Fossil insects from the Middle Ecca (Lower permian) of southern Africa

Main articleThree insects are recorded from carbonaceous shales of Middle Ecca age from Hammanskraal, near Pretoria. Thaumalophora pranotalis gen. et sp. nov., is an aquatic nymph of the Paraplecoptera showing lateral abdominal gills. Sysciophlebia kovacsae sp. nov. is a tegmen of a spiloblattinid cockroach. The third specimen is a small protopsyllidiid nymph. Only three insects of greater age are known from southern Africa.Non

A FOSSIL INSECT FROM THE DWYKA SERIES OF RHODESIA

Hadenlomoides dwykensis, gen. et sp. nov. (Paraplecoptera: Hadentomidael is the oldest recorded insect in the southern hemisphere. It is similar to Hadenlomum americanum from the Upper Carboniferous of North America. The close relationship between these two species tends to support the view that at least part of the Dwyka Series extends below the Permian into the Upper Carboniferous

An unusual mayfly (Insecta: Ephemeroptera) from the Triassic of South Africa

Main articleAn unusual mayfly from the Upper Triassic near Dordrecht in the Cape Province of South Africa is described as Xenophlebia optata gen. et sp. nov., and is ascribed to a new family, the Xenophlebiidae, as its sole representative.Non

UPPER TRIASSIC INSECTS FROM THE MOLTENO "FORMATION", SOUTH AFRICA.

Insects are recorded from eight plant fossil localities in the Molteno "Formation", but only heavily sclerotized species (Blattodea and Coleoptera) have been obtained from six of them. A small mecopteron was found at another locality, and only at Birds River, near Dordrecht, has a more diverse fauna, with representatives of the Orthoptera, ?Mantodea, Blattodea, Homoptera and Megaloptera, been obtained. The known fauna is closely comparable with the Triassic faunas of Australia. Thirteen species, nine of which are described as new, are recorded from the Molteno. Six of the new species, and one described species, are referred to Hagla, Mesorthopteron, Triassoblatta, Dysmorphoptiloides and Ademosyne, genera represented in or previously restricted to the Australian Triassic faunas. The new monotypic genera, Prosbolomorpha (type species clara: Homoptera) and Afristella (type species delicatula: Mecoptera), are similar to genera recorded from the Triassic of Australia. Euchauliodes distinctus, gen. et sp. nov., is the earliest known Corydaloidean wing (Megaloptera); it is referred to a new family

Renormalization of a gapless Hartree-Fock approximation to a theory with spontaneously broken O(N)-symmetry

The renormalization of a gapless Phi-derivable Hartree--Fock approximation to the O(N)-symmetric lambda*phi^4 theory is considered in the spontaneously broken phase. This kind of approach was proposed by three of us in a previous paper in order to preserve all the desirable features of Phi-derivable Dyson-Schwinger resummation schemes (i.e., validity of conservation laws and thermodynamic consistency) while simultaneously restoring the Nambu--Goldstone theorem in the broken phase. It is shown that unlike for the conventional Hartree--Fock approximation this approach allows for a scale-independent renormalization in the vacuum. However, the scale dependence still persists at finite temperatures. Various branches of the solution are studied. The occurrence of a limiting temperature inherent in the renormalized Hartree--Fock approximation at fixed renormalization scale mu is discussed.Comment: 11 pages, 14 figures / Version accepted by Phys. Rev. D: title and one reference change

Gapless Hartree-Fock Resummation Scheme for the O(N) Model

A modified selfconsistent Hartree-Fock approximation to the lambda*phi^4 theory with spontaneously broken O(N) symmetry is proposed. It preserves all the desirable features, like conservation laws and thermodynamic consistency, of the selfconsistent Dyson scheme generated from a 2PI functional, also known as the Phi-derivable scheme, while simultaneously respecting the Nambu-Goldstone theorem in the chiral-symmetry broken phase. Various approximate resummation schemes are discussed.Comment: 13 pages, 10 figures / Version accepted by Phys. Rev. D: the introduction has been expanded by a few remarks in order to further clarify the goal of the pape

Quark Recombination and Heavy Quark Diffusion in Hot Nuclear Matter

We discuss resonance recombination for quarks and show that it is compatible with quark and hadron distributions in local thermal equilibrium. We then calculate realistic heavy quark phase space distributions in heavy ion collisions using Langevin simulations with non-perturbative T-matrix interactions in hydrodynamic backgrounds. We hadronize the heavy quarks on the critical hypersurface given by hydrodynamics after constructing a criterion for the relative recombination and fragmentation contributions. We discuss the influence of recombination and flow on the resulting heavy meson and single electron R_AA and elliptic flow. We will also comment on the effect of diffusion of open heavy flavor mesons in the hadronic phase.Comment: Contribution to Quark Matter 2011, submitted to J.Phys.G; 4 pages, 5 figure

Quarkonia and Heavy-Quark Relaxation Times in the Quark-Gluon Plasma

A thermodynamic T-matrix approach for elastic 2-body interactions is employed to calculate spectral functions of open and hidden heavy-quark systems in the Quark-Gluon Plasma. This enables the evaluation of quarkonium bound-state properties and heavy-quark diffusion on a common basis and thus to obtain mutual constraints. The two-body interaction kernel is approximated within a potential picture for spacelike momentum transfers. An effective field-theoretical model combining color-Coulomb and confining terms is implemented with relativistic corrections and for different color channels. Four pertinent model parameters, characterizing the coupling strengths and screening, are adjusted to reproduce the color-average heavy-quark free energy as computed in thermal lattice QCD. The approach is tested against vacuum spectroscopy in the open (D, B) and hidden (Psi and Upsilon) flavor sectors, as well as in the high-energy limit of elastic perturbative QCD scattering. Theoretical uncertainties in the static reduction scheme of the 4-dimensional Bethe-Salpeter equation are elucidated. The quarkonium spectral functions are used to calculate Euclidean correlators which are discussed in light of lattice QCD results, while heavy-quark relaxation rates and diffusion coefficients are extracted utilizing a Fokker-Planck equation.Comment: 33 pages, 28 figure