Numerical Study of Wave Propagation in Uniaxially Anisotropic Lorentzian Backward Wave Slabs

The propagation and refraction of a cylindrical wave created by a line current through a slab of backward wave medium, also called left-handed medium, is numerically studied with FDTD. The slab is assumed to be uniaxially anisotropic. Several sets of constitutive parameters are considered and comparisons with theoretical results are made. Electric field distributions are studied inside and behind the slab. It is found that the shape of the wavefronts and the regions of real and complex wave vectors are in agreement with theoretical results.Comment: 6 pages, figure

Correlates of substitution rate variation in mammalian protein-coding sequences

BACKGROUND: Rates of molecular evolution in different lineages can vary widely, and some of this variation might be predictable from aspects of species' biology. Investigating such predictable rate variation can help us to understand the causes of molecular evolution, and could also help to improve molecular dating methods. Here we present a comprehensive study of the life history correlates of substitution rate variation across the mammals, comparing results for mitochondrial and nuclear loci, and for synonymous and non-synonymous sites. We use phylogenetic comparative methods, refined to take into account the special nature of substitution rate data. Particular attention is paid to the widespread correlations between the components of mammalian life history, which can complicate the interpretation of results. RESULTS: We find that mitochondrial synonymous substitution rates, estimated from the 9 longest mitochondrial genes, show strong negative correlations with body mass and with maximum recorded lifespan. But lifespan is the sole variable to remain after multiple regression and model simplification. Nuclear synonymous substitution rates, estimated from 6 genes, show strong negative correlations with body mass and generation time, and a strong positive correlation with fecundity. In contrast to the mitochondrial results, the same trends are evident in rates of nonsynonymous substitution. CONCLUSION: A substantial proportion of variation in mammalian substitution rates can be explained by aspects of their life history, implying that molecular and life history evolution are closely interlinked in this group. The strength and consistency of the nuclear body mass effect suggests that molecular dating studies may have been systematically misled, but also that methods could be improved by incorporating the finding as a priori information. Mitochondrial synonymous rates also show the body mass effect, but for apparently quite different reasons, and the strength of the relationship with maximum lifespan provides support for the hypothesis that mtDNA damage is causally linked to aging

Lights on a Ground of Darkness: An Evocation of a Place aud Time

Review of: "Lights on a Ground of Darkness: An Evocation of a Place and Time," by Ted Kooser

Tunneling of Cooper pairs across voltage biased asymmetric single-Cooper-pair transistors

We analyze tunneling of Cooper pairs across voltage biased asymmetric single-Cooper-pair transistors. Also tunneling of Cooper pairs across two capacitively coupled Cooper-pair boxes is considered, when the capacitive coupling and Cooper pair tunneling are provided by a small Josephson junction between the islands. The theoretical analysis is done at subgap voltages, where the current-voltage characteristics depend strongly on the macroscopic eigenstates of the island(s) and their coupling to the dissipative environment. As the environment we use an impedance which satisfies Re[Z]<<R_Q and a few LC-oscillators in series with Z. The numerically calculated I-V curves are compared with experiments where the quantum states of mesoscopic SQUIDs are probed with inelastic Cooper pair tunneling. The main features of the observed I-V data are reproduced. Especially, we find traces of band structure in the higher excited states of the Cooper-pair boxes as well as traces of multiphoton processes between two Cooper-pair boxes in the regime of large Josephson coupling.Comment: 9 pages, 9 figures, Revtex

Sunday Afternoon on the Porch: Reflections of a Small Town in Iowa, 1939–1942

Review of: "Sunday Afternoon on the Porch: Reflections of a Small Town in Iowa, 1939–1942," by Jim Heynen (text), and Everett W. Kuntz (photog.

The War Comes to Plum Street

Review of: "The War Comes to Plum Street," by Bruce C. Smith

The War Comes to Plum Street

Review of: "The War Comes to Plum Street," by Bruce C. Smith

American Dreaming, Global Realities: Rethinking U. S. Immigration History

Review of: "American Dreaming, Global Realities: Rethinking U.S. Immigration History," edited by Donna R. Gabaccia and Vicki L. Rui

Patriotism, Courage, & Sacrifice: Warren County\u27s Response to WW II

Review of: Patriotism, Courage, & Sacrifice: Warren County\u27s Response to WW II by Jerry K. Beatt

Negative reflections of electromagnetic waves in chiral media

We investigate the reflection properties of electromagnetic/optical waves in isotropic chiral media. When the chiral parameter is strong enough, we show that an unusual \emph{negative reflection} occurs at the interface of the chiral medium and a perfectly conducting plane, where the incident wave and one of reflected eigenwaves lie in the same side of the boundary normal. Using such a property, we further demonstrate that such a conducting plane can be used for focusing in the strong chiral medium. The related equations under paraxial optics approximation are deduced. In a special case of chiral medium, the chiral nihility, one of the bi-reflections disappears and only single reflected eigenwave exists, which goes exactly opposite to the incident wave. Hence the incident and reflected electric fields will cancel each other to yield a zero total electric field. In another word, any electromagnetic waves entering the chiral nihility with perfectly conducting plane will disappear.Comment: 5 pages, 5 figure