THYMELICUS LINEOLA (LEPIDOPTERA: HESPERIIDAE) AND ITS PARASITES IN EUROPE

The distribution, ecology, and host-plants of the European skipper, Thymelicus lineola (Ochs.), are described, and notes given on its biology and abundance in continental Europe. Agricultural practices are responsible for its virtual absence from hay-fields; however, even in undisturbed wild host-plant communities, it is never abundant, and has never required control measures as in Canada. Parasites of T. lineola are listed, with notes on their life-histories, distribution, host spectra, relative abundance, annual fluctuations, and interpopulation variations. Parasites reared were Phryxe vulgaris Fall., Thecocarcelia incedens Rond, (both attacking larvae, but sometimes emerging after host pupation), Rogas tristis Wesm. (larval parasite), Labrorychus delarvatus Grav. (larval-pupal parasite), Stenichneumon scutellator Grav. and Brachymeria intermedia Nees (pupal parasites); an undetermined mermithid was reared from larvae and also once from an adult S. scutellator. Rogas tristis was attacked by the hyperparasite Mesochorus macrurus Thoms., and S. scutellator by Gelis cursitans F. Potentialities of the more important species for biological control of T. lineola in Canada are discussed. S. scutellator, which is well synchronized with the host, regularly parasitizes 30-50% of pupae and is the most promising natural enemy for introduction, although in Canada it will compete with the native Itoplectis conquisitor (Say). R. tristis (3-57% parasitism) and P. vulgaris (8-44%), with high constancy in Europe, might be considered for introduction to Canada because of the absence there of effective native larval parasites. T. incedens, although probably a specific hesperiid parasite, is uncommon (usually 1-5% parasitism) and has low constancy in central Europe. All other species encountered are rare on T. lineola. Comparison of parasite complexes in Europe and Canada, where the host has acquired 22 natural enemies, shows that four genera are represented in both areas; of three holarctic species two have been found associated with T. lineola only in Canada, and one only in Europ

Effective Operator Treatment of the Anharmonic Oscillator

We analyse the one dimensional quartic oscillator using the effective operator methodology of Lee and Suzuki. We reproduce known results for low lying energy eigenvalues.Comment: 9 Pages, Extended version with new references. To appear in Phys.ReV.

Geometry of PT-symmetric quantum mechanics

Recently, much research has been carried out on Hamiltonians that are not Hermitian but are symmetric under space-time reflection, that is, Hamiltonians that exhibit PT symmetry. Investigations of the Sturm-Liouville eigenvalue problem associated with such Hamiltonians have shown that in many cases the entire energy spectrum is real and positive and that the eigenfunctions form an orthogonal and complete basis. Furthermore, the quantum theories determined by such Hamiltonians have been shown to be consistent in the sense that the probabilities are positive and the dynamical trajectories are unitary. However, the geometrical structures that underlie quantum theories formulated in terms of such Hamiltonians have hitherto not been fully understood. This paper studies in detail the geometric properties of a Hilbert space endowed with a parity structure and analyses the characteristics of a PT-symmetric Hamiltonian and its eigenstates. A canonical relationship between a PT-symmetric operator and a Hermitian operator is established. It is shown that the quadratic form corresponding to the parity operator, in particular, gives rise to a natural partition of the Hilbert space into two halves corresponding to states having positive and negative PT norm. The indefiniteness of the norm can be circumvented by introducing a symmetry operator C that defines a positive definite inner product by means of a CPT conjugation operation.Comment: 22 Page

Transmission and Reflection in the Stadium Billiard: Time-dependent asymmetric transport

We investigate the transmission and reflection survival probabilities for the chaotic stadium billiard with two holes placed asymmetrically. Classically, these distributions are shown to have algebraic or exponential decays depending on the choice of injecting hole and exact expressions are given for the first time and confirmed numerically. As there is no reported quantum theoretical or experimental analogue we propose a model for experimental observation of the asymmetric transport using semiconductor nano-structures and comment on the relevant quantum time-scales.Comment: 4 pages, 4 figure

The Multi-Component Nature of the Vela Pulsar Nonthermal X-ray Spectrum

We report on our analysis of a 274 ks observation of the Vela pulsar with the Rossi X-Ray Timing Explorer (RXTE). The double-peaked, pulsed emission at 2 - 30 keV, which we had previously detected during a 93 ks observation, is confirmed with much improved statistics. There is now clear evidence, both in the spectrum and the light curve, that the emission in the RXTE band is a blend of two separate non-thermal components. The spectrum of the harder component connects smoothly with the OSSE, COMPTEL and EGRET spectrum and the peaks in the light curve are in phase coincidence with those of the high-energy light curve. The spectrum of the softer component is consistent with an extrapolation to the pulsed optical flux, and the second RXTE pulse is in phase coincidence with the second optical peak. In addition, we see a peak in the 2-8 keV RXTE pulse profile at the radio phase.Comment: 12 pages, 3 figures, accepted for publication in Astrophysical Journa

Methanation of CO over Ni catalyst: A theoretical study

Theoretical methods (generalized valence‐bond calculations) were used to examine the bond energies and geometries of numerous species chemisorbed onto Ni clusters representing Ni surface. These results were used to obtain thermochemical information and to examine various mechanisms for the methanation of CO over Ni: CO+3H^(→)_(2(Ni)) CH_4+H_2O. It is found that chemisorbed formyl radicals (Ni–CHO) lead to a favorably appearing chain reaction that is consistent with current experimental results. In addition, we find a chemisorbed C_2 species that may be the catalytically active C_(ad) formed from dissociation of CO