Multivariate Geostatistical Modeling and Risk Analysis of Beach Litter: A Case Study of Playa Blanca Beach, Chile.

Beach litter is a worldwide problem that has several negative effects. A first step in preventing an environmental hazard is to determine and model the level of contamination. In this paper, geostatistical simulation is used to model two main forms of beach litter (cigarette butts and sharp items) in one of the most contaminated beaches in Antofagasta, Chile. A hundred realizations of cigarette butts and broken glass are generated to emulate their joint spatial distribution. The simulation results are used to classify the beach into different areas with respect to the risk of injury by broken glass and the level of contamination by cigarette butts. The models obtained can be used by local authorities in beach clean-up programs and by visitors to beaches in choosing the safest and cleanest areas. The results demonstrate the capability of geostatistical simulation algorithms to model different types of beach litter.

Ball Recovery Consistency as a Performance Indicator in Elite Soccer / Consistência na recuperação da bola como indicador de desempenho no futebol

Abstract In soccer, an attack begins with ball recovery. Therefore, the consistency of this performance indicator during a match and its balanced distribution in the field zones can be one of the distinct characteristics of successful soccer teams. This study aims to investigate the performance consistency of ball recovery during a match within several time periods (6 periods of 15 min) and zones (four zones). To this end, observational methodology and software Focus X2 were adopted to evaluate 28 matches of semi-final teams at FIFA 2014 including Germany, Argentina, Netherlands, and Brazil in terms of ball recovery frequency. In total, 3222 performances were recorded. All teams in each match and in whole competition had homogeneity of distribution of ball recovery during the time periods (χ23 =1.597, p=0.66). The results of time-zone evaluation indicated that Netherlands and Brazil teams did not have performance consistency on all field zones (χ215=31.29, p=0.008 and χ215 =37.53, p=0.001, respectively). Most ball recoveries were made in the defensive and middle-defensive zones in accordance with modern soccer. It was found that for a soccer team to be successful, it requires a space distribution of experienced players in the field, which leads to power balance for redesigning a team to be offensive in all zones.

Resumo No futebol, um ataque começa com recuperação de bola. Por isso, a consistência desse indicador de desempenho pode ser uma das características distintas para o sucesso das equipes de futebol. Este estudo tem como objetivo investigar a consistência da recuperação da bola no desempenho durante um jogo dentro de vários períodos de tempo (6 períodos de 15 min) e zonas (quatro zonas). Empegou-se o software Focus X2 para avaliar 28 partidas das equipes que chegaram às semifinais do mundial da FIFA de 2014 (Alemanha, Argentina, Holanda e Brasil) em termos de frequência de recuperação de bola. No total, foram registados 3,222 desempenhos. Todas as equipes em cada jogo e em toda competição teve a homogeneidade da distribuição de recuperação de bola durante os períodos de tempo (χ23 = 1.597, p = 0,66). Os resultados indicaram que as equipes da Holanda e do Brasil não tinham consistência de desempenho em todas as zonas de campo (χ215 = 31,29, p = 0,008 e χ215 = 37,53, p = 0,001, respectivamente). A maioria das recuperações de bola foi feita na zona defensiva e na zona meio-defensivo. Verificou-se que para um time de futebol ser bem sucedido é necessário distribuição espacial dos jogadores mais experientes no campo, o que leva ao equilíbrio da equipe para ser ofensivo em todas as zonas.