We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air plasma.Our experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to r...We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air plasma.Our experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to radiation minima that can be quantitatively reconstructed using the linear-dipole-array model.The phase difference between the two colors,determined by the chirp and intensity of the laser,can account for the radiation minima.Furthermore,we observe an asynchronous variation in the generated THz spectrum,which suggests a THz frequency-dependent phase matching between the laser pulse and THz wave.These results highlight the importance of laser chirp during the THz wave generation and demonstrate the possibility of modulating the THz yields and spectrum through chirping the incident laser pulse.This work can provide valuable insights into the mechanism of plasma-based THz wave generation and offer a unique means to control THz emissions.展开更多
In this paper,a local discontinuous Galerkin(LDG)scheme for the time-fractional diffusion equation is proposed and analyzed.The Caputo time-fractional derivative(of orderα,with 0<α<1)is approximated by a finit...In this paper,a local discontinuous Galerkin(LDG)scheme for the time-fractional diffusion equation is proposed and analyzed.The Caputo time-fractional derivative(of orderα,with 0<α<1)is approximated by a finite difference method with an accuracy of order3-α,and the space discretization is based on the LDG method.For the finite difference method,we summarize and supplement some previous work by others,and apply it to the analysis of the convergence and stability of the proposed scheme.The optimal error estimate is obtained in the L2norm,indicating that the scheme has temporal(3-α)th-order accuracy and spatial(k+1)th-order accuracy,where k denotes the highest degree of a piecewise polynomial in discontinuous finite element space.The numerical results are also provided to verify the accuracy and efficiency of the considered scheme.展开更多
为了抑制病毒在网络中快速爆发,快速有效的免疫策略将有助于减少病毒带来的巨大损失,随机免疫、目标免疫、熟人免疫以及多种改进的免疫策略已经被提出.目前基于节点重要性的免疫策略主要关注该节点的度大小,而忽略了与其相邻的不同节点...为了抑制病毒在网络中快速爆发,快速有效的免疫策略将有助于减少病毒带来的巨大损失,随机免疫、目标免疫、熟人免疫以及多种改进的免疫策略已经被提出.目前基于节点重要性的免疫策略主要关注该节点的度大小,而忽略了与其相邻的不同节点的重要性并不相同.基于节点的重要性提出一种改进的免疫策略——基于节点度与聚类系数的病毒免疫算法(Virus immunization based on degree and clustering coefficient of node,IDCC).通过考虑节点的度信息和与其邻居节点间的连接紧密程度计算节点重要性,选择用聚类系数表示连接紧密程度,并计算节点的度大小与聚类系数之和,选择和值较大的节点进行免疫.在人工合成网络和真实的大学邮件网络实现免疫模型并记录感染的节点数目.实验结果表明,使用IDCC免疫策略后,更能抑制病毒传播,且在免疫比例低于20%时,IDCC免疫策略效率最高.展开更多
基金supported by the National Key R&D Program of China(2019YFA0906003)the National Natural Science Foundation of China(32000989)+5 种基金China Postdoctoral Science Foundation Grant(2020M682911 and 2020M670051ZX)Guangdong Special Support Program(2021JC06Y578)the Shenzhen Municipal Government of China(JCYJ20200109120016553,CJGJZD20200617102403009,and RCBS20210706092256081)the Sanming Project of Shenzhen Health and Family Planning Commission(SZSM202011017)Shenzhen Institute of Synthetic Biology Scientific Research Program(ZTXM20214005)the Shenzhen High-level Hospital Construction Fund。
基金supported by the National Natural Science Foundation of China (Grant Nos.12174449,12225511,T2241002,12074250,11991073,12135009,61988102,and 61971397)the National Key Research and Development Program of China (Grant Nos.2019YFA0307703 and 2018YFB2202500)。
文摘We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air plasma.Our experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to radiation minima that can be quantitatively reconstructed using the linear-dipole-array model.The phase difference between the two colors,determined by the chirp and intensity of the laser,can account for the radiation minima.Furthermore,we observe an asynchronous variation in the generated THz spectrum,which suggests a THz frequency-dependent phase matching between the laser pulse and THz wave.These results highlight the importance of laser chirp during the THz wave generation and demonstrate the possibility of modulating the THz yields and spectrum through chirping the incident laser pulse.This work can provide valuable insights into the mechanism of plasma-based THz wave generation and offer a unique means to control THz emissions.
基金supported by the Nursing Research Fund of Weifang Medical University(2022MS001).
文摘目的 旨在建立一个动态在线诺谟图模型并进行验证,以预测老年心力衰竭住院患者的衰弱风险.方法 2021年12月至2022年11月,选取山东省潍坊市1所三级甲等医院心血管内科住院的451例老年心力衰竭患者为研究对象.采用Bartherl指数、工具性日常生活活动能力量表、迷你营养评估简表、匹兹堡睡眠质量指数量表、Morse跌倒评估量表及一般资料量表收集数据,并通过电子病历收集患者的脑钠肽和超声心动图指标.所有数据使用R软件按7:3的比例随机分为训练集(n=319)和验证集(n=132).采用最小绝对收缩和选择算子(Least Absolute Shrinkage and Selection Operator,LASSO)回归方法筛选建模变量,然后使用多变量逻辑回归建立诺谟图.采用受试者工作特征曲线下面积(area under the curve,AUC)、Hosmer-Lemeshow检验、校准图和决策曲线分析(decision curve analysis,DCA)评估模型性能.结果 衰弱的总体发生率为50.6%.在训练集和验证集中,衰弱发生率分别为51.4%和48.5%.LASSO回归结果显示,饮酒、握力、纽约心脏协会心功能分级、多发疾病、心力衰竭住院史、日常生活活动能力、工具性日常生活活动能力、营养状况、睡眠、跌倒风险和左心房舒张末直径为模型纳入变量.诺谟图的AUC为0.920,敏感性为86.8%,特异性为84.4%.H-L检验P值为0.742,DCA表明诺谟图具有良好的临床适用性.结论 在线动态诺谟图适用于预测老年心力衰竭住院患者的衰弱程度,可以帮助医护人员及时诊断衰弱高危人群,以减轻心力衰竭住院负担.
基金supported by the State Key Program of National Natural Science Foundation of China(11931003)the National Natural Science Foundation of China(41974133)。
文摘In this paper,a local discontinuous Galerkin(LDG)scheme for the time-fractional diffusion equation is proposed and analyzed.The Caputo time-fractional derivative(of orderα,with 0<α<1)is approximated by a finite difference method with an accuracy of order3-α,and the space discretization is based on the LDG method.For the finite difference method,we summarize and supplement some previous work by others,and apply it to the analysis of the convergence and stability of the proposed scheme.The optimal error estimate is obtained in the L2norm,indicating that the scheme has temporal(3-α)th-order accuracy and spatial(k+1)th-order accuracy,where k denotes the highest degree of a piecewise polynomial in discontinuous finite element space.The numerical results are also provided to verify the accuracy and efficiency of the considered scheme.
文摘为了抑制病毒在网络中快速爆发,快速有效的免疫策略将有助于减少病毒带来的巨大损失,随机免疫、目标免疫、熟人免疫以及多种改进的免疫策略已经被提出.目前基于节点重要性的免疫策略主要关注该节点的度大小,而忽略了与其相邻的不同节点的重要性并不相同.基于节点的重要性提出一种改进的免疫策略——基于节点度与聚类系数的病毒免疫算法(Virus immunization based on degree and clustering coefficient of node,IDCC).通过考虑节点的度信息和与其邻居节点间的连接紧密程度计算节点重要性,选择用聚类系数表示连接紧密程度,并计算节点的度大小与聚类系数之和,选择和值较大的节点进行免疫.在人工合成网络和真实的大学邮件网络实现免疫模型并记录感染的节点数目.实验结果表明,使用IDCC免疫策略后,更能抑制病毒传播,且在免疫比例低于20%时,IDCC免疫策略效率最高.
