Neutral models for testing landscape hypotheses

Neutral landscape models were originally developed to test the hypothesis that human-induced fragmentation produces patterns distinctly different from those associated with random processes. Other uses for neutral models have become apparent, including the development and testing of landscape metrics to characterize landscape pattern. Although metric development proved to be significant, the focus on metrics obscured the need for iterative hypothesis testing fundamental to the advancement of the discipline. We present here an example of an alternative neutral model and hypothesis designed to relate the process of landscape change to observed landscape patterns. The methods and program, QRULE, are described and options for statistical testing outlined. The results show that human fragmentation of landscapes results in a non-random association of land-cover types that can be describe by simple statistical methods. Options for additional landscape studies are discussed and access to QRULE described in the hope that these methods will be employed to advance our understanding of the processes that affect the structure and function in human dominated landscapes.     

Concentrations of constitutive alk(en)ylresorcinols in peel of commercial mango varieties and resistance to postharvest anthracnose

Mature green mango fruits of commercially important varieties were screened to investigate the levels of constitutive antifungal compounds in peel and to assess anthracnose disease after inoculation with Colletotrichum gloeosporioides. High-pressure liquid chromatography was used to quantify the levels of 5-n-heptadecenylresorcinol and 5-n-pentadecylresorcinol in the peel extracts. The fruit peel of the varieties ‘Kensington Pride’ and ‘Keitt’ were observed to have the highest levels of both 5-n-heptadecenylresorcinol (107.3–123.7 and 49.9–61.4 μg/g FW, respectively) and 5-n-pentadecylresorcinol (6.32–7.99 and 3.30–6.05 μg/g FW, respectively), and the fruits of the two varieties were found to have some resistance to postharvest anthracnose. The varieties ‘Kent’, ‘R2E2’, ‘Nam Doc Mai’, ‘Calypso’ and ‘Honey Gold’ contained much lower concentrations of resorcinols in their peel and three of these varieties were found to be more susceptible to anthracnose. Concentrations of 5-n-heptadecenylresorcinol were significantly lower at the ‘sprung’ and ‘eating ripe’ stages of ripening compared to levels at harvest. Concentrations of 5-n-pentadecylresorcinol did not differ significantly across the three stages of ripening. The levels of these two resorcinols were found to be strongly inter-correlated (P<0.01, r²=0.71), with concentrations of 5-n-heptadecenylresorcinol being an average 18 times higher than those of 5-n-pentadecylresorcinol. At the ‘eating ripe’ stage, significant relationships were observed between the concentrations of each type of alk(en)ylresorcinol and anthracnose lesion areas following postharvest inoculation, P<0.001, r²= 0.69 for 5-n-pentadecylresorcinol, and P<0.001, r²= 0.44 for 5-n-heptadecenylresorcinol.     

小麦叶疫病检疫研究

介绍了１９９２￣１９９５年间小麦叶疫病检疫研究的主要结果。研究证实我国局部地区已有叶疫病发生,分离得到了１１个小麦链格孢菌株,并研究了其生物学特性,确定了小麦链格孢的鉴定条件和鉴别标准,发现分生孢子链长度和分枝状况是区分类似种类的主要特征。提出了病株诊断方法和种子带菌的快速检验方法,后者包括吸水纸培养检验法和ＧＬＵＺＡ鉴别性培养基培养检验法,根据研究结果和国外发病动态,提出了有关检疫对策的建议。     

褐飞虱不同为害状损失率测定研究

本研究旨在为褐飞虱为害损失的调查提供直观、准确的参考依据。研究表明,褐飞虱各种田间受害状都有产量损失,各症状的产量损失率为２５．８％～９４．０％。以百穗实粒干重为统计标准,Ｆ＝１８８．７０４＊＊,达极显著差异水平。ＳＳＲ多重比较,不同水稻被害状之间损失梯度明显。产量因素剖析表明,褐飞虱的为害主要是导致结实率和千粒重显著降低。文中举例说明了研究结果的应用方法。     

杉木耐瘠薄速生优树子代测定及早期选择

在福建省洋口国有林场,对7年生的杉木耐瘠薄速生优树半同胞子代测定林进行调查和分析测定。参试的各家系间树高、胸径和材积生长量均差异极显著,说明在家系水平上存在明显的分化;从参试的18个家系中选择出23号等5个在瘠薄立地条件下生长表现优良的家系,树高、胸径和材积平均值分别达7.67 m、10.88 cm和0.043 6 m3,与第2代种子园子代相比,其材积现实增益达21.11%,通过这种后向选择所选出的耐瘠薄速生优良家系具有明显的生长优势和耐瘠薄性,可以作为杉木第3代建园材料的补充。     

水泵试验台快速夹紧机构的研制

水泵试验时，泵与管道的联接一般用法兰及螺栓联接，费时长，劳动强度大，自动化水平低。采用无螺栓联接、液压驱动的快速夹紧机构，能节约换件时间、减轻劳动强度、提高自动化水平。用灰铁制造运动副，使机构稳定性高，耐磨损。运动副用燕尾槽形式，运动间隙可调，磨损能够得到补偿。测压管与被夹紧件处于自由状态，密封面能紧密贴合，使密封可靠。该机构噪音小，占用空间少，生产率高。     

基于形式规约的软件测试用例自动生成技术研究

在Hierons提出的一种基于Z语言软件自动测试方法的基础上进行了拓展．该方法基于软件的Z语言规约；以HierOns提出的推理规则为基础，提出了分裂树的算法，将操作模式的约束条件转换为形如ViPi∧Qi的析取范式；然后根据析取范式将Z语言描述的操作模式划分为子操作模式；依据子操作模式的前置条件和后置条件，将子操作模式作为状态转换图的转换关系，构建了被测试软件的状态转换图；依据状态转换图，提出了相应的状态覆盖准则、转换关系覆盖准则和转换关系谓词覆盖准则等测试数据选择准则．     

县级测土施肥化验室建设中存在的问题与建议

我省县级测土施肥化验室建设中或多或少存在一些如选址不当、水电配置不符、质量控制不健全等问题,本文针对这些问题提出搞好实验室标准化设计,从而进行系列化实验、达到一个具有较高技术水平和管理水平的测土施肥化验室。     

影响反力式滚筒制动试验台检测精度的因素

针对目前国内大部分汽车检测站使用的反力式滚筒制动试验台的检测数据存在较大差异的问题。详细分析了各种相关因素对汽车制动检测性能的影响以及正确使用反力式滚筒制动试验台的方法。     

不同氮磷钾组合搭配对佛手茶产量效应的影响初报

以茶叶目标产量为基础，以氮磷钾肥料不同组合搭配进行L9（3^4）正交试验，结果氮磷钾肥取2：1：1水平为最优化配方组合，处理4（A281C2）、处理6（A283C1）较接近最优化配方组合，但经经济效益分析，只有处理6（A283C1）单产582．00kg／667m^2，纯收入2973．59元／667m^2为最佳组合。由此认为在粘质红壤施肥，应以氮肥为主，配合施用速效磷肥，即尿素32．60kg／667m^2、钙镁磷66.18kg／667m^2、氯化钾7．50kg／667m^2，纯N14．996kg／667m^2，N：P2O5：K2O=1：0．75：013为最佳组合较合理。佛手茶是大叶品种，适量增施氮磷肥，有利于促进新梢的生长而提高产量.