Gluck twist on a certain family of 2-knots

We show that by performing the Gluck twist along the 2-knot $K^2_{pq}$ derived from two ribbon presentations of the ribbon 1-knot $K(p,q)$ we get the standard 4-sphere $S^4$. In the proof we apply Kirby calculus.Comment: 11 pages, 12 figure

Material Modifications for Improved Performance of Shape Memory Polymer Medical Devices

Shape memory polymers (SMPs) are a class of materials that can be programmed into a secondary, metastable geometry and subsequently stimulated to return to their original geometry. These biocompatible materials enable the delivery and subsequent expansion of multiple catheter-based medical devices, including low density foams for embolic applications. In this work, cold plasma surface modifications and bulk compositional changes were used to address three design limitations of previous SMP systems: controlled foam expansion, controlled foam membrane removal, and inherent x-ray visibility. SMP parameters including glass transition temperature, foam pore size, expansion rate in water, and x-ray contrast can be modified by altering the SMP composition or by using particulate additives to form an SMP composite. However, aggressive changes in bulk material chemistry can also affect properties associated with the surface, such as biocompatibility or hydrophobicity. To address the current limitations of SMP devices, this dissertation investigates the use of cold gas plasma techniques as an additional tool to alter surface material properties independent of bulk material composition. The material modifications imparted by plasma processes or changes in composition were first analyzed on simple film and bulk substrates using techniques such as ellipsometry, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, uniaxial tensile testing, and goniometry. After material characterization, each process was applied to a specific medical device application and characterized based on device performance criteria. Device-specific characteristics, including cell-material interactions, x-ray visibility, fluid permeability, and expansion kinetics, were conducted on device prototypes using confocal microscopy, fluoroscopic imaging, flow system analysis, and isothermal expansion imaging, respectively. Cold plasma film deposition using hydrocarbon gases was proven to influence SMP foam expansion kinetics by modulating the rate of moisture plasticization. Additionally, oxygen and tetrafluoromethane cold plasmas preferentially removed foam membranes to increase the interconnected porosity and fluid permeability of embolic SMP scaffolds with minimal impacts on material toughness. Finally, chemically incorporating triiodobenzene containing monomers not only provided x-ray visibility, but also significantly improved tensile toughness

Material Modifications for Improved Performance of Shape Memory Polymer Medical Devices

Shape memory polymers (SMPs) are a class of materials that can be programmed into a secondary, metastable geometry and subsequently stimulated to return to their original geometry. These biocompatible materials enable the delivery and subsequent expansion of multiple catheter-based medical devices, including low density foams for embolic applications. In this work, cold plasma surface modifications and bulk compositional changes were used to address three design limitations of previous SMP systems: controlled foam expansion, controlled foam membrane removal, and inherent x-ray visibility. SMP parameters including glass transition temperature, foam pore size, expansion rate in water, and x-ray contrast can be modified by altering the SMP composition or by using particulate additives to form an SMP composite. However, aggressive changes in bulk material chemistry can also affect properties associated with the surface, such as biocompatibility or hydrophobicity. To address the current limitations of SMP devices, this dissertation investigates the use of cold gas plasma techniques as an additional tool to alter surface material properties independent of bulk material composition. The material modifications imparted by plasma processes or changes in composition were first analyzed on simple film and bulk substrates using techniques such as ellipsometry, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, uniaxial tensile testing, and goniometry. After material characterization, each process was applied to a specific medical device application and characterized based on device performance criteria. Device-specific characteristics, including cell-material interactions, x-ray visibility, fluid permeability, and expansion kinetics, were conducted on device prototypes using confocal microscopy, fluoroscopic imaging, flow system analysis, and isothermal expansion imaging, respectively. Cold plasma film deposition using hydrocarbon gases was proven to influence SMP foam expansion kinetics by modulating the rate of moisture plasticization. Additionally, oxygen and tetrafluoromethane cold plasmas preferentially removed foam membranes to increase the interconnected porosity and fluid permeability of embolic SMP scaffolds with minimal impacts on material toughness. Finally, chemically incorporating triiodobenzene containing monomers not only provided x-ray visibility, but also significantly improved tensile toughness

Upfront: Economic news across the region

Articles: "Danville works: new IKEA factory hums;" "Troubled asset relief: Bank of America repays government loans;" "Apples, soybeans, poultry: Virginia's exports to Cuba grow;" "Cash economy: underground commerce grows in recession"Economic conditions ; Federal Reserve District, 5th

The Summary Judgment Revolution that Wasn\u27t

The U.S. Supreme Court decided a trilogy of cases on summary judgment in 1986. Questions remain as to how much effect these cases have had on judicial decision-making in terms of wins and losses for plaintiffs. Shifts in wins, losses, and what cases get to decisions on the merits impact access to justice. We assemble novel datasets to examine this question empirically in three areas of law that are more likely to respond to shifts in the standard for summary judgment: antitrust, securities regulation, and civil rights. We find that the Supreme Court’s decisions had a statistically significant effect in antitrust, an ambiguous effect in civil rights cases, and no effect in securities regulation. We also find that, in the trilogy’s wake, antitrust appellate cases were far more likely to cite trilogy cases— particularly the one trilogy case that was an antitrust case—than appellate cases in the other areas. This suggests that the lone trilogy case that arose in antitrust had an effect on decision making in that field, but that the trilogy had a limited effect across other substantive areas of law. This finding differs from Twombly and Iqbal where an antitrust decision ultimately reshaped the entire body of law across doctrines around motions to dismiss

Daniel Nash: \u27On The Verge\u27 MFA Thesis Exhibit Show Card

Show Card for alumni Daniel Nash: \u27On The Verge\u27 MFA Thesis Exhibit.https://digitalcommons.udallas.edu/alumni_89-90/1015/thumbnail.jp