Experimental analysis of the human perception threshold of a DC electric field

To study the biological effects of extremely low frequency (ELF) electric fields, a fundamental study is conducted of the human perception threshold of an electric field. The perception threshold is measured with human subjects, and the results are analysed. It is clear that field perception is based on the movement of hair and not on other sensations. Variance in the perception threshold and its causes are investigated. The perception threshold decreases by almost 30% as the relative humidity increases from 50 to 90%. The perception threshold is also dependent on the physical condition (length and density) of the hair and the psychological condition (degree of awareness) of the subject. The dependence on these is much smaller than that on relative humidity. The cause of the gender difference in the threshold is ascribed to the difference in the physical condition of the hair. Through this study, some factors to be taken into account for the safety standard are made clear.     

用小波变换结合神经网络检测ECG信号的P波

通过小波变换对ＥＧＣ信号进行分解,然后采用神经网络检测ＥＣＧ信号的Ｐ波,该方法作为一种辅助检测手段,效果良好。将其用于心率变异性分析具有重要意义。     

小学体育教师职业倦怠

目的:调查小学体育教师的职业倦怠现状。方法:采用教师职业倦怠量表对陕西省604名小学体育教师的职业倦怠展开调查。结果:1职业倦怠得分为(3.75±1.03)分,轻度、中度、重度的倦怠检出率依次为17.55%、67.38%、13.08%;2与小学主科教师相比,体育教师的情感耗竭高(t=4.12,P0.01),成就感低(t=6.26,P0.01),职业倦怠更明显(t=3.59,P0.01);3在低成就感维度上,男教师得分高于女教师(t=2.06,P0.05),不同职称(F=3.89,P0.05)、是否获奖(t=-2.49,P0.05)、有无职务(t=-2.03,P0.05)、不同教龄教师(F=5.96,P0.01)得分具有统计学差异。在情感耗竭维度上,不同职称(F=6.65,P0.01)、有无职务(t=-2.02,P0.05)、不同教龄(F=8.75,P0.001)教师得分具有统计学差异。在人格解体维度上,城县教师得分低于乡镇教师(t=-2.43,P0.05)。结论 :小学体育教师的职业倦怠检出率很高,倦怠程度深,亟需有针对性的干预与调适。     

一种多通道酶标仪的研制

基于朗伯比尔定律的酶标分析仪在临床诊断、实验室检测领域有着广泛的应用。本研究给出了采用双单片机控制的酶标仪的实现方法,对光学系统、电路结构、控制软件和机械驱动进行了设计。按照酶标分析仪检定规程对吸光度误差和通道差异进行检验,其结果符合要求。该酶标分析仪基本满足实际使用要求。     

肝螺杆菌TaqMan MGB探针实时荧光定量PCR快速检测方法的建立及应用研究

目的 建立特异、敏感、快速检测肝螺杆菌的TaqMan MGB探针实时荧光定量PCR方法.方法 针对肝螺杆菌flaB 基因的保守区设计特异性引物和探针,建立肝螺杆菌TaqMan MGB探针实时荧光定最PCR方检测方法,验证方法的特异性、敏感性和稳定性.对2008-2011年期间采集的1081份临床样本中的肝螺杆菌进行检测,同时进行分离培养和常规PCR检测.结果 建立的TaqMan MGB探针实时荧光定量PCR方法对肝螺杆菌的检测具有高度的特异性,对幽门螺杆菌、空肠弯曲菌、泰泽氏菌、侵肺巴斯德氏菌、大肠埃希菌、铜绿假单胞菌均无交叉反应,检测的灵敏度达8.3拷贝.标准曲线显示各浓度范围内具有良好的线性关系,相关系数为0.999,斜率为-3.227,TaqManMGB探针实时荧光定量PCR效率为100％.对1081份临床样本进行检测,TaqMan MGB探针实时荧光定量PCR和常规PCR均能检出86份肝螺杆菌阳性样本,而细菌分离培养则仅检出4份阳性.结果显示,建立的TaqMan MGB探针实时荧光定量PCR方法比细菌分离培养方法更敏感,能够直接从临床样本中检出肝螺杆菌DNA,检测时间仅为2h.结论 研究建立的TaqMan MGB探针实时荧光定量PCR方法具有可靠、特异、敏感的特点,适用于肝螺杆菌的快速检测.     

Diagnostic accuracy of loop-mediated isothermal amplification coupled to nanopore sequencing (LamPORE) for the detection of SARS-CoV-2 infection at scale in symptomatic and asymptomatic populations

ObjectivesRapid, high throughput diagnostics are a valuable tool, allowing the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in populations so as to identify and isolate people with asymptomatic and symptomatic infections. Reagent shortages and restricted access to high throughput testing solutions have limited the effectiveness of conventional assays such as quantitative RT-PCR (RT-qPCR), particularly throughout the first months of the coronavirus disease 2019 pandemic. We investigated the use of LamPORE, where loop-mediated isothermal amplification (LAMP) is coupled to nanopore sequencing technology, for the detection of SARS-CoV-2 in symptomatic and asymptomatic populations.MethodsIn an asymptomatic prospective cohort, for 3 weeks in September 2020, health-care workers across four sites (Birmingham, Southampton, Basingstoke and Manchester) self-swabbed with nasopharyngeal swabs weekly and supplied a saliva specimen daily. These samples were tested for SARS-CoV-2 RNA using the Oxford Nanopore LamPORE system and a reference RT-qPCR assay on extracted sample RNA. A second retrospective cohort of 848 patients with influenza-like illness from March 2020 to June 2020 were similarly tested from nasopharyngeal swabs.ResultsIn the asymptomatic cohort a total of 1200 participants supplied 23 427 samples (3966 swab, 19 461 saliva) over a 3-week period. The incidence of SARS-CoV-2 detection using LamPORE was 0.95%. Diagnostic sensitivity and specificity of LamPORE was >99.5% (decreasing to approximately 98% when clustered estimation was used) in both swab and saliva asymptomatic samples when compared with the reference RT-qPCR test. In the retrospective symptomatic cohort, the incidence was 13.4% and the sensitivity and specificity were 100%.ConclusionsLamPORE is a highly accurate methodology for the detection of SARS-CoV-2 in both symptomatic and asymptomatic population settings and can be used as an alternative to RT-qPCR.     

表达人CD36基因的293T细胞株的建立

目的 建立一种表达人类CD36基因的293T细胞株,用于CD36抗原的研究及CD36抗体检测.方法 采用RT-PCR技术,从人血小板中获取CD36基因的cDNA,克隆至表达载体pEGFP-C1中,对重组质粒测序鉴定后将质粒转染至293T细胞,该转基因的产物在293T细胞中的表达被观察超过1年.与CD36单克隆抗体及CD36阳性血清反应的流式细胞术试验评估这个细胞株的敏感性和特异性.结果 重组表达载体pEGFP-C1-CD36被成功构建,流式细胞术验证其转染效率达90％以上,实时荧光定量PCR和Western blot证明CD36基因在293T细胞中过表达.流式细胞试验结果为CD36单克隆抗体及CD36阳性血清为阳性,而其他所有的血清样本,包括CD36抗体阴性血清、含有HLA或HPA-3a抗体血清均为阴性.结论 建立的pEGFP-C1-CD36-293T细胞株能成功高效表达CD36抗原,并能特异快速、成功地检测CD36抗体,并且不受其他血型抗体的干扰,有一定的运用前景.     

基于自适应小波神经网络的心电图检测法

自适应小波神经网络检测法就是利用小波函数取代通常神经网络中隐层的作用函数来实现的，通过网络的学习自适应地调整尺度参数和时移因子，提高了特征提取能力，因此，该网络可提高心电信号的检测率和可靠性。     

中山地区54258例育龄人群G6PD筛查结果分析

目的通过大样本的筛查了解中山地区育龄人群G6PD的分布情况。方法以紫外速率法检测54258例育龄人群的静脉血液红细胞中葡萄糖-6-磷酸脱氢酶的活性,将G6PD活性按缺乏、正常和增高进行分组。结果中山地区G6PD酶活性检出率分别为：缺乏组4．33％、正常组94．75％、增高组0．92％,其中缺乏组检出率男性高于女性,增高组检出率男性低于女性。结论中山地区是G6PD缺乏症的高发地区,对育龄人群进行G6PD筛查,并进行优生优育的合理指导,是减少出生缺陷和提高出生人口质量的必要措施。     

False-Positive β-Galactosidase Staining in Osteoclasts by Endogenous Enzyme: Studies in Neonatal and Month-Old Wild-Type Mice

Escherichia coli β-galactosidase (β-gal), encoded by the lacZ gene, has become an essential tool in studies of gene expression and function in higher eukaryotes. lac-Z is widely used as a marker gene to detect expression of transgenes or Cre recombinase driven by tissue-specific promoters. The timing and location of promoter activity is easily visualized in whole embryos or specific tissues using the cleavable, chromogenic substrate, 5-bromo-4-chloro-3-indolyl-D-galactopyranoside (X-gal). The tissue specificity of promoters in transgenic constructs is routinely tested by using a promoter of choice to drive lacZ. Alternatively, the targeted expression of Cre recombinase to perform in vivo recombination of loxP sites can be visualized by β-gal staining in mice carrying a Cre-activated lacZ transgene, such as the ROSA26 strain. In the course of our investigations, we examined β-gal activity in bone tissue from genetically normal mice using standard detection methodology and found very high endogenous activity in bone-resorbing osteoclasts. This was true in frozen, paraffin, and glycol methacrylate sections. X-gal staining colocalized with the osteoclast marker, tartrate-resistant acid phosphatase (TRAP). β-gal activity was present in osteoclasts in long bones, in the mandible, and in both neonatal and more mature animals. We present this brief article as a caution to those testing genetic models of skeletal gene expression using β-gal as a marker gene.