Dynamics and gravitational wave signature of collapsar formation.

We perform 3+1 general relativistic simulations of rotating core collapse in the context of the collapsar model for long gamma-ray bursts. We employ a realistic progenitor, rotation based on results of stellar evolution calculations, and a simplified equation of state. Our simulations track self-consistently collapse, bounce, the postbounce phase, black hole formation, and the subsequent early hyperaccretion phase. We extract gravitational waves from the spacetime curvature and identify a unique gravitational wave signature associated with the early phase of collapsar formation.

3D collapse of rotating stellar iron cores in general relativity including deleptonization and a nuclear equation of state.

We present 2D and 3D simulations of the collapse of rotating stellar iron cores in general relativity employing a nuclear equation of state and an approximate treatment of deleptonization. We compare fully general relativistic and conformally flat evolutions and find that the latter treatment is sufficiently accurate for the core-collapse supernova problem. We focus on gravitational wave (GW) emission from rotating collapse, bounce, and early postbounce phases. Our results indicate that the GW signature of these phases is much more generic than previously estimated. We also track the growth of a nonaxisymmetric instability in one model, leading to strong narrow-band GW emission.

Gravitational-wave emission from rotating gravitational collapse in three dimensions.

We present the first three-dimensional (3D) calculations of the gravitational-wave emission in the collapse of uniformly rotating stars to black holes. The initial models are polytropes which are dynamically unstable and near the mass-shedding limit. The waveforms have been extracted using a gauge-invariant approach and reflect the properties of both the initial stellar models and of newly produced black holes, being in good qualitative agreement with those computed in previous 2D simulations. The wave amplitudes, however, are about 1 order of magnitude smaller, giving, for a source at 10 kpc, a signal-to-noise ratio S/N approximately 0.25 for LIGO-VIRGO and S/N less than or approximately equal 4 for LIGO II.

The influence of age and gender on normal appendicectomy rates.

Epidemiological data from a retrospective analysis of 1307 pathology reports of appendicectomy specimens from four Hunter Valley Hospitals, having a 100% tissue audit, showed that there was a significant difference in normal appendicectomy (histologically normal appendix following appendicectomy for suspected acute appendicitis) rates for the young (male and female 0-12 years) and reproductive female (13-50 years) groups when compared with the elderly (over 60 years) and the rest (male 13-59, female 51-59 years) of the population. The overall normal appendicectomy rate was 26%, and the perforation rate 3.6%. These data suggest that suspected acute appendicitis in the Hunter Valley is managed in an appropriate way. The perforation rate was significantly higher in the elderly group, and management of these patients will remain a problem due to delayed and atypical presentation. Continuing audit programmes and area-wide review should contribute to improved accuracy in the diagnosis of acute appendicitis.