Low internal magnetic fields in anisotropic superconductors

This thesis is a theoretical, numerical study of the magnetic fields which exist in the anisotropic, high temperature superconductors like YBa\sb2Cu\sb3O\sb{7-\delta}, or YBCO for short, using both the anisotropic London theory and simulations based on existing muon spin rotation techniques. The thesis first describes the muon spin rotation ($\mu$SR) techniques, and then gives a brief discussion of superconductivity with regard to the London theory of anisotropic, type II superconductors. Next, numerical results of the application of this theory to YBCO are presented. Three dimensional surface plots of the magnetic field components within the flux line lattice (FLL) are shown, as well as the corresponding contour plots of the fields. Field distributions are calculated from these surfaces, and the graphs are presented. These distributions correspond to the real part of the Fourier transform of the muon histogram, and a comparison between data taken on a polycrystalline sample and the theoretical prediction is made. In addition, variation of the field distributions with parameters such as penetration depth, angle of the average field, and the magnitude of the average field is discussed. The last part of the thesis is a theoretical study of the behavior of muons which have stopped within a superconductor. The muons are assumed to stop uniformly throughout the FLL area, and the precession of each about its local field is recorded as the projection of its polarization along each of three mutually perpendicular detectors. The depolarization of these signals as a function of time is an indication of the existence of transverse field components which exist within the FLL due solely to the anisotropy of the material. In order to further investigate these off axis fields, we have developed an extension of the usual $\mu$SR techniques, coupled with Fourier analysis, which yields new information. For example, with the proper analysis procedure, one may determine to good precision the direction of the average internal field B with respect to the applied field H\sb{a}. Other quantities, which we call moments of the field distribution, may also be determined

Developing Teachers’ Intentions of Incorporating Socioscientific Issues in Lesson Design

In an effort to increase students’ informed decisions and evidence-based argumentation and perspective taking in the STEM classroom, this case study explored the ways in which teachers’ thinking and intention of incorporating Socioscientific Issues (SSI) into their lesson plans change after participating in an experiential workshop. Recognizing the difficulties inherent in SSI implementation, the day-long teacher development implemented a multi-layered approach which included declarative and procedural knowledge construction, namely understanding SSI components, SSI lesson planning, and learning STEM topics through the SSI framework. Pre-post conference questionnaires and lesson analysis showed that teachers were adept in developing SSI-focused lessons. In addition, the majority of teachers who had not previously taught an SSI lesson, did intend to develop SSI lessons in the future which included scientific phenomena or system dynamics. Implications for STEM teacher development are discussed

An Open-Label Pilot Study Testing the Feasibility of Assessing Total Symptom Burden in Trials of Cannabinoid Medications in Palliative Care.

Background: There is considerable interest in the use of cannabinoids for symptom control in palliative care, but there is little high-quality evidence to guide clinical practice. Objectives: Assess the feasibility of using global symptom burden measures to assess response to medicinal cannabis, to determine median tolerated doses of cannabidiol (CBD) and tetrahydrocannabinol (THC), and to document adverse events (AEs). Design: Prospective two-arm open-label pilot trial of escalating doses of CBD and THC oil. Setting/Subjects: Participants had advanced cancer and cancer-related symptoms in a palliative and supportive care service in an Australian cancer center. Measurements: The main outcome measures were the number of participants screened and randomized over the time frame, the number of participants completing days 14 and 28 and providing total symptom distress scores (TSDSs) (measured using the Edmonton Symptom Assessment Scale), and the change from baseline of the TSDS at day 14. Results: Of the 21 participants enrolled (CBD, n = 16; THC, n = 5), 18 (86%) completed the primary outcome measure at day 14 and 8 completed at day 28. The median maximum tolerated doses were CBD, 300 mg/day (range 100-600 mg); THC, 10 mg/day (range 5-30 mg). Nine of 21 patients (43%) met the definition of response (≥6 point reduction in TSDS). Drowsiness was the most common AE. Conclusions: Trials of medicinal cannabis in advanced cancer patients undergoing palliative care are feasible. The doses of THC and CBD used in this study were generally well tolerated and the outcome measure of total symptom distress is promising as a measure of overall symptom benefit. Trial registration: ACTRN12618001205224

Enhancing Engineering Identity Among Boys of Color

Black and Brown men continue to be underrepresented in engineering. One explanation for the dearth of Black and Latino men in engineering is that engineering (and STEM) identity often is not inclusive of People of Color. As a result, Black and Brown boys may be less likely to become interested in STEM subjects. The purpose of this study, then, was to investigate how the components of one afterschool engineering program tap into engineering identity formation among fourth- and fifth-grade Black and Brown boys. Leveraging research on the STEM and engineering identity, we argue that the program and its key components play both constructive and protective roles. This study comprises a case study of an afterschool engineering program completing its third year of implementation at three elementary schools. Over four semesters, we recruited approximately 60 students from the three schools and 21 mentors to participate in the study. We collected data via one-on-one interviews, focus groups, and observations. We found that engineering design activities are constructive, offering the young Black and Brown boys opportunities to engage with the work of engineers. The mentors played constructive roles by recognizing the students’ engineering work. The mentors also played a protective role, buffering against identity interference and cultivating a sense of belonging. We conclude by discussing how the findings contribute to existing research on engineering identity and making recommendations for practice