VictorJuiz/thesis huggingface dataset:
The role of cognitive biases and executive functions in adolescent worry
Keywords: adolescents
longitudinal
cognitive biases
worry
executive functions

Worry is common in childhood and adolescence. In moderation, worry can serve as an adaptive response in anticipation to perceived threat. However, some young people experience excessive, uncontrollable, and persistent worries that cause significant distress and impairments to daily functioning. Research presented in this thesis investigated the role of cognitive biases and executive functions in adolescent worry. In Chapter Two, a systematic review examined the existing literature on child and adolescent worry and found that cognitive biases and executive functions were associated with worry in youth. The systematic review identified some of the gaps in the child and adolescent literature on worry, which provided a research framework for subsequent studies in this thesis. Chapters Three and Four presented data from the CogBias Longitudinal study and showed that interpretation and memory biases were closely interrelated cognitive processes associated with adolescent worry. Furthermore, Chapter Four found that negative biases played a causal role in the manifestation of worry from early to mid-adolescence. Chapters Five and Six, investigated the role of executive functions in adolescent worry. Findings in Chapter Five, indicated that attentional control and working memory were not associated with worry in adolescence. Moreover, these executive functions did not moderate the association between cognitive biases and worry. In Chapter Six, an experimental study was designed to assess the effect of active worry on working memory capacity using a worry induction paradigm in a community sample of adolescents. In line with the findings of Chapter Five, active worry did not impair working memory capacity in adolescents. The research presented in this thesis indicates that cognitive biases are mechanisms underlying worry in adolescence, however evidence that executive functions play a role in adolescent worry was not supported. Future research using longitudinal and experimental designs would provide further insight into the causal mechanisms underlying worry in adolescence and how these cognitive processes interact and develop over time.
Neo-traditionalism in the West: navigating modernity, tradition, and politics
Keywords: Modernity
Islam in the West
Hamza Yusuf
Neo-traditionalism
Umar Faruq Abd-Allah
Abdal Hakim Murad

The present thesis studies the emergence of neo-traditionalism, its public pedagogues and their students (seekers of sacred knowledge), in the West. These pedagogues, many of whom Western-born converts, emerged in the 1990’s after having culminated their studies in the ‘traditional centres’ of knowledge in the Muslim world. They came back with the intent of transmitting the ‘traditional’ knowledge they attained to the wider Muslim community. Of these, this research focuses primarily on Hamza Yusuf, Abdal Hakim Murad, and Umar Faruq Abd-Allah. To their community of followers and students – known as ‘seekers of sacred knowledge’, they represented a connection to an authentic religious tradition marginalised by modernist voices. Their religious discourse was both highly intellectual and deeply spiritual; at a time when there was a seeming decline in both intellect and spirituality. The shuyūkh disseminate their traditional knowledge in religious retreats. These retreats – often– are isolated from the modern world and imbued with traditional symbolism. In these spaces, the shuyūkh provide the desirable orientations to the sacred world in Islam, and a rejection of the modern world around them. That is, the retreat provides both 'ways of seeing' as well as 'what is to be seen' as part of Islam within modernity. The central thrust of the sites of the transaction of sacred knowledge is to 'school' the learners into different narratives of the spiritual decline under modern condition. In the Muslim specific context, this led to the rise of different modernist post-colonial movements and activist tendencies. Such trends obscured Muslim metaphysical outlook. The shuyūkh’s critiques of modernity and discourses on the side lining of metaphysics interpret these in terms of the wider political and social principles. This research shows, on the one hand, how the neo-traditionalist shuyūkh conceive of modernity, tradition, and how that impacts their political discourse on issues such as dissent, race, belonging, and gender. The research highlights how the critique of ‘modernity’ is interlinked and reaffirms notions of authority and stability. On the other hand, it shows, through field interviews with seekers who attended their religious retreats, how young Muslims negotiate and navigate these discourses on modernity, tradition, and politics.
Hegel, Marx and the state as a prerequisite for freedom
Keywords: political philosophy
Marx
Hegel

In my thesis, I discuss the dispute between Hegel and Marx over whether or not the state is necessary for human freedom. According to Hegel, the state is necessary for such freedom because he believed that humans require a family life for love and support, but as family life is characterized by natural necessity, it cannot be truly free. Therefore, beyond family life, there must be a civil society where individuals approach one another as self-sufficient beings fully conscious of their independence from one another. But this atomistic relation of individuals to one another within civil society then requires that the state exist beyond it as an institution in which the interests of these different individuals are unified into one will in order to return unity to society. However, Marx believed that the state is incompatible with social freedom because it is an institution for the rule of one class over another rather than a general will for society.
My thesis will discuss the opposition between Marx and Hegel with special reference to Hegel’s 'Elements of the Philosophy of Right' and Marx’s 'Critique of Hegel’s Philosophy of Right,' 'Civil War in France' and 'Critique of the Gotha Programme.' First I will present Hegel’s theory of why the state is necessary for human freedom and then I will present a critique of Hegel’s theory of the rational society. I will then explain Marx’s theory of the state and why Marx believed the state is incompatible with social freedom. Then I will defend Marx’s position against Hegel by arguing that social freedom does not require the state because it is possible for a mediated substantial unity (a unity between individuals in which they still also recognise themselves as particulars) to exist even without the state.
Magnetic-field amplification in turbulent laser-plasmas
Keywords: Astrophysical plasmas
Proton radiography
Plasma dynamo
Proton imaging

Understanding magnetic-field generation in turbulent plasma is essential for explain- ing the presence of dynamically significant magnetic fields in astrophysical environments such as the intracluster medium. Seemingly plausible theoretical frameworks attributing the origin and sustainment of these fields to amplification by the so-called fluctuation dynamo are somewhat hampered by conceptual uncertainties concerning the validity of the models in which these frameworks are formulated. A recent experiment on the OMEGA laser facility attempted to overcome some of these uncertainties by demonstrating the feasibility of magnetic-field amplification by stochastic motions up to dynamical strengths in actual turbulent plasma. In order to realise the scientific goals of this experiment, accurate measurements of stochastic magnetic fields arising in turbulent laser-plasmas were required. This thesis reports on the development of an analysis technique which meets this requirement by recover- ing the magnetic-energy spectrum from proton imaging data, as well as the mean magnetic-energy density and characteristic structure sizes. The general applicability and reliability of the technique is considered in depth. On application to data derived from the OMEGA experiment, the magnetic-energy density is found to increase over five hundred times in the experiment from its initial value; in addition, estimates of the maximum magnetic field strength indicate that the field is likely to be dynamically significant. The experiment therefore constitutes the first demonstration in the laboratory of the fluctuation dynamo. The results of a second experiment on the OMEGA laser facility – in which a remodelled variant of the previously employed experimental platform is used to provide a time-resolved characterisation of a plasma dynamo’s evolution, measuring temperatures, densities, flow velocities and magnetic fields – are also described. It is shown that the initial growth of the dynamo-generated fields occurs exponentially at a rate which significantly exceeds the turnover rate of the driving-scale stochastic motions in the plasma. Both experiments validate the claim that the fluctuation dynamo is indeed capable of amplifying magnetic fields significantly.
Diets in England: change, continuity and regionality between the Iron Age and Domesday Book (700 B.C -1086 A.D.)
Keywords: Isotope

Quantitative MRI has promise to provide precise measures for assessing neurological disorders such as amyotrophic lateral sclerosis (ALS). While MRI is very sensitive to pathological changes in tissue, it lacks the specificity needed for biological interpretability. One way to address this is to compare MRI to more direct measurements, such as histopathology. In this thesis, I present methods that enable direct comparison of quantitative T2 imaging to histopathology in the same post-mortem tissue samples, with the aim of better understanding alterations to T2 in ALS. This requires that we address several challenges to acquiring T2 maps in post-mortem brains, particularly in the context of our study at 7 tesla. First, 7T MRI exhibits considerable spatial inhomogeneity of the B1 field, leading to non-exponential signal evolution. To more accurately model the signal, we utilize the extended phase graph (EPG) model and derive voxel-wise maps of B1, T2 and S0 simultaneously. We show that EPG fitting provides improved T2 mapping under inhomogeneous B1 field. A second issue for quantitative T2 mapping in post-mortem brains is the influence of formalin fixation, which can dramatically reduce the T2 value in proportion with the formalin concentration distribution. We propose a kinetic tensor (KT) model to simulate 4D formalin flux under Fick’s diffusion law. Based on the KT prediction of formalin concentration, we propose a simple linear correction of quantitative T2 maps. Combining EPG fitting with the KT correction, we demonstrate that quantitative T2 map values in motor cortex can distinguish ALS brains from the control group, and that quantitative T2 value is significantly correlated to the tissue ferritin content. This work provides evidence that quantitative T2 mapping may provide a non-invasive marker of cortical iron deposition in ALS.
Freedom and ethics in Madhyamaka Buddhism
Keywords: Moral Responsibility
Madhyamaka
Paleo-compatibilism
Free Will

This research project articulates the relationship between freedom and ethics in Indian Madhyamaka. Chapter 1 provides a defence of anti-realist interpretations of Madhyamaka, the ramifications of which are felt throughout the remainder of the investigation. Chapter 2 introduces the reconstructive, cross-cultural and, at times, a-historical methodology used to explicate Madhyamaka’s implied stance on issues such as free will and the naturalistic fallacy. Chapter 3 examines the suitability of ‘paleo-compatibilism’ as a potential solution to the Buddhist free will problem, arguing that, with some modifications, it could be viable in a Madhyamaka context. Chapter 4 investigates the similarities and differences between the Western theory of causal determinism and the Madhyamaka doctrine of dependent origination: dependency relations encompass but are not coterminous with causal relations. Chapter 5 examines ‘perspectivalism,’ another proposed solution to the Buddhist free will problem, but contends that it is better conceived of as a meta-theory about free will rather than as simply another theory. From chapter 6 onwards, the focus moves from ‘free will’ to ‘freedom’ of a spiritual kind. Chapter 6 seeks to negotiate the tension in Madhyamaka’s conception of karma as both that which binds beings to saṃsāra and, through the accumulation of merit, as a facilitator of liberation. Chapter 7 introduces the ethical ideal of the bodhisattva figure and considers the coherence of Madhyamaka’s conception of a Buddha’s non-karmic moral action. Chapters 8 and 9 articulate the implied Madhyamaka view on a range of meta-ethical questions, such as whether moral sentences can be truth-apt and whether Madhyamaka can respond to accusations that it commits the naturalistic fallacy. Chapter 10 offers some concluding remarks on the value of cross-cultural philosophical engagement and summarizes this project’s key findings.
Development of high-throughput imaging mass spectrometry
Keywords: Imaging mass spectrometry
high-throughput
high resolution
data analysis
genetic algorithm
broad mass range

Mass specific surface images with micron and sub-micron spatial resolution can be recorded with a mass spectrometer. Ion microscope mass spectrometry imaging uses a defocused laser or ion beam to simultaneously analyse large sample areas. The ions are subsequently separated by their time-of-flight (ToF) and their spatial location is electrostatically transferred onto a two-dimensional position-sensitive detector. The detected ions are converted to light and recorded by either, a charged coupled device (CCD) camera and a photo multiplier tube (PMT), or an event-triggered complementary metal-oxide semiconductor (CMOS) sensor. CMOS sensors such as the Timepix3 cam and a PImMS camera are capable of multi-mass ion imaging. The result is a series of images corresponding to each recorded m/z, further demonstrating the high-throughput capability of the instrument.
An ion microscope has three drawbacks when compared to microprobe MSI: low mass resolution, a small mass range and poor spatial resolution. For each of these limitations, this thesis presents a solution that can be applied simultaneously to improve the performance and applicability.
An ion microscope, incorporating a reflectron, was used to simultaneously image mass-resolved ions generated from a 0.3mm diameter surface. Mass and spatial resolutions of 8100±700m/Δm and 14 μm were obtained by using post extraction differential acceleration (PEDA) ion optical focusing to create a pseudo-source plane for a single-stage gridless reflectron. The obtainable mass resolution was limited only by the response time of the position-sensitive detector, and could potentially reach 30 200±2900m/Δm.
Single-field PEDA has a mass-resolved window that is approximately 19% of the spatially-resolved mass window. A time-dependent pulse applied after ions have exited the extraction region facilitates an increase in the mass resolution over the entire spatially resolved mass range. The potential energy surface of the time-dependent pulse is chosen so that it approximates the dependency between the ion ToF and molecular weight. Mass resolution between 2500 - 8100m/Δm has been achieved for ions between 300 - 625 Da, whilst preserving approximately 14 μm spatial resolution.
The spatial resolution has been improved in silico with the introduction of a four-plate ion optic. The electrode arrangement and potentials have been optimised using minimisation routines. An 800 nm spatial resolution has been achieved with the optimised ion optics.
The Timepix3 cam has recorded time resolved ion images from a reflectron ion microscope. The camera has been operated in continuous readout mode and the individual experiments have been separated using optical fibre that directs part of the laser pulse onto the sensor. This provides an alternative to the expensive readout systems that are typically used. The resolutions achieved with this technique are comparable to those obtained using a CCD/PMT combination.
Adaptive timestepping for SDEs with non-globally Lipschitz drift
Keywords: Chaotic System
Multilevel Monte Carlo
Numerical method
Adaptive
Ergodic SDE

In this thesis, we focus on the numerical approximation of SDEs with a drift which is not globally Lipschitz, and corresponding sensitivity calculations.
First, we propose an adaptive timestep construction for an Euler- Maruyama approximation of these SDEs over a finite time interval. It is proved that if the timestep is bounded appropriately, then over a finite time interval the numerical approximation is stable, and the expected number of timesteps is finite. Moreover, we extend this scheme to ergodic SDEs with contractivity over an infinite time interval and prove that the bound for moments and the strong error of the numerical solution are uniform in T, which allow us to introduce the adaptive multilevel Monte Carlo (MLMC) method to further improve the efficiency.
Next, we apply a new MLMC method for the ergodic SDEs without contractivity. By introducing a change of measure technique, we simulate the paths with contractivity and add the Radon-Nikodym derivative to the estimator. It is shown that the variance of the new level estimators increases linearly in T, which is a great reduction compared with the exponential increase in the standard MLMC.
Lastly, we derive a new pathwise sensitivity estimator for chaotic SDEs by introducing a spring term between the original and perturbed SDEs. The variance of the new estimator increases only linearly in time T; compared with the exponential increase of the standard pathwise estimator. We also consider using this estimator for the SDE with Richardson-Romberg extrapolation on the volatility parameter to approximate the sensitivities of the invariant measure of chaotic ODEs.
All of the analysis is supported by numerical results.
The interaction between reward-driven learning and selective attention
Keywords: fmri
visual attention
reward learning
magnetoencephalography
selective attention
reinforcement learning
functional magnetic resonance imaging

Selective attention is the prioritisation of certain pieces of information over others, and is often guided by task goals or by physical salience. Attention can also be guided by stimuli previously learned to be associated with reward which can capture attention in the absence of task relevance or physical salience—a phenomenon termed value-driven attentional capture (VDAC; reviewed in Chapter 1). The first part of this thesis examines the cognitive and neural mechanisms of VDAC. Chapter 2 shows that stimuli with reward history can rapidly capture spatial attention without being currently task-relevant (akin to exogenous cues) and can also sustain attention over intervals as long as one second. Chapter 3 examines the neural mechanisms of VDAC using multivariate pattern analysis of magnetoencephalography data. Learned value modulates spatial representations of stimuli within posterior visual, parietal, and inferior temporal cortex, and this relates to the magnitude of the behavioural VDAC effect. No evidence was found suggesting that non-spatial features are similarly modulated. A stimulus-independent value signal was also found in insular and posterior visual and parietal cortex. However, the relatively late onset of these modulations during visual processing (~250ms) suggests that value signals may first arise elsewhere. The second part of this thesis describes a behavioural and functional magnetic resonance imaging (fMRI) study in macaques which examines the impact of stimuli with reward history on reward learning and decision-making, and the brain regions that represent reward history and other parameters relevant to these processes. Chapter 4 shows that the reward history of a currently unrewarded option interferes with decision-making, possibly by slowing subjects’ learning rates. Chapter 5 describes fMRI analyses showing that regions within the ventromedial prefrontal cortex (vmPFC) and ventrolateral prefrontal cortex (vlPFC) track the learned value of stimuli. Analyses also revealed activity consistent with value comparison signals in the vmPFC, reward prediction error (RPE) signals in the amygdala and putamen, and unsigned RPE (“attention”) signals in the putamen, anterior cingulate cortex, and the vlPFC. However, fMRI analyses were not able to clearly explain the impact of reward history in the current study; possible reasons for this are discussed. Chapter 6 summarises the findings and their limitations and places them in the broader context of the interaction between learning and attention.
Multiscale turbulence in magnetic confinement fusion devices
Keywords: Ion Scale
Cross-scale Interaction
Magnetised Plasma Turbulence
Gyrokinetics
ITG
ETG
Electron Scale
Multiscale
Magnetic Confinement Fusion

Turbulence in magnetised plasmas is driven by microinstabilities which exist at the spatial scales of the ion and the electron thermal gyroradii, with time scales corresponding to the ion and the electron thermal speeds, respectively. Hence, plasma turbulence can have a well-separated long wavelength "ion scale" (IS) and short wavelength "electron scale" (ES), where the separation is controlled by the electron-to-deuterium mass ratio (me/mi)1/2 = 1/60. Resolving multiscale plasma turbulence in direct numerical simulations (DNS) is costly due to the small value of (me/mi)1/2; nonetheless, several DNS have been performed which show that interactions between the long wavelength and the short wavelength pieces of the turbulence can be important for determining the character of the turbulence. In this thesis we find scale-separated, coupled equations for the IS and the ES pieces of the turbulence, valid in the limit that (me/mi)1/2 → 0. These equations can be efficiently simulated in a system of coupled flux tubes. The equations provide insight into the mechanisms and the impact of the cross-scale interactions between the IS and the ES pieces of the turbulence, whilst avoiding the cost of DNS. We find that to leading order the IS turbulence evolves independently of the ES turbulence. The ES turbulence is sheared by parallel variation in the IS E × B drift, and the drive of instability at the ES is modified by the gradient of the IS distribution function. We study the effect of IS turbulence on the linear stability of the electron temperature gradient (ETG) mode. We find that a strongly driven ETG instability is stabilised by strongly driven IS turbulence, but is only weakly suppressed by IS turbulence driven near marginal stability. We identify the dominant suppression mechanism as parallel-to-the-field shear in the IS E × B drift: the simple nature of this suppression mechanism may explain why short wavelength turbulence saturates at a low level in the presence of strongly driven long wavelength turbulence in DNS.