目的：探讨40～70岁年龄段正常汉族人颅脑各区域磁共振表观弥散系数（ADC）变化特点，建立正常中老年人群颅脑ADC值变化趋势的基准。方法选择30例无阳性颅脑病征的正常汉族受试者，按年龄段分为3组，使用GE Medical System 3.0 T超导磁...目的：探讨40～70岁年龄段正常汉族人颅脑各区域磁共振表观弥散系数（ADC）变化特点，建立正常中老年人群颅脑ADC值变化趋势的基准。方法选择30例无阳性颅脑病征的正常汉族受试者，按年龄段分为3组，使用GE Medical System 3.0 T超导磁共振扫描仪进行头部平扫及弥散加权成像，测量额叶灰质、白质、壳核、丘脑及小脑感兴趣区ADC值，分析各年龄组不同区域脑组织ADC值的关系。结果同一年龄的正常中老年人不同部位的脑组织ADC值不同，其中以额叶灰质最高，其次为壳核、额叶白质与丘脑，小脑最低（均P＜0.05）。不同部位脑组织左右两侧间ADC值均无统计学差异（均P＞0.05）。不同年龄段的正常中老年人额叶灰质、额叶白质、壳核、丘脑与小脑ADC值间均无统计学差异（均P＞0.05）；不同部位脑组织的ADC值随着年龄的增长均呈上升趋势，且40-60岁上升趋势较缓，60岁之后除小脑外，额叶灰质、额叶白质、壳核、丘脑上升趋势加快。结论正常中老年人群同一部位脑组织的ADC值随年龄增长而上升，60岁之后总体上升趋势加快。展开更多
We reported the rare case of an elderly man with secondary breast lymphoma （SBL） associated with magnetic resonance imaging findings. MR images demonstrated multiple well-defined masses in the left breast, with hete...We reported the rare case of an elderly man with secondary breast lymphoma （SBL） associated with magnetic resonance imaging findings. MR images demonstrated multiple well-defined masses in the left breast, with heterogeneous enhancement on dynamic contrast-enhanced sequences. The time signal-intensity curve rapidly increased during the initial rise phase and washed out during the delayed phase. The apparent diffusion coefficient （ADC） value was 0.649 x 104 mm2/s. Maximum intensity projection （MIP） showed that the masses were distributed in the upper outer quadrant, in the axillary region and in the lower outer region of the left chest wall. The pathology confirmed the diagnosis of non-Flodgkin＇s lymphoma. The combination of morphological and kinetic features, as well as a significantly lower ADC value, are helpful in the diagnosis of breast lymphoma and its differentiation from breast cancer.展开更多
China is believed to have gained immensely from its admission into to the World Trade Organization （WTO） in 2001. One of the direct gains comes from the lessening of deadweight loss （DWL） due to tariff reduction. ...China is believed to have gained immensely from its admission into to the World Trade Organization （WTO） in 2001. One of the direct gains comes from the lessening of deadweight loss （DWL） due to tariff reduction. Conventional measures for DWL, however, are too aggregate to capture the trade policies, which are determined at a much higher disaggregated level, and ignore the interactions between tariff and corresponding import demand as suggested by theories. In this paper, we first systematically estimate the import demand elasticities at a highly disaggregated level and then match them with the most detailed lines of the applied tariff for the most favored nations as reported by the WTO. Using the detailed matching data, we construct Feenstra＇s （1995） simplified trade restrictiveness index （TRI）, which captures the covariance of tariff and the corresponding demand elasticity. Finally, we use the TRI to compute the DWL from1997 to 2008 and find that the DWL due to the tariff barrier was reduced to 0.73% of GNI in 2008, noticeably lower than the highest previous mark of 4.58% of GNI in 2001.展开更多
文摘目的：探讨40～70岁年龄段正常汉族人颅脑各区域磁共振表观弥散系数（ADC）变化特点，建立正常中老年人群颅脑ADC值变化趋势的基准。方法选择30例无阳性颅脑病征的正常汉族受试者，按年龄段分为3组，使用GE Medical System 3.0 T超导磁共振扫描仪进行头部平扫及弥散加权成像，测量额叶灰质、白质、壳核、丘脑及小脑感兴趣区ADC值，分析各年龄组不同区域脑组织ADC值的关系。结果同一年龄的正常中老年人不同部位的脑组织ADC值不同，其中以额叶灰质最高，其次为壳核、额叶白质与丘脑，小脑最低（均P＜0.05）。不同部位脑组织左右两侧间ADC值均无统计学差异（均P＞0.05）。不同年龄段的正常中老年人额叶灰质、额叶白质、壳核、丘脑与小脑ADC值间均无统计学差异（均P＞0.05）；不同部位脑组织的ADC值随着年龄的增长均呈上升趋势，且40-60岁上升趋势较缓，60岁之后除小脑外，额叶灰质、额叶白质、壳核、丘脑上升趋势加快。结论正常中老年人群同一部位脑组织的ADC值随年龄增长而上升，60岁之后总体上升趋势加快。
文摘We reported the rare case of an elderly man with secondary breast lymphoma （SBL） associated with magnetic resonance imaging findings. MR images demonstrated multiple well-defined masses in the left breast, with heterogeneous enhancement on dynamic contrast-enhanced sequences. The time signal-intensity curve rapidly increased during the initial rise phase and washed out during the delayed phase. The apparent diffusion coefficient （ADC） value was 0.649 x 104 mm2/s. Maximum intensity projection （MIP） showed that the masses were distributed in the upper outer quadrant, in the axillary region and in the lower outer region of the left chest wall. The pathology confirmed the diagnosis of non-Flodgkin＇s lymphoma. The combination of morphological and kinetic features, as well as a significantly lower ADC value, are helpful in the diagnosis of breast lymphoma and its differentiation from breast cancer.
基金Acknowledgements We are grateful to the participants at CESifo Venice Summer Institute workshop on ＂China and the Global Economy Post Crisis＂ for their invaluable comments. All errors in this paper are ours. Bo Chen acknowledges the financial support of the Ministry of Education of China （No. 09YJC790180） and of the Natural Science Foundation of China （No. 71103116）.
文摘China is believed to have gained immensely from its admission into to the World Trade Organization （WTO） in 2001. One of the direct gains comes from the lessening of deadweight loss （DWL） due to tariff reduction. Conventional measures for DWL, however, are too aggregate to capture the trade policies, which are determined at a much higher disaggregated level, and ignore the interactions between tariff and corresponding import demand as suggested by theories. In this paper, we first systematically estimate the import demand elasticities at a highly disaggregated level and then match them with the most detailed lines of the applied tariff for the most favored nations as reported by the WTO. Using the detailed matching data, we construct Feenstra＇s （1995） simplified trade restrictiveness index （TRI）, which captures the covariance of tariff and the corresponding demand elasticity. Finally, we use the TRI to compute the DWL from1997 to 2008 and find that the DWL due to the tariff barrier was reduced to 0.73% of GNI in 2008, noticeably lower than the highest previous mark of 4.58% of GNI in 2001.
