This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.

In this paper, we establish bounds on the norm of multiplication operators on the Bloch space of the unit disk via weighted composition operators. In doing so, we characterize the isometric multiplication operators to be precisely those induced by constant functions of modulus 1. We then describe the spectrum of the multiplication operators in terms of the range of the symbol. Lastly, we identify the isometries and spectra of a particular class of weighted composition operators on the Bloch space.

Carbon nanotubes have the potential of being used as interconnects and active semiconducting material in future electronic circuits. It is necessary to study such nano-scale circuits with probes that can make measurements with molecular precision. We describe results using two nanoprobe techniques, namely scanning surface potential microscopy (SSPM), and conductive tip atomic force microscopy (CT-AFM), in the investigation of electrical properties of nanotube circuits. Vertical arrays of multi-walled nanotubes, grown in a porous alumina template with a metal back contact were analyzed. Current mapping confirmed that the nanotubes were electrically connected to the back contact. Isolated single-walled nanotube bundles deposited on an oxidized silicon wafer, and contacted electrically through chromium electrodes were also studied. Contact potential differences between the metal and nanotubes, and the current in some connected nanotubes were measured. Measurements of contact potential with different metals, and the nature of microscopic transport is crucial. Contact potential measurements can also provide fast and reliable characterization of junctions between metallic and semiconducting nanotubes and metals electrodes.

We have fabricated ordered arrays of gold nanocrystals on FIB-processed silicon substrates using electroless deposition. We have also fabricated ordered arrays of silver nanocrystals on silicon with diameters 40–60 nm separated by 180 nm center-to-center, using pulsed-laser deposition (PLD) to deposit silver on the substrate. The metal nanocrystal arrays are characterized using SEM as well as AFM and energy dispersive x-ray (EDX) analysis. AFM confirms particle sizes measured in SEM, and EDX analysis demonstrates that Ag preferentially clusters at sites that have been damaged by the ion beam. These results suggest that the FIB-PLD combination can be used to create ordered arrays of Ag nanocrystals with diameters of 10 nm or less.

Almost as long as African studies has been a recognized intellectual enterprise in U.S. higher education, scholars have sought to establish its credentials as an academic pursuit and have debated its characteristics. To take the most obvious example, the home page of the African Studies Association (ASA) Web site (http://www.africanstudies.org/) declares, “The African Studies Association was founded in 1957 as a non-profit organization open to all individuals and institutions interested in African affairs. Its mission is to bring together people with a scholarly and professional interest in Africa.”