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arxiv_dataset-92001712.01401 | The commutator and centralizer description of Sylow 2-subgroups of
alternating and symmetric groups
math.GR
Given a permutational wreath product sequence of cyclic groups of prime order
we research a commutator width of such groups and some properties of its
commutator subgroup.
Commutator width of Sylow 2-subgroups of alternating group $A_{2^{k}}$,
permutation group $S_{2^k}$ and $C_p \wr B$ were founded. The result of
research was extended on subgroups $(Syl_2 {A_{2^k}})'$, $p>2$. The paper
presents a construction of commutator subgroup of Sylow 2-subgroups of
symmetric and alternating groups. Also minimal generic sets of Sylow
2-subgroups of $A_{2^k}$ were founded. Elements presentation of $(Syl_2
{A_{2^k}})'$, $(Syl_2 {S_{2^k}})'$ was investigated. We prove that the
commutator width \cite {Mur} of an arbitrary element of a discrete wreath
product of cyclic groups $C_p$ is 1. Key words: wreath product of group,
commutator width of $p$-Sylow subgroups, commutator subgroup, centralizer
subgroup, semidirect product.
| arxiv topic:math.GR |
arxiv_dataset-92011712.01501 | Generating scalable entanglement of ultracold bosons in superlattices
through resonant shaking
cond-mat.quant-gas quant-ph
Based on a one-dimensional double-well superlattice with a unit filling of
ultracold atoms per site, we propose a scheme to generate scalable entangled
states in the superlattice through resonant lattice shakings. Our scheme
utilizes periodic lattice modulations to entangle two atoms in each unit cell
with respect to their orbital degree of freedom, and the complete atomic system
in the superlattice becomes a cluster of bipartite entangled atom pairs. To
demonstrate this we perform $ab \ initio$ quantum dynamical simulations using
the Multi-Layer Multi-Configuration Time-Dependent Hartree Method for Bosons,
which accounts for all correlations among the atoms. The proposed clusters of
bipartite entanglements manifest as an essential resource for various quantum
applications, such as measurement based quantum computation. The lattice
shaking scheme to generate this cluster possesses advantages such as a high
scalability, fast processing speed, rich controllability on the target
entangled states, and accessibility with current experimental techniques.
| arxiv topic:cond-mat.quant-gas quant-ph |
arxiv_dataset-92021712.01601 | Rooted tree maps and the derivation relation for multiple zeta values
math.NT math.CO
Rooted tree maps assign to an element of the Connes-Kreimer Hopf algebra of
rooted trees a linear map on the noncommutative polynomial algebra in two
letters. Evaluated at any admissible word these maps induce linear relations
between multiple zeta values. In this note we show that the derivation
relations for multiple zeta values are contained in this class of linear
relations.
| arxiv topic:math.NT math.CO |
arxiv_dataset-92031712.01701 | Dynamical properties of the $S=\frac{1}{2}$ random Heisenberg chain
cond-mat.str-el
We use numerical techniques to study dynamical properties at finite
temperature ($T$) of the Heisenberg spin chain with random exchange couplings,
which realizes the random singlet (RS) fixed point in the low-energy limit.
Specifically, we study the dynamic spin structure factor $S(q,\omega)$, which
can be probed directly by inelastic neutron scattering experiments and, in the
limit of small $\omega$, in nuclear magnetic resonance (NMR) experiments
through the spin-lattice relaxation rate $1/T_1$. Our work combines three
complementary methods: exact diagonalization, matrix-product-state algorithms,
and stochastic analytic continuation of quantum Monte Carlo results in
imaginary time. Unlike the uniform system, whose low-energy excitations at low
$T$ are restricted to $q$ close to $0$ and $\pi$, our study reveals a
continuous narrow band of low-energy excitations in $S(q,\omega)$, extending
throughout the Brillouin zone. Close to $q=\pi$, the scaling properties of
these excitations are well captured by the RS theory, but we also see
disagreements with some aspects of the predicted $q$-dependence further away
from $q=\pi$. Furthermore we find spin diffusion effects close to $q=0$ that
are not contained within the RS theory but give non-negligible contributions to
the mean $1/T_1$. To compare with NMR experiments, we consider the distribution
of the local $1/T_1$ values, which is broad, approximately described by a
stretched exponential. The mean value first decreases with $T$, but starts to
increase and diverge below a crossover temperature. Although a similar
divergent behavior has been found for the static uniform susceptibility, this
divergent behavior of $1/T_1$ has never been seen in experiments. Our results
show that the divergence of the mean $1/T_1$ is due to rare events in the
disordered chains and is concealed in experiments, where the typical $1/T_1$
value is accessed.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-92041712.01801 | On the Cosmic No-Hair Conjecture in T2-symmetric non-linear scalar field
spacetimes
gr-qc math-ph math.DG math.MP
We consider spacetimes solving the Einstein non-linear scalar field equations
with T2-symmetry and show that they admit an areal time foliation in the
expanding direction. In particular, we prove global existence and uniqueness of
solutions to the corresponding system of evolution equations for all future
times. The only assumption we have to make is that the potential is a
non-negative smooth function.
In the special case of a constant potential, a setting which is equivalent to
a linear scalar field on a background with a positive cosmological constant, we
achieve detailed asymptotic estimates for the different components of the
spacetime metric. This result holds for all T3-Gowdy symmetric metrics and
extends to certain T2-symmetric ones satisfying an a priori decay property.
Building upon these asymptotic estimates, we show future causal geodesic
completeness and prove the Cosmic No-Hair conjecture.
| arxiv topic:gr-qc math-ph math.DG math.MP |
arxiv_dataset-92051712.01901 | On the rack homology of graphic quandles
math.GT math.AT
This paper has partially a novel and partially a survey character. We start
with a short review of rack (two term) homology of self distributive algebraic
structures (shelves) and their connections to knot theory. We concentrate on a
sub-family of quandles satisfying the graphic axiom. For a large family of
graphic quandles (including infinite ones), we compute the second rack homology
groups. Finally, we propose conjectures based on our computational data.
| arxiv topic:math.GT math.AT |
arxiv_dataset-92061712.02001 | Predicting Short-Term Uber Demand Using Spatio-Temporal Modeling: A New
York City Case Study
stat.AP
The demand for e-hailing services is growing rapidly, especially in large
cities. Uber is the first and popular e-hailing company in the United Stated
and New York City. A comparison of the demand for yellow-cabs and Uber in NYC
in 2014 and 2015 shows that the demand for Uber has increased. However, this
demand may not be distributed uniformly either spatially or temporally. Using
spatio-temporal time series models can help us to better understand the demand
for e-hailing services and to predict it more accurately. This paper analyzes
the prediction performance of one temporal model (vector autoregressive (VAR))
and two spatio-temporal models (Spatial-temporal autoregressive (STAR); least
absolute shrinkage and selection operator applied on STAR (LASSO-STAR)) and for
different scenarios (based on the number of time and space lags), and applied
to both rush hours and non-rush hours periods. The results show the need of
considering spatial models for taxi demand.
| arxiv topic:stat.AP |
arxiv_dataset-92071712.02101 | Radiative neutrino masses from order-4 CP symmetry
hep-ph
Generalized CP symmetry of order 4 (CP4) is surprisingly powerful in shaping
scalar and quark sectors of multi-Higgs models. Here, we extend this framework
to the neutrino sector. We build two simple Majorana neutrino mass models with
unbroken CP4, which are analogous to Ma's scotogenic model. Both models use
three Higgs doublets and two or three right-handed (RH) neutrinos. The minimal
CP4 symmetric scotogenic model uses only two RH neutrinos, leads to three
non-zero light neutrino masses, and contains a built-in mechanism to further
suppress them via phase alignment. With three RH neutrinos, one generates a
type I seesaw mass matrix of rank 1, which is then corrected by the same
scotogenic mechanism, naturally leading to two neutrino mass scales with mild
hierarchy. These minimal CP4-based constructions emerge as a primer for
introducing additional symmetry structures and exploring their phenomenological
consequences.
| arxiv topic:hep-ph |
arxiv_dataset-92081712.02201 | Targeting realistic geometry in Tokamak code Gysela
physics.plasm-ph physics.comp-ph
In magnetically confined plasmas used in Tokamak, turbulence is responsible
for specific transport that limits the performance of this kind of reactors.
Gyrokinetic simulations are able to capture ion and electron turbulence that
give rise to heat losses, but require also state-of-the-art HPC techniques to
handle computation costs. Such simulations are a major tool to establish good
operating regime in Tokamak such as ITER, which is currently being built. Some
of the key issues to address more realistic gyrokinetic simulations are:
efficient and robust numerical schemes, accurate geometric description, good
parallelization algorithms. The framework of this work is the Semi-Lagrangian
setting for solving the gyrokinetic Vlasov equation and the Gyseka code. In
this paper, a new variant for the interpolation method is proposed that can
handle the mesh singularity in the poloidal plane at r=0 (polar system is used
for the moment in Gysela). A non-uniform meshing of the poloidal plane is
proposed instead of uniform one in order to save memory and computations. The
interpolation method, the gyroaverage operator, and the Poisson solver are
revised in order to cope with non-uniform meshes. A mapping that establish a
bijection from polar coordinates to more realistic plasma shape is used to
improve realism. Convergence studies are provided to establish the validity and
robustness of our new approach.
| arxiv topic:physics.plasm-ph physics.comp-ph |
arxiv_dataset-92091712.02301 | Phase transitions in a system of hard $Y$-shaped particles on the
triangular lattice
cond-mat.stat-mech
We study the different phases and the phase transitions in a system of
$Y$-shaped particles, examples of which include Immunoglobulin-G and
trinaphthylene molecules, on a triangular lattice interacting exclusively
through excluded volume interactions. Each particle consists of a central site
and three of its six nearest neighbours chosen alternately, such that there are
two types of particles which are mirror images of each other. We study the
equilibrium properties of the system using grand canonical Monte Carlo
simulations that implements an algorithm with cluster moves that is able to
equilibrate the system at densities close to full packing. We show that, with
increasing density, the system undergoes two entropy-driven phase transitions
with two broken-symmetry phases. At low densities, the system is in a
disordered phase. As intermediate phases, there is a solid-like sublattice
phase in which one type of particle is preferred over the other and the
particles preferentially occupy one of four sublattices, thus breaking both
particle-symmetry as well as translational invariance. At even higher
densities, the phase is a columnar phase, where the particle-symmetry is
restored, and the particles preferentially occupy even or odd rows along one of
the three directions. This phase has translational order in only one direction,
and breaks rotational invariance. From finite size scaling, we demonstrate that
both the transitions are first order in nature. We also show that the simpler
system with only one type of particles undergoes a single discontinuous phase
transition from a disordered phase to a solid-like sublattice phase with
increasing density of particles.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-92101712.02401 | FRW and domain walls in higher spin gravity
hep-th
We present exact solutions to Vasiliev's bosonic higher spin gravity
equations in four dimensions with positive and negative cosmological constant
that admit an interpretation in terms of domain walls, quasi-instantons and
Friedman-Robertson-Walker (FRW) backgrounds. Their isometry algebras are
infinite dimensional higher-spin extensions of spacetime isometries generated
by six Killing vectors. The solutions presented are obtained by using a method
of holomorphic factorization in noncommutative twistor space and gauge
functions. In interpreting the solutions in terms of Fronsdal-type fields in
spacetime, a field-dependent higher spin transformation is required, which is
implemented at leading order. To this order, the scalar field solves
Klein-Gordon equation with conformal mass in (anti) de Sitter space. We
interpret the FRW solution with de Sitter asymptotics in the context of
inflationary cosmology and we expect that the domain wall and FRW solutions are
associated with spontaneously broken scaling symmetries in their holographic
description. We observe that the factorization method provides a convenient
framework for setting up a perturbation theory around the exact solutions, and
we propose that the nonlinear completion of particle excitations over FRW and
domain wall solutions requires black hole-like states.
| arxiv topic:hep-th |
arxiv_dataset-92111712.02501 | CNNs are Globally Optimal Given Multi-Layer Support
cs.LG cs.CV cs.NE
Stochastic Gradient Descent (SGD) is the central workhorse for training
modern CNNs. Although giving impressive empirical performance it can be slow to
converge. In this paper we explore a novel strategy for training a CNN using an
alternation strategy that offers substantial speedups during training. We make
the following contributions: (i) replace the ReLU non-linearity within a CNN
with positive hard-thresholding, (ii) reinterpret this non-linearity as a
binary state vector making the entire CNN linear if the multi-layer support is
known, and (iii) demonstrate that under certain conditions a global optima to
the CNN can be found through local descent. We then employ a novel alternation
strategy (between weights and support) for CNN training that leads to
substantially faster convergence rates, nice theoretical properties, and
achieving state of the art results across large scale datasets (e.g. ImageNet)
as well as other standard benchmarks.
| arxiv topic:cs.LG cs.CV cs.NE |
arxiv_dataset-92121712.02601 | Blind Multi-user Detection for Autonomous Grant-free High-Overloading MA
without Reference Signal
cs.IT math.IT
In this paper, a novel blind multi-user detection(MUD) framework for
autonomous grant-free high-overloading non-orthogonal multiple access is
introduced in detail aimed at fulfilling the requirements of fifth-generation
massive Machine Type Communications. From the perspective of the transmitter
side, pros and cons regarding diverse types of emerging grant-free
transmission, particularly autonomous grant-free, are elaborated and presented
in a comparative manner. In the receiver end,code word-level successive
interference cancellation (CL-SIC) is revealed as the main framework to perform
MUD. In addition, underpinning state-of-art blind ideas such as blind
activation detection taking advantage of the statistical metric of the
aggregate signals, blind equalization based on the constellation's simple
geometric character of low order modulation symbols, and blind channel
estimation employing solely the successfully decoded code words are explained.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-92131712.02701 | A duality principle for non-linear elasticity
math.OC
This article develops a duality principle for non-linear elasticity. The
results are obtained through standard tools of convex analysis and the Legendre
transform concept. We emphasize the dual variational formulation is concave.
Moreover, sufficient optimality conditions are also established.
| arxiv topic:math.OC |
arxiv_dataset-92141712.02801 | 3d Abelian Dualities with Boundaries
hep-th cond-mat.mes-hall
We establish the action of three-dimensional bosonization and particle-vortex
duality in the presence of a boundary, which supports a non-anomalous
two-dimensional theory. We confirm our prescription using a microscopic
realization of the duality in terms of a Euclidean lattice.
| arxiv topic:hep-th cond-mat.mes-hall |
arxiv_dataset-92151712.02901 | Disintegration of an Eruptive Filament via Interactions with
Quasi-Separatrix Layers
astro-ph.SR
The disintegration of solar filaments via mass drainage is a frequently
observed phenomenon during a variety of filament activities. It is generally
considered that the draining of dense filament material is directed by both
gravity and magnetic field, yet the detailed process remains elusive. Here we
report on a partial filament eruption during which filament material drains
downward to the surface not only along the filament's legs, but to a remote
flare ribbon through a fan-out curtain-like structure. It is found that the
magnetic configuration is characterized by two conjoining dome-like
quasi-sepratrix layers (QSLs). The filament is located underneath one QSL dome,
whose footprint apparently bounds the major flare ribbons resulting from the
filament eruption, whereas the remote flare ribbon matches well with the other
QSL dome's far-side footprint. We suggest that the interaction of the filament
with the overlying QSLs results in the splitting and disintegration of the
filament.
| arxiv topic:astro-ph.SR |
arxiv_dataset-92161712.03001 | Attracted by an elliptic fixed point
math.DS
We give examples of symplectic diffeomorphisms of R^6 for which the origin is
a non-resonant elliptic fixed point which attracts an orbit.
| arxiv topic:math.DS |
arxiv_dataset-92171712.03101 | Combining symmetry breaking and restoration with configuration
interaction: extension to z-signature symmetry in the case of the Lipkin
Model
nucl-th cond-mat.supr-con
Background: Ab initio many-body methods whose numerical cost scales
polynomially with the number of particles have been developed over the past
fifteen years to tackle closed-shell mid-mass nuclei. Open-shell nuclei have
been further addressed by implementing variants based on the concept of
spontaneous symmetry breaking (and restoration).
Purpose: In order to access the spectroscopy of open-shell nuclei more
systematically while controlling the numerical cost, we design a novel
many-body method that combines the merit of breaking and restoring symmetries
with those brought about by low-rank individual excitations.
Methods: The recently proposed truncated configuration-interaction method
based on optimized symmetry-broken and -restored states is extended to the
z-signature symmetry associated with a discrete subgroup of SU(2). The
highly-truncated N-body Hilbert subspace within which the Hamiltonian is
diagonalized is spanned by a z-signature broken and restored Slater determinant
vacuum and associated low-rank excitations.
Results: The proposed method provides an excellent reproduction of the
ground-state energy and of low-lying excitation energies of various
z-signatures and total angular momenta. In doing so, the successive benefits of
(i) breaking the symmetry, (ii) restoring the symmetry, (iii) including
low-rank particle-hole excitations and (iv) optimizing the amount by which the
underlying vacuum breaks the symmetry are illustrated.
Conclusions: The numerical cost of the newly designed variational method is
polynomial with respect to the system size. The present study confirms the
results obtained previously for the attractive pairing Hamiltonian in
connection with the breaking and restoration of U(1) global gauge symmetry.
These two studies constitute a strong motivation to apply this method to
realistic nuclear Hamiltonians.
| arxiv topic:nucl-th cond-mat.supr-con |
arxiv_dataset-92181712.03201 | Mining Fix Patterns for FindBugs Violations
cs.SE
In this paper, we first collect and track a large number of fixed and unfixed
violations across revisions of software.
The empirical analyses reveal that there are discrepancies in the
distributions of violations that are detected and those that are fixed, in
terms of occurrences, spread and categories, which can provide insights into
prioritizing violations.
To automatically identify patterns in violations and their fixes, we propose
an approach that utilizes convolutional neural networks to learn features and
clustering to regroup similar instances. We then evaluate the usefulness of the
identified fix patterns by applying them to unfixed violations.
The results show that developers will accept and merge a majority (69/116) of
fixes generated from the inferred fix patterns. It is also noteworthy that the
yielded patterns are applicable to four real bugs in the Defects4J major
benchmark for software testing and automated repair.
| arxiv topic:cs.SE |
arxiv_dataset-92191712.03301 | Measurement of the real dielectric permittivity epsilon_r of glacial ice
astro-ph.IM
Using data collected by the Askaryan Radio Array (ARA) experiment at the
South Pole, we have used long-baseline propagation of radio-frequency signals
to extract information on the radio-frequency index-of-refraction in South
Polar ice. Owing to the increasing ice density over the upper 150--200 meters,
rays are observed along two, nearly parallel paths, one of which is direct and
a second which refracts through an inflection point, with differences in both
arrival time and arrival angle that can be used to constrain the neutrino
properties. We also observe indications, for the first time, of radio-frequency
ice birefringence for signals propagating along predominantly horizontal
trajectories, corresponding to an asymmetry of order 0.1% between the ordinary
and extra-ordinary paths, numerically compatible with previous measurements of
birefringent asymmetries for vertically-propagating radio-frequency signals at
South Pole. Taken together, these effects offer the possibility of redundantly
measuring the range from receiver to a neutrino interaction in Antarctic ice,
if receiver antennas are deployed at shallow (25 m<z<100 m) depths. Such range
information is essential in determining both the neutrino energy, as well as
the incident neutrino direction.
| arxiv topic:astro-ph.IM |
arxiv_dataset-92201712.03401 | Exploiting WiFi Channel State Information for Residential Healthcare
Informatics
eess.SP
Detection and interpretation of human activities have emerged as a
challenging healthcare problem in areas such as assisted living and remote
monitoring. Besides traditional approaches that rely on wearable devices and
camera systems, WiFi based technologies are evolving as a promising solution
for indoor monitoring and activity recognition. This is, in part, due to the
pervasive nature of WiFi in residential settings such as homes and care
facilities, and unobtrusive nature of WiFi based sensing. Advanced signal
processing techniques can accurately extract WiFi channel status information
(CSI) using commercial off-the-shelf (COTS) devices or bespoke hardware. This
includes phase variations, frequency shifts and signal levels. In this paper,
we describe the healthcare application of Doppler shifts in the WiFi CSI,
caused by human activities which take place in the signal coverage area. The
technique is shown to recognize different types of human activities and
behaviour and be very suitable for applications in healthcare. Three
experimental case studies are presented to illustrate the capabilities of WiFi
CSI Doppler sensing in assisted living and residential care environments. We
also discuss the potential opportunities and practical challenges for
real-world scenarios.
| arxiv topic:eess.SP |
arxiv_dataset-92211712.03501 | Switching of magnons by electric and magnetic fields in multiferroic
borates
cond-mat.mtrl-sci
Electric manipulation of magnetic properties is a key problem of materials
research. To fulfil the requirements of modern electronics, these processes
must be shifted to high frequencies. In multiferroic materials this may be
achieved by electric and magnetic control of their fundamental excitations.
Here we identify magnetic vibrations in multiferroic iron-borates which are
simultaneously sensitive to external electric and magnetic fields. Nearly 100%
modulation of the terahertz radiation in an external field is demonstrated for
SmFe3(BO3)4. High sensitivity can be explained by a modification of the spin
orientation which controls the excitation conditions in multiferroic borates.
These experiments demonstrate the possibility to alter terahertz magnetic
properties of materials independently by external electric and magnetic fields.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-92221712.03601 | An explicit isomorphism between quantum and classical sl(n)
math.RT
Let g be a complex, semisimple Lie algebra. Drinfeld showed that the quantum
group associated to g is isomorphic as an algebra to the trivial deformation of
the universal enveloping algebra of g. In this paper we construct explicitly
such an isomorphism when g = sl(n), previously known only for n=2.
| arxiv topic:math.RT |
arxiv_dataset-92231712.03701 | RG analysis at higher orders in perturbative QFTs in CMP
hep-ph
In this contribution we report on the perturbative determination of
$\beta$-functions and anomalous dimensions for the chiral Ising, chiral XY and
chiral Heisenberg Gross-Neveu-Yukawa model around $D=4$ dimensions at four
loops and the first Pad\'e extrapolation of critical exponents at non-trivial,
infrared stable fixed points to $D=3$ to this order. This talk is based on Ref.
[Zerf:2017zqi].
| arxiv topic:hep-ph |
arxiv_dataset-92241712.03801 | On the Zariski topology of $\Omega$-groups
math.AG
A number of geometric properties of $\Omega$-groups from a given variety of
$\Omega$-groups can be characterized using the notions of domain and equational
domain. An $\Omega$-group $H$ of a variety $\Theta$ is an equational domain in
$\Theta$ if the union of algebraic varieties over $H$ is an algebraic variety.
We give necessary and sufficient conditions for an $\Omega$-group $H$ in
$\Theta$ to be an equational domain in this variety.
| arxiv topic:math.AG |
arxiv_dataset-92251712.03901 | Label-free optical vibrational spectroscopy to detect the metabolic
state of M. tuberculosis cells at the site of disease
physics.bio-ph physics.optics
Tuberculosis relapse is a barrier to shorter treatment. It is thought that
lipid rich cells, phenotypically resistant to antibiotics, may play a major
role. Most studies investigating relapse use sputum samples although tissue
bacteria may play an important role. We developed a non-destructive, label-free
technique combining wavelength modulated Raman (WMR) spectroscopy and
fluorescence detection (Nile Red staining) to interrogate Mycobacterium
tuberculosis cell state. This approach could differentiate single 'dormant'
(lipid rich, LR) and 'non-dormant' (lipid poor, LP) cells with high sensitivity
and specificity. We applied this to experimentally infected guinea pig lung
sections and were able to distinguish both cell types showing that the LR
phenotype dominates in infected tissue. Both in-vitro and ex-vivo spectra
correlated well, showing for the first time that Mycobacterium tuberculosis,
likely to be phenotypically resistant to antibiotics, are present in large
numbers in tissue. This is an important step in understanding the pathology of
relapse supporting the idea that they may be caused by M. tuberculosis cells
with lipid inclusions.
| arxiv topic:physics.bio-ph physics.optics |
arxiv_dataset-92261712.04001 | Sensitivity of seismically cued antineutrino detectors to nuclear
explosions
nucl-ex hep-ex physics.app-ph physics.ins-det
We evaluate the sensitivity of large, gadolinium-doped water detectors to
antineutrinos released by nuclear fission explosions, using updated signal and
background models and taking advantage of the capacity for seismic observations
to provide an analysis trigger. Under certain realistic conditions, the
antineutrino signature of a 250-kiloton pure fission explosion could be
identified several hundred kilometers away in a detector about the size of the
largest module currently proposed for a basic physics experiment. In principle,
such an observation could provide rapid confirmation that the seismic signal
coincided with a fission event, possibly useful for international monitoring of
nuclear weapon tests. We discuss the limited potential for seismically cued
antineutrino observations to constrain fission yield, differentiate pure
fission from fusion-enhanced weapon tests, indicate that the seismic evidence
of an explosion had been intentionally masked, or verify the absence of
explosive testing in a targeted area. We conclude that advances in seismic
monitoring and neutrino physics have made the detection of explosion-derived
antineutrinos more conceivable than previously asserted, but the size and cost
of sufficiently sensitive detectors continue to limit applications.
| arxiv topic:nucl-ex hep-ex physics.app-ph physics.ins-det |
arxiv_dataset-92271712.04101 | Deep Reinforcement Learning Boosted by External Knowledge
cs.LG
Recent improvements in deep reinforcement learning have allowed to solve
problems in many 2D domains such as Atari games. However, in complex 3D
environments, numerous learning episodes are required which may be too time
consuming or even impossible especially in real-world scenarios. We present a
new architecture to combine external knowledge and deep reinforcement learning
using only visual input. A key concept of our system is augmenting image input
by adding environment feature information and combining two sources of
decision. We evaluate the performances of our method in a 3D
partially-observable environment from the Microsoft Malmo platform.
Experimental evaluation exhibits higher performance and faster learning
compared to a single reinforcement learning model.
| arxiv topic:cs.LG |
arxiv_dataset-92281712.04201 | On the Energy-Efficient Deployment for Ultra-Dense Heterogeneous
Networks with NLoS and LoS Transmissions
cs.NI
We investigate network performance of ultra-dense heterogeneous networks
(HetNets) and study the maximum energy-efficient base station (BS) deployment
incorporating probabilistic non-line-of-sight (NLoS) and line-of-sight (LoS)
transmissions. First, we develop an analytical framework with the maximum
instantaneous received power (MIRP) and the maximum average received power
(MARP) association schemes to model the coverage probability and related
performance metrics, e.g., the potential throughput (PT) and the energy
efficiency (EE). Second, we formulate two optimization problems to achieve the
maximum energy-efficient deployment solution with specific service criteria.
Simulation results show that there are tradeoffs among the coverage
probability, the total power consumption, and the EE. To be specific, the
maximum coverage probability with ideal power consumption is superior to that
with practical power consumption when the total power constraint is small and
inferior to that with practical power consumption when the total power
constraint becomes large. Moreover, the maximum EE is a decreasing function
with respect to the coverage probability constraint.
| arxiv topic:cs.NI |
arxiv_dataset-92291712.04301 | Deep Learning for IoT Big Data and Streaming Analytics: A Survey
cs.NI cs.DB cs.LG
In the era of the Internet of Things (IoT), an enormous amount of sensing
devices collect and/or generate various sensory data over time for a wide range
of fields and applications. Based on the nature of the application, these
devices will result in big or fast/real-time data streams. Applying analytics
over such data streams to discover new information, predict future insights,
and make control decisions is a crucial process that makes IoT a worthy
paradigm for businesses and a quality-of-life improving technology. In this
paper, we provide a thorough overview on using a class of advanced machine
learning techniques, namely Deep Learning (DL), to facilitate the analytics and
learning in the IoT domain. We start by articulating IoT data characteristics
and identifying two major treatments for IoT data from a machine learning
perspective, namely IoT big data analytics and IoT streaming data analytics. We
also discuss why DL is a promising approach to achieve the desired analytics in
these types of data and applications. The potential of using emerging DL
techniques for IoT data analytics are then discussed, and its promises and
challenges are introduced. We present a comprehensive background on different
DL architectures and algorithms. We also analyze and summarize major reported
research attempts that leveraged DL in the IoT domain. The smart IoT devices
that have incorporated DL in their intelligence background are also discussed.
DL implementation approaches on the fog and cloud centers in support of IoT
applications are also surveyed. Finally, we shed light on some challenges and
potential directions for future research. At the end of each section, we
highlight the lessons learned based on our experiments and review of the recent
literature.
| arxiv topic:cs.NI cs.DB cs.LG |
arxiv_dataset-92301712.04401 | Interior-exterior penalty approach for solving elasto-hydrodynamic
lubrication problem: Part I
math.NA
A new interior-exterior penalty method for solving quasi-variational
inequality and pseudo-monotone operators arising in two-dimensional point
contact problem has been analyzed and developed in discontinuous Galerkin
finite volume method environment. In this article, we proved the existence of
solution for the more realistic model problem without taking any constant
assumption in viscosity or density of the lubricant. We have shown that optimal
error estimate of $H^{1}$ and $L^{2}$ norm can be achieved under a light load
non-dimensional parameter condition. In addition, we provided a complete
algorithm to tackle all numerical complexities appear in the solution
procedure. We obtained results for moderate loaded conditions which have been
discussed at the end of the section. Furthermore, results give a hope for the
further development of the scheme for highly loaded condition appeared in a
more realistic operating situation which will be discussed in part II. This
method is well suited for solving elasto-hydrodynamic lubrication line as well
as point contact problems and can probably be treated as commercial software.
| arxiv topic:math.NA |
arxiv_dataset-92311712.04501 | Maximum-Likelihood Power-Distortion Monitoring for GNSS Signal
Authentication
eess.SP cs.CR
We propose an extension to the so-called PD detector. The PD detector jointly
monitors received power and correlation profile distortion to detect the
presence of GNSS carry-off-type spoofing, jamming, or multipath. We show that
classification performance can be significantly improved by replacing the PD
detector's symmetric-difference-based distortion measurement with one based on
the post-fit residuals of the maximum-likelihood estimate of a single-signal
correlation function model. We call the improved technique the PD-ML detector.
In direct comparison with the PD detector, the PD-ML detector exhibits improved
classification accuracy when tested against an extensive library of recorded
field data. In particular, it is (1) significantly more accurate at
distinguishing a spoofing attack from a jamming attack, (2) better at
distinguishing multipath-afflicted data from interference-free data, and (3)
less likely to issue a false alarm by classifying multipath as spoofing. The
PD-ML detector achieves this improved performance at the expense of additional
computational complexity.
| arxiv topic:eess.SP cs.CR |
arxiv_dataset-92321712.04601 | Transition between Kerr comb and stimulated Raman comb in a silica
whispering gallery mode microcavity
physics.optics
We theoretically and experimentally investigated the transition between
modulation instability and Raman gain in a small silica microcavity with a
large free-spectral range (FSR), which reveals that we can selectively switch
from a four-wave mixing dominant state to a stimulated Raman scattering
dominant state. Both the theoretical analysis and the experiment show that a
Raman-dominant region is present between transitions of Kerr combs with
different free-spectral range spacings. We can obtain a stable Kerr comb and a
stable Raman state selectively by changing the driving power, coupling between
the cavity and the waveguide, and laser detuning. Such a controllable
transition is achieved thanks to the presence of gain competition between
modulation instability and Raman gain in silica whispering gallery mode
microcavities.
| arxiv topic:physics.optics |
arxiv_dataset-92331712.04701 | Reconnection fluxes in eruptive and confined flares and implications for
superflares on the Sun
astro-ph.SR
We study the energy release process of a set of 51 flares (32 confined, 19
eruptive) ranging from GOES class B3 to X17. We use H$\alpha$ filtergrams from
Kanzelh\"ohe Observatory together with SDO HMI and SOHO MDI magnetograms to
derive magnetic reconnection fluxes and rates. The flare reconnection flux is
strongly correlated with the peak of the GOES 1-8 \AA\ soft X-ray flux (c=0.92,
in log-log space), both for confined and eruptive flares. Confined flares of a
certain GOES class exhibit smaller ribbon areas but larger magnetic flux
densities in the flare ribbons (by a factor of 2). In the largest events, up to
$\approx$50\%\ of the magnetic flux of the active region (AR) causing the flare
is involved in the flare magnetic reconnection. These findings allow us to
extrapolate toward the largest solar flares possible. A complex solar AR
hosting a magnetic flux of $2\cdot 10^{23}\, \mathrm{Mx}$, which is in line
with the largest AR fluxes directly measured, is capable of producing an X80
flare, which corresponds to a bolometric energy of about $7 \cdot 10^{32}$
ergs. Using a magnetic flux estimate of $6\cdot 10^{23}\, \mathrm{Mx}$ for the
largest solar AR observed, we find that flares of GOES class $\approx$X500
could be produced ($E_{\rm bol} \approx 3 \cdot 10^{33}$ ergs). These estimates
suggest that the present day's Sun is capable of producing flares and related
space weather events that may be more than an order of magnitude stronger than
have been observed to date.
| arxiv topic:astro-ph.SR |
arxiv_dataset-92341712.04801 | Open data, open review and open dialogue in making social sciences
plausible
stat.OT stat.ME
Nowadays, protecting trust in social sciences also means engaging in open
community dialogue, which helps to safeguard robustness and improve efficiency
of research methods. The combination of open data, open review and open
dialogue may sound simple but implementation in the real world will not be
straightforward. However, in view of Begley and Ellis's (2012) statement that,
"the scientific process demands the highest standards of quality, ethics and
rigour," they are worth implementing. More importantly, they are feasible to
work on and likely will help to restore plausibility to social sciences
research. Therefore, I feel it likely that the triplet of open data, open
review and open dialogue will gradually emerge to become policy requirements
regardless of the research funding source.
| arxiv topic:stat.OT stat.ME |
arxiv_dataset-92351712.04901 | Earth-Scattering of super-heavy Dark Matter: updated constraints from
detectors old and new
hep-ph astro-ph.CO
Direct searches for Dark Matter (DM) are continuously improving, probing down
to lower and lower DM-nucleon interaction cross sections. For
strongly-interacting massive particle (SIMP) Dark Matter, however, the
accessible cross section is bounded from above due to the stopping effect of
the atmosphere, Earth and detector shielding. We present a careful calculation
of the SIMP signal rate, focusing on super-heavy DM ($m_\chi \gtrsim 10^5
\,\,\mathrm{GeV}$) for which the standard nuclear-stopping formalism is
applicable, and provide code for implementing this calculation numerically.
With recent results from the low-threshold CRESST 2017 surface run, we improve
the maximum cross section reach of direct detection searches by a factor of
around 5000, for DM masses up to $10^8 \,\,\mathrm{GeV}$. A reanalysis of the
longer-exposure, sub-surface CDMS-I results (published in 2002) improves the
previous cross section reach by two orders of magnitude, for masses up to
$10^{15} \,\,\mathrm{GeV}$. Along with complementary constraints from SIMP
capture and annihilation in the Earth and Sun, these improved limits from
direct nuclear scattering searches close a number of windows in the SIMP
parameter space in the mass range $10^6$ GeV to $10^{13}$ GeV, of particular
interest for heavy DM produced gravitationally at the end of inflation.
| arxiv topic:hep-ph astro-ph.CO |
arxiv_dataset-92361712.05001 | On the ultra-relativistic Prompt Emission (UPE), the Hard and Soft X-ray
Flares, and the extended thermal emission (ETE) in GRB 151027A
astro-ph.HE
We analyze GRB 151027A within the binary-driven hypernova (BdHN) approach,
with progenitor a carbon-oxygen core on the verge of a supernova (SN) explosion
and a binary companion neutron star (NS). The hypercritical accretion of the SN
ejecta onto the NS leads to its gravitational collapse into a black hole (BH),
to the emission of the GRB and to a copious $e^+e^-$ plasma. The impact of this
$e^+e^-$ plasma on the SN ejecta explains {the} early soft X-ray flare observed
in long GRBs. We here apply this approach to the UPE and to the hard X-ray
flares. We use GRB 151027A as a prototype. From the time-integrated and the
time-resolved analysis we identify a double component in the UPE and confirm
its ultra-relativistic nature. We confirm the mildly-relativistic nature of the
soft X-ray flare, of the hard X-ray flare and of the ETE. We show that the ETE
identifies the transition from a SN to the HN. We then address the theoretical
justification of these observations by integrating the hydrodynamical
propagation equations of the $e^+ e^-$ into the SN ejecta, the latter
independently obtained from 3D smoothed-particle-hydrodynamics simulations. We
conclude that the UPE, the hard X-ray flare and the soft X-ray flare do not
form a causally connected sequence: Within our model they are the manifestation
of \textbf{the same} physical process of the BH formation as seen through
different viewing angles, implied by the morphology and the $\sim 300$~s
rotation period of the HN ejecta.
| arxiv topic:astro-ph.HE |
arxiv_dataset-92371712.05101 | Range Queries in Non-blocking $k$-ary Search Trees
cs.DC
We present a linearizable, non-blocking $k$-ary search tree ($k$-ST) that
supports fast searches and range queries. Our algorithm uses single-word
compare-and-swap (CAS) operations, and tolerates any number of crash failures.
Performance experiments show that, for workloads containing small range
queries, our $k$-ST significantly outperforms other algorithms which support
these operations, and rivals the performance of a leading concurrent skip-list,
which provides range queries that cannot always be linearized.
| arxiv topic:cs.DC |
arxiv_dataset-92381712.05201 | Muon spin relaxation and inelastic neutron scattering investigations of
all-in/all-out antiferromagnet Nd2Hf2O7
cond-mat.str-el cond-mat.mtrl-sci
Nd2Hf2O7, belonging to the family of geometrically frustrated cubic rare
earth pyrochlore oxides, was recently identified to order antiferromagnetically
below T_N = 0.55 K with an all-in/all-out arrangement of Nd3+ moments, however
with a much reduced ordered state moment. Herein we investigate the spin
dynamics and crystal field states of Nd2Hf2O7 using muon spin relaxation (muSR)
and inelastic neutron scattering (INS) measurements. Our muSR study confirms
the long range magnetic ordering and shows evidence for coexisting persistent
dynamic spin fluctuations deep inside the ordered state down to 42 mK. The INS
data show the crytal electric field (CEF) excitations due to the transitions
both within the ground state multiplet and to the first excited state
multiplet. The INS data are analyzed by a model based on CEF and crystal field
states are determined. Strong Ising-type anisotropy is inferred from the ground
state wavefunction. The CEF parameters indicate the CEF-split Kramers doublet
ground state of Nd3+ to be consistent with the dipolar-octupolar character.
| arxiv topic:cond-mat.str-el cond-mat.mtrl-sci |
arxiv_dataset-92391712.05301 | The Many Routes to AGN Feedback
astro-ph.GA
The energy released by Active Galactic Nuclei (AGN) in the form of radiation,
winds, or radio plasma jets, is known to impact on the surrounding interstellar
medium. The result of these processes, known as AGN (negative) feedback, is
suggested to prevent gas, in and around galaxies, from cooling, and to remove,
or at least redistribute, gas by driving massive and fast outflows, hence
playing a key role in galaxy evolution. Given its importance, a large effort is
devoted by the astronomical community to trace the effects of AGN on the
surrounding gaseous medium and to quantify their impact for different types of
AGN. This review briefly summarizes some of the recent observational results
obtained in different wavebands, tracing different phases of the gas. I also
summarize the new insights they have brought, and the constraints they provide
to numerical simulations of galaxy formation and evolution. The recent addition
of deep observations of cold gas and, in particular, of cold molecular gas, has
brought some interesting surprises and has expanded our understanding of AGN
and AGN feedback.
| arxiv topic:astro-ph.GA |
arxiv_dataset-92401712.05401 | swordfish: Efficient Forecasting of New Physics Searches without Monte
Carlo
hep-ph physics.data-an
We introduce swordfish, a Monte-Carlo-free Python package to predict expected
exclusion limits, the discovery reach and expected confidence contours for a
large class of experiments relevant for particle- and astrophysics. The tool is
applicable to any counting experiment, supports general correlated background
uncertainties, and gives exact results in both the signal- and
systematics-limited regimes. Instead of time-intensive Monte Carlo simulations
and likelihood maximization, it internally utilizes new approximation methods
that are built on information geometry. Out of the box, swordfish provides
straightforward methods for accurately deriving many of the common sensitivity
measures. In addition, it allows one to examine experimental abilities in great
detail by employing the notion of information flux. This new concept
generalizes signal-to-noise ratios to situations where background uncertainties
and component mixing cannot be neglected. The user interface of swordfish is
designed with ease-of-use in mind, which we demonstrate by providing typical
examples from indirect and direct dark matter searches as jupyter notebooks.
| arxiv topic:hep-ph physics.data-an |
arxiv_dataset-92411712.05501 | Permutation Modules associated to the Hyperoctahedron and Group Actions
math.CO
We investigate the permutation modules associated to the set of
$k$-dimensional faces of the hyperoctahedron in dimension $n$, denoted $H^{n}.$
For any $k\leq n$ such a module can be defined over an arbitrary field $F$, it
is called a face module of $H^{n}$ over $F.$ We describe a spectral
decomposition of such face modules into submodules and show that these
submodules are irreducible under the hyperoctahedral group $B_{n}.$ The same
method can be used to describe the exact relationship between the face modules
in any two dimensions $0\leq t\leq k\leq n.$ Applications of this technique
include a rank formula for the rank of the incidence matrix of $t$-dimensional
versus $k$-dimensional faces of $H^{n}$ and a characterization of
$(t,k,\ell)$-designs on $H^{n}.$ We also prove an orbit theorem for subgroups
of the hyperoctahedral group on the set of faces of $H^{n}.$ The decomposition
method is elementary, mostly characteristic free and does not involve the
representation theory of automorphism groups. It is therefore quite general and
can be used to decompose permutation modules associated to other geometries.
| arxiv topic:math.CO |
arxiv_dataset-92421712.05601 | Asymptotics of the contour of the stationary phase and efficient
evaluation of the Mellin-Barnes integral for the F_3 structure function
hep-ph
A new approximation is proposed for the contour of the stationary phase of
the Mellin--Barnes integrals in the case of its finite asymptotic behavior as
${\rm Re} z\to -\infty$. The efficiency of application of the proposed contour
and the quadratic approximation to the contour of the stationary phase is
compared by the example of the inverse Mellin transform for the structure
function $F_3$. It is shown that, although for a small number of terms $N$ in
quadrature formulas used to calculate integrals along these contours, the
quadratic contour is more efficient, but for $N>20$ the asymptotic stationary
phase integration contour gives better accuracy. The case of the
$Q^2$-dependence of the $F_3$ structure function is also considered.
| arxiv topic:hep-ph |
arxiv_dataset-92431712.05701 | High-Reflection Coatings for Gravitational-Wave Detectors: State of The
Art and Future Developments
physics.ins-det physics.app-ph
We report on the optical, mechanical and structural characterization of the
sputtered coating materials of Advanced LIGO, Advanced Virgo and KAGRA
gravitational-waves detectors. We present the latest results of our research
program aiming at decreasing coating thermal noise through doping, optimization
of deposition parameters and post-deposition annealing. Finally, we propose
sputtered Si3N4 as a candidate material for the mirrors of future detectors.
| arxiv topic:physics.ins-det physics.app-ph |
arxiv_dataset-92441712.05801 | Fragmentation Uncertainties in Hadronic Observables for Top-quark Mass
Measurements
hep-ph hep-ex
We study the Monte Carlo uncertainties due to modeling of hadronization and
showering in the extraction of the top-quark mass from observables that use
exclusive hadronic final states in top decays, such as $t \rightarrow
\text{anything+J/}\psi$ or $t\rightarrow \text{anything}+(B\rightarrow
\text{charged tracks})$, where $B$ is a $B$-hadron. To this end, we investigate
the sensitivity of the top-quark mass, determined by means of a few observables
already proposed in the literature as well as some new proposals, to the
relevant parameters of event generators, such as HERWIG 6 and PYTHIA 8. We find
that constraining those parameters at $\mathcal{O}(1\%-10\%)$ is required to
avoid a Monte Carlo uncertainty on $m_t$ greater than 500 MeV. For the sake of
achieving the needed accuracy on such parameters, we examine the sensitivity of
the top-quark mass measured from spectral features, such as peaks, endpoints
and distributions of $E_{B}$, $m_{B\ell}$, and some $m_{T2}$-like variables. We
find that restricting oneself to regions sufficiently close to the endpoints
enables one to substantially decrease the dependence on the Monte Carlo
parameters, but at the price of inflating significantly the statistical
uncertainties. To ameliorate this situation we study how well the data on
top-quark production and decay at the LHC can be utilized to constrain the
showering and hadronization variables. We find that a global exploration of
several calibration observables, sensitive to the Monte Carlo parameters but
very mildly to $m_{t}$, can offer useful constraints on the parameters, as long
as such quantities are measured with a 1% precision.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-92451712.05901 | Automatic Music Highlight Extraction using Convolutional Recurrent
Attention Networks
cs.LG cs.MM cs.SD stat.ML
Music highlights are valuable contents for music services. Most methods
focused on low-level signal features. We propose a method for extracting
highlights using high-level features from convolutional recurrent attention
networks (CRAN). CRAN utilizes convolution and recurrent layers for sequential
learning with an attention mechanism. The attention allows CRAN to capture
significant snippets for distinguishing between genres, thus being used as a
high-level feature. CRAN was evaluated on over 32,000 popular tracks in Korea
for two months. Experimental results show our method outperforms three baseline
methods through quantitative and qualitative evaluations. Also, we analyze the
effects of attention and sequence information on performance.
| arxiv topic:cs.LG cs.MM cs.SD stat.ML |
arxiv_dataset-92461712.06001 | Status of the Theoretical Calculation of Nuclear Electric Dipole Moment
nucl-th hep-ex hep-ph nucl-ex
The electric dipole moment is a very sensitive probe of CP violation beyond
the standard model. Light nuclei are particularly interesting since the CP
violation may be enhanced by nuclear many-body effects. In this proceeding, we
present the current status of the theoretical evaluations of the electric
dipole moment of light nuclei in the ab initio approach and in the cluster
model. We add the preliminary result of the evaluation of the electric dipole
moment of $^7$Li which is treated in a cluster model with a triton.
| arxiv topic:nucl-th hep-ex hep-ph nucl-ex |
arxiv_dataset-92471712.06101 | A universal macroscopic theory of surface plasma waves and their losses
cond-mat.mes-hall
Recently, we have revealed an intrinsic instability of metals due to surface
plasma waves (SPWs) and raised the prospect of using it to create lossless
SPWs. The counter-intuitive nature of this finding prompts one to ask, why had
not this instability been disclosed before, given the long history of this
subject? If this instability does exist, how far is it from reality? The
present work is devoted to answering these questions. To this end, we derive a
unified macroscopic theory of SPWs that applies to any type of electron
dynamics, be they local or non-local, classical or quantum-mechanical. In light
of this theory, we analyze the behaviors of SPWs according to several electron
dynamics models, including the widely used local dielectric model (DM), the
hydrodynamic model (HDM) and the specular reflection model (SRM), in addition
to the less common semi-classical model (SCM). We find that, in order to unveil
the instability, one must (i) self-consistently treat surface effects without
any of the usually imposed auxiliary conditions and (ii) include translation
symmetry breaking effects in electron dynamics. As far as we are concerned,
none existing work had fulfilled both (i) and (ii). To assess the possibility
of realizing the instability, we analyze two very important factors: the
dielectric interfacing the metal and inter-band transitions, which both were
ignored in our recent work. Whereas inter-band absorption -- together with
Landau damping -- is shown adverse to the instability, a dielectric brings it
closer to occurrence. One may even attain it in common plasmonic materials such
as silver under not so tough conditions.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-92481712.06201 | Continious-time Importance Sampling: Monte Carlo Methods which Avoid
Time-discretisation Error
stat.ME math.PR stat.CO
In this paper we develop a continuous-time sequential importance sampling
(CIS) algorithm which eliminates time-discretisation errors and provides online
unbiased estimation for continuous time Markov processes, in particular for
diffusions. Our work removes the strong conditions imposed by the EA and thus
extends significantly the class of discretisation error-free MC methods for
diffusions. The reason that CIS can be applied more generally than EA is that
it no longer works on the path space of the SDE. Instead it uses proposal
distributions for the transition density of the diffusion, and proposal
distributions that are absolutely continuous with respect to the true
transition density exist for general SDEs.
| arxiv topic:stat.ME math.PR stat.CO |
arxiv_dataset-92491712.06301 | Gaussian representation of a class of Riesz probabilitydistributions
math.PR
The Wishart probability distribution on symmetricmatrices has been initially
defined by mean of the multivariateGaussian distribution as an of the
chi-square distribution. A moregeneral definition is given using results for
harmonic analysis.Recently a probability distribution on symmetric matrices
called theRiesz distribution has been defined by its Laplace transform as
ageneralization of the Wishart distribution. The aim of the presentpaper is to
show that some Riesz probability distributions which arenot necessarily Wishart
may also be presented by mean of theGaussian distribution using Gaussian
samples with missing data.
| arxiv topic:math.PR |
arxiv_dataset-92501712.06401 | Two-dimensional Yukawa interaction driven by a nonlocal-Proca quantum
electrodynamics
hep-th cond-mat.str-el
We derive two versions of an effective model to describe dynamical effects of
the Yukawa interaction among Dirac electrons in the plane. Such short-range
interaction is obtained by introducing a mass term for the intermediate
particle, which may be either scalar or an abelian gauge field, both of them in
(3+1) dimensions. Thereafter, we consider that the matter field propagates only
in (2+1) dimensions, whereas the bosonic field is free to propagate out of the
plane. Within these assumptions, we apply a mechanism for dimensional
reduction, which yields an effective model in (2+1) dimensions. In particular,
for the gauge-field case, we use the Stueckelberg mechanism in order to
preserve gauge invariance. We refer to this version as nonlocal-Proca quantum
electrodynamics (NPQED). For both scalar and gauge cases, the effective models
reproduce the usual $e^{-m r}/r$ Yukawa interaction in the static limit. By
means of perturbation theory at one loop, we calculate the mass renormalization
of the Dirac field. Our model is a generalization of Pseudoquantum
electrodynamics (PQED), which is a gauge-field model that provides a Coulomb
interaction for two-dimensional electrons. Possibilities of application to
Fermi-Bose mixtures in mixed dimensions, using cold atoms, are briefly
discussed.
| arxiv topic:hep-th cond-mat.str-el |
arxiv_dataset-92511712.06501 | Room-temperature ultrafast non-linear spectroscopy of a single molecule
physics.chem-ph physics.optics
Single molecule spectroscopy aims at unveiling often hidden but potentially
very important contributions of single entities to a system's ensemble
response. Albeit contributing tremendously to our ever growing understanding of
molecular processes the fundamental question of temporal evolution, or change,
has thus far been inaccessible, resulting in a static picture of a dynamic
world. Here, we finally resolve this dilemma by performing the first ultrafast
time-resolved transient spectroscopy on a single molecule. By tracing the
femtosecond evolution of excited electronic state spectra of single molecules
over hundreds of nanometres of bandwidth at room temperature we reveal their
non-linear ultrafast response in an effective 3-pulse scheme with fluorescence
detection. A first excitation pulse is followed by a phase-locked de-excitation
pulse-pair, providing spectral encoding with 25 fs temporal resolution. This
experimental realisation of true single molecule transient spectroscopy
demonstrates that two-dimensional electronic spectroscopy of single molecules
is experimentally in reach.
| arxiv topic:physics.chem-ph physics.optics |
arxiv_dataset-92521712.06601 | Decoherence of Gravitational Wave Oscillations in Bigravity
gr-qc astro-ph.CO hep-ph
Following up on our recent study, we consider the regime of graviton masses
and gravitational wave propagation distances at which decoherence of the wave
packets plays a major role for phenomenology. This regime is of particular
interest, as it can lead to very striking phenomena of echo events in the
gravitational waves coming from coalescence events. The power of the
experimental search in this case lies in the fact that it becomes sensitive to
a large range of graviton masses, while not relying on a specific production
mechanism. We are thus able to place new relevant limits on the parameter space
of the graviton mixing angle.
| arxiv topic:gr-qc astro-ph.CO hep-ph |
arxiv_dataset-92531712.06701 | Rational Cohomology and Supports for Linear Algebraic Groups
math.RT
This paper is an extended version of four lectures at PIMS in Vancouver given
June 27 - 30, 2016. The primary goal of these lectures was to publicize the
author's recent efforts to extend to representations of linear algebraic groups
the "theory of support varieties" which has proved successful in the study of
representations of finite group schemes. The lectures offer readers an
introduction to the subject together with "homework problems, simplify and
clarify some points in the literature, and mention some directions for future
research.
| arxiv topic:math.RT |
arxiv_dataset-92541712.06801 | Detecting qubit entanglement : an alternative to the PPT test
quant-ph
We propose a Partial Lorentz Transformation (PLT) test for detecting
entanglement in a two qubit system. One can expand the density matrix of a two
qubit system in terms of a tensor product of $(\mathbb{I}, \vec{\sigma})$. The
matrix $A$ of the coefficients that appears in such an expansion can be
"squared" to form a $4\times4$ matrix $B$. It can be shown that the eigenvalues
$\lambda_0, \lambda_1, \lambda_2, \lambda_3$ of $B$ are positive. With the
choice of $\lambda_0$ as the dominant eigenvalue, the separable states satisfy
$\sqrt{\lambda_1}+\sqrt{\lambda_2}+\sqrt{\lambda_3}\leq \sqrt{\lambda_0}$.
Violation of this inequality is a test of entanglement. Thus, this condition is
both necessary and sufficient and serves as an alternative to the celebrated
Positive Partial Transpose (PPT) test for entanglement detection. We illustrate
this test by considering some explicit examples.
| arxiv topic:quant-ph |
arxiv_dataset-92551712.06901 | A topological interpretation of three Leibnizian principles within the
functional extensions
math.LO cs.LO math.GN
Three philosophical principles are often quoted in connection with Leibniz:
"objects sharing the same properties are the same object" (Identity of
indiscernibles), "everything can possibly exist, unless it yields
contradiction" (Possibility as consistency), and "the ideal elements correctly
determine the real things" (Transfer). Here we give a precise
logico-mathematical formulation of these principles within the framework of the
Functional Extensions, mathematical structures that generalize at once
compactifications, completions, and elementary extensions of models. In this
context, the above Leibnizian principles appear as topological or algebraic
properties, namely: a property of separation, a property of compactness, and a
property of directeness, respectively. Abiding by this interpretation, we
obtain the somehow surprising conclusion that these Leibnizian principles may
be fulfilled in pairs, but not all three together.
| arxiv topic:math.LO cs.LO math.GN |
arxiv_dataset-92561712.07001 | Fractional Elliptic Quasi-Variational Inequalities: Theory and Numerics
math.OC math.AP math.NA
This paper introduces an elliptic quasi-variational inequality (QVI) problem
class with fractional diffusion of order $s \in (0,1)$, studies existence and
uniqueness of solutions and develops a solution algorithm. As the fractional
diffusion prohibits the use of standard tools to approximate the QVI, instead
we realize it as a Dirichlet-to-Neumann map for a problem posed on a
semi-infinite cylinder. We first study existence and uniqueness of solutions
for this extended QVI and then transfer the results to the fractional QVI: This
introduces a new paradigm in the field of fractional QVIs. Further, we truncate
the semi-infinite cylinder and show that the solution to the truncated problem
converges to the solution of the extended problem, under fairly mild
assumptions, as the truncation parameter $\tau$ tends to infinity. Since the
constraint set changes with the solution, we develop an argument using Mosco
convergence. We state an algorithm to solve the truncated problem and show its
convergence in function space. Finally, we conclude with several illustrative
numerical examples.
| arxiv topic:math.OC math.AP math.NA |
arxiv_dataset-92571712.07101 | Improving End-to-End Speech Recognition with Policy Learning
cs.CL cs.SD eess.AS stat.ML
Connectionist temporal classification (CTC) is widely used for maximum
likelihood learning in end-to-end speech recognition models. However, there is
usually a disparity between the negative maximum likelihood and the performance
metric used in speech recognition, e.g., word error rate (WER). This results in
a mismatch between the objective function and metric during training. We show
that the above problem can be mitigated by jointly training with maximum
likelihood and policy gradient. In particular, with policy learning we are able
to directly optimize on the (otherwise non-differentiable) performance metric.
We show that joint training improves relative performance by 4% to 13% for our
end-to-end model as compared to the same model learned through maximum
likelihood. The model achieves 5.53% WER on Wall Street Journal dataset, and
5.42% and 14.70% on Librispeech test-clean and test-other set, respectively.
| arxiv topic:cs.CL cs.SD eess.AS stat.ML |
arxiv_dataset-92581712.07201 | Creation of Localized Skyrmion Bubbles in Co/Pt Bilayers using a Spin
Valve Nanopillar
cond-mat.mes-hall
We fabricate devices in which a magnetic nanopillar spin valve makes contact
to a Co/Pt bilayer thin film with perpendicular magnetic anisotropy, in order
to achieve local control of domains in the Co/Pt bilayer underneath the
nanopillar. The goal is to develop the ability to nucleate, detect, and
annihilate magnetic skyrmions in the Co/Pt using spin-polarized currents from
the nanopillar. We demonstrate the ability to distinguish the local behavior of
the Co/Pt film beneath the nanopillar from the extended film and show that the
two can switch independently of each other. This allows us to isolate a
localized domain under the pillar that can be controlled separately from the
rest of the Co/Pt film using applied currents and magnetic fields.
Micromagnetic simulations indicate that this localized domain has skyrmion
symmetry. Our results represent a first step toward controlling
room-temperature skyrmions using localized spin-transfer torque.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-92591712.07301 | Using Forbush decreases to derive the transit time of ICMEs propagating
from 1 AU to Mars
physics.space-ph astro-ph.SR
The propagation of 15 interplanetary coronal mass ejections (ICMEs) from
Earth's orbit (1 AU) to Mars (~ 1.5 AU) has been studied with their propagation
speed estimated from both measurements and simulations. The enhancement of
magnetic fields related to ICMEs and their shock fronts cause the so-called
Forbush decrease, which can be de- tected as a reduction of galactic cosmic
rays measured on-ground. We have used galactic cosmic ray (GCR) data from
in-situ measurements at Earth, from both STEREO A and B as well as GCR
measurements by the Radiation Assessment Detector (RAD) instrument onboard Mars
Science Laboratory (MSL) on the surface of Mars. A set of ICME events has been
selected during the periods when Earth (or STEREO A or B) and Mars locations
were nearly aligned on the same side of the Sun in the ecliptic plane
(so-called opposition phase). Such lineups allow us to estimate the ICMEs'
transit times between 1 and 1.5 AU by estimating the delay time of the
corresponding Forbush decreases measured at each location. We investigate the
evolution of their propagation speeds before and after passing Earth's orbit
and find that the deceleration of ICMEs due to their interaction with the
ambient solar wind may continue beyond 1 AU. We also find a substantial
variance of the speed evolution among different events revealing the dynamic
and diverse nature of eruptive solar events. Furthermore, the results are
compared to simulation data obtained from two CME propagation models, namely
the Drag-Based Model and ENLIL plus cone model.
| arxiv topic:physics.space-ph astro-ph.SR |
arxiv_dataset-92601712.07401 | Existence of solutions to discrete boundary value problem of fractional
difference equations
math.CA
In this paper, we obtained the sufficient conditions for the existence of
solutions to the discrete boundary value problems of fractional difference
equation depending on parameters. We use Krasnoselskii fixed point theorem to
establish the existence results.
| arxiv topic:math.CA |
arxiv_dataset-92611712.07501 | Nonlinear mean-field dynamo and prediction of solar activity
astro-ph.SR
We apply a nonlinear mean-field dynamo model which includes a budget equation
for the dynamics of Wolf numbers to predict solar activity. This dynamo model
takes into account the algebraic and dynamic nonlinearities of the alpha
effect, where the equation for the dynamic nonlinearity is derived from the
conservation law for the magnetic helicity. The budget equation for the
evolution of the Wolf number is based on a formation mechanism of sunspots
related to the negative effective magnetic pressure instability. This
instability redistributes the magnetic flux produced by the mean-field dynamo.
To predict solar activity on the time scale of one month we use a method based
on a combination of the numerical solution of the nonlinear mean-field dynamo
equations and the artificial neural network. A comparison of the results of the
prediction of the solar activity with the observed Wolf numbers demonstrates a
good agreement between the forecast and observations.
| arxiv topic:astro-ph.SR |
arxiv_dataset-92621712.07601 | An Analytical Perspective to Traffic Engineering in Anonymous
Communication Systems
cs.CR
Anonymous communication systems (ACS) offer privacy and anonymity through the
Internet. They are mostly free tools and are popular among users all over the
world. In the recent years, anonymity applications faced many problems
regarding traffic engineering methods. Even though they ensure privacy under
some conditions, their anonymity will be endangered by high performance
processing units. To address these issues, this study is devoted to
investigating traffic-engineering methods in anonymous communication systems,
and proposes an analytical view of the current issues in ACS privacy and
anonymity. Our study also indicates new types of solutions for these current
issues with ACS.
| arxiv topic:cs.CR |
arxiv_dataset-92631712.07701 | On the Prevalence and Nature of Computational Instruction in
Undergraduate Physics Programs across the United States
physics.ed-ph
A national survey of physics faculty was conducted to investigate the
prevalence and nature of computational instruction in physics courses across
the United States. 1246 faculty from 357 unique institutions responded to the
survey. The results suggest that more faculty have some form of computational
teaching experience than a decade ago, but it appears that this experience does
not necessarily translate to computational instruction in undergraduate
students' formal course work. Further, we find that formal programs in
computational physics are absent from most departments. A majority of faculty
do report using computation on homework and in projects, but few report using
computation with interactive engagement methods in the classroom or on exams.
Specific factors that underlie these results are the subject of future work,
but we do find that there is a variation on the reported experience with
computation and the highest degree that students can earn at the surveyed
institutions.
| arxiv topic:physics.ed-ph |
arxiv_dataset-92641712.07801 | Density Estimation with Contaminated Data: Minimax Rates and Theory of
Adaptation
math.ST stat.ME stat.TH
This paper studies density estimation under pointwise loss in the setting of
contamination model. The goal is to estimate $f(x_0)$ at some
$x_0\in\mathbb{R}$ with i.i.d. observations, $$ X_1,\dots,X_n\sim
(1-\epsilon)f+\epsilon g, $$ where $g$ stands for a contamination distribution.
In the context of multiple testing, this can be interpreted as estimating the
null density at a point. We carefully study the effect of contamination on
estimation through the following model indices: contamination proportion
$\epsilon$, smoothness of target density $\beta_0$, smoothness of contamination
density $\beta_1$, and level of contamination $m$ at the point to be estimated,
i.e. $g(x_0)\leq m$. It is shown that the minimax rate with respect to the
squared error loss is of order $$
[n^{-\frac{2\beta_0}{2\beta_0+1}}]\vee[\epsilon^2(1\wedge
m)^2]\vee[n^{-\frac{2\beta_1}{2\beta_1+1}}\epsilon^{\frac{2}{2\beta_1+1}}], $$
which characterizes the exact influence of contamination on the difficulty of
the problem. We then establish the minimal cost of adaptation to contamination
proportion, to smoothness and to both of the numbers. It is shown that some
small price needs to be paid for adaptation in any of the three cases.
Variations of Lepski's method are considered to achieve optimal adaptation.
The problem is also studied when there is no smoothness assumption on the
contamination distribution. This setting that allows for an arbitrary
contamination distribution is recognized as Huber's $\epsilon$-contamination
model. The minimax rate is shown to be $$
[n^{-\frac{2\beta_0}{2\beta_0+1}}]\vee [\epsilon^{\frac{2\beta_0}{\beta_0+1}}].
$$ The adaptation theory is also different from the smooth contamination case.
While adaptation to either contamination proportion or smoothness only costs a
logarithmic factor, adaptation to both numbers is proved to be impossible.
| arxiv topic:math.ST stat.ME stat.TH |
arxiv_dataset-92651712.07901 | Improvements to Inference Compilation for Probabilistic Programming in
Large-Scale Scientific Simulators
cs.AI physics.data-an
We consider the problem of Bayesian inference in the family of probabilistic
models implicitly defined by stochastic generative models of data. In
scientific fields ranging from population biology to cosmology, low-level
mechanistic components are composed to create complex generative models. These
models lead to intractable likelihoods and are typically non-differentiable,
which poses challenges for traditional approaches to inference. We extend
previous work in "inference compilation", which combines universal
probabilistic programming and deep learning methods, to large-scale scientific
simulators, and introduce a C++ based probabilistic programming library called
CPProb. We successfully use CPProb to interface with SHERPA, a large code-base
used in particle physics. Here we describe the technical innovations realized
and planned for this library.
| arxiv topic:cs.AI physics.data-an |
arxiv_dataset-92661712.08001 | A unified picture of strong coupling stochastic thermodynamics and time
reversals
cond-mat.stat-mech
Strong-coupling statistical thermodynamics is formulated as Hamiltonian
dynamics of an observed system interacting with another unobserved system (a
bath). It is shown that the entropy production functional of stochastic
thermodynamics, defined as the log-ratio of forward and backward system path
probabilities, is in one-to-one relation with the log-ratios of joint initial
conditions of the system and the bath. A version of strong-coupling statistical
thermodynamics where the system-bath interaction vanishes at the beginning and
the end of a process is, as is also weak-coupling stochastic thermodynamics,
related the bath initially in equilibrium by itself. The heat is then the
change of bath energy over the process. It is discussed when this heat is a
functional of system history alone. The version of strong-coupling statistical
thermodynamics introduced by Seifert and Jarzynski is related to the bath
initially in conditional equilibrium with respect to the system. This leads to
heat as another functional of system history which needs to be determined by
thermodynamic integration. The log-ratio of forward and backward system path
probabilities in a stochastic process is finally related to log-ratios of
initial conditions of a combined system and bath. It is shown that the entropy
production formulas of stochastic processes under general class of time
reversals are given by change of a bath energy in a larger underlying
Hamiltonian system. The paper highlights the centrality of time reversal in
stochastic thermodynamics, also in the case of strong coupling.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-92671712.08101 | Profit Driven Decision Trees for Churn Prediction
stat.ML cs.LG stat.AP
Customer retention campaigns increasingly rely on predictive models to detect
potential churners in a vast customer base. From the perspective of machine
learning, the task of predicting customer churn can be presented as a binary
classification problem. Using data on historic behavior, classification
algorithms are built with the purpose of accurately predicting the probability
of a customer defecting. The predictive churn models are then commonly selected
based on accuracy related performance measures such as the area under the ROC
curve (AUC). However, these models are often not well aligned with the core
business requirement of profit maximization, in the sense that, the models fail
to take into account not only misclassification costs, but also the benefits
originating from a correct classification. Therefore, the aim is to construct
churn prediction models that are profitable and preferably interpretable too.
The recently developed expected maximum profit measure for customer churn
(EMPC) has been proposed in order to select the most profitable churn model. We
present a new classifier that integrates the EMPC metric directly into the
model construction. Our technique, called ProfTree, uses an evolutionary
algorithm for learning profit driven decision trees. In a benchmark study with
real-life data sets from various telecommunication service providers, we show
that ProfTree achieves significant profit improvements compared to classic
accuracy driven tree-based methods.
| arxiv topic:stat.ML cs.LG stat.AP |
arxiv_dataset-92681712.08201 | Multilevel LDPC Lattices with Efficient Encoding and Decoding and a
Generalization of Construction D'
cs.IT math.IT
Lattice codes are elegant and powerful structures that not only can achieve
the capacity of the AWGN channel but are also a key ingredient to many
multiterminal schemes that exploit linearity properties. However, constructing
lattice codes that can realize these benefits with low complexity is still a
challenging problem. In this paper, efficient encoding and decoding algorithms
are proposed for multilevel binary LDPC lattices constructed via Construction
D' whose complexity is linear in the total number of coded bits. Moreover, a
generalization of Construction D' is proposed that relaxes some of the nesting
constraints on the parity-check matrices of the component codes, leading to a
simpler and improved design. Based on this construction, low-complexity
multilevel LDPC lattices are designed whose performance under multistage
decoding is comparable to that of polar lattices and close to that of
low-density lattice codes (LDLC) on the power-unconstrained AWGN channel.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-92691712.08301 | Atomic properties of actinide ions with particle-hole configurations
physics.atom-ph physics.optics quant-ph
We study the effects of higher-order electronic correlations in the systems
with particle-hole excited states using a relativistic hybrid method that
combines configuration interaction and linearized coupled-cluster approaches.
We find the configuration interaction part of the calculation sufficiently
complete for eight electrons while maintaining good quality of the effective
coupled-cluster potential for the core. Excellent agreement with experiment was
demonstrated for a test case of La$^{3+}$. We apply our method for homologue
actinide ions Th$^{4+}$ and U$^{6+}$ which are of experimental interest due to
a puzzle associated with the resonant excitation Stark ionization spectroscopy
(RESIS) method. These ions are also of interest to actinide chemistry and this
is the first precision calculation of their atomic properties.
| arxiv topic:physics.atom-ph physics.optics quant-ph |
arxiv_dataset-92701712.08401 | Steinberg-like characters for finite simple groups
math.RT math.GR
Let $G$ be a finite group and, for a prime $p$, let $S$ be a Sylow
$p$-subgroup of $G$. A character $\chi$ of $G$ is called $\Syl_p$-regular if
the restriction of $\chi$ to $S$ is the character of the regular representation
of $S$. If, in addition, $\chi$ vanishes at all elements of order divisible by
$p$, $\chi$ is said to be Steinberg-like. For every finite simple group $G$ we
determine all primes $p$ for which $G$ admits a Steinberg-like character,
except for alternating groups in characteristic~2. Moreover, we determine all
primes for which $G$ has a projective $FG$-module of dimension $|S|$, where $F$
is an algebraically closed field of characteristic~$p$.
| arxiv topic:math.RT math.GR |
arxiv_dataset-92711712.08501 | Search for physics beyond the standard model in events with
high-momentum Higgs bosons and missing transverse momentum in proton-proton
collisions at 13 TeV
hep-ex
A search for physics beyond the standard model in events with one or more
high-momentum Higgs bosons, H, decaying to pairs of b quarks in association
with missing transverse momentum is presented. The data, corresponding to an
integrated luminosity of 35.9 fb$^{-1}$, were collected with the CMS detector
at the LHC in proton-proton collisions at the center-of-mass energy $\sqrt{s}=$
13 TeV. The analysis utilizes a new b quark tagging technique based on jet
substructure to identify jets from H $\to$ bb. Events are categorized by the
multiplicity of H-tagged jets, jet mass, and the missing transverse momentum.
No significant deviation from standard model expectations is observed. In the
context of supersymmetry (SUSY), limits on the cross sections of pair-produced
gluinos are set, assuming that gluinos decay to quark pairs, H (or Z), and the
lightest SUSY particle, LSP, through an intermediate next-to-lightest SUSY
particle, NLSP. With large mass splitting between the NLSP and LSP, and 100%
NLSP branching fraction to H, the lower limit on the gluino mass is found to be
2010 GeV.
| arxiv topic:hep-ex |
arxiv_dataset-92721712.08601 | Fayet-Iliopoulos terms in supergravity without gauged R-symmetry
hep-th hep-ph
We construct a supergravity-Maxwell theory with a novel embedding of the
Fayet-Iliopoulos D-term, leading to spontaneous supersymmetry breaking. The
gauging of the R-symmetry is not required and a gravitino mass is allowed for a
generic vacuum. When matter couplings are introduced, an uplift through a
positive definite contribution to the scalar potential is obtained. We observe
a notable similarity to the $\overline{D3}$ uplift constructions and we give a
natural description in terms of constrained multiplets.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-92731712.08701 | Interacting superradiance samples: modified intensities and timescales,
and frequency shifts
quant-ph physics.atom-ph
We consider the interaction between distinct superradiance (SR) systems and
use the dressed state formalism to solve the case of two interacting two-atom
SR samples at resonance. We show that the ensuing entanglement modifies the
transition rates and intensities of radiation, as well as introduces a
potentially measurable frequency chirp in the SR cascade, the magnitude of
which being a function of the separation between the samples. For the dominant
SR cascade we find a significant reduction in the duration and an increase of
the intensity of the SR pulse relative to the case of a single two-atom SR
sample.
| arxiv topic:quant-ph physics.atom-ph |
arxiv_dataset-92741712.08801 | Voronoi Glass-Forming Liquids : A Structural Study
cond-mat.stat-mech cond-mat.soft
We introduce a new theoretical model of simple fluid, whose interactions,
defined in terms of the Voronoi cells of the configurations, are local and
many-body. The resulting system is studied both theoretically and numerically.
We show that the fluid, though sharing the global features of other models of
fluids with soft interactions, has several unusual characteristics, which are
investigated and discussed.
| arxiv topic:cond-mat.stat-mech cond-mat.soft |
arxiv_dataset-92751712.08901 | Bott-Chern blow-up formula and bimeromorphic invariance of the
$\partial\bar{\partial}$-Lemma for threefolds
math.AG math.AT math.DG
The purpose of this paper is to study the bimeromorphic invariants of compact
complex manifolds in terms of Bott-Chern cohomology. We prove a blow-up formula
for Bott-Chern cohomology. As an application, we show that for compact complex
threefolds the non-K\"{a}hlerness degrees, introduced by Angella-Tomassini
[Invent. Math. 192, (2013), 71-81], are bimeromorphic invariants. Consequently,
the $\partial\bar{\partial}$-Lemma on threefolds admits the bimeromorphic
invariance.
| arxiv topic:math.AG math.AT math.DG |
arxiv_dataset-92761712.09001 | Kernel Regression with Sparse Metric Learning
cs.LG stat.ML
Kernel regression is a popular non-parametric fitting technique. It aims at
learning a function which estimates the targets for test inputs as precise as
possible. Generally, the function value for a test input is estimated by a
weighted average of the surrounding training examples. The weights are
typically computed by a distance-based kernel function and they strongly depend
on the distances between examples. In this paper, we first review the latest
developments of sparse metric learning and kernel regression. Then a novel
kernel regression method involving sparse metric learning, which is called
kernel regression with sparse metric learning (KR$\_$SML), is proposed. The
sparse kernel regression model is established by enforcing a mixed $(2,1)$-norm
regularization over the metric matrix. It learns a Mahalanobis distance metric
by a gradient descent procedure, which can simultaneously conduct
dimensionality reduction and lead to good prediction results. Our work is the
first to combine kernel regression with sparse metric learning. To verify the
effectiveness of the proposed method, it is evaluated on 19 data sets for
regression. Furthermore, the new method is also applied to solving practical
problems of forecasting short-term traffic flows. In the end, we compare the
proposed method with other three related kernel regression methods on all test
data sets under two criterions. Experimental results show that the proposed
method is much more competitive.
| arxiv topic:cs.LG stat.ML |
arxiv_dataset-92771712.09101 | Gravity from Entanglement and RG Flow in a Top-down Approach
hep-th
The duality between a $d$-dimensional conformal field theory with relevant
deformation and a gravity theory on an asymptotically AdS$_{d+1}$ geometry, has
become a suitable tool in the investigation of the emergence of gravity from
quantum entanglement in field theory. Recently, we have tested the duality
between the mass-deformed ABJM theory and asymptotically AdS$_4$ gravity
theory, which is obtained from the KK reduction of the 11-dimensional
supergravity on the LLM geometry. In this paper, we extend the KK reduction
procedure beyond the linear order and establish non-trivial KK maps between
4-dimensional fields and 11-dimensional fluctuations. We rely on this
gauge/gravity duality to calculate the entanglement entropy by using the
Ryu-Takayanagi holographic formula and the path integral method developed by
Faulkner. We show that the entanglement entropies obtained using these two
methods agree when the asymptotically AdS$_4$ metric satisfies the linearized
Einstein equation with nonvanishing energy-momentum tensor for two scalar
fields. These scalar fields encode the information of the relevant deformation
of the ABJM theory. This confirms that the asymptotic limit of LLM geometry is
the emergent gravity of the quantum entanglement in the mass-deformed ABJM
theory with a small mass parameter. We also comment on the issue of the
relative entropy and the Fisher information in our setup.
| arxiv topic:hep-th |
arxiv_dataset-92781712.09201 | Approximation methods for piecewise deterministic Markov processes and
their costs
math.PR q-fin.CP
In this paper, we analyse piecewise deterministic Markov processes, as
introduced in Davis (1984). Many models in insurance mathematics can be
formulated in terms of the general concept of piecewise deterministic Markov
processes. In this context, one is interested in computing certain quantities
of interest such as the probability of ruin of an insurance company, or the
insurance company's value, defined as the expected discounted future dividend
payments until the time of ruin. Instead of explicitly solving the
integro-(partial) differential equation related to the quantity of interest
considered (an approach which can only be used in few special cases), we adapt
the problem in a manner that allows us to apply deterministic numerical
integration algorithms such as quasi-Monte Carlo rules; this is in contrast to
applying random integration algorithms such as Monte Carlo. To this end, we
reformulate a general cost functional as a fixed point of a particular integral
operator, which allows for iterative approximation of the functional.
Furthermore, we introduce a smoothing technique which is applied to the
integrands involved, in order to use error bounds for deterministic cubature
rules. On the analytical side, we prove a convergence result for our PDMP
approximation, which is of independent interest as it justifies phase-type
approximations on the process level. We illustrate the smoothing technique for
a risk-theoretic example, and provide a comparative study of deterministic and
Monte Carlo integration.
| arxiv topic:math.PR q-fin.CP |
arxiv_dataset-92791712.09301 | Derivations on four dimensional genetic Volterra algebra
math.RA
In this paper, we describe all derivations on four dimensional genetic
Volterra algebras. We show that any local derivation is a derivation of the
algebra. It is a positive answer to a conjecture made by Ganikhodzhaev,
Mukhamedov, Pirnapasov and Qaralleh.
| arxiv topic:math.RA |
arxiv_dataset-92801712.09401 | Robust Minutiae Extractor: Integrating Deep Networks and Fingerprint
Domain Knowledge
cs.CV
We propose a fully automatic minutiae extractor, called MinutiaeNet, based on
deep neural networks with compact feature representation for fast comparison of
minutiae sets. Specifically, first a network, called CoarseNet, estimates the
minutiae score map and minutiae orientation based on convolutional neural
network and fingerprint domain knowledge (enhanced image, orientation field,
and segmentation map). Subsequently, another network, called FineNet, refines
the candidate minutiae locations based on score map. We demonstrate the
effectiveness of using the fingerprint domain knowledge together with the deep
networks. Experimental results on both latent (NIST SD27) and plain (FVC 2004)
public domain fingerprint datasets provide comprehensive empirical support for
the merits of our method. Further, our method finds minutiae sets that are
better in terms of precision and recall in comparison with state-of-the-art on
these two datasets. Given the lack of annotated fingerprint datasets with
minutiae ground truth, the proposed approach to robust minutiae detection will
be useful to train network-based fingerprint matching algorithms as well as for
evaluating fingerprint individuality at scale. MinutiaeNet is implemented in
Tensorflow: https://github.com/luannd/MinutiaeNet
| arxiv topic:cs.CV |
arxiv_dataset-92811712.09501 | Experimental Realization of a Relativistic Harmonic Oscillator
cond-mat.quant-gas quant-ph
We report the experimental study of a harmonic oscillator in the relativistic
regime. The oscillator is composed of Bose-condensed lithium atoms in the third
band of an optical lattice, which have an energy-momentum relation nearly
identical to that of a massive relativistic particle, with an effective mass
reduced below the bare value and a greatly reduced effective speed of light.
Imaging the shape of oscillator trajectories at velocities up to 98% of the
effective speed of light reveals a crossover from sinusoidal to nearly
photon-like propagation. The existence of a maximum velocity causes the
measured period of oscillations to increase with energy; our measurements
reveal beyond-leading-order contributions to this relativistic anharmonicity.
We observe an intrinsic relativistic dephasing of oscillator ensembles, and a
monopole oscillation with exactly the opposite phase of that predicted for
non-relativistic harmonic motion. All observed dynamics are in quantitative
agreement with longstanding but hitherto-untested relativistic predictions.
| arxiv topic:cond-mat.quant-gas quant-ph |
arxiv_dataset-92821712.09601 | Building the Brazilian Academic Genealogy Tree
cs.DL
Along the history, many researchers provided remarkable contributions to
science, not only advancing knowledge but also in terms of mentoring new
scientists. Currently, identifying and studying the formation of researchers
over the years is a challenging task as current repositories of theses and
dissertations are cataloged in a decentralized way through many local digital
libraries. Following our previous work in which we created and analyzed a large
collection of genealogy trees extracted from NDLTD, in this paper we focus our
attention on building such trees for the Brazilian research community. For
this, we use data from the Lattes Platform, an internationally renowned
initiative from CNPq, the Brazilian National Council for Scientific and
Technological Development, for managing information about individual
researchers and research groups in Brazil.
| arxiv topic:cs.DL |
arxiv_dataset-92831712.09701 | Mirror fermions and the strong CP problem: A new axionless solution and
experimental implications
hep-ph hep-ex
A new solution to the strong CP problem with distinct experimental signatures
(long-lived particles) at the LHC is proposed. It is based on the Yukawa
interactions between mirror quarks, Standard Model (SM) quarks and Higgs
singlets. (Mirror quarks and leptons which include non-sterile right-handed
neutrinos whose Majorana masses are proportional to the electroweak scale, form
the basis of the EW-$\nu_R$ model.) The aforementioned Yukawa couplings can in
general be complex and can contribute to $Arg\, Det M$ ($\bar{\theta} =
\theta_{QCD} + Arg\, Det M$) at tree-level. The model contains a
Peccei-Quinn-type global symmetry which allows it to rotate away
$\theta_{QCD}$.The crux of matter in this manuscript is the fact that {\em no
matter how large} the CP-violating phases in the Yukawa couplings might be,
$Arg\, Det M$ can remain small i.e. $\bar{\theta} < 10^{-10}$ for reasonable
values of the Yukawa couplings and, in fact, vanishes when the VEV of the Higgs
singlet (responsible for the Dirac part of the neutrino mass in the seesaw
mechanism) vanishes. The smallness of the contribution to $\bar{\theta}$ is
{\em principally due} to the smallness of the ratio of the two mass scales in
the seesaw mechanism: the Dirac and Majorana mass scales.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-92841712.09801 | Topological magnon bands in the zigzag and stripy phases of
antiferromagnetic honeycomb lattice
cond-mat.mes-hall
We investigated the topological property of magnon bands in the collinear
magnetic orders of zigzag and stripy phases for the antiferromagnetic honeycomb
lattice and identified Berry curvature and symmetry constraints on the magnon
band structure. Different symmetries of both zigzag and stripy phases lead to
different topological properties, in particular, the magnon bands of the stripy
phase being disentangled with a finite Dzyaloshinskii-Moriya (DM) term with
non-zero spin Chern number. This is corroborated by calculating the spin Nernst
effect. Our study establishes the existence of the non-trivial magnon band
topology for all observed collinear antiferromagnetic honeycomb lattice in the
presence of the DM term.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-92851712.09901 | Remarks on multisymplectic reduction
math-ph math.MP
The problem of reduction of multisymplectic manifolds by the action of Lie
groups is stated and discussed, as a previous step to give a fully covariant
scheme of reduction for classical field theories with symmetries.
| arxiv topic:math-ph math.MP |
arxiv_dataset-92861712.10001 | Determinant Monte Carlo for irreducible Feynman diagrams in the strongly
correlated regime
cond-mat.str-el
We develop a numerically exact method for the summation of irreducible
Feynman diagrams for fermionic self-energy in the thermodynamic limit. The
technique, based on the Diagrammatic Determinant Monte Carlo and its recent
extension to connected diagrams, allows us to reach high ($\sim 10$) orders of
the weak-coupling expansion for the self-energy of the two-dimensional Hubbard
model. Access to high orders reveals a non-trivial analytic structure of the
self-energy and enables its controlled reconstruction with arbitrary momentum
resolution in the nonperturbative regime of essentially strong correlations,
which has recently been reached with ultracold atoms in optical lattices.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-92871712.10101 | A variant of the plane wave least squares method for the time-harmonic
Maxwell's equations
math.NA
In this paper we are concerned with the plane wave method for the
discretization of time-harmonic Maxwell's equations in three dimensions. As
pointed out in [6], it is difficult to derive a satisfactory L2 error estimate
of the standard plane wave approximation of the time-harmonic Maxwell's
equations. We propose a variant of the plane wave least squares (PWLS) method
and show that the new plane wave approximations possess the desired L2 error
estimate. Moreover, the numerical results indicate that the new approximations
have sightly smaller L2 errors than the standard plane wave approximations.
More importantly, the results are derived for more general models in layered
media.
| arxiv topic:math.NA |
arxiv_dataset-92881712.10201 | Metascheduling of HPC Jobs in Day-Ahead Electricity Markets
cs.DC
High performance grid computing is a key enabler of large scale collaborative
computational science. With the promise of exascale computing, high performance
grid systems are expected to incur electricity bills that grow super-linearly
over time. In order to achieve cost effectiveness in these systems, it is
essential for the scheduling algorithms to exploit electricity price
variations, both in space and time, that are prevalent in the dynamic
electricity price markets. In this paper, we present a metascheduling algorithm
to optimize the placement of jobs in a compute grid which consumes electricity
from the day-ahead wholesale market. We formulate the scheduling problem as a
Minimum Cost Maximum Flow problem and leverage queue waiting time and
electricity price predictions to accurately estimate the cost of job execution
at a system. Using trace based simulation with real and synthetic workload
traces, and real electricity price data sets, we demonstrate our approach on
two currently operational grids, XSEDE and NorduGrid. Our experimental setup
collectively constitute more than 433K processors spread across 58 compute
systems in 17 geographically distributed locations. Experiments show that our
approach simultaneously optimizes the total electricity cost and the average
response time of the grid, without being unfair to users of the local batch
systems.
| arxiv topic:cs.DC |
arxiv_dataset-92891712.10301 | On regularizing the AdS superstring worldsheet
hep-th
In this short review (to appear as a contribution to an edited volume) we
discuss perturbative and non-perturbative approaches to the quantization of the
Green-Schwarz string in AdS backgrounds with RR-fluxes, where the guiding
thread is the use of genuine field theory methods, the search for a good
regularization scheme associated to them and the generality of the analysis
carried out. We touch upon various computational setups, both analytical and
numerical, and on the role of their outcomes in understanding the detailed
structure of the AdS/CFT correspondence.
| arxiv topic:hep-th |
arxiv_dataset-92901801.00069 | Structural second-order nonlinearity in metamaterials
physics.optics cond-mat.mtrl-sci
Nonlinear processes are at the core of many optical technologies including
lasers, information processing, sensing, and security, and require optimised
materials suitable for nanoscale integration. Here we demonstrate the emergence
of a strong bulk second-order nonlinear response in a composite plasmonic
nanorod material comprised of centrosymmetric materials. The metamaterial
provides equally strong generation of the p-polarized second harmonic light in
response to both s- and p-polarized excitation. We develop an effective-medium
description of the underlying physics, compare its predictions to the
experimental results and analyze the limits of its applicability. We show that
while the effective medium theory adequately describes the nonlinear
polarization, the process of emission of second harmonic light cannot be
described in the same framework. The work provides an understanding of the
emergent nonlinear optical response in composites and opens a doorway to new
nonlinear optical platform designs for integrated nonlinear photonics.
| arxiv topic:physics.optics cond-mat.mtrl-sci |
arxiv_dataset-92911801.00169 | OGLE-2016-BLG-1045: A Test of Cheap Space-Based Microlens Parallaxes
astro-ph.SR astro-ph.IM
Microlensing is a powerful and unique technique to probe isolated objects in
the Galaxy. To study the characteristics of these interesting objects based on
the microlensing method, measurement of the microlens parallax is required to
determine the properties of the lens. Of the various methods to measure
microlens parallax, the most robust way is to make simultaneous ground- and
space-based observations, i.e., by measuring the space-based microlens
parallax. However, space-based campaigns usually require "expensive" resources.
Gould & Yee (2012) proposed an idea called the "cheap space-based microlens
parallax" that can measure the lens-parallax using only $2$ or $3$ space-based
observations of high-magnification events. This cost-effective observation
strategy to measure microlens parallaxes could be used by space-borne
telescopes to build a complete sample for studying isolated objects. This would
enable a direct measurement of the mass function including both extremely
low-mass objects and high-mass stellar remnants. However, to adopt this idea
requires a test to check how it would work in actual situations. Thus, we
present the first practical test of the idea using the high-magnification
microlensing event OGLE-2016-BLG-1045, for which a subset of Spitzer
observations fortuitously duplicate the prescription of Gould & Yee (2012).
From the test, we confirm that the measurement of the lens-parallax adopting
this idea has sufficient accuracy to determine the physical properties of the
isolated lens.
| arxiv topic:astro-ph.SR astro-ph.IM |
arxiv_dataset-92921801.00269 | Interactive Video Object Segmentation in the Wild
cs.CV
In this paper we present our system for human-in-the-loop video object
segmentation. The backbone of our system is a method for one-shot video object
segmentation. While fast, this method requires an accurate pixel-level
segmentation of one (or several) frames as input. As manually annotating such a
segmentation is impractical, we propose a deep interactive image segmentation
method, that can accurately segment objects with only a handful of clicks. On
the GrabCut dataset, our method obtains 90% IOU with just 3.8 clicks on
average, setting the new state of the art. Furthermore, as our method
iteratively refines an initial segmentation, it can effectively correct frames
where the video object segmentation fails, thus allowing users to quickly
obtain high quality results even on challenging sequences. Finally, we
investigate usage patterns and give insights in how many steps users take to
annotate frames, what kind of corrections they provide, etc., thus giving
important insights for further improving interactive video segmentation.
| arxiv topic:cs.CV |
arxiv_dataset-92931801.00369 | Resource Abundance and Life Expectancy
econ.EM
This paper investigates the impacts of major natural resource discoveries
since 1960 on life expectancy in the nations that they were resource poor prior
to the discoveries. Previous literature explains the relation between nations
wealth and life expectancy, but it has been silent about the impacts of
resource discoveries on life expectancy. We attempt to fill this gap in this
study. An important advantage of this study is that as the previous researchers
argued resource discovery could be an exogenous variable. We use longitudinal
data from 1960 to 2014 and we apply three modern empirical methods including
Difference-in-Differences, Event studies, and Synthetic Control approach, to
investigate the main question of the research which is 'how resource
discoveries affect life expectancy?'. The findings show that resource
discoveries in Ecuador, Yemen, Oman, and Equatorial Guinea have positive and
significant impacts on life expectancy, but the effects for the European
countries are mostly negative.
| arxiv topic:econ.EM |
arxiv_dataset-92941801.00469 | The Wind/EPACT proton event catalog (1996-2016)
astro-ph.SR
We present the finalized catalog of solar energetic proton events detected by
Wind/EPACT instrument over the period 1996-2016. Onset times, peak times, peak
proton intensity and onset-to-peak proton fluence are evaluated for the two
available energy channels, at about 25 and 50 MeV. We describe the procedure
utilized to identify the proton events and to relate them to their solar origin
(in terms of flares and coronal mass ejections). The statistical relationships
between the energetic protons and their origin (linear and partial correlation
analysis) are reported and discussed in view of earlier findings. Finally, the
different trends found in the first eight years of solar cycles 23 and 24 are
discussed.
| arxiv topic:astro-ph.SR |
arxiv_dataset-92951801.00569 | Parameter estimation with a class of outer probability measures
stat.ME
We explore the interplay between random and deterministic phenomena using a
representation of uncertainty based on the measure-theoretic concept of outer
measure. The meaning of the analogues of different probabilistic concepts is
investigated and examples of application are given. The novelty of this article
lies mainly in the suitability of the tools introduced for jointly representing
random and deterministic uncertainty. These tools are shown to yield intuitive
results in simple situations and to generalise easily to more complex cases.
Connections with Dempster-Shafer theory, the empirical Bayes methods and
generalised Bayesian inference are also highlighted.
| arxiv topic:stat.ME |
arxiv_dataset-92961801.00669 | E11, Brane Dynamics and Duality Symmetries
hep-th
Following hep-th/0412336 we use the non-linear realisation of the semi-direct
product of E11 and its vector representation to construct brane dynamics. The
brane moves through a spacetime which arises in the non-linear realisation from
the vector representation and it contains the usual embedding coordinates as
well as the world volume fields. The resulting equations of motion are first
order in derivatives and can be thought of as duality relations. Each brane
carries the full E11 symmetry and so the Cremmer-Julia duality symmetries. We
apply this theory to find the dynamics of the IIA and IIB strings, the M2 and
M5 branes, the IIB D3 brane as well as the one and two branes in seven
dimensions.
| arxiv topic:hep-th |
arxiv_dataset-92971801.00769 | Quasiparticles in quantum spin chains with long-range interactions
cond-mat.str-el
We study quasiparticle excitations for quantum spin chains with long-range
interactions using variational matrix product state techniques. It is confirmed
that the local quasiparticle ansatz is able to capture those excitations very
accurately, even when the correlation length becomes very large and in the case
of topological nontrivial excitation such as spinons. It is demonstrated that
the breaking of the Lieb-Robinson bound follows from the appearance of cusps in
the dispersion relation, and evidence is given for a crossover between
different quasiparticles as the long-range interactions are tuned.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-92981801.00869 | On properties of Bourgeois contact structures
math.SG
The Bourgeois construction associates to every contact open book on a
manifold $V$ a contact structure on $V\times T^2$. We study in this article
some of the properties of $V$ that are inherited by $V\times T^2$ and some that
are not.
Giroux has provided recently a suitable framework to work with contact open
books. In the appendix of this article, we quickly review this formalism, and
we work out a few classical examples of contact open books to illustrate how to
use this new language.
| arxiv topic:math.SG |
arxiv_dataset-92991801.00969 | Towards platform-independent verification of the standard mathematical
functions: the square root function
cs.LO
The paper presents (human-oriented) specification and (pen-and-paper)
verification of the square root function. The function implements Newton method
and uses a look-up table for initial approximations. Specification is done in
terms of total correctness assertions with use of precise arithmetic and the
mathematical square root $\sqrt{\dots}$, algorithms are presented in
pseudo-code with explicit distinction between precise and machine arithmetic,
verification is done in Floyd-Hoare style and adjustment (matching) of runs of
algorithms with precise arithmetic and with machine arithmetic. The primary
purpose of the paper is to make explicit properties of the machine arithmetic
that are sufficient to make verification presented in the paper. Computer-aided
implementation and validation of the proofs (using some proof-assistant) is the
topic for further studies.
| arxiv topic:cs.LO |
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