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Articles 1 - 30 of 539
Full-Text Articles in Physics
Feedback Indices To Evaluate Llm Responses To Rebuttals For Multiple Choice Type Questions, Justin C. Dunlap, Anne-Simone Parent, Ralf Widenhorn
Feedback Indices To Evaluate Llm Responses To Rebuttals For Multiple Choice Type Questions, Justin C. Dunlap, Anne-Simone Parent, Ralf Widenhorn
Physics Faculty Publications and Presentations
We present a set of indices designed to characterize Large Language Model (LLM) responses when challenged with rebuttals during a chat. Assessing how LLMs respond to user dissent is crucial for understanding their reliability and behavior patterns, yet the complexity of human-LLM interactions makes systematic evaluation challenging. Our approach employs a fictitious-response rebuttal method that quantifies LLM behavior when presented with multiple-choice questions followed by deliberate challenges to their fictitious previous response. The indices are specifically designed to detect and measure what could be characterized as sycophantic behavior (excessive agreement with user challenges) or stubborn responses (rigid adherence to the …
An Infinite Set Of One-Range Addition Theorems Without An Infinite Second Series, For Slater Orbitals And Their Derivatives, Applicable To Multiple Coordinate Systems, Jack C. Straton
Physics Faculty Publications and Presentations
Addition theorems have been indispensable tools for the reduction of quantum transition amplitudes. They are normally utilized at the start of the process to move the angular dependence within plane waves, Coulomb potentials, and the like, into a sum over spherical harmonics that allows the angular integration to be carried out. These have historically been “two-range” addition theorems, characterized by the two-fold notation r>=Max[r1,r2] and r< =Min[r1,r2] and comprising a single infinite series. More recently, “one-range” addition theorems have been created that have no such piecewise notation, but at the cost of the introduction of another infinite series. We use a very different approach to derive an infinite set of addition theorems for Slater orbitals, hydrogenic and Hylleraas wave functions, and so on, that retain the one-range variable dependence but have, at worst, a finite second series rather than an infinite one. In addition, unlike previous addition theorems, they are applicable to more than one coordinate system. One of these addition theorems may also be used for Yukawa-like functions that may appear late in the reduction of amplitude integrals, and we show its utility for an integral that has stubbornly defied reduction to analytic form for nearly sixty years. Finally, we craft indefinite integrals of 15 half-integer Macdonald functions multiplied by (inverse) powers and negative exponentials containing squares of the integration variable.
Microbial Communities Of Selected Regions Of The Deep Springs Lake Aquifer System, Rania Zaki, Emma Bourne, Andrew Storino, Jay Nadeau
Microbial Communities Of Selected Regions Of The Deep Springs Lake Aquifer System, Rania Zaki, Emma Bourne, Andrew Storino, Jay Nadeau
Physics Faculty Publications and Presentations
Deep Springs Lake is a small, isolated, highly alkaline soda lake in Inyo County of Eastern California, USA. It is a seasonally filled salt lake or playa, and is part of a closed aquifer system. Such closed systems are globally rare, occurring only in arid zones where annual evaporation is greater than annual rainfall. Deep Springs Lake’s hydrology and geology have been well studied, and it is home to a unique toad species, but its microbiome remains unexplored. Here we perform 16S, 18S, and ITS amplicon sequencing of the lake water, dried salt crust at the edges the lake, and …
Synthesis And Characterization Of Highly Stable Fisetin Encapsulated In Lecithin-Chitosan-Savie Nanoparticles, Hart Monyatovsky, Travis Anderson, Jay Nadeau
Synthesis And Characterization Of Highly Stable Fisetin Encapsulated In Lecithin-Chitosan-Savie Nanoparticles, Hart Monyatovsky, Travis Anderson, Jay Nadeau
Physics Faculty Publications and Presentations
Senolytic drugs, of the class of polyphenolic flavonoids, have attracted attention for a wide variety of medical applications for which they may be delivered topically, orally, and/or intravenously. However, due to their hydrophobicity and sensitivity to light and oxygen, they have been proven difficult to package and deliver. Here we report a synthesis method for encapsulated fisetin using lecithin-chitosan ionic gelation with a recently reported surfactant that is an alternative to polyethylene glycol (PEG)-containing compounds. Called “Savie” for a contraction of its components, sarcosine-Vitamin E, this surfactant allows for production of sub-100 nm nanoparticles that are bench stable for at …
Spectrum Analysis Of Thermally Driven Curvature Inversion In Strained Graphene Ripples For Energy Conversion Applications Via Molecular Dynamics, James M. Mangum, Md R. Kabir, Tamzeed B. Amin, Syed M. Rahman, Ashaduzzaman, Paul M. Thibado
Spectrum Analysis Of Thermally Driven Curvature Inversion In Strained Graphene Ripples For Energy Conversion Applications Via Molecular Dynamics, James M. Mangum, Md R. Kabir, Tamzeed B. Amin, Syed M. Rahman, Ashaduzzaman, Paul M. Thibado
Physics Faculty Publications and Presentations
The extraordinary mechanical flexibility, high electrical conductivity, and nanoscale instability of freestanding graphene make it an excellent candidate for vibration energy harvesting. When freestanding graphene is stretched taut and subject to external forces, it will vibrate like a drum head. Its vibrations occur at a fundamental frequency along with higher-order harmonics. Alternatively, when freestanding graphene is compressed, it will arch slightly out of the plane or buckle under the load. Remaining flat under compression would be energetically too costly compared to simple bond rotations. Buckling up or down, also known as ripple formation, naturally creates a bistable situation. When the …
Teaching Diffuse, Specular, And Total Internal Reflection Via A Halo Effect, Paul R. Destefano, Ralf Widenhorn
Teaching Diffuse, Specular, And Total Internal Reflection Via A Halo Effect, Paul R. Destefano, Ralf Widenhorn
Physics Faculty Publications and Presentations
Interesting and pedagogically useful physics can be found in the halo produced by a laser pointer directed into a shallow body of water. We describe a simple model for this phenomenon using geometric optics and support this model with empirical evidence. We also discuss and verify extensions to this model that explain variations in the visual pattern. These variants include a double halo pattern and a disk of dim light that can be produced with minor modifications of the single halo configuration. Although the level of complexity differs, all of these models rely on the same ray optics, specifically refraction …
Glacial-Interglacial And Millennial-Scale Changes In Nitrous Oxide Emissions Pathways And Source Regions, J. A. Menking, J. E. Lee, E. J. Brook, J. Schmitt, L. Soussaintjean, H. Fischer, J. Kaiser, A. Rice
Glacial-Interglacial And Millennial-Scale Changes In Nitrous Oxide Emissions Pathways And Source Regions, J. A. Menking, J. E. Lee, E. J. Brook, J. Schmitt, L. Soussaintjean, H. Fischer, J. Kaiser, A. Rice
Physics Faculty Publications and Presentations
During the transition from the Last Glacial Maximum (LGM) to the Holocene, the atmospheric N2O mole fraction increased by 80 nmol mol−1. Using ice core measurements of N2O isotopomer ratios, we show that this increase was driven by increases in both nitrification and denitrification, with the relative partitioning between both production pathways depending on the assumed isotopic end‐member source signatures. Similarly, we also attribute a 35 nmol mol−1 N2O mole fraction increase during the Heinrich Stadial 4/Dansgaard Oeschger 8 (HS4/DO8) millennial‐scale event to increases in both N2O production pathways. In contrast, the 25 nmol mol−1 N2O mole fraction decrease during …
Extant Life Detection Using Label-Free Video Microscopy In Analog Aquatic Environments, Carl D. Snyder, Manuel Bedrossian, Casey Barr, Jody W. Deming, Chris A. Lindensmith, Christian Stenner, Jay L. Nadeau
Extant Life Detection Using Label-Free Video Microscopy In Analog Aquatic Environments, Carl D. Snyder, Manuel Bedrossian, Casey Barr, Jody W. Deming, Chris A. Lindensmith, Christian Stenner, Jay L. Nadeau
Physics Faculty Publications and Presentations
The ability of microbial active motion, morphology, and optical properties to serve as biosignatures was investigated by in situ video microscopy in a wide range of extreme field sites where such imaging had not been performed previously. These sites allowed for sampling seawater, sea ice brines, cryopeg brines, hypersaline pools and seeps, hyperalkaline springs, and glaciovolcanic cave ice. In all samples except the cryopeg brine, active motion was observed without any sample treatment. Active motion was observed in the cryopeg brines when samples were subjected to a temperature gradient above in situ. In general, levels of motility were low in …
3F4 Hypergeometric Functions As A Sum Of A Product Of 1F2 Functions, Jack C. Straton
3F4 Hypergeometric Functions As A Sum Of A Product Of 1F2 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 1F2 functions. In special cases, the 3F4 hypergeometric functions reduce to 2F3 functions. Further special cases allow one to reduce the 2F3 functions to 1F2 functions, and the sums to products of 0F1 (Bessel) and 1F2 functions. The class of hypergeometric functions with summation theorems are thereby expanded beyond those expressible as pair-products of 2F1 functions, 3F2 functions, and generalized Whittaker functions, into …
Descending An Inclined Plane With A Large Language Model, Justin C. Dunlap, Ryan Sissons, Ralf Widenhorn
Descending An Inclined Plane With A Large Language Model, Justin C. Dunlap, Ryan Sissons, Ralf Widenhorn
Physics Faculty Publications and Presentations
[This paper is part of the Focused Collection in Artificial Intelligence Tools in Physics Teaching and Physics Education Research.] We present a study in which a version of a common conservation of mechanical energy introductory physics problem, an object released on an inclined plane, is given to OpenAI’s GPT-4 large language model (LLM). We investigate how different permutations of object, action verb, and property of the incline impact the responses of the LLM. The problem setup and prompting was left purposefully minimal, requiring the LLM to state multiple assumptions to justify the final answer. We specifically studied how different keywords …
Distinct Composition-Dependent Topological Hall Effect In Mn2-Xznxsb, Md Rafique Un Nabi, Yue Li, Suzanne G.E. Te Velthuis, Santosh Karki Chhetri, Dinesh Upreti, Rabindra Basnet, Gokul Acharya, Charudatta Phatak, Jin Hu
Distinct Composition-Dependent Topological Hall Effect In Mn2-Xznxsb, Md Rafique Un Nabi, Yue Li, Suzanne G.E. Te Velthuis, Santosh Karki Chhetri, Dinesh Upreti, Rabindra Basnet, Gokul Acharya, Charudatta Phatak, Jin Hu
Physics Faculty Publications and Presentations
Spintronics, an evolving interdisciplinary field at the intersection of magnetism and electronics, explores innovative applications of electron charge and spin properties for advanced electronic devices. The topological Hall effect (THE), a key component in spintronics, has gained significance due to emerging theories surrounding noncoplanar chiral spin textures. This study focuses on Mn2-xZnxSb, a material crystalizing in centrosymmetric space group with rich magnetic phases tunable by Zn contents. Through comprehensive magnetic and transport characterizations, we found that the high-Zn (x > 0.6) samples display THE which is enhanced with decreasing temperature, while THE in the low-Zn ( …
Reconfigurable Photonic Lattices Based On Atomic Coherence, Jiaqi Yuan, Shun Liang, Qingsong Yu, Chiangbao Li, Yanpeng Zhang, Min Xiao, Zhaoyang Zhang
Reconfigurable Photonic Lattices Based On Atomic Coherence, Jiaqi Yuan, Shun Liang, Qingsong Yu, Chiangbao Li, Yanpeng Zhang, Min Xiao, Zhaoyang Zhang
Physics Faculty Publications and Presentations
The array of coupled optical waveguides, which is also viewed as a photonic lattice, can exhibit abundant photonic band structures depending on the desired spatial arrangements of involved waveguides. Studies of photonic lattices are usually performed in solid-state materials, where the required periodic susceptibilities can be achieved by employing the femtosecond laser direct-writing or optical induction method, and have spawned flourishing achievements in manipulating the behaviors of light. Recently, the concept of electromagnetically induced photonic lattice (EIPL) is proposed under the well-known electromagnetically induced transparency (EIT) in coherently prepared multilevel alkali-metal atomic systems, where the strong coupling beams producing EIT …
Summed Series Involving 1F2 Hypergeometric Functions, Jack C. Straton
Summed Series Involving 1F2 Hypergeometric Functions, Jack C. Straton
Physics Faculty Publications and Presentations
Summation of infinite series has played a significant role in a broad range of problems in the physical sciences and is of interest in a purely mathematical context. In a prior paper, we found that the Fourier–Legendre series of a Bessel function of the first kind JN(kx) and modified Bessel functions of the first kind IN(kx) lead to an infinite set of series involving 1F2 hypergeometric functions (extracted therefrom) that could be summed, having values that are inverse powers of the eight primes 1/ ( 2i 3j 5k …
Insulator-To-Metal Transition And Isotropic Gigantic Magnetoresistance In Layered Magnetic Semiconductors, Gokul Acharya, Bimal Neupane, Chia-Hsiu Hsu, Xian P. Yang, David Graf, Eun Sang Choi, Krishna Pandey, Md Rafique Un Nabi, Santosh Karki Chhetri, Rabindra Basnet, Sumaya Rahman, Jian Wang, Zhengxin Hu, Bo Da, Hugh O.H. Churchill, Guoqing Chang, M. Zahid Hasan, Yuanxi Wang, Jin Hu
Insulator-To-Metal Transition And Isotropic Gigantic Magnetoresistance In Layered Magnetic Semiconductors, Gokul Acharya, Bimal Neupane, Chia-Hsiu Hsu, Xian P. Yang, David Graf, Eun Sang Choi, Krishna Pandey, Md Rafique Un Nabi, Santosh Karki Chhetri, Rabindra Basnet, Sumaya Rahman, Jian Wang, Zhengxin Hu, Bo Da, Hugh O.H. Churchill, Guoqing Chang, M. Zahid Hasan, Yuanxi Wang, Jin Hu
Physics Faculty Publications and Presentations
Magnetotransport, the response of electrical conduction to external magnetic field, acts as an important tool to reveal fundamental concepts behind exotic phenomena and plays a key role in enabling spintronic applications. Magnetotransport is generally sensitive to magnetic field orientations. In contrast, efficient and isotropic modulation of electronic transport, which is useful in technology applications such as omnidirectional sensing, is rarely seen, especially for pristine crystals. Here a strategy is proposed to realize extremely strong modulation of electron conduction by magnetic field which is independent of field direction. GdPS, a layered antiferromagnetic semiconductor with resistivity anisotropies, supports a field-driven insulator-to-metal transition …
Substrate Interference And Strain In The Second-Harmonic Generation From Mose2 Monolayers, Sudeep Puri, Sneha Patel, Jose Luis Cabellos, Luis Enrique Rosas-Hernandez, Kaitlin Reynolds, Hugh O.H. Churchill, Salvador Barraza-Lopez, Bernardo S. Mendoza, Hiroyuki Nakamura
Substrate Interference And Strain In The Second-Harmonic Generation From Mose2 Monolayers, Sudeep Puri, Sneha Patel, Jose Luis Cabellos, Luis Enrique Rosas-Hernandez, Kaitlin Reynolds, Hugh O.H. Churchill, Salvador Barraza-Lopez, Bernardo S. Mendoza, Hiroyuki Nakamura
Physics Faculty Publications and Presentations
Nonlinear optical materials of atomic thickness, such as non-centrosymmetric 2H transition metal dichalcogenide monolayers, have a second-order nonlinear susceptibility (χ(2)) whose intensity can be tuned by strain. However, whether χ(2) is enhanced or reduced by tensile strain is a subject of conflicting reports. Here, we grow high-quality MoSe2 monolayers under controlled biaxial strain created by two different substrates and study their linear and nonlinear optical responses with a combination of experimental and theoretical approaches. Up to a 15-fold overall enhancement in second-harmonic generation (SHG) intensity is observed from MoSe2 monolayers grown on SiO2 when …
Understanding And Tuning Magnetism In Van Der Waals-Type Metal Thiophosphates, Rabindra Basnet, Jin Hu
Understanding And Tuning Magnetism In Van Der Waals-Type Metal Thiophosphates, Rabindra Basnet, Jin Hu
Physics Faculty Publications and Presentations
Over the past two decades, significant progress in two-dimensional (2D) materials has invigorated research in condensed matter and material physics in low dimensions. While traditionally studied in three-dimensional systems, magnetism has now been extended to the 2D realm. Recent breakthroughs in 2D magnetism have attracted substantial interest from the scientific community, owing to the stable magnetic order achievable in atomically thin layers of the van der Waals (vdW)-type layered magnetic materials. These advances offer an exciting platform for investigating related phenomena in low dimensions and hold promise for spintronic applications. Consequently, vdW magnetic materials with tunable magnetism have attracted significant …
Monitoring Water Meniscus Formation At Nanocontacts With Shear-Force Acousto Near-Field Microscopy, Xiaohua Wang, Rodolfo Fernandez, Theodore Brockman, Kacharat Supichayanggoon, Andres H. La Rosa
Monitoring Water Meniscus Formation At Nanocontacts With Shear-Force Acousto Near-Field Microscopy, Xiaohua Wang, Rodolfo Fernandez, Theodore Brockman, Kacharat Supichayanggoon, Andres H. La Rosa
Physics Faculty Publications and Presentations
Shear-force acoustic near-field microscopy (SANM) is employed to monitor stochastic formation and post dynamic response of a water meniscus that bridges a tapered gold probe (undergoing lateral oscillations of a few nanometers amplitude at constant frequency) and a flat (gold or silicon oxide) substrate. As the probe further approaches the substrate, its amplitude decreases. Shear forces (of yet unknown precise origin) are typically invoked to explain the apparently pure damping effects affecting the probe's motion. Herein, SANM measurements underscore instead the role of near-field acoustic emission from the water meniscus as an elastic energy dissipation channel involved in shear interactions. …
Defect-Free Nanowelding Of Bilayer Snse Nanoplates, Jing-Rong Ji, John W. D. Villanova, Salvador Barraza-Lopez, Stuart S. P. Parkin, Kai Chang
Defect-Free Nanowelding Of Bilayer Snse Nanoplates, Jing-Rong Ji, John W. D. Villanova, Salvador Barraza-Lopez, Stuart S. P. Parkin, Kai Chang
Physics Faculty Publications and Presentations
Nanowelding is a bottom-up technique to create custom-designed nanostructures and devices beyond the precision of lithographic methods. Here, a new technique is reported based on anisotropic lubricity at the van der Waals interface between monolayer and bilayer SnSe nanoplates and a graphene substrate to achieve precise control of the crystal orientation and the interface during the welding process. As-grown SnSe monolayer and bilayer nanoplates are commensurate with graphene's armchair direction but lack commensuration along graphene's zigzag direction, resulting in a reduced friction along that direction and a rail-like, 1D movement that permits joining nanoplates with high precision. This way, molecular …
Motion History Images: A New Method For Tracking Microswimmers In 3d, Max Riekeles, Hadi Albalkhi, Megan Marie Dubay, Jay Nadeau, Christian A. Lindensmith
Motion History Images: A New Method For Tracking Microswimmers In 3d, Max Riekeles, Hadi Albalkhi, Megan Marie Dubay, Jay Nadeau, Christian A. Lindensmith
Physics Faculty Publications and Presentations
Quantitative tracking of rapidly moving micron-scale objects remains an elusive challenge in microscopy due to low signal-to-noise. This paper describes a novel method for tracking micron-sized motile organisms in off-axis Digital Holographic Microscope (DHM) raw holograms and/or reconstructions. We begin by processing the microscopic images with the previously reported Holographic Examination for Life-like Motility (HELM) software, which provides a variety of tracking outputs including motion history images (MHIs). MHIs are stills of videos where the frame-to-frame changes are indicated with color time-coding. This exposes tracks of objects that are difficult to identify in individual frames at a low signal-to-noise ratio. …
Impact Of Property Covariance On Cluster Weak Lensing Scaling Relations, Zhuowen Zhang, Arya Farahi, Daisuke Nagai, Erwin T. Lau, Joshua Frieman, Marina Ricci, Anja Von Der Linden, Hao-Yi Wu, Lsst Dark Energy Science Collaboration
Impact Of Property Covariance On Cluster Weak Lensing Scaling Relations, Zhuowen Zhang, Arya Farahi, Daisuke Nagai, Erwin T. Lau, Joshua Frieman, Marina Ricci, Anja Von Der Linden, Hao-Yi Wu, Lsst Dark Energy Science Collaboration
Physics Faculty Publications and Presentations
We present an investigation into a hitherto unexplored systematic that affects the accuracy of galaxy cluster mass estimates with weak gravitational lensing. Specifically, we study the covariance between the weak lensing signal, ΔΣ, and the ‘true’ cluster galaxy number count, Ngal, as measured within a spherical volume that is void of projection effects. By quantifying the impact of this covariance on mass calibration, this work reveals a significant source of systematic uncertainty. Using the MDPL2 simulation with galaxies traced by the SAGE semi-analytic model, we measure the intrinsic property covariance between these observables within the three-dimensional vicinity of …
Spin Disorder Control Of Topological Spin Texture, Hongrui Zhang, Yu-Tsun Shao, Xiang Chen, Binhua Zhang, Tianye Wang, Fanhao Meng, Kun Xu, Peter Meisenheimer, Xianzhe Chen, Xiaoxi Huang, Piush Behera, Sajid Husain, Tiancong Zhu, Hao Pan, Yanli Jia, Nick Settineri, Nathan Giles-Donovan, Zehao He, Andreas Scholl, Alpha N'Diaye, Padraic Shafer, Archana Raja, Changsong Xu, Lane W. Martin, Michael F. Crommie, Jie Yao, Ziqiang Qiu, Arun Majumdar, Laurent Bellaiche, David A. Muller, Robert J. Birgeneau, Ramamoorthy Ramesh
Spin Disorder Control Of Topological Spin Texture, Hongrui Zhang, Yu-Tsun Shao, Xiang Chen, Binhua Zhang, Tianye Wang, Fanhao Meng, Kun Xu, Peter Meisenheimer, Xianzhe Chen, Xiaoxi Huang, Piush Behera, Sajid Husain, Tiancong Zhu, Hao Pan, Yanli Jia, Nick Settineri, Nathan Giles-Donovan, Zehao He, Andreas Scholl, Alpha N'Diaye, Padraic Shafer, Archana Raja, Changsong Xu, Lane W. Martin, Michael F. Crommie, Jie Yao, Ziqiang Qiu, Arun Majumdar, Laurent Bellaiche, David A. Muller, Robert J. Birgeneau, Ramamoorthy Ramesh
Physics Faculty Publications and Presentations
Stabilization of topological spin textures in layered magnets has the potential to drive the development of advanced low-dimensional spintronics devices. However, achieving reliable and flexible manipulation of the topological spin textures beyond skyrmion in a two-dimensional magnet system remains challenging. Here, we demonstrate the introduction of magnetic iron atoms between the van der Waals gap of a layered magnet, Fe3GaTe2, to modify local anisotropic magnetic interactions. Consequently, we present direct observations of the order-disorder skyrmion lattices transition. In addition, non-trivial topological solitons, such as skyrmioniums and skyrmion bags, are realized at room temperature. Our work highlights …
Algorithm-Based Linearly Graded Compositions Of Gesn On Gaas (001) Via Molecular Beam Epitaxy, Calbi Gunder, Mohammad Zamani-Alavijeh, Emmanuel Wangila, Fernando Maia De Oliveira, Aida Sheibani, Serhii Kryvyi, Paul C. Attwood, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo
Algorithm-Based Linearly Graded Compositions Of Gesn On Gaas (001) Via Molecular Beam Epitaxy, Calbi Gunder, Mohammad Zamani-Alavijeh, Emmanuel Wangila, Fernando Maia De Oliveira, Aida Sheibani, Serhii Kryvyi, Paul C. Attwood, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo
Physics Faculty Publications and Presentations
The growth of high-composition GeSn films in the future will likely be guided by algorithms. In this study, we show how a logarithmic-based algorithm can be used to obtain high-quality GeSn compositions up to 16% on GaAs (001) substrates via molecular beam epitaxy. Herein, we use composition targeting and logarithmic Sn cell temperature control to achieve linearly graded pseudomorph Ge1−xSnx compositions up to 10% before partial relaxation of the structure and a continued gradient up to 16% GeSn. In this report, we use X-ray diffraction, simulation, secondary ion mass spectrometry, and atomic force microscopy to analyze and …
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 …
Effects Of Heterogeneous Data Sets And Time-Lag Measurement Techniques On Cosmological Parameter Constraints From Mg Ii And C Iv Reverberation-Mapped Quasar Data, Shulei Cao, Michal Zajaček, Bożena Czerny, Swayamtrupta Panda, Bharat Ratra
Effects Of Heterogeneous Data Sets And Time-Lag Measurement Techniques On Cosmological Parameter Constraints From Mg Ii And C Iv Reverberation-Mapped Quasar Data, Shulei Cao, Michal Zajaček, Bożena Czerny, Swayamtrupta Panda, Bharat Ratra
Physics Faculty Publications and Presentations
Previously, we demonstrated that Mg II and C IV reverberation-mapped quasars (RM QSOs) are standardizable and that the cosmological parameters inferred using the broad-line region radius–luminosity (R–L) relation are consistent with those determined from better-established cosmological probes. With more data expected from ongoing and future spectroscopic and photometric surveys, it is imperative to examine how new QSO data sets of varied quality, with their own specific luminosity and time-delay distributions, can be best used to determine more restrictive cosmological parameter constraints. In this study, we test the effect of adding 25 OzDES Mg II RM QSOs as well …
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.
Association Of Alpha-Crystallin With Human Cortical And Nuclear Lens Lipid Membrane Increases With The Grade Of Cortical And Nuclear Cataract, Preston Hazen, Geraline Trossi-Torres, Raju Timsina, Nawal K. Khadka, Laxman Mainali
Association Of Alpha-Crystallin With Human Cortical And Nuclear Lens Lipid Membrane Increases With The Grade Of Cortical And Nuclear Cataract, Preston Hazen, Geraline Trossi-Torres, Raju Timsina, Nawal K. Khadka, Laxman Mainali
Physics Faculty Publications and Presentations
Eye lens α-crystallin has been shown to become increasingly membrane-bound with age and cataract formation; however, to our knowledge, no studies have investigated the membrane interactions of α-crystallin throughout the development of cataracts in separated cortical membrane (CM) and nuclear membrane (NM) from single human lenses. In this study, four pairs of human lenses from age-matched male and female donors and one pair of male lenses ranging in age from 64 to 73 years old (yo) were obtained to investigate the interactions of α-crystallin with the NM and CM throughout the progression of cortical cataract (CC) and nuclear cataract (NC) …
Cholesterol Content Regulates The Interaction Of Αa-, Αb-, And Α-Crystallin With The Model Of Human Lens-Lipid Membranes, Raju Timsina, Preston Hazen, Geraline Trossi-Torres, Nawal K. Khadka, Navdeep Kalkat, Laxman Mainali
Cholesterol Content Regulates The Interaction Of Αa-, Αb-, And Α-Crystallin With The Model Of Human Lens-Lipid Membranes, Raju Timsina, Preston Hazen, Geraline Trossi-Torres, Nawal K. Khadka, Navdeep Kalkat, Laxman Mainali
Physics Faculty Publications and Presentations
α-Crystallin (αABc) is a major protein comprised of αA-crystallin (αAc) and αB-crystallin (αBc) that is found in the human eye lens and works as a molecular chaperone by preventing the aggregation of proteins and providing tolerance to stress. However, with age and cataract formation, the concentration of αABc in the eye lens cytoplasm decreases, with a corresponding increase in the membrane-bound αABc. This study uses the electron paramagnetic resonance (EPR) spin-labeling method to investigate the role of cholesterol (Chol) and Chol bilayer domains (CBDs) in the binding of αAc, αBc, and αABc to the Chol/model of human lens-lipid (Chol/MHLL) membranes. …
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 …