Au4V – Moment Stability and Spin Fluctuations in the Ordered Phase

Although neither gold nor vanadium generally possess a magnetic moment, the intermetallic compound Au4V is found to be ferromagnetic below 42K. In this paper we report the results of a muon spin relaxation study of the itinerant electron moment fluctuations in Au4V above the Curie temperature. The temperature dependence of the muon spin relaxation rate is found to be similar to that of the weak itinerant helimagnet, MnSi

The development of linked databases and environmental modelling systems for decision-making in London

A basic requirement for a city's growth is the availability of land, raw material and water. For continued and sustainable development of today’s cities we must be able to meet these basic requirements whilst being mindful of the environment and its relationship with anthropogenic activity. The heterogeneous and complex nature of urban systems where there are obvious environmental and anthropogenic inter-dependencies necessitates a more holistic approach to decision-making. New developments such as linked databases of environmental data and integrated environmental modelling systems provide new ways of organising cross-disciplinary information and a means to apply this to explain, explore and predict the urban systems response to environmental change. In this paper we show how, accessibility to linked databases, detailed understanding of the geology and integrated environmental modelling solutions has the potential to provide decision-makers and policy developers with the science based information needed to understand and address these challenges

From geological complexity to hydrogeological understanding using an integrated 3D conceptual modelling approach : insights from the Cotswolds, UK

Adequate hydrogeological conceptualisation of structurally complex fractured aquifers requires the support of detailed geological mapping and three dimensional understanding. With a geological framework in place uncertainties in hydrological understanding and irregularities in hydraulic observations may be rationalised. Using the Cotswold of southern England, which are underlain by the ooidal limestone-dominated Middle Jurassic Inferior Oolite and Great Oolite groups, 3D modelling software GSI3D and Geographical Information Systems (GIS) have been used to integrate observed hydraulic behaviours with the 3D geological framework. In this way a conceptual model is developed to assist simulation of groundwater flow and the predicted response of groundwater levels and river flows to climatic extremes. The structural and lithological complexity of the bedrock results in sub-catchments which exhibit individual hydraulic responses and a hydrogeological setting dominated by shallow rapid fracture pathways and copious spring discharge

The position of graptolites within Lower Palaeozoic planktic ecosystems.

An integrated approach has been used to assess the palaeoecology of graptolites both as a discrete group and also as a part of the biota present within Ordovician and Silurian planktic realms. Study of the functional morphology of graptolites and comparisons with recent ecological analogues demonstrates that graptolites most probably filled a variety of niches as primary consumers, with modes of life related to the colony morphotype. Graptolite coloniality was extremely ordered, lacking any close morphological analogues in Recent faunas. To obtain maximum functional efficiency, graptolites would have needed varying degrees of coordinated automobility. A change in lifestyle related to ontogenetic changes was prevalent within many graptolite groups. Differing lifestyle was reflected by differing reproductive strategies, with synrhabdosomes most likely being a method for rapid asexual reproduction. Direct evidence in the form of graptolithophage 'coprolitic' bodies, as well as indirect evidence in the form of probable defensive adaptations, indicate that graptolites comprised a food item for a variety of predators. Graptolites were also hosts to a variety of parasitic organisms and provided an important nutrient source for scavenging organisms

Recent developments in the characterization of superconducting films by microwaves

We describe and analyze selected surface impedance data recently obtained by different groups on cuprate, ruthenate and diboride superconducting films on metallic and dielectric substrates for fundamental studies and microwave applications. The discussion includes a first review of microwave data on MgB2, the weak-link behaviour of RABiTS-type YBa2Cu3O7-d tapes, and the observation of a strong anomalous power-dependence of the microwave losses in MgO at low temperatures. We demonstrate how microwave measurements can be used to investigate electronic, magnetic, and dielectric dissipation and relaxation in the films and substrates. The impact of such studies reaches from the extraction of microscopic information to the engineering of materials and further on to applications in power systems and communication technology.Comment: Invited contribution to EUCAS2001, accepted for publication in Physica C in its present for

Theory of coherent acoustic phonons in InGaN/GaN multi-quantum wells

A microscopic theory for the generation and propagation of coherent LA phonons in pseudomorphically strained wurzite (0001) InGaN/GaN multi-quantum well (MQW) p-i-n diodes is presented. The generation of coherent LA phonons is driven by photoexcitation of electron-hole pairs by an ultrafast Gaussian pump laser and is treated theoretically using the density matrix formalism. We use realistic wurzite bandstructures taking valence-band mixing and strain-induced piezo- electric fields into account. In addition, the many-body Coulomb ineraction is treated in the screened time-dependent Hartree-Fock approximation. We find that under typical experimental conditions, our microscopic theory can be simplified and mapped onto a loaded string problem which can be easily solved.Comment: 20 pages, 17 figure

Pattern formation in directional solidification under shear flow. I: Linear stability analysis and basic patterns

An asymptotic interface equation for directional solidification near the absolute stabiliy limit is extended by a nonlocal term describing a shear flow parallel to the interface. In the long-wave limit considered, the flow acts destabilizing on a planar interface. Moreover, linear stability analysis suggests that the morphology diagram is modified by the flow near the onset of the Mullins-Sekerka instability. Via numerical analysis, the bifurcation structure of the system is shown to change. Besides the known hexagonal cells, structures consisting of stripes arise. Due to its symmetry-breaking properties, the flow term induces a lateral drift of the whole pattern, once the instability has become active. The drift velocity is measured numerically and described analytically in the framework of a linear analysis. At large flow strength, the linear description breaks down, which is accompanied by a transition to flow-dominated morphologies, described in a companion paper. Small and intermediate flows lead to increased order in the lattice structure of the pattern, facilitating the elimination of defects. Locally oscillating structures appear closer to the instability threshold with flow than without.Comment: 20 pages, Latex, accepted for Physical Review

Spatial competition and agglomeration in the visitor attraction sector

This paper provides a theoretical and empirical contribution to understanding spatial competition by examining visitor attractions in two contrasting clusters of lower and higher levels of agglomeration of businesses in Cornwall, the UK. The study found that competition is mainly for customers and labour and is related differently to the levels of agglomeration, spatial proximity and thematic product similarity between visitor attractions at the local compared to the regional scale. Location can be used differently for employing ‘weak’ and ‘strong’ competitive strategies. The study contributes to the knowledge on the spatiality of competition and the locational strategies of service businesses

Toward an internally consistent astronomical distance scale

Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been established. We review current efforts to homogenize the Local Group's distance framework, with particular emphasis on the potential of RR Lyrae stars as distance indicators, and attempt to extend this in an internally consistent manner to cosmological distances. Calibration based on Type Ia supernovae and distance determinations based on gravitational lensing represent particularly promising approaches. We provide a positive outlook to improvements to the status quo expected from future surveys, missions, and facilities. Astronomical distance determination has clearly reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press (chapter 8 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

Behaviour and Climate Change: Consumer Perceptions of Responsibility

This paper explores the under-researched notion of consumer responsibility, a potentially significant influence on consumer behaviour that marketers and policymakers may be able to harness as they attempt to respond to environmental challenges such as climate change. The paper uses data derived from a commercially motivated survey (n = 1513) to explore domestic consumption behaviours most closely associated with the issue of disruptive climate change. A measure of 'General Environmental Responsiveness' (GER) is used to test: (1) the effects of consumers both taking responsibility for their actions and placing responsibility on others for the consequences of their consumption behaviour; and (2) whether sociodemographic variables can aid the targeting of consumers by the level and type of responsibility and pro-environmental behavioural intentions expressed. The study's findings demonstrate clear, if not strong, relationships between consumer conceptions of responsibilities for causing and tackling climate change and environment-related consumer behaviour. The study's implications both challenge accepted wisdom about environment-related consumer behaviour and suggest avenues for future research