按提交时间
按主题分类
按作者
按机构
  • 科技智库建设的多层次图景分析

    分类: 图书馆学、情报学 >> 情报学 提交时间: 2018-10-19 合作期刊: 《智库理论与实践》

    摘要: [目的/意义]当前我国科技智库建设普遍存在定位模糊和“库”重于“智”的问题,在新的决策背景下,找到“位”、提升“智”是当前科技智库建设的首要任务。[方法/过程]为此,本文以知识为基础,构建了科技智库建设的多层次图景:宏观层面的属性和边界关系图景,微观层面的研究体系及功能结构图景,中观层面的类型模式和组织演化图景,希望能够以“图”定“位”,以“知”明“智”。[结果/结论]从多个维度对科技智库进行了以“图”定“位”,并明晰了科技智库提高“智”识—提升“智”量—彰显“智”能的以“知”明“智”的路径,得出了一些新的认识:(1)认为知识与决策的双向互动是科技智库区别于其他智库的本质特征,将科技智库与其他智库的互动关系分为强联系与弱联系型,提出科技智库是智库体系中最为基础、最为能动、最为新锐的力量;(2)明确了核心科学在科技智库中的灵魂地位以及科技智库对核心科学的反哺作用,提出科技智库应超越当前“科技咨询”模式,向不确定性和决策风险高的后常规科学问题及策略拓展;(3)基于知识体系架构和领域跨度,将科技智库划分为综合型、专业型、咨询型、平台型4个类型,并在系统整合的基础上构建了科技智库的组织演化图景,基本明确了科技智库的建设路径及一流科技智库的建设方向。希望为个体科技智库建设和国家科技智库的宏观管理提供一些可能的靶标和参考,为科技智库理论和实践的多元化、系统化、有序化发展贡献力量。

  • Crassulacean acid metabolism (CAM) offers sustainable bioenergy production and resilience to climate change

    分类: 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间: 2016-05-04

    摘要:

    Biomass production on low-grade land is needed to meet future energy demands and minimize resource conflicts. This, however, requires improvements in plant water-use efficiency (WUE) that are beyond conventional C3 and C4 dedicated bioenergy crops. Here we present the first global-scale geographic information system (GIS)-based productivity model of two highly water-efficient crassulacean acid metabolism (CAM) candidates: Agave tequilana and Opuntia ficus-indica. Features of these plants that translate to WUE advantages over C3 and C4 bioenergy crops include nocturnal stomatal opening, rapid rectifier-like root hydraulic conductivity responses to fluctuating soil water potential and the capacity to buffer against periods of drought. Yield simulations for the year 2070 were performed under the four representative concentration pathway (RCPs) scenarios presented in the IPCC's 5th Assessment Report. Simulations on low-grade land suggest that O. ficus-indica alone has the capacity to meet ‘extreme’ bioenergy demand scenarios (>600 EJ yr−1) and is highly resilient to climate change (−1%). Agave tequilana is moderately impacted (−11%). These results are significant because bioenergy demand scenarios >600 EJ yr−1 could be met without significantly increasing conflicts with food production and contributing to deforestation. Both CAM candidates outperformed the C4 bioenergy crop, Panicum virgatum L. (switchgrass) in arid zones in the latitudinal range 30°S–30°N.

  • A highly recombined, high‐density, eight‐founder wheat MAGIC map reveals extensive segregation distortion and genomic locations of introgression segments

    分类: 生物学 >> 植物学 >> 植物细胞学与植物遗传学、植物形态学 提交时间: 2016-05-04

    摘要: Multiparent Advanced Generation Intercross (MAGIC) mapping populations offer unique opportunities and challenges for marker and QTL mapping in crop species. We have constructed the first eight-parent MAGIC genetic map for wheat, comprising 18 601 SNP markers. We validated the accuracy of our map against the wheat genome sequence and found an improvement in accuracy compared to published genetic maps. Our map shows a notable increase in precision resulting from the three generations of intercrossing required to create the population. This is most pronounced in the pericentromeric regions of the chromosomes. Sixteen percent of mapped markers exhibited segregation distortion (SD) with many occurring in long (>20 cM) blocks. Some of the longest and most distorted blocks were collinear with noncentromeric high-marker-density regions of the genome, suggesting they were candidates for introgression fragments introduced into the bread wheat gene pool from other grass species. We investigated two of these linkage blocks in detail and found strong evidence that one on chromosome 4AL, showing SD against the founder Robigus, is an interspecific introgression fragment. The completed map is available from http://www.niab.com/pages/id/326/Resources.

  • Rare $B$ decays using lattice QCD form factors

    分类: 物理学 >> 核物理学 提交时间: 2016-09-13

    摘要: In this write-up we review and update our recent lattice QCD calculation of B→K∗, Bs→ϕ, and Bs→K∗form factors [arXiv:1310.3722]. These unquenched calculations, performed in the low-recoil kinematic regime, provide a significant improvement over the use of extrapolated light cone sum rule results. The fits presented here include further kinematic constraints and estimates of additional correlations between the different form factor shape parameters. We use these form factors along with Standard Model determinations of Wilson coefficients to give Standard Model predictions for several observables [arXiv:1310.3887]. The modest improvements to the form factor fits lead to improved determinations of FL, the fraction of longitudinally polarized vector mesons, but have little effect on most other observables.

  • Deep Learning, Feature Learning, and Clustering Analysis for SEM Image Classification

    分类: 计算机科学 >> 计算机科学的集成理论 提交时间: 2022-11-18 合作期刊: 《数据智能(英文)》

    摘要: In this paper, we report upon our recent work aimed at improving and adapting machine learning algorithms to automatically classify nanoscience images acquired by the Scanning Electron Microscope (SEM). This is done by coupling supervised and unsupervised learning approaches. We first investigate supervised learning on a ten-category data set of images and compare the performance of the different models in terms of training accuracy. Then, we reduce the dimensionality of the features through autoencoders to perform unsupervised learning on a subset of images in a selected range of scales (from 1 μm to 2 μm). Finally, we compare different clustering methods to uncover intrinsic structures in the images.