The three-dimensional structure of Kilauea Volcano, Hawaii, from travel time tomography

A linear, travel time tomography study of the most active shield volcano of the world, Kilauea Volcano, Hawaii, was undertaken to determine the lateral heterogeneities produced by its intricate magmatic and tectonic environment. Kilauea provides an ideal setting to do tomography because of its dense seismograph array and many local earthquakes that allow excellent ray coverage of complex subsurface features. Local P wave data from ∼ 12,295 events were inverted using a one-dimensional layered velocity model. Inversions were done for two cell sizes (5×5×5 km and 1×1×1 km) to resolve structural regions on different length scales. This study provided a view of the average velocity variations relative to a one-dimensional velocity model. Analysis and interpretation of the tomographic images allowed us to infer the following model. The main shallow magma reservoir is delineated by a slow velocity region southeast of the summit from 0 to 2 km depth. There is a distinct high velocity region centered northwest of the summit from 0 to 2 km depth that represents a cap of dense, intrusive dikes surrounding the magma chamber. We suggest that the shallow reservoir is a narrow, compartmentalized region of sills and dikes, centered just south-southeast of Halemaumau caldera. Below the main reservoir, the summit is imaged as a slightly fast region from 5 to 10 km in the coarse model indicating that the main conduit is structurally defined by an intrusive dike complex until about 10 km. The rift zones of Kilauea are imaged as major, high velocity entities, widening to the south with depth until 6 km. These fast anomalies are related to the sheeted dike complexes along the rifts. On a finer scale, slow anomalies suggest the presence of magma pockets centered at 0–2 km depth beneath Mauna Ulu, Makaopuhi and Puu Oo, along the east rift zone (ERZ). Two significant high velocity regions along the lower ERZ near Kalalua and Kaliu are inferred to represent intrusive barriers to magma injection along the shallow (0–4 km) ERZ conduit. The southwest rift zone may have an intrusive barrier related to a high velocity region just southwest of Mauna Iki. The Hilina and Kaoiki fault zones are imaged as slow features at shallow depths (< 5 km) related to the open fractures and scarps along the normal faults. The Koae fault system is imaged as a slightly fast shallow structure (< 6 km) possibly related to intrusive diking from the adjacent rift zones that fill and may even induce the extensional structures associated with this complex fault zone. Continued inversions with the immense amount of seismic data collected for Hawaiian events will allow the detailed development of a three-dimensional structural model for Kilauea. Such a model will be extremely useful to seismologists and petrologists alike for understanding the tectonic growth and magmatic evolution of this dynamic shield volcano

Absence of reflection as a function of the coupling constant

We consider solutions of the one-dimensional equation $-u'' +(Q+ \lambda V) u = 0$ where $Q: \mathbb{R} \to \mathbb{R}$ is locally integrable, $V : \mathbb{R} \to \mathbb{R}$ is integrable with supp$(V) \subset [0,1]$, and $\lambda \in \mathbb{R}$ is a coupling constant. Given a family of solutions $\{u_{\lambda} \}_{\lambda \in \mathbb{R}}$ which satisfy $u_{\lambda}(x) = u_0(x)$ for all $x<0$, we prove that the zeros of $b(\lambda) := W[u_0, u_{\lambda}]$, the Wronskian of $u_0$ and $u_{\lambda}$, form a discrete set unless $V \equiv 0$. Setting $Q(x) := -E$, one sees that a particular consequence of this result may be stated as: if the fixed energy scattering experiment $-u'' + \lambda V u = Eu$ gives rise to a reflection coefficient which vanishes on a set of couplings with an accumulation point, then $V \equiv 0$.Comment: To appear in Journal of Mathematical Physic

What Large-Scale, Survey Research Tells Us About Teacher Effects on Student Achievement: Insights From the Prospectus Study of Elementary Schools

This report is about conceptual and methodological issues that arise when educational researchers use data from large-scale, survey research studies to investigate teacher effects on student achievement. In the report, we illustrate these issues by reporting on a series of analyses we conducted using data from Prospects: The Congressionally Mandated Study of Educational Opportunity. This large-scale, survey research effort gathered a rich store of data on instructional processes and student achievement in a large sample of U.S. elementary schools during the early 1990s as part of the federal government\u27s evaluation of the Title I program. We use data from Prospects to estimate the overall size of teacher effects on student achievement and to test some specific hypotheses about why such effects occur. On the basis of these analyses, we draw some substantive conclusions about the magnitude and sources of teacher effects on student achievement and suggest some ways that survey-based research on teaching can be improved

Formal and spatial variations in a traditional walled city : Zaria, Nigeria

Thesis (M.Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1981.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography: p. 101-102.by Robert Keith Rowan.M.Arch

Technical Communication As Teaching: A Grounded Theory Study Of Cognitive Empathy And Audience Engagement Among Computer Science Majors In A Technical Communication Classroom

This dissertation is a grounded theory study of empathy, ethical awareness, and audience engagement activities in students in a technical writing service course. The course was designed around an empathy-oriented approach to teaching technical writing and writing research. The students are primarily computer science majors, and the teaching methods include a genre and writing research approach as well as the use of an extended metaphor of technical communication as a form of teaching. Findings indicate that students respond to the metaphor by drawing upon positive and empathetically-informed models of teachers and teaching to guide how they would work with and write for their own audiences; however, students show moderate resistance to adopting the identity of writer and strong resistance to adopting the identity of researcher. I argue that teachers tend to undervalue and underutilize the two strongest areas of experience and observationally-derived identity knowledge that students possess (the teacher and the student) while asking them to take on roles or identities such as writer or researcher that we have only described to them but not shown them through direct example. We also ask them to perform activities which we may not have not fully contextualized, or which may not be fully contextualizable given the location of that context outside of the students\u27 areas of experience. The result is an imbalance between identity, performance, and expectations. I consider some pedagogical modifications which more closely follow the contours of student experience and needs, and which may result in improved outcomes in both willingness and ability to engage with diverse audiences and communities. I examine potential implications for technical communication and STEM fields more generally

Global History Hackathon Playbook Version 1.1: Practical Guidance for Hosting a Hackathon for the Arts, Humanities, and Social Sciences

What happens when you take a format more commonly associated with computer science and technology—the hackathon—and apply it to historical thinking and research design in global history using unique archival and museum collections? This playbook shares what we learned from our project, Global History Hackathons: Doing Global History through Local Archives and Museum Collections (January-June 2019). An inspiring crowd of students and staff took part in Global History Hackathons. You can read about some of their creative and intriguing ideas through Twitter (@HistGlobal #GlobalHistHack19) and our event blogs, which are listed in the Bibliography. We hope this playbook will encourage you to plan and carry out your own hackathons: not just for global history, but also across the arts, humanities, and social sciences