Self-energy correction to the bound-electron g factor in H-like ions

The one-loop self-energy correction to the 1s electron g factor is evaluated to all orders in Z\alpha with an accuracy, which is essentially better than that of previous calculations of this correction. As a result, the uncertainty of the theoretical prediction for the bound-electron g factor in H-like carbon is reduced by a factor of 3. This improves the total accuracy of the recent electron-mass determination [Beier et al. Phys. Rev. Lett. 88, 011603 (2002)]. The new value of the electron mass is found to be m_e = 0.000 548 579 909 3(3) u

Zeeman effect of the hyperfine structure levels in hydrogenlike ions

The fully relativistic theory of the Zeeman splitting of the $1s$ hyperfine structure levels in hydrogenlike ions is considered for the magnetic field magnitude in the range from 1 to 10 T. The second-order corrections to the Breit -- Rabi formula are calculated and discussed. The results can be used for a precise determination of nuclear magnetic moments from $g$ factor experiments.Comment: 13 page

g factor of lithiumlike silicon 28Si11+

The g factor of lithiumlike 28Si11+ has been measured in a triple-Penning trap with a relative uncertainty of 1.1x10^{-9} to be g_exp=2.0008898899(21). The theoretical prediction for this value was calculated to be g_th=2.000889909(51) improving the accuracy to 2.5x10^{-8} due to the first rigorous evaluation of the two-photon exchange correction. The measured value is in excellent agreement with the state-of-the-art theoretical prediction and yields the most stringent test of bound-state QED for the g factor of the 1s^22s state and the relativistic many-electron calculations in a magnetic field

Evaluation of the self-energy correction to the g-factor of S states in H-like ions

A detailed description of the numerical procedure is presented for the evaluation of the one-loop self-energy correction to the $g$-factor of an electron in the $1s$ and $2s$ states in H-like ions to all orders in $Z\alpha$.Comment: Final version, December 30, 200

How do baleen whales stow their filter? A compoarative bioimechanical analysis of baleen bending

Bowhead and right whale (balaenid) baleen filtering plates, longer in vertical dimension (3-4+ m) than the closed mouth, presumably bend during gape closure. This has not been observed in live whales, even with scrutiny of videorecorded feeding sequences. To determine what happens to baleen as gape closes, we conducted an integrative, multifactorial study including materials testing, functional (flow tank and kinematic) testing, and histological examination. We measured baleen bending properties along the dorsoventral length of plates and anteroposterior location within a rack of plates via mechanical (axial bending, composite flexure, compression, and tension) tests of hydrated and air-dried tissue samples from balaenid and other whale baleen. Balaenid baleen is remarkably strong yet pliable, with ductile fringes and low stiffness and high elasticity when wet; it likely bends in the closed mouth when not used for filtration. Calculation of flexural modulus from stress/strain experiments shows baleen is slightly more flexible where it emerges from the gums and at its ventral terminus, but kinematic analysis indicates plates bend evenly along their whole length. Fin and humpback whale baleen has similar material properties but less flexibility, with no dorsoventral variation. Internal horn tubes have greater external and hollow luminal diameter but lower density in lateral relative to medial baleen of bowhead and fin whales, suggesting greater capacity for lateral bending. Baleen bending has major consequences not only for feeding morphology and energetics but also conservation given that entanglement in fishing gear is a leading cause of whale mortality

Recoil correction to the bound-electron g factor in H-like atoms to all orders in αZ\alpha Z

The nuclear recoil correction to the bound-electron g factor in H-like atoms is calculated to first order in $m/M$ and to all orders in $\alpha Z$. The calculation is performed in the range Z=1-100. A large contribution of terms of order $(\alpha Z)^5$ and higher is found. Even for hydrogen, the higher-order correction exceeds the $(\alpha Z)^4$ term, while for uranium it is above the leading $(\alpha Z)^2$ correction.Comment: 6 pages, 3 tables, 1 figur

Reconstructing Dryopteris “semicristata” (Dryopteridaceae): Molecular profiles of tetraploids verify their undiscovered diploid ancestor

This is the publisher's version, also available electronically from http://www.amjbot.org.• Premise of the study: Discovering missing ancestors is essential to understanding the evolutionary history of biodiversity on Earth. Evidence from extinct species can provide links for reconstructing intricate patterns of reticulate relationships among extant descendents. When fossils are unavailable and other evidence yields competing hypotheses to explain species ancestry, data from proteins and DNA can help resolve conflicts and generate novel perspectives. The identity of a parent shared by two tetraploid species in the cosmopolitan fern genus Dryopteris has remained elusive for more than 50 years. Based on available data, four hypotheses were developed previously, each providing a different resolution to this uncertainty. • Methods: New molecular evidence from studies of isozymes and restriction site analysis of chloroplast DNA tested the competing hypotheses about the diploid ancestors of these two extant Dryopteris polyploids. • Key results: The results falsify two of the hypotheses, resolve the uncertainty in the third, and support the fourth. • Conclusions: Our data validate the prior existence of Dryopteris “semicristata,” which was proposed 38 years ago as a diploid progenitor of the allotetraploids D. cristata and D. carthusiana but has never been collected. After developing a phylogeny using the new molecular data, we describe a plausible morphology for D. “semicristata” by extrapolating likely character states from related extant species

g factor of Li-like ions with nonzero nuclear spin

The fully relativistic theory of the g factor of Li-like ions with nonzero nuclear spin is considered for the (1s)^2 2s state. The magnetic-dipole hyperfine-interaction correction to the atomic g factor is calculated including the one-electron contributions as well as the interelectronic-interaction effects of order 1/Z. This correction is combined with the interelectronic-interaction, QED, nuclear recoil, and nuclear size corrections to obtain high-precision theoretical values for the g factor of Li-like ions with nonzero nuclear spin. The results can be used for a precise determination of nuclear magnetic moments from g factor experiments.Comment: 20 pages, 5 figure