Master of Science

thesisThe indium-gallium-nitride on gallium-nitride (InGaN/GaN) materials system is a promising candidate for providing a high intensity, high efficiency solution to the yet unsolved problem of solid state lighting in the range of 550 to 590 nm, a.k.a the Green Gap. The bandgap of InGaN/GaN spans the visual spectrum, making it tunable for emission at any wavelength. The lattice constant mismatch and resulting strain at the heterojunction induces a miscibility gap that enables spontaneous self-assembly of indium-rich nm-scale islands during Stranski-Krastanov growth of the InGaN active layer of the Light Emitting Diode (LED). These islands serve as quantum discs, confining excitons, and increasing internal quantum efficiency. InGaN/GaN/Al2O3 samples from Cao Group Inc. were interrupted after the InGaN growth step of the Organometallic Vapor-Phase Epitaxy (OMVPE) process and analyzed using Atomic Force Microscopy (AFM), High Resolution Scanning Electron Microscopy (HRSEM), Transmission Electron Microscopy (TEM), Raman, and Photoluminescence (PL) spectroscopies. Results show inhomogeneities in light emission and structure as well as conductivity.Coherence, strain, and the presence of indium were all confirmed through TEM and Energy Dispersive X-ray spectroscopy (EDX). Islands (3-10nm in height) and pits (1-4nm deep) cluster in patches with a marbled pattern. Islands tend to be found most predominantly at the edges or the bottom of pits, suggesting indium-rich island growth is preferred along the edges of structures of high surface area, where strain from lattice mismatch is most compensated by surface area. Despite coherence, Fast Fourier Transform (FFT) reciprocal space patterns show lattice spacing and possibly the crystal structure type itself differ between island and subisland areas. The difference between island emission energy and the energy required to excite carriers is greater than expected. PL peak energy and Raman shift frequency test results were used to estimate island indium composition. Polarization of emission was observed, though was unexpected due to the InGaN having been grown on c-plane GaN which should result in isotropic biaxial strain and a valence band configuration that does not lend to bifurcating probabilities of polarization. Near-Field PL testing was performed, also with unexpected results

Disclosure Of Nonaudit Services Fees: Perceptions Of Investors And Accounting Professionals

This study examines investors’ and accounting professionals’ perceptions related to the necessity and form of disclosure of nonaudit service (NAS) fees pursuant to the Security and Exchange Commission’s Final Rule on auditor independence. A between-subjects design was used to examine participants’ opinions as to the need for disclosure of the performance of NAS and the particular form of disclosure that was preferred. The design incorporated four types of NAS (actuarial services, internal audit outsourcing, legal services, and software training), two levels of materiality (40 percent and 3 percent), and three categories of participants (non-Big 5 CPA firm professionals, Big 5 CPA firm professionals, and investors). A larger percentage of investors favored disclosure of NAS fees than either non-Big 5 CPA firm professionals or Big 5 CPA firm professionals. In addition, of those who favored disclosure, investors favored disclosure of the amount of NAS along with the total audit fees, regardless of the amount, while non-Big 5 CPA firm professionals and Big 5 CPA firm professionals both favored disclosure of the amount of NAS alone and only if those services exceeded a specified threshold. The investor results lend support to the SEC’s revised auditor independence rules

A Content Analysis of Women’s Experiences of Workplace Bullying Since 2000

A content analysis was conducted to explore women’s experiences of bullying in the workplace, which revealed characteristics, impacts, and strategies of women being bullied at work

“In Touch With my Creative Side”: Supporting Self-Care Among Nursing Students Through Arts-Based Pedagogy.

Nursing students experience academic, practice-related, and personal stressors, all of which can affect their learning, fitness-to-practice, and overall well-being. One way for educators to support students’ well-being is to foster their capacity for, and enactment of, self-care. We used an arts-based assignment that required students to reflect on the stressors they encountered and engage in strategies to relieve their stress and provide self-care. The assignment also provided students with a creative outlet for managing the stressors they faced during their program of study. We designed a web-based survey comprised of Likert scales and three open-ended questions to explore students’ perspectives on the assignment. These open-ended qualitative data and optional submissions of creative assignments are the focus of this paper. The use of an arts-based assignment added positively to the experience for many students; for others, evaluation of their creative work detracted from the experience. Résumé Les étudiantes en sciences infirmières vivent du stress dans le contexte de leurs études universitaires, des pratiques en milieux de soins et de leur vie personnelle, qui peut affecter leur apprentissage, leur aptitude à la pratique et leur bien-être général. Une façon pour les professeures et enseignantes de soutenir le bien-être des étudiantes est de favoriser leur capacité à prendre soin d’elles-mêmes et à la mettre en pratique. Nous avons utilisé un travail faisant appel aux arts qui demandait aux étudiantes de réfléchir aux facteurs de stress auxquels elles étaient confrontées et de s’engager dans des stratégies pour diminuer ce stress et prendre soin d’elles-mêmes. L’exercice s’est également avéré un exutoire créatif pour gérer le stress auquel elles ont été confrontées au cours de leur programme d’études. Nous avons conçu un sondage en ligne composé de questions à répondre à l’aide d’une échelle de Likert et de trois questions ouvertes pour explorer les points de vue des étudiantes sur ce travail. Les données qualitatives en réponse à ces questions ouvertes et les travaux créatifs soumis de manière facultative sont au centre de cet article. L’utilisation d’un travail basé sur les arts a été une expérience positive pour de nombreuses étudiantes; pour d’autres, l’évaluation de leur travail créatif a nui à l’expérience

Individual pulmonary vein size and survival in infants with totally anomalous pulmonary venous connection

AbstractObjectives. We investigated whether mortality in totally anomalous pulmonary venous connection could be predicted from preoperative individual pulmonary vein size.Background. Some infants with this anomaly die with or without surgical repair because of stenosis of individual pulmonary veins.Methods. Individual pulmonary vein, vertical vein and pulmonary venous confluence diameters were retrospectively measured from preoperative echocardiograms in 32 infants with totally anomalous pulmonary venous connection presenting to Children's Hospital, Boston over a 1/2-year period. Data on body surface area, other cardiac anomalies, presence of initial pulmonary venous obstruction and early surgery and outcome were also recorded.Results. Of 32 patients, 6 (18.8%) died before hospital discharge, and 8 (25.0%) died subsequently. Six (75.0%) of the eight patients who died late had individual pulmonary vein stenosis at sites remote from the surgical anastomosis to the left atrium. The remaining 18 patients (56.3%) are alive at a mean follow-up period of 9.7 months. A Cox proportional hazard model revealed that small sum of individual pulmonary vein diameters (p = 0.0004), small confluence size (p = 0.02) and presence of heterotaxy syndrome (p = 0.008) were each significant univariate predictors of survival. Multivariate analysis showed that small pulmonary vein sum was a strong predictor of survival (p = 0.008), independent of the presence of heterotaxy syndrome. An analysis stratified by the presence of heterotaxy syndrome showed that the predictive effect of small pulmonary vein sum on survival was strongest in patients without heterotaxy syndrome.Conclusions. These data show that individual pulmonary vein size at diagnosis is a strong, independent predictor of survival in patients with totally anomalous pulmonary venous connection. In patients with this anomaly and small individual pulmonary veins, the anomaly may not be correctable by surgical creation of an anastomosis between the pulmonary venous confluence and the left atrium

Multipolar endocardial mapping of the right atrium during cardiac catheterization: description of a new technique

AbstractObjectives. Using a new mapping system that allows the simultaneous acquisition of date from 25 right atrial bipolar electrodes during cardiac catheterization, we mapped normal sinus rhythm and atrial reentrant tachycardia in 24 sheep (20 to 49 kg) and 7 pigs (25 to 35 kg).Background. Rapid, high resolution mapping during cardiac catheterization may shorten ablation procedures and permit ablation of otherwise refractory arrhythmias.Methods. A flexible, elliptic, basket-shaped recording catheter has five spokes, each with 10 electrodes arranged as 5 bipolar pairs. Catheter shape, electrode spacing and introduction technique were modified in response to the results of experiments in the first 23 animals. In the most recent eight animals, retraction of a string attached to the distal tip distended the basket, providing safe tissue contact. Filtered (30 to 250 Hz) bipolar recordings from all 25 electrode pairs, as well as a surface electrocardiogram, were recorded and digitized at 1,000 Hz using custom software. An activation map was digitally constructed and superimposed on anteroposterior and lateral fluoroscopic catheter images. Bipolar recordings were made in normal sinus rhythm (31 animals), with adequate signals recorded from >95% of electrode pairs. Rapid burst pacing and intentional right atrial air embolus (30 to 50 ml) induced sustained atrial reentrant tachycardia in five animais, which was also adequately recorded.Results. Catheter positioning and complete atrial mapping required <10 min after venous access in the most recent eight experiments. The catheter was left in position for up to 4 h. Postmortem evaluation revealed minor superficial abrasion of the venae cavae or right atrial endocardium in six animals and moderate abrasion in two. No other damage was observed.Conclusions. This new system may ultimately assist in mapping simple or complex atrial arrhythmias during cardiac eatheterization

Ventricular Tachycardia Detection Using Bipolar Electrogram Analysis is Site Specific

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75656/1/j.1540-8159.1992.tb03039.x.pd

Evolution or revolution: Where next for impact assessment?

Impact assessment (IA) has become one of the most prevalent environmental policy instruments today. Its introduction under the National Environmental Policy Act (US) in 1969 was revolutionary. Perhaps it is not surprising, then, that such a widely used tool has received its share of criticism, including that it fails to meet some of its fundamental goals. Over the last fifty years, IA has broadened in scope and application and embraced new techniques. It has followed evolved, but has not changed fundamentally. We believe that IA must continue to change to meet the societal and environmental challenges of the 21st century. But will it be enough for IA to progress through incremental change (evolution), or is a complete overhaul of impact assessment (revolution) needed? We provide some ideas as to what ‘evolution’ and ‘revolution’ may look like, but rather then offering a definitive way forward now, we invite stakeholders to present their thoughts and suggestions at the IAIA19 Annual Conference in Brisbane, which carries the same theme as the title of this article