146 research outputs found

    College Experiences of the Eastern Band of Cherokee Indians

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    A survey was distributed to all enrolled members of the Eastern Band of Cherokee Indian (EBCI) college students to compare the experiences of those attending Tribal and non-tribal colleges. The results of the survey provided data for a nonexperimental quantitative study that addressed 18 research questions in an effort to determine whether there is a significant difference between the educational experiences of EBCI college students who attend non-tribal institutions and those who attend Tribal colleges. In particular, there was a focus on three domains: student viewpoints on separation and alienation from their tribal community; tribal community connections; and individual perceptions of success. A comparison of the experiences by gender between students attending Tribal versus non-tribal colleges was made. The researcher used the Native American Collective Orientation and Pursuits in Education Scale (NACOPE) survey results as determinants of the college students’ experiences. The findings of this study indicated there were no significant differences between the experiences of EBCI students who attended either Tribal or nontribal colleges. In addition, there were no significant differences when gender and type of college were considered. However, there were significant differences in those attending Tribal and nontribal colleges regarding some dimensions. Students in both groups had significantly higher survey scores than the median test value on the NACOPE in three areas. These higher scores were observed in their overall experiences being reported as positive; feelings of community connectedness to their home tribe; and less feelings of separation and alienation on their college campuses

    Possible first order transition in the two-dimensional Ginzburg-Landau model induced by thermally fluctuating vortex cores

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    We study the two-dimensional Ginzburg-Landau model of a neutral superfluid in the vicinity of the vortex unbinding transition. The model is mapped onto an effective interacting vortex gas by a systematic perturbative elimination of all fluctuating degrees of freedom (amplitude {\em and} phase of the order parameter field) except the vortex positions. In the Coulomb gas descriptions derived previously in the literature, thermal amplitude fluctuations were neglected altogether. We argue that, if one includes the latter, the vortices still form a two- dimensional Coulomb gas, but the vortex fugacity can be substantially raised. Under the assumption that Minnhagen's generic phase diagram of the two- dimensional Coulomb gas is correct, our results then point to a first order transition rather than a Kosterlitz-Thouless transition, provided the Ginzburg-Landau correlation length is large enough in units of a microscopic cutoff length for fluctuations. The experimental relevance of these results is briefly discussed. [Submitted to J. Stat. Phys.]Comment: 36 pages, LaTeX, 6 figures upon request, UATP2-DB1-9

    The Shapes of Flux Domains in the Intermediate State of Type-I Superconductors

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    In the intermediate state of a thin type-I superconductor magnetic flux penetrates in a disordered set of highly branched and fingered macroscopic domains. To understand these shapes, we study in detail a recently proposed "current-loop" (CL) model that models the intermediate state as a collection of tense current ribbons flowing along the superconducting-normal interfaces and subject to the constraint of global flux conservation. The validity of this model is tested through a detailed reanalysis of Landau's original conformal mapping treatment of the laminar state, in which the superconductor-normal interfaces are flared within the slab, and of a closely-related straight-lamina model. A simplified dynamical model is described that elucidates the nature of possible shape instabilities of flux stripes and stripe arrays, and numerical studies of the highly nonlinear regime of those instabilities demonstrate patterns like those seen experimentally. Of particular interest is the buckling instability commonly seen in the intermediate state. The free-boundary approach further allows for a calculation of the elastic properties of the laminar state, which closely resembles that of smectic liquid crystals. We suggest several new experiments to explore of flux domain shape instabilities, including an Eckhaus instability induced by changing the out-of-plane magnetic field, and an analog of the Helfrich-Hurault instability of smectics induced by an in-plane field.Comment: 23 pages, 22 bitmapped postscript figures, RevTex 3.0, submitted to Phys. Rev. B. Higher resolution figures may be obtained by contacting the author

    Density Functional for Anisotropic Fluids

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    We propose a density functional for anisotropic fluids of hard body particles. It interpolates between the well-established geometrically based Rosenfeld functional for hard spheres and the Onsager functional for elongated rods. We test the new approach by calculating the location of the the nematic-isotropic transition in systems of hard spherocylinders and hard ellipsoids. The results are compared with existing simulation data. Our functional predicts the location of the transition much more accurately than the Onsager functional, and almost as good as the theory by Parsons and Lee. We argue that it might be suited to study inhomogeneous systems.Comment: To appear in J. Physics: Condensed Matte
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