寰枢椎后路柔性固定的生物力学研究

目的分析细棒、PEEK棒固定对寰枢关节稳定性的影响。方法采用6具新鲜成人枕骨(occipital bone,Oc)~颈椎C4节段进行测试,模拟以下手术及固定状态:①完整状态;②损伤状态:枢椎齿状突II型骨折;③坚强固定:寰枢椎均采用普通椎弓根螺钉固定,直径3.5 mm钛棒连接;④PEEK棒:直径3.5 mm的PEEK棒连接;⑤细棒:直径2.0 mm钛棒连接。采用重复测量实验设计,在完整、损伤和不同的固定状态下,通过脊柱试验机对标本分别施加1.5 N·m的前屈/后伸、左/右侧弯和左/右轴向旋转的纯力偶矩。采用Optotrak三维运动测量系统连续采集标本运动,分析寰枢椎之间角度运动范围和中性区。结果采用直径3.5 mm的钛棒,2.0 mm的细棒以及3.5 mm的PEEK棒固定后,在前屈、后伸、侧弯和旋转方向上均显著减小了固定节段的运动范围(P<0.05)。直径3.5 mm和2.0 mm的棒固定后的运动范围,在各个方向上无显著性差异。PEEK棒固定的运动范围仅在侧弯方向上大于坚强固定(P=0.005),其他方向无显著性差异。3种固定方式在屈伸、侧弯和旋转方向上均显著减小了固定节段的中性区(P<0.05)。各种固定方式之间相比较,无显著性差异(P>0.05)。结论在寰枢关节采用直径2.0 mm的细棒固定,与坚强固定的稳定性相当。采用直径3.5 mm的PEEK棒固定,在前屈、后伸、旋转方向上与坚强固定的稳定性相当,在侧弯方向上弱于坚强固定。     

Dual wavelength 5-aminolevulinic acid photodynamic therapy using a novel flexible light-emitting diode unit

Background

Photosensitizers used for photodynamic therapy (PDT) to treat dermatologic disease are metabolized into mainly protoporphyrin IX (PpIX), which has five absorption wavelength peaks: 410?nm, 510?nm, 545?nm, 580?nm, and 630?nm. Although only red light around 635?nm and blue light around 400?nm are used as light sources for PDT, the efficiency of PDT might be improved by using multiple wavelengths, including those that correspond to the other absorption peaks of PpIX. Furthermore, because the target disease often occurs on the face, a flexible-type light-source unit that can be fitted to the lesion without unnecessarily exposing the mucous membranes, e.g., the eyes, nostrils, and mouth, is preferred.

纤维支气管镜对右中叶肺不张的诊治价值(附50例报告)

目的：探讨应用纤维支气管镜检查术在右中叶肺不张诊断和治疗中的价值。方法：对50例右中叶肺不张患者应用纤维支气管镜进行诊断和治疗。结果：50例右中叶肺不张中非特异性炎症29例、肺癌12例、结核3例、异物1例、未确定诊断5例，总确诊率90％(45／50)；50例中33例经纤维支气管镜直视下局部治疗后复张，有效率66％(33／50)，术后未见严重并发症。结论：纤维支气管镜对右中叶肺不张有一定的临床诊断和治疗价值。     

用纤支镜为支气管哮喘患者作肺灌洗的安全性观察

本文对12例支气管哮喘病人作了22例次支气管肺泡灌洗,其中3例次为重度哮喘发作;8例次为中度发作[1];11例次为缓解期.灌洗方法在一般肺灌洗的基础上经过改良后,12例病人无1例死亡.11例次哮喘发作患者,灌洗后临床症状皆有不同程度改善.11例次缓解期病人,灌洗后皆无不良反应.凡哮喘时间较长者,均能灌洗出较大量脓痰栓.     

The yield of flexible fiberoptic sigmoidoscopy in the detection of asymptomatic colorectal neoplasia

Recent evidence of a reduction in mortality rates from distal colorectal cancers in populations screened by rigid sigmoidoscopy suggests that further benefits may be achieved by the use of fiberoptic sigmoidoscopy as the screening modality. However, there is limited evidence as to the expected yield of neoplasia using the standard 60-cm instrument. The aim of this study was to determine the yield of neoplasia in an asymptomatic population in the at-risk age group undergoing fiberoptic sigmoidoscopy.Recruitment into the screening program was among State Department personnel. In total, 4,216 asymptomatic subjects (50–65 years) were offered flexible sigmoidoscopic screening performed following a simple enema bowel preparation. Those in whom a neoplastic condition was identified underwent further investigation (colonoscopy or barium enema).Of those offered screening 4,005 (95%) underwent the examination. Eleven carcinomas were detected at flexible sigmoidoscopy and two carcinomas were detected at further investigation in subjects with rectosigmoid polyps. The overall detection rate of carcinomas was 3.2 per 1,000 subjects screened.Histologically proven adenomas were detected in 217 subjects, 5.4% of the population screened.In this cohort of individuals flexible sigmoidoscopy appears to have been an acceptable form of screening.The detection rate of neoplasia, particularly colorectal adenomas, is higher than that reported from studies of fecal occult blood screening.     

An optimal dynamic output feedback controller for a flexible spacecraft

The design of a low-order dynamic output feedback controller for a flexible spacecraft is carried out using modified linear quadratic Gaussian (LQG) theory. The necessary conditions for optimization are given. The linear equations governing a flexible spacecraft with a central rigid body and two sun-tracking solar panels are presented. The parameters of the Solar Electric Propulsion Spacecraft (SEPS) are selected for analysis and simulation. The optimal gains for the dynamic controller are estimated using an iterative algorithm. The sequential procedure which assures convergence is selected. The initial gains which stabilize the system are chosen on the basis of the principle of a PD controller. A third-order controller for pitch, roll and yaw axes of the 18th-order system, which includes sensor and actuator dynamics, is designed. Numerical simulations carried out to ascertain the performance of the controller show the performance to be satisfactory.     

A multi-input/multi-output optimal PI controller for redundant robots in the presence of flexible disturbances

The two-stage synthesis of a multi-input/multi-output optimal proportional-integral (PI) controller is described for linear, time-invariant systems. In the first stage the PI controller is designed by solving a steady state algebraic Riccati equation. As a result, the optimal cost is expressed in terms of the system's constant output set-points. In the second stage the cost is further reduced by optimally selecting the output set-points to minimize a static quadratic performance index subject to linear algebraic constraints. The design framework is applied to a planar redundant robotic manipulator equipped with four joints and mounted at the tip of a long flexible arm. We then address the problem of self-motion control in the presence of vibratory disturbances.     

Necessary optimality conditions for a generalized problem of production scheduling

This communication concerns a derivation and study of necessary optimality conditions for production scheduling. The continuous-time optimal control problem is stated for the analysis of extremal behaviour of a flexible flow shop. This is accomplished by means of the maximum principle, which is applied to the problem with irregular constraints and three typical forms of objective function.