Spin correlations in Ca3Co2O6: A polarised-neutron diffraction and Monte Carlo study

We present polarised-neutron diffraction measurements of the Ising-like spin-chain compound Ca3Co2O6 above and below the magnetic ordering temperature TN. Below TN, a clear evolution from a single-phase spin-density wave (SDW) structure to a mixture of SDW and commensurate antiferromagnet (CAFM) structures is observed on cooling. For a rapidly-cooled sample, the majority phase at low temperature is the SDW, while if the cooling is performed sufficiently slowly, then the SDW and the CAFM structure coexist between 1.5 and 10 K. Above TN, we use Monte Carlo methods to analyse the magnetic diffuse scattering data. We show that both intra- and inter-chain correlations persist above TN, but are essentially decoupled. Intra-chain correlations resemble the ferromagnetic Ising model, while inter-chain correlations resemble the frustrated triangular-lattice antiferromagnet. Using previously-published bulk property measurements and our neutron diffraction data, we obtain values of the ferromagnetic and antiferromagnetic exchange interactions and the single-ion anisotropy.Comment: 10 pages, 7 figure

The rapid dispersal of low-mass virialised clusters

Infant mortality brought about by the expulsion of a star cluster's natal gas is widely invoked to explain cluster statistics at different ages. While a well studied problem, most recent studies of gas expulsion's effect on a cluster have focused on massive clusters, with stellar counts of order $10^4$. Here we argue that the evolutionary timescales associated with the compact low-mass clusters typical of the median cluster in the Solar neighborhood are short enough that significant dynamical evolution can take place over the ages usually associated with gas expulsion. To test this we perform {\it N}-body simulations of the dynamics of a very young star forming region, with initial conditions drawn from a large-scale hydrodynamic simulation of gravitational collapse and fragmentation. The subclusters we analyse, with populations of a few hundred stars, have high local star formation efficiencies and are roughly virialised even after the gas is removed. Over 10 Myr they expand to a similar degree as would be expected from gas expulsion if they were initially gas-rich, but the expansion is purely due to the internal stellar dynamics of the young clusters. The expansion is such that the stellar densities at 2 Myr match those of YSOs in the Solar neighborhood. We argue that at the low-mass end of the cluster mass spectrum, a deficit of clusters at 10s of Myr does not necessarily imply gas expulsion as a disruption mechanism.Comment: 11 pages, accepted to MNRAS. Updated to match accepted version: title changed, one new subsection, some new figure

Integrating multicriteria decision analysis and scenario planning : review and extension

Scenario planning and multiple criteria decision analysis (MCDA) are two key management science tools used in strategic planning. In this paper, we explore the integration of these two approaches in a coherent manner, recognizing that each adds value to the implementation of the other. Various approaches that have been adopted for such integration are reviewed, with a primary focus on the process of constructing preferences both within and between scenarios. Biases that may be introduced by inappropriate assumptions during such processes are identified, and used to motivate a framework for integrating MCDA and scenario thinking, based on applying MCDA concepts across a range of "metacriteria" (combinations of scenarios and primary criteria). Within this framework, preferences according to each primary criterion can be expressed in the context of different scenarios. The paper concludes with a hypothetical but non-trivial example of agricultural policy planning in a developing country

Which Test Is Best? A Cluster-Randomized Controlled Trial of a Risk Calculator and Recommendations on Colorectal Cancer Screening Behaviour in General Practice

Introduction: This cluster-randomized controlled trial aimed to assess the effect of the "Which test is best?"tool on risk-appropriate screening (RAS) and colorectal cancer (CRC) screening uptake. Methods: General practices in Sydney and Melbourne, Australia, and a random sub-sample of 460 patients (aged 25-74 years) per practice were invited by post. Clusters were computer randomized independently of the researchers to an online CRC risk calculator with risk-based recommendations versus usual care. Primary and secondary outcomes were RAS and screening uptake via self-reported 5-year screening behaviour after 12 months follow-up. The usual care group (UCG) also self-reported 5-year CRC screening behaviour at 12 month post-randomization. Results: Fifty-six practices were randomized (27 to the intervention and 29 to the control, 55 practices participated) with 818 intervention and 677 controls completing the primary outcome measure. The intervention significantly increased RAS in high-risk participants compared with UCG (80.0% vs. 64.0%, respectively; OR = 3.14, 95% CI: 1.25-7.96) but not in average-risk (44.9% vs. 49.5%, respectively; OR = 0.97, 95% CI: 0.99-1.12) or moderate-risk individuals (67.9% vs. 81.1%, respectively; OR = 0.40, 95% CI: 0.12-1.33). Faecal occult blood testing uptake over 12 months was increased compared with the UCG (24.9% vs. 15.1%; adjusted OR = 1.66, 95% CI: 1.24-2.22), and there was a non-significant increase in colonoscopies during the same period (16.6% vs. 12.2%; adjusted OR = 1.42, 95% CI: 0.97-2.08). Conclusion: An online CRC risk calculator with risk-based screening recommendations increased RAS in high-risk participants and improved screening uptake overall within a 12-month follow-up period. Such tools may be useful for facilitating the uptake of risk-based screening guidelines

Extreme water levels, waves and coastal impacts during a severe tropical cyclone in northeastern Australia: a case study for cross-sector data sharing

Severe tropical cyclone (TC) Debbie made landfall on the northern Queensland coast of Australia on 27 March 2017 after crossing the Great Barrier Reef as a slow-moving Category 4 system. Groups from industry, government and academia collected coastal hazard and impact data before, during and after the event and shared these data to produce a holistic picture of TC Debbie at the coast. Results showed the still water level exceeded the highest astronomical tide by almost a metre. Waves added a further 16&thinsp;% to water levels along the open coast, and were probably unprecedented for this area since monitoring began. In most places, coastal barriers were not breached and as a result there was net offshore sand transport. If landfall had occurred 2&thinsp;h earlier with the high tide, widespread inundation and overwash would have ensued. This paper provides a case study of effective cross-sector data sharing in a natural hazard context. It advocates for a shared information platform for coastal extremes in Australia to help improve the understanding and prediction of TC-related coastal hazards in the future.</p

Modelling the dynamics of support for a right-wing populist party: the case of UKIP

ABSTRACT: Similar to a number of other right-wing populist parties in Europe, Great Britain's United Kingdom Independence Party (UKIP) has experienced increased public support in recent years. Using aggregate data from monthly national surveys conducted between April 2004 and April 2014, time series analyses demonstrate that the dynamics of UKIP support were influenced by a combination of spatial and valence issues. A spatial issue, Euroscepticism, was fundamental, with UKIP support moving in dynamic equilibrium with changing public attitudes towards EU membership. In addition, widespread anti-immigration sentiment and dissatisfaction with the performance of the Conservative–Liberal Democrat coalition government combined with the “oxygen of publicity” to propel UKIP's surge. The political context after the 2010 general election helped as well by enabling UKIP to benefit from valence considerations. Many voters continued to doubt the competence of the major opposition party, Labour, while the Liberal Democrats were part of the government and, hence, unavailable as a protest vehicle. Since many of the forces driving UKIP support are beyond its control, the party's prospects are highly uncertain