Hemodynamic prediction in patent ductus arteriosus morphologies

Patent ductus arteriosus (PDA) is a condition in which the ductus arteriosus remain opened after birth, causing the blood to shunt through from the aorta to the pulmonary artery. However, due to the complicated nature of the arterial geometry, the flow characteristic inside the PDA is not fully understood, since simplified model are commonly used in researches. This study aims to identify the hemodynamic characteristic in three different patient-specific morphologies. Computational modeling via computational fluid dynamic (CFD) is implemented to predict the blood flow behavior in different PDA morphologies. The result shows that low wall shear stress is observed at the region where the flow recirculation occurs. High wall shear stress is observed in the pulmonary artery due to increase of flow velocity at the insertion point of PDA. The PDA morphologies exhibit left-to-right shunt, which diverts approximately 10% of blood flow from the aorta to the pulmonary artery. The highest shunted blood flow is found in TR LPA morphology. High value of OSI indicates the changes of wall shear stress vector. It is observed that DS LPA has the highest area covered by OSI which presents better hemodynamic characteristic as compared to other morphology

Estimation of Laceration Length by Emergency Department Personnel

Introduction Documentation and billing for laceration repair involves a description of wound length. We designed this study to test the hypothesis that emergency department (ED) personnel can accurately estimate wound lengths without the aid of a measuring device. Methods This was a single-center prospective observational study performed in an academic ED. Seven wounds of varying lengths were simulated by creating lacerations on purchased pigs’ ears and feet. We asked healthcare providers, defined as nurses and physicians working in the ED, to estimate the length of each wound by visual inspection. Length estimates were given in centimeters (cm) and inches. Estimated lengths were considered correct if the estimate was within 0.5 cm or 0.2 inches of the actual length. We calculated the differences between estimated and actual laceration lengths for each laceration and compared the accuracy of physicians to nurses using an unpaired t-test. Results Thirty-two physicians (nine faculty and 23 residents) and 16 nurses participated. All subjects tended to overestimate in cm and inches. Physicians were able to estimate laceration length within 0.5 cm 36% of the time and within 0.2 inches 29% of the time. Physicians were more accurate at estimating wound lengths than nurses in both cm and inches. Both physicians and nurses were more accurate at estimating shorter lengths (5.0 cm). Conclusion ED personnel are often unable to accurately estimate wound length in either cm or inches and tend to overestimate laceration lengths when based solely on visual inspection

Poisoning and fading mechanism of grain refinement in Al-7Si alloy

The poisoning and fading mechanism of grain refinement in Al-7Si alloy has been studied in detail with the conventional (0.01%Ti or B) and higher addition levels of indigenously developed Al-3Ti, Al-5Ti, Al-3B and Al-5Ti- 1B master alloys. Results suggest that on prolonged holding the melt after the conventional addition of grain refiner to Al-7Si alloy, size of the α-Al dendrites increases (fading), which could be due to the dissolution/settling of TiAl3 and AlB2 particles. However, vigorous agitation of the melt after prolonged holding (120s min.), can partly bring back the particles into the liquid melt and acts as heterogeneous nucleating sites to some limited extents (120s min. sample). In addition, the conventional addition (0.2 wt%) of Ti-rich Al-3Ti, Al-5Ti and Al-5Ti-1B master alloy to Al-7Si alloy, the Si from the melt reacts with grain refining constituents (TiAl3) and formation of titanium silicide and coats on the surface of the TiAl3 particles and poisons the effectiveness of the nuclei. However, the higher addition level of these master alloy or B-rich Al-3B master alloys can overcome poisoning effect of Al-7Si alloy