The compactification of D=10 type IIA supergravity (the point-field theory limit of the type IIA superstring) on a Calabi-Yau manifold ((2.2) vacuum) is performed. The resulting D=4, N=2 effective supergravity Lagrangian gives rise to an explicit cons . . .

The Rapid Oscillations in the Solar Atmosphere instrument reveals solar atmospheric fluctuations at high frequencies. Spectra of variations of the G-band intensity (IG ) and Ca IIK-line intensity (IK ) show correlated fluctuations above white noise to . . .

Radial magnetic fields that resist orbital shear can explain the outwards angular momentum transport required for accretion in non-self-gravitating disks. This generates azimuthal magnetic fields and thus Maxwell stresses that transfer angular momentu . . .

Principal components analysis (PCA) and independent component analysis (ICA) are used to identify global patterns in solar and space data. PCA seeks orthogonal modes of the two-point correlation matrix constructed from a data set. It permits the ident . . .

We show that the interaction between planetary waves and the stratospheric zonal mean flow results in bi-modal (directreverse flow) or unimodal state depending on wave number of the waves. First we demonstrate this using a simple nonlinear dynamic sys . . .

Many studies have pointed out fractal and multifractal properties of photospheric magnetic fields, but placing the various approaches into context has proved difficult. Although fractal quantities are defined mathematically in the asymptotic limit of . . .

Quasi periodicities on scales of 1 to 2.5 years have been observed in solar, interplanetary and geomagnetic time series. The relation of these signals to 1 and 1.3 yr fluctuations in the solar interior suggest the presence of structures or characteris . . .

There is a growing literature on dyonic black holes as they appear in string theory. Here we examine the correspondence limit of a dyonic black hole which is not supersymmetric. Assuming the existence of a dyon with non-supersymmetric Kerr-Schild stru . . .

We study the nonlinear spinor field in a Kerr–Schild background by first looking for solitonic solutions in the absence of rotation, given that in the special relativistic limit there are solitonic solutions in this approximation. Since for the scalar . . .

Recent years have shown that accretion disks around young stars have extended regions, which are too low ionized to couple to magnetic fields and thus the nature of the underlying turbulence cannot be exclusively magnetic. We also found that disks hav . . .