基于独立元分析和联合小波熵检测多导联ECG信号的QRS

QRS波群的准确定位是ECG信号自动分析的基础。为提高QRS检测率,提出一种基于独立元分析（ICA）和联合小波熵（CWS）检测多导联ECG信号QRS的算法。ICA算法从滤波后的多导联ECG信号中分离出对应心室活动的独立元;然后对各独立元进行连续小波变换（CWT）,重构小波系数的相空间,结合相空间中的QRS信息对独立元排序;最后检测排序后独立元的CWS得到QRS信息。实验对St.Petersburg12导联心率失常数据库及64导联犬心外膜数据库测试,比较本文算法与单导联QRS检测算法和双导联QRS检测算法的性能。结果表明,该文算法的性能最好,检测准确率分别为99.98%和100%。     

血清降钙素原、C反应蛋白/白蛋白比值联合尿白细胞酯酶对复杂性肾结石患者经皮肾镜碎石术后发生尿路感染的预测价值分析

摘要 目的：探讨血清降钙素原（PCT）、C反应蛋白（CRP）/白蛋白（ALB）比值联合尿白细胞酯酶（LEU）对复杂性肾结石患者经皮肾镜碎石术（PCNL）后发生尿路感染的预测价值。方法：选择2015年3月-2021年6月我院收治的128例行PCNL的复杂性肾结石患者作为观察对象,术后定期随访,统计尿路感染情况,根据是否发生术后尿路感染分为尿路感染组和非尿路感染组。比较两组PCT水平、LEU,CRP/ALB比值及其他临床资料。采用多因素Logistic回归分析术后尿路感染的危险因素,绘制受试者工作特征（ROC）曲线,分析PCT、CRP/ALB比值、LEU单独以及联合检测预测术后尿路感染的价值。结果：尿路感染组的血清PCT、CRP/ALB高于非尿路感染组（P<0.05）。尿路感染组的LEU呈阳性,而非尿路感染组的LEU呈阴性。两组在既往泌尿道手术史、手术时间、导尿管留置时间、住院时间、术前尿路感染、结石负荷、使用>3种抗菌药物、合并肾功能障碍、术中通道类型、术前血糖水平方面对比有统计学差异（P<0.05）。既往泌尿道手术史、手术时间≧100 min、导尿管留置时间≧7 d、术前尿路感染、结石负荷≧1000 mm2、术前血糖水平高、合并肾功能障碍是复杂性肾结石患者PCNL后发生尿路感染的危险因素（P<0.05）。PCT、CRP/ALB、LEU单独预测PCNL后尿路感染的曲线下面积（AUC）分别为0.712（0.476～0.944）、0.686（0.436～0.931）、0.836（0.753～0.918）,三者联合预测PCNL后尿路感染的AUC为0.879（0.785～0.972）,均高于PCT、CRP/ALB、LEU单独预测。结论：复杂性肾结石患者PCNL后发生尿路感染的影响因素较多,包括导尿管留置时间、住院时间、结石负荷等,且PCNL后发生尿路感染患者PCT、CRP/ALB比值偏高,LEU呈阳性,三者可能作为PCNL后发生尿路感染的生物标记物。     

A mathematical model of lateral flow bioreactions applied to sandwich assays

Lateral flow (LF) biodetectors facilitate low-cost, rapid identification of various analytes at the point of care. The LF cell consists of a porous membrane containing immobilized ligands at various locations. Through the action of capillary forces, samples and reporter particles are transported to the ligand sites. The LF membrane is then scanned or probed, and the concentration of reporter particles is measured. A mathematical model for sandwich assays is constructed and used to study the performance of the LF device under various operating conditions. The model provides insights into certain experimental observations including the reduction in the level of the detected signal at high target analyte concentrations. Furthermore, the model can be used to test rapidly and inexpensively various operating conditions, assist in the device's design, and optimize the performance of the LF device.     

应用双光子显微镜和流式细胞仪定性及定量确定小鼠巨噬细胞的吞噬功能

建立了流式细胞仪和双光子激光共聚焦荧光显微镜进行定性和定量检测小鼠巨噬细胞吞噬鸡红细胞的方法,并同传统光学显微镜细胞化学染色观察方法相比较,探讨其检测巨噬细胞吞噬效应的优越性。常规方法获取小鼠腹腔和脾脏巨噬细胞,制备巨噬细胞悬液。常规制备鸡红细胞,计数并调整活细胞数,用5-二醋酸羧基荧光素琥珀酸单胞菌酯(5-carboxyfluorescein diacetate succinimidyl ester,CFSE)染色,与巨噬细胞共温育一定时间后,小鼠巨噬细胞特异性荧光抗体F4/80标记巨噬细胞。应用流式细胞仪检测巨噬细胞中CFSE阳性百分率来表示巨噬细胞吞噬率;应用双光子显微镜观察被吞噬的CFSE阳性鸡红细胞动态分布情况。同时,采用传统光学显微镜吉姆萨染色观察巨噬细胞吞噬百分率。结果显示,流式细胞仪结合双光子显微镜检测巨噬细胞吞噬率与传统的显微镜计数法比较,两者有明显的正相关性。双光子显微镜和流式细胞仪可以定性与定量检测巨噬细胞吞噬功能,该方法具有灵敏、快捷、重复性好以及准确率高的特点,是进行免疫学研究的可行方法。     

The denitrification potential and density of denitrifying bacteria in the bottom sediments of Matupi Harbor (Papua New Guinea)

The denitrification potential and density of denitrifying bacteria were determined in suboxidized sediments of Matupi Harbor (Papua New Guinea). The sediments were characterized by low denitrification potentials, not exceeding 0.8 nM/(g h). The maximum density of denitrifying bacteria was recorded in the upper sediment horizons and was 10⁴ cells/g of wet ground.     

The value of small habitat islands for the conservation of genetic variability in a steppe grass species

The habitat loss and fragmentation due to agricultural land-conversion affected the steppe throughout its range. In Ukraine, 95% of steppe was destroyed in the last two centuries. Remaining populations are confined to few refuges, like nature reserves, loess ravines, and kurgans (small burial mounds), the latter being often subject to destruction by archeological excavations.Stipa capillata L. is a typical grass species of Eurasian steppes and extrazonal dry grasslands, that was previously used as a model species in studies on steppe ecology. The aim of our research was to assess genetic diversity of S. capillata populations within different types of steppe refuges (loess ravines, biosphere reserve, kurgan) and to evaluate the value of the latter group for the preservation of genetic diversity in the study species.We assessed genetic diversity of 266 individuals from 15 populations (nine from kurgans, three from loess ravines and three from Askania-Nova Biosphere Reserve) with eight Universal Rice Primers (URPs).Studied populations showed high intra-population variability (I: 0.262–0.419, PPB: 52.08–82.64%). Populations from kurgans showed higher genetic differentiation (Φ_ST = 0.247) than those from loess ravines (Φ_ST = 0.120) and the biosphere reserve (Φ_ST = 0.142). Although the diversity metrics were to a small extent lower for populations from kurgans than from larger refugia we conclude that all studied populations of the species still preserve high genetic variability and are valuable for protection. To what extent this pattern holds true under continuous fragmentation in the future must be carefully monitored.     

The PIRLA project: Paleoecological investigations of recent lake acidification

The PIRLA project is a broadly interdisciplinary paleolimnological investigation of five to fifteen comparable watershed/lake systems from each of four low-alkalinity regions in North America that are currently receiving acid deposition. The areas are the Adirondack Mountains (N.Y.), northern New England, northern Great Lakes states, and northern Florida. The primary objective of the study is to provide a detailed reconstruction of the recent acidification histories of a representative suite of lakes from each of the regions. The study will increase our understanding of the timing, rates, and magnitude of acidification (and other chemical changes), and the regional and inter-regional patterns of lake acidification.     

The fate of15N labeled nitrogen applied to mature citrus trees

Summary The efficiency and balance of nitrogen from one year's application was studied in a long-term fertigation experiment. Enriched nitrogen fertilizer, K¹⁵NO₃, was applied to a 22-year-old Shamouti orange tree with a history of high N applications (N₃) and to an N-starved tree (N₁). The distribution of N in the different parts of the trees and in the soil was determined after the experimental trees were excavated. Similar total recovery of the labeled fertilizer N was found in the trees and soil in both treatments (N₁−61.7% N₃−56%). However, the distribution between tree and soil was different. The amount of recovered residual fertilizer in the soil was much larger in the N₃ treatment than in N₁. The highest percentage of fertilizer N was found in the new organs,i.e. fruits, twigs and leaves. The roots and branches took up only 6–14% from the labeled fertilizer. Only 20.9% of the leaf N and 23.4% of the fruit N in the N₃ tree originated in the labeled fertilizer, indicating translocation of N from older parts of the tree to new growth. Evidence was found of storage of N in the wooded branches, while the roots contained a surprisingly small part of labeled fertilizer. Contribution 1599E.     

不同检验方法在尿路感染诊断中的临床价值

目的探讨尿干化学分析法与尿沉渣分析法在诊断患者尿路感染中的临床价值。方法收集2017年9月至2018年7月于重庆市黔江中心医院就诊的疑似尿路感染患者尿液标本400份,分别利用尿干化学分析及尿沉渣分析法检测标本,比较不同检测分析法的灵敏度、特异度、阳性预测值及阴性预测值。结果尿干化学分析法检测阳性率为42.25%(169/400),尿沉渣分析法检测阳性率为32.75%(131/400),尿沉渣分析法检测阳性率明显低于尿干化学分析法(X~2=7.7010,P=0.0070),差异有统计学意义。尿干化学分析法检测白细胞计数阳性率为25.25%(101/400)、亚硝酸盐阳性率为17.00%(68/400);尿沉渣分析法检测白细胞计数阳性率为24.25%(97/400),细菌计数阳性率为8.50%。尿沉渣分析法检测白细胞计数阳性率与尿干化学分析法比较,差异无统计学意义(X~2=0.1070,P=0.8060)。尿干化学分析法灵敏度为72.95%,特异度为90.67%,阳性预测值为89.35%,阴性预测值为75.76%;尿沉渣分析法灵敏度为57.97%,特异度为94.30%,阳性预测值为91.60%,阴性预测值为67.66%。尿干化学分析法检测的灵敏度及阴性预测值明显高于尿沉渣分析法(X~2=10.2660,P=0.0020;X~2=3.9930,P=0.0480),差异具有统计学意义。结论尿干化学分析法及尿沉渣分析法均有一定的临床诊断价值。可针对两种检测方法的联合应用进一步研究,以期提高尿路感染诊断的灵敏度及特异度。     

The effect of sediment chemistry on the successful establishment of wild rice (Zizania palustris L.) in northern Saskatchewan water bodies

Sediment chemistry of productive and non-productive wild rice sites was measured over 3 consecutive growing seasons Although productive sites differed from non-productive sites in terms of pH, N and potential N mineralization, redox potential was considered to be the major factor which distinguished these site classes. Productivity of wild rice in commercial stands could not be consistently correlated to sediment nutrients. However, growth appeared to be restricted in strongly reduced sediments and sediment Eh is considered to be a rapid, accurate method of estimating site potential. Good growth is expected if Eh is above –150 mB while poor growth is expected when Eh drops below –200 mV. Eh values of sediment samples changed as storage time increased. It is therefore recommended that Eh is recorded on-site.