Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 70

Deep-sea anglerfishes (Lophiiformes, Ceratioidei) of the familes Caulophrynidae, Melanocetidae, Himantolophidae, Diceratiidae, Oneirodidae, Thaumatichthyidae, Centrophrynidae, Ceratiidae, Gigantactinidae and Linophrynidae from southern Africa are reviewed since the publication of the book Smiths’ Sea Fishes (1986, 1991). Twenty-three new records of ceratioid anglerfishes are reported for the region, bringing the total to 32. No new taxa are described. The faunal area for southern African deep-sea fishes is expanded from that of Smiths’ Sea Fishes in order to include several literature records and recognize the broad distributions of these fishes through the deep-pelagic Atlantic/Indo-Pacific transit zone. Keys to all families, genera and species, as well as descriptions of all southern African specimens, are provided. The bulk of this material was collected during research cruises of South Africa’s RS AFRICANA and MEIRING NAUDE.Rhodes University Libraries (Digitisation

Identifying Priority Areas for Chronic Wasting Disease Surveillance in Montana

Chronic Wasting Disease is a fatal prion disease affecting ungulate species throughout North America.  As of 2013, no CWD positive deer have been found in the state of Montana, however, several surrounding states and provinces have identified multiple cases of the disease.  We used information on mule deer habitat selection, abundance, and locations of CWD cases in surrounding states to identify priority areas in Montana for CWD surveillance. The habitat selection models were based on over 10000 VHF and GPS locations collected from mule deer from 1975-2011, and predicted resource selection function (RSF) values for winter and summer in 5 of the 7 wildlife management regions in the state of Montana. We estimated mule deer density using the aerial survey counts weighted by the value of the RSF for each pixel. High priority areas were those that contained the highest densities of mule deer and were closest to locations with CWD positive deer. This information can be used to inform Montana’s CWD surveillance program for mule deer. We concluded that based on mule deer distribution and movement patterns several mule deer herds in Montana were at risk of coming into contact with deer from known infected herds

Siegert pseudostates: completeness and time evolution

Within the theory of Siegert pseudostates, it is possible to accurately calculate bound states and resonances. The energy continuum is replaced by a discrete set of states. Many questions of interest in scattering theory can be addressed within the framework of this formalism, thereby avoiding the need to treat the energy continuum. For practical calculations it is important to know whether a certain subset of Siegert pseudostates comprises a basis. This is a nontrivial issue, because of the unusual orthogonality and overcompleteness properties of Siegert pseudostates. Using analytical and numerical arguments, it is shown that the subset of bound states and outgoing Siegert pseudostates forms a basis. Time evolution in the context of Siegert pseudostates is also investigated. From the Mittag-Leffler expansion of the outgoing-wave Green's function, the time-dependent expansion of a wave packet in terms of Siegert pseudostates is derived. In this expression, all Siegert pseudostates--bound, antibound, outgoing, and incoming--are employed. Each of these evolves in time in a nonexponential fashion. Numerical tests underline the accuracy of the method

Localization of elastic waves in heterogeneous media with off-diagonal disorder and long-range correlations

Using the Martin-Siggia-Rose method, we study propagation of acoustic waves in strongly heterogeneous media which are characterized by a broad distribution of the elastic constants. Gaussian-white distributed elastic constants, as well as those with long-range correlations with non-decaying power-law correlation functions, are considered. The study is motivated in part by a recent discovery that the elastic moduli of rock at large length scales may be characterized by long-range power-law correlation functions. Depending on the disorder, the renormalization group (RG) flows exhibit a transition to localized regime in {\it any} dimension. We have numerically checked the RG results using the transfer-matrix method and direct numerical simulations for one- and two-dimensional systems, respectively.Comment: 5 pages, 4 figures, to appear in Phys. Rev. Let

Metal-insulator crossover in the Boson-Fermion model in infinite dimensions

The Boson-Fermion model, describing a mixture of tightly bound electron pairs and quasi-free electrons hybridized with each other via a charge exchange term, is studied in the limit of infinite dimensions, using the Non-Crossing Approximation within the Dynamical Mean Field Theory. It is shown that a metal-insulator crossover, driven by strong pair fluctuations, takes place as the temperature is lowered. It manifests itself in the opening of a pseudogap in the electron density of states, accompanied by a corresponding effect in the optical and dc conductivity.Comment: 4 pages, 3 figures, to be published in Phys. Rev. Let

An Einstein-Hilbert Action for Axi-Dilaton Gravity in 4-Dimensions

We examine the axi-dilatonic sector of low energy string theory and demonstrate how the gravitational interactions involving the axion and dilaton fields may be derived from a geometrical action principle involving the curvature scalar associated with a non-Riemannian connection. In this geometry the antisymmetric tensor 3-form field determines the torsion of the connection on the frame bundle while the gradient of the metric is determined by the dilaton field. By expressing the theory in terms of the Levi-Civita connection associated with the metric in the ``Einstein frame'' we confirm that the field equations derived from the non-Riemannian Einstein-Hilbert action coincide with the axi-dilaton sector of the low energy effective action derived from string theory.Comment: 6 pages Plain Tex (No Figures), Letter to Editor Classical and Quantum Gravit

A Cu2+ (S = 1/2) Kagom\'e Antiferromagnet: MgxCu4-x(OH)6Cl2

Spin-frustrated systems are one avenue for inducing macroscopic quantum states in materials. However, experimental realization of this goal has been difficult because of the lack of simple materials and, if available, the separation of the unusual magnetic properties arising from exotic magnetic states from behavior associated with chemical disorder, such as site mixing. Here we report the synthesis and magnetic properties of a new series of magnetically frustrated materials, MgxCu4-x(OH)6Cl2. Because of the substantially different ligand-field chemistry of Mg2+ and Cu2+, site disorder within the kagom\'e layers is minimized, as directly measured by X-ray diffraction. Our results reveal that many of the properties of these materials and related systems are not due to disorder of the magnetic lattice but rather reflect an unusual ground state.Comment: Accepted for publication in J. Am. Chem. Soc

Using a synthesis of the research literature related to the aetiology of adolescent idiopathic scoliosis to provide ideas on future directions for success

This review is atypical by design. It has used a synthesis of the available literature relating to the aetiology of AIS to draw attention to the lack of progress in this area despite intensive research for more than 100 years. The review has argued that if progress is to be made in this area then significant changes in approach to the problem must be made. Such changes have been outlined and major areas of potential focus identified with the intention of creating debate and discussion. There is no doubt that people are working hard in this area of research but this review has deliberately attempted to question its achievements and future directions