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A novel framework for systematic propositional formula simplification based on existential graphs
No full textThis paper presents a novel simplification calculus for propositional logic derived from Peirce’s existential graphs’ rules of inference and implication graphs. Our rules can be applied to propositional logic formulae in nested form, are equivalence-preserving, guarantee a monotonically decreasing number of variables, clauses and literals, and maximise the preservation of structural problem information. Our techniques can also be seen as higher-level SAT preprocessing, and we show how one of our rules (TWSR) generalises and streamlines most of the known equivalence-preserving SAT preprocessing methods. In addition, we propose a simplification procedure based on the systematic application of two of our rules (EPR and TWSR) which is solver-agnostic and can be used to simplify large Boolean satisfiability problems and propositional formulae in arbitrary form, and we provide a formal analysis of its algorithmic complexity in terms of space and time. Finally, we show how our rules can be further extended with a novel n-ary implication graph to capture all known equivalence-preserving preprocessing procedures
Exploring productivity hotspots in the Precambrian biosphere
No full textEarth’s earliest biosphere was likely limited by metabolic energy. Nutrient limitation, which imparts a strong control on productivity today, only began with the origin of oxygenic photosynthesis ca 3 billion years ago (Ga). This contribution builds upon these concepts to explore how the spatial distribution of primary producers evolved across this transition from energy- to nutrient-limited. While on the modern Earth hotspots of primary productivity are centred around deep-marine upwelling zones and estuaries, preliminary calculations suggest that the early chemotrophic biosphere may have been fuelled by hydrothermal injections of H2 and Fe2+, making volcanically active basins at least 2–8 times more productive relative to background. The rise of oxygenic photosynthesis in the Neoarchean likely enabled the expansion of primary producers into freshwater habitats, which provided nutrients by weathering and perhaps boosted biological diversification. In the Proterozoic, when the deep ocean was nutrient-depleted, primary productivity was probably clustered around estuarine settings, where it may have been enhanced by a factor of 3–25. In conclusion, the spatial distribution of primary producers has likely evolved over the past 4 billion years. Accounting for this trend may help identify biogeochemical limits and opportunities in future studies of the early Earth and other habitable words.This article is part of the discussion meeting issue ‘Chance and purpose in the evolution of biospheres’
Sensory reading practices:touching the pages of Manchester John Rylands Library MS French 1
No full textThe touches and abrasions to miniatures in Manchester, John RylandsLibrary MS French 1 can be read as emotional glosses to the manuscriptthat physically communicate an early audience’s responses to significantcharacters and/or events. Each abraded image thus tells two narratives:the story as illustrated in the miniature, and the narrative of a previousreader’s reaction to it
Familiarity breeds confidence:creating effective digital literacy resources for older adults
No full textAs population ageing is observed globally, and technology continues to expand into most parts of our lives, many older adults face challenges in adapting to a world that they feel unprepared to inhabit — one filled with increasingly intertwined and fast-evolving technologies that have become necessary to fully participate in society. The age-related digital divide, caused by the gaps in access, motivation and skills of many older adults to use digital technologies compared to younger people, is now a significant problem for the wellbeing and independence of older adults and requires urgent solutions. Increasing the digital literacy and confidence of older adults may help reduce this gap. However, effective strategies for improving digital literacy in later life must take into account the needs and preferences of older learners. This paper reports on two pilot studies conducted to create and evaluate prototype digital literacy resources to discover effective forms and content. This wo rk draws from literature, related work, and feedback on our prototypes from older adults in local communities. Our findings indicate that older adults often prefer device and task-specific digital literacy resources in printed form as a familiar medium before progressing to digital learning, and value community involvement in ongoing support for the learning process. Resources that use figure-of-speech based language and informative diagrams can also be beneficial to older adults, particularly when learning novel digital tasks. These preliminary insights also highlight the potential for conflicting requirements from a diverse demographic and the need for further exploration of the topi
The role of vision science in understanding animal camouflage
No full textAnimal camouflage in the natural world has been studied for over a century, with early research often relying on descriptive accounts of patterning as perceived by human observers. Recent advances, however, have leveraged a deeper understanding of visual processing across a wide range of predators. In this review, we examine literature illustrating how insights from vision science have enriched research on camouflage. We focus on three primary areas: colour and pattern processing, motion processing, and the perception of shape and depth. We discuss findings from vision research that show how animals seeking to remain undetected optimise their camouflage to deter adversaries. We also explore how predator visual systems have evolved to break that camouflage. Lastly, we highlight gaps where vision science has yet to be applied to research on camouflage, with the hope of encouraging further interdisciplinary work
What is provisional possession?
No full textThe concept of provisional possession in Kant presents a significant interpretative challenge. Scholars agree that prior empirical possession must be rationalized but have struggled to identify a form of omnilaterality within the state of nature. I propose understanding provisionality through the Pure Concept of Understanding of Possession (PUP) – a unilateral yet normative framework that rationalizes empirical possession based on temporal priority. Possession understood through PUP serves as a precursor to intelligible possession within the state of nature. To support this account, I first demonstrate that intelligible possession starts from empirical possession, thereby requiring an explanation of the transition from the latter to the former. I then argue that provisional possession unfolds in two distinct steps: first, prior empirical possession acquires an empirical title through the postulate of practical reason, which confers normative significance on temporal priority; second, PUP abstracts from empirical conditions, facilitating the progression towards a rational title
Establishing pharmacy perceptions of e-learning format, design and development for general practice continuing professional development in Scotland
No full textBackground: This study explores an important area for Continuing Professional Development in pharmacy education and digital learning. Increased demand has generated the necessity for reviewing e-learning module development that successfully meets user needs and learner experience. Objective: This study investigates learners’ perceptions of standard and segmented e-learning modules and their impact on learner experience to inform future healthcare educational module development. Methods: Semi-structured interviews were conducted with pharmacists (14) and pharmacy technicians (1) on the General Practice Clinical Pharmacist programme. Participants were randomised to either single or segmented module design. Fifteen interviews were conducted and data were thematically analysed. Results: The format allowed for expressing opinions regarding the experience of using the module and highlighted key issues. The analysis identified 125 codes, which resulted in nine themes: Navigation, Interactivity, Structure, Time, Presentation, Resource, Content, Actions and Language. Conclusion: Results reassure educational providers that e-learning modules suit standard or segmented formats. Findings imply that module format is less important than easy-to-use, well-structured modules with high-quality content. Constructive feedback provided potential improvements to usability, which will help focus future resources and development. More work is needed to explore the translation of learning into practice and the benefit of the segmented format for diverse or interprofessional learners
Geometrically inspired kernel machines for collaborative learning beyond gradient descent
No full textThis paper develops a novel mathematical framework for collaborative learning by means of geometrically inspired kernel machines which includes statements on the bounds of generalisation and approximation errors, and sample complexity. For classification problems, this approach allows us to learn bounded geometric structures around given data points and hence solve the global model learning problem in an efficient way by exploiting convexity properties of the related optimisation problem in a Reproducing Kernel Hilbert Space (RKHS). In this way, we can reduce classification problems to determining the closest bounded geometric structure from a given data point. Further advantages that come with our solution is that our approach does not require clients to perform multiple epochs of local optimisation using stochastic gradient descent, nor require rounds of communication between client/server for optimising the global model. We highlight that numerous experiments have shown that the proposed method is a competitive alternative to the state-of-the-art