REPRODUCTIVE SUCCESS IN HATCHERY-PRODUCED EASTERN OYSTER, CRASSOSTREA VIRGINICA (GMELIN)

The eastern oyster (Crassostrea virginica Gmelin 1791) has great ecological and economic importance but populations have declined, especially in Chesapeake Bay, to historically low numbers. Hatcheries strive to produce oysters with beneficial characteristics for supplementation and commercial purposes, both natural and stimulated mass spawning. Unequal contribution of parents in mass spawnings potentially can lead to high levels of inbreeding and a loss of beneficial characteristics in offspring. In this study, we determined microsatellite genotypes for parents (n^parents =24, 49, and 77 parents) and progeny (n=96 each) of three hatchery-produced families and used the data for parental assignment. We observed the presence of more than two alleles per locus for some offspring, yet because genetic analysis software only allows for a maximum of two alleles per locus, we chose the two alleles with the strongest signals. For the three parent “populations,” 71% of alleles had frequencies of \u3c0.05 and observed heterozygosities were lower than expected by an average factor of 0.27. Inbreeding within the various parent populations was similar across the three families ranging from F^IS 0.26–0.43. In all three families, the offspring exhibited greater levels of genetic diversity and lower inbreeding levels than the parents (F^IS 0.14–0.21), and in some cases offspring exhibited alleles that were not present in the parents. Variance in the number of offspring produced per parent was observed for all families and in general, \u3c10% of potential parents (generally 2-5 females and 1-3 males) produced \u3e10% of the offspring. Reproductive success for spawning parents, N^b, determined by three methods, ranged from 0.07 to 0.27. As the number of parents per family increased, a higher proportion of parents failed to produce offspring. Across all three families, the average effective number of breeders was N^b = 7.1 and the level of reproductive success was inversely proportional to the number of potential parents. This finding implies that to maintain high levels of diversity and beneficial characteristics in the offspring (and to avoid the chance of unintentional inbreeding), hatcheries should perform more spawnings with fewer parents

The Open Society and coach education: a philosophical agenda for policy reform and future sociological research

Background: The realisation of the strategic importance of high quality coaching to the achievement of national sport policy objectives is resulting in extensive movements to professionalise the coaching industry. Interest in coach education is therefore growing among academics and policy-makers alike. A recent review of literature in this field, however, reveals a troubling problem situation: formal coach education is important for coach learning but tends to be expensive, inflexible and overly technical and therefore has little real impact on coaching practice. The solutions offered by many academics are, unfortunately, vague and often philosophically flawed. This is particularly so when the descriptive model of communities of practice (CoP) is suggested as a prescriptive model for coach education. The first part of the paper, therefore, ends with an extended critique of the use of CoP as a model for coach education. Purpose: To provide a clear philosophical argument for the direction of reform for coach education, drawing on a normative theory of the ideal conditions for the growth of knowledge. Discussion: Starting with the argument that any descriptive (or ‘evidence-based’) model is inherently conservative, the second part of the paper offers an alternative solution to the problem of coach education that is openly prescriptive (or normative). It is the Popperian ideal type of an Open Society (OS). It is argued that the concept of an OS is a better prescriptive model for coach learning for a number of reasons. First, it is based on a logically sound epistemological theory of the ideal social conditions for the growth of knowledge. Second, it is simple and easy for lay people to understand. Third, as an ideal type, it offers a target or goal against which progress towards a better method of coach education can be measured. In this final sense, it also offers a clear agenda for policy reform and future sociological research. Conclusions: The paper makes a series of practical recommendations for reforming coach education and its institutions based on the model of the OS. Foremost among these are making learning resources free at the point of use and using Web 2.0 technologies to democratise educational episodes and widen participation in coach education programmes of all kinds

Palindromic primitives and palindromic bases in the free group of rank two

The present paper records more details of the relationship between primitive elements and palindromes in F_2, the free group of rank two. We characterise the conjugacy classes of primitive elements which contain palindromes as those which contain cyclically reduced words of odd length. We identify large palindromic subwords of certain primitives in conjugacy classes which contain cyclically reduced words of even length. We show that under obvious conditions on exponent sums, pairs of palindromic primitives form palindromic bases for F_2. Further, we note that each cyclically reduced primitive element is either a palindrome, or the concatenation of two palindromes.Comment: 8 page

‘CEO equals man’: Gender and informal organisational practices in English sport governance

© The Author(s) 2019. © YYYY Owner. The final, definitive version of this paper has been published in Piggott, L. V., & Pike, E. C. (2019). ‘CEO equals man’: Gender and informal organisational practices in English sport governance. International Review for the Sociology of Sport by Sage Publications Ltd. All rights reserved. It is available at: https://doi.org/10.1177/1012690219865980Despite the benefits of diversity amongst sport leaders increasingly being argued by both researchers and practitioners, English sport governance remains gender-imbalanced at all levels of leadership. Within this article, we aim to explore how informal organisational practices within two established English national governing bodies impact upon gender equity and gender balance within their governance. This is important to raise awareness of the power of informal organisational practices to favour one gender over another. We present findings generated through a multi-method qualitative approach of semi-structured interviews and participant observation. Official documents from the two organisations were also drawn upon to add specific detail or fill information gaps during the collection, analysis and write-up of data. Throughout the article, we draw upon Bourdieu’s theory of practice to focus on the ways in which cultural resources, processes and institutions hold sport leaders within gendered hierarchies of dominance. We found that informal organisational practices contribute to the reinforcement of gendered structures of dominance which privilege (dominant) men and masculinity, and normalise and naturalise the positions of men as leaders. Some examples of resistance against inequitable informal practices were also evident. Drawing upon Bourdieu’s theorising, we highlight that alternative practices must be valued more highly by the organisation than current problematic practices in order for them to become legitimised, habitual and sustainable. We suggest that one way of achieving this is by linking gender-equitable governance to organisational values and performance to provide motivation for organisations to make genuine, sustainable change.Peer reviewe

Rigidity of graph products of abelian groups

We show that if $G$ is a group and $G$ has a graph-product decomposition with finitely-generated abelian vertex groups, then $G$ has two canonical decompositions as a graph product of groups: a unique decomposition in which each vertex group is a directly-indecomposable cyclic group, and a unique decomposition in which each vertex group is a finitely-generated abelian group and the graph satisfies the $T_0$ property. Our results build on results by Droms, Laurence and Radcliffe.Comment: 11 pages, 1 figur

The Bieri-Neumann-Strebel Invariant of the Pure Symmetric Automorphisms of a Right-Angled Artin Group

We compute the BNS-invariant for the pure symmetric automorphism groups of right-angled Artin groups. We use this calculation to show that the pure symmetric automorphism group of a right-angled Artin group is itself not a right-angled Artin group provided that its defining graph contains a separating intersection of links

Consumer Price Formation with Demographic Translating

We investigate how to theoretically and empirically incorporate demographic translating in consumer distance functions. Consumer distance functions yield inverse demand systems that are of interest when attempting to better understand questions of price formation. Translating procedures are important when incorporating pre-committed quantities, pre-allocated factors, or demographic variables (e.g., advertising, health or food safety information) in the inverse demand system. Examples are included for illustrative purposes.Consumer/Household Economics,

Mature-age labour force participation: trends, barriers, incentives, and future potential

The fiscal challenges of population ageing can be tackled in a number of ways. These include investing in capital and productivity of the smaller workforce, greater saving for retirement, higher migration, an active population policy, reducing benefits for the old, and/or encouraging and enabling them to work longer. This briefing focuses on the latter. It presents historical and international precedents for higher mature-age labour force participation rates in Australia, summarising available data as well as looking at the public policy response so far and the potential for further intervention.Executive Summary The fiscal challenges of population ageing can be tackled in a number of ways. These include investing in capital and productivity of the smaller workforce, greater saving for retirement, higher migration, an active population policy, reducing benefits for the old, and/or encouraging and enabling them to work longer. This briefing focuses on the latter. It presents historical and international precedents for higher mature-age labour force participation rates in Australia, summarising available data as well as looking at the public policy response so far and the potential for further intervention.The economic case for higher mature-age labour force participation is strong. A five percentage point increase to participation rates of 50-69 year olds is projected to be worth 2.4% of GDP in 2050. If all inactive people aged 55 and over who say they want to work did so, the participation rate for that group would increase six percentage points – also worth 2.4% of GDP. And if Australia had the same mature- age participation as New Zealand, GDP in 2012 would be 4% higher.The Australian Government has undertaken a number of measures to resolve ongoing barriers to employment for older Australians, but important issues remain.Institutional barriers to mature-age participation, resulting from the carrots and sticks that make up the tax, benefit and retirement income system, can be more amenable to policy intervention than those relating to barriers such as health and education. There is also evidence (e.g., from New Zealand) that changing system parameters relating to eligibility age can help.Yet it seems that too little thought has gone into the operation of eligibility ages in Australia. While pension age is increasing from 65 to 67, the eligibility age for Super will remain low, increasing from 55 to 60. At the same time, the age at which Super benefits are tax-free will remain at 60. In the absence of harmonisation of all eligibility ages, there is a case that the tax-free age be increased to 62, moving with the pension age, or to 65, moving with the Super access age.The briefing contextualises the discussion by making use of historic and international benchmarks. A set of scenarios is used to demonstrate the compositional effect of ageing and mature-age participation rates on total participation rates in the long term. Keeping all else equal, ageing would result in a 5 percentage point fall in total participation rates by 2050. If instead Australia were to achieve the higher mature- age rates seen in New Zealand, the fall would be only 2 percentage points. &nbsp