Exploring site-specific N application rate to reduce N footprint and increase crop production for green manure-rice rotation system in southern China.

Milk vetch (Astragalus sinicus L.) is leguminous green manure (GM) which produces organic nitrogen (N) for subsequent crops and is widely planted and utilized to simultaneously reduce the use of synthetic N fertilizer and its environmental costs in rice systems. Determination of an optimal N application rate specific to the GM-rice system is challenging because of the large temporal and spatial variations in soil, climate, and field management conditions. To solve this problem, we developed a framework to explore the site-specific N application rate for the low-N footprint rice production system in southern China based on multi-site field experiments, farmer field survey, and process-based model (WHCNS_Rice, soil water heat carbon nitrogen simulator for rice). The results showed that a process-based model can explain >83.3% (p < 0.01) of the variation in rice yield, aboveground biomass, crop N uptake, and soil mineral N. Based on the scenario analysis of the tested WHCNS_Rice model, the simple regression equation was developed to implement site-specific N application rates that considered variations in GM biomass, soil, and climatic conditions. Simulation evaluation on nine provinces in southern China showed that the site-specific N application rate reduced regional synthetic N fertilizer input by 29.6 ± 17.8% and 65.3 ± 23.0% for single and early rice, respectively; decreased their total N footprints (NFs) by 23.4% and 49.3%, respectively; and without reduction in rice yield, compared with traditional farming N practices. The reduction in total NF was attributed to the reduced emissions from ammonia volatilization by 35.2%, N leaching by 28.4%, and N runoff by 32.7%. In this study, we suggested a low NF rice production system that can be obtained by combining GM with site-specific N application rate in southern China.

Vector spatiotemporal solitons in cold atomic gases with linear and nonlinear PT symmetric potentials.

Realizing vector spatiotemporal solitons that are stable in high dimensions is a long-standing goal in the study of nonlinear optical physics. Here, a scheme is proposed to generate three-dimensional (3D) vector spatiotemporal solitons in a cold atomic system with linear and nonlinear parity-time (PT) potentials by utilizing electromagnetically induced transparency (EIT). We investigate the existence and stability of these vector 3D semilunar solitons (SSs) and vortex solitons (VSs) supported by the linear and nonlinear PT potentials. The results show that these solitons have extremely low generation power and very slow propagation velocity and can stably propagate with constant total energy in this system. The frontal head-on collisions of two vector solitons feature quasi-elastic collisions. The dynamics characteristics of these solitons depend on the linear and nonlinear PT-symmetric potential parameters, in particular, the imaginary part of PT potentials. Our study provides a new route for manipulating high-dimensional nonlinear vector optical signals via the controlled optical linear and nonlinear potentials in cold atomic gases.

Parity-time symmetry light bullets in a cold Rydberg atomic gas.

A scheme is proposed to generate stable light bullets (LBs) in a cold Rydberg atomic system with a parity-time (PT) symmetric potential, by utilizing electromagnetically induced transparency (EIT). Using an incoherent population pumping between two low-lying levels and spatial modulations of control and auxiliary laser fields, we obtain a two-dimensional (2D) periodic optical potential with PT symmetry. Based on PT symmetry potential and the long-range Rydberg-Rydberg atomic interaction, the system may support slow LBs with low light intensity. Further, it is found that the local and non-local nonlinear coefficients and PT-symmetric potential can be tuned and used to manipulate the behavior of LBs.

[Changes of matrix metalloproteinase 2,9 and tissue inhibitor of metalloproteinase 1, 2, 3 expression level in aged rat lung].

OBJECTIVES: To investigate the underlying mechanism of age related increase of pulmonary fibrosis incidence METHODS: The levels of pulmonary collagen and TGF-beta1 protein, MMP2,9 mRNA and TIMP 1,2,3 mRNA expression were measured by ELISA and realtime PCR. RESULTS: As compared with adult rats [(756 +/- 160) pg/g vs (1 000 +/- 246) pg/g, P<0.05] the aged rats had more extracellular matrix components, increased TGF-beta1 protein level, lower (3.15 +/- 1.76 vs 0.17 +/- 0.13, P<0.01) MMP2 mRNA expression and TIMP 1,2,3 mRNA expressions (TIMP1 2.00 +/- 1.74 vs 0.11 +/- 0.06,TIMP2 7.60 +/- 2.51 vs 2.69 +/- 1.76, TIMP3 1.32 +/- 0.46 vs 0.29 +/- 0.16, P<0.01). No difference was observed in MMP9 (1.66 +/- 0.67 vs 1.74 +/- 0.87, P>0.05) mRNA expression. CONCLUSION: elevation in TGF-beta1 protein level, changes in the expression of MMP2/9 and decreased expression of TIMPS mRNA could be the underlying mechanism of age related increase of pulmonary incidence.

Effects of different nitrogen supply levels on the yield of Orychophragmus violaceus, soil residual inorganic nitrogen, and nitrogen balance.

Understanding the responses of winter green manure February orchid (Orychophragmus violaceus) to different levels of nitrogen (N) supply in Northern China and determining the optimal soil N supply level to meet N demands of green manure production with high yield and efficiency, could provide a theoretical foundation and practice reference for maximizing ecological effects of green manure and optimizing N management for spring maize-green manure rotation system in intensive farmland in Northern China. We carried out a field experiment in a site which had received no fertilizer for many years. The aboveground biomass accumulation, N uptake of February orchid and soil residual inorganic N before green manure incorporation, as well as the N balance during the green manure growing season were determined under different levels of N supply. The results showed that N fertilizer application significantly increased the biomass and N uptake of February orchid under low soil inorganic N content (15 kg·hm-2 in 0-90 cm soil layer). At the application rate of 90 kg·hm-2, the biomass (dry mass) and N uptake reached the maximum, being 2031 and 42 kg·hm-2, respectively. The soil residual inorganic N amount rose with the increases of N fertilizer application before sowing, growing very rapidly once the application rate was over 60 kg·hm-2. With the increases of N application rate, the calculated apparent N balance changed from deficit to surplus in the growing season of February orchid. The inputs and outputs of N reached a balance at the application rates of 60 to 90 kg·hm-2. The relationships between February orchid biomass, N uptake, soil inorganic N before green manure incorporation, and soil N supply amount (0-90 cm preplant soil inorganic N content plus N application rate) could be fitted by the quadratic, linear plus plateau and exponential models respectively. Based on the simulation, we calculated the preplant soil N supply and soil residual inorganic N content before green manure incorporation would be 136 and 78 kg·hm-2 individually, as the biomass of February orchid reached the maximum (2010 kg·hm-2). While N uptake was at the highest level of 40 kg·hm-2, the biomass of February orchid was 95% of the maximum biomass mentioned above (1919 kg·hm-2) and the soil residual inorganic N before green manure incorporation decreased to 57 kg·hm-2 whose corresponding minimum soil N supply amount was 105 kg·hm-2. This value was quite near to the recommended soil residual inorganic N (100 kg·hm-2) after maize harvest under optimized N management in Nor-thern China. Taken together, our results showed that the level of soil N supply should be at approximately 100 to 105 kg·hm-2 in spring maize-winter green manure system for improving tradeoffs between agronomic and environmental impacts.

[Efficiency of APACHE II and III scoring system in the prognostication of patients older than 75 years].

OBJECTIVE: To observe the efficiency of both the APACHE II/III scoring systems in predicting the prognosis of patients older than 75 years. METHODS: We calculated both the APACHE II and III scores in patients older than 75 years who were admitted to the geriatric intensive care unit (GICU) of our hospital in a duration of 6 months. The scores and predicting death rates were compared with the actual death rates. RESULTS: There was definite correlation between the APACHE II/III scores and the actual death rates. Sensitivity of the APACHE II/III systems are 66.7% and 41.7% respectively. Specificity of the APACHE II/III systems are 90.9% and 100% respectively. CONCLUSIONS: Both the APACHE II/III systems can do well in predicting the prognosis of ICU patients older than 75 years, but APACHE III tends to underestimate the hospital death rate of elderly patients.