More than 3 years have passed since the outbreak of COVID-19 and yet, the origin of the causal virus SARS-CoV-2 remains unknown. We examined the evolutionary trajectory of SARS-CoV-2 by analyzing non-redundant genome ...More than 3 years have passed since the outbreak of COVID-19 and yet, the origin of the causal virus SARS-CoV-2 remains unknown. We examined the evolutionary trajectory of SARS-CoV-2 by analyzing non-redundant genome sets classified based on six closely linked mutations. The results indicated that SARS-CoV-2 emerged in February 2019 or earlier and evolved into three main haplotypes (GL, DS, and DL) before May 2019, which then continued to evolve in parallel. The dominant haplotype GL had spread worldwide in the summer (May to July) of 2019 and then evolved into virulent strains in December 2019 that triggered the global pandemic, whereas haplotypes DL and DS arrived in China in October 2019 and caused the epidemic in China in December 2019. Therefore, haplotype GL neither originated in China nor from the viral strains that caused the epidemic in China. Accordingly, considering data solely from China would be inadequate to reveal the mysterious origin of SARS-CoV-2, emphasizing the necessity of global cooperation.展开更多
Background: Coronary artery anomalies(CAAs) are a relatively rare condition usually diagnosed in vivo by conventional angiography. In the past few years Magnetic resonance coronary angiography(MRCA) has been used to d...Background: Coronary artery anomalies(CAAs) are a relatively rare condition usually diagnosed in vivo by conventional angiography. In the past few years Magnetic resonance coronary angiography(MRCA) has been used to detect CAAs and found to be highly accurate. No data is available regarding the ability of MRCA to detect previously not suspected anomalies. Methods: We prospectively analyzed the origin and course of 336 patients undergoing a diagnostic Cardiovascular magnetic resonance(CMR) study. After the completion of a standard examination a navigator-echo 3D-MRCA low-quality scan was used in all the cases to rule out CAAs. The high-quality MRCA was applied only if an abnormal coronary arterial tree was seen. Results: Nineteen patients with CAAs(12 men, 7 women;mean age, 53±18 years) were identified by MRCA. Six out of the 19 CAAs subjects had already been detected by other means(coronary angiography in 5, and transesophageal echocardiography in 1 case). However in none of them a complete anatomical assessment was achieved. In 13 patients CAAs were an unexpected and new finding. MRCA was able to assess the origin and proximal course of the anomalous artery in all the cases. Conclusions: MRCA is able to detect the presence and anomalous course of CAAs. Besides offering precise information about already suspected CAAs, MRCA can identify anomalies previously not suspected. This study suggests a potential role for MRCA as a screening tool for CAAs in young patients with angina, ventricular arrhythmias, or unexplained syncope as well as in highly competitive athletes.展开更多
Motivated by sample path decomposition of the stationary continuous state branching process with immigration, a general population model is considered using the idea of immortal individual. We compute the joint distri...Motivated by sample path decomposition of the stationary continuous state branching process with immigration, a general population model is considered using the idea of immortal individual. We compute the joint distribution of the random variables： the time to the most recent common ancestor （MRCA）, the size of the current population, and the size of the population just before MRCA. We obtain the bottleneck effect as well. The distribution of the number of the oldest families is also established. These generalize the results obtained by Y. T. Chen and J. F. Delmas.展开更多
基金supported by grants from the National Key R&D Program of China and the Central Public-interest Scientific Institution Basal Research Fund to J.Z.(1630052020022)by the Project of Science and Technology Department of Sichuan Provincial of China to L.Y.(2019JDJQ0035).
文摘More than 3 years have passed since the outbreak of COVID-19 and yet, the origin of the causal virus SARS-CoV-2 remains unknown. We examined the evolutionary trajectory of SARS-CoV-2 by analyzing non-redundant genome sets classified based on six closely linked mutations. The results indicated that SARS-CoV-2 emerged in February 2019 or earlier and evolved into three main haplotypes (GL, DS, and DL) before May 2019, which then continued to evolve in parallel. The dominant haplotype GL had spread worldwide in the summer (May to July) of 2019 and then evolved into virulent strains in December 2019 that triggered the global pandemic, whereas haplotypes DL and DS arrived in China in October 2019 and caused the epidemic in China in December 2019. Therefore, haplotype GL neither originated in China nor from the viral strains that caused the epidemic in China. Accordingly, considering data solely from China would be inadequate to reveal the mysterious origin of SARS-CoV-2, emphasizing the necessity of global cooperation.
文摘Background: Coronary artery anomalies(CAAs) are a relatively rare condition usually diagnosed in vivo by conventional angiography. In the past few years Magnetic resonance coronary angiography(MRCA) has been used to detect CAAs and found to be highly accurate. No data is available regarding the ability of MRCA to detect previously not suspected anomalies. Methods: We prospectively analyzed the origin and course of 336 patients undergoing a diagnostic Cardiovascular magnetic resonance(CMR) study. After the completion of a standard examination a navigator-echo 3D-MRCA low-quality scan was used in all the cases to rule out CAAs. The high-quality MRCA was applied only if an abnormal coronary arterial tree was seen. Results: Nineteen patients with CAAs(12 men, 7 women;mean age, 53±18 years) were identified by MRCA. Six out of the 19 CAAs subjects had already been detected by other means(coronary angiography in 5, and transesophageal echocardiography in 1 case). However in none of them a complete anatomical assessment was achieved. In 13 patients CAAs were an unexpected and new finding. MRCA was able to assess the origin and proximal course of the anomalous artery in all the cases. Conclusions: MRCA is able to detect the presence and anomalous course of CAAs. Besides offering precise information about already suspected CAAs, MRCA can identify anomalies previously not suspected. This study suggests a potential role for MRCA as a screening tool for CAAs in young patients with angina, ventricular arrhythmias, or unexplained syncope as well as in highly competitive athletes.
基金Acknowledgements The author would like to express his sincere thanks to his advisor Professor Zenghu Li for his persistent encouragements and suggestions and Professor J. F. Delmas for his careful check of this work. Thanks are also given to the anonymous referees for the suggestions. This work was supported in part by the National Natural Science Foundation of China （Grant No. 11131003） and the 985 Program.
文摘Motivated by sample path decomposition of the stationary continuous state branching process with immigration, a general population model is considered using the idea of immortal individual. We compute the joint distribution of the random variables： the time to the most recent common ancestor （MRCA）, the size of the current population, and the size of the population just before MRCA. We obtain the bottleneck effect as well. The distribution of the number of the oldest families is also established. These generalize the results obtained by Y. T. Chen and J. F. Delmas.
