Self-organized criticality describes a class of dynamical systems that maintain themselves in an attractor state with no intrinsic length or time scale. Fundamentally, this theoretical construct requires mechanism for instability may trigger additional instabilities locally via dissipative processes. This concept has been invoked to explain nonlinear phenomena such as featureless energy spectra...

Here we present observational results on the RS CVn star UX Arietis from four very-long-baseline interferometry observations distributed in time to cover the rotational period of 6.44 days. The data are better fit by two Gaussian components than by the usual core-plus-halo model. In the first three days the sizes of the two components did not change much from hour to hour but their relative pos...

introdouction: it is important for the clinician to be aware regarding the necessary thickness of materials used as intra-orifice coronal barriers to prevent microleakage. the purpose of this in vitro study was to compare coronal microleakage of three different thicknesses of white and gray angelus mineral trioxide aggregate (wamta, gamta). materials and methods: a total of 66 canals of extract...

We report the first resolved rapid transition from a Flaring Branch Oscillation to a Normal Branch Oscillation in the RXTE data of the Z source Sco X-1. The transition took place on a time scale of ∼100 seconds and was clearly associated to the Normal Branch-Flaring Branch vertex in the color-color diagram. We discuss the results in the context of the possible association of the Normal Branch O...

We present Extreme Ultraviolet Explorer spectroscopy and photometry of the nearby F8 V star HD 35850 (HR 1817). The EUVE short-wavelength 75–175 Å and medium-wavelength 160–365 Å spectra reveal 28 emission lines from Fe IX and Fe XV to Fe XXIV. The Fe XXI λλ102, 129 ratio yields an upper limit for the coronal electron density, log ne < 11.6 cm −3. The EUVE SW spectrum shows a small but clearly ...

We present simultaneous ultraviolet and optical observations of five flares on the very late type M dwarf Gl 866 (dM5.5e). A procedure to estimate the physical parameters of the flaring plasma has been developed using a simplified model of the flare and a comparison of observed and computed Balmer decrements. With this procedure we have determined the optical thickness, electron temperature and...