Contemporary Surgical Options for the Aortic Root

Aortic root pathology is diverse, and it is the most common cause of aortic valve incompetence in the United States. Aortic root surgery is undergoing continuous development and refinements. From the original description of Bentall on aortic root replacement, many advances have been made in the field of aortic root surgery. The surgical armamentarium available today provides advanced repair options as well as replacement options for the aortic root. The aim of this chapter is to provide an insight into the basics of aortic root surgery as well as to further describes the current up-to-date solutions for aortic valve and aortic root pathologies

Free-space Excitation of Resonant Cavities formed from Cloaking Metamaterial

We propose a new class of resonant electromagnetic structures, and study their response to free-space illumination. The structures consist of partial cylindrical shells that have cloaking material properties proposed by Pendry et al. These metamaterial shells have apertures that allow the propagation of incident irradiation into an interior resonant cavity. We use full wave time-harmonic analysis to study the field distribution inside the cavity, and show that an analogue of Whispering Gallery Modes (WGMs) can be efficiently excited via free-space illumination.Comment: to appear J. Modern Optic

Total arch replacement using moderate hypothermic circulatory arrest and unilateral selective antegrade cerebral perfusion

ObjectiveTo examine the clinical outcomes and impact of using moderate hypothermic circulatory arrest (MHCA) and unilateral selective antegrade cerebral perfusion (uSACP) in the setting of total aortic arch replacement (TOTAL).MethodsFrom 2004 to 2012, 733 patients underwent open arch reconstruction with MHCA and SACP. Of these, 145 (20%) underwent TOTAL. Measured outcomes included death, stroke, temporary neurologic dysfunction (TND), and renal failure. Mean follow-up time was 33 months and ranged from 0 to 95 months.ResultsCore temperature at the onset of MHCA was 25.8°C. Cardiopulmonary bypass and myocardial ischemic times were 236 minutes and 181 minutes, respectively. Twenty-three patients (16%) underwent emergency repair of acute type A dissection. Fifty-four cases (37%) were reoperative and 52 (34%) were stage I elephant trunk procedures. Concomitant root replacement was performed in 50 (35%) patients, including 20 David V valve-sparing procedures. Mean duration of circulatory arrest was 55 minutes. Operative mortality was 9.7%. Overall incidence of stroke and TND was 2.8% and 5.6%, respectively. Four patients (2.8%) required postoperative dialysis. Seven-year survival was significantly reduced (P = .04) after repair of type A dissection (83.8%) compared with elective surgery (89.5%). Higher temperature during TOTAL was not found to be a significant risk factor for adverse events.ConclusionsTOTAL using MHCA and uSACP can be accomplished with excellent early and late results. MHCA was not associated with adverse neurologic outcomes or higher operative risk, despite prolonged periods of circulatory arrest

Machine learning logical gates for quantum error correction

Quantum error correcting codes protect quantum computation from errors caused by decoherence and other noise. Here we study the problem of designing logical operations for quantum error correcting codes. We present an automated procedure which generates logical operations given known encoding and correcting procedures. Our technique is to use variational circuits for learning both the logical gates and the physical operations implementing them. This procedure can be implemented on near-term quantum computers via quantum process tomography. It enables automatic discovery of logical gates from analytically designed error correcting codes and can be extended to error correcting codes found by numerical optimizations. We test the procedure by simulation on classical computers on small quantum codes of four qubits to fifteen qubits and show that it finds most logical gates known in the current literature. Additionally, it generates logical gates not found in the current literature for the [[5,1,2]] code, the [[6,3,2]] code, and the [[8,3,2]] code.Comment: 17 page