752 research outputs found
Statistics of football dynamics
We investigate the dynamics of football matches. Our goal is to characterize
statistically the temporal sequence of ball movements in this collective sport
game, searching for traits of complex behavior. Data were collected over a
variety of matches in South American, European and World championships
throughout 2005 and 2006. We show that the statistics of ball touches presents
power-law tails and can be described by -gamma distributions. To explain
such behavior we propose a model that provides information on the
characteristics of football dynamics. Furthermore, we discuss the statistics of
duration of out-of-play intervals, not directly related to the previous
scenario.Comment: 7 page
q-exponential, Weibull, and q-Weibull distributions: an empirical analysis
In a comparative study, the q-exponential and Weibull distributions are
employed to investigate frequency distributions of basketball baskets, cyclone
victims, brand-name drugs by retail sales, and highway length. In order to
analyze the intermediate cases, a distribution, the q-Weibull one, which
interpolates the q-exponential and Weibull ones, is introduced. It is verified
that the basketball baskets distribution is well described by a q-exponential,
whereas the cyclone victims and brand-name drugs by retail sales ones are
better adjusted by a Weibull distribution. On the other hand, for highway
length the q-exponential and Weibull distributions do not give satisfactory
adjustment, being necessary to employ the q-Weibull distribution. Furthermore,
the introduction of this interpolating distribution gives an illumination from
the point of view of the stretched exponential against inverse power law
(q-exponential with q > 1) controversy.Comment: 6 pages, Latex. To appear in Physica
The Contribution of the Smectic-Nematic Interface to the Surface Energy
The contribution of the smectic-nematic interface to the surface energy of a
nematic liquid crystal sample is analyzed. By means of a simple model it is
shown that the surface energy depends on the thickness of the region over which
the transition smectic-nematic takes place. For perfectly flat substrates this
thickness is of the order of the correlation length entering in the transition.
An estimate of this contribution shows that it is greater than the one arising
from the nematic-substrate interaction. Moreover, it is also shown that the
surface energy determined in this way presents a non-monotonic behavior with
the temperature.Comment: 10 pages, revte
Tracking the source of the hepatitis B virus-specific CD8 T cells during lamivudine treatment
Lamivudine treatment in chronic hepatitis B leads to the reconstitution of virus-specific T cells in the circulation, but it is not clear whether this is the preferential result of T cell efflux from the liver or lymph nodes. To address this question, the frequency and function of liver-, lymph node-, and blood-derived hepatitis B virus (HBV)-specific CD8 T cells were analyzed in patients treated with lamivudine and undergoing liver transplantation. HBV-specific CD8 T cells, identified in portal lymph nodes, were able to expand in vitro after antigen-specific stimulation and displayed a heterogeneous profile of cytokine production. These findings suggest that the peripherally reconstituted HBV-specific CD8 T cells can originate from precursor cells within lymph nodes
On the dynamics of bubbles in boiling water
We investigate the dynamics of many interacting bubbles in boiling water by
using a laser scattering experiment. Specifically, we analyze the temporal
variations of a laser intensity signal which passed through a sample of boiling
water. Our empirical results indicate that the return interval distribution of
the laser signal does not follow an exponential distribution; contrariwise, a
heavy-tailed distribution has been found. Additionally, we compare the
experimental results with those obtained from a minimalist phenomenological
model, finding a good agreement.Comment: Accepted for publication in Chaos, Solitons & Fractal
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