A new phasing procedure has been proposed for dealing with single isomorphous replacement （SIR） x-ray diffraction data. The procedure combines SOLVE/RESOLVE with the dual-space fragment extension involving OASIS. Tw...A new phasing procedure has been proposed for dealing with single isomorphous replacement （SIR） x-ray diffraction data. The procedure combines SOLVE/RESOLVE with the dual-space fragment extension involving OASIS. Two sets of SIR data at 0.28 nm resolution taken from the protein （R）-phycoerythrin （PDB code： 1LIA） were used in the test. For one of the two SIR data sets, a default run of SOLVE/RESOLVE based on the heavy-atom substructure found by SHLEXD led automatically to an interpretable electron density map. OASIS could not effectively improve the result. For the other set of SIR data, SOLVE/RESOLVE resulted in a fragmented model consisting of 454 of the total 668 residues, in which only 29 residues were docked into the sequence. Based on this model, 7 iteration cycles of OASIS-DM- RESOLVE （build only） yielded automatically a model of 547 residues with 133 residues docked into the sequence. The overall-averaged phase error decreased considerably and the quality of electron density map was improved significantly. Two more cycles of iterative OASIS-DM-RESOLVE were carried out, in which the output phases and figures of merit from DM were merged with that from the original run of SOLVE/RESOLVE before they were passed onto RESOLVE （build only）. This led automatically to a model containing 452 residues with 173 docked into the sequence. The resultant electron density map is manually traceable. It is concluded that when results of SOLVE/RESOLVE are not sufficiently satisfactory, the combination of SOLVE/RESOLVE and OASIS-DM-RESOLVE （build only） may significantly improve them.展开更多
The quaternion approach to solve the coupled nonlinear Schrodinger equations （CNSEs） in fibers is proposed, converting the CNSEs to a single variable equation by using a conception of eigen-quaternion of coupled qua...The quaternion approach to solve the coupled nonlinear Schrodinger equations （CNSEs） in fibers is proposed, converting the CNSEs to a single variable equation by using a conception of eigen-quaternion of coupled quater- nion. The crosstalk of quarter-phase-shift-key signals caused by fiber nonlinearity in polarization multiplexing systems with 100 Cbps bit-rate is investigated and simulated. The results demonstrate that the crosstalk is like a rotated ghosting of input constellation. For the 50 km conventional fiber link, when the total power is less than 4roW, the crosstalk effect can be neglected; when the power is larger than 20roW, the crosstalk is very obvious. In addition, the crosstalk can not be detected according to the output eye diagram and state of polarization in Poincare sphere in the trunk fiber, making it difficult for the monitoring of optical trunk link.展开更多
FOR a long time, agricultural development and food production in Africa have been severely constrained due to various reasons. These include insufficient agricultural infrastructure, lack of breeding capacity, and a p...FOR a long time, agricultural development and food production in Africa have been severely constrained due to various reasons. These include insufficient agricultural infrastructure, lack of breeding capacity, and a poor level of agricultural mechanization. In addition, in recent years, due to various factors such as natural disasters and epidemics, the food security situation in many African countries is not optimistic.展开更多
The new round of Sino-US high-level economic and trade consultations has been concluded.This is the 13th round of negotiations since the wide acceleration of economic and trade frictions between China and US.
English education in China has its problems due to its history and teaching environment,such as deficiency of communication purpose,insufficiency of teaching on oral expression and so on.Consequently,to solve the prob...English education in China has its problems due to its history and teaching environment,such as deficiency of communication purpose,insufficiency of teaching on oral expression and so on.Consequently,to solve the problems of English teaching in China seems necessary.Therefore,the solutions as the changes of policy,updated teaching methods,improvement of teacher’s skills on teaching and diverse ways of teaching should be pointed out.展开更多
Maths is important in our life, especially fraction, and it is also fun.But can you solve the following fraction problems? Try, please.(1) Adam needs to drive a distance of 372 miles to New York to attend his friend s...Maths is important in our life, especially fraction, and it is also fun.But can you solve the following fraction problems? Try, please.(1) Adam needs to drive a distance of 372 miles to New York to attend his friend s birthday party. He stops over to grab a quick bite after he covers one-third the total distance.展开更多
Some of the primary school students can solve percentage problems written in Chinese but fail to solve them written in English. Why?Is bilingual maths more diffi cult than Chinese maths? The answer is 'No'.The...Some of the primary school students can solve percentage problems written in Chinese but fail to solve them written in English. Why?Is bilingual maths more diffi cult than Chinese maths? The answer is 'No'.The main reason is that they might not know well about the formula of percentage and the English expressions of percentage.展开更多
It has long been assumed that no solution exists. For decades, Chinese and foreign experts in Beijing have wrestled over evermore elaborate micro-creditschemes with the sole aim of raising the Chinese peasant out of p...It has long been assumed that no solution exists. For decades, Chinese and foreign experts in Beijing have wrestled over evermore elaborate micro-creditschemes with the sole aim of raising the Chinese peasant out of poverty, yet the peasants are too poor to present any collateral to get the loan.展开更多
As NATO forces continue bombing Libya and no solution to the conflict is in sight,Zhang Zhongxiang,Deputy Director of the Department of the West Asian and African Studies at the Shanghai Institutes for International S...As NATO forces continue bombing Libya and no solution to the conflict is in sight,Zhang Zhongxiang,Deputy Director of the Department of the West Asian and African Studies at the Shanghai Institutes for International Studies,says African countries should be left to resolve their own conflicts via the African Union and Western intervention in Libya only exacerbates an already volatile situation. His thoughts are as follows:展开更多
Education has always been a deeply emotional topic for Chinese parents. A recent proposal calling for postponing boys＇ school starting age by one year has led to even more heated discussions on the topic.
文摘A new phasing procedure has been proposed for dealing with single isomorphous replacement （SIR） x-ray diffraction data. The procedure combines SOLVE/RESOLVE with the dual-space fragment extension involving OASIS. Two sets of SIR data at 0.28 nm resolution taken from the protein （R）-phycoerythrin （PDB code： 1LIA） were used in the test. For one of the two SIR data sets, a default run of SOLVE/RESOLVE based on the heavy-atom substructure found by SHLEXD led automatically to an interpretable electron density map. OASIS could not effectively improve the result. For the other set of SIR data, SOLVE/RESOLVE resulted in a fragmented model consisting of 454 of the total 668 residues, in which only 29 residues were docked into the sequence. Based on this model, 7 iteration cycles of OASIS-DM- RESOLVE （build only） yielded automatically a model of 547 residues with 133 residues docked into the sequence. The overall-averaged phase error decreased considerably and the quality of electron density map was improved significantly. Two more cycles of iterative OASIS-DM-RESOLVE were carried out, in which the output phases and figures of merit from DM were merged with that from the original run of SOLVE/RESOLVE before they were passed onto RESOLVE （build only）. This led automatically to a model containing 452 residues with 173 docked into the sequence. The resultant electron density map is manually traceable. It is concluded that when results of SOLVE/RESOLVE are not sufficiently satisfactory, the combination of SOLVE/RESOLVE and OASIS-DM-RESOLVE （build only） may significantly improve them.
基金Supported by the National Natural Science Foundation of China under Grant No 61275075the Beijing Natural Science Foundation under Grant Nos 4132035 and 4144080
文摘The quaternion approach to solve the coupled nonlinear Schrodinger equations （CNSEs） in fibers is proposed, converting the CNSEs to a single variable equation by using a conception of eigen-quaternion of coupled quater- nion. The crosstalk of quarter-phase-shift-key signals caused by fiber nonlinearity in polarization multiplexing systems with 100 Cbps bit-rate is investigated and simulated. The results demonstrate that the crosstalk is like a rotated ghosting of input constellation. For the 50 km conventional fiber link, when the total power is less than 4roW, the crosstalk effect can be neglected; when the power is larger than 20roW, the crosstalk is very obvious. In addition, the crosstalk can not be detected according to the output eye diagram and state of polarization in Poincare sphere in the trunk fiber, making it difficult for the monitoring of optical trunk link.
文摘FOR a long time, agricultural development and food production in Africa have been severely constrained due to various reasons. These include insufficient agricultural infrastructure, lack of breeding capacity, and a poor level of agricultural mechanization. In addition, in recent years, due to various factors such as natural disasters and epidemics, the food security situation in many African countries is not optimistic.
文摘The new round of Sino-US high-level economic and trade consultations has been concluded.This is the 13th round of negotiations since the wide acceleration of economic and trade frictions between China and US.
文摘English education in China has its problems due to its history and teaching environment,such as deficiency of communication purpose,insufficiency of teaching on oral expression and so on.Consequently,to solve the problems of English teaching in China seems necessary.Therefore,the solutions as the changes of policy,updated teaching methods,improvement of teacher’s skills on teaching and diverse ways of teaching should be pointed out.
文摘Maths is important in our life, especially fraction, and it is also fun.But can you solve the following fraction problems? Try, please.(1) Adam needs to drive a distance of 372 miles to New York to attend his friend s birthday party. He stops over to grab a quick bite after he covers one-third the total distance.
文摘Some of the primary school students can solve percentage problems written in Chinese but fail to solve them written in English. Why?Is bilingual maths more diffi cult than Chinese maths? The answer is 'No'.The main reason is that they might not know well about the formula of percentage and the English expressions of percentage.
文摘It has long been assumed that no solution exists. For decades, Chinese and foreign experts in Beijing have wrestled over evermore elaborate micro-creditschemes with the sole aim of raising the Chinese peasant out of poverty, yet the peasants are too poor to present any collateral to get the loan.
文摘As NATO forces continue bombing Libya and no solution to the conflict is in sight,Zhang Zhongxiang,Deputy Director of the Department of the West Asian and African Studies at the Shanghai Institutes for International Studies,says African countries should be left to resolve their own conflicts via the African Union and Western intervention in Libya only exacerbates an already volatile situation. His thoughts are as follows:
文摘Education has always been a deeply emotional topic for Chinese parents. A recent proposal calling for postponing boys＇ school starting age by one year has led to even more heated discussions on the topic.
