2022年3月31日—4月2日,云南省出现历史同期罕见的寒潮天气过程.通过地面观测资料、高空观测资料和NCEP FNL资料,对此次寒潮过程的成因进行分析,并对欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)...2022年3月31日—4月2日,云南省出现历史同期罕见的寒潮天气过程.通过地面观测资料、高空观测资料和NCEP FNL资料,对此次寒潮过程的成因进行分析,并对欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)模式的形势场及最低气温进行检验.结果表明:此次寒潮过程发生在北极涛动负位相期间,西伯利亚高压偏强,欧亚中高纬形成两槽一脊的环流形势.东亚大槽后侧强劲的偏北风引导低层冷空气南移,南支槽向东移动为云南省输送暖湿气流,700 hPa切变线和地面冷锋的南侵,共同造成了此次寒潮天气过程的发生;此次寒潮过程的强降温是由过程中近地层强冷平流的作用,冷锋后部较强的垂直上升运动,引起绝热膨胀冷却作用,加剧了局地气温的下降;通过定量分析导致昆明局地气温变化的各项因子发现,昆明的降温主要受温度平流项的影响,其次是非绝热项的影响. ECMWF模式能较好地预报此次寒潮过程的高低空环流形势及降温的范围,但对降温强度的预报效果相对较差.展开更多
为提高暴雨预报准确率,减少暴雨致灾损失,基于地面常规气象观测资料、卫星云图反演的云顶亮温(Black Body Temperature,TBB)资料及美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)再分析资料,对2017年8月云...为提高暴雨预报准确率,减少暴雨致灾损失,基于地面常规气象观测资料、卫星云图反演的云顶亮温(Black Body Temperature,TBB)资料及美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)再分析资料,对2017年8月云南一次强对流暴雨成因进行分析。结果表明:500 hPa低槽东移、700 hPa切变线南压、地面冷锋西推是此次降水过程发生的天气背景;中-β、中-α尺度对流系统(Mesoscale Convective System,MCS)是产生强对流暴雨的直接系统,强降雨主要出现在TBB梯度大值区;MCS与700 hPa切变线关系最为密切,切变线位于滇中以东地区,MCS呈椭圆状,沿切变线附近及后部发展,切变线靠近哀牢山或翻越后,MCS呈西北—东南向带状分布,沿切变线前部发展;切变线翻越哀牢山前,白天移动较快,主要产生雷暴天气,夜间移动缓慢,降雨较强;强对流暴雨需重点关注水汽通量辐合大值区、800 hPa与500 hPa温差大于20℃区域;强降雨时段,整层大气均为上升运动,强降雨区维持低层辐合、中高层辐散的动力抽吸机制。展开更多
BACKGROUND： Kainic acid can be used to induce a model of epilepsy by systemic injection, such as intraperitoneal or subcutaneous injection. Individual rats have different responses to kainic acid, therefore high dose...BACKGROUND： Kainic acid can be used to induce a model of epilepsy by systemic injection, such as intraperitoneal or subcutaneous injection. Individual rats have different responses to kainic acid, therefore high doses of drug are required and the success rate of model induction is low. It is necessary to develop an improved method to establish a temporal lobe epilepsy （TLE） animal model. OBJECTIVE： To explore an economic, stable and efficient method of establishing a TLE animal model. DESIGN, TIME AND SETTING： A completely randomized, controlled study. The experiments were performed in the Cellular Function Laboratory of the Physiology Department, Anhui Medical University from March to July 2007. MATERIALS： Twenty adult male Wistar rats, weighing 230-260 g, were provided by the Experimental Animal Centre of Nanjing Medical University. Kainic acid was purchased from Sigma in USA. Type SN-2 stereotaxic apparatus was made by Narishge in Japan. METHODS： Wistar rats were randomly divided into a kainic acid （KA） group （n = 12） and a normal saline （NS） group （n = 8）. For intrahippocampal microinjection, a burr hole was drilled in the skull at the following stereotaxic coordinates： anteroposterior （AP） 4.1 mm caudal to bregma; lateral （ML） 4.2 mm right lateral to the midline. Rats in the KA group were injected with 2.5 μL KA （0.4 g/L） into the center of the CA3 region, while in the NS group the same volume of NS was injected into the same site. MAIN OUTCOME MEASURES： Both groups were monitored under a video capture system for 12 weeks to record spontaneous seizures. Intracranial eletroencepholograph （IEEG） recordings in vivo were performed after the behavioral observations. After the IEEG recordings, hippocampi were processed into coronal sections. Nissl and Timm stainings were then performed to observe and confirm pathology. RESULTS： Twenty rats were involved in the final analysis. Behavioral observations： the eadiest spontaneous onset of epilepsy appeared 2 weeks after injection of KA. Eight rats had spontaneous onset of epilepsy 3-12 weeks after treatment. None of rats in the NS group had spontaneous onset of epilepsy. IEEG recordings： Epileptic-form waves, such as sharp waves and spike waves, were calculated by artificial analysis The number of epileptic-form waves in the KA group increased significantly compared to those of the NS group （P 〈 0.01）. Morphology results： In the KA group, Nissl staining and Timm staining revealed typical pathology in the hippocampal temporosphenoid lobe. In the NS group, no pathology was observed. CONCLUSION： Intrahippocampal microinjection of KA is a reliable method to establish a temporal lobe epilepsy animal model, requiring low doses of kainic acid and giving a high rate of success.展开更多
文摘2022年3月31日—4月2日,云南省出现历史同期罕见的寒潮天气过程.通过地面观测资料、高空观测资料和NCEP FNL资料,对此次寒潮过程的成因进行分析,并对欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)模式的形势场及最低气温进行检验.结果表明:此次寒潮过程发生在北极涛动负位相期间,西伯利亚高压偏强,欧亚中高纬形成两槽一脊的环流形势.东亚大槽后侧强劲的偏北风引导低层冷空气南移,南支槽向东移动为云南省输送暖湿气流,700 hPa切变线和地面冷锋的南侵,共同造成了此次寒潮天气过程的发生;此次寒潮过程的强降温是由过程中近地层强冷平流的作用,冷锋后部较强的垂直上升运动,引起绝热膨胀冷却作用,加剧了局地气温的下降;通过定量分析导致昆明局地气温变化的各项因子发现,昆明的降温主要受温度平流项的影响,其次是非绝热项的影响. ECMWF模式能较好地预报此次寒潮过程的高低空环流形势及降温的范围,但对降温强度的预报效果相对较差.
基金Funds for the Excellent Talent of Anhui Province of China, No.06043090National Century Excellent Talents in University of China, No.NCET-06-0557Natural Science Foundation of Anhui Province Department of Education, No. KJ2007A028
文摘BACKGROUND： Kainic acid can be used to induce a model of epilepsy by systemic injection, such as intraperitoneal or subcutaneous injection. Individual rats have different responses to kainic acid, therefore high doses of drug are required and the success rate of model induction is low. It is necessary to develop an improved method to establish a temporal lobe epilepsy （TLE） animal model. OBJECTIVE： To explore an economic, stable and efficient method of establishing a TLE animal model. DESIGN, TIME AND SETTING： A completely randomized, controlled study. The experiments were performed in the Cellular Function Laboratory of the Physiology Department, Anhui Medical University from March to July 2007. MATERIALS： Twenty adult male Wistar rats, weighing 230-260 g, were provided by the Experimental Animal Centre of Nanjing Medical University. Kainic acid was purchased from Sigma in USA. Type SN-2 stereotaxic apparatus was made by Narishge in Japan. METHODS： Wistar rats were randomly divided into a kainic acid （KA） group （n = 12） and a normal saline （NS） group （n = 8）. For intrahippocampal microinjection, a burr hole was drilled in the skull at the following stereotaxic coordinates： anteroposterior （AP） 4.1 mm caudal to bregma; lateral （ML） 4.2 mm right lateral to the midline. Rats in the KA group were injected with 2.5 μL KA （0.4 g/L） into the center of the CA3 region, while in the NS group the same volume of NS was injected into the same site. MAIN OUTCOME MEASURES： Both groups were monitored under a video capture system for 12 weeks to record spontaneous seizures. Intracranial eletroencepholograph （IEEG） recordings in vivo were performed after the behavioral observations. After the IEEG recordings, hippocampi were processed into coronal sections. Nissl and Timm stainings were then performed to observe and confirm pathology. RESULTS： Twenty rats were involved in the final analysis. Behavioral observations： the eadiest spontaneous onset of epilepsy appeared 2 weeks after injection of KA. Eight rats had spontaneous onset of epilepsy 3-12 weeks after treatment. None of rats in the NS group had spontaneous onset of epilepsy. IEEG recordings： Epileptic-form waves, such as sharp waves and spike waves, were calculated by artificial analysis The number of epileptic-form waves in the KA group increased significantly compared to those of the NS group （P 〈 0.01）. Morphology results： In the KA group, Nissl staining and Timm staining revealed typical pathology in the hippocampal temporosphenoid lobe. In the NS group, no pathology was observed. CONCLUSION： Intrahippocampal microinjection of KA is a reliable method to establish a temporal lobe epilepsy animal model, requiring low doses of kainic acid and giving a high rate of success.
