An evolution of pulse speed in arteries

In this work, treating the artery as a thick-walled cylindrical shell made of an incompressible, isotropic and elastic solid, utilizing the large deformation theory and the stress-strain relation proposed by Demiray (1976b, Trans. ASME Ser. E, J. Appl. Mech., 98, 194-197), an explicit expression for the pulse speed is obtained and the effect of lumen pressure and the axial stretch on wave speed is discussed. Numerical results indicate that the wave speed increases with lumen pressure but decreases with the axial stretch. The results of the present model are compared with our previous work (Demiray, 1988, J. Biomech. 21, 55-58) on the same subject.     

小口径管材超声水膜法检测探头跟踪系统

小口径管材曲率大,超声水膜法不易应用于小口径管材检测。针对小口径管材水膜法检测的特点,设计了一种小口径管材超声水膜法检测探头跟踪系统,主要包括3套缓冲器和2套固定楔。现场测试表明,使用该系统可以很好地实现探头跟踪、耦合等功能,检测所得信号灵敏度高、稳定性好,各项指标均达到国家和行业标准。     

Standards and quality control: problems and pitfalls

The proliferation of standards and quality assurance programs is posing a major problem for mental health administrators. The authors review some of these problems and emphasize the differences between cost and quality controls. They propose that quality controls be judged on their ability to improve patient care and suggest that administrators consider the establishment of quality control offices.     

大管径超声波煤气流量计的研制

由同济大学声学研究所研制的大管径超声波煤气流量计,采用非介入式的超声波探头,直接进行煤气流理的连续在线检测,经过温度和压力的自动补偿后,其测量精度优于２％。超声波煤气流量计的最大测量管径为３０００ｍｍ。     

Evaluation of a palliative care service: problems and pitfalls

OBJECTIVE: To evaluate a palliative care home support team based on an inpatient unit. DESIGN: Randomised controlled trial with waiting list. Patients in the study group received the service immediately, those in the control group received it after one month. Main comparison point was at one month. SETTING: A city of 300,000 people with a publicly funded home care service and about 200 general practitioners, most of whom provide home care. MAIN OUTCOME MEASURES: Pain and nausea levels were measured at entry to trial and at one month, as were quality of life for patients and care givers' health. RESULTS: Because of early deaths, problems with recruitment, and a low compliance rate for completion of questionnaires, the required sample size was not attained. CONCLUSION: In designing evaluations of palliative care services, investigators should be prepared to deal with the following issues: attrition due to early death, opposition to randomisation by patients and referral sources, ethical problems raised by randomisation of dying patients, the appropriate timing of comparison points, and difficulties of collecting data from sick or exhausted patients and care givers. Investigators may choose to evaluate a service from various perspectives using different methods: controlled trials, qualitative studies, surveys, and audits. Randomised trials may prove to be impracticable for evaluation of palliative care.     

Pharmacological analysis of intracellular Ca2+ signalling: problems and pitfalls

Sexual coercion, a topic of relevance to school health personnel, may be as common in high school populations as in university populations. Twenty-one sexuality education curricula were examined for information on the topics of date rape, stranger rape, pressure, incest, sexual harassment, unwanted/inappropriate touch, and exploitation/victimization. Curricula scoring highest in total coverage also were the most comprehensive with six of the seven sexual coercion topics covered. Overall, pressure and exploitation/victimization received the greatest attention, while sexual harassment was not covered in any of the curricula. Common themes occurring within the coercion topic areas included guilt, communication/assertiveness skills, blame, drug use, premeditation, fear, sources of help. Results suggest sexuality education curricula have not responded to the increased concern regarding sexual harassment in schools.     

Performance of ultrasonic speckle tracking in various tissues

The purpose of this study was to investigate the accuracy of ultrasound speckle tracking in various tissues. Results from two-dimensional tissue speckle tracking in liver, muscle, fat, and sponge samples are presented, while keeping other speckle tracking parameters constant. Speckle tracking performance was characterized both in terms of the magnitude of tracking errors and in terms of the percentage of correctly tracked displacement vectors. Speckle tracking in muscle tissue, which contains myofibrils and significant tissue microstructure, produced the highest percentage of correctly tracked vectors and smallest tracking errors relative to other tissues.     

An instrument for ultrasonic biometry

A simple instrument has been developed for measurement of axial length and anterior chamber depth. It is pocket sized, and the digital output is easy to interpret. The long term accuracy of 0.2 mm is ideal in helping to eliminate errors of lens selection.     

Perils, pitfalls, and accomplishments of guidelines for treatment of back problems

Science should be the basis for guidelines. As a result of the Flexner Report in 1911, we now live in an era where randomized trials are available. Statistical methods can truly be applied to evaluate the reliability of data published in the literature. The result is that we can now demand more from future publications and allow for a better evaluation of the mistakes or bias that can distort validity, applicability, and reliability. The importance of this methodology is to reduce misunderstandings by patients, clinicians, manufacturers, and government agencies about issues important to patient care.     

低噪声回波测距系统的电路设计与系统分析

描述了超声波脉冲回波测距系统的基本组成,重点研究了超声波测距系统中的低噪声问题,设计了分时和分区的开关隔离式超声波发射和接收电路,彻底切断了发射电路和其他电干扰信号对接收电路的影响.低噪声\     

Non-invasive measurement of pulsatile vessel diameter change and elastic properties in human arteries: a methodological study

A recently developed ultrasound phase-locked echo-tracking system makes it possible to measure non-invasive pulsatile vessel diameter changes, and, in combination with blood-pressure measurement, to calculate pressure strain elastic modulus (Ep) and stiffness (beta). The reproducibility in measurements of pulsatile diameter changes with this system was evaluated. Also the precision of indirect blood-pressure measurements, as compared to the simultaneously measured intra-arterial blood pressure was tested. The resulting reproducibility in pressure strain elastic modulus (Ep) and stiffness (beta) was evaluated. Intra-observer variabilities in measuring pulsatile diameter changes were 16% for the abdominal aorta, 10% for the common carotid artery, and 15% for the common femoral artery, respectively. Intra-observer variabilities for Ep and beta were 21% for both in the abdominal aorta, 17% for both in the common carotid artery, and 18% for both in the common femoral artery, respectively. There were only small differences in indirect and direct measurement of systolic blood pressure, whereas indirect blood pressure measurement systematically overestimated the diastolic blood pressure, on average by 20%. The variabilities in indirect blood pressure measurements were 2% for the systolic and 3% for the diastolic blood pressure, respectively. Inter-observer variability in the investigation of the common carotid artery was 10% for the pulsatile diameter changes, and 21% and 23% for Ep and beta, respectively. Thus, the echo-tracking system represents a reliable system for estimation of pressure strain elastic modulus and stiffness. However, Ep and beta are systematically underestimated by 25-30%, when used in combination with indirect blood pressure measurements.     

An ultrasonic scalpel for laparoscopic gynecologic surgery

In order to obtain good results in laparoscopic surgery the surgeon should be well trained and experienced and the equipment perfect. The recent innovation in laparoscopic surgery is the ultrasonically activated scalpel. Scissors make the working part of scalpel with one hand vibrating 55,000 Hz in a second. The effect reflects in braking hydrogen links and denaturation of proteins in instant haemostasis and coagulation in blood vessels, and there is no need of tying them up. Practically, there is no damaging of the surrounding tissues. The technique is easy to use. When performing laparoscopic vaginal hysterectomy and adnexectomy the ligamentum infundibulopelvicum and ligamentum rotundum are cut, and there the blood vessels are not thicker than 3 millimeters. As these ligaments are easy to reach with ultrasonically activated scalpel, we can say that this instrument is the ideal option for laparoscopic vaginal hysterectomy.     

武钢铁路货车实时跟踪管理信息系统

武钢铁路货车实时跟踪管理信息系统是武钢运输部铁路信息化建设的重要组成部分。介绍其总体设计思路、系统框架组成、主要功能和应用情况,并对武钢铁路货车实时跟踪管理信息系统进行深入的分析和阐述。     

大直径铝锭热顶铸造中超声施振深度的细晶机制

在直径为650 mm的铝合金热顶半连续铸造过程中施加双源超声振动系统, 研究3种超声辐射杆浸入深度对铸锭宏观凝固组织的影响.基于铝合金铸锭凝固组织形貌的检测结果以及ANSYS等有限元软件对铸造过程中声场的仿真结果, 深入探讨了超声辐射杆在不同的施振深度下对铝合金铸锭凝固组织细化机制的影响.结果表明: 随着超声辐射杆施振深度的增加, 铸锭截面组织整体进一步细化, 晶粒形状由发达的枝晶变为等轴枝晶; 由于超声辐射杆端面以及柱面存在几个固定位置处振动波峰, 在铝熔体中不同的超声施振深度下存在不同的超声空化范围, 进而导致凝固组织的细化机制也不同.      

纵切线卷径测控系统的设计

介绍宝钢热轧厂纵切线卷径测控系统的设计。该要用了较先进的卷径测量装置，设计了 人机对话功能，简化了操作人员的操作工序，并使卷径误差减小到令人满意的结果。     

Identifying illness: pitfalls and discoveries

A 63-year-old woman presented with a comatose state after a fall. Results of cranial computed tomography (CT) and magnetic resonance imaging (MRI) scans were normal. An EEG recorded 5 h after admission was very severely attenuated and slowed. Consciousness and EEG were improved the next day. No cause was detected initially. After sleep deprivation, the patient had a generalized seizure followed by a similar coma and EEG. Even a single seizure may cause a prolonged coma with a very severely attenuated and slowed EEG.