Using phonon imaging to probe anisotropy in the superconducting energy gap of lead

Short, Jonathan David University of Illinois at Urbana-Champaign 2001 해외박사(DDOD)

A new application of phonon-imaging techniques is demonstrated to probe the superconducting state of Pb. I have observed highly selective attenuation of phonons with wavevectors in {111} planes, inspiring an investigation of the superconducting properties of Pb. This thesis will consist of several parts that investigate and develop a possible explanation of the attenuation of {111} phonons. Most probes of the superconducting state used for Pb have been either insensitive to directions of reduced gap or limited to probing the gap along a few symmetry directions. In this work, I will attempt to use the scanning nature of phonon-imaging experiments to overcome this limitation and determine if an anisotropic gap explains the phonon data in Pb. A crucial observation is that the anisotropic attenuation increases with increasing sample temperature. This temperature dependence is consistent with the earlier specific-heat and ultrasound-attenuation experiments that suggest regions of reduced gap for Pb. However, a significant difference from these earlier experiments is that the directional dependence of phonon attenuation in these experiments will be used to gain insight into the locations of reduced gap. I will show that the shape of the Fermi surface has profound consequences on phonon scattering and may have important implications on a successful theory of a highly anisotropic energy gap in Pb. The only theory, so far, to explain the anomalous superconducting properties of Pb postulates the presence of a spin-density-wave (SDW) ground state. I will show that, at present, most of the experimental data can be explained by assuming that the ground state of Pb is described by a family of twelve [211] SDWs. I will show that the short laser pulses used to generate phonons create a localized phonon source with a lifetime up to 50 times longer than the laser duration. In investigating the temporal characteristics of the phonon source in Pb, an unexplained phonon pulse arriving after the ballistic propagation time is discussed. A new method for low-pass filtering phonons arriving at the detector is demonstrated in the current attempts to explain this anomalous pulse. (Abstract shortened by UMI.).

The life cycle theory, uncertainty and saving behavior of the elderly

Short, Kathleen Strunck Edward Elgar 1984 국내박사

Information-seeking patterns and resource use by Baptist leaders in three Central American countries

Allen, Jean Short University Microfilms International 1987 국내박사

Development of an in situ and mobile mass spectrometer for environmental and medical analysis

Short, Luke Chandler University of California, Irvine 2004 해외박사(DDOD)

Applications of analytical chemistry and novel trace-gas detection techniques permit new insights into environmental chemistry and human biology. My dissertation involves the theoretical, methodological and experimental development of analytical techniques to measure several such significant compounds. The focus of the doctoral work was the construction of a portable Time-of-Flight Mass Spectrometer (TOF-MS) using Resonance Enhanced Multi-Photon Ionization (REMPI) for compound selectivity. Two general types of light sources are used for ionization: excimer lasers (KrF*, XeCl* and ArF*) and Nd:YAG lasers. The two tuneable light sources used are an excimer-umped dye laser and an Optical Parametric Oscillator (OPO) - Nd:YAG laser system made at our laboratory. Several applications of gas analysis are presented to illustrate the use of this instrument and technique in both the fields of environmental research and medicine. Example compounds are: formaldehyde (HCHO), nitric oxide (NO), nitrogen dioxide (NO2) and aromatic hydrocarbons, such as benzene (C6H6). Presented here are the REMPI-MS techniques designed by our group for simultaneous NO and NO quantification, as well as a new REMPI-MS technique for the detection of HCHO and longer normal-chain aldehydes. The applicability of a commercially-available chemical HCHO analyzer to quantify HCHO in urine was also studied. A comparison of contemporary HCHO analyzers was performed in cooperation with other research groups to verify the agreement among these atmospheric techniques. This study indicates that atmospheric measurements of HCHO using the chemical technique are accurate.

21st century skills development: Learning in digital communities: Technology and collaboration

Short, Barbara J University of Oregon 2012 해외박사(DDOD)

This study examines some aspects of student performance in the 21 st century skills of Information and Communication (ICT) Literacy and collaboration. In this project, extant data from the Assessment and Teaching for 21st Century Skills project (ATC21S) will be examined. ATC21S is a collaborative effort among educational agencies in six countries, universities, educational research groups, high tech innovators and the multinational corporations Cisco, Intel and Microsoft. ATC21S demonstration tasks explore the use of digital literacy and collaborative problem solving constructs in educational assessment. My research investigates evidence from cognitive laboratories and pilots administered in one of the ATC21S demonstration scenarios, a collaborative mathematics/science task called "Global Collaboration Contest: Arctic Trek." Using both quantitative and qualitative methods, I analyze student work samples. Specifically, I (i) develop a rubric as a measurement tool to evaluate the student assessment artifact "Arctic Trek Notebook" for (a) generalized patterns and (b) trends that may indicate skill development in collaborative learning in a digital environment and (ii) conduct descriptive studies among the variables of student age and student notebook characteristics. Results are intended to inform instructional leaders on estimates of student ability in virtual collaboration and to make suggestions for instructional design and professional development for online collaborative learning assessment tasks in K-12 education.

The story of David's rise as political apology: A reconsideration

Short, John Randall Harvard University 2006 해외박사(DDOD)

Modern biblical scholars have increasingly characterized the story of David's rise to kingship as stemming from an originally independent and unified source that was composed in the Jerusalemite royal court for the purpose of legitimizing David's usurpation of Saul's throne. Scholars have made this case for interpreting "the History of David's Rise" (HDR) as royal propaganda through comparisons of it with other ancient Near Eastern royal texts, particularly the Hittite "Apology of H ⌣ attusili." Furthermore, they have detected in HDR a rhetorical posture that addresses several underlying or implied charges of illegitimacy and lese-majeste against the historical David. Inasmuch as these scholars believe that the original HDR remained essentially unchanged throughout its literary history, they interpret the biblical account in terms of the apologetic needs of King David. In this dissertation, I contend that these recent characterizations of HDR as "the Apology of David" fail to make adequate sense of many literary and theological features and particularities of the biblical account. My contention is not that the story of David's rise to kingship was never used for any sort of "apologetic" purposes, but that the biblical account---at any point in its literary history---cannot be so easily assimilated to the genre of ancient Near Eastern "royal apology" and basically reduced to "political self-justification" or "secular, political ideology," as some scholars have characterized it. Ultimately, this approach leads to unsatisfactory results even for versions of HDR that have been reconstructed according to these historical and literary assumptions. Reading through the lens of political apology is all the more inadequate, then, vis-`a-vis the present biblical account. Within the biblical context of 1 and 2 Samuel, I argue, YHWH's initial election of David is not simply one of several legitimizing themes or motifs in "David's story" Divine election, rather, is the sole ground upon which David's kingship rises and stands. Subsequent to YHWH's initial election of David as His king, therefore, the rest of the narrative presents YHWH's confirmation of him as His choice for king through the emergence of David as the "beloved son" of Jesse, Saul, all Israel, and YHWH Himself.

Gender disparities in tenure-track faculty job satisfaction

Short, Heidi Neiman Harvard University 2006 해외박사(DDOD)

Women have made significant progress in earning graduate degrees and entering the professorate, but they have not had the same success as men in developing and sustaining faculty careers, as illustrated by the following comparisons: (1) In 2001, 48 percent of full-time female faculty and 65 percent of full-time male faculty had tenure at four- and two-year institutions (Lindholm, Astin, Sax, and Korn, 2002); (2) In 2001, 21 percent of female faculty and 43 percent of male faculty were full professors (Lindholm et al., 2002); (3) Women comprise only 31 percent of full-time faculty, an increase of 5 percentage points in the last 75 years (Cooper and Stevens, 2002). Research suggests that slower progress by women through the academic ranks reflects the differential treatment men and women receive in their institutions and departments (Aguirre, 2000; Jackson, 2001; Tierney and Bensimon, 1996). This disparity produces at least two outcomes for female academics. First, they are less satisfied with their jobs than male faculty (Boice, 1993; Hagedorn, 1996; Tack and Patitu, 1992). Second, female tenure-track faculty are more apt than men to leave academe before a tenure decision (Tack and Patitu, 1992; Tierney and Rhoads, 1994). This dissertation examines the job satisfaction of tenure-track faculty and endeavors to understand how and why it differs by gender at one institution, but not at another. Two overarching questions guide this research: What factors do tenure-track faculty at two institutions cite as contributing to their job satisfaction? How do tenure-track faculty at two institutions describe the relationship between their expectations, values, and needs and their job satisfaction? Data was collected through qualitative interviews with 31 tenure-track faculty at two research sites, one at which there were gender disparities in the overall job satisfaction of tenure-track faculty, and one at which there were not. Data analysis was informed by two theories of job satisfaction: content theory and process theory. Content theory strives to identify factors that influence job satisfaction and study the degree to which these factors predict job satisfaction, while process theory underscores the significance of an individual's expectations, needs, and values, and whether they are fulfilled in the workplace. Study findings suggest that there are no gender differences in the factors contributing to tenure-track job satisfaction. However, there are gender differences in how these factors conform to individuals' values, interests, needs, and expectations. Specifically, women tend to value teaching more than men, while men tend to value autonomy more than women. In addition women were more likely than men to find that the tenure criteria did not allow them to do what they enjoyed most, and this was not what they expected when they started their junior faculty jobs. These gender differences were more pronounced at the institution where gender differentials in overall job satisfaction were evident.

A Marathon at a Sprinter's Pace: Improving Retention in a Turnaround Environment Through Manager Development

Short, Kathryn Harvard University ProQuest Dissertations & Theses 2018 해외박사(DDOD)

Topics in hierarchical spatial models

Short, Margaret B University of Minnesota 2003 해외박사(DDOD)

Epidemiological data often and environmental data usually include a spatial component; such data may contain a temporal component as well. In this thesis, we discuss techniques, broadly falling into two categories, for analyzing such data. Both are hierarchical Bayesian in nature and use Markov chain Monte Carlo methods to estimate parameters of interest. First, we demonstrate a method for combining various epidemiological data given in the form of aggregate figures for a collection of adjoining geographic regions. We illustrate with a data set consisting of mortality, incidence, staging and screening rates for breast cancer across Minnesota counties during 1993--1998. The objective is to rate the counties in a manner that reflects the effectiveness of their cancer control efforts. The various cancer aspect/rate combinations are modelled with Gaussian distributions, with CAR prior distributions modeling spatial correlations between the underlying parameters. Convex combinations of the cancer aspect variables are computed to produce final summary maps. The second part of the thesis describes and extends the concept of spatial cumulative distribution functions (SCDFs) in a Bayesian context. We predict SCDFs via Monte Carlo integration, then generalize to a "covariate-adjusted" SCDF. We present a method for SCDF prediction that handles spatially misaligned data, e.g. point level pollutant and block level covariate. We further generalize to bivariate settings in which two point-level processes are modeled jointly. We explore these concepts in two settings, one in which race (measured at zip code level) is used as a weighting function for ozone, using data from the Atlanta area; and another involving a bivariate process, in which one air pollutant is used to weight another in a California data set. We extend the notion of SCDFs to spatio-temporal settings, hoping to improve precision by incorporating repeated measurements. We develop and implement computational techniques to handle the difficulties introduced by the large data sets (large due to the added temporal component), the inclusion of a measurement error term, and the handling of missing data. We explore model selection via the Deviance Information Criteria and illustrate the concepts using supersets of the Atlanta and California data sets.

Flow-informed strategies for trajectory design and analysis

Short, Cody R Purdue University 2016 해외박사(DDOD)

This research is focused on augmenting and extending classical dynamical methods by introducing flow-based methodologies into astrodynamical design and analysis. These flow-informed tools apply in extended phase spaces and through all levels of model fidelity. Thus, they apply where classical approaches begin to lose relevance and persist beyond this point. Such methodologies are common in various fields, and have recently began to receive significant attention within the astrodynamical community for design and analysis efforts. Trajectory design spaces are frequently vast and complex. In some cases, there are an infinite number of possibilities for particular solutions. Even after eliminating the infeasible choices, many options may still remain. Some strategies for selecting a candidate solution to incorporate into an astrodynamical design focus on simplification or reduction of the space. This approach has proven useful for many mission scenarios. However, such an approach, by its very nature, represents a potential loss of alternative solutions and may require reverting to the initial phases of the process when a new option is required. Approaches that reduce the distance from the initial design effort to its end result represent a potential improvement to the design process. Methods incorporating flow behaviors represent one such option where the understanding of the space is expanded and additional solutions are revealed.