Within-population variation in ejaculate characteristics in a prolonged breeder, Peron's tree frog, Litoria peronii

Sperm number is often a good predictor of success in sperm competition; however, it has become increasingly clear that, for some species, variation in probability of paternity cannot be explained by sperm number alone. Intraspecific variation in ejaculate characteristics, such as the number of viable sperm and sperm longevity, may play an equally important role in determining fertilization success. Here, we assess variation among ejaculates in three factors that may contribute to fertilization success (number of sperm per ejaculate, viability, and longevity), in a population of Peron’s tree frog (Litoria peronii). We detected large variation among males in the number of sperm per ejaculate and the proportion of viable sperm within ejaculates, which could not be explained by variation in either male size or body condition. However, the proportion of viable sperm released by males increased over the season. Finally, we assessed sperm longevity (proportion viable sperm determined using a dual-fluorochrome vital dye) at two different temperatures. At 23°C, on average, 75% of sperm remained viable after 2 h, but there were significant differences amongst males with the percentage of viable sperm ranging from 43% to 95%. For sperm incubated at 4°C, ejaculates varied fivefold in sperm longevity with some males having 50% viable sperm after 5 days. Our data suggest that ejaculate characteristics (sperm number, viability, and longevity) vary widely in Peron’s tree frog and may therefore play an important role in determining siring success both in the presence and absence of sperm competition. We discuss the results in relation to selection on ejaculate traits via natural and sexual selection in this and other amphibians.

Male and female effects on fertilization success and offspring viability in the Peron's tree frog, Litoria peronii

There is increasing theoretical and empirical evidence that genetic compatibility among partners is an important determinant of fertilization success and offspring viability. In amphibians, females often actively choose partners from among a variety of males and polyandry is common. Genetic compatibility among partners may therefore be an important determinant of fertilization success and offspring viability in some amphibians. Amphibians also show some of the highest levels of genetic differentiation among neighbouring populations known in vertebrates, and as such, populations may have evolved different co-adapted gene complexes. This means that offspring from among-population crosses may have reduced fitness. It is therefore essential to understand to what extent crossings between and within populations may interfere with successful fertilization and offspring viability. Here, we test whether crossing individuals within and between two different populations of the Australian Peron's tree frog (Litoria peronii) using artificial fertilizations affect fertilization success and offspring viability. Fertilization success per se is strongly influenced by male identity, which is likely to depend at least to some extent on the experimental procedure (e.g. resulting in variation in sperm number per ejaculate), whereas there was no fertilization effect of female identity. More importantly, male and female identity, independently of each other, explained significant variation in offspring viability, whereas no such effect could be linked to population of origin. Thus, our experiments suggest that crossing populations may not always be the most significant factor affecting fertilization success or offspring viability, but may be more influenced by the genetic quality or the genetic compatibility of partners.

A stochastic derivation of the ratio form of contest success functions

This note provides a distribution-based justification for the ratio form of contest success functions (CSFs), in which a player’s success depends positively on her effort relative to that of her opponents. I show that the inverse exponential distribution of the random shocks yields the ratio form. Extending this approach to asymmetric contests, I also derive an asymmetric ratio form of CSFs.

Critical success factors for the requirements engineering process, with reference to quality management of information systems development

Preliminary research into the critical factors associated with software development/implementation identified three dimensions for successful implementation based on alignment of the requirements engineering process with business needs, change management process and quality of the implementation process. Research results demonstrate the link between the conceptual model for process quality and the process management attributes determined during the research.

Key success factors in real-time industrial system assurance

The thesis analyses the issues of implementing real-time software systems in industrial applications. The benefit is the development of the Integrated Mega Project Development Model, to improve the effectiveness of planning and timely delivery of software, the quality of the delivered software and reducing problems associated with integrating software systems.

Organising inclusion work : key factors for success

This paper presents the findings of research conducted by Scope in 2007-2009. It proposes a way of categorising the dominant modes or orientations to inclusion work in the disability sector in Australia and identifies the barriers and enablers to it. The research engaged with seventeen ‘inclusion workers’ or managers in Victoria and Perth, Western Australia and sought examples of successful practice along with the ingredients of success, and outcomes of the work. Coincidently, the majority of examples provided related to inclusion work with people with intellectual disability, and a minority of these relating to people with severe intellectual disability. This data was analysed to identify key organisational factors required for successful inclusion work. Most importantly, respondents were also asked to identify the outcomes of inclusion work for individuals with a disability and their families, as well as for services, and for the communities with whom they engaged. The paper offers a way of conceptualising the breadth of inclusion work, including work focused on presence and participation, as well as the larger scale activities of social engineering or social change. The paper presents key ingredients for successful organisational approaches to such work.

On a class of contest success functions

In this article, I analyze a class of contest success functions (CSFs) that satisfy Luce's Choice Axiom. I show that the functional forms of these CSFs can be fully identified if they are characterized by a partial differential equation (PDE), which has several intuitive economic interpretations. This POE approach provides foundations for popular CSFs and their generalizations.

Positive conditions for success

This paper reflects material presented by the authors of this article1 at a workshop presented at the Cambridge International Symposium on Economic Crime at Jesus College Cambridge between September 5 and 12, 2010. The impetus for this topic came from Neil Jensen, who had completed a significant body of research on compliance by FATF and non-FATF members with the 40 recommendations and the nine special recommendations.

Timing of immune escape linked to success or failure of vaccination

Successful vaccination against HIV should limit viral replication sufficiently to prevent the emergence of viral immune escape mutations. Broadly directed immunity is likely to be required to limit opportunities for immune escape variants to flourish. We studied the emergence of an SIV Gag cytotoxic T cell immune escape variant in pigtail macaques expressing the Mane-A*10 MHC I allele using a quantitative RT-PCR to measure viral loads of escape and wild type variants. Animals receiving whole Gag expressing vaccines completely controlled an SIV_mac251 challenge, had broader CTL responses and exhibited minimal CTL escape. In contrast, animals vaccinated with only a single CTL epitope and challenged with the same SIV_mac251 stock had high levels of viral replication and rapid CTL escape. Unvaccinated naïve animals exhibited a slower emergence of immune escape variants. Thus narrowly directed vaccination against a single epitope resulted in rapid immune escape and viral levels equivalent to that of naïve unvaccinated animals. These results emphasize the importance of inducing broadly directed HIV-specific immunity that effectively quashes early viral replication and limits the generation of immune escape variants. This has important implications for the selection of HIV vaccines for expanded human trials.

Critical success factors for stakeholder management: construction practitioners' perspectives

Although various factors have been identified as important for accomplishing successful stakeholder management, few studies appear to have undertaken a comparative analysis of practitioners’ views on the relative importance of critical success factors (CSFs) for stakeholder management in construction projects. In an attempt to fill this research gap, a questionnaire survey was conducted in Hong Kong to collect the opinions of construction practitioners regarding the relative importance of CSFs for stakeholder management. Findings from this study show that all 15 selected CSFs are regarded as critical by most respondents for the success of stakeholder management in construction projects. The factor regarding social responsibilities is considered most important for managing stakeholders. Although correlations between CSFs and types of projects and organizations were statistically significant, these were not particularly strong. Also, even though there is a general consensus on the rankings of the CSFs among different respondents, the detailed pairwise comparisons actually show the existence of a few differences in perceptions on the relative importance of the CSFs. Therefore, the working priorities of project managers for managing stakeholders are context specific, depending on the nature, client sector, and cost of the project, and also on their organizations and management levels in the organization. These findings should help project managers become more aware of their responsibilities and the relative importance of issues for management stakeholders.

Exploring critical success factors for stakeholder management in construction projects

With a focus on different aspects of stakeholder management, various sets of critical success factors (CSFs) have been suggested in the literature. It is crucial to explore the relative importance and groupings of these factors. This paper aims to identify CSFs associated with stakeholder management in construction projects, and explore their ranking and underlying relationship. 15 CSFs were identified through a literature review, and consolidated by interviews and pilot studies with professionals in construction industry. A questionnaire instrument containing these 15 CSFs was sent out to project managers in Hong Kong, and 183 completed questionnaires were retrieved. The top three ranked factors for stakeholder management were "managing stakeholders with social responsibilities", "assessing the stakeholders' needs and constraints to the project", and "communicating with stakeholders properly and frequently". Using factor analysis and considering the high importance of the factor "managing stakeholders with social responsibilities", the 15 CSFs were grouped into five dimensions namely, precondition factor, stakeholder estimation, information inputs, decision making, and sustainable support. All these five groupings and their relationship were included in a framework for successful stakeholder management in construction projects. These findings help to clarify what the high prioritized factors are, and could also be used as an assessment tool to evaluate the performance of stakeholder management and thus help to identify areas for improvement.