Local discriminative spatial patterns for movement-related potentials-based EEG classification

A novel discriminant method, termed local discriminative spatial patterns (LDSP), is proposed for movement-related potentials (MRPs)-based single-trial electroencephalogram (EEG) classification. Different from conventional discriminative spatial patterns (DSP), LDSP explicitly considers local structure of EEG trials in the construction of scatter matrices in the Fisher-like criterion. The underlying manifold structure of two-dimensional spatio-temporal EEG signals contains more discriminative information. LDSP is an extension to DSP in the sense that DSP can be formulated as a special case of LDSP. By constructing an adjacency matrix, LDSP is calculated as a generalized eigenvalue problem, and so is computationally straightforward. Experiments on MRPs-based single-trial EEG classification show the effectiveness of the proposed LDSP method.     

The utility of deformable image registration for small artery visualisation in contrast-enhanced whole body MR angiography

PurposeAn investigation was carried out into the effect of three image registration techniques on the diagnostic image quality of contrast-enhanced magnetic resonance angiography (CE-MRA) images.MethodsWhole-body CE-MRA data from the lower legs of 27 patients recruited onto a study of asymptomatic atherosclerosis were processed using three deformable image registration algorithms. The resultant diagnostic image quality was evaluated qualitatively in a clinical evaluation by four expert observers, and quantitatively by measuring contrast-to-noise ratios and volumes of blood vessels, and assessing the techniques' ability to correct for varying degrees of motion.ResultsThe first registration algorithm (‘AIR’) introduced significant stenosis-mimicking artefacts into the blood vessels' appearance, observed both qualitatively (clinical evaluation) and quantitatively (vessel volume measurements). The two other algorithms (‘Slicer’ and ‘SEMI’), based on the normalised mutual information (NMI) concept and designed specifically to deal with variations in signal intensity as found in contrast-enhanced image data, did not suffer from this serious issue but were rather found to significantly improve the diagnostic image quality both qualitatively and quantitatively, and demonstrated a significantly improved ability to deal with the common problem of patient motion.ConclusionsThis work highlights both the significant benefits to be gained through the use of suitable registration algorithms and the deleterious effects of an inappropriate choice of algorithm for contrast-enhanced MRI data. The maximum benefit was found in the lower legs, where the small arterial vessel diameters and propensity for leg movement during image acquisitions posed considerable problems in making accurate diagnoses from the un-registered images.     

Size adaptation of turing prepatterns

Spontaneous pattern formation may arise in biological systems as primary and secondary bifurcations to nonlinear parabolic partial differential equations describing chemical reaction-diffusion systems. Such Turing prepatterns have a specified geometry as long as D/R ² (the diffusion coefficient of the morphogen D divided by the square of a characteristic length) is confined to a (usually) limited interval. As real biochemical systems like cleaving eggs or early embryos vary considerably in size, Turing prepatterns are unable to maintain a specified prepattern-geometry, unless D/R ² is varied as well. We show, that actual biochemical control systems may vary D _app/R², where D _app(k) is an apparent diffusion constant, dependent on enzyme regulated rate constants, and that such simple control systems allow Turing structures to adapt to size variations of at least a factor 10³ (linearly), not only in large connected cell systems, but in single cells as well.     

Selective attention and host-plant specialization

The importance of attentional processing is summarized, and the different ways in which selective attention is maintained, explained. Examples from arthropods are highlighted. The significance of selective attentiveness for insect herbivores is discussed. In the finding and selecting of host plants, insects should adopt the strongest or most clear-cut cues that override noise, and they should channel the appropriate sensory information efficiently. It is argued that achieving this end is difficult and costly because the information capacity of the sensory system is far greater than the capacity of the central nervous system to process it. It is suggested that the need to obtain a clear signal quickly and efficiently may be one of the factors favoring reduced diet breadth, and that the existence of highly specific and sensitive receptor neurons is an adaptation to the information-processing problem.     

黑龙江长白山森林生物量的时空变化分析

森林生物量碳储量的空间分布及其变化信息, 对揭示地表空间变化规律及驱动因子、分析评价森林生产力及生态功能具有重要意义。该文以20世纪70年代、80年代、90年代和21世纪初4个时期的遥感数据和同期的森林资源清查样地数据为基础, 应用遥感信息模型, 估算了黑龙江长白山地区的森林生物量, 分析了该地区森林生物量的时空动态变化, 以及森林生物量随高程、坡度和坡向的变化规律。结果表明: 该地区4个时期的森林平均生物量分别为81.56、44.27、48.27和54.82 t·hm^-2。4个时期总的森林生物量分别为5.37 × 10 ⁸、2.83 × 10 ⁸、3.06 × 10 ⁸和3.46 × 10 ⁸ t。20世纪70年代到21世纪初森林平均生物量和总的森林生物量都呈现出先降低后增加的趋势, 呈先下降趋势的主要原因是20世纪70-80年代以森林采伐为主, 后增加趋势的主要原因是实施天然林保护工程起到了很大的作用。该地区4个时期森林生物量随高程、坡度和坡向都表现出一致性的变化规律, 森林生物量随高程和坡度变化都呈先增加后减少的趋势, 导致这一现象的主要原因是, 高程、坡度和坡向变化引起了局地气候条件的变化, 从而直接影响森林生长环境, 造成森林分布的变化。森林生物量在200-400 m高程所占的比例最大, 约为35%, 在坡度5°-15°所占的比例接近50%。森林生物量在南坡和西南坡所占的比例最小, 为7%; 平坡所占的比例最大, 为28%; 南坡次之, 为19%。     

Use of mutual information arrays to predict coevolving sites in the full length HIV gp120 protein for subtypes B and C

It is well established that different sites within a protein evolve at different rates according to their role within the protein; identification of these correlated mutations can aid in tasks such as ab initio protein structure, structure function analysis or sequence alignment. Mutual Information is a standard measure for coevolution between two sites but its application is limited by signal to noise ratio. In this work we report a preliminary study to investigate whether larger sequence sets could circumvent this problem by calculating mutual information arrays for two sets of drug naïve sequences from the HIV gp120 protein for the B and C subtypes. Our results suggest that while the larger sequences sets can improve the signal to noise ratio, the gain is offset by the high mutation rate of the HIV virus which makes it more difficult to achieve consistent alignments. Nevertheless, we were able to predict a number of coevolving sites that were supported by previous experimental studies as well as a region close to the C terminal of the protein that was highly variable in the C subtype but highly conserved in the B subtype.     

以遗传信息为主线的遗传学教学架构及与其他课程的衔接

文章分析了遗传学教学面临的问题, 对遗传学教学架构以及与其他课程的内容衔接进行了探讨, 认为以遗传信息为中心重新组织教学内容, 保证遗传学教学内容的完整性和系统性, 凸显遗传学特色。根据遗传学25章教学内容的相关性重新组合成4个模块, 即遗传信息的遗传、遗传信息的储存、遗传信息的读取、遗传信息的复制、变异与进化。各模块紧扣遗传信息这一主题-- 也是遗传现象的内在联系, 每个模块讲解遗传信息的一个方面。对比与其他课程重叠的内容, 提取其中涉及遗传信息的部分, 重点讲解遗传信息的流动和变化。以遗传信息为主线的遗传学教学使课堂既充满遗传学特色, 又易于被学生接受和掌握。     

The Next-Generation Flora iFlora

The 21st century has witnessed a rapid development in technologies of molecular biology and computer informatics. Fundamental changes have taken place in means and methods in which humans take cognition of the world. Based on the currently available eFlora and combining this with elements of next generation sequencing techniques, DNA sequence data, geographical information system data and computer information technology, the next-generation Flora (iFlora) is bursting. Through a series of key technological innovations and integrations, the main objective of iFlora is to construct the next-generation Flora, which will fulfill the function of accurately and rapidly identifying species and acquiring species related digital information. iFlora will greatly advance the development of plant taxonomy, phylogenetics, evolutionary biology, ecology, biogeography, conservation biology and other related disciplines. Furthermore, iFlora will be a valuable tool for biodiversity conservation and sustainable utilization of biological resources, ecological security, public education and services, and will profoundly promote public understanding of biodiversity. The application of iFlora will tremendously nurture and boost the taxasphere and bioliterate world, and will be a new focal point that may reshape modern botany at the global and regional levels.     

东海区底层及近底层鱼类资源的空间异质性

运用空间自相关指数和变异函数分析东海区底层及近底层鱼类资源的空间自相关性和空间变异．其空间分布平均场的Geary c和Moran Ⅰ指数分别为0．38和0．52,各向同性随机变异占总变异的59．9％。表明其空间分布具有中等自相关特性,空间变异中由随机引起的变异大于由空间相关尺度过程引起的变异;各方向变异属于几何异向性,资源密度的年际变化与C、C0和C+C0均呈正相关,说明年际平均密度的增加由空间自相关变异和随机变异共同引起,随机变异略强于空间自相关变异。     

一维响应变量时最高无毒副作用剂量水平的识别

在毒性试验中,将暴露在某一剂量水平下的处理组与接受相当于零剂量处理的对照组相比,随着药物剂量的增加,感兴趣的变量通常会呈现一种递增的趋势。考虑不会导致风险显著增加的最高剂量,本文使用AIC(Akaike information criterion)方法得到该剂量水平的强相合估计,并且通过两组数据及模拟的结果来说明AIC方法的优良性.