Non-collinear Magnetic Textures Studied by Neutron Scattering

Non-collinear magnetic structures, where the magnetic moments do not align along a single axis, can lead to interesting physical phenomena and potential device applications. In this dissertation, two specific non-collinear magnetic textures are studied which includes soft/hard bilayer and skyrmions. Soft/hard magnetic bilayer thin films have been widely used in data storage technologies and permanent magnet applications. Here, we use polarized neutron reflectometry (PNR) to study magnetic configuration in soft-hard bilayer heterostructure thin films designed with different sample geometry and material properties under a range of temperatures and fields. Comparing the PNR results to the micromagnetic simulations reveals that the interfacial magnetic configuration is highly dependent on thickness and saturation magagnetization of soft layer materials and external factors (field and temperature) and has a relatively weak dependence on hard layer properties. Magnetic skyrmions, another example of non-collinear structures, exhibit unique, technologically relevant pseudo-particle behaviors which arise from their topological protection, including well-defined, three-dimensional dynamic modes that occur at microwave frequencies. In this work, we use small angle neutron scattering (SANS) to capture the dynamics in hybrid skyrmions and investigate the spin wave structure. Performing simultaneous ferromagnetic resonance and SANS, the diffraction pattern shows a large increase in low-angle scattering which is present only in the resonance condition. This scattering pattern is best fit using a mass fractal model, which suggests the spin waves form a long-range fractal network. Overall, this dissertation contributes to a deeper understanding of the complex behavior and potential applications of non-collinear magnetic structures, particularly in soft/hard bilayer heterostructures and magnetic skyrmions

Workplace Violence in Chinese Hospitals: The Effects of Healthcare Disturbance on the Psychological Well-Being of Chinese Healthcare Workers

Healthcare disturbance is a form of workplace violence against healthcare workers perpetrated by patients, their relatives, and gangs hired by them. It is a prevalent phenomenon in China, where evidence suggests that it impacts on the job satisfaction of healthcare workers. This study aims to examine the relationship between healthcare disturbance, surface acting as a response to emotional labour, and depressive symptoms in Chinese healthcare workers. The study adopted a cross-sectional design and used an online survey methodology. Data were collected from 418 doctors and nurses from one hospital in China. The results showed that frequency of healthcare disturbance was positively related to surface acting and depressive symptoms, respectively; surface acting was also positively related to depression, while deep acting showed no effect on symptoms of depression. Furthermore, surface acting in response to emotional labour mediated the relationship between healthcare disturbance and depressive symptoms. The results highlight the importance of preventing healthcare disturbance and of training healthcare staff in strategies for managing emotional demands in reducing depressive symptoms in Chinese healthcare staff

Deductive Optimization of Relational Data Storage

Optimizing the physical data storage and retrieval of data are two key database management problems. In this paper, we propose a language that can express a wide range of physical database layouts, going well beyond the row- and column-based methods that are widely used in database management systems. We use deductive synthesis to turn a high-level relational representation of a database query into a highly optimized low-level implementation which operates on a specialized layout of the dataset. We build a compiler for this language and conduct experiments using a popular database benchmark, which shows that the performance of these specialized queries is competitive with a state-of-the-art in memory compiled database system