The impossible puzzle: No global embedding in environmental space memory

We live in compartmentalized, clustered environments and have to deal with spatial information scattered across rooms, streets, neighborhoods, and cities every day of our life. Yet, we are able to piece this information together in our head, for example, in order to find our way from our flat to our workplace, even when faced with construction work and blocked streets. Furthermore, we can point out the direction to the supermarket to a pedestrian without having direct visual access to it. My thesis is concerned with the question of how our memory for spatial relations of places in navigable space (also called survey knowledge) is actually structured. In four consecutive studies, I contrasted two major theo-retical approaches that try to explain how we represent survey knowledge, namely, Euclidean map and enriched graph approaches. Euclidean map approaches assume that spatial locations are represented in a map-like, globally embedded, Euclidean format. Enriched graph approaches propose a partitioned, unitwise representation of places connected in a network. These local units are not required to be globally consistent. In each study, I used different virtual environments, sometimes single rooms, mostly navigable multi-corridor environ-ments, once even an impossible non-Euclidean environment. Participants learned spatial relations between objects spread across these environments and solved survey tasks afterward (e.g., pointing to object locations from memory). Their performance yielded multiple effects. In short, the most prominent effects were: (1) Pointing latency increased with increasing number of places along the route towards the target, (2) facilitated recall along the direction of the initially experienced path walked within the environment, (3) globally incoherent point-ing behavior following the local metrics experienced from place to place, (4) facilitated performance upon alignment with local corridor geometry but also (5) upon alignment with regional geometry and a global main orientation, and (6) decreased pointing latency when pointing beyond regional boundaries. Interpreting these effects jointly implies that human survey knowledge is not repre-sented in the form of a Euclidean mental map embedding all encountered places in a uniform, globally consistent format. Instead, just as the environment we experience, also our memory of it seems to be compartmentalized, consisting of a network of local places connected by directed links that specify how to get from one place to another (rotation and translation) without directly requiring a global calibration. Survey estimates have to be constructed incrementally following this graph structure along the memorized connectivity, thereby relying on the local metrics that enrich the graph entities. These estimates are generally transient but can be retained for a limited amount of time for aiding subsequent estimates. In addition to the local entities of the enriched graph representation, it seems that general reference directions can be acquired during learning a navigable multi-compartment space. Such a reference direction can be understood as a mental “north”, a main direction that is tried to be main-tained and propagated across multiple local places and represented supplemen-tary in memory. It might be limited to only a sub-group of local units, thereby forming regional clusters, or it can cover the entire environment that was encountered. Such a general reference direction can aid the coordination of the local memory units during the construction of survey estimates, however, it does not require a global embedding of all place information into a coherent Euclidean map format. In sum, our representation of navigable space seems to be best described as an impossible puzzle where the memorized pieces and connec-tions do not necessarily match up on a global scale

Theoretical Computational Models for the Cognitive Map

In den letzten Jahrzehnten hat die Forschung nach der Frage, wie Raum im Gehirn repräsentiert wird, ein weit verzweigtes Netzwerk von spezialisierten Zellen aufgedeckt. Es ist nun klar, dass Räumlichkeit auf irgendeine Art repräsentiert sein muss, aber die genaue Umsetzung wird nach wie vor debattiert. Folgerichtig liegt das übergeordnete Ziel meiner Dissertation darin, das Verständnis von der neuronalen Repräsentation, der Kognitiven Karte, mithilfe von theoretischer Computermodellierung (im Gegensatz zu datengetriebener Modellierung) zu erweitern. Die Arbeit setzt sich aus vier Publikationen zusammen, die das Problem aus verschiedenen, aber miteinander kompatiblen Richtungen angehen: In den ersten beiden Publikationen geht es um zielgerichtete Navigation durch topologische Graphen, in denen die erkundete Umgebung als Netzwerk aus loka len Positionen und sie verbindenden Handlungen dargestellt wird. Im Gegensatz zu Koordinaten-basierten metrischen Karten sind Graphenmodelle weniger gebunden und haben verschiedene Vorteile wie z.B. Algorithmen, die garantiert optimale Pfade finden. Im ersten Modell sind Orte durch Populationen von einfachen Bildfeatures im Graphen gespeichert. Für die Navigation werden dann mehrere Pfade gleichzeitig zwischen Start- und Zielpopulationen berechnet und die schlussendliche Route folgt dem Durchschnitt der Pfade. Diese Methode macht die Wegsuche robuster und umgeht das Problem, Orte entlang der Route wiedererkennen zu müssen. In der zweiten Publikation wird ein hierarchisches Graphenmodell vorgeschlagen, bei dem die Umgebung in mehrere Regionen unterteilt ist. Das Regionenwissen ist ebenfalls als übergeordnete Knoten im Graphen gespeichert. Diese Struktur führt bei der Wegsuche dazu, dass die berechneten Routen verzerrt sind, was mit dem Verhalten von menschlichen Probanden in Navigationsstudien übereinstimmt. In der dritten Publikation geht es auch um Regionen, der Fokus liegt aber auf der konkreten biologischen Umsetzung in Form von Place Cell und Grid Cell-Aktivität. Im Gegensatz zu einzigartigen Ortsknoten im Graphen zeigen Place Cells multiple Feuerfelder in verschiedenen Regionen oder Kontexten. Dieses Phänomen wird als Remapping bezeichnet und könnte der Mechanismus hinter Regionenwissen sein. Wir modellieren das Phänomen mithilfe eines Attraktor-Netzwerks aus Place- und Grid Cells: Immer, wenn sich der virtuelle Agent des Modells von einer Region in eine andere bewegt, verändert sich der Kontext und die Zellaktivität springt zu einem anderen Attraktor, was zu einem Remapping führt. Das Modell kann die Zellaktivität von Tieren in mehreren Experimentalumgebungen replizieren und ist daher eine plausible Erklärung für die Vorgänge im biologischen Gehirn. In der vierten Publikation geht es um den Vergleich von Graphen- und Kartenmodellen als fundamentale Struktur der kognitiven Karte. Im Speziellen geht es bei dieser Debatte um die Unterscheidung zwischen nicht-metrischen Graphen und metrischen euklidischen Karten; euklidische Karten sind zwar mächtiger als die Alternative, aber menschliche Probanden neigen dazu, Fehler zu machen, die stark von einer metrischen Vorhersage abweichen. Deshalb wird häufig argumentiert, dass nicht-metrische Modelle das Verhalten besser erklären können. Wir schlagen eine alternative metrische Erklärung für die nichtmetrischen Graphen vor, indem wir die Graphen im metrischen Raum einbetten. Die Methode wird in einer bestimmten nicht-euklidischen Beispielumgebung gezeigt, in der sie Versuchspersonenverhalten genauso gut vorhersagen kann, wie ein nichtmetrischer Graph. Wir argumentieren daher, dass unser Modell ein besseres Modell für Raumrepräsentation sein könnte. Zusätzlich zu den Einzelergebnissen diskutiere ich außerdem die Gemeinsamkeiten der Modelle und wie sie in den derzeitigen Stand der Forschung zur kognitiven Karte passen. Darüber hinaus erörtere ich, wie die Ergebnisse zu komplexeren Modellen vereint werden könnten, um unser Bild der Raumkognition zu erweitern.Decades of research into the neural representation of physical space have uncovered a complex and distributed network of specialized cells in the mammalian brain. It is now clear that space is represented in some form, but the realization remains debated. Accordingly, the overall aim of my thesis is to further the understanding of the neural representation of space, the cognitive map, with the aid of theoretical computational modeling (as opposed to data-driven modeling). It consists of four separate publications which approach the problem from different but complementing perspectives: The first two publications consider goal-directed navigation with topological graph models, which encode the environment as a state-action graph of local positions connected by simple movement instructions. Graph models are often less constrained than coordinate-based metric maps and offer a variety of computational advantages; for example, graph search algorithms may be used to derive optimal routes between arbitrary positions. In the first model, places are encoded by population codes of low-level image features. For goal-directed navigation, a set of simultaneous paths is obtained between the start and goal populations and the final trajectory follows the population average. This makes route following more robust and circumvents problems related to place recognition. The second model proposes a hierarchical place graph which subdivides the known environment into well-defined regions. The region knowledge is included in the graph as superordinate nodes. During wayfinding, these nodes distort the resulting paths in a way that matches region-related biases observed in human navigation experiments. The third publication also considers region coding but focuses on more concrete biological implementation in the form of place cell and grid cell activity. As opposed to unique nodes in a graph, place cells may express multiple firing fields in different contexts or regions. This phenomenon is known as “remapping” and may be fundamental to the encoding region knowledge. The dynamics are modeled in a joint attractor neural network of place and grid cells: Whenever a virtual agent moves into another region, the context changes and the model remaps the cell activity to an associated pattern from memory. The model is able to replicate experimental findings in a series of mazes and may therefore be an explanation for the observed activity in the biological brain. The fourth publication again returns to graph models, joining the debate on the fundamental structure of the cognitive map: The internal representation of space has often been argued to either take the form of a non-metric topological graph or a Euclidean metric map in which places are assigned specific coordinates. While the Euclidean map is more powerful, human navigation in experiments often strongly deviates from a (correct) metric prediction, which has been taken as an argument for the non-metric alternative. However, it may also be possible to find an alternative metric explanation to the non-metric graphs by embedding the latter into metric space. The method is shown with a specific non-Euclidean example environment where it can explain subject behavior equally well to the purely non-metric graph, and it is argued that it is therefore a better model for spatial knowledge. Beyond the individual results, the thesis discusses the commonalities of the models and how they compare to current research on the cognitive map. I also consider how the findings may be combined into more complex models to further the understanding of the cognitive neuroscience of space

Humans Construct Survey Estimates on the Fly from a Compartmentalised Representation of the Navigated Environment

Despite its relevance for navigation surprisingly little is known about how goal direction bearings to distant locations are computed. Behavioural and neuroscientific models proposing the path integration of previously navigated routes are supported indirectly by neural data, but behavioral evidence is lacking. We show that humans integrate navigated routes post-hoc and incrementally while conducting goal direction estimates. Participants learned a multi-corridor layout by walking through a virtual environment. Throughout learning, participants repeatedly performed pairwise pointing from the start location, end location, and each turn location between segments. Pointing latency increased with the number of corridors to the target and decreased with pointing experience rather than environmental familiarity. Bimodal pointing distributions indicate that participants made systematic errors, for example, mixing up turns or forgetting segments. Modeling these error sources suggests that pointing did not rely on one unified, but rather multiple representations of the experimental environment. We conclude that participants performed incremental on-the-fly calculations of goal direction estimates within compartmentalised representations, which was quicker for nearby goals and became faster with repeated pointing. Within navigated environments humans do not compute difference vectors from coordinates of a globally consistent integrated “map in the head”

Making a success of ‘failure’: a Science Studies analysis of PILOT and SERC in the context of Australian space science

This thesis presents an in-depth empirical investigation, based on participant observation, interviews and publicly available materials, of PILOT and SERC, two recent Australian space science projects that were both connected to the problem of space debris. While PILOT’s proposal for funding failed, SERC was successfully funded yet failed to reach its initially stated goal of demonstrating the possibility of Active Debris Removal (ADR) using a ground-based high power laser combined with laser guide star adaptive optics. My analysis illustrates that the Australian space science funding and policy environment changed significantly in the brief period between PILOT’s unsuccessful proposal and SERC’s formation, marking the period of time in which dual-use space capability development was recognised as a political strategic priority. In SERC’s case, dual-use technology has been developed through (substantially) publicly funded institutions and by civil scientists. I argue that the current arrangement of policy and funding structures in the Australian space sciences sector facilitates engagement in dual-use technology development in such a way that two outcomes emerge: first, that moral responsibility for the products of such research is institutionally and individually avoided by distributing it ‘up the chain’ to national governmental entities, and second, that international legal responsibility is likewise avoided at a national level by distributing it ‘down the chain’ to institutions. I demonstrate how policy and funding conditions in Australia allowed individuals working in, and adjacent to, the space sciences to maintain, unchallenged, the convenient fiction that science is itself amoral and, to some extent, apolitical

Proceedings of the Cardiff University Engineering Research Conference 2023

The conference was established for the first time in 2023 as part of a programme to sustain the research culture, environment, and dissemination activities of the School of Engineering at Cardiff University in the United Kingdom. The conference served as a platform to celebrate advancements in various engineering domains researched at our School, explore and discuss further advancements in the diverse fields that define contemporary engineering

Shape-shifting nature in a congested landscape in Guinea-Bissau

Studying people and wild animals based only on their strict and present-day interactions is not enough to develop a comprehensive understanding of social constructions of animal species. People encounter other species (and other people) from within particular historical, social, ecological and economic settings. In 13 months of fieldwork, I adopted a multi-disciplinary perspective, using qualitative ethnographic tools alongside quantitative ecological and interviewing approaches to seek for an in-depth understanding that provides access to multiple views about nature and nature conservation. In southern Guinea-Bissau, space and its history, magic and religion, changes in the landscape and environment, local livelihoods and trade, as well as local relations of power for accessing resources, all shape the social and cosmological terrain of the interactions between people and other living and non-living things. On the one hand, magical territories, the role animal figures play in witchcraft, local knowledge and its management, all portray nature as part of society, both as an element and an actor in society. On the other hand, when nature conservation initiatives based on fines and fences are emphasised, the social appropriation of nature envisions people and nature as separate, even antagonistic entities that negotiate each other’s existence. Land is the most important component of livelihoods as it is tightly connected to labour allocation and knowledge exchange. Therefore, by constraining people’s access to land, nature conservation policies are largely seen as affecting local people’s ability to secure their livelihoods. Consequently, constraints and benefits bestowed by conservation are negotiated locally through complex mechanisms of storytelling, witchcraft, meetings, and protests. These all play a role in challenging standing agreements, as well as expressing social tension and marking out morality. The chimpanzee, the flagship species of Cantanhez National Park, appears as a multi-faceted character capable of shape-shifting into various forms and signifiers that challenge existing power asymmetries, including those inherent within local nature conservation

The research on mechanical properties and compressive behavior of graphene foam with multi-scale model?

Computational simulation is an effective method to study the deformation mechanism and mechanical behaviour of graphene-based porous materials. However, due to limitations in computational methods and costs, existing research model deviate significantly from the real material in terms of the scale of structure. Therefore, building a highly accurate computational model and maintaining an appropriate cost is both necessary and challenging. This paper proposed a multi-scale modelling approach for finite element (FE) analysis based on the concept of structural hierarchy. The stochastic feature of the microstructure of porous materials are also considered. The simulation results of the regular structure model and the Voronoi tessellation model are compared to investigate the effect of regularity on the material properties. Despite some shortcomings, other microstructural features of porous graphene materials can be gradually introduced to improve the material model step by step. Thus the developed multiscale model has great potential to simulate the properties of materials with mesoscopic size structure such as graphene foam (GF)

Disrupting the fatal sleep: innovation and the elimination of Human African Trypanosomiasis in Northern Uganda

For more than a century, a wide variety of tools, techniques, and strategies have been deployed in attempts to control Human African Trypanosomiasis with mixed success. However, the recent development of more simple and cost-effective diagnostic devices, drug candidates, and vector control methods have culminated in renewed political commitments toward eliminating the disease. This thesis draws on ethnographic case studies of these ‘contemporary and emerging strategies’ (Steinmann et al. 2015) at a critical moment between implementation and scale; where technologies form relationships and take on social connotations, and where policy struggles to become practice. These multi-sited studies provide empirical examples of how technologies of global health become commodities of governance, and objects of expertise, controversy, and advocacy. This study critiques the global health community’s fixation on technology as the harbinger of progress in sleeping sickness control, and argues that solutions continue to be overly simplistic and attentive to discrete devices. In doing so, programmes overlook the dynamic systems that govern technologies’ social proximity to people. Case studies on diagnostics and tsetse control illustrate how socially embedded technologies can become tools of advocacy by promoting horizontal forms of knowledge production and exchange. The social proximity of interventions are key drivers of sustainability, as more community embedded technologies take on, and persist through social lives of their own. Examining diagnostic capacity in the passive surveillance system reveals how infrastructures are relational as well as material, thus technology alone cannot address infrastructural paucity. Global commitments to collaborative ‘One Health’ approaches to eliminating HAT disentangle in practice and become fragmented at the point of implementation. Decentralised and under-resourced district offices struggle to maintain operational cohesion, as a precarious network of health workers, entomologists, and veterinarians struggle to align vertical programmes with local priorities. In summary, this study reveals HAT control as a fragile assemblage of actors operating in environments of uncertainty, and explores how introducing new technologies into these socio-technical ecosystems can disrupt and transform them in unpredictable ways. Due to the dominance of top-down technocratic approaches in global health, anthropological contributions to HAT programmes are widely underutilised (Bardosh, 2014). This thesis advocates critical, multidisciplinary approaches for developing adaptive, locally specific solutions to HAT in a landscape of elimination

Towards Interoperable Research Infrastructures for Environmental and Earth Sciences

This open access book summarises the latest developments on data management in the EU H2020 ENVRIplus project, which brought together more than 20 environmental and Earth science research infrastructures into a single community. It provides readers with a systematic overview of the common challenges faced by research infrastructures and how a ‘reference model guided’ engineering approach can be used to achieve greater interoperability among such infrastructures in the environmental and earth sciences. The 20 contributions in this book are structured in 5 parts on the design, development, deployment, operation and use of research infrastructures. Part one provides an overview of the state of the art of research infrastructure and relevant e-Infrastructure technologies, part two discusses the reference model guided engineering approach, the third part presents the software and tools developed for common data management challenges, the fourth part demonstrates the software via several use cases, and the last part discusses the sustainability and future directions

Entrepreneurship, identity, and their overlap in the slum: an ethnographic study of the Mukuru slum in Nairobi, Kenya

This study explores the relationship between entrepreneurship and collective identity in an informal, or ‘slum’, community in Nairobi, Kenya. In Nairobi, as in cities across the Developing World, slum communities stand out as islands of poverty and neglect amidst increasingly cosmopolitan urban surroundings. Extant research, much of which centres on the so-called ‘Base of the Pyramid’ (BoP), has shown that where social groups experience levels of social and economic disadvantage which are far in excess of comparable groups, entrepreneurship is often underpinned by a strong collective orientation. This can have a profound and wide-ranging bearing on the venturing process. Slum communities, however, have yet to be considered in this research and, moreover, they remain largely neglected within the broader literature on entrepreneurship at the BoP. Drawing on ethnographic data collected during four-and-a-half months of fieldwork, I observed that collective identity was closely tied up with economic informality. Entrepreneurs believed that their community’s marginal status afforded them a de facto right to circumvent the costs of registration and taxation, considerably reducing the barriers to market entry in an environment characterised by widespread and acute resource deprivation. However, for most entrepreneurs this was the only facet of the venturing process that was permeated by collective identity. Navigating the many challenges of their market context was seen as an individual rather than a collective concern. This was observed to differ, however, among the slum’s younger generation, who, for the most part, had grown up there or moved there as adolescents. This cohort exhibited a stronger proclivity towards collaboration in entrepreneurial venturing, and their ventures were firmly rooted in dense, close-knit friendship networks. This study extends current understandings of how entrepreneurship is affected by social-group membership, particularly in a BoP context