EVALUATION OF OVERPRESSURE WAVE TRANSITION BY AIRBLAST OVERPRESSURE AND SHOCK WAVE ATTENUATION ANALYSIS USING A SMALL BLACK POWDER CHARGE

Eight flush mount pressure sensors were used in a series of 3 test sequences to measure air overpressure produced by a firecracker. Overpressure was recorded at a range of 1 inch to 21 inches away from detonation, and charge weight was determined to be 0.1mg of black powder. Air overpressure prediction equations were developed from test series then compared to collected data for subsequent tests. Overpressure wave velocity was measured using wave arrival time and distance between sensors. This wave velocity was compared to calculated wave velocity using overpressure and ideal gas law. Overpressure and wave velocity are directly related to each other in shock wave behavior. The goal of these tests was to identify at what point the in elastic-plastic region the overpressure wave no longer closely resembled a shock wave, but an elastic wave instead

Corticomedullary Strain Ratio

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135508/1/jum201332101769.pd

Hemodialysis Graft with Blind Loop Inflow Segment Treated with Stent Placement

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74924/1/j.1525-139X.2008.00460.x.pd

Feasibility of applying ultrasound strain imaging to detect renal transplant chronic allograft nephropathy

Feasibility of applying ultrasound strain imaging to detect renal transplant chronic allograft nephropathy.Chronic renal transplant fibrosis, often termed Chronic Allograft Nephropathy, may progress undetected. Since renal fibrosis may be accompanied by a change in measurable elastic tissue properties, ultrasound strain measurements may be useful in its detection. Ultrasound strain imaging was performed for two subjects with renal transplants; one with normal renal function and one with mild renal insufficiency and biopsy demonstrated fibrosis. Subjects underwent ultrasound examination with application of a controlled deformation using phase-sensitive, two-dimensional speckle tracking to evaluate internal tissue motion to measure tissue displacement and strain. Measurements over multiple beams for an equivalent deformational stress showed there was a threefold differences in renal cortical strain between the two subjects. These data suggest that ultrasound elasticity imaging may prove useful in measuring mechanical changes related to fibrosis within the transplant kidney

Analysis of novel geometry-independent method for dialysis access pressure-flow monitoring

Abstract Background End-stage renal disease (ESRD) confers a large health-care burden for the United States, and the morbidity associated with vascular access failure has stimulated research into detection of vascular access stenosis and low flow prior to thrombosis. We present data investigating the possibility of using differential pressure (ΔP) monitoring to estimate access flow (Q) for dialysis access monitoring, with the goal of utilizing micro-electro-mechanical systems (MEMS) pressure sensors integrated within the shaft of dialysis needles. Methods A model of the arteriovenous graft fluid circuit was used to study the relationship between Q and the ΔP between two dialysis needles placed 2.5–20.0 cm apart. Tubing was varied to simulate grafts with inner diameters of 4.76–7.95 mm. Data were compared with values from two steady-flow models. These results, and those from computational fluid dynamics (CFD) modeling of ΔP as a function of needle position, were used to devise and test a method of estimating Q using ΔP and variable dialysis pump speeds (variable flow) that diminishes dependence on geometric factors and fluid characteristics. Results In the fluid circuit model, ΔP increased with increasing volume flow rate and with increasing needle-separation distance. A nonlinear model closely predicts this ΔP-Q relationship (R2 > 0.98) for all graft diameters and needle-separation distances tested. CFD modeling suggested turbulent needle effects are greatest within 1 cm of the needle tip. Utilizing linear, quadratic and combined variable flow algorithms, dialysis access flow was estimated using geometry-independent models and an experimental dialysis system with the pressure sensors separated from the dialysis needle tip by distances ranging from 1 to 5 cm. Real-time ΔP waveform data were also observed during the mock dialysis treatment, which may be useful in detecting low or reversed flow within the access. Conclusion With further experimentation and needle design, this geometry-independent approach may prove to be a useful access flow monitoring method.http://deepblue.lib.umich.edu/bitstream/2027.42/112774/1/12976_2008_Article_178.pd

Characterization of vascular strain during in-vitro angioplasty with high-resolution ultrasound speckle tracking

<p>Abstract</p> <p>Background</p> <p>Ultrasound elasticity imaging provides biomechanical and elastic properties of vascular tissue, with the potential to distinguish between tissue motion and tissue strain. To validate the ability of ultrasound elasticity imaging to predict structurally defined physical changes in tissue, strain measurement patterns during angioplasty in four bovine carotid artery pathology samples were compared to the measured physical characteristics of the tissue specimens.</p> <p>Methods</p> <p>Using computational image-processing techniques, the circumferences of each bovine artery specimen were obtained from ultrasound and pathologic data.</p> <p>Results</p> <p>Ultrasound-strain-based and pathology-based arterial circumference measurements were correlated with an R²value of 0.94 (p = 0.03). The experimental elasticity imaging results confirmed the onset of deformation of an angioplasty procedure by indicating a consistent inflection point where vessel fibers were fully unfolded and vessel wall strain initiated.</p> <p>Conclusion</p> <p>These results validate the ability of ultrasound elasticity imaging to measure localized mechanical changes in vascular tissue.</p

Quantification of Ultrasound Correlation‐Based Flow Velocity Mapping and Edge Velocity Gradient Measurement

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135662/1/jum201332101815.pd

Notes of a Meeting Held in the Diplomatic Reception Room of the Department of State on Monday, March 20, 1911

The document is a carbon transcript of notes from a meeting held in the State Department respecting the necessity of more such meetings, the present organization of the Department, expenditures, and esprit de corps. Present at the meeting were: The Assistant Secretaries, the Solicitor, the Director of the Consular Service, the Chief Clerk and the Chiefs and Assistant Chiefs of the Divisions and Bureaus of the Department.https://digitalcommons.ursinus.edu/fmhw_speeches/1004/thumbnail.jp

Arterial elasticity imaging: comparison of finite-element analysis models with high-resolution ultrasound speckle tracking

<p>Abstract</p> <p>Background</p> <p>The nonlinear mechanical properties of internal organs and tissues may be measured with unparalleled precision using ultrasound imaging with phase-sensitive speckle tracking. The many potential applications of this important noninvasive diagnostic approach include measurement of arterial stiffness, which is associated with numerous major disease processes. The accuracy of previous ultrasound measurements of arterial stiffness and vascular elasticity has been limited by the relatively low strain of nonlinear structures under normal physiologic pressure and the measurement assumption that the effect of the surrounding tissue modulus might be ignored in both physiologic and pressure equalized conditions.</p> <p>Methods</p> <p>This study performed high-resolution ultrasound imaging of the brachial artery in a healthy adult subject under normal physiologic pressure and the use of external pressure (pressure equalization) to increase strain. These ultrasound results were compared to measurements of arterial strain as determined by finite-element analysis models with and without a surrounding tissue, which was represented by homogenous material with fixed elastic modulus.</p> <p>Results</p> <p>Use of the pressure equalization technique during imaging resulted in average strain values of 26% and 18% at the top and sides, respectively, compared to 5% and 2%, at the top and sides, respectively, under physiologic pressure. In the artery model that included surrounding tissue, strain was 19% and 16% under pressure equalization versus 9% and 13% at the top and sides, respectively, under physiologic pressure. The model without surrounding tissue had slightly higher levels of strain under physiologic pressure compared to the other model, but the resulting strain values under pressure equalization were > 60% and did not correspond to experimental values.</p> <p>Conclusions</p> <p>Since pressure equalization may increase the dynamic range of strain imaging, the effect of the surrounding tissue on strain should be incorporated into models of arterial strain, particularly when the pressure equalization technique is used.</p

Sonographic Elasticity Imaging of Acute and Chronic Deep Venous Thrombosis in Humans

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135317/1/jum20062591179.pd