自适应跌倒前实时检测方法

为了能利用单一传感器在跌倒撞击前实时检测出跌倒即将发生,结合支持向量机(SVM)和阈值法设计了一种自适应跌倒前实时检测方法.实验结果表明,该方法能在跌倒撞击前实时检测出跌倒即将发生,且比人工阈值法和SVM方法有更长的间隔时间,比SVM方法有更高的召回率和特异度.     

动车组进站过程精准停车控制方法研究

通过分析高速动车组进站停车过程中制动力与速度之间的关系,构建动车组多质点动力学模型。由于制动停车后期产生空气制动力过程给系统带来延时影响,引入Smith预估器,采用基于RBF(Radial Basis Function)神经网络的PID控制策略与Smith预估器相结合,实现制动过程中对给定速度的跟踪控制。仿真分析表明:该混合控制器控制的列车速度与设定速度的误差小于±1 km/h,停车误差小于±0.3 m,可满足进站制动停车的要求。     

产后早期肛提肌裂孔扩张程度及相关因素分析

目的 分析产后早期肛提肌裂孔扩张的影响因素.方法 盆底超声测量产后早期女性肛提肌裂孔面积,其中研究组为105名肛提肌裂孔扩张者,对照组为145名肛提肌裂孔正常者,对肛提肌裂孔扩张的相关因素进行二元Logistic回归分析.结果 研究组中盆底疾病的发生率高于对照组(P＜0.05),Logistic回归分析显示第二产程时间、胎儿体重、催产素使用和盆腔器官脱垂与肛提肌裂孔扩张显著相关(P＜0.05).结论 第二产程时间延长、催产素增加和胎儿体重增加是肛提肌裂孔扩张的影响因素,对预测和精确诊断盆底疾病有临床意义.     

河南方言词"高低"词汇化探析

在河南方言中,"高低"是一个使用频率极高的词汇.翻阅相关方言词典,发现对河南方言里"高低"的解释并不全面,但在口语及小说中却有很多用例,通过搜集具体的语料,发现在河南方言中双音节词"高低"的衍生途径,即通过并列式短语粘合而成,且有五种义项:高度层面的高低比较;水平优劣;分寸;无论如何、横竖;终究.     

联合功率域SPMA协议的动态阈值算法

针对基于优先级概率统计的多址接入(statistic priority-based multiple access, SPMA)模式协议在高负载情况下战术信息的碰撞概率十分严重, 网络性能无法满足协同攻击要求的问题, 本文借鉴非正交多址接入技术在功率域上区分同时同频信号的思想, 改进SPMA协议信号发送机制与多优先级检测机制, 在原有的时域、频域基础上引入功率域, 提出一种联合功率域的SPMA协议性能改进策略。并针对各优先级数据包到达率的动态变化场景, 设计动态阈值算法, 以达到降低碰撞概率, 提升网络吞吐量的目的。仿真结果表明, 采用该改进策略与动态阈值算法可以使网络承载更大的业务流量, 提高网络吞吐量。     

基于效率和经济价值的期货套期保值二次决策准则

基于不同风险测度得到的期货套期保值策略不同，利用套期保值效率可以对比分析不同风险测度下的套期保值效果。然而，当考虑套保成本时，套保效率大的套保策略不一定是“最优”的。为兼顾套保效率和套保成本，引入经济价值进一步对比不同套保策略的效用，提出期货套期保值二次决策准则。首先，构建方差、VaR和 CVaR等风险测度下的期货套期保值模型，给出最优套保头寸和套保效率的显式表达式，提出模型驱动下的最优套保策略决策准则；然后，考虑套保成本，基于经济价值提出不同套保策略的二次决策准则；最后，针对Brent原油期货套期保值进行实证分析，实证研究结果与理论研究相吻合。基于一次准则的最优套保策略的经济价值并不恒大于零，即当考虑套保成本时，基于套保效率最大的套保策略可能使投资者得不偿失，这也进一步体现了本文所构建的套保二次准则的有效性。     

The TET enzymes

During the past decade, we have learnt that the most common DNA modification, 5-methylcytosine (5mC), playing crucial roles in development and disease, is not stable but can be actively reversed to its unmodified form via enzymatic catalysis involving the TET enzymes. These ground-breaking discoveries have been achieved thanks to technological advances in the detection of the oxidized forms of 5mC and to the boldness of individual scientists. The TET enzymes require molecular oxygen for their catalysis, making them important targets for hypoxia research. They also require special cofactors which enable additional levels of regulation. Moreover, mutations and other genetic alterations in TETs are found, especially in myeloid malignances. This review focuses on the kinetic and inhibitory properties of the TET enzymes and the role of TETs in cellular differentiation and transformation and in cancer.     

Current knowledge on exosome biogenesis and release

Exosomes are nanosized membrane vesicles released by fusion of an organelle of the endocytic pathway, the multivesicular body, with the plasma membrane. This process was discovered more than 30 years ago, and during these years, exosomes have gone from being considered as cellular waste disposal to mediate a novel mechanism of cell-to-cell communication. The exponential interest in exosomes experienced during recent years is due to their important roles in health and disease and to their potential clinical application in therapy and diagnosis. However, important aspects of the biology of exosomes remain unknown. To explore the use of exosomes in the clinic, it is essential that the basic molecular mechanisms behind the transport and function of these vesicles are better understood. We have here summarized what is presently known about how exosomes are formed and released by cells. Moreover, other cellular processes related to exosome biogenesis and release, such as autophagy and lysosomal exocytosis are presented. Finally, methodological aspects related to exosome release studies are discussed.