Utility of a dynamic termination criterion in the ZEST adaptive threshold method

Bayesian adaptive threshold procedures may be run for a fixed number of trials, or may be stopped when the calculated confidence interval for the threshold reaches a selected limit (a dynamic termination criterion). This study used Monte-Carlo simulations to determine whether the confidence interval is a useful predictor of errors in the estimated threshold. No difference was found between the distribution of errors in a fixed trial procedure versus a dynamically terminated procedure of the same average number of trials. In addition, the width of the confidence interval failed to usefully predict observer variability arising from a shallow psychometric function slope or increased false positive response probabilities. This study suggests that dynamic termination criteria are of little use in Bayesian adaptive threshold procedures.     

Muscle efficiency: the controversial role of elasticity and mechanical energy conversion in stretch-shortening cycles

The analysis of muscle efficiency was performed on a variety of simulated muscle stretch-shortening cycles of in situ rat gastrocnemius muscle. The processes of biochemical energy conversions (phosphorylation and contraction-coupling) and mechanical conversions (internal work to external work) were incorporated in the efficiency calculations. Metabolic cost was determined using a simple linear model. Special attention was drawn to the interacting roles of series elastic compliance and contraction dynamics. The results showed that series elastic compliance affected the efficiency of muscle contraction to a great extent. Stiff muscle was well designed to perform efficient contractions in which muscle merely shortened while active. Compliant muscle performed best in true stretch-shortening contractions utilising the storage and release of series elastic energy effectively. However, both stiff and compliant series elastic elements showed similar optimal muscle efficiency values in shortening contractions and stretch-shortening contractions, respectively. The findings indicate that the storage and re-utilisation of series elastic energy does not enhance overall muscle efficiency, but that optimal efficiency is obtained by a proper design of the muscle with regard to the dynamics of the movement task. Furthermore, it was found that although biochemical efficiency determined the feasible range of muscle efficiency, mechanical work conversions had the strongest influence on the exact value of overall muscle efficiency in stretch-shortening contractions. Electronic Publication     

4种核酸提取方法在流行性感冒病毒核酸检测中的比较

目的：比较常见的4种核酸抽提方法，比较其对流行性感冒（流感）病毒检测的敏感性差异，为实验室应用和结果的评价提供依据。方法：对已确定效价的甲1型流感病毒，作10^-2～10^-5系列稀释，选用Roche公司Hish Pure Viral RNA Kit、QIAGEN公司的Rneasy mini Kit、国产Z生物公司RNA提取试剂盒和Invitrogen公司Trizol试剂等4种核酸提取方法提取上述标本核酸模板，采用罗氏公司的RT-PCR试剂盒，用实时荧光定量聚合酶链反应（FQ-PCR）对其进行评价。结果：在对不同病毒拷贝数流感病毒的检测中，4种核酸提取方法以Roche公司High Pure Viral RNA Kit提取效率最高，以此提取效率作为100％，则QIAGEN Rneasy mini Kit、Invitrogen Trizol和国产Z生物公司RNA提取试剂盒的平均提取效率依次为89．71％、75．30％、68．00％。经方差分析及t检验，4种方法之间存在显著性差异（P均〈0．05）。对临床标本的检测，也获得相似结果。结论：各试剂之间提取核酸的效率存在差异，应该选择性价比较好的方法进行临床标本的实验室RNA提取。     

Efficiency gains from the addition of controls to matched sets in cohort studies

We evaluate relative efficiencies of added controls in matched cohort studies in terms of the asymptotic variance of the estimate of the log relative risk associated with a single binary exposure variable. We calculate expected contributions to the information based on the Cox proportional hazards model under the assumption that the failure times for exposed and unexposed individuals have independent exponential or Weibull distributions and that the censoring variable, when present, also has an exponential distribution or a Weibull distribution with a shape parameter common to that of the failure time distribution. With estimation of a relative risk of four or less, one gains little with an increase in the ratio of unexposed to exposed cohort members beyond five or so.     

Effect of covariate measurement error in randomized clinical trials

Prognostic factors often appear as covariates in clinical trials designed to estimate treatment effects. These factors are usually subject to measurement error and lead to decreased efficiency in the estimation of the treatment effect. We use Weibull regression models and asymptotic theory to derive the efficiency of estimation obtained by adjusting for one dichotomous and one continuous covariate measured with error. An application to a clinical trial involving advanced lung cancer patients illustrates the results.     

中药物质基础研究的思路与方法

本文以中药现代化和国际化为导向，论述了中药研究中的重点与难点问题。阐述了中药研究的主要发展方向是突破中药化学物质基础研究，并提出了以活性导向的标准组分模式的中药物质基础研究新思路、新观点。强调中药物质基础研究的关键技术发展的重要性，并介绍了现代中药分离分析与表征的方法与技术。     

Determination and interpretation of mechanical power in human movement: application to ergometer cycling

Summary Based on a model consisting of three rigid links, an instantaneous power equation has been deduced for ergometer cycling which shows a causal relationship between power liberated in joint rotation on the one hand and the rate of change of segmental energy plus the power transferred to the pedal on the other. The shape and magnitude of these two types of power have been calculated by measurements of pedal force and cinematographic analysis and the results show fair agreement between them. When cycling at a mean exercise intensity of 340 W at 90 rpm, less than 28 W appears to be lost in the (necessary) changes of segmental energies. It is suggested that power liberated in the joints should be judged as the source of power in the power equation. It is, therefore, proposed that this power should be defined as external power in this and other human movement.     

小剂量甲状腺素治疗老年心功能不全临床研究

目的　探讨小剂量甲状腺素治疗老年心功能不全的疗效。方法　 82例老年心功能不全病人随机分成两组 ,治疗组 4 6例 ,对照组 36例 ,两组病人常规抗心衰治疗 ,同时治疗组加小剂量甲状腺素 2 0mg、1次 /d口服 ,连续服用 2周 ,观察两组治疗前后心功能级别、心胸比例、心脏射血分数变化。结果　用甲状腺素治疗 2周后 ,治疗组心功能明显改善、心胸比例缩小、心脏射血分数增高 ,与对照组比较 ,具有显著性差异 (P <0 0 0 5 ) ,在治疗期间治疗组未发生严重不良反应。结论　小剂量甲状腺素治疗慢性心功能不全尤其对老年心功能不全患者有明显疗效