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[en] Geometric quantum discord, proposed by Dakic et al (2010 Phys. Rev. Lett. 105 190502), is an important measure for bipartite correlations. In this paper, we generalize it to multipartite states, we call the generalized version geometric global quantum discord (GGQD). We characterize GGQD in different ways, give a lower bound for GGQD and provide some special states which allow analytical GGQD. (paper)
[en] A spatial quantile regression model is proposed to estimate the quantile curve for a given probability of non-exceedance, as function of locations and covariates. Canonical vines copulas are considered to represent the spatial dependence structure. The marginal at each location is an asymmetric Laplace distribution where the parameters are functions of the covariates. The full conditional quantile distribution is given using the Joe–Clayton copula. Simulations show the flexibility of the proposed model to estimate the quantiles with special dependence structures. A case study illustrates its applicability to estimate quantiles for spatial temperature anomalies.
[en] The data on the mean surface brightness of spiral single galaxies are compared to the data on the mean surface brightness of spiral binary galaxies. It is shown that the mean surface brightness of the spiral galaxies being the components of the pairs exceeds with high statistical significance that of isolated spiral galaxies. The increase of the mean surface brightness of the spiral galaxies in the pairs with decrease of linear distance between them is stated. The small correlation between the mean surface brightness of the components of the pairs is also revealed. It decreases with the increase of the linear distances between them
[en] The influence of the current channel radius on the electrostatic ion-cyclotron instability is investigated. The effective radius of the channel is varied by negatively biasing a ring electrode surrounding the circular positively biased electrode which draws the current. When the current channel is contracted to a few ion Larmor radii the instability is quenched. (author)
[en] On the base of a data base on the rocket profiles of electron density, measured by means of an electrostatic probe, is precised an empirical dependence of the elecron density of the lower ionosphere on the Sun zenits angle for day-time middle-latitude (49 deg N, 44 deg E) heliogeophysically nondisturbed conditions
[en] Earth attributes show complex, heterogeneous spatial patterns generated by exogenous environmental factors and formation processes. This study investigates various strategies to quantify the underlying spatial patterns of simulated fields resembling real earthscapes and to compare their performance for describing them. The approach is to disaggregate the variability of earth attributes into two components, deterministic trend m(xi) and spatial dependence ε(xi), and determine the effects of m(xi) and ε(xi) on prediction accuracy under various combinations of spatial fields of earth attributes encountered in different earthscapes. We illustrate that cross-dependencies exist between spatial and feature accuracy. Scientific visualization is used to transpose quantitative results into visual space.