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The Effects of Continued Enrollment in the Children\u27s Health Insurance Program on Health and Educational Outcomes
No full textWe determine how enrollment in the Children\u27s Health Insurance Program (CHIP) over an extended period of time affects medical and dental care use, health status and academic achievement. In contrast to prior research, which focuses on the program\u27s effects during infancy and early childhood, we examine CHIP enrollment among elementary and middle school students. Using the 1999-2007 panels of the Early Childhood Longitudinal Study, Kindergarten Class and an instrumental variables model to address selection bias, we find that an additional year of CHIP enrollment increases the regular use of routine medical care by 16 percent, but has no detectible effects on overall parent-reported health status, obesity or test scores in reading and math
Investigating and Controlling the Mechanical Properties of Solvent-Cast Constructs for Tunable Biomaterial Scaffolds
No full textBiomaterial scaffolds have been used to provide chondrogenic (cartilage-promoting) and osteogenic (bone-promoting) cues to promote osteochondral (OC) tissue formation. However, repairing and regenerating this tissue is challenging because it contains a unique transition between bone to cartilage that includes biochemical, physical, and architectural gradients that are critical for tissue function. Successful OC regeneration therefore requires fabrication techniques that enable these bioactive cues to be organized within a single scaffold to direct native-like tissue formation. Three-dimensional (3D) printing is a popular fabrication method that can generate multi-material constructs with complex architectures suitable for tissue engineering. Our lab uses a form of direct-write 3D printing known as solvent-cast 3D printing (SCP) where a polymer is dissolved in a volatile solvent to create an "ink" that is extruded through a nozzle. The solvent evaporates, leaving behind solid polymer filaments in a desired scaffold architecture. Previous work from our lab leveraged SCP to create peptide-functionalized scaffolds by adding peptide-poly(caprolactone) (PCL) conjugates into the polymer ink. The surface presentation of these peptides provides biochemical cues that influenced human mesenchymal stem cell (hMSC) differentiation towards cartilage and bone. However, this prior work was performed with one polymer type and molecular weight (MW). Printing parameters were also empirically determined, which limited expansion to other polymer types and MWs. A greater understanding of the SCP process was required to expand ability to 3D print multi-material scaffolds with tunable properties for tissue engineering.A roadmap to printability was generated to accelerate the use SCP with other polymer types. Chapter 2 describes how rheological characterization of polymer inks was used to define relationships between the shear applied to the ink during SCP and reproducible printed architectures. Print parameters of pressure and line speed were adapted to control the morphology of printed filaments. Ink viscosity was matched between polymer types to successfully fabricate scaffolds with PCL, poly(lactic acid) (PLA), and poly(lactic-co-glycolic acid) (PLGA). This work showed that ink viscosity can be used to guide the selection of print parameters for SCP
