非平稳海杂波的消除趋势波动分析

根据消除趋势波动分析(DFA)的基本原理,研究了非平稳条件下两种不同波段实测海杂波数据的分形标度特性以及海洋环境参数对分析结果的影响.采用分段数据均值/方差的差异、随机游走模型和对数方差-尺度法等对海杂波的非平稳性、分形特性和长程相关性进行定性判定.利用DFA得到的波动函数-尺度的双对数坐标曲线,分析了不同尺度范围内海杂波和目标单元的标度指数特性.对交叉标度现象的研究结果表明:它由海杂波本身的相关性在不同尺度范围存在差异导致的,且在VV极化时差异性更加显著.当海况改变时,不同尺度范围内标度指数的变化趋势与极化方式密切相关.最后,以拟合误差为检验统计量,对分析结果在目标检测算法中的应用进行了验证性分析.     

Detrended fluctuation analysis of EEG as a measure of depth of anesthesia

For several decades, a number of methods have been developed for the noninvasive assessment of the level of consciousness during general anesthesia. In this paper, detrended fluctuation analysis is used to study the scaling behavior of the electroencephalogram as a measure of the level of consciousness. Three indexes are proposed in order to characterize the patient state. Statistical analysis demonstrates that they allow significant discrimination between the awake, sedated and anesthetized states. Two of them present a good correlation with established indexes of depth of anesthesia. The scaling behavior has been found related to the depth of anesthesia and the methodology allows real-time implementation, which enables its application in monitoring devices.     

VEGF165基因修饰的神经干细胞对脑外伤大鼠的神经保护作用及机制

目的：探讨移植转染pDsVEGF165Redl-N1质粒的神经干细胞对脑外伤大鼠的神经保护作用及机制。方法：由新生大鼠脑组织分离培养神经干细胞,应用Lipofectamine2000介导pDsVEGF16sRed1-N1质粒转染神经干细胞;分别将PBS（A组）、神经干细胞（B组）、转基因神经干细胞（C组）移植到脑外伤大鼠局部损伤灶边缘;利用ELISA法检测转基因细胞在体内的表达情况,以免疫组化检测移植后局部损伤组织中微血管密度变化,通过NSS评分评价移植后大鼠神经功能的变化。结果：转基因细胞移植后在一定时间内持续表达VEGFl65,C组大鼠NSS评分从移植后第3天开始明显低于A组（P〈0．05）,而B组大鼠NSS评分则从移植后第7天开始明显低于A组（P〈0．05）,C组大鼠微血管密度从移植后第7天开始明显高于其他两组（P〈0．01）。结论：转基因神经干细胞表达的VEGF165既可以通过促进微血管再生和改善微循环发挥保护作用又可以直接作用于神经细胞发挥保护作用。     

Interpretation of approximate entropy: analysis of intracranial pressure approximate entropy during acute intracranial hypertension

We studied changes in intracranial pressure (ICP) complexity, estimated by the approximate entropy (ApEn) of the ICP signal, as subjects progressed from a state of normal ICP (< 20-25 mmHg) to acutely elevated ICP (an ICP "spike" defined as ICP > 25 mmHg for < or = 5 min). We hypothesized that the measures of intracranial pressure (ICP) complexity and irregularity would decrease during acute elevations in ICP. To test this hypothesis we studied ICP spikes in pediatric subjects with severe traumatic brain injury (TBI). We conclude that decreased complexity of ICP coincides with episodes of intracranial hypertension (ICH) in TBI. This suggests that the complex regulatory mechanisms that govern intracranial pressure are disrupted during acute rises in ICP. Furthermore, we carried out a series of experiments where ApEn was used to analyze synthetic signals of different characteristics with the objective of gaining a better understanding of ApEn itself, especially its interpretation in biomedical signal analysis.     

颅脑损伤后大脑胆硷酯酶变化的电镜观察

颅脑损伤易造成病人死亡及后遗症 ,临床上依据症状及客观检测进行诊断 ,法医学则难以判断颅脑损伤的程度和时间 ,这是近年来法医临床鉴定急待解决的问题 [1] ,胆硷酯酶 ( Acetylcholinesterase,Ach E)是中枢神经系的标志酶 ,是胆硷能神经元的神经递质 ,本研究采用胆硷酯酶的电镜组织细胞化学方法 [2 ] ,对大鼠颅脑损伤后不同时间内的损伤大脑的胆硷酯酶活性分布变化进行了电镜观察。材料与方法　实验动物用 5 0只 Wistar大鼠 ,体重 2 5 0 g,随机分组为实验组 (损伤组 ) 35只 ,对照组 (无损伤组 ) 1 5只。实验组大鼠制作颅脑损伤模型 ,将大…     

Nonlinear analysis of cerebral hemodynamic and intracranial pressure signals for characterization of autoregulation

The objective of this study was to determine whether or not the underlying physiological systems that generates spontaneous arterial blood pressure (ABP), cerebral blood flow velocity (CBFV), and intracranial pressure signals could be adequately approximated as a linear stochastic process. Furthermore, a new measure (C) capable of capturing the degree of nonlinear dependency between two ABP and CBFV signals (including a time-varying situation) was proposed for quantifying the degree of cerebral blood flow autoregulation. A surrogate data test of fifteen ABP, CBFV, and intracranial pressure (ICP) segments was conducted for detecting whether there exists a statistically significant deviation from the null hypothesis of linear signals. The extension of the established block computation method of C measure to an adaptive one was achieved. This new algorithm was then applied to study the C evolution using brain injury patients data from a hyperventilation study and two propofol studies. Nonlinearity has not been detected for all the fifteen recordings, neither has nonlinear dependency between CBFV and ABP. However, their presences in some of the signal segments justified the adoption of a nonlinear measure of dependency capable of characterizing both linear and nonlinear correlations for inferring autoregulation status. C measure started to decrease with the introduction of hypocapnia state indicating that hyperventilation may reduce the dependency of CBFV on ABP fluctuations. On the other hand, complex patterns of C measure evolution were observed among 14 cases of propofol data indicating a nontrivial effect of propofol on the dependency of CBFV on ABP.     

纳洛酮对大鼠中重度创伤性脑损伤后细胞免疫功能影响的实验研究

目的：通过观察大鼠创伤性脑损伤（traumatic brain injury,TBI）后纳洛酮治疗前后血浆β-EP、CD4＋、CD8＋和IL-2的动态变化,探讨纳洛酮对大鼠TBI后细胞免疫功能变化的影响及作用机制。方法：采用气体冲击致大鼠中重度脑损伤模型;流式细胞术、RIA、ELISA检测血液中CD4＋、CD8＋、β-EP、IL-2的变化。结果：TBI大鼠经纳洛酮治疗后,血浆中CD4＋和IL-2含量升高,β-EP和CD8＋则降低。大、小剂量纳洛酮治疗在相应时间点比较有显著性差异（P〈0.05）。结论：纳洛酮可通过降低TBI大鼠血浆中β-EP,调节TBI后应激紊乱,竞争性抑制β-EP对免疫细胞受体的作用,从而使CD4＋、CD8＋和IL-2水平趋于正常,恢复免疫平衡,起到治疗与保护作用。     

Phantom model of physiologic intracranial pressure and cerebrospinal fluid dynamics

We describe herein a novel life-size phantom model of the intracranial cavity and its validation. The cerebrospinal fluid (CSF) domains including ventricular, cysternal, and subarachnoid spaces were derived via magnetic resonance imaging. Brain mechanical properties and cranio-spinal compliance were set based on published data. Both bulk and pulsatile physiologic CSF flow were modeled. Model validation was carried out by comparisons of flow and pressure measurements in the phantom with published in vivo data of healthy subjects. Physiologic intracranial pressure with 10 mmHg mean and 0.4 mmHg peak pulse amplitude was recorded in the ventricles. Peak CSF flow rates of 0.2 and 2 ml/s were measured in the cerebral aqueduct and subarachnoid space, respectively. The phantom constitutes a first-of-its-kind approach to modeling physiologic intracranial dynamics in vitro. Herein, we describe the phantom design and manufacturing, definition and implementation of its operating parameters, as well as the validation of the modeled dynamics.     

Cerebrovascular mechanical properties and slow waves of intracranial pressure in TBI patients

Myogenic autoregulation of cerebral blood flow is one of the mechanisms affecting cerebral hemodynamics. Short or long-lasting changes in intracranial pressure (ICP) are believed to reveal the responses of the cerebral system to myogenic stimuli. Through the incorporation of a theoretical model into the experimental measurements of cerebrovascular distensibility and compliance in patients with traumatic brain injury (TBI), the current study is an attempt to explain ICP dynamics in either presence or absence of cerebral autoregulation. The pulse wave velocity and transfer function between arterial blood pressure and ICP were utilized as the major tools to reflect variations in the mechanical properties of distant cerebral artries/arteriols. The results imply that different states of cerebral autoregulation and associated regimes within the cerebrovascular system can lead to different types of interrelationship between the slow variations of ICP, cerebral arterial distensibility, and compliance. Consequently, each of these classes may require different types of treatment on patients with TBI.     

参数浮动下低功耗多米诺门的蒙特卡罗分析

Using the multiple-parameter Monte Carlo method, the effectiveness of the dual threshold voltage technique （DTV） in low power domino logic design is analyzed. Simulation results indicate that under significant temperature and process fluctuations, DTV is still highly effective in reducing the total leakage and active power consumption for domino gates with speed loss. Also, regarding power and delay characteristics, different structure domino gates with DTV have different robustness against temperature and process fluctuation.     

An analysis of process fluctuation induced propagation delay variation using analytical model

The parametric yield of VLSI depends strongly on the statistical process fluctuations. Using an analytical model, this paper analyzes the relations between process fluctuations and circuit performance variations, namely, process-to-device and device-to-circuit response surfaces.It is found that the worst-cases for the channel length L, the gate insulator thickness t_ox, and the channel impurity concentration N_chn corresponded to those for the ring oscillator propagation delay τ_pd when the drain current was estimated using the saturation velocity v_sat, since the response surfaces for L-to-τ_pd, τ_ox-to-τ_pd and N_chn-to-τ_pd were monotonic. The fluctuations of L resulted in a lower tail of the distribution of the NMOS threshold voltage V_thn due to the short-channel effect and a higher tail of the drain saturation current I_dn. However, the distribution of τ_pd was nearly normal, as the probability of the normal distribution (the P-value) was greater than 5%. This is because the influence of L on τ_pd was mainly due to the gate capacitance C_g. Also, the non-linear relation between L and V_thn was cancelled by the non-linear I_dn-to-τ_pd response surface.     

Monte Carlo analysis of a low power domino gate under parameter fluctuation

Using the multiple-parameter Monte Carlo method, the effectiveness of the dual threshold voltage technique (DTV) in low power domino logic design is analyzed. Simulation results indicate that under significant temperature and process fluctuations, DTV is still highly effective in reducing the total leakage and active power consumption for domino gates with speed loss. Also, regarding power and delay characteristics, different structure domino gates with DTV have different robustness against temperature and process fluctuation.     

Detection of loss of cerebral vascular tone by correlation ofarterial and intracranial pressure signals

With the use of a laboratory model, arterial and intracranial pressure signals were obtained under conditions of intact regulation of cerebral blood flow and massive dilation. During elevated intracranial pressure and intact regulation, positive pressure inhalation appears to briefly occlude venous flow into the cranial sinuses during inspiration. As a result, the intracranial pressure and arterial pressure signals are not similar. In contrast, when maximal dilation causes failure of regulation of cerebral blood flow, the intracranial pressure signal is approximately proportional to the arterial pressure signal. Comparison of the cross-correlation function derived from the intracranial and arterial pressure signals to the autocorrelation function of the arterial signal reveals that the two correlation functions are: (1) different during intact regulation and (2) nearly identical during dilation induced failure of regulation of cerebral blood flow     

儿童血友病患者口腔外伤性出血的回顾性分析

目的:回顾性分析儿童血友病患者并发口腔外伤出血的临床特点、治疗方案,为指导该类疾病的诊断治疗提供科学依据.方法:分析我院因口腔外伤(包括舌损伤、上下唇裂伤、唇舌系带裂伤等)出血同时患血友病的住院儿童44人次,年龄9月至10岁3月,分析其就诊原因、发病特点、实验室检查情况及病情发展等临床特点及治疗方法和疗效等,并进行归纳总结.结果:1.患儿均因口腔外伤出血为主诉,其中入院时已确诊血友病者31例；2.患儿多数为陈旧性伤口,有的经多次清创缝合,因慢性失血,实验室检查多数有贫血(入院时或入院后几天加重),且均有活化部分凝血活酶时间(activated partial thromboplastin time,APTT)延长；3.入院前已确诊为血友病者经针对性治疗,疗效好；4.全身治疗加彻底的清创缝合疗效好,单纯一种手段效果差,患儿反复入院几率高.结论:儿童血友病伴发口腔外伤出血时,应尽早明确病因,补充凝血因子、纠正贫血,同时必须尽早、彻底地对伤口进行清创缝合才能取得好的疗效.     

Comparison of detrended fluctuation analysis and spectral analysis for heart rate variability in sleep and sleep apnea

Sleep has been regarded as a testing situation for the autonomic nervous system, because its activity is modulated by sleep stages. Sleep-related breathing disorders also influence the autonomic nervous system and can cause heart rate changes known as cyclical variation. We investigated the effect of sleep stages and sleep apnea on autonomic activity by analyzing heart rate variability (HRV). Since spectral analysis is suited for the identification of cyclical variations and detrended fluctuation analysis can analyze the scaling behavior and detect long-range correlations, we compared the results of both complementary techniques in 14 healthy subjects, 33 patients with moderate, and 31 patients with severe sleep apnea. The spectral parameters VLF, LF, HF, and LF/HF confirmed increasing parasympathetic activity from wakefulness and REM over light sleep to deep sleep, which is reduced in patients with sleep apnea. Discriminance analysis was used on a person and sleep stage basis to determine the best method for the separation of sleep stages and sleep apnea severity. Using spectral parameters 69.7% of the apnea severity assignments and 54.6% of the sleep stage assignments were correct, while using scaling analysis these numbers increased to 74.4% and 85.0%, respectively. We conclude that changes in HRV are better quantified by scaling analysis than by spectral analysis.     

A large-scale, energetic model of cardiovascular homeostasis predicts dynamics of arterial pressure in humans.

The energetic balance of forces in the cardiovascular system is vital to the stability of blood flow to all physiological systems in mammals. Yet, a large-scale, theoretical model, summarizing the energetic balance of major forces in a single, mathematically closed system has not been described. Although a number of computer simulations have been successfully performed with the use of analog models, the analysis of energetic balance of forces in such models is obscured by a big number of interacting elements. Hence, the goal of our study was to develop a theoretical model that represents large-scale, energetic balance in the cardiovascular system, including the energies of arterial pressure wave, blood flow, and the smooth muscle tone of arterial walls. Because the emphasis of our study was on tracking beat-to-beat changes in the balance of forces, we used a simplified representation of the blood pressure wave as a trapezoidal pressure-pulse with a strong-discontinuity leading front. This allowed significant reduction in the number of required parameters. Our approach has been validated using theoretical analysis, and its accuracy has been confirmed experimentally. The model predicted the dynamics of arterial pressure in human subjects undergoing physiological tests and provided insights into the relationships between arterial pressure and pressure wave velocity.     

Development of intracranial brain-computer interface system using non-motor brain area for series of motor functions

An intracranial brain-computer interface (BCI) system using the neuronal activity of a non-motor brain area to fulfil a series of motor functions has been developed. The presented BCI system encodes a series of motor functions into a small number of neuronal units of the primary somatosensory cortex of a rat and generates real-time command signals to control a machine according to the animal's motor intentions. The results of this study demonstrate the practical usability of the BCI system using a non-motor brain area in the field of rehabilitation.     

Intracranial pressure dynamics in patients with acute brain damage:a critical analysis with the aid of a mathematical model

The time pattern of intracranial pressure (ICP) in response to typical clinical tests (i.e., bolus injection and bolus withdrawal of 1 to 4 mL of saline in the craniospinal space) was studied in 18 patients with acute brain damage by means of a mathematical model. The model includes the main biomechanical factors assumed to affect intracranial pressure, particularly cerebrospinal fluid (CSF) dynamics, intracranial compliance, and cerebral hemodynamics. Best fitting between model simulation curves and clinical tracings was achieved using the Powell minimization algorithm and a least-square criterion function. The simulation results demonstrate that, in most patients, the ICP time pattern cannot be explained merely on the basis of CSF dynamics but also requires consideration of the contribution of cerebral hemodynamics and blood volume alterations. In particular, only in a few patients (about 40% of total) the ICP monotonically returns toward baseline following the clinical maneuver. In most of the examined cases (about 60%), ICP exhibits an anomalous response to the same maneuver, characterized by a delayed increase after bolus injection and a delayed decrease after withdrawal. The model is able to explain these responses, imputing them to active intracranial blood volume changes induced by mechanisms controlling cerebral blood flow. Finally, the role of the main intracranial biomechanical parameters in the genesis of the ICP time pattern is discussed and a comparison with previous theoretical studies performed