基于不同机器学习模型的川中丘陵区参考作物蒸散量模拟

为探究不同数值模拟模型在川中丘陵区的适应能力,提高川中丘陵区气象资料缺失下的参考作物蒸散量(ET0)预报精度。选取7个代表性站点1961-2016年逐日气象资料,分别建立基于M5回归树(M5-RT)、双隐含层优化的反向传播神经网络(H-BPNN)和交叉验证优化的广义回归神经网络(CV-GRNN)的ET0预报模型。并选取3个在川中丘陵区具有较高精度的经验模型与其进行对比,在日尺度上评估模型的预报精度,利用可移植性分析评价3种模型在川中丘陵区的泛化能力。结果表明:①基于温度、风速和大气顶层辐射输入的M5-RT2、CV-GRNN2和H-BPNN2模型都具有较高的模拟精度,其R\+2分别为0.987、0.967和0.988,NSE分别为0.987、0.937和0.988;②日尺度误差分析表明,4类输入项组合下,M5-RT模型最优,H-BPNN模型次之,CV-GRNN模型最差,但3种模型的均方根误差均小于0.5 mm/d、平均相对误差均小于13.59%,优于Jensen-Haise、Hargreaves-Li和Irmak-Allen模型,M5-RT2(输入大气顶层辐射、最高/低温度和风速)、M5-RT3(输入最高/低温度和风速)和M5-RT4(输入大气顶层辐射和风速)在川中丘陵区内具有广泛的适应性,均可作为气象数据缺失下川中丘陵区ET0预报的推荐模型;③可移植性分析发现,训练、预测站点交叉组合下,3种模型的预报精度都有降低,但M5-RT泛化能力最强,模拟输出稳定,H-BPNN和CV-GRNN在ET0大于6 mm/d时出现明显截断误差,预测值普遍偏小,同时CV-GRNN模拟结果于标准值的趋势线斜率较小,模拟数值整体偏小。基于M5回归树的ET0预报模型在川中丘陵区具有较高精度,模拟结果稳定,可作为推荐的ET0简化模拟模型。     

基于基因表达式编程算法的参考作物腾发量模拟计算

选取都安气象站5年(2008—2012年)的逐日气象数据,包括日最高气温、最低气温、平均风速、日照时数以及相对湿度5个气象要素的不同组合作为输入,并以FAO-56 Penman-Monteith法(FAO P-M)的计算结果作为标准值,采用基因表达式编程算法(GEP)及径向基函数网络算法(RBFNN)对参考作物腾发量ETo进行模拟计算,并将模拟结果与Hargreaves模型的计算结果进行比较,用决定系数R2和均方根误差RMSE作为评价指标。结果表明,GEP模型能够捕捉到ETo的变化,具有较强的适用性,与FAO P-M公式的计算值有很高的一致性。引入关键气象因子(气温和相对湿度)后,模型的决定系数R2达到0.914,均方根误差RMSE为0.240 mm/d。在相同输入情况下GEP模型计算精度高于RBFNN模型和Hargreaves模型,并建立了可以替代Hargreaves模型的GEP模型及缺少相对湿度RH时的GEP模型。结果表明,在缺乏相关气象因子时,可以利用GEP模型模拟ETo。     

Evaluation of tricuspid annular plane systolic excursion measured by two-dimensional echocardiography in healthy dogs: repeatability,reference intervals,and comparison with M-mode assessment

Introduction

We sought to determine the feasibility, measurement variability, and within-day repeatability of tricuspid annular plane systolic excursion (TAPSE) measured by two-dimensional echocardiography (2D TAPSE), generate reference intervals for 2D TAPSE, assess agreement and correlation between 2D TAPSE and the conventional TAPSE measured by M-mode echocardiography (MM TAPSE), and to assess the ability of 2D TAPSE to track a drug-induced decrease in right ventricular (RV) function compared with MM TAPSE.

Transthoracic echocardiography in Estrela Mountain dogs: reference values for the breed

Of 100 Estrela Mountain dogs, 74 were examined to obtain echocardiographic reference values for the breed. The influence of bodyweight, age and sex on different echocardiographic parameters was studied using either analysis of variance or regression analysis. Statistically significant differences were found between sex and heart rate as well as interventricular septal thickness at end-systole and left ventricular internal dimension at end-diastole. A statistically significant linear correlation was also found between several parameters and (1) age (mean arterial pressure, left ventricular internal dimension at end-systole, fractional shortening, circularity index in systole, aortic valve velocity time integral, pulmonic valve velocity time integral and mitral valve E wave peak velocity), (2) weight (left ventricular posterior wall thickness at end-diastole and end-systole, end-diastolic volume index, left atrium diameter, aortic valve peak velocity and mitral valve E wave deceleration time), (3) sex and age (left ventricle end-diastolic volume), and (4) sex and weight (aortic root diameter and pulmonic valve peak velocity). Reference values for the breed are presented, as well as dispersion graphics for selected parameters, based on a regression equation.     

淮河流域参考作物蒸散量变化特征及主要气象因子的贡献分析

利用淮河流域171个站点1971-2010年的气象资料,采用FAO Penman-Monteith公式计算该区近40a的参考作物蒸散量（ET0）,并对ET0的时空分布特征和影响因子进行定量分析。结果表明：淮河流域年ET0为898mm,近40a总体以17.5mm/10a的速率减小（P〈0.05）;空间分布显示西北部大部站点ET0呈显著下降趋势（P〈0.05）,仅东南部个别站点呈显著上升趋势（P〈0.05）。各气象因子对ET0变化的贡献表现为两方面,即ET0对气象因子的敏感性和气象因子的多年相对变化率,在4个主要因子中（平均温度、相对湿度、日照时数和风速）,ET0对相对湿度的变化最敏感（敏感系数最大）,而风速的多年平均变化率最大。从各因子的贡献率看,对ET0贡献最大的是风速,平均温度的贡献最小,4个因子对ET0变化的总贡献率为-4.96%,总贡献率为负在很大程度上解释了ET0呈下降趋势的原因。     

Reference Intervals of Serum Protein Concentrations from Clinically Healthy Female Ragusana Donkeys (Equus asinus) Determined by Cellulose Acetate Electrophoresis

The aim of this study was to evaluate total serum protein concentration measured using biuret reaction and the protein fractions determined using acetate cellulose electrophoresis in Ragusana donkeys (Equus asinus). Blood samples were collected from 68 clinically healthy female donkeys by jugular venipuncture. The serum levels of total proteins were determined using biuret method, and the separation of proteins was performed using acetate cellulose electrophoresis. Coefficients of variation were also calculated for within-assay precision, and were found to be less than 5% for α- and β₁-globulins and 8% or less for albumin, β₂-, and γ-globulins. A total of five protein fractions were separated and quantified: albumin, α-, β₁-, β₂-, and γ-globulins. Data obtained from young and adult subjects were compared using the Mann–Whitney U test. Reference intervals (2.5%-97.5% quantiles) were determined for total proteins (50.0-84.0 g/L), albumin (16.2-36.6 g/L), α-globulins (4.85-19.5 g/L), β₁-globulins (2.25-10.35 g/L), β₂-globulins (3.30-14.85 g/L), γ-globulins (10.0-30.5 g/L), and albumin/globulin ratio (0.41-1.13). In relation to age, statistically significant differences were found in total protein concentration and γ-globulins. The results obtained in the present study contributed to establish reference intervals of serum protein fractions obtained using acetate cellulose electrophoresis in female Ragusana donkeys to be used by practitioners for health control.     

试论高校资料室的情报服务

本文以高校资料室的情报服务为起点，对情报服务的范畴、原则、问题、条件和方法等相关问题进行了探讨，指出高质量的情报服务可以对专业教学改革和科研进步起到积极的推动作用。     

农业设备租赁会计相关准则的比较

2007年1月,我国新发布的《企业会计准则第21号——租赁》开始执行,对农业类企业有较大影响。通过比较农业设备租赁相关的新旧会计准则以及国内外会计准则的差异,简要分析了准则变化对农业设备租赁行业的影响。     

口蹄疫病毒株China/99 P3区一级结构及与参考毒株的比较分析

用RT－PCR法，以口蹄疫病毒China/99感染的牛舌水泡皮为材料，扩增目的cDNA，与pGEM-T Easy载体连接并转化JM109菌株，再经重组质粒电泳、PCR和EcoR1酶切鉴定。序列测定和分析结果表明，猪源毒在3A基因内缺失10个密码子，与牛源毒的核苷酸和氨基酸序列差异较大。A－G和T－C的转换率较高，而且A－G转换导致氨基酸变异的几率大于T－C转换，它们是影响氨基酸稳定的因素之一。China/99P3区编码产物在第8、120、121、127、132、193、493、501和538位具有特征性氨基酸，可能与该毒株的表型如毒力等有关。3A基因突变率较高，3B、3C和3D较低，3D最为保守，这对维持3C和3D蛋白酶和3B的引物功能至关重要。