Wonders of Technology-Teaching Physics to Non-Scientists

Wonders of Technology is a conceptual physics course developed for non—science majors. The approach taken here in the introduction of the physical concepts is to depict their role in today’s technology, specifically the technology familiar to the students, and also to emphasize the connection between technology, art, and culture from the historical perspective. Why this approach? The traditional method of teaching physics is perceived by many students as user-unfriendly — they think physics is difficult, abstract, and, in fact, of little or no relevance to everyday life. The course Wonders of Technology alleviates this perception by placing the students on familiar ground that provides a fertile environment for an easier assimilation of knowledge. By examining the technology students use on a daily basis to demonstrate how physics makes things work, students are motivated to seek understanding of the principles underlying their operation. The course was developed within the guidelines of the new general education requirements at Virginia Commonwealth University. This presentation highlights some of the highly successful features of the newly developed course, with emphasis on responses from the education majors who are enrolled in the course

The Casimir Effect

After a review of the standard calculation of the Casimir force between two metallic plates at zero and non-zero temperatures, we present the study of microscopic models to determine the large-distance asymptotic force in the high-temperature regime. Casimir's conducting plates are modelized by plasmas of interacting charges at temperature T. The charges are either classical, or quantum-mechanical and coupled to a (classical) radiation field. In these models, the force obtained is twice weaker than that arising from standard treatments neglecting the microscopic charge fluctutations inside the bodies. The enforcement of inert boundary conditions on the field in the usual calculations turns out to be inadequate in this regime. Other aspects of dispersion forces are also reviewed. The status of (non-retarded) van der Waals-London forces in a dilute medium of non-zero temperature and density is investigated. In a proper scaling regime called the atomic limit (high dilution and low temperature), one is able to give the exact large-distance atomic correlations up to exponentially small terms as T->0. Retarded van der Waals forces and forces between dielectric bodies are also reviewed. Finally, the Casimir effect in critical phenomena is addressed by considering the free Bose gas. It is shown that the grand-canonical potential of the gas in a slab at the critical value of the chemical potential has finite size corrections of the standard Casimir type. They can be attributed to the existence of long-range order generated by gapless excitations in the phase with broken continuous symmetry.Comment: Lecture notes prepared for the proceedings of the 1st Warsaw School of Statistical Physics, Kazimierz, Poland, June 2005. To appear in Acta Physica Polonica (2006). 52 pages, 0 figures. Available at http://th-www.if.uj.edu.pl/acta/vol37/pdf/v37p2503.pd

Raising the Higgs mass with Yukawa couplings for isotriplets in vector-like extensions of minimal supersymmetry

Extra vector-like matter with both electroweak-singlet masses and large Yukawa couplings can significantly raise the lightest Higgs boson mass in supersymmetry through radiative corrections. I consider models of this type that involve a large Yukawa coupling between weak isotriplet and isodoublet chiral supermultiplets. The particle content can be completed to provide perturbative gauge coupling unification, in several different ways. The impact on precision electroweak observables is shown to be acceptably small, even if the new particles are as light as the current experimental bounds of order 100 GeV. I study the corrections to the lightest Higgs boson mass, and discuss the general features of the collider signatures for the new fermions in these models.Comment: 30 page

The role and effects of teaching assistants in English primary schools (Years 4 to 6) 2000-2003. Results from the Class Size and Pupil-Adult Ratios (CSPAR) KS2 Project

It is widely assumed that increasing the number of Teaching Assistants (TAs) in the classroom will be beneficial to children, and this is one important aim of the recently implemented Workforce Agreement. But there are still significant gaps in knowledge about many aspects of their deployment and impact. The Class Size and Pupil-Adult Ratio (CSPAR) KS2 study built on earlier findings when the pupils were in reception and KS1 and investigated: 1. the deployment of TAs in classrooms and how key parties involved perceived this; 2. the effect of TAs on interactions involving pupils and teachers in the same classrooms, and on pupil attainments. The study had a longitudinal, mixed method and multi-informant design. There were 202 schools, 332 classes and 8728 pupils in Y4. Methods of data collection included: for the whole sample) questionnaires completed by TAs, teachers and head teachers, assessments of pupil attainments in mathematics, English and science, data on pupil background, and (for a sub-sample) case studies and a systematic observation study. This study found that the TA’s role in KS2 is predominantly a direct one, in the sense of face-to-face interactions supporting certain pupils. There was no evidence that the presence of TAs, or any characteristic of TAs, had a measurable effect on pupil attainment. However, results were clear in showing that TAs had an indirect effect on teaching, e.g., pupils had a more active form of interaction with the teacher and there was more individualised teacher attention. This supported teachers’ views that TAs are effective in supporting them in this way. We conclude that more attention needs to be paid to what we call the pedagogical role of TAs so that they can be used effectively to help teachers and pupils, particularly in the context of the enhanced roles for TAs being introduced as part of the Government’s remodeling agenda

Galactic annihilation emission from nucleosynthesis positrons

The Galaxy hosts a widespread population of low-energy positrons revealed by successive generations of gamma-ray telescopes through a bright annihilation emission from the bulge region, with a fainter contribution from the inner disk. The exact origin of these particles remains currently unknown. We estimate the contribution to the annihilation signal of positrons generated in the decay of radioactive 26Al, 56Ni and 44Ti. We adapted the GALPROP propagation code to simulate the transport and annihilation of radioactivity positrons in a model of our Galaxy. Using plausible source spatial distributions, we explored several possible propagation scenarios to account for the large uncertainties on the transport of ~1MeV positrons in the interstellar medium. We then compared the predicted intensity distributions to the INTEGRAL/SPI observations. We obtain similar intensity distributions with small bulge-to-disk ratios, even for extreme large-scale transport prescriptions. At least half of the positrons annihilate close to their sources, even when they are allowed to travel far away. In the high-diffusion, ballistic case, up to 40% of them escape the Galaxy. In proportion, this affects bulge positrons more than disk positrons because they are injected further off the plane in a tenuous medium, while disk positrons are mostly injected in the dense molecular ring. The predicted intensity distributions are fully consistent with the observed longitudinally-extended disk-like emission, but the transport scenario cannot be strongly constrained by the current data. Nucleosynthesis positrons alone cannot account for the observed annihilation emission in the frame of our model. An additional component is needed to explain the strong bulge contribution, and the latter is very likely concentrated in the central regions if positrons have initial energies in the 100keV-1MeV range.Comment: 16 pages, 7 figures, accepted for publication in A&

The blocks of the Brauer algebra in characteristic zero

We determine the blocks of the Brauer algebra in characteristic zero. We also give information on the submodule structure of standard modules for this algebra

Duality in Fuzzy Sigma Models

Nonlinear `sigma' models in two dimensions have BPS solitons which are solutions of self- and anti-self-duality constraints. In this paper, we find their analogues for fuzzy sigma models on fuzzy spheres which were treated in detail by us in earlier work. We show that fuzzy BPS solitons are quantized versions of `Bott projectors', and construct them explicitly. Their supersymmetric versions follow from the work of S. Kurkcuoglu.Comment: Latex, 9 pages; misprints correcte