Vertebral Fractures in Newborn Calves

A prospective study on vertebral fractures in newborn calves is described. Vertebral fractures were found in 7.0% of necropsied calves of the Danish Holstein-Friesian (SDM) and Red Danish Dairy (RDM) breeds. Cases were not found in submitted calves of the Jersey breed or beef breeds. At least in beef breeds this was probably due to the low number necropsied. The rate of vertebral fractures in SDM and RDM breeds and between males and females were similar. Most cases occurred in calves born by heifers, and manual traction force had been applied in all cases. All fractures which in most cases consisted of a simple epiphysiolysis were located at the thoraco-lumbar area, and especially the posterior epiphysis of T13 was afflicted.     

Risk factors for dystocia in farmed red deer (Cervus elaphus).

OBJECTIVE: To analyse data from a study of deer herd health and productivity to identify potential risk factors for the occurrence of dystocia. DESIGN: A 2-year longitudinal observational study of 14 red deer farms was carried out in New Zealand. About 2700 hinds were monitored each year for individual characteristics including body condition score (BCS), and reproductive performance. Grazing and calving management practices were recorded. During calving, farmers recorded calving difficulties (dystocia) that needed human assistance or caused the death of the hind. Risk factors potentially affecting the occurrence of dystocia were identified and analysed by multivariable statistical techniques. RESULTS: The percentage of hinds with dystocia was 0.52% (95% CI 0.32 to 0.78). Hinds with a post-winter BCS over 3.5 were 2.7 times as likely to experience dystocia as hinds scoring 3.5 or less. Given the same BCS class, bodyweight gain in late pregnancy was associated with an increased risk of dystocia. Grazing steep paddocks in the last trimester of pregnancy decreased the risk of dystocia in hinds with a BCS over 3.5. CONCLUSIONS: The risk of dystocia on red deer farms may be reduced if key individual animal, management and environmental factors are optimal.     

甘肃尕海湿地退化过程中植物生物量及物种多样性变化动态

以尕海湿地区内的典型沼泽泥炭和沼泽化草甸为研究对象,采用空间序列代替时间序列的方法,研究了尕海湿地退化过程中植物生物量及物种多样性的变化特征。结果表明：在尕海湿地退化过程中,湿地的地上、地下生物量均显著降低,但地下生物量降低幅度较大,地下、地上生物量比例系数呈减小趋势;尕海湿地退化过程中植物群落特征发生明显变化,具体表现为,泥炭沼泽退化过程中的优势种从未退化时乌拉苔草（Carex meyeriana）演变为退化时的问荆（Equisetum arvense）。沼泽化草甸退化过程中的优势种从未退化时藏嵩（Kobresia tibetica）演变为轻度和中度退化程度时的青藏苔草（Carex moorcroftii）和密毛白莲蒿（Artemisia sacrorum.var mess-rschmidtiana）;重度退化程度时仅有零星的冷蒿（Artemisia frigida）、珠芽蓼（Polygonum viviparum）;主要伴生种表现为湿生植物逐渐消失,中、旱生毒杂草逐渐增加。泥炭沼泽的植物物种丰富度和多样性指数呈增加趋势,沼泽化草甸为先增加后降低,均匀度指数恰好相反;群落相似性系数逐渐降低。说明尕海湿地原有植物群落物种多样性分布格局向杂草型退化方向演替,建议减少放牧压力,采取人工措施促进尕海湿地生态功能恢复。     

Predicting field weed emergence with empirical models and soft computing techniques

Seedling emergence is one of the most important phenological processes that influence the success of weed species. Therefore, predicting weed emergence timing plays a critical role in scheduling weed management measures. Important efforts have been made in the attempt to develop models to predict seedling emergence patterns for weed species under field conditions. Empirical emergence models have been the most common tools used for this purpose. They are based mainly on the use of temperature, soil moisture and light. In this review, we present the more popular empirical models, highlight some statistical and biological limitations that could affect their predictive accuracy and, finally, we present a new generation of modelling approaches to tackle the problems of conventional empirical models, focusing mainly on soft computing techniques. We hope that this review will inspire weed modellers and that it will serve as a basis for discussion and as a frame of reference when we proceed to advance the modelling of field weed emergence.     

不同焙烤温度和时间对澳洲坚果果仁颜色的影响

坚果果仁的颜色在焙烤过程中能发生显著变化。针对澳洲坚果果仁在不同焙烤条件下的颜色指标(亮度值、红绿值、黄蓝值、饱和度和色调角)的变化规律进行研究,并找出焙烤条件与果仁颜色的关系。根据颜色指标的变化规律将焙烤条件大致划分为4个焙烤程度：(1)浅度焙烤。焙烤条件为130℃焙烤10～15 min、150℃焙烤5 min和170℃焙烤4 min,果仁颜色奶白色;(2)中度焙烤。焙烤条件为130℃焙烤25～40 min、150℃焙烤10 min和170℃焙烤6 min,果仁颜色淡黄色;(3)中深度焙烤。130℃焙烤50～60 min、150℃焙烤15 min和170℃焙烤8 min,果仁颜色金黄色;(4) 深度焙烤。150℃焙烤20～30 min和170℃焙烤10～14 min,果仁颜色深黄色。通过建立焙烤坚果颜色与焙烤程度的关系,更好地指导澳洲坚果的焙烤工艺和拓展坚果产品的应用范围。     

灰色关联分析法在汽车零部件故障分析中的应用

介绍了灰色关联分析的有关理论,并采用该方法在汽车零部件的故障诊断中研究系统的故障特征与内部特征之间的相关性,确定实际模式归属于某个标准模式,并对故障树诊断进行综合分析。实例诊断表明,这种方法是有效可行的,并且诊断结果可靠。     

农用三轮机动车跨越障碍物的侧翻动力学分析

建立农用三轮机动车跨越障碍物的侧翻动力学模型,通过动力学理论对车辆侧翻现象进行分析。考虑减振弹簧和阻尼器的影响,推导出三轮机动车六自由度车辆动力学方程,提出其刚体侧翻运动模型。通过振动分析,得到三轮机动车行驶过程中单个车轮碰撞障碍物时各自由度以及质心的位移响应,由刚体侧翻运动分析得到其侧翻临界条件,并利用该条件分析了车辆质心位置以及后轮轴间距变化对侧翻临界载荷值的影响。     

马铃薯品种抗旱性鉴定研究

通过对马铃薯品种同薯20号和晋薯15号的根系拉力与冠层覆盖度测试,以及在旱作生态区的适应性试验,对上述2个品种的抗旱性进行了鉴定,结果表明,同薯20号与晋薯15号在干旱胁迫下根系拉力强、冠层覆盖度大、产量水平高、适应性强,是很好的抗旱性品种,可以在全国一季作区及各旱作生态区推广应用。     

基于信息理论的生态网络灵敏度分析

将信息理论与物流模型的研究挂接 ,定义了生态系统的信息熵和信息流量。以各分室输出量占总体的份额作为系统选择该分室的概率。通过对系统聚合度和冗余度的分析 ,推导了二者对各分室的灵敏度。对黑龙江省双城市双城镇永和村的物流模型进行了灵敏度分析。计算结果表明 ,籽粒和土壤分室对系统的稳定性起重要作用 ;而调整畜牧业的结构 ,改变农肥的投入量等 ,可以有效地改善系统的物流情况 ,使系统向良性循环     

新型香蕉种植开坑机的结构设计与仿真分析

基于降低减轻人力成本、提高劳动效率的原则,研发了一种可控连杆式三自由度香蕉种植开坑机。首先,通过基于旋量理论为基础的自由度公式,计算出可控香蕉种植开坑机自由度;其次,运用闭环矢量法建立了可控香蕉种植开坑机的运动学方程,得出其运动学特性;最后,结合多体动力学理论及ADAMS软件,对可控香蕉种植开坑机进行仿真分析,得出其发动机运动特性,进而验证了该新型结构的合理性和可行性。