Mothers adjust offspring sex to match the quality of the rearing environment

Theory predicts that mothers should adjust offspring sex ratios when the expected fitness gains or rearing costs differ between sons and daughters. Recent empirical work has linked biased offspring sex ratios to environmental quality via changes in relative maternal condition. It is unclear, however, whether females can manipulate offspring sex ratios in response to environmental quality alone (i.e. independent of maternal condition). We used a balanced within-female experimental design (i.e. females bred on both low- and high-quality diets) to show that female parrot finches (Erythrura trichroa) manipulate primary offspring sex ratios to the quality of the rearing environment, and not to their own body condition and health. Individual females produced an unbiased sex ratio on high-quality diets, but over-produced sons in poor dietary conditions, even though they maintained similar condition between diet treatments. Despite the lack of sexual size dimorphism, such sex ratio adjustment is in line with predictions from sex allocation theory because nutritionally stressed foster sons were healthier, grew faster and were more likely to survive than daughters. These findings suggest that mothers may adaptively adjust offspring sex ratios to optimally match their offspring to the expected quality of the rearing environment.

Influence of field position and phase of play on the physical demands of match-play in professional rugby league forwards

This article describes the utilisation of an unsupervised machine learning technique and statistical approaches (e.g., the Kolmogorov-Smirnov test) that assist cycling experts in the crucial decision-making processes for athlete selection, training, and strategic planning in the track cycling Omnium. The Omnium is a multi-event competition that will be included in the summer Olympic Games for the first time in 2012. Presently, selectors and cycling coaches make decisions based on experience and intuition. They rarely have access to objective data. We analysed both the old five-event (first raced internationally in 2007) and new six-event (first raced internationally in 2011) Omniums and found that the addition of the elimination race component to the Omnium has, contrary to expectations, not favoured track endurance riders. We analysed the Omnium data and also determined the inter-relationships between different individual events as well as between those events and the final standings of riders. In further analysis, we found that there is no maximum ranking (poorest performance) in each individual event that riders can afford whilst still winning a medal. We also found the required times for riders to finish the timed components that are necessary for medal winning. The results of this study consider the scoring system of the Omnium and inform decision-making toward successful participation in future major Omnium competitions.

Short-term impacts of the cricket match performances on national share markets – a case study of India and Australia

We investigate the impact that investor sentiment can have on stock market following performances by the national cricket teams of India and Australia in one-day cricket matches from 1990 to 2011. Motivated by previous findings of cricket’s impacts on stock markets, this study expands on previous research by investigating whether performances of individuals within the teams can also have an impact on their respective leading stock indices. Using an event study, we find no evidence of player or team performances significantly impacting the stock or futures markets. However, we find evidence of a ‘mood effect’ of poor performance by key players of national cricket teams in terms of significant drop in trading volumes in the following day. Our research poses and statistically examines some interesting questions and opens up the field for further research on this intriguing topic of sporting event impacts on national economies.

Predictors of individual player match performance in junior Australian football

PURPOSE: Player match statistics in junior Australian football (AF) are not well documented while contributors to success are poorly understood. A clearer understanding of the relationships between fitness and skill in younger age players participating at the foundation level of the performance pathway in AF has implications for the development of coaching priorities (e.g., physical or technical). The aim of this study was to investigate the relationships between indices of fitness (speed, power and endurance) and skill (coach rating) on player performance (disposals and effective disposals) in junior AF. METHODS: Junior male AF players (n = 156, 10 - 15 years old) were recruited from 12 teams of a single amateur recreational AF club located in metropolitan Victoria. All players were tested for fitness (20 m sprint, vertical jump, 20 m shuttle run) and rated by their coach on a 6-point Likert scale for skill (within a team in comparison to their teammates). Player performance was assessed during a single match in which disposals and their effectiveness were coded from a video recording. RESULTS: Coach rating of skill displayed the strongest correlations and combined with 20 m shuttle test showed a good ability to predict both disposals and the number of effective disposals. None of the skill or fitness attributes adequately explained the percentage of effective disposals. The influence of team did not meaningfully contribute to the performance of any of the models. CONCLUSION: Skill development should be considered a high priority by coaches in junior AF.

Evaluation of the components of production of the ricinus according of rates of calcareous rock and match

The soil of the Paraiba, in generality, are acid and with low levels of available match, seriously limiting the income of the plants. A research in vegetation house was lead, with the objective to evaluate doses of calcareous soil and match in the culture of ricinus. The treatments had been composites for five levels of match: 0.0; 80; 160; 240 and 360 kg ha(-1) of P(2)O(5) and four dosis of calcareous rock: 0.0; 2.5; 3.5 and 4.5 t ha(-1) in experimental delineation of blocks casualized with 4 factorial project x 3 (four levels of match and three doses of calcareous soil) more two treatments you add zero of match (0.0 P(2)O(5): 2,5 t ha(-1) of calcareous soil) and calcareous soil zero (240 P(2)O(5): 0.0 t ha(-1) of calcareous soil), with three repetitions. The calcareous soil reduced the acidity of the ground and effect of the application of the match (>= 80 kg ha(-1) of P(2)O(5)) in the presence of the collagen (>= 2.5 t ha(-1) of CaCO(3)) with of the calcareous soil (>= 2.5 t ha(-1) of CaCO(3)) in the presence of the match was not verified well (>= 80 kg ha(-1) of P(2)O(5)). The match applied in the absence of the calcareous soil was limited to the income of the culture of what the calcareous soil in the absence of the match.

The workload and plasma ion concentration in a training match session of high-goal (elite) polo ponies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The influence of fluid ingestion on performance of soccer players during a match

The purpose of this study was to verify the effects of a carbohydrate-electrolyte drink on soccer performance. Twenty soccer players volunteered to participate in the study. Players were allocated to two assigned trials according to their positional roles in the team: CHO group (ingesting a 6% carbohydrate-electrolyte solution at regular 15 minutes intervals) and NCHO (ingesting no fluid) during 75 min on-field soccer game. During the trials, body mass loss, heart rate, time spent running, number of sprints and core temperature were measured. There were statistically significant changes (p < 0.05) in body mass loss (CHO: 1.14 ± 0.37 kg vs. NCHO: 1.75 ± 0.47 kg) and number of sprints performed (CHO: 14.70 ± 4.38 vs. NCHO: 10.70 ± 5.80) between groups. The main finding of the present study indicates that supplementation with a carbohydrate-electrolyte drink during a soccer match is beneficial in helping to prevent deterioration in performance. © Journal of Sports Science and Medicine (2004).