3D Finite Volume Simulation of Accretion Discs with Spiral Shocks

We perform 2D and 3D numerical simulations of an accretion disc in a close binary system using the Simplified Flux vector Splitting (SFS) finite volume method. In our calculations, gas is assumed to be the ideal one, and we calculate the cases with gamma=1.01, 1.05, 1.1 and 1.2. The mass ratio of the mass losing star to the mass accreting star is unity. Our results show that spiral shocks are formed on the accretion disc in all cases. In 2D calculations we find that the smaller gamma is, the more tightly the spiral winds. We observe this trend in 3D calculations as well in somewhat weaker sense.Comment: 2 pages, LaTeX with 2 ps figures using crckapb.sty. To appear in the Proceedings of Numerical Astrophysics 1998, Tokyo, Japan, 10-13 March, 1998, eds. S. M. Miyama, K. Tomisaka and T. Hanawa (Kluwer Academic Publishers

Spiral Structure in IP Peg: Confronting Theory and Observations

The first convincing piece of evidence of spiral structure in the accretion disc in IP Pegasi was found by Steeghs et al. (1997). We performed two kinds of 2D hydrodynamic simulations, a SFS finite volume scheme and a SPH scheme, with a mass ratio of 0.5. Both results agreed well with each other. We constructed Doppler maps and line flux-binary phase relations based on density distributions, the results agreeing well with those obtained by observation.Comment: 4 pages, LaTeX with 2 ps figures using crckapb.sty. To appear in the Proceedings of Numerical Astrophysics 1998, Tokyo, Japan, 10-13 March, 1998, eds. S. M. Miyama, K. Tomisaka and T. Hanawa (Kluwer Academic Publishers

Educating Seth: An Ecosophical Conversation

Most accounts of human activity have a particular structure that supports the accounting. Education as a human activity has over centuries, and particularly in the past century, developed a narrative structure that, while seemingly "neutral", privileges accounts of a certain kind. The authors suggest that if ecosophical education is to find a presence in today's schools, the now dominant narrative structure needs to be challenged. By revealing an alternate narrative structure embodied in the particularities of a grade 4 classroom, the authors hope that such a narrative structure can provide ecosophical education with an authentic home in today's schools

Tracking Transfer of Reform Methodology from Science and Math College Courses to the Teaching Style of Beginning Teachers of Grades 5-12

The purpose of this study was to determine if reformed science and math courses at community colleges and the university were impacting education majors as they began a teaching career. The reformed courses, in contrast to typical lecture classes, implemented inquiry-based methods that emphasized deep understanding of fundamental science and math concepts. Trained evaluators, utilizing the Reformed Teaching Observation Protocol (RTOP) gathered a total of 86 classroom observations to gauge the level of reform that beginning teachers (one to three years’ teaching experience) were implementing in grades 5-12. The pre-service experience of the beginning teachers varied from having had zero to four reform courses. Results indicated that teachers who had completed reform college courses instructed in a significantly more reformed manner. Furthermore, analysis of years of teaching experience revealed that, while both control and experimental groups achieved higher RTOP scores as they progressed from year to year, the experimental group significantly outpaced their counterparts

The Impact of a Summer Workshop: Staff Orientation at Mesa Community College

The Arizona Collaborative for Excellence in the Preparation of Teachers (ACEPT) is a National Science Foundation (NSF) funded project to reform teacher preparation in Arizona. One of the major modes for initiating both collaboration and reform between and among university and community college staff has been the Summer Faculty Enhancement Workshops developed and offered by ACEPT co-principal investigators each summer since 1996. The summer of 1999 featured five workshops, one of which was the Geology Summer Workshop which brought participants into close contact with eighteen reformed practices appropriate for large lecture style classes. One of the nineteen participants was Ray Grant, Department of Science Chair at Mesa Community College, one of the collaborating institutions in ACEPT. This report describes what Ray, as department chair, did as a follow-up to the summer workshop. What occurred completely transformed the Department of Science staff orientation meeting held just prior to the fall semester. Some of the surprising events are described in this report. The transformation of the staff meeting not only speaks to the impact of the Geology Summer Workshop, but also suggests creative roles for staff orientation meetings in community college settings

Coordinate space proton-deuteron scattering calculations including Coulomb force effects

We present a practical method to solve the proton-deuteron scattering problem at energies above the three-body breakup threshold, in which we treat three-body integral equations in coordinate space accommodating long-range proton-proton Coulomb interactions. The method is examined for phase shift parameters, and then applied to calculations of differential cross sections in elastic and breakup reactions, analyzing powers, etc. with a realistic nucleon-nucleon force and three-nucleon forces. Effects of the Coulomb force and the three-nucleon forces on these observables are discussed in comparing with experimental data.Comment: 15 pages, 14 figures, submitted to PR

Gigantic Enhancement of Magneto-Chiral Effect in Photonic Crystals

We theoretically propose a method to enhance dramatically a magneto-chiral(MC) effect by using the photonic crystals composed of a multiferroic material. The MC effect, the directional birefringence even for unpolarized light, is so small that it has been difficult to observe experimentally. Two kinds of periodic structures are investigated; (a) a multilayer and (b) a stripe composed of a magneto-chiral material and air. In both cases, the difference in reflectivity between different magnetization directions is enhanced by a factor of hundreds compared with a bulk material.Comment: 3 pages, 3 figure

Magnetotransport Study of the Canted Antiferromagnetic Phase in Bilayer ν=2\nu=2 Quantum Hall State

Magnetotransport properties are investigated in the bilayer quantum Hall state at the total filling factor $\nu=2$. We measured the activation energy elaborately as a function of the total electron density and the density difference between the two layers. Our experimental data demonstrate clearly the emergence of the canted antiferromagnetic (CAF) phase between the ferromagnetic phase and the spin-singlet phase. The stability of the CAF phase is discussed by the comparison between experimental results and theoretical calculations using a Hartree-Fock approximation and an exact diagonalization study. The data reveal also an intrinsic structure of the CAF phase divided into two regions according to the dominancy between the intralayer and interlayer correlations.Comment: 6 pages, 7 figure

Microscopic Theory of Skyrmions in Quantum Hall Ferromagnets

We present a microscopic theory of skyrmions in the monolayer quantum Hall ferromagnet. It is a peculiar feature of the system that the number density and the spin density are entangled intrinsically as dictated by the W$$ algebra. The skyrmion and antiskyrmion states are constructed as W$_{\infty }$-rotated states of the hole-excited and electron-excited states, respectively. They are spin textures accompanied with density modulation that decreases the Coulomb energy. We calculate their excitation energy as a function of the Zeeman gap and compared the result with experimental data.Comment: 15 pages (to be published in PRB

The structure of cool accretion disc in semidetached binaries

We present the results of qualitative consideration of possible changes occurring during the transition from the hot accretion disc to the cool one. We argue the possible existence of one more type of spiral density waves in the inner part of the disc where gasdynamical perturbations are negligible. The mechanism of formation of such a wave as well as its parameters are considered. We also present the results of 3D gasdynamical simulation of cool accretion discs. These results confirm the hypothesis of possible formation of the spiral wave of a new, "precessional" type in the inner regions of the disc. Possible observational manifestations of this wave are discussed.Comment: LaTeX, 16 pages, 8 figures, to be published in Astron. Z