Space(time) oddity: dualities, holography and branes

In this Thesis, we study (several) aspects of three and five dimensional non-supersymmetric gauge theories. Using non-perturbative techniques, such as known strong-weak coupling dualities and holography, we present new results concerning their dynamics and phase diagrams. The thesis is divided into six Chapters. In the first Chapter, we start reviewing some general aspects of non-supersymmetric three dimensional theories, focusing on the dynamics of gauge theory both in the absence and in presence of Chern-Simons terms. We then focus on known dualities among three dimensional theories, such as particle-vortex and bosonization duality. Thanks to these tools, we discuss what is known about the phase diagram of QCD3, namely the three dimensional analog of four dimensional quantum chromodynamics, for various ranges of its parameters. In Chapter two, we introduce the basics of holography, starting by reviewing the AdS/CFT correspondence. We then generalize the discussion to the case of non-conformal field theories, with particular emphasis on the description of confining theories. Finally, we review the holographic construction of four dimensional and three dimensional gauge theories, and, focusing on the latter case, we construct the gravity dual of QCD3. In Chapter three, we show new results regarding the phase diagram of QCD3 in presence of flavor-breaking mass deformation. The corresponding theory, namely QCD3 with two sets of flavors, is studied in detail, thanks to the conjectured infrared dualities characterizing gauge theories with matter in three dimensions, namely boson-fermion dualities. In particular, the low-energy phase diagram is charted, and its consistency gives additional support to the conjectured phase diagram of QCD3. Moreover, new non-perturbative phases are observed, together with peculiar phase transitions among them, which are novel to QCD3 with two flavors. In Chapter four, we study the phase diagram of large N QCD3 through its holographic dual. This novel study shows perfect agreement with the field theory analysis, giving a simple explanation of the observed peculiarity of its phase diagram, together with an holographic evidence of the validity of boson-fermion dualities. In Chapter five, we review the main aspects of five dimensional theories. Firstly, we focus on general properties of supersymmetric gauge theories, their BPS spectrum, and their moduli spaces of vacua. Then, we study their non-perturbative dynamics using string constructions, both in type I’ and in type IIB string theory. The latter type of construction, known as the pq-web or brane web construction, gives us the possibility of studying in detail many non-perturbative phenomena characterizing these theories and their superconformal ultraviolet fixed points, such as global symmetry enhancement and continuation past infinite coupling

5d SCFTs and their non-supersymmetric cousins

We consider generalisations of the recently proposed supersymmetry breaking deformation of the 5d rank-1 $E_1$ superconformal field theory to higher rank. We generalise the arguments to theories which admit a mass deformation leading to gauge theories coupled to matter hypermultiplets at low energies. These theories have a richer space of non-supersymmetric deformations, due to the existence of a larger global symmetry. We show that there is a one-to-one correspondence between the non-SUSY deformations of the gauge theory and their $(p,q)$ 5-brane web. We comment on the (in)stability of these deformations both from the gauge theory and the 5-brane web point of view. UV duality plays a key role in our analysis, fixing the effective Chern-Simons level for the background vector multiplets, together with their complete prepotential. We partially classify super-Yang-Mills theories known to enjoy UV dualities which show a phase transition where different phases are separated by a jump of Chern-Simons levels of both a perturbative and an instantonic global symmetry. When this transition can be reached by turning on a non-supersymmetric deformation of the UV superconformal field theory, it can be a good candidate to host a 5d non-supersymmetric CFT. We also discuss consistency of the proposed phase diagram with the 't Hooft anomalies of the models that we analyse.Comment: references added, minor typos correcte

Vacuum structure of large N QCD3 from holography

We study the vacuum structure of three-dimensional SU(N) gauge theory coupled to a Chern-Simons term at level k and to F fundamental Dirac fermions. We use a large N holographic description based on a D3/D7 system in type IIB string theory compactified on a supersymmetry breaking circle. The multiple vacua of the theory and the transitions between them are nicely captured by the dual holographic background. The resulting phase diagram, which we derive both at leading and first subleading orders in the 1/N expansion, shows a rich structure where topological field theories, non-linear sigma models and first-order phase transitions appear

Validation of a New Classification Method of Postoperative Complications in Patients Undergoing Coronary Surgery

International audienceObjective The authors aimed to validate the European Multicenter Study on Coronary Artery Bypass Grafting (E-CABG) classification of postoperative complications in patients undergoing coronary artery bypass grafting (CABG). Design Retrospective, observational study. Setting University hospital. Participants A total of 2,764 patients with severe coronary artery disease. Complete baseline, operative, and postoperative data were available for patients who underwent isolated CABG. Interventions Isolated CABG. Measurements and Main Results The E-CABG complication classification was used to stratify the severity and prognostic impact of adverse postoperative events. Primary outcome endpoints were 30-day, 90-day, and long-term all-cause mortality. The secondary outcome endpoints was the length of intensive care unit stay. Both the E-CABG complication grades and additive score were predictive of 30-day (area under the receiver operating characteristics curve 0.866, 95% confidence interval [CI] 0.829-0.903; and 0.876; 95% CI 0.844-0.908, respectively) and 90-day (area under the receiver operating characteristics curve 0.850, 95% CI 0.812-0.887; and 0.863, 95% CI 0.829-0.897, respectively) all-cause mortality. The complication grades were independent predictors of increased mortality at actuarial (log-rank: p<0.0001) and adjusted analysis (p<0.0001; grade 1: hazard ratio [HR] 1.757, 95% CI 1.111-2.778; grade 2: HR 2.704, 95% CI 1.664-4.394; grade 3: HR 5.081, 95% CI 3.148-8.201). When patients who died within 30 days were excluded from the analysis, this grading method still was associated with late mortality (p<0.0001). The grading method (p<0.0001) and the additive score (rho, 0.514; p<0.0001) were predictive of the length of intensive care unit stay. Conclusions The E-CABG postoperative complication classification seems to be a promising tool for stratifying the severity and prognostic impact of postoperative complications in patients undergoing cardiac surger

On non-supersymmetric fixed points in five dimensions

We generalize recent results regarding the phase space of the mass deformed E-1 fixed point to a full class of five-dimensional superconformal field theories, known as X-1,X-N. As in the E-1 case, a phase transition occurs as a supersymmetry preserving and a supersymmetry breaking mass deformations are appropriately tuned. The order of such phase transition could not be unequivocally determined in the E-1 case. For X-1,X-N, instead, we can show that at large N there exists a regime where the phase transition is second order. Our findings give supporting evidence for the existence of non-supersymmetric fixed points in five dimensions

HAZARD ‐ HYDROLOGY

Hydraulic forcings on bridges are of different nature and generated by different water‐driven processes; these can be both fast‐evolving events (high water levels, debris flows, trees accumulations) generated by flood events, or slow processes (e.g., morphological changes in the river). Such processes depend on the hydrological behaviour of the river basin at different time (and space) scales and requires the evaluation of different hydrological variables to be properly estimated in the site of interest, to support the design or the bridge analysis. The Italian Group of Hydraulics is developing an initiative to define comprehensive and up‐todate guidelines to quantify the hydraulic‐related forcings on bridges; this is particularly relevant as most of the bridge collapses in Italy can be related to hydraulic effects while the regulations provide little or no guidance about practical design and verification methods. This manuscript will focus on methods for the estimation of hydrological variables that are used to quantify the forcing actions on bridges

Outcome of emergency coronary artery bypass grafting

OBJECTIVES: The aim of this study was to evaluate the immediate and late outcome of emergency coronary artery bypass grafting (CABG) in a multicenter setting. DESIGN: Multicenter, retrospective study. SETTING: Four university hospitals. PARTICIPANTS: 596 patients were included in this study. INTERVENTIONS: Included patients underwent isolated, emergency CABG. MEASUREMENTS AND MAIN RESULTS: Sixty patients (absolute rate: 10.1%, pooled rate: 8.7%) died during the in-hospital stay period. Increasing emergency CABG classes (p<0.0001), recent myocardial infarction (p=0.019), left ventricular ejection fraction≤30% (p=0.034), on-pump surgery (p=0.012), and participating centers (p<0.0001) were independent predictors of in-hospital mortality. Survival rates at 1, 3, and 5 years were 86.4%, 81.6%, and 76.1%, respectively. Extracorporeal membrane oxygenation was used in 6 patients and 3 of them (50.0%) survived the immediate postoperative period. Patient populations of participating centers differed significantly in most of baseline characteristics. The preoperative use of intra-aortic balloon pump (8% to 51%) and off-pump surgery (2.8% to 56.3%) varied significantly between institutions. In-hospital mortality (2.8%, 5.9%, 7.7% and 19.8%, p<0.0001), as well as midterm survival, significantly differed between institutions (at 3 years, 90.6%, 89.8%, 81.2%, and 67.2%, p<0.0001). CONCLUSIONS: The outcome after emergency CABG is satisfactory despite a significant operative risk. However, the results of emergency CABG significantly differed between the participating institutions, likely due to differences in the referral pathways and perioperative treatment strategies. Evaluation of these factors is crucial for implementation of treatment in centers with suboptimal results

Surgical factors and complications affecting hospital outcome in redomitral surgery: Insights from a multicentre experience

OBJECTIVES: Several single-centre experiences have reported significant operative mortality and morbidity after mitral valve surgery in redo scenarios (ReMVS). Several preoperative risk factors outlining 'high-risk' categories have been reported, but scanty data on the impact of different operative techniques for these major challenging procedures have been analysed to date. The aim of the study is to investigate those intraoperative factors and postoperative events affecting early survival after redo mitral procedures. METHODS: Operative mortality and major morbidity events from a large multicentre registry enrolling 832 consecutive redo mitral procedures were analysed. Intraoperative technical issues and postoperative complications impacting operative mortality were identified. RESULTS: ReMVS was associated with significant operative mortality (12.5%), acute myocardial infarction (AMI; 5.9%), stroke (4.9%), acute respiratory insufficiency (14.8%), pneumonia (7.0%), acute renal insufficiency (16.1%) and failure (12.6%), reintervention for bleeding (7.6%), massive transfusion (28.0%), need for permanent pacemaker (10.1%). Injury of a previous patent left internal mammary artery (LIMA) graft [odds ratio (OR) 4.2, 95% confidence interval (CI): 1.6-11.5; P = 0.005], major cardiovascular iatrogenic lesions at re-entry (OR 19.2, 95% CI: 9.2-39.9; P 48 h (OR 5.3, 95% CI: 2.9-9.4; P = 0.001) and massive (>6 units) transfusions (OR 4.4, 95% CI: 2.4-8.0; P = 0.001) also predicted operative mortality. CONCLUSIONS: ReMVS still carries the risk of significant early mortality and major morbidity. Major lesion to cardiovascular structures is the most dreadful iatrogenic complication, and injury of a previous LIMA graft identifies patients at higher risk of operative mortality. Prolonged cross-clamp times, extracellular crystalloid cardioplegia and massive transfusions have profound impact on early outcome, as well as the development of perioperative AMI, eventually requiring IABP and prolonged intubation. The combination of antegrade and retrograde cardioplegia seems to offer a better myocardial protection in these high-risk patients

Early and intermediate outcome after aortic valve replacement with a sutureless bioprosthesis: Results of a multicenter study

OBJECTIVE: The aim of this study was to evaluate the outcome of aortic valve replacement with the sutureless Perceval S aortic valve bioprosthesis (Sorin Biomedica Cardio Srl, Saluggia, Italy). METHODS: This is a retrospective analysis of 314 patients (mean age, 77.9 ± 5.0 years, mean European System for Cardiac Operative Risk Evaluation II, 9.0% ± 7.6%) who underwent aortic valve replacement with the Perceval S valve with (94 patients) or without (220 patients) concomitant coronary artery bypass surgery at 5 European centers. RESULTS: The Perceval S valve was successfully implanted in all but 1 patient (99.7%). The mean aortic crossclamping time was 43 ± 20 minutes (isolated procedure, 39 ± 15 minutes; concomitant coronary surgery, 52 ± 26 minutes). Severe paravalvular leak occurred in 2 patients (0.6%). In-hospital mortality was 3.2% (1.4% after isolated procedure and 7.4% after concomitant coronary surgery). In-hospital mortality was 2.8% and 4.0% among patients with a European System for Cardiac Operative Risk Evaluation II less than 10% and 10% or greater, respectively (P = .558). Octogenarians had slightly higher in-hospital mortality (5.2% vs 2.0%, P = .125; after isolated procedure: 2.7% vs 0.7%, P = .223; after concomitant coronary surgery: 9.5% vs 5.8%, P = .491) compared with younger patients. Full sternotomy did not increase the in-hospital mortality risk compared with ministernotomy or minithoracotomy access (1.3% vs 1.4%, when adjusted for baseline covariates: P = .921; odds ratio, 0.886; 95% confidence interval, 0.064-12.346). One-year survival was 90.5%. Freedom from valve-related mortality, stroke, endocarditis, and reoperation was 99.0%, 98.1%, 99.2%, and 98.3%, respectively. CONCLUSIONS: The sutureless Perceval S valve is associated with excellent early survival in high-risk patients, particularly among those undergoing an isolated procedure. Further studies are needed to prove the durability of this bioprosthesis