Identifying obstacles to reducing the use of antibiotics to control porcine proliferative enteropathy

Proliferative enteropathy (PE) is an enteric disease of pigs that results in diarrhoea, reduced growth rate, reduced feed conversion efficiency and sometimes death. A survey of 13 pig veterinary practitioners in Australia was conducted to determine: (1) PE control strategies (antibiotics and vaccination), (2) how the efficacies of these strategies are evaluated and (3) how reliance on antibiotics could be reduced by increasing vaccine adoption. Antibiotics were routinely prescribed in the diets of weaner, grower and finisher pigs by 9/13, 10/13 and 8/13 veterinarians, respectively, if vaccination was not implemented. Water-soluble antibiotics were prescribed less frequently than in-feed antibiotics. Efficacy of control strategies was assessed most often through reduced clinical signs (diarrhoea, 'tail-ender' pigs, death) and reduced lesion incidence at abattoir postmortem inspection. Twelve practitioners had recommended PE vaccination to their clients in the previous 6 months. Barriers to continued vaccine implementation included perceived lack of efficacy for pigs housed in bedded systems, high cost relative to medication and difficulties in vaccinating pigs post-weaning.     

健全农村公共物品供给中农民需求表达机制的探讨

从农民需求表达与农村公共物品供给的关系入手,揭示出农民需求表达与公共物品最优供给的内在联系,说明了建立健全农民需求表达机制在促进农村公共物品供给中起着举足轻重的作用。从农民、农民组织和政府三个层面剖析了当前我国农民需求表达机制中存在的问题并提出健全和完善的对策建议。     

公共基础化学实验微型化教学改革探讨

将微型实验与常规实验仪器规格和试剂用量进行了对比,并进行了试验。微型化学实验具有减少环境污染、节约实验经费、节省实验时间和实验室空间、培养学生科学创新的能力等优点,微型化化学实验为研究性学习提供了一个崭新的化学实验教学模式,有利于学生综合素质的提高。     

Sulphur speciation and turnover in soils: evidence from sulphur K-edge XANES spectroscopy and isotope dilution studies

Sulphur K-edge X-ray absorption near edge structure (XANES) spectroscopy was used to quantify S species in humic substance extracts from ten soils from the UK, China and New Zealand, which differ in land use and agricultural management. XANES spectroscopy showed the presence of most reduced (sulphides, disulphides, thiols and thiophenes), intermediate (sulphoxides and sulphonates) and highly oxidised S (ester sulphates) forms, with the three groups representing 14-32%, 33-50% and 22-53% of the organic S in the humic substance extracts, respectively. Land use had a profound influence on the relative proportions of S species. Well-drained arable soils generally had a higher proportion of organic S present in the most oxidised form than the grassland soils collected nearby, whereas paddy soils showed a more reduced profile due to episodic flooding. In the Broadbalk Classical Experiment at Rothamsted, reversion of an arable system to grassland or woodland in the 1880s resulted in an increase of the most reduced and intermediate S species at the expense of the most oxidised S species. Long-term applications of farmyard manure to an arable plot also shifted S species from the most oxidised to the intermediate and the most reduced species. Sulphur immobilisation and gross mineralisation were determined in seven soils using the ³⁵S isotope dilution method. Gross mineralisation during a 53-day incubation correlated more closely with the amounts of the most reduced and intermediate S species than with the most oxidised S species, suggesting that the former (C-bonded S) were the main source of organic S for mineralisation in the short-term.     

农作物的红边特征与农学参数的关系

The hyperspectral reflectance of the canopy and the leaves on the main stem for six varieties, two each of rice, corn, and cotton crops, were measured at different growth stages with an ASD FieldSpec Pro FR^TM to analyze red edge characteristics for leaf area indices (LAI), aboveground biomass, as well as the chlorophyll, carotenoid, and nitrogen content, emphasizing comparative differences on the red edge parameters. The results showed a ‘double peak' phenomenon for the red edge of the canopy spectra but not for the leaves. There were ‘increase' and ‘decrease' change rules for the red edge position, λ_r, the red edge slope, Dλ_r, and the red edge area, S_r, of the canopy spectra for all 3 crops with a ‘blue shift' for λ_r of the leaf spectra for all 3 crops as the development stages progressed. For rice, corn, and cotton the LAI and fresh leaf mass had highly significant correlations (P < 0.01) so the red edge parameters λ_r, Dλ_r, and S_r of their canopy spectra. Additionally, for all crops the chlorophyll-a, chlorophyll-b, total chlorophyll, and carotenoid content of the leaves all had highly significant (P < 0.01) correlations to their λ_r. For rice, the nitrogen content of the leaves in g kg^-1 and phytomass for a unit area of land in g m^-2 also had a highly significant (P < 0.01) correlation to λ_r, Dλ_r, and S_r of the canopy spectra.     

生态公益林补偿标准确定的问题、方法与建议

生态公益林补偿是生态公益林建设的一项重要内容,如何合理有效地确立生态公益林补偿标准,是解决区域经济发展与生态环境保护矛盾关键。笔者在查阅文献的基础上,概括了我国现有生态补偿标准现状以及存在的主要问题,并对生态公益林补偿标准确定的影响因素和主要方法进行了总结和阐述,最后对如何完善生态补偿标准确定提出几点建议。     

广州河涌景观变更对城市公共生活的影响分析——以东濠涌改造为例

广州水岸公共景观的变更影响着城市及人们的公共生活。本文通过分析东濠涌的沿岸公共活动变迁及其2010年的改造实例，探讨水岸环境与沿岸公共生活类型之间的关系。     

政府行为与公共文化事业:基于“十一五”规划的内容分析

研究以随机抽样方式选择11份由各级政府出台的＂十一五＂规划文本为语料,以研究者编制的编码工具对这些资料进行了内容分析,结合分析中各项数据,研究者对＂规划涉及的具体公共文化机构、资源保障与支持途径、规划实施过程中的联动机制、规划目标和规划实施的评估＂等5个方面的问题进行分析和讨论。     

论房屋征收与补偿过程中的维权机制

随着现阶段城市建设速度的加快，各地因拆迁行为引发的争议越来越激烈。为了更好地协调城市发展与私人权益的关系，2011年1月21日国务院颁布了《国有土地上房屋征收与补偿条例》（简称《征收条例》，下同）。与先前的《城市房屋拆迁管理条例》相比较，《征收条例》无论在立法的价值目标、具体的实施机制方面都有很大的区别。以《征收条例》和相关立法作为制度框架，构建并逐步完善房屋征收与补偿过程中的维权机制，有助于使得包括《征收条例》在内的上述立法得以贯彻实现，从而使得利益博弈在市场经济、法治国家的轨道上进行。     

论影响麻花钻切削因素之间的关系

学生搞不清楚麻花钻刃磨时几何角度之间的关系,导致麻花钻头的刃磨失败,最终使学生形成了麻花钻内容太难,麻花钻刃磨起来太麻烦的结论。用图示、口诀配合文字讲解的方式讲解标准麻花钻切削部分之间的关系,学生易于接受。