Plutonium Assessment Modeling -- Government Policy, Non-Proliferation, and the Government Fence

Assessment modeling for the evaluation of plutonium as an energy resource is stressed, and generic mathematical model forms are outlined. Representative necessary objective functions are developed. Constraints and assumptions are listed. An example involving present-day light water reactor technology is demonstrated. Technical, environmental, and political implications are drawn. Specific new directions for analysis are suggested. The position of the boundary of government control and responsibility -- the government exclusion fence -- is shown to be a critical, but overlooked, constraint. Existing governmental uranium stockpiles may be an unmentioned, though important, constraint

A bioprinted cardiac patch composed of cardiac-specific extracellular matrix and progenitor cells for heart repair

Congenital heart defects are present in 8 of 1000 newborns and palliative surgical therapy has increased survival. Despite improved outcomes, many children develop reduced cardiac function and heart failure requiring transplantation. Human cardiac progenitor cell (hCPC) therapy has potential to repair the pediatric myocardium through release of reparative factors, but therapy suffers from limited hCPC retention and functionality. Decellularized cardiac extracellular matrix hydrogel (cECM) improves heart function in animals, and human trials are ongoing. In the present study, a 3D-bioprinted patch containing cECM for delivery of pediatric hCPCs is developed. Cardiac patches are printed with bioinks composed of cECM, hCPCs, and gelatin methacrylate (GelMA). GelMA-cECM bioinks print uniformly with a homogeneous distribution of cECM and hCPCs. hCPCs maintain >75% viability and incorporation of cECM within patches results in a 30-fold increase in cardiogenic gene expression of hCPCs compared to hCPCs grown in pure GelMA patches. Conditioned media from GelMA-cECM patches show increased angiogenic potential (>2-fold) over GelMA alone, as seen by improved endothelial cell tube formation. Finally, patches are retained on rat hearts and show vascularization over 14 d in vivo. This work shows the successful bioprinting and implementation of cECM-hCPC patches for potential use in repairing damaged myocardium

Quartz as an archive of deformation and metamorphism of the continental crust

University of Minnesota Ph.D. dissertation. December 2015. Major: Earth Sciences. Advisors: Donna Whitney, Christian Teyssier. 1 computer file (PDF); xx, 346 pages.Quartz is perhaps the most rheologically-significant mineral in the continental crust. It occurs in many different rock types, it is susceptible to deformation over a range of crustal conditions, and it yields plastically at stresses lower than other rock-forming minerals. Consequently the deformation behavior of quartz – its rheology, microstructures, and recrystallization fabrics – has been well-studied in both natural and laboratory settings and is commonly used by structural geologists to interpret the direction and magnitude of forces in exhumed shear zones. In the last decade, it was discovered that quartz can be used as a quantitative indicator of metamorphic conditions. The solubility and diffusivity of trace concentrations of Ti in quartz was determined experimentally, establishing a technique that uses quartz geochemistry as a thermometer, barometer, and geospeedometer to estimate temperatures, pressures, and rates of crystallization in natural rocks. However, the experiments that determined these parameters were conducted under hydrostatic stress. Given the propensity for quartz to deform ductiley in the Earth, it is important to investigate the influence of dynamic recrystallization on Ti substitution to determine if quartz geochemistry provides reliable information on the conditions and rates of ductile deformation. This dissertation combined field and experimental approaches to study the effect of deformation on Ti exchange in quartz. Observations of quartzite mylonites from extensional shear zones in the North American Cordillera inspired the design of rock deformation experiments to simulate natural deformation processes under controlled laboratory conditions. Multiple quantitative (electron-, ion-, and laser-beam techniques) and semi-quantitative (cathodoluminescence) analytical methods were used to measure the Ti content of fine-scale microstructures, which were compared with crystallographic fabric analysis (electron back-scattered diffraction) to correlate the extent of recrystallization with Ti exchange. Results of this research show that dynamic recrystallization is effective at resetting Ti concentrations in quartz, indicating that Ti-in-quartz is capable of recording the conditions of ductile deformation. With the documented importance of quartz for accommodating ductile strain during orogenesis, findings presented in this dissertation demonstrate that quartz is capable of linking metamorphic petrology with deformation microstructures to contribute a new perspective on interpreting deformation in continental shear zones