This work analyzes the photometric data of the Oort spike comets C/2019 L3(ATLAS)and C/2019 O3(Palomar)obtained between 2016 and 2023 by the ATLAS network and the Belgian Olmen Observatory.The comets Palomar and ATLAS...This work analyzes the photometric data of the Oort spike comets C/2019 L3(ATLAS)and C/2019 O3(Palomar)obtained between 2016 and 2023 by the ATLAS network and the Belgian Olmen Observatory.The comets Palomar and ATLAS have a typical and unusually high activity level,respectively,based on the Afρparameter corrected to phase angle zero at perihelion.The absolute magnitude of comets ATLAS and Palomar in the o-band is 4.71±0.05 and 4.16±0.02 respectively.The cometary activity of comets ATLAS and Palomar probably began at r>13 au before perihelion and will end at r>14 au after perihelion,which means that they could remain active until the second half of 2026.The nucleus of comet ATLAS has a minimum radius of 7.9 km,and the nucleus of comet Palomar could be a little larger.The c-o colors of the comets ATLAS and Palomar are redder and bluer,respectively,at perihelion than the solar twin YBP 1194.These comets showed a bluish trend in the coma color with decreasing heliocentric distance.Comet Palomar probably had two outbursts after its perihelion,each releasing about 10^(8)kg of dust.The slopes of the photometric profile of the comae of these comets were between 1and 1.5,indicating a steady state during the observation campaign.展开更多
In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We ex...In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We extracted morphological features through image enhancement techniques and calculated the dust activity parameter,Afρ,along with dust mass loss rates and coma color indices using broadband photometric data.Our morphological analysis uncovered a spectrum of dust characteristics among the observed comets,ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels.The Afρvalues varied between 148.8±0.3 cm for 64P/Swift-Gehrels and1118.5±6.2 cm for C/2017 M4(ATLAS)(measured within a reference aperture radius ofρ=6″),indicating a range from moderate to high activity levels.Dust mass loss rates were estimated from 328.1 kg s^(-1)for comet 64P/Swift-Gehrels to 1395.5 kg s^(-1)for comet C/2017 M4(ATLAS).The color indices of comets 38P/Stephan-Oterma and C/2017 M4(ATLAS)closely resemble the average colors of active short-period comets and active longperiod comets,respectively.In contrast,64P/Swift-Gehrels exhibits a significantly bluer hue than typical Jupiter family comets.展开更多
Upper mantle earthquakes are usually associated with plate boundary tectonics, but rarely occur beneath intracontinental orogenic belts. In the Moroccan Atlas Mountains, earthquakes determined at subcrustal depths are...Upper mantle earthquakes are usually associated with plate boundary tectonics, but rarely occur beneath intracontinental orogenic belts. In the Moroccan Atlas Mountains, earthquakes determined at subcrustal depths are a controversial topic because they are few in number compared to subduction zones and are not related to plate boundary tectonics. A recent increase of broadband stations in Morocco has revealed numerous events below the Atlas belts, thought to occur from the upper mantle. Using additional available stations, these Atlas events were relocated and new epicenter resolutions were acquired following rigorous depth and RMS error criteria. 309 events were reprocessed and epicenter depths obtained were between 31 and 240 km during the last 23 years. Temporal variations of High Atlas events appear to be continually dipping while Anti Atlas events show no temporal variation trends. In addition, a recent strong event M6.8 occurred in September 2023 at the transition crust-uppermost mantle followed by several aftershocks which have been relocated at uppermost mantle depths. These events support delamination model under the High-Middle Atlas which could flow southward beneath the Anti Atlas lithosphere, and explain the large variation observed in lithosphere thickness between the High-Middle Atlas, and the Anti Atlas. Subcrustal events beneath the Atlas may be related to upper mantle earthquakes beneath the neighboring Canary Islands which have experienced recent swarms and eruptions. This possible correlation cannot be excluded since descending and ascending material is necessary for a regional geodynamic balance.展开更多
由杨培增教授独自完成的大型英文葡萄膜炎专著《Atlas of Uveitis:Diagnosis and Treatment》已于2020年12月由Springer出版社和人民卫生出版社联合出版。此书是目前国际上单人完成的最大葡萄膜炎专著,共860页、3000余张患者图片,约合中...由杨培增教授独自完成的大型英文葡萄膜炎专著《Atlas of Uveitis:Diagnosis and Treatment》已于2020年12月由Springer出版社和人民卫生出版社联合出版。此书是目前国际上单人完成的最大葡萄膜炎专著,共860页、3000余张患者图片,约合中文170万字。此书分为Overview、Diagnosis of Uveitis、Treatment of Uveitis.Uveitisentities,Scleritis and Episcleritis四大部分,详细介绍了葡萄膜炎类疾病的疾病谱,常见类型的临床特征、进展和致盲规律,疾病诊疗的思想、原则、策略,并使用大量精美图片展现了常见葡萄膜炎类型的表现谱,即从发病到疾病后期,从最细微的异常到最严重的改变,从罕见的表现到典型的特征,展示出葡萄膜炎的全貌和细节,既可使临床医师快速掌握疾病要点,又不至于遗漏细微之处。这也是中国眼科医师首次向国际介绍葡萄膜炎诊疗的中国标准、方案和经验。展开更多
基金The ATLAS project is primarily funded to search for near-earth asteroids through NASA grants NN12AR55G,80NSSC18K0284,and 80NSSC18K1575funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889,and STFC grants ST/T000198/1 and ST/S006109/1。
文摘This work analyzes the photometric data of the Oort spike comets C/2019 L3(ATLAS)and C/2019 O3(Palomar)obtained between 2016 and 2023 by the ATLAS network and the Belgian Olmen Observatory.The comets Palomar and ATLAS have a typical and unusually high activity level,respectively,based on the Afρparameter corrected to phase angle zero at perihelion.The absolute magnitude of comets ATLAS and Palomar in the o-band is 4.71±0.05 and 4.16±0.02 respectively.The cometary activity of comets ATLAS and Palomar probably began at r>13 au before perihelion and will end at r>14 au after perihelion,which means that they could remain active until the second half of 2026.The nucleus of comet ATLAS has a minimum radius of 7.9 km,and the nucleus of comet Palomar could be a little larger.The c-o colors of the comets ATLAS and Palomar are redder and bluer,respectively,at perihelion than the solar twin YBP 1194.These comets showed a bluish trend in the coma color with decreasing heliocentric distance.Comet Palomar probably had two outbursts after its perihelion,each releasing about 10^(8)kg of dust.The slopes of the photometric profile of the comae of these comets were between 1and 1.5,indicating a steady state during the observation campaign.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China(grant No.2021D01B112)Tianshan Talent Training Program through the grant 2023TSYCCX0101。
文摘In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We extracted morphological features through image enhancement techniques and calculated the dust activity parameter,Afρ,along with dust mass loss rates and coma color indices using broadband photometric data.Our morphological analysis uncovered a spectrum of dust characteristics among the observed comets,ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels.The Afρvalues varied between 148.8±0.3 cm for 64P/Swift-Gehrels and1118.5±6.2 cm for C/2017 M4(ATLAS)(measured within a reference aperture radius ofρ=6″),indicating a range from moderate to high activity levels.Dust mass loss rates were estimated from 328.1 kg s^(-1)for comet 64P/Swift-Gehrels to 1395.5 kg s^(-1)for comet C/2017 M4(ATLAS).The color indices of comets 38P/Stephan-Oterma and C/2017 M4(ATLAS)closely resemble the average colors of active short-period comets and active longperiod comets,respectively.In contrast,64P/Swift-Gehrels exhibits a significantly bluer hue than typical Jupiter family comets.
文摘Upper mantle earthquakes are usually associated with plate boundary tectonics, but rarely occur beneath intracontinental orogenic belts. In the Moroccan Atlas Mountains, earthquakes determined at subcrustal depths are a controversial topic because they are few in number compared to subduction zones and are not related to plate boundary tectonics. A recent increase of broadband stations in Morocco has revealed numerous events below the Atlas belts, thought to occur from the upper mantle. Using additional available stations, these Atlas events were relocated and new epicenter resolutions were acquired following rigorous depth and RMS error criteria. 309 events were reprocessed and epicenter depths obtained were between 31 and 240 km during the last 23 years. Temporal variations of High Atlas events appear to be continually dipping while Anti Atlas events show no temporal variation trends. In addition, a recent strong event M6.8 occurred in September 2023 at the transition crust-uppermost mantle followed by several aftershocks which have been relocated at uppermost mantle depths. These events support delamination model under the High-Middle Atlas which could flow southward beneath the Anti Atlas lithosphere, and explain the large variation observed in lithosphere thickness between the High-Middle Atlas, and the Anti Atlas. Subcrustal events beneath the Atlas may be related to upper mantle earthquakes beneath the neighboring Canary Islands which have experienced recent swarms and eruptions. This possible correlation cannot be excluded since descending and ascending material is necessary for a regional geodynamic balance.
文摘由杨培增教授独自完成的大型英文葡萄膜炎专著《Atlas of Uveitis:Diagnosis and Treatment》已于2020年12月由Springer出版社和人民卫生出版社联合出版。此书是目前国际上单人完成的最大葡萄膜炎专著,共860页、3000余张患者图片,约合中文170万字。此书分为Overview、Diagnosis of Uveitis、Treatment of Uveitis.Uveitisentities,Scleritis and Episcleritis四大部分,详细介绍了葡萄膜炎类疾病的疾病谱,常见类型的临床特征、进展和致盲规律,疾病诊疗的思想、原则、策略,并使用大量精美图片展现了常见葡萄膜炎类型的表现谱,即从发病到疾病后期,从最细微的异常到最严重的改变,从罕见的表现到典型的特征,展示出葡萄膜炎的全貌和细节,既可使临床医师快速掌握疾病要点,又不至于遗漏细微之处。这也是中国眼科医师首次向国际介绍葡萄膜炎诊疗的中国标准、方案和经验。
