半干旱黄土区典型林地土壤水分消耗与补给动态研究

通过对半干旱黄土丘陵沟壑区几种典型林地生长季土壤水分进行动态监测,研究不同林种对土壤水分消耗和补给的影响。结果显示,土壤总含水率大小依次为草地、沙棘、河北杨、油松、山杏,并且这一次序主要来源于120 cm深度（相对稳定层）以下的差异;不同林地及草地土壤含水率季节变化表现基本一致,3—8月波动下降,8—10月持续上升;各林地及草地土壤水分在0-60 cm内变化活跃,60-120 cm内由上至下逐渐趋于稳定,120-200 cm内保持相对稳定;林种、土壤深度、月份3种因素单独作用和交互作用均造成土壤水分差异显著;水分补给期后各林地土壤水分仍处于一定亏缺状态。

Behavioral and physiological flexibility are used by birds to manage energy and support investment in the early stages of reproduction

Interest in phenotypic flexibility has increased dramatically over the last decade, but flexibility during reproduction has received relatively little attention from avian scientists, despite its possible impact on fitness. Because most avian species maintain atrophied reproductive organs when not active, reproduction in birds requires major tissue remodeling in preparation for breeding. Females undergo rapid （days） recrudescence and regression of their reproductive organs at each breeding attempt, while males grow their organs ahead of time at a much slower rate （weeks） and may maintain them at maximal size throughout the breeding season. Reproduction is associated with significant metabolic costs. Egg production leads to a 22%-27% increase in resting metabolic rate （RMR） over non-reproductive values. This is partly due to the activity of the oviduct, an organ that may allow females to adjust reproductive investment by modulating egg size and quality. In males, gonadal recrudescence may lead to a 30% increase in RMR, but the data are inconsistent and general conclusions regarding energetic costs of reproduction in males will require more research. Recent studies on captive female zebra finches describe the impacts of these costs on daily energy budgets and highlight the strategies used by birds to maintain their investment in reproduction when energy is limited. Whenever possible, birds use behavioral flexibility as a first means of saving energy. Decreasing locomotor activity saves energy during challenges such as egg production or exposure to cold temperatures and is an efficient way to buffer variation in individual daily energy budgets. However, when behavioral flexibility is not possible, birds must rely on flexibility at the physiological level to meet energy demands. In zebra finches breeding in the cold, this results in a reduced pace of laying, likely due to down-regulation of both reproductive and non-reproductive function, allowing females to defend minimal egg size and maintain reproductive success. More research involving a range of species in captive and flee-living conditions is needed to determine how phenotypic flexibility during tissue remodeling and early reproductive investment translates to natural conditions and affects fitness [Current Zoology 56 （6）： 767-792, 2010].

An unequal clustering routing protocal for wireless sensor networks based on genetic algorithm

The imbalance of energy consumption in wireless sensor networks(WSNs)easily results in the“hot spot”problem that the sensor nodes in a particular area die due to fast energy consumption.In order to solve the“hot spot”problem in WSNs,we propose an unequal clustering routing algorithm based on genetic algorithm(UCR-GA).In the cluster head election phase,the fitness function is constructed based on the residual energy,density and distance between nodes and base station,and the appropriate node is selected as the cluster head.In the data transmission phase,the cluster head selects single-hop or multi-hop communication mode according to the distance to the base station.After we comprehensively consider the residual energy of the cluster head and its communication energy consumption with the base station,an appropriate relay node is selected.The designed protocal is simulated under energy homogeneous and energy heterogeneity conditions,and the results show that the proposed routing protocal can effectively balance energy consumption,prolong the life cycle of network,and is appicable to heterogeneous networks.

Investigation of the environmental impacts of steel deck pavement based on life cycle assessment

To investigate the environmental impacts of steel deck pavement through the whole life cycle,the steel deck pavement was divided into five stages:raw materials production,asphalt mixture mixing,pavement construction,operation management,and pavement removing stage.Based on the process-based life cycle assessment(PLCA)method,the calculation methods of energy consumption and gas emissions of two typical steel deck pavement systems(EA+EA pavement and GA+SMA pavement)were determined.The data lists of two pavements were analyzed,and the calculation model was built.Four characteristic indices including primary energy demand(PED),global warming potential(GWP),acidification potential(AP)and respiratory inorganics(RI)were used to quantify the environmental impacts of two pavements.The results show that the environmental impact of the GA+SMA pavement is more than 1.3 times that of the EA+EA pavement.Moreover,the critical stage of energy-saving and emission-reduction of EA+EA pavement and GA+SMA pavement are the raw material production stage and asphalt mixture mixing stage,respectively.

Life Cycle Assessment of Biodegradable Polylactic Acid(PLA)Plastic Packaging Products—Taking Tianjin,China as a Case Study

In this paper, the life cycle assessment(LCA) method is used to evaluate and quantify the energy consumption and environmental impacts of biodegradable polylactic acid(PLA) plastic packaging from the five stages of raw material acquisition, raw material transportation, product production, products use and final disposal. Seven impact categories were selected for the impact analysis: abiotic depletion potential fossil fuels(ADP), global warming potential(GWP), acidification potential(AP), eutrophication potential(EP), photochemical ozone formation potential(POCP), human toxicity potential(HTP), and terrestrial ecotoxicity potential(TETP). The results of the LCA are discussed and the results show that production of products is the highest stage of the environmental impact. Meanwhile, in the entire life cycle, the top three environmental impact categories are GWP, ADP and HTP,which account for 32.63%, 24.83% and 14.01%, respectively. The LCA results show that the environmental impact can be reduced in several ways: reducing the consumption of electricity, increasing the input of new energy, increasing the conversion rate of materials in the production process, using organic and water-soluble fertilizers instead of conventional fertilizers, using environment-friendly fuels and establishing a sound recycling system.

Energy and environmental life-cycle assessment of passenger car electrification based on Beijing driving patterns

This paper examines the energy and environmental benefits within the whole life cycle shifting from traditional gasoline vehicles to electrified advanced vehicles under regional real-world driving behaviors. The advance vehicles focus on family passenger cars and include battery electric vehicles （BEVs）, plug-in hybrid electric vehicles （PHEVs）, and hybrid electric vehicles （HEVs）. The GREET （greenhouse gases, regulated emissions, and energy use in transportation） model is adopted with regional circumstances modifications, especially the UF （utility factors） of PHEVs. The results show that the electrified vehicles offer great benefits concerning energy consumption, greenhouse gas （GHG） emissions as well as urban Particulate Matter 2,5 （PMz.s） emissions. Compared to conventional gasoline vehicles, the life-cycle total energy reduction for advance vehicles is 51% to 57%. There is little difference on energy reduction among the HEVs, PHEVs and BEVs, with the energy mix shifting from petroleum to coal for the stronger electrification. The reductions of GHG emissions are 57% for HEV, 54% to 48% for PHEVs with 10 miles to 40 miles CD range, and 40% for BEV. The life-cycle and local PM2.5 emissions are discussed separately. The life-cycle PM2.5 emissions increase with vehicle electrification and reach a maximum for the BEV which are 5% higher than the conventional vehicle （CV）. However, electric vehicles can shift PM2.5 emissions from vehicle operation to upstream operations and help mitigate PM2.5 emissions in urban areas. The local emissions of PHEVs and BEVs can be reduced by 37% to 81% and 100% compared with CVs.

Comparative literature study between investigations in foreign Science Citation Index journals and Chinese core domestic journals in the treatment of low back pain with acupuncture

OBJECTIVE： To investigate the quality and meth- ods of clinical research literature published in for- eign Science Citation Index （SCI） journals studying the treatment of low back pain with acupuncture. To conduct a comparative study with clinical re- search literature published in Chinese core domes- tic journals, and to understand the prospects of cur- rent research trends of acupuncture clinical studies in Western countries and China. METHODS： Studies on clinical acupuncture treat- ment of low back pain in English SCI journals and four Chinese core domestic journals dated from 2002 to 2012 were sourced and summarized for this study. Objective analysis and evaluation on the differences in subject and scope of study on low back pain by foreign and Chinese researchers were conducted. RESULTS： Forty-seven English studies and 115 Chi- nese studies met our inclusion criteria. A keyword search revealed different kinds of low back pain re- lated conditions in English and Chinese studies. The English studies were broad in scope, while the Chinese studies were more focused. There were al-so differences in the understanding and definition of concepts and study orientation. CONCI.IJSION： More study should be undertaken to understand the contradictions that acupuncture faces in view of modern research to further ad- vance the field.