7,235 research outputs found
Complexity-Entropy Causality Plane as a Complexity Measure for Two-dimensional Patterns
Complexity measures are essential to understand complex systems and there are
numerous definitions to analyze one-dimensional data. However, extensions of
these approaches to two or higher-dimensional data, such as images, are much
less common. Here, we reduce this gap by applying the ideas of the permutation
entropy combined with a relative entropic index. We build up a numerical
procedure that can be easily implemented to evaluate the complexity of two or
higher-dimensional patterns. We work out this method in different scenarios
where numerical experiments and empirical data were taken into account.
Specifically, we have applied the method to i) fractal landscapes generated
numerically where we compare our measures with the Hurst exponent; ii) liquid
crystal textures where nematic-isotropic-nematic phase transitions were
properly identified; iii) 12 characteristic textures of liquid crystals where
the different values show that the method can distinguish different phases; iv)
and Ising surfaces where our method identified the critical temperature and
also proved to be stable.Comment: Accepted for publication in PLoS On
Universal patterns in sound amplitudes of songs and music genres
We report a statistical analysis over more than eight thousand songs.
Specifically, we investigate the probability distribution of the normalized
sound amplitudes. Our findings seems to suggest a universal form of
distribution which presents a good agreement with a one-parameter stretched
Gaussian. We also argue that this parameter can give information on music
complexity, and consequently it goes towards classifying songs as well as music
genres. Additionally, we present statistical evidences that correlation aspects
of the songs are directly related with the non-Gaussian nature of their sound
amplitude distributions.Comment: Accepted for publication as a Brief Report in Physical Review
Cross-national differences in risk preference and individual deprivation: a large-scale empirical study
Although risk-taking has been found to be associated with economic deprivation, there is little evidence on whether the relation between individual deprivation and propensity for risk-taking is inherent to all individuals, or varies across cultural contexts. Consequently, the present study investigated the interaction effects of macroeconomic factors [Gross Domestic Product (GDP) per capita and Human Development Index (HDI)] in the relationship between individual deprivation and propensity for risk-taking using the World Values Survey data from 58 countries (N = 87,223). On average, individuals in more developed countries (higher HDI) had less propensity for risk-taking. In contradiction to this, the positive association between individual deprivation and risk-taking was stronger in countries with higher GDP per capita. The present study suggests that the association between individual deprivation and propensity for risk-taking varies with environmental variables assessing the socio-economic development of a country
Hypothalamo-pituitary axis and puberty
Puberty is a complex process that culminates in the acquisition of psychophysical maturity and reproductive capacity. This elaborate and fascinating process marks the end of childhood. Behind it lies a complex, genetically mediated neuroendocrine mechanism through which the gonads are activated thanks to the fine balance between central inhibitory and stimulating neuromodulators and hormones with both central and peripheral action. The onset of puberty involves the reactivation of the hypothalamic-pituitary-gonadal (HPG) axis, supported by the initial “kiss” between kisspeptin and the hypothalamic neurons that secrete GnRH (the GnRH “pulse generator”). This pulsatile production of GnRH is followed by a rise in LH and, consequently, in gonadal steroids. The onset of puberty varies naturally between individuals, and especially between males and females, in the latter of whom it is typically earlier. However, pathological variations, namely precocious and delayed puberty, are also possible. This article reviews the scientific literature on the physiological mechanisms of puberty and the main pathophysiological aspects of its onset
Milky spots reactions to schistosomal mansoni infection
Milky spots (MS), considered by the authors as a Coelomatic Lympho-myelopoietic Organ (CLMO), present a strong reactivity during experimental schistosomal mansoni infection, characterized by an increase of lymphocytes, macrophages, plasmocytes, mast cells, neutrophils and expression of eosinophil metaplasia. Intraperitoneal injection of purified Schistosoma mansoni (Sm) eggs provoked a rise in the number and size of MS, which developed the sessile marginal and pedunculated types. The authors conclude that egg antigens are, at least partially, responsible for MS reactivity during Sm infection
STUDY OF THE O-18+Ni-64 TWO-NEUTRON TRANSFER REACTION AT 84 MeV BY MAGNEX
A study of the two-neutron transfer reaction of the O-18 + Ni-64 system at 84 MeV incident energy to the ground and first 2(+) excited state of the residual Ni-66 nucleus is presented. The experiment was performed at the INFN-LNS (Italy) by using the large acceptance MAGNEX spectrometer. Theoretical models are used in order to disentangle the competition between long-range and short-range correlations
Long-range versus short-range correlations in the two-neutron transfer reaction Ni 64 (O 18, O 16) Ni 66
Recently, various two-neutron transfer studies using the (18O,16O) reaction were performed with a large success. This was achieved because of a combined use of the microscopic quantum description of the reaction mechanism and of the nuclear structure. In the present work we use this methodology to study the two-neutron transfer reaction of the 18O+64Ni system at 84 MeV incident energy, to the ground and first 2+ excited state of the residual 66Ni nucleus. All the experimental data were measured by the large acceptance MAGNEX spectrometer at the Instituto Nazionale di Fisica Nucleare \u2013Laboratori Nazionali del Sud (Italy). We have performed exact finite range cross section calculations using the coupled channel Born approximation (CCBA) and coupled reaction channel (CRC) method for the sequential and direct two-neutron transfers, respectively. Moreover, this is the first time that the formalism of the microscopic interaction boson model (IBM-2) was applied to a two-neutron transfer reaction. From our results we conclude that for two-neutron transfer to the ground state of 66Ni, the direct transfer is the dominant reaction mechanism, whereas for the transfer to the first excited state of 66Ni, the sequential process dominates. A competition between long-range and short-range correlations is discussed, in particular, how the use of two different models (Shell model and IBM's) help to disentangle long- and short-range correlations
Cross sections for the excitation of isovector charge-exchange resonances in 208Tl
The Glauber approximation for the treatment of heavy-ion scattering, has
already been shown to give reliable predictions for the reaction cross section
in the particular case of intermediate energy charge-exchange processes. In the
present work, we couple a Glauber-type model to microscopic Random Phase
Approximation calculations of the charge-exchange excitations of Pb.
The aim is to solve the longstanding question whether the very elusive
charge-exchange isovector monopole has been really identified in the past
experiments, or other multipoles were prevalent in the observed spectra.Comment: text + 4 figures; accepted for publication in Phys. Rev.
Anomalous diffusion in a symbolic model
We address this work to investigate some statistical properties of symbolic
sequences generated by a numerical procedure in which the symbols are repeated
following a power law probability density. In this analysis, we consider that
the sum of n symbols represents the position of a particle in erratic movement.
This approach revealed a rich diffusive scenario characterized by non-Gaussian
distributions and, depending on the power law exponent and also on the
procedure used to build the walker, we may have superdiffusion, subdiffusion or
usual diffusion. Additionally, we use the continuous-time random walk framework
to compare with the numerical data, finding a good agreement. Because of its
simplicity and flexibility, this model can be a candidate to describe real
systems governed by power laws probabilities densities.Comment: Accepted for publication in Physica Script
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