Optimal insemination and replacement decisions to minimize the cost of pathogen-specific clinical mastitis in dairy cows

Mastitis is a serious production-limiting disease, with effects on milk yield, milk quality, and conception rate, and an increase in the risk of mortality and culling. The objective of this study was 2-fold: (1) to develop an economic optimization model that incorporates all the different types of pathogens that cause clinical mastitis (CM) categorized into 8 classes of culture results, and account for whether the CM was a first, second, or third case in the current lactation and whether the cow had a previous case or cases of CM in the preceding lactation; and (2) to develop this decision model to be versatile enough to add additional pathogens, diseases, or other cow characteristics as more information becomes available without significant alterations to the basic structure of the model. The model provides economically optimal decisions depending on the individual characteristics of the cow and the specific pathogen causing CM. The net returns for the basic herd scenario (with all CM included) were $507/cow per year, where the incidence of CM (cases per 100 cow-years) was 35.6, of which 91.8% of cases were recommended for treatment under an optimal replacement policy. The cost per case of CM was $216.11. The CM cases comprised (incidences, %) Staphylococcus spp. (1.6), Staphylococcus aureus (1.8), Streptococcus spp. (6.9), Escherichia coli (8.1), Klebsiella spp. (2.2), other treated cases (e.g., Pseudomonas; 1.1), other not treated cases (e.g., Trueperella pyogenes; 1.2), and negative culture cases (12.7). The average cost per case, even under optimal decisions, was greatest for Klebsiella spp. ($477), followed by E. coli ($361), other treated cases ($297), and other not treated cases ($280). This was followed by the gram-positive pathogens; among these, the greatest cost per case was due to Staph. aureus ($266), followed by Streptococcus spp. ($174) and Staphylococcus spp. ($135); negative culture had the lowest cost ($115). The model recommended treatment for most CM cases (>85%); the range was 86.2% (Klebsiella spp.) to 98.5% (Staphylococcus spp.). In general, the optimal recommended time for replacement was up to 5 mo earlier for cows with CM compared with cows without CM. Furthermore, although the parameter estimates implemented in this model are applicable to the dairy farms in this study, the parameters may be altered to be specific to other dairy farms. Cow rankings and values based on disease status, pregnancy status, and milk production can be extracted; these provide guidance when determining which cows to keep or cull.     

Systematic Comparison of Hedonic Ranking and Rating Methods Demonstrates Few Practical Differences

Hedonic ranking is one of the commonly used methods to evaluate consumer preferences. Some authors suggest that it is the best methodology for discriminating among products, while others recommend hedonic rating. These mixed findings suggest the statistical outcome(s) are dependent on the experimental conditions or a user's expectation of “what is” and “what is not” desirable for evaluating consumer preferences. Therefore, sensory and industry professionals may be uncertain or confused regarding the appropriate application of hedonic tests. This paper would like to put this controversy to rest, by evaluating 3 data sets (3 yogurts, 79 consumers; 6 yogurts, 109 consumers; 4 apple cultivars, 70 consumers) collected using the same consumers and by calculating nontied ranks from hedonic scores. Consumer responses were evaluated by comparing bivariate associations between the methods (nontied ranks, tied ranks, hedonic rating scores) using trellis displays, determining the number of consumers with discrepancies in their responses between the methods, and comparing mean values using conventional statistical analyses. Spearman's rank correlations (0.33–0.84) revealed significant differences between the methods for all products, whether or not means separation tests differentiated the products. The work illustrated the inherent biases associated with hedonic ranking and recommended alternate hedonic methodologies.     

低阶煤煤层气富集模式初探

我国低阶煤中煤层气资源丰富，开发低阶煤煤层气具有重要的意义，对于低阶煤煤层气开发来说，寻找煤层气富集区是开发的关键。本文通过对美国粉河盆地以及我国铁法盆地煤层气富集规律的分析，总结出影响煤层气富集的关键因素和5种不同的煤层气富集模式。     

低中煤级煤结构演化的FTIR表征

通过对28个最大镜质组反射率0.295%-2.047%镜煤样品的FT-IR分析,获得低中煤级煤结构的演化规律及机理。研究表明：煤化学结构主要由芳香结构、脂族结构和含氧官能团组成。煤的结构演化分为三个阶段,分别是镜质组反射率小于0.8%、0.8-1.3%和1.3-2.0%。在镜质组反射率小于0.8%阶段,以含氧官能团的脱落和脂肪类物质的富集为主;在镜质组反射率0.8-1.3%阶段,则主要是脂肪类物质的富集和支链化程度的增加或脂环化作用与芳香化作用的协同;在镜质组反射率1.3-2.0%阶段,则在镜质组反射率小于1.7%前,主要为脂肪类物质的热解断裂,而之后,则是随着脂肪类物质的断裂脱落,形成新的芳香结构体系。低中煤级阶段煤结构的演化特征与第一、二次煤化作用跃变的发生密切相关。     

低阶烟煤煤岩组分解离特性及其分选

为研究低阶烟煤煤岩显微组分的分选,以高惰质组含量的神东长焰煤为研究对象,利用偏光显微镜Leica DM4500P,分析了不同破碎程度下煤岩显微组分的分布形态和解离规律,确定了煤岩组分的最佳解离粒度,并对比了不同破碎程度下煤岩显微组分的重力分选结果。煤岩显微组分的解离特性表明,随着破碎粒度的降低,镜质组含量先基本不变,后逐渐降低,而惰质组含量先基本不变,后逐渐增加;当破碎粒度为0.125 mm时,镜质组单体解离度为91.77%,惰质组单体解离度为86.77%,连生体含量为8.05%;不同破碎程度下的煤岩显微组分重力分选结果表明,将煤样破碎至-0.125 mm,当分选密度为1.33 kg/L时,可获得镜质组含量为89.05%、镜质组回收率为58.72%的富镜质组富集物。     

不同煤化程度煤的热解及氮的释放行为

采用热重-红外-质谱联用技术（TG-IR-MS）,对4种不同煤化程度的煤进行热解实验,实时记录了煤在30~1 100 ℃,以10 ℃/min升温速率、氦气气氛下热解过程中的质量变化和生成气体成分。研究结果表明：随着热解温度的升高,煤中逐渐释放出氮化物,如HCN,NH3等。不同煤化程度的煤具有不同的N释放行为。气煤、焦煤、1/3焦煤等主要以NH3与HCN两种形式释放,无烟煤热解时主要是以NH3形式释放。煤热解释放的HCN和NH3来源于不同的氮。 HCN可能主要来源于煤分子边缘的五元环吡咯氮和六元环吡啶氮,而NH3主要来源于煤分子内部的季氮。NH3的释放经历了2个阶段:低温（550 ℃）阶段为煤中挥发分的初级热解产物;高温（750~850 ℃）阶段为煤中挥发分的二次热解产物。     

南水北调东线工程山东段突发事故风险评估

南水北调东线工程山东段由新修渠道、原有河道及湖泊、水库共同构成。输水干线多为开敞式且与当地交通道路交叉,南四湖和梁济运河承担航运任务,交通、航运等突发事故有可能影响正常输水,因而输水安全受到多种潜在突发事故的威胁。为能够在突发事故发生后采取有效的应急控制和处置措施,降低事故造成的损失,采用核对表法对工程突发风险源进行识别,确定突发事故类型,综合利用模糊意见集中决策和层次分析法建立风险评估体系,对南水北调东线工程山东段的突发事故风险进行评估,确定各类突发事故对工程的影响程度,经评定该工程的主要风险包括陆运和航运交通事故引发的突发风险,次要风险主要包括人为投毒、自然灾害及机器故障等原因引发的各类突发风险。该成果可为后续应急控制和处置方案的制定提供决策依据,同时可为其他资料短缺地区的风险评估提供参考。     

中小城镇天然气配气管网的压力级别选择

中小城镇是我国当前天然气利用快速发展的区域,工程设计中其天然气管网多采用中压A级配气管网,而忽略了中压B级管网具有的特性。为此,比较了中压B级和中压A级管道的爆破能量比和泄漏质量流量比,分析了压能转移利用的贡献,对中压A级管道所需的最小街道宽度进行了定量分析,论证了中压B级管道的适用性。进而用虚拟环网覆盖中小城镇供气区域,推导出等流速工况下中压天然气配气管网管径表达式,计算了相同管网构成时不同供气规模、不同最大管路长度时,中压B级管网与中压A级管网的管材耗量比。结果表明:中小城镇天然气配气管网采用中压B级比采用中压A级投资增加20%以上,经济性相对较差;但中压B级在压力安全和敷设条件方面却具有明显的优势。因此对于老城古镇等区域较窄的街道,要考虑各种方案并综合决策。结论认为:中压B级配气管网在中小城镇的应用具有广阔的前景。     

“U”型井开发煤层气适应性研究

国内外煤层气研究成果和生产实践证明,需要不同类型的钻井开发煤阶、含气量、含水量等关键参数相异的煤层,以实现煤层气产能最大化。作为一个新的钻井类型,研究"U"型井适合钻探的煤层类型对于提高其产能,实现中国煤层气产业化至关重要。为此,选取沁水、鄂尔多斯盆地等中、高煤阶盆地,根据其地质资料及煤层气生产资料,从煤阶、煤层厚度、煤割理与钻进方向关系、含水量、煤层倾角等方面阐述了"U"型井钻井适应性,认为低煤阶煤层因硬度、密度低,采用"U"型井钻探容易引起坍塌;"U"型井采用两井连通、地质导向、远距离穿针等新技术,而厚煤层在有效使用这些技术的同时,更容易实现在煤层中钻进;"U"型井具有水平井和直井两个井口,可以更有效排出高含水煤层中的承压水,同时也可利用煤层坡度,将直井设置在煤层下倾方向,利用重力排水采气;"U"型井中的水平井具有方向性,垂直于面割理方向钻进可以获得较大产能。以上研究成果表明:"U"型井可以有效开发割理发育、具一定倾角、高含水的中高煤阶厚储层。该研究成果为"U"型井高效开采煤层气指明了方向。     

近红外光谱分析技术预测煤质挥发分含量模型的研究

应用近红外光谱方法进行煤质在线分析工作的研究,主要进行煤中挥发分的测定。在阅读了多个光谱图的基础上,采用多元回归方法对数据进行了分析和处理,建立了多元线性模型,该模型得出的煤中挥发分的预测值与人工化验标准值之间的相关系数为0．96,所建模型的定标标准差为1．41。