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One of the special topics in the aeroelastic field is the flutter of the airplane wing at an index speed called the flutter speed, which, if this phenomenon is not controlled, there will be a possibility of destroying the structure (airplane wing). Various methods for wing control have been proposed in the last two decades. In the current research, two-way forced jet momentum embedded on the wing is used to control a pseudo three-dimensional wing with a simplified unsteady flow regime. The jet activation signal at the flutter speed is provided by the pulse width-pulse frequency modulator. The advantages of this modulator include its quasi-linear performance, high precision with the presence of fluctuations and flexibility. In this research, the double aeroelastic, non-reversible and rectangular (Hancock) wing model is considered, and the strip theory is used to develop the lift force during spinball. In the speed of the flutter ball, the swing of the wing is driven to damping by the jet activity, and according to the obtained aeroelastic graphs, satisfactory results have followed.

Abstract Background Surgery for congenital heart disease has progressed by leaps and bounds in the last few decades, but the right ventricular outflow tract continues to pose a challenge to the congenital heart surgeon. Objectives We aim to describe the outcomes of patients with CHD who had surgical placement of right ventricle to pulmonary artery conduits with a focus on the risk factors for redo-surgery. Methods We performed a retrospective single-center clinical data review of patients who had RVOT surgery using RV-to-PA conduits Results Thirty-three patients (54.5% males) were included. The mean age at first conduit placement was 3.57 ± 3.18 years, mean conduit size conduit was 14.45 ± 3.85 mm. 51.5% of patients received Contegra tubes. On a mean follow-up of 2.07 ± 2.36 years, 45.5% of patients underwent RV-to-PA conduits redo replacement after 5.67 ± 3.25 years from the first surgery, 2 patients underwent re-intervention for the second time, 7 patients had transcatheter interventions on RVOT or branch PAs. The main mode of conduit failure was stenosis. The median survival without the need for surgical reintervention was 2.5 years for the non-contegra subgroup versus 3 years for the contegra subgroup (P = 0.59). we predicted that 100% of the study group would require redo surgery for conduit replacement within the first 11 years post-initial surgery. For every year of age increase at follow-up, the hazard ratio for redo surgery increases by a factor of 1.47. For every year of age increase at the time of first operation, the hazard ratio for redo surgery decreases by a factor of 0.7. Conclusions The use of conduits to treat the RV to PA discontinuity is a cornerstone in treating congenital heart diseases. Nevertheless, conduit failure and replacement are inevitable. In our experience the higher the age at the first conduit, the longer the re-intervention-free survival period.

Background: Surgery for congenital heart disease has progressed by leaps and bounds in the last few decades, but the right ventricular outflow tract continues to pose a challenge to the congenital heart surgeon. Objectives: We aim to describe the outcomes of patients with CHD who had surgical placement of right ventricle to pulmonary artery conduits with a focus on the risk factors for redo-surgery. Methods: We performed a retrospective single-center clinical data review of patients who had RVOT surgery using RV-to-PA conduits Results: Thirty-three patients (54.5% males) were included. The mean age at first conduit placement was 3.57 ± 3.18 years, mean conduit size conduit was 14.45 ± 3.85 mm. 51.5% of patients received Contegra tubes. On a mean follow-up of 2.07 ± 2.36 years, 45.5% of patients underwent RV-to-PA conduits redo replacement after 5.67 ± 3.25 years from the first surgery, 2 patients underwent re-intervention for the second time, 7 patients had transcatheter interventions on RVOT or branch PAs. The main mode of conduit failure was stenosis. The median survival without the need for surgical reintervention was 2.5 years for the non-contegra subgroup versus 3 years for the contegra subgroup (P = 0.59). we predicted that 100% of the study group would require redo surgery for conduit replacement within the first 11 years post-initial surgery. For every year of age increase at follow-up, the hazard ratio for redo surgery increases by a factor of 1.47. For every year of age increase at the time of first operation, the hazard ratio for redo surgery decreases by a factor of 0.7. Conclusions: The use of conduits to treat the RV to PA discontinuity is a cornerstone in treating congenital heart diseases. Nevertheless, conduit failure and replacement are inevitable. In our experience the higher the age at the first conduit, the longer the re-intervention-free survival period. [ABSTRACT FROM AUTHOR]

In the recent explosion of literature on Leo Strauss, authors have identified or alleged many different kinds of Straussians. This article for the first time in print analyzes a previously unmentioned kind: Christian Straussians. It does so by analyzing the work of Ralph Hancock to see if Hancock is a Christian friend of Strauss or a Straussian friend of Christianity. The difference is whether his primary anchor is in philosophy with an affinity to Christianity or in theology with an affinity to Strauss. While Hancock avers great differences from Strauss on both the theoretical and practical levels, this essay argues that while Hancock’s practical disagreements with Strauss are strong, his theoretical difference is ambiguous. [ABSTRACT FROM PUBLISHER]

Abstract: Background: Bioprosthetic heart valves are more frequently being used in valve replacement procedures today. Although second-generation bioprosthetic valves have improved functionality over their first-generation counterparts, they still often fail due to primary tissue degeneration. Methods: This study examines two second-generation porcine valves after surgical explantation, the Hancock-II (HAN; Medtronic Heart Valve Division, Irvine, CA, USA) and the Carpentier–Edwards supraannular (CE-SAV; Baxter Healthcare Corporation, now Edwards LifeSciences, Irvine, CA, USA), with special attention to morphological/histological changes and reasons for valve failure. A total of 98 HAN and 65 CE-SAV valves were explanted and seen over a 10-year period. Results: CE-SAV valves had a longer average implant duration than HAN valves (13.9±3.9 years vs. 10.0±5.1 years). Compared with HAN valves, CE-SAV valves also had a higher incidence of stent deformation (41.5% vs. 14.3%), calcification (75.4% vs. 54.1%), and pannus (100% vs. 91.8%). Conclusions: The greater degenerative changes seen with CE-SAV valves over HAN valves may be due to the longer implant duration of CE-SAV valves in this series. To our knowledge, the present study is the first direct morphological comparison of these two valve models. [Copyright &y& Elsevier]

Background: Surgery for congenital heart disease has progressed by leaps and bounds in the last few decades, but the right ventricular outflow tract continues to pose a challenge to the congenital heart surgeon. Objective: To describe short and intermediate term outcome in congenital heart disease patients undergoing surgical repair using right ventricle to pulmonary artery conduits. Patients and Methods: Our study included 33 patients that were operated upon by putting a conduit between the right ventricle and the pulmonary artery in a single center (Al Agouza police hospital) between 2015 and 2019. Results: This study was done in order to follow up patients who underwent surgery for conduit placement between the right ventricle (RV) and the pulmonary artery (PA), to observe the reintervention rates and to determine the most important determinants of re-operation. 33 patients were included in this study, with age range 1.5-17 years and mean age of 8.29 +/- 4.7 years. The mean age at placement of the first conduit was 3.57 +/- 3.18 years. The youngest patient at time of conduit placement for the first time was 0.2 years old and the oldest had 12.5 years. Conclusion: The use of conduits to treat the RV to PA discontinuity is a cornerstone in the treatment of some congenital heart diseases requiring construction of the right ventricle outflow tract (RVOT). Nevertheless, conduit failure and replacement is inevitable, and depends on many factors: as age at first operation, type of conduit, mean and peak pressure gradient across the conduit. The higher the age at first conduit, the bigger the event / re-intervention free survival period. [ABSTRACT FROM AUTHOR]

Abstract: Background: The valve-in-valve (VinV) procedure is a minimally invasive, transcatheter, off-pump, alternative to conventional valve replacement, which uses a failing bioprosthesis to anchor a second transcatheter-delivered prosthesis. This technique appears effective for prolonging freedom from reintervention and treating early device failure. However, it is unknown as to how long reintervention can be avoided. Methods: We present the pathological findings of a VinV explanted after 47 months, as well as the failure modes of these devices. Results: The VinV approach in our case ultimately failed, likely due to the proximity of the host''s tissues to the prosthetic device, resulting in a combination of pannus, calcification, and a cusp tear. Conclusions: Additional long-term follow-up of pulmonary VinV implantations is needed in order to determine the life span of VinVs and what causes them to fail. [Copyright &y& Elsevier]

Objective To determine the incidence and risk factors for endocarditis and reintervention in patients undergoing placement of right ventricle-to-pulmonary artery valve conduits. Methods All right ventricle–to–pulmonary artery valved conduits placed between 1995 and 2014 were included. Freedom from endocarditis, reintervention, and replacement were analyzed using the Kaplan-Meier method and parametric survival regression models. Results A total of 586 patients underwent placement of a total of 792 valved conduits, including 289 (36%) pulmonary homografts, 121 (15%) aortic homografts, 245 (31%) bovine jugular grafts, and 137 (17%) porcine heterografts. There were 474 (60%) primary placements and 318 (40%) replacements. The median duration of conduit follow-up was 7 years; 23 conduits developed endocarditis at a median of 5 years after surgery. The use of bovine jugular grafts was the sole significant risk factor associated with endocarditis (hazard ratio, 9.05; 95% confidence interval, 2.6–31.8 compared with homografts). The hazard was greater for bovine jugular grafts compared with the other conduit types and increased with time; however, bovine jugular grafts were associated with a lower risk for reintervention ( P < .0001) and replacement ( P = .0002). Factors associated with greater risk of both reintervention and replacement were younger age and smaller conduit size. In addition, a diagnosis of truncus arteriosus was associated with a greater risk for replacement ( P = .03). Conclusions Bovine jugular grafts are associated with a significantly greater risk of late endocarditis but with lower reintervention rates compared with other valved conduits. The risk of endocarditis and durability must be balanced during conduit selection. Antibiotic prophylaxis and a high index of suspicion for endocarditis are warranted in patients with bovine jugular grafts. [ABSTRACT FROM AUTHOR]