Infrared and submillimetre observations of nearby Vega-like stars have revealed a number of clumpy, asymmetric dust debris disks. Previous studies using semi-analytical and numerical methods have suggested planetary companions of various mass as the likely cause of most examples of disk asymmetry. In this paper, we modify an N-body symplectic gravitational integrator to include radiation terms ...

This contribution presents the optical spectral properties of FIR-luminous galaxies, whose distinctive feature is often the simultaneous presence in the spectra of a strong Hδ line in absorption and of emission lines (e(a) spectra). A discrepancy between the star formation rate estimated from the FIR luminosity and that derived from the Hα luminosity persists even after having corrected the Hα ...

In laboratory experiments, I study strongly-coupled dusty plasma levitated in a glow-discharge plasma. Dusty plasma is an arrangement of small dust particles in a plasma background of electrons, ions, and neutral gas. The dust particles are negatively charged because they collect electrons and ions from the background plasma. Depending on the experimental setup, the plasma’s electric field can ...

DESIGN Case-control study among incident African patients with cancer. Questionnaire assessment of exposure to tobacco, occupation, and place of birth. SETTING Northern Province, South Africa. SUBJECTS Between 1993 and 1995, 288 men and 60 women with lung cancer and 183 male and 197 female controls (consisting of patients newly diagnosed with cancers other than those known to be associated ...

Webster et al (1995) claimed that up to 80% of QSOs may be obscured by dust. They inferred the presence of this dust from the remarkably broad range of B?K optical-infrared colours of a sample of at-spectrum PKS radio QSOs. If such dust is typical of QSOs, it will have rendered invisible most of those which would otherwise been have detected by optical surveys. We used the William Herschel Tele...

Preliminary results of a project aiming at unveiling the nature of the extremely red galaxies (ERGs) 1 found in deep optical-NIR surveys are presented. Very little is known about these objects, the critical issue being whether they are old ellipticals at z>1 or distant star-forming galaxies strongly reddened by dust extinction. We expect to shed light onto the unknown nature of these galaxies b...

We investigate the effect of inertial particles dispersed in a circular patch finite radius on stability two-dimensional Rankine vortex semi-dilute dusty flows. Unlike particle-free case where no unstable modes exist, we show that feedback force from triggers novel instability. The mechanisms driving instability are characterized using linear analysis for weakly and further validated against Eu...