院内获得性肺炎呼吸道病毒病原分析

目的了解当前小儿院内获得性肺炎（HAP）病毒病原学的状况。方法收集251例HAP的患儿资料,对其中做痰液病毒分离,获得合胞病毒（RSV）、流感病毒、副流感病毒病原学检测阳性结果的病例进行分析。结果251例HAP患儿中141例做了痰液病毒检测,其中阳性67例,病毒检出率为47.52%（67/141）,其中以RSV肺炎最为多见。67例病毒性HAP均以喘息为主要临床表现,多数不发热或低热,少部分可以表现为高热,血常规、CRP基本正常。67例中22例有明确的诱因,其中以使用激素最为多见。67例患儿均治疗有效。结论251例住院患儿中HAP病毒检出以呼吸道合胞病毒为主,预后均良好。     

Extending Mosaic Displays: Marginal,Conditional, and Partial Views of Categorical Data

Abstract

This article first illustrates the use of mosaic displays for the analysis of multiway contingency tables. We then introduce several extensions of mosaic displays designed to integrate graphical methods for categorical data with those used for quantitative data. The scatterplot matrix shows all pairwise (bivariate marginal) views of a set of variables in a coherent display. One analog for categorical data is a matrix of mosaic displays showing some aspect of the bivariate relation between all pairs of variables. The simplest case shows the bivariate marginal relation for each pair of variables. Another case shows the conditional relation between each pair, with all other variables partialled out. For quantitative data this represents (a) a visualization of the conditional independence relations studied by graphical models, and (b) a generalization of partial residual plots. The conditioning plot, or coplot shows a collection of partial views of several quantitative variables, conditioned by the values of one or more other variables. A direct analog of the coplot for categorical data is an array of mosaic plots of the dependence among two or more variables, stratified by the values of one or more given variables. Each such panel then shows the partial associations among the foreground variables; the collection of such plots shows how these associations change as the given variables vary.     

Visualizing Loglinear Models

Abstract

We consider visual methods based on mosaic plots for interpreting and modeling categorical data. Categorical data are most often modeled using loglinear models. For certain loglinear models, mosaic plots have unique shapes that do not depend on the actual data being modeled. These shapes reflect the structure of a model, defined by the presence and absence of particular model coefficients. Displaying the expected values of a loglinear model allows one to incorporate the residuals of the model graphically and to visually judge the adequacy of the loglinear fit. This procedure leads to stepwise interactive graphical modeling of loglinear models. We show that it often results in a deeper understanding of the structure of the data. Linking mosaic plots to other interactive displays offers additional power that allows the investigation of more complex dependence models than provided by static displays.     

“新冠肺炎”疫情环境下实验教学形式多样化的运用

实验教学的主要授课形式在科技的发展下已经变得多样化,实验课程不仅是学生实践与研究的基础,也是从知识理解向科学研究的转化,在教学中占据着不可缺少的地位。全国“新型冠状病毒肺炎”(简称“新冠肺炎”)疫情的爆发极具偶然性,给实验教学带来了前所未有的压力。在突发困难面前,通过直/录播线上教学、数字化资源的运用、授课形式的转变、评价体系的调整等一系列应急措施,在实验教学中取得了较好的效果。这不仅与理论课程形成了良好的配合,充分保障了实验教学的内容和质量,而且大大促进了学生的自主学习能力,还引发了对高校实验教学发展的思考,即,不应在疫情等特殊情况下才思考求变,实验教学应坚持不懈地着力于学生培养和持续改革。     

Effects of the AlN nucleation layer thickness on the crystal structures of an AlN epilayer grown on the 6H-SiC substrate

The influence of the LT-AlN(NL) growth times on the mosaic structure parameters of the AlN layer grown on the LT-AlN(NL)/6H-SiC structures as well as the dislocation densities and the strain behaviours in the AlN epilayers has been investigated using XRD measurements. The growth times of the LT-AlN(NL) were changed to 0, 60, 120, 180, and 240?s. We observed that the mosaic structure parameters of the AlN epilayers were slightly affected by the LT-AlN(NL) growth times. However, the dislocation densities in the AlN layer are affected by the growth times of the LT-AlN(NL) layer. The highest edge dislocation density (5.48?×?10¹⁰?±?2.3?×?10⁹?cm^?2) was measured for the sample in which 120?s grown LT-AlN(NL) was used. On the other hand, highest screw type dislocation density (1.21?×?10¹⁰?±?1.7?×?10⁹?cm^?2) measured in the sample E that contains 240?s growth LT-AlN(NL). The strain calculation results show that the samples without LT-AlN(NL) suffered maximum compressive in-plane strain (?10.9?×?10^?3?±?1.8?×?10^?4), which can be suppressed by increasing the LT-AlN(NL) growth times. The out-of-plane strain also has a compressive character and its values increase with LT-AlN(NL) growth times between 60 and 180?s. Same out-of-plane strain values were measured for the LT-AlN(NL) growth times of 180 and 240?s. Furthermore, the form of the biaxial stress in the AlN epilayer changed from compressive to tensile when the LT-AlN(NL) growth times were greater than 120?s.     

棚龄对大棚种植黄瓜品质影响的傅里叶变换红外光谱研究

蔬菜大棚种植对蔬菜供应发挥着重要的作用，蔬菜大棚棚龄会影响蔬菜的产量和质量。以不同棚龄（1年、10年和18年）的黄瓜为对象，利用漫反射傅里叶变换中红外光谱，通过解析黄瓜的光谱特征峰，探究棚龄对黄瓜品质的影响。研究表明，黄瓜的多糖和蛋白质组分在3个棚龄呈现先增加后降低的趋势，10年棚龄种植的黄瓜多糖和蛋白质组分显著高于1年和18年的黄瓜多糖和蛋白质组分。高的棚龄（即10年和18年）显著增加了黄瓜的木质素组分。木质素组分主要分布于黄瓜皮中，增加木质素组分会降低黄瓜的食用口感。另外，黄瓜中各有机组分的比值能综合反映不同棚龄下黄瓜的品质。18年棚龄的黄瓜多糖与蛋白质组分的比值以及多糖与木质素组分的比值低于1年和10年棚龄的黄瓜各有机组分的比值，表明1年和10年棚龄的黄瓜中碳水化合物和营养物质的比值更加均衡。通过分析黄瓜各有机组分以及黄瓜各有机组分比值随着黄瓜棚龄的变化，知悉黄瓜棚龄在10年以内时，对黄瓜品质提升具有促进作用，但更长的棚龄会抑制黄瓜品质。因此，综合考虑黄瓜的品质，建议黄瓜棚龄不宜太长。另外，通过分析棚龄对黄瓜叶片有机组分的影响，发现黄瓜叶片各组分与黄瓜各组分的变化趋势相似。线性相关分析指出黄瓜蛋白质和木质素组分分别与黄瓜叶片蛋白质和木质素组分显著正相关，表明黄瓜叶片在一定程度上能反映黄瓜的营养成分和黄瓜口感。利用红外光谱解析不同棚龄下表征黄瓜品质的有机组分，为蔬菜大棚管理以及提高蔬菜品质提供了科学依据。     

基于复杂网络的邮件病毒的传播模型

本文以电子邮件病毒为例，通过构建改进的SEIR病毒传播模型，并结合更符合实际的复杂网络与人际关系对病毒的传播特性进行深入研究。从用户的主观与客观等多种角度研究了有效拉制病毒在网络中快速传播的方式．理论分析及仿真实验表明，通过对实际生活中某些参数的控制，能有效遏制邮件病毒在网络中的传播．‘     

Nanoscale Wetting of Single Viruses

The epidemic spread of many viral infections is mediated by the environmental conditions and influenced by the ambient humidity. Single virus particles have been mainly visualized by atomic force microscopy (AFM) in liquid conditions, where the effect of the relative humidity on virus topography and surface cannot be systematically assessed. In this work, we employed multi-frequency AFM, simultaneously with standard topography imaging, to study the nanoscale wetting of individual Tobacco Mosaic virions (TMV) from ambient relative humidity to water condensation (RH > 100%). We recorded amplitude and phase vs. distance curves (APD curves) on top of single virions at various RH and converted them into force vs. distance curves. The high sensitivity of multifrequency AFM to visualize condensed water and sub-micrometer droplets, filling gaps between individual TMV particles at RH > 100%, is demonstrated. Dynamic force spectroscopy allows detecting a thin water layer of thickness ~1 nm, adsorbed on the outer surface of single TMV particles at RH < 60%.     

Dynamical behavior of a virus dynamics model with CTL immune response

In this paper, the dynamical behavior of a virus dynamics model with CTL immune response is studied. Sufficient conditions for the asymptotical stability of a disease-free equilibrium, an immune-free equilibrium and an endemic equilibrium are obtained. We prove that there exists a threshold value of the infection rate b beyond which the endemic equilibrium bifurcates from the immune-free one. Still for increasing b values, the endemic equilibrium bifurcates towards a periodic solution. We further analyze the orbital stability of the periodic orbits arising from bifurcation by applying Poore’s condition. Numerical simulation with some hypothetical sets of data has been done to support the analytical findings.