Type Ia supernovae (SNe Ia) span a range of luminosities and timescales, from rapidly evolving subluminous to slowly evolving overluminous subtypes. Previous theoretical work has, for the most part, ...been unable to match the entire breadth of observed SNe Ia with one progenitor scenario. Here, for the first time, we apply non-local thermodynamic equilibrium radiative transfer calculations to a range of accurate explosion models of sub-Chandrasekhar-mass white dwarf detonations. The resulting photometry and spectra are in excellent agreement with the range of observed non-peculiar SNe Ia through 15 d after the time of B-band maximum, yielding one of the first examples of a quantitative match to the entire Phillips (1993) relation. The intermediate-mass element velocities inferred from theoretical spectra at maximum light for the more massive white dwarf explosions are higher than those of bright observed SNe Ia, but these and other discrepancies likely stem from the one-dimensional nature of our explosion models and will be improved upon by future non-local thermodynamic equilibrium radiation transport calculations of multi-dimensional sub-Chandrasekhar-mass white dwarf detonations.
Conventional aortography accurately defines arterial anatomy for the preoperative assessment of abdominal aortic aneurysms (AAA). Helical computed tomography angiography (CTA) allows enhanced ...visualization of the aneurysm using less invasive, conventional, computed tomography (CT) methods. Also, three-dimensional (3-D) images may be reconstructed which provide perspective not possible with biplanar arteriograms. The authors tested the hypothesis that helical CTA matches the utility of conventional aortography in the preoperative evaluation of infrarenal AAA. Thirty-one patients with a suspected AAA were evaluated by helical CTA, which included 3-D reconstructions using the maximum intensity projection (MIP) technique. Seven of these patients also received conventional aortography after CTA. Three radiologists and 1 surgeon evaluated all the radiographs for the location and size of the aneurysm or thrombus, for patency of the renal and mesenteric vessels, and for iliac artery patency. In the 7 patients for whom both CTA and aortography were performed, the mesenteric and renal arteries were visualized in both tests. The inferior mesenteric artery (IMA) was recorded in 4 of 7 patients by aortography and in 2 of 7 patients by CTA. In addition, CTA provided detail regarding aneurysm size, presence of aneurysm thrombus, and vessel wall calcification that was not provided by conventional angiography. Of the 31 patients who had CTA, 16 received conventional surgical aneurysm repair after their imaging procedure with no significant intraoperative findings that were not present on CTA. These results suggest that helical CTA is a useful technique in the preoperative evaluation of AAAs. The arteriograrn should be reserved for patients with peripheral occlusive disease or for further evaluation of and possible percutaneous transluminal angioplasty of renal or visceral arterial disease.
