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Genomics, Proteomics & Bioinformatics 2008年第3期6卷 144-154页

作者： Frederick c.c. Leung School of Biological Sciences and Genome research centre The University of Hong Kong

Vertebrate genomes are characterized with cpG deficiency, particularly for Gcpoor regions. The Gc content-related cpG deficiency is probably caused by context-dependent deamination of methylated cpG sites. This hypothesis was examined in this study by comparing nucleotide frequencies at cpG flanking positions among invertebrate and vertebrate genomes. The finding is a transition of nucleotide preference of 5＇ T to 5＇ A at the invertebrate-vertebrate boundary, indicating that a large number of cpG sites with 5＇ Ts were depleted because of global DNA methylation developed in vertebrates. At genome level, we investigated cpG observed/expected （obs/exp） values in 500 bp fragments, and found that higher cpG obs/exp value is shown in Gc-poor regions of invertebrate genomes （except sea urchin） but in Gc-rich sequences of vertebrate genomes. We next compared Gc content at cpG flanking positions with genomic average, showing that the Gc content is lower than the average in invertebrate genomes, but higher than that in vertebrate genomes. These results indicate that although 5＇ T and 5＇ A are different in inducing deamination of methylated cpG sites, Gc content is even more important in affecting the deamination rate. In all the tests, the results of sea urchin are similar to vertebrates perhaps due to its fractional DNA methylation. cpG deficiency is therefore suggested to be mainly a result of high mutation rates of methylated cpG sites in Gc-poor regions.

关键词： cpG deficiency DNA methylation invertebrate genomes Gc content

Assessment of Man-made and Natural Hazards in the Surroundings of Hydropower Projects under construction in the Beas Valley of Northwestern Himalaya

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Journal of Mountain Science 2007年第3期4卷 221-236页

作者： Sanjeev Sharma Jagdish c. Kuniyal J. c. Sharma G.B. Pant Institute of Himalayan Environment & Development Himachal UnitMohal-Kullu 175 126Himachal Pradesh India Department of Geography Himachal Pradesh University

Mountain ecosystem,on the earth,has plenty of natural resources. In Himachal Pradesh all the rivers are snowfed and therefore rich in water resources. These resources have been supporting enough for the generation of electricity through introducing hydropower projects since the last decade. However,every developmental activity has its own negative impacts on the surrounding environment. Due to the fragile nature of topography and delicacy of ecology of the Himalaya,it results in lot of disturbances because of high degree of human interferences like construction of major hydropower projects. The increased extent of geological hazards,such as landslides,rock fall and soil erosion,have mainly due to alike developmental interventions in the natural ecosystem. So understanding and analysing such impacts of the hydropower projects have mainly been on the environment in various forms but natural hazards have been frequent ones. The present study,therefore,focuses mainly on the Parbati Stage Ⅱ (800 MW) and the Parbati Stage Ⅲ (520 MW) hydropower projects; both of which fall within the Kullu district of Himachal Pradesh. Based on the perception survey of the local communities,the existing land use pattern,status of total acquired land of the residents by hydropower projects,frequent natural hazards and resultant loss to the local communities due to upcoming construction of hydropower projects surrounding to the Parbati Stage Ⅱ and Ⅲ have been analysed in the paper. Also,the preventive measures to mitigate these adverse impacts have been suggested to strengthen these projects in eco-friendly manner in the mountain context.

关键词：高山生态系统水利工程生态环境水资源

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中红外量子级联激光气体检测系统

光子学报 2018年第4期47卷 67-74页

作者：蔺百杨党敬民郑传涛张宇王一丁吉林大学电子科学与工程学院集成光电子学国家重点联合实验室吉林大学实验区长春130012 吉林大学生物与农业工程学院长春130022

为了满足基于室温连续量子级联激光器(QcL)的中红外气体检测系统的需求,研制了板级量子级联激光器的驱动电路以及谐波锁相放大电路。通过信号发生电路产生高精度的直流偏置信号、低频锯齿波扫描信号和高频正弦波调制信号,控制激光器的... 详细信息

为了满足基于室温连续量子级联激光器(QcL)的中红外气体检测系统的需求,研制了板级量子级联激光器的驱动电路以及谐波锁相放大电路。通过信号发生电路产生高精度的直流偏置信号、低频锯齿波扫描信号和高频正弦波调制信号,控制激光器的工作电流,进而扫描/调制激光器的输出波长;为了探测痕量气体吸收光谱的二次谐波信号,并获得较高的信噪比,研制了锁相放大电路,主要包括倍频电路、正交转换电路和数据转换电路;为了提高系统的稳定性和可靠性,研制了高稳定性的线性供电电路以及保护电路.采用中科院半导体所研制的波长为4.76μm的QcL作为光源,开展了电学系统的功能验证实验以及气体检测实验.实验结果表明:QcL驱动电路线性度为0.006 3%,长期电流稳定度为5.0×10^(-5),QcL光强稳定度为5.07×10^(-4);锁相放大器系统具有较高的稳定性和较低的误差,一次谐波的最大误差在2.4%以内,二次谐波的最大误差在5.5%以内.通过动态配气方式开展了低浓度一氧化碳(cO)气体检测实验,在0~100×10^(-6)范围内,二次谐波信号的幅值与cO气体浓度具有较高的线性度(拟合优度>0.99),表明所研制的电学系统具有良好的稳定性和可靠性,为中红外cO气体的检测提供了安全可靠的保障.

关键词：光电子学中红外驱动电路锁相放大量子级联激光器气体检测

Body image in paediatric burns: a review

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Burns & Trauma 2018年第2期6卷 93-98页

作者： Ian c.c.King Department of Plastic and reconstructive Surgery St George's HospitalTootingLondon SW170QTUK

Burn injuries in children can result in life-long disfigurement. As medical and surgical techniques of burn management improve survival prospects more than ever before, body image adjustment is increasingly a central consideration in the care of burn-injured individuals. An appreciation that both physiological and psychosocial processes underpin such injuries is key to understanding wound healing. Perceptions of idealized body images in Western society challenge children and their families as they grow up with and adapt to disfigurement from burns. Whilst many studies have examined the psychosocial recovery of adults with burn injuries, few have considered the impact on burn-injured children. This paper explores the models of body image and discusses the relevance of these to research and practice in understanding how to manage burns in children.

关键词： Burns Body image children Paediatric burns Wound healing

Spatio-temporal snowmelt variability across the headwaters of the Southern rocky Mountains

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Frontiers of Earth Science 2017年第3期11卷 505-514页

作者： S.r. FASSNAcHT J.I. LOPEZ-MOrENO c. MA A.N. WEBEr A.K.D. PFOHL S.K. KAMPF M. KAPPAS ESS-Watershed Science Colorado State University Fort Collins CO 80523-1476 USA cooperative Institute for research in the Atmosphere Fort Collins CO 80523-1375 USA Geospatial centroid at cSU Fort Collins CO 80523-1019 USA Natural resources Ecology Laboratory Fort Collins CO 80523-1499 USA Geographisches Institut Georg-August-Universitat Gottingen 37077 Gottingen Germany Instituto Pirenaico de Ecologia CSIC Campus de Aula Dei 50080 Zaragoza Spain EASc-Watershed Science Colorado State University Fort Collins CO 80523-1482 USA

Understanding the rate of snowmelt helps inform how water stored as snow will transform into streamflow. Data from 87 snow telemetry （SNOTEL） stations across the Southern rocky Mountains were used to estimate spatio-temporal melt factors. Decreases in snow water equivalent were correlated to temperature at these monitoring stations for eight half-month periods from early March through late June. Time explained 70% of the variance in the computed snow melt factors. A residual linear correlation model was used to explain subsequent spatial variability. Longitude, slope, and land cover type explained further variance. For evergreen trees, canopy density was relevant to find enhanced melt rates; while for all other land cover types, denoted as non- evergreen, lower melt rates were found at high elevation, high latitude and north facing slopes, denoting that in cold environments melting is less effective than in milder sites. A change in the temperature sensor about mid-way through the time series （1990 to 2013） created a discontinuity in the temperature dataset. An adjustment to the time series yield larger computed melt factors.

关键词： melt SWE temperatutre SNOTEL tempera-ture sensor change

Quantifying the thermal damping effect in underground vertical shafts using the nonlinear autoregressive with external input(NArx) algorithm

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International Journal of Mining Science and Technology 2019年第2期29卷 255-262页

作者： Pedram roghanchi Karoly c.Kocsis Mineral Engineering Derpartment New Mexico Institute of Mining and Technology Mining Engineering Derpartment University of Nevada

As air descends the intake shaft, its infrastructure, lining and the strata will emit heat during the night when the intake air is cool and, on the contrary, will absorb heat during the day when the temperature of the air becomes greater than that of the strata. This cyclic phenomenon, also known as the "thermal damping effect" will continue throughout the year reducing the effect of surface air temperature variation. The objective of this paper is to quantify the thermal damping effect in vertical underground airways. A nonlinear autoregressive time series with external input(NArx) algorithm was used as a novel method to predict the dry-bulb temperature(Td) at the bottom of intake shafts as a function of surface air temperature. Analyses demonstrated that the artificial neural network(ANN) model could accurately predict the temperature at the bottom of a shaft. Furthermore, an attempt was made to quantify typical "damping coefficient" for both production and ventilation shafts through simple linear regression models. comparisons between the collected climatic data and the regression-based predictions show that a simple linear regression model provides an acceptable accuracy when predicting the Tdat the bottom of intake shafts.

关键词： Underground mining Vertical openings Thermal damping effect Artificial neural network Nonlinear autoregressive with external input(NArx)

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相分离对NEPE推进剂性能的影响

推进技术 2004年第1期25卷 93-96页

作者：张小平赵孝彬杜磊郑剑湖北航天化学技术研究所湖北襄樊441003 上海航天技术研究院上海200233

采用低温贮存及性能测试的方法研究了相分离对NEPE推进剂力学性能、危险性能以及燃烧性能的影响规律。在-20℃贮存条件下,增塑比小于等于2 8时NEPE推进剂存在相分离,相分离程度随增塑比降低及低温贮存时间增加而增大。发生相分离以后,N... 详细信息

采用低温贮存及性能测试的方法研究了相分离对NEPE推进剂力学性能、危险性能以及燃烧性能的影响规律。在-20℃贮存条件下,增塑比小于等于2 8时NEPE推进剂存在相分离,相分离程度随增塑比降低及低温贮存时间增加而增大。发生相分离以后,NEPE推进剂的低温力学性能下降并且最大伸长率的波动幅度增大;NEPE推进剂的冲击感度显著降低,摩擦感度有轻微增加;NEPE推进剂在2 94～8 83MPa范围内的燃速升高了0 3～0 7mm/s。为了稳定NEPE推进剂的性能,应采取有效措施控制NEPE推进剂的相分离。

关键词：硝胺推进剂聚醚推进剂相分离力学性能安全性能燃烧性能

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人工智能与软件工程的交叉

计算机科学 1989年第2期16卷 48-55页

作者： c.rich r.c.Waters 林金明

人工智能和钦件工程的交叉多年来一直是个十分活跃的研究领域。人工智能在软件工程上的应用至少在两个方面是令人感兴趣的。一是,人工智能对软件工程具有实际的重要性。人工智能技术可以提高程序员的生产率和程序的可靠性达一个数量级... 详细信息

人工智能和钦件工程的交叉多年来一直是个十分活跃的研究领域。人工智能在软件工程上的应用至少在两个方面是令人感兴趣的。一是,人工智能对软件工程具有实际的重要性。人工智能技术可以提高程序员的生产率和程序的可靠性达一个数量级。二是,软件工程已被证明是一个推动人工智能研究的领域。试图把人工智能技巧应用到程序设计任务方面已促进了知识表示和自动推理的进一步发展。

关键词：人工智能软件工程程序自动设计

Mxene（Ti3c2）的制备及其吸波性能

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硅酸盐学报 2018年第3期46卷 315-321页

作者：耿欣温广武杨思宇黄小萧闫旭吴赟哈尔滨工业大学材料科学与工程学院哈尔滨150001 山东理工大学材料学院山东淄博255091 天津城建大学材料科学与工程学院天津300384

基于氢氟酸（HF）选择腐蚀MAx相（Ti3Alc2）中Al原子层制备出Mxene的原理,通过IcP–OES测定滤液中Al离子含量而计算出Mxene的转化率。调节HF浓度、反应温度和时间制备出4种高纯Mxene材料;利用x射线衍射和扫描电子显微镜表征其晶体结构... 详细信息

基于氢氟酸（HF）选择腐蚀MAx相（Ti3Alc2）中Al原子层制备出Mxene的原理,通过IcP–OES测定滤液中Al离子含量而计算出Mxene的转化率。调节HF浓度、反应温度和时间制备出4种高纯Mxene材料;利用x射线衍射和扫描电子显微镜表征其晶体结构和微观组织形貌;用网络矢量仪测量其电磁参数并计算出反射率损耗。结果表明：高浓度40%HF组制备的Mxene吸波峰在低频（2～13 GHz）,样品H1和H2在厚度为3.5 mm时,分别在2.8和2.4 GHz处,反射率损耗达到极值：–7.5和–6 d B;而低浓度10%HF制备的高纯Mxene吸波在高频段（5～18 GHz）,当厚度为2 mm时,样品L1和样品L2分别在13.5和14.5 GHz处反射率损耗达到极值为–35和–16 d B。

关键词：碳化铝钛碳化物/氮化物腐蚀吸波

Glutathione-s-transferaseπas a target for the development of novel anticancer drugs

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Glutathione-s-transferaseπas a target for the development o...