Reinventing the High School Government Course: Rigor, Simulations, and Learning from Text

The high school government course is arguably the main site of formal civic education in the country today. This article presents the curriculum that resulted from a multiyear study aimed at improving the course. The pedagogic model, called Knowledge in Action, centers on a rigorous form of project-based learning where the projects are weeks-long simulations. The first section introduces the course and the study, the second describes the methodology and design principles, the third describes the political simulations that are the spine of the course, and the fourth examines implementation and design issues that emerged across the years. The latter are concerned with the centrality of simulations, the selection of core content and skills for deeper learning, and the ongoing struggle to help students learn from texts. Readers are invited to adopt or adapt any of the design elements to suit their needs

Experimental transonic flutter characteristics of two 72 deg-sweep delta-wing models

Transonic flutter boundaries are presented for two simple, 72 deg. sweep, low-aspect-ratio wing models. One model was an aspect-ratio 0.65 delta wing; the other model was an aspect-ratio 0.54 clipped-delta wing. Flutter boundaries for the delta wing are presented for the Mach number range of 0.56 to 1.22. Flutter boundaries for the clipped-delta wing are presented for the Mach number range of 0.72 to 0.95. Selected vibration characteristics of the models are also presented

The Casimir Effect for Parallel Plates Revisited

The Casimir effect for a massless scalar field with Dirichlet and periodic boundary conditions (b.c.) on infinite parallel plates is revisited in the local quantum field theory (lqft) framework introduced by B.Kay. The model displays a number of more realistic features than the ones he treated. In addition to local observables, as the energy density, we propose to consider intensive variables, such as the energy per unit area $\epsilon$, as fundamental observables. Adopting this view, lqft rejects Dirichlet (the same result may be proved for Neumann or mixed) b.c., and accepts periodic b.c.: in the former case $\epsilon$ diverges, in the latter it is finite, as is shown by an expression for the local energy density obtained from lqft through the use of the Poisson summation formula. Another way to see this uses methods from the Euler summation formula: in the proof of regularization independence of the energy per unit area, a regularization-dependent surface term arises upon use of Dirichlet b.c. but not periodic b.c.. For the conformally invariant scalar quantum field, this surface term is absent, due to the condition of zero trace of the energy momentum tensor, as remarked by B.De Witt. The latter property does not hold in tha application to the dark energy problem in Cosmology, in which we argue that periodic b.c. might play a distinguished role.Comment: 25 pages, no figures, late

Transgenic avian-derived recombinant human interferon-alpha2b (AVI-005) in healthy subjects: an open-label, single-dose, controlled study.

BACKGROUND/AIMS: This study characterized the safety and pharmacological properties of AVI-005, a novel glycosylated recombinant human interferon-alpha2b produced from the egg whites of chickens transfected with human cDNA. METHODS: 18 healthy volunteers received single subcutaneous rising doses (0.5, 1.66 or 5 million international units, MIU) of AVI-005. A randomized parallel comparator group of 10 subjects received 5 MIU of unglycosylated IFN-alpha2b (Intron A). The pharmacokinetic parameters t1/2, tmax, Cmax, AUC0-24h, Vd, and clearance were compared between AVI-005 and unglycosylated IFN-alpa2b. RESULTS: At equipotent doses, AVI-005 had a larger AUC0-24h than the control interferon. Pharmacodynamic markers ofneopterin and beta2-microglobulin for the two treatments were similar. These markers were increased by AVI-005 in a dose-dependent manner. Pharmacodynamic responses to treatment with AVI-005 were shown by the change in mRNA expression for interferon inducible protein kinase and 2\u275\u27-oligoadenylate synthetase. Adverse events in the two groups were qualitatively and quantitatively similar. CONCLUSION: AVI-005 demonstrates biological activity and pharmaco-kinetic properties in humans that support further development

The flaring and quiescent components of the solar corona

The solar corona is a template to understand stellar activity. The Sun is a moderately active star, and its corona differs from active stars: active stellar coronae have a double-peaked EM(T) with the hot peak at 8-20 MK, while the non flaring solar corona has one peak at 1-2 MK. We study the average contribution of flares to the solar EM(T) to investigate indirectly the hypothesis that the hot peak of the EM(T) of active stellar coronae is due to a large number of unresolved solar-like flares, and to infer properties on the flare distribution from nano- to macro-flares. We measure the disk-integrated time-averaged emission measure, EM_F(T), of an unbiased sample of solar flares analyzing uninterrupted GOES/XRS light curves over time intervals of one month. We obtain the EM_Q(T) of quiescent corona for the same time intervals from the Yohkoh/SXT data. To investigate how EM_F(T) and EM_Q(T) vary with the solar cycle, we evaluate them at different phases of the cycle (from Dec. 1991 to Apr. 1998). Irrespective of the solar cycle phase, EM_F(T) appears like a peak of the distribution significantly larger than the values of EM_Q(T) for T~5-10 MK. As a result the time-averaged EM(T) of the whole solar corona is double-peaked, with the hot peak, due to time-averaged flares, located at temperature similar of that of active stars, but less enhanced. The EM_F(T) shape supports the hypothesis that the hot EM(T) peak of active coronae is due to unresolved solar-like flares. If this is the case, quiescent and flare components should follow different scaling laws for increasing stellar activity. In the assumption that the heating of the corona is entirely due to flares, from nano- to macro-flares, then either the flare distribution or the confined plasma response to flares, or both, are bimodal.Comment: 8 pages, 7 postscript figures, accepted for publication in Astronomy and Astrophysic

The Red Sea, Coastal Landscapes, and Hominin Dispersals

This chapter provides a critical assessment of environment, landscape and resources in the Red Sea region over the past five million years in relation to archaeological evidence of hominin settlement, and of current hypotheses about the role of the region as a pathway or obstacle to population dispersals between Africa and Asia and the possible significance of coastal colonization. The discussion assesses the impact of factors such as topography and the distribution of resources on land and on the seacoast, taking account of geographical variation and changes in geology, sea levels and palaeoclimate. The merits of northern and southern routes of movement at either end of the Red Sea are compared. All the evidence indicates that there has been no land connection at the southern end since the beginning of the Pliocene period, but that short sea crossings would have been possible at lowest sea-level stands with little or no technical aids. More important than the possibilities of crossing the southern channel is the nature of the resources available in the adjacent coastal zones. There were many climatic episodes wetter than today, and during these periods water draining from the Arabian escarpment provided productive conditions for large mammals and human populations in coastal regions and eastwards into the desert. During drier episodes the coastal region would have provided important refugia both in upland areas and on the emerged shelves exposed by lowered sea level, especially in the southern sector and on both sides of the Red Sea. Marine resources may have offered an added advantage in coastal areas, but evidence for their exploitation is very limited, and their role has been over-exaggerated in hypotheses of coastal colonization

Galactic winds driven by cosmic-ray streaming

Galactic winds are observed in many spiral galaxies with sizes from dwarfs up to the Milky Way, and they sometimes carry a mass in excess of that of newly formed stars by up to a factor of ten. Multiple driving processes of such winds have been proposed, including thermal pressure due to supernova-heating, UV radiation pressure on dust grains, or cosmic ray (CR) pressure. We here study wind formation due to CR physics using a numerical model that accounts for CR acceleration by supernovae, CR thermalization, and advective CR transport. In addition, we introduce a novel implementation of CR streaming relative to the rest frame of the gas. We find that CR streaming drives powerful and sustained winds in galaxies with virial masses M_200 < 10^{11} Msun. In dwarf galaxies (M_200 ~ 10^9 Msun) the winds reach a mass loading factor of ~5, expel ~60 per cent of the initial baryonic mass contained inside the halo's virial radius and suppress the star formation rate by a factor of ~5. In dwarfs, the winds are spherically symmetric while in larger galaxies the outflows transition to bi-conical morphologies that are aligned with the disc's angular momentum axis. We show that damping of Alfven waves excited by streaming CRs provides a means of heating the outflows to temperatures that scale with the square of the escape speed. In larger haloes (M_200 > 10^{11} Msun), CR streaming is able to drive fountain flows that excite turbulence. For halo masses M_200 > 10^{10} Msun, we predict an observable level of H-alpha and X-ray emission from the heated halo gas. We conclude that CR-driven winds should be crucial in suppressing and regulating the first epoch of galaxy formation, expelling a large fraction of baryons, and - by extension - aid in shaping the faint end of the galaxy luminosity function. They should then also be responsible for much of the metal enrichment of the intergalactic medium.Comment: 25 pages, 14 figures, accepted by MNRA

Control of star formation by supersonic turbulence

Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation relying on the control by turbulence. We demonstrate that although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic scale star formation. (ABSTRACT ABBREVIATED)Comment: Invited review for "Reviews of Modern Physics", 87 pages including 28 figures, in pres