Aortic Coarctation: Recent Developments in Experimental and Computational Methods to Assess Treatments for this Simple Condition

Coarctation of the aorta (CoA) is often considered a relatively simple disease, but long-term outcomes suggest otherwise as life expectancies are decades less than in the average population and substantial morbidity often exists. What follows is an expanded version of collective work conducted by the authors\u27 and numerous collaborators that was presented at the 1st International Conference on Computational Simulation in Congenital Heart Disease pertaining to recent advances for CoA. The work begins by focusing on what is known about blood flow, pressure and indices of wall shear stress (WSS) in patients with normal vascular anatomy from both clinical imaging and the use of computational fluid dynamics (CFD) techniques. Hemodynamic alterations observed in CFD studies from untreated CoA patients and those undergoing surgical or interventional treatment are subsequently discussed. The impact of surgical approach, stent design and valve morphology are also presented for these patient populations. Finally, recent work from a representative experimental animal model of CoA that may offer insight into proposed mechanisms of long-term morbidity in CoA is presented

Development of a Physical Windkessel Module to Re-Create \u3ci\u3eIn Vivo\u3c/i\u3e Vascular Flow Impedance for \u3ci\u3eIn Vitro\u3c/i\u3e Experiments

To create and characterize a physical Windkessel module that can provide realistic and predictable vascular impedances for in vitro flow experiments used for computational fluid dynamics validation, and other investigations of the cardiovascular system and medical devices. We developed practical design and manufacturing methods for constructing flow resistance and capacitance units. Using these units we assembled a Windkessel impedance module and defined its corresponding analytical model incorporating an inductance to account for fluid momentum. We tested various resistance units and Windkessel modules using a flow system, and compared experimental measurements to analytical predictions of pressure, flow, and impedance. The resistance modules exhibited stable resistance values over wide ranges of flow rates. The resistance value variations of any particular resistor are typically within 5% across the range of flow that it is expected to accommodate under physiologic flow conditions. In the Windkessel impedance modules, the measured flow and pressure waveforms agreed very favorably with the analytical calculations for four different flow conditions used to test each module. The shapes and magnitudes of the impedance modulus and phase agree well between experiment and theoretical values, and also with those measured in vivo in previous studies. The Windkessel impedance module we developed can be used as a practical tool to provide realistic vascular impedance for in vitro cardiovascular studies. Upon proper characterization of the impedance module, its analytical model can accurately predict its measured behavior under different flow conditions

The Ursinus Weekly, June 10, 1904

Baccalaureate sermon • Class Day exercises • Commencement • Alumni Day • Final field house report • Junior oratorical contest • President\u27s reception • Schaff society • Senior reverie • Zwinglian debate • May • Baseball • College worldhttps://digitalcommons.ursinus.edu/weekly/3055/thumbnail.jp

Agribusiness Capstone Courses Design: Objectives and Strategies

This paper discusses the benefits of using strategic management principles as the cornerstone for building the agribusiness capstone experience. The necessity for agribusiness firms to create and implement strategies that build a sustainable competitive advantage in turn necessitates the development of strategic management skills in the leaders/managers of the future. As such, the objectives of a capstone course lean heavily toward the integrative development of strategic decision-making competence. This has a number of implications for the capstone professor in terms of course content, pedagogies, and subsequent measurement of student performance.Agribusiness, Teaching/Communication/Extension/Profession,

Ventilating the Box Cut of a Two-Pass 40-ft Extended Cut

On a continuous miner coal face methane concentrations are affected by the quantity of fresh intake air reaching the face. When mining the box cut on a 12.2-m (40-ft) two-pass extended cut face, the continuous miner is always at the point of deepest penetration, and operation of the machine-mounted dust scrubber and water spray system improve the flow of fresh air to the end of the box cut. However, when the continuous miner leaves the box cut to begin cutting the 40-ft slab, little is known about how much ventilation air reaches the end of the box cut. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health conducted a full-scale study to answer this question. Tests were run to determine how much ventilation air reaches the end of the box cut with the continuous miner at three locations in the 40-ft two-pass extended cut mining sequence; at the end of the 40-ft box cut, at the start of the 40-ft slab cut, and 6.1 m (20ft) into the slab cut. During these tests, methane gas was uniformly released at the end of the 40-ft box cut. Methane concentrations measured 0.3 m (1 ft) from the roof and face of the box cut were used to estimate face airflow quantities. Fresh airflow rates of 1.89 and 4. 72 m3/sec (4,000 and 10.000 cfm), scrubber flow rates of 0, 4,000 and 10,000 cfm, water spray pressures of 0 and 827 kPa (0 and 120 psi), and a blowing curtain setback position of 15.2 m (50ft) were used during these tests. To improve ventilation to the end of the 40-ft box cut when the continuous miner was starting the 40-ft slab cut and 20ft into the slab cut, the blowing curtain was advanced from its 50-ft setback to locations 40-ft and then 8.5 m (28ft) from the face

Computational Simulations for Aortic Coarctation: Representative Results From a Sampling of Patients

Treatments for coarctation of the aorta (CoA) can alleviate blood pressure (BP) gradients(D), but long-term morbidity still exists that can be explained by altered indices of hemodynamics and biomechanics. We introduce a technique to increase our understanding of these indices for CoA under resting and nonresting conditions, quantify their contribution to morbidity, and evaluate treatment options. Patient-specific computational fluid dynamics (CFD) models were created from imaging and BP data for one normal and four CoA patients (moderate native CoA: D12 mmHg, severe native CoA: D25 mmHg and postoperative end-to-end and end-to-side patients: D0 mmHg). Simulations incorporated vessel deformation, downstream vascular resistance and compliance. Indices including cyclic strain, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) were quantified. Simulations replicated resting BP and blood flow data. BP during simulated exercise for the normal patient matched reported values. Greatest exercise-induced increases in systolic BP and mean and peak DBP occurred for the moderate native CoA patient (SBP: 115 to 154 mmHg; mean and peak DBP: 31 and 73 mmHg). Cyclic strain was elevated proximal to the coarctation for native CoA patients, but reduced throughout the aorta after treatment. A greater percentage of vessels was exposed to subnormal TAWSS or elevated OSI for CoA patients. Local patterns of these indices reported to correlate with atherosclerosis in normal patients were accentuated by CoA. These results apply CFD to a range of CoA patients for the first time and provide the foundation for future progress in this area