We derive the exchange currents of pseudoscalar, vector, and scalar mesons from Feynman diagrams, and use them to calculate the magnetic form factors of nucleon and △(1232). The magnetic moments and electromagnetic r...We derive the exchange currents of pseudoscalar, vector, and scalar mesons from Feynman diagrams, and use them to calculate the magnetic form factors of nucleon and △(1232). The magnetic moments and electromagnetic radii are obtained by using those form factors and the parameters determined from the masses of nucleon and △(1232).We find the magnetic moments and electromagnetic radii of nucleon and △(1232) can be produced very well in the extended Goldstone-Boson-exchange model in which all of pseudoscalar, vector, and scalar meson nonet are included.The magnetic moments of △(1232) are closer to experiment values and results from lattice calculation than the results obtained by the model without other mesons except for pion and sigma.展开更多
Beijing has been severely affected by SARS, and SARS-associated coronavirus has been confirmed as its cause. However, clinical and experimental evidence implicates the possibility of co-infection. In this report, reov...Beijing has been severely affected by SARS, and SARS-associated coronavirus has been confirmed as its cause. However, clinical and experimental evidence implicates the possibility of co-infection. In this report, reovirus was isolated from throat swabs of SARS patients, including the first case in Beijing and her mother. Identification with the electron microscopy revealed the characteristic features of reovirus. 24 of 38 samples from other SARS cases were found to have serologic responses to the reovirus. Primers designed for reovirus have amplified several fragments of DNA, one of which was sequenced (S2 gene fragment), which indicates it as a unique reovirus (orthoreovirus). Preliminary animal experiment showed that inoculation of the reovirus in mice caused death with atypical pneumonia. Nevertheless, the association of reovirus with SARS outbreak requires to be further investigated.展开更多
What does SARS mean to China? Hu Jingtao, the new leader of China, shared his understanding of it-SARS is really a disaster to China. Hu is right. A magic box opened and a devil called SARS came out. Thousands of peop...What does SARS mean to China? Hu Jingtao, the new leader of China, shared his understanding of it-SARS is really a disaster to China. Hu is right. A magic box opened and a devil called SARS came out. Thousands of people were infected, hundreds died. Almost all of China s residents have saent time worrvin~ about SARS.展开更多
文摘We derive the exchange currents of pseudoscalar, vector, and scalar mesons from Feynman diagrams, and use them to calculate the magnetic form factors of nucleon and △(1232). The magnetic moments and electromagnetic radii are obtained by using those form factors and the parameters determined from the masses of nucleon and △(1232).We find the magnetic moments and electromagnetic radii of nucleon and △(1232) can be produced very well in the extended Goldstone-Boson-exchange model in which all of pseudoscalar, vector, and scalar meson nonet are included.The magnetic moments of △(1232) are closer to experiment values and results from lattice calculation than the results obtained by the model without other mesons except for pion and sigma.
基金supported by the National High Technology Research and Development Program of China(Grant No.2001AA233041).
文摘Beijing has been severely affected by SARS, and SARS-associated coronavirus has been confirmed as its cause. However, clinical and experimental evidence implicates the possibility of co-infection. In this report, reovirus was isolated from throat swabs of SARS patients, including the first case in Beijing and her mother. Identification with the electron microscopy revealed the characteristic features of reovirus. 24 of 38 samples from other SARS cases were found to have serologic responses to the reovirus. Primers designed for reovirus have amplified several fragments of DNA, one of which was sequenced (S2 gene fragment), which indicates it as a unique reovirus (orthoreovirus). Preliminary animal experiment showed that inoculation of the reovirus in mice caused death with atypical pneumonia. Nevertheless, the association of reovirus with SARS outbreak requires to be further investigated.
文摘What does SARS mean to China? Hu Jingtao, the new leader of China, shared his understanding of it-SARS is really a disaster to China. Hu is right. A magic box opened and a devil called SARS came out. Thousands of people were infected, hundreds died. Almost all of China s residents have saent time worrvin~ about SARS.
