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Full-Text Articles in Physics
Long-Range And Chaotic Active Mixing Of Swimming Microbes In A Vortex Chain Flow, Nghia Le
Long-Range And Chaotic Active Mixing Of Swimming Microbes In A Vortex Chain Flow, Nghia Le
Honors Theses
We present experiments studying the motion and active mixing of swimming mi- crobes in laminar, vortex-dominated fluid flows. We are testing a theory that predicts the existence of swimming invariant manifolds (SwIMs) - invisible, one-way barriers blocking the paths of self-propelled tracers in the flow in one direction. We also pro- pose that the SwIMs together can form chute structures in three-dimensional phase space that facilitate cross-vortex transport of the microbes. We also observe evidence of how these structures promote long-range transport at different non-dimensional velocities (microbe’s velocity relative to flow velocity). Long-range transport is quan- tified by measuring the …
Pixe Analysis Of Heavy Metals In Soil Along The East River, Mia Villeneuve
Pixe Analysis Of Heavy Metals In Soil Along The East River, Mia Villeneuve
Honors Theses
We collected samples of soil from along the East River in Queens, New York, near the Hell Gate Bridge, on the Astoria Park side of the bridge in 2019 and on the Randall’s Island Park side in 2021. We performed proton-induced X-ray emission (PIXE) analysis on the samples and found that soil closer to the Hell Gate Bridge contained higher concentrations of heavy metals, specifically lead and zinc. Many of the soil samples contained lead concentrations greater than the EPA standard of 400 ppm. We also performed PIXE analysis on a sample of the paint used on the bridge and …
Electron-Positron Annihilation Lifetime Spectroscopy Of Mgo And Aluminum-Doped Mgo, Elise Liebow
Electron-Positron Annihilation Lifetime Spectroscopy Of Mgo And Aluminum-Doped Mgo, Elise Liebow
Honors Theses
Radiation is a form of energy that can damage materials at an atomic level. This has implications for the mobility of radioactive waste through containment materials. We are characterizing atomic defects in materials by using Electron-Positron Annihilation Lifetime Spectroscopy (EPALS). When an electron and positron come into contact with each other, they annihilate and release two antiparallel 511-keV gamma rays. In a pristine crystalline sample, positrons can easily annihilate with electrons, but in a sample with vacancies/defects in the crystal structure, positrons take longer to annihilate. Therefore, the more vacancies in a sample, the longer the average lifetime of a …
Quantumness And Coherence In Photosynthesis, Brian Doolittle
Quantumness And Coherence In Photosynthesis, Brian Doolittle
Honors Theses
Long-lived oscillations lasting up to 1800 fs have been observed in the Fenna--Mathews--Olsen (FMO) Pigment-Protein complex. It is unclear if the oscillations are quantum or classical in origin. Quantized intra-pigment normal modes are responsible for these long-lived oscillations. In this thesis we simulate a bacteriachlorophyll dimer in the FMO Complex at physiological conditions. Our model describes two electronically coupled pigments coupled to the vibrational protein environment. Our goal is to find system parameters that allow long-lived quantum coherences to exist in photosynthetic complexes. We calculate the time evolution of our system's density matrix using the numerically exact quantum adiabatic path …