Mêdog and Nagqu are two typical regions of the Tibetan Plateau with different geographical locations and climate regimes.These differences may lead to discrepancies in the raindrop size distributions(DSDs)and pre...Mêdog and Nagqu are two typical regions of the Tibetan Plateau with different geographical locations and climate regimes.These differences may lead to discrepancies in the raindrop size distributions(DSDs)and precipitation microphysical processes between the two regions.This paper investigates discrepancies in the DSDs using disdrometer data obtained during the rainy season in Mêdog and Nagqu.The DSD characteristics are studied under five different rainfall rate categories and two precipitation types(stratiform and convective).For the total datasets,the number concentrations of drops with diameters D>0.6(D<0.6)mm are higher(lower)in Nagqu than in Mêdog.The fitted normalized gamma distributions of the averaged DSDs for the five rainfall rate categories show that Nagqu has a larger(lower)mass-weighted mean diameter D_(m)(normalized intercept parameter,lgNw)than Mêdog does.The difference in D_(m)between Nagqu and Mêdog increases with the rainfall rate.Convective clusters in Nagqu could be identified as continental-like,while convective precipitation in Mêdog could be classified as maritime-like.The relationships between the shape factorμand slope parameterΛof the gamma distribution model,the radar reflectivity Z,and the rainfall rate R are also derived.Furthermore,the possible causative mechanism for the notable DSD variation between the two regions during the rainy season is illustrated using reanalysis data and automated weather station observations.Cold rain processes are mainly responsible for the lower concentrations of larger drops observed in Nagqu,whereas warm rain prevails in Mêdog,producing abundant small drops.展开更多
A medium-carbon steel was processed through different warm rolling techniques,and the microstructural features with bimodal grain size distribution were found to be different.The combination of strength and ductility ...A medium-carbon steel was processed through different warm rolling techniques,and the microstructural features with bimodal grain size distribution were found to be different.The combination of strength and ductility was ameliorated in the steel processed through warm rolling characterized by biaxial reduction.The enhanced strength is attributed to the densely distributed fine intragranular cementite particles and the small grain size in the coarse grain regions.The enhanced uniform elongation is due to the improved work hardening behavior at the large-strain stage.This work hardening behavior is predominantly ascribed to the finely dispersed intragranular particles.The relatively small grain size with nearly equiaxed shape in the coarse grain regions helps stabilize the uniform deformation to a large strain.展开更多
Anthropogenic disturbances are causing significant impacts on plant distribution worldwide,and many of these effects are driven by changes in the recruitment patterns of plant species.Global warming and land-use chang...Anthropogenic disturbances are causing significant impacts on plant distribution worldwide,and many of these effects are driven by changes in the recruitment patterns of plant species.Global warming and land-use change are two major disturbances leading to changes in germination strategies by changing both soil temperature regimes and light quality reaching the seeds due to soil disturbance.Investigating the range,overlap,and redundancy of niche germination of co-occurring plant species allows us to understand whether endemic species are threatened either by native non-endemic or by alien species,especially in an ecosystem of restricted distribution such as the campo rupestre.Employing a systematic review,this study aimed to evaluate the effect of temperature increase and seed burial on the germination of endemic and non-endemic species in the campo rupestre in Brazil.We performed a metaanalysis using increased temperature and darkness as proxies for the impact of disturbance on germination patterns.In this context,we hypothesized that:increased temperature and darkness negatively influence the germination of native species and positively influence the germination of alien species in the campo rupestre.Specifically,we expect the negative effect to be more pronounced in endemic species than in native non-endemic species.Moreover,we intend to describe the role of seed size in the germination of native and alien species from campo rupestre in the context of increased temperature and darkness.Our analysis showed that increased temperature influenced the germination of alien species by ca.55%,while it did not influence the germination of endemic or native non-endemic species.Furthermore,the germination of alien species under higher temperatures was promoted by increasing seed size.Darkness negatively influenced seed germination of native species,independent of their distribution.Moreover,under darkness conditions,the germination of endemic seeds decreased with seed size.Through their direct effects on germination strategies,we conclude that warming temperatures and land-use change can lead to a long-term displacement of endemic species by native non-endemic and alien species in campo rupestre,thus compromising ecosystem services and conservation of these fragile physiognomies in the near future.展开更多
基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0105)the National Natural Science Foundation of China(Grant No.41775036).
文摘Mêdog and Nagqu are two typical regions of the Tibetan Plateau with different geographical locations and climate regimes.These differences may lead to discrepancies in the raindrop size distributions(DSDs)and precipitation microphysical processes between the two regions.This paper investigates discrepancies in the DSDs using disdrometer data obtained during the rainy season in Mêdog and Nagqu.The DSD characteristics are studied under five different rainfall rate categories and two precipitation types(stratiform and convective).For the total datasets,the number concentrations of drops with diameters D>0.6(D<0.6)mm are higher(lower)in Nagqu than in Mêdog.The fitted normalized gamma distributions of the averaged DSDs for the five rainfall rate categories show that Nagqu has a larger(lower)mass-weighted mean diameter D_(m)(normalized intercept parameter,lgNw)than Mêdog does.The difference in D_(m)between Nagqu and Mêdog increases with the rainfall rate.Convective clusters in Nagqu could be identified as continental-like,while convective precipitation in Mêdog could be classified as maritime-like.The relationships between the shape factorμand slope parameterΛof the gamma distribution model,the radar reflectivity Z,and the rainfall rate R are also derived.Furthermore,the possible causative mechanism for the notable DSD variation between the two regions during the rainy season is illustrated using reanalysis data and automated weather station observations.Cold rain processes are mainly responsible for the lower concentrations of larger drops observed in Nagqu,whereas warm rain prevails in Mêdog,producing abundant small drops.
基金sponsored by National Natural Science Foundation of China(51304061,51474092)Natural Science Foundation of Hebei Province of China(E2014209161)Scientific Research Project for Universities in Hebei Province of China(QN20131074)
文摘A medium-carbon steel was processed through different warm rolling techniques,and the microstructural features with bimodal grain size distribution were found to be different.The combination of strength and ductility was ameliorated in the steel processed through warm rolling characterized by biaxial reduction.The enhanced strength is attributed to the densely distributed fine intragranular cementite particles and the small grain size in the coarse grain regions.The enhanced uniform elongation is due to the improved work hardening behavior at the large-strain stage.This work hardening behavior is predominantly ascribed to the finely dispersed intragranular particles.The relatively small grain size with nearly equiaxed shape in the coarse grain regions helps stabilize the uniform deformation to a large strain.
基金financial support from CNPq/Peld CRSC,Fapemig,CAPES,Anglo American,and Vale.
文摘Anthropogenic disturbances are causing significant impacts on plant distribution worldwide,and many of these effects are driven by changes in the recruitment patterns of plant species.Global warming and land-use change are two major disturbances leading to changes in germination strategies by changing both soil temperature regimes and light quality reaching the seeds due to soil disturbance.Investigating the range,overlap,and redundancy of niche germination of co-occurring plant species allows us to understand whether endemic species are threatened either by native non-endemic or by alien species,especially in an ecosystem of restricted distribution such as the campo rupestre.Employing a systematic review,this study aimed to evaluate the effect of temperature increase and seed burial on the germination of endemic and non-endemic species in the campo rupestre in Brazil.We performed a metaanalysis using increased temperature and darkness as proxies for the impact of disturbance on germination patterns.In this context,we hypothesized that:increased temperature and darkness negatively influence the germination of native species and positively influence the germination of alien species in the campo rupestre.Specifically,we expect the negative effect to be more pronounced in endemic species than in native non-endemic species.Moreover,we intend to describe the role of seed size in the germination of native and alien species from campo rupestre in the context of increased temperature and darkness.Our analysis showed that increased temperature influenced the germination of alien species by ca.55%,while it did not influence the germination of endemic or native non-endemic species.Furthermore,the germination of alien species under higher temperatures was promoted by increasing seed size.Darkness negatively influenced seed germination of native species,independent of their distribution.Moreover,under darkness conditions,the germination of endemic seeds decreased with seed size.Through their direct effects on germination strategies,we conclude that warming temperatures and land-use change can lead to a long-term displacement of endemic species by native non-endemic and alien species in campo rupestre,thus compromising ecosystem services and conservation of these fragile physiognomies in the near future.
