地面大型森林消防装备发展现状研究

地面大型森林消防装备、空中扑救装备和消防队员单兵作战构成了全方位联合作战的森林消防格局,地面大型森林消防装备作为森林消防装备的重要组成部分发挥着不可替代的作用.文章介绍了国内外防火推土机、防火犁和防火耙、清林割灌机和森林消防车4种地面大型森林消防装备的主要功用和发展现状,以期自主研发适合我国国情的地面大型森林消防装备.     

模拟退火遗传算法在手持GPS接收机中的应用

分析了手持GPS接收机在实际应用中定位精度的影响因素,提出了模拟退火遗传算法,并将该算法用于导航接收机中,建立了实现原理框图,进而提出了模拟退火遗传算法的具体步骤,通过实测检测得到较高的精度。     

Probing and Analysis of Diffusion Model for Technology Creating Something New

Technology Creating something new is spring of technology progress,and diffusion of trasfer of technology is a key stage or symbol of technology progress.Raz Baruch,Liu Wenge and Zhu Jiaxing,respectively,had given or modified receiver state model of technology transfer.This paper firstly explains that S-type model is a model of simple,applicable and higher guasi-degree for technology transfer as well.Next,a long-time model of receiver state of technology(development) in technology diffusion is obtained and Zhu's model is revised.     

The reliability of leaf bioassays for predicting disease resistance on fruit: a case study on grapevine resistance to downy and powdery mildew

This study was designed to assess the reliability of grapevine leaf bioassays for predicting disease resistance on fruit in the field. The efficacy of various grapevine quantitative trait loci (QTLs) for conferring resistance to downy and powdery mildew was evaluated in bioassays and in a 2‐year field experiment for downy mildew. The resistance genes studied were inherited from Muscadinia rotundifolia (Rpv1 and Run1) and from American Vitis species through cv. Regent (QTLRgP and QTLRgD). In bioassays, genotypes carrying Run1 blocked powdery mildew development at early stages. Genotypes combining Run1 with QTLRgP displayed no greater level of resistance. For downy mildew, genotypes carrying Rpv1 and/or QTLRgD were more resistant than the susceptible cv. Merlot, and showed a high level of leaf resistance in the field (<10% severity). Disease levels on bunches were much higher than those on leaves, with a high variability between Rpv1 genotypes (1–48%). A Bayesian decision theory framework predicted that an OIV‐452 threshold of 5 in leaf bioassays allowed accurate selection of grapevine genotypes (P = 0·83) with satisfactory disease severity on bunches. Therefore, this study validates that the use of early bioassays on leaves, as currently performed by grapevine breeders, ensures a satisfactory level of resistance to downy mildew of bunches in the field.     

Summary receiver operating characteristics (SROC) and hierarchical SROC models for analysis of diagnostic test evaluations of antibody ELISAs for paratuberculosis

Critical, systematic reviews of available diagnostic test evaluations are a meticulous approach to synthesize evidence about a diagnostic test. However, often the review finds that data quality is poor due to deficiencies in design and reporting of the test evaluations and formal statistical comparisons are discouraged. Even when only simple summary measures are appropriate, the strong correlation between sensitivity and specificity and their dependence on differences in diagnostic threshold across studies, creates the need for tools to summarise properties of the diagnostic test under investigation.This study presents summary receiver operating characteristics (SROC) analysis as a means to synthesize information from diagnostic test evaluation studies. Using data from a review of diagnostic tests for ante mortem diagnosis of paratuberculosis as an illustration, SROC and hierarchical SROC (HSROC) analysis were used to estimate overall diagnostic accuracies of antibody ELISAs for bovine paratuberculosis while accounting for covariates: the target condition (infectious or infected) used in the test evaluation (one for the evaluation of Se and one for Sp); and the type of test (serum vs. milk). The methods gave comparable results (regarding the estimated diagnostic log odds ratio), considering the small sample size and the quality of data. The SROC analysis found a difference in the performance of tests when the target condition for evaluation of Se was infected rather than infectious, suggesting that ELISAs are not suitable for detecting infected cattle. However, the SROC model does not take differences in sample size between study units into account, whereas the HSROC allows for both between and within study variation. Considering the small sample size, more credibility should be given to the results of the HSROC. For both methods the area under the (H)SROC curve was calculated and results were comparable.The conclusion is that while the SROC is simpler and easier to implement, analyse and interpret, the HSROC does have properties encourage the extra effort involved in the analysis.     

LOW-FIELD MAGNETIC RESONANCE IMAGING OF BEAGLE BRAIN WITH A DEDICATED RECEIVER COIL

A specially designed radio frequency receiver coil was used in a low-field-strength (0.1 T) magnetic resonance imager to improve the image quality of the Beagle brain. The aim was to obtain better distinction of anatomic details with a better signal-to-noise ratio in shorter imaging time. The spin-echo (TR/TE = 1200/100; TR is the repetition time and TE is the echo time in ms) brain images of three Beagles indicate that the new receiver coil can fulfill these goals.     

指盘式搂草机动力学仿真及结构寻优试验

玉米秸秆的搂集清理工作劳动密集度高且费时,如果雨天没有及时收获,很容易导致秸秆的变质[1].现阶段玉米秸秆基本上由搂草机搂集,由于作物和耕种方式的不同,引进国外的搂草机存在适应性问题,且搂草机搂集的玉米秸秆含土量大、漏搂率高.针对这一问题,设计了多参数可调节的指盘搂草机实验台,在满足搂草机整机结构及工作原理的基础上,对...     

Spatial distribution of ocean habitat of yearling Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon off Washington and Oregon,USA

We determined the habitat usage and habitat connectivity of juvenile Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon in continental shelf waters off Washington and Oregon, based on samples collected every June for 9 yr (1998–2006). Habitat usage and connectivity were evaluated using SeaWiFS satellite‐derived chlorophyll a data and water depth. Logistic regression models were developed for both species, and habitats were first classified using a threshold value estimated from a receiver operating characteristic curve. A Bernoulli random process using catch probabilities from observed data, i.e. the frequency of occurrence of a fish divided by the number of times a station was surveyed, was applied to reclassify stations. Zero‐catch probabilities of yearling Chinook and yearling coho salmon decreased with increases in chlorophyll a concentration, and with decreases in water depth. From 1998 to 2006, ～ 47% of stations surveyed were classified as unfavorable habitat for yearling Chinook salmon and ～ 53% for yearling coho salmon. Potentially favorable habitat varied among years and ranged from 9 856 to 15 120 km² (Chinook) and from 14 800 to 16 736 km² (coho). For both species, the smallest habitat area occurred in 1998, an El Niño year. Favorable habitats for yearling Chinook salmon were more isolated in 1998 and 2005 than in other years. Both species had larger and more continuous favorable habitat areas along the Washington coast than along the Oregon coast. The favorable habitats were also larger and more continuous nearshore than offshore for both species. Further investigations on large‐scale transport, mesoscale physical features, and prey and predator availability in the study area are necessary to explain the spatial arrangement of juvenile salmon habitats in continental shelf waters.     

故障受油器影响下灯泡贯流式机组非线性振动特性

针对故障受油器引发的灯泡贯流式机组事故,为提高机组运行的安全性和稳定性,基于构建复合偏心影响下不平衡磁拉力模型,建立多振源激励下含故障受油器灯泡贯流式机组轴系模型及其运动微分方程.应用数值计算方法分析有无故障受油器系统动态特性的差异,对系统在励磁电流、气隙静偏心以及动偏心变化过程中的非线性振动特性进行研究.结果表明:故障受油器的存在虽加大了转子非稳态运动范围并激发转子不利振动形式,但其对抑制系统振幅、削弱谐波成分表现出一定的积极作用,使机组受迫振动程度得以减缓;相比于数值固定的静偏心,随机组转动而不断变化的动偏心可使系统产生拟周期、周期二等丰富的动态响应形式,并进一步缩减了系统整体稳定运行范围,需引起足够重视.研究结果可为灯泡贯流式机组安全运行及稳定性分析提供一定借鉴.     

围产期奶牛脂肪肝生物标志物受试者工作特征曲线分析

[目的] 通过受试者工作特征（receiver operating characteristic，ROC）曲线筛选诊断脂肪肝生物标志物的最佳临界值。[方法] 随机采集77头产后7 d中国荷斯坦奶牛血清，测定生理生化指标。根据Reid方程计算的Y值将奶牛分为正常组（Y>1）和脂肪肝组（Y<1），比较两组奶牛血清指标的差异，并与Y值进行相关性分析，筛选组间差异与相关性显著的指标作为生物标志物，用ROC曲线评估生物标志物的AUC值、诊断敏感性与特异性和最佳临界值。将Reid方程诊断脂肪肝的准确率作为标准，用非酯化脂肪酸（NEFA）、谷草转氨酶（AST）的最佳临界值检测461头奶牛患脂肪肝的情况。[结果] 生理生化检测结果表明NEFA、葡萄糖（Glu）、AST、谷丙转氨酶（ALT）在2组间差异极显著（P<0.01），总蛋白（TP）组间差异显著（P<0.05），其他指标两组间无显著差异（P>0.05）；NEFA、Glu、AST、ALT、TP、甘油三酯（TG）、低密度脂蛋白胆固醇（LDL-C）、胰岛素（Ins）、胰高血糖素（Gln）与Y值显著相关（P<0.05），可作为生物标志物；NEFA、AST、ALT和Gln的AUC值>0.5能准确诊断脂肪肝，诊断敏感性分别为81.8%、72.7%、63.6%和54.5%，特异性分别为92.8%、89.4%、84.8%和69.7%，最佳临界值分别为471.74 μmol/L、95.50 U/L、46.50 U/L和64.60 ng/mL。用NEFA、AST和NEFA+AST最佳临界值诊断脂肪肝的准确率分别高达89.96%、73.49%和69.08%。Y值诊断发病率为54.01%，NEFA、AST、NEFA+AST诊断出的发病率分别为48.59%、39.70%和37.31%。[结论] NEFA、AST、ALT和Gln可用于快速、准确地诊断脂肪肝。