Imaging the seismic velocity structure of the crust and upper mantle in the northern East African Rift using Rayleigh wave tomography

Understanding the dynamics and evolution of continental rifting is broadly important for our understanding of plate tectonics. The northern East African Rift offers an excellent opportunity to study these processes at an active rift that was initiated by a large magmatic event. Multiple seismic models have been produced to understand the evolution of magmatism which image punctuated slow velocity zones in the asthenosphere. However, the depth extent of the slow velocity bodies has been less well constrained leading to much debate regarding the primary controls on melt generation. Variations between methods, resolution, and scale of the seismic models make direct quantitative comparisons challenging. The lack of instrumentation off-rift further limits our understanding of the spatial extent of tectonic and magmatic processes, which is crucial to understanding magmatic continental rifting. In this paper, we jointly invert Rayleigh wave dispersion curves from ambient noise and teleseisms to obtain absolute shear velocity maps at 10–150 km depth. This includes data from a new seismic network located on the Ethiopian Plateau and enhanced resolution at Moho and upper mantle depths from the joint inversion. At crustal depths, velocities are slowest beneath the Main Ethiopian Rift and the off-rift Ethiopian Plateau (0.1 km/s faster than surroundings), in agreement with previous estimates of lithospheric thickness from receiver functions. The fast lid is not observed within the Main Ethiopian Rift or central Afar which instead are underlain by asthenospheric slow velocity anomalies (<4.05 ±0.04 km/s at 60–120 km depth). This suggests melt is infiltrating the lithosphere within the rift. Furthermore, punctuated asthenospheric slow velocity anomalies (∼110×80 km wide) exist in areas that have not undergone significant crustal and plate thinning, potentially indicating melt infiltration may start prior to significant plate deformation. Finally, the punctuated asthenospheric slow velocity zones are not located directly beneath melt-rich crustal regions including those off-rift, suggesting melt migration processes are dynamic and/or may occur laterally

Comprehensive molecular and clinical characterization of NUP98 fusions in pediatric acute myeloid leukemia

NUP98 fusions comprise a family of rare recurrent alterations in AML, associated with adverse outcomes. In order to define the underlying biology and clinical implications of this family of fusions, we performed comprehensive transcriptome, epigenome, and immunophenotypic profiling of 2,235 children and young adults with AML and identified 160 NUP98 rearrangements (7.2%), including 108 NUP98-NSD1 (4.8%), 32 NUP98-KDM5A (1.4%) and 20 NUP98-X cases (0.9%) with 13 different fusion partners. Fusion partners defined disease characteristics and biology; patients with NUP98-NSD1 or NUP98-KDM5A had distinct immunophenotypic, transcriptomic, and epigenomic profiles. Unlike the two most prevalent NUP98 fusions, NUP98-X variants are typically not cryptic. Furthermore, NUP98-X cases are associated with WT1 mutations, and have epigenomic profiles that resemble either NUP98-NSD1 or NUP98-KDM5A. Cooperating FLT3-ITD and WT1 mutations define NUP98-NSD1, and chromosome 13 aberrations are highly enriched in NUP98-KDM5A. Importantly, we demonstrate that NUP98 fusions portend dismal overall survival, with the noteworthy exception of patients bearing abnormal chromosome 13 (clinicaltrials gov. Identifiers: NCT00002798, NCT00070174, NCT00372593, NCT01371981).</p

Imaging lithospheric discontinuities beneath the Northern East African Rift using S -to-P receiver functions

Imaging the lithosphere is key to understand mechanisms of extension as rifting progresses. Continental rifting results in a combination of mechanical stretching and thinning of the lithosphere, decompression upwelling, heating, sometimes partial melting of the asthenosphere, and potentially partial melting of the mantle lithosphere. The northern East African Rift system is an ideal locale to study these processes as it exposes the transition from tectonically active continental rifting to incipient seafloor spreading. Here we use S‐to‐P receiver functions to image the lithospheric structure beneath the northernmost East African Rift system where it forms a triple junction between the Main Ethiopian rift, the Red Sea rift, and the Gulf of Aden rift. We image the Moho at 31 ± 6 km beneath the Ethiopian plateau. The crust is 28 ± 3 km thick beneath the Main Ethiopian rift and thins to 23 ± 2 km in northern Afar. We identify a negative phase, a velocity decrease with depth, at 67 ± 3 km depth beneath the Ethiopian plateau, likely associated with the lithosphere‐asthenosphere boundary (LAB), and a lack of a LAB phase beneath the rift. Using observations and waveform modeling, we show that the LAB phase beneath the plateau is likely defined by a small amount of partial melt. The lack of a LAB phase beneath the rift suggests melt percolation through the base of the lithosphere beneath the northernmost East African Rift system

The structure of strategic communication: Theory, measurement, and effects

This dissertation advances a novel approach that I refer to as the structure of strategic communication. Leveraging theory on how people naturally structure their arguments, this approach contends that organizational actors deploy arguments to influence others at two structurally distinct levels— within the rules of the game or about the rules of the game. This dissertation’s primary claim is that talking more about the rules of the game, which exposes the assumptions underlying our social institutions to direct examination, may have profound implications. I build evidence for this claim in two ways. First, I develop a new measurement called the argument structure ratio (ASR) that conceptually and empirically captures how explicit a speaker makes these assumptions in their communication. I outline a three-step methodology for measuring the ASR of any collection of written texts. Second, I theorize and empirically demonstrate how the ASR impacts an audience’s reaction. Using all public speeches made by the Chairperson of the United States Federal Reserve from 1998 to 2014, I show that the more they expose the assumptions underlying the Federal Reserve System, the more their speeches produce market uncertainty. I argue that these findings fundamentally change how we think about the role of strategic communication in market contexts. More generally, this work provides a new way to conceptualize and study strategic communication that extends well beyond financial markets to a variety of different organizational contexts and across multiple levels of analysis. Taken together, this dissertation provides a theoretical and methodological foundation upon which to conduct research on the structure of strategic communication

DS_10.1177_0001839218777475 – Supplemental material for When the Fed Speaks: Arguments, Emotions, and the Microfoundations of Institutions

<p>Supplemental material, DS_10.1177_0001839218777475 for When the Fed Speaks: Arguments, Emotions, and the Microfoundations of Institutions by Derek J. Harmon in Administrative Science Quarterly</p

The efficacy of an anatomy and ultrasonography workshop on improving residents’ confidence and knowledge in regional anesthesia

Abstract Background Ultrasound Guided Regional Anesthesia (UGRA) has become the standard for regional anesthesia practice, but there is not a standardized educational approach for training residents. The objective of this study was to evaluate the efficacy of an UGRA workshop utilizing the theoretical framework of embodied cognition for anesthesiology residents. Methods A workshop was developed consisting of didactics, scanning training on standardized patients (SPs) and anatomy reviews on prosected cadavers that focused on the most common UGRA procedures for the upper and lower extremity. At the beginning of the workshop and at the end of the workshop residents completed pre-test and pre-confidence surveys, as well as post-test and post-confidence surveys, respectively to assess the impact of the workshop. Results 39 residents (100% of the possible residents) participated in the workshop in 2019. Residents’ confidence in identifying relevant anatomy for the most common UGRA procedures significantly increased in 13 of the 14 measurements. Residents’ knowledge gain was also statistically significant from the pre-test to post-test (20.13 ± 3.61 and 26.13 ± 2.34; p < .0001). The residents found the course overall to be very useful (4.90 ± 0.38) and in particular the cadaveric component was highly rated (4.74 ± 0.55). Conclusions In this study, we developed a workshop guided by the embodied cognition framework to aid in shortening the overall learning curve of UGRA for anesthesiology residents. Based on our results this workshop should be replicated by institutions that are hoping to decrease the learning curve associated with UGRA and increase residents’ confidence in identifying the relevant anatomy in UGRA nerve blocks

Imaging the seismic velocity structure of the crust and upper mantle in the northern East African Rift using Rayleigh wave tomography

Understanding the dynamics and evolution of continental rifting is broadly important for our understanding of plate tectonics. The northern East African Rift offers an excellent opportunity to study these processes at an active rift that was initiated by a large magmatic event. Multiple seismic models have been produced to understand the evolution of magmatism which image punctuated slow velocity zones in the asthenosphere. However, the depth extent of the slow velocity bodies has been less well constrained leading to much debate regarding the primary controls on melt generation. Variations between methods, resolution, and scale of the seismic models make direct quantitative comparisons challenging. The lack of instrumentation off-rift further limits our understanding of the spatial extent of tectonic and magmatic processes, which is crucial to understanding magmatic continental rifting. In this paper, we jointly invert Rayleigh wave dispersion curves from ambient noise and teleseisms to obtain absolute shear velocity maps at 10–150 km depth. This includes data from a new seismic network located on the Ethiopian Plateau and enhanced resolution at Moho and upper mantle depths from the joint inversion. At crustal depths, velocities are slowest beneath the Main Ethiopian Rift and the off-rift Ethiopian Plateau (&lt;3.00-3.75 ±0.04 km/s, 10–40 km depth) and ongoing magmatic emplacement is required. At 60–80 km depth off-rift, we observe a fast velocity lid (&gt;0.1 km/s faster than surroundings), in agreement with previous estimates of lithospheric thickness from receiver functions. The fast lid is not observed within the Main Ethiopian Rift or central Afar which instead are underlain by asthenospheric slow velocity anomalies (&lt;4.05 ±0.04 km/s at 60–120 km depth). This suggests melt is infiltrating the lithosphere within the rift. Furthermore, punctuated asthenospheric slow velocity anomalies (∼110×80 km wide) exist in areas that have not undergone significant crustal and plate thinning, potentially indicating melt infiltration may start prior to significant plate deformation. Finally, the punctuated asthenospheric slow velocity zones are not located directly beneath melt-rich crustal regions including those off-rift, suggesting melt migration processes are dynamic and/or may occur laterally