Chern-Simons Field Theories with Non-semisimple Gauge Group of Symmetry

Subject of this work is a class of Chern-Simons field theories with non-semisimple gauge group, which may well be considered as the most straightforward generalization of an Abelian Chern-Simons field theory. As a matter of fact these theories, which are characterized by a non-semisimple group of gauge symmetry, have cubic interactions like those of non-abelian Chern-Simons field theories, but are free from radiative corrections. Moreover, at the tree level in the perturbative expansion,there are only two connected tree diagrams, corresponding to the propagator and to the three vertex originating from the cubic interaction terms. For such theories it is derived here a set of BRST invariant observables, which lead to metric independent amplitudes. The vacuum expectation values of these observables can be computed exactly. From their expressions it is possible to isolate the Gauss linking number and an invariant of the Milnor type, which describes the topological relations among three or more closed curves.Comment: 16 pages, 1 figure, plain LaTeX + psfig.st

Effect of the Equivalence Between Topological and Electric Charge on the Magnetization of the Hall Ferromagnet

The dependence on temperature of the spin magnetization of a two-dimensional electron gas at filling factor unity is studied. Using classical Monte Carlo simulations we analyze the effect that the equivalence between topological and electrical charge has on the the behavior of the magnetization. We find that at intermediate temperatures the spin polarization increases in a thirty per cent due to the Hartree interaction between charge fluctuations.Comment: 4 pages. Submitted to Phys.Rev.

Angiographic outcomes following stenting or coronary artery bypass surgery of the left main coronary artery: Fifteen-month outcomes from the synergy between PCI with TAXUS express and cardiac surgery left main angiographic substudy (SYNTAX-LE MANS)

Aims: The SYNTAX-LE MANS substudy prospectively evaluated 15-month angiographic and clinical outcomes in patients with treated left main (LM) disease. Methods and results: In the SYNTAX trial, 1,800 patients with three-vessel and/or LM disease were randomised to either CABG or PCI; of these, 271 LM patients were prospectively assigned to receive a 15-month angiogram. The primary endpoint for the CABG arm was the ratio of ≥50% to <100% obstructed/occluded grafts bypassing LM lesions to the number placed. The primary endpoint for the PCI arm was the proportion of patients with ≤50% diameter stenosis ('patent' stents) of treated LM lesions. Per protocol, no formal comparison between CABG and PCI arms was intended based on the differing primary endpoints. Available 15-month angiograms were analysed for 114 CABG and 149 PCI patients. At 15 months, 9.9% (26/263) of CABG grafts were 100% occluded and an additional 5.7% (15/263) were ≥50% to <100% occluded. Overall, 27.2% (31/114) of patients had ≥1 obstructed/occluded graft. The 15-month CABG MACCE rate was 8.8% (10/114) and MACCE at 15 months was not significantly associated with graft obstruction/occlusion (p=0.85). In the PCI arm, 92.4% (134/145) of patients had ≤50% diameter LM stenosis at 15 months (89.7% [87/97] distal LM lesions and 97.9% [47/48] non-distal LM lesions). The 15-month PCI MACCE rate was 12.8% (20/156) and this was significantly associated with lack of stent patency at 15 months (p<0.001), mainly due to repeat revascularisation. Conclusions: At 15 months, 15.6% (41/263) of grafts were at least 50% obstructed but this was not significantly associated with MACCE; 92.4% (134/145) of patients had stents that remained patent at 15 months, and stent restenosis was significantly associated with MACCE, predominantly due to revascularisation