两阶段领域自适应学习

针对领域自适应问题中源域和目标域的联合分布差异最小化问题,提出两阶段领域自适应学习方法.在第一阶段考虑样本标签和数据结构的判别信息,通过学习一个共享投影变换,使投影后的共享空间中边缘分布的差异最小.第二阶段利用源域标记数据和目标域非标记数据学习一个带结构风险的自适应分类器,不仅能最小化源域和目标域条件分布差异,还能进一步保持源域和目标域边缘分布的流形一致性.在3个基准数据集上的实验表明,文中方法在平均分类准确率和Kappa系数两项评价指标上均表现较优.     

Attitude-behaviour dissonance regarding the importance of food preservation for customers

The aim of the study was to identify the importance of individual food product attributes (the use of preservatives, processing method, shelf-life period and nutritional value) as well as their relation to the purchase behaviour. To achieve this, consumer preferences were decomposed in conditions of full access to information, and data was compared with actual consumer behaviour related to making purchasing decisions in front of the store shelf. Based on data from 338 respondents, conjoint analysis and repeated ANOVA measurements were carried out, allowing to eliminate individual behavioural patterns. The results showed a dissonance between the consumers attitudes towards the attributes and their shopping behaviour. The processing method was the most important declared attribute for consumers, meanwhile this information was the least searched for during purchase. At the same time, shelf-life period marked as the least important was the main information searched for by consumers when shopping. The results also show a clear dislike towards the use of microwaves as a preservation method, while traditional thermal preservation was marked as the most positive for consumers. In addition, consumers were classified into 3 heterogeneous groups, identifying differences in the preferences of food attributes. The obtained results have practical value relating not only to the preferences of individual attributes, but also to their various variants. The results can be a guide for companies to properly label food products. The indicated dissonance illustrates the educational gap and related insufficient motivation to get to know the product before buying it. This is extremely important in connection with technological development and new food processing methods.     

低温等离子体处理模式对冷藏南美白对虾中假单胞菌的抑菌效果及机理研究

摘 要：目的 探究低温等离子体(cold plasma, CP)处理模式对冷藏南美白对虾中常见荧光假单胞菌(Pseudomonas fluorescens)的抑菌效果及其作用机制。方法 通过CP直接处理和循环处理P. fluorescens,研究了两种处理模式下臭氧含量动态变化对P. fluorescens的生长曲线、细胞活力,生物膜形成、细胞壁、细胞膜完整性和南美白对虾菌落总数及假单胞菌数等指标的影响。结果 两种处理模式在CP处理3 min或3 cycles后,包装内臭氧含量达到最高值,分别为(850±10) mg/m3和(874±20) mg/m3。CP循环处理模式使得臭氧含量随处理循环数递增,因此获得更长的臭氧存在时间从而具有更大的抑菌能力。P. fluorescens生长曲线表明CP处理使得菌体延迟期变长且对数生长期推迟。此外,CP处理后的P. fluorescens细胞活力显著下降(P<0.05),CP-1 min,CP-3 min和CP-3 cycles组的细胞活力分别为33.03%、5.90%和4.82%。同时相比CP-3 min组,CP-3 cycles组的P. fluorescens生物膜OD值下降27.61%。碱性磷酸酶(alkaline phosphatase, AKP)活性和核酸蛋白泄漏量结果表明,细胞壁和细胞膜完整性受损可能是P. fluorescens失活的直接原因。对虾保鲜测试结果证实,贮藏第6 d,CP-3 cycles组虾体中的菌落总数和假单胞菌数相比CP-3 min组分别降低了58.02%和79.54%。结论 CP循环处理模式通过延长对臭氧与对虾的暴露时间,提高了对P. fluorescens的灭活效果,同时还具有更优越的保鲜能力。本研究为开发基于CP技术的新型保鲜技术应用提供了理论参考。 关键词：低温等离子体;荧光假单胞菌;抑菌机制;保鲜     

四川盆地东南地区龙马溪组页岩气有效保存区综合评价

受差异构造边界的制约,四川盆地东南地区(简称川东南)中新生代发生差异构造变形,使得保存条件成为控制该区下古生界页岩气富集的主要因素。为此,从制约保存条件的直接原因——构造作用出发,对该区页岩气保存条件进行了综合评价。首先以构造研究为先导,立足于中新生代差异构造变形方式和强度,将评价区划分为7个构造形变带,并对各构造形变带的断裂规模、断裂密度、顶底板岩性和厚度、目的层埋深、构造形态和裂缝间距指数等影响因素进行系统揭示,确立页岩气有效保存区的评价指标和标准,建立页岩气保存条件综合评价体系。在此基础上,依据该区页岩气保存条件最优评价参数标准,对7个构造形变带下志留统龙马溪组页岩气的保存条件进行了宏观评价。结果表明:齐岳山断裂以西地区的保存条件整体上好于东侧;齐岳山断裂以东地区,以武隆断褶带的保存条件为最好,其次为彭水断褶带和黔江断褶带,道真叠加断褶带、务川叠加断褶带和沿河叠加断褶带相对较差。     

冰温保藏技术在生鲜肉保藏中的应用

生鲜肉营养丰富,但在加工、运输和储存过程中易受微生物和外界环境的影响发生腐败变质,因此保鲜方式极其重要。冰温保藏较传统冷藏技术可更加有效地延长产品的货架期,同时也不会因冻结而造成产品品质下降,因此近年来在生鲜肉的保藏逐渐受到关注。目前对冰温保藏技术在生鲜肉的应用还缺乏全面的综述,因此,本文以冰温保藏技术为研究对象,阐述了其原理以及在禽肉、畜肉、水产品保鲜中的应用研究进展,论述了冰温保藏技术在生鲜肉保藏中的应用前景,介绍了冰温保藏技术与真空、气调和生物保鲜剂相结合的保藏方式在生鲜肉中的应用研究进展,为冰温保藏技术能更好地应用于生鲜肉中提供一些思路和研究方向,以期为冰温保藏技术的推广应用提供参考。     

申报世界遗产保护和永续利用人类瑰宝

目前中国的世界遗产地的发展存在重申报、轻管理,在全国范围内缺乏有效、统一的协调和管理,过度开发利用与被动保护管理等问题.中国应强化国家对世界遗产地工作的协调、领导和管理,注重对遗产资源的严格管理和科学利用,加强世界遗产地间的沟通交流与遗产资源保护的宣传等.     

关于城市工业遗产的保护和利用

工业遗产是城市的一种特殊语言,是一种特殊的历史记忆与景观,具有巨大的经济、社会人文与生态效益.对待已认定或尚未认定的工业遗产,我们需要从更广泛的层面、采取更灵活的方式进行保护,挖掘工业遗产潜在的价值,正视民族发展进程中的文明.     

遗产保护视角下的国家公园建设

国家公园是国家的重要遗产。该文首先从遗产保护的视角比较分析了北美和西欧两种不同的国家公园模式。其次,结合我国当前建设国家公园体制的现实需要,对我国的风景遗产特征,风景保护存在的问题进行梳理,指出在国家公园建设的探索中,我国比较注重研究借鉴美国的国家公园模式,但对西欧模式重视不够。最后,从国家公园体系、目标、管理机制等方面对我国的国家公园建设提出建议与思考。     

Reducing SO(2) in fresh pork burgers by adding chitosan

The use of 0.02 or 0.05% chitosan is proposed to reduce from 450 to 150mgkg(-1) the SO(2) required to preserve pork burgers aerobically packed and stored at 2°C for up to 21days under retail display conditions. The effects of chitosan and/or sulfite addition and the storage time were determined in fresh (color deterioration, lipid oxidation, pH, total viable counts, Escherichia coli and coliforms, Salmonella, appearance and odor) and cooked (appearance, odor, flavor and texture) burgers. The addition of either 0.02 or 0.05% chitosan was not detected by sensory analysis, and extended the shelf life of low-SO(2) burgers from 7 to 14days. Chitosan enhanced the preservative effects of sulfite at a low dose, acting on the main causes of meat deterioration (bacterial spoilage, color stability and lipid oxidation), and provided good sensory properties to fresh and cooked pork burgers.