Musical commonplace book : manuscript, [approximately 1790-approximately 1810]

Contains songs, partly from English operas, and instrumental music.

Experimental analysis of novel telecom source materials and devices

Incumbent telecommunication lasers emitting at 1.5 µm are fabricated on InP substrates and consist of multiple strained quantum well layers of the ternary alloy InGaAs, with barriers of InGaAsP or InGaAlAs. These lasers have been seen to exhibit very strong temperature dependence of the threshold current. This strong temperature dependence leads to a situation where external cooling equipment is required to stabilise the optical output power of these lasers. This results in a significant increase in the energy bill associated with telecommunications, as well as a large increase in equipment budgets. If the exponential growth trend of end user bandwidth demand associated with the internet continues, these inefficient lasers could see the telecommunications industry become the dominant consumer of world energy. For this reason there is strong interest in developing new, much more efficient telecommunication lasers. One avenue being investigated is the development of quantum dot lasers on InP. The confinement experienced in these low dimensional structures leads to a strong perturbation of the density of states at the band edge, and has been predicted to result in reduced temperature dependence of the threshold current in these devices. The growth of these structures is difficult due to the large lattice mismatch between InP and InAs; however, recently quantum dots elongated in one dimension, known as quantum dashes, have been demonstrated. Chapter 4 of this thesis provides an experimental analysis of one of these quantum dash lasers emitting at 1.5 µm along with a numerical investigation of threshold dynamics present in this device. Another avenue being explored to increase the efficiency of telecommunications lasers is bandstructure engineering of GaAs-based materials to emit at 1.5 µm. The cause of the strong temperature sensitivity in InP-based quantum well structures has been shown to be CHSH Auger recombination. Calculations have shown and experiments have verified that the addition of bismuth to GaAs strongly reduces the bandgap and increases the spin orbit splitting energy of the alloy GaAs1−xBix. This leads to a bandstructure condition at x = 10 % where not only is 1.5 µm emission achieved on GaAs-based material, but also the bandstructure of the material can naturally suppress the costly CHSH Auger recombination which plagues InP-based quantum-well-based material. It has been predicted that telecommunications lasers based on this material system should operate in the absence of external cooling equipment and offer electrical and optical benefits over the incumbent lasers. Chapters 5, 6, and 7 provide a first analysis of several aspects of this material system relevant to the development of high bismuth content telecommunication lasers.

The Career Development of Black Female Chief Nurse Executives

This qualitative study was designed to explore the career development of Black female chief nurse executives. Although a small proportion of Black female nurses have achieved positions at the nurse executive level, there remains a paucity of Black female nurse executives in this crucial position which raised the question of what factors contributed to this lack of advancement, but, more important, what factors have contributed to the success of the few who have achieved such level of success in healthcare organizations. The purpose of the study was to explore the career paths of Black female chief nurse executives with a view of understanding the factors which both facilitate and hinder the career development of these leaders in healthcare organizations. The guiding research question was, How do Black female nurse executives in this sample describe their career development? The participants in this study were Black female chief nurse executives located throughout the United States who, for the most part, were raised in segregation with a strong family foundation. To collect data, semistructured telephone interviews were conducted with 10 Black female chief nurse executives throughout the United States. The transcripts from the interviews were transcribed, coded, and analyzed. Using Super’s (1990, 1996), and Gottfredson’s (1981, 1996, 2002, 2005) career development theories and critical race theory (Crenshaw, 1995; Delgado, 2000) as the theoretical framework, the researcher found that the participants’ career development was influenced by (a) strong support system, (b) guidance, (c) influence of diversity, and (d) servant leadership. The findings help us understand the factors that have contributed to their successes as Black chief nurse executives. With the increasingly diverse population and concurrent increasing diversity in nursing and concerns about healthcare disparities, it is imperative that organizations attract, hire, develop, retain, and advance qualified Black nurses. Future studies addressing not only the career development of Black nurses but nurses in general might be informed by the present study’s findings. Recommendations are offered for nursing practice, education, and organizational policy.