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A computational study of the Lobula Plate Tangential Cells of flies for bio-inspired optical flow encoding and self-motion estimation
No full textWhen driving a car, determining whether an object is moving toward or away from us is crucial. Similarly, motion perception provides essential visual cues that sighted animals rely on extensively for their survival. The image moving across an observer’s retina results from a combination of motion patterns generated by either the observed scene or the observer’s motion. The structured pattern of apparent displacement forming this visual input is known as Optical Flow. Since optical flow depends on the observer’s motion relative to the surrounding environment and the nearness distribution of this observed environment, it serves as a valuable cue for both self-motion estimation and perception of the environment. Animals use optical flow for navigation, and the same concept has been widely adopted in Computer Vision, where motion-based algorithms are integrated into drones, robots, and smart devices. However, while both animals and drones exploit optical flow for navigation, they process and interpret it differently. Studying biological models—especially flies, which have a uniquely understood visual system —can inspire alternative approaches to visual navigation in autonomous systems. In this thesis, I draw inspiration from the functional behaviour of Lobula Plate Tangential Cells (LPTCs) in the fly’s visual system, and investigate how the LPTCs’ global optical flow templates, or other analogous templates derived through a data-driven approach, can encode self-motion information. My research focuses primarily on the blowfly (Calliphora vicina), a species whose visual system and flight behaviour has been studied intensively for decades. First, I analyse existing optical flow datasets and identify gaps in their suitability for studying LPTC responses using computer vision techniques. To address this, I develop a bio-informed computer vision dataset specifically designed to capture the optical flow experienced by flies during navigation. The dataset provides panoramic visual images along with ground-truth optical flow, depth maps, and pose estimation data. Secondly, I investigate how LPTCs respond collectively to diverse optical flow stimuli. While past studies have examined individual LPTCs based on their preferred motion directions or responses to specific rotational and translational flows, I analyse their population response across ipsilateral and contralateral sister cells’ preferred direction and several different motion primitives. My findings support existing literature while offering new insights into how LPTCs contribute to decomposing the optical flow experienced in flight. Thirdly, I explore Principal Component Analysis (PCA) as a data reduction technique to encode optical flow using global motion templates, akin to LPTC response maps. I demonstrate that the Principal Components (PCs) of the optical flow experienced by flies correspond to six-degree-of-freedom motion patterns and strongly align with LPTCs. Additionally, I show that global optical flow templates —similar to PCs and LPTCs— can effectively be used to compress optical flow information in such a way it can be decoded back with high accuracy, though they exhibit limitations when handling discontinuities in motion fields, such as moving objects. Fourthly, I develop shallow neural networks leveraging global optical flow processors to estimate the instantaneous rotation axis of the fly, comparing the performance of LPTCs and PCs. Comparing 312 different models trained on the bio-informed dataset, I demonstrate that sub-degree accuracy can be achieved at over thousands of iterations per second. Moreover, I show that a model with just 234 parameters is capable of accurately estimating the instantaneous axis of rotation in fly trajectories and finds reasonable success on drone trajectories. Finally, I examine the relationship between the Principal Components used throughout this thesis and the dynamically-significant directions (DSDs) previously identified for Calliphora flies. My results reveal a strong alignment between PCs and DSDs, suggesting that both represent different facets of the same underlying principle of energy transfer. This alignment further supports the idea that LPTCs optimize energy transfer from photoreceptors to descending neurons for higher-level tasks, such as self-motion estimation. Overall, this thesis presents a novel approach to investigating motion perception in both biological and artificial systems. By bridging the gap between computational and biological vision, my findings pave the way for new data-driven models of animal behaviour and energy-efficient computer vision pipelines for drone navigation
David Dufresne’s Un Pays qui se tient sage (2020) and contemporary documentary activism
Get PDFDavid Dufresne’s Un Pays qui se tient sage (2020) offers a critique of French police violence, particularly in relation to the Gilets Jaunes protests. The film is set in a viewing space where participants (including protesters, sociologists, lawyers, and police representatives) analyze footage of the protests, which primarily consists of mobile phone recordings shot by the protesters themselves as well as television reports from the mainstream media. This article argues that rather than understanding these images as representations of pre-existing events, they should instead be understood as politics in action. Drawing on critics such as Aurora Hoel, John Durham Peters, and Jacques Rancière, the article proposes that documentary film scholars move away from the idea of images as re-presentations (Hoel’s paradigm of “images-of”) and toward an understanding of images as “civilizational ordering mechanisms” (Peters).
Culinary cosmologies: proteins and customs in late Yuan
No full textThis thesis investigates the intersection of food, ritual, and cultural identity in the late Yuan dynasty, developing the concept of “culinary cosmologies” as a framework for comparative analysis. It focuses on two dietary manuals produced in the fourteenth century: Hu Sihui’s Yinshan zhengyao (Proper and Essential Things for the Emperor’s Food and Drink, 1330) and the Yinshi xuzhi (Things One Must Know about Food and Drink, c. 1370, attributed to Jia Ming). While both texts reflect courtly dietary concerns, they embody contrasting cultural orientations—Mongol and Han Chinese—and thus provide a lens into competing systems of nourishment, ritual practice, and ideological meaning. The thesis examines sheep and horse as case studies, analysing their dietary, ritual, and symbolic roles across medical, cosmological, and aesthetic registers. Sheep, central to nomadic pastoral life, reveal continuities between shamanistic ritual and court practice, particularly through sacrificial and culinary rites. Horses, by contrast, embody prohibitive dietary categories, their colour symbolism and perceived toxicity illustrating broader cultural biases and tensions between Mongol and Chinese foodways. Through this comparative study, the thesis demonstrates how foodstuffs become spiritually charged commodities, serving as sites of negotiation between continuity and rupture, pragmatism and ideology. By integrating archaeological, textual, and anthropological evidence, the thesis reconstructs dietary networks that illuminate both Mongol persistence and Chinese influence. Ultimately, it argues that culinary cosmologies not only shaped patterns of consumption but also reflected deeper cultural negotiations, offering a methodological model for future studies of food, identity, and empire
Equal pay: navigating the thicket
No full textDespite over 50 years of equal pay legislation in the UK, the gender pay gap stubbornly persists. This is in part due to its dependence on an individual complaints system demonstrably ill-suited to the task, both because respondents have been able to utilize procedural requirements to delay and prolong claims, and because of the ways in which the substantive rights have been formulated and interpreted. Given that many of these problems have been apparent for decades, it is apposite to consider the many equal pay cases presided over by Elias LJ between 2005 and 2009 when he was president of the Employment Appeal Tribunal. A close examination of these 20 cases reveals Elias LJ’s rigour, his patient commitment to unravelling an increasingly complex area of the law, but also his wry humour and pertinent social comments during the course of the journey. This article begins by setting the context and demonstrates the dysfunctionality of the complaints-led process as reflected in the cases canvassed. The article then turns to substantive issues, which despite their apparent straightforward wording, have been interpreted in increasingly complex and technical ways. The conclusion considers new developments and ways forward. The article demonstrates Elias LJ’s long-lasting contribution to both doctrine and principle in relation to equal pay. It also considers the impetus for reform created by the New Labour government and suggests ways in which the lessons learned during that period, as well as more recent developments from the European Union, could be translated into real improvements in equal pay legislation. It is hoped that the impetus for reform will release equal pay claims from sole reliance on individual complaints. Moreover, change needs to go well beyond the current anaemic proposals for pay transparency. Instead, a collective response requiring proactive measures by employers across the whole pay scale, with close participation by workers and their representatives, is urgently needed
FROM MILAN TO WEST BERLIN: SPATIAL ALIENATION AND THE POST‐1945 ANXIOGENIC CITYSCAPE IN ANNA MARIA ORTESE'S SILENZIO A MILANO AND INGEBORG BACHMANN'S ‘EIN ORT FÜR ZUFÄLLE’
Get PDFThis article examines Anna Maria Ortese's collection of journalistic reportages and short stories, Silenzio a Milano (Silence in Milan, 1958), and Ingeborg Bachmann's speech ‘Ein Ort für Zufälle’ (17 October 1964). It focuses on their topophobic images of Milan and West Berlin, the anxious representations of these post‐1945 urban landscapes. Their pathographies of 1950s Milan and 1960s West Berlin are explored by linking contemporary studies on alienation with the polarity of affective responses to space. The analysis especially resorts to Gaston Bachelard's and Yi‐Fu Tuan's discourses of topoaffective polarities, that is topophobia and topophilia, as a starting point to highlight Ortese's and Bachmann's shared focus on the material, psychic and social character of peacetime Italian and West German societies. While recognising the texts’ differences in genre and degree of negativity, the article reads the complex representations of the ‘pathological’ relationality between the self and the socially constructed world in Silenzio a Milano and ‘Ein Ort für Zufälle’ as topical metaphors for alienation in urban capitalism. It positions Ortese and Bachmann as critics not only of the haunted histories of Nazi‐fascism but also of post‐1945 European models of growth
Cerebrovascular Reactivity at Rest and Its Association With Cognitive Function in People With Genetic Frontotemporal Dementia
Get PDFBackground and objectivesCerebrovascular reactivity (CVR) is an indicator of cerebrovascular health, and its signature in familial frontotemporal dementia (FTD) remains unknown. The primary aim was to investigate CVR in genetic FTD using an fMRI index of vascular contractility termed resting-state fluctuation amplitudes (RSFAs) and to assess whether RSFA differences are moderated by age. A secondary aim was to study the relationship between RSFA and cognition.MethodsParticipants included presymptomatic and symptomatic C9orf72, GRN, and MAPT pathogenic variation carriers, along with noncarriers, from the prospective Genetic FTD Initiative cohort study. Cross-sectional differences in CVR were assessed using both component-based and voxel-level RSFA maps. To study disease progression-related effects, the moderating effect of age on differences between genetic status groups was analyzed using generalized linear models. The influence of RSFA, and its interaction with genetic status, on participants' cognitive function was also examined. All models were adjusted for sex, handedness, and scanning site and false discovery rate-corrected at p < 0.05.ResultsA total of 284 presymptomatic and 124 symptomatic sequence variation carriers, and 265 noncarriers, were included in the analysis (mean age 48.17 years, 55% female). Across the sample, symptomatic carriers exhibited lower RSFA and a greater age-related RSFA decline predominantly in the medial frontal (-0.07 standard units, p = 0.046, 95% CI -0.13 to -0.01) and posterior parietal (-0.06 standard units, p = 0.048, 95% CI -0.12 to 0.01) cortex, compared with presymptomatic carriers and noncarriers. RSFA was inversely correlated with age (-0.43 standard units, p < 0.001, 95% CI -0.48 to -0.37) and positively associated with cognitive function (0.09 standard units, p = 0.008, 95% CI 0.04-0.15), particularly in the prefrontal cortex, in sequence variation carriers across the sample, independent of disease stage.DiscussionCVR impairment in genetic FTD has a predilection for the middle frontal and posterior cortex, and its preservation may yield a cognitive benefit for at-risk individuals. Although findings do not provide causality and warrant replication, they support the notion that vascular dysfunction in familial FTD may be a target for biomarker identification and disease-modifying efforts
Phylogenomics and the falsification of shearwater species (Puffinus mauretanicus, P. yelkouan) hypotheses: a comment on Ferrer Obiol et al. (2023)
No full textChanging minds: Understanding the use of oral steroids in acute asthma
No full textAsthma is a heterogenous disease with a substantial global burden. Asthma attacks are treated based on symptoms alone with oral steroids despite some attacks displaying little evidence of type-2 inflammation. Type-2 low inflammatory attacks may experience more dose-dependent harm from steroids than clinical benefits. A personalised medicine approach to treating asthma attacks using biomarkers may improve patient clinical outcomes and minimise side effects. FeNO and blood eosinophils are the two key biomarkers that measure type-2 inflammation. The goal of my DPhil was to provide supportive evidence for a biomarker-directed, placebo-controlled trial of oral steroid treatment for asthma attacks. A systematic review identified that trials of asthma attack treatment have been set almost entirely in urgent care, focussing on short-term, physiological outcome measures. A discrete choice experiment identified that patients and healthcare professionals will trade-off treatment benefits to avoid the side-effects associated with OCS. While symptom recovery was the most important clinical outcome to HCPs and patients, HCPs preferred avoiding further healthcare utilisation more than patients. Proteomic analysis of sputum and blood samples identified that prednisolone still had broad anti-inflammatory airway effects on top of anti-IL5 monoclonal antibody therapy. However, these effects were heterogeneous and not present in some participants. A prospective observational study of adults on anti-IL5/5Rα therapy identified that FeNO-high attacks were associated with larger clinical improvements and airway anti-inflammatory effects after 7 days prednisolone treatment compared to FeNO-low attacks. In conclusion, after systemic blood eosinophil suppression there is heterogeneity in steroid-responsiveness amongst the asthma population, which can be discriminated by FeNO testing at attack. There is clinical equipoise in using oral steroids treatment for type-2 low asthma attacks. Given the willingness of patients and healthcare professionals to trade-off clinical benefits to avoid oral steroid risks, my thesis supports pursuing a biomarker-directed approach to treating asthma attacks
Testing strong-field QED with the avalanche precursor
No full textA two-beam high-power laser facility is essential for the study of one of the most captivating phenomena predicted by strong-field quantum electrodynamics (QED) and yet unobserved experimentally: the avalanchetype cascade. In such a cascade, the energy of intense laser light can be efficiently transformed into high-energy radiation and electron-positron pairs. The future 50-petawatt-scale laser facility NSF OPAL will provide unique opportunities for studying such strong-field QED effects, as it is designed to deliver two ultra-intense, tightly focused laser pulses onto the interaction point. In this work, we investigate the potential of such a facility for studying elementary particle and plasma dynamics deeply in the quantum radiation-dominated regime, and the generation of QED avalanches. With 3D particle-in-cell simulations, we demonstrate that QED avalanche precursors can be reliably triggered under realistic laser parameters and layout (namely, focusing f /2, tilted optical axes, and non-ideal co-pointing) with the anticipated capabilities of NSF OPAL. We demonstrate that seed electrons can be efficiently injected into the laser focus by using targets of three types: a gas of heavy atoms, an overcritical plasma, and a thin foil. A strong positron and high-energy photon signal is generated in all cases. The cascade properties can be identified from the final particle distributions, which have a clear directional pattern. At increasing laser field intensity, such distributions provide signatures of the transition, first, to the radiation-dominated interaction regime, and then to a QED avalanche. Our findings can also be used for designing related future experiments
Examification: curricular, temporal, affective, and discursive dimensions of examination’s effects on education
Get PDFThis article introduces examification, a new concept for understanding the far-reaching impacts of examinations on education. Examinations have long been integral to education systems, serving as markers of achievement and instruments of accountability. This article introduces examification as a new conceptual framework for analysing the wide-ranging and interconnected ways in which examinations shape curricula, pedagogy, temporal structures, emotional experiences, and educational discourses. Far from being neutral tools for assessing achievement, examinations (whether ‘high’ or ‘low’ stakes) emerge as powerful mechanisms that dictate what is taught, how it is taught, how success is defined, and how education is experienced. This conceptual paper examines four interconnected dimensions of examification: curriculum, time, affect, and discourse. It highlights how examinations compress and narrow subject choices, intensify and reshape temporal rhythms, provoke diverse affective responses, and perpetuate discourses that sustain hierarchies and the commodification of education. The article illustrates how these dimensions interact across individual, institutional, national, and global scales. While the impacts of examification are often negative, they are not uniform or inevitable; the concept invites critical engagement with examinations’ effects and possibilities for reform