8 research outputs found
Universal temporal features of rankings in competitive sports and games
Many complex phenomena, from the selection of traits in biological systems to
hierarchy formation in social and economic entities, show signs of competition
and heterogeneous performance in the temporal evolution of their components,
which may eventually lead to stratified structures such as the wealth
distribution worldwide. However, it is still unclear whether the road to
hierarchical complexity is determined by the particularities of each phenomena,
or if there are universal mechanisms of stratification common to many systems.
Human sports and games, with their (varied but simplified) rules of competition
and measures of performance, serve as an ideal test bed to look for universal
features of hierarchy formation. With this goal in mind, we analyse here the
behaviour of players and team rankings over time for several sports and games.
Even though, for a given time, the distribution of performance ranks varies
across activities, we find statistical regularities in the dynamics of ranks.
Specifically the rank diversity, a measure of the number of elements occupying
a given rank over a length of time, has the same functional form in sports and
games as in languages, another system where competition is determined by the
use or disuse of grammatical structures. Our results support the notion that
hierarchical phenomena may be driven by the same underlying mechanisms of rank
formation, regardless of the nature of their components. Moreover, such
regularities can in principle be used to predict lifetimes of rank occupancy,
thus increasing our ability to forecast stratification in the presence of
competition
Scoring dynamics across professional team sports: tempo, balance and predictability
Despite growing interest in quantifying and modeling the scoring dynamics
within professional sports games, relative little is known about what patterns
or principles, if any, cut across different sports. Using a comprehensive data
set of scoring events in nearly a dozen consecutive seasons of college and
professional (American) football, professional hockey, and professional
basketball, we identify several common patterns in scoring dynamics. Across
these sports, scoring tempo---when scoring events occur---closely follows a
common Poisson process, with a sport-specific rate. Similarly, scoring
balance---how often a team wins an event---follows a common Bernoulli process,
with a parameter that effectively varies with the size of the lead. Combining
these processes within a generative model of gameplay, we find they both
reproduce the observed dynamics in all four sports and accurately predict game
outcomes. These results demonstrate common dynamical patterns underlying
within-game scoring dynamics across professional team sports, and suggest
specific mechanisms for driving them. We close with a brief discussion of the
implications of our results for several popular hypotheses about sports
dynamics.Comment: 18 pages, 8 figures, 4 tables, 2 appendice
Comparative Genomics of Ape Plasmodium Parasites Reveals Key Evolutionary Events Leading to Human Malaria
African great apes are infected with at least six species of P. falciparum-like parasites, including the ancestor of P. falciparum. Comparative studies of these parasites and P. falciparum (collectively termed the Laverania subgenus) will provide insight into the evolutionary origins of P. falciparum and identify genetic features that influence host tropism. Here we show that ape Laverania parasites do not serve as a recurrent source of human malaria and use novel enrichment techniques to derive near full-length genomes of close and distant relatives of P. falciparum. Using a combination of single template amplification and deep sequencing, we observe no evidence of ape Laverania infections in forest dwelling humans in Cameroon. This result supports previous findings that ape Laverania parasites are host specific and have successfully colonized humans only once. To understand the determinants of host specificity and identify genetic characteristics unique to P. falciparum, we develop a novel method for selective enrichment of Plasmodium DNA from sub-microscopically infected whole blood samples. We use this technique to enrich for Laverania genomic DNA from chimpanzee blood samples and assemble near full length genomes for both close (P. reichenowi) and distant (P. gaboni) relatives of P. falciparum. Comparative analyses of these genomes to P. falciparum identify features that are conserved across the Laverania subgenus, including the expansion of the FIKK kinases and the presence of var-like multigene families in all Laverania species. Our analyses also identify genetic features that are unique to P. falciparum, such as a very low within-species diversity and a complex evolutionary history of the essential invasion genes RH5 and CyRPA. This dissertation lays the groundwork for future comparative analyses of the Laverania subgenus including population genomic analyses of ape parasites and comparisons of P. falciparum to its ancestor, P. praefalciparum