High resolution study of the solar atmosphere Final report

High resolution study of solar atmosphere of H alpha lin

The Ubiquity of Sidon Sets That Are Not I0I_0

We prove that every infinite, discrete abelian group admits a pair of $I_0$ sets whose union is not $I_0$. In particular, this implies that every such group contains a Sidon set that is not $I_{0}$

A quantification of hydrodynamical effects on protoplanetary dust growth

Context. The growth process of dust particles in protoplanetary disks can be modeled via numerical dust coagulation codes. In this approach, physical effects that dominate the dust growth process often must be implemented in a parameterized form. Due to a lack of these parameterizations, existing studies of dust coagulation have ignored the effects a hydrodynamical gas flow can have on grain growth, even though it is often argued that the flow could significantly contribute either positively or negatively to the growth process. Aims. We intend to provide a quantification of hydrodynamical effects on the growth of dust particles, such that these effects can be parameterized and implemented in a dust coagulation code. Methods. We numerically integrate the trajectories of small dust particles in the flow of disk gas around a proto-planetesimal, sampling a large parameter space in proto-planetesimal radii, headwind velocities, and dust stopping times. Results. The gas flow deflects most particles away from the proto-planetesimal, such that its effective collisional cross section, and therefore the mass accretion rate, is reduced. The gas flow however also reduces the impact velocity of small dust particles onto a proto-planetesimal. This can be beneficial for its growth, since large impact velocities are known to lead to erosion. We also demonstrate why such a gas flow does not return collisional debris to the surface of a proto-planetesimal. Conclusions. We predict that a laminar hydrodynamical flow around a proto-planetesimal will have a significant effect on its growth. However, we cannot easily predict which result, the reduction of the impact velocity or the sweep-up cross section, will be more important. Therefore, we provide parameterizations ready for implementation into a dust coagulation code.Comment: 9 pages, 6 figures; accepted for publication in A&A; v2 matches the manuscript sent to the publisher (very minor changes

Fence and Gates for the City Farm SLO

This paper summarizes the construction of roughly 300 feet of game fence and two metal gates for the City Farm San Luis Obispo (SLO). The City Farm SLO is a nonprofit organization in San Luis Obispo, CA. They are focused on organic and sustainable agriculture. This paper will highlight the process for estimating, funding, scheduling, and constructing the fence and gates. This project aimed to provide a secure perimeter against pedestrians and wildlife. The project site is along the creek, attracting many unwanted guests. There were many obstacles to overcome throughout the project, from preconstruction to construction. Each phase had its own unique challenges. The first hurdle was obtaining funding. Many hours were spent calling local contractors and politicians until I finally received the money to complete my project. The second obstacle faced was the construction of the project. Finding the labor and time to complete the work was a challenge. Despite these, and multiple other obstacles discussed throughout the paper, the project was completed allowing the City Farm SLO to have an area protected against wildlife and pedestrians. The project was completed on time and within budget. Finally, the project fulfilled all items requested from the City Farm SLO