Free energy calculations may provide vital information for studying various chemical and biological processes.Quantum mechanical methods are required to accurately describe interaction energies,but their computations ...Free energy calculations may provide vital information for studying various chemical and biological processes.Quantum mechanical methods are required to accurately describe interaction energies,but their computations are often too demanding for conformational sampling.As a remedy,level correction schemes that allow calculating high level free energies based on conformations from lower level simulations have been developed.Here,we present a variation of a Monte Carlo(MC)resampling approach in relation to the weighted histogram analysis method(WHAM).We show that our scheme can generate free energy surfaces that can practically converge to the exact one with sufficient sampling,and that it treats cases with insufficient sampling in a more stable manner than the conventional WHAM-based level correction scheme.It can also provide a guide for checking the uncertainty of the levelcorrected surface and a well-defined criterion for deciding the extent of smoothing on the free energy surface for its visual improvement.We demonstrate these aspects by obtaining the free energy maps associated with the alanine dipeptide and proton transfer network of the KillerRed protein in explicit water,and exemplify that the MC resampled WHAM scheme can be a practical tool for producing free energy surfaces of realistic systems.展开更多
Introduction Errors are unavoidable in language learning, however, to a great extent, teachers in most middle schools in China regard errors as undesirable, a sign of failure in language learning. Most middle schools ...Introduction Errors are unavoidable in language learning, however, to a great extent, teachers in most middle schools in China regard errors as undesirable, a sign of failure in language learning. Most middle schools are still using the grammar-translation method which aims at encouraging students to read scientific works and enjoy literary works. The other goals of this method are to gain a greater understanding of the first language and to improve the students’ ability to cope with difficult subjects and materials, i.e. to develop the students’ minds. The practical purpose of using this method is to help learners pass the annual entrance examination. "To achieve these goals, the students must first learn grammar and vocabulary,... Grammar is taught deductively by means of long and elaborate explanations... students learn the rules of the language rather than its use." (Tang Lixing, 1983:11-12)展开更多
Changes in barometric pressure can affect the micro-dynamic state of groundwater level.The groundwater level data carry a lot of important information of tectonic activity and earthquakes.It is very significant to eli...Changes in barometric pressure can affect the micro-dynamic state of groundwater level.The groundwater level data carry a lot of important information of tectonic activity and earthquakes.It is very significant to eliminate the barometric pressure effects from the groundwater level data in order to recognize seismic anomalies effectively.With the analysis of the main influential constituents of barometric pressure and their changes,we can have a better understanding of the changes of the aquifer medium,which can provide useful information for earthquake prediction.Taking the May 12,2008 Wenchuan earthquake as an example,this paper deals with the influence of barometric pressure on groundwater level based on observational data from Nanxi,Qionglai and Chaohu wells.The methods of the linear regression and the deconvolution regression were employed to remove the barometric pressure from the groundwater level data.The harmonic analysis and the spectral analysis were used to recognize the main influential waves of barometric pressure effect.A comparison was conducted on the main influential waves before and after the earthquake.The results showed that the main influential waves of barometric pressure effect changed and the amplitudes of all constituents also changed.This phenomenon may result from the characteristics of the influential constituents of pressure,or from the changes of the aquifer medium,which were caused by the earthquake.展开更多
基金supported by the Mid-career Researcher Program(No.2017R1A2B3004946)through National Research Foundationfunded by Ministry of Science and ICT of Korea.
文摘Free energy calculations may provide vital information for studying various chemical and biological processes.Quantum mechanical methods are required to accurately describe interaction energies,but their computations are often too demanding for conformational sampling.As a remedy,level correction schemes that allow calculating high level free energies based on conformations from lower level simulations have been developed.Here,we present a variation of a Monte Carlo(MC)resampling approach in relation to the weighted histogram analysis method(WHAM).We show that our scheme can generate free energy surfaces that can practically converge to the exact one with sufficient sampling,and that it treats cases with insufficient sampling in a more stable manner than the conventional WHAM-based level correction scheme.It can also provide a guide for checking the uncertainty of the levelcorrected surface and a well-defined criterion for deciding the extent of smoothing on the free energy surface for its visual improvement.We demonstrate these aspects by obtaining the free energy maps associated with the alanine dipeptide and proton transfer network of the KillerRed protein in explicit water,and exemplify that the MC resampled WHAM scheme can be a practical tool for producing free energy surfaces of realistic systems.
文摘Introduction Errors are unavoidable in language learning, however, to a great extent, teachers in most middle schools in China regard errors as undesirable, a sign of failure in language learning. Most middle schools are still using the grammar-translation method which aims at encouraging students to read scientific works and enjoy literary works. The other goals of this method are to gain a greater understanding of the first language and to improve the students’ ability to cope with difficult subjects and materials, i.e. to develop the students’ minds. The practical purpose of using this method is to help learners pass the annual entrance examination. "To achieve these goals, the students must first learn grammar and vocabulary,... Grammar is taught deductively by means of long and elaborate explanations... students learn the rules of the language rather than its use." (Tang Lixing, 1983:11-12)
基金supported by the National Natural Science Foundation of China (Grant No. 40930637)Special Project for Earthquake Science(Grant No. 200808079)Subject Foundation of Ministry of Education for Doctor Candidates in Universities (Grant No. 20100022110001)
文摘Changes in barometric pressure can affect the micro-dynamic state of groundwater level.The groundwater level data carry a lot of important information of tectonic activity and earthquakes.It is very significant to eliminate the barometric pressure effects from the groundwater level data in order to recognize seismic anomalies effectively.With the analysis of the main influential constituents of barometric pressure and their changes,we can have a better understanding of the changes of the aquifer medium,which can provide useful information for earthquake prediction.Taking the May 12,2008 Wenchuan earthquake as an example,this paper deals with the influence of barometric pressure on groundwater level based on observational data from Nanxi,Qionglai and Chaohu wells.The methods of the linear regression and the deconvolution regression were employed to remove the barometric pressure from the groundwater level data.The harmonic analysis and the spectral analysis were used to recognize the main influential waves of barometric pressure effect.A comparison was conducted on the main influential waves before and after the earthquake.The results showed that the main influential waves of barometric pressure effect changed and the amplitudes of all constituents also changed.This phenomenon may result from the characteristics of the influential constituents of pressure,or from the changes of the aquifer medium,which were caused by the earthquake.
