Applications of Unidirectional Flow Models to Lower Crustal Deformation

Honors (Bachelor's)Geological SciencesUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/91784/1/slui.pd

Earthquake Source Characterization Through Seismic Observations and Numerical Modeling

In this thesis, I present a series of works on the characterization of source properties and physical mechanisms of various small to moderate earthquakes through both observational and numerical approaches. From the results, we find implications on a broader scheme of topics relating to larger earthquakes, shear zone structure, frictional properties of faults, and seismic hazard assessment. Part I consists of two studies using waveform modeling. In Chapter 2, we present an in-depth study of a series of intraslab earthquakes that occurred in a localized region near the downdip edge of the 2011 Mw Tohoku-Oki megathrust earthquake. By refining source parameters of selected events, simulating their rupture properties and comparing their mechanisms to stress changes caused by the main shock in the region, we are able to identify the true rupture plane and the reactivation of a subducted normal fault, enhancing our understanding on the downdip shear zone. In Chapter 3, based on similar techniques, we further develop a systematic methodology to perform fast assessments on important source properties as an earthquake occurs. For two Mw 4.4 earthquakes in Fontana, moment magnitude and focal mechanism can be accurately estimated with 3 to 6 s after the first P-wave arrival, while focal depth can be constrained upon the arrival of S waves. Rupture directivity can also be determined with as little as 3 seconds of P waves. This study opens the opportunity to predict ground motions ahead of time and can potentially be useful for Earthquake Early Warning. Part II involves the modeling of seismic source properties and physical mechanisms of interacting earthquakes in dynamic rupture simulations. In particular, we focus on small repeating earthquake sequences that trigger one another. In Chapter 4, we quantify the relative importance of physical mechanisms that contribute to earthquake interaction and identify that the stress change caused by post seismic slip is the dominating factor. Our findings introduce the possibility to constrain frictional properties of the fault based on earthquake interactions. We further apply this working model in Chapter 5 to reproduce the actual interacting repeating sequences in Parkfield. We are able to identify possible physical mechanisms that cause the inferred high stress drops of these repeating events, as well as reproduce their synchronized seismic cycles. Results from our simulations are consistent with the observed scaling relation between the recurrence time interval and the seismic moment of these events. Our findings indicate that the difference between the observed and the theoretical scaling relations can be explained by the significant aseismic slip in the rupture area.</p

Reducing iatrogenic hypoglycemia in hyperkalemic patients treated with insulin therapy with a modified hyperkalemia order set at The Queen’s Medical Center

D.N.P.D.N.P. Thesis. University of Hawaiʻi at Mānoa 201

Evaluation of Hybrid Arc and Volumetric-Modulated Arc Therapy Treatment Plans for Fractionated Stereotactic Intracranial Radiotherapy.

PURPOSE: The study was aimed to compare hybrid arc and volumetric-modulated arc therapy treatment plans for fractionated stereotactic radiotherapy of brain tumors. METHODS: Treatment plans of 22 patients were studied. Hybrid arc and volumetric-modulated arc therapy plans were generated using Brainlab iPlanDose and Varian Eclipse treatment planning systems, respectively, with 6 MV photon beams on a Varian TrueBeam STx linear accelerator (Palo Alto, CA). Prescription dose was 54 Gy. The fractionation was 1.8 Gy per fraction and 30 fractions in total, or 2 Gy per fraction and 27 fractions in total. Planning target volume ranged from 2.4 to 28.6 cm RESULTS: Conformity indexes of hybrid arc and volumetric-modulated arc therapy plans are 1.10 ± 0.10 and 1.14 ± 0.07, respectively ( P = .4); gradient indexes are 5.02 ± 1.20 and 5.64 ± 1.28, respectively ( P = .0001); homogeneity indexes are 1.02 ± 0.01 and 1.05 ± 0.01, respectively ( P = .0001); brainstem maximum doses are 53.87 ± 1.63 Gy and 54.06 ± 3.17 Gy, respectively ( P = .1); and optic chiasm maximum doses are 53.86 ± 1.28 Gy and 53.95 ± 1.81, respectively ( P = .4). The monitor unit efficiencies of hybrid arc and volumetric-modulated arc therapy plans are 2.57 ± 0.25 MU/cGy and 2.68 ± 0.24 MU/cGy, respectively ( P = .2). The differences of conformity index, gradient index, and homogeneity index between hybrid arc and volumetric-modulated arc therapy plans are small: 0.08 ± 0.05, 0.65 ± 0.46, and 0.02 ± 0.01, respectively. The maximum doses in organs at risks are similar between hybrid arc and volumetric-modulated arc therapy plans. Hybrid arc and volumetric-modulated arc therapy plans, which have similar monitor unit efficiencies, present similar dosimetric results in the fractionated intracranial radiotherapy

James Webb Space Telescope (JWST) Integrated Science Instruments Module (ISIM) Cryo-Vacuum (CV) Test Campaign Summary

JWST Integrated Science Instruments Module (ISIM) completed its system-level space simulation testing program at the NASA Goddard Space Flight Center (GSFC). In March 2016, ISIM was successfully delivered to the next level of integration with the Optical Telescope Element (OTE), to form OTIS (OTE + ISIM), after concluding a series of three cryo-vacuum (CV) tests. During these tests, the complexity of the mission has generated challenging requirements that demand highly reliable system performance and capabilities from the Space Environment Simulator (SES) vacuum chamber. The first test served as a risk reduction test; the second test provided the initial verification of the fully-integrated flight instruments; and the third test verified the system in its final flight configuration following mechanical environmental tests (vibration and acoustics). From one test to the next, shortcomings of the facility were uncovered and associated improvements in operational capabilities and reliability of the facility were required to enable the project to verify system-level requirements. This paper: (1) provides an overview of the integrated mechanical and thermal facility systems required to achieve the objectives of JWST ISIM testing, (2) compares the overall facility performance and instrumentation results from the three ISIM CV tests, and (3) summarizes lessons learned from the ISIM testing campaign