为了解珠江流域黄颡鱼不同群体的遗传分化,以黄颡鱼为材料,通过形态度量学和分子生物学的方法对其进行研究。形态度量学的主成分分析(PCA)的散点图显示都柳江群体与漓江群体聚集于一处,东江群体与都柳江、漓江群体分开,表明东江群体与...为了解珠江流域黄颡鱼不同群体的遗传分化,以黄颡鱼为材料,通过形态度量学和分子生物学的方法对其进行研究。形态度量学的主成分分析(PCA)的散点图显示都柳江群体与漓江群体聚集于一处,东江群体与都柳江、漓江群体分开,表明东江群体与其它两个群体形态上有分化,漓江群体与都柳江群体形态间分化较小。D-loop序列分析最终检测到176个变异位点,单倍型36个,3个群体的平均碱基组成差异很小,且A+T含量(59.6%)高于G+C含量(40.4%),3个群体平均Nm=3.234,表明群体间存在较大基因流,单倍型NJ树显示漓江群体与都柳江群体聚为一支,东江群体聚为一支。3个群体21个微卫星标记位点的分析结果显示:3个群体有15个位点属于高度多态位点(PIC>0.5),3个群体基于Nei's遗传距离构建的UAPGM聚类结果与mt DNA D-loop聚类结果一致,与地理分布呈一定相关性。综合形态度量学与分子生物学标记结果可以看出,黄颡鱼3个群体存在一定形态差异,3个黄颡鱼野生群体遗传多样性水平较高。展开更多
For a long time,the requirement model is difficult to measure. This paper introduces the de-veloping status of requirement analysis modeling and metrics,brings forward the point of turning the objective of metric to U...For a long time,the requirement model is difficult to measure. This paper introduces the de-veloping status of requirement analysis modeling and metrics,brings forward the point of turning the objective of metric to UML,after pressenting the requirement modeling methods of using UML,puts forward the metrics of ours.展开更多
The next generation of synchrotron radiation light sources features extremely low emittance,enabling the generation of synchrotron radiation with significantly higher brilliance,which facilitates the exploration of ma...The next generation of synchrotron radiation light sources features extremely low emittance,enabling the generation of synchrotron radiation with significantly higher brilliance,which facilitates the exploration of matter at smaller scales.However,the extremely low emittance results in stronger sextupole magnet strengths,leading to high natural chromaticity.This necessitates the use of sextupole magnets to correct the natural chromaticity.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a lattice was designed for the storage ring that can achieve an ultra-low natural emittance of 72.2 pm·rad at the beam energy of 3.5 GeV.However,the significant detuning effects,driven by high second-order resonant driving terms due to strong sextupoles,will degrade the performance of the facility.To resolve this issue,installation of octupoles in the SSRF-U storage ring has been planned.This paper presents the study results on configuration selection and optimization method for the octupoles.An optimal solution for the SSRF-U storage ring was obtained to effectively mitigate the amplitude-dependent tune shift and the second-order chromaticity,consequently leading to an increased dynamic aperture(DA),momentum acceptance(MA),and reduced sensitivity to magnetic field errors.展开更多
文摘为了解珠江流域黄颡鱼不同群体的遗传分化,以黄颡鱼为材料,通过形态度量学和分子生物学的方法对其进行研究。形态度量学的主成分分析(PCA)的散点图显示都柳江群体与漓江群体聚集于一处,东江群体与都柳江、漓江群体分开,表明东江群体与其它两个群体形态上有分化,漓江群体与都柳江群体形态间分化较小。D-loop序列分析最终检测到176个变异位点,单倍型36个,3个群体的平均碱基组成差异很小,且A+T含量(59.6%)高于G+C含量(40.4%),3个群体平均Nm=3.234,表明群体间存在较大基因流,单倍型NJ树显示漓江群体与都柳江群体聚为一支,东江群体聚为一支。3个群体21个微卫星标记位点的分析结果显示:3个群体有15个位点属于高度多态位点(PIC>0.5),3个群体基于Nei's遗传距离构建的UAPGM聚类结果与mt DNA D-loop聚类结果一致,与地理分布呈一定相关性。综合形态度量学与分子生物学标记结果可以看出,黄颡鱼3个群体存在一定形态差异,3个黄颡鱼野生群体遗传多样性水平较高。
文摘For a long time,the requirement model is difficult to measure. This paper introduces the de-veloping status of requirement analysis modeling and metrics,brings forward the point of turning the objective of metric to UML,after pressenting the requirement modeling methods of using UML,puts forward the metrics of ours.
文摘The next generation of synchrotron radiation light sources features extremely low emittance,enabling the generation of synchrotron radiation with significantly higher brilliance,which facilitates the exploration of matter at smaller scales.However,the extremely low emittance results in stronger sextupole magnet strengths,leading to high natural chromaticity.This necessitates the use of sextupole magnets to correct the natural chromaticity.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a lattice was designed for the storage ring that can achieve an ultra-low natural emittance of 72.2 pm·rad at the beam energy of 3.5 GeV.However,the significant detuning effects,driven by high second-order resonant driving terms due to strong sextupoles,will degrade the performance of the facility.To resolve this issue,installation of octupoles in the SSRF-U storage ring has been planned.This paper presents the study results on configuration selection and optimization method for the octupoles.An optimal solution for the SSRF-U storage ring was obtained to effectively mitigate the amplitude-dependent tune shift and the second-order chromaticity,consequently leading to an increased dynamic aperture(DA),momentum acceptance(MA),and reduced sensitivity to magnetic field errors.
