Decentralized policy learning with partial observation and mechanical constraints for multiperson modeling

Extracting the rules of real-world multi-agent behaviors is a current challenge in various scientific and engineering fields. Biological agents independently have limited observation and mechanical constraints; however, most of the conventional data-driven models ignore such assumptions, resulting in lack of biological plausibility and model interpretability for behavioral analyses. Here we propose sequential generative models with partial observation and mechanical constraints in a decentralized manner, which can model agents' cognition and body dynamics, and predict biologically plausible behaviors. We formulate this as a decentralized multi-agent imitation-learning problem, leveraging binary partial observation and decentralized policy models based on hierarchical variational recurrent neural networks with physical and biomechanical penalties. Using real-world basketball and soccer datasets, we show the effectiveness of our method in terms of the constraint violations, long-term trajectory prediction, and partial observation. Our approach can be used as a multi-agent simulator to generate realistic trajectories using real-world data.Comment: 17 pages with 7 figures and 4 tables, accepted in Neural Network

RNA-seq Transcriptional Profiling of an Arbuscular Mycorrhiza Provides Insights into Regulated and Coordinated Gene Expression in Lotus japonicus and Rhizophagus irregularis

Gene expression during arbuscular mycorrhizal development is highly orchestrated in both plants and arbuscular mycorrhizal fungi. To elucidate the gene expression profiles of the symbiotic association, we performed a digital gene expression analysis of Lotus japonicus and Rhizophagus irregularis using a HiSeq 2000 next-generation sequencer with a Cufflinks assembly and de novo transcriptome assembly. There were 3,641 genes differentially expressed during arbuscular mycorrhizal development in L. japonicus, approximately 80% of which were up-regulated. The up-regulated genes included secreted proteins, transporters, proteins involved in lipid and amino acid metabolism, ribosomes and histones. We also detected many genes that were differentially expressed in small-secreted peptides and transcription factors, which may be involved in signal transduction or transcription regulation during symbiosis. Coregulated genes between arbuscular mycorrhizal and root nodule symbiosis were not particularly abundant, but transcripts encoding for membrane traffic-related proteins, transporters and iron transport-related proteins were found to be highly co-up-regulated. In transcripts of arbuscular mycorrhizal fungi, expansion of cytochrome P450 was observed, which may contribute to various metabolic pathways required to accommodate roots and soil. The comprehensive gene expression data of both plants and arbuscular mycorrhizal fungi provide a powerful platform for investigating the functional and molecular mechanisms underlying arbuscular mycorrhizal symbiosis.ArticlePLANT AND CELL PHYSIOLOGY. 56(8):1490-1511 (2015)journal articl

Evaluation of water dynamics of contour-levee irrigation system in sloped rice fields in Colombia

Contour-levee irrigation system is commonly used for rice cultivation in Latin American and Caribbean countries, but its water dynamics in commercial farm field settings are yet to be fully determined. This study aimed to investigate the water dynamics of the contour-levee irrigation system by analyzing conventional irrigation practices and by quantifying water balance and additionally to examine potential toposequential effects. Field experiments with different irrigation intervals were conducted on three commercial farms in Ibagué, Colombia for two seasons from 2017 to 2018. Irrigation and runoff water flows were constantly measured during the crop cycle using Parshall flumes with water level sensors. Percolation rate and field water table were measured using percolators and piezometers installed along the toposequence. The results showed that conventional irrigation management was highly flexible depending on soil permeability, rainfall, and agronomic factors, not particularly paying attention to ensure the flooded conditions during flowering period. The water balance resulted in the irrigation accounting for 76% of the total water input, whereas the runoff, ET, and percolation accounted for 40%, 21%, and 31% on overall average with considerable variation among the three farms. Percolation rates and duration with standing water did not show a clear and consistent tendency among the toposequential positions, but the percolation rate was significantly different among the farms corresponding to soil permeability. Consequently, clear toposequential effects on the water dynamics or on grain yield were not observed at the study site. To our knowledge, this study is the first to elucidate detailed water dynamics of contour-levee irrigation system in farm fields including toposequential difference

Denitrification Losses in Response to N Fertilizer Rates—Integrating High Temporal Resolution N2_2O, In Situ 15^{15}N2_2O and 15^{15}N2_2 Measurements and Fertilizer 15^{15}N Recoveries in Intensive Sugarcane Systems

Denitrification is a key process in the global nitrogen (N) cycle, causing both nitrous oxide (N$_2$O) and dinitrogen (N$_2$) emissions. However, estimates of seasonal denitrification losses (N$_2$O + N$_2$) are scarce, reflecting methodological difficulties in measuring soil-borne N$_2$ emissions against the high atmospheric N$_2$ background and challenges regarding their spatio-temporal upscaling. This study investigated N$_2$O + N$_2$ losses in response to N fertilizer rates (0, 100, 150, 200, and 250 kg N ha$^{−1}$) on two intensively managed tropical sugarcane farms in Australia, by combining automated N$_2$O monitoring, in situ N$_2$ and N$_2$O measurements using the $^{15}$N gas flux method and fertilizer $^{15}$N recoveries at harvest. Dynamic changes in the N$_2$O/(N$_2$O + N$_2$) ratio (<0.01 to 0.768) were explained by fitting generalized additive mixed models (GAMMs) with soil factors to upscale high temporal-resolution N$_2$O data to daily N$_2$ emissions over the season. Cumulative N$_2$O + N$_2$ losses ranged from 12 to 87 kg N ha$^{−1}$, increasing non-linearly with increasing N fertilizer rates. Emissions of N$_2$O + N$_2$ accounted for 31%–78% of fertilizer $^{15}$N losses and were dominated by environmentally benign N$_2$ emissions. The contribution of denitrification to N fertilizer loss decreased with increasing N rates, suggesting increasing significance of other N loss pathways including leaching and runoff at higher N rates. This study delivers a blueprint approach to extrapolate denitrification measurements at both temporal and spatial scales, which can be applied in fertilized agroecosystems. Robust estimates of denitrification losses determined using this method will help to improve cropping system modeling approaches, advancing our understanding of the N cycle across scales

Synthesis and Magnetic Properties of Fergusonite Structured La(NbVMn)O4

The authors have synthesized fergusonite-structured La(Nb0·71V0·04Mn0·25)O4 samples. The samples, consisting of La3+, Nb5+, V5+, Mn4+ and oxygen ions, demonstrated temperature-dependent magnetization that increased with lowering the temperature below ≈200 K, and almost saturated below ≈100 K. At 75 K, the field-dependent magnetization demonstrated sigmoidal curve and reached 3 μB/Mn at 1 T. Such a magnetic behavior can be ascribed to exchange interaction between Mn4+Nb2O11 nanoclusters. The Mn4+ substitution for the V5+ sites of the crystal resulted also in the occupied state above the valence band maximum