Analysis and Synthesis Prior Greedy Algorithms for Non-linear Sparse Recovery

In this work we address the problem of recovering sparse solutions to non linear inverse problems. We look at two variants of the basic problem, the synthesis prior problem when the solution is sparse and the analysis prior problem where the solution is cosparse in some linear basis. For the first problem, we propose non linear variants of the Orthogonal Matching Pursuit (OMP) and CoSamp algorithms; for the second problem we propose a non linear variant of the Greedy Analysis Pursuit (GAP) algorithm. We empirically test the success rates of our algorithms on exponential and logarithmic functions. We model speckle denoising as a non linear sparse recovery problem and apply our technique to solve it. Results show that our method outperforms state of the art methods in ultrasound speckle denoising

Shear Force Fiber Spinning: Process Parameter and Polymer Solution Property Considerations

For application of polymer nanofibers (e.g., sensors, and scaffolds to study cell behavior) it is important to control the spatial orientation of the fibers. We compare the ability to align and pattern fibers using shear force fiber spinning, i.e. contacting a drop of polymer solution with a rotating collector to mechanically draw a fiber, with electrospinning onto a rotating drum. Using polystyrene as a model system, we observe that the fiber spacing using shear force fiber spinning was more uniform than electrospinning with the rotating drum with relative standard deviations of 18% and 39%, respectively. Importantly, the approaches are complementary as the fiber spacing achieved using electrospinning with the rotating drum was ~10 microns while fiber spacing achieved using shear force fiber spinning was ~250 microns. To expand to additional polymer systems, we use polymer entanglement and capillary number. Solution properties that favor large capillary numbers (\u3e50) prevent droplet breakup to facilitate fiber formation. Draw-down ratio was useful for determining appropriate process conditions (flow rate, rotational speed of the collector) to achieve continuous formation of fibers. These rules of thumb for considering the polymer solution properties and process parameters are expected to expand use of this platform for creating hierarchical structures of multiple fiber layers for cell scaffolds and additional applications

Migration as a Climate Change Adaptation Strategy: What Role do Emotions Play?

Climate change intersecting with complex socio-economic and political processes has produced distinctive patterns of crisis migration. However there exists a significant gap in understanding and theorizing these forms of migration creating significant policy challenges. Using a case study of an interstate migrant settlement in Bengaluru, India this article unpacks migration as an adaptation strategy through the lens of emotions. The article offers significant insights into how emotions affect the choice of migration as an adaptation strategy and shapes the differential experiences of risks and vulnerability for different groups of people. Emphasizing such relational aspects of migration, the article calls for more research that develops a nuanced understanding of the emotional landscapes of migrants across migration pathways

Ocean Vuong, on Earth We Are Briefly Gorgeous (USA: Penguin Press, 2019)

Set in New York, the book is filled with the experiences of a boy from Vietnam as he struggles with both his identity as well as sexuality. Even as everyone interprets a work of literature in their own way, I see a sense of urgency in the tone often taken by the author. There is an attempt to establish that all those living in one house may be dealing with more than one hierarchy in a neighborhood, a city, a country. What is unsettling is the impact of the perceptions of those around on the narrator and his family, the lack of acceptance for anything that looks different from the rest is exhausting and attacks the spirit of those who are already suffering from financial disparity as well as violence within a household. DOI: 10.5281/zenodo.431867