To better understand the relationship between lightning activity and nitrogen oxides （NOx） in the troposphere and to estimate lightning-produced NOx （LNOx） production in China more precisely, spatial and temporal ...To better understand the relationship between lightning activity and nitrogen oxides （NOx） in the troposphere and to estimate lightning-produced NOx （LNOx） production in China more precisely, spatial and temporal distributions of vertical column densities of tropospheric nitrogen dioxide （NO2 VCDs） and lightning activity were analyzed using satellite measure- ments. The results showed that the spatial distribution of lightning activity is greater in the east than in the west of China, as with NO2 VCDs. However, the seasonal and annual variation between lightning and NO2 density show different trends in the east and west. The central Tibetan Plateau is sparsely populated without modem industry, and NO2 VCDs across the plateau are barely affected by anthropogenic sources. The plateau is an ideal area to study LNOx. By analyzing 15 years of satellite data from that region, it was found that lightning density is in strong agreement with annual, spatial and seasonal variations of NO2 VCDs, with a correlation coefficient of 0.79 from the linear fit. Combining Beirle＇s method and the linear fit equation, LNOx production in the Chinese interior was determined to be 0.07 （0.02-0.27） TgN yr-1 for 1997-2012, within the range of 0.016-0.384 TgN yr-1 from previous estimates.展开更多
Convective storms and lightning are among the most important weather phenomena that are challenging to forecast.In this study,a novel multi-task learning(MTL)encoder-decoder U-net neural network was developed to forec...Convective storms and lightning are among the most important weather phenomena that are challenging to forecast.In this study,a novel multi-task learning(MTL)encoder-decoder U-net neural network was developed to forecast convective storms and lightning with lead times for up to 90 min,using GOES-16 geostationary satellite infrared brightness temperatures(IRBTs),lightning flashes from Geostationary Lightning Mapper(GLM),and vertically integrated liquid(VIL)from Next Generation Weather Radar(NEXRAD).To cope with the heavily skewed distribution of lightning data,a spatiotemporal exponent-weighted loss function and log-transformed lightning normalization approach were developed.The effects of MTL,single-task learning(STL),and IRBTs as auxiliary input features on convection and lightning nowcasting were investigated.The results showed that normalizing the heavily skew-distributed lightning data along with a log-transformation dramatically outperforms the min-max normalization method for nowcasting an intense lightning event.The MTL model significantly outperformed the STL model for both lightning nowcasting and VIL nowcasting,particularly for intense lightning events.The MTL also helped delay the lightning forecast performance decay with the lead times.Furthermore,incorporating satellite IRBTs as auxiliary input features substantially improved lightning nowcasting,but produced little difference in VIL forecasting.Finally,the MTL model performed better for forecasting both lightning and the VIL of organized convective storms than for isolated cells.展开更多
Lightning-generated nitrogen oxides(LNO_(x))have a major influence on the atmosphere and global climate change.Therefore,it is of great importance to obtain a more accurate estimation of LNO_(x).The aim of this study ...Lightning-generated nitrogen oxides(LNO_(x))have a major influence on the atmosphere and global climate change.Therefore,it is of great importance to obtain a more accurate estimation of LNO_(x).The aim of this study is to provide a reference for the accurate estimation of the total LNO_(x) in the mainland of China based on cloud-to-ground lightning(CG)location data from 2014 to 2018.The energy of each CG flash was based on the number of return strokes per CG flash,the peak current of each return stroke,and the assumed CG breakdown voltage.The energy of intracloud lightning(IC)was based on the estimated frequencies of IC and the assumed energy of each IC flash.Combining the energy of lightning and the number of nitric oxide(NO)molecules produced by unit energy(ρno),the total LNO_(x) production in the mainland of China was determined.The LNO_(x) in the mainland of China estimated in this study is in the range(0.157-0.321)×10^(9) kg per year[Tg(N)yr-1],which is on the high end of other scholars’works.Negative cloud-to-ground lightning(NCG)flashes produce the most moles of NO_(x),while positive cloud-to-ground lightning(PCG)flashes produce the least total moles of NO_(x).The breakdown voltage of PCG is greater than that of IC or NCG,while the latter has a greater output of LNO_(x).展开更多
OBJECTIVE To evaluate the p73 gene G4C14-to-A4T14 double nucleotide polymorphism with both increased gastric cancer(GC) risk and different histological subtypes of GC in a northwestern Chinese population. METHODS Geno...OBJECTIVE To evaluate the p73 gene G4C14-to-A4T14 double nucleotide polymorphism with both increased gastric cancer(GC) risk and different histological subtypes of GC in a northwestern Chinese population. METHODS Genotyping of the polymorphism of the p73 gene was conducted with PCR-CTPP. RESULTS All 385 GC patients including 305 diffuse-type and 80 intestinal-type cases and 412 healthy controls were investigated.The frequencies of p73 AT/AT,AT/GC,and GC/GC genotypes were 28.1%,47.1%,and 24.8% in the controls,and were 22.0%,45.0%,and 33.0% in GC cases respectively;the GC/GC homozygote frequency was higher in GC cases,mainly in diffuse type compared to the controls with OR=1.71(1.16～2.51) and 1.87 (95%CI,1.24～2.81) respectively.The results showed that carriers of the p73 G4A GC/GC homozygote had a 1.71-time higher risk of GC,especially of the diffuse-type GC compared to the controls. The carriers of the AT/GC heterozygote also had a slightly increased risk of GC cancer,mainly on intestinal-type GC.This is the first report that the p73 G4A double-nucleotide polymorphism is associated with an increased risk of diffuse-type gastric cancer. CONCLUTION The p73 G4A GC/GC genotype is associated with an increased risk of gastric cancer,especially of the GC diffuse-type.展开更多
The listening teaching to students should not be a passive acceptance process, but the use ot knowledge and non-knowledge of the language of all language information analysis processing and reconstruction of the infor...The listening teaching to students should not be a passive acceptance process, but the use ot knowledge and non-knowledge of the language of all language information analysis processing and reconstruction of the information process. The paper shows the information that listeners accept relates to a variety of factors, which is a complex psychological process and proactive thinking process. However, due to the weak language basics, unhealthy hearing psychological and incorrect hearing and learning methods seriously affect and hinder the improvement of the hearing ability of college students. Therefore, how to improve the English listening comprehension become the majority of English learners continue to explore the issues. To the right way to learn in a short period of time to improve the level of English listening, it is necessary to grasp the scientific and reasonable learning strategy.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.91537209,91644224)the National Key Basic Research Program of China(Grant No.2014CB441403)the Basic Research Fund of the Chinese Academy of Meteorological Sciences(Grant No.2016Z002)
文摘To better understand the relationship between lightning activity and nitrogen oxides （NOx） in the troposphere and to estimate lightning-produced NOx （LNOx） production in China more precisely, spatial and temporal distributions of vertical column densities of tropospheric nitrogen dioxide （NO2 VCDs） and lightning activity were analyzed using satellite measure- ments. The results showed that the spatial distribution of lightning activity is greater in the east than in the west of China, as with NO2 VCDs. However, the seasonal and annual variation between lightning and NO2 density show different trends in the east and west. The central Tibetan Plateau is sparsely populated without modem industry, and NO2 VCDs across the plateau are barely affected by anthropogenic sources. The plateau is an ideal area to study LNOx. By analyzing 15 years of satellite data from that region, it was found that lightning density is in strong agreement with annual, spatial and seasonal variations of NO2 VCDs, with a correlation coefficient of 0.79 from the linear fit. Combining Beirle＇s method and the linear fit equation, LNOx production in the Chinese interior was determined to be 0.07 （0.02-0.27） TgN yr-1 for 1997-2012, within the range of 0.016-0.384 TgN yr-1 from previous estimates.
基金supported by the Science and Technology Grant No.520120210003,Jibei Electric Power Company of the State Grid Corporation of China。
文摘Convective storms and lightning are among the most important weather phenomena that are challenging to forecast.In this study,a novel multi-task learning(MTL)encoder-decoder U-net neural network was developed to forecast convective storms and lightning with lead times for up to 90 min,using GOES-16 geostationary satellite infrared brightness temperatures(IRBTs),lightning flashes from Geostationary Lightning Mapper(GLM),and vertically integrated liquid(VIL)from Next Generation Weather Radar(NEXRAD).To cope with the heavily skewed distribution of lightning data,a spatiotemporal exponent-weighted loss function and log-transformed lightning normalization approach were developed.The effects of MTL,single-task learning(STL),and IRBTs as auxiliary input features on convection and lightning nowcasting were investigated.The results showed that normalizing the heavily skew-distributed lightning data along with a log-transformation dramatically outperforms the min-max normalization method for nowcasting an intense lightning event.The MTL model significantly outperformed the STL model for both lightning nowcasting and VIL nowcasting,particularly for intense lightning events.The MTL also helped delay the lightning forecast performance decay with the lead times.Furthermore,incorporating satellite IRBTs as auxiliary input features substantially improved lightning nowcasting,but produced little difference in VIL forecasting.Finally,the MTL model performed better for forecasting both lightning and the VIL of organized convective storms than for isolated cells.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91537209 and 91644224)
文摘Lightning-generated nitrogen oxides(LNO_(x))have a major influence on the atmosphere and global climate change.Therefore,it is of great importance to obtain a more accurate estimation of LNO_(x).The aim of this study is to provide a reference for the accurate estimation of the total LNO_(x) in the mainland of China based on cloud-to-ground lightning(CG)location data from 2014 to 2018.The energy of each CG flash was based on the number of return strokes per CG flash,the peak current of each return stroke,and the assumed CG breakdown voltage.The energy of intracloud lightning(IC)was based on the estimated frequencies of IC and the assumed energy of each IC flash.Combining the energy of lightning and the number of nitric oxide(NO)molecules produced by unit energy(ρno),the total LNO_(x) production in the mainland of China was determined.The LNO_(x) in the mainland of China estimated in this study is in the range(0.157-0.321)×10^(9) kg per year[Tg(N)yr-1],which is on the high end of other scholars’works.Negative cloud-to-ground lightning(NCG)flashes produce the most moles of NO_(x),while positive cloud-to-ground lightning(PCG)flashes produce the least total moles of NO_(x).The breakdown voltage of PCG is greater than that of IC or NCG,while the latter has a greater output of LNO_(x).
基金a grant from Natural Science Foundation of Gansu Province,China(No.3ZS041-A25-013)
文摘OBJECTIVE To evaluate the p73 gene G4C14-to-A4T14 double nucleotide polymorphism with both increased gastric cancer(GC) risk and different histological subtypes of GC in a northwestern Chinese population. METHODS Genotyping of the polymorphism of the p73 gene was conducted with PCR-CTPP. RESULTS All 385 GC patients including 305 diffuse-type and 80 intestinal-type cases and 412 healthy controls were investigated.The frequencies of p73 AT/AT,AT/GC,and GC/GC genotypes were 28.1%,47.1%,and 24.8% in the controls,and were 22.0%,45.0%,and 33.0% in GC cases respectively;the GC/GC homozygote frequency was higher in GC cases,mainly in diffuse type compared to the controls with OR=1.71(1.16～2.51) and 1.87 (95%CI,1.24～2.81) respectively.The results showed that carriers of the p73 G4A GC/GC homozygote had a 1.71-time higher risk of GC,especially of the diffuse-type GC compared to the controls. The carriers of the AT/GC heterozygote also had a slightly increased risk of GC cancer,mainly on intestinal-type GC.This is the first report that the p73 G4A double-nucleotide polymorphism is associated with an increased risk of diffuse-type gastric cancer. CONCLUTION The p73 G4A GC/GC genotype is associated with an increased risk of gastric cancer,especially of the GC diffuse-type.
文摘The listening teaching to students should not be a passive acceptance process, but the use ot knowledge and non-knowledge of the language of all language information analysis processing and reconstruction of the information process. The paper shows the information that listeners accept relates to a variety of factors, which is a complex psychological process and proactive thinking process. However, due to the weak language basics, unhealthy hearing psychological and incorrect hearing and learning methods seriously affect and hinder the improvement of the hearing ability of college students. Therefore, how to improve the English listening comprehension become the majority of English learners continue to explore the issues. To the right way to learn in a short period of time to improve the level of English listening, it is necessary to grasp the scientific and reasonable learning strategy.
