Evaluating stress patterns for Plio-Quaternary brittle deformation along the Calama-Olacapato-El Toro fault zone, Central Andes

Understanding the geometry and kinematics of the major structures of an orogen is important to elucidate its style of deformation, as well as its tectonic evolution. We describe the temporal and spatial changes in the state of stress of the trans-orogen area of the Calama-Olacapato-El Toro (COT) Fault Zone in the Central Andes, at about 24°S within the northern portion of the Puna Plateau between the Argentina-Chile border. The importance of the COT derives principally from the Quaternary-Holocene activity recognized on some segments, which may shed new light on its possible control on Quaternary volcanism and on the seismic hazard evaluation of the area. Field geological surveys along with kinematic analysis and numerical inversion of ∼140 new fault-slip measurements have revealed that this portion of the COT zone, previously considered a continuous, long-lived lineament, in reality has been subjected to three different kinematic regimes: 1) a Miocene transpressional phase with the maximum principal stress (σ1) chiefly trending NNE-SSW; 2) an extensional phase that started by 9 Ma, with a horizontal NW-SE-striking minimum principal stress (σ3) – permutations between σ2 and σ3 axes have been recognized at two sites – and 3) a left-lateral strike-slip phase with a horizontal ∼E-W &sigma1 and ∼N-S σ3 dating to the Late Pliocene-Quaternary. Spatially, in the Quaternary, the left-lateral component decreases toward the westernmost tip of the COT, where it transitions to extension; this produced to a N-S horst and graben structure. Hence, even if transcurrence is still active in the eastern portion of the COT, as focal mechanisms of crustal earthquakes indicate, our study demonstrates that extension is becoming the predominant structural style of deformation, at least in the western region. These major temporal and spatial changes in the tectonic regimes are attributed in part to changes in the magnitude of the boundary forces due to subduction processes. The overall orogen-perpendicular extension might be the result of vertical stress larger than both the horizontal stresses induced by gravitational effect of a thickened crust.

BUILDING A DISCOURSE: BRIDGING THE GAP BETWEEN NEW MEDIA'S CONVERGENCE AND RHETORIC AND COMPOSITION'S MULTIMODALITY

My dissertation emphasizes the use of narrative structuralism and narrative theories about storytelling in order to build a discourse between the fields of New Media and Rhetoric and Composition. Propp's morphological analysis and the breaking down of stories into component pieces aides in the discussion of storytelling as it appears in and is mediated by digital and computer technologies. New Media and Rhetoric and Composition are aided by shared concerns for textual production and consumption. In using the notion of "kairotic reading" (KR), I show the interconnectedness and interdisciplinarity required in the development of pedagogy utilized to teach students to develop into reflective practitioners that are aware of their rhetorical surroundings and can made sound judgments concerning their own message generation and consumption in the workplace. KR is a transferable skill that is beneficial to students and teachers alike. The dissertation research utilizes theories of New Media and New Media-influenced practitioners, including Jenkins' theory of convergence, Bourdieu's notion of taste, Gee's term "semiotic domains," and Manovich's "modification." These theoretical pieces are combined in order to show how KR can be extended by convergent narrative practices. In order to build connections with New Media, the consideration and inclusion of Kress and van Leeuwen's multimodality, Selber's "reflective practitioners," and Selfe's definition of multimodal composing allow for a greater establishment of conversation order to create a richer conversation around the implications of metacognitive development and practitioner reflexivity with scholars in New Media. My research also includes analysis of two popular media franchises Deborah Harkness' A Discovery of Witches and Fox's Bones television series to show similarities and differences among convergence-linked and multimodal narratives. Lastly, I also provide example assignments that can be taken, further developed, and utilized in classrooms engaging in multimodal composing practices. This dissertation pushes consideration of New Media into the work already being performed by those in Rhetoric and Composition.

DEVELOPMENT OF PRECIPITATION HARDENABLE AL-SC-ZR-HF QUATERNARY ALLOYS THROUGH THERMODYNAMIC MODELING, AND ROOM-TEMPERATURE AND ELEVATED TEMPERATURE HARDNESS

Aluminum alloyed with small atomic fractions of Sc, Zr, and Hf has been shown to exhibit high temperature microstructural stability that may improve high temperature mechanical behavior. These quaternary alloys were designed using thermodynamic modeling to increase the volume fraction of precipitated tri-aluminide phases to improve thermal stability. When aged during a multi-step, isochronal heat treatment, two compositions showed a secondary room-temperature hardness peak up to 700 MPa at 450°C. Elevated temperature hardness profiles also indicated an increase in hardness from 200-300°C, attributed to the precipitation of Al3Sc, however, no secondary hardness response was observed from the Al3Zr or Al3Hf phases in this alloy.

RATE OF CONVERGENCE OF MAXIMUM LIKELIHOOD ESTIMATORS UNDER RELAXED SMOOTHNESS CONDITIONS ON THE LIKELIHOOD FUNCTION

This report reviews literature on the rate of convergence of maximum likelihood estimators and establishes a Central Limit Theorem, which yields an O(1/sqrt(n)) rate of convergence of the maximum likelihood estimator under somewhat relaxed smoothness conditions. These conditions include the existence of a one-sided derivative in θ of the pdf, compared to up to three that are classically required. A verification through simulation is included in the end of the report.