生计安全研究的可视化分析

以Web of science核心库中1991~2016年间收录主题为“livelihood security”的文献为基础,应用CiteSpace软件,采取突现词分析、关键词共现分析、文献共被引分析等方法对生计安全研究进行可视化分析。研究发现,干旱、健康、妇女、艾滋病、粮食安全、难民等是生计安全研究的前沿领域;生计安全研究热点主要包括生计结果类、生态环境类、生计策略类和重点地区类;生计安全研究的知识基础主要包括粮食安全、海洋资源、气候变化适应性等研究领域;从研究内容来看,中国生计安全研究主要包括自然资源与粮食安全、自然灾害与生计安全、快速城镇化与生计安全、气候变化与生计安全等4个方面。

New-generation Migrant Workers' Urban Adaptation: A Case Study of Jianggan District in Hangzhou City

New-generation migrant workers are the " elite" among migrant workers,and whether they can really adapt to the city is one of the real problems to be urgently solved during China's new urbanization,related to the success of new urbanization construction. From the perspective of livelihood capital,this paper uses the measuring indicators in line with the new-generation migrant workers' livelihood characteristics,to analyze the typical characteristics and causes of new-generation migrant workers' urban adaptation in Jianggan District of Hangzhou City based on field survey data. In the study,it is found that the new-generation migrant workers' urban adaptation characteristics are focused on life adaptation,work adaptation and cultural adaptation,but the adaptation in the three areas is not good and there is a big room for improvement.

Assessment of Regional Vulnerability to Natural Hazards in China Using a DEA Model

This paper presents a new method for quantifying regional vulnerability to natural hazards in China. In recent decades, the study of vulnerability has gained a position of centrality in natural hazards research. How to quantitatively assess vulnerability has raised much interest in academia. Researchers have proposed a variety of methods for quantitative assessment. But these methods are very sensitive to weights set for subindices. As a result, analytic results are often less convincing. A model based on data envelopment analysis(DEA) is used for the assessment of regional vulnerability to natural hazards in an attempt to improve existing analytical methods. Using a regional natural disaster system framework, this article constructs an input-output DEA model for the assessment of regional vulnerability, and takes China’s mainland as a case study area. The result shows that the overall level of vulnerability to natural hazards in China's Mainland is high. The geographical pattern is that vulnerability is highest in western China, followed by diminishing vulnerability in central China, and lowest vulnerability levels in eastern China. There is a negative correlation between the level of regional vulnerability and level of regional economic development. Generally speaking, the more economically developed a region, the lower its regional vulnerability.

A genetically engineered Escherichia coli that senses and degrades tetracycline antibiotic residue

Due to the abuse of antibiotics,antibiotic residues can be detected in both natural environment and various industrial products,posing threat to the environment and human health.Here we describe the design and implementation of an engineered Escherichia coli capable of degrading tetracycline(Tc)-one of the commonly used antibiotics once on humans and now on poultry,cattle and fisheries.A Tcdegrading enzyme,TetX,from the obligate anaerobe Bacteroides fragilis was cloned and recombinantly expressed in E.coli and fully characterized,including its Km and kcat value.We quantitatively evaluated its activity both in vitro and in vivo by UVeVis spectrometer and LC-MS.Moreover,we used a tetracycline inducible amplification circuit including T7 RNA polymerase and its specific promoter PT7 to enhance the expression level of TetX,and studied the dose-response of TetX under different inducer concentrations.Since the deployment of genetically modified organisms(GMOs)outside laboratory brings about safety concerns,it is necessary to explore the possibility of integrating a kill-switch.Toxin-Antitoxin(TA)systems were used to construct a mutually dependent host-plasmid platform and biocontainment systems in various academic and industrious situations.We selected nine TA systems from various bacteria strains and measured the toxicity of toxins(T)and the detoxifying activity of cognate antitoxins(A)to validate their potential to be used to build a kill-switch.These results prove the possibility of using engineered microorganisms to tackle antibiotic residues in environment efficiently and safely.