfaces in a Randers sphere of constant flag curvature,
Abstract: In this paper, I study the isoparametric hypersurfaces in a Randers sphere
$(S^n,F)$ of constant flag curvature, with the navigation datum $(h,W)$. I
prove that an isoparametric hypersurface $M$ for the standard round sphere
$(S^n,h)$ which is tangent to $W$ remains isoparametric for $(S^n,F)$ after the
navigation process. This observation provides a special class of isoparametric
hypersurfaces in $(S^n,F)$, which can be equivalently described as the regular
level sets of isoparametric functions $f$ satisfying $-f$ is transnormal. I
provide a classification for these special isoparametric hypersurfaces $M$,
together with their ambient metric $F$ on $S^n$, except the case that $M$ is of
the OT-FKM type with the multiplicities $(m_1,m_2)=(8,7)$. I also give a
complete classificatoin for all homogeneous hypersurfaces in $(S^n,F)$. They
all belong to these special isoparametric hypersurfaces. Because of the extra
$W$, the number of distinct principal curvature can only be 1,2 or 4, i.e.
there are less homogeneous hypersurfaces for $(S^n,F)$ than those for
$(S^n,h)$. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Bright-field microscopy of transparent objects: a ray tracing approach,
Abstract: Formation of a bright-field microscopic image of a transparent phase object
is described in terms of elementary geometrical optics. Our approach is based
on the premise that image replicates the intensity distribution (real or
virtual) at the front focal plane of the objective. The task is therefore
reduced to finding the change in intensity at the focal plane caused by the
object. This can be done by ray tracing complemented with the requirement of
conservation of the number of rays. Despite major simplifications involved in
such an analysis, it reproduces some results from the paraxial wave theory.
Additionally, our analysis suggests two ways of extracting quantitative phase
information from bright-field images: by vertically shifting the focal plane
(the approach used in the transport-of-intensity analysis) or by varying the
angle of illumination. In principle, information thus obtained should allow
reconstruction of the object morphology. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Quantitative Biology"
] |
Title: When do we have the power to detect biological interactions in spatial point patterns?,
Abstract: Determining the relative importance of environmental factors, biotic
interactions and stochasticity in assembling and maintaining species-rich
communities remains a major challenge in ecology. In plant communities,
interactions between individuals of different species are expected to leave a
spatial signature in the form of positive or negative spatial correlations over
distances relating to the spatial scale of interaction. Most studies using
spatial point process tools have found relatively little evidence for
interactions between pairs of species. More interactions tend to be detected in
communities with fewer species. However, there is currently no understanding of
how the power to detect spatial interactions may change with sample size, or
the scale and intensity of interactions.
We use a simple 2-species model where the scale and intensity of interactions
are controlled to simulate point pattern data. In combination with an
approximation to the variance of the spatial summary statistics that we sample,
we investigate the power of current spatial point pattern methods to correctly
reject the null model of bivariate species independence.
We show that the power to detect interactions is positively related to the
abundances of the species tested, and the intensity and scale of interactions.
Increasing imbalance in abundances has a negative effect on the power to detect
interactions. At population sizes typically found in currently available
datasets for species-rich plant communities we find only a very low power to
detect interactions. Differences in power may explain the increased frequency
of interactions in communities with fewer species. Furthermore, the
community-wide frequency of detected interactions is very sensitive to a
minimum abundance criterion for including species in the analyses. | [
0,
0,
0,
0,
1,
0
] | [
"Quantitative Biology",
"Statistics"
] |
Title: Spectral Algorithms for Computing Fair Support Vector Machines,
Abstract: Classifiers and rating scores are prone to implicitly codifying biases, which
may be present in the training data, against protected classes (i.e., age,
gender, or race). So it is important to understand how to design classifiers
and scores that prevent discrimination in predictions. This paper develops
computationally tractable algorithms for designing accurate but fair support
vector machines (SVM's). Our approach imposes a constraint on the covariance
matrices conditioned on each protected class, which leads to a nonconvex
quadratic constraint in the SVM formulation. We develop iterative algorithms to
compute fair linear and kernel SVM's, which solve a sequence of relaxations
constructed using a spectral decomposition of the nonconvex constraint. Its
effectiveness in achieving high prediction accuracy while ensuring fairness is
shown through numerical experiments on several data sets. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: On a method for constructing the Lax pairs for integrable models via quadratic ansatz,
Abstract: A method for constructing the Lax pairs for nonlinear integrable models is
suggested. First we look for a nonlinear invariant manifold to the
linearization of the given equation. Examples show that such invariant manifold
does exist and can effectively be found. Actually it is defined by a quadratic
form. As a result we get a nonlinear Lax pair consisting of the linearized
equation and the invariant manifold. Our second step consists of finding an
appropriate change of the variables to linearize the found nonlinear Lax pair.
The desired change of the variables is again defined by a quadratic form. The
method is illustrated by the well-known KdV equation and the modified Volterra
chain. New Lax pairs are found. The formal asymptotic expansions for their
eigenfunctions are constructed around the singular values of the spectral
parameter. By applying the method of the formal diagonalization to these Lax
pairs the infinite series of the local conservation laws are obtained for the
corresponding nonlinear models. | [
0,
1,
0,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Uncorrelated far AGN flaring with their delayed UHECRs events,
Abstract: The most distant AGN, within the allowed GZK cut-off radius, have been
recently candidate by many authors as the best location for observed UHECR
origination. Indeed, the apparent homogeneity and isotropy of recent UHECR
signals seems to require a far cosmic isotropic and homogeneous scenario
involving a proton UHECR courier: our galaxy or nearest local group or super
galactic plane (ruled by Virgo cluster) are too much near and apparently too
much anisotropic in disagreement with PAO and TA almost homogeneous sample
data. However, the few and mild observed UHECR clustering, the North and South
Hot Spots, are smeared in wide solid angles. Their consequent random walk
flight from most far GZK UHECR sources, nearly at 100 Mpc, must be delayed
(with respect to a straight AGN photon gamma flaring arrival trajectory) at
least by a million years. During this time, the AGN jet blazing signal, its
probable axis deflection (such as the helical jet in Mrk501), its miss
alignment or even its almost certain exhaust activity may lead to a complete
misleading correlation between present UHECR events and a much earlier active
AGN ejection. UHECR maps maybe anyway related to galactic or nearest (Cen A,
M82) AGN extragalactic UHECR sources shining in twin Hot Spot. Therefore we
defend our (quite different) scenarios where UHECR are mostly made by lightest
UHECR nuclei originated by nearby AGN sources, or few galactic sources, whose
delayed signals reach us within few thousand years in the observed smeared sky
areas. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Opinion Dynamics via Search Engines (and other Algorithmic Gatekeepers),
Abstract: Ranking algorithms are the information gatekeepers of the Internet era. We
develop a stylized model to study the effects of ranking algorithms on opinion
dynamics. We consider a search engine that uses an algorithm based on
popularity and on personalization. We find that popularity-based rankings
generate an advantage of the fewer effect: fewer websites reporting a given
signal attract relatively more traffic overall. This highlights a novel,
ranking-driven channel that explains the diffusion of misinformation, as
websites reporting incorrect information may attract an amplified amount of
traffic precisely because they are few. Furthermore, when individuals provide
sufficiently positive feedback to the ranking algorithm, popularity-based
rankings tend to aggregate information while personalization acts in the
opposite direction. | [
1,
0,
0,
0,
0,
1
] | [
"Computer Science",
"Statistics"
] |
Title: Exploring home robot capabilities by medium fidelity prototyping,
Abstract: In order for autonomous robots to be able to support people's well-being in
homes and everyday environments, new interactive capabilities will be required,
as exemplified by the soft design used for Disney's recent robot character
Baymax in popular fiction. Home robots will be required to be easy to interact
with and intelligent--adaptive, fun, unobtrusive and involving little effort to
power and maintain--and capable of carrying out useful tasks both on an
everyday level and during emergencies. The current article adopts an
exploratory medium fidelity prototyping approach for testing some new robotic
capabilities in regard to recognizing people's activities and intentions and
behaving in a way which is transparent to people. Results are discussed with
the aim of informing next designs. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Management system for the SND experiments,
Abstract: A new management system for the SND detector experiments (at VEPP-2000
collider in Novosibirsk) is developed. We describe here the interaction between
a user and the SND databases. These databases contain experiment configuration,
conditions and metadata. The new system is designed in client-server
architecture. It has several logical layers corresponding to the users roles. A
new template engine is created. A web application is implemented using Node.js
framework. At the time the application provides: showing and editing
configuration; showing experiment metadata and experiment conditions data
index; showing SND log (prototype). | [
1,
1,
0,
0,
0,
0
] | [
"Computer Science",
"Physics"
] |
Title: Kernel-Based Learning for Smart Inverter Control,
Abstract: Distribution grids are currently challenged by frequent voltage excursions
induced by intermittent solar generation. Smart inverters have been advocated
as a fast-responding means to regulate voltage and minimize ohmic losses. Since
optimal inverter coordination may be computationally challenging and preset
local control rules are subpar, the approach of customized control rules
designed in a quasi-static fashion features as a golden middle. Departing from
affine control rules, this work puts forth non-linear inverter control
policies. Drawing analogies to multi-task learning, reactive control is posed
as a kernel-based regression task. Leveraging a linearized grid model and given
anticipated data scenarios, inverter rules are jointly designed at the feeder
level to minimize a convex combination of voltage deviations and ohmic losses
via a linearly-constrained quadratic program. Numerical tests using real-world
data on a benchmark feeder demonstrate that nonlinear control rules driven also
by a few non-local readings can attain near-optimal performance. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Temperature fluctuations in a changing climate: an ensemble-based experimental approach,
Abstract: There is an ongoing debate in the literature about whether the present global
warming is increasing local and global temperature variability. The central
methodological issues of this debate relate to the proper treatment of
normalised temperature anomalies and trends in the studied time series which
may be difficult to separate from time-evolving fluctuations. Some argue that
temperature variability is indeed increasing globally, whereas others conclude
it is decreasing or remains practically unchanged. Meanwhile, a consensus
appears to emerge that local variability in certain regions (e.g. Western
Europe and North America) has indeed been increasing in the past 40 years. Here
we investigate the nature of connections between external forcing and climate
variability conceptually by using a laboratory-scale minimal model of
mid-latitude atmospheric thermal convection subject to continuously decreasing
`equator-to-pole' temperature contrast, mimicking climate change. The analysis
of temperature records from an ensemble of experimental runs (`realisations')
all driven by identical time-dependent external forcing reveals that the
collective variability of the ensemble and that of individual realisations may
be markedly different -- a property to be considered when interpreting climate
records. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Matrix factorizations for quantum complete intersections,
Abstract: We introduce twisted matrix factorizations for quantum complete intersections
of codimension two. For such an algebra, we show that in a given dimension,
almost all the indecomposable modules with bounded minimal projective
resolutions correspond to such matrix factorizations. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: RELink: A Research Framework and Test Collection for Entity-Relationship Retrieval,
Abstract: Improvements of entity-relationship (E-R) search techniques have been
hampered by a lack of test collections, particularly for complex queries
involving multiple entities and relationships. In this paper we describe a
method for generating E-R test queries to support comprehensive E-R search
experiments. Queries and relevance judgments are created from content that
exists in a tabular form where columns represent entity types and the table
structure implies one or more relationships among the entities. Editorial work
involves creating natural language queries based on relationships represented
by the entries in the table. We have publicly released the RELink test
collection comprising 600 queries and relevance judgments obtained from a
sample of Wikipedia List-of-lists-of-lists tables. The latter comprise tuples
of entities that are extracted from columns and labelled by corresponding
entity types and relationships they represent. In order to facilitate research
in complex E-R retrieval, we have created and released as open source the
RELink Framework that includes Apache Lucene indexing and search specifically
tailored to E-R retrieval. RELink includes entity and relationship indexing
based on the ClueWeb-09-B Web collection with FACC1 text span annotations
linked to Wikipedia entities. With ready to use search resources and a
comprehensive test collection, we support community in pursuing E-R research at
scale. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Optical bandgap engineering in nonlinear silicon nitride waveguides,
Abstract: Silicon nitride is awell-established material for photonic devices and
integrated circuits. It displays a broad transparency window spanning from the
visible to the mid-IR and waveguides can be manufactured with low losses. An
absence of nonlinear multi-photon absorption in the erbium lightwave
communications band has enabled various nonlinear optic applications in the
past decade. Silicon nitride is a dielectric material whose optical and
mechanical properties strongly depend on the deposition conditions. In
particular, the optical bandgap can be modified with the gas flow ratio during
low-pressure chemical vapor deposition (LPCVD). Here we show that this
parameter can be controlled in a highly reproducible manner, providing an
approach to synthesize the nonlinear Kerr coefficient of the material. This
holistic empirical study provides relevant guidelines to optimize the
properties of LPCVD silicon nitride waveguides for nonlinear optics
applications that rely on the Kerr effect. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: How Robust are Deep Neural Networks?,
Abstract: Convolutional and Recurrent, deep neural networks have been successful in
machine learning systems for computer vision, reinforcement learning, and other
allied fields. However, the robustness of such neural networks is seldom
apprised, especially after high classification accuracy has been attained. In
this paper, we evaluate the robustness of three recurrent neural networks to
tiny perturbations, on three widely used datasets, to argue that high accuracy
does not always mean a stable and a robust (to bounded perturbations,
adversarial attacks, etc.) system. Especially, normalizing the spectrum of the
discrete recurrent network to bound the spectrum (using power method, Rayleigh
quotient, etc.) on a unit disk produces stable, albeit highly non-robust neural
networks. Furthermore, using the $\epsilon$-pseudo-spectrum, we show that
training of recurrent networks, say using gradient-based methods, often result
in non-normal matrices that may or may not be diagonalizable. Therefore, the
open problem lies in constructing methods that optimize not only for accuracy
but also for the stability and the robustness of the underlying neural network,
a criterion that is distinct from the other. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Approximate Profile Maximum Likelihood,
Abstract: We propose an efficient algorithm for approximate computation of the profile
maximum likelihood (PML), a variant of maximum likelihood maximizing the
probability of observing a sufficient statistic rather than the empirical
sample. The PML has appealing theoretical properties, but is difficult to
compute exactly. Inspired by observations gleaned from exactly solvable cases,
we look for an approximate PML solution, which, intuitively, clumps comparably
frequent symbols into one symbol. This amounts to lower-bounding a certain
matrix permanent by summing over a subgroup of the symmetric group rather than
the whole group during the computation. We extensively experiment with the
approximate solution, and find the empirical performance of our approach is
competitive and sometimes significantly better than state-of-the-art
performance for various estimation problems. | [
1,
0,
0,
1,
0,
0
] | [
"Statistics",
"Mathematics",
"Computer Science"
] |
Title: 802.11 Wireless Simulation and Anomaly Detection using HMM and UBM,
Abstract: Despite the growing popularity of 802.11 wireless networks, users often
suffer from connectivity problems and performance issues due to unstable radio
conditions and dynamic user behavior among other reasons. Anomaly detection and
distinction are in the thick of major challenges that network managers
encounter. Complication of monitoring the broaden and complex WLANs, that often
requires heavy instrumentation of the user devices, makes the anomaly detection
analysis even harder. In this paper we exploit 802.11 access point usage data
and propose an anomaly detection technique based on Hidden Markov Model (HMM)
and Universal Background Model (UBM) on data that is inexpensive to obtain. We
then generate a number of network anomalous scenarios in OMNeT++/INET network
simulator and compare the detection outcomes with those in baseline approaches
(RawData and PCA). The experimental results show the superiority of HMM and
HMM-UBM models in detection precision and sensitivity. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Optimally Gathering Two Robots,
Abstract: We present an algorithm that ensures in finite time the gathering of two
robots in the non-rigid ASYNC model. To circumvent established impossibility
results, we assume robots are equipped with 2-colors lights and are able to
measure distances between one another. Aside from its light, a robot has no
memory of its past actions, and its protocol is deterministic. Since, in the
same model, gathering is impossible when lights have a single color, our
solution is optimal with respect to the number of used colors. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: On Grauert-Riemenschneider type criterions,
Abstract: Let $(X,\omega)$ be a compact Hermitian manifold of complex dimension $n$. In
this article, we first survey recent progress towards Grauert-Riemenschneider
type criterions. Secondly, we give a simplified proof of Boucksom's conjecture
given by the author under the assumption that the Hermitian metric $\omega$
satisfies $\partial\overline{\partial}\omega^l=$ for all $l$, i.e., if $T$ is a
closed positive current on $X$ such that $\int_XT_{ac}^n>0$, then the class
$\{T\}$ is big and $X$ is Kähler. Finally, as an easy observation, we point
out that Nguyen's result can be generalized as follows: if
$\partial\overline{\partial}\omega=0$, and $T$ is a closed positive current
with analytic singularities, such that $\int_XT^n_{ac}>0$, then the class
$\{T\}$ is big and $X$ is Kähler. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: The Forgettable-Watcher Model for Video Question Answering,
Abstract: A number of visual question answering approaches have been proposed recently,
aiming at understanding the visual scenes by answering the natural language
questions. While the image question answering has drawn significant attention,
video question answering is largely unexplored.
Video-QA is different from Image-QA since the information and the events are
scattered among multiple frames. In order to better utilize the temporal
structure of the videos and the phrasal structures of the answers, we propose
two mechanisms: the re-watching and the re-reading mechanisms and combine them
into the forgettable-watcher model. Then we propose a TGIF-QA dataset for video
question answering with the help of automatic question generation. Finally, we
evaluate the models on our dataset. The experimental results show the
effectiveness of our proposed models. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Partition algebras $\mathsf{P}_k(n)$ with $2k>n$ and the fundamental theorems of invariant theory for the symmetric group $\mathsf{S}_n$,
Abstract: Assume $\mathsf{M}_n$ is the $n$-dimensional permutation module for the
symmetric group $\mathsf{S}_n$, and let $\mathsf{M}_n^{\otimes k}$ be its
$k$-fold tensor power. The partition algebra $\mathsf{P}_k(n)$ maps
surjectively onto the centralizer algebra
$\mathsf{End}_{\mathsf{S}_n}(\mathsf{M}_n^{\otimes k})$ for all $k, n \in
\mathbb{Z}_{\ge 1}$ and isomorphically when $n \ge 2k$. We describe the image
of the surjection $\Phi_{k,n}:\mathsf{P}_k(n) \to
\mathsf{End}_{\mathsf{S}_n}(\mathsf{M}_n^{\otimes k})$ explicitly in terms of
the orbit basis of $\mathsf{P}_k(n)$ and show that when $2k > n$ the kernel of
$\Phi_{k,n}$ is generated by a single essential idempotent $\mathsf{e}_{k,n}$,
which is an orbit basis element. We obtain a presentation for
$\mathsf{End}_{\mathsf{S}_n}(\mathsf{M}_n^{\otimes k})$ by imposing one
additional relation, $\mathsf{e}_{k,n} = 0$, to the standard presentation of
the partition algebra $\mathsf{P}_k(n)$ when $2k > n$. As a consequence, we
obtain the fundamental theorems of invariant theory for the symmetric group
$\mathsf{S}_n$. We show under the natural embedding of the partition algebra
$\mathsf{P}_n(n)$ into $\mathsf{P}_k(n)$ for $k \ge n$ that the essential
idempotent $\mathsf{e}_{n,n}$ generates the kernel of $\Phi_{k,n}$. Therefore,
the relation $\mathsf{e}_{n,n} = 0$ can replace $\mathsf{e}_{k,n} = 0$ when $k
\ge n$. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Suppression of Hall number due to charge density wave order in high-$T_c$ cuprates,
Abstract: Understanding the pseudogap phase in hole-doped high temperature cuprate
superconductors remains a central challenge in condensed matter physics. From a
host of recent experiments there is now compelling evidence of translational
symmetry breaking charge density wave (CDW) order in a wide range of doping
inside this phase. Two distinct types of incommensurate charge order --
bidirectional at zero or low magnetic fields and unidirectional at high
magnetic fields close to the upper critical field $H_{c2}$ -- have been
reported so far in approximately the same doping range between $p\simeq 0.08$
and $p\simeq 0.16$. In concurrent developments, recent high field Hall
experiments have also revealed two indirect but striking signatures of Fermi
surface reconstruction in the pseudogap phase, namely, a sign change of the
Hall coefficient to negative values at low temperatures at intermediate range
of hole doping and a rapid suppression of the positive Hall number without
change in sign near optimal doping $p \sim 0.19$. We show that the assumption
of a unidirectional incommensurate CDW (with or without a coexisting weak
bidirectional order) at high magnetic fields near optimal doping and a
coexistence of both types of orders of approximately equal magnitude at high
magnetic fields at intermediate range of doping may help explain the striking
behavior of low temperature Hall effect in the entire pseudogap phase. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Dual-Primal Graph Convolutional Networks,
Abstract: In recent years, there has been a surge of interest in developing deep
learning methods for non-Euclidean structured data such as graphs. In this
paper, we propose Dual-Primal Graph CNN, a graph convolutional architecture
that alternates convolution-like operations on the graph and its dual. Our
approach allows to learn both vertex- and edge features and generalizes the
previous graph attention (GAT) model. We provide extensive experimental
validation showing state-of-the-art results on a variety of tasks tested on
established graph benchmarks, including CORA and Citeseer citation networks as
well as MovieLens, Flixter, Douban and Yahoo Music graph-guided recommender
systems. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
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