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Full-Text Articles in Physical Sciences and Mathematics
Fluorescence Microscopy With Deep Uv, Near Uv, And Visible Excitation For In Situ Detection Of Microorganisms, Noel Case, Nikki Johnston, Jay Nadeau
Fluorescence Microscopy With Deep Uv, Near Uv, And Visible Excitation For In Situ Detection Of Microorganisms, Noel Case, Nikki Johnston, Jay Nadeau
Physics Faculty Publications and Presentations
We report a simple, inexpensive design of a fluorescence microscope with light-emitting diode (LED) excitation for detection of labeled and unlabeled microorganisms in mineral substrates. The use of deep UV (DUV) excitation with visible emission requires no specialized optics or slides and can be implemented easily and inexpensively using an oblique illumination geometry. DUV excitation (<280 >nm) is preferable to near UV (365 nm) for avoidance of mineral autofluorescence. When excited with DUV, unpigmented bacteria show two emission peaks: one in the near UV ∼320 nm, corresponding to proteins, and another peak in the blue to green range, corresponding to …
Open-Inquiry Opens Doors To Intriguing Optics Experiments At Home: A Case Study, Paul R. Destefano, Ralf Widenhorn
Open-Inquiry Opens Doors To Intriguing Optics Experiments At Home: A Case Study, Paul R. Destefano, Ralf Widenhorn
Physics Faculty Publications and Presentations
[This paper is part of the Focused Collection on Instructional labs: Improving traditions and new directions.] This manuscript presents a case study of an introductory physics student who, during the remote learning conditions imposed during the COVID-19 pandemic, found inspiration within a new, openinquiry, project-based, laboratory curriculum designed at Portland State University. The phenomenon investigated by the study subject was intriguing to both the student and the lab instructors for its unfamiliar and instructive optical effect: a ring-shaped pattern or halo created by a laser diffusely reflected in a shallow body of water. Drawing on classwork and interview responses, this …
3F4 Hypergeometric Functions As A Sum Of A Product Of 2F3 Functions, Jack C. Straton
3F4 Hypergeometric Functions As A Sum Of A Product Of 2F3 Functions, Jack C. Straton
Physics Faculty Publications and Presentations
This paper shows that certain 3F4 hypergeometric functions can be expanded in sums of pair products of 2F3 functions, which reduce in special cases to 2F3 functions expanded in sums of pair products of 1F2 functions. This expands the class of hypergeometric functions having summation theorems beyond those expressible as pair-products of generalized Whittaker functions, 2F1 functions, and 3F2 functions into the realm of pFq functions where p < q for both the summand and terms in the series. In addition to its intrinsic value, this result has a specific application in calculating the response of the atoms to laser stimulation in the Strong Field Approximation.
The Fourier–Legendre Series Of Bessel Functions Of The First Kind And The Summed Series Involving 1F2 Hypergeometric Functions That Arise From Them, Jack C. Straton
The Fourier–Legendre Series Of Bessel Functions Of The First Kind And The Summed Series Involving 1F2 Hypergeometric Functions That Arise From Them, Jack C. Straton
Physics Faculty Publications and Presentations
The Bessel function of the first kind JN(kx) is expanded in a Fourier–Legendre series, as is the modified Bessel function of the first kind IN(kx). The purpose of these expansions in Legendre polynomials was not an attempt to rival established numerical methods for calculating Bessel functions but to provide a form for JN(kx) useful for analytical work in the area of strong laser fields, where analytical integration over scattering angles is essential. Despite their primary purpose, one can easily truncate the series at 21 terms to provide 33-digit accuracy that matches the IEEE extended precision in …
Integral Representations Over Finite Limits For Quantum Amplitudes, Jack C. Straton
Integral Representations Over Finite Limits For Quantum Amplitudes, Jack C. Straton
Physics Faculty Publications and Presentations
We extend previous research to derive three additional M-1-dimensional integral representations over the interval [0,1]" The prior version covered the interval [0,∞]" role="presentation position: relative;">[0,∞][0,∞]. This extension applies to products of M Slater orbitals, since they (and wave functions derived from them) appear in quantum transition amplitudes. It enables the magnitudes of coordinate vector differences (square roots of polynomials) |x1−x2|=x12−2x1x2cosθ+x22" to be shifted from disjoint products of functions into a single quadratic form, allowing for the completion of its square. The M-1-dimensional integral representations of M Slater orbitals that both this extension and the prior version introduce …
The Use Of Fluorescence Lifetime Imaging (Flim) For In Situ Microbial Detection In Complex Mineral Substrates, Yekaterina G. Chmykh, Jay Nadeau
The Use Of Fluorescence Lifetime Imaging (Flim) For In Situ Microbial Detection In Complex Mineral Substrates, Yekaterina G. Chmykh, Jay Nadeau
Physics Faculty Publications and Presentations
The utility of fluorescence lifetime imaging microscopy (FLIM) for identifying bacteria in complex mineral matrices was investigated. Baseline signals from unlabelled Bacillus subtilis and Euglena gracilis, and Bacillus subtilis labelled with SYTO 9 were obtained using two-photon excitation at 730, 750 and 800 nm, identifying characteristic lifetimes of photosynthetic pigments, unpigmented cellular autofluorescence, and SYTO 9. Labelled and unlabelled B. subtilis were seeded onto marble and gypsum samples containing endolithic photosynthetic cyanobacteria and the ability to distinguish cells from mineral autofluorescence and nonspecific dye staining was examined in parallel with ordinary multichannel confocal imaging. It was found that FLIM …