This paper analyzes the status and the development trend of refrigerator fresh-keeping technologies domestically and internationally, introduces several popular fresh-keeping technologies, elaborates on the principles...This paper analyzes the status and the development trend of refrigerator fresh-keeping technologies domestically and internationally, introduces several popular fresh-keeping technologies, elaborates on the principles and characteristics of several fresh-keeping technologies, and put forth that the future research should be focused on the different needs of customers.展开更多
Input-output analysis is widely employed to analyze inventories of a product＇s embodied energy and environmental burdens. However, input-output analysis focuses only on the production stage and ignores other life cyc...Input-output analysis is widely employed to analyze inventories of a product＇s embodied energy and environmental burdens. However, input-output analysis focuses only on the production stage and ignores other life cycle phases. Input-output analysis is not exactly a LCA （life cycle assessment） method in the strict sense of ISO 14040 standards, which must cover all stages of a product＇s life cycle, ＂from the cradle to the grave＂, so to speak. A tiered hybrid LCA is a useful tool that covers all life cycle stages by combining a process analysis with the input-output analysis method. This study aims to extend input-output analysis to the use, disposal, and recycling stages by using matrix-based method. The new method is applied to the analysis of the embodied CO2 emissions of a refrigerator as a case study. The entire life cycle C02 emissions are estimated to be 2.9 tons, including indirect emissions, and the reduction in CO2 emissions due to recycling steel scrap is calculated as 48.5 kg. The authors conclude that the new method enables a consistent inventory analysis for all life cycle stages by combining process and input-output methods.展开更多
Morphologically divergent ecotypes arise in fish populations on postglacial time scales, and resource polymorphisms are often invoked to explain their origin. However, genetic recombination can constrain the ability o...Morphologically divergent ecotypes arise in fish populations on postglacial time scales, and resource polymorphisms are often invoked to explain their origin. However, genetic recombination can constrain the ability of divergent selection to pro- duce reproductive isolation in sympatry. Recombination breaks up favorable combinations of traits （＂adaptive suites＂） if indivi- dual traits are affected by different loci. Recombination also breaks up any association between traits under divergent selection and traits contributing to reproductive isolation. Thus, ecological speciation in the absence of preexisting barriers to gene flow is more likely when pleiotropy minimizes the number of loci involved. Here, we revisit research conducted by Carl Hubbs in the early 1900s on the effects of developmental rate on morphological traits in fishes. Hubbs＇ work provides a mechanism to explain how sympatric divergence by trophic polymorphism can occur despite the challenges of recombination. We consider the implica- tions of Hubbs＇ observations for ecological speciation with gene flow in fishes, as well as rapid evolution in captive fish popula- tions [Current Zoology 58 （1）： 21-34, 2012].展开更多
文摘This paper analyzes the status and the development trend of refrigerator fresh-keeping technologies domestically and internationally, introduces several popular fresh-keeping technologies, elaborates on the principles and characteristics of several fresh-keeping technologies, and put forth that the future research should be focused on the different needs of customers.
文摘Input-output analysis is widely employed to analyze inventories of a product＇s embodied energy and environmental burdens. However, input-output analysis focuses only on the production stage and ignores other life cycle phases. Input-output analysis is not exactly a LCA （life cycle assessment） method in the strict sense of ISO 14040 standards, which must cover all stages of a product＇s life cycle, ＂from the cradle to the grave＂, so to speak. A tiered hybrid LCA is a useful tool that covers all life cycle stages by combining a process analysis with the input-output analysis method. This study aims to extend input-output analysis to the use, disposal, and recycling stages by using matrix-based method. The new method is applied to the analysis of the embodied CO2 emissions of a refrigerator as a case study. The entire life cycle C02 emissions are estimated to be 2.9 tons, including indirect emissions, and the reduction in CO2 emissions due to recycling steel scrap is calculated as 48.5 kg. The authors conclude that the new method enables a consistent inventory analysis for all life cycle stages by combining process and input-output methods.
文摘Morphologically divergent ecotypes arise in fish populations on postglacial time scales, and resource polymorphisms are often invoked to explain their origin. However, genetic recombination can constrain the ability of divergent selection to pro- duce reproductive isolation in sympatry. Recombination breaks up favorable combinations of traits （＂adaptive suites＂） if indivi- dual traits are affected by different loci. Recombination also breaks up any association between traits under divergent selection and traits contributing to reproductive isolation. Thus, ecological speciation in the absence of preexisting barriers to gene flow is more likely when pleiotropy minimizes the number of loci involved. Here, we revisit research conducted by Carl Hubbs in the early 1900s on the effects of developmental rate on morphological traits in fishes. Hubbs＇ work provides a mechanism to explain how sympatric divergence by trophic polymorphism can occur despite the challenges of recombination. We consider the implica- tions of Hubbs＇ observations for ecological speciation with gene flow in fishes, as well as rapid evolution in captive fish popula- tions [Current Zoology 58 （1）： 21-34, 2012].
