The correlation of structure and electronic properties near the surface of transition metal oxides

The strong couplings between different degrees of freedom are believed to be responsible for novel and complex phenomena discovered in transition metal oxides (TMOs). The physical complexity is directly responsible for their tunability. Creating surfaces/interfaces add an additional ' man-made' twist, approaching the quantum phenomena of correlated materials. ^ The dissertation focused on the structural and electronic properties in proximity of surface of three prototype TMO compounds by using three complementary techniques: scanning tunneling microscopy, angle-resolved photoelectron spectroscopy and low energy electron diffraction, particularly emphasized the effects of broken symmetry and imperfections like defects on the coupling between charge and lattice degrees of freedom. ^ Ca1.5Sr0.5RuO4 is a layered ruthenate with square lattice and at the boundary of magnetic/orbital instability in Ca2-xSrxRuO4. That the substitution of Sr 2+ with Ca2+ causing RuO6 rotation narrows the dxy band width and changes the Fermi surface topology. Particularly, the γ(dxy) Fermi surface sheet exhibited hole-like in Ca1.5Sr0.5RuO4 in contrast to electron-like in Sr2RuO4, showing a strong charge-lattice coupling. ^ Na0.75CoO2 is a layered cobaltite with triangular lattice exhibiting extraordinary thermoelectric properties. The well-ordered CoO2-terminated surface with random Na distribution was observed. However, lattice constants of the surface are smaller than that in bulk. The surface density of states (DOS) showed strong temperature dependence. Especially, an unusual shift of the minimum DOS occurs below 230 K, clearly indicating a local charging effect on the surface. ^ Cd2Re2O7 is the first known pyrochlore oxide superconductor (Tc ∼ 1K). It exhibited an unusual second-order phase transition occurring at TS1 = 200 K and a controversial first-order transition at TS2 = 120 K. While bulk properties display large anomalies at TS1 but rather subtle and sample-dependent changes at TS2, the surface DOS near the EF show no change at T s1 but a substantial increase below TS2---a complete reversal as the signature for the transitions. We argued that crystal imperfections, mainly defects, which were considerably enhanced at the surface, resulted in the transition at TS2. ^

International education and the post-9/11 syndrome: A study of international educators in selected Miami-area colleges

This dissertation investigated the relationship between the September 11, 2001 terrorist attacks and the internationalization agenda of U.S. colleges and universities. The construct, post-9/11 syndrome, is used metaphorically to delineate the apparent state of panic and disequilibrium that followed the incident. Three research questions were investigated, with two universities in the Miami-area of South Florida, one private and the other public, as qualitative case studies. The questions are: (a) How are international student advisors and administrators across two types of institutions dealing with the post-9/11 syndrome? (b) What, if any, are the differences in international education after 9/11? (c) What have been the institutional priorities in relation to international education before and after 9/11? Data-gathering methods included interviews with international student/study abroad advisors and administrators with at least 8 years of experience in the function(s) at their institutions, document and institutional data analysis. The interviews were based on the three-part scheme developed by Schuman (1982): context of experience, details of experience and reflection on the meaning of experiences. Taped interviews, researcher insights, and member checks of transcripts constituted an audit trail for this study. Key findings included a progressive decline in Fall to Fall enrollment of international students at UM by 13.05% in the 5 years after 9/11, and by 6.15% at FIU in the seven post-9/11 years. In both institutions, there was an upsurge in interest in study abroad during the same period but less than 5% of enrolled students ventured abroad annually. I summarized the themes associated with the post-9/11 environment of international education as perceived by my participants at both institutions as 3Ms, 3Ts, and 1D: Menace of Anxiety and Fear, Menace of Insularity and Insecurity, Menace of Over-Regulation and Bigotry, Trajectory of Opportunity, Trajectory of Contradictions, Trajectory of Illusion, Fatalism and Futility, and Dominance of Technology. Based on these findings, I recommended an integrated Internationalization At Home Plus Collaborative Outreach (IAHPCO) approach to internationalization that is based on a post-9/11 recalibration of national security and international education as complementary rather than diametrically opposed concepts.

Labor turnover : its causes, consequences, and control strategy in five selected restaurants in the Miami area

The purpose of this study is to identify and analyze the basic causes of food service employee turnover in five selected restaurants in the Miami area. The withdrawal behavior in this study is treated in terms of controllable turnover, for the purpose of management, learning more about what action to take to solve this problem which has eaten into the fabric of the hospitality industry. The aim is to find out from the food service employees and management view of work for the purpose of identifying the variables which cause an employee to voluntarily leave a job. The objective is therefore, to analyze and describe the problem of labor turnover in these selected restaurants. Such description must precede efforts to arrive at solutions to the problem if these efforts are ever to be more than haphazard and superficial. Sigmund Freud once stated: "The true beginning of scientific activity consists in describing phenomena and only then in proceeding to group, classify and correlate them."1 The nature of the study is basically descriptive survey. Data is collected by the use of management questionnaire, food service employee questionnaire and finally employees job description index. The survey consisted of a series of well defined questions with open and closed endings dealing with employee with employee turnover. As Robert Ferber and P. J. Verdoom state in their book titled Research Method in Economics of Business: "Structured questionnaires, by supplying question formulations in very specific terms as well as the different possible answers are easier for the sample members to answer and also serve to reduce the danger of interviewer bias."2 The answers to the prepared questionnaire by sample members were then recorded. The results of the questionnaire responses were then compiled for presentation and analysis. 1 Julian Simon, Basic Research Methods in Social Science. Random House, New York, 1969, p.53. 2 Robert J. Ferber and P.J. Verdoon, Research Methods in Economics and Business, The McMillan Company, 1962, p. 20 9 .