期刊文献+
共找到425篇文章
< 1 2 22 >
每页显示 20 50 100
Neurogenesis dynamics in the olfactory bulb:deciphering circuitry organization, function, and adaptive plasticity
1
作者 Moawiah M.Naffaa 《Neural Regeneration Research》 SCIE CAS 2025年第6期1565-1581,共17页
Adult neurogenesis persists after birth in the subventricular zone, with new neurons migrating to the granule cell layer and glomerular layers of the olfactory bulb, where they integrate into existing circuitry as inh... Adult neurogenesis persists after birth in the subventricular zone, with new neurons migrating to the granule cell layer and glomerular layers of the olfactory bulb, where they integrate into existing circuitry as inhibitory interneurons. The generation of these new neurons in the olfactory bulb supports both structural and functional plasticity, aiding in circuit remodeling triggered by memory and learning processes. However, the presence of these neurons, coupled with the cellular diversity within the olfactory bulb, presents an ongoing challenge in understanding its network organization and function. Moreover,the continuous integration of new neurons in the olfactory bulb plays a pivotal role in regulating olfactory information processing. This adaptive process responds to changes in epithelial composition and contributes to the formation of olfactory memories by modulating cellular connectivity within the olfactory bulb and interacting intricately with higher-order brain regions. The role of adult neurogenesis in olfactory bulb functions remains a topic of debate. Nevertheless, the functionality of the olfactory bulb is intricately linked to the organization of granule cells around mitral and tufted cells. This organizational pattern significantly impacts output, network behavior, and synaptic plasticity, which are crucial for olfactory perception and memory. Additionally, this organization is further shaped by axon terminals originating from cortical and subcortical regions. Despite the crucial role of olfactory bulb in brain functions and behaviors related to olfaction, these complex and highly interconnected processes have not been comprehensively studied as a whole. Therefore, this manuscript aims to discuss our current understanding and explore how neural plasticity and olfactory neurogenesis contribute to enhancing the adaptability of the olfactory system. These mechanisms are thought to support olfactory learning and memory, potentially through increased complexity and restructuring of neural network structures, as well as the addition of new granule granule cells that aid in olfactory adaptation. Additionally, the manuscript underscores the importance of employing precise methodologies to elucidate the specific roles of adult neurogenesis amidst conflicting data and varying experimental paradigms. Understanding these processes is essential for gaining insights into the complexities of olfactory function and behavior. 展开更多
关键词 network adaptability NEUROGENESIS neuronal communication olfactory bulb olfactory learning olfactory memory synaptic plasticity
下载PDF
Climate &Sustainability Implications of Land Use Alterations in an Urbanizing Region: Raleigh-Durham, North Carolina
2
作者 E. M. B. Doran J. S. Golden 《Journal of Environmental Protection》 2016年第7期1072-1088,共18页
Urban climate is the most immediate manifestation of the warming global climate for the majority of people on earth. Nearly half of those people live in small to medium sized cities, an understudied scale in urban cli... Urban climate is the most immediate manifestation of the warming global climate for the majority of people on earth. Nearly half of those people live in small to medium sized cities, an understudied scale in urban climate research. Widespread characterization would be useful to decision makers in planning and design for land use decisions. Using a multi-method approach, the mesoscale UHI in the study region is characterized and the secular trend over the last sixty years evaluated. Under isolated ideal conditions the findings indicate a UHI of 5.3℃ ± 0.97℃ to be present in the study area, the magnitude of which is growing over time. 展开更多
关键词 Land Use Urban Heat Island MESOSCALE Urban Climate PIEDMONT North Carolina
下载PDF
治疗相关神经内分泌前列腺癌机制研究与靶向治疗新进展
3
作者 黄教悌 胡菁 韩博 《北京大学学报(医学版)》 CAS CSCD 北大核心 2024年第4期557-561,共5页
前列腺癌是男性泌尿生殖系统最常见的恶性肿瘤,我国前列腺癌新发病例临床分期偏晚,Gleason级别较高,临床上多表现为进展期前列腺癌,已失去手术机会[1]。雄激素剥夺治疗(androgen deprivation therapy,ADT)是进展期前列腺癌的主要治疗手... 前列腺癌是男性泌尿生殖系统最常见的恶性肿瘤,我国前列腺癌新发病例临床分期偏晚,Gleason级别较高,临床上多表现为进展期前列腺癌,已失去手术机会[1]。雄激素剥夺治疗(androgen deprivation therapy,ADT)是进展期前列腺癌的主要治疗手段,可显著抑制前列腺癌的进展,但是几乎所有患者在治疗12~18个月后进展为更具侵袭性的去势抵抗性前列腺癌(castration resistant prostate cancer,CRPC)[2]。 展开更多
关键词 神经内分泌前列腺癌 谱系可塑性 肿瘤异质性 靶向治疗
下载PDF
Preface 被引量:1
4
作者 Andrea Bertozzil Ron Fedkiw +5 位作者 Frederic Gibou Chiu-Yen Kao Chi-Wang Shu Richard Tsai Wotao Yin Hong-Kai Zhao 《Communications on Applied Mathematics and Computation》 EI 2024年第2期755-756,共2页
During April 20-22,2022,colleagues and friends gathered at the Institute of Pure&Applied Mathematics(IPAM),at the University of California at Los Angeles to celebrate Professor Stanley Osher's 8Oth birthday in... During April 20-22,2022,colleagues and friends gathered at the Institute of Pure&Applied Mathematics(IPAM),at the University of California at Los Angeles to celebrate Professor Stanley Osher's 8Oth birthday in a conference focusing on recent developments in"Optimization,Shape analysis,High-dimensional differential equations in science and Engineering,and machine learning Research(OSHER)"This conference hosted in-person talks by mathematicians,scientists,and industrial professionals worldwide.Those who could not attend extended their warm regards and expressed their appreciation for Professor Osher. 展开更多
关键词 Stanley gathered BIRTHDAY
下载PDF
Orthogonal matrix of polarization combinations:concept and application to multichannel holographic recording
5
作者 Shujun Zheng Jiaren Tan +4 位作者 Hongjie Liu Xiao Lin Yusuke Saita Takanori Nomura Xiaodi Tan 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2024年第10期4-13,共10页
Orthogonal matrices have become a vital means for coding and signal processing owing to their unique distributional properties.Although orthogonal matrices based on amplitude or phase combinations have been extensivel... Orthogonal matrices have become a vital means for coding and signal processing owing to their unique distributional properties.Although orthogonal matrices based on amplitude or phase combinations have been extensively explored,the orthogonal matrix of polarization combinations(OMPC)is a novel,relatively unexplored concept.Herein,we propose a method for constructing OMPCs of any dimension encompassing 4n(where n is 1,2,4,8,…)mutually orthogonal 2ncomponent polarization combinations.In the field of holography,the integration of polarization multiplexing techniques with polarization-sensitive materials is expected to emerge as a groundbreaking approach for multichannel hologram multiplexing,offering considerable enhancements in data storage capacity and security.A multidimensional OMPC enables the realization of multichannel multiplexing and dynamical modulation of information in polarization holographic recording.Despite consolidating all information into a single position within the material,we effectively avoided extraneous crosstalk during the reconstruction process.Our results show that achieving four distinct holographic images individually and simultaneously depends on the polarization combination represented by the incident wave.This discovery opens up a new avenue for achieving highly holographic information storage and dynamically displayed information,harnessing the potential of OMPC to expand the heretofore limited dimensionality of orthogonal polarization. 展开更多
关键词 orthogonal matrix of polarization combinations polarization-modulated multiplexing multichannel recording polarization holography dynamical information modulation
下载PDF
Effectiveness of mindfulness-based interventions on the well-being of healthcare workers:a systematic review and meta-analysis
6
作者 Natasha Yixuan Ong Finn Jing Jie Teo +4 位作者 Jane Zi Ying Ee Chun En Yau Julian Thumboo Hiang Khoon Tan Qin Xiang Ng 《General Psychiatry》 CSCD 2024年第3期335-344,共10页
Background Growing evidence attests to the efficacy of mindfulness-based interventions(MBIs),but their effectiveness for healthcare workers remains uncertain.Aims To evaluate the evidence for MBIs in improving healthc... Background Growing evidence attests to the efficacy of mindfulness-based interventions(MBIs),but their effectiveness for healthcare workers remains uncertain.Aims To evaluate the evidence for MBIs in improving healthcare workers’psychological well-being.Methods A systematic literature search was conducted on Medline,Embase,Cumulative Index for Nursing and Allied Health Literature,PsycINFO and Cochrane Central Register of Controlled Trials up to 31 August 2022 using the keywords‘healthcare worker’,‘doctor’,‘nurse’,‘allied health’,‘mindfulness’,‘wellness’,‘workshop’and‘program’.Randomised controlled trials with a defined MBI focusing on healthcare workers and quantitative outcome measures related to subjective or psychological well-being were eligible for inclusion.R V.4.0.3 was used for data analysis,with the standardised mean difference as the primary outcome,employing DerSimonian and Laird’s random effects model.Grading of Recommendations,Assessment,Development and Evaluation framework was used to evaluate the quality of evidence.Cochrane’s Risk of Bias 2 tool was used to assess the risk of bias in the included studies.Results A total of 27 studies with 2506 participants were included,mostly from the USA,involving various healthcare professions.MBIs such as stress reduction programmes,apps,meditation and training showed small to large effects on anxiety,burnout,stress,depression,psychological distress and job strain outcomes of the participants.Positive effects were also seen in self-compassion,empathy,mindfulness and well-being.However,long-term outcomes(1 month or longer postintervention)varied,and the effects were not consistently sustained.Conclusions MBIs offer short-term benefits in reducing stress-related symptoms in healthcare workers.The review also highlights limitations such as intervention heterogeneity,reduced power in specific subgroup analyses and variable study quality. 展开更多
关键词 NURSE SUSTAINED workers
下载PDF
Advancements in Photovoltaic Panel Fault Detection Techniques
7
作者 Junyao Zheng 《Journal of Materials Science and Chemical Engineering》 2024年第6期1-11,共11页
This paper examines the progression and advancements in fault detection techniques for photovoltaic (PV) panels, a target for optimizing the efficiency and longevity of solar energy systems. As the adoption of PV tech... This paper examines the progression and advancements in fault detection techniques for photovoltaic (PV) panels, a target for optimizing the efficiency and longevity of solar energy systems. As the adoption of PV technology grows, the need for effective fault detection strategies becomes increasingly paramount to maximize energy output and minimize operational downtimes of solar power systems. These approaches include the use of machine learning and deep learning methodologies to be able to detect the identified faults in PV technology. Here, we delve into how machine learning models, specifically kernel-based extreme learning machines and support vector machines, trained on current-voltage characteristic (I-V curve) data, provide information on fault identification. We explore deep learning approaches by taking models like EfficientNet-B0, which looks at infrared images of solar panels to detect subtle defects not visible to the human eye. We highlight the utilization of advanced image processing techniques and algorithms to exploit aerial imagery data, from Unmanned Aerial Vehicles (UAVs), for inspecting large solar installations. Some other techniques like DeepLabV3 , Feature Pyramid Networks (FPN), and U-Net will be detailed as such tools enable effective segmentation and anomaly detection in aerial panel images. Finally, we discuss implications of these technologies on labor costs, fault detection precision, and sustainability of PV installations. 展开更多
关键词 Photovoltaic Panels Fault Detection Deep Learning Image Processing
下载PDF
白令海楚科奇海的海冰范围变化特征 被引量:9
8
作者 胡宪敏 苏洁 +1 位作者 赵进平 Genevieve Hiltebrand 《冰川冻土》 CSCD 北大核心 2007年第1期53-60,共8页
白令海和楚科奇海位于北极太平洋一侧的海冰外缘线附近,具有较强烈的气冰海相互作用.采用滑动t检验和小波分析方法对白令海和楚科奇海1953—2004年海冰范围的年际变化、年代际变化和总体趋势变化进行分析.结果表明:20世纪70年代后期,海... 白令海和楚科奇海位于北极太平洋一侧的海冰外缘线附近,具有较强烈的气冰海相互作用.采用滑动t检验和小波分析方法对白令海和楚科奇海1953—2004年海冰范围的年际变化、年代际变化和总体趋势变化进行分析.结果表明:20世纪70年代后期,海冰范围在白令海存在显著的均值突变现象,而楚科奇海在对应阶段则表现为更明显的变频现象;在突变点前后两个时段里,阿留申低压中心低压加强、核心位置偏移以及对应风场分布的变化是导致白令海海冰范围明显缩小的主要动力原因.楚科奇海海冰范围的年际变化中存在由低频向高频变化的现象,该现象除了在局地气温变化中存在之外,在北冰洋区域风涡度、波弗特海纬向风、东西伯利亚海经向风等动力因素中也有所体现.因此,除热力因素外,动力因素引起的海冰的平流与该变频现象也存在一定的联系. 展开更多
关键词 白令海 楚科奇海 海冰范围 突变 阿留申低压
下载PDF
胞外Ca^(2+)信号——动植物中的第一信使 被引量:10
9
作者 赵昕 裴真明 何奕昆 《遗传》 CAS CSCD 北大核心 2007年第3期269-275,共7页
钙离子作为重要的胞内第二信使,控制着许多细胞的功能,人们对此已经研究得比较深入。然而最近发现的一些细胞表面胞外Ca2+探测器使我们想到是否在胞外环境中,钙离子也具有信号分子的功能。钙离子传感器包括已经研究得比较清楚的胞外Ca2... 钙离子作为重要的胞内第二信使,控制着许多细胞的功能,人们对此已经研究得比较深入。然而最近发现的一些细胞表面胞外Ca2+探测器使我们想到是否在胞外环境中,钙离子也具有信号分子的功能。钙离子传感器包括已经研究得比较清楚的胞外Ca2+敏感受体—最初从甲状旁腺分离的G-耦联蛋白受体(CaR),另外,还有其他受体、通道和膜蛋白也都对胞外[Ca2+]的变化很敏感。最近从拟南芥保卫细胞中克隆到一个胞外钙离子受体蛋白(CAS),通过胞外钙离子的变化引起胞内钙离子信号。这些受体蛋白的克隆,使人们确信Ca2+在细胞中可以发挥第一信使的功能。 展开更多
关键词 CA^2+ 胞外Ca^2+敏感受体(caR) 胞外钙离子受体(CAS)
下载PDF
一氧化氮在植物中的信号分子功能研究:进展和展望 被引量:21
10
作者 刘维仲 张润杰 +1 位作者 裴真明 何奕昆 《自然科学进展》 北大核心 2008年第1期10-24,共15页
一氧化氮(NO)是一种生物活性分子,越来越多的证据表明它是生物体内分布最为广泛的信号分子之一.NO作为植物生长发育的一个关键调节因子,能对各种生物或非生物胁迫产生应答,在植物生长发育与环境互作的协调过程中起着中枢性的作用.近年来... 一氧化氮(NO)是一种生物活性分子,越来越多的证据表明它是生物体内分布最为广泛的信号分子之一.NO作为植物生长发育的一个关键调节因子,能对各种生物或非生物胁迫产生应答,在植物生长发育与环境互作的协调过程中起着中枢性的作用.近年来,对于一氧化氮在植物中分子功能的研究取得了较大进展,特别是其信号转导功能、对基因表达的调控和植物体内NO稳态平衡的维持等方面.文中较全面地介绍了植物体内NO的合成、功能、信号转导、对基因表达的调控以及植物体内NO动态平衡的维持等方面研究的进展,并对该领域今后的研究进行了展望. 展开更多
关键词 一氧化氯 信号转导 信号分子 稳态平衡
下载PDF
植物保卫细胞离子通道在气孔运动中的作用 被引量:11
11
作者 薛绍武 杨频 裴真明 《植物生理学通讯》 CSCD 北大核心 2004年第4期489-494,共6页
介绍保卫细胞质膜和液泡膜上的离子通道活性变化及其在气孔运动中的作用,同时对各种刺激引发气孔运动过程中的信使Ca2+、H2O2和pH等对离子通道的调节作用作了概述。
关键词 植物 保卫细胞 离子通道 气孔运动 胞质钙 H202
下载PDF
电磁致热超声系统设计及基于小波阈值去噪方法的信号处理 被引量:2
12
作者 陈国平 于万宝 +2 位作者 赵志钦 聂在平 柳清伙 《电子学报》 EI CAS CSCD 北大核心 2008年第6期1130-1134,共5页
本文给出了一个电磁致热超声(EMITA)实验系统,针对实验信号的提取问题,首先研究了实验平台的改进方法,通过置入波导内容器截面的设计,增加微波透过率;对耦合液的选择研究,减小微波脉冲对超声波接收传感器的电磁冲击,从而提高系统在强电... 本文给出了一个电磁致热超声(EMITA)实验系统,针对实验信号的提取问题,首先研究了实验平台的改进方法,通过置入波导内容器截面的设计,增加微波透过率;对耦合液的选择研究,减小微波脉冲对超声波接收传感器的电磁冲击,从而提高系统在强电磁脉冲下的电磁兼容(EMC)能力;其次为了从低信噪比数据中有效提取EMITA超声信号,研究了应用小波分析方法和阈值去噪重构方法处理实验采集的EMITA信号. 展开更多
关键词 电磁致热超声 小波分析 阈值去噪重构
下载PDF
基于BSWT-DDTFA方法的地球天然脉冲电磁场震前信号时频分析研究 被引量:5
13
作者 郝国成 白雨晓 +2 位作者 吴敏 王巍 刘辉 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2018年第10期4063-4074,共12页
地球天然脉冲电磁场(ENPEMF)信号,可理解为地球天然变化磁场的瞬间扰动,携带了大量有用的地质构造及其动力学信息.研究ENPEMF信号所蕴含的时间-频率联合分布特点,有利于深入了解目标对象的地球物理现象及其地质动力学原理.本文针对ENPEM... 地球天然脉冲电磁场(ENPEMF)信号,可理解为地球天然变化磁场的瞬间扰动,携带了大量有用的地质构造及其动力学信息.研究ENPEMF信号所蕴含的时间-频率联合分布特点,有利于深入了解目标对象的地球物理现象及其地质动力学原理.本文针对ENPEMF信号的非平稳特点,在数据驱动时频分析方法(DDTFA)的基础上提出了基于二值化同步压缩小波变换的改进算法(BSWT-DDTFA).该算法可以实现数据驱动初始相位自动赋值的功能,具有自适应性.实验仿真和实际数据均证明了该改进算法不仅能够得到较为精确的频率曲线和更加清晰的时频分布,而且具有较强的抗噪声能力.以2013年芦山MS7.0地震为例,利用BSWT-DDTFA方法提取ENPEMF信号的时频特性,结果表明ENPEMF信号的时间-频率-幅度分布在震前有明显的异常特征. 展开更多
关键词 地球天然脉冲电磁场 时频分析 数据驱动 同步压缩变换 震前异常
下载PDF
松花江干流治理工程生态护坡覆土改良研究 被引量:9
14
作者 王笑峰 郭显锋 +2 位作者 蔡体久 王洪君 琚存勇 《森林工程》 2020年第3期1-6,共6页
为有效解决松花江干流堤防生态护坡覆土土源不足及土源质量差的问题,本研究选取工程现场剥离的表层稻田土和工程废弃的砂土、黏土为研究对象,依据3种土壤分析测定的理化特性,设计9种不同配比的改良土壤进行覆土改良试验研究,通过对改良... 为有效解决松花江干流堤防生态护坡覆土土源不足及土源质量差的问题,本研究选取工程现场剥离的表层稻田土和工程废弃的砂土、黏土为研究对象,依据3种土壤分析测定的理化特性,设计9种不同配比的改良土壤进行覆土改良试验研究,通过对改良土壤的颗粒组成、水分特征、养分状况以及盆栽试验植物生长状况的测定、调查和综合对比分析,处理M(50%稻田土+25%砂土+25%黏土)和处理O(50%稻田土+10%砂土+40%黏土)均可作为松花江干流堤防生态护坡适宜的覆土改良配比。此配比的改良土壤在保证护坡植被正常生长的前提下,能够减少腐殖土用量50%,充分利用现场废弃土,有效降低工程建设成本,对黑龙江省河流堤防生态护坡建设具有较强的实践指导意义和广泛推广应用价值。对于改良土壤中速效氮缺乏和有机质含量不高的问题,可通过坡面种植豆科绿肥植物和添加废弃水稻秸秆等方法加以补充和改善。 展开更多
关键词 生态护坡 覆土 土壤改良
下载PDF
环境与遗传因素交互作用对老龄健康的影响——相关前期研究综述 被引量:5
15
作者 曾毅 程令国 +6 位作者 阮荣平 陈华帅 李建新 张风雨 陶伟 顾军 田小利 《医学与哲学(A)》 北大核心 2014年第9期1-6,25,共7页
综述了环境与遗传交互作用对老龄健康影响的文献和国际研究进展,概述三个相关前期研究案例:FOXO基因类型与高龄老人60岁左右和当前喝茶的交互作用显著影响高龄老人健康,携带FOXO基因者喝茶对认知功能改善作用比不携带FOXO基因者显著要大... 综述了环境与遗传交互作用对老龄健康影响的文献和国际研究进展,概述三个相关前期研究案例:FOXO基因类型与高龄老人60岁左右和当前喝茶的交互作用显著影响高龄老人健康,携带FOXO基因者喝茶对认知功能改善作用比不携带FOXO基因者显著要大;ADRB2-rs1042718或ADRB2-rs1042719基因类型与经常锻炼和参加社会休闲活动的交互作用对高龄老人认知功能和自评健康有显著改善;APOE4基因与生活重压交互作用会显著诱发老人自评健康差。根据研究分析结论,建议在保护个人隐私前提下,充分考虑环境因素与基因类型交互作用,实行有的放矢的健康干预方案,可能大大提高老龄健康干预效益。 展开更多
关键词 老龄健康 环境与遗传交互作用 健康干预 生活重压 基因类型
下载PDF
层状介质中计算体积分方程的弱化BCGS-FFT算法 被引量:10
16
作者 魏宝君 LIU Q H 《中国石油大学学报(自然科学版)》 EI CAS CSCD 北大核心 2007年第1期49-55,共7页
采用弱化稳定型双共轭梯度快速Fourier变换(BCGS-FFT)算法精确计算了层状介质中的体积分方程。采用递推矩阵方法计算层状介质中的并矢Green函数,可以很方便地与体积分方程结合。将“屋顶”函数作为基函数和试探函数对体积分方程进行弱... 采用弱化稳定型双共轭梯度快速Fourier变换(BCGS-FFT)算法精确计算了层状介质中的体积分方程。采用递推矩阵方法计算层状介质中的并矢Green函数,可以很方便地与体积分方程结合。将“屋顶”函数作为基函数和试探函数对体积分方程进行弱化离散,从而有效地避免了体积分方程的奇异性。离散后的体积分方程采用稳定型双共轭梯度迭代方法进行求解,从而得到异常体内电场的分布。假设异常体只分布在层状介质中的某一层介质内,则体积分方程内并矢Green函数与对比源之间的乘积可表示为褶积或相关形式,从而在每一次迭代过程中可以同时在x,y,z方向采用快速Fourier变换技术加快运算速度。数值算例说明了该算法的精确性和有效性。 展开更多
关键词 体积分方程 弱化BCGS-FFT算法 并矢Green函数 层状介质 电法测井
下载PDF
过墙壁探测:层状介质中二维层析成像模拟
17
作者 魏宝君 LIU Q H 《中国石油大学学报(自然科学版)》 EI CAS CSCD 北大核心 2007年第3期49-53,58,共6页
开发了一种基于对比源反演(CSI)算法的二维非线性逆散射技术,对层状介质中的二维物体进行层析成像并用其模拟过墙壁探测。对一些复杂模型的反演结果说明了CSI算法的有效性和进行过墙壁探测的可行性。数值模拟结果表明,在观测受到限制的... 开发了一种基于对比源反演(CSI)算法的二维非线性逆散射技术,对层状介质中的二维物体进行层析成像并用其模拟过墙壁探测。对一些复杂模型的反演结果说明了CSI算法的有效性和进行过墙壁探测的可行性。数值模拟结果表明,在观测受到限制的情况下通过对多种频率的数据进行反演仍可以精确重构被探测目标的位置、形状及电参数。 展开更多
关键词 对比源反演(CSI)算法 层状介质 层析成像 过墙壁探测 快速FOURIER变换
下载PDF
Hepatitis C virus core antigen testing: Role in diagnosis, disease monitoring and treatment 被引量:7
18
作者 Hans L Tillmann 《World Journal of Gastroenterology》 SCIE CAS 2014年第22期6701-6706,共6页
While hepatitis B virus(HBV)screening relies on hepatitis B surface antigen to confirm HBV infection since the early days of hepatitis B disease management,hepatitis C virus(HCV)infection screening is based on anti-HC... While hepatitis B virus(HBV)screening relies on hepatitis B surface antigen to confirm HBV infection since the early days of hepatitis B disease management,hepatitis C virus(HCV)infection screening is based on anti-HCV testing which does not discriminate active from past infection.Thus to confirm infection HCV RNA testing has been required;recently a HCV core antigen assay became widely commercially available which could serve to confirm infection.That assay is less sensitive than current HCV RNA assays,but as more than 50%of anti-HCV positive persons will be HCV core antigen positive,HCV core antigen testing can be a cost effective and reflex test to confirm HCV infection in anti-HCV positive individuals and will be easier as it can be applied on the same platform.For treatment monitoring,more data need to be generated,but the early data available at present suggest that HCV core antigen may be an alternative to HCV RNA monitoring.With direct antivirals,HCV core antigen could even be superior to HCV RNA testing,as direct antivirals might already prevent virus formation when HCV core antigen is still produced and thereby correlates better with eventual viral clearance. 展开更多
关键词 Hepatitis C virus Hepatitis C Diagnostic assay Diagnostic accuracy Hepatitis C virus core antigen Treatment monitoring
下载PDF
Hopf-flip bifurcation of high dimensional maps and application to vibro-impact systems 被引量:9
19
作者 Jianhua Xie Wangcai Ding +1 位作者 E.H. Dowell L. N. Virgin 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2005年第4期402-410,共9页
This paper addresses the problem of Hopf-flip bifurcation of high dimensional maps. Using the center manifold theorem, we obtain a three dimensional reduced map through the projection technique. The reduced map is fur... This paper addresses the problem of Hopf-flip bifurcation of high dimensional maps. Using the center manifold theorem, we obtain a three dimensional reduced map through the projection technique. The reduced map is further transformed into its normal form whose coefficients are determined by that of the original system. The dynamics of the map near the Hopf-flip bifurcation point is approximated by a so called “time-2τ^2 map” of a planar autonomous differential equation. It is shown that high dimensional maps may result in cycles of period two, tori T^1 (Hopf invariant circles), tori 2T^1 and tori 2T^2 depending both on how the critical eigenvalues pass the unit circle and on the signs of resonant terms' coefficients. A two-degree-of-freedom vibro-impact system is given as an example to show how the procedure of this paper works. It reveals that through Hopf-flip bifurcations, periodic motions may lead directly to different types of motion, such as subharmonic motions, quasi-periodic motions, motions on high dimensional tori and even to chaotic motions depending both on change in direction of the parameter vector and on the nonlinear terms of the first three orders. 展开更多
关键词 MAPS Vibro-impact dynamics Hopf-flip bifurcation TORUS CHAOS
下载PDF
Textbook outcomes in hepatobiliary and pancreatic surgery 被引量:7
20
作者 Diamantis I Tsilimigras Timothy Michael Pawlik Dimitrios Moris 《World Journal of Gastroenterology》 SCIE CAS 2021年第15期1524-1530,共7页
The concept of textbook outcome (TO) has recently gained popularity in surgicalresearch and has been used to evaluate the quality or success of different surgicalprocedures, including hepatopancreatobiliary (HPB) oper... The concept of textbook outcome (TO) has recently gained popularity in surgicalresearch and has been used to evaluate the quality or success of different surgicalprocedures, including hepatopancreatobiliary (HPB) operations. TO consists ofindividual outcome parameters that each reflect different domains of careincluding structure, process, and individual outcomes;in turn, the composite TOmetric represents the optimal course after a surgical episode. TO can be used toassess patient-level outcomes, hospital performance, center designation andquality metrics. In addition to being an outcome measurement, TO may also belinked to healthcare costs. Future efforts should be directed towards establishing auniversal definition of TO in HPB surgery so that surgeons and hospitals canassess and compare outcomes, identify shortcomings and improve real worldpatient outcomes. 展开更多
关键词 TEXTBOOK OUTCOME Hepatopancreatobiliary SURGERY
下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部