Brief communication: impacts of ocean-wave-induced breakup of Antarctic sea ice via thermodynamics in a stand-alone version of the CICE sea-ice model

Impacts of wave-induced breakup of Antarctic sea ice on ice concentration and volume are investigated using a modified version of the CICE sea-ice model, run in standalone mode from 1979–2010. Model outputs show that during summer wave-induced breakup reduces local ice concentration by up to 0.3–0.4 in a vicinity of the ice edge and total ice volume by up to a factor of 0.1–0.2.Luke G. Bennetts, Siobhan O’Farrell, and Petteri Uotil

Localisation in water wave and thin plate problems

Simulations obtained for water waves over rough seabed and waves in rough in vacuo plate. Attenuation rates of effective and individual wave fields extracted, compared and found to differ

The impact of oral English proficiency on humanitarian migrants’ experiences of settling in Australia

© 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group. Key drivers for migrants’ social integration are education, employment, and skills in the dominant language of the settlement country. Data from Building a New Life in Australia: The Longitudinal Study of Humanitarian Migrants were used to examine migrants’ English proficiency and how oral English proficiency facilitated or hindered participation in activities that may help them become self-sufficient and settle. Participants were 2399 humanitarian migrants interviewed in the first wave of data collection (during 2013/14). Before arrival in Australia, 80.1% reported they spoke English not well or not at all. After arrival, oral English proficiency was a statistically significant predictor of self-sufficiency (knowing how to look for a job, get help in an emergency, etc.) explaining 21% of the variance while controlling for confounding variables such as age and education. After English proficiency, age (neither too young nor too old), gender (male), education (more than 12 years), and time since arrival (more than one year) were significant predictors of self-sufficiency. Identification of factors that predict self-sufficiency informs the understanding of people who provide support for humanitarian migrants. These findings indicate poor oral English skills may profoundly hinder humanitarian migrants’ ability to settle and highlight the importance of supporting migrants’ English learning

The wallaby menace in the Kimberleys

Countless thousands of Sandy Wallabies (Macropus agilis) have long been a menace to the pastoral industry in the Kimberleys. These animals eat almost the same foods as the sheep and cattle and have substantially reduced the stock-carrying capacity of the river-frontage areas where they are found in the greatest numbers. Research into control methods was commenced in 1952 when Mr. L. A. Harrison undertook some investigations designed to ascertain the best line of approach to a poisoning campaign

An assessment of key risk factors for surgical site infection in patients undergoing surgery for spinal metastases

Objectives This study aimed to determine the rate of surgical site infection (SSI) in patients undergoing surgery for spinal metastases, and identify key risk factors for SSI among this patient group. Methods A retrospective case note review was undertaken in 152 adult patients being treated at a single specialist centre for spinal surgery. Results Overall SSI rate was 11.2% per patients (9.7% per procedure). An increase in the risk of SSI was observed when surgery involved a greater number of vertebral levels (odds ratio 1.26, P=0.019) when controlling for primary spinal region. Controlling for the number of spinal levels, the odds of SSI increased by a factor of 5.6 (P=0.103) when the primary surgical region was thoracic, as opposed to cervical or lumbar. Conclusions In conclusion, surgery associated with multiple vertebral levels for treatment of spinal metastases, particularly of the thoracic spine, is associated with increased risk of SSI

Water wave transmission by an array of floating discs

Published 27 November 2014An experimental validation of theoretical models of regular-water-wave transmission through arrays of floating discs is presented. The experiments were conducted in a wave basin. The models are based on combined potential-flow and thin-plate theories, and the assumption of linear motions. A low-concentration array, in which discs are separated by approximately a disc diameter in equilibrium, and a high-concentration array, in which adjacent discs are almost touching in equilibrium, were used for the experiments. The proportion of incident-wave energy transmitted by the discs is presented as a function of wave period, and for different wave amplitudes. Results indicate the models predict wave-energy transmission accurately for small-amplitude waves and low-concentration arrays. Discrepancies for large-amplitude waves and high-concentration arrays are attributed to wave overwash of the discs and collisions between discs. Validation of model predictions of a solitary disc's rigid-body motions are also presented.L. G. Bennetts and T. D. William

Spectral analysis of wave propagation through rows of scatterers via random sampling and a coherent potential approximation

A method is proposed for determining the modal spectra of waves supported by arrays, which are composed of multiple rows of scatterers randomly disordered around an underlying periodic configuration. The method is applied to the canonical problem of arrays of identical small acoustically soft circular cylinders and disorder in the location of the rows. Two different approaches are adopted to calculate the modes: (i) forming an ensemble average of the modes from individual realizations (loosely: extract information, then average); and (ii) extracting the modes from the ensemble average wave field (loosely: average, then extract information). Differences in the attenuation rates predicted by the two approaches, which cannot be attributed to numerical errors, are found for problems involving multiple wave directions and large disorder. A form of the coherent potential approximation (CPA) is also devised. Comparisons of the CPA to the results given by random sampling show that it gives high accuracy. © 2013 Society for Industrial and Applied Mathematics.Luke G. Bennetts and Malte A. Pete

Three-dimensional time-domain scattering of waves in the marginal ice zone

Three-dimensional scattering of ocean surface waves in the marginal ice zone (MIZ) is determined in the time domain. The solution is found using spectral analysis of the linear operator for the Boltzmann equation. The method to calculate the scattering kernel that arises in the Boltzmann model from the single-floe solution is also presented along with new identities for the far-field scattering, which can be used to validate the single-floe solution. The spectrum of the operator is computed, and it is shown to have a universal structure under a special non-dimensionalization. This universal structure implies that under a scaling wave scattering in the MIZ has similar properties for a large range of ice types and wave periods. A scattering theory solution using fast Fourier transforms is given to find the solution for directional incident wave packets. A numerical solution method is also given using the split-step method and this is used to validate the spectral solution. Numerical calculations of the evolution of a typical wave field are presented. This article is part of the theme issue 'Modelling of sea-ice phenomena'.M.H. Meylan and L.G. Bennett

Water-wave scattering and energy dissipation by a floating porous elastic plate in three dimensions

Abstract not availableMichael H. Meylan, Luke G. Bennetts, Malte A. Pete