[Objective] The aim of this study was to produce Streptomyces avermitilis strain with site-directed mutagenesis in aveD gene,and so as to provide theoretical basis for genetic breeding of S.avermitilis.[Method] PCR-dr...[Objective] The aim of this study was to produce Streptomyces avermitilis strain with site-directed mutagenesis in aveD gene,and so as to provide theoretical basis for genetic breeding of S.avermitilis.[Method] PCR-driven overlap extension was conducted for the site-directed mutagenesis in aveD gene;the mutated aveD gene then was used to construct vector pDC3（pKC1139∷aveD） via molecular manipulations like in vitro enzyme digestion and ligation;the vector pDC3（pKC1139∷aveD） was then introduced to aveD deletion mutant 489 of avermectin-producing strain S.avermitilis 76-9.[Result] Mutant strain 536 of site-directed mutagenesis of S.avermitilis 76-9 was obtained by homologous recombination.The sequencing results show that the sixty-ninth base C in aveD-coding region of mutant 536 was substituted by T,and the corresponding amino acid Thr was mutated to be Ile.[Conclusion] This study laid basis for the development of strains specifically producing avermectin B.展开更多
The sie index lists of the artificia l Laix gmelini and Pinus sykrestris var.mongolica forests in Daxing'an Mountainsregion weie analyzed by the principle of the two-point me thod.The standa rdzed growth model of ...The sie index lists of the artificia l Laix gmelini and Pinus sykrestris var.mongolica forests in Daxing'an Mountainsregion weie analyzed by the principle of the two-point me thod.The standa rdzed growth model of the artificial needle-lea vedforest was set up.According to the model,the ea ch growth-index class and theore tical values ofe ach age-class were calculated,and the standardized sie index list was constiute d.The test of the theore tical values showe d that the standardized site indexlit meet the de ma nd of precision.This study resolved the conversions of site indexes between the same species in diffe rentsite type s and the different spe cies in diffe re nt ste types for nee dle-leave d forests in Da xing'an Moun tains region.展开更多
为解决第三代音视频编码标准(audio video coding standard 3,AVS3)帧内预测的耗时问题,提出一种基于最小编码单元(coding unit,CU)代价的帧内预测并行算法。首先,将图像划分为最小CU。然后,利用原始像素作为参考,并行计算所有最小CU的...为解决第三代音视频编码标准(audio video coding standard 3,AVS3)帧内预测的耗时问题,提出一种基于最小编码单元(coding unit,CU)代价的帧内预测并行算法。首先,将图像划分为最小CU。然后,利用原始像素作为参考,并行计算所有最小CU的帧内模式代价。最后,用代价组合的方式快速计算出其他CU的帧内模式优先级,选择最优的15个模式进入粗略模式决策(rough mode decision,RMD)阶段。此外,为减少方法引入的误差,提出了3种优化策略。在预测前对原始像素进行预处理,使其更贴合重构像素;修改帧内预测的代价函数,以更准确地估计每种模式的优先级;大尺寸CU使用顶层的CU代价作为参考,减少CU组合累积的误差。实验结果表明,在码率仅下降0.35%的情况下,整体编码的计算时间减少了27%,有效地减少了帧内预测的耗时并保证了编码质量。展开更多
针对提高4K超高清电视广播视频压缩效率,减少存储空间和网络带宽这一需求,提出应用音视频编码标准3(Audio Video Coding Standard 3,AVS3)视频编解码技术,利用AVS3编解码标准的高效性,提升4K超高清视频内容的编码质量和传输效率。首先,...针对提高4K超高清电视广播视频压缩效率,减少存储空间和网络带宽这一需求,提出应用音视频编码标准3(Audio Video Coding Standard 3,AVS3)视频编解码技术,利用AVS3编解码标准的高效性,提升4K超高清视频内容的编码质量和传输效率。首先,从节目制播环节入手,通过扩展帧内角度预测和信源动态编码,在保持图像质量的同时降低编码比特率,优化编码过程,节省传输带宽;其次,通过视频分层并行解码和音频解码还放声音技术,提升接收解码及呈现的速度和质量;最后,通过应用实验验证AVS3视频编解码技术在4K超高清电视广播领域的实际效果。展开更多
The BRASH syndrome,an acronym for bradycardia,renal failure,atrioventricular(AV)nodal blockade,shock,and hyperkalemia,was first described as a distinct clinical entity in 2016 by Josh Farkas.[1]He proposed a vicious p...The BRASH syndrome,an acronym for bradycardia,renal failure,atrioventricular(AV)nodal blockade,shock,and hyperkalemia,was first described as a distinct clinical entity in 2016 by Josh Farkas.[1]He proposed a vicious pathophysiological cycle driven by the synergy between AV nodal blockade and hyperkalemia.展开更多
BACKGROUND:BRASH syndrome(Bradycardia,Renal failure,AV nodal blockade,Shock,and Hyperkalemia)is a recently described clinical entity characterized by synergistic interaction between AV nodal blocking medications and h...BACKGROUND:BRASH syndrome(Bradycardia,Renal failure,AV nodal blockade,Shock,and Hyperkalemia)is a recently described clinical entity characterized by synergistic interaction between AV nodal blocking medications and hyperkalemia.Despite increasing recognition,its clinical characteristics,risk factors,and outcomes remain poorly defined.The rationale of this review is to provide clinicians an upto-date overview of the most commonly encountered risk factors,triggers,clinical pictures,usual lab values,complications and outcomes,via the systemic analysis of currently published cases.METHODS:A systematic review was conducted using MEDLINE,Web of Science,and Cochrane Library databases through December 2024.Case reports,case series,and conference abstracts involving adult patients with BRASH syndrome were included.Data extraction focused on demographics,clinical presentations,laboratory findings,management strategies,and outcomes.RESULTS:Analysis included 131 patients from 111 published cases.Mean age was(71±13)years,with female predominance(58.1%).Hypertension(77.0%),chronic kidney disease(48.4%),and diabetes mellitus(46.7%)were the most common comorbidities.Beta-blockers were the predominant medication(76.5%).Most common presenting symptoms were syncope(17.9%),generalized weakness(16.2%),and altered mental status(11.9%).Mean potassium level was 6.6 mEq/L,with more than half of cases presenting with non-severe hyperkalemia(<6.5 mEq/L).Management often required multimodal therapy,with 50.8% of patients requiring vasopressors and 31.6% requiring hemodialysis.CONCLUSION:This systematic review provides the most comprehensive analysis of BRASH syndrome to date,demonstrating that while potentially serious,outcomes are generally favorable with appropriate recognition and management.The syndrome can develop even with modest hyperkalemia,particularly in elderly patients with multiple comorbidities.Early recognition and systematic management addressing all components of the syndrome appear crucial for optimal outcomes.展开更多
在音视频传输领域,AV over IP系统通过网络传送高质量的音视频内容,已成为现代传输技术的一种重要形式。随着AV over IP技术的长足发展,基带和网际互连协议(Internet Protocol,IP)融合成为现阶段广电行业制作与播出的典型应用模式。该...在音视频传输领域,AV over IP系统通过网络传送高质量的音视频内容,已成为现代传输技术的一种重要形式。随着AV over IP技术的长足发展,基带和网际互连协议(Internet Protocol,IP)融合成为现阶段广电行业制作与播出的典型应用模式。该模式考虑了不同的级联方案,既能够应对复杂的现场环境,又减少了系统传输节点,降低了信号传输时延。基于此,分析混合架构在AV over IP系统中提升传输效率的策略,并通过实验评估其性能,旨在提供一种有效的技术路线,以应对日益增长的数据传输需求。展开更多
SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56...SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56)Ni model to fit the multiband light curves(LCs)of SN 2014av.For the CSI and CSI plus^(56)Ni models,we assume that the CSM is a constant density shell(“shell”)or a steady-state stellar wind(“wind”)with density∝r-2.We find that both the^(56)Ni and CSI models fail to fit the multiband LCs of SN 2014av,while the CSI plus^(56)Ni model can account for the LCs.In the last scenario,the LCs around the peaks were mainly powered by the CSI,while the flattening of the LCs was mainly powered by the radioactive decay of^(56)Ni.For the wind case,the derived mass-loss rate of the progenitor is≈20.5-205.5 M_(⊙)yr^(-1),whose lower limit is significantly larger than the upper limit of normal stellar winds,and comparable the upper limit of hyper-winds.Hence,we suggest that the wind case is disfavored.For the shell case,the best-fitting values of the ejecta,^(56)Ni,and the CSM are2.29 M_(⊙),0.09 M_(⊙),and 5.00 M_(⊙),respectively.Provided the velocity of the CSM shell is 100-1000 km s^(-1),we infer that the shell might be expelled≈0.49-5.20 yr before the SN exploded.展开更多
基金Supported by Special Fund for Doctors in Universities in Hebei Province(B2003201)~~
文摘[Objective] The aim of this study was to produce Streptomyces avermitilis strain with site-directed mutagenesis in aveD gene,and so as to provide theoretical basis for genetic breeding of S.avermitilis.[Method] PCR-driven overlap extension was conducted for the site-directed mutagenesis in aveD gene;the mutated aveD gene then was used to construct vector pDC3（pKC1139∷aveD） via molecular manipulations like in vitro enzyme digestion and ligation;the vector pDC3（pKC1139∷aveD） was then introduced to aveD deletion mutant 489 of avermectin-producing strain S.avermitilis 76-9.[Result] Mutant strain 536 of site-directed mutagenesis of S.avermitilis 76-9 was obtained by homologous recombination.The sequencing results show that the sixty-ninth base C in aveD-coding region of mutant 536 was substituted by T,and the corresponding amino acid Thr was mutated to be Ile.[Conclusion] This study laid basis for the development of strains specifically producing avermectin B.
文摘The sie index lists of the artificia l Laix gmelini and Pinus sykrestris var.mongolica forests in Daxing'an Mountainsregion weie analyzed by the principle of the two-point me thod.The standa rdzed growth model of the artificial needle-lea vedforest was set up.According to the model,the ea ch growth-index class and theore tical values ofe ach age-class were calculated,and the standardized sie index list was constiute d.The test of the theore tical values showe d that the standardized site indexlit meet the de ma nd of precision.This study resolved the conversions of site indexes between the same species in diffe rentsite type s and the different spe cies in diffe re nt ste types for nee dle-leave d forests in Da xing'an Moun tains region.
文摘为解决第三代音视频编码标准(audio video coding standard 3,AVS3)帧内预测的耗时问题,提出一种基于最小编码单元(coding unit,CU)代价的帧内预测并行算法。首先,将图像划分为最小CU。然后,利用原始像素作为参考,并行计算所有最小CU的帧内模式代价。最后,用代价组合的方式快速计算出其他CU的帧内模式优先级,选择最优的15个模式进入粗略模式决策(rough mode decision,RMD)阶段。此外,为减少方法引入的误差,提出了3种优化策略。在预测前对原始像素进行预处理,使其更贴合重构像素;修改帧内预测的代价函数,以更准确地估计每种模式的优先级;大尺寸CU使用顶层的CU代价作为参考,减少CU组合累积的误差。实验结果表明,在码率仅下降0.35%的情况下,整体编码的计算时间减少了27%,有效地减少了帧内预测的耗时并保证了编码质量。
文摘针对提高4K超高清电视广播视频压缩效率,减少存储空间和网络带宽这一需求,提出应用音视频编码标准3(Audio Video Coding Standard 3,AVS3)视频编解码技术,利用AVS3编解码标准的高效性,提升4K超高清视频内容的编码质量和传输效率。首先,从节目制播环节入手,通过扩展帧内角度预测和信源动态编码,在保持图像质量的同时降低编码比特率,优化编码过程,节省传输带宽;其次,通过视频分层并行解码和音频解码还放声音技术,提升接收解码及呈现的速度和质量;最后,通过应用实验验证AVS3视频编解码技术在4K超高清电视广播领域的实际效果。
文摘The BRASH syndrome,an acronym for bradycardia,renal failure,atrioventricular(AV)nodal blockade,shock,and hyperkalemia,was first described as a distinct clinical entity in 2016 by Josh Farkas.[1]He proposed a vicious pathophysiological cycle driven by the synergy between AV nodal blockade and hyperkalemia.
文摘BACKGROUND:BRASH syndrome(Bradycardia,Renal failure,AV nodal blockade,Shock,and Hyperkalemia)is a recently described clinical entity characterized by synergistic interaction between AV nodal blocking medications and hyperkalemia.Despite increasing recognition,its clinical characteristics,risk factors,and outcomes remain poorly defined.The rationale of this review is to provide clinicians an upto-date overview of the most commonly encountered risk factors,triggers,clinical pictures,usual lab values,complications and outcomes,via the systemic analysis of currently published cases.METHODS:A systematic review was conducted using MEDLINE,Web of Science,and Cochrane Library databases through December 2024.Case reports,case series,and conference abstracts involving adult patients with BRASH syndrome were included.Data extraction focused on demographics,clinical presentations,laboratory findings,management strategies,and outcomes.RESULTS:Analysis included 131 patients from 111 published cases.Mean age was(71±13)years,with female predominance(58.1%).Hypertension(77.0%),chronic kidney disease(48.4%),and diabetes mellitus(46.7%)were the most common comorbidities.Beta-blockers were the predominant medication(76.5%).Most common presenting symptoms were syncope(17.9%),generalized weakness(16.2%),and altered mental status(11.9%).Mean potassium level was 6.6 mEq/L,with more than half of cases presenting with non-severe hyperkalemia(<6.5 mEq/L).Management often required multimodal therapy,with 50.8% of patients requiring vasopressors and 31.6% requiring hemodialysis.CONCLUSION:This systematic review provides the most comprehensive analysis of BRASH syndrome to date,demonstrating that while potentially serious,outcomes are generally favorable with appropriate recognition and management.The syndrome can develop even with modest hyperkalemia,particularly in elderly patients with multiple comorbidities.Early recognition and systematic management addressing all components of the syndrome appear crucial for optimal outcomes.
文摘在音视频传输领域,AV over IP系统通过网络传送高质量的音视频内容,已成为现代传输技术的一种重要形式。随着AV over IP技术的长足发展,基带和网际互连协议(Internet Protocol,IP)融合成为现阶段广电行业制作与播出的典型应用模式。该模式考虑了不同的级联方案,既能够应对复杂的现场环境,又减少了系统传输节点,降低了信号传输时延。基于此,分析混合架构在AV over IP系统中提升传输效率的策略,并通过实验评估其性能,旨在提供一种有效的技术路线,以应对日益增长的数据传输需求。
基金supported by the National Key R&D Program(2024YFA1611700)the National Natural Science Foundation of China(grant Nos.12133003,12494571 and 11963001)supported by the Guangxi Talent Program(“Highland of Innovation Talents”)and Program of Bagui Scholars(LHJ)。
文摘SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56)Ni model to fit the multiband light curves(LCs)of SN 2014av.For the CSI and CSI plus^(56)Ni models,we assume that the CSM is a constant density shell(“shell”)or a steady-state stellar wind(“wind”)with density∝r-2.We find that both the^(56)Ni and CSI models fail to fit the multiband LCs of SN 2014av,while the CSI plus^(56)Ni model can account for the LCs.In the last scenario,the LCs around the peaks were mainly powered by the CSI,while the flattening of the LCs was mainly powered by the radioactive decay of^(56)Ni.For the wind case,the derived mass-loss rate of the progenitor is≈20.5-205.5 M_(⊙)yr^(-1),whose lower limit is significantly larger than the upper limit of normal stellar winds,and comparable the upper limit of hyper-winds.Hence,we suggest that the wind case is disfavored.For the shell case,the best-fitting values of the ejecta,^(56)Ni,and the CSM are2.29 M_(⊙),0.09 M_(⊙),and 5.00 M_(⊙),respectively.Provided the velocity of the CSM shell is 100-1000 km s^(-1),we infer that the shell might be expelled≈0.49-5.20 yr before the SN exploded.
