A Multi-Agent Reinforcement Learning Approach for Efficient Client Selection in Federated Learning

Federated learning (FL) is a training technique that enables client devices to jointly learn a shared model by aggregating locally computed models without exposing their raw data. While most of the existing work focuses on improving the FL model accuracy, in this paper, we focus on the improving the training efficiency, which is often a hurdle for adopting FL in real world applications. Specifically, we design an efficient FL framework which jointly optimizes model accuracy, processing latency and communication efficiency, all of which are primary design considerations for real implementation of FL. Inspired by the recent success of Multi Agent Reinforcement Learning (MARL) in solving complex control problems, we present FedMarl, a federated learning framework that relies on trained MARL agents to perform efficient run-time client selection. Experiments show that FedMarl can significantly improve model accuracy with much lower processing latency and communication cost

A Triangle Hybrid Plasmonic Waveguide with Long Propagation Length for Ultradeep Subwavelength Confinement

Facing the problems of ohmic loss and short propagation length, the application of plasmonic waveguides is limited. Here, a triangle hybrid plasmonic waveguide is introduced, where a cylinder silicon waveguide is separated from the triangle prism silver waveguide by a nanoscale silica gap. The process of constant optimization of waveguide structure is completed and simulation results indicate that the propagation length could reach a length of 510 μm, and the normalized mode area could reach 0.03 along with a high figure of merit 3150. This implies that longer propagation length could be simultaneously achieved along with relatively ultra-deep subwavelength mode confinement due to the hybridization between metallic plasmon polarization mode and silicon waveguide mode, compared with previous study. By an analysis of fabrication errors, it is confirmed that this waveguide is fairly stable over a wide error range. Additionally, the excellent performance of this is further proved by the comparison with other hybrid plasmonic waveguides. Our work is significant to manipulate light waves at sub-wavelength dimensions and enlarge the application fields, such as light detection and photoelectric sensors, which also benefit the improvement of the integration of optical devices

Protective effects of modified UW solution with dexmedetomidine and xenon on swine lung for donation after cardiac death

Objective To explore the protective effects of dexmedetomidine (DEX) and xenon (Xe) modified university of Wisconsin solution (UW solution) in a pig model of lung donation after cardiac death (DCD). Methods Four healthy male mini-musk pigs aged 4-6 months, weighing 13-17 kg, were subjected to cardiac arrest by cis-atracurium infusion and cessation of oxygen supply. After 1 h of warm ischemia (WI), the lungs were harvested and cut into thin slices. Some of the slices served as WI group, while the other slices were preserved in N2/DEX/Xe added 4 types of UW solutions at 4 ℃ for 24 h of cold ischemia (CI). These slices were divided into WI+CI+N2 group, WI+CI+DEX group, WI+CI +DEX +30% Xe group, and WI+CI+DEX+50% Xe group. The above 5 group of tissue slices were stained with HE for pathological score. Apoptosis of pulmonary cells were detected by TUNEL. Western blotting was used to detect the expression of cleaved Caspase-3 and glutathione peroxidase 4 (GPX4). The expression of GPX4 and high mobility group protein 1 (HMGB1) were assessed by immunohistochemical staining. Results Compared with the WI group, the histology of other groups showed no significant damage to alveolar structures. Pulmonary edema and inflammatory cell infiltration were not obvious. The injury score of lung had no significant change in lung tissues of all groups (P>0.05). Compared with the WI group, the number of TUNEL-positive cells and the protein level of cleaved Caspase-3 were increased in the WI+CI+N2 group (P < 0.05). However, the protein level of GPX4 had no significant change in lung tissues of all groups. Compared with the WI group, the protein level of HMGB1 was elevated in the WI+CI+N2 group (P < 0.05). Compared with the WI+CI+N2 group, the number of TUNEL-positive cells was significantly reduced in the WI+CI+DEX group, WI+CI+DEX+30%Xe group and WI+CI+DEX+50%Xe group (P < 0.001, P < 0.05, P < 0.05, respectively). The protein level of HMGB1 was significantly reduced in the WI+CI+DEX+30%Xe group (P < 0.01). Conclusion The UW solution added with DEX alone or in combination with Xe can provide better cell protection on swine DCD lung through inhibiting cell apoptosis, down-regulating expression and restraining cytoplasmic translocation of HMGB1