Phenomenological Transport Equation for the Cuprate Metals

We observe that the appearance of two transport relaxation times in the various transport coefficients of cuprate metals may be understood in terms of scattering processes that discriminate between currents that are even, or odd under the charge conjugation operator. We develop a transport equation that illustrates these ideas and discuss its experimental and theoretical consequences.Comment: Replaced with journal ref. Latex+ p

Heliothis dispersal and migration

A few of the many species of Heliothis (Lepidoptera, Noctuidae) are important crop pests in the Old and New Worlds. Among these, H.armigera, H.zea, H.virescens and H.punctigera are the best known. The former is a particularly destructive species of a wide range of crops cultivated in Africa, the Middle East and Asia, including several staple foods and important peasant farmer cash crops. As new cultivation techniques are introduced and more extensive areas of crops are grown, often on larger irrigation and Government development schemes, it appears that this pest is becoming increasingly important. There is a strong suspicion that H.armigera populations move locally between crops grown in sequence or intercropped and that probably more extensive migratory movement occurs, as has been demonstrated in the closely related species H. zea in North America. This has considerable implications for effective control of the pest on the crops of some of the least priviledged farmers of the Developing World and in some of the poorest countries. There are recorded instances of resistance to pesticides in the species. Clearly large scale movements could have an effect on dissemination of such resistance and affect the level of control exerted by local parasite and predator populations and hence the necessity for rapid control action to combat rapid population increases of the pest on both staple food and cash crops. The ability to forecast or warn of such incidents would assist in effective timing of control operations and maximise efficiency of any insecticidal input required. This bibliography consolidates much of the scattered literature on the migratory behaviour of Heliothis spp. and will help to identify gaps in the existing knowledge of this aspect of the ecology of the genus. It will hopefully assist in focussing attention on the necessity for work on H.armigera, which is of such great importance in Developing Countries. Work on migratory movement could lead to effective action both regionally and internationally to reduce possibilities of migration of damaging numbers of moths. It will certainly assist in increasing knowledge on the bionomics of one of the most damaging agricultural pest species in the Old World and be of benefit to some of the least advantaged farmers of the tropics

Analysis of the Dynamics of Liquid Aluminium: Recurrent Relation Approach

By use of the recurrent relation approach (RRA) we study the microscopic dynamics of liquid aluminium at T=973 K and develop a theoretical model which satisfies all the corresponding sum rules. The investigation covers the inelastic features as well as the crossover of our theory into the hydrodynamical and the free-particle regimes. A comparison between our theoretical results with those following from a generalized hydrodynamical approach is also presented. In addition to this we report the results of our molecular dynamics simulations for liquid aluminium, which are also discussed and compared to experimental data. The received results reveal that (i) the microscopical dynamics of density fluctuations is defined mainly by the first four even frequency moments of the dynamic structure factor, and (ii) the inherent relation of the high-frequency collective excitations observed in experimental spectra of dynamic structure factor $S(k,\omega)$ with the two-, three- and four-particle correlations.Comment: 11 pages, 4 figure

Efficient algorithms for rigid body integration using optimized splitting methods and exact free rotational motion

Hamiltonian splitting methods are an established technique to derive stable and accurate integration schemes in molecular dynamics, in which additional accuracy can be gained using force gradients. For rigid bodies, a tradition exists in the literature to further split up the kinetic part of the Hamiltonian, which lowers the accuracy. The goal of this note is to comment on the best combination of optimized splitting and gradient methods that avoids splitting the kinetic energy. These schemes are generally applicable, but the optimal scheme depends on the desired level of accuracy. For simulations of liquid water it is found that the velocity Verlet scheme is only optimal for crude simulations with accuracies larger than 1.5%, while surprisingly a modified Verlet scheme (HOA) is optimal up to accuracies of 0.4% and a fourth order gradient scheme (GIER4) is optimal for even higher accuracies.Comment: 2 pages, 1 figure. Added clarifying comments. Accepted for publication in the Journal of Chemical Physic

Illustrative components of the geological environment

In this chapter we provide an account of the contribution made by the Geosphere, in particular bedrock geological materials (part of the lithosphere), groundwater and hydrochemistry to the development of a GDF. In order to put this in context we provide a brief account of the general requirements of these attributes, particularly in respect of the post closure safety and, to a lesser extent, the construction phase of the GDF. We also provide a brief summary of the international approach to using bedrock geological materials and go on to describe the summary properties from a range of bedrock geological materials (lithologies and formations) in England, Wales and Northern Ireland, illustrated from well-documented examples

Quantum free energy differences from non-equilibrium path integrals: I. Methods and numerical application

The imaginary-time path integral representation of the canonical partition function of a quantum system and non-equilibrium work fluctuation relations are combined to yield methods for computing free energy differences in quantum systems using non-equilibrium processes. The path integral representation is isomorphic to the configurational partition function of a classical field theory, to which a natural but fictitious Hamiltonian dynamics is associated. It is shown that if this system is prepared in an equilibrium state, after which a control parameter in the fictitious Hamiltonian is changed in a finite time, then formally the Jarzynski non-equilibrium work relation and the Crooks fluctuation relation are shown to hold, where work is defined as the change in the energy as given by the fictitious Hamiltonian. Since the energy diverges for the classical field theory in canonical equilibrium, two regularization methods are introduced which limit the number of degrees of freedom to be finite. The numerical applicability of the methods is demonstrated for a quartic double-well potential with varying asymmetry. A general parameter-free smoothing procedure for the work distribution functions is useful in this context.Comment: 20 pages, 4 figures. Added clarifying remarks and fixed typo

How should we interpret the two transport relaxation times in the cuprates ?

We observe that the appearance of two transport relaxation times in the various transport coefficients of cuprate metals may be understood in terms of scattering processes that discriminate between currents that are even, or odd under the charge conjugation operator. We develop a transport equation that illustrates these ideas and discuss its experimental and theoretical consequences.Comment: 19 pages, RevTeX with 8 postscript figures included. To appear in ``Non Fermi Liquid Physics'', J. Phys:Cond. Matt. (1997