A three-dimensional active cloaking strategy for the Helmholtz equation that exploits the symmetry of the platonic solids.

An active cloaking strategy for the scalar Helmholtz equation in three dimensions is developed by placing active sources at the vertices of Platonic solids. In each case, a "silent zone" is created interior to the Platonic solid and only the incident field remains in a defined region exterior to this zone. This distribution of sources ensures that implementation of the cloaking strategy is efficient: once the multipole source amplitudes at a single source location are determined, the other amplitudes are calculated by multiplying the multipole source vector by a rotation matrix.

Asymptotics of the meta-atom: plane wave scattering by a single Helmholtz resonator.

Using a combination of multipole methods and the method of matched asymptotic expansions, we present a solution procedure for acoustic plane wave scattering by a single Helmholtz resonator in two dimensions. Closed-form representations for the multipole scattering coefficients of the resonator are derived, valid at low frequencies, with three fundamental configurations examined in detail: the thin-walled, moderately thick-walled and extremely thick-walled limits. Additionally, we examine the impact of dissipation for extremely thick-walled resonators, and also numerically evaluate the scattering, absorption and extinction cross-sections (efficiencies) for representative resonators in all three wall thickness regimes.

Deeply subwavelength giant monopole elastodynamic metacluster resonators.

The giant monopole resonance is a well-known phenomenon, employed to tune the dynamic response of composite materials comprising voids in an elastic matrix which has a bulk modulus much greater than its shear modulus, e.g. elastomers.

Food insecurity as experienced by New Zealand women and their children.

Food insecurity, defined as uncertainty in reliably accessing adequate quantities of nutritious food, is an issue for many families and children, including in New Zealand. Drawing on the experiences of mothers, this study explored the nature, causes and impact of food insecurity for their families. Semi-structured face-to-face interviews conducted with six female sole-parents were complemented with food insecurity data from the NZ Health Survey and Youth2000 surveys.

Bayesian inference on a microstructural, hyperelastic model of tendon deformation.

Microstructural models of soft-tissue deformation are important in applications including artificial tissue design and surgical planning. The basis of these models, and their advantage over their phenomenological counterparts, is that they incorporate parameters that are directly linked to the tissue's microscale structure and constitutive behaviour and can therefore be used to predict the effects of structural changes to the tissue. Although studies have attempted to determine such parameters using diverse, state-of-the-art, experimental techniques, values ranging over several orders of magnitude have been reported, leading to uncertainty in the true parameter values and creating a need for models that can handle such uncertainty.

Correction to 'A modified formulation of quasi-linear viscoelasticity for transversely isotropic materials under finite deformation'.

[This corrects the article DOI: 10.1098/rspa.2018.

A Recruitment Model of Tendon Viscoelasticity That Incorporates Fibril Creep and Explains Strain-Dependent Relaxation.

Soft tissues exhibit complex viscoelastic behavior, including strain-rate dependence, hysteresis, and strain-dependent relaxation. In this paper, a model for soft tissue viscoelasticity is developed that captures all of these features and is based upon collagen recruitment, whereby fibrils contribute to tissue stiffness only when taut. We build upon existing recruitment models by additionally accounting for fibril creep and by explicitly modeling the contribution of the matrix to the overall tissue viscoelasticity.

Static elastic cloaking, low-frequency elastic wave transparency and neutral inclusions.

New connections between static elastic cloaking, low-frequency elastic wave scattering and neutral inclusions (NIs) are established in the context of two-dimensional elasticity. A cylindrical core surrounded by a cylindrical shell is embedded in a uniform elastic matrix. Given the core and matrix properties, we answer the questions of how to select the shell material such that (i) it acts as a static elastic cloak, and (ii) it eliminates low-frequency scattering of incident elastic waves.

A population health dietary intervention for African American adults with chronic kidney disease: The Fruit and Veggies for Kidney Health randomized study.

Background: Chronic kidney disease (CKD) is commonly asymptomatic until its late stages, reduces life quality and length, is costly to manage, and is disproportionately prevalent in low-income, African American (AA) communities. Traditional health system strategies that engage only patients with symptomatic CKD limit opportunities to prevent progression to end stage kidney disease (ESKD) with the need for expensive kidney replacement therapy and to reduce risk for their major mortality cause, cardiovascular disease (CVD). Published studies show that giving fruits and vegetables (F&V) to AA with early-stage CKD along with preparation instructions slowed CKD progression.

A proof that multiple waves propagate in ensemble-averaged particulate materials.

Effective medium theory aims to describe a complex inhomogeneous material in terms of a few important macroscopic parameters. To characterize wave propagation through an inhomogeneous material, the most crucial parameter is the . For this reason, there are many published studies on how to calculate a single effective wavenumber.

Soft metamaterials with dynamic viscoelastic functionality tuned by pre-deformation.

The small amplitude dynamic response of materials can be tuned by employing inhomogeneous materials capable of large deformation. However, soft materials generally exhibit viscoelastic behaviour, i.e.

Thermo-viscous damping of acoustic waves in narrow channels: A comparison of effects in air and water.

Recent work in the acoustic metamaterial literature has focused on the design of metasurfaces that are capable of absorbing sound almost perfectly in narrow frequency ranges by coupling resonant effects to visco-thermal damping within their microstructure. Understanding acoustic attenuation mechanisms in narrow, viscous-fluid-filled channels is of fundamental importance in such applications. Motivated by recent work on acoustic propagation in narrow, air-filled channels, a theoretical framework is presented that demonstrates the controlling mechanisms of acoustic propagation in arbitrary Newtonian fluids, focusing on attenuation in air and water.

Damage prediction via nonlinear ultrasound: A micro-mechanical approach.

Nonlinear constitutive mechanical parameters, predominantly governed by micro-damage, interact with ultrasound to generate harmonics that are not present in the excitation. In principle, this phenomenon therefore permits early stage damage identification if these higher harmonics can be measured. To understand the underlying mechanism of harmonic generation, a nonlinear micro-mechanical approach is proposed here, that relates a distribution of clapping micro-cracks to the measurable macroscopic acoustic nonlinearity by representing the crack as an effective inclusion with Landau type nonlinearity at small strain.

A modified formulation of quasi-linear viscoelasticity for transversely isotropic materials under finite deformation.

The theory of quasi-linear viscoelasticity (QLV) is modified and developed for transversely isotropic (TI) materials under finite deformation. For the first time, distinct relaxation responses are incorporated into an integral formulation of nonlinear viscoelasticity, according to the physical mode of deformation. The theory is consistent with linear viscoelasticity in the small strain limit and makes use of relaxation functions that can be determined from small-strain experiments, given the time/deformation separability assumption.

Correction to 'Antiplane wave scattering from a cylindrical cavity in pre-stressed nonlinear elastic media'.

[This corrects the article DOI: 10.1098/rspa.2015.

Hyperelastic antiplane ground cloaking.

Hyperelastic materials possess the appealing property that they may be employed as elastic wave manipulation devices and cloaks by imposing pre-deformation. They provide an alternative to microstructured metamaterials and can be used in a reconfigurable manner. Previous studies indicate that exact elastodynamic invariance to pre-deformation holds only for neo-Hookean solids in the antiplane wave scenario and the semi-linear material in the in-plane compressional/shear wave context.

Reflection from a multi-species material and its transmitted effective wavenumber.

We formally deduce closed-form expressions for the transmitted effective wavenumber of a material comprising multiple types of inclusions or particles (multi-species), dispersed in a uniform background medium. The expressions, derived here for the first time, are valid for moderate volume fractions and without restriction on the frequency. We show that the multi-species effective wavenumber is not a straightforward extension of expressions for a single species.

An integral equation method for the homogenization of unidirectional fibre-reinforced media; antiplane elasticity and other potential problems.

In Parnell & Abrahams (2008 , 1461-1482. (doi:10.1098/rspa.

Soft phononic crystals with deformation-independent band gaps.

Soft phononic crystals have the advantages over their stiff counterparts of being flexible and reconfigurable. Normally, the band gaps of soft phononic crystals will be modified after deformation due to both geometric and constitutive nonlinearity. Indeed these are important properties that can be exploited to tune the dynamic properties of the material.

Development of a Healthy Dietary Habits Index for New Zealand Adults.

Healthful dietary habits are individually associated with better nutrient intake and positive health outcomes; however, this information is rarely examined together to validate an indicator of diet quality. This study developed a 15-item Healthy Dietary Habits Index (HDHI) based on self-reported dietary habits information collected in the 2008/09 New Zealand Adult Nutrition Survey. The validity of HDHI as a diet quality index was examined in relation to sociodemographic factors, 24-diet recall derived nutrient intakes, and nutritional biomarkers in a representative sample of adults aged 19 years and above.

The influence of random microstructure on wave propagation through heterogeneous media.

In this paper the influence of mechanical and geometrical properties, both deterministic and stochastic in nature, of a heterogeneous periodic composite material on wave propagation has been analysed in terms of the occurrence of stop-bands. Numerical analyses have been used to identify those parameters that have the most significant effect on the wave filtering properties of the medium. A striking conclusion is that randomness in geometrical properties has a much larger effect than randomness in mechanical properties.

The Newtonian potential inhomogeneity problem: non-uniform eigenstrains in cylinders of non-elliptical cross section.

Understanding the fields that are set up in and around inhomogeneities is of great importance in order to predict the manner in which heterogeneous media behave when subjected to applied loads or other fields, e.g., magnetic, electric, thermal, etc.

Obesity and the extent of liver damage among adult New Zealanders: findings from a national survey.

Objective: Non-alcoholic fatty liver disease (NAFLD), defined as excessive fat accumulation in hepatocytes when no other pathologic causes are present, is an increasingly common obesity-related disorder. We sought to describe the prevalence of elevated liver enzymes, a marker of liver damage, among New Zealand adults, and high-risk subgroups including those with an elevated body mass index and those with pre-diabetes or diabetes, to gain a better understanding of the burden of liver disease.

Methods: A total of 4,721 New Zealanders aged 15+ years participated in a nationally representative nutrition survey.

Serum Zinc Is a Major Predictor of Anemia and Mediates the Effect of Selenium on Hemoglobin in School-Aged Children in a Nationally Representative Survey in New Zealand.

Background: Zinc, selenium, and vitamin D status of New Zealand (NZ) school-aged children was examined in a national survey in 2002. To our knowledge, however, the role of these micronutrients as predictors of hemoglobin has not been explored despite plausible mechanisms for such relations.

Objective: We examined the relations of iron, zinc, selenium, and vitamin D status with hemoglobin and anemia in children of New Zealand European and other (NZEO) ethnicity enrolled in the 2002 Children's Nutrition Survey and explored whether zinc mediated the relation between selenium and hemoglobin.