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Articles 1 - 27 of 27
Full-Text Articles in Physical Sciences and Mathematics
Strain-Driven Growth Of Gaas(111) Quantum Dots With Low Fine Structure Splitting, Paul J. Simmonds
Strain-Driven Growth Of Gaas(111) Quantum Dots With Low Fine Structure Splitting, Paul J. Simmonds
Physics Faculty Publications and Presentations
Symmetric quantum dots (QDs) on (111)-oriented surfaces are promising candidates for generating polarization-entangled photons due to their low excitonic fine structure splitting(FSS). However, (111) QDs are difficult to grow. The conventional use of compressive strain to drive QD self-assembly fails to form 3D nanostructures on (111) surfaces. Instead, we demonstrate that (111) QDs self-assemble under tensile strain by growing GaAs QDs on an InP(111)A substrate. Tensile GaAs self-assembly produces a low density of QDs with a symmetric triangular morphology. Coherent, tensile QDs are observed without dislocations, and the QDs luminescence at room temperature. Single QD measurements reveal low FSS with …
Charge On Luminous Bodies Resembling Natural Ball Lightning Produced Via Electrical Arcs Through Lump Silicon, Christina L. Porter, Galen P. Miley, David J. Griffiths, Erik J. Sánchez
Charge On Luminous Bodies Resembling Natural Ball Lightning Produced Via Electrical Arcs Through Lump Silicon, Christina L. Porter, Galen P. Miley, David J. Griffiths, Erik J. Sánchez
Physics Faculty Publications and Presentations
A phenomenon resembling natural ball lightning can be produced via electrical arcing through silicon. We use lump silicon instead of silicon wafers to achieve higher production rates and larger, longer-lived luminous balls than previously reported. The luminous balls consist of a silicon core surrounded by a porous network of loosely bound silicon dioxide nanoparticles. We find that the balls carry a small net charge on the order of 10−12 C and propose that the nanoparticles are electrostatically bound to the core due to this charge.
Extended Necessary Condition For Local Operations And Classical Communication: Tight Bound For All Measurements, Scott M. Cohen
Extended Necessary Condition For Local Operations And Classical Communication: Tight Bound For All Measurements, Scott M. Cohen
Physics Faculty Publications and Presentations
We give a necessary condition that a separable measurement can be implemented by local quantum operations and classical communication (LOCC) in any finite number of rounds of communication, generalizing and strengthening a result obtained previously. That earlier result involved a bound that is tight when the number of measurement operators defining the measurement is relatively small. The present results generalize that bound to one that is tight for any finite number of measurement operators, and we also provide an extension which holds when that number is infinite. We apply these results to the famous example on a 3 × 3 …
Kinetic Competition During The Transcription Cycle Results In Stochastic Rna Processing, Antoine Coulon, Matthew L. Ferguson, Valeria De Turris, Murali Palangat, Carson C. Chow, Daniel R. Larson
Kinetic Competition During The Transcription Cycle Results In Stochastic Rna Processing, Antoine Coulon, Matthew L. Ferguson, Valeria De Turris, Murali Palangat, Carson C. Chow, Daniel R. Larson
Physics Faculty Publications and Presentations
Synthesis of mRNA in eukaryotes involves the coordinated action of many enzymatic processes, including initiation, elongation, splicing, and cleavage. Kinetic competition between these processes has been proposed to determine RNA fate, yet such coupling has never been observed in vivo on single transcripts. In this study, we use dual-color single-molecule RNA imaging in living human cells to construct a complete kinetic profile of transcription and splicing of the β-globin gene. We find that kinetic competition results in multiple competing pathways for pre-mRNA splicing. Splicing of the terminal intron occurs stochastically both before and after transcript release, indicating there is not …
Positional Control Of Plasmonic Fields And Electron Emission, Robert Campbell Word, Joseph P. Fitzgerald, Rolf Könenkamp
Positional Control Of Plasmonic Fields And Electron Emission, Robert Campbell Word, Joseph P. Fitzgerald, Rolf Könenkamp
Physics Faculty Publications and Presentations
We report the positional control of plasmonic fields and electron emission in a continuous gap antenna structure of sub-micron size. We show experimentally that a nanoscale area of plasmon-enhanced electron emission can be motioned by changing the polarization of an exciting optical beam of 800 nm wavelength. Finite-difference calculations are presented to support the experiments and to show that the plasmon-enhanced electric field distribution of the antenna can be motioned precisely and predictively.
3d Systems' Technology Overview And New Applications In Manufacturing, Engineering, Science, And Education, Trevor Snyder, Mike Andrews, Mark M. Weislogel, Peter Moeck, Jennifer Stone-Sundberg, Derek Birkes, Madeline Paige Hoffert, Adam Lindeman, Jeff Morrill, Ondrej Fercak, Sasha Friedman, Jeff Gunderson, Anh Ha, Jack Mccollister, Yongkang Chen, John T. Geile, Andrew Paul Wollman, Babek Attari, Nathan Botnen, Vasant Vuppuluri, Jennifer Shim, Werner Kaminsky, Dustin Adams, John Graft
3d Systems' Technology Overview And New Applications In Manufacturing, Engineering, Science, And Education, Trevor Snyder, Mike Andrews, Mark M. Weislogel, Peter Moeck, Jennifer Stone-Sundberg, Derek Birkes, Madeline Paige Hoffert, Adam Lindeman, Jeff Morrill, Ondrej Fercak, Sasha Friedman, Jeff Gunderson, Anh Ha, Jack Mccollister, Yongkang Chen, John T. Geile, Andrew Paul Wollman, Babek Attari, Nathan Botnen, Vasant Vuppuluri, Jennifer Shim, Werner Kaminsky, Dustin Adams, John Graft
Physics Faculty Publications and Presentations
Since the inception of 3D printing, an evolutionary process has taken place in which specific user and customer needs have crossed paths with the capabilities of a growing number of machines to create value-added businesses. Even today, over 30 years later, the growth of 3D printing and its utilization for the good of society is often limited by the various users' understanding of the technology for their specific needs. This article presents an overview of current 3D printing technologies and shows numerous examples from a multitude of fields from manufacturing to education.
Vibrational Modes In Acoustic Gallery Scanning Probe Microscopy, Hsien-Chih Hung, Andres H. La Rosa, Rodolfo Fernandez, Bret Comnes, Richard Nordstrom
Vibrational Modes In Acoustic Gallery Scanning Probe Microscopy, Hsien-Chih Hung, Andres H. La Rosa, Rodolfo Fernandez, Bret Comnes, Richard Nordstrom
Physics Faculty Publications and Presentations
A distinct characteristic in Acoustic Gallery Scanning Probe Microscopy (AG-SPM) constitutes the use of its supporting structural frame as an acoustic resonant cavity for monitoring the nanometer-sized amplitude of its stylus-probe. Although very straightforward in its implementation, its amplitude detection sensitivity could be improved by a more thorough understanding of its working principle mechanism, as well as by a more systematic procedure to attain a closer matching between one of the cavitys acoustic resonances and the probes natural frequency. Herein, a description of the working principle of the AG-SPM is attempted from a vibrationalmode analysis perspective, and a successful specific …
Sliding Rocks On Racetrack Playa, Death Valley National Park: First Observation Of Rocks In Motion, Richard D. Norris, James M. Norris, Ralph D. Lorenz, Jib Ray, Brian Jackson
Sliding Rocks On Racetrack Playa, Death Valley National Park: First Observation Of Rocks In Motion, Richard D. Norris, James M. Norris, Ralph D. Lorenz, Jib Ray, Brian Jackson
Physics Faculty Publications and Presentations
The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved >60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 …
Optical Injection Unlocking For Cavity Ringdown Spectroscopy, Gregory A. Bostrom, Andrew L. Rice, Dean B. Atkinson
Optical Injection Unlocking For Cavity Ringdown Spectroscopy, Gregory A. Bostrom, Andrew L. Rice, Dean B. Atkinson
Physics Faculty Publications and Presentations
Continuous wave cavity ringdown spectroscopy requires a rapid termination of the injection of light into the cavity to initiate the decay (i.e., ringdown) event. We demonstrate a technique that accomplishes this through pulsed optical injection of a second laser into the main laser, resulting in 20-100 MHz frequency shifts in the otherwise cavity-locked main laser sufficient to create ringdown events at 3.5 kHz. Data on the frequency shift as a function of both main laser current and relative wavelength are presented, 88 well 88 a demonstration that single exponential decays are maintained in the process.
Radical Constructivism And Social Justice: Educational Implications, Dewey I. Dykstra Jr.
Radical Constructivism And Social Justice: Educational Implications, Dewey I. Dykstra Jr.
Physics Faculty Publications and Presentations
Upshot • Gash describes some very interesting and exemplary work using RC-influenced research and practices. I worry that his third stage of a three-stage emergence of constructivist epistemology in the study of cognitive development is consistent with a distinction between focus on individual cognitive development and focus on knowledge not in the mind but in the group, inconsistent with RC. An alternative is given and the issue of an RC perspective on social justice is discussed.
Necessary Condition For Local Quantum Operations And Classical Communication With Extensive Violation By Separable Operations, Scott M. Cohen
Necessary Condition For Local Quantum Operations And Classical Communication With Extensive Violation By Separable Operations, Scott M. Cohen
Physics Faculty Publications and Presentations
We give a conceptually simple necessary condition such that a separable quantum operation can be implemented by local operations on subsystems and classical communication between parties (LOCC), a condition which follows from a novel approach to understanding LOCC. This necessary condition applies to all LOCC protocols involving any number of parties and any finite number of rounds of communication. Furthermore, it demonstrates an extremely strong difference between separable operations and LOCC, in that there exist examples of the former for which the condition is extensively violated. More precisely, the violation by separable operations of our necessary condition for LOCC grows …
Subwavelength Visualization Of Light In Thin Film Waveguides With Photoelectrons, Joseph P. Fitzgerald, Robert Campbell Word, Rolf Könenkamp
Subwavelength Visualization Of Light In Thin Film Waveguides With Photoelectrons, Joseph P. Fitzgerald, Robert Campbell Word, Rolf Könenkamp
Physics Faculty Publications and Presentations
We report the visualization and quantitative analysis of electromagnetic surface fields at solid surfaces with the potential for λ/50 resolution. To illustrate this capability, we investigate patterns in two-photon photoemission images of light-diffracting structures in waveguiding, transparent thin films. The obtained micrographs show interference patterns between incident and guided light with a remarkable sensitivity to subwavelength features. We demonstrate that photoemission rates are directly related to the surface field strengths and develop a subwavelength method to calculate the surface fields from optical properties and surface topology based on the two-dimensional Kirchhoff diffraction integral. Calculated images based on this theoretical approach …
Cytotoxicity Of Zno Nanoparticles Can Be Tailored By Modifying Their Surface Structure: A Green Chemistry Approach For Safer Nanomaterials, Alex Punnoose, Kelsey Dodge, John W. Rasmussen, Jordan Chess, Denise Wingett, Catherine Anders
Cytotoxicity Of Zno Nanoparticles Can Be Tailored By Modifying Their Surface Structure: A Green Chemistry Approach For Safer Nanomaterials, Alex Punnoose, Kelsey Dodge, John W. Rasmussen, Jordan Chess, Denise Wingett, Catherine Anders
Physics Faculty Publications and Presentations
ZnO nanoparticles (NP) are extensively used in numerous nanotechnology applications; however, they also happen to be one of the most toxic nanomaterials. This raises significant environmental and health concerns and calls for the need to develop new synthetic approaches to produce safer ZnO NP, while preserving their attractive optical, electronic, and structural properties. In this work, we demonstrate that the cytotoxicity of ZnO NP can be tailored by modifying their surface-bound chemical groups, while maintaining the core ZnO structure and related properties. Two equally sized (9.26 ± 0.11 nm) ZnO NP samples were synthesized from the same zinc acetate precursor …
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Physics Faculty Publications and Presentations
Surface effects on the magnetization of Zn-doped SnO2 are investigated using first principles method. Magnetic behavior of Zn-doped bulk and highest and lowest energy surfaces—(001) and (110), respectively, are investigated in presence and absence of other intrinsic defects. The Zn-doped (110) and (001) surfaces of SnO2 show appreciable increase in the magnetic moment (MM) compared to Zn-doped bulk SnO2. Formation energies of Zn defects on both the surfaces are found to be lower than those in bulk SnO2. Zn doping favors the formation of oxygen vacancies. The density of states analysis on the Zn-doped …
Defect Induced Ferromagnetism In Undoped Zno Nanoparticles, K. Rainey, J. Chess, J. Eixenberger, D. A. Tenne, C. B. Hanna, A. Punnoose
Defect Induced Ferromagnetism In Undoped Zno Nanoparticles, K. Rainey, J. Chess, J. Eixenberger, D. A. Tenne, C. B. Hanna, A. Punnoose
Physics Faculty Publications and Presentations
Undoped ZnO nanoparticles (NPs) with size ∼12 nm were produced using forced hydrolysis methods using diethylene glycol (DEG) [called ZnO-I] or denatured ethanol [called ZnO-II] as the reaction solvent; both using Zn acetate dehydrate as precursor. Both samples showed weak ferromagnetic behavior at 300 K with saturation magnetization Ms = 0.077 ± 0.002 memu/g and 0.088 ± 0.013 memu/g for ZnO-I and ZnO-II samples, respectively. Fourier transform infrared(FTIR) spectra showed that ZnO-I nanocrystals had DEG fragments linked to their surface. Photoluminescence (PL) data showed a broad emission near 500 nm for ZnO-II which is absent in the ZnO-I samples, …
Dopant Spin States And Magnetism Of Sn1−XFeXO2 Nanoparticles, A. Punnoose, Kelsey Dodge, J. J. Beltrán, K. M. Reddy, Nevil Franco, Jordan Chess, Josh Eixenberger
Dopant Spin States And Magnetism Of Sn1−XFeXO2 Nanoparticles, A. Punnoose, Kelsey Dodge, J. J. Beltrán, K. M. Reddy, Nevil Franco, Jordan Chess, Josh Eixenberger
Physics Faculty Publications and Presentations
This work reports detailed investigations of a series of ∼2.6 nm sized, Sn1−xFexO2 crystallites with x = 0–0.10 using Mossbauer spectroscopy, x-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR), and magnetometry to determine the oxidation state of Fe dopants and their role in the observed magnetic properties. The magnetic moment per Fe ion μ was the largest ∼6.48 × 10−3 μB for the sample with the lowest (0.001%) Fe doping, and it showed a rapid downward trend with increasing Fe doping. Majority of the Fe ions are in 3+ oxidation state occupying octahedral …
Approximate Equations Of State In Two-Temperature Plasma Mixtures, John D. Ramshaw, Andrew W. Cook
Approximate Equations Of State In Two-Temperature Plasma Mixtures, John D. Ramshaw, Andrew W. Cook
Physics Faculty Publications and Presentations
Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials, number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest …
Surface Plasmons Of A Graphene Parallel Plate Waveguide Bounded By Kerr-Type Nonlinear Media, H. Hajian, A. Soltani-Vala, M. Kalafi, Pui T. Leung
Surface Plasmons Of A Graphene Parallel Plate Waveguide Bounded By Kerr-Type Nonlinear Media, H. Hajian, A. Soltani-Vala, M. Kalafi, Pui T. Leung
Physics Faculty Publications and Presentations
The exact dispersion relations of the transverse magnetic surface plasmons (SPs) supported by a graphene parallel plate waveguide (PPWG), surrounded on one or both sides by Kerr-type nonlinear media, are obtained analytically. It is shown that if self-focusing nonlinear materials are chosen as the surrounding media, the SPs localization length (LL) is decreased, while their propagation length (PL) remains unchanged, as compared to those of a typical graphene PPWG. Moreover, PL and LL of the SPs are considerably affected by adjusting nonlinear parts of the dielectric permittivities of the nonlinear media. It is found that using an appropriate defocusing nonlinear …
Bioelectrical Impedance Analysis As A Laboratory Activity: At The Interface Of Physics And The Body, Elliot Mylott, Ellynne Marie Kutschera, Ralf Widenhorn
Bioelectrical Impedance Analysis As A Laboratory Activity: At The Interface Of Physics And The Body, Elliot Mylott, Ellynne Marie Kutschera, Ralf Widenhorn
Physics Faculty Publications and Presentations
We present a novel laboratory activity on RC circuits aimed at introductory physics students in life-science majors. The activity teaches principles of RC circuits by connecting ac-circuit concepts to bioelectrical impedance analysis (BIA) using a custom-designed educational BIA device. The activity shows how a BIA device works and how current, voltage, and impedance measurements relate to bioelectrical characteristics of the human body. From this, useful observations can be made including body water, fat-free mass, and body fat percentage. The laboratory is engaging to pre-health and life-science students, as well as engineering students who are given the opportunity to observe electrical …
Reproducible Nanostructure Fabrication Using Atomic Force Microscopy Indentation With Minimal Tip Damage, Seunghee Jeon, Bongwoo Ryu, Wonho Jhe, Zheong G. Khim, Byung I. Kim
Reproducible Nanostructure Fabrication Using Atomic Force Microscopy Indentation With Minimal Tip Damage, Seunghee Jeon, Bongwoo Ryu, Wonho Jhe, Zheong G. Khim, Byung I. Kim
Physics Faculty Publications and Presentations
A uniform pattern of quantum dots and nanowires were reproducibly fabricated by creating holes in a two-layer structure using atomic force microscopy (AFM) indentation, dry-etching of polymer resists, and metal deposition through the indentation holes. The two-layer structure was created by depositing a thin gold layer onto a polymethyl methacrylate (PMMA) layer on a silicon substrate. The indentation depth was set so that the AFM tip penetrated the thin gold layer without the tip contacting the silicon substrate. This two-layer indentation was used to create a pattern of holes in the thin gold layer. Then, the PMMA was exposed to …
Force-Feedback High-Speed Atomic Force Microscope, Byung I. Kim, Ryan D. Boehm
Force-Feedback High-Speed Atomic Force Microscope, Byung I. Kim, Ryan D. Boehm
Physics Faculty Publications and Presentations
High-speed atomic force microscopy (HSAFM) has enabled researchers to view the nanometer-scale dynamic behavior of individual biological and bio-relevant molecules at a molecular-level resolution under physiologically relevant time scales, which is the realization of a dream in life sciences. These high-speed imaging applications now extend to the cellular/bacterial systems with the use of a smaller cantilever. By reducing the sizes of the HSAFM cantilevers by a factor of ten, systems have demonstrated image speeds up to 0.1 frames per second for larger biological systems such as bacteria. However, this imaging speed is insufficient to understand many rapid large-scale biological phenomena. …
3d Printing Of Crystallographic Models And Open Access Databases, Werner Kaminsky, Trevor J. Snyder, Peter Moeck
3d Printing Of Crystallographic Models And Open Access Databases, Werner Kaminsky, Trevor J. Snyder, Peter Moeck
Physics Faculty Publications and Presentations
Provides a brief overview of opportunities for crystallography allowed by the recent developments in 3D printing technology. in combination with open access databases.
3d Printing Of Crystallographic Models For Interdisciplinary College Education, Peter Moeck, Werner Kaminsky, Trevor J. Snyder
3d Printing Of Crystallographic Models For Interdisciplinary College Education, Peter Moeck, Werner Kaminsky, Trevor J. Snyder
Physics Faculty Publications and Presentations
Provides a brief overview of the Crystallography Open Database, and how advances in 3D printing have created opportunities in teaching of college level crystallography courses.
3d Printing & Open Access Databases For Crystallographic College Education, Peter Moeck, Jennifer Stone-Sundberg, Trevor J. Snyder, Werner Kaminsky, Saulius Grazulis, International Advisory Board Of The Crystallography Open Database
3d Printing & Open Access Databases For Crystallographic College Education, Peter Moeck, Jennifer Stone-Sundberg, Trevor J. Snyder, Werner Kaminsky, Saulius Grazulis, International Advisory Board Of The Crystallography Open Database
Physics Faculty Publications and Presentations
Presentation gives an overview of available open access databases of crystals and crystal structures, as well as discussions of how newly developed 3D printing technologies can be used to teach crystallography at the college level. Offers advice regarding conversion of crystallographic information files to 3D printing files, and shares news from the 3D printing of crystallographic models community.
On The Production Of The Positive Antihydrogen Ion H̄+ Via Radiative Attachment, Chris M. Keating, M. Charlton, Jack C. Straton
On The Production Of The Positive Antihydrogen Ion H̄+ Via Radiative Attachment, Chris M. Keating, M. Charlton, Jack C. Straton
Physics Faculty Publications and Presentations
We provide an estimate of the cross section for the radiative attachment of a second positron into the state of the ion using Ohmura and Ohmura's (1960 Phys. Rev. 118 154) effective range theory and the principle of detailed balance. The ion can potentially be created using interactions of positrons with trapped antihydrogen, and our analysis includes a discussion in which estimates of production rates are given. Motivations to produce include its potential use as an intermediary to cool antihydrogen to ultra-cold (sub-mK) temperatures for a variety of studies, including spectroscopy and probing the gravitational interaction of the anti-atom.
Advances In Crystallographic Image Processing For Scanning Probe Microscopy, Peter Moeck, Taylor T. Bilyeu, A. Mainzer Koenig, Jack C. Straton
Advances In Crystallographic Image Processing For Scanning Probe Microscopy, Peter Moeck, Taylor T. Bilyeu, A. Mainzer Koenig, Jack C. Straton
Physics Faculty Publications and Presentations
Brief overview of advances in image processing for scanning probe microscopes, as related to high resolution images of crystals and arrays of membrane proteins.
Kinesthetic Activities For The Classroom, Elliot E. Mylott, Justin C. Dunlap, Lester Lampert, Ralf Widenhorn
Kinesthetic Activities For The Classroom, Elliot E. Mylott, Justin C. Dunlap, Lester Lampert, Ralf Widenhorn
Physics Faculty Publications and Presentations
Educators have found that kinesthetic involvement in an experiment or demonstration can engage students in a powerful way. With that as our goal, we developed three activities that allow students to connect with and quantitatively explore key physics principles from mechanics with three fun physical challenges. By presenting these activities as competitions, we can challenge students to use what they know about the relevant physics to improve their performance and beat their own score or those of other students. Each activity uses an original, real-time data collecting program that offers students and educators a simple, clear method to demonstrate various …