Emergent Noninvertible Symmetries in N=4 Supersymmetric Yang-Mills Theory.

One of the simplest examples of noninvertible symmetries in higher dimensions appears in 4D Maxwell theory, where its SL(2,Z) duality group can be combined with gauging subgroups of its electric and magnetic 1-form symmetries to yield such defects at many different values of the coupling. Even though N=4 supersymmetric Yang-Mills (SYM) theory also has an SL(2,Z) duality group, it only seems to share two types of such noninvertible defects with Maxwell theory (known as duality and triality defects). Motivated by this apparent difference, we begin our investigation of the fate of these symmetries by studying the case of 4D N=4 U(1) gauge theory, which contains Maxwell theory in its content. Surprisingly, we find that the noninvertible defects of Maxwell theory give rise, when combined with the standard U(1) symmetry acting on the free fermions, to defects that act on local operators as elements of the U(1) outer automorphism of the N=4 superconformal algebra, an operation that was referred to in the past as the "bonus symmetry." Turning to the non-Abelian case of N=4 SYM theory, the bonus symmetry is not an exact symmetry of the theory, but is known to emerge at the supergravity limit. Based on this observation, we study this limit and show that, if it is taken in a certain way, noninvertible defects that realize different elements of the bonus symmetry emerge as approximate symmetries, in analogy to the Abelian case.

Single versus bilateral internal thoracic artery grafting in patients with impaired renal function.

OBJECTIVE: The optimal strategy for surgical revascularization in patients with impaired renal function is inconclusive. We compared early and late outcomes between bilateral internal thoracic artery (BITA) and single ITA (SITA) grafting in patients with renal dysfunction. METHODS: This is a retrospective analysis of all the patients with multivessel disease and impaired renal function (estimated glomerular filtration rate <60mL/min/1.73m2) who underwent isolated coronary artery bypass graft (CABG) in our center during 1996-2011, utilizing either BITA or SITA revascularization. RESULTS: Of the 5301 patients with multivessel disease who underwent surgical revascularization during the study period, 391 were with impaired renal function: 212 (54.2%) underwent BITA, 179 (45.8%) underwent SITA. Patients who underwent BITA were less likely to have comorbidities. Statistically significant differences were not observed between the BITA and SITA groups in 30-day mortality (5.6% vs. 9.0%, p = 0.2) and in rates of early stroke, myocardial infarction, and sternal infection (4.5% vs. 6.1%, p = 0.467; 1.7% vs. 2.8%, p = 0.517; and 2.2% vs. 5.7%, p = 0.088, respectively). Long-term survival of the BITA group was better: median 8.36 vs. 4.14 years, p<0.001. In multivariable analysis, BITA revascularization was associated with decreased late mortality (HR = 0.704, 95% CI: 0.556-0.89, p = 0.003). In analysis of a matched cohort (134 pairs), early outcomes did not differ between the groups; however, in multivariable analysis, BITA revascularization was associated with decreased late mortality (HR = 0.35 (95%CI 0.18-0.68), p = 0.002) . CONCLUSIONS: BITA revascularization did not impact early outcome in patients with CRF, but demonstrated a significant protective effect on long-term survival in the unmatched and matched cohorts.

Saphenous Vein vs Arterial Graft to the Right System in Left-Sided Arterial Revascularization.

BACKGROUND: To investigate clinical outcomes of various arterial grafts (AGs) vs saphenous vein grafts (VGs) to the right coronary system in patients who received left-sided bilateral internal thoracic artery revascularization. METHODS: We compared short- and long-term outcomes of all the patients operated in our center during 1996-2011, who received left-sided bilateral internal thoracic artery (left anterior descending and left circumflex) grafting and either a VG or an AG to the right coronary system. RESULTS: Of 1691 patients, 983 received a VG and 708 received an AG to the right coronary system: 387 gastroepiploic arteries and 321 internal thoracic artery grafts. The median follow-up was 15.7 ± 0.32 years. For the VG and AG groups, early mortality (1.6% for VG and 1.3% for AG, P = .55) and other early adverse outcomes did not differ. Long-term (up to 20 years) survival was similar (34.1% ± 3.4% for VG vs 36.0% ±2% for AG, P = .86). In multivariable analysis, VG to the right coronary artery was not found to be a predictor of inferior survival (hazard ratio: 0.99, 95% confidence interval 0.836-1.194, P = .99). Comparing 2 propensity-matched groups of 349 pairs with a VG or an AG, and accounting for the severity of the right coronary lesion, did not demonstrate differences in early outcome or late survival between the groups. CONCLUSIONS: Early outcomes and long-term survival were comparable among patients who received left-sided bilateral internal thoracic artery revascularization, between various graft types to the right coronary system.

Early and late outcomes of single versus bilateral internal thoracic artery revascularization for patients in critical condition.

OBJECTIVE: The optimal surgical approach for critically ill patients with complex coronary disease remains uncertain. We compared outcomes of bilateral internal thoracic artery (BITA) versus single ITA (SITA) revascularization in critical patients. METHODS: We evaluated 394 consecutive critical patients with multi-vessel disease who underwent CABG during 1996-2001. Outcomes measured were early mortality, strokes, myocardial-infarctions, sternal infections, revisions for bleeding, and late survival. The critical preoperative state was acknowledged concisely by one or more of the following: preoperative ventricular tachycardia/fibrillation, aborted sudden cardiac death, or the need for mechanical ventilation or for preoperative insertion of intra-aortic-balloon counter-pulsation. RESULTS: During the study period, 193 of our patients who underwent SITA and 201 who underwent BITA were in critical condition. The SITA group was older (mean 68.0 vs. 63.3 years, p = 0.001) and higher proportions were females (28.5% vs. 18.9% p = 0.025), after recent-MI (69.9% vs. 57.2% p = 0.009) and with left-main disease (38.3% vs. 49.3% p = .029); the median logistic EuroSCORE was higher (0.2898 vs. 0.1597, p<0.001). No statistically significant differences were observed between the SITA and BITA groups in 30-day mortality; and in rates of early CVA, MI and sternal infections (13.0% vs. 8.5%, p = 0.148; 4.1% vs. 6.0%, p = 0.49; 6.7% vs. 4.5%, p = 0.32 and 2.1% vs. 2.5%, p>0.99, respectively). Long-term survival (median follow-up of 15 years, interquartile-range: 13.57-15) was better in the BITA group (median 14.39 vs. 9.31± 0.9 years, p = 0.001). Propensity-score matching (132 matched pairs) also yielded similar early outcomes and improved long-term survival (median follow-up of 15 years, interquartile-range: 13.56-15) for the BITA group (median 12.49±1.71 vs. 7.63±0.99 years, p = 0.002). In multivariable analysis, BITA revascularization was found to be a predictor for improved survival (hazard-ratio of 0.419, 95%CI 0.23-0.76, p = 0.004). CONCLUSIONS: This study demonstrated long-term survival benefit for BITA revascularization in patients in a critical pre-operative state who presented for surgical revascularization.

Between Symmetry and Duality in Supersymmetric Quantum Field Theories.

We study two cases of interrelations between the enhancement of symmetries in the infrared (IR) and duality properties of supersymmetric quantum field theories in four dimensions. First, we discuss an SU(2) N=1 model with four flavors, singlet fields, and a superpotential. We show that this model flows to a conformal field theory with E_{6}×U(1) global symmetry. The enhancement of the flavor symmetry follows from Seiberg duality. The second example is concerned with an SU(4) gauge theory with matter in the fundamental and antisymmetric representations. We argue that this model has enhanced SO(12) symmetry in the IR, and, guided by this enhancement, we deduce a new IR duality.