Which similarity measure to use in network analysis: Impact of sample size on phi correlation coefficient and Ochiai index

Some networks are explicit where members make direct connections (e.g. Facebook network), whereas other networks are implicit (e.g. co-citation network) in which an edge between two nodes is inferred using a similarity index. Choosing the right index to infer connections in an implicit/inferred network is important because conclusions can be biased if a network does not represent true relationships. In this study, we compared two indexes: Phi Correlation Coefficient (PCC) and Ochiai Coefficient (Och) based on their sensitivity to the sample size of transactions from where the network is inferred. For demonstration, we used an implicit network, called a comorbidity network, developed from health records of 22.1 million patients. The networks were compared based on their overall topologies and node centralities. Results showed that the network formed using Och was more robust to the sample size than PCC. The network using Och followed a small-world topology irrespective of the sample size whereas the structure of a network using PCC was inconsistent. Regarding node centralities, the betweenness centrality was most affected by the sample size. Our results lead us to recommend Och over PCC.     

The effects of different syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin

Introductıon:

We evaluated the effect of different syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin.

Materials and methods:

In this multi-step experimental study, percent dilution ratios (PDRs) and final heparin concentrations (FHCs) were calculated by gravimetric method for determining the effect of syringe volume (1, 2, 5 and 10 mL), needle size (20, 21, 22, 25 and 26 G) and sample volume (0.5, 1, 2, 5 and 10 mL). The effect of different PDRs and FHCs on blood gas and electrolyte parameters were determined. The erroneous results from nonstandardized sampling were evaluated according to RiliBAK’s TEa.

Results:

The increase of PDRs and FHCs was associated with the decrease of syringe volume, the increase of needle size and the decrease of sample volume: from 2.0% and 100 IU/mL in 10 mL-syringe to 7.0% and 351 IU/mL in 1 mL-syringe; from 4.9% and 245 IU/mL in 26G to 7.6% and 380 IU/mL in 20 G with combined 1 mL syringe; from 2.0% and 100 IU/mL in full-filled sample to 34% and 1675 IU/mL in 0.5 mL suctioned sample into 10 mL-syringe. There was no statistical difference in pH; but the percent decreasing in pCO₂, K⁺, iCa²⁺, iMg²⁺; the percent increasing in pO₂ and Na⁺ were statistical significance compared to samples full-filled in syringes. The all changes in pH and pO₂ were acceptable; but the changes in pCO₂, Na⁺, K⁺ and iCa²⁺ were unacceptable according to TEa limits except fullfilled-syringes.

Conclusions:

The changes in PDRs and FHCs due nonstandardized sampling in syringe washed with liquid heparin give rise to erroneous test results for pCO₂ and electrolytes.     

The maximal value of a zipf size variable: Sampling properties and relationship to other parameters

Because the Zipf size-frequency distribution is used so often as a mathematical model for bibliometric variables, it is important that the relationships among its parameters and its sampling properties be understood by investigators in this field. This paper examines these relationships and properties. In addition, it provides tables for the sampling distribution of the maximal value of a finite Zipf distribution and an approximation formula for confidence intervals. Confidence limits for the maximal value in a number of previous studies are determined.     

Laminated microfluidic system for small sample protein analysis

We describe a technology based on lamination that allows for the production of highly integrated 3D devices suitable for performing a wide variety of microfluidic assays. This approach uses a suite of microfluidic coupons (“microfloupons”) that are intended to be stacked as needed to produce an assay of interest. Microfloupons may be manufactured in paper, plastic, gels, or other materials, in advance, by different manufacturers, then assembled by the assay designer as needed. To demonstrate this approach, we designed, assembled, and characterized a microfloupon device that performs sodium-dodecyl-sulfate polyacrylamide gel electrophoresis on a small sample of protein. This device allowed for the manipulation and transport of small amounts of protein sample, tight injection into a thin polyacrylamide gel, electrophoretic separation of the proteins into bands, and subsequent removal of the gel from the device for imaging and further analysis. The microfloupons are rugged enough to handle and can be easily aligned and laminated, allowing for a variety of different assays to be designed and configured by selecting appropriate microfloupons. This approach provides a convenient way to perform assays that have multiple steps, relieving the need to design highly sophisticated devices that incorporate all functions in a single unit, while still achieving the benefits of small sample size, automation, and high speed operation.     

Sampling expansions and generalized translation invariance

The generalized sampling theorem of Kramer is derived and interpreted in the context of the theory of linear systems satisfying a generalized form of translation invariance. The results are extended to the form of expansions developed by Papoulis and by Campbell.     

Sampling and control of switched linear systems

In this paper, we address the sampling and control issues for switched linear systems. Under synchronous switching and piecewise constant control, a continuous-time switched system is naturally related to a discrete-time sampled-data system. We prove that, with almost any sampling rate, the controllable subspace will be preserved for a switched linear system. We also investigate the possibility of achieving controllability using regular switching mechanisms. We show that, to achieve controllability for a switched linear system, it is sufficient to use cyclic and synchronous switching paths and constant control laws.     

区域人才开发指数的实证研究——基于广东省的样本调查与分析

旨在构建出一套能够反映中国各地市人才开发能力与水平的指数评价体系。1 012份调查问卷的因子分析结果表明,区域人才开发由科技开发、配置开发、教育开发、健康开发4个基本维度构成,共涵盖17个具体指标。对广东省21个地级市数据进行指数体系实践评估,发现珠三角、粤北、粤西、粤东地区的人才开发情况具有地区内相似性以及地区间差异性,且中心效应较为明显;并将其与滞后1期的人才增长与经济发展数据进行相关性检验,结果显示该指数具有较高的有效性。基于指数评价结果,借助人才开发的理论与方法,从人才“引、用、育、留”角度为区域人才开发提出建议。     

规模、R&D与绩效:对我国软件产业的实证分析

本文在国家统计局公布的2002年度我国软件开发企业统计资料和我们所收集的杭州软件企业数据基础上,对中国软件产业是否存在着可观测的规模效应、中国软件产业研究开发(R&D)活动对绩效是否存在着一致性的正向影响这两个问题进行了实证研究。研究表明,就规模对企业绩效的影响而言,企业规模对于产出率存在着一致性的正向影响,但对于利润率却未表现出显著相关性;在研发强度对企业绩效的影响上,我们发现研发强度对利润率存在着显著性的负向影响,并且在一定程度上对于产出率也存在着负向影响。在此基础上,我们就这些发现的政策含义进行了讨论。     

浇注系统初始尺寸对Moldflow平衡分析效果的影响

以一模八腔浇注系统为倒,对比分析了两组浇注系统初始尺寸经过Moldflow平衡分析后的平衡效果,通过分析结果的对比得出：不同的初始浇注系统尺寸经过Moldflow平衡分析后将得到不同的平衡效果,适当增加由公式a1=L1a3^3/L3a3^2＋2a4^2L4得到的流道1的直径,有利于浇注系统达到平衡。     

关于信号处理中采样和谱分析的几点讨论

本文分析目前信号处理类课程中信号采样和谱分析中存在的问题。文章结合实验过程的问题和典型信号的分析,从三个方面入手阐述了实验中信号频谱的显示、分析;介绍了数字信号滤波时时域分析法和频域分析法应注意的问题以及随机信号自相关分析和功率谱分析的方法和注意事项。本文对于采样定理和谱分析基本理论了解不清的同学将会起到一定的指导作用。     

Sampling method for linear system reduction

A new method for obtaining reduced order models for single-input-single-output, continuous-time systems is presented. The proposed algorithm matches the transfer functions of the original and the reduced system at 2M points where M is the order of the reduced model. The location of these points depends on a parameter which can be selected to control the accuracy of the approximation and stability. Numerical examples and comparisons with other methods of model reduction are given.     

航空发动机参数采集系统的设计与研究

在对国内外现役飞机电子座舱显示系统研究的基础上,设计了一种DSP+FPGA结构的数据采集系统。能够采集航空发动机的各项参数,并且可应用于具有数字多功能显示器的新型电子座舱系统。系统有效的实现了各种信号的采集以及对频率信号的滤波。     

小儿氨酚黄那敏颗粒评价性抽验结果及质量评价

目的:对广西区内不同生产企业生产的18个批次小儿氨酚黄那敏颗粒质量进行考察,评价其质量现状以及分析存在的问题.方法:采用现行质量标准检验方法与探索性研究相结合的方法对样品进行测定,统计分析测定结果.结果:按现行质量标准检验方法检验18批次样品,仅2批检出性状不合格.探索性研究弥补了现行质量标准的缺失,发现了样品性状的改变可能造成样品杂质增加、以及样品中马来酸氯苯那敏含量不均匀等现象.结论:目前区内的小儿氨酚黄那敏颗粒产品质量基本能符合现行质量标准的要求,但探索性研究显示现行标准仍存在缺陷,需要进一步完善从而全面反映产品质量,保障药品的安全有效性.     

抽样检验方案信息量的研究

抽样检验不仅是一个统计推断过程 ,又是一个信息过程。在样本检验过程中 ,不断产生各类信息 ,当信息积累到一定程度时 ,便可以对总体状况作出判断。这种以信息量为判断依据的抽样检验 ,强调了每一个体所产生信息量的作用 ,提高了检验过程中的敏感度。     

Comparison of protein precipitation methods for sample preparation prior to proteomic analysis of Chinese hamster ovary cell homogenates

BackgroundChinese hamster ovary (CHO) cells are the workhorse for obtaining recombinant proteins. Proteomic studies of these cells intend to understand cell biology and obtain more productive and robust cell lines for therapeutic protein production in the pharmaceutical industry. Because of the great importance of precipitation methods for the processing of samples in proteomics, the acetone, methanol-chloroform (M/C), and trichloroacetic acid (TCA)-acetone protocols were compared for CHO cells in terms of protein recovery, band pattern resolution, and presence on SDS-PAGE.ResultsHigher recovery and similar band profile with cellular homogenates were obtained using acetone precipitation with ultrasonic bath cycles (104.18 ± 2.67%) or NaOH addition (103.12 ± 5.74%), compared to the other two protocols tested. TCA-acetone precipitates were difficult to solubilize, which negatively influenced recovery percentage (77.91 ± 8.79%) and band presence. M/C with ultrasonic homogenization showed an intermediate recovery between the other two protocols (94.22 ± 4.86%) without affecting protein pattern on SDS-PAGE. These precipitation methods affected the recovery of low MW proteins (< 15 kDa).ConclusionsThese results help in the processing of samples of CHO cells for their proteomic study by means of an easily accessible, fast protocol, with an almost complete recovery of cellular proteins and the capture of the original complexity of the cellular composition. Acetone protocol could be incorporated to sample-preparation workflows in a straightforward manner and can probably be applied to other mammalian cell lines as well.How to cite: Pérez-Rodriguez S, Ramírez OT, Trujillo-Roldán MA et al. Comparison of protein precipitation methods for sample preparation prior to proteomic analysis of Chinese hamster ovary cell homogenates. Electron J Biotechnol 2020;48. https://doi.org/10.1016/j.ejbt.2020.09.006.     

全自动取制样系统运行问题及对策研究

文章从商品规格、设备的稳定性、人员素质、职业安全等角度分析了全自动取制样系统运行中可能出现的问题,并提出了准确判断货物特性、注重设备的维护保养、提升员工的能力和素质、加强人员的职业健康安全教育及检查等措施,对做好全自动取制样系统工作具有重要的参考意义.