Aims Nitrogen(N)-fixing legumes,despite being highly phosphorus(P)-demanding,constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands.However,legume performance,...Aims Nitrogen(N)-fixing legumes,despite being highly phosphorus(P)-demanding,constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands.However,legume performance,including biomass,abundance and species richness,is expected to change,because anthropogenic activities have drastically increased soil N and P availability world-wide.We conducted a field experiment to assess the effects of N and P addition,alone and in combination,on legume performance in an alpine grassland,and identified and clarified the mechanisms underlying these changes.Methods A three year field experiment of N addition(10 g N m−2 year−1),P addition(5 g P m−2 year−1),and N+P combined addition(both N and P,same amounts as solo treatments)was conducted in an alpine grassland on the tibetan Plateau in china from 2011 to 2013.Effects of nutrient addition were assessed at the community level(above-ground net primary production(ANPP),height and light intensity),functional group level(biomass,species richness,relative height,relative coverage and relative density of legumes)and species level(foliar N,P concentration of two legumes).Important findings Overall,adding N alone significantly increased ANPP by 20.82%,but adding P alone did not;whereas,addition of N and P together resulted in a large increase in ANPP(+37.03%)than addition of either alone,indicating potential co-limitation of alpine grasslands.In contrast,adding P alone significantly promoted legume perfor-mance as measured by 65.22%increase in biomass and 58.45%increase in relative abundance,while adding N alone reduced leg-ume performance as measured by 39.54%decrease in biomass and 50.36%in relative abundance.combining P and N addition did not mitigate the negative effect of N addition on legume performance and,surprisingly,suppressed legume biomass by 53.14%and relative abundance by 63.51%.N and P addition altered the balance of light competition between grasses and legumes as indicated by the changes in light levels,plant heights and litter accumulation.However,there were no obvious changes in legume species richness in response to N and P within our experimental timeframe.this study provides further evidence of the importance of P as a co-limiting nutrient in alpine grasslands,contrary to the traditional view that N limitation predominates in such regions.the contrasting effects of N and P addition on legume performance provide important insights into potential changes in legume performance in nutrient-limited grasslands following N and P enrichment under climate change,with implications for nutrient management in alpine grasslands.展开更多
Superabsorbent Polymer(SAP)has emerged as a topic of considerable interest in recent years.The present study systematically and quantitively investigated the effect of SAP on hydration,autogenous shrinkage,mechanical ...Superabsorbent Polymer(SAP)has emerged as a topic of considerable interest in recent years.The present study systematically and quantitively investigated the effect of SAP on hydration,autogenous shrinkage,mechanical properties,and microstructure of cement mortars.Influences of SAP on hydration heat and autogenous shrinkage were studied by utilizing TAM AIR technology and a non-contact autogenous shrinkage test method.Scanning Electron Microscope(SEM)was employed to assess the microstructure evolution.Although SAP decreased the peak rate of hydration heat and retarded the hydration,it significantly increased the cumulative heat,indicating SAP helps promote the hydration.Hydration promotion caused by SAP mainly occurred in the deceleration period and attenuation period.SAP can significantly mitigate the autogenous shrinkage when the content ranged from 0 to 0.5%.Microstructure characteristics showed that pores and gaps were introduced when SAP was added.The microstructure difference caused by SAP contributed to the inferior mechanical behaviors of cement mortars treated by SAP.展开更多
Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a modelindependent way.In this study,the Particle Flow Network and ParticleNet techniques are used to classify the Higgs de...Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a modelindependent way.In this study,the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories,and the ultimate goal is to realize an"end-to-end"analysis.A Monte Carlo simulation study is performed to demonstrate the feasibility,and the performance looks rather promising.This result could be the basis of a"one-stop"analysis to measure all the branching fractions of the Higgs decays simultaneously.展开更多
Initial State Radiation(ISR)plays an important role in e+e−collision experiments such as the BESIII.To correct the ISR effects in measurements of hadronic cross-sections of e+e−annihilation,an iterative method that we...Initial State Radiation(ISR)plays an important role in e+e−collision experiments such as the BESIII.To correct the ISR effects in measurements of hadronic cross-sections of e+e−annihilation,an iterative method that weights simulated ISR events is proposed here to assess the efficiency of event selection and the ISR correction factor for the observed cross-section.The simulated ISR events were generated only once,and the obtained cross-sectional line shape was used iteratively to weigh the same simulated ISR events to evaluate the efficiency and corrections until the results converge.Compared with the method of generating ISR events iteratively,the proposed weighting method provides consistent results,and reduces the computational time and disk space required by a factor of five or more,thus speeding-up e+e−hadronic cross-section measurements.展开更多
Pavement skid resistance is critical for contributing to traffic safety.In this study,two pavement specimens were fabricated using different aggregate gradations and binder contents.Compaction efforts were made to ens...Pavement skid resistance is critical for contributing to traffic safety.In this study,two pavement specimens were fabricated using different aggregate gradations and binder contents.Compaction efforts were made to ensure the same porosity of the two specimens.Some parameters related to the surface morphology were measured using the sand patching method and a 3D laser.The parameters include mean texture depth(MTD),interface roughness(R_(a)),skewness(R_(sk)),kurtosis(R_(ku)),fractal dimension(D)and parameters related to material ratio curve.Relationships between these parameters and skid resistance were quantitatively developed.Skid resistance increased along with the increase of MTD,R_(a) and D.From the surface A to surface B,MTD increased from 0.23 to 1.10 mm,R_(a) increased from 0.93 to 1.80 mm,D increased from 2.25 to 2.43 and the British Pendulum Number increased from 80 to 97 accordingly.The comprehensive analysis could assist scholars and practitioners to facilitate the understanding of tyre-pavement interaction and further assist pavement design.展开更多
文摘Aims Nitrogen(N)-fixing legumes,despite being highly phosphorus(P)-demanding,constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands.However,legume performance,including biomass,abundance and species richness,is expected to change,because anthropogenic activities have drastically increased soil N and P availability world-wide.We conducted a field experiment to assess the effects of N and P addition,alone and in combination,on legume performance in an alpine grassland,and identified and clarified the mechanisms underlying these changes.Methods A three year field experiment of N addition(10 g N m−2 year−1),P addition(5 g P m−2 year−1),and N+P combined addition(both N and P,same amounts as solo treatments)was conducted in an alpine grassland on the tibetan Plateau in china from 2011 to 2013.Effects of nutrient addition were assessed at the community level(above-ground net primary production(ANPP),height and light intensity),functional group level(biomass,species richness,relative height,relative coverage and relative density of legumes)and species level(foliar N,P concentration of two legumes).Important findings Overall,adding N alone significantly increased ANPP by 20.82%,but adding P alone did not;whereas,addition of N and P together resulted in a large increase in ANPP(+37.03%)than addition of either alone,indicating potential co-limitation of alpine grasslands.In contrast,adding P alone significantly promoted legume perfor-mance as measured by 65.22%increase in biomass and 58.45%increase in relative abundance,while adding N alone reduced leg-ume performance as measured by 39.54%decrease in biomass and 50.36%in relative abundance.combining P and N addition did not mitigate the negative effect of N addition on legume performance and,surprisingly,suppressed legume biomass by 53.14%and relative abundance by 63.51%.N and P addition altered the balance of light competition between grasses and legumes as indicated by the changes in light levels,plant heights and litter accumulation.However,there were no obvious changes in legume species richness in response to N and P within our experimental timeframe.this study provides further evidence of the importance of P as a co-limiting nutrient in alpine grasslands,contrary to the traditional view that N limitation predominates in such regions.the contrasting effects of N and P addition on legume performance provide important insights into potential changes in legume performance in nutrient-limited grasslands following N and P enrichment under climate change,with implications for nutrient management in alpine grasslands.
基金The authors would like to thank the financial sponsorship provided by the National Natural Science Foundation of China(Grant No.51778638).The contents of this paper reflect the views of the authors,who are responsible for the facts and the accuracy of the data presented herein,and do not necessarily reflect any official views or policies.The first author would also like to thank the China Scholarship Council(CSC)for their support.
文摘Superabsorbent Polymer(SAP)has emerged as a topic of considerable interest in recent years.The present study systematically and quantitively investigated the effect of SAP on hydration,autogenous shrinkage,mechanical properties,and microstructure of cement mortars.Influences of SAP on hydration heat and autogenous shrinkage were studied by utilizing TAM AIR technology and a non-contact autogenous shrinkage test method.Scanning Electron Microscope(SEM)was employed to assess the microstructure evolution.Although SAP decreased the peak rate of hydration heat and retarded the hydration,it significantly increased the cumulative heat,indicating SAP helps promote the hydration.Hydration promotion caused by SAP mainly occurred in the deceleration period and attenuation period.SAP can significantly mitigate the autogenous shrinkage when the content ranged from 0 to 0.5%.Microstructure characteristics showed that pores and gaps were introduced when SAP was added.The microstructure difference caused by SAP contributed to the inferior mechanical behaviors of cement mortars treated by SAP.
基金Supported by the National Natural Science Foundation of China(NSFC)(12075271,12047569)。
文摘Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a modelindependent way.In this study,the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories,and the ultimate goal is to realize an"end-to-end"analysis.A Monte Carlo simulation study is performed to demonstrate the feasibility,and the performance looks rather promising.This result could be the basis of a"one-stop"analysis to measure all the branching fractions of the Higgs decays simultaneously.
基金The material presented in this paper is by the authors alone,and has not been reviewed by the BESIII Collaboration.However,we thank our colleagues for allowing us to make use of the BESIII software environment.This work was supported by the National Natural Science Foundation of China,under Grant Nos.U1732105,U1632106,11947415,and 12047569 and the Research Foundation for Advanced Talents of Nanjing Normal University,under Grant No.2014102XGQ0085.We also appreciate valuable discussions with Dr.Kai Zhu,Dr.Yuping Guo,and Prof.Changzheng Yuan.
文摘Initial State Radiation(ISR)plays an important role in e+e−collision experiments such as the BESIII.To correct the ISR effects in measurements of hadronic cross-sections of e+e−annihilation,an iterative method that weights simulated ISR events is proposed here to assess the efficiency of event selection and the ISR correction factor for the observed cross-section.The simulated ISR events were generated only once,and the obtained cross-sectional line shape was used iteratively to weigh the same simulated ISR events to evaluate the efficiency and corrections until the results converge.Compared with the method of generating ISR events iteratively,the proposed weighting method provides consistent results,and reduces the computational time and disk space required by a factor of five or more,thus speeding-up e+e−hadronic cross-section measurements.
基金funded by the National Natural Science Foun-dation of China (Grant Nos.52008405 and 51778638),to which the authors are very grateful.
文摘Pavement skid resistance is critical for contributing to traffic safety.In this study,two pavement specimens were fabricated using different aggregate gradations and binder contents.Compaction efforts were made to ensure the same porosity of the two specimens.Some parameters related to the surface morphology were measured using the sand patching method and a 3D laser.The parameters include mean texture depth(MTD),interface roughness(R_(a)),skewness(R_(sk)),kurtosis(R_(ku)),fractal dimension(D)and parameters related to material ratio curve.Relationships between these parameters and skid resistance were quantitatively developed.Skid resistance increased along with the increase of MTD,R_(a) and D.From the surface A to surface B,MTD increased from 0.23 to 1.10 mm,R_(a) increased from 0.93 to 1.80 mm,D increased from 2.25 to 2.43 and the British Pendulum Number increased from 80 to 97 accordingly.The comprehensive analysis could assist scholars and practitioners to facilitate the understanding of tyre-pavement interaction and further assist pavement design.
