Mobile-phone pulse triggers evoked potentials

If mobile-phone electromagnetic fields (EMFs) are hazardous, as suggested in the literature, processes or mechanisms must exist that allow the body to detect the fields. We hypothesized that the low-frequency pulses produced by mobile phones (217 Hz) were detected by sensory transduction, as evidenced by the ability of the pulses to trigger evoked potentials (EPs). Electroencephalograms (EEGs) were recorded from six standard locations in 20 volunteers and analyzed to detect brain potentials triggered by a pulse of the type produced by mobile phones. Evoked potentials having the expected latency were found in 90% of the volunteers, as assessed using a nonlinear method of EEG analysis. Evoked potentials were not detected when the EEG was analyzed using time averaging. The possibility of systematic error was excluded by sham-exposure analyses. The results implied that mobile-phones trigger EP at the rate of 217 Hz during ordinary phone use. Chronic production of the changes in brain activity might be pertinent to the reports of health hazards among mobile-phone users.     

基于光学相干层析离体牙图像的去噪算法研究

目的光学相干层析成像因其高分辨率、无损等优点,适于早期龋检测;但由于系统中存在的噪声,影响其成像质量。为了重建牙齿的原貌信息,需寻找一种适于早期龋检测的光学相干层析成像实时图像去噪算法。方法比较平均曲率流滤波、非线性扩散拉普拉斯金字塔算法、非局部均值滤波3种滤波方法对光学相干层析人离体牙图像的去噪效果,从噪声抑制、边界保持、运算时间3方面分析上述3种算法的实时去噪性能及其优缺点。结果非局部均值滤波在噪声抑制和边界保持2个方面能达到很好的平衡,但实时性差;而非线性扩散拉普拉斯金字塔算法则能在滤波效果和运算效率达到较好的平衡;平均曲率流滤波次之。结论非线性扩散拉普拉斯金字塔算法较适于早期龋检测的光学相干层析成像实时图像去噪。     

Quantitative Relations between Outer Hair Cell Electromotility and Nonlinear Capacitance

The electrically evoked somatic motility of outer hair cells (OHC), briefly termed OHC electromotility, plays a crucial role in cochlear amplification that underlies the remarkably high sensitivity and frequency selectivity of the mammalian hearing. Accompanying OHC electromotility is a voltage-dependent gating charge movement within the cell lateral membrane, manifested as a measurable nonlinear capacitance (NLC) in OHCs. The electromotility and NLC of OHCs are highly correlated by sharing a common molecular substrate, the motor protein prestin. In this study, we systematically characterized the quantitative relationship between OHC electromotility and NLC in their voltage dependences for the purpose of further understanding the electromechanical transduction in OHCs. The results demonstrated that the two possess differing voltage dependences with the V1/2 of electromotility consistently being ～20 mV depolarized in comparison with that of NLC although their slope factors α are statistically identical. Further investigations showed that the initial state of OHCs influences the voltage dependence of electromotility but not that of NLC, indicating that some biophysical factors other than the motor protein per se are involved in the process of OHC length changes. We proposed that the cytoskeletal spectrin-actin framework underneath the OHC plasma membrane and the cell’s turgor are the two most probable factors that cause the voltage-dependence discrepancy between OHC electromotility and NLC.     

Shock-Induced Heating and Millisecond Boiling in Gels and Tissue Due to High Intensity Focused Ultrasound

Nonlinear propagation causes high-intensity ultrasound waves to distort and generate higher harmonics, which are more readily absorbed and converted to heat than the fundamental frequency. Although such nonlinear effects have been investigated previously and found to not significantly alter high-intensity focused ultrasound (HIFU) treatments, two results reported here change this paradigm. One is that at clinically relevant intensity levels, HIFU waves not only become distorted but form shock waves in tissue. The other is that the generated shock waves heat the tissue to boiling in much less time than predicted for undistorted or weakly distorted waves. In this study, a 2-MHz HIFU source operating at peak intensities up to 25,000 W/cm² was used to heat transparent tissue-mimicking phantoms and ex vivo bovine liver samples. Initiation of boiling was detected using high-speed photography, a 20-MHz passive cavitation detector and fluctuation of the drive voltage at the HIFU source. The time to boil obtained experimentally was used to quantify heating rates and was compared with calculations using weak shock theory and the shock amplitudes obtained from nonlinear modeling and measurements with a fiber optic hydrophone. As observed experimentally and predicted by calculations, shocked focal waveforms produced boiling in as little as 3 ms and the time to initiate boiling was sensitive to small changes in HIFU output. Nonlinear heating as a result of shock waves is therefore important to HIFU, and clinicians should be aware of the potential for very rapid boiling because it alters treatments. (E-mail: mcanney@u.washington.edu).     

精神分裂症脑电分析技术研究的进展

讨论了精神分裂症脑电分析技术,包括脑电图,脑诱发电位和脑电地形图在人的几种主要技术的研究进展和应用现状,并对其应用前景做了展望。     

Nonlinear analyses of heart rate variability in normal and growth-restricted fetuses

BACKGROUND: Many studies on the physiology of the cardiovascular system reported that nonlinear chaotic dynamics may govern the generation of the heart rate signal. OBJECTIVE: To examine whether the heart rate dynamics of an intrauterine growth restricted (IUGR) fetus is different from a healthy normal fetus by nonlinear methods of time series analysis. DESIGN OF THE STUDY: One hundred nineteen fetal heart rate (FHR) recordings from healthy normal fetuses, and 69 recordings from IUGR fetuses were analyzed. Nonlinear analyses included attractor reconstruction, calculation of the largest Lyapunov exponents using the Wolf algorithm, and estimation of correlation dimension. The largest Lyapunov exponents from normal fetuses were checked by means of surrogate-data test. RESULTS: Abnormal FHR patterns of IUGR fetuses such as decreased variability and repetitive late decelerations presented a remarkably different structure in the reconstructed attractor. Surrogate data suggest that the FHR of healthy normal fetuses has unique nonlinear characteristics. The largest Lyapunov exponents were positive for all of 119 healthy normal fetuses, indicating that the FHR control system is sensitive to initial conditions. The values of IUGR fetuses were significantly lower than those of normal subjects. In normal fetuses, significant changes of correlation dimension according to gestational age were observed. In IUGR fetuses, however, such changes were not found. CONCLUSIONS: The heart rate dynamics of IUGR fetuses is less chaotic than that of normal fetuses. Decreased system complexity suggested by correlation dimension may limit the IUGR fetuses' ability to maintain cardiovascular integrity, and therefore, to adapt to the variety of internal and external cardiovascular stresses.     

非线性回归的线性拟合加权最小二乘估计

目的探讨非线性回归的线性化拟合技术，改善线性化技术对非线性回归的拟合效果。方法通过设立适当的权重，采用加权最小二乘法对非线性回归的线性化方程进行拟合。结果在讨论非线性模型与相应的直线化模型误差间关系的基础上，导出了利用线性化方程进行加权最小二乘估计的权重，使得利用加权最小二乘估计得到的模型参数的估计误差近似于直接对非线性模型进行估计得到的估计误差，建立了非线性回归的加权线性化拟合技术。结论非线性回归的加权线性化拟合技术能较好地改善线性化技术对非线性回归的估计效果。     

非线性动力学在脑神经系统研究中的应用

采集一组脑电数据，利用3种非线性动力学算法对数据进行性分析，通过对结果的分析展望了非线性动力学方法在研究脑神经系统方面的应用前景。     

吗替麦考酚酯在原发性肾病综合征患者中的群体药动学研究

目的：研究吗替麦考酚酯在原发性肾病综合征患者中的群体药动学模型,为临床个体化用药提供参考。方法选取2011年1月~2014年2月期间我院收治的56例原发性肾病综合征患者作为本组研究的观察对象,所有患者在给予吗替麦考酚酯对症治疗后,采集其血液样本,通过非线性混合效应模型构建出麦考酚酯的群体药动学模型,从而探讨患者的年龄、性别、身高、体重、剂量、血清肌酐、治疗时间等对药动学参数的影响。结果药动学基本模型采用一级吸收和消除的二房室模型最为有效;患者体重与治疗时间是吗替麦考酚酯清除率的主要因素;最终群体药动学模型为：清除率=0.476×体重×(1-e-1.17POD)。结论吗替麦考酚酯在原发性肾病综合征患者中的药动学模型具有明显的代表性,为个体化给药方案的确定提供依据。     

Redefining 3Dimensional placental membrane microarchitecture using multiphoton microscopy and optical clearing

IntroductionRemodeling of human placental membranes (amniochorionic or fetalmembrane) throughout gestation, a necessity to accommodate increasing uterine volume, involves continuous alterations (replacement of cells and remodeling of extracellular matrix). Methodologic limitations have obscured microscopic determination of cellular and layer-level alterations. This study used a combination of advanced imaging by multiphoton autofluorescence microscopy (MPAM) and second harmonic generation (SHG) microscopy along with tissue optical clearing to characterize the 3Dimensional multilayer organization of placental membranes.MethodsPlacental membranes biopsies (6 mm) collected from term, not-in-labor cesarean deliveries (n = 7) were fixed in 10% formalin (native) or treated with 2,2′-thiodiethanol to render them transparent for deeper imaging. Native and cleared tissues were imaged using MPAM (cellular autofluorescence) and SHG (fibrillar collagen). Depth z-stacks captured the amnion epithelium, underlying matrix layers, and in the cleared biopsies, the decidua layer.ResultsMPAM and SHG revealed fetal membrane epithelial topography and collagen organization in multiple matrix layers. Term amnion layers showed epithelial shedding and gaps. Optical clearing provided full-depth imaging with improved visualization of collagen structure, mesenchymal cells in extracellular matrix layers, and decidua morphology. Layer thicknesses measured by imaging corroborated with histology. Mosaic tiling of MPAM/SHG image stacks allowed large area visualization of entire biopsies.ConclusionMPAM-SHG microscopy allowed for study of this multi-layered tissue and revealed shedding, gap formation, and other structural changes. This approach could be used to study structural changes associated with membranes as well as other uterine tissues to better understand events in normal and abnormal parturition.