We characterize the entire functions which transform a weighted Banach space of holomorphic functions on the disc of type H∞ into another such space by superposition. We also show that all the superposition operators induced by such entire functions map bounded sets into bounded sets and are continuous. Superposition operators that map bounded sets into relatively compact sets are also considered.

We present the detection of an enormous disc of cool neutral hydrogen (H I) gas surrounding the S0 galaxy NGC 612, which hosts one of the nearest powerful radio sources (PKS 0131-36). Using the Australia Telescope Compact Array, we detect MHI = 1.8 × 10 9M⊙ of H I emission-line gas that is distributed in a 140 kpc wide disc-like structure along the optical disc and dust-lane of NGC 612. The bul...

The digital versatile disc (DVD) is a new optical recording medium with a storage capacity seven times higher than the conventional compact disc (CD). The major part of the capacity increase is achieved by the use of optics, shorter laser wavelength, and larger numerical aperture, which reduces the spot diameter by a factor of 1.65. The track formed by the recorded pits and lands, as well as th...

Significant misrepresentation of both 1-bit SDM and multi-bit LPCM coding paradigms persist within both professional and commercial arenas that impacts directly upon the perception of DVD-A and SACD formats. A balanced appraisal of these schemes is presented in order to expose the core differences in the technology both in the theoretical and instrumentation domains. Some observations are made ...

We consider packings of the plane using discs of radius 1 and r. A packing is compact if every disc D is tangent to a sequence of discs D1,D2, · · · ,Dn such that Di is tangent to Di+1. We prove that there are only nine values of r with r < 1 for which such packings are possible. For each of the nine values we describe the possible compact packings. c © 2004 by the author. Reproduction of this ...

We study the origin of high-redshift, compact, quenched spheroids (red nuggets) through the dissipative shrinkage of gaseous discs into compact star-forming systems (blue nuggets). The discs, fed by cold streams, undergo violent disc instability that drives gas into the centre (along with mergers). The inflow is dissipative when its time-scale is shorter than the star formation time-scale. This...

Let D be the open unit disc and, as usual, let H(D) be the algebra of bounded analytic functions on D with ‖f‖ = supz∈D |f(z)|. With pointwise addition and multiplication, H(D) is a well known uniform algebra. In this note we characterize the compact endomorphisms of H(D) and determine their spectra. We show that although not every endomorphism T of H(D) has the form T (f)(z) = f(φ(z)) for some...

Context. Lenticular galaxies are believed to form by a combination of environmental effects and secular evolution. Aims. We study the nearby disc-dominated S0 galaxy NGC 6340 photometrically and spectroscopically to understand the mechanisms of S0 formation and evolution in groups. Methods. We use SDSS images to build colour maps and light profile of NGC 6340 which we decompose using a three-co...

We present a new visualization technique, called (Reconfigurable Disc Tree) which can alleviate the disadvantages of cone trees significantly for large hierarchies while maintaining its context of using 3D depth. In , each node is associated with a disc around which its children are placed. Using discs instead of cones as the basic shape in has several advantages: significant reduction of occlu...

We consider the resonances of a quantum graph G that consists of a compact part with one or more infinite leads attached to it. We discuss the leading term of the asymptotics of the number of resonances of G in a disc of a large radius. We call G a Weyl graph if the coefficient in front of this leading term coincides with the volume of the compact part of G. We give an explicit topological crit...