Slow equivariant lump dynamics on the two sphere

The low-energy, rotationally equivariant dynamics of n CP^1 lumps on S^2 is studied within the approximation of geodesic motion in the moduli space of static solutions. The volume and curvature properties of this moduli space are computed. By lifting the geodesic flow to the completion of an n-fold cover of the moduli space, a good understanding of nearly singular lump dynamics within this approximation is obtained.Comment: 12 pages, 3 figure

Magnetic bubble refraction and quasibreathers in inhomogeneous antiferromagnets

The dynamics of magnetic bubble solitons in a two-dimensional isotropic antiferromagnetic spin lattice is studied, in the case where the exchange integral J(x,y) is position dependent. In the near continuum regime, this system is described by the relativistic O(3) sigma model on a spacetime with a spatially inhomogeneous metric, determined by J. The geodesic approximation is used to describe low energy soliton dynamics in this system: n-soliton motion is approximated by geodesic motion in the moduli space of static n-solitons, equipped with the L^2 metric. Explicit formulae for this metric for various natural choices of J(x,y) are obtained. From these it is shown that single soliton trajectories experience refraction, with 1/J analogous to the refractive index, and that this refraction effect allows the construction of simple bubble lenses and bubble guides. The case where J has a disk inhomogeneity (taking the value J_1 outside a disk, and J_2<J_1 inside) is considered in detail. It is argued that, for sufficiently large J_1/J_2 this type of antiferromagnet supports approximate quasibreathers: two or more coincident bubbles confined within the disk which spin internally while their shape undergoes periodic oscillations with a generically incommensurate period.Comment: Conference proceedings paper for talk given at Nonlinear Physics Theory and Experiment IV, Gallipoli, Italy, June 200

Terrestrial laser scanning: an operational tool for fuel hazard mapping?

Fuel hazard estimates are vital for the prediction of fire behaviour and planning fuel treatment activities. Previous literature has highlighted the potential of Terrestrial Laser Scanning (TLS) to be used to assess fuel properties. However, operational uptake of these systems has been limited due to a lack of a sampling approach that balances efficiency and data efficacy. This study aims to assess whether an operational approach utilising Terrestrial Laser Scanning (TLS) to capture fuel information over an area commensurate with current fuel hazard assessment protocols implemented in South-Eastern Australia is feasible. TLS data were captured over various plots in South-Eastern Australia, utilising both low- and high-cost TLS sensors. Results indicate that both scanners provided similar overall representation of the ground, vertical distribution of vegetation and fuel hazard estimates. The analysis of fuel information contained within individual scans clipped to 4 m showed similar results to that of the fully co-registered plot (cover estimates of near-surface vegetation were within 10%, elevated vegetation within 15%, and height estimates of near-surface and elevated strata within 0.05 cm). This study recommends that, to capture a plot in an operational environment (balancing efficiency and data completeness), a sufficient number of non-overlapping individual scans can provide reliable estimates of fuel information at the near-surface and elevated strata, without the need for co-registration in the case study environments. The use of TLS within the rigid structure provided by current fuel observation protocols provides incremental benefit to the measurement of fuel hazard. Future research should leverage the full capability of TLS data and combine it with moisture estimates to gain a full realisation of the fuel hazard

Quantum lump dynamics on the two-sphere

It is well known that the low-energy classical dynamics of solitons of Bogomol'nyi type is well approximated by geodesic motion in M_n, the moduli space of static n-solitons. There is an obvious quantization of this dynamics wherein the wavefunction evolves according to the Hamiltonian H_0 equal to (half) the Laplacian on M_n. Born-Oppenheimer reduction of analogous mechanical systems suggests, however, that this simple Hamiltonian should receive corrections including k, the scalar curvature of M_n, and C, the n-soliton Casimir energy, which are usually difficult to compute, and whose effect on the energy spectrum is unknown. This paper analyzes the spectra of H_0 and two corrections to it suggested by work of Moss and Shiiki, namely H_1=H_0+k/4 and H_2=H_1+C, in the simple but nontrivial case of a single CP^1 lump moving on the two-sphere. Here M_1=TSO(3), a noncompact kaehler 6-manifold invariant under an SO(3)xSO(3) action, whose geometry is well understood. The symmetry gives rise to two conserved angular momenta, spin and isospin. A hidden isometry of M_1 is found which implies that all three energy spectra are symmetric under spin-isospin interchange. The Casimir energy is found exactly on the zero section of TSO(3), and approximated numerically on the rest of M_1. The lowest 19 eigenvalues of H_i are found for i=0,1,2, and their spin-isospin and parity compared. The curvature corrections in H_1 lead to a qualitatively unchanged low-level spectrum while the Casimir energy in H_2 leads to significant changes. The scaling behaviour of the spectra under changes in the radii of the domain and target spheres is analyzed, and it is found that the disparity between the spectra of H_1 and H_2 is reduced when the target sphere is made smaller.Comment: 35 pages, 3 figure

On the RIP: using Relative Impact Potential to assess the ecological impacts of invasive alien species

Invasive alien species continue to arrive in new locations with no abatement in rate, and thus greater predictive powers surrounding their ecological impacts are required. In particular, we need improved means of quantifying the ecological impacts of new invasive species under different contexts. Here, we develop a suite of metrics based upon the novel Relative Impact Potential (RIP) metric, combining the functional response (consumer per capita effect), with proxies for the numerical response (consumer population response), providing quantification of invasive species ecological impact. These metrics are comparative in relation to the eco-evolutionary baseline of trophically analogous natives, as well as other invasive species and across multiple populations. Crucially, the metrics also reveal how impacts of invasive species change under abiotic and biotic contexts. While studies focused solely on functional responses have been successful in predictive invasion ecology, RIP retains these advantages while adding vital other predictive elements, principally consumer abundance. RIP can also be combined with propagule pressure to quantify overall invasion risk. By highlighting functional response and numerical response proxies, we outline a user-friendly method for assessing the impacts of invaders of all trophic levels and taxonomic groups. We apply the metric to impact assessment in the face of climate change by taking account of both changing predator consumption rates and prey reproduction rates. We proceed to outline the application of RIP to assess biotic resistance against incoming invasive species, the effect of evolution on invasive species impacts, application to interspecific competition, changing spatio-temporal patterns of invasion, and how RIP can inform biological control. We propose that RIP provides scientists and practitioners with a user-friendly, customisable and, crucially, powerful technique to inform invasive species policy and management

Climate change challenges for central banks and financial regulators

The academic and policy debate regarding the role of central banks and financial regulators in addressing climate-related financial risks has rapidly expanded in recent years. This Perspective presents the key controversies and discusses potential research and policy avenues for the future. Developing a comprehensive analytical framework to assess the potential impact of climate change and the low-carbon transition on financial stability seems to be the first crucial challenge. These enhanced risk measures could then be incorporated in setting financial regulations and implementing the policies of central banks

Global Assessment Report on Disaster Risk Reduction 2019

The Global Assessment Report on Disaster Risk Reduction (GAR) is the flagship report of the United Nations on worldwide efforts to reduce disaster risk

Evolution of innovation policy in Emilia-Romagna and Valencia: Similar reality, similar results?

This is an author's accepted manuscript of an article published in: “European Planning Studies"; Volume 22, Issue 11, 2014; copyright Taylor & Francis; available online at: http://dx.doi.org/10.1080/09654313.2013.831398[EN] This paper examines the evolution of regional innovation policy in Emilia-Romagna and Valencia, two regions with similar economic features that implemented close innovation policies in the 1970s and 1980s. We investigate whether their similarities have led to parallel targets, policy tools and governance developments. We show that innovation policy in both regions suffered from the effects of privatization, budget constraints and changes to manufacturing during the 1990s and we highlight the consequences. Although Emilia-Romagna experienced deeper changes to its innovation policy, privatizations and/or the replacement of public funds promoted commercial approaches and induced market failures in both regions. The worst effects of these policies were the implementation of less-risky innovation projects, the shift towards extraregional projects and markets, and the favouring of large firms.López Estornell, M.; Barberá Tomás, JD.; Garcia Reche, A.; Mas Verdú, F. (2013). Evolution of innovation policy in Emilia-Romagna and Valencia: Similar reality, similar results?. European Planning Studies. 22(11):2287-2304. doi:10.1080/09654313.2013.831398S22872304221