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Your search keyword '"Zhou, Xinghua"' showing total 434 results
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434 results on '"Zhou, Xinghua"'

1. Outbreak.info genomic reports: scalable and dynamic surveillance of SARS-CoV-2 variants and mutations.

Author

Latif, Alaa, Mullen, Julia, Alkuzweny, Manar, Hufbauer, Emory, Tsueng, Ginger, Haag, Emily, Zeller, Mark, Aceves, Christine, Zaiets, Karina, Cano, Marco, Zhou, Xinghua, Qian, Zhongchao, Sattler, Rachel, Matteson, Nathaniel, Levy, Joshua, Lee, Raphael, Freitas, Lucas, Maurer-Stroh, Sebastian, Wu, Chunlei, Su, Andrew, Andersen, Kristian, Hughes, Laura, Suchard, Marc, and Gangavarapu, Karthik

Subjects
Humans, SARS-CoV-2, COVID-19, Genomics, Disease Outbreaks, Mutation
Abstract

In response to the emergence of SARS-CoV-2 variants of concern, the global scientific community, through unprecedented effort, has sequenced and shared over 11 million genomes through GISAID, as of May 2022. This extraordinarily high sampling rate provides a unique opportunity to track the evolution of the virus in near real-time. Here, we present outbreak.info , a platform that currently tracks over 40 million combinations of Pango lineages and individual mutations, across over 7,000 locations, to provide insights for researchers, public health officials and the general public. We describe the interpretable visualizations available in our web application, the pipelines that enable the scalable ingestion of heterogeneous sources of SARS-CoV-2 variant data and the server infrastructure that enables widespread data dissemination via a high-performance API that can be accessed using an R package. We show how outbreak.info can be used for genomic surveillance and as a hypothesis-generation tool to understand the ongoing pandemic at varying geographic and temporal scales.

Published
2023

8. Outbreak.info genomic reports: scalable and dynamic surveillance of SARS-CoV-2 variants and mutations

Author

Gangavarapu, Karthik, Latif, Alaa Abdel, Mullen, Julia L., Alkuzweny, Manar, Hufbauer, Emory, Tsueng, Ginger, Haag, Emily, Zeller, Mark, Aceves, Christine M., Zaiets, Karina, Cano, Marco, Zhou, Xinghua, Qian, Zhongchao, Sattler, Rachel, Matteson, Nathaniel L., Levy, Joshua I., Lee, Raphael T. C., Freitas, Lucas, Maurer-Stroh, Sebastian, Suchard, Marc A., Wu, Chunlei, Su, Andrew I., Andersen, Kristian G., and Hughes, Laura D.

Published
2023
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21. Explicit solutions of quadratic FBSDEs arising from quadratic term structure models

Author

Hyndman, Cody and Zhou, Xinghua

Subjects
Quantitative Finance - Mathematical Finance, Mathematics - Probability, 60G35, 60H20, 60H30, 91B28, 91B70
Abstract

We provide explicit solutions of certain forward-backward stochastic differential equations (FBSDEs) with quadratic growth. These particular FBSDEs are associated with quadratic term structure models of interest rates and characterize the zero-coupon bond price. The results of this paper are naturally related to similar results on affine term structure models of Hyndman (Math. Financ. Econ. 2(2):107-128, 2009) due to the relationship between quadratic functionals of Gaussian processes and linear functionals of affine processes. Similar to the affine case a sufficient condition for the explicit solutions to hold is the solvability in a fixed interval of Riccati-type ordinary differential equations. However, in contrast to the affine case, these Riccati equations are easily associated with those occurring in linear-quadratic control problems. We also consider quadratic models for a risky asset price and characterize the futures price and forward price of the asset in terms of similar FBSDEs. An example is considered, using an approach based on stochastic flows that is related to the FBSDE approach, to further emphasize the parallels between the affine and quadratic models. An appendix discusses solvability and explicit solutions of the Riccati equations., Comment: 23 pages, minor revisions (typos, restatement of main results to rely on additional lemmas)

Published
2014
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47. Correlating severe land subsidence and confined brine aquifer compaction in the Yellow River Delta, China, with Sentinel-1A/1B satellite images.

Author

Zhang, Yi, Luo, Yafei, Huang, Haijun, Liu, Yanxia, Bi, Haibo, Zhang, Xinyuan, Zhang, Zehua, Wang, Kuifeng, Bai, Zechao, and Zhou, Xinghua

Subjects
LAND subsidence, REMOTE-sensing images, SOIL mechanics, SALT, SYNTHETIC aperture radar, AQUIFERS
Abstract

In recent years, noticeable subsidence depressions have occurred along the coastal zone of the Yellow River Delta. In some coastal areas, the average annual subsidence varies from tens of millimeters to hundreds of millimeters. Although some studies have discovered a significant land subsidence funnel in the coastal zone of the Yellow River Delta, it has rarely been reported in recent years. Using Sentinel-1A/1B images from the last five years and permanent scatterers interferometric synthetic aperture radar technology, we found a typical subsidence bowl in the northeastern part of the delta, with a cumulative settlement of nearly 1 m over five years. In addition, we used the approach of soil mechanics to simulate the settlement of confined brine layers with different thicknesses under drainage conditions. We found that the 15 m thick confined aquifer can produce 1 m of settlement for every 15% decrease in water content. The simulation results explain the large settlement of the brine industrial area. This study can provide guidance for brine mining in the future. If we continue to overexploit underground brine, there will be more severe land subsidence in the delta in the future. [ABSTRACT FROM AUTHOR]

Published
2023
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48. An Inversion Method for Geoacoustic Parameters in Shallow Water Based on Bottom Reflection Signals.

Author

Wang, Zhuo, Ma, Yuxuan, Kan, Guangming, Liu, Baohua, Zhou, Xinghua, and Zhang, Xiaobo

Subjects
WATER depth, INVERSION (Geophysics), SPEED of sound, REFLECTANCE, ACOUSTIC field, ACOUSTIC emission testing, GENETIC algorithms, GRAZING
Abstract

The inversion method based on the reflection loss-grazing angle curve is an effective tool to obtain local underwater acoustic parameters. Because geoacoustic parameters vary in sensitivity to grazing angle, it is difficult to get accurate results in geoacoustic parameter inversion based on small-grazing-angle data in shallow water. In addition, the normal-mode model commonly used in geoacoustic parameter inversion fails to meet the needs of accurate local sound field simulation as the influence of the secant integral is ignored. To solve these problems, an acoustic data acquisition scheme was rationally designed based on a sparker source, a fixed vertical array, and ship drifting with the swell, which could balance the trade-off among signal transmission efficiency and signal stability, and the actual local acoustic data at low-to-mid frequencies were acquired at wide grazing angles in the South Yellow Sea area. Furthermore, the bottom reflection coefficients (bottom reflection losses) corresponding to different grazing angles were calculated based on the wavenumber integration method. The local seafloor sediment parameters were then estimated using the genetic algorithm and the bottom reflection loss curve with wide grazing angles, obtaining more accurate local acoustic information. The seafloor acoustic velocity inverted is c p = 1659   m / s and the sound attenuation is α p = 0.656   dB / λ in the South Yellow Sea. Relevant experimental results indicate that the method described in this study is feasible for local inversion of geoacoustic parameters for seafloor sediments. Compared with conventional large-scale inversion methods, in areas where there are significant changes in the seabed sediment level, this method can obtain more accurate local acoustic features within small-scale areas. [ABSTRACT FROM AUTHOR]

Published
2023
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