Prototype system for an MR simulation of intracavitary brachytherapy for cervical cancer: Preliminary results in six cases

We report a newly developed MR simulation system for intracavitary brachytherapy for cervical cancer and subsequent treatment results. MR simulation was performed on six patients. The spatial relationship of the tumor to the bladder, rectum, bowel, applicators, etc. was depicted well. Doses to the tumor and surrounding normal tissues were read from isodose curves superimposed on the T2-weighted sagittal image. This system promises to be useful in customizing the dose distribution.     

头低位限制活动对家兔主要脏器微血管壁通透性的影响

本文报导了用40只白色短毛家兔所做的动物模拟失重实验,得出各脏器微血管通透性的动态反应曲线。并用微循环研究方法,分析了模拟失重时各脏器微血管功能状态与微血管通透性之间的关系;阐述了各脏器微循环功能变化特点;并对变化机理作了初步探讨。     

Change in knowledge of midwives and obstetricians following obstetric emergency training: a randomised controlled trial of local hospital, simulation centre and teamwork training

Objectives  To explore the effect of obstetric emergency training on knowledge. Furthermore, to assess if acquisition of knowledge is influenced by the training setting or teamwork training.
Design  A prospective randomised controlled trial.
Setting  Training was completed in six hospitals in the South West of England, UK and at the Bristol Medical Simulation Centre, UK.
Population  Midwives and obstetric doctors working for the participating hospitals were eligible for inclusion in the study. A total of 140 participants (22 junior and 23 senior doctors, 47 junior and 48 senior midwives) were studied.
Methods  Participants were randomised to one of four obstetric emergency training interventions: (1) 1-day course at local hospital, (2) 1-day course at simulation centre, (3) 2-day course with teamwork training at local hospital and (4) 2-day course with teamwork training at simulation centre.
Main outcome measures  Change in knowledge was assessed by a 185 question Multiple-Choice Questionnaire (MCQ) completed up to 3 weeks before and 3 weeks after the training intervention.
Results  There was a significant increase in knowledge following training; mean MCQ score increased by 20.6 points (95% CI 18.1–23.1, P < 0.001). Overall, 123/133 (92.5%) participants increased their MCQ score. There was no significant effect on the MCQ score of either the location of training (two-way analysis of variants P = 0.785) or the inclusion of teamwork training ( P = 0.965).
Conclusions  Practical, multiprofessional, obstetric emergency training increased midwives' and doctors' knowledge of obstetric emergency management. Furthermore, neither the location of training, in a simulation centre or in local hospitals, nor the inclusion of teamwork training made any significant difference to the acquisition of knowledge in obstetric emergencies.     

测胎儿器官重量探讨其生长发育规律

根据1022例新鲜胎尸的不同受精龄与体重，十项重要器官（心、肝、脾、左右肺、左右肾、左右肾上腺、胸腺等）的重量进行测量，将所测得的原始数据输入到IBM-PC/XT微型计算机内进行数据处理。探讨胎儿生长发育的基本规律。结果：（1）建立了胎儿体重与胎龄之间的推算式；（2）建立了胎儿各重要器官重量与胎龄之间的推算式；（3）建立了胎儿体重每月平均增长量与胎龄之间的推算式；（4）按胎儿体重每月平均增长量，用有序聚类分析方法，将胎儿生长发育过程划分为三个阶段。     

An algorithm for the automated quantitation of metabolites in in vitro NMR signals.

The quantitation of metabolite concentrations from in vitro NMR spectra is hampered by the sensitivity of peak positions to experimental conditions. The quantitation methods currently available are generally labor intensive and cannot readily be automated. Here, an algorithm is presented for the automatic time domain analysis of high-resolution NMR spectra. The TARQUIN algorithm uses a set of basis functions obtained by quantum mechanical simulation using predetermined parameters. Each basis function is optimized by subdividing it into a set of signals from magnetically equivalent spins and varying the simulated chemical shifts of each of these groups to match the signal undergoing analysis. A novel approach to the standard multidimensional minimization problem is introduced based on evaluating the fit resulting from different permutations of possible chemical shifts, obtained from one-dimensional searches. Results are presented from the analysis of (1)H proton magic angle spinning spectra of cell lines illustrating the robustness of the method in a typical application. Simulation was used to investigate the biggest peak shifts that can be tolerated.     

Sampling Patients Within and Across Health Care Providers: Multi-Stage Non-Nested Samples in Health Services Research

In order to better inform study design decisions when sampling patients within and across health care providers we develop a simulation-based approach for designing complex multi-stage samples. The approach explores the tradeoff between competing design goals such as precision of estimates, coverage of the target population and cost.We elicit a number of sensible candidate designs, evaluate these designs with respect to multiple sampling goals, investigate their tradeoffs, and identify the design that is the best compromise among all goals. This approach recognizes that, in the practice of sampling, precision of the estimates is not the only important goal, and that there are tradeoffs with coverage and cost that should be explicitly considered. One can easily add other goals. We construct a sample frame with all phase III clinical cancer treatment trials that are conducted by cooperative oncology groups of the National Cancer Institute from October 1, 1998 through December 31, 1999. Simulation results for our study suggest sampling a different number of trials and institutions than initially considered.Simulations of different study designs can uncover efficiency gains both in terms of improved precision of the estimates and in terms of improved coverage of the target population. Simulations enable us to explore the tradeoffs between competing sampling goals and to quantify these efficiency gains. This is true even for complex designs where the stages are not strictly nested in one another.     

颈动脉分叉血液动力状态的计算流体力学初步研究

目的应用计算流体力学（CFD）方法结合血管影像显示在体颈动脉分叉的血流动力状态.方法选取1例志愿者,采用Siemens多层螺旋CT机行左侧颈动脉CT血管成像检查（CTA）,扫描所得原始图像经计算机后处理后,用CFD方法计算并显示血液动力学各项指标.结果（1）该血管血液流率均值范围为0.04～0.36 m/s,颈外和颈内动脉的内侧壁（均以分叉顶点为参照）可见一高血流速区,球部可见较大片低血流速区;颈动脉分叉及颈内、外动脉近端均可见血液涡流与回流.（2）血液绝对压、静态压和动态压的均值范围分别为100 266.70～101 615.90 Pa、-10 58.34～290.88 Pa、6.12～553.25 Pa;（3）管壁切应力均值范围为0.59～5.35 Pa,在颈动脉球部及颈内动脉后壁显示大范围的低切应力区,最低约为0.25 Pa,颈外动脉前外侧壁存在一小范围低切应力区.结论CFD方法结合血管影像能计算并显示在体颈动脉分叉的个体化血液动力学指标.     

Development of computer-assisted simulation procedure to analyze receptor modulatory processes

Summary Experimentally induced changes in neurotransmitter receptors have been analyzed by means of a computer assisted simulation procedure over a wide range of free ligand concentrations. This approach allows to evaluate, for a given range of ligand concentrations, the relative influence of simultaneous variations in binding parameters (i.e. dissociation constant or K_d and in maximal number of binding sites or B_m) and to predict the net and final effect of the experimental condition on the receptor-mediated transmission line. The function representing the changes in bound values versus the respective free ligand concentrations, has been studied analytically on the basis of all the possible values that the percent changes in both K_d and B_m parameters induced by a given experimental condition can assume. A well characterized change in the pattern of bound radioligand could in this way be defined. This approach, developed to show in an immediate and clear way treatment-induce changes in receptor populations or to fit directly rough experimental data expressed as differences in bound values versus free ligand concentrations, seems to be an useful complement to the widely used saturation analysis of binding data.     

一种基于μ子进行核材料探测成像的模拟系统

宇宙射线斗子成像检测技术具有穿透力强、对高Z材料敏感等特点，特别适合检测特殊核材料，是监控核材料走私的有效方式之一。在搭建μ子成像检测硬件系统的同时，我们开发了一套针对实际硬件系统的模拟系统，并利用该系统开展斗子成像方法的研究。本文将介绍该模拟系统的有关情况，并给出利用该系统得到的仿真结果。相信这一工作将对实际宇宙射线μ子成像系统的设计给出指导意见。     

RF refocused echoes of J-coupled spin systems: effects on RARE-based spectroscopic imaging.

A numerical simulation tool was developed to calculate the echo amplitudes of J-coupled resonances within a series of radiofrequency (RF) refocused echoes. The signal modulation due to J-coupling in rapid acquisition with relaxation enhancement (RARE) is suppressed only when the inverse of the pulse interval (tau) is large compared to both the chemical shift (CS) difference (Deltadelta) of the coupled spins and the coupling constant. In contrast, the echo amplitudes in ultrafast low-flip-angle RARE (U-FLARE) oscillate around a quasi-steady-state value that is greater than zero (neglecting relaxation and diffusion) even when Deltadelta > 1/tau. The flip-angle distribution over the measured slice caused by the use of Gaussian-shape slice-selective refocusing pulses further reduces the echo oscillations. When the pulse interval falls short of the fast pulse rate regime, spectroscopic U-FLARE provides an improved spatial impulse response in the phase-encoding (PE) direction compared to spectroscopic RARE.