Mechanical properties testing and results for thermal barrier coatings

Thermal Barrier Coatings (TBC's) provide a significant challenge in the evaluation of their mechanical properties in ways that provide data that is not specimen dependent. The paper reviews various developments of the principal author over the past several years for both plasma sprayed and physical vapor deposited (PVD) materials, as well as new data on the fatigue behavior of one material system. The test methods that have been employed address tensile and compressive modulus and ultimate strength, tensile and compressive fatigue strength, and interfacial strength. This testing is now underway. Property testing is especially difficult for TBC's owing to the limitation on fabrication thickness of the coating. Bending tests are not used as these tests do not provide sufficiently uniform states of strain for property evaluations. Test specimens with uniform states of axial stress have been devised for each material system. The results show that the material property results between various experimenters and experimental methods are not yet consistent. However, the results provide critical design data at a suitable level of accuracy for life prediction. The paper will review both tensile and compressive mechanical testing of uniaxial specimens showing property dependencies on material density and temperatures for both material systems. Successful test results for both tensile and compressive fatigue loadings will be given. The test data shows that the fatigue strength of the TBC's is highly stress dependent in both loading conditions and is likely to depend on stress range and not mean stress. The fatigue strength of the plasma sprayed TBC's appears to increase with elevated temperatures in a range of temperatures below the creep activation temperature for the materials. The plasma sprayed TBC materials have been confirmed to have cyclic hysteresis at all temperature levels down to room temperature. Limited failure analysis data for various specimens suggest that the failure modes are driven by normal geometric discontinuities in the TBC's

The contributions of diverse sense organs in the control of leg movement by a walking insect

Cruse H, Dean J, Suilmann M. The contributions of diverse sense organs in the control of leg movement by a walking insect. Journal of Comparative Physiology, A. 1984;154(5):695-705

Institute at Midyear, 1970-71, a Program and Interim Report for the Spring Meeting of Council of the American Institute of Certified Public Accountants

https://egrove.olemiss.edu/aicpa_assoc/2013/thumbnail.jp

An Immersive Virtual Reality Curriculum for Pediatric Hematology Clinicians on Shared Decision-making for Hydroxyurea in Sickle Cell Anemia

Although hydroxyurea (HU) is an effective treatment for sickle cell anemia, uptake remains low. Shared decision-making (SDM) is a recommended strategy for HU initiation to elicit family preferences; however, clinicians lack SDM training. We implemented an immersive virtual reality (VR) curriculum at 8 pediatric institutions to train clinicians on SDM that included counseling virtual patients. Clinicians’ self-reported confidence significantly improved following the VR simulations on all communication skills assessed, including asking open-ended questions, eliciting specific concerns, and confirming understanding (Ps≤0.01 for all). VR may be an effective method for educating clinicians to engage in SDM for HU

Impact of quality of evidence on the strength of recommendations: an empirical study

<p>Abstract</p> <p>Background</p> <p>Evidence is necessary but not sufficient for decision-making, such as making recommendations by clinical practice guideline panels. However, the fundamental premise of evidence-based medicine (EBM) rests on the assumed link between the quality of evidence and "truth" and/or correctness in making guideline recommendations. If this assumption is accurate, then the quality of evidence ought to play a key role in making guideline recommendations. Surprisingly, and despite the widespread penetration of EBM in health care, there has been no empirical research to date investigating the impact of quality of evidence on the strength of recommendations made by guidelines panels.</p> <p>Methods</p> <p>The American Association of Blood Banking (AABB) has recently convened a 12 member panel to develop clinical practice guidelines (CPG) for the use of fresh-frozen plasma (FFP) for 6 different clinical indications. The panel was instructed that 4 factors should play a role in making recommendation: quality of evidence, uncertainty about the balance between desirable (benefits) and undesirable effects (harms), uncertainty or variability in values and preferences, and uncertainty about whether the intervention represents a wise use of resources (costs). Each member of the panel was asked to make his/her final judgments on the strength of recommendation and the overall quality of the body of evidence. "Voting" was anonymous and was based on the use of GRADE (Grading quality of evidence and strength of recommendations) system, which clearly distinguishes between quality of evidence and strength of recommendations.</p> <p>Results</p> <p>Despite the fact that many factors play role in formulating CPG recommendations, we show that when the quality of evidence is higher, the probability of making a strong recommendation for or against an intervention dramatically increases. Probability of making strong recommendation was 62% when evidence is "moderate", while it was only 23% and 13% when evidence was "low" or "very low", respectively.</p> <p>Conclusion</p> <p>We report the first empirical evaluation of the relationship between quality of evidence pertinent to a clinical question and strength of the corresponding guideline recommendations. Understanding the relationship between quality of evidence and probability of making (strong) recommendation has profound implications for the science of quality measurement in health care.</p

Prediction of post-operative necrosis after mastectomy: A pilot study utilizing optical diffusion imaging spectroscopy

<p>Abstract</p> <p>Introduction</p> <p>Flap necrosis and epidermolysis occurs in 18-30% of all mastectomies. Complications may be prevented by intra-operative detection of ischemia. Currently, no technique enables quantitative valuation of mastectomy skin perfusion. Optical Diffusion Imaging Spectroscopy (ViOptix T.Ox Tissue Oximeter) measures the ratio of oxyhemoglobin to deoxyhemoglobin over a 1 × 1 cm area to obtain a non-invasive measurement of perfusion (StO₂).</p> <p>Methods</p> <p>This study evaluates the ability of ViOptix T.Ox Tissue Oximeter to predict mastectomy flap necrosis. StO₂measurements were taken at five points before and at completion of dissection in 10 patients. Data collected included: demographics, tumor size, flap length/thickness, co-morbidities, procedure length, and wound complications.</p> <p>Results</p> <p>One patient experienced mastectomy skin flap necrosis. Five patients underwent immediate reconstruction, including the patient with necrosis. Statistically significant factors contributing to necrosis included reduction in medial flap StO₂(p = 0.0189), reduction in inferior flap StO₂(p = 0.003), and flap length (p = 0.009).</p> <p>Conclusion</p> <p>StO₂reductions may be utilized to identify impaired perfusion in mastectomy skin flaps.</p

Posture of the arm when grasping spheres to place them elsewhere

Despite the infinitely many ways to grasp a spherical object, regularities have been observed in the posture of the arm and the grasp orientation. In the present study, we set out to determine the factors that predict the grasp orientation and the final joint angles of reach-tograsp movements. Subjects made reach-to-grasp movements toward a sphere to pick it up and place it at an indicated location. We varied the position of the sphere and the starting and placing positions. Multiple regression analysis showed that the sphere's azimuth from the subject was the best predictor of grasp orientation, although there were also smaller but reliable contributions of distance, starting position, and perhaps even placing position. The sphere's initial distance from the subject was the best predictor of the final elbow angle and shoulder elevation. A combination of the sphere's azimuth and distance from the subject was required to predict shoulder angle, trunkhead rotation, and lateral head position. The starting position best predicted the final wrist angle and sagittal head position. We conclude that the final posture of the arm when grasping a sphere to place it elsewhere is determined to a larger extend by the initial position of the object than by effects of starting and placing position. © 2010 Springer-Verlag