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Jin Ma. A colleague, a thinker, a scholar, a husband and father, but most of all: a friend. In a previous lifetime, or so it seems, I worked at Purdue University, in West Lafayette, Indiana. During my time at Purdue, I had the good fortune to hire Jin Ma as a postdoc, fresh from his PhD at the University of Minnesota. He was so outstanding we were able to change his status after two years, from a postdoc to tenure track. The rest was inevitable: Associate Professor, and then Professor.
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Thermal Evolution of the 3 Ma to 0.1 Ma Goat Rocks Volcanic Complex, Washington Cascades
Interpretation of magma storage temperature in time at the Goat Rocks Volcanic Complex SW Washington Cascades
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- Award ID(s):
- 1939347
- PAR ID:
- 10337335
- Date Published:
- Journal Name:
- American Geophysical Union
- Volume:
- V-11A
- Issue:
- 06
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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This paper presents a novel semantics for the mA* epistemic action language that takes into consideration dynamic per-agent observability of events. Different from the original mA* semantics, the observability of events is defined locally at the level of possible worlds, giving a new method for compiling event models. Locally defined observability represents agents' uncertainty and false-beliefs about each others' ability to observe events. This allows for modeling second-order false-belief tasks where one agent does not know the truth about another agent's observations and resultant beliefs. The paper presents detailed constructions of event models for ontic, sensing, and truthful announcement action occurrences and proves various properties relating to agents' beliefs after the execution of an action. It also shows that the proposed approach can model second order false-belief tasks and satisfies the robustness and faithfulness criteria discussed by Bolander (2018, https://doi.org/10.1007/978-3-319-62864-6_8).more » « less
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Abstract Our study used zircon (U-Th)/He (ZHe) thermochronology to resolve cooling events of Precambrian basement below the Great Unconformity surface in the eastern Grand Canyon, United States. We combined new ZHe data with previous thermochronometric results to model the <250 °C thermal history of Precambrian basement over the past >1 Ga. Inverse models of ZHe date-effective uranium (eU) concentration, a relative measure of radiation damage that influences closure temperature, utilize He diffusion and damage annealing and suggest that the main phase of Precambrian cooling to <200 °C was between 1300 and 1250 Ma. This result agrees with mica and potassium feldspar 40Ar/39Ar thermochronology showing rapid post–1400 Ma cooling, and both are consistent with the 1255 Ma depositional age for the Unkar Group. At the young end of the timescale, our data and models are also highly sensitive to late-stage reheating due to burial beneath ∼3–4 km of Phanerozoic strata prior to ca. 60 Ma; models that best match observed date-eU trends show maximum temperatures of 140–160 °C, in agreement with apatite (U-Th)/He and fission-track data. Inverse models also support multi-stage Cenozoic cooling, with post–20 Ma cooling from ∼80 to 20 °C reflecting partial carving of the eastern Grand Canyon, and late rapid cooling indicated by 3–7 Ma ZHe dates over a wide range of high eU. Our ZHe data resolve major basement exhumation below the Great Unconformity during the Mesoproterozoic (1300–1250 Ma), and “young” (20–0 Ma) carving of Grand Canyon, but show little sensitivity to Neoproterozoic and Cambrian basement unroofing components of the composite Great Unconformity.more » « less
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Accepted Manuscript1.0
- Conference Paper:
- The DOI is not currently available.
