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Tree diversity is changing across tropical Andean and Amazonian forests in response to global change
Get PDFClimate and atmospheric changes are impacting forest function and structure worldwide, but their effects on tropical forest diversity are unclear. Nowhere is the scientific challenge greater than in the Andes and the Amazon, which together include the world’s most diverse forests. Here, using 406 permanent plots spanning four decades of intact lowland and montane forest dynamics, we test for long-term change in species richness and assess the influence of climate and other variables. We show that, at a continental scale, species richness appears stable, but this masks substantial regional variation. Species richness increased in Northern Andean and Western Amazon plots, yet declined in the Central Andes, Guyana Shield and Central-Eastern Amazon. Overall, warmer, drier and more seasonal forests lost species, while those at higher elevations, in less fragmented areas and with faster rates of tree turnover experienced increases. Region-specific drivers, particularly precipitation seasonality and demographic factors, modulated these trends. The results highlight the diverse ways in which Amazon–Andes forests are changing and underscore the critical need to preserve large-scale ecosystem integrity to maintain local tree diversity. By doing so, Northern Andean forests in particular could serve as an important refuge for species increasingly displaced by climate change
Mass violence, age and gender in the Early Iron Age of the Carpathian Basin
No full textNarratives about the motivations and conditions for mass violence as a persistent feature of conflict throughout human history have evolved in complexity and materiality. Victims of these events are key for understanding the evolution and transformative power of violent behaviour as it developed from simple inter-group conflict to more strategic mass violence. Here we present the results of a bioarchaeological study of 77 and biomolecular analysis of 25 individuals from a 9th century BCE mass grave from Gomolava in the Carpathian Basin, Southeast Europe. The site is located at the interface of complex socio-spatial relations, divergent cultural traditions and values, and competing ideologies of landscape use. Here we show that excessive lethal violence enacted mostly on women and children suggests a selective demographic bias. The people buried together shared few, even distant, genetic relationships, and so their killing presents striking evidence for an episode of cross-regional conflict and an underlying aggressive shift in power, violence and gender relations in the region. Gomolava provides evidence for the deliberate annihilation of select sections of a regional population as a motivation for mass violence behaviour in later prehistoric Europe. It also shines new light on the socioeconomic agency and importance of women and young individuals in later European prehistory
From microstructure to arrhythmia: structural drivers of re‐entrant activity in atrial fibrillation
No full textMisfits in the Polish Carpathians: Pastoralism, property, and spatial justice beyond redistribution
Get PDFIn this article, I examine the demand for spatial justice among shepherds in Highland Poland, focusing on the ‘misfit’ between the mobile, communal nature of traditional pastoralism and the static perceptions of landscape and property underpinning Polish and European agricultural policy. The movement of animals and people through a mountain environment increasingly dominated by infrastructure, private property and commercial activity, creates considerable social and spatial friction in Highland communities. Drawing on the work of legal scholar Andreas Philippopoulos-Mihalopoulos, I show how shepherds seek to address these frictions by lobbying for greater political and legal recognition of their right to move through the landscape. In this way, I argue, they propose an alternative vision of spatial justice as based in and enacted through custodianship and mobility, challenging dominant ideas of spatial justice based on property rights and resource redistribution
Altered Brain Structure in an ATRX ‐Deficient Mouse Model of Autism Spectrum Disorder
Get PDFLay Summary: Changes in a gene called ATRX are known to affect brain development and are linked to intellectual disability and autism. In our previous work, we found that removing this gene early in brain development caused mice to show behaviors like those seen in people with autism. In this study, we used detailed brain scans to see if these behavioral changes were linked to differences in brain structure. We found that male mice without ATRX had smaller brains and bodies, while female mice did not show the same brain size reduction. However, both male and female mice had smaller areas of the brain important for memory and movement, and larger areas involved in thinking and sensing. We also saw changes in parts of the brain where ATRX was still present, suggesting that early changes in one area can affect how the whole brain develops. These findings help us understand how early disruptions in brain development might lead to autism‐related behaviors
Do more school resources increase learning outcomes? Evidence from an extended school-day reform
No full textWe evaluate a large-scale government reform in Peruvian public secondary schools that lengthened the school day and invested in pedagogy, staffing, and infrastructure. Using a fuzzy regression discontinuity design, we find that the program increased math and reading test scores by approximately 0.185 SD and 0.1023 SD, respectively. For math only, we estimate that instructional time contributes approximately two-thirds of the effect, suggesting the importance of complementary inputs. The reform effectively enhanced school resources and increased students’ overall study time. Relative to other education interventions in Lowand Middle-Income Countries, the program delivered above-average learning gains but was relatively expensive
Insights into blood donor screening for occult hepatitis B virus infection
Get PDFOccult hepatitis B virus (HBV) infection remains a risk to the blood supply. Prevention of transmission by transfusion requires a numerous set of tests, including surface antigen, anti-core antibodies and HBV DNA. Since anti-core testing was introduced in 2022 in England, the effectiveness of testing and potential alternatives required investigations. This thesis details the development of assays that uncover the existence of donors with HBV DNA viral loads below the limit of detection of commercially available assays; the potential utility (and insensitivity) of next-generation sequencing assays in blood donor screening; the need for a second screening assay to reduce false positivity in anti-core screening assays; and an international survey gained insight into the screening practices for occult HBV infection, effectiveness of screening in preventing transfusion-transmitted infections, and the lack of consensus regarding donor follow-up. These results highlight the complexity of the diagnosis and care of individuals with occult HBV infection, and conclude that while screening strategies are necessary, a more sensitive screening strategy to identify occult HBV infections would improve blood safety even further. Further research could identify alternative biomarkers that could predict the presence of infectious forms of occult HBV, as well as gather insights from donors with occult HBV infection into their diagnosis and follow-up
Action in memory and memory in action: experiments in the encoding and retrieval of spatial representation
Get PDFIn this thesis, I posit a fundamental link between action and memory in human cognition. I present results from a series of behavioural experiments which examine this interplay from two distinct angles: I investigate how action representations modulate memory formation (action in memory) and examine how memory representations shape action sequences (memory in action).
I offer a contribution to the cognitive sciences by presenting fourteen studies across five empirical chapters, which demonstrate behavioural markers of cognitive ties between action and memory. This work pertains to theories of cognition and curriculum design in service of learning.
Chapter I lays the theoretical foundations of the investigation through a review of memory research and previously revealed cognitive effects at the junction of action and memory. I situate the focus on action in memory amidst long established inquiries: at the intersection between procedural and declarative memory formation, amidst theories of active learning and epistemic actions, and in relation to the embodied cognition paradigm. I review and rely on theories of memory as reconstructive, which position memory as a substrate for mental simulation or model-based reconstruction of unseen, future or fictional scenes and behaviours.
Chapters II-IV (Action in Memory) report the foundational modulation of memory through a manipulation of the alignment between action selections and supervision signals in an associative, spatial memory task. These chapters empirically demonstrate that memory performance during test phases is superior when action selections during training were aligned with feedback signals, compared to when action selections were misaligned during training. I introduce this action alignment effect and show its generalisations and robustness against a range of controls.
In chapters V, VI (Memory in Action), I reverse and expand the inquiry and consider how memories are used to guide action sequences in a self-simulation task. Here, the experiments ask humans to reconstruct their own prior behaviour from incomplete memory in the context of a spatial rule discovery task. A re-enactment of their own learning dynamics requires an emulation of the behavioural markers associated with an epistemic transition from ignorance to knowledge. I first identify subtle behavioural markers of this epistemic transition, and then, by use of a comparison between behaviour during discovery and behaviour during a simulation of discovery, I quantify distinct biases in self-simulation of counterfactual epistemic states. Chapters V, VI thus explore the role of partial memory in metacognitive access as revealed by action sequences. In a final discussion chapter (VII), I summarise my contributions and their limitations
The archaeology of archipelagos: human ecological and behavioural dynamics in island systems
No full textThis paper presents a framework for long-term human behavioural and ecological dynamics in archipelagos. The framework is built on four points. First, archipelagos are in flux. Processes like geological formation, climatic change, and insularisation have influenced not only plant and animal distributions, but also human water-crossing capacities, connectivity, and cognition. Second, humans are behaviourally plastic and can be adaptively flexible. Fluctuating archipelagos became intertwined with people’s plasticity as they made their livelihoodsin these spaces. Third, as humans peopled islands they transformed them, creating ‘cultured archipelagos’. Cultured archipelagos were not just humanly altered environments, but developmental systems built on ecological and technical knowledge, scaffolding future possibilities for island life and maritime activity. Fourth, cultured archipelagos evolved as rhizomatic networks. This means they emerged through simultaneous processes of divergence and connection. To illustrate the approach, these dynamics are explored through the archaeological record of New Guinea’s outlying islands. This shifts the focus of island archaeology away from insular spaces that exert structuring influences on humans, or humans that create insular identities in isolation, to evolving archipelagic ecologies formed by the activities of islands, biota, and humans. Beyond islands, archipelagic archaeology could help to understand spatial and temporal dynamics in other fragmented landscapes.