Magnetic Field Effects in Quantum Biology: Beyond the Radical Pair Mechanism

The effects of weak magnetic fields on biological systems have become an area of burgeoning research and interest in recent years. Specifically, the Radical Pair Mechanism (RPM) has been quite successful at beginning to explain phenomena such as avian magnetoreception, the magnetosensitivity of lipid peroxidation reactions and other such biological magnetic field effects (MFEs) - but there are still many questions to answer. This thesis addresses such questions, by proposing a new mechanism (D3M) to offer a new perspective on radical spin dynamics, and methods for amplifying biological MFEs

On the magnetosensitivity of lipid peroxidation: two- versus three-radical dynamics

This is the final version. Available on open access from the Royal Society of Chemistry via the DOI in this recordData availability: The datasets generated during the current study are available from the corresponding author on reasonable request.We present a theoretical analysis of the putative magnetosensitivity of lipid peroxidation. We focus on the widely accepted radical pair mechanism (RPM) and a recently suggested idea based on spin dynamics induced in three-radical systems by the mutual electron–electron dipolar coupling (D3M). We show that, contrary to claims in the literature, lipid peroxides, the dominant chain carriers of the autoxidation process, have associated non-zero hyperfine coupling interactions. This suggests that their recombination could, in principle, be magnetosensitive due to the RPM. While the RPM indeed goes a long way to explaining magnetosensitivity in these systems, we show that the simultaneous interaction of three peroxyl radicals via the D3M can achieve larger magnetic field effects (MFE), even if the third radical is remote from the recombining radical pair. For randomly oriented three-radical systems, the D3M induces a low-field effect comparable to that of the RPM. The mechanism furthermore immunizes the spin dynamics to the presence of large exchange coupling interactions in the recombining radical pair, thereby permitting much larger MFE at magnetic field intensities comparable to the geomagnetic field than would be expected for the RPM. Based on these characteristics, we suggest that the D3M could be particularly relevant for MFE at low fields, provided that the local radical concentration is sufficient to allow for three-spin radical correlations. Eventually, our observations suggest that MFEs could intricately depend on radical concentration and larger effects could ensue under conditions of oxidative stress.Engineering and Physical Sciences Research Council (EPSRC

Scenes of a sexual nature: theorising representations of sex and the sexual body in the sagas of the Icelanders

This thesis considers depictions of and discourse around sexual activity in the Íslendingasögur (the sagas of the Icelanders), also drawing on Eddic poetry, the samtíðarsögur (contemporary sagas), fornaldarsögur (legendary sagas) and riddarasögur (chivalric sagas) to give a broader view of sex in Old Norse literature. The Old Norse literary canon is extensive, and seduction, complicated love lives and sexual insults often lie at the heart of conflicts and fatalities. Where sex comes into focus, contextually and culturally relevant imagery and wordplay enliven the scenes, conveying the tension, humour, or erotic ambitions of the authors. The thesis explores how sex and sexuality are represented, possible reasons behind these methods, and their effect on the audience’s perspectives of sex and the body. Analysis of the language and context is supported by contemporaneous literature, cognitive metaphor theory and modern theories of sexuality and anthropology, providing fresh perspectives on well-known passages in the sagas. The first chapter concentrates on sexual metaphors, offering an assessment of different aspects of sexual language that feature in the sagas and identifying common themes, from the benign and regular euphemisms for sexual intercourse, to more obscure metaphors that are highly contextualised and ambiguous. The second chapter looks at public judgement in the form of gossip, which often serves as a vehicle for sexual material, as well as the methods and motivations behind its circulation. Chapter three considers the opposite: the private discussion of sex and sexual woes, with reference to Foucault and examples of the model of confession as precedent for honest and open discussion. The final chapter looks at how sex and the sexualised body are employed as a means of entertainment, bringing slapstick humour, jokes and grotesque imagery to even the bleakest situations, thus concluding an interdisciplinary, theoretically-inflected approach to the forms and functions of sex in the sagas

Monte-Carlo wavefunction approach for the spin dynamics of recombining radicals

This is the final published version; available from IOP Publishing via the DOI in this record.We adapt the Monte-Carlo wavefunction (MCWF) approach to treat the open-system spin dynamics of radical pairs subject to spin-selective recombination reactions. For these systems, nonLindbladian master equations are widely employed, which account for recombination via the non trace-preserving Haberkorn superoperator in combination with reaction-dependent exchange and singlet-triplet dephasing terms. We show that this type of master equation can be accommodated in the MCWF approach, by introducing a second type of quantum jump that accounts for the reaction simply by suitably terminating the propagation. In this way, we are able to evaluate approximate solutions to the time-dependent radical pair survival probability for systems that have been considered untreatable with the master equation approach until now. We explicate the suggested approach with calculations for radical pair reactions that have been suggested to be relevant for the quantum compass of birds and related phenomena.Engineering and Physical Sciences Research Council (EPSRC

Ecstatic Spaces

The chant shakes the crowd, uncorking the energy of the masquerade. This is our stomping ground. Nothing can hold us back. We display ourselves, we play ourselves. Uncontrolled bodies pelt rhythmically. Bouncing backsides, arms and legs move in all directions. In a mess of sweat, feathers, and beads, this ‘Jumbie’ is ready to come out. As I rush the stage, the music hits me. I am speechless, breathless, and removed. Out of body, I see the chaos on the streets below. I see the colors, the costumes, the mass of open mouths, singing and laughing. The crowd climaxes, delivered from reason. In that moment I saw the sweet revelry of an island I felt, more than ever, I belonged to. I wondered what that feeling was, why it happened, and when it would happen again. This is not an everyday occurrence; this is inexplicable excitement. It swamps all the senses. It is addictive; like a drug it keeps you coming back for more. It is an out-of-body experience and an opportunity to express your shadow self. Trinidad’s Carnival was introduced by the French and adapted by Trinidad’s diverse population. Trinidadian’s reinvent and revitalize new forms within carnival: it is uniquely theirs. The participants revel in a festival that is not only excessive, but also temporal, occurring outside of ordinary life. In the festival, everything is upside down and inside out. This inversion is expressed in laughter. The people of Trinidad communicate in the playful and sensuous nature of the carnival costume. They mock the seriousness of the political world, rejecting state and class. A medium for humor, the costumes stand in for the bodies we do not have; ambivalently, they both degrade and regenerate. Costumed, Carnival embraces laughter and the grotesque, and gives the community identity. The chaos of parade, music, and dance fuses the body with the costume, transforming the individual, freeing him from inhibitions. For a brief moment it allows the body to engage in its own ideal, becoming something that it is not. The fusion of body and Carnival costume tells the untold story of the masquerader. The four costume designs shown here are grotesque, making extreme exaggerations and unfathomable representations of the body, violating the idealized, classical body. The costumes portray the carnival body in the act of becoming, taking inspiration from earthy worldliness, while also giving out to it. Costume enables the individual to wake an essential connection to the community, becoming part of something larger. In this new connection we are emotionally reborn; Carnival moves us beyond our bodies and into the experience of ecstasy

How symmetry-breaking can amplify the magnetosensitivity of dipolarly coupled n-radical systems

This is the final version. Available on open access from AIP Publishing via the DOI in this recordData availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.In systems of more than two reactive radicals, the radical recombination probability can be magnetosensitive due to the mere effect of the inter-radical electron-electron dipolar coupling. Here, we demonstrate that this principle, previously established for three-radical systems, generalizes to n-radical systems. We focus on radical systems in the plane and explore the effects of symmetry, in particular its absence, on the associated magnetic field effects of the recombination yield. We show, by considering regular configurations and slightly distorted geometries, that the breaking of geometric symmetry can lead to an enhancement of the magnetosensitivity of these structures. Furthermore, we demonstrate the presence of effects at low-field that are abolished in the highly symmetric case. This could be important to the understanding of the behavior of radicals in biological environments in the presence of weak magnetic fields comparable to the Earth's, as well as the construction of high-precision quantum sensing devices.Engineering and Physical Sciences Research Council (EPSRC

Children and young adults who received tracheostomies or were initiated on long-term ventilation in PICUs

Objectives: To characterize patients who received tracheostomies for airway compromise or were initiated on long-term ventilation for chronic respiratory failure in pediatric intensive care units (PICU), and to examine variation in the incidence of initiation, patient characteristics, and modalities across sites. Design: Retrospective cross-sectional analysis. Settings: Seventy three North American PICUs that participated in the Virtual Pediatric Intensive Care Unit Performance System. Patients: PICU patients admitted between 2009 and 2011. Interventions: None. Measurements and Main Results: Among 115,437 PICU patients, 1.8% received a tracheostomy or were initiated on long-term ventilation; 1034 received a tracheostomy only, 717 were initiated on invasive ventilation (IV), and 381 were initiated on noninvasive ventilation (NIV). Ninety percent had substantial chronic conditions and comorbidities, including more than 50% with moderate or worse cerebral disability upon discharge. Seven percent were initiated after a catastrophic injury/event. Across sites, there was variation in incidence of tracheotomy and initiation of long-term ventilation, ranging 0–4.6%. There also was variation in patient characteristics, time to tracheotomy, number of extubations prior to tracheostomy, and the use of IV versus NIV. Conclusions: While the PICU incidence of initiation of tracheostomies and long-term ventilation was relatively uncommon, it suggests that thousands of children and young adults receive these interventions each year in North American PICUs. The majority of them have conditions and comorbidities that impose on-going care needs, beyond those required by artificial airways and long-term ventilation themselves

Addition of a channel for XCO observations to a portable FTIR spectrometer for greenhouse gas measurements

The portable FTIR (Fourier transform infrared) spectrometer EM27/SUN, dedicated to the precise and accurate observation of column-averaged abundances of methane and carbon dioxide, has been equipped with a second detector channel, which allows the detection of additional species, especially carbon monoxide. This allows an improved characterisation of observed carbon dioxide enhancements and makes the extended spectrometer especially suitable as a validation tool of ESA's Sentinel 5 Precursor mission, as it now covers the same spectral region as used by the infrared channel of the TROPOMI (TROPOspheric Monitoring Instrument) sensor. The extension presented here does not rely on a dichroic, but instead a fraction of the solar beam is decoupled near the aperture stop of the spectrometer using a small plane mirror. This approach allows maintaining the camera-controlled solar tracker set-up, which is referenced to the field stop in front of the primary detector. Moreover, the upgrade of existing instruments can be performed without alterating the optical set-up of the primary channel and resulting changes of the instrumental characteristics of the original instrument