Bayesian Ranking and Selection of Fishing Boat Efficiencies

The steadily accumulating literature on technical efficiency in fisheries attests to the importance of efficiency as an indicator of fleet condition and as an object of management concern. In this paper, we extend previous work by presenting a Bayesian hierarchical approach that yields both efficiency estimates and, as a byproduct of the estimation algorithm, probabilistic rankings of the relative technical efficiencies of fishing boats. The estimation algorithm is based on recent advances in Markov Chain Monte Carlo (MCMC) methods—Gibbs sampling, in particular—which have not been widely used in fisheries economics. We apply the method to a sample of 10,865 boat trips in the US Pacific hake (or whiting) fishery during 1987–2003. We uncover systematic differences between efficiency rankings based on sample mean efficiency estimates and those that exploit the full posterior distributions of boat efficiencies to estimate the probability that a given boat has the highest true mean efficiency.Ranking and selection, hierarchical composed-error model, Markov Chain Monte Carlo, Pacific hake fishery, Resource /Energy Economics and Policy, Q2, L5, C1,

Your neighbours are your friends : An investigation into microgeographical exchanges in the remote northwest of Australia between 1987-2012

This paper addresses intersections of communication, technology and geography in remote areas of Western Australia. It uses verbatim accounts from fieldwork bracketing decades of communication development to explore changes and constants in the micro-geographical exchange strategies of people living in the remote northwest of Australia. It articulates the continuing irony that the Australians who most need reliable and effective communications are those who experience the greatest difficulty in accessing them. We contend that geographical isolation and continuing problems with the reliability and reach of communication technologies in remote Western Australia have cultivated a robust community in which flexibility, resilience and interdependence redress, to some degree, the vulnerability remote communities often experience—especially in times of stress or crisis. The paper includes historical interviews from the 1980s and contemporary (2012) interviews carried out as part of an ARC Linkage-funded project, 2012-14, with industry partner Landgate, a Western Australian government entity

Towards a natural history of internet use? Working to overcome the implications for research of the child-adult divide

Using a metaphor borrowed from the biological sciences, this paper discusses a ‘natural history’ of Internet use. As ‘digital natives’ many of today’s teenagers and young people have grown up and matured interacting with the Internet from an early age. Research about young people’s Internet use tends, however, to focus on the protection of minors. Young people, 16 years or older, are often excluded from noncommercial research about how young people grow into more mature patterns of Internet use. This paper highlights how parents with teenagers are building dynamic models of their children’s engagement with the Internet as they mature. Parents reported changes in the level of their children’s Internet use as they age and they envisage further changes as their children mature. We also identify the variety of ways in which parents support their children’s developing Internet skills that anticipate and respond to Internet risks and excessive Internet use

Rank varieties for a class of finite-dimensional local algebras

AbstractWe develop a rank variety for finite-dimensional modules over a certain class of finite-dimensional local k-algebras, Aq,mn. Included in this class are the truncated polynomial algebras k[X1,…,Xm]/(Xin), with k an algebraically closed field and char(k) arbitrary. We prove that these varieties characterise projectivity of modules (Dade’s lemma) and examine the implications for the tree class of the stable Auslander–Reiten quiver. We also extend our rank varieties to infinitely generated modules and verify Dade’s lemma in this context

Linear Taylor–Couette stability of a transversely isotropic fluid

Fibre-laden fluids are found in a variety of situations, while Couette devices are used for flow spectroscopy of long biological molecules, such as DNA and proteins in suspension. The presence of these fibres can significantly alter the rheology of the fluid, and hence must be incorporated in any modelling undertaken. A transversely isotropic fluid treats these suspensions as a continuum with an evolving preferred direction, through a modified stress tensor incorporating four viscosity-like parameters. We consider the axisymmetric linear stability of a transversely isotropic viscous fluid, contained between two rotating co-axial cylinders, and determine the critical wave and Taylor numbers for varying gap width and inner cylinder velocity (assuming the outer cylinder is fixed). Through the inclusion of transversely isotropic effects, the onset of instability is delayed, increasing the range of stable operating regimes. This effect is felt most strongly through incorporation of the anisotropic shear viscosity, although the anisotropic extensional viscosity also contributes. The changes to the rheology induced by the presence of the fibres therefore significantly alter the dynamics of the system, and hence should not be neglected

Statistical analysis of an RNA titration series evaluates microarray precision and sensitivity on a whole-array basis

BACKGROUND: Concerns are often raised about the accuracy of microarray technologies and the degree of cross-platform agreement, but there are yet no methods which can unambiguously evaluate precision and sensitivity for these technologies on a whole-array basis. RESULTS: A methodology is described for evaluating the precision and sensitivity of whole-genome gene expression technologies such as microarrays. The method consists of an easy-to-construct titration series of RNA samples and an associated statistical analysis using non-linear regression. The method evaluates the precision and responsiveness of each microarray platform on a whole-array basis, i.e., using all the probes, without the need to match probes across platforms. An experiment is conducted to assess and compare four widely used microarray platforms. All four platforms are shown to have satisfactory precision but the commercial platforms are superior for resolving differential expression for genes at lower expression levels. The effective precision of the two-color platforms is improved by allowing for probe-specific dye-effects in the statistical model. The methodology is used to compare three data extraction algorithms for the Affymetrix platforms, demonstrating poor performance for the commonly used proprietary algorithm relative to the other algorithms. For probes which can be matched across platforms, the cross-platform variability is decomposed into within-platform and between-platform components, showing that platform disagreement is almost entirely systematic rather than due to measurement variability. CONCLUSION: The results demonstrate good precision and sensitivity for all the platforms, but highlight the need for improved probe annotation. They quantify the extent to which cross-platform measures can be expected to be less accurate than within-platform comparisons for predicting disease progression or outcome