A Note on Testing Equality of Means when Sample Sizes are Random with Application

The problem of testing the equality of means of two normal populations is considered when independent random samples of random sizes are given with the total number of observations from both populations being a fixed number. An application in forestry is discussed.     

Acute bone response to whole body vibration in healthy pre-pubertal boys

The skeleton responds to mechanical stimulation. We wished to ascertain the magnitude and speed of the growing skeleton’s response to a standardised form of mechanical stimulation, vibration. 36 prepubertal boys stood for 10 minutes in total on one of two vibrating platforms (high (>2 g) or low (<1 g) magnitude vibration) on either 1, 3 or 5 successive days (n=12 for each duration); 15 control subjects stood on an inactive platform. Blood samples were taken at intervals before and after vibration to measure bone formation (P1NP, osteocalcin) and resorption (CTx) markers as well as osteoprotegerin and sclerostin. There were no significant differences between platform and control groups in bone turnover markers immediately after vibration on days 1, 3 and 5. Combining platform groups, at day 8 P1NP increased by 25.1% (CI 12.3 to 38.0; paired t-test p=0.005) and bone resorption increased by 10.9% (CI 3.6 to 18.2; paired t-test p=0.009) compared to baseline. Osteocalcin, osteoprotogerin and sclerostin did not change significantly. The growing skeleton can respond quickly to vibration of either high or low magnitude. Further work is needed to determine the utility of such “stimulation-testing” in clinical practice.     

Isotonic and isoelectric endurance tests for the upper trapezius muscle

As an alternative to a conventional endurance electromyogram (EMG) test for assessment of muscle capacity in the upper trapezius muscle (isotonic test, IT), an isoelectric test (IE) has been investigated. Nine subjects performed the two endurance tests. The tests were performed with a straight horizontal arm in the plane of the scapula. In IE, EMG amplitude was fed back to the subject and the subject was instructed to maintain a constant EMG activity equal to the level with the arm unsupported. Subjective ratings of local fatigue were obtained during the experiments. The EMG recordings from both tests were analysed for the root mean square value as well as according to the mean power frequency (MPF) technique. All the subjects endured maximal 15 min IE while in IT the median endurance was 11.9 min. Average subjective ratings of perceived fatigue increased more in IT compared to IE. The average normalised MPF curve from IT increased while that from IE was unaffected. There was a significant difference between the MPF results at 6 and 8 min. It is noteworthy that the MPF was higher in IT in spite of a higher accumulated biomechanical load. It was concluded from these studies that the interpretation of decreased MPF as an indicator of increased local muscle fatigue is doubtful at low contraction levels. It is suggested that an IE is a more appropriate method for the functional evaluation of low threshold motor units of the upper trapezius muscle in research into occupational disorders. Accepted: 15 October 1996     

Inhibition of Lipid Peroxidation by S -nitrosoglutathione and Copper

The antioxidant properties of S -nitrosoglutathione, a nitric oxide-derived product were studied in different experimental systems. By using the crocin bleaching test, S -nitrosoglutathione, in the presence of copper ions, shows an antioxidant capacity about six times higher than that of Trolox c and referable to the interception of peroxyl radicals by nitric oxide. Copper alone shows a modest inhibitory action, which is about seven times lower than that of Trolox c. S -nitrosoglutathione prevents lipid peroxidation induced by the well-known Fe 2+ /ascorbate system (IC 50 =450 &#119 M) and the inhibitory effect is strongly reinforced by the presence of copper ions (IC 50 =6.5 &#119 M). In addition, cumene hydroperoxide-induced lipid peroxidation is markedly decreased by S -nitrosoglutathione, provided that copper ions, maintained reduced by ascorbate, are present. Decomposition of S -nitrosoglutathione through metal catalysis and/or the presence of reducing agents and the consequent release of nitric oxide are of crucial importance for eliciting the antioxidant power. In this way, copper ions and/or reducing species with low antioxidant potency are able to promote the formation of an extremely strong antioxidant species such as nitric oxide.     

革兰染色对患者阴道分泌物的检验价值

目的探讨革兰染色对患者阴道分泌物的检验价值。方法选择2015年4月至2017年4月于诸暨市中心医院进行阴道分泌物检验的阴道炎患者为研究对象,共1 600例。采用生理盐水镜检法和革兰染色法对分泌物进行检验,比较两种检验方法对分泌物病变的检出情况,同时比较两种检验方法的特异性和敏感性。结果革兰染色法对分泌物病变的检出率为32.50%,生理盐水镜检法的检出率为28.50%,二者差异有统计学意义(P0.05)。革兰染色法对阴道分泌物检验的准确性、敏感性及特异性分别为95.61%、96.34%、97.87%,均高于生理盐水镜检法,差异有统计学意义(P0.05)。结论阴道分泌物检验是诊断阴道炎最便捷的方法。与常规的生理盐水镜检法相比,革兰染色法具有更高的准确性、特异性和敏感性,对阴道炎的早发现、早治疗具有较高的应用价值。     

Gender differences in anaerobic power tests

The purpose of this study was to determine if the differences in anaerobic power between males and females could be accounted for by differences in body composition, strength, and neuromuscular function. A total of 82 untrained men and 99 women took part in the study. Body composition, somatotype, isometric strength, neuromuscular function were measured, and four anaerobic power tests performed. The men were significantly different from the women on all strength, power, and neuromuscular measurements except reaction time and on all anthropometric and somatotype dimensions except ectomorphy. Strength and anthropometric dimensions were similarly related to anaerobic power values within each sex. Relative fat (%fat) exerted different degrees of influence on sprint and jump performances in each sex. Removing the influence of anthropometric, strength, and neuromuscular differences by analysis of covariance reduced, but did not remove, the significant differences between the sexes. Therefore, factors other than lean body mass, leg strength, and neuromuscular function may be operating in short-term, explosive power performances to account for the differences between the sexes. The task-specific nature of anaerobic power tests and the relatively large influence of anthropometric factors on power production were confirmed.     

军医大学学员坚毅性评价的内隐效应及脑电特征研究

目的:探寻军医大学学员内隐层面对自我和他人坚毅性评价的特点及脑电特征,为全面、客观的评估个体的坚毅性提供理论依据和客观指标。方法:使用E-Prime2.0参照经典内隐联想范式编制内隐联想-坚毅测验,对100名军医大学学员施测坚毅量表(Grit O),选取高、低坚毅水平被试(各20名)进行内隐联想-坚毅测验,并记录脑电,分析两组被试的内隐效应及主要脑电成分。结果:计算内隐效应D值,t检验显示高坚毅组(0.55±0.36)显著低于低坚毅组(0.87±0.49),t=-2.257,P0.05,Cohen'd=0.74。两组被试均诱发明显的N400和LPP,高坚毅组中N400在任务状态下主效应显著,F(1,17)=8.528,P0.05,η2=0.334,且在电极位置上主效应显著,F(10,170)=8.207,P0.001,η2=0.326。LPP在任务状态下主效应显著,F(1,17)=5.471,P0.05,η2=0.243,且在电极位置上主效应显著,F(10,170)=18.479,P0.001,η2=0.521;低坚毅组中N400在任务状态下主效应显著,F(1,17)=10.051,P0.05,η2=0.372,且在电极位置上主效应显著,F(10,170)=8.223,P0.001,η2=0.326,LPP在任务状态下主效应不显著。结论:1.军医大学学员坚毅性评价的内隐效应显著,即均倾向于认为自我的坚毅性高,他人的坚毅性低,通过问卷法评估坚毅性时应考虑坚毅评价的内隐效应。2.高、低坚毅性军医大学学员坚毅性内隐评价时的主要脑电成分N400、LPP存在差异,N400可作为坚毅性内隐评价符合程度的判断指标。3.内隐效应及N400可以作为对军医大学学员坚毅性评价时的客观指标。     

A suggested standardised method for testing photocatalytic inactivation of aeroterrestrial algal growth on TiO2-coated glass

Aeroterrestrial green algae form conspicuous biofilms on man-made surfaces. The self-cleaning properties of photocatalytic coatings prevent their growth and can probably replace biocides. The aim of this study was to develop a laboratory method to investigate the efficiency of photocatalytic materials against algal growth. Two algal isolates (“Chlorella” luteoviridis, SAG 2196, and Coccomyxa sp., SAG 2040) functioned well as model organisms because they grew on almost all test specimens at 100% humidity and low UVA radiation. With these species, we examined algal growth prevention using photocatalytic glass. No effects on algal growth were detected, although the coated surfaces were photocatalytically active and degraded methylene blue. Because their cells are protected well against photocatalytically generated hydroxyl radicals, aeroterrestrial algae survive various stress factors. Nevertheless, the newly developed experimental design may be useful for assessing the biological function of other photocatalytic materials or stress factors.