Mixtures of Bose gases confined in concentrically coupled annular traps

A two-component Bose-Einstein condensate confined in an axially-symmetric potential with two local minima, resembling two concentric annular traps, is investigated. The system shows a number of quantum phase transitions that result from the competition between phase coexistence, and radial/azimuthal phase separation. The ground-state phase diagram, as well as the rotational properties, including the (meta)stability of currents in this system, are analysed.Comment: 6 pages, 5 figures, minor revision

Randomly Diluted e_g Orbital-Ordered Systems

Dilution effects on the long-range ordered state of the doubly degenerate $e_g$ orbital are investigated. Quenched impurities without the orbital degree of freedom are introduced in the orbital model where the long-range order is realized by the order-from-disorder mechanism. It is shown by the Monte-Carlo simulation and the cluster-expansion method that a decrease in the orbital ordering temperature by dilution is remarkable in comparison with that in the randomly diluted spin models. Tiltings of orbitals around impurity cause this unique dilution effects on the orbital systems. The present theory provides a new view point for the recent experiments in KCu$_{1-x}$Zn$_x$F$_3$.Comment: 4 pages, 4 figure

Simple versus cooperative relaxations in complex correlated systems

A method for investigating the nature of thermally activated relaxations in terms of their cooperative character is tested in both polymer and low molecular weight crystal systems. This approach is based on analysis of the activation entropy in order to describe thermally activated relaxations. The betaine arsenate/phosphate mixed system of low molecular weight crystals was selected for investigation because pure compounds of this system show ferro-/antiferroelectric phase transitions and the mixed crystals undergo different kinds of relaxation processes involving both dipole-dipole and dipole-lattice interactions. The polymer chosen was a side chain liquid-crystalline polysiloxane, which shows the beta -relaxation characteristic of disordered systems and amorphous materials. The cooperative versus local character of the relaxations is described in terms of "complex'' and ''simple'' relaxations based on calculations of the activation entropies. The initial assumptions of the theory, as well as the resulting equations, were found to be applicable to the systems studied

AdS3 Gravitational Instantons from Conformal Field Theory

A conformal field theory on the boundary of three-dimensional asymptotic anti-de Sitter spaces which appear as near horizon geometry of D-brane bound states is discussed. It is shown that partition functions of gravitational instantons appear as high and low temperature limits of the partition function of the conformal field theory. The result reproduces phase transition between the anti-de Sitter space and the BTZ black hole in the bulk gravity.Comment: 22 pages, minor correction

Final report: Second generation waste package design study

The objectives of this project activity are: to review the current YMP baseline environment and establish corrosion test environments representative of the range of dry to intermittently wet conditions expected in the drifts as a function of time. to demonstrate the oxidation and corrosion resistance of A588 weathering steel and reference Alloy 22 samples in the representative dry to intermittently dry conditions. to evaluate backfill and design features to improve the thermal performance analyses of the proposed second-generation waste packages using existing models developed at UNR

Charged black holes: Wave equations for gravitational and electromagnetic perturbations

A pair of wave equations for the electromagnetic and gravitational perturbations of the charged Kerr black hole are derived. The perturbed Einstein-Maxwell equations in a new gauge are employed in the derivation. The wave equations refer to the perturbed Maxwell spinor $\Phi_0$ and to the shear $\sigma$ of a principal null direction of the Weyl curvature. The whole construction rests on the tripod of three distinct derivatives of the first curvature $\kappa$ of a principal null direction.Comment: 12 pages, to appear in Ap.

An Economic Analysis of Swaziland’s Cotton Pricing and Marketing Policies for Smallholder Farmers in Marginal Rainfall Areas

An AEE Working Paper on cotton pricing and marketing for small holder farmers in Swaziland low rainfall areas.Cotton is the main source of income for rural households in the smallholder-farming sector and provides employment at rural and national level. Despite the vital role played by cotton, production has declined since 1991. The main objective of the study was to identify the country's competitiveness and comparative advantage in cotton production. In addition the study highlights the factors affecting cotton profitability. The world market was used to assess Swaziland's comparative advantage in producing cotton because of the on-going reforms in the SADC market. Smallholder farmers in kaKhuphuka have a DRC of 1.2 indicating that they would not be efficient competing on the world market. However, access to the Republic of South Africa results in higher prices and a DRC of 0.98, indicating efficiency in cotton production. There was a marked difference in the productivity of low and high performing smallholders, high performers achieved DRCs of 0.98 at world market prices and 0.87 at RSA prices. Factors such as fertiliser application rate, area under cotton production, level of education, farming experience and pesticide use were important than credit in affecting yield, although credit was also significant at p=0.05. Low performing credit farmers are making negative profits and apparent irrational producing cotton. The study revealed that, if low performing farmers increase yields by 13% in order that they will be profitable at the rural daily labour wage rate. Alternatively low-performers are considered rational to continue producing cotton if one assumes that the opportunity cost of labour is 44% lower at E 4.50 per man day. Improvement of technology through research and extension is critical in increasing farmers'yields and subsequently both profits and Swaziland's competitiveness in cotton production