How pre-service teachers navigate trade-offs of food systems across time scales: a lens for exploring understandings of sustainability

In response to the increasing recognition of the need for sustainable food systems, research on students’ and educators’ knowledge of food systems and sustainability more broadly has grown but has generally focused on what people ‘fail’ to understand. Moving away from this deficit approach, the present study used semi-structured interviews to explore how 12 pre-service teachers (PSTs) in the US consider sustainability in terms of the trade-offs – or concurrent costs and benefits – associated with using different agricultural resources over short, medium, and long terms. Drawing upon the constructs of framing, metacognition, and complex causality, the study found that the majority of PSTs referred to indirect experiences of seeing or hearing about agricultural resources to demonstrate stable knowledge of short-term trade-offs and construct tentative knowledge about medium-term trade-offs. Few described long-term trade-offs. Most participants also acknowledged some gaps in their knowledge in discussing trade-offs across the different time scales. Findings suggest the importance of leveraging and building upon educators’ (and ultimately students’) prior experiences to build their understanding of complex trade-offs that underlie food systems. The study also illustrates the value of using the concept of trade-offs across time scales to explore people’s conceptions and understandings of sustainability.     

基于指数法的陕西省耕地和粮食时空变化分析

本文尝试性地提出了相对粮食承载指数并结合李晓文等人提出的耕地变化强度指数，计算了陕西省101个县（区）2000年～2004年的耕地变化强度指数和相对粮食承载指数，分析了陕西省近年耕地和粮食生产时空差异：①陕西省近年人口增加，耕地减少，而粮食总产量和人均粮食占有量波动较大；②全省耕地变化空间差异显著，大部分县（区）耕地减少，少部分县（区）耕地有所增加或保持数量平衡；③以小康水平粮食标准400kg/人·年为参照，全省整体处于不足状态，101个研究县（区）中，有66个县（区）处于不足状态，1个县（区）处于临界状态，34个县（区）处于富余状态。针对陕西省耕地和粮食生产现状，应充分考虑区域差异，通过保护和合理利用现有的耕地、加强农业基础设施建设、改良品种、加强利用先进农业生产技术的应用、调整大农业结构等措施来提高粮食承载能力。     

质量信息揭示、逆向选择与食品安全

食品质量信息揭示是缓解食品市场中的"逆向选择"行为,提高食品安全水平的重要方式。基于食品的经验品和信任品特性,分析食品厂商如何通过自愿性信息揭示缓解食品市场中的逆向选择问题,以及政府如何通过强制性信息揭示保障食品安全。研究结果表明,对于自愿性信息揭示来说,信息揭示成本对于能否实现高质量厂商与低质量厂商的分离均衡至关重要,信息揭示在能为高质量厂商带来溢价收益的同时,应使低质量厂商出于成本考虑不敢进行虚假信息揭示;对于强制性信息揭示来说,信息揭示成本应促使厂商丧失生产不安全食品的动机,保障食品安全。     

地衣芽孢杆菌A－57碱性蛋白酶提取新工艺的探讨

研究了以Ｎａ＿２ＳＯ＿４为主要盐析剂提取碱性蛋白酶的工艺，分别就Ｎａ＿２ＳＯ＿４加量、ｐＨ和温度３个因素进行了试验，得出Ｎａ＿２ＳＯ＿４最佳用量为２５％、最佳ｐＨ为８．５和最适温度３０℃．其中Ｎａ＿２ＳＯ＿４加量是影响盐析的主要因素。本文还以有机溶剂丙酮对酶的提取作了初步研究，可考虑用于生产食品级碱性蛋白酶。     

<Emphasis Type="Italic">Enteromorpha compressa (L.) Greville</Emphasis> an edible green alga as a source of antiallergic principle (S)

Enteromorpha compressa a marine green algal species grows extensively in North coastal Andhra Pradesh. Besides its nutritional importance it has also been identified as source of anti-anaphylactic compound(s).E. compressa extracts alleviated the IgE levels raised against ovalbumin and other allergens in mice. Further,Enteromorpha extract also significantly down regulated the serum IgE levels in different murine models irrespective of their genetic background. The results obtained in this study suggest thatE. compressa extract has compound(s), which inhibit IgE immune response and may have potential in curing various types of allergies.     

转基因食品标签管制与消费者的知情选择权

转基因食品的标签管制在国内外引起了广泛的争论,很多组织和某些国家政府都强调通过强制性的标签政策保障消费者的知情选择权。但是本论文通过对国内外进行的一系列调查进行分析,发现消费者对于转基因食品的态度是多元化的。强制性标签制度在保护不喜欢转基因食品消费者利益的同时,却提高了食品成本,让全社会承担了成本,并不能真正的给消费者以知情选择权。分析表明,自愿性标签制度才能真正保障消费者的知情选择权。     

粮食综合生产能力与国家粮食安全

提高粮食综合生产能力,是确保国家粮食安全的重要战略性举措。随着城市化和工业化的快速推进,耕地、水资源、农业基础设施、种粮比较收益等方面的弊端相继凸显,不仅影响了粮食综合生产能力的进一步提升,甚至还可能危及到未来国家粮食的安全。为了实现国家粮食的长治久安,必须破除现存的瓶颈,构建粮食综合生产能力稳步提升的长效机制。     

隐喻的认知演变：汉语年俗证据

隐喻的认知研究成为最近三十年的热门话题。从汉语春节过年的食物、数字、装饰以及生肖等其他文化特征项目看隐喻,文章赞同认知观对于隐喻的认定：即隐喻是两个认识域的投射,概念隐喻存在并具有文化共核,以及隐喻普遍存在并对认知和思维有着重要的影响。     

Food for Thought in Restaurant Reviews

Coverage of food journalism has increased in contemporary media and restaurant reviews are a regular feature in newspapers. The reaction to a rating of zero for a restaurant in The Weekend Australian newspaper in 2016 highlighted the role and expectations of critics. It also raised the issue of whether this form of lifestyle journalism included traditional journalistic objectives, or was influenced more by commercial factors. In this environment, it is therefore valuable to explore whether restaurant reviews are more aligned with detached journalism or an extension of marketing. Utilising a content analysis, this pilot study examines the ratings of food critics in four broadsheet/quality newspapers in Australia and the United Kingdom. During the three years of the data collection, 550 restaurant reviews were coded. The pattern of review marks suggested more supportive judgements than critical ones, and was consistent with the softer side of journalism.     

从中国玉米生物乙醇发展分析生物能源对粮食安全的影响

本文以玉米生物乙醇为例,采用情景分析法定量分析“生物能源”与“吃饭”的关系.研究表明:(1)设定2020年生物乙醇的产量为1000万吨、1500万吨和2300万吨,玉米生物乙醇占生物乙醇的60％、40％和20％,则9个子情景所需玉米量最多3864万吨,最少560万吨;(2)结合其他玉米需求分析其供需关系,发现9个子情景均未达均衡,最大和最小缺口分别为4249万吨和945万吨,说明玉米生物乙醇的发展对玉米需求造成了影响.如对口粮和其他工业用粮进行更切合实际的预测,则供求情况会有所缓解,所以玉米生物乙醇的发展不会对“吃饭”问题造成太大影响.但若考虑库存和出口则会显得供求紧张.发展粮食能源是一场技术与战略的考验,积极引导技术创新,并保证最基本的粮食需求是未来的出路.