Classification of Tibetan lakes based on variations in seasonal lake water temperature

Widespread lakes on the Tibetan Plateau （TP） are valuable archives for investigating climate and environment changes, which could provide essential information on the mechanisms of past climate changes on the TP and their interaction with the global climate systems. However, there is a lack of in-depth investigation of modern limnological processes in the Tibetan lakes, which hampers the understanding of paleolimnological records and lake ecosystem succession. In this study, we performed continuous temperature monitoring at two lakes, Bangong Co, a freshwater lake in the western TP, and Dagze Co, a brackish lake in the central TP, in order to characterize the patterns of seasonal temperature variability, stratification, and mixing. Temperature data for an entire hydrological year demonstrate that Bangong Co is a dimictic lake and that Dagze Co is a meromictic lake. The higher salinity in the deep water at Dagze Co prevents the lake from overturning completely, and this finding is supported by simulations using a physical limnological model Lake Analyzer. Continuous lake water temperature monitoring provides fundamental data for classifying Tibetan lakes, as well as the hydrological basis for understanding their pa- leolimnological records and ecosystem succession.     

DNA sequencing technology based on nanopore sensors by theoretical calculations and simulations

DNA sequencing based on nanopore sensors is a promising tool for third-generation sequencing technol- ogy because of its special properties, such as revolutionized speed and low cost. With about two decades of nanopore technology development, the pioneering work has dem- onstrated the ability of nanopores to perform single-mole- cule detection and DNA sequencing. However, the microscopic mechanisms of DNA transport dynamics through nanopores remain largely unknown. Currently, DNA microscopic transport in a nanopore is difficult to characterize and several unexpected experimental obser- vations are equivocal. This limitation can be resolved using theoretical calculations and simulations. These computa- tional methods can monitor the entire dynamic process that DNA undergoes in solution at a single-atom resolution that can accurately unveil the mystery of DNA transport dynamics and predict certain unexpected phenomena. This paper mainly reports the recent applications of computa- tional and simulation methods applied to the study of DNA transport through both biological and synthetic nanopores. We hope the theoretical calculations and simulations of DNA transport through nanopores can benefit the design of DNA sequencing devices.     

国外期刊亮点

正发现新分子标靶有助治疗阿尔兹海默症香港科技大学理学院院长叶玉如领导的研究团队,发现了可以治疗阿尔兹海默症的新分子标靶,有机会进一步开发成为治疗该症的新药。研究团队针对导致患者认知障碍的EphA4蛋白异常活化,成功从传统中药中筛选出一种天然化合物,证实可以抑制EphA4的活性,并改善阿尔兹海默症病症。这项研究6月4日在线发表于PNAS上。阿尔兹海默症主要影响65岁以上的人士,患者在出现认知能力下降等症状前就已经患上了阿尔兹海默症。淀粉样蛋白被视为导致患者出现认知功能障碍的主因。研究发现,淀粉样蛋白会过度激活EphA4蛋白,     

不受DEM空间分辨率影响的地形指数计算

为了减小数字高程模型(DEM)分辨率对地形指数计算的影响,开发了一种不受DEM空间分辨率影响的地形指数计算方法.选取汉江上游褒河流域作为研究区域,通过引入分辨率因子考虑DEM空间分辨率对单宽上坡集水面积的影响,应用分形方法处理DEM空间尺度对地形坡度的影响,将该算法应用到褒河流域DEM数据的计算中.结果表明:此法可以成功地由低分辨率的DEM数据获得与目标高分辨率精度相仿的地形指数分布,能在一定程度上消除DEM空间分辨率对地形指数计算的影响,因而对无资料地区的水文预报有着十分重要的现实意义.     

Construction and visualization of high-resolution three-dimensional anatomical structure datasets for Chinese digital human

The objective of the China Digital Human Project （CDH） is to digitize and visualize the anatomical structures of human body. In the project, a database with information of morphology, physical characteristics and physiological function will be constructed. The raw data of CDH which was completed in the Southern Medical University is employed. In Huazhong University of Science and Technology （HUST）, the frozen section images are preprocessed, segmented, labeled in accordance with the major organs and tissues of human beings, and reconstructed into three-dimensional （3D） models in parallel on high performance computing clusters （HPC）. Some visualization software for 2D atlas and 3D models are developed based on the new dataset with high resolution （0.1 mm× 0.1 mm × 0.2 mm）. In order to share, release and popularize the above work, a website （www.vch.org.cn） is online. The dataset is one of the most important parts in the national information database and the medical infrastructure.     

Millennial temperature reconstruction based on tree-ring widths of Qilian juniper from Wulan, Qinghai Province, China

The climate of the past 1000 years is an important context for evaluating the recent climate warming. However, there are few 1000-year-long climate reconstructions with annual resolution in the Qinghal-Tibet Plateau. In this paper, a dendroclimatic analysis was conducted for the radial growth of Qilian juniper from the upper forest limit in Wulan, Qinghai Province. The results of correlation analysis between the tree-ring widths and the climate variables indicate that the growth of junipers at the upper forest limit is mainly limited by low temperatures of September, November and February of the pregrowth season, and July of the current growth season. There is no significant correlation between the tree-ring widths and precipitation. A mean temperature from the previous year＇s September to the current year＇s April was reconstructed for the Wulan area since A.D. 1000. The reconstruction can explain 40.8% of the instrumental variance in the calibration period （1856-2002）. The reconstruction shows that the 20th century is the warmest 100 years, and the 1990s is the warmest decade during the past 1000 years, while the coldest 100 years and decade occur at 1600-1699 and 1642-1651, respectively. The variations are verified well by the temperature reconstruction of the middle Qilian Mountain （QL） and the total organic carbon （TOC） in the Qinghai Lake sediments. The comparison of our reconstruction with the annual temperature reconstruction of extra-tropical Northern Hemisphere suggests that the climate of Wulan during the Medieval Warm Period is of obvious regional specialty, but there was a good response to the climate of hemispheric scales during the recent 400 years.     

图像处理中分辨率的选取

分辨率的合理选取是影响图像处理效果的一个重要因素.本文在明晰分辨率概念的基础上,就扫描--处理--输出这样一种日常的图像处理过程中分辨率的选取方法作了探讨,提出了分辨率选取的一般规律.     

基于小波变换的图像超分辨率增强算法

视频图像超分辨率增强技术具有重要的研究价值。文章在研究和分析小波变换理论的基础上提出了一种基于小波变换的图像超分辨率增强算法,该算法充分利用小波多分辨率分解思想,体现图像分辨率降低的自然过程;通过估计高分辨率小波系数,经插值逆变换可得到重构的高分辨率图像。实验结果证明该算法克服了传统的插值方法致使图像高频部分损失、细节被模糊的缺点,是超分辨率图像处理的一种行之有效的途径,具有一定的实用价值。     

一种信息加密与唯一识别的全新方法——陈-Mobius变换的一种新应用

某些常用数字波形的陈-Mobius变换的计算结果被应用到信息加密与唯一识别中,形成了一种全新的信息加密与识别的方法。在信息加密时,要被加密的信息经转换与被编码后被调制在某个调制波上数个周期,并经过某种手段记录在某种介质上,可以携带到任何地点。而当需要恢复原来的信息时,先以同样的手段从介质中读取出已调制的信息,尔后将其乘以与调制波相正交的解调波形,并经过一个低通滤波器或积分器得到被编码的信息,最后再经与初始转换相反的过程得到原始的信息。本方法中,解调波与调制波是常用数字波形及其陈-Mobius逆变换,这两个函数族之间相互正交的一一对应性与唯一性,使它也可成为唯一识别的一种新方法。而且,信息加密调制与记录的时间均可人为选择,并以某种方式记录于同一个介质中,它们可帮助使加密信息无法破译。     

CCD生物显微摄像系统自组装及其应用

采用计算机及相关部件组装了生物显微图像数码摄像系统,并采用该系统对蚕豆根尖染色体、昆虫复眼以及蝴蝶口器进行了图像拍摄;对实验结果以CCD生物显微摄像系统的优点进行了分析和讨论.