目的通过Meta分析明确中国老年人孤独感的总体流行率及其在人群中的差异。方法检索PubMed、Embase、Web of Science等9个中英文数据库,检索时限自建库至2024年3月。2名研究者独立完成文献筛选、质量评价和信息提取,使用STATA 14.2软件...目的通过Meta分析明确中国老年人孤独感的总体流行率及其在人群中的差异。方法检索PubMed、Embase、Web of Science等9个中英文数据库,检索时限自建库至2024年3月。2名研究者独立完成文献筛选、质量评价和信息提取,使用STATA 14.2软件进行统计分析。结果共纳入58项研究,涉及271094名中国老年人。中国老年人孤独感的流行率为47.2%[95%CI(0.41,0.54)],且在性别、年龄、文化程度、婚姻状况、居住状况、与家庭成员的关系、慢性病、视听力障碍、经济状况、吸烟与否、兴趣爱好、运动锻炼、地域和测量工具等方面差异均有统计学意义(均P<0.05)。结论中国老年人孤独感流行率较高,不同人群间差异显著,未来需进一步探讨其风险和保护因素。展开更多
We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse.The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration,where t...We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse.The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration,where the hohlraum is composed of a single metal liner,a low-Z plastic foam,and a high-Z metallic foam.The implosion dynamics of a hohlraum and a multi-shell target are investigated separately by the one-dimensional code MULTI-IFE.When the peak drive current is 50 MA,simulations suggest that an x-ray pulse with nearly constant radiation temperature(-310 eV)and a duration about 9 ns can be obtained.A small multi-shell target with a radius of 1.35 mm driven by this radiation pulse is able to achieve volumetric ignition with an energy gain(G)about 6.19,where G is the ratio of the yield to the absorbed radiation.Through this research,we better understand the effects of non-uniformities and hydrodynamics instabilities in Z-pinch dynamic hohlraum.展开更多
A new scheme is proposed to improve the electron beam quality of ionization-induced injection by tailoring gas profile in laser wakefield acceleration.Two-dimensional particle-in-cell simulations show that the ionizat...A new scheme is proposed to improve the electron beam quality of ionization-induced injection by tailoring gas profile in laser wakefield acceleration.Two-dimensional particle-in-cell simulations show that the ionization-induced injection mainly occurs in high-density stage and automatically truncates in low-density stage due to the decrease of the wakefield potential difference.The beam loading can be compensated by the elongated beam resulting from the density transition stage.The beam quality can be improved by shorter injection distance and beam loading effect.A quasi-monoenergetic electron beam with a central energy of 258 MeV and an energy spread of 5.1%is obtained under certain laser-plasma conditions.展开更多
The electron injection and acceleration driven by a few-cycle laser with a sharp vacuum-plasma boundary have been investigated through three-dimensional(3D)particle-in-cell simulations.It is found that an isotropic bo...The electron injection and acceleration driven by a few-cycle laser with a sharp vacuum-plasma boundary have been investigated through three-dimensional(3D)particle-in-cell simulations.It is found that an isotropic boundary impact injection(BII)first occurs at the vacuum-plasma boundary,and then carrier-envelope-phase(CEP)shift causes the transverse oscillation of the plasma bubble,resulting in a periodic electron self-injection(SI)in the laser polarization direction.It shows that the electron charge of the BII only accounts for a small part of the total charge,and the CEP can effectively tune the quality of the injected electron beam.The dependences of laser intensity and electron density on the total charge and the ratio of BII charge to the total charge are studied.The results are beneficial to electron acceleration and its applications,such as betatron radiation source.展开更多
文摘目的通过Meta分析明确中国老年人孤独感的总体流行率及其在人群中的差异。方法检索PubMed、Embase、Web of Science等9个中英文数据库,检索时限自建库至2024年3月。2名研究者独立完成文献筛选、质量评价和信息提取,使用STATA 14.2软件进行统计分析。结果共纳入58项研究,涉及271094名中国老年人。中国老年人孤独感的流行率为47.2%[95%CI(0.41,0.54)],且在性别、年龄、文化程度、婚姻状况、居住状况、与家庭成员的关系、慢性病、视听力障碍、经济状况、吸烟与否、兴趣爱好、运动锻炼、地域和测量工具等方面差异均有统计学意义(均P<0.05)。结论中国老年人孤独感流行率较高,不同人群间差异显著,未来需进一步探讨其风险和保护因素。
基金Project supported by the Science Challenge Project (Grant No. TZ2018001)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos. XDA25051200 and XDA25050200)+4 种基金the National Natural Science Foundation of China (Grant Nos. 11705282 and 11775305)Hunan Graduate Scientific Research Innovation Project (Grant No. CX20190001)supported by the spanish “Ministerio de Ciencia Innovación y Universidades”project RTI2018-098801-B-100the Spanish “Ministerio de Economía y Competitividad” Project ENE2014-54960-Rthe EURO fusion Consortium project AWP15-ENR-01/CEA-02
文摘We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse.The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration,where the hohlraum is composed of a single metal liner,a low-Z plastic foam,and a high-Z metallic foam.The implosion dynamics of a hohlraum and a multi-shell target are investigated separately by the one-dimensional code MULTI-IFE.When the peak drive current is 50 MA,simulations suggest that an x-ray pulse with nearly constant radiation temperature(-310 eV)and a duration about 9 ns can be obtained.A small multi-shell target with a radius of 1.35 mm driven by this radiation pulse is able to achieve volumetric ignition with an energy gain(G)about 6.19,where G is the ratio of the yield to the absorbed radiation.Through this research,we better understand the effects of non-uniformities and hydrodynamics instabilities in Z-pinch dynamic hohlraum.
基金supported by the National Natural Science Foundation of China(Grant Nos.12005297,11975308,and 11775305)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA25050200)+2 种基金the Fund of Science Challenge Project(Grant No.TZ2018001)Natural Science Foundation of Hunan Province,China(Grant No.2020JJ5651)the Fund of the State Key Laboratory of Laser Interaction with Matter(Grant No.SKLLIM1908)。
文摘A new scheme is proposed to improve the electron beam quality of ionization-induced injection by tailoring gas profile in laser wakefield acceleration.Two-dimensional particle-in-cell simulations show that the ionization-induced injection mainly occurs in high-density stage and automatically truncates in low-density stage due to the decrease of the wakefield potential difference.The beam loading can be compensated by the elongated beam resulting from the density transition stage.The beam quality can be improved by shorter injection distance and beam loading effect.A quasi-monoenergetic electron beam with a central energy of 258 MeV and an energy spread of 5.1%is obtained under certain laser-plasma conditions.
基金the National Natural Science Foundation of China(Grant Nos.12005297,12175309,12175310,11975308,and 12275356)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA25050200)+3 种基金the Research Project of NUDT(Grant No.ZK21-12)the Key Laboratory Foundation of Laser Plasma of Ministry of Educationthe financial support from the NUDT Young Innovator Awards(Grant No.20190102)Outstanding Young Talents。
文摘The electron injection and acceleration driven by a few-cycle laser with a sharp vacuum-plasma boundary have been investigated through three-dimensional(3D)particle-in-cell simulations.It is found that an isotropic boundary impact injection(BII)first occurs at the vacuum-plasma boundary,and then carrier-envelope-phase(CEP)shift causes the transverse oscillation of the plasma bubble,resulting in a periodic electron self-injection(SI)in the laser polarization direction.It shows that the electron charge of the BII only accounts for a small part of the total charge,and the CEP can effectively tune the quality of the injected electron beam.The dependences of laser intensity and electron density on the total charge and the ratio of BII charge to the total charge are studied.The results are beneficial to electron acceleration and its applications,such as betatron radiation source.
