Ankle-brachial index and brachial-ankle pulse wave velocity are risk factors for ischemic stroke in patients with type 2 diabetes

The incidence of ischemic stroke in patients with diabetes is increasing. While brachial-ankle pulse wave velocity （BaPWV） and ankle-bra- chial index （ABI） are known to be associated with ischemic cardiovascular and cerebrovascular diseases, whether these measures predict the risk of ischemic cerebrovascular disease in diabetic patients remains unclear. 117 patients with type 2 diabetes were enrolled in this study. According to the results of head magnetic resonance imaging, the patients were divided into a diabetes-only group （n = 55） and a diabetes and ischemic stroke group （n = 62）. We then performed ABI and BaPWV examinations for all patients. Compared with the diabe- tes-only group, we found decreased ABI and increased BaPWV in the diabetes and ischemic stroke group. Multivariate logistic regression analyses revealed that BaPWV and ABI were risk factors for ischemic stroke in patients with type 2 diabetes. Our findings indicate that decreased ABI and increased BaPWV are objective indicators of increased risk of ischemic stroke in patients with type 2 diabetes.

Changes in mean cerebral blood flow velocity during cognitive task-induced cerebral fatigue in high performance fighter pilots

BACKGROUND： Several studies have demonstrated that sustained cognitive tasks can induce cognitive fatigue and that the mean cerebral blood flow velocity changes in some cerebral regions during cerebral fatigue. OBJECTIVE： To dynamically monitor the changes in mean cerebral blood flow velocity in different brain regions of high performance fighter pilots during mental arithmetic tasks and consecutive performance tasks. DESIGN, TIME AND SETTING： The present neurophysiological trial, based on controlled observation, was performed at the Laboratory of Neurophysiology, Institute of Aviation Medicine, Air Force of China between January 2003 and December 2005. PARTICIPANTS： Forty-five males, high performance fighter pilots, averaging （27.6±2.5） years, were recruited for this study. METHODS： The mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery of subjects was dynamically tested using transcranial Doppler during 5- hour mental arithmetic tasks and during 5- hour consecutive performance tasks. The neurobehavioral ability index was analyzed throughout each trial according to the number of correct responses, false responses, and lost responses. Simultaneously, cerebral cognitive fatigue-induced lethargy was assessed by the Stanford Sleepiness Scale. MAIN OUTCOME MEASURES： Changes in mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery; neurobehavioral ability index of mental arithmetic and consecutive performance tasks; Stanford Sleepiness Scale scores. RESULTS： During mental arithmetic tasks, the mean cerebral blood flow velocity in the anterior cerebral artery increased during hour 2 and decreased after hour 4. There was no significant change in mean cerebral blood flow velocity in the middle cerebral artery and posterior cerebral artery. During hour 4, cerebral cognitive fatigue was observed and, simultaneously, Stanford Sleepiness Scale scores demonstrated the presence of fatigue. During such a stage, the neurobehavioral ability index decreased, indicating a decline in performance ability. During consecutive performance tasks, the mean cerebral blood flow velocity declined earlier in the posterior cerebral artery compared to the middle cerebral artery. CONCLUSION： Five- hour mental arithmetic tasks have few effects on cerebral functions and do not lead to a significant change in mean cerebral blood flow velocity. Five-hour consecutive performance tasks can induce cerebral cognitive fatigue, and a marked decline in mean cerebral blood flow velocity.

农村电网35kV输电线路工程造价评价指标模型

随着中国电网建设的快速发展,传统的输电工程造价评价指标已逐渐难以满足当前造价管理和项目评价的需要,亟待提出经过改进的更合理的评价指标。以内蒙古自治区巴彦淖尔市农村电网1998—2006年30个新建35 kV输电线路工程造价数据为统计样本,应用ABC分类法对影响35 kV输电线路工程造价的影响因子进行了筛选,并分别进行因子分析和独立性分析,再应用多元线性回归方法确定每个因子的影响程度,在此基础上建立了35 kV输电线路综合线路长度造价评价指标。经实际工程验证,所建立评价指标较之传统指标的准确性明显改善。

±800kV特高压直流输电线路电磁环境参数控制指标研究

采用长距离、大容量输电时,特高压直流输电能够有效地节省线路走廊、有助于改善网络结构,实现大范围的资源优化配置。总结了国内外研究成果,结合我国实际情况,就如何规范±800kV特高压直流输电线路的环境行为,围绕电场、磁场、无线电干扰和可听噪声等电磁环境参数进行研究,提出了环境参数的控制指标:以30kV/m作为直流输电线路下方最大地面合成场强的控制指标;25kV/m作为邻近民房的最大合成场强的控制指标;以好天气下58dB(μV/m)为距极导线投影外侧20m处0.5MHz的无线电干扰电平的控制指标;L50=50dB(A)为线路可听噪声设计控制指标,人口密集区以L50=45dB(A)校核。

±800 kV特高压直流输电线路微气象实时监测与带电作业安全评估方法研究

针对特高压直流输电线路局地微气象复杂多变、难以准确预报且给带电作业安全开展带来较大问题,基于定点监测手段,实时获取输电线路局地微气象信息;在此基础上,分析了±800 kV输电线路带电作业安全影响因素,基于气体击穿理论修正了气压、温度及湿度对最小安全距离的影响,构建了以最小安全距离、气象条件、地形条件、作业人员条件及作业设备条件等因素为指标的±800 kV特高压直流输电线路带电作业安全评估指标体系。基于评价指标层次结构建立关系矩阵及模糊一致矩阵,获取项目层及指标层各因素的权值;划分带电作业安全等级,结合半梯形和三角形函数构建各指标隶属度函数,采用模糊综合评估法获得带电作业安全等级。针对四川锦苏线±800 kV带电作业安全等级进行了评估,验证了所提方法的正确性及有效性。该方法为实时准确地获取输电线路局地微气象信息及±800 kV特高压直流输电线路带电作业安全评估提供了参考。

Assessment of cerebrovascular reserve impairment using the breath-holding index in patients with leukoaraiosis

Many studies have demonstrated that leukoaraiosis is associated with impaired cerebrovascular reserve function. However, the definitive hemodynamic changes that occur in leukoaraiosis are not clear, and there are many controversies. This study aimed to investigate hemodynamic changes in symptomatic leukoaraiosis using transcranial Doppler ultrasonography and the breath-holding test in a Chinese Han population, from northern China. A total of 203 patients who were diagnosed with ischemic stroke or clinical chronic progressive ischemic symptoms were enrolled in this study, including 97 males and 106 females, with an age range of 43-93 years. The severity of leukoaraiosis was evaluated according to the Fazekas grading scale, and patients were divided into four groups accordingly. Grade 0 was no leukoaraiosis, and grades I, II, and III were mild, moderate, and severe leukoaraiosis, respectively, with 44, 79, 44, and 36 cases in each group. Transcranial Doppler ultrasonography and the breath-holding test were performed. The mean blood flow velocity of the bilateral middle cerebral artery was measured and the breath-holding index was calculated. The breath holding index was correlated with leukoaraiosis severity and cognitive impairment. Patients with a low breath holding index presented poor performance in the Montreal Cognitive Assessment (MoCA) and executive function tests. That is, the lower the breath holding index, the lower the scores for the MoCA and the higher for the trail-making test Parts A and B. These results indicate that the breath-holding index is a useful parameter for the evaluation of cerebrovascular reserve impairment in patients with leukoaraiosis. In addition, the breath-holding index can reflect cognitive dysfunction, providing a new insight into the pathophysiology of leukoaraiosis. This study was approved by the Ethics Committee of the Fifth Peoples Hospital of Shenyang, China (approval No. 20160301) and registered in the Chinese Clinical Trial Registry (registration number: ChiCTR1800014421).

500kV XLPE电缆绝缘中树枝化现象的述评

介绍日本开发 5 0 0 k V XL PE电力电缆时研究树枝化现象的形成 ,评述 XL PE电缆形成电树和水树与场强的相关性、树枝引发场强和长期寿命特性的研究结果 ,说明由此确定 5 0 0 k V XL PE电力电缆的绝缘设计。

Elevated radial arterial augmentation index in hypertensive patients with diastolic dysfunction

Objective To investigate the correlation between augmentation index (AI) of the radial artery and diastolic heart function in patients with hypertension. Methods Echocardiographs were obtained for 305 patients with hypertension. AI, pulse wave velocity (PWV) of peripheral arteries and serum pro-brain natriuretic peptide (proBNP) levels were determined. Correlations and receiver operating characteristic (ROC) curves were drawn between AI values and impaired diastolic function. Results AI levels were significantly increased in patients with impaired diastolic function diagnosed by ultrasound. Assessment of diastolic heart function based on proBNP levels revealed that AI and aortic pulse wave velocity were significantly elevated in patients with impaired diastolic function. The operating curve indicated that AI may be a more accurate and efficient index for the evaluation of impaired diastolic function compared to PWV. Correlation analysis also showed that proBNP levels had altered in parallel with changes in AI and PWV. After adjusting for various factors including age, gender, blood pressure and blood lipid, a positive correlation was observed between proBNP and AI with a correlation coefficient of 0.3697 (P=0.003). However, no correlation between proBNP and aortic PWV was seen after adjustment. Conclusions Changes in radial AI levels may reflect parallel changes in diastolic cardiac function in patients with hypertension, suggesting that AI may be utilized as a non-invasive clinical indicator of diastolic heart function.

Superluminal light attenuated by strong dispersion of complex refractive index

The propagation of narrow packets of electromagnetic waves（EMWs） in frequency dispersive medium with the consideration of the complex refractive index is studied. It is shown that counting in the dispersion of the complex refractive index within the context of the conventional expression of the group velocity of narrow wave packets of EMWs propagating in a dispersive medium results in the appearance of additional constraints on the group velocity, which dictates that the physically acceptable group velocity can only be realized in the case of a negligible imaginary part of the group index. In this paper, the conditions that allow one to realize the physically acceptable group velocity are formulated and analyzed numerically for the relevant model of the refractive index of a system of two-level atoms in the optical frequency range. It is shown that in the frequency band where superluminal light propagation is expected, there is a strong dispersion of the refractive index that is accompanied with strong absorption, resulting in a strongly attenuated superluminal light.

Detection of kinematics parameters of index finger movement with high-speed video camera

Synergic movement of finger's joints provides human hand tremendous dexterities,and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers.The present work is the attempt to investigate how the angular velocity and angular acceleration of the joints of index finger vary with respect to time during conducting a motor task.A high-speed video camera has been employed to visually record the movement of index finger,and miniaturized(5-mm diameter) reflective markers have affixed to the subject's index finger on the side close to thumb and dorsum of thumb at different joint landmarks.Captured images have been reviewed frame by frame to get the coordinate values of each joint,and the angular displacements,angular velocities and angular acceleration can be obtained with triangle function.The experiment results show that the methods here can detect the kinematics parameters of index finger joints during moving,and can be a valid route to study the motor function of index finger.

10kV配电网线损指标体系及降损潜力测算模型

在电网分压线损统计中,供电量大但管理水平较低的10kV配电网线损电量占比最大。针对这种情况,对国内供电企业10kV配电网线损管理工作进行深入调研分析,找寻10kV配电网线损管理特点及不足之处,并通过建立两级指标体系来分析影响线损的众多指标;基于指标体系、FCM聚类算法和等值电阻法,设计了一种10kV配电网线损降损潜力测算模型;然后给出10kV配电网节能管理的具体措施;最后,以某大型城市10kV配电网实际数据为例,对该测算模型进行测试,结果显示该模型可客观测算10kV配电网节能降损潜力,为线损管理提供数据支持及考核指标。

Prediction of Young’s modulus of weathered igneous rocks using GRNN,RVM,and MPMR models with a new index

Young’s modulus(YM)of intact rock is an important parameter in the assessment of engineering behaviours of rock masses,and it cannot always be obtained in an economical and practical manner in laboratory experiments.The main purpose of this study is to examine the capability of the minimax probability machine regression(MPMR),relevance vector machine(RVM),and generalised regression neural network(GRNN)models for the prediction of YM.The other aim is to determine the usefulness of a new index,the n-durability index(ndrb),which is based on porosity and the slake durability index.According to the regression analysis performed in this study,the n-durability index as an explanatory parameter performs better than the P-wave velocity(Vp),porosity,and slake durability index in the models,considering the results herein as well as the existing literature.According to regression error characteristic curves,Taylor diagrams,and performance indices,the best prediction model is MPMR,while the worst is the GRNN model.Although GRNN is the worst of the soft computing models,its performance is slightly better than that of the multiple linear regression(MLR)model.According to the results of the study,the MPMR and RVM models with ndrb and Vp are successful tools that can predict the YM of igneous rock materials to different degrees.

Assessment of Arterial Stiffness Index in Hypertensive Patients in Relation to Their Treatment Status Attending a Tertiary Care Center in South India

Objectives: To assess the arterial stiffness index (ASI) and pulse wave velocity (PWV) in patients with hypertension and to compare with age matched healthy controls;to assess and compare the ASI and PWV in relation to the treatment status. Methods: The study was observational-cross sectional. Group one included chronic hypertensive patients on regular treatment for more than 2 months;group two included newly diagnosed hypertensive patients and group three had age matched healthy controls with normal blood pressure. The hypertensives subjects with other comormid conditions such as renal disease, diabetes were excluded from the study. The study was approved by the Institute Ethics Committee. The subjects were interviewed and explained the purpose of the study. All subjects gave written informed consent. The noninvasive periscope device was used to measure PWV, ASI and pulse pressure. Results: PWV, ASI and pulse pressure were statistically higher in hypertensive patients when compared to controls. Further, carotid-femoral PWV was correlated with mean arterial pressure in hypertensive subjects and was found to be statistically significant. Conclusion: PWV, ASI and pulse pressure are significantly higher in chronic and newly diagnosed non-diabetic hypertensives as compared to controls irrespective of their treatment status.

基于双基点法的10kV配电网供电质量评价方法

通过配电网传统电能质量指标和供电可靠性指标的研究,提出了10kV配电网供电质量的综合评价指标体系以及基于双基点法的10 kV配电网供电质量综合评价方法,并通过实际案例分析验证了该供电质量指标体系的合理性以及评价方法的有效性。

单轴压缩下松软煤体波速演化与裂隙分布特征

为研究松软煤体超声波传播规律与破坏特征,选用型煤代替原煤,设定3条波速传播路径,运用MTS岩石力学实验机、PCI-Ⅱ声发射仪开展单轴压缩条件下煤体多路径波速同步监测试验,引入各向异性指数分析波速演化规律;选定3个横、纵向切面,采用CT扫描设备开展破坏特征观测试验,重构破坏后煤体细观几何结构,对比研究二维横纵切面裂隙分布差异性;探讨波速和三维裂隙体积的关系。结果表明:①随轴向应变的增加,平行、垂直加载方向及煤体平均波速均表现出先平稳后降低再平稳的基本规律,波速各向异性指数具有先平稳后增大再平稳的变化趋势;垂直加载方向波速最先下降,且降幅最大。②与纵向切面相比,破坏后煤体横向切面裂隙谱峰占比和裂隙分形维数均较大,裂隙密度较高,裂隙形态也较为复杂。③随裂隙体积的增大,破坏后煤体平均波速大致呈线性降低,单轴荷载作用下煤体内部裂隙扩展以平行加载方向为主,裂隙竖向线状扩展是造成各方向波速和横纵切面破坏特征差异性的主要原因。④与平行加载方向相比,采用垂直加载方向波速求得的损伤变量较大、评价煤体损伤破坏状态也更为可靠。现场采用声波评价煤体破坏状态时,将声波传播路径设置为垂直煤体受载(最大主应力)方向,有利于提高预测失稳事故的合理性。

110 kV变电站带电作业安全综合评价应用分析

为确保110 kV变电站带电作业施工安全,通过将层次分析法与模糊评价方法相结合,建立了包括带电作业环境、作业人员素质、作业机具与防护及安全管理等因子的递阶层次安全综合评价指标体系,通过构建安全评价等级,分析了带电作业安全状况,并针对某110 kV变电站带电作业进行了安全评价。

10 kV配网不停电作业技术的应用分析

分析10 kV配网不停电作业技术的应用情况,提出评价指标并进行实证分析,同时探讨如何进一步优化技术应用。从基于气体绝缘开关的不停电转供技术、不停电接地故障割除技术以及基于局部放电在线监测的不停电巡检技术等3个方面,列举不同10 kV配网不停电作业技术的具体应用案例,并针对上述3种技术的应用效果进行了实证分析,通过表格方式对各项指标进行数据统计及分析和总结。最后,针对应用过程中存在的问题提出了相应的优化措施,包括进一步完善技术细节、提高操作人员的技术水平和加强设备维护保养等方面。

甘油三酯-葡萄糖乘积指数与动脉硬化进展的回顾性队列研究

目的:胰岛素抵抗(insulin resistance,IR)与动脉硬化和不良心血管病事件均存在密切关联。甘油三酯-葡萄糖(triglyceride-glucose,TyG)指数可作为评估IR的有效指标。本研究旨在探讨Ty G指数与动脉硬化进展风险的关系。方法:本研究为回顾性队列研究。选取2012年1月至2022年12月在中南大学湘雅三医院健康管理医学中心参加健康体检次数≥2且完成动脉硬化检测的成年人作为研究对象,收集其临床资料。TyG指数采用公式ln(甘油三酯×空腹血糖/2)计算。基线TyG指数分别以连续变量和四分位数的分类变量为自变量评价。动脉硬化进展采用臂踝脉搏波传导速度(brachial-ankle pulse wave velocity,baPWV)的年变化速率和新发动脉僵硬度增加为因变量评价。通过线性回归模型和Cox比例风险回归模型,探索TyG指数是否为动脉硬化进展的独立风险因素。根据年龄、性别、体重指数,以及是否合并2型糖尿病、高血压和高脂血症进行亚组分析,以确定TyG指数和动脉硬化进展之间的关联特征。结果:共纳入4971名研究对象,随访时间为(3.01±1.98)年。随访期间,baPWV的年变化速率为(24.94±81.15)cm/s,共计278例为新发动脉僵硬度增加。在全面校正混杂因素后,自变量为连续变量时,基线Ty G指数与baPWV的年变化速率(β=17.5,95%CI 9.00~25.94,P<0.001)和新发动脉僵硬度增加[风险比(hazard ratio,HR)=1.43,95%CI 1.18~1.74,P<0.001]呈独立正相关。自变量为分类变量时,与第1四分位数组相比,第2、3、4四分位数组的baPWV年变化速率依次增加,新发动脉僵硬度增加的风险也依次增高(均P<0.05)。年龄≥45岁、男性、BMI<28 kg/m2、高血压病、无高血压病、无2型糖尿病和无高脂血症亚组中,基线TyG指数(连续和分类变量)与新发动脉僵硬度增加具有明显关联(均P<0.05),各亚组均不存在显著的交互作用(均P>0.05)。结论:TyG指数与动脉硬化进展风险增加独立相关,可用作体检人群动脉硬化进展风险的评估指标。

110 kV变电站带电作业安全综合评价应用分析

为确保110 k V变电站带电作业施工安全,本文通过将层次分析法与模糊评价方法相结合,建立了包括带电作业环境、作业人员素质、作业机具与防护及安全管理等因子的递阶层次安全综合评价指标体系,通过构建安全评价等级,分析了带电作业安全状况,并针对湖南某110 k V变电站带电作业进行了安全评价,验证了评价模型的准确性。

准噶尔盆地东南缘页岩油储层脆性预测与评价

准噶尔盆地东南缘二叠系中下部发育页岩油致密储层,脆性预测与评价对其勘探和开发有重要意义。本文利用岩石物理实验、测井资料和叠前地震资料计算了准噶尔盆地东南缘二叠系页岩油致密储层脆性指数,对Rickman经典公式法、杨氏模量与泊松比比值法、拉梅系数法和剪切模量法进行了比较、分析与评价。研究认为:1)杨氏模量相对泊松比对岩性有更好的区分度,由拉梅系数表征的泥岩分布率较高;2)根据文献所得测井多参数计算脆性指数的方法应用效果不佳,在Castagna经验公式换算横波速度基础上计算的脆性指数具有较好的应用效果;3)由YPD(Young's modulus-Poisson's ratio-density)式和LMR(拉梅系数-密度)式反演的弹性参数变化率也能较好地指示有利储层,尤以密度变化率为最佳,该属性在扇三角洲前缘及分流河道特征上得到很好的展示;4)岩石物理实验和实际资料应用均表明,ρE/σ为研究区脆性的最佳表征公式,效果好于Rickman经典公式与其他方法。