胫骨上端外部形状及内部结构的模拟

目的，进行胫骨上端内部结构和外部形状的模拟。方法，采用高阶非线性骨再造速率方程和有限元方法相结合，引入拓扑优化的思想，选取大于模拟的胫骨上端外形的模拟域，从不固定外形出发，对正常力学环境下的胫骨上端内部结构及外部形状进行模拟。结果，模拟的胫骨上端的外部形状和内部结构与真实结构十分接近。     

基于人工视网膜神经节细胞感受野的图像边缘检测

用光电池组装一个工感受野，在一维上模拟视网膜神经节细胞的零交叉滤波特性，进一步用该工工感受野构建一个图像边缘检测系统，并成功地用系统检测到图像边缘。一与般的基于视觉原理的图像系统相比，这种以人工感受野灵基础的系统，在图像输入的同时即可并行地提取图像边缘信息，而更接近于动物视觉系统原型，此结果将为人工视觉和图像技术的发展提供新的探索。     

Natural frequency/damping coefficient relationship of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure

Using a digital simulation method, we analyzed the relationship between natural frequency (f _n ) and damping coefficient () of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure. The pulmonary artery pressure waveform was obtained with a catheter-tip transducer and it was fed into a dynamic simulator programmed on a computer. The original waveform and the output of the simulator were compared and judged visually for the fidelity. From this analysis, the combination of f _n and was obtained and was plotted on a f _n – diagram. It showed as an area, which was convex on the left side and open on the right side. The left-convex endpoint was located at a damping coefficient of about 0.7. At a lower heart rate, this area was extended to the lower frequency side, while, at a higher heart rate, this area was limited to the higher frequency side. The f _n – diagram was also constructed theoretically by calculating the relations between natural frequencies and damping coefficients of a second order system with the amplitude and phase error tolerance set at +/–5% respectively.(Kinefuchi Y, Suzuki T, Takiguchi M, et al.: Natural frequency/Damping coefficient relationship of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure. J Anesth 7: 419--426, 1993)     

头低位卧床期间四肢加压套带预防大脑中动脉血流下降

目的　观察头低位卧床 2 1d期间套带对大脑中动脉血流变化的影响 .方法　健康男性志愿者 12名随机分为对照组和套带组 ,每组 6人 ,进行 - 6°卧床试验 2 1d.套带组卧床每日 0 8:30～ 2 0 :30四肢加压套带 ,压力维持在 5 .3k Pa,对照组不做任何对抗措施 .卧床前、卧床 10 d及卧床结束时进行 3次立位耐力试验 .卧床前、卧床 1,3,10和 2 1d用经颅超声多普勒 (TCD)测量大脑中动脉血流动力学指标 .结果　对照组 2 1d卧床期间大脑中动脉血流速度下降 ,血流量减少 ,其中卧床 3 d和 2 1d较卧床前血流速 (vs,vm)明显降低 ,血流量减少 (P<0 .0 5或 P<0 .0 1) .套带组卧床期间及卧床结束时血流速度及血流量较卧床前无显著降低或减少 (P>0 .0 5 ) .卧床 10 d和卧床结束时立位耐力试验对照组 6人均未通过立位耐力试验 .套带组 4人顺利通过立位耐力试验 ,2人未通过立位耐力试验 .结论　头低位卧床期间使用套带能有效减缓大脑中动脉血流速度下降 ,对改善失重引起的脑缺血和立位耐力不良有明显的作用 .     

头高位倾斜时心血管反应的仿真

仿真头高位倾斜时心血管系统的反应,进一步研究有关立位应激的生理机制。方法以仿真下体负压时心血管反应的模型为基础,在血液重新分配子模中引入了重力致血液重新转移的环节,在压力反射控制子模型中考虑了心水平与颈动脉压力感受器间的流体静压差。     

5—氨基水杨酸与乙基纤维素溶混性的计算机模拟

使用计算机辅助分子建模（ＣＡＭＭ）、分子力学和蒙特卡罗方法,模拟了５－氨基水杨酸（５－ＡＳＡ,Ｃ７Ｈ７ＮＯ３,美沙拉灵（ｓｐ－５７－６））与乙基纤维素（ＥＣ）的溶混性。模拟结果显示,在２７３Ｋ至３１６Ｋ的温度范围内,５－氨基水杨酸与乙基纤维素能以任何比例混溶。得出Ｅｍｉｘ（Ｔ）＝Ａ＋ＢＴ＋Ｃ／Ｔ模型,Ａ＝０．３６９４Ｅ＋０４,Ｂ＝－０．２６１０Ｅ－０２,ａｎｄＣ＝０．１８１８Ｅ＋０４,以及Ｅｍｉｘ（Ｔ）模型标准方差,Ｓ＝０．２６５４Ｅ－０３ｋｃａｌ／ｍｏｌ。对乙基纤维素及５－氨基水杨酸与乙基纤维素混溶过程的能量和构象分析表明,混溶过程中有乙基纤维素分子内和乙基纤维素与乙基纤维素分子间氢键形成。对两相混溶体系进行了热力学分析。     

Steps to optimize transscleral photocoagulation

Background: In transscleral photocoagulation, the desired effect is coagulation of parts of the ciliary body or of the peripheral retina. However, the application is often limited by the unwanted effect of coagulation of the sclera. to reduce this effect, the ratio of incident radiation flux to radiation flux transported through the sclera (and able to coagulate the target tissue) should be minimized by the incident beam characteristics.Methods: Monte Carlo simulations for the radiation transport problem of multiple scattering in the sclera were used to calculate the ratio of transported to incident radiation for different parameter settings of beam diameters, optical thicknesses of the sclera and beam angles. To verify the theoretical calculations, an simple optical device utilizing a bulb instead of a laser source was constructed and applied to enucleated porcine eyes.Results: The theoretical calculations showed that the ratio of incident to transported radiation flux can typically be decreased by a factor of three by increasing the beam radius from 0.35 mm (as used in state-of-the-art laser devices) to 2 mm. This was confirmed by the experiments. Coagulations of the ciliary body or of the peripheral retina were possible with power densities an order of magnitude below the values normally applied with laser sources.Conclusion: To improve transscleral photocoagulation, beam diameters should be increased.     

Laser energy threshold for thermal vascular injury in a port-wine stain skin model

Monte Carlo simulation of laser energy deposition in a port-wine stain (PWS) skin model and numerical solution of the thermal diffusion equation have been used to calculate threshold energies for thermal injury of PWS blood vessels for different vessel sizes and laser pulse durations. It has been assumed that an average vessel temperature rise of 65 C causes thermal injury to the blood vessel. The result is that for a certain combination of wavelength, pulse duration and incident energy density, only a limited range of blood vessel sizes can be injured optimally. Higher energy densities are required to injure smaller vessels with the same pulse duration, spot size and wavelength. This gives support to the mechanisms of selective photothermolysis suggested previously by Anderson and Parrish, although their model was based on the cooling behaviour of instantaneously heated vessels. The authors hypothesize that different laser parameter settings that match the individual PWS vessel anatomy during treatment will be used in the future, instead of many treatments with the same laser parameters. This could lead to less treatment sessions and to an improved predictability of clinical results.     

Locating human quantitative trait loci: Guidelines for the selection of sibling pairs for genotyping

Simulation studies were conducted to assess the relative merits of different nonrandom sampling strategies for the selection of sibling pairs for genotyping in the attempt to locate individual loci (QTLs) contributing to variation in human quantitative traits. For a constant amount of variation contributed by a QTL (25% of the total) the frequencies and dominance relationships of a trait increasing allele were varied. Three strategies for selection of pairs for genotyping were based on the phenotypic values of the siblings: Concordant sib pairs (CSP) are pairs in which both individuals exceed a given threshold value; discordant sib pairs (DSP) are pairs in which one member exceeds a given upper threshold and the other is below a specified lower threshold; and most similar pairs (MSP) are pairs selected for falling below a specified percentile ranking of the within-pair mean square for the quantitative trait. Tests for linkage with markers at 1, 2, 5, 10, and 20 cM from each of the QTLs were conducted for each of the selected samples and compared with tests based on the regression, in the entire sample, of within pair variation on the proportion of alleles identical by descent (IBD) at each marker locus. Tests for the effect of the increasing allele at the QTL (candidate gene) were also conducted for the DSP pairs. No single nonrandom selection procedure yields as much as half the information realized in the total sample. However, a combined strategy which involves genotyping the 5% of MSP and DSP for the upper and lower quintiles of values of the quantitative trait (a further 3% of the sample approximately) yields lod scores which are usually more than 65% of the values realized for the entire sample. Tests comparing the proportion of increasing alleles in high- and low-scoring siblings from DSP samples are uniformly very powerful for detecting candidate loci. Even when it is not possible to measure the entire range of the phenotype with uniform precision, some attempt to differentiate among individuals in a common unaffected class of individuals can lead to considerable increase in power.     

虚拟现实模拟培训在青年医师腹腔镜技能培训中的作用

目的 通过分析郑州大学附属郑州中心医院参加过腹腔镜技能培训的普外科青年医师的腹腔镜胆囊切除术学习曲线,探讨腹腔镜虚拟现实模拟培训的意义。方法 将青年外科医师50人分为两组,干预组参加虚拟现实模拟培训,对照组参加传统腹腔镜临床培训。培训完成后,在高年资拥有丰富腹腔镜手术经验医师的监督下完成30例腹腔镜胆囊切除术。应用CUSUM分析法,根据完成率、手术评分和手术时间绘制学员的手术学习曲线。x为手术例数,k为斜率。计算k=0时的x值,比较两组学员的手术学习曲线和术中评分。采用SPSS 23.00进行t检验和卡方检验。结果 干预组与对照组分别在x=19.24±0.39、x=21.72±0.73时跨过手术学习曲线,差异有统计学意义（P<0.01）;干预组与对照组显露胆囊部分得分分别为（10.82±2.73）、（9.71±2.69）（t=4.61,P<0.01）;解剖胆囊三角得分分别为（12.59±3.12）、（8.87±2.99）（t=6.21,P<0.01）;剥离胆囊得分分别为（10.69±3.38）、（8.80±3.55）（t=3.10,P<0.01）。结论 虚拟现实模拟培训可以促进腹腔镜培训的基本技能转化为临床操作技能,可促进普外科青年医师成长。