The humid agroclimatic conditions of Kerala,India permit the cultivation of an array of bamboo species of which Dendrocalamus strictus Roxb.(Nees.) is an important one on account of its high growth rate and multiple u...The humid agroclimatic conditions of Kerala,India permit the cultivation of an array of bamboo species of which Dendrocalamus strictus Roxb.(Nees.) is an important one on account of its high growth rate and multiple uses. Stand density, a potential tool in controlling the productivity of woody ecosystems, its effect on growth and root distribution patterns may provide a better understanding of productivity optimization especially when bamboo-based intercropping options are considered.Growth attributes of 7-year-old bamboo(D. strictus) stands managed at variable spacing(4×4 m, 6×6 m, 8×8 m,10×10 m, 12×12 m) were studied. Functional root activity among bamboo clumps were also studied using a radio tracer soil injection method in which the radio isotopeP was applied to soil at varying depths and lateral distances from the clump. Results indicate that spacing exerts a profound influence on growth of bamboo. Widely spaced bamboo exhibited higher clump diameters and crown widths while clump heights were better under closer spacing. Clump height was 30% lower and DBH 52%higher at the widest spacing(12×12 m) compared to the closest spacing(4×4 m). With increasing soil depth and lateral distance, root activity decreased significantly. Root activity near the clump base was highest(809 counts per minute, cpm; 50 cm depth and 50 cm lateral distance) at 4×4 m. Tracer study further showed wider distribution of root activity with increase in clump spacing. It may be concluded that the intensive foraging zone of bamboo is within a 50-cm radius around the clump irrespective of spacing. N, P and K content in the upper 20 cm was 2197,21, and 203 kg/ha respectively for the closely spaced bamboo(4×4 m) which were significantly higher than corresponding nutrient content at wider spacings. About 50% of N, P and K were present within the 0–20 cm soil layer, which decreased drastically beyond the 20 cm depth.The results suggest that stand management practices through planting density regulation can modify the resource acquisition patterns of D. strictus which in turn can change growth and productivity considerably. Such information on root activities, spatial and temporal strategies of resource sharing will be helpful in deciding the effective nutrition zone for D. strictus. Further, the study throws light on the spatial distribution of non-competitive zones for productivity optimization yields, especially when intercropping practices are considered.展开更多
We design a nunchakus-like tracer and investigate its self-adaptive behavior in an active Brownian particle(ABP)bath via systematically tuning the self-propelled capability and density of ABPs.Specifically,the nunchak...We design a nunchakus-like tracer and investigate its self-adaptive behavior in an active Brownian particle(ABP)bath via systematically tuning the self-propelled capability and density of ABPs.Specifically,the nunchakus-like tracer will have a stable wedge-like shape in the ABP bath when the self-propelled force is high enough.We analyze the angle between the two arms of the tracer and the velocity of the joint point of the tracer.The angle exhibits a non-monotonic phenomenon as a function of active force.However,it increases with density of ABPs increasing monotonically.A simple linear relationship between the velocity and the self-propelled force is found under the highly active force.In other words,the joint points of the tracer diffuse and the super-diffusive behavior can make the relation between the self-propelled force and the density of ABPs persist longer.In addition,we find that the tracer can flip at high density of ABPs.Our results also suggest the new self-adaptive model research of the transport properties in a non-equilibrium medium.展开更多
We investigate the effective diffusion of a tracer immersed in an active particle bath consisting of self-propelled particles.Utilising the Dean's method developed for the equilibrium bath and extending it to the ...We investigate the effective diffusion of a tracer immersed in an active particle bath consisting of self-propelled particles.Utilising the Dean's method developed for the equilibrium bath and extending it to the nonequilibrium situation,we derive a generalized Langevin equation(GLE)for the tracer particle.The complex interactions between the tracer and bath particles are shown as a memory kernel term and two colored noise terms.To obtain the effective diffusivity of the tracer,we use path integral technique to calculate all necessary correlation functions.Calculations show the effective diffusion decreases with the persistent time of active force,and has rich behavior with the number density of bath particles,depending on different activities.All theoretical results regarding the dependence of such diffusivity on bath parameters have been confirmed by direct computer simulation.展开更多
To investigate the dispersal pattern and the fate of dredged materials disposed at a pre-selected disposal site, a field tracer experiment was conducted in the North Passage of the Changjiang Estuary during the 2005 f...To investigate the dispersal pattern and the fate of dredged materials disposed at a pre-selected disposal site, a field tracer experiment was conducted in the North Passage of the Changjiang Estuary during the 2005 flood season. Three tons of dredged materials were mixed with 2.792 kg of sodium hexachloroiridate （IV） hexahydrate （SHH）, which contained the rare earth element tracer iridum （Ir）. Sampling was conducted at pre-selected sections of the estuary on the second, third and fourth day after the release of dredged materials. All samples were evaluated by use of neutron activation analysis. The majority of the dredged material was dispersed nearly parallel to the navigation channel and deposited between the channel and the south dike. Only a small quantity of dredged materials entered or crossed the navigation channel, and the back silting ratio in the navigation channel was about 5%. The dredged materials also dispersed southeasterly beyond two dike heads.展开更多
We quantify the mean potential energy of a passive colloidal particle harmonically confined in a bacterial solution using optical traps.We find that the average potential energy of the passive particle depends on the ...We quantify the mean potential energy of a passive colloidal particle harmonically confined in a bacterial solution using optical traps.We find that the average potential energy of the passive particle depends on the trap stiffness,in contrast to the equilibrium case where energy partition is independent of the external constraints.The constraint dependence of the mean potential energy originates from the fact that the persistent collisions between the passive particle and the active bacteria are influenced by the particle relaxation dynamics.Our experimental results are consistent with the Brownian dynamics simulations,and confirm the recent theoretical prediction.展开更多
基金financially supported by the Kerala Agricultural University
文摘The humid agroclimatic conditions of Kerala,India permit the cultivation of an array of bamboo species of which Dendrocalamus strictus Roxb.(Nees.) is an important one on account of its high growth rate and multiple uses. Stand density, a potential tool in controlling the productivity of woody ecosystems, its effect on growth and root distribution patterns may provide a better understanding of productivity optimization especially when bamboo-based intercropping options are considered.Growth attributes of 7-year-old bamboo(D. strictus) stands managed at variable spacing(4×4 m, 6×6 m, 8×8 m,10×10 m, 12×12 m) were studied. Functional root activity among bamboo clumps were also studied using a radio tracer soil injection method in which the radio isotopeP was applied to soil at varying depths and lateral distances from the clump. Results indicate that spacing exerts a profound influence on growth of bamboo. Widely spaced bamboo exhibited higher clump diameters and crown widths while clump heights were better under closer spacing. Clump height was 30% lower and DBH 52%higher at the widest spacing(12×12 m) compared to the closest spacing(4×4 m). With increasing soil depth and lateral distance, root activity decreased significantly. Root activity near the clump base was highest(809 counts per minute, cpm; 50 cm depth and 50 cm lateral distance) at 4×4 m. Tracer study further showed wider distribution of root activity with increase in clump spacing. It may be concluded that the intensive foraging zone of bamboo is within a 50-cm radius around the clump irrespective of spacing. N, P and K content in the upper 20 cm was 2197,21, and 203 kg/ha respectively for the closely spaced bamboo(4×4 m) which were significantly higher than corresponding nutrient content at wider spacings. About 50% of N, P and K were present within the 0–20 cm soil layer, which decreased drastically beyond the 20 cm depth.The results suggest that stand management practices through planting density regulation can modify the resource acquisition patterns of D. strictus which in turn can change growth and productivity considerably. Such information on root activities, spatial and temporal strategies of resource sharing will be helpful in deciding the effective nutrition zone for D. strictus. Further, the study throws light on the spatial distribution of non-competitive zones for productivity optimization yields, especially when intercropping practices are considered.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11804085 and 21674078)the Natural Science Foundation of the Jiangsu Provincial Higher Education Institutions,China(Grant No.21KJB140023)the Foundation of Jiangsu Provincial Innovation and Entrepreneurship Doctor,China(Grant No.JSSCBS20211147)。
文摘We design a nunchakus-like tracer and investigate its self-adaptive behavior in an active Brownian particle(ABP)bath via systematically tuning the self-propelled capability and density of ABPs.Specifically,the nunchakus-like tracer will have a stable wedge-like shape in the ABP bath when the self-propelled force is high enough.We analyze the angle between the two arms of the tracer and the velocity of the joint point of the tracer.The angle exhibits a non-monotonic phenomenon as a function of active force.However,it increases with density of ABPs increasing monotonically.A simple linear relationship between the velocity and the self-propelled force is found under the highly active force.In other words,the joint points of the tracer diffuse and the super-diffusive behavior can make the relation between the self-propelled force and the density of ABPs persist longer.In addition,we find that the tracer can flip at high density of ABPs.Our results also suggest the new self-adaptive model research of the transport properties in a non-equilibrium medium.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0450402)the National Natural Science Foundation of China(32090040 and 22373090)
文摘We investigate the effective diffusion of a tracer immersed in an active particle bath consisting of self-propelled particles.Utilising the Dean's method developed for the equilibrium bath and extending it to the nonequilibrium situation,we derive a generalized Langevin equation(GLE)for the tracer particle.The complex interactions between the tracer and bath particles are shown as a memory kernel term and two colored noise terms.To obtain the effective diffusivity of the tracer,we use path integral technique to calculate all necessary correlation functions.Calculations show the effective diffusion decreases with the persistent time of active force,and has rich behavior with the number density of bath particles,depending on different activities.All theoretical results regarding the dependence of such diffusivity on bath parameters have been confirmed by direct computer simulation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50979053 and 50939003)the Major State Basic Research Development Program of China (973 Program, Grant No. 2010CB429002)
文摘To investigate the dispersal pattern and the fate of dredged materials disposed at a pre-selected disposal site, a field tracer experiment was conducted in the North Passage of the Changjiang Estuary during the 2005 flood season. Three tons of dredged materials were mixed with 2.792 kg of sodium hexachloroiridate （IV） hexahydrate （SHH）, which contained the rare earth element tracer iridum （Ir）. Sampling was conducted at pre-selected sections of the estuary on the second, third and fourth day after the release of dredged materials. All samples were evaluated by use of neutron activation analysis. The majority of the dredged material was dispersed nearly parallel to the navigation channel and deposited between the channel and the south dike. Only a small quantity of dredged materials entered or crossed the navigation channel, and the back silting ratio in the navigation channel was about 5%. The dredged materials also dispersed southeasterly beyond two dike heads.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874397,11674365,11774393,and 11774394).
文摘We quantify the mean potential energy of a passive colloidal particle harmonically confined in a bacterial solution using optical traps.We find that the average potential energy of the passive particle depends on the trap stiffness,in contrast to the equilibrium case where energy partition is independent of the external constraints.The constraint dependence of the mean potential energy originates from the fact that the persistent collisions between the passive particle and the active bacteria are influenced by the particle relaxation dynamics.Our experimental results are consistent with the Brownian dynamics simulations,and confirm the recent theoretical prediction.
