The 70 Percent Solution Summary Report

This summary report offers a different vision of how educators, employers, parents, and all those who care about the development of young people should understand and address life after high school. The report finds that students and all Americans need better and more informed choices for the next step after high school, and at every stage of their careers, as they seek the knowledge and skills that will help them succeed in the workplace and meet their economic necessities. It calls upon parents, students, policymakers, and educators to recognize the realities and opportunities of the changing new economy for people of different educational backgrounds -- and to support the increasing importance of lifelong learning to the success of so many Americans

The 70 Percent Solution: Five Principles for Helping Young People Make Decisions During and After High School

This report offers a different vision of how educators, employers, parents, and all those who care about the development of young people should understand and address life after high school. The report finds that students and all Americans need better and more informed choices for the next step after high school, and at every stage of their careers, as they seek the knowledge and skills that will help them succeed in the workplace and meet their economic necessities. It calls upon parents, students, policymakers, and educators to recognize the realities and opportunities of the changing new economy for people of different educational backgrounds -- and to support the increasing importance of lifelong learning to the success of so many Americans

Ubiquitous finite-size scaling features in IV characteristics of various dynamic XY models in two dimensions

Two-dimensional (2D) XY model subject to three different types of dynamics, namely Monte Carlo, resistivity shunted junction (RSJ), and relaxational dynamics, is numerically simulated. From the comparisons of the current-voltage (I-V) characteristics, it is found that up to some constants I-V curves at a given temperature are identical to each other in a broad range of external currents. Simulations of the Villain model and the modified 2D XY model allowing stronger thermal vortex fluctuations are also performed with RSJ type of dynamics. The finite-size scaling suggested in Medvedyeva et al. [Phys. Rev. B 62, 14531(2000)] is confirmed for all dynamic models used, implying that this finite-size scaling behaviors in the vicinity of the Kosterlitz-Thouless transition are quite robust.Comment: 7 pages, 4 pictures, accepted in Physica

Renormalization Group Study of the Intrinsic Finite Size Effect in 2D Superconductors

Vortices in a thin-film superconductor interact logarithmically out to a distance on the order of the two-dimensional (2D) magnetic penetration depth $\lambda_\perp$, at which point the interaction approaches a constant. Thus, because of the finite $\lambda_\perp$, the system exhibits what amounts to an {\it intrinsic} finite size effect. It is not described by the 2D Coulomb gas but rather by the 2D Yukawa gas (2DYG). To study the critical behavior of the 2DYG, we map the 2DYG to the massive sine-Gordon model and then perform a renormalization group study to derive the recursion relations and to verify that $\lambda_\perp$ is a relevant parameter. We solve the recursion relations to study important physical quantities for this system including the renormalized stiffness constant and the correlation length. We also address the effect of current on this system to explain why finite size effects are not more prevalent in experiments given that the 2D magnetic penetration depth is a relevant parameter.Comment: 8 pages inRevTex, 5 embedded EPS figure

Campus Vol VII N 2

Howard Studio. Betty Janda, Junior . Picture. 0. Bedell, Barrie. Campus Affords Opportunity . Prose. 2. Pierson, Pete. Untitled. Cartoon. 2.; Gould, James. A Christmas Fable . Prose. 3. Dake, Hart. The House I Lived In, Or The Real Story Behind the Closing of The Pines . Prose. 4. Adams, Rob and Bill Hughes. Eastward Ha! . Prose. 6. Wellman, Lynn. Denison Debators Used to Winning . Prose. 8. Gould, Chester. The American Way . Prose. 9.; Dutro, Jacqui. The Portable Christmas . Prose. 10. Malcomson, Bill. A City Street . Prose. 12. Pierson, Pete. Untitled. Cartoon. 13. Umphrey, Shirley. 1952 Campus Gal-ender Girls . Poem. 14. Smith, Orlo et al. 1952 Campus Gal-ender Girls . Picture. 14. Jacobs, Edward R. It Came to Pass . Prose. 18. Hodges, John. A Native Returns . Prose. 19. Pierson, Pete. Untitled. Cartoon. 21. Hart, Herbert. The Case of The Reticent Regurgitator . Prose. 23. Potts. Untitled. Cartoon. 23. Rounds, Dave. Infamous Past Words . Cartoon. 24. Potts. Untitled. Cartoon. 25

Dynamic Scaling and Two-Dimensional High-Tc Superconductors

There has been ongoing debate over the critical behavior of two-dimensional superconductors; in particular for high Tc superconductors. The conventional view is that a Kosterlitz-Thouless-Berezinskii transition occurs as long as finite size effects do not obscure the transition. However, there have been recent suggestions that a different transition actually occurs which incorporates aspects of both the dynamic scaling theory of Fisher, Fisher, and Huse and the Kosterlitz-Thouless-Berezinskii transition. Of general interest is that this modified transition apparently has a universal dynamic critical exponent. Some have countered that this apparent universal behavior is rooted in a newly proposed finite-size scaling theory; one that also incorporates scaling and conventional two-dimensional theory. To investigate these issues we study DC voltage versus current data of a 12 angstrom thick YBCO film. We find that the newly proposed scaling theories have intrinsic flexibility that is relevant to the analysis of the experiments. In particular, the data scale according to the modified transition for arbitrarily defined critical temperatures between 0 K and 19.5 K, and the temperature range of a successful scaling collapse is related directly to the sensitivity of the measurement. This implies that the apparent universal exponent is due to the intrinsic flexibility rather than some real physical property. To address this intrinsic flexibility, we propose a criterion which would give conclusive evidence for phase transitions in two-dimensional superconductors. We conclude by reviewing results to see if our criterion is satisfied.Comment: 14 page

Dynamic scaling for 2D superconductors, Josephson junction arrays and superfluids

The value of the dynamic critical exponent $z$ is studied for two-dimensional superconducting, superfluid, and Josephson Junction array systems in zero magnetic field via the Fisher-Fisher-Huse dynamic scaling. We find $z\simeq5.6\pm0.3$, a relatively large value indicative of non-diffusive dynamics. Universality of the scaling function is tested and confirmed for the thinnest samples. We discuss the validity of the dynamic scaling analysis as well as the previous studies of the Kosterlitz-Thouless-Berezinskii transition in these systems, the results of which seem to be consistent with simple diffusion ($z=2$). Further studies are discussed and encouraged.Comment: 19 pages in two-column RevTex, 8 embedded EPS figure

Dynamic Impedance of Two-Dimensional Superconducting Films Near the Superconducting Transition

The sheet impedances, Z(w,T), of several superconducting a-Mo77Ge23 films and one In/InOx film have been measured in zero field using a two-coil mutual inductance technique at frequencies from 100 Hz to 100 kHz. Z(w,T) is found to have three contributions: the inductive superfluid, renormalized by nonvortex phase fluctuations; conventional vortex-antivortex pairs, whose contribution turns on very rapidly just below the usual Kosterlitz-Thouless-Berezinskii unbinding temperature; and an anomalous contribution. The latter is predominantly resistive, persists well below the KTB temperature, and is weakly dependent on frequency down to remarkably low frequencies, at least 100 Hz. It increases with T as e-U'(T)/kT, where the activation energy, U'(T), is about half the energy to create a vortex-antivortex pair, indicating that the frequency dependence is that of individual excitations, rather than critical behavior.Comment: 10 pages, 10 figs; subm PR