动脉瘤性蛛网膜下腔出血后并发脑性盐耗损综合征诊治体会

目的探讨动脉瘤性蛛网膜下腔出血后并发脑性盐耗损综合征的临床诊治。方法对36例动脉瘤性蛛网膜下腔出血后并发脑性盐耗损综合征患者的临床资料进行回顾性分析,对所有患者进行血钠、尿钠检测,同时通过中心静脉压(CVP)及血浆渗透压对血容量进行评估。结果 36例患者低血钠症状均消失,治疗时间为3~11 d,平均(6.16±2.08)d;意识状态好转治疗时间为2~7 d,平均(5.21±1.86)d;所有患者CVP范围2~5 cmH2O,平均(3.50±2.08)cmH2O;血浆渗透压范围281.45~332.14 mmol/L,平均(304.65±12.26)mmol/L;治疗时间与治疗前血清钠、24 h尿钠和CVP均不存在直线相关关系(P=0.36、0.13、0.12);所有患者均未出现不良反应。结论 CVP和血浆渗透压是诊断动脉瘤性蛛网膜下腔出血后并发脑性盐耗损综合征的一种重要方法,同时对治疗也有指导意义。

老年颅脑损伤后脑性盐耗损综合征

目的 探讨老年急性颅脑损伤脑性盐耗损综合征的诊断及治疗。方法 回顾分析 2 1例 6 0岁以上老年颅脑损伤后脑性盐耗损综合征 (CSWS)的临床表现、实验室检查和诊治方法。结果 除早期的 3例死于脑水肿和脑梗塞外 ,其余18例水电解质代谢紊乱均得到纠正。结论 低血钠、低血容量、高尿钠、高尿量、高比重尿 (二低三高 )是CSWS的诊断依据 ,补高渗盐水和水化治疗是行之有效的方法。

老年颅脑损伤后脑性盐耗损综合征21例处理体会

颅脑外伤后有时可发生脑性盐耗损综合征(cerebral salt wasting syndrome,CSWS),因其临床表现及实验室检查与抗利尿激素不适当分泌综合征(SIADH)相似,对老年病人极易引起临床医生误诊误治。本文报告我科1995年至2000年5月收治的21例老年脑外伤CSWS的诊治体会。

以可靠性为中心定量确定预防性维修周期的新模型

阐述耗损性机电部件和冗余部件预防检测维修的必要性和可能性,阐述了同一部件用于不同任务剖面的不同检测更换期,以及不同性质的耗损性的不同处理方式,提出了从可靠性要求确定不同任务剖面、不同耗损性部件预防检测或更换周期的新模型。

神经外科低钠性意识障碍的诊疗探讨

目的:探讨神经外科病人低钠性意识障碍的病因、诊断及治疗。方法:回顾分析15例低钠性意识障碍病人的临床表现、实验室资料及治疗效果。结果:营养不良性低钠9例,CSWS5例,SIADH1例。营养不良性低钠及CSWS病人经补钠、补液,而SIADH病人经限水、限钠治疗,意识障碍均短时间恢复或好转。结论:神经外科低钠性意识障碍由不同病因引起,但多由营养不良性缺钠所致。治疗应根据不同病因采取不同的治疗措施。

基于故障行为模型的产品寿命分析方法

针对传统可靠性工程方法无法满足高可靠长寿命需求产品设计与分析要求的现状。本文充分考虑引起产品寿命分散性的内因和外因的不确定性,在产品功能模型或数字样机模型的基础上,结合产品的故障行为模型,建立了一种基于产品故障行为模型的产品寿命分析方法。在该方法中,内因参数与外因参数的分散性分别可以用相应的概率密度函数来表示,都是通过对实际使用情况和生产条件的估计得到的,因此,按照这种方法评估得到的产品寿命特征,能够弥补基于故障物理的可靠性预计方法无法体现产品正常使用条件的不足。

电子产品的寿命设计与管理

本文介绍了电子产品寿命的相关概念,并从产品管理和产品设计实现的角度探讨了如何进行产品的寿命设计与管理。

On-body propagation characterization based on FDTD method for 2.4/5.2/5.7 GHz wearable body sensor networks

The on-body path loss and time delay of radio propagation in 2. 4/5.2/5.7 GHz wearable body sensor networks （W-BSN） are studied using Remcom XFDTD, a simulation tool based on the finite-difference time- domain method. The simulation is performed in the environment of free space with a simplified three- dimensional human body model. Results show that the path loss at a higher radio frequency is significantly smaller. Given that the transmitter and the receiver are located on the body trunk, the path loss relevant to the proposed minimum equivalent surface distance follows a log-fitting parametric model, and the path loss exponents are 4. 7, 4. 1 and 4. 0 at frequencies of 2. 4, 5.2, 5.7 GHz, respectively. On the other hand, the first- arrival delays are less than 2 ns at all receivers, and the maximum time delay spread is about 10 ns. As suggested by the maximum time delay spread, transmission rates of W-BSN must be less than 10^8 symbol/s to avoid intersymbol interference from multiple-path delay.

鞍区肿瘤术后脑性盐耗损综合征的观察与护理

鞍区肿瘤术后由于垂体功能紊乱，常发生电解质紊乱，造成严重的临床综合症状，一旦发生脑性盐耗损综合症更为突出。因其与脑水肿症状相似，易于混淆。如果不早期发现，早期治疗，易造成病情急剧恶化，甚至造成不可逆的后果。现将鞍区肿瘤术后脑性盐耗损综合症的观察与护理总结如下。

对热力学第二定律的解析

热力学第二定律是热力学的基本定律之一，它是关于在有限空间和有限时间内，一切和热运动有关的物理、化学过程具有不可逆性的总结．同学们对热力学第二定律的理解有些困难，现从以下几个方面举例分析．

金属矿山机械设备常见故障及使用维修建议

金属矿山机械设备的应用,不仅提高了金属矿山的开采效率,增加了金属矿业单位的经济收入,有效提高了金属矿山开采工作的安全性。但是金属矿山机械设备工作环境恶劣,长期连续运行,经常会出现一些机械故障。本文针对矿山机械设备故障特点进行了分析总结,根据检测方式提出了科学有效的检测方法。

Influences of polishing on return loss of optical fiber connectors

With Al2O3 and SiO2 as polishing medium, under different polishing conditions, e.g. with different polishing pressure, polishing time and polishing fluid, the influences of polishing treatment on the return loss of optical fiber connectors were investigated. The return loss of optical fiber connectors is 32CD*238dB before polishing. The results show that dry polishing（i.e. no polishing fluid） with Al2O3 has less influence on return loss of optical fiber connectors, while dry polishing with SiO2 reduces return loss to about 20dB because of the end-face of optical fiber contaminated. The wet polishing（i.e. using distilled water as polishing fluid） with Al2O3 or SiO2 can increase return loss to 45CD*250dB, but wet polishing with Al2O3 may produce optical fiber undercut depth of 80CD*2140nm. Wet polishing with SiO2 should be preferentially selected for optical fiber connectors and polishing time should be controlled within 20CD*230s.

Coherence Loss of Two-Photon Jaynes-Cummings Model in Dispersive Approximation

Completely solving the dissipative dynamics of nonlinear Jaynes-Cumming model is a very difficult task.In our recent work (Phys. Lett. A284 (2001) 156), we just obtained analytical results of the field dissipative dynamicsof the nonlinear JCM. In the present paper, employing the perturbative expansion of master equation, we obtain thedensity operator of the system (field +atom). The coherence losses of the system and of the atom are investigated whentwo-photon process is involved. We also study the effect of different atomic initial states and the influence of the fieldamplitude on the atomic coherence loss.

The effects of fluid loss on physical performance： A critical review

Purpose： The purpose of this review was to critically analyse the cun;ent evidence investigating the effect of an athlete＇s hydration status on physical performance. Methods： A literature search of multiple databases was used to identify studies that met the inclusion criteria for this review. The included studies were then critically appraised using the Downs and Black protocol. Results： Nine articles were found to meet the inclusion criteria, with an average score of 79% for methodological quality representative of a ＂high＂ standard of research. Conclusion： The evidence suggests that dehydration has a negative impact on physical performance for activities lasting more than 30 s in duration. However dehydration was found to have no significant impact on physical performance for activities lasting less than 15 s in duration.

Study of multi-band property of rectangular microstrip patch antenna having different numbers of wide slots

The property of multi-band operation has been studied and investigated analytically through the design of a rectangular patch microstrip antenna having different numbers of wide slots arranged at both the radiating edges. The analyses were carried out using the method of moments simulation software. It is shown that a patch with three slots has a multi-band feature with four resonant frequencies at 1.6, 1.8, 2.65, and 4.83 GHz and adequate values of return loss and gain. It is also shown that a patch with two pairs of wide slots arranged at both the radiating edges has the dual band feature with resonant frequencies at 1.64 and 1.8 GHz and good values of return loss and gain.

Radio Channel Measurements and Analysis at 2.4/5GHz in Subway Tunnels

There is an increasing demand on wireless communications in subway tunnels to provide video surveillance and sensory data for security,maintenance and train control,and to offer various communication or entertainment services(e.g.,Internet,etc.) to passengers as well.The wireless channel in tunnels is quite unique due to the confined space and the waveguide effects.Therefore,modeling the radio channel characteristics in tunnels is critically important for communication systems design or optimization.This paper investigates the key radio channel characteristics of a subway tunnel at 2.4 GHz and 5 GHz,such as the path loss,root mean square(RMS) delay spread,channel stationarity,Doppler shift,and channel capacity.The field measurements show that channel characteristics in tunnels are highly location-dependent and there exist abundant components in Doppler shift domain.In the straight section of the subway tunnel,the measured path loss exponents are close to1.6,lower than that in free space.

Dielectric Properties of Fe73.5-Cu1-Ta3-Si13.5-B9 Magnetic Alloy

The studied sample is a metallic glass in Fe-Si-B system. It is developed with the nominal composition of Fe735-Cu1-Ta3-Si13.5-B9 by single-roller melt spinning technique in air. The dielectric constant and loss factor have been measured both for as cast and annealed samples using Agilent Impedance analyzer. They are found to decrease with frequency up to 10 MHz and remain constant afterwards. The decrease of dielectric constant and loss factor with frequency is due to ceasing of orientational polarizability. Their constancy is owing to presence of only electronic contribution to its polarizability above 10 MHz. Three distinct regions （1-4 MHz, 4-10 MHz and 10 MHz-1 GHz） also noticed from its frequency dependence, which might make it useful in switching and sensor devices. The temperature dependence of dielectric constant and loss factor maintain inverse relationship： （1） dielectric constant increases, and （2） loss factor decreases with annealing temperature for structural relaxation due to thermal agitation.

Preparation and characterization of Mg-doped CaCu_(3)Ti_(4)O_(12) thin films

Mg-doped CaCu_(3-x)Mg_(x)Ti_(4)O_(12)(x=0,0.05,0.1,0.15,0.2,at.%)thin films were prepared by a modified sol−gel method.A comparative study on the microstructure and electrical properties of Mg-doped CaCu_(3)Ti_(4)O_(12)(CCTO)thin films was carried out.The grain sizes of the Mg-doped CCTO thin films were smaller in comparison to the undoped CCTO films.Furthermore,compared to undoped CCTO films,Mg-doped CCTO thin films obtained higher dielectric constant as well as excellent frequency stability.Meanwhile,Mg doping could reduce the dielectric loss of CCTO thin films in the frequency range of 104−106 Hz.The results showed that the Mg-doped CCTO thin films had the better electrical characteristics compared with the undoped CCTO films.The nonlinear coefficient of Mg-doped CCTO thin films at x=0.15 and x=0.1 was improved to 7.4 and 6.0,respectively.

Heating and Life Problem of High Power Density Induction Motor

An induction motor with its speed modulated by frequency features wide transfer speed range, high systematie efficiency, simple structure and long life, and it therefore becomes one of the best driving motors used in electrical vehicles. The present research trend of it is high power, high speed, high efficiency and long life. How to meet the above requirements by using the electromagnetic design, structure design and beat design, becomes a matter that needs to be resolved now. In this paper, the characters of the motor in operation are analyzed, all kinds of factors that relate to life are laid out, its heating and loss are discussed and analyzed. The key reasons affecting the motor life are presented, and different characters of a high induction motor are compared with these of a general induction motor. A design idea is described, that is : we should consider how to improve the efficiency and reliability as well as bow to reduce the heating by changing the electromagnet, structure, dissipation and operation of the motor. How to reduce its losses and to improve its dissipation has been presented in the paper.