17837 research outputs found
Sort by
A cold but stable 4,200 yr event in Britain and the northeastern Atlantic region
Get PDFThe existence of an abrupt cold event in the British Isles at ca 4200 years before AD1950 (cal. yr BP) is investigated through analysis of the oxygen and carbon isotope value (δ18O and δ13C) of annually laminated, seasonally precipitated lake carbonates from the lake of Diss Mere in eastern England. Modern rainfall and lake water isotope data indicate that evaporation is a major control on the isotope value of modern lake waters, consistent with Diss Mere's current status as a small (0.0034 km2) and shallow (<6m), closed lake system. However, both the characteristics of isotope data from the interval 4700 to 3700 cal yr BP and the greater depth of the lake basin at that time (>15m water) indicates that whilst evaporation still operated, major shifts in δ18O values most likely reflect shifts in patterns of atmospheric circulation (primarily through air mass trajectory, air temperature and precipitation amount). A centennial-scale interval of persistently low δ18O values occurred between ca 4320 and 4210 cal yr BP and is interpreted as a cold event with changes in the elemental composition of the sediments supporting this interpretation. Correlation of this record with other sequences from the North Atlantic and western Europe, either through comparison of independent chronologies or age markers such as the Hekla 4 tephra, indicates that this event was well expressed across this region and was characterised by changes in temperature, storminess and ocean/atmospheric circulation. It is argued that increasing evidence exists for an abrupt event in this region at ca 4200 cal yr BP, but it is the high-resolution nature of the Diss Mere sequence and the regionally extensive tephras that this record contains that allows the timing and character of this event to be understood
The Influence of Human-inspired Agentic Sophistication in LLM-driven Strategic Reasoners
Get PDFThe rapid rise of large language models (LLMs) has shifted artificial intelligence (AI) research toward agentic systems, motivating the use of weaker and more flexible notions of agency. However, this shift raises key questions about the extent to which LLM-based agents replicate human strategic reasoning, particularly in game-theoretic settings. In this context, we examine the role of agentic sophistication in shaping artificial reasoners' performance by evaluating three agent designs: a simple game-theoretic model, an unstructured LLM-as-agent model, and an LLM integrated into a traditional agentic framework. Using guessing games as a testbed, we benchmarked these agents against human participants across general reasoning patterns and individual role-based objectives. Furthermore, we introduced obfuscated game scenarios to assess agents' ability to generalise beyond training distributions. Our analysis, covering over 2000 reasoning samples across 25 agent configurations, shows that human-inspired cognitive structures can enhance LLM agents' alignment with human strategic behaviour. Still, the relationship between agentic design complexity and human-likeness is non-linear, highlighting a critical dependence on underlying LLM capabilities and suggesting limits to simple architectural augmentation
Written evidence to the Northern Ireland Affairs Committee Inquiry on Policing and Security in Northern Ireland.
Get PDFThis submission provides responses to the Northern Ireland Affairs Committee’s ‘Policing and security in Northern Ireland’ inquiry evidence call. It focuses on two questions:a. What are the risks and opportunities associated with a process for the disbandment of paramilitary groups which the forthcoming independent scoping exercise should consider?b. What lessons should be learnt from previous attempts at paramilitary disbandment?<br/
Optimal Threshold Singular Spectrum Analysis for Efficient Electrocardiogram Interference Removal
Get PDFSingular Spectrum Analysis (SSA) has become well known for its ability to effectively separate mixtures of signals with overlapping spectral content but with different statistical natures. In this paper, we show how a new approach to grouping the singular values that efficiently denoise biomedical signals, specifically, mixtures of Electrocardiogram and Electromyogram signals. It is based on optimal Singular Value Hard Thresholding (SVHT) but for signals that are periodic or quasi-periodic in nature. An optimal thresholding technique can provide similar results with much smaller trajectory matrices and thus significantly reduced computational burden. The resultant Singular Value Decomposition process is significantly faster and shows similar performance to kurtosis based sliding SSA with a reduction in computational complexity of the order of 12,500 times. This technique is well suited to real-time implementation for de-noising biomedical signals on the fly
Adult belief change: New theoretical and empirical perspectives.:Special issue introduction
Get PDFBelief change in later life is understudied as it goes against the well-established idea that political attitudes are formed early on in life and remain mostly stable thereafter. Recently, some studies have emerged that address adult belief change. However, these studies are mostly descriptive and offer relatively little insight into how, for whom, and under which conditions adult belief change takes place. This special issue on adult belief change addresses new theoretical and methodological perspectives and sets the agenda for future research on this highly relevant theme. Together, the special issue contributions provide robust evidence for changing beliefs well into adulthood. This implies that attitudes are not as fixed or settled as previously thought. A better understanding of the processes of adult belief change is vital to understand the social and psychological aspects of national and international political developments, especially in the current context of ongoing political change. The works presented in this special issue form an important starting point for further advancing research in this direction
An activities expansion of the transition polynomial of a multimatroid
Get PDFThe weighted transition polynomial of a multimatroid is a generalization of the Tutte polynomial. By defining the activity of a skew class with respect to a basis in a multimatroid, we obtain an activities expansion for the weighted transition polynomial. We also decompose the set of all transversals of a multimatroid as a union of subsets of transversals. Each term in the decomposition has the structure of a boolean lattice, and each transversal belongs to a number of terms depending only on the sizes of some of its skew classes. Further expressions for the transition polynomial of a multimatroid are obtained via an equivalence relation on its bases and by extending Kochol's theory of compatible sets.We apply our multimatroid results to obtain a result of Morse about the transition polynomial of a delta-matroid and get a partition of the boolean lattice of subsets of elements of a delta-matroid determined by the feasible sets. Finally, we describe how multimatroids arise from graphs embedded in surfaces and apply our results to obtain an activities expansion for the topological transition polynomial. Our work extends results for the Tutte polynomial of a matroid
The phonological store of working memory:A critique and an alternative, perceptual-motor, approach to verbal short-term memory
Get PDFA key quality of a good theory is its fruitfulness, one measure of which might be the degree to which it compels researchers to test it, refine it, or offer alternative explanations of the same empirical data. Perhaps the most fruitful element of Baddeley and Hitch’s (1974) Working Memory framework has been the concept of a short-term phonological store, a discrete cognitive module dedicated to the passive storage of verbal material that is architecturally fractionated from perceptual, language, and articulatory systems. This review discusses how the phonological store construct has served as the main theoretical springboard for an alternative perceptual-motor approach in which serial recall performance reflects the opportunistic co-opting of the articulatory planning system and, when auditory material is involved, the products of obligatory auditory perceptual organisation. It is argued that this approach, which rejects the need to posit a distinct short-term store, provides a better account of the two putative empirical hallmarks of the phonological store—the phonological similarity effect and the irrelevant speech effect—and that it shows promise too in being able to account for nonword repetition and word-form learning, the supposed evolved function of the phonological store. The neuropsychological literature cited as strong additional support for the phonological store concept is also scrutinised through the lens of the perceptual-motor approach for the first time and a tentative articulatory-planning deficit hypothesis for the ‘short-term memory’ patient profile is advanced. Finally, the relation of the perceptual-motor approach to other ‘emergent-property’ accounts of short-term memory is briefly considered
Hyperbolic Adversarial Learning for Personalized Item Recommendation
Get PDFPersonalized recommendation systems are indispensable intelligent components for social media and e-commerce. Traditional personalized item recommendation models are vulnerable to adversarial perturbations, resulting in poor robustness. Although adversarial learning-based recommendation models are able to improve the robustness, they inherently model the interaction relationships between users and items in Euclidean space, where it is difficult for them to capture the hierarchical relationships among entities. To address the above issues, we propose a hyperbolic adversarial learning based personalized item recommendation model, called HALRec. Specifically, HALRec models the interactions in hyperbolic space and utilizes hyperbolic distances to measure the similarities among entities. Moreover, instead of in Euclidean space, HALRec exploits the adversarial learning technique in hyperbolic space, i.e., HAL-Rec maximizes the hyperbolic adversarial perturbations loss while minimizing the hyperbolic based Bayesian personalized ranking loss. Hence, HALRec inherits the advantages of hyperbolic representation learning in capturing hierarchical relationships and adversarial learning in enhancing the robustness of the recommendation model. In addition, we utilize tangent space optimization to simplify the learning of model parameters. Experimental results on real-world datasets show that our proposed hyperbolic adversarial learning-based personalized item recommendation method outperforms the state-of-the-art personalized recommendation algorithms
Speed vs Accuracy in Goal Recognition for Time-Sensitive Applications: a Game-Theoretic Approach
Get PDFThis work addresses a specific case of Goal Recognition (GR), wherea malicious actor (the attacker) seeks to reach and damage one ofseveral sensitive targets, while the observer (the defender) mustidentify the attacker’s target and allocate limited resources to pro-tect it. Focusing on real-world physical and cyber security scenarios,the defender faces a trade-off between acting early, with limited in-formation, or waiting for more data but risking insufficient time todefend. Our contributions include introducing a game-theoretic for-mulation of this instance of GR, which captures the time-sensitivenature of these scenarios, and providing an efficient method tocompute Nash equilibria using the fictitious play learning scheme.Experimental results confirm that our method equips the defen
Data sources:
Access Repository Dashboard
Do you manage Royal Holloway - Pure? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!