2,041 research outputs found
Large deviations for local times and intersection local times of fractional Brownian motions and Riemann-Liouville processes
In this paper we prove exact forms of large deviations for local times and
intersection local times of fractional Brownian motions and Riemann-Liouville
processes. We also show that a fractional Brownian motion and the related
Riemann-Liouville process behave like constant multiples of each other with
regard to large deviations for their local and intersection local times. As a
consequence of our large deviation estimates, we derive laws of iterated
logarithm for the corresponding local times. The key points of our methods: (1)
logarithmic superadditivity of a normalized sequence of moments of
exponentially randomized local time of a fractional Brownian motion; (2)
logarithmic subadditivity of a normalized sequence of moments of exponentially
randomized intersection local time of Riemann-Liouville processes; (3)
comparison of local and intersection local times based on embedding of a part
of a fractional Brownian motion into the reproducing kernel Hilbert space of
the Riemann-Liouville process.Comment: To appear in the Annals of Probabilit
Oxidized Forms of Antiaromatic Oligomers of Biphenylene
Rsumen de la comunicaciónThe importance of antiaromatic molecules in Chemistry and more recently in material science is rising. In the particular case of applications in electronics, the antiaromatic skeleton offers the favorable situation of high energy (i.e., destabilized) occupied molecular orbitals allowing to ease oxidation, doping or electron transfer to form conductive and photo-active substrates.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Critical -Free Graphs
Given two graphs and , a graph is -free if it contains
no induced subgraph isomorphic to nor . Let be the path on
vertices. A dart is the graph obtained from a diamond by adding a new vertex
and making it adjacent to exactly one vertex with degree 3 in the diamond.
In this paper, we show that there are finitely many -vertex-critical
-free graphs for To prove these results, we use induction
on and perform a careful structural analysis via Strong Perfect Graph
Theorem combined with the pigeonhole principle based on the properties of
vertex-critical graphs. Moreover, for we characterize all
-vertex-critical -free graphs using a computer generation
algorithm. Our results imply the existence of a polynomial-time certifying
algorithm to decide the -colorability of -free graphs for where the certificate is either a -coloring or a -vertex-critical
induced subgraph.Comment: arXiv admin note: text overlap with arXiv:2211.0417
A GPU-accelerated package for simulation of flow in nanoporous source rocks with many-body dissipative particle dynamics
Mesoscopic simulations of hydrocarbon flow in source shales are challenging,
in part due to the heterogeneous shale pores with sizes ranging from a few
nanometers to a few micrometers. Additionally, the sub-continuum fluid-fluid
and fluid-solid interactions in nano- to micro-scale shale pores, which are
physically and chemically sophisticated, must be captured. To address those
challenges, we present a GPU-accelerated package for simulation of flow in
nano- to micro-pore networks with a many-body dissipative particle dynamics
(mDPD) mesoscale model. Based on a fully distributed parallel paradigm, the
code offloads all intensive workloads on GPUs. Other advancements, such as
smart particle packing and no-slip boundary condition in complex pore
geometries, are also implemented for the construction and the simulation of the
realistic shale pores from 3D nanometer-resolution stack images. Our code is
validated for accuracy and compared against the CPU counterpart for speedup. In
our benchmark tests, the code delivers nearly perfect strong scaling and weak
scaling (with up to 512 million particles) on up to 512 K20X GPUs on Oak Ridge
National Laboratory's (ORNL) Titan supercomputer. Moreover, a single-GPU
benchmark on ORNL's SummitDev and IBM's AC922 suggests that the host-to-device
NVLink can boost performance over PCIe by a remarkable 40\%. Lastly, we
demonstrate, through a flow simulation in realistic shale pores, that the CPU
counterpart requires 840 Power9 cores to rival the performance delivered by our
package with four V100 GPUs on ORNL's Summit architecture. This simulation
package enables quick-turnaround and high-throughput mesoscopic numerical
simulations for investigating complex flow phenomena in nano- to micro-porous
rocks with realistic pore geometries
Dilepton Yield in Heavy-Ion Collisions with Bose Enhancement of Decay Width
The excess of low invariant mass dilepton yield in heavy ion collisions
arising from reduction in the rho meson mass at finite temperatures is
partially suppressed because of the effect on the width of the rho meson
induced by Bose enhancement, essentially due to emission of pions in a medium
of the pion gas in the central rapidity region. The sensitivity of the effect
on the initial temperature of the hadronic phase is also examined.Comment: Plain latex fil
The space group classification of topological band insulators
Topological band insulators (TBIs) are bulk insulating materials which
feature topologically protected metallic states on their boundary. The existing
classification departs from time-reversal symmetry, but the role of the crystal
lattice symmetries in the physics of these topological states remained elusive.
Here we provide the classification of TBIs protected not only by time-reversal,
but also by crystalline symmetries. We find three broad classes of topological
states: (a) Gamma-states robust against general time-reversal invariant
perturbations; (b) Translationally-active states protected from elastic
scattering, but susceptible to topological crystalline disorder; (c) Valley
topological insulators sensitive to the effects of non-topological and
crystalline disorder. These three classes give rise to 18 different
two-dimensional, and, at least 70 three-dimensional TBIs, opening up a route
for the systematic search for new types of TBIs.Comment: Accepted in Nature Physic
An associative information visualizer
IEEE Symposium on Information Visualization, INFOVIS 2004, p. r8
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