Lepidopteran stem borers are the most damaging pests of maize in Sub-Saharan Africa. Despite the growing importance of maize in the forest zone of Democratic Republic of Congo, no data is available regarding stem bore...Lepidopteran stem borers are the most damaging pests of maize in Sub-Saharan Africa. Despite the growing importance of maize in the forest zone of Democratic Republic of Congo, no data is available regarding stem borer pest species present and their relative importance. It is thus important to gather information likely to guide future research in this area. This study was undertaken to catalogue stem borer pest species identity and assess their relative infestation levels on maize. Surveys were carried out in wild and cultivated habitats in Kisangani. Five species were collected on maize, i.e., Sesamia calamistis Hampson （1910）, Eldana saccharina Walker （1865）, Busseola fusca Fuller （1901）, Chilo sp. Strand （1913）, and Mussidia nigrivenella Ragonot （1888）. In the wild habitats, Poenoma serrata Hampson, B. fusca and S. calamistis were collected on Pennisetum purpureum whereas Chilo sp. was collected on Panicum maximum. Our results suggest that P. maximum might affect the population dynamics of Chilo sp. whereas P. purpureum is expected not to influence the population dynamics of other stem borers owing to its scarcity in the interior of the forest.展开更多
Based on archival materials discovered in America,Britain,and China,this paper carefully examines the history of the short-lived and completely overlooked Department of Physics in the Premedical School of Peking Union...Based on archival materials discovered in America,Britain,and China,this paper carefully examines the history of the short-lived and completely overlooked Department of Physics in the Premedical School of Peking Union Medical College(PUMC),and uncovers this department’s extensive interconnections with its counterpart at Yenching University.This project also looks into the Master of Science(MS)program in the Department of Physics at Yenching University,which,founded in 1927,was the first graduate program in physics in China.It was this MS program that transformed the Yenching Department from a largely premedical training center serving the PUMC into a prominent cradle of Chinese physics research.This Yenching Department,despite its small faculty and brief existence,nurtured many eminent Chinese physicists,such as Chao-Ying Meng孟昭英,Wen-Yu Chang张文裕,Ming-Chen Wang王明贞,Chia-Liu Luke Yuan袁家骝,Cheng-Shu Wang(Chang)王承书,Ho-Fu Lu卢鹤绂,Ting-Sui Ke葛庭燧,Kun Huang黄昆,and Chia-Lin Hsieh谢家麟.It would have been impossible to achieve these outstanding accomplishments without the effective leadership and pioneering work of C.H.Corbett,P.A.Anderson,Y.M.Hsieh,and W.Band—the first four Department Chairs—in combination with relatively abundant private funding,mostly from America,and extensive educational connections with Western institutions.This paper not only introduces in detail these four department heads and their contributions,but also discloses the unique role played by the Rockefeller Foundation via the China Medical Board and the PUMC in the development of the Yenching Department of Physics.展开更多
Soil organic carbon(SOC) content and its stable carbon isotopic composition(within the upper 1 m) were measured to determine the e?ect of land-use changes from dry evergreen forest to maize fields in eastern Thailand....Soil organic carbon(SOC) content and its stable carbon isotopic composition(within the upper 1 m) were measured to determine the e?ect of land-use changes from dry evergreen forest to maize fields in eastern Thailand.Digital land cover maps,derived from aerial photography and satellite images for years 1989,1996,and 2002 were used in association with field surveys and farmer interviews to derive land-use history and to assist in study site selection.Conversion from forest to maize cultivation for the duration of 12 years reduced SOC stocks at the rate of 6.97 Mg C ha-1 year-1.Reduction was most pronounced in the top 10 cm soil layer,which was 47% after 12 years of cultivation.Stable carbon isotope data revealed that the main fraction lost was forest-derived C.Generally low input rates of maize-derived C were not sufficient to maintain SOC at the level prior to forest conversion.After 12 years of continuous maize cultivation,the maize-derived C fraction made up about 20% of total SOC(5 Mg ha-1 of the total 25.31 Mg ha-1).展开更多
Information on the most influential factors determining gas flux from soils is needed in predictive models for greenhouse gases emissions. We conducted an intensive soil and air sampling along a 2 000 m transect exten...Information on the most influential factors determining gas flux from soils is needed in predictive models for greenhouse gases emissions. We conducted an intensive soil and air sampling along a 2 000 m transect extending from a forest, pasture, grassland and corn field in Shizunai, Hokkaido （Japan）, measured CO2, CH4, N20 and NO fluxes and calculated soil bulk density （Pb）, air-filled porosity （fa） and total porosity （Ф）. Using diffusivity models based on either fa alone or on a combination of fa and 4, we predicted two pore space indices： the relative gas diffusion coefficient （Ds/Do） and the pore tortuosity factor （T）. The relationships between pore space indices （Ds/Do and T） and C02, CH4, N2O and NO fluxes were also studied. Results showed that the grassland had the highest Pb while fa and Ф were the highest in the forest. CO2, CH4, N20 and NO fluxes were the highest in the grassland while N20 dominated in the corn field. Few correlations existed between fa, Ф, Pb and gases fluxes while all models predicted that Ds/Do and T significantly correlated with CO2 and CH4 with correlation coefficient （r） ranging from 0.20 to 0.80. Overall, diffusivity models based on fa alone gave higher Ds/Do, lower τ, and higher R2 and better explained the relationship between pore space indices （Ds/Do and τ） and gases fluxes. Inclusion of Ds/Do and τ in predictive models will improve our understanding of the dynamics of greenhouse gas fluxes from soils. Ds/Do and τ can be easily obtained by measurements of soil air and water and existing diffusivity models.展开更多
文摘Lepidopteran stem borers are the most damaging pests of maize in Sub-Saharan Africa. Despite the growing importance of maize in the forest zone of Democratic Republic of Congo, no data is available regarding stem borer pest species present and their relative importance. It is thus important to gather information likely to guide future research in this area. This study was undertaken to catalogue stem borer pest species identity and assess their relative infestation levels on maize. Surveys were carried out in wild and cultivated habitats in Kisangani. Five species were collected on maize, i.e., Sesamia calamistis Hampson （1910）, Eldana saccharina Walker （1865）, Busseola fusca Fuller （1901）, Chilo sp. Strand （1913）, and Mussidia nigrivenella Ragonot （1888）. In the wild habitats, Poenoma serrata Hampson, B. fusca and S. calamistis were collected on Pennisetum purpureum whereas Chilo sp. was collected on Panicum maximum. Our results suggest that P. maximum might affect the population dynamics of Chilo sp. whereas P. purpureum is expected not to influence the population dynamics of other stem borers owing to its scarcity in the interior of the forest.
文摘Based on archival materials discovered in America,Britain,and China,this paper carefully examines the history of the short-lived and completely overlooked Department of Physics in the Premedical School of Peking Union Medical College(PUMC),and uncovers this department’s extensive interconnections with its counterpart at Yenching University.This project also looks into the Master of Science(MS)program in the Department of Physics at Yenching University,which,founded in 1927,was the first graduate program in physics in China.It was this MS program that transformed the Yenching Department from a largely premedical training center serving the PUMC into a prominent cradle of Chinese physics research.This Yenching Department,despite its small faculty and brief existence,nurtured many eminent Chinese physicists,such as Chao-Ying Meng孟昭英,Wen-Yu Chang张文裕,Ming-Chen Wang王明贞,Chia-Liu Luke Yuan袁家骝,Cheng-Shu Wang(Chang)王承书,Ho-Fu Lu卢鹤绂,Ting-Sui Ke葛庭燧,Kun Huang黄昆,and Chia-Lin Hsieh谢家麟.It would have been impossible to achieve these outstanding accomplishments without the effective leadership and pioneering work of C.H.Corbett,P.A.Anderson,Y.M.Hsieh,and W.Band—the first four Department Chairs—in combination with relatively abundant private funding,mostly from America,and extensive educational connections with Western institutions.This paper not only introduces in detail these four department heads and their contributions,but also discloses the unique role played by the Rockefeller Foundation via the China Medical Board and the PUMC in the development of the Yenching Department of Physics.
基金Supported by the National Research University Project of Thailand's Office of the Higher Education Commission (HEC)
文摘Soil organic carbon(SOC) content and its stable carbon isotopic composition(within the upper 1 m) were measured to determine the e?ect of land-use changes from dry evergreen forest to maize fields in eastern Thailand.Digital land cover maps,derived from aerial photography and satellite images for years 1989,1996,and 2002 were used in association with field surveys and farmer interviews to derive land-use history and to assist in study site selection.Conversion from forest to maize cultivation for the duration of 12 years reduced SOC stocks at the rate of 6.97 Mg C ha-1 year-1.Reduction was most pronounced in the top 10 cm soil layer,which was 47% after 12 years of cultivation.Stable carbon isotope data revealed that the main fraction lost was forest-derived C.Generally low input rates of maize-derived C were not sufficient to maintain SOC at the level prior to forest conversion.After 12 years of continuous maize cultivation,the maize-derived C fraction made up about 20% of total SOC(5 Mg ha-1 of the total 25.31 Mg ha-1).
基金Supported by the Japanese Society for the Promotion of Science (JSPS)the Ministry of Education of Japan (No. PI0701)
文摘Information on the most influential factors determining gas flux from soils is needed in predictive models for greenhouse gases emissions. We conducted an intensive soil and air sampling along a 2 000 m transect extending from a forest, pasture, grassland and corn field in Shizunai, Hokkaido （Japan）, measured CO2, CH4, N20 and NO fluxes and calculated soil bulk density （Pb）, air-filled porosity （fa） and total porosity （Ф）. Using diffusivity models based on either fa alone or on a combination of fa and 4, we predicted two pore space indices： the relative gas diffusion coefficient （Ds/Do） and the pore tortuosity factor （T）. The relationships between pore space indices （Ds/Do and T） and C02, CH4, N2O and NO fluxes were also studied. Results showed that the grassland had the highest Pb while fa and Ф were the highest in the forest. CO2, CH4, N20 and NO fluxes were the highest in the grassland while N20 dominated in the corn field. Few correlations existed between fa, Ф, Pb and gases fluxes while all models predicted that Ds/Do and T significantly correlated with CO2 and CH4 with correlation coefficient （r） ranging from 0.20 to 0.80. Overall, diffusivity models based on fa alone gave higher Ds/Do, lower τ, and higher R2 and better explained the relationship between pore space indices （Ds/Do and τ） and gases fluxes. Inclusion of Ds/Do and τ in predictive models will improve our understanding of the dynamics of greenhouse gas fluxes from soils. Ds/Do and τ can be easily obtained by measurements of soil air and water and existing diffusivity models.
