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Decentralized Reinforcement Learning for Cooperative Multi-Robot Navigation
No full textCooperative multi-robot navigation requires large teams of robots to reach individual goals without collisions in shared spaces, which is a challenge compounded by partial observability, dynamic interactions, and the combinatorial nature of joint decision-making. Centralized methods provide optimality but fail to scale, while decentralized approaches offer efficiency yet often suffer from deadlocks and weak cooperation. To overcome these limitations, we propose a decentralized reinforcement learning framework that integrates a dual-head soft actor-critic architecture with selective graph-attention communication and task-specific reward shaping. A compact encoder processes a novel observation representation that combines local fields of view, goal projections, and directional heuristics, enabling scal-able awareness under limited sensing. Heuristic and blocking rewards further accelerate convergence and promote cooperative navigation in congested regions. Extensive experiments on grid environments of varying sizes and robot densities show that our method achieves faster convergence, higher success rates, and stronger scalability than state-of-the-art methods in this domain
The Horizons of Medieval French and Occitan: New Approaches to Manuscripts and Texts
No full textThis volume celebrates Simon Gaunt’s scholarship by exploring the current boundaries and future directions of medieval French and Occitan literary criticism. The essays address questions of vital importance to these disciplines, including: What are the literary cultures and identities associated with supralocal vernacular languages? How do medieval manuscripts construct authorship, gendered identity, and voice in ways that range across genres and expressive registers? How do such codices mediate sensory experience and connect the textual, the visual, and the aural? How do French and Occitan texts negotiate the agencies of human and nonhuman bodies, and theorize emotions, sacrifice, and affect?Contributors are William Burgwinkle, Philippe Frieden, Jane Gilbert, Miranda Griffin, Alice Hazard, Thomas Hinton, Melek Karataş, Sarah Kay, Matthew Siôn Lampitt, Catherine Léglu, Peggy McCracken, Robert Mills, David Murray, Linda Paterson, Karen Pratt, Henry Ravenhall, and Simone Ventura
Well-posedness of coupled Navier-Stokes and advection-diffusion equations for propagation of reaction fronts in viscous fluids
No full textIn this paper, we investigate a steady system used for modelling propagation of reaction fronts in viscous fluids subject to a generalized Arrhenius law. The model consists of the incompressible Navier-Stokes equations for the fluid flow and a set of advection-diffusion equations for the temperature and degree of conversion. The resulting system is strongly coupled and presents many additional nonlinearities as the physical parameters such as the viscosity, diffusion and source terms are assumed to depend on the temperature and/or degree of conversion. Using a fixed-point method we prove the existence and uniqueness of the weak solution for the considered problem. To solve the associated fixed-point problem we consider an iterative scheme and its convergence is also studied in the present study. Here, the proposed scheme uncouples the computation of velocity, temperature and degree of conversion using the fixed-point iteration and we theoretically establish its convergence towards the unique solution of the considered model. Numerical results obtained for two test examples are presented to verify the theoretical analysis and to assess the performance of the proposed algorithm. The obtained computational results for both examples support the theoretical expectations for a good numerical convergence with the developed estimates
Revealing Ambipolar Charge Transport in BTBT‐Based D–A–D Molecules via Photo‐MIS‐CELIV Measurements
Get PDF[1]Benzothieno[3,2‐b][1]benzothiophene (BTBT) and its tetraoxide derivative [1]benzothieno[3,2‐b]benzothiophene‐tetraoxide (BTBTOx4) are among the most interesting planar building blocks for constructing p‐type and n‐type transporting materials for organic optoelectronic devices. Herein, we report a study of six recently synthetized small molecules, namely PTz2‐BTBT, PTz2‐BTBTOx4, MPA2‐BTBT, MPA2‐BTBTOx4, POCz2‐BTBT, and POCz2‐BTBTOx4, designed as donor–acceptor–donor (D–A–D) structures. These compounds combine BTBT and BTBTOx4 as electron‐accepting fused‐ring cores with phenothiazine, bis(4‐methoxyphenyl)amine, and 3,6‐bis(4‐(octyloxy)phenyl)‐9H‐carbazole as electron‐donating end groups. The differences in electrochemistry, electronic molecular structures, and charge carrier mobilities of the six compounds are systematically studied. BTBTOX4‐based compounds exhibit an ambipolar character and can serve as effective electron‐ and hole‐transport materials for organic‐based devices, showing also higher conductivity compared to the BTBT counterpart. On the contrary, the BTBT‐based compounds show mainly a hole transport behavior but higher mobility
History of luminescence dating from an instrumentation perspective
Get PDFLuminescence dating has developed over the last ∼60 years as a powerful technique for placing environmental and anthropogenic change into a secure temporal framework. However, over time, many have forgotten, or were never introduced to, the history of how of the method developed, particularly the role of unique instruments built in-house that enabled key methodological advances. In this paper we provide a concise history of the technique’s evolution, drawing on our own experiences
Institutionalisation and market integration in the archaic Greek economy. Modelling overseas trade from the distribution pattern of Samian transport amphoras
No full textThis article advances the view that there was widespread institutionalisation in the early Greek economy right from the end of the eighth century BCE. Challenging the widespread assumption that Mediterranean market integration crystallised much later and only by the end of the ‘archaic period’, agent based modelling is used here alongside the archaeological distribution of Samian transport amphoras to demonstrate the co-ordination that must have existed between trade partners in shipping olive oil from one corner of the Mediterranean to the other. ‘Brownian flow’ models of randomised drift fail to properly reproduce the amphora pattern, while a network of trade hubs stretching from the Black Sea to the shores of modern-day Spain provides a much more robust solution. While these results shed some light on the navigation of various environmental niches and on the lived experience of the sailors distributing products like Samian olive oil, the most important implication of this analysis is that the early Greek economy was more organised —and earlier, too— than we have previously suspected
Narrow-spectrum drug repurposing: targeting Gardnerella vaginalis biofilms associated with bacterial vaginosis.
Get PDFBacterial vaginosis (BV) is the most common vaginal disorder in women of reproductive age. Current therapies are limited by poor activity against biofilms and high recurrence rates (>50%), demonstrating that new antimicrobials are required. Drug repurposing is an attractive approach for the discovery of new antimicrobials, so we aimed to screen repurposed libraries for activity against the key BV pathobiont Gardnerella vaginalis. Two drug libraries from Medicines for Malaria Venture comprising 640 compounds were screened against G. vaginalis and various Lactobacilli species. Initial screening identified 16 G. vaginalis-selective compounds, of which 10 showed ≥90% inhibition of planktonic growth whilst sparing Lactobacillus crispatus. Subsequent assays revealed that three candidates displayed activity against pre-formed G. vaginalis biofilms; MMV1634360 (an antiproliferative compound with reported anticancer and antifungal activity), MMV1582487 (originally developed as an Escherichia coli aminopeptidase N inhibitor) and MMV1582497 (a thymidylate kinase inhibitor developed for Mycobacterium tuberculosis). All three produced >2-log reduction in viable cell counts at 10 µM (p4log10 CFU/mL reduction in viable cell counts at 10 µM (p<0.001), and synergy with existing antibiotic therapy. We demonstrate that MMV1582487 is a selective, non-cytotoxic, anti-biofilm candidate against G. vaginalis, supporting it's potential as a novel therapeutic option for BV. [Abstract copyright: © The Author(s) 2026. Published by Oxford University Press on behalf of Applied Microbiology International.
Magnetically reconfigurable multistable ribbon arrays for liquid manipulation
Get PDFLiquid manipulation at the micro- to millimeter scale has usage in applications such as programmable fluidic circuits, capillary-driven machines, and digital-droplet-based diagnostics. Existing strategies face limitations in achieving complex, programmable fluid control, as static surfaces are locked into a single, permanent function and cannot adapt to changing tasks, while actively reconfigured systems often require continuous energy input. A promising direction involves structures with multiple stable states, such as bistable structures that can maintain one of two configurations without persistent power. In this work, we present magnetically programmable multistable structures that offer three or more stable states, enabling on-demand, reconfigurable fluid control. We built an array of segmented ribbons that can switch between distinct stable shapes under an external magnetic field. By altering the geometry of the array, the system can direct fluid flow along different pathways
TutorLLM: Customizing Learning Recommendations with Knowledge Tracing and Retrieval-Augmented Generation
Get PDFThe integration of AI into education enables more flexible and effective learning. Large Language Models (LLMs) such as ChatGPT offer broad topic coverage but lack personalization and may generate irrelevant or inaccurate content. To address these challenges, we propose TutorLLM, a personalized learning system that combines Knowledge Tracing (KT) and Retrieval-Augmented Generation (RAG). TutorLLM tailors responses based on each student’s learning state, predicted by the MLFBK KT model, and improves relevance using a Scraper component for context retrieval. Implemented as a Chrome plugin, TutorLLM was evaluated in a two-week field study with undergraduate students, demonstrating a 10% increase in user satisfaction and a 5% improvement in quiz scores compared to general LLMs
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