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.

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.     

儿童喉、气管异物的诊治分析

目的探讨儿童喉、气管异物的临床特点及诊治手段。方法分析2001年1月到2005年6月间经硬质气管镜或纤维支气管镜确诊的87例喉、气管异物患儿的临床特点、影像学改变、并发症、异物取除方法。结果气管、喉异物占同期呼吸道异物的10.7%(87813),1～3岁组占73.6%。93.1%有异物吸入史,喘鸣占67.8%、吸气性凹陷40.2%、发绀27.6%、声音嘶哑19.5%、气管拍击音4.6%。6例(6.9%)患儿病情突变,表现发绀、呼吸困难,神志不清。胸片异常30.2%,胸透异常26.5%。硬质气管镜取异物63例并全部取出(100%),其中3例为纤支镜取异物未成功者;纤支镜取异物20例,取出17例(85.0%),两者成功率差异无显著性(P>0.5),但纤支镜取异物耗时不确定,并有5例异物通过鼻后孔时跌落入食道。结论儿童喉、气管异物典型症状不多见,异物吸入史为敏感指标;胸片、胸透异常率低,应及时作纤支镜检查,取除喉、气管异物首选硬质气管镜。     

软性神经内镜在神经外科手术中的应用

目的探讨软性神经内镜在神经外科的应用价值。方法应用光学纤维神经内镜和电子软性神经内镜,配合软性内镜专用手术器械单独或辅助显微外科手术治疗各种神经外科疾病228例。结果对63例慢性硬膜下血肿采用内镜下单纯钻孔冲洗术治疗,除早期1例术后血肿复发接受2次手术外,其余患者均一次治愈。10例侧脑室及三脑室后部肿瘤患者采用内镜下肿瘤活检、全切或部分切除,有8例明确病理诊断后改用其他治疗方式治疗。78例梗阻性脑积水患者在内镜下进行第三脑室底造瘘术,所有患者均获得成功造瘘,无1例造成副损伤。对19例因脑脊液吸收障碍导致的脑积水患者进行脉络丛烧灼术,其中13例仅单纯行脉络丛烧灼术,除1例单纯烧灼后颅压下降不明显、术后2周再行脑室-腹腔分流外,其余均获得满意疗效。内镜下打通脑室内多发分隔(感染或出血后)配合透明隔造瘘3例,均获成功。内镜下治疗颅内蛛网膜囊肿16例,手术效果满意。此外,完成内镜辅助下手术39例,效果满意。结论软性神经内镜有其独特的应用优势,和硬性神经内镜配合使用可以大大提高神经内镜在神经外科微创手术中的应用范围,值得推广。     

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.     

医疗器械供应链弹性管理的实践探讨

通过建立健全医院层面应急管理体系,建立医疗器械供应链预警机制,进行医院内外部动态管理,以信息化提高供应链可视性,可实现医疗器械供应链弹性管理。该管理模式能够有效确保供应链稳定性和可恢复性,进而提升医院应急防控能力,最终保障患者和医务人员安全。     

弹性材料修复前牙缺失的临床探讨

目的 为探讨弹性材料在修复前牙缺失中的临床效果,进一步推广应用弹性材料在口腔修复美容中的价值。方法 利用美国Valpast公司研制的弹性材料,湖南长沙AULEN公司生产的隐形义齿机。选择前牙缺失患者216例,按临床要求制备基牙工作模型,制作蜡型装合,加热去腊后灌注弹性材料,冷却后取出铸件修整抛光。结果 216例患者修复298颗牙,两年后随访168例,优良者156例,占92．86％;一般者8例,占4．76％;较差者4例,占2．38％。结论 本方法修复前牙缺失与传统方法相比,无需金属卡环支架固位,具有美观、舒适、超薄、耐磨、制作快捷、简单等优点,是修复前牙缺失的理想材料及方法,值得临床推广应用。