Visual regulation during competition long jumps and run-throughs

Previous investigators have reported that the ability of long jumpers to visually regulate their stride pattern as they approach the take-off board is critical for success. The importance of visual regulation (VA) on long jump (LJ) distance was assessed in six national-class competitors during two simulated competitions. Linear regression analyses indicated that increased VR contributes to a high average approach velocity -a key predictor of LJ distance. Early VA enabled the athletes to make small systematic adjustments to stride length in order to strike the board in an optimal take-off position, without sacrificing approach velocity. Athletes practice their LJ approach by repeating the stride pattern of the approach, but without the take-off. The current study established that these 'run-throughs' (AT) don't accurately simulate the VR characteristics of a LJ approach. One strategy to increase the VA required during RT's may be to place additional targets across the runway for the athletes to negotiate whilst approaching the take-off board, without compromising approach velocity.

Visual guidance during competition performance and run-through training in long jumping

To ensure precise foot placement on the take-off board, long jumpers visually regulate their stride pattern during their run-up. A relationship between how much visual guidance they use and the horizontal distance they jump has not, however, been quantified. Run-up precision is often practiced using run-throughs, which exclude the take-off and, therefore, the high physical stress of the complete long jump. The validity with which this common training method simulates the long jump approach remains, however, to be verified. Four state-standard long jumpers and two heptathletes completed two sessions, each comprising six run-throughs and six competition long jumps. A 50 Hz video camera was manually panned from an elevated platform to film each trial, to enable subsequent gait characteristic evaluations. Linear regression analyses identified that a longer visual regulation phase, measured in time, distance or number of strides, was a key predictor of long jump distance. The number of strides that were visually regulated during the long jump approach was, accordingly, positively correlated with long jump distance (r = 0.67, p = 0.001). The amount of visual regulation used during run-throughs was, however, less than half (p = 0.001) of that observed during long jump approaches. Our results should compel long jump coaches to supplement run-through training with additional visual guidance exercises, to encourage their athletes to visually regulate more of their long jump approach.

Ecology of Pittosporum undulatum Vent. (Pittosporaceae) an environmental weed in south east Australia

Pittosporum undulatum Vent. (Sweet Pittosporum) is a densely foliaged tall shrub or small tree, native to the wet forests of south east Australia, This species now functions as a serious environmental weed in a range of habitats in Australia and on other continents and islands throughout the temperate, sub-tropical and tropical zones. This study investigated some of the ecological causes and consequences of P. undulatum invasion across a range of habitat types in south east Australia. Key aspects of P. undulatum biology and ecology investigated in the current study include; patterns of morphological variation across the range of habitats occupied (as a measure of the species’ plasticity), dispersal ecology and seed germinability, population structure and spatial pattern, community relationships and the ecological impacts of invasion. Phenotypic plasticity is considerable in P. undulatum. No clear patterns of geographic variation emerged from a study of leaf morphological attributes across the current range of this species on mainland south east Australia. The pattern of morphological variation is particularly complex in Victoria, where the invasion of this species is most advanced. The species’ adaptability to a range of environments and environmental conditions will likely promote further range expansion. The abundant winter fruit crop produced by functionally female P. undulatum plants attracts a suite of generalist opportunistic frugivores, which feed on P. undulatum fruits and seeds at various stages of fruit dehiscence, thereby enhancing dispersal opportunities for this species. P. undulatum seed collected from natural and invasive populations, at two stages of fruit maturity and from the scats and pellets of dispersal agents, displayed high germinability. European Blackbirds and Pied Currawongs are implicated as the main avian dispersal agents of P undulatum in south east Australia. The broader ecological implications of developing relationships between invasive fleshy-fruited bird-dispersed plant species and adaptive frugivores are likely to be considerable. The distribution of P. undulatutn seedlings was significantly negatively correlated with adult conspecifics and significantly positively correlated with trees and shrubs of other genera. This pattern reflects the importance of both firugivorous dispersal agents and the species’ germination and establishment requirements, in shaping the contagious distribution pattern typical of this species. These analyses suggest that recruitment opportunities for conspecific seedlings are limited beneath the canopy of adult conspecifics. Densities of P. undulatum were on average, 2.7 times higher in invaded populations, compared to the natural populations sampled. A male-bias was evident in all populations and no relationships between reproductive activity and the density of seedlings and juveniles were evident. Invading populations of P. undulatum impose substantial changes on ecosystem-level properties and functions. Mean species richness and cover-abundance declined notably once P. undulatum cover-abundance exceeded 20% at the invaded sites and 60% at the natural sites sampled. The natural communities sampled displayed comparatively greater resilience to the competitive effects of P. undulatum, but community attributes were affected at high densities and cover-abundance of this species. The cover-abundance of herbs and grasses declined most substantially with increasing P. undulatum at invaded sites, whereas, at the natural sites sampled, the species’ structural analogues appeared to be most affected by increasing P. undulatum cover-abundance. This study has demonstrated that the ecological consequences of P. undulatum population expansion are substantial and contribute to changes in the composition and successional trajectory of affected communities. These processes ultimately lead to the loss and simplification of biodiversity values and the homogenisation of affected habitats. P. undulatum has the potential to emerge as one of south east Australia's most serious environmental weed species.

Sperm competition and offspring viability at hybridization in Australian tree frogs, Litoria peronii and L. tyleri

Hybridization between closely related species often leads to reduced viability or fertility of offspring. Complete failure of hybrid offspring (post-zygotic hybrid incompatibilities) may have an important role in maintaining the integrity of reproductive barriers between closely related species. We show elsewhere that in Peron's tree frog, Litoria peronii, males more closely related to a female sire more offspring in sperm competition with a less related rival male. Observations of rare 'phenotypic intermediate' males between L. peronii and the closely related L. tyleri made us suggest that these relatedness effects on siring success may be because of selection arising from risks of costly hybridization between the two species. Here, we test this hypothesis in an extensive sperm competition experiment, which shows that there is no effect of species identity on probability of fertilization in sperm competition trials controlling for sperm concentration and sperm viability. Instead, there was a close agreement between a male's siring success in isolation with a female and his siring success with the same female in competition with a rival male regardless of species identity. Offspring viability and survival, however, were strongly influenced by species identity. Over a 14-day period, hybrid offspring suffered increasing mortality and developed more malformations and an obvious inability to swim and right themselves, leading to compromised probability of survival. Thus, hybridization in these sympatric tree frogs does not compromise fertilization but has a strong impact on offspring viability and opportunity for reinforcement selection on mate choice for conspecific partners.

A microscopic competition model and its dynamics analysis on network attacks

Modeling network traffic has been a critical task in the development of Internet. Attacks and defense are prevalent in the current Internet. Traditional network models such as Poisson-related models do not consider the competition behaviors between the attack and defense parties. In this paper, we present a microscopic competition model to analyze the dynamics among the nodes, benign or malicious, connected to a router, which compete for the bandwidth. The dynamics analysis demonstrates that the model can well describe the competition behavior among normal users and attackers. Based on this model, an anomaly attack detection method is presented. The method is based on the adaptive resonance theory, which is used to learn the model by normal traffic data. The evaluation shows that it can effectively detect the network attacks.

Compensatory growth in an aquatic plant mediates exploitative competition between seasonally tied herbivores

The degree to which vertebrate herbivores exploitatively compete for the same food plant may depend on the level of compensatory plant growth. Such compensation is higher when there is reduced density-dependent competition in plants after herbivore damage. Whether there is relief from competition may largely be determined by the life-history stage of plants under herbivory. Such stage-specific compensation may apply to seasonal herbivory on the clonal aquatic plant sago pondweed (Potamogeton pectinatus L.). It winters in sediments of shallow lakes as tubers that are foraged upon by Bewick's Swans (Cygnus columbianus bewickii Yarrell), whereas aboveground biomass in summer is mostly consumed by ducks, coots, and Mute Swans. Here, tuber predation may be compensated due to diminished negative density dependence in the next growth season. However, we expected lower compensation to summer herbivory by waterfowl and fish as density of aboveground biomass in summer is closely related to photosynthetic carbon fixation. In a factorial exclosure study we simultaneously investigated (1) the effect of summer herbivory on aboveground biomass and autumn tuber biomass and (2) the effect of tuber predation in autumn on aboveground biomass and tuber biomass a year later. Summer herbivory strongly influenced belowground tuber biomass in autumn, limiting food availability to Bewick's Swans. In contrast, tuber predation in autumn by Bewick's Swans had a limited and variable effect on P. pectinatus biomass in the following growth season. Whereas relief from negative density dependence largely eliminates effects of belowground herbivory by swans, aboveground herbivory in summer limits both above- and belowground plant biomass. Hence, there was an asymmetry in exploitative competition, with herbivores in summer reducing food availability for belowground herbivores in autumn, but not the other way around.

Balancing act : competition and cooperation in US Asia-Pacific regionalism

While the United States is an important Asia-Pacific actor, its engagement with the region is complex and often difficult. Not only must US regionalism balance the diverse requirements of an ambitious policy agenda, but also US policy norms and priorities often clash with those of other regional actors. This has important implications for the capacity of the United States to provide regional leadership. Recent years have seen growing policy convergence between the United States and other Asia-Pacific actors, particularly in economic terms, but US regionalism continues to feature competition alongside collaboration.

Separating the influences of environment and species interactions on patterns of distribution and abundance : competition between large herbivores

* 1
Much recent research has focused on the use of species distribution models to explore the influence(s) of environment (predominantly climate) on species’ distributions. A weakness of this approach is that it typically does not consider effects of biotic interactions, including competition, on species’ distributions.
* 2
Here we identify and quantify the contribution of environmental factors relative to biotic factors (interspecific competition) to the distribution and abundance of three large, wide-ranging herbivores, the antilopine wallaroo (Macropus antilopinus), common wallaroo (Macropus robustus) and eastern grey kangaroo (Macropus giganteus), across an extensive zone of sympatry in tropical northern Australia.
* 3
To assess the importance of competition relative to habitat features, we constructed models of abundance for each species incorporating habitat only and habitat + the abundance of the other species, and compared their respective likelihoods using Akaike's information criterion. We further assessed the importance of variables predicting abundance across models for each species.
* 4
The best-supported models of antilopine wallaroo and eastern grey kangaroo abundance included both habitat and the abundance of the other species, providing evidence of interspecific competition. Contrastingly, models of common wallaroo abundance were largely influenced by climate and not the abundance of other species. The abundance of antilopine wallaroos was most influenced by water availability, eastern grey kangaroo abundance and the frequency of late season fires. The abundance of eastern grey kangaroos was most influenced by aspects of climate, antilopine wallaroo abundance and a measure of cattle abundance.
* 5
Our study demonstrates that where census and habitat data are available, it is possible to reveal species’ interactions (and measure their relative strength and direction) between large, mobile and/or widely-distributed species for which competition is difficult to demonstrate experimentally. This allows discrimination of the influences of environmental factors and species interactions on species’ distributions, and should therefore improve the predictive power of species distribution models.

The increasing criminalization of economic law : a competition law perspective

Purpose – The purpose of this paper is to examine the trend towards the criminalization of hard core cartel conduct and to consider the appropriateness and effectiveness of extending the criminal law to this conduct. In addition, it will consider some of the legal implications, including the exposure of directors of companies to potential racketeering charges.
Design/methodology/approach – The paper first examines cartel theory and the justification for prohibition. The paper then identifies the emerging trend toward criminalization of hard core cartel conduct, followed by an assessment of potential justifications for criminalization. Implications of criminalization, including the potential impact of organized crime legislation on offenders and regulators, will then be considered.
Findings – There is a clear trend towards the criminalization of hard core cartels. The paper argues that this trend is appropriate, both because of the moral culpability it attracts and because of its potential to enhance general deterrence. The paper also argues that cartel conduct, in jurisdictions in which it is criminalized, will constitute “organized crime” as defined in the Palermo Convention and, as such, expose participants to potential money laundering and asset forfeiture consequences.
Originality/value – This paper is of value to governments and regulators considering adoption or implementation of a criminal cartel regime and to practitioners in advising clients about potential consequences of cartel conduct within a criminal regime.

Software developer policies : economics and s 46 of the Competition and Consumer Act 2010

This article considers the impact of developer policies that hinder or restrict cross platform application development. We suggest that policies that hinder or restrict cross platform development have the potential to erode competition within the market for smartphones. The article also considers the relevance of dominance measures in software markets, arguing that conventional economic approaches may not be applicable. Furthermore, while most monitoring activities tend to focus primarily on protection of consumers, the article points out that modern electronic/information technology markets are multi-sided and there is a need for monitoring of practices designed to attract and retain the favour of developers. While the article is written in the context and application of the applicable Australian legislation, this being s 46 of the Competition and Consumer Act 2010 (Cth), our findings are equally relevant to other jurisdictions.

Competition : the heart and soul of sport management

Understanding competition is central to the task of strategy formulation and implementation and it is the link between competition and strategy that was explored in the 2011 Dr. Earle F. Zeigler Lecture. It was argued that strategy, given its centrality to organizational phenomena, and strategy research in particular, provides rich and diverse competitive contexts with the potential to reveal some of the unique properties of sport management. To ascertain the prevalence of sport-related strategy research, three sport management journals were subject to content analysis to identify published manuscripts related to strategy. Before presenting the results, the Lecture considered competition on and off the field, the origins of competitive behavior in sport management and a brief review of the major research themes in the generic strategic management literature. Results revealed that 20 (2.5%) of the 805 manuscripts published in the three journals were strategy focused. Research themes and contexts were presented as well as a bibliometric analysis of the reference lists of the 20 identified strategy manuscripts. This analysis highlighted the journals that are influencing published sport management strategy-related research. It was concluded that strategy research specific to sport management has been sparse to date, yet the role of strategy formulation is central to the role of management and should also be central to sport management scholarship.