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Full-Text Articles in Physics
2d Vs 3d Tracking In Bacterial Motility Analysis, Jacqueline Acres, Jay Nadeau
2d Vs 3d Tracking In Bacterial Motility Analysis, Jacqueline Acres, Jay Nadeau
Physics Faculty Publications and Presentations
Digital holographic microscopy provides the ability to observe throughout a large volume without refocusing. This capability enables simultaneous observations of large numbers of microorganisms swimming in an essentially unconstrained fashion. However, computational tools for tracking large 4D datasets remain lacking. In this paper, we examine the errors introduced by tracking bacterial motion as 2D projections vs. 3D volumes under different circumstances: bacteria free in liquid media and bacteria near a glass surface. We find that while XYZ speeds are generally equal to or larger than XY speeds, they are still within empirical uncertainties. Additionally, when studying dynamic surface behavior, the …
Microscopic Object Classification Through Passive Motion Observations With Holographic Microscopy, Christian Lindensmith, Jay Nadeau, Manuel Bedrossian, Louis Sumrall, J. Kent Wallace, Eugene Serabyn
Microscopic Object Classification Through Passive Motion Observations With Holographic Microscopy, Christian Lindensmith, Jay Nadeau, Manuel Bedrossian, Louis Sumrall, J. Kent Wallace, Eugene Serabyn
Physics Faculty Publications and Presentations
Digital holographic microscopy provides the ability to observe throughout a volume that is large compared to its resolution element without the need to refocus through the volume. This capability enables simultaneous observations of large numbers of small objects within such a volume. We have constructed a microscope that can observe a volume 0.4 x 0.4 x 1.0 μm with submicrometer resolution for observation of microorganisms and minerals in liquid environments in earth and on potential planetary missions. Because environmental samples are likely to contain mixtures of inorganics and microorganisms that are of comparable sizes near the resolution limit of the …
Dipole Emission Characteristics Near A Topological Insulator Sphere Coated With A Metallic Nanoshell, Huai-Yi Xie, Railing Chang, P. T. Leung
Dipole Emission Characteristics Near A Topological Insulator Sphere Coated With A Metallic Nanoshell, Huai-Yi Xie, Railing Chang, P. T. Leung
Physics Faculty Publications and Presentations
Topological insulators (TI) are quantum states of (2D/3D) matter with an insulating interior but conducting edge/surface states, with these boundary conducting states being protected topologically by time-reversal symmetry. Composite materials of heavy atoms such as Bi2Te3 can be fabricated to show TI properties due to the strong intrinsic spin-orbit coupling of the electrons in these materials. Among the so many intriguing physical properties of these materials, their topological magneto-electric (TME) response is unique and has been studied intensively in the literature, leading to intriguing optical effects such as Faraday and Kerr rotations of incident polarized beams at …
The Influence Of Spaceflight And Simulated Microgravity On Bacterial Motility And Chemotaxis, Jacqueline Acres, Myka Jaap Youngapelian, Jay Nadeau
The Influence Of Spaceflight And Simulated Microgravity On Bacterial Motility And Chemotaxis, Jacqueline Acres, Myka Jaap Youngapelian, Jay Nadeau
Physics Faculty Publications and Presentations
As interest in space exploration rises, there is a growing need to quantify the impact of microgravity on the growth, survival, and adaptation of microorganisms, including those responsible for astronaut illness. Motility is a key microbial behavior that plays important roles in nutrient assimilation, tissue localization and invasion, pathogenicity, biofilm formation, and ultimately survival. Very few studies have specifically looked at the effects of microgravity on the phenotypes of microbial motility. However, genomic and transcriptomic studies give a broad general picture of overall gene expression that can be used to predict motility phenotypes based upon selected genes, such as those …
Using The Gouy Phase Anomaly To Localize And Track Bacteria In Digital Holographic Microscopy 4d Images, True Gibson, Manuel Bedrossian, Eugene Serabyn, Chris Lindensmith, Jay Nadeau
Using The Gouy Phase Anomaly To Localize And Track Bacteria In Digital Holographic Microscopy 4d Images, True Gibson, Manuel Bedrossian, Eugene Serabyn, Chris Lindensmith, Jay Nadeau
Physics Faculty Publications and Presentations
Described over 100 years ago, the Gouy phase anomaly refers to the additional π phase shift that is accumulated as a wave passes through focus. It is potentially useful in analyzing any type of phase-sensitive imaging; in light microscopy, digital holographic microscopy (DHM) provides phase information in the encoded hologram. One limitation of DHM is the weak contrast generated by many biological cells, especially unpigmented bacteria. We demonstrate here that the Gouy phase anomaly may be detected directly in the phase image using the z-derivative of the phase, allowing for precise localization of unlabeled, micrometer-sized bacteria. The use of dyes …