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Articles 1 - 30 of 26428

Full-Text Articles in Physics

Effect Of Head Group Size On The Photoswitching Applications Of Azobenzene Disperse Red 1 Analogues, Chris Corkery, Alexis Goulet-Hanssens, Arri Priimagi, Christopher Barrett Dec 2103

Effect Of Head Group Size On The Photoswitching Applications Of Azobenzene Disperse Red 1 Analogues, Chris Corkery, Alexis Goulet-Hanssens, Arri Priimagi, Christopher Barrett

Chris Corkery

No abstract provided.


Recursive Non-Local Means Filter For Video Denoising, Redha A. Ali, Russell C. Hardie Dec 2017

Recursive Non-Local Means Filter For Video Denoising, Redha A. Ali, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

In this paper, we propose a computationally efficient algorithm for video denoising that exploits temporal and spatial redundancy. The proposed method is based on non-local means (NLM). NLM methods have been applied successfully in various image denoising applications. In the single-frame NLM method, each output pixel is formed as a weighted sum of the center pixels of neighboring patches, within a given search window.

The weights are based on the patch intensity vector distances. The process requires computing vector distances for all of the patches in the search window. Direct extension of this method from 2D to 3D, for video ...


Climate Change, Development, And The Global Commons, Robert J. Brecha Nov 2017

Climate Change, Development, And The Global Commons, Robert J. Brecha

The Social Practice of Human Rights: Charting the Frontiers of Research and Advocacy

An important link between energy, climate change, human development, and human rights comes in the form of a question that has yet to be answered satisfactorily: The earth’s atmosphere and other physical systems are the ultimate example of the global commons. Do future generations have a human right to an unchanged earth system? Sustainable Development Goals 13, 14, and 15 imply an affirmative answer. Given that climate scientists have a good estimate of the amount of carbon dioxide that can be emitted before the safe uptake capacity of the atmosphere is breached, how do we allocate that remaining atmospheric ...


Discrete Space-Time Model For Heat Conduction: Application To Sizedependent Thermal Conductivity In Nano-Films, Sergey Sobolev Oct 2017

Discrete Space-Time Model For Heat Conduction: Application To Sizedependent Thermal Conductivity In Nano-Films, Sergey Sobolev

Sergey Sobolev

No abstract provided.


Characterizing The Effects Of Radiation On Muscle Cells, Lori Caldwell, Elizabeth Vargis, Charles Harding, Jr Dennison Oct 2017

Characterizing The Effects Of Radiation On Muscle Cells, Lori Caldwell, Elizabeth Vargis, Charles Harding, Jr Dennison

Posters

One of the primary concerns for those spending time in low gravity and high radiation environments is muscle atrophy. A major cause of muscular atrophy is oxidative stress which is amplified by increased levels of ionizing radiation during spaceflight. Additionally, high levels of radiation can damage DNA, increasing the risk of cancer. Utah State University’s Space Environment Test Facility was used to irradiate C2C12 myoblasts and human vascular endothelial cells with a beta-radiation dosage mimicking that on the International Space Station and a 3-year deep space mission.


Electron Yield Of A Carbon-Composite Nanodielectric, Matthew Robertson, Justin Christensen, Greg Wilson, Jr Dennison Oct 2017

Electron Yield Of A Carbon-Composite Nanodielectric, Matthew Robertson, Justin Christensen, Greg Wilson, Jr Dennison

Posters

No abstract provided.


Imaging Electronic Motions By Ultrafast Electron Diraction, Hua-Chieh Shao, Anthony F. Starace Oct 2017

Imaging Electronic Motions By Ultrafast Electron Diraction, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

Recently ultrafast electron diraction and microscopy have reached unprecedented temporal resolution, and transient structures with atomic precision have been observed in various reactions. It is anticipated that these extraordinary advances will soon allow direct observation of electronic motions during chemical reactions. We therefore performed a series of theoretical investigations and simulations to investigate the imaging of electronic motions in atoms and molecules by ultrafast electron diraction. Three prototypical electronic motions were considered for hydrogen atoms. For the case of a breathing mode, the electron density expands and contracts periodically, and we show that the time-resolved scattering intensities re ect such ...


Energy-Resolved Coherent Diffraction From Laser-Driven Electronic Motion In Atoms, Hua-Chieh Shao, Anthony F. Starace Oct 2017

Energy-Resolved Coherent Diffraction From Laser-Driven Electronic Motion In Atoms, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

We investigate theoretically the use of energy-resolved ultrafast electron diffraction to image laser-driven electronic motion in atoms. A chirped laser pulse is used to transfer the valence electron of the lithium atom from the ground state to the first excited state. During this process, the electronic motion is imaged by 100-fs and 1-fs electron pulses in energy-resolved diffraction measurements. Simulations show that the angle-resolved spectra reveal the time evolution of the energy content and symmetry of the electronic state. The time-dependent diffraction patterns are further interpreted in terms of the momentum transfer. For the case of incident 1-fs electron pulses ...


Characterizing The Effects Of Radiation On Muscle Cells, Lori Caldwell, Charles Harding, Jr Dennison, Elizabeth Vargis Oct 2017

Characterizing The Effects Of Radiation On Muscle Cells, Lori Caldwell, Charles Harding, Jr Dennison, Elizabeth Vargis

Posters

As longer space missions become more desirable to public and private institutions, the physiological impact on astronauts must be considered. One of the primary concerns for those spending time in low gravity and high radiation environments is muscle atrophy. A major cause of muscular atrophy is oxidative stress which is amplified by increased levels of ionizing radiation during spaceflight. Additionally, high levels of radiation can damage DNA, increasing the risk of cancer. Utah State University’s Space Environment Test Facility was used to irradiate C2C12 myoblasts and human vascular endothelial cells with a dosage mimicking that on the International Space ...


Thermodynamics Of An Evolving Gene Sequence, Brian Clark Oct 2017

Thermodynamics Of An Evolving Gene Sequence, Brian Clark

Annual Symposium on Biomathematics and Ecology: Education and Research

No abstract provided.


The Behavior Response Of Antlion Larvae To Alternating Magnetic Fields, Lindsey Wagner, Caleb L. Adams Oct 2017

The Behavior Response Of Antlion Larvae To Alternating Magnetic Fields, Lindsey Wagner, Caleb L. Adams

Annual Symposium on Biomathematics and Ecology: Education and Research

No abstract provided.


A Critical Firing Rate In Synchronous Transitions Of Coupled Neurons, Annabelle Shaffer, Epaminondas Rosa, Rosangela Follmann Oct 2017

A Critical Firing Rate In Synchronous Transitions Of Coupled Neurons, Annabelle Shaffer, Epaminondas Rosa, Rosangela Follmann

Annual Symposium on Biomathematics and Ecology: Education and Research

No abstract provided.


Mathematical Modeling Of Inhibitory Effects On Chemically Coupled Neurons, Nathhaniel Harraman, Epaminondas Rosa Oct 2017

Mathematical Modeling Of Inhibitory Effects On Chemically Coupled Neurons, Nathhaniel Harraman, Epaminondas Rosa

Annual Symposium on Biomathematics and Ecology: Education and Research

No abstract provided.


Temperature Effects On Neuronal Tonic-To-Bursting Transitions, Manuela Burek, Epaminondas Rosa Oct 2017

Temperature Effects On Neuronal Tonic-To-Bursting Transitions, Manuela Burek, Epaminondas Rosa

Annual Symposium on Biomathematics and Ecology: Education and Research

No abstract provided.


A Brief History Of Neuroscience, Zachary Mobille, Epaminondas Rosa Oct 2017

A Brief History Of Neuroscience, Zachary Mobille, Epaminondas Rosa

Annual Symposium on Biomathematics and Ecology: Education and Research

No abstract provided.


The Production Of Phantom Partials Due To Nonlinearities In The Structural Components Of The Piano, Thomas R. Moore, Eric Rokni, Lauren Neldner, Camille Adkison Oct 2017

The Production Of Phantom Partials Due To Nonlinearities In The Structural Components Of The Piano, Thomas R. Moore, Eric Rokni, Lauren Neldner, Camille Adkison

Student-Faculty Collaborative Research Publications

Phantom partials are anomalous overtones in the spectrum of the piano sound that occur at sum and difference frequencies of the natural overtones of the string. Although they are commonly assumed to be produced by forced longitudinal waves in the string, analysis of the sound of a piano produced by mechanically vibrating the soundboard while all the strings are damped indicates that phantom partials can occur in the absence of string motion. The magnitude of the effect leads to the conclusion that nonlinearity in the non-string components may be responsible for some of the power in the phantom partials.


Electron Yield Of Challenging Materials: Low Density Polyethylene And Carbon-Composite Nanodielectrics, Matthew Robertson, Jordan Lee, Jr Dennison Oct 2017

Electron Yield Of Challenging Materials: Low Density Polyethylene And Carbon-Composite Nanodielectrics, Matthew Robertson, Jordan Lee, Jr Dennison

Presentations

The electron yield—the ratio of the number of emitted electrons to incident electrons—is a key material property that characterizes how materials will charge due to exposure to electron fluxes. The USU Materials Physics Group has developed expertise in measuring this for a wide array of conductors, semiconductors and insulators, including many challenging materials. The basic definitions associated with electron yield and how they are measured will be discussed. We will highlight many critical applications investigated at USU, particularly those associated with spacecraft charging as materials interact with space plasma environments. Electron irradiation experiments conducted to investigate the electron ...


A Mathematical Analysis Of Drug Dissolution In The Usp Flow Through Apparatus, David Mcdonnell, Deirdre M. D'Arcy, Lawrence J. Crane, Brendan Redmond Oct 2017

A Mathematical Analysis Of Drug Dissolution In The Usp Flow Through Apparatus, David Mcdonnell, Deirdre M. D'Arcy, Lawrence J. Crane, Brendan Redmond

Articles

This paper applies boundary layer theory to the process of drug dissolution in the USP (United States Pharmacopeia) Flow Through Apparatus. The mass transfer rate from the vertical planar surface of a compact within the device is examined. The theoretical results obtained are then compared with those of experiment. The paper also examines the effect on the dissolution process caused by the interaction between natural and forced convection within the apparatus and the introduction of additional boundaries.


Effective One-Dimensional Coupling In The Highly Frustrated Square-Lattice Itinerant Magnet Caco 2 − Y As 2, Aashish Sapkota, B. G. Ueland, V. K. Anand, N. S. Sangeetha, D. L. Abernathy, M. B. Stone, J. L. Niedziela, D. C. Johnston, A. Kreyssig, A. I. Goldman, R. J. Mcqueeney Oct 2017

Effective One-Dimensional Coupling In The Highly Frustrated Square-Lattice Itinerant Magnet Caco 2 − Y As 2, Aashish Sapkota, B. G. Ueland, V. K. Anand, N. S. Sangeetha, D. L. Abernathy, M. B. Stone, J. L. Niedziela, D. C. Johnston, A. Kreyssig, A. I. Goldman, R. J. Mcqueeney

Ames Laboratory Accepted Manuscripts

Inelastic neutron scattering measurements on the itinerant antiferromagnet CaCo2−yAs2 at a temperature of 8 K reveal two orthogonal planes of scattering perpendicular to the Co square lattice in reciprocal space, demonstrating the presence of effective one-dimensional spin interactions. These results are shown to arise from near-perfect bond frustration within the J1-J2 Heisenberg model on a square lattice with ferromagnetic J1 and hence indicate that the extensive previous experimental and theoretical study of the J1-J2 Heisenberg model on local-moment square spin lattices should be expanded to include itinerant spin systems.


Pressure Induced Half-Collapsed-Tetragonal Phase In Cakfe4as4, Udhara Kaluarachchi, Valentin Taufour, Aashish Sapkota, Vladislav Borisov, Tai Kong, W. R. Meier, Karunakar Kothapalli, Benjamin G. Ueland, Andreas Kreyssig, Roser Valenti, Robert J. Mcqueeney, Alan I. Goldman, Sergey L. Bud'ko, Paul C. Canfield Oct 2017

Pressure Induced Half-Collapsed-Tetragonal Phase In Cakfe4as4, Udhara Kaluarachchi, Valentin Taufour, Aashish Sapkota, Vladislav Borisov, Tai Kong, W. R. Meier, Karunakar Kothapalli, Benjamin G. Ueland, Andreas Kreyssig, Roser Valenti, Robert J. Mcqueeney, Alan I. Goldman, Sergey L. Bud'ko, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

We report the temperature-pressure phase diagram of CaKFe4As4 established using high-pressure electrical resistivity, magnetization, and high-energy x-ray diffraction measurements up to 6 GPa. With increasing pressure, both resistivity and magnetization data show that the bulk superconducting transition of CaKFe4As4 is suppressed and then disappears at p≳4 GPa. High-pressure x-ray data clearly indicate a phase transition to a collapsed tetragonal phase in CaKFe4As4 under pressure that coincides with the abrupt loss of bulk superconductivity near 4 GPa. The x-ray data, combined with resistivity data, indicate that the collapsed tetragonal transition line is essentially independent of pressure, occurring at 4.0 ...


An Enhanced Operational Definition Of Dielectric Breakdown For Dc Voltage Step-Up Tests, Allen Andersen, Jr Dennison Oct 2017

An Enhanced Operational Definition Of Dielectric Breakdown For Dc Voltage Step-Up Tests, Allen Andersen, Jr Dennison

Journal Articles

The imprecise definition of breakdown in the ASTM D3755-14 standard can misidentify breakdown. If the recommended test circuit current sensing element threshold is set too high, breakdown may occur undetected. Conversely, false positives may result from designating a low current threshold. An operational definition of breakdown much less sensitive to these pitfalls is outlined herein. This enhanced definition of breakdown is based on the average rate of change of the leakage current with increasing voltage, rather than a simple current threshold, avoiding ambiguous association with anomalies in current traces. For tests that continuously monitor leakage current, breakdown can be detected ...


Highly Accelerated Test Method For Characterizing Likelihood Of Breakdown In Hvdc Dielectric Materials, Allen Andersen, Jr Dennison Oct 2017

Highly Accelerated Test Method For Characterizing Likelihood Of Breakdown In Hvdc Dielectric Materials, Allen Andersen, Jr Dennison

Journal Articles

Increasing application and development of HVDC technologies emphasizes the need for improved characterization of candidate insulating materials. Accurately predicting the lifetime to breakdown of dielectric materials by means of accelerated voltage step-up to breakdown tests can be prohibitively time consuming. Step-up to breakdown tests with sufficiently slow voltage ramp rates that continuously monitor leakage current have detected a distribution of DC partial discharge (DCPD) events occurring prior to breakdown, which increase with increasing field. These DCPD distributions are shown to correlate strongly with the likelihood of breakdown for four common polymers. Given that hundreds of DCPD events are typically observed ...


Detecting Majorana Fermion Induced Crossed Andreev Reflection, Lei Fang Sep 2017

Detecting Majorana Fermion Induced Crossed Andreev Reflection, Lei Fang

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

This dissertation is devoted to a study of detecting the Majorana fermion induced crossed Andreev reflection.

Majorana fermions are particles that constitute their own antiparticles. In condensed matter physics, Majorana fermions are zero energy modes that reside at edges or around vortices of topological superconductors. The special properties of Majorana fermions result in their potential to conduct topological quantum computation, which has been attracting a lot of current research. One of the most important issues in the field of the Majorana fermion physics now is to detect their existence in realistic systems. Among many classes of detecting methods, a transport ...


Structural And Functional Analysis Of The Transcriptional Regulator Rv3066 Of Mycobacterium Tuberculosis, Jani Reddy Bolla, Sylvia V. Do, Feng Long, Lei Dai, Chih-Chia Su, Hsiang-Ting Lei, Xiao Chen, Jillian E. Gerkey, Daniel C. Murphy, Kanagalaghatta R. Rajashankar, Qijing Zhang, Edward W. Yu Sep 2017

Structural And Functional Analysis Of The Transcriptional Regulator Rv3066 Of Mycobacterium Tuberculosis, Jani Reddy Bolla, Sylvia V. Do, Feng Long, Lei Dai, Chih-Chia Su, Hsiang-Ting Lei, Xiao Chen, Jillian E. Gerkey, Daniel C. Murphy, Kanagalaghatta R. Rajashankar, Qijing Zhang, Edward W. Yu

Qijing Zhang

The Mmr multidrug efflux pump recognizes and actively extrudes a broad range of antimicrobial agents, and promotes the intrinsic resistance to these antimicrobials in Mycobacterium tuberculosis . The expression of Mmr is controlled by the TetR-like transcriptional regulator Rv3066, whose open reading frame is located downstream of the mmr operon. To understand the structural basis of Rv3066 regulation, we have determined the crystal structures of Rv3066, both in the absence and presence of bound ethidium, revealing an asymmetric homodimeric two-domain molecule with an entirely helical architecture. The structures underscore the flexibility and plasticity of the regulator essential for multidrug recognition. Comparison ...


Aligning Technology, Policy And Culture To Enhance Nuclear Security: A Comparative Analysis Of Nigeria And The U.S., Stephen Olumuyiwa Ariyo Dahunsi, John D. Auxier Ii, Joseph Ruric Stainback Iv, Howard Lewis Hall Sep 2017

Aligning Technology, Policy And Culture To Enhance Nuclear Security: A Comparative Analysis Of Nigeria And The U.S., Stephen Olumuyiwa Ariyo Dahunsi, John D. Auxier Ii, Joseph Ruric Stainback Iv, Howard Lewis Hall

International Journal of Nuclear Security

Around the world, current energy and climate change concerns have led to more nations adopting nuclear technology as an option for electricity generation. However, one of the challenges to the peaceful application of this technology is the possibility that it will be misused, or that terrorists with global reach may acquire nuclear materials. Nigeria is one country that has embraced the technology to solve its energy challenges, but the country is now faced with an upsurge in terrorism and uprisings staged by various ethnic groups. In addition, corruption is continually becoming a hindrance to national development. These challenges are critical ...


Cubesat Space Environments Effects Studied In The Space Survivability Test Chamber, Alexander Souvall, Gregory Wilson, Ben Russon, Katie Gamaunt, Jr Dennison Sep 2017

Cubesat Space Environments Effects Studied In The Space Survivability Test Chamber, Alexander Souvall, Gregory Wilson, Ben Russon, Katie Gamaunt, Jr Dennison

Posters

No abstract provided.


Modification Of The G-Phonon Mode Of Graphene By Nitrogen Doping, Pavel V. Lukashev, Liuyan Zhao, Tula R. Paudel, Theanne Schiros, Noah Hurley, Evgeny Y. Tsymbal, Aron Pinczuk, Abhay Pasupathy, Rui He Sep 2017

Modification Of The G-Phonon Mode Of Graphene By Nitrogen Doping, Pavel V. Lukashev, Liuyan Zhao, Tula R. Paudel, Theanne Schiros, Noah Hurley, Evgeny Y. Tsymbal, Aron Pinczuk, Abhay Pasupathy, Rui He

Pavel Lukashev

The effect of nitrogen doping on the phonon spectra of graphene is analyzed. In particular, we employ first-principles calculations and scanning Raman analysis to investigate the dependence of phonon frequencies in graphene on the concentration of nitrogen dopants. We demonstrate that the G phonon frequency shows oscillatory behavior as a function of nitrogen concentration. We analyze different mechanisms which could potentially be responsible for this behavior, such as Friedel charge oscillations around the localized nitrogen impurity atom, the bond length change between nitrogen impurity and its nearest neighbor carbon atoms, and the long-range interactions of the nitrogen point defects. We ...


Simple, Complete, And Novel Quantitative Model Of Holography For Students Of Science And Science Education, Dale Olson Sep 2017

Simple, Complete, And Novel Quantitative Model Of Holography For Students Of Science And Science Education, Dale Olson

Dale W. Olson

A Moiré graphical method for predicting the directions of all permitted image waves for thin and volume holograms is described. This method has been developed in connection with a holography centred optics course for students in science, technology and science education that has evolved over several decades. A somewhat unique view of the holographic process underlies this novel method of predicting the behaviour of diffraction gratings.


Modification Of The G-Phonon Mode Of Graphene By Nitrogen Doping, Pavel V. Lukashev, Liuyan Zhao, Tula R. Paudel, Theanne Schiros, Noah Hurley, Evgeny Y. Tsymbal, Aron Pinczuk, Abhay Pasupathy, Rui He Sep 2017

Modification Of The G-Phonon Mode Of Graphene By Nitrogen Doping, Pavel V. Lukashev, Liuyan Zhao, Tula R. Paudel, Theanne Schiros, Noah Hurley, Evgeny Y. Tsymbal, Aron Pinczuk, Abhay Pasupathy, Rui He

Rui He

The effect of nitrogen doping on the phonon spectra of graphene is analyzed. In particular, we employ first-principles calculations and scanning Raman analysis to investigate the dependence of phonon frequencies in graphene on the concentration of nitrogen dopants. We demonstrate that the G phonon frequency shows oscillatory behavior as a function of nitrogen concentration. We analyze different mechanisms which could potentially be responsible for this behavior, such as Friedel charge oscillations around the localized nitrogen impurity atom, the bond length change between nitrogen impurity and its nearest neighbor carbon atoms, and the long-range interactions of the nitrogen point defects. We ...


Modification Of The G-Phonon Mode Of Graphene By Nitrogen Doping, Pavel V. Lukashev, Liuyan Zhao, Tula R. Paudel, Theanne Schiros, Noah Hurley, Evgeny Y. Tsymbal, Aron Pinczuk, Abhay Pasupathy, Rui He Sep 2017

Modification Of The G-Phonon Mode Of Graphene By Nitrogen Doping, Pavel V. Lukashev, Liuyan Zhao, Tula R. Paudel, Theanne Schiros, Noah Hurley, Evgeny Y. Tsymbal, Aron Pinczuk, Abhay Pasupathy, Rui He

Rui He

The effect of nitrogen doping on the phonon spectra of graphene is analyzed. In particular, we employ first-principles calculations and scanning Raman analysis to investigate the dependence of phonon frequencies in graphene on the concentration of nitrogen dopants. We demonstrate that the G phonon frequency shows oscillatory behavior as a function of nitrogen concentration. We analyze different mechanisms which could potentially be responsible for this behavior, such as Friedel charge oscillations around the localized nitrogen impurity atom, the bond length change between nitrogen impurity and its nearest neighbor carbon atoms, and the long-range interactions of the nitrogen point defects. We ...