Manifestations of Broken Symmetry: The Surfaces Phases of Ca\u3csub\u3e2−x\u3c/sub\u3eSr\u3csub\u3ex\u3c/sub\u3eRuO\u3csub\u3e4\u3c/sub\u3e

The discovery of superconductivity in Sr2RuO4 has renewed vigor in the study of correlated electron systems. The evolution of a p-wave superconducting state from a para- magnetic 2-dimensional Fermi liquid shows the ruthenate superconductivity is anything but conventional. Sr2RuO4 is isostructural with La2CuO4, the parent compound for the high temperature superconducting family La2−xSrxRuO4. The substitution of Ca2+ for Sr2+ generates a different structure involving a static rotation and tilt of the RuO6 octahedral, however, the antiferromagnetic insulating ground state of Ca2RuO4 is more akin to the cuprate parent. The generation of Ca2−xSrxRuO4 has offered a new family of com- pounds where the evolution from an antiferromagnetic insulator to a superconductor can be studied. Bulk studies have demonstrated how the intricate couplings between structural, orbital, electronic, and magnetic degrees of freedom are responsible for the exotic phases of the system. The layered perovskite structure which plays a key role in the properties observed also makes the crystals amenable to cleaving. Breaking symmetry by the creation of a surface on a quasi 2-dimensional system offers an opportunity to gain insight into the role of structure and symmetry on the properties of the system and offers a new avenue to discover new physics. Inelastic neutron scattering has been utilized to reveal the structural instability against the RuO6 tilt. While the Σ4 phonon mode involving the octahedral tilt shows classic soft phonon mode behavior across a tetragonal to orthorhombic phase transition, a new anomalous mode is discovered and its origin is explored. Surface phonon dynamics have been investigated across a Mott metal-to-insulator transition utilizing High Resolution Electron Energy Loss Spectroscopy where it is revealed the surface electronic transition temperature is significantly lower than the bulk. Low Energy Electron Diffraction has been employed to investigate the surface structure and structural transitions on the surface. Results show surface relaxations inhibit the RuO6 tilt dramatically altering the ensuing orthorhombic phase transition near a quantum critical point at xc = 0.5. It is also revealed that structural distortions accompanying the bulk metal-to-insulator transition are simply nonexistent on the surface. Physical manifestations from breaking symmetry in a correlated electron system are revealed

Teachers\u27 and Principals\u27 Perceptions Regarding the Implementation of Project Based Learning

The majority of teachers in a medium-sized, rural, low socioeconomic high school in the U.S. state of Arkansas were not implementing mandated project-based learning (PjBL) or were not implementing the method with fidelity, which was problematic because students may not have been reaping benefits associated with the method. The reasons underlying those conditions were not well understood. Therefore, the purpose of this study, which was reflected in the study\u27s 2 main research questions, was to better understand why teachers at the focus school were not implementing PjBL or were not implementing PjBL with fidelity and to generate potential solutions for improving teacher implementation of PjBL. Concepts from Ajzen and Fishbein\u27s theory of planned behavior, Bandura\u27s self-efficacy theory, and Deci and Ryan\u27s self-determination theory served as a foundation for understanding the conceptual framework in this study, teacher behavior. In this generic qualitative study, data were collected from 28 teachers using an online anonymous qualitative survey, and from 3 principals using a focus group. Documents from faculty and personnel meetings did not yield usable data. Open and axial coding were used to analyze the survey and focus group data. Results showed that teachers may not implement PjBL or may not implement it with fidelity because (a) they are not knowledgeable about PjBL, (b) they have a negative attitude toward PjBL, (c) they do not feel confident in their ability to implement PjBL, (d) they are not motivated to implement PjBL, and/or (e) they do not have the needed supports to implement PjBL. Results of this study could be used by stakeholders to improve teacher implementation of PjBL at the focus school, which could lead to positive social change in the form of improved student engagement, motivation, and achievement

The Hamstring-quadricep Strength Ratio of College-age Females

The purpose of this study was to describe the hamstring-quadricep strength ratio, as attained through isokinetic measurement, among eighteen to twenty-two year old female subjects. More specifically, the purpose of the study was to answer the following questions: 1. What is the hamstring-quadricep strength ratio of eighteen to twenty-two year old females as determined by isokinetic testing? 2. How does the hamstring-quadricep strength ratio for females, as determined in the present study, compare to the hamstring-quadricep strength ratio for males of similar age, as determined by isometric testing in previous studies? 3. Is there a significant difference between the hamstring-quadricep strength ratio and the variables age and dominant leg of the subjects? This study was conducted during the school years of 1977-80 in the training room of the gymnasium of Valparaiso University, Indiana. The subjects (N = 188) were volunteers to announcements made in physical education classes, dormitories and sororities for undergraduate females enrolled at Valparaiso University. The subjects were not selected as to height, weight, strength, or other anthropometrical classifications. Neither were the subjects selected as to prior athletic background. The investigator recognized the following limitations: 1. All subjects with existing knee and upper leg injuries, as determined by the preliminary history of the subject, were excluded. 2. No attempt was made to adjust body position to negate the effect of gravity; thus, gravity may affect, positively or negatively, the respective flexion and extension movements performed. 3. No attempt was made to control the activities of the subjects prior to the testing; thus, the subjects could have had various levels of rest or activity prior to the test

The 1980s—Did We Save the Stockholders While the Corporation Burned?

Although the long-range ramifications of the takeover craze are not yet known, one thing is clear: the 1980s changed the way American corporations do business. I suspect that the effects of the era have changed or will change the way in which America looks at corporations. In retrospect, many ask why this era of mega-mergers happened and why nothing was done to control events that seemed to be endangering the entire economy and the livelihood of millions. In order to appreciate these events, however, it is necessary to understand the environment in which they occurred

Short-Run Economic Impacts of Hurricane Katrina (and Rita)

Sturm; Erdölförderung; Offshore-Industrie; Makroökonomischer Einfluss; USA