Phonon spectra and thermodynamic properties of rare gas solids based on empirical and semi-empirical (ab initio) two-body potentials : a comparative study /

We study the phonon dispersion, cohesive and thermal properties of raxe gas solids Ne, Ar, Kr, and Xe, using a variety of potentials obtained from different approaches; such as, fitting to crystal properties, purely ab initio calculations for molecules and dimers or ab initio calculations for solid crystalline phase, a combination of ab initio calculations and fitting to either gas phase data or sohd state properties. We explore whether potentials derived with a certain approaxih have any obvious benefit over the others in reproducing the solid state properties. In particular, we study phonon dispersion, isothermal ajid adiabatic bulk moduli, thermal expansion, and elastic (shear) constants as a function of temperatiue. Anharmonic effects on thermal expansion, specific heat, and bulk moduli have been studied using A^ perturbation theory in the high temperature limit using the neaxest-neighbor central force (nncf) model as developed by Shukla and MacDonald [4]. In our study, we find that potentials based on fitting to the crystal properties have some advantage, particularly for Kr and Xe, in terms of reproducing the thermodynamic properties over an extended range of temperatiures, but agreement with the phonon frequencies with the measured values is not guaranteed. For the lighter element Ne, the LJ potential which is based on fitting to the gas phase data produces best results for the thermodynamic properties; however, the Eggenberger potential for Ne, where the potential is based on combining ab initio quantum chemical calculations and molecular dynamics simulations, produces results that have better agreement with the measured dispersion, and elastic (shear) values. For At, the Morse-type potential, which is based on M0ller-Plesset perturbation theory to fourth order (MP4) ab initio calculations, yields the best results for the thermodynamic properties, elastic (shear) constants, and the phonon dispersion curves.

Families of the traumatically brian-injured : a case study approach to perceptions of quality of service, degree of satisfaction, and family needs /

The purpose of this qualitative research study was to foster an understanding of the rehabilitation counselling practice offamilies of the brain-injured. Specifically, the study explores the perceptions of stakeholders in regards to the degree of satisfaction with the quality of service received. Questionnaires were administered, and semi-structured, openended interviews were conducted, with six participating families (n=8). Preliminary data were collected via two instruments: (i) the Family Participant Questionnaire, consisting of participants' sample characteristics, information pertaining to the history of the family, details of the injury, and information relating to the type, use, and need offamily services utilized; and (ii) the Community Integration Questionnaire, a measurement of the degree of social displacementllevel of community integration of the injured family member. Utilizing the procedural steps outlined by Colaizzi's (1978) method of protocol analysis, recommendations for a future program based on related and current family needs are discussed in detail. Substantiating and supporting information are offered to rehabilitation practitioners, educational planners, and policymakers alike, concerning the degree of satisfaction with rehabilitative service, and the means of improving upon the overall quality of health care to families of the brain-injured. Implications for clinical practice and research are also raised for discussion.

Male and Female Perspectives on Female Principals in South Africa

In South Africa, women are at a high risk of discrimination and opposition to authority when they obtain leadership positions, especially in education (Gouws & Kotze, 2007). The purpose of this study was to inquire into 10 secondary school educators’ perceptions of female principals’ effectiveness in two South African schools. Qualitative case study research methodology included interviews, as well as participant observations and semi-structured interviews. These interviews were conducted within two school settings in South Africa. The participants were teachers, department heads, and deputy principals. When the data were analyzed, it was found that all participants wanted a leader who was transformational and there was a strong preference for those who had feminine traits. This research showed the strong desire for transformational leaders as well as how feminine characteristics are not only starting to become more accepted, but also are now becoming preferred.

A Mixed-Method Study of Educator Knowledge and Practice Related to Student Socio-moral Development

The purpose of this study was to explore elementary educators’ knowledge of moral development, how this knowledge relates to their beliefs and sense of efficacy pertaining to character education practices and the socio-moral reasoning of their students. It was hypothesized that educators’ beliefs and practices related to character education would reflect their pedagogy rather than knowledge of moral development theory. It was further hypothesized that there would be differences in student socio-moral reasoning specifically the beliefs and desires that guide actions would differ based on grade and gender. This mixed-method study employing self-report questionnaires, open response vignettes, and semi-structured educator interviews yielded quantitative and qualitative data. Findings indicated socio-moral reasoning of students differed according to grade (age) and gender. Knowledge of moral development theory was found to vary among participants however some practices employed by educators did align with a social cognitive approach to moral development. Significant variables identified consistently among educator and student participants included, autonomy, social competence, sense of school community, and supportiveness. These variables, in conjunction with a sense of fairness, have been identified elsewhere as foundational to moral development (Nucci, 2009), and intrinsic motivation (Ryan & Deci, 2000) and are relevant to educators working to develop student socio-moral reasoning as an aspect of character.

The nature experiences of wilderness recreation leaders : throwing a stone

Through this descriptive exploratory study, the ways that wilderness recreation leaders experience nature are illuminated, deconstructing the assumed environmental benefits of and practices used in outdoor recreation (Haluza-Delay, 2001). This study also offers a foundation for advancing an environmental ethic among wilderness recreation leaders, participants, and organizations. With the continued degradation of and threats to natural environments, and the rising popularity of outdoor recreation participation, the outdoor recreation professional can be a leader in promoting human reconnections to the Earth (Henderson, 1999). Leaders of outdoor recreation experiences play an important role in encouraging these revived relationships to natural settings and can contribute to the necessary environmental consciousness shift needed within Western society (Hanna, 1995; Jordan, 1996). The purpose of this research was to describe the lived-experience in nature of wilderness recreation leaders. Specifically, a phenomenological method of inquiry was used to describe the meaning of nature, the connections and relationships to nature, and the behaviours and emotions experienced in nature by a group of wilderness canoe trip leaders employed by a residential summer camp. In addition to the implications of this research, achieving this outcome provides a rich descriptive understanding of wilderness leaders' experiences—a basis from which to extend future research endeavours and programmatic practices that promote effective environmental outcomes of outdoor recreation participation. Each of the five study participants was employed in the summer of 2003 by an Ontario residential summer camp organization that sponsors extended wilderness river canoe trips for youth. Two in-depth and semi-structured interviews were performed with each participant, asking them to reflect on the canoe trip that they led for the summer camp organization during 2003. Phenomenological data was analyzed according to Colaizzi's (1978) thematic analysis process. Consistent with van Manen's (1997) emphasis on phenomenological writing, the final result presents the essence of the nature experiences of wilderness recreation leaders in the format of a narrative description. This narrative piece is the culmination of this research effort. Throughout the journey, however, various foundations within the outdoor recreation field, such as minimum impact principles, environmentally responsible behaviours, anthropocentric and ecocentric worldviews, and effective leadership are deconstructed and discussed.

Solid state NMR chemical shifts as an alternative to diffraction data in the determination of SIC polytypic structures

Silicon carbide, which has many polytypic modifications of a very simple and very symmetric structure, is an excellent model system for exploring, the relationship between chemical shift, long-range dipolar shielding, and crystal structure in network solids. A simple McConnell equation treatment of bond anisotropy effects in a poly type predicts chemical shifts for silicon and carbon sites which agree well with the experiment, provided that contributions from bonds up to 100 A are included in the calculation. The calculated chemical shifts depend on three factors: the layer stacking sequence, electrical centre of gravity, and the spacings between silicon and carbon layers. The assignment of peaks to lattice sites is proved possible for three polytypes (6H, 15R, and 3C). The fact that the calculated chemical shifts are very sensitive to layer spacings provides us a potential way to detennine and refine a crystal structure. In this work, the layer spacings of 6H SiC have been calculated and are within X-ray standard deviations. Under this premise, the layer spacings of 15R have been detennined. 29Si and 13C single crystal nmr studies of 6H SiC polytype indicate that all silicons and carbons are magnetically anisotropic. The relationship between a magnetic shielding tensor component and layer spacings has been derived. The comparisons between experimental and semi-empirical chemical shielding tensor components indicate that the paramagnetic shielding of silicon should be included in the single crystal chemical shift calculation.