Surface Imaging of Cold DC Magnetized Air Plasma Treated Poly(dimethyl siloxane) Surfaces

Surface Imaging of Cold DC Magnetized Air Plasma Treated Poly(dimethyl siloxane) Surfaces

Abstract

The surface morphology of poly(dimethyl siloxane) surfaces treated with cold dc magnetized air plasma had been investigated via scanning electron microscopy. The treatment parameters involved in the study were sample-cathode distance, discharge power, and discharge pressure. The plasma treated PDMS surfaces exhibit a variety of surface structures ranging from cracked film morphology to the presence of disordered buckling and aligned, corrugation depending on the treatment parameter studied. Read More

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Freshman Physics Majors’ Cognitive Expectations and Academic Performance in their Introductory Physics Course

Abstract

The research investigates the extent of change in Physics majors’ cognitive expectations – beliefs about the learning process and the structure of knowledge – after going through their first Introductory Physics course. Using the Maryland Physics Expectations (MPEX) Survey, the students’ responses are compared with the responses of ‘life-long learners of physics’. The students’ post-instruction responses reflected highest agreement with the experts’ response in the Concepts, Reality Link, and Effort Link dimensions of the survey. Analysis of the beliefs profile of the students in the upper quartile compared with the beliefs profile of the students in the lower quartile revealed that a more ‘expert-like’ thinking in the Coherence, Concepts, and Effort Link dimensions is present for the students who performed academically well in class. Read More

Geodesic Equation for an Acceleration-Dependent Metric

Geodesic Equation for an Acceleration-Dependent Metric

Abstract

In Einstein’s General Relativity, a spacetime-dependent metric defines the curvature of the manifold. Some studies however propose to resolve various celestial anomalies by allowing some anomalous acceleration to modify the law of inertia. If higher-derivative dependencies are allowed in an otherwise monogenic Lagrangian, the usual variational technique leads to a higher-derivative extension of the Euler-Lagrange equations first presented by Ostrogradsky. Using this technique, to find the extremum of the spacetime interval, we derive the geodesic equation for a spacetime whose metric may have explicit dependence on the spacetime four-vector, four-velocity and four-acceleration. Read More