Real‐time PCR detection of Erwinia amylovora on blossoms correlates with subsequent fire blight incidence

Fire blight is the most devastating bacterial disease of rosaceous plants. Forecasting fire blight infections is important to allow for countermeasures that reduce economic damage in pome fruit production. Current computerized forecasting models are solely based on physical factors such as temperature and moisture, but not on the actual presence of the pathogen Erwinia amylovora. Although the inoculum concentration is considered to be crucial for infection and disease outbreak, most current approaches used for identification of fire blight inoculum including morphological, biochemical, serological, and DNA‐based methods are nonquantitative. Based on a real‐time PCR approach previously published, an improved protocol to be used directly on whole bacteria in the field is described. The method allows for early detection and quantification of the pathogen prior to the occurrence of first symptoms. There is a clear correlation between bacterial abundance and subsequent disease development. However, in some cases, no disease symptoms could be observed despite a pathogen load of up to 3·4 × 10⁶ cells per blossom. Integration of the amount of pathogen detected into refined prediction algorithms may allow for the improvement of applied forecasting models, finally permitting a better abatement of fire blight.     

基于数量化理论和BP神经网络的滑坡体积预测

[目的]探讨数量化理论Ⅲ和BP神经网络在滑坡中综合应用的效果,为滑坡体积的预测提供一种新的思路。[方法]采用数量化理论Ⅲ分析滑坡体积的影响因素及其耦合作用强度,并结合其分析结果,将次要因素和强耦合程度样本进行剔除,再依据其剔除的不同阶段构建3种滑坡体积的BP神经网络预测模型。[结果]滑坡体积的主要影响因素是坡角、坡向、植被覆盖率和坡高,次要影响因素是岩层倾角、斜坡高程和岩层倾向因素,且在不同样本中,体积影响因素之间的耦合程度具有一定的差异。[结论]该预测方法可行,对次要因素和强耦合程度样本的剔除,提高了预测精度。     

评价回归模型拟合效果的数量化方法

回归模型模拟的效果直接影响其预测结果的精确性，针对残差分析法检验模型似合效果的局限性，采用数量化方法进行检验，不仅综合分析的模拟效果，而且可以直接比较模型间的拟合效果，并为建立拟合效果好的新模型提供了充分的依据。     

A New,Quick, and Simple Protocol to Evaluate Microalgae Polysaccharide Composition

In this work, a new methodological approach, relying on the high specificity of enzymes in a complex mixture, was developed to estimate the composition of bioactive polysaccharides produced by microalgae, directly in algal cultures. The objective was to set up a protocol to target oligomers commonly known to be associated with exopolysaccharides’ (EPS) nutraceutical and pharmaceutical activities (i.e., rhamnose, fucose, acidic sugars, etc.) without the constraints classically associated with chromatographic methods, while maintaining a resolution sufficiently high to enable their monitoring in the culture system. Determination of the monosaccharide content required the application of acid hydrolysis (2 M trifluoroacetic acid) followed by NaOH (2 M) neutralization. Quantification was then carried out directly on the fresh hydrolysate using enzyme kits corresponding to the main monosaccharides in a pre-determined composition of the polysaccharides under analysis. Initial results showed that the enzymes were not sensitive to the presence of TFA and NaOH, so the methodology could be carried out on fresh hydrolysate. The limits of quantification of the method were estimated as being in the order of the log of nanograms of monosaccharides per well, thus positioning it among the chromatographic methods in terms of analytical performance. A comparative analysis of the results obtained by the enzymatic method with a reference method (high-performance anion-exchange chromatography) confirmed good recovery rates, thus validating the closeness of the protocol. Finally, analyses of raw culture media were carried out and compared to the results obtained in miliQ water; no differences were observed. The new approach is a quick, functional analysis method allowing routine monitoring of the quality of bioactive polysaccharides in algal cultures grown in photobioreactors.     

地表微地形测量及定量化方法研究综述

地表微地形测量是地表粗糙度定量化的基础,对地表形态动态监测、水文过程模拟以及土壤侵蚀过程模型的构建具有重要意义。目前,微地形测量方法主要分为接触式和非接触式2大类,前者包括测针法、链条法、差分GPS法等,后者包括超声波测距法、红外线传感器法、结构光激光扫描法、激光测距扫描法、三维激光扫描仪法、近景摄影测量法等。在全面回顾各方法原理、优缺点及其应用的基础上,分析地表粗糙度定量化常用方法：统计方法指数、地统计学指数和分形及多重分形模型。认为：1）差分GPS法、结构光激光扫描法、三维激光扫描仪法和近景摄影测量法将在亚毫米一,厘米级地表微地形测量及地表粗糙度多尺度特征研究中发挥重要作用,同时简单、方便的测针法可能在野外测量中依然占据主导地位;2）以地表微地形测量技术为基础,在土壤侵蚀过程模型中亟需形成一套完整的“测量一定量化一模型应用”范式,同时应加强对地表微地形空间异质性和各向异性的研究,发展新的统一的地表粗糙度定量化方法。     

水稻GA20ox-2基因mRNA的TaqMan荧光定量RT-PCR检测

 成功建立了一项基于TaqMan 实时荧光定量的RT-PCR技术,定量分析水稻半矮化关键基因之一GA20ox-2转录水平。该技术体系中重组质粒标准品的制备方法具有很好的实用性;质粒标准品对基因GA20ox-2表达的实时定量准确、可靠、便捷。标准曲线表明,所建立的GA20ox-2基因mRNA表达实时荧光定量PCR检测方法,特异性好,灵敏度高,可达102拷贝;线性范围广,可达102～107拷贝;扩增效率高（E=100.3%）;稳定性、重复性好,可靠性高,批内和批间变异系数仅分别为0.12%～0.31%和0.21%～0.34%;循环阈值与PCR 体系中起始模板量的对数值之间有着良好的线性关系（^r＝0.999）,可对GA20ox 2基因表达进行准确实时定量。     

Spatially resolved quantification of agrochemicals on plant surfaces using energy dispersive X‐ray microanalysis

BACKGROUND: In the present study the principle of energy dispersive X‐ray microanalysis (EDX), i.e. the detection of elements based on their characteristic X‐rays, was used to localise and quantify organic and inorganic pesticides on enzymatically isolated fruit cuticles. Pesticides could be discriminated from the plant surface because of their distinctive elemental composition. RESULTS: Findings confirm the close relation between net intensity (NI) and area covered by the active ingredient (AI area). Using wide and narrow concentration ranges of glyphosate and glufosinate, respectively, results showed that quantification of AI requires the selection of appropriate regression equations while considering NI, peak‐to‐background (P/B) ratio, and AI area. The use of selected internal standards (ISs) such as Ca(NO₃)₂ improved the accuracy of the quantification slightly but led to the formation of particular, non‐typical microstructured deposits. The suitability of SEM‐EDX as a general technique to quantify pesticides was evaluated additionally on 14 agrochemicals applied at diluted or regular concentration. CONCLUSION: Among the pesticides tested, spatial localisation and quantification of AI amount could be done for inorganic copper and sulfur as well for the organic agrochemicals glyphosate, glufosinate, bromoxynil and mancozeb. Copyright © 2009 Society of Chemical Industry     

基于色彩要素量化分析的郑州市龙子湖滨水公园植物群落景观评价

色彩丰富的季相植物景观能提供丰富的视觉感受,营造良好生活环境。以郑州市龙子湖滨水公园为研究对象,基于季节性色彩量化分析,采用AHP法与SBE法对选定的20个植物群落进行植物景观色彩评价,分析影响植物景观色彩质量的主要因子。结果表明,样地植物种类多样,色彩丰富度较高,对比度较低,景观整体色相值偏低,饱和度及明度适中,色彩特征鲜明;AHP法与SBE法虽侧重点不同但二者评价结果具有一致性,可共同应用于景观评价中;根据评价模型可知色彩数量C¹、明度指数C⁸是影响植物景观美景度的主要因子。本次研究结果可为城市园林绿化植物种类的选择及景观塑造提供理论支撑。     

Quantifying fishing effort: a synthesis of current methods and their applications

The need to accurately quantify fishing effort has increased in recent years as fisheries have expanded around the world and many fish stocks and non‐target species are threatened with collapse. Quantification methods vary greatly among fisheries, and to date there has not been a comprehensive review of these methods. Here we review existing approaches to quantify fishing effort in small‐scale, recreational, industrial, and illegal, unreported and unregulated (IUU) fisheries. We present the strengths and limitations of existing methods, identifying the most robust methods and the critical knowledge gaps that must be addressed to improve our ability to quantify and map fishing effort. Although identifying the ‘best’ method ultimately depends on the intended application of the data, in general, quantification methods that are based on information on gear use and spatial distribution offer the best approaches to representing fishing effort on a broad scale. Integrating fisher’s knowledge and involving fishers in data collection and management decisions may be the most effective way to improve data quality and accessibility.     

Computational fluid dynamics characterization of a novel mixed cell raceway design

Computational fluid dynamics (CFD) analysis was performed on a new type of mixed cell raceway (MCR) that incorporates longitudinal plug flow using inlet and outlet weirs for the primary fraction of the total flow. As opposed to conventional MCR’s wherein vortices are entirely characterized by the boundary conditions at inlet nozzles and outlet center drains in the center of each cell, the new MCR design can develop a wider variety of fluid behaviors due to the additional boundary conditions at the inlet and outlet walls where the weirs are placed. In this study, we investigated how the primary longitudinal flow would affect vortex formations in the cells by designing three different MCR models and simulating three major cases for each model. Through this process, performances of two numerical CFD models (transition k-kl-ω vs. k-ε) were compared, along with two vortex quantification methods (Q-criterion vs. a proposed method). We found that the k-kl-ω CFD model more accurately predicted vortex formation than the k-ε model. The three MCR models differed only by weir geometry or drain size, in order to see their individual influence on cell vortex formation. Each case had its own unique weir flow rate and center drain loading rate values that combined to a total flow rate resulting in 15-min hydraulic retention time (HRT) for the MCR. The ratio of (expressed as percentage) of center drain loading rate to total flow rate (R = 7.5%, 12.5%, and 20.1%.) was defined to establish a relationship between R and vortex strength or size. Simulations demonstrated that inlet weir aspect ratio impacted cell vortex formation and strength. Unlike weir geometry effects, the drain size had non-significant impacts on fluid behavior other than the velocity very near the drains. While R did have positive correlations with vortex strength, vortex size, and self-cleaning performance, an R of 20.1% was sufficient to create uninterrupted vortex formations. Too low of a center drain rate or R value can result in lack of any meaningful cell vortex formation which then obviates any self-cleaning action in an MCR. Our key finding through extensive computational analysis was that an R value of 20% was required in order to maintain effective vortex formation. Expressed more explicitly, this can be described as maintaining a center drain loading rate of 0.010094 m³/s per cell (160 gpm), which correspond to unit loading rates of 16.3 lpm/m² per cell (0.40 gpm/ft² per cell).