链接预测是网络分析的一项重要任务,它研究个体之间的相互作用,并推断在未来不断发展的网络中可能出现的新关系;然而,在链接预测过程中可能存在偏见,特别是当涉及包含某些敏感属性的个体之间的链接时,如引发“过滤气泡”的效应,这一效...链接预测是网络分析的一项重要任务,它研究个体之间的相互作用,并推断在未来不断发展的网络中可能出现的新关系;然而,在链接预测过程中可能存在偏见,特别是当涉及包含某些敏感属性的个体之间的链接时,如引发“过滤气泡”的效应,这一效应表现为在线用户公开信息的隔离程度加剧、多样性降低。针对上述问题,从算法公平性的角度缓解“过滤气泡”问题,将预处理阶段的方法和处理阶段的方法相结合,进而提出ALFLP(Adding Link and Adversarial Learning for Fair Link Prediction)方法。在预处理阶段,通过向劣势链接群组添加链接,减小不同群组的链接密度差异;在处理阶段,将预处理阶段的输出输入至基于对抗学习的方法,并通过生成器与鉴别器相互博弈,促进更多组间链接,缓解“过滤气泡”问题。在真实数据集pokec_n和pokec_z上的实验结果表明,与基线方法(如Jaccard)相比,ALFLP方法的AUC指标分别提高了约12和10个百分点,而modred指标分别提高了约0.14和0.10。可见,ALFLP方法能在公平性和预测准确性之间实现较好的权衡。展开更多
利用42个优质小麦(Triticum aestivum)品种籽粒发芽指数对6个小麦穗发芽抗性相关基因[Tamyb10、TaDFR(Dihydroflavone reductase)、TaVp-1(Viviparous‑1)、TaSdr(Seed dormancy)、TaPM19-A1(Plasma membrane 19‑A1)、TaMFT(Mother of FT...利用42个优质小麦(Triticum aestivum)品种籽粒发芽指数对6个小麦穗发芽抗性相关基因[Tamyb10、TaDFR(Dihydroflavone reductase)、TaVp-1(Viviparous‑1)、TaSdr(Seed dormancy)、TaPM19-A1(Plasma membrane 19‑A1)、TaMFT(Mother of FT and TFL1)]的分子标记的有效性进行验证,以期为抗穗发芽优质小麦品种的筛选及选育奠定基础。结果表明,小麦穗发芽抗性相关基因Tamyb10、TaDFR、TaVp-1、TaSdr、TaPM19-A1、TaMFT在42个优质小麦品种中均检测到2种等位变异,优异等位基因所占比例存在明显差异,介于4.8%~78.6%,未发现TaVp-1的TaVp-1 Bb基因型。等位基因类型与籽粒发芽指数相关性分析表明,标记myb10D、MFT-3A和MFT-A2与优质小麦穗发芽抗性极显著相关,而标记DFR-B、Vp1B3、Sdr2A、Sdr2B和PM19-A1与优质小麦穗发芽抗性相关性不显著。STS标记myb10D可用于红粒优质小麦的穗发芽抗性筛选,CAPS标记MFT-3A和STS标记MFT-A2可用于白粒优质小麦的穗发芽抗性筛选,TaMFT可能在优质小麦抗穗发芽机制中发挥着重要作用。展开更多
Imaging blood vessels is of importance for determining the vascular distribution of organs and tumors.Phase-contrast X-ray imaging can reveal the vessels in much more detail than conventional X-ray absorption method.V...Imaging blood vessels is of importance for determining the vascular distribution of organs and tumors.Phase-contrast X-ray imaging can reveal the vessels in much more detail than conventional X-ray absorption method.Visualizing murine liver microvasculature ex vivo with phase-contrast X-ray imaging was performed at Shanghai Synchrotron Radiation Facility.Barium sulfate and physiological saline were used as contrast agents for the blood vessels.Blood vessels of <Φ20μm could be detected by replacing resident blood with physiological saline or barium sulfate.An entire branch of the portal vein (from the main axial portal vein to the ninth generation of branching) could be captured in a single phase-contrast image.It is demonstrated that selective angiography based on phase contrast X-ray imaging,with a physiological material of low Z elements (such as saline) being the contrast agent,is a viable imaging strategy.Further efforts will be focused on using the technique to image tumor angiogenesis.展开更多
文摘链接预测是网络分析的一项重要任务,它研究个体之间的相互作用,并推断在未来不断发展的网络中可能出现的新关系;然而,在链接预测过程中可能存在偏见,特别是当涉及包含某些敏感属性的个体之间的链接时,如引发“过滤气泡”的效应,这一效应表现为在线用户公开信息的隔离程度加剧、多样性降低。针对上述问题,从算法公平性的角度缓解“过滤气泡”问题,将预处理阶段的方法和处理阶段的方法相结合,进而提出ALFLP(Adding Link and Adversarial Learning for Fair Link Prediction)方法。在预处理阶段,通过向劣势链接群组添加链接,减小不同群组的链接密度差异;在处理阶段,将预处理阶段的输出输入至基于对抗学习的方法,并通过生成器与鉴别器相互博弈,促进更多组间链接,缓解“过滤气泡”问题。在真实数据集pokec_n和pokec_z上的实验结果表明,与基线方法(如Jaccard)相比,ALFLP方法的AUC指标分别提高了约12和10个百分点,而modred指标分别提高了约0.14和0.10。可见,ALFLP方法能在公平性和预测准确性之间实现较好的权衡。
文摘利用42个优质小麦(Triticum aestivum)品种籽粒发芽指数对6个小麦穗发芽抗性相关基因[Tamyb10、TaDFR(Dihydroflavone reductase)、TaVp-1(Viviparous‑1)、TaSdr(Seed dormancy)、TaPM19-A1(Plasma membrane 19‑A1)、TaMFT(Mother of FT and TFL1)]的分子标记的有效性进行验证,以期为抗穗发芽优质小麦品种的筛选及选育奠定基础。结果表明,小麦穗发芽抗性相关基因Tamyb10、TaDFR、TaVp-1、TaSdr、TaPM19-A1、TaMFT在42个优质小麦品种中均检测到2种等位变异,优异等位基因所占比例存在明显差异,介于4.8%~78.6%,未发现TaVp-1的TaVp-1 Bb基因型。等位基因类型与籽粒发芽指数相关性分析表明,标记myb10D、MFT-3A和MFT-A2与优质小麦穗发芽抗性极显著相关,而标记DFR-B、Vp1B3、Sdr2A、Sdr2B和PM19-A1与优质小麦穗发芽抗性相关性不显著。STS标记myb10D可用于红粒优质小麦的穗发芽抗性筛选,CAPS标记MFT-3A和STS标记MFT-A2可用于白粒优质小麦的穗发芽抗性筛选,TaMFT可能在优质小麦抗穗发芽机制中发挥着重要作用。
基金Supported by National Basic Research Program of China (973 Program Grant No.2010CB834305)
文摘Imaging blood vessels is of importance for determining the vascular distribution of organs and tumors.Phase-contrast X-ray imaging can reveal the vessels in much more detail than conventional X-ray absorption method.Visualizing murine liver microvasculature ex vivo with phase-contrast X-ray imaging was performed at Shanghai Synchrotron Radiation Facility.Barium sulfate and physiological saline were used as contrast agents for the blood vessels.Blood vessels of <Φ20μm could be detected by replacing resident blood with physiological saline or barium sulfate.An entire branch of the portal vein (from the main axial portal vein to the ninth generation of branching) could be captured in a single phase-contrast image.It is demonstrated that selective angiography based on phase contrast X-ray imaging,with a physiological material of low Z elements (such as saline) being the contrast agent,is a viable imaging strategy.Further efforts will be focused on using the technique to image tumor angiogenesis.
