Multi-agent reinforcement learning holds tremendous potential for revolutionizing intelligent systems across diverse domains. However, it is also concomitant with a set of formidable challenges, ...which include the effective allocation of credit values to each agent, real-time collaboration among heterogeneous agents, and an appropriate reward function to guide agent behavior. To handle these issues, we propose an innovative solution named the Graph Attention Counterfactual Multiagent Actor–Critic algorithm (GACMAC). This algorithm encompasses several key components: First, it employs a multi-agent actor–critic framework along with counterfactual baselines to assess the individual actions of each agent. Second, it integrates a graph attention network to enhance real-time collaboration among agents, enabling heterogeneous agents to effectively share information during handling tasks. Third, it incorporates prior human knowledge through a potential-based reward shaping method, thereby elevating the convergence speed and stability of the algorithm. We tested our algorithm on the StarCraft Multi-Agent Challenge (SMAC) platform, which is a recognized platform for testing multi-agent algorithms, and our algorithm achieved a win rate of over 95% on the platform, comparable to the current state-of-the-art multi-agent controllers.
Purpose
This paper aims to evaluate the early effects of the pandemic of coronavirus disease 2019 (COVID-19) and accompanying stay-at-home orders on restaurant demand in US counties.
...Design/methodology/approach
The following two sets of daily restaurant demand data were collected for each US county: foot traffic data and card transaction data. A two-way fixed-effects panel data model was used to estimate daily restaurant demand from February 1 to April 30, 2020.
Findings
Results show that a 1% increase in daily new COVID-19 cases led to a 0.0556% decrease in daily restaurant demand, while stay-at-home orders were collectively associated with a 3.25% drop in demand. The extent of these declines varied across counties; ethnicity, political ideology, eat-in habits and restaurant diversity were found to moderate the effects of the COVID-19 pandemic and stay-at-home orders.
Practical implications
These results characterize the regional restaurant industry’s resilience to COVID-19 and identify particularly vulnerable areas that may require pubic policies and managerial strategies for intervention.
Originality/value
This study represents a pioneering attempt to investigate the economic impact of COVID-19 on restaurant businesses.
Display omitted
•A full-scale project was operated for sludge fermentation to produce VFAs.•Sludge reduce, carbon recovery and nutrient removal were simultaneously improved.•A very high solid content ...of 7% was adopted in sludge fermentation.•VFAs from sludge meets requirement for upgrading nutrient removal of wastewater.•This project presents greater economic advantage than biogas production process.
A full-scale project of thermal-alkaline pretreatment and alkaline fermentation of sewage sludge was built to produce volatile fatty acids (VFAs) which was then used as external carbon source for improving biological nitrogen and phosphorus removals (BNPR) in wastewater plant. Results showed this project had efficient and stable performances in VFA production, sludge reduce and BNPR. Hydrolysis rate in pretreatment, VFAs yield in fermentation and total VS reduction reached 68.7%, 261.32 mg COD/g VSS and 54.19%, respectively. Moreover, fermentation liquid with VFA presented similar efficiency as acetic acid in enhancing BNPR, obtaining removal efficiencies of nitrogen and phosphorus up to 72.39% and 89.65%, respectively. Finally, the project also presented greater economic advantage than traditional processes, and the net profits for VFAs and biogas productions are 9.12 and 3.71 USD/m3 sludge, respectively. Long-term operation indicated that anaerobic alkaline fermentation for VFAs production is technically and economically feasible for sludge carbon recovery.
•Large amounts of HAs were released from sludge during THP.•Structural characteristics of HAs were altered during THP.•Influences of HAs on sludge digestion varied with the concentration and ...structure.•HAs inhibited sludge hydrolysis but improved methanogenesis at low concentration.
Humic-like acids (HAs) are abundant in sewage sludge but mainly bonded with solids. Thus, their influences are often neglected in conventional digestion processes. Currently thermal hydrolysis pretreatment (THP) has been widely adopted in sludge anaerobic digestion (AD) to enhance hydrolysis of complex matters and further to improve methane production. However, the impacts of enhanced release of HAs and the mechanisms involved are not well understood and need to be further investigated because the substantial amounts of HAs present in AD could severely threaten the sludge AD processes. Results in the present study indicated that the concentration of soluble HAs in sludge was elevated by 90 times due to the THP, from 8 mg/L in raw sludge to 727 mg/L in the pretreated sludge hydrolyzed at 180 °C. Moreover, the structural characteristics of soluble HAs, including aromatic condensation degree, elemental composition and functional group, also showed substantial differences with the increased temperature of the THP. Furthermore, the release of HAs presented significant influences on sludge digestion. Acidification rate was inhibited by over 50% with 0.4 g/L of HAs, whereas methanogenesis was improved by nearly 200% with 0.8 g/L HAs and inhibited about 50% with 2.0 g/L. The activities of proteinase and co-enzyme F420 were decreased by 20% and increased by 19%, respectively, under HAs stress at 0.6 g/L for 5 days. Moreover, molecular structural changes of soluble HAs also contributed to the influences. Especially, the E4/E6 value representing the degree of HAs aromatic condensation and C/N ratio of soluble HAs were closely correlated with their inhibition degree to sludge hydrolysis. The findings of this study demonstrate that the influences of HAs are evident and also vary to the different steps of anaerobic digestion processes, which shall not be negligible during the sludge digestion that is with THP. Due to the rate-limiting step was methanogenesis in the AD process of pretreated sludge by thermal hydrolysis, HAs concentration was recommended at low level, for example around 1.0 g/L, to accelerate or not limit methanogenesis.
Display omitted
COVID-19 has become a global pandemic and there is an urgent call for developing drugs against the virus (SARS-CoV-2). The 3C-like protease (3CL
pro
) of SARS-CoV-2 is a preferred target for broad ...spectrum anti-coronavirus drug discovery. We studied the anti-SARS-CoV-2 activity of S. baicalensis and its ingredients. We found that the ethanol extract of S. baicalensis and its major component, baicalein, inhibit SARS-CoV-2 3CL
pro
activity in vitro with IC
50
's of 8.52 µg/ml and 0.39 µM, respectively. Both of them inhibit the replication of SARS-CoV-2 in Vero cells with EC
50
's of 0.74 µg/ml and 2.9 µM, respectively. While baicalein is mainly active at the viral post-entry stage, the ethanol extract also inhibits viral entry. We further identified four baicalein analogues from other herbs that inhibit SARS-CoV-2 3CL
pro
activity at µM concentration. All the active compounds and the S. baicalensis extract also inhibit the SARS-CoV 3CL
pro
, demonstrating their potential as broad-spectrum anti-coronavirus drugs.
Display omitted
•Anaerobic digesters with varied GAC dosages were compared at low and high OLRs.•Methanogenic degradation of acetate was almost unaffected by GAC addition.•GAC dose-dependent ...enhancing effect was found for syntrophic HPr/HBu degradation.•GAC stimulated the enrichment of syntrophic bacteria.
Granular activated carbon (GAC) could promote methane production from organic wastes, but a wide range of dosages has been reported. In present study, different GAC dosages of 0, 0.5, 5 and 25 g/L were supplemented into anaerobic digesters and the methanogenic degradation kinetics of acetate, propionate and butyrate were characterized, respectively. At high organic load of 5 g/L, the degradation rates of propionate and butyrate increased by 1.5–4.7 and 2.5–7.0 times at varied GAC dosages. The methane production rates (Rmax) from propionate and butyrate were significantly elevated when increasing GAC dosage up to 5 g/L. However, only a minor increment was found for acetate degradation either at 1 g/L or 5 g/L. The stimulatory mechanism of GAC for accelerated syntrophic degradation of propionate and butyrate can be primarily attributed to the triggering effect on acetogenesis, as evidenced by the enrichment of syntrophic bacteria e.g. Thermovirga, Synergistaceae, and Syntrophomonas etc.
This brief considers the problem of trajectory tracking control for marine surface vessels with unknown time-variant environmental disturbances. The adopted mathematical model of the surface ship ...movement includes the Coriolis and centripetal matrix and the nonlinear damping terms. An observer is constructed to provide an estimation of unknown disturbances and is applied to design a novel trajectory tracking robust controller through a vectorial backstepping technique. It is proved that the designed tracking controller can force the ship to track the arbitrary reference trajectory and guarantee that all the signals of the closed-loop trajectory tracking control system of ships are globally uniformly ultimately bounded. The simulation results and comparisons illustrate the effectiveness of the proposed controller and its robustness to external disturbances.
Cyclophilins, a type of peptidyl-prolyl cis-trans isomerase, function as important molecular chaperones in a series of biological processes. However, the expression pattern and signal transduction ...pathway of cyclophilins are still unclear. Here, we showed that the promoter of OsCYP2 could function as a tissue-specific promoter by GUS staining. Moreover, we found that the promoter sequence contained not only core elements but also inducible elements. Then, the ABA-responsive element was used for cDNA library screening, and the transcription factor MYC2-like was identified by a yeast one-hybrid assay and confirmed through an electrophoretic mobility shift assay. Furthermore, the relative expression showed that MYC2-like was induced by abscisic acid. In addition, MYC2-like overexpression enhanced salt tolerance in transformants and partially restored the cyp2-RNAi line. In summary, we explored a novel transcriptional signal mediated by MYC2-like, a potential regulator of salt stress-related physiological processes in rice.
Respiratory syncytial virus (RSV) is one of the important pathogenic agents of pediatric respiratory tract infection. Weighted gene co-expression network analysis (WGCNA) is used to study autoimmune ...diseases, which can find potential hub genes. The diagnostic model based on hub genes and machine learning makes it possible to diagnose the extracellular immune response to RSV infection early.
The aim of the present study was to identify potential immune, diagnose and treatment related genes expressed in RSV-infected cells.
Firstly, gene expression data were downloaded from the Gene Expression Omnibus (GEO) to identify differentially expressed genes (DEGs). Secondly, WGCNA was performed based on DEGs to obtain hub genes related to immunity score. Thirdly, protein-protein interaction (PPI) and the immune infiltration analysis of hub immune related genes were performed. Finally, diagnostic and immune related genes were identified by machine learning, followed by functional analysis.
Totally, 2063 DEGs were identified in the extracellular immune response to RSV infection. Among which, 10 key immune and diagnosis related genes were identified, including ITGA2B, GP9, ITGB3, SELP, PPBP, MPL, CXCL8, NFE2, PTGS1 and LY6G6F. Several immune/diagnosis related gene-immunocyte subtype networks were identified, such as CXCL8-Type 17 T helper cell, LY6G6F-CD56 bright natural killer cell, PPBP-activated CD4 T cell/T follicular helper cell, NFE2/PTGS1/SELP-activated dendritic cell, GP9/ITGA2B/MPL-activated CD8 T cell. ITGB3, MPL and PTGS1 could be considered as therapeutic targets. Some significantly enriched signaling pathways were identified, including hematopoietic cell lineage (involving GP9 and ITGA2B), cytokine-cytokine receptor interaction (involving MPL), chemokine signaling pathway (involving PPBP) and arachidonic acid metabolism (involving PTGS1).
The 10-immune related gene signature may be used as potential diagnostic markers for the extracellular immune response to RSV infection, which may provide a new field in searching for diagnostic and therapeutic molecules in the extracellular immune response to RSV infection.
•Higher VFAs yield was observed at neutral pH for heat-alkaline pretreated sludge.•Higher VFAs yield was obtained at alkaline pH for raw sludge.•Neutral pH is suitable for acidogenesis ...process.•Alkaline pH is suitable for hydrolysis process.•Alkaline fermentation results in low microbial richness.
In this study, the anaerobic fermentation was carried out for volatile fatty acids (VFAs) production at different pH (between 7.0 and 10.0) conditions with untreated sludge and heat-alkaline pretreated waste activated sludge. In the fermentation with untreated sludge, the extent of hydrolysis of organic matters and extent of acidification at alkaline pH are 54.37% and 30.37%, respectively, resulting in the highest VFAs yield at 235.46mg COD/gVS of three pH conditions. In the fermentation with heat-alkaline pretreated sludge, the acidification rate and VFAs yield at neutral pH are 30.98% and 240.14mg COD/gVS, respectively, which are higher than that at other pH conditions. With the glucose or bovine serum albumin as substrate for VFAs production, the neutral pH showed a higher VFAs concentration than the alkaline pH condition. The results of terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that the alkaline pH caused low microbial richness. Based on the results in this study, we demonstrated that the alkaline pH is favor of hydrolysis of organic matter in sludge while neutral pH improved the acidogenesis for the VFAs production from sludge. Our finding is obvious different to the previous research and helpful for the understanding of how heat-alkaline pretreatment and alkaline fermentation influence the VFAs production, and beneficial to the development of VFAs production process.
PDF
