据美国WebMD医学新闻网（2015-11-20）报道,一篇小型的研究指出,年长者走路太慢,大脑中与阿尔茨海默病相关的蛋白质含量就较高。研究人员发现,年长者的淀粉样斑块含量较高与走路速度较慢有关;淀粉样斑块是β淀粉样蛋白密集沉淀所造成的...据美国WebMD医学新闻网（2015-11-20）报道,一篇小型的研究指出,年长者走路太慢,大脑中与阿尔茨海默病相关的蛋白质含量就较高。研究人员发现,年长者的淀粉样斑块含量较高与走路速度较慢有关;淀粉样斑块是β淀粉样蛋白密集沉淀所造成的。法国图卢兹的神经退化性疾病卓越中心科学管理者Natalia del Campo认为,这些结果指出,即使完全没有阿尔茨海默病的征兆,且以正常范围的速度走路,但微小的走路障碍可能预示阿尔茨海默病以及个人的记忆问题。展开更多
The main factors affecting seismic exploration is the propagation velocity of seismic waves in the medium. In the past, during marine seismic data processing, the propagation velocity of sea water was generally taken ...The main factors affecting seismic exploration is the propagation velocity of seismic waves in the medium. In the past, during marine seismic data processing, the propagation velocity of sea water was generally taken as a constant 1500 m/s. However, for deep water exploration, the sound velocity varies with the season, time, location, water depth, ocean currents, and etc.. It also results in a layered velocity distribution, so there is a difference of seismic traveltime, ray paths, and amplitude, which affect the migration imaging results if sea water propagation velocity is still taken as constant for the propagation wavefield. In this paper, we will start from an empirical equation of seismic wave velocity in seawater with changes of temperature, salinity, and depth, consider the variation of their values, build a seawater velocity model, and quantitatively analyze the impact of seawater velocity variation on seismic traveltime, ray paths, and amplitude in the seawater velocity model.展开更多
文摘据美国WebMD医学新闻网（2015-11-20）报道,一篇小型的研究指出,年长者走路太慢,大脑中与阿尔茨海默病相关的蛋白质含量就较高。研究人员发现,年长者的淀粉样斑块含量较高与走路速度较慢有关;淀粉样斑块是β淀粉样蛋白密集沉淀所造成的。法国图卢兹的神经退化性疾病卓越中心科学管理者Natalia del Campo认为,这些结果指出,即使完全没有阿尔茨海默病的征兆,且以正常范围的速度走路,但微小的走路障碍可能预示阿尔茨海默病以及个人的记忆问题。
基金supported by the Major Projects of National Science and Technology Sub-topics(2011ZX05025-001-05)
文摘The main factors affecting seismic exploration is the propagation velocity of seismic waves in the medium. In the past, during marine seismic data processing, the propagation velocity of sea water was generally taken as a constant 1500 m/s. However, for deep water exploration, the sound velocity varies with the season, time, location, water depth, ocean currents, and etc.. It also results in a layered velocity distribution, so there is a difference of seismic traveltime, ray paths, and amplitude, which affect the migration imaging results if sea water propagation velocity is still taken as constant for the propagation wavefield. In this paper, we will start from an empirical equation of seismic wave velocity in seawater with changes of temperature, salinity, and depth, consider the variation of their values, build a seawater velocity model, and quantitatively analyze the impact of seawater velocity variation on seismic traveltime, ray paths, and amplitude in the seawater velocity model.
