On the interaction of ultrasound with cracks: Applications to fatigue crack growth

Partial contact of two rough fatigue crack surfaces leads to transmission and diffraction of an acoustic signal at those contacts. Recent experimental and theoretical efforts to understand and quantify such contact in greater detail are discussed. The objective is to develop an understanding of the closure phenomenon and its application to the interpretation of fatigue data, in particular the R-ratio, spike overload/underload and threshold effects on crack propagation

Characterization of Knots and Links Arising From Site-specific Recombination on Twist Knots

We develop a model characterizing all possible knots and links arising from recombination starting with a twist knot substrate, extending previous work of Buck and Flapan. We show that all knot or link products fall into three well-understood families of knots and links, and prove that given a positive integer $n$, the number of product knots and links with minimal crossing number equal to $n$ grows proportionally to $n^5$. In the (common) case of twist knot substrates whose products have minimal crossing number one more than the substrate, we prove that the types of products are tightly prescribed. Finally, we give two simple examples to illustrate how this model can help determine previously uncharacterized experimental data.Comment: 32 pages, 7 tables, 27 figures, revised: figures re-arranged, and minor corrections. To appear in Journal of Physics

High-output forage systems for meeting beef markets – Phase 1. Project B.NBP.0496 Final Report

This report addresses the issue of how to identify, grow,manage and profitably utilise high quality, speciality forages for growing and finishing beef cattle in the Fitzroy River catchment. Best-practice agronomic management of forages and data for cattle production responses in the target area were reviewed. In addition, existing forage decision support tools were reviewed and recommendations made on an approach to develop a simple animal production model for forages. A partial budgeting approach was used to assess five high quality forages and a baseline pasture option to indicate the relative profitability of key forage options. This was done at each of three sites within the Fitzroy River catchment and for both zero till and cultivation methods of fallow weed control. This information can be used, in conjunction with qualitative assessment of social, managerial and environmental factors and assessment of flow-on effects on whole farm profitability, to help inform decisions about whether, when and how to incorporate various high quality forage systems into a beef production enterprise. A best-practice management guide, Using high quality forages to meet beef markets in the Fitzroy River catchment, and a spreadsheet calculator, ForageCalc, have been produced and can be used to support decision making

Feeding forages in the Fitzroy : A guide to profitable beef production in the Fitzroy River catchment

This guide brings together information on: • selection, agronomy and management of suitable forages • example forage yields across the Fitzroy River catchment • expected nutrient content of forages and their relationship to cattle performance • indicative cattle growth rates from a range of high quality forages • approaches to incorporating high quality forages into feed plans to give the best opportunity to achieve the target growth rates and liveweights required to meet market specifications • non-nutritional factors that can affect liveweight gain • example gross margin analysis at key sites across the catchment to provide objective comparisons of various forage options • spreadsheets to allow calculation of forage gross margins with the user’s own input variables • the effect of sown forages on the whole farm profitability • data collected from 24 producer co-operator forage sites across the Fitzroy River catchment during 2011–2014

Plant nutrient analysis in established leucaena

Growth and forage quality of established leucaena can be constrained by low nutrient supply due to naturally low soil nutrient levels or induced deficiencies from previous land uses that removed nutrients (e.g. grain cropping). Monitoring nutrient levels in the soil or plant tissue is important for maintaining high productivity from established leucaena stands. Plant tissue testing measures the concentration of nutrients in a leucaena stand to determine if levels are sufficient for optimal growth. Sampling and testing plant tissue nutrients can sound complicated, but following a few simple steps can ensure reliable results

Radii and Binding Energies of Nuclei in the Alpha-Cluster Model

The alpha-cluster model is based on two assumptions that the proton-neutron pair interactions are responsible for adherence between alpha-clusters and that the NN-interaction in the alpha-clusters is isospin independent. It allows one to estimate the Coulomb energy and the short range inter-cluster bond energy in dependence on the number of clusters. The charge radii are calculated on the number of alpha-clusters too. Unlike the Weizsacker formula in this model the binding energies of alpha-clusters and excess neutrons are estimated separately. The calculated values are in a good agreement with the experimental data.Comment: Latex2e 2.09, 13 pages, 4 figure

Changes in the Sea-Ice Brine Community During the Spring-Summer Transition, McMurdo Sound, Antarctica .2. Phagotrophic Protists

The land-fast sea-ice brine contains a diverse phagotrophic protist assemblage consisting of \u3c 5 mum heterotrophic flagellates, Cryothecomonas spp., heterotrophic dinoflagellates, and heterotrophic and mixotrophic ciliates. Fine-scale horizontal spatial variability is a feature of this assemblage; samples taken within 1 m of each other can be dominated by different heterotrophic protists. Many of the larger heterotrophic protists found in the brine are also found in the water column. The photosynthetic ciliate Mesodinium rubrum is also common. In mid to late austral spring, the heterotrophic assemblage accounts for ca 10% of the total protist biomass in the brine and is dominated by Cryothecomonas spp. This flagellate can reach densities of over 106 cells l-1 of brine. In the early austral summer, ciliates (primarily Strombidium spp., Mesodinium rubrum and Didinium spp.) and heterotrophic dinoflagellates (primarily a small Gymnodinium sp. and Polykrikos sp.) increase in abundance in the brine. Ciliate densities of ≥ 3 x 103 l-1 and heterotrophic dinoflagellate densities of 104 cells l-1 are common in the brine during early summer. By the end of January (just prior to ice decay and break-out), heterotrophic flagellates and ciliates can account for 50 % of the protist biomass