Driving factors of slab geometry between depths of 400-1000 km

Through seismic imaging, varying geometries of slab subduction are noted throughout the mantle. While some slabs remain mostly unaffected when penetrating down to the lower mantle (e.g. Mariana plate/trench), others appear to flatten out and lie along the 660 km discontinuity (e.g. Izanagi plate). Penetrating slabs with moderate dip angles (e.g. South American plate/Peru-Chile trench) are also observed. The exact cause of these varying geometries is largely unknown. This study attempts to identify if a variation in slab geometry at the upper lower mantle transition zone is caused by an internal (e.g. phase change, viscosity structure, Rayleigh number) or external (trench migration) processes of subduction. The mantle flow regime of the mantle has also been assessed. Mantle convection models with tectonic surface boundary reconstructions were grouped together according to their specific input parameters and then had their present-day temperatures compared to seismic tomography. Matches and mismatches to tomography were analysed and quantified on global and regional scales. The presence of switching geometries throughout a slab’s evolution has led this study to favour a whole mantle convection regime with compositionally different layers. Results from comparisons of mantle flow models with tomography indicate that the presence of a phase change and a change in viscosity structure, two internal parameters, have little effect on the variation of slab geometry. More significantly, a change in the Rayleigh number caused major variations, with too low and too high a convection vigour resulting in a variation of predicted slab material between mantle flow models. The external parameter of surface boundary reconstructions was observed to be the main contributor to a high variation in predicted slab geometry. When modelled through time, both the internal and external parameters displayed the same level of variation seen at present day. In the evolution of subduction, each modelled slab location was seen to start as a steeply penetrating slab. Trench migration at the surface caused upper mantle material to migrate at a high rate, while material in the lower mantle moved at a lower rate, resulting in a decrease in the angle of slab penetration in the lower mantle. Trench migration appears to be the key factor in shaping slab geometry

Information, Design, and Support OH MY!

Overview of the teaching and learning support services available in the Lamson Learning Commons. -Pedagogy and course design -Research and information literacy -Instructional Technology -Writin

Energy-Constrained Programmable Matter Under Unfair Adversaries

Individual modules of programmable matter participate in their system's collective behavior by expending energy to perform actions. However, not all modules may have access to the external energy source powering the system, necessitating a local and distributed strategy for supplying energy to modules. In this work, we present a general energy distribution framework for the canonical amoebot model of programmable matter that transforms energy-agnostic algorithms into energy-constrained ones with equivalent behavior and an $\mathcal{O}(n^2)$-round runtime overhead -- even under an unfair adversary -- provided the original algorithms satisfy certain conventions. We then prove that existing amoebot algorithms for leader election (ICDCN 2023) and shape formation (Distributed Computing, 2023) are compatible with this framework and show simulations of their energy-constrained counterparts, demonstrating how other unfair algorithms can be generalized to the energy-constrained setting with relatively little effort. Finally, we show that our energy distribution framework can be composed with the concurrency control framework for amoebot algorithms (Distributed Computing, 2023), allowing algorithm designers to focus on the simpler energy-agnostic, sequential setting but gain the general applicability of energy-constrained, asynchronous correctness.Comment: 31 pages, 4 figures, 1 table. Submitted to OPODIS 202

The Gospel : according to Matt

The Gospel: According to Matt is a novel, told in the first person, simple past tense, depicting the struggle of a young man attempting to make sense of his relationship with his estranged father as he wrestles with a growing crisis of faith. Matt is deeply sincere in his desire to do right, but he is, at heart, skeptical of the teachings of his mother's fundamentalist church. In the beginning of the novel Matt attempts to avoid confronting his own feelings about faith. The novel consists of four major movements, two of which are explored in the present document. The first of these details Matt's trip across the county with his father, a rowdy truck driver. Matt's conservative Christian values are challenged at every turn by his father's behavior and outlook, which are foreign to him. Matt finds himself compromising his principles in small things, and he must face his growing fear that, inside, he is just like his father. In the second movement, Matt is dropped off by his father at a summer Bible camp, where he expects to find companionship and guidance that will reestablish his faith. In the camp, though, he is disappointed to find that his peers do not take their faith as seriously as he tries to take his, and some are even engaged in sexual activity while in camp. Further, Matt is thrown off balance by the secular and liberal viewpoints of some of the faculty. In the creation of this document I have paid special attention to the voice of the narrator in an attempt to capture the nuance of late adolescence, while balancing the perspective of a retrospective narrator who is aware of the irony of the situations and experiences he is recounting