Marron, more than a meal. Harvey River restoration, Western Australia

The Southwestern Province has the highest proportion of endemic fishes and crayfishes on the continent, and is a globally recognosed endemic hospot. Over the last few decades, there has been a growing body of evidence that has suggested that the inland aquatic fauna of the Southwestern Province of Western Australia is declining. Much of this decline has been driven by large scale modification to habitat quality and quantity. The loss of suitable habitats through stream channelisation, river regulation, land clearing, flood abatement and the impact of introduced species, has resulted in large-scale losses of aquatic fauna. This, coupled with the increasing impact of climate change driven reductions in rainfall and subsequent run-off and aquifer recharge continue to challenge the aquatic fauna and necessitates adaptive management to help with their conservation. Since the turn of the Century, five of the region’s freshwater fish species, four freshwater crayfish species and the sole species of freshwater mussel have been listed as threatened under the Federal Government’s Environment and Biodiversity Conservation Act (EPBC Act 1999). Other species are variously listed under State legislation. Surprisingly, in 2013, the significant discovery of a previously undetected fish species was made, and since that time, several other species have been discovered in the region, but await formal description. The Marron (Cherax cainii) is recognised as a south-western Australian aquatic icon, not only for the important and unique recreational fishery that it supports, but also for its aquaculture potential and the sheer size to which it attains; while also being considered a delicacy and a biological indicator of ecosystem health. The Marron, More than a Meal Project aims to demonstrate how the restoration of drainage channels can lead to an improvement of the aquatic ecosystems

Search for 3p-3h States in the A=12 and 16 Systems with the (6-Li,t) and (6-Li,3-He) Reaction

Supported by the National Science Foundation and Indiana Universit

Search for 3p-3h States in the A=16 System

This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit

Anderson-Yuval approach to the multichannel Kondo problem

We analyze the structure of the perturbation expansion of the general multichannel Kondo model with channel anisotropic exchange couplings and in the presence of an external magnetic field, generalizing to this case the Anderson-Yuval technique. For two channels, we are able to map the Kondo model onto a generalized resonant level model. Limiting cases in which the equivalent resonant level model is solvable are identified. The solution correctly captures the properties of the two channel Kondo model, and also allows an analytic description of the cross-over from the non Fermi liquid to the Fermi liquid behavior caused by the channel anisotropy.Comment: 23 pages, ReVTeX, 4 figures av. on reques

Charging effects in quantum wires

We investigate the role of charging effects in a voltage-biased quantum wire. Both the finite range of the Coulomb interaction and the long-ranged nature of the Friedel oscillation imply a finite capacitance, leading to a charging energy. While observable Coulomb blockade effects are absent for a single impurity, they are crucial if islands are present. For a double barrier, we give the resonance condition, fully taking into account the charging of the island.Comment: 6 Pages RevTeX, no figures, Phys. Rev. B (in press

Conductance renormalization and conductivity of a multi-subband Tomonaga-Luttinger model

We studied the conductance renormalization and conductivity of multi-subband Tomonaga-Luttinger models with inter-subband interactions. We found that, as in single-band systems, the conductance of a multi-subband system with an arbitrary number of subbands is not renormalized due to interaction between electrons. We derived a formula for the conductivity in multi-subband models. We applied it to a simplified case and found that inter-subband interaction enhances the conductivity, which is contrary to the intra-subband repulsive interaction, and that the conductivity is further enhanced for a larger number of subbands.Comment: 12 pages, no figures. to be published in Physical Review B as a brief repor

Nonequilibrium Transport through a Kondo Dot in a Magnetic Field: Perturbation Theory

Using nonequilibrium perturbation theory, we investigate the nonlinear transport through a quantum dot in the Kondo regime in the presence of a magnetic field. We calculate the leading logarithmic corrections to the local magnetization and the differential conductance, which are characteristic of the Kondo effect out of equilibrium. By solving a quantum Boltzmann equation, we determine the nonequilibrium magnetization on the dot and show that the application of both a finite bias voltage and a magnetic field induces a novel structure of logarithmic corrections not present in equilibrium. These corrections lead to more pronounced features in the conductance, and their form calls for a modification of the perturbative renormalization group.Comment: 16 pages, 7 figure

Spin Susceptibility in Underdoped YBa2Cu3O6+x\bf YBa_2Cu_3O_{6+x}

We report a comprehensive polarized and unpolarized neutron scattering study of the evolution of the dynamical spin susceptibility with temperature and doping in three underdoped single crystals of the \YBCO{6+x} high temperature superconductor: \YBCO{6.5} (Tc = 52 K), \YBCO{6.7} (Tc = 67 K), and \YBCO{6.85} (T_c = 87 K). Theoretical implications of these data are discussed, and a critique of recent attempts to relate the spin excitations to the thermodynamics of high temperature superconductors is given.Comment: minor revisions, to appear in PR

Transport properties of strongly correlated metals:a dynamical mean-field approach

The temperature dependence of the transport properties of the metallic phase of a frustrated Hubbard model on the hypercubic lattice at half-filling are calculated. Dynamical mean-field theory, which maps the Hubbard model onto a single impurity Anderson model that is solved self-consistently, and becomes exact in the limit of large dimensionality, is used. As the temperature increases there is a smooth crossover from coherent Fermi liquid excitations at low temperatures to incoherent excitations at high temperatures. This crossover leads to a non-monotonic temperature dependence for the resistance, thermopower, and Hall coefficient, unlike in conventional metals. The resistance smoothly increases from a quadratic temperature dependence at low temperatures to large values which can exceed the Mott-Ioffe-Regel value, hbar a/e^2 (where "a" is a lattice constant) associated with mean-free paths less than a lattice constant. Further signatures of the thermal destruction of quasiparticle excitations are a peak in the thermopower and the absence of a Drude peak in the optical conductivity. The results presented here are relevant to a wide range of strongly correlated metals, including transition metal oxides, strontium ruthenates, and organic metals.Comment: 19 pages, 9 eps figure

Competing orders in a magnetic field: spin and charge order in the cuprate superconductors

We describe two-dimensional quantum spin fluctuations in a superconducting Abrikosov flux lattice induced by a magnetic field applied to a doped Mott insulator. Complete numerical solutions of a self-consistent large N theory provide detailed information on the phase diagram and on the spatial structure of the dynamic spin spectrum. Our results apply to phases with and without long-range spin density wave order and to the magnetic quantum critical point separating these phases. We discuss the relationship of our results to a number of recent neutron scattering measurements on the cuprate superconductors in the presence of an applied field. We compute the pinning of static charge order by the vortex cores in the `spin gap' phase where the spin order remains dynamically fluctuating, and argue that these results apply to recent scanning tunnelling microscopy (STM) measurements. We show that with a single typical set of values for the coupling constants, our model describes the field dependence of the elastic neutron scattering intensities, the absence of satellite Bragg peaks associated with the vortex lattice in existing neutron scattering observations, and the spatial extent of charge order in STM observations. We mention implications of our theory for NMR experiments. We also present a theoretical discussion of more exotic states that can be built out of the spin and charge order parameters, including spin nematics and phases with `exciton fractionalization'.Comment: 36 pages, 33 figures; for a popular introduction, see http://onsager.physics.yale.edu/superflow.html; (v2) Added reference to new work of Chen and Ting; (v3) reorganized presentation for improved clarity, and added new appendix on microscopic origin; (v4) final published version with minor change