Generalised action-angle coordinates defined on island chains

Straight-field-line coordinates are very useful for representing magnetic fields in toroidally confined plasmas, but fundamental problems arise regarding their definition in 3-D geometries because of the formation of islands and chaotic field regions, ie non-integrability. In Hamiltonian dynamical systems terms these coordinates are a form of action-angle variables, which are normally defined only for integrable systems. In order to describe 3-D magnetic field systems, a generalisation of this concept was proposed recently by the present authors that unified the concepts of ghost surfaces and quadratic-flux-minimising (QFMin) surfaces. This was based on a simple canonical transformation generated by a change of variable $\theta = \theta(\Theta,\zeta)$, where $\theta$ and $\zeta$ are poloidal and toroidal angles, respectively, with $\Theta$ a new poloidal angle chosen to give pseudo-orbits that are a) straight when plotted in the $\zeta,\Theta$ plane and b) QFMin pseudo-orbits in the transformed coordinate. These two requirements ensure that the pseudo-orbits are also c) ghost pseudo-orbits. In the present paper, it is demonstrated that these requirements do not \emph{uniquely} specify the transformation owing to a relabelling symmetry. A variational method of solution that removes this lack of uniqueness is proposed.Comment: 10 pages. Accepted by Plasma Physics and Controlled Fusion as part of a cluster of refereed papers in a special issue containing papers arising from the Joint International Stellarator & Heliotron Workshop and Asia-Pacific Plasma Theory Conference, held in Canberra and Murramarang Resort, Australia, 30 January - 3 February, 201

Field Playback of Male Display Attracts Females in Lek Breeding Sage Grouse

Recent correlational studies of lekking sage grouse suggest that male vocal display attracts females. To test this hypothesis further, the natural displays of a territorial male were supplemented with the tape-recorded display of another reproductively successful individual. Significantly, more females approached the speaker\u27s location on days when the recording was played, and also on nonplayback days immediately following a playback, than on other nonplayback days. Analysis of male displays indicated that females were responding to the playback itself rather than to changes in male behavior. The after-response following a playback suggests that some females present during a playback remembered its location and approached on a subsequent lek visit. The results provide necessary support for the epigamic function of vocal display, and suggest ways in which female responses to male display may influence lek structure

Microsatellite analysis of female mating behaviour in lek-breeding sage grouse

We used microsatellite DNA markers to genotype chicks in 10 broods of lek-breeding sage grouse, Centrocercus urophasianus, whose mothers’ behaviour was studied by radio tracking and observing leks. Previous behavioural studies suggested that almost all matings are performed by territorial males on leks and that multiple mating is rare. Two broods (20%) were sired by more than one male. Genetic analyses of the broods of eight females that visited an intensively studied lek were consistent with behavioural observations. Four females observed mating produced singly sired broods and males other than the individual observed copulating were excluded as sires for most or all of their chicks. Territorial males at the study lek were excluded as sires of broods of four other females that visited the lek but were not observed mating there. Radio-tracking suggested that two of these females mated at other leks. Our results confirm the reliability of mating observations at leks, but do not rule out a possible unseen component of the mating system

Sexual Selection in Lekking Sage Grouse: Phenotypic Correlates of Male Mating Success

Mate choice cues in sage grouse were reinvestigated by analyzing relationships between male mating success and a range of suggested cues. Display cues were implicated by significant relationships between mating status (whether or not a male mated) and lek attendance, display rate (corrected for effects of female proximity and time of day) and an acoustic component related to temporal and frequency measures of a whistle emitted during the strut display. Although display rate and the acoustic component were intercorrelated, both exerted significant partial effects on mating success in multivariate analyses. These display measures also differed significantly between males. In contrast, mating success was not significantly related to measures of territory characteristics, including size and proximity to the lek center, or to body size. These results resolve discrepancies between previous studies and provide a basis for experimental analysis of the role of female choice in this lek system

Physicians and Lawyers: Science, Art, and Conflict

The relations between physicians and lawyers have deteriorated rapidly over the past several decades, most particularly since the early 70s when the perception that a medical malpractice crisis existed in America became widespread. Some believe that the factors dividing the two professions . are linked (1) to professional jealousy, (2) to sometimes conflicting economic interests, or (3) to difficulties in communication, since both professions use many of the same words, or terms of art, but with different intended meanings. While the authors agree that these factors may have aggravated the problem, they believe that the conflict\u27s real roots are in the very different ways in which physicians and lawyers are trained and in the different epistemologies that each profession has accepted, as a result of which each reasons and solves problems in a manner that not only diverges from but sometimes contradicts the other\u27s. The authors conclude that only as the varying epistemologies begin to converge can physicians and lawyers begin to approach problems in more similar ways, and to discover the underlying compatibility of many of their interests and goals

Potential ring of Dirac nodes in a new polymorph of Ca3_3P2_2

We report the crystal structure of a new polymorph of Ca$_3$P$_2$, and an analysis of its electronic structure. The crystal structure was determined through Rietveld refinements of powder synchrotron x-ray diffraction data. Ca$_3$P$_2$ is found to be a variant of the Mn$_5$Si$_3$ structure type, with a Ca ion deficiency compared to the ideal 5:3 stoichiometry to yield a charge-balanced compound. We also report the observation of a secondary phase, Ca$_5$P$_3$H, in which the Ca and P sites are fully occupied and the presence of interstitial hydride ions creates a closed-shell electron-precise compound. We show via electronic structure calculations of Ca$_3$P$_2$ that the compound is stabilized by a gap in the density of states compared to the hypothetical compound Ca$_5$P$_3$. Moreover, the calculated band structure of Ca$_3$P$_2$ indicates that it should be a three-dimensional Dirac semimetal with a highly unusual ring of Dirac nodes at the Fermi level. The Dirac states are protected against gap opening by a mirror plane in a manner analogous to graphene. The results suggest that further study of the electronic properties of Ca$_3$P$_2$ will be of interest

The X-Ray Properties of the Optically Brightest Mini-BAL Quasars from the Sloan Digital Sky Survey

We have compiled a sample of 14 of the optically brightest radio-quiet quasars ($m_{i}$~$\le$~17.5 and $z$~$\ge$~1.9) in the Sloan Digital Sky Survey Data Release 5 quasar catalog that have C IV mini-BALs present in their spectra. X-ray data for 12 of the objects were obtained via a Chandra snapshot survey using ACIS-S, while data for the other two quasars were obtained from archival XMM-Newton observations. Joint X-ray spectral analysis shows the mini-BAL quasars have a similar average power-law photon index ($\Gamma\approx1.9$) and level of intrinsic absorption ($N_H \lesssim 8\times 10^{21} \ {\rm cm}^{-2}$) as non-BMB (neither BAL nor mini-BAL) quasars. Mini-BAL quasars are more similar to non-BMB quasars than to BAL quasars in their distribution of relative X-ray brightness (assessed with $\Delta\alpha_{\rm ox}$). Relative colors indicate mild dust reddening in the optical spectra of mini-BAL quasars. Significant correlations between $\Delta\alpha_{\rm ox}$ and UV absorption properties are confirmed for a sample of 56 sources combining mini-BAL and BAL quasars with high signal-to-noise ratio rest-frame UV spectra, which generally supports models in which X-ray absorption is important in enabling driving of the UV absorption-line wind. We also propose alternative parametrizations of the UV absorption properties of mini-BAL and BAL quasars, which may better describe the broad absorption troughs in some respects.Comment: ApJ accepted; 21 pages, 11 figures, and 9 table