3,153 research outputs found
Towards Real-Time Detection and Tracking of Spatio-Temporal Features: Blob-Filaments in Fusion Plasma
A novel algorithm and implementation of real-time identification and tracking
of blob-filaments in fusion reactor data is presented. Similar spatio-temporal
features are important in many other applications, for example, ignition
kernels in combustion and tumor cells in a medical image. This work presents an
approach for extracting these features by dividing the overall task into three
steps: local identification of feature cells, grouping feature cells into
extended feature, and tracking movement of feature through overlapping in
space. Through our extensive work in parallelization, we demonstrate that this
approach can effectively make use of a large number of compute nodes to detect
and track blob-filaments in real time in fusion plasma. On a set of 30GB fusion
simulation data, we observed linear speedup on 1024 processes and completed
blob detection in less than three milliseconds using Edison, a Cray XC30 system
at NERSC.Comment: 14 pages, 40 figure
Dynamics for a two-species competition–diffusion model with two free boundaries
[[abstract]]To understand the spreading and interaction of two-competing species, we study the dynamics for a two-species competition–diffusion model with two free boundaries. Here, the two free boundaries which describe the spreading fronts of two competing species, respectively, may intersect each other. Our result shows there exists a critical value such that the superior competitor always spreads successfully if its territory size is above this constant at some time. Otherwise, the superior competitor can be wiped out by the inferior competitor. Moreover, if the inferior competitor does not spread fast enough such that the superior competitor can catch up with it, the inferior competitor will be wiped out eventually and then a spreading–vanishing trichotomy is established. We also provide some characterization of the spreading–vanishing trichotomy via some parameters of the model. On the other hand, when the superior competitor spreads successfully but with a sufficiently low speed, the inferior competitor can also spread successfully even the superior species is much stronger than the weaker one. It means that the inferior competitor can survive if the superior species cannot catch up with it.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]紙本[[countrycodes]]GB
Simulations of Re-Entry Vehicles by Using DSMC with Chemical-Reaction Module
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76448/1/AIAA-2006-8084-520.pd
Tectonic Implications of Stratigraphy Architecture in Distal Part of Foreland Basin, Southwestern Taiwan
Prevalence of Helicobacter pylori Infection in High-school Students on Lanyu Island, Taiwan: Risk Factor Analysis and Effect on Growth
Background/PurposeThe Yami inhabit Lanyu Island and are the smallest and most primitive aboriginal tribe in Taiwan. Lanyu Island is a closed environment and little information is available on the prevalence of Helicobacter pylori infection there. This study aimed to establish the prevalence of H. pylori infection in high-school students on Lanyu Island and its risk factors and effect on growth.MethodsA cross-sectional population-based study was conducted among high-school students to determine the prevalence of H. pylori infection by using the 13C urea breath test. A questionnaire was administered to the recruited population. Relevant personal and socioeconomic data for risk factors of infection were collected. Body height and weight of the recruited adolescents in relation to H. pylori infection were analyzed.ResultsA total of 106 high-school students (55 boys and 51 girls), with a mean age of 14.3 ± 1.4 years were enrolled. The overall prevalence of H. pylori infection was 54.7%. Those residing in Dongcing village had the highest rate of H. pylori infection (73.3%). There was no difference in the prevalence of H. pylori infection according to sex, ethnicity, socioeconomic level or parental education. Sixty-two students (54.8%) were completely asymptomatic and the others had at least one gastrointestinal symptom. H. pylori infection was asymptomatic in 56.8% and symptomatic in 53.2% of students. There was no significant difference between infected and uninfected children with regard to body weight, height and body mass index.ConclusionThe prevalence of H. pylori infection is high among high-school students on Lanyu Island. There is no evidence that infection is related to growth failure
Ectopic cervical thymoma in a patient with Myasthenia gravis
Ectopic cervical thymoma is rare and is often misdiagnosed as a thyroid tumor or other malignancy. Ectopic thymic tissue can be found along the entire thymic descent path during embryogenesis. However, a thymoma arising from such ectopic thymic tissue is extremely rare. Herein we report a patient with ectopic cervical thymoma and myasthenia gravis (MG) and discuss the management
Unraveling Diffusion in Fusion Plasma: A Case Study of In Situ Processing and Particle Sorting
This work starts an in situ processing capability to study a certain
diffusion process in magnetic confinement fusion. This diffusion process
involves plasma particles that are likely to escape confinement. Such particles
carry a significant amount of energy from the burning plasma inside the tokamak
to the diverter and damaging the diverter plate. This study requires in situ
processing because of the fast changing nature of the particle diffusion
process. However, the in situ processing approach is challenging because the
amount of data to be retained for the diffusion calculations increases over
time, unlike in other in situ processing cases where the amount of data to be
processed is constant over time. Here we report our preliminary efforts to
control the memory usage while ensuring the necessary analysis tasks are
completed in a timely manner. Compared with an earlier naive attempt to
directly computing the same diffusion displacements in the simulation code,
this in situ version reduces the memory usage from particle information by
nearly 60% and computation time by about 20%
The color gradients of spiral disks in the Sloan Digital Sky Survey
We investigate the radial color gradients of galactic disks using a sample of
about 20,000 face-on spiral galaxies selected from the fourth data release of
the Sloan Digital Sky Survey (SDSS-DR4). We combine galaxies with similar
concentration, size and luminosity to construct composite galaxies, and then
measure their color profiles by stacking the azimuthally averaged radial color
profiles of all the member galaxies. Except for the smallest galaxies (R_{50}<3
kpc), almost all galaxies show negative disk color gradients with mean g-r
gradient G_{gr}=-0.006 mag kpc^{-1} and r-z gradient G_{rz}=-0.018 mag
kpc^{-1}. The disk color gradients are independent of the morphological types
of galaxies and strongly dependent on the disk surface brightness \mu_{d}, with
lower surface brightness galactic disks having steeper color gradients. We
quantify the intrinsic correlation between color gradients and surface
brightness as G_{gr}=-0.011\mu_{d}+0.233 and G_{rz}=-0.015\mu_{d}+0.324. These
quantified correlations provide tight observational constraints on the
formation and evolution models of spiral galaxies.Comment: 20 pages, 5 figures, Accepted for publication in RAA (Research in
Astronomy and Astrophysics
Subsurface Structure, Physical Properties, and Fault Zone Characteristics in the Scientific Drill Holes of Taiwan Chelungpu-Fault Drilling Project
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