Overview of a Passive Tracking Index for Monitoring Wild Canids and Associated Species

Population density estimates for many animal species are often difficult or expensive to obtain, and they rely on assumptions that, if violated, result in unmeasurable estimation errors. Density estimates also may be unnecessary for research or management purposes, because an index that tracks changes in a population within appropriate time and geographic constraints could provide the information necessary to make management decisions or to evaluate the impact of a control program. We review research on a passive tracking index where observations are made on a series of tracking plots placed on lightly used dirt roads. The number of sets of tracks (individual intrusions) are recorded for each species of interest on each plot on consecutive days. The mean number of intrusions over the plots is calculated for each day for each species. The index is the mean of the daily means. These design and measurement methods present valuable advantages over most traditional tracking plot methods. Because no scents or baits are used as attractants, no conditioning of animals to the plots biases the results. This also permits multiple species, predator and prey alike, to be simultaneously monitored. Using the number of animal intrusions as observations produces results that are far more sensitive to change than tracking surveys where only presence or absence of spoor are recorded for each plot. Of particular importance, the statistical properties inherent to this data structure permit calculation of standard errors, confidence intervals and statistical tests, without subjectively subdividing the data.     

Fractals and search paths in mammals

The fractal index by Katz and George (1985) for thecharacterization of planar curves is applied to wolf search pathsrecorded by radio-telemetry. All the sets of paths studied showspatial patterns whose complexity is between a straight line anda true random walk. Females fractal dimensions show significantchanges throughout the year, depending on the state of their lifecycle (normal, breeding and wandering). There are alsodifferences between males and females, but not between adults andnon-adults. The results are discussed with regard to wolffood-search strategies.     

新疆大蒜叶疫病的研究:Ⅱ病菌越冬致病性病害流行因素及防治

 试验结果表明,本菌(Stemphylium vesicarium(Wallr.) Simons)以病残体上分生孢子和菌丝体在田间和冷藏室越冬,9月至翌年6月检查,分生孢子萌发率为16.4~41.3%。人工接种试验指出,不论有无伤口,病菌均可侵染大蒜,但洋葱与大葱在伤口接种条件下病情较重。在自然条件下,大蒜的斑点型病状出现于6月下旬,7月为病情高峰期。影响病情的天气因素,主要是7月份温度和7月中旬的降水量(r=0.69)。如果7月雨次多、雨时长,病情即极为严重,可导致蒜田绝收。化学防治试验结果,以腐霉利防效最佳。从7月上旬开始,每间隔10~13天喷药1次。喷药2~3次即可取得较好的防治效果。     

莴笋根茎部病害的病状特征及防治措施

对莴笋灰霉病、腐败病、软腐病这3种常见莴笋根茎部病害的病原、侵染循环、流行规律、危害症状进行了探讨,最后提出相应的综合防治措施。     

自动导航插秧机路径跟踪系统稳定性模糊控制优化方法

为了提高自动导航插秧机路径跟踪系统的稳定性,提出了一种利用模糊控制调整纯追踪模型前视距离的路径跟踪方法。在考虑自动转向系统一阶惯性环节的情况下,建立插秧机运动学模型,分析了在跟踪直线时纯追踪模型的稳定性条件;基于此稳定性条件,以速度和横向偏差为输入,以前视距离为输出,建立模糊控制模型实时调整纯追踪模型的前视距离;以洋马VP6E型水田插秧机为实验平台对所提出方法进行了实验验证,结果证明,该方法能有效提高路径跟踪系统的稳定性。     

昆明地区奶牛临床型乳房炎的病原与发生特点

 本文旨在探索昆明地区奶牛临床乳房炎的病原特点,为本病的防治提供科学依据。 1987～1990年期间,对昆明地区4个农场和个体户的93例临床型乳房炎的306份乳样进行了病原的分离与鉴定。从这些乳样共检出15个科,23个属的30种病原,共113株。其中包括主要病原81株,检出率为87.1%(81/93),混合感染病原32株,混合感染率为39.5%(32/81),培养阴性率为12.9%(12/93)。调查结果表明:该病在雨季发病率最高;年龄以3～6岁的牛发病率最高;在发病乳室中,以后乳室,尤其是右后乳室较为多见。     

蝴蝶兰细菌性褐斑病鉴定

本文首次报道蝴蝶兰细胞性褐斑病在我国大陆的发生，对分离到的菌株经形态特性，培养性状，致病性以及生理生化测定，确定引起广州地区蝴蝶兰细胞性褐斑病的病原菌为：Ｐｓｅｕｄｏｍａｍａｓ ｃａｔｔｌｅｙａｅ Ｓａｖｕｌｅｓｏｕ。     

大樱桃褐斑病病原菌鉴定与田间流行动态研究

【目的】为有效防控大樱褐斑病,【方法】采用传统形态学鉴定方法、单胞分离法和柯赫氏法则,开展了樱桃褐斑病原菌、田间流行学和品种抗病性研究。【结果】研究结果明确了褐斑病病原菌为核果钉孢菌(Passalora circum-scissa)。田间流行动态研究结果表明,6月下旬或7月初始见褐斑病发生,7月下旬进入发病高峰,与降雨程度关系密切;7月下旬或8月初检测到褐斑病菌孢子,8月中旬至9月中旬为孢子释放高峰期。不同大樱桃主栽品种褐斑病发生程度差异较大。明确了烟台樱桃褐斑病初次防治关键期为6月中旬。【结论】研究结果为有针对性地田间防控大樱桃褐斑病提供了理论依据。     

基于ASTUKF的分布式农业车辆路面参数辨识方法

针对分布式驱动农业车辆在路面参数辨识过程中,因路面环境变化出现的状态模型误差和时变噪声,导致辨识结果发散的问题,提出了基于自适应强跟踪无迹卡尔曼滤波(Adaptive strong tracking unscented Kalman filter, ASTUKF)的辨识方法。与传统内燃机农业车辆相比,分布式驱动可以直接获取驱动轮的状态信息,结合含有峰值附着系数和极限滑转率的μ-s曲线模型,建立了无迹卡尔曼滤波(Unscented Kalman filter, UKF)辨识算法的状态方程和量测方程。同时,将强跟踪滤波(Strong tracking filter, STF)和自适应滤波(Adaptive filter, AF)引入辨识算法,用以提高对多变环境的识别精度和鲁棒性,并采用奇异值分解(Singular value decomposition, SVD)解决了迭代过程中出现的非正定矩阵的问题。仿真试验结果表明,在突变噪声环境工况下,ASTUKF辨识结果可以快速收敛至目标值附近,且不受突变噪声的影响,各驱动轮峰值附着系数估计结果的平均绝对误差(Mean absolute error...     

梨火疫病病原菌的分离鉴定及室内抑菌药剂筛选

为明确新疆库尔勒地区梨火疫病致病菌,并筛选有效防治药剂。采用平板划线法获得分离物,结合致病性测定、形态学特征与分子生物学技术综合鉴定致病菌,采用“药液-菌液共培养法”与“抑菌圈法”测定16种杀菌剂对其室内毒力。鉴定分离物为Erwinia amylovora。16种杀菌剂对梨火疫病菌均有抑制作用。其中,0.3%四霉素AS抑菌效果最好,EC₅₀为2.968μg/mL。研究结果对梨火疫病田间药剂防治提供科学依据。