2,297 research outputs found
Scaling and memory in the return intervals of energy dissipation rate in three-dimensional fully developed turbulence
We study the statistical properties of return intervals between
successive energy dissipation rates above a certain threshold in
three-dimensional fully developed turbulence. We find that the distribution
function scales with the mean return interval as
except for , where the scaling function
has two power-law regimes. The return intervals are short-term and long-term
correlated and possess multifractal nature. The Hurst index of the return
intervals decays exponentially against , predicting that rare extreme
events with are also long-term correlated with the Hurst index
.Comment: 5 pages, 5 figure
Multifractal detrending moving average cross-correlation analysis
There are a number of situations in which several signals are simultaneously
recorded in complex systems, which exhibit long-term power-law
cross-correlations. The multifractal detrended cross-correlation analysis
(MF-DCCA) approaches can be used to quantify such cross-correlations, such as
the MF-DCCA based on detrended fluctuation analysis (MF-X-DFA) method. We
develop in this work a class of MF-DCCA algorithms based on the detrending
moving average analysis, called MF-X-DMA. The performances of the MF-X-DMA
algorithms are compared with the MF-X-DFA method by extensive numerical
experiments on pairs of time series generated from bivariate fractional
Brownian motions, two-component autoregressive fractionally integrated moving
average processes and binomial measures, which have theoretical expressions of
the multifractal nature. In all cases, the scaling exponents extracted
from the MF-X-DMA and MF-X-DFA algorithms are very close to the theoretical
values. For bivariate fractional Brownian motions, the scaling exponent of the
cross-correlation is independent of the cross-correlation coefficient between
two time series and the MF-X-DFA and centered MF-X-DMA algorithms have
comparative performance, which outperform the forward and backward MF-X-DMA
algorithms. We apply these algorithms to the return time series of two stock
market indexes and to their volatilities. For the returns, the centered
MF-X-DMA algorithm gives the best estimates of since its
is closest to 0.5 as expected, and the MF-X-DFA algorithm has the
second best performance. For the volatilities, the forward and backward
MF-X-DMA algorithms give similar results, while the centered MF-X-DMA and the
MF-X-DFA algorithms fails to extract rational multifractal nature.Comment: 15 pages, 4 figures, 2 matlab codes for MF-X-DMA and MF-X-DF
Statistical significance of rich-club phenomena in complex networks
We propose that the rich-club phenomena in complex networks should be defined
in the spirit of bootstrapping, in which a null model is adopted to assess the
statistical significance of the rich-club detected. Our method can be served as
a definition of rich-club phenomenon and is applied to analyzing three real
networks and three model networks. The results improve significantly compared
with previously reported results. We report a dilemma with an exceptional
example, showing that there does not exist an omnipotent definition for the
rich-club phenomenon.Comment: 3 Revtex pages + 5 figure
FA-GAN: fused attentive generative adversarial networks for MRI image super-resolution
High-resolution magnetic resonance images can provide fine-grained anatomical information, but acquiring such data requires a long scanning time. In this paper, a framework called the Fused Attentive Generative Adversarial Networks(FA-GAN) is proposed to generate the super- resolution MR image from low-resolution magnetic resonance images, which can reduce the scanning time effectively but with high resolution MR images. In the framework of the FA-GAN, the local fusion feature block, consisting of different three-pass networks by using different convolution kernels, is proposed to extract image features at different scales. And the global feature fusion module, including the channel attention module, the self-attention module, and the fusion operation,is designed to enhance the important features of the MR image. Moreover, the spectral normalization process is introduced to make the discriminator network stable. 40 sets of 3D magnetic resonance images (each set of images contains 256 slices) are used to train the network, and 10 sets of images are used to test the proposed method. The experimental results show that the PSNR and SSIM values of the super-resolution magnetic resonance image generated by the proposed FA-GAN method are higher than the state-of-the-art reconstruction methods
Superconductivity up to 30 K in the vicinity of quantum critical point in BaFe(AsP)
We report bulk superconductivity induced by an isovalent doping of phosphorus
in BaFe(AsP). The P-for-As substitution results in
shrinkage of lattice, especially for the FeAs block layers. The resistivity
anomaly associated with the spin-density-wave (SDW) transition in the undoped
compound is gradually suppressed by the P doping. Superconductivity with the
maximum of 30 K emerges at =0.32, coinciding with a magnetic quantum
critical point (QCP) which is evidenced by the disappearance of SDW order and
the linear temperature-dependent resistivity in the normal state. The
values were found to decrease with further P doping, and no superconductivity
was observed down to 2 K for 0.77. The appearance of superconductivity
in the vicinity of QCP hints to the superconductivity mechanism in iron-based
arsenides.Comment: 9 pages, 4 figures; more data; to appear in Journal of Physics:
Condensed Matte
Age-Sex differences in the global burden of lower respiinfections and risk factors, 1990-2019 : results from the Global Burden of Disease Study 2019
Background The global burden of lower respiratory infections (LRIs) and corresponding risk factors in children older than 5 years and adults has not been studied as comprehensively as it has been in children younger than 5 years. We assessed the burden and trends of LRIs and risk factors across a groups by sex, for 204 countries and territories.Methods In this analysis of data for the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we used dinician-diagnosed pneumonia or bronchiolitis as our case definition for LRIs. We included International Classification of Diseases 9th edition codes 079.6, 466-469, 470.0, 480-482.8, 483.0-483.9, 484.1-484.2, 484.6-484.7, and 487-489 and International Classification of Diseases 10th edition codes A48.1, A70, B97.4 B97.6, 109-115.8, J16 J16.9, J20-121.9, J91.0, P23.0 P23.4, and U04 U04.9. We used the Cause of Death Ensemble modelling strategy to analyse 23109 site-years of vital r *stration data, 825 site-years of sample vital registration data, 1766 site-years of verbal autopsy data, and 681 site-years of mortality surveillance data. We used DisMod-MR 2.1, a Bayesian metaregression tool, to analyse age sex-specific incidence and prevalence data identified via systematic reviews of the literature, population-based survey data, and daims and inpatient data. Additio y, we estimated age sex-specific LRI mortality that is attributable to the independent effects of 14 risk factors.Findings Globally, in 2019, we estimated that there were 257 million (95% uncertainty interval [UI] 240-275) LRI incident episodes in males and 232 million (217-248) in females. In the same year, LRIs accounted for 1.30 million (95% UI 1.18-1.42) male deaths and 1.20 million (1.07-1.33) female deaths. Age-standardised incidence and mortality rates were 1.17 times (95% UI 1.16-1.18) and 1.31 times (95% UI 1.23-1.41) greater in males than in fe es in 2019. Between 1990 and 2019, LRI incidence and mortality rates declined at different rates across age groups and an increase in LRI episodes and deaths was estimated among all adult age groups, with males aged 70 years and older having the highest increase in LRI episodes (126.0% [95% UI 121.4-131.1]) and deaths (100.0% [83.4-115.9]). During the same period, LRI episodes and deaths in children younger than 15 years were estimated to have decreased, and the greatest dedine was observed for LRI deaths in males younger than 5 years (-70.7% [-77.2 to 61.8]). The leading risk factors for LRI mortality varied across age groups and sex. More than half of global LRI deaths in children younger than 5 years were attributable to child wasting (population attributable fraction [PAF] 53.0% [95% UI 37.7-61.8] in males and 56.4% [40.7-65.1] in females), and more than a quarter of LRI deaths among those aged 5-14 years were attributable to household air pollution (PAF 26.0% [95% UI 16.6-35.5] for males and PAF 25.8% [16.3-35.4] for females). PAFs of male LRI deaths attributed to smoking were 20.4% (95% UI 15.4-25.2) in those aged 15-49 years, 305% (24.1-36. 9) in those aged 50-69 years, and 21.9% (16. 8-27. 3) in those aged 70 years and older. PAFs of female LRI deaths attributed to household air pollution were 21.1% (95% UI 14.5-27.9) in those aged 15-49 years and 18 " 2% (12.5-24.5) in those aged 50-69 years. For females aged 70 years and older, the leading risk factor, ambient particulate matter, was responsible for 11-7% (95% UI 8.2-15.8) of LRI deaths.Interpretation The patterns and progress in reducing the burden of LRIs and key risk factors for mortality varied across age groups and sexes. The progress seen in children you - than 5 years was dearly a result of targeted interventions, such as vaccination and reduction of exposure to risk factors. Similar interventions for other age groups could contribute to the achievement of multiple Sustainable Development Goals targets, induding promoting wellbeing at all ages and reducing health inequalities. Interventions, including addressing risk factors such as child wasting, smoking, ambient particulate matter pollution, and household air pollution, would prevent deaths and reduce health disparities.Copyright 2022 The Author(s). Published by Elsevier Ltd.Peer reviewe
EGenBio : a data management system for evolutionary genomics and biodiversity
From The Third Annual Conference of the MidSouth Computational Biology and Bioinformatics Society Baton Rouge, Louisiana. 2–4 March, 2006.© 2006 Nahum et al; licensee BioMed Central Ltd.
This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.EGenBio is a system for manipulation and filtering of large numbers of sequences,
integrating curated sequence alignments and phylogenetic trees, managing evolutionary analyses, and visualizing their output. EGenBio is organized into three conceptual divisions, Evolution, Genomics, and Biodiversity. The Genomics division includes tools for selecting pre-aligned sequences
from different genes and species, and for modifying and filtering these alignments for further
analysis. Species searches are handled through queries that can be modified based on a tree-based navigation system and saved. The Biodiversity division contains tools for analyzing individual sequences or sequence alignments, whereas the Evolution division contains tools involving phylogenetic trees. Alignments are annotated with analytical results and modification history using
our PRAED format. A miscellaneous Tools section and Help framework are also available. EGenBio was developed around our comparative genomic research and a prototype database of mtDNA genomes. It utilizes MySQL-relational databases and dynamic page generation, and calls numerous custom programs.This work was partly funded by the National Institutes of Health (R22/R33
Innovation and Development grant to David Pollock), the National Science
Foundation (CBM2/EPSCOR), and the State of Louisiana (Biological Computation and Visualization Center, Governor's iotechnology Initiative, and startup funds to David Pollock)
Superconductivity in LaFeAsPO: effect of chemical pressures and bond covalency
We report the realization of superconductivity by an isovalent doping with
phosphorus in LaFeAsO. X-ray diffraction shows that, with the partial
substitution of P for As, the FeAs layers are squeezed while the
LaO layers are stretched along the c-axis. Electrical resistance and
magnetization measurements show emergence of bulk superconductivity at 10
K for the optimally-doped LaFeAsPO (). The upper
critical fields at zero temperature is estimated to be 27 T, much higher than
that of the LaFePO superconductor. The occurrence of superconductivity is
discussed in terms of chemical pressures and bond covalency.Comment: 5 pages, 6 figures, more data presente
Improved Detection of Enterotoxigenic Escherichia coli among Patients with Travelers' Diarrhea, by Use of the Polymerase Chain Reaction Technique
This study sought to determine whether a specific polymerase chain reaction (PCR) for enterotoxigenic Escherichia coli (ETEC) toxins after chaotropic extraction of DNA from stool would increase the detection of ETEC over that of conventional oligonucleotide probe hybridization of 5 E. coli colonies per stool sample (a standard method). By DNA hybridization, 29 (21%) of 140 patients were positive for ETEC, and 59 (42%) of 140 were positive for ETEC when PCR was used. Sensitivity of the PCR assay was confirmed through spiked stool experiments to be ∼100-1000 ETEC colonies per sample. Specificity of the assay was determined by showing an absence of ETEC by the PCR technique in a subgroup of 48 subjects and by confirming the presence of ETEC DNA of positive samples by dot blot procedure. PCR technique detected significantly more ETEC infections in these subjects than did the hybridization method (P < .0001
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