针对AOMedia Video 1(AV1)编码时间较长的问题,基于不同纹理的视频内容与分区模式之间的联系,引入了虚拟子块的跨块梯度差来衡量图像纹理分布的差异,提出了一种快速块划分决策算法,以跳过非必要的分区模式。利用分区终止块大小与性能损...针对AOMedia Video 1(AV1)编码时间较长的问题,基于不同纹理的视频内容与分区模式之间的联系,引入了虚拟子块的跨块梯度差来衡量图像纹理分布的差异,提出了一种快速块划分决策算法,以跳过非必要的分区模式。利用分区终止块大小与性能损失之间的联系,根据当前块大小自适应调整快速块划分的判断阈值,使得较小的编码块具有较宽松的跳过条件。与libaom相比,该算法在全帧内(All-Intra,AI)配置下平均可节省16.15%的编码时间,同时性能损失较小,有望被用于减少高分辨率视频的编码时间。展开更多
开放媒体联盟开发的第一代视频编码标准(Alliance for Open Media Video 1,AV1)作为新一代的开放式视频编码技术,以其高压缩效率和高质量视频输出等优势成为在线视频领域的主流编解码标准之一。旨在优化帧内预测编码技术以降低编码运行...开放媒体联盟开发的第一代视频编码标准(Alliance for Open Media Video 1,AV1)作为新一代的开放式视频编码技术,以其高压缩效率和高质量视频输出等优势成为在线视频领域的主流编解码标准之一。旨在优化帧内预测编码技术以降低编码运行的计算复杂度,从而节约视频编码时间。为此,提出了长边采样(Long-side Sampling, LS)和长边稀疏采样(Long-side Sparse Sampling, LSS)的参考像素选择方法,根据块的划分方式规律地提取关键参考像素,以改进直流(Direct Current, DC)预测和亮度预测色度(Chroma from Luma, CfL)预测技术的性能。实验结果表明,LSS可以规避运算中的除法操作且减少大量加法计算量,在全I帧(All Intra, AI)和随机接入(Random Access, RA)配置下,相较原始算法平均编码时间减少11%和13%,同时节省0.03%和0.04%的Bj?ntegaard Delta Bit Rate(BDBR)。展开更多
Under a suitable condition of crystallization, dark brown short rhombohedron crystals could be obtained from FeMoco-deficient MoFe protein (DeltanifE Avl) purified from a nifE deleted mutant DJ35 of Azotobacter vinela...Under a suitable condition of crystallization, dark brown short rhombohedron crystals could be obtained from FeMoco-deficient MoFe protein (DeltanifE Avl) purified from a nifE deleted mutant DJ35 of Azotobacter vinelandii Lipmann grown in NH3-limited medium. The number, size and quality of crystals were significantly affected by either the concentration of precipitants and buffer or diffusion method. The longest sides of the largest crystal of DeltanifE Avl protein, which was obtained by vapor diffusion in the hanging drop method, were 0.12 and 0.13 mm, respectively.展开更多
Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has b...Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has been widely investigated in the Chinese herbal medicine field.However,little is known at this point about the biological roles of artemisinic acid in regulating the behavioral trends of A.lucorum.In this study,we collected volatiles from A.annua at the seedling stage by using headspace solid phase microextraction(HS-SPME).Gas chromatography-mass spectrometry(GC-MS) analysis showed that approximately 11.03±6.00 and 238.25±121.67 ng hartemisinic acid were detected in volatile samples and milled samples,respectively.Subsequently,a key gene for artemisinic acid synthesis,the cytochrome P450 gene cyp71 av1,was expressed in engineered Saccharomyces cerevisiae to catalyze the production of artemisinic acid.After the addition of exogenous artemisinic alcohol or artemisinic aldehyde,artemisinic acid was identified as the product of the expressed gene.In electroantennogram(EAG) recordings,3-day-old adult A.lucorum showed significant electrophysiological responses to artemisinic alcohol,artemisinic aldehyde and artemisinic acid.Furthermore,3-day-old female bugs were significantly attracted by artemisinic acid and artemisinic alcohol at a concentration of 10 mmol L,whereas 3-day-old male bugs were attracted significantly by 10 mmol Lartemisinic acid and artemisinic aldehyde.We propose that artemisinic acid and its precursors could be used as potential attractant components for the design of novel integrated pest management strategies to control A.lucorum.展开更多
文摘针对AOMedia Video 1(AV1)编码时间较长的问题,基于不同纹理的视频内容与分区模式之间的联系,引入了虚拟子块的跨块梯度差来衡量图像纹理分布的差异,提出了一种快速块划分决策算法,以跳过非必要的分区模式。利用分区终止块大小与性能损失之间的联系,根据当前块大小自适应调整快速块划分的判断阈值,使得较小的编码块具有较宽松的跳过条件。与libaom相比,该算法在全帧内(All-Intra,AI)配置下平均可节省16.15%的编码时间,同时性能损失较小,有望被用于减少高分辨率视频的编码时间。
文摘开放媒体联盟开发的第一代视频编码标准(Alliance for Open Media Video 1,AV1)作为新一代的开放式视频编码技术,以其高压缩效率和高质量视频输出等优势成为在线视频领域的主流编解码标准之一。旨在优化帧内预测编码技术以降低编码运行的计算复杂度,从而节约视频编码时间。为此,提出了长边采样(Long-side Sampling, LS)和长边稀疏采样(Long-side Sparse Sampling, LSS)的参考像素选择方法,根据块的划分方式规律地提取关键参考像素,以改进直流(Direct Current, DC)预测和亮度预测色度(Chroma from Luma, CfL)预测技术的性能。实验结果表明,LSS可以规避运算中的除法操作且减少大量加法计算量,在全I帧(All Intra, AI)和随机接入(Random Access, RA)配置下,相较原始算法平均编码时间减少11%和13%,同时节省0.03%和0.04%的Bj?ntegaard Delta Bit Rate(BDBR)。
文摘Under a suitable condition of crystallization, dark brown short rhombohedron crystals could be obtained from FeMoco-deficient MoFe protein (DeltanifE Avl) purified from a nifE deleted mutant DJ35 of Azotobacter vinelandii Lipmann grown in NH3-limited medium. The number, size and quality of crystals were significantly affected by either the concentration of precipitants and buffer or diffusion method. The longest sides of the largest crystal of DeltanifE Avl protein, which was obtained by vapor diffusion in the hanging drop method, were 0.12 and 0.13 mm, respectively.
基金supported by the National Natural Science Foundation of China (31772176 and 31972338)the National Key Research and Development Program of China (2019YFD0300100)
文摘Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has been widely investigated in the Chinese herbal medicine field.However,little is known at this point about the biological roles of artemisinic acid in regulating the behavioral trends of A.lucorum.In this study,we collected volatiles from A.annua at the seedling stage by using headspace solid phase microextraction(HS-SPME).Gas chromatography-mass spectrometry(GC-MS) analysis showed that approximately 11.03±6.00 and 238.25±121.67 ng hartemisinic acid were detected in volatile samples and milled samples,respectively.Subsequently,a key gene for artemisinic acid synthesis,the cytochrome P450 gene cyp71 av1,was expressed in engineered Saccharomyces cerevisiae to catalyze the production of artemisinic acid.After the addition of exogenous artemisinic alcohol or artemisinic aldehyde,artemisinic acid was identified as the product of the expressed gene.In electroantennogram(EAG) recordings,3-day-old adult A.lucorum showed significant electrophysiological responses to artemisinic alcohol,artemisinic aldehyde and artemisinic acid.Furthermore,3-day-old female bugs were significantly attracted by artemisinic acid and artemisinic alcohol at a concentration of 10 mmol L,whereas 3-day-old male bugs were attracted significantly by 10 mmol Lartemisinic acid and artemisinic aldehyde.We propose that artemisinic acid and its precursors could be used as potential attractant components for the design of novel integrated pest management strategies to control A.lucorum.
