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Digitisation as archival intermediary: Quantifying and qualifying Greta B. Stevenson's mycological collector networks
No full textSocietal Impact Statement Mass digitisation of natural science collections and archives has increasingly become a priority for scientific heritage institutions. Here, we explore the potential of mass digitisation to improve our understanding of the nature and history of scientific collaboration. Focusing on mycologist Greta B. Stevenson (1911–1990)—a peripatetic researcher whose career alternated between Great Britain and New Zealand—we quantify and qualify the often‐transient nature of scientific networks and collaborations. Through this, we highlight the varied applications of digitised collections data beyond traditional scientific research and emphasise the need for digitisation programmes to shift towards ‘messy’ databases to facilitate these uses. Summary The ongoing digitisation of natural history specimens provides opportunities not just for novel scientific research and discoveries but also for ‘big data’ approaches to the humanities. In particular, it allows for historians of science to build more comprehensive interaction networks of individuals engaged in natural history—including those from marginalised groups who have historically had their contributions and voices hidden. Using data primarily generated from digitisation programmes at the Royal Botanic Gardens, Kew, and the New Zealand Fungarium – Te Kohinga Hekaheka o Aotearoa, in combination with published records and archival documents, we map the collector‐networks of one New Zealand mycologist Greta Barbara Stevenson (1911–1990). In doing so, we highlight her diverse network of collectors and collaborators—obscured by the separation of her collections into two temporally and geographically distinct herbaria—providing biographical information and exploring ways in which the collections inform our understanding of how amateur science functioned during the 20th century at both national and international scales. Finally, through comparing different digitisation practices and projects, we suggest how future projects might be conducted to better facilitate humanities‐focused research
Enhanced visualisation of concealed target objects by infrared thermography and machine learning
No full textElectromagnetic waves such as millimetre-wave, terahertz, and infrared have been extensively employed in security scanning applications due to their non-invasive nature and strong detection capabilities. Millimetre-wave and terahertz imaging systems benefit from longer wavelengths, allowing for deeper penetration through clothing. This has enabled the development of commercial stand-off and walk-through detectors for the identification of concealed items beneath garments. In contrast, infrared radiation, while less penetrative and yielding weaker signals on clothing surfaces, offers significantly higher imaging resolution due to its shorter wavelength. Additionally, infrared cameras are generally more cost-effective, widely available, and well-suited for high-throughput applications over longer distances. In this work, a machine learning-based methodology was applied to thermal infrared images to improve the detection and visualisation of objects concealed under layered clothing. Principal Component Analysis was employed to identify pixels with marked thermal contrast between the subject and the background. This was followed by image segmentation using the Chan-Vese active contour algorithm and region-of-interest clustering using Fuzzy-c means. Finally, image fusion with the corresponding visible spectrum image was performed to enhance the interpretability of the results. Compared to K-means clustering, the proposed Fuzzy-c-based approach demonstrated improved performance in localising concealed objects, such as eliminating low heat signal due to the palm’s residual heat, underscoring the potential of machine learning-enhanced infrared imaging for practical security applications
Genomic and clinical epidemiology of SARS-CoV-2 in Lebanon: a prospective multicenter study 2020-2024.
No full textBACKGROUND: Globally, the trajectory of COVID-19 has been shaped by viral evolution, widespread vaccination and immunity from prior infections. We assessed the epidemiological and clinical patterns of COVID-19 in Lebanon between 2020 and 2024, identified the predominant SARS-CoV-2 clades and evaluated risk factors for COVID-19 associated mortality. METHODS: This multicenter prospective study enrolled 1302 patients hospitalized with COVID-19 in Lebanon between November 2020 and October 2024. Multivariate logistic regression was used to determine predictors of COVID-19 associated mortality. Whole genome sequencing (WGS) was utilized to investigate the genomic epidemiology of SARS-CoV-2 and infer viral interactions between Lebanon and other countries. Multiple sequence alignment and phylogenetic analysis were conducted using the augur pipeline. RESULTS: A progressive and significant reduction in severe outcomes, including pneumonia and mortality was observed throughout the study period. Pneumonia (AOR, 6.714; CI, 4.140-10.888; p < 0.0001) and age ≥ 60 years (AOR, 6.051; CI, 2.190-16.723; p = 0.001) were identified as independent predictors of COVID-19 mortality. Moreover, receiving 3 doses of a COVID-19 vaccine significantly reduced the odds of mortality (AOR, 0.229; CI, 0.108-0.486; p < 0.0001). Genomic analysis revealed multiple introductions of the same SARS-CoV-2 clades into Lebanon, which seeded local transmission chains. CONCLUSIONS: The transition of COVID-19 from pandemic to endemic in Lebanon was associated with reduced disease severity. Vaccination remains essential, particularly in older adult patients who are at high risk of mortality. Moreover, early diagnosis and management of pneumonia are crucial, given its association with COVID-19 mortality. Furthermore, WGS has proven valuable in tracking the local evolution of SARS-CoV-2 and its impact on clinical outcomes
A common framework for semantic memory and semantic composition.
No full textHow the brain constructs meaning from individual words and phrases is a fundamental question for research in semantic cognition, language, and their disorders. These two aspects of meaning are traditionally studied separately, resulting in two large, multi-method literatures, which we sought to bring together in this study. Not only would this address basic cognitive questions of how semantic cognition operates but also because, despite their distinct focuses, both literatures ascribe a critical role to the anterior temporal lobe (ATL) in each aspect of semantics. Given these considerations, we explored the notion that these systems rely on common underlying computational principles when activating conceptual semantic representations via single words, versus building a coherent semantic representation across sequences of words. The present pre-registered study used magnetoencephalography and electroencephalography to track brain activity in participants reading nouns and adjective-noun phrases, while integrating conceptual variables from both literatures: the concreteness of nouns (e.g., "lettuce" vs. "fiction") and the denotational semantics of adjectives (subsective vs. privative, e.g., "bad" vs. "fake"). Region-of-interest analyses show that bilateral ATLs responded more strongly to phrases at different time points, irrespective of concreteness. Decoding analyses on ATL signals further revealed a time-varying representational format for adjective semantics, whereas representations of noun concreteness were more stable and maintained for around 300 ms. Further, the neural representation of noun concreteness was modulated by the preceding adjectives: decoders learning concreteness signals in single words generalised better to subsective relative to privative phrases. These findings point to a unified ATL function for semantic memory and composition
Gravity-dependent rate sensitivity in granular intrusion: microgravity experiments and simulations.
No full textUnderstanding the shear and intrusion rheological behavior of granular materials under reduced gravitational conditions is crucial for applications in planetary exploration and submarine earthquake engineering. To this end, it is important to understand whether gravity affects the drag forces on objects intruding granular media and, if so, quantify these effects. We have studied this issue experimentally in 1 g and 0 g conditions, the latter using the Beijing Drop Tower. Measuring the resistive forces on a cylinder moving at a constant speed through a granular bed, we find that gravity plays a significant role - the resistive forces increase significantly with cylinder speed in 0 g, while increasing much more slowly in 1 g. We use Coupled Eulerian-Lagrangian (CEL) simulations that support our results. We attribute this behavior to the increasingly dominant effect of pressure-sensitive frictional forces in microgravity with increasing fluidity in these conditions. Other than the significant implications for extraterrestrial exploration, our findings suggest that constitutive modeling of flow in microgravity should differ significantly from that in 1 g
Spatial resilience and population replacement in Europe during MIS 3: a comparative study of Neanderthals and H. sapiens
No full textHomo sapiens dispersed out of Africa several times during the Late Pleistocene. The most recent dispersal event, which began around 60,000 years ago, resulted in the permanent establishment of Sapiens populations in Europe, followed by the disappearance of Neanderthals from the archaeological record. Various hypotheses suggest that the process of population replacement in Europe was influenced by climate change, habitat dynamics, demographic processes, and/or competitive exclusion. To test these hypotheses, we use habitat suitability modeling and GIS tools to predict the optimal distribution of Neanderthal and Aurignacian populations in Europe during stadial and interstadial events of Marine Isotope Stage 3 (MIS 3) and reconstruct their regional networks. The models show that while relatively more suitable habitat was available for Homo sapiens under interstadial conditions, both groups were affected by climate change resulting in shifts in the location of optimal regions and concomitant changes in the social networks that connected them.
Our analysis indicates that optimally suitable habitat persisted across the potential ranges of both species despite climate change. Climate stress alone is not indicated as a cause of Neanderthal's extinction, therefore. Several “core” regions are identified that could have sustained a pattern of demographic resilience, allowing populations to rebound and re-expand during climate upturns, notably in southwestern Europe and, in the case of Neanderthals, in southern Iberia. The optimal regions and the networks they form indicate a potential for interaction between Neanderthals and Sapiens across Europe. While their ranges overlap, however, there are subtle differences in habitat preference that mitigate the potential impact of interactions, suggesting that competition for resources may not have been the primary cause of Neanderthal extinction. The results also suggest regional differences in the combination of stressors that could have influenced Neanderthal extinction, with Sapiens potentially playing a more active role in Western Europe, where regional overlaps impinge on the “core” regions. In Southeastern Europe, where regional connection within the Neanderthal network were relatively tenuous, Neanderthal groups may have been more vulnerable to random events and demographic pressures, including genetic assimilation.
A more complex interplay of climate change, population dynamics and demographic factors is suggested to have contributed to the eventual disappearance of the Neanderthals. Ultimately, the study suggests that the process of population replacement in Europe is the result of the complex and regionally differentiated interplay of climate, geography, demography and interspecific interactions rather than a homogeneous, climate-driven process
Seismicity associated with magmatic intrusions: insights from the Reykjanes Peninsula, southwest Iceland
No full textSince the volcanic re-awakening of southwest Iceland’s Reykjanes Peninsula in 2021, there has been significant interest amongst the scientific community in trying to improve our understanding of the processes governing the ongoing eruptions and the magmatic intrusions that precede them. Microseismicity is a powerful lens through which to view these processes, providing the means to track melt movement as it triggers earthquakes in the surrounding crust. This dissertation makes use of an exceptional seismic dataset recorded by the Cambridge seismic network on the Reykjanes Peninsula, supplemented by instruments from several other institutions, which has made the recent series of magmatic intrusions and eruptions among the best
instrumented events of their kind.
In the first part of this dissertation, I analyse the intense seismicity produced during the February - March 2021 Fagradalsfjall dyke intrusion, which preceded the peninsula’s first eruption for almost 800 years. A catalogue of over 80,000 earthquake hypocentres was produced covering the 9.5 km-long two-segment dyke throughout three-week period of dyking. Through a combination of linear regression on subsets of relatively relocated hypocentres; earthquake focal mechanism determination to analyse the geometry and slip of the fault planes in individual earthquakes; and analysis of the orientation of mapped fractures, I infer that pre-existing structures exert primary control on the orientation of dyke-related faulting, almost all of which occurs on approximately north-south striking faults that exhibit right-lateral strike-slip motion.
In the second part of this dissertation, I analyse the February - March 2021 Fagradalsfjall dyke seismicity further by relatively relocating an earthquake catalogue for the full intrusion period. This reveals even greater detail in the propagation and dynamics of the dyke-related seismicity thanks to exceptionally fine spatial and temporal resolution. It also builds on the previous analysis by illuminating, through alignment of hypocentres, an even greater number of north-south striking faults than previously visible. The increased resolution afforded by the fully relocated catalogue also allows the identification of a small swarm of earthquakes with dip-slip faulting mechanisms occurring at∼ 6 km depth during the early stages of the intrusion, which is likely related to the initial opening of the dyke and its earliest propagation within the brittle crust.
In the final part of this dissertation, I apply similar analysis techniques to those previously applied to the study of an inflationary event that occurred in the neighbouring Eldvörp-Svartsengi volcanic system in April - May 2022, believed to be in response to the intrusion of a sill-like layer within a pre-existing mid-crustal magma domain. I produce a catalogue of∼ 15,000 relatively relocated earthquake hypocentres covering the intrusion period and the month prior, from which I manually analyse events selected from structures delineated by alignment of relatively relocated earthquake hypocentres. Fault plane solutions reveal nodal planes which align well with these structures, and also with mapped fractures in their vicinity. I use this to infer that the intrusion is mostly triggering slip on pre-existing structures. I also identify a sharp base to the seismicity, quantified by the decrease in occurrence of earthquakes with depth, with the shallowest point of this base situated above the modelled centre of inflation,∼ 1.5 km below sea level.
These two contrasting case studies provide insight into the strengths and limitations of using microseismicity to inform the properties of different magmatic intrusions on the Reykjanes Peninsula
Household and climate factors influence Aedes aegypti presence in the arid city of Huaquillas, Ecuador.
No full textArboviruses transmitted by Aedes aegypti (e.g., dengue, chikungunya, Zika) are of major public health concern on the arid coastal border of Ecuador and Peru. This high transit border is a critical disease surveillance site due to human movement-associated risk of transmission. Local level studies are thus integral to capturing the dynamics and distribution of vector populations and social-ecological drivers of risk, to inform targeted public health interventions. Our study examines factors associated with household-level Ae. aegypti presence in Huaquillas, Ecuador, while accounting for spatial and temporal effects. From January to May of 2017, adult mosquitoes were collected from a cohort of households (n = 63) in clusters (n = 10), across the city of Huaquillas, using aspirator backpacks. Household surveys describing housing conditions, demographics, economics, travel, disease prevention, and city services were conducted by local enumerators. This study was conducted during the normal arbovirus transmission season (January-May), but during an exceptionally dry year. Household level Ae. aegypti presence peaked in February, and counts were highest in weeks with high temperatures and a week after increased rainfall. Univariate analyses with proportional odds logistic regression were used to explore household social-ecological variables and female Ae. aegypti presence. We found that homes were more likely to have Ae. aegypti when households had interruptions in piped water service. Ae. aegypti presence was less likely in households with septic systems. Based on our findings, infrastructure access and seasonal climate are important considerations for vector control in this city, and even in dry years, the arid environment of Huaquillas supports Ae. aegypti breeding habitat
Groups acting acylindrically on trees
No full textWe develop a notion of groups that act acylindrically and non-elementarily on simplicial trees, which we call acylindrically arboreal groups. We then prove a complete classification of when graph products of groups and the fundamental groups of certain hyperbolic 3-manifolds are acylindrically arboreal, and use these classifications to provide examples of acylindrically hyperbolic groups that have actions on trees but have no non-elementary acylindrical actions on trees
Hierarchical Multi‐Material Architectures With Gradient Design for Dynamic‐Range Flexible Tactile Sensing
No full textABSTRACT Flexible pressure sensors that can simultaneously provide mechanical compliance, a broad detection range, and robust operation under complex loading conditions are highly desired for next‐generation electronic skin (e‐skin) and wearable systems. Herein, we report a hierarchical multi‐material by‐layer sensor (HMBS) based on triply periodic minimal surface (TPMS) architectures, fabricated through an additive manufacturing‐assisted template‐based casting strategy and functionalized with a hierarchical electrically conductive coating. Gyroid and diamond TPMS lattices are combined in a multi‐stacked configuration, with a soft PDMS gyroid layer on top of a stiffer PDMS diamond layer, to introduce a vertical stiffness gradient and graded deformation under compression. The sacrificial ABS moulds, 3D printed from inverse TPMS geometries, allow accurate control of lattice topology while in situ polypyrrole (PPy) polymerization followed by MWCNT dip‐coating forms a conformal 3D conductive coating network throughout the scaffold. The HMBS shows a continuous, non‐saturating piezoresistive response from 3.75 to 375 kPa and remains stable over 4000 loading–unloading cycles across relevant frequencies. We further demonstrate reliable sensing of non‐uniform, localized, and dynamic/vibration‐induced loads, representative of bio‐signal‐like stimuli. These results showcase a hierarchical TPMS‐based platform for architected, multi‐material tactile sensors and provide a scalable design paradigm for bio‐integrated wearables, and human–machine interface platforms