Horizontally integrated aquaculture development: Exploring consensus on constraints and opportunities with a stakeholder Delphi

Horizontal integration represents a technically viable opportunity for aquaculture producers to reduce environmental impacts whilst apparently enhancing production efficiency and gaining from economies of integration. Despite significant research, pilot-scale developments and recommendations advocating adoption by producers, uptake has been limited. Consequently, research was undertaken, invoking the iterative Delphi methodology, to explore consensus amongst a multidisciplinary stakeholder panel concerning the nature and significance of constraints and opportunities associated with horizontal integration. Round 1 participants (n = 24) submitted 84 and 94 statements identifying constraints and opportunities, respectively, within physical, environmental, managerial, institutional, economic and social subcategories; aggregating similar statements produced 29 distinct constraints and 27 opportunities for subsequent evaluation. Friedman’s randomised block analysis indicated similar rank patterns (P < 0.001, two-tailed) in the distribution of weights assigned to opportunities and constraints by panel members after round 3. Kendall’s coefficient of concordance (W) indicated that agreement on constraints was ‘strong’ and confidence in rank patterns ‘high’; agreement was ‘very strong’ and confidence ‘high’ to ‘unusually high’ concerning opportunities. Agreement within subcategories ranged from ‘unusually high’ for physical and environmental constraints and opportunities to ‘moderate’ for institutional and social constraints. Economic, physical and managerial constraints were ranked highest, as compared with environmental and physical opportunities. These findings confirm that constraints and opportunities associated with horizontal integration are multifaceted and that a multidisciplinary, systems-based approach to aquaculture development is critical. Furthermore, the stakeholder Delphi constitutes a promising approach to facilitating constructive dialogue and consensus-building amongst diverse, antagonistic and hierarchical stakeholder groups frequently associated with aquaculture development.     

Quantitative transmission characteristics of different H5 low pathogenic avian influenza viruses in Muscovy ducks

EU annual serosurveillance programs show that domestic duck flocks have the highest seroprevalence of H5 antibodies, demonstrating the circulation of notifiable avian influenza virus (AIV) according to OIE, likely low pathogenic (LP). Therefore, transmission characteristics of LPAIV within these flocks can help to understand virus circulation and possible risk of propagation. This study aimed at estimating transmission parameters of four H5 LPAIV (three field strains from French poultry and decoy ducks, and one clonal reverse-genetics strain derived from one of the former), using a SIR model to analyze data from experimental infections in SPF Muscovy ducks. The design was set up to accommodate rearing on wood shavings with a low density of 1.6 ducks/m²: 10 inoculated ducks were housed together with 15 contact-exposed ducks. Infection was monitored by RNA detection on oropharyngeal and cloacal swabs using real-time RT-PCR with a cutoff corresponding to 2–7 EID50. Depending on the strain, the basic reproduction number (R₀) varied from 5.5 to 42.7, confirming LPAIV could easily be transmitted to susceptible Muscovy ducks. The lowest R₀ estimate was obtained for a H5N3 field strain, due to lower values of transmission rate and duration of infectious period, whereas reverse-genetics derived H5N1 strain had the highest R₀. Frequency and intensity of clinical signs were also variable between strains, but apparently not associated with longer infectious periods. Further comparisons of quantitative transmission parameters may help to identify relevant viral genetic markers for early detection of potentially more virulent strains during surveillance of LPAIV.     

水平双圆盘式有机肥撒肥器的试验研究

为提高有机肥撒施均匀性,设计了水平双圆盘式撒肥器。利用拟水平法正交试验设计方法,研究水平双圆盘的转速、输送速度、两盘安装中心距和圆盘结构对撒肥均匀度的影响。得出了撒肥器结构和工作参数的合理组合:圆盘转速200 r/min、输送速度800 mm/s、两盘安装中心距750 mm和盘面偏心安装两组叶片。     

砾石对土壤水分入渗(扩散）的影响研究

砾石(>2 mm的碎石)广泛存在于世界的部分土壤中。近几年来,随着山地土壤的开发与利用,砾石对土壤物理和侵蚀过程的影响研究受到广泛重视。不同砾石具有不同持水性,砾石含量、大小和形状以及存在位置对土壤入渗有不同影响。     

完善生态补偿横向转移支付方式的必要性分析

由于环境过度利用、资源过度开发等原因使我国面临发展社会经济和保护环境的双重压力,因此有必要建立健全生态补偿机制,尤其是大力完善生态补偿横向财政转移支付方式。笔者从阐述生态补偿机制与生态补偿财政转移支付的内涵入手,实证分析了我国现行生态补偿财政转移支付机制的问题与不足,在此基础上提出了应该建立并完善生态补偿横向财政转移支付的建议。     

木工平刨床的振动测试与分析

通过对MB-504B木工平刨床的振动实测,得到了工作台而的振动加速度量值。这些测试数据对于了解木工平刨床的振动状况,研究减振,提高加工精度以及对制定木工机床振动的测试方法和振动标准提供了参考数据。     

病虫粪便在蝗虫微孢子虫病水平传播中的作用研究

本文采用室外采集与室内接种饲养相结合的方法，研究草原蝗虫取食孢子的数量与其粪便中孢子的含量之间的关系。结果表明，以１０７个／ｍｌ接种时，接种３０天后粪便中孢子的含量达 ９．０ ×１０５个／ｇ，以１０６个／ｍｌ接种二次后，在接种后１２天，其粪便中抱子的含量即可达 １．３×１０５个／ｇ；取食的孢子的数量越多，粪便中孢子的含量也越高，出现得越早，为研究微孢子虫病在田间的水平流行途径及其持续治蝗机理提供了科学依据。     

超声检测在糖厂榨辊轴环向裂纹检测中的应用

文章主要介绍对糖厂榨辊轴环向裂纹的超声检测,使用新的方法对环向裂纹深度作出判定,为企业生产决策提供有力支持。     

真核生物水平基因转移研究进展

综述了真核生物水平基因转移的4个种类：内共生和大量的基因转移、原核到真核的基因转移、真核到真核的水平基因转移和真核到原核的水平基因转移,以及真核水平基因转移的4种检测方法：序列相似性分析法、密码子分析法、基因分布分析法和系统发育树分析法,并分析了水平基因转移在真核基因组进化中的作用。