Recently,the quantitative rescattering model(QRS)for nonsequential double ionization(NSDI)is modified by taking into account the potential change(PC)due to the presence of electric field at the time of recollision.Usi...Recently,the quantitative rescattering model(QRS)for nonsequential double ionization(NSDI)is modified by taking into account the potential change(PC)due to the presence of electric field at the time of recollision.Using the improved QRS model,we simulate the longitudinal momentum distributions of doubly charged ions He2+by projecting the correlated two-electron momentum distributions for NSDI of He onto the main diagonal.The obtained results are compared directly with the experimental data at different intensities.It is found that when the PC is considered,the width of momentum distributions reduces and the agreement between theory and experiment is improved.展开更多
It is now well known that coastal urban local climate has been showing changing pattern due to global climate change. This communication attempts to explore fluctuating pattern of urban average monthly wind speed duri...It is now well known that coastal urban local climate has been showing changing pattern due to global climate change. This communication attempts to explore fluctuating pattern of urban average monthly wind speed during past 50 years (1961-2010). It shows peculiar results taking Karachi (24?53'N, 67?00'E), a coastal mega-city of Pakistan, as a case study. Mann-Kendall trend test shows that March, April and October and both summer and winter seasons show positive trends for the average monthly wind speed during the whole study period (1961-2010). For the earlier 25 years data, it has been found that January, March, May, August, November and December and annual wind speed data have shown the negative trends. Only summer season has shown the positive trend for the wind speed. Similarly, for the most recent 25 years data it has been found that January, February, March, April, May, June, October, November and December and annual and both summer and winter wind speed data have shown the positive trends showing some degree of change in wind speed pattern. Probabilistic analysis reveals that average monthly wind speed data sets follow lognormal, logistic, largest extreme value, and Weibull (two-and three-parameters) probability distributions. Change point analysis has also confirmed the change in the pattern of observed average monthly wind speed data near 1992. The analysis performed reveals the effect of global warming on the local urban wind speed which appears to be temporal non-stationary.展开更多
How various peoples crossed geographical barriers,were affected by climate change and human-made technologies comprise some of the most interesting quandaries in the history of cultures.This paper considers the Hu lin...How various peoples crossed geographical barriers,were affected by climate change and human-made technologies comprise some of the most interesting quandaries in the history of cultures.This paper considers the Hu line,which is a major boundary between population centres and different environments in China.The boundary became evident approximately 11,400 years ago;however,evidence suggests that people crossed through at 5200,3800,and 2800 cal a BP,facilitating the increases of the trans-Eurasian exchange.The timings of the crossings correspond to the weakening of the East Asian summer monsoon that triggers seesaw changes of precipitation in western and eastern China.This analysis demonstrates that climate change on a millennial-to-centennial scale can have a profound influence on population distribution with long-term consequences.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11274219)the Science and Technology Planning Project of Guangdong Province of China(Grant No.180917124960522)the Program for Promotion of Science at Universities in Guangdong Province of China(Grant No.2018KTSCX062)。
文摘Recently,the quantitative rescattering model(QRS)for nonsequential double ionization(NSDI)is modified by taking into account the potential change(PC)due to the presence of electric field at the time of recollision.Using the improved QRS model,we simulate the longitudinal momentum distributions of doubly charged ions He2+by projecting the correlated two-electron momentum distributions for NSDI of He onto the main diagonal.The obtained results are compared directly with the experimental data at different intensities.It is found that when the PC is considered,the width of momentum distributions reduces and the agreement between theory and experiment is improved.
文摘It is now well known that coastal urban local climate has been showing changing pattern due to global climate change. This communication attempts to explore fluctuating pattern of urban average monthly wind speed during past 50 years (1961-2010). It shows peculiar results taking Karachi (24?53'N, 67?00'E), a coastal mega-city of Pakistan, as a case study. Mann-Kendall trend test shows that March, April and October and both summer and winter seasons show positive trends for the average monthly wind speed during the whole study period (1961-2010). For the earlier 25 years data, it has been found that January, March, May, August, November and December and annual wind speed data have shown the negative trends. Only summer season has shown the positive trend for the wind speed. Similarly, for the most recent 25 years data it has been found that January, February, March, April, May, June, October, November and December and annual and both summer and winter wind speed data have shown the positive trends showing some degree of change in wind speed pattern. Probabilistic analysis reveals that average monthly wind speed data sets follow lognormal, logistic, largest extreme value, and Weibull (two-and three-parameters) probability distributions. Change point analysis has also confirmed the change in the pattern of observed average monthly wind speed data near 1992. The analysis performed reveals the effect of global warming on the local urban wind speed which appears to be temporal non-stationary.
基金supported by the National Natural Science Foundation of China(41888101,41830322)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB26000000)+1 种基金the National Key Research&Development Program of China(2020YFC1521605)Youth Innovation Promotion Association of Chinese Academy of Sciences。
文摘How various peoples crossed geographical barriers,were affected by climate change and human-made technologies comprise some of the most interesting quandaries in the history of cultures.This paper considers the Hu line,which is a major boundary between population centres and different environments in China.The boundary became evident approximately 11,400 years ago;however,evidence suggests that people crossed through at 5200,3800,and 2800 cal a BP,facilitating the increases of the trans-Eurasian exchange.The timings of the crossings correspond to the weakening of the East Asian summer monsoon that triggers seesaw changes of precipitation in western and eastern China.This analysis demonstrates that climate change on a millennial-to-centennial scale can have a profound influence on population distribution with long-term consequences.
