合唱的力度处理

在合唱艺术表现中，力度是作品情感表现的重要因素。力度的强弱变化对比直接影响着作品的情感表现力。只有了解和掌握不同时期合唱力度的特点，才能准确合理地运用声音力度的强弱变化对比，塑造不同的音乐形象，表达作品丰富的内涵。     

从信息构建看未来的知识管理

本文从信息构建出发 ,进而引申到知识管理与知识推理 ,最终提出了知识基础工程。在设计并实现自然语言的语法开发平台时 ,产生了构建知识库的设想。利用语法开发平台 ,就可以对自然语言的语法进行开发 ,加上一个好的算法 ,就可以对大规模文本进行自动分析。对分析过的句子进行内容提取 ,并用面向对象方法和逻辑形式进行格式化 ,得到以面向对象为特征的常识知识库和以逻辑命题为特征的专家知识库 ,这应该是知识发现、知识管理的最高层次 ,也是知识工程的核心     

Automatic Alphabet Recognition

The last step of the Information Retrieval process is to display the found documents to the user. However, some difficulties might occur at that point. English texts are usually written in the ASCII standard. Unlike the English language, many languages have different character sets, and do not have one standard. This plurality of standards causes problems, especially in a web environment, where one may download a document with an unknown standard. This paper suggests a purely automatic way of finding the standard which was used by the document writer based on the statistical letters distribution in the language. We developed a vector-space-based method that creates frequencies vectors for each letter of the language and then matches a new document's vectors to the pre-computed templates. The algorithm was applied on various types of corpora in Hebrew, Russian and English, and provides an efficient solution to the stated problem in most cases.     

微博信息可信度分析研究综述

简述微博信息可信度研究的背景和意义,并对微博信息可信度分析等相关概念进行界定;对微博信息可信度的研究成果进行梳理,指出这些研究的不足,并认为微博信息可信度分析的关键问题是微博信息特征的提取和可信度分析方法的设计;结合微博信息的特点及已有研究成果,指出微博信息可信度分析的核心技术包括自然语言处理、社会网络分析、机器学习与数据挖掘等;最后总结全文,对微博信息可信度分析的未来发展方向进行展望,为进一步研究提供参考。     

论自动文摘及其分类

自动文摘 ,即利用计算机自动编制文摘 ,是信息时代的需要。本文讨论了文摘的不同定义、特点和功能。目前 ,文摘的分类方法不适用于自动文摘的分类 ,因此 ,本文试着从多角度对自动文摘系统进行了分类 ,这样的分类根据自动文摘的特点进行的划分 ,是对自动文摘分类的一种总结 ,可以作为构造自动文摘系统和思考自动文摘发展方向的参考和借鉴。最后 ,概述了中文自动文摘系统的研究状况 ,展望了自动文摘的发展趋势。     

Two decades of suspect evidence for adaptive molecular evolution—negative selection confounding positive-selection signals

There has been a large literature in the last two decades affirming adaptive DNA sequence evolution between species. The main lines of evidence are from (i) the McDonald-Kreitman (MK) test, which compares divergence and polymorphism data, and (ii) the phylogenetic analysis by maximum likelihood (PAML) test, which analyzes multispecies divergence data. Here, we apply these two tests concurrently to genomic data of Drosophila and Arabidopsis. To our surprise, the >100 genes identified by the two tests do not overlap beyond random expectation. Because the non-concordance could be due to low powers leading to high false negatives, we merge every 20–30 genes into a ‘supergene’. At the supergene level, the power of detection is large but the calls still do not overlap. We rule out methodological reasons for the non-concordance. In particular, extensive simulations fail to find scenarios whereby positive selection can only be detected by either MK or PAML, but not both. Since molecular evolution is governed by positive and negative selection concurrently, a fundamental assumption for estimating one of these (say, positive selection) is that the other is constant. However, in a broad survey of primates, birds, Drosophila and Arabidopsis, we found that negative selection rarely stays constant for long in evolution. As a consequence, the variation in negative selection is often misconstrued as a signal of positive selection. In conclusion, MK, PAML and any method that examines genomic sequence evolution has to explicitly address the variation in negative selection before estimating positive selection. In a companion study, we propose a possible path forward in two stages—first, by mapping out the changes in negative selection and then using this map to estimate positive selection. For now, the large literature on positive selection between species has to await reassessment.     

博古学研究与欧洲近代早期自然史的复兴探析

博古学者对史料的搜集和整理,为后世史学家的深入研究提供材料,并使古希腊、古罗马时期探究事物的根本方法,即自然史在近代欧洲再次盛行。随着自然史的复兴,历史研究开始对知识本身有更深刻的诉求。博古学者借用自然史的方法,质疑古代作品的真实性,将实物史料中蕴含的经验知识纳入历史研究的范畴。学者们提高了对事实的敏感度,想象和虚构也变得不再容易,开始与古典史学那种修辞、演讲的功用有了明显的区分。     

论综合实践活动课程开发的自然维度

综合实践活动课程是基于现实世界视野对生活的探究与体验,自然世界本身成为课程.超越对自然的役用与膜拜,走向对自然的理解、欣赏与看护,是综合实践活动自然维度开发的基本原则."在自然中"的自然探究、"关于自然"的自然探究和"为了自然"的自然探究是综合实践活动自然维度开发的基本内容.此外,在开发的过程中尚须注意季节的变化、在自然探究中渗透人文精神并引导学生慎重对待探究结论.     

Natural selection contributes to the myopia epidemic

The prevalence of myopia, or nearsightedness, has skyrocketed in the past few decades, creating a public health crisis that is commonly attributed to lifestyle changes. Here we report an overall increase in the frequencies of myopia-associated mutant alleles over 25 years among participants of the UK Biobank. Although myopia itself appears to be selected against, many of the mutant alleles are associated with reproductive benefits, suggesting that reproduction-related selection inadvertently contributes to the myopia epidemic. We estimate that, in the UK alone, natural selection adds more than 100 000 myopia cases per generation, and argue that antagonistic pleiotropy be broadly considered in explaining the spreads of apparently disadvantageous phenotypes in humans and beyond.     

The cumulative and residual fatigue response associated with soccer-specific activity performed on different playing surfaces

ABSTRACT

This study aimed to assess the effect of playing surface (Natural [NT] and Artificial [AT] Turf) on the fatigue response to a soccer-specific exercise protocol (SSEP). Eighteen male soccer players completed the SSEP on NT and AT with pre-, post-, and 48 h post-assessments of eccentric knee flexor (eccKF) and concentric knee extensor peak torque (PT), peak countermovement (CMJ) and squat jump (SJ) height, and Nordic hamstring break angle. No significant main effects for surface or any surface and time interactions were observed for any of the outcome measures, except for eccKF PT recorded at 3.14 rad·s^-1, which was significantly lower 48 h post-trial in the AT condition (AT = 146.3 ± 20.4 Nm; NT = 158.8 ± 24.7 Nm). Main effects for time were observed between pre- and post-trial measures for eccKF PT at all angular velocities, Nordic break angle, CMJ and SJ height. Nordic break angle, and both CMJ and SJ height were significantly impaired 48 h post-trial when compared to pre-trial. The findings of the current study suggest surface dependent changes in eccKF PT which may have implications for recovery and subsequent performance after competition on AT.