ABSTRACT
The level of sustainable livelihoods, as a yardstick for measuring the social development of migrants, is of great importance to the sustainable development of the region. Based on the analysis of the policy logic of ecological protection and high-quality development in the Yellow River basin, this paper constructs a "ternary" system model and evaluation index system for sustainable livelihoods of farm households in the ecological resettlement areas of the upper Yellow River, and proposes that the harmonious relationship between the three basic dimensions of economy, society and environment is the key to evaluate the sustainable livelihood level of farm households in ecological resettlement areas. Based on the comprehensive evaluation index to assess the comprehensive development level of ecological resettlement areas, we introduced the coupling coordination degree and constructed the coordinated development degree model of "economic-social-environmental" system to characterize the sustainable livelihood level. Through the data of 1116 questionnaires and in-depth interviews in the ecological migrant resettlement area of Liujiaxia reservoir in the upper reaches of the Yellow River basin, the sustainable livelihood status and spatial distribution differences of farm households in 14 townships in the region were evaluated, and the validity of the indicator system was empirically tested. Finally, sustainable livelihood strategies for farm households in the ecological resettlement areas of the upper Yellow River are proposed for the economic, social and environmental dimensions, and the indicator system is further revised. The evaluation system can not only advance the research paradigm of sustainable livelihood assessment for farmers in ecological migrant resettlement areas but can also be widely guided and applied to the sustainable development of ecological migrant practices in China.
Subject(s)
Farmers , Rivers , Humans , China , Farms , Family Characteristics , Conservation of Natural ResourcesABSTRACT
Recently, flexible metacomposites with negative permittivity have triggered extensive interest owing largely to their promising applications in areas such as sensors, cloaking, and wearable and flexible electronic devices. In this paper, flexible silver nanowire/carbon fiber felt (AgNW/CFF) metacomposites with weakly negative permittivity were fabricated by adjusting their composition and microstructure. Along with the formation of a conductive AgNW network, the resulting composites gradually presented metal-like behavior. Interestingly, weakly negative permittivity with a small absolute value (as low as about 6.4) and good flexibility were observed in the composites with 3.7 wt% AgNWs. The one-dimensional silver nanowires contribute to reducing the overall electron density of the resulting composites, which is responsible for the weakly negative permittivity. As the AgNWs increased, the Drude-like negative permittivity got stronger owing to the enhancement of the electron density. Further investigation from the perspective of microelectronics revealed that the negative permittivity is dependent on the inductive characteristic. The proposed design strategy for AgNW/CFF composites with tunable negative permittivity opens up a new approach to flexible metacomposites.
ABSTRACT
The prevalence of Perkinsus sp. infection in Manila clam Ruditapes philippinarum was investigated in the coastal areas of east China. Thirteen groups of clams were collected from 5 sites: Dandong and Qingdao Bays (Yellow Sea), Weifang Bay (Bohai Sea), and Ningbo and Fuzhou Bays (East China Sea). The clams were tested for perkinsosis infection using Ray's fluid thioglycollate medium culture assay. Perkinsus sp. was found in samples from all 5 sites from May 2008 to May 2009. Infection prevalence ranged from 43.75 to 95.83%, and was significantly higher in October than in May. The only 3 uninfected groups of clams were collected from Weifang Bay, the site farthest from the ocean. There was no difference in the prevalence of infection among the remaining 4 sites. The conserved internal transcribed spacer regions of the ribosomal RNA gene complex in each of the Perkinsus sp. isolates were amplified by PCR. The resulting amplicons were sequenced and phylogenetically analyzed. All the Perkinsus isolates were identified as Perkinsus olseni.
