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Full-Text Articles in Physical Sciences and Mathematics

Author Correction: Femtosecond Laser Mass Spectrometry And High Harmonic Spectroscopy Of Xylene Isomers (Scientific Reports (2018) Doi: 10.1038/S41598-018-22055-9), Abdullah Alharbi, Andrewy E. Boguslavskiy, Dane Austin, Nicolas Thire, D. Wood, P. Hawkins, Felicity Mcgrath, A. S. Johnson, I. Lopez-Quintas, Bruno Schmidt, Francois Legare, J. P. Marangos, Anh-Thu Le, Ravi Bhardwaj Dec 2018

Author Correction: Femtosecond Laser Mass Spectrometry And High Harmonic Spectroscopy Of Xylene Isomers (Scientific Reports (2018) Doi: 10.1038/S41598-018-22055-9), Abdullah Alharbi, Andrewy E. Boguslavskiy, Dane Austin, Nicolas Thire, D. Wood, P. Hawkins, Felicity Mcgrath, A. S. Johnson, I. Lopez-Quintas, Bruno Schmidt, Francois Legare, J. P. Marangos, Anh-Thu Le, Ravi Bhardwaj

Physics Faculty Research & Creative Works

The original version of this Article contained a typographical error in the spelling of the author Nicolas Thiré, which was incorrectly given as Nicholas Thiré. Nicolas Thiré was also incorrectly affiliated with 'Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 119, 28006, Madrid, Spain'. The correct affiliation is listed below.

INRS-EMT, Advanced Laser Light Source, 1650 Lionel-Boulet Bvd, Varennes, J3X1S2, Canada.

This has now been corrected in the PDF and HTML versions of the Article and in the accompanying Supplementary Information file.


The Rotational Spectrum And Potential Energy Surface Of The Ar-Sio Complex, Michael C. Mccarthy, Steve Alexandre Ndengue, Richard Dawes Oct 2018

The Rotational Spectrum And Potential Energy Surface Of The Ar-Sio Complex, Michael C. Mccarthy, Steve Alexandre Ndengue, Richard Dawes

Chemistry Faculty Research & Creative Works

The rotational spectra of five isotopic species of the Ar-SiO complex have been observed at high-spectral resolution between 8 and 18 GHz using chirped Fourier transform microwave spectroscopy and a discharge nozzle source; follow-up cavity measurements have extended these measurements to as high as 35 GHz. The spectrum of the normal species is dominated by an intense progression of a-type rotational transitions arising from increasing quanta in the Si-O stretch, in which lines up to v = 12 (~14 500 cm-1) were identified. A structural determination by isotopic substitution and a hyperfine analysis of the Ar-Si17O spectrum both ...


Real-Time Observation Of Molecular Spinning With Angular High-Harmonic Spectroscopy, Lixin He, Pengfei Lan, Anh-Thu Le, Baoning Wang, Bincheng Wang, Xiaosong Zhu, Peixiang Lu, C. D. Lin Oct 2018

Real-Time Observation Of Molecular Spinning With Angular High-Harmonic Spectroscopy, Lixin He, Pengfei Lan, Anh-Thu Le, Baoning Wang, Bincheng Wang, Xiaosong Zhu, Peixiang Lu, C. D. Lin

Physics Faculty Research & Creative Works

We demonstrate an angular high-harmonic spectroscopy method to probe the spinning dynamics of a molecular rotation wave packet in real time. With the excitation of two time-delayed, polarization-skewed pump pulses, the molecular ensemble is impulsively kicked to rotate unidirectionally, which is subsequently irradiated by another delayed probe pulse for high-order harmonic generation (HHG). The spatiotemporal evolution of the molecular rotation wave packet is visualized from the time-dependent angular distributions of the HHG yields and frequency shift measured at various polarization directions and time delays of the probe pulse. The observed frequency shift in HHG is demonstrated to arise from the ...


Polymer Coated Gold-Ferric Oxide Superparamagnetic Nanoparticles For Theranostic Applications, Muhammad Raisul Abedin, Siddesh Umapathi, Harika Mahendrakar, Tunyaboon Laemthong, Holly Coleman, Denise Muchangi, Santimukul Santra, Manashi Nath, Sutapa Barua Oct 2018

Polymer Coated Gold-Ferric Oxide Superparamagnetic Nanoparticles For Theranostic Applications, Muhammad Raisul Abedin, Siddesh Umapathi, Harika Mahendrakar, Tunyaboon Laemthong, Holly Coleman, Denise Muchangi, Santimukul Santra, Manashi Nath, Sutapa Barua

Chemistry Faculty Research & Creative Works

Background: Engineered inorganic nanoparticles (NPs) are essential components in the development of nanotechnologies. For applications in nanomedicine, particles need to be functionalized to ensure a good dispersibility in biological fluids. In many cases however, functionalization is not sufficient: the particles become either coated by a corona of serum proteins or precipitate out of the solvent. We show that by changing the coating of magnetic iron oxide NPs using poly-l-lysine (PLL) polymer the colloidal stability of the dispersion is improved in aqueous solutions including water, phosphate buffered saline (PBS), PBS with 10% fetal bovine serum (FBS) and cell culture medium, and ...


Explosive Dust Test Vessel Comparison Using Pulverized Pittsburgh Coal, Jacob Miller, Jay Schafler, Phillip R. Mulligan, Robert Eades, Kyle A. Perry, Catherine E. Johnson Oct 2018

Explosive Dust Test Vessel Comparison Using Pulverized Pittsburgh Coal, Jacob Miller, Jay Schafler, Phillip R. Mulligan, Robert Eades, Kyle A. Perry, Catherine E. Johnson

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Explosions of coal dust are a major safety concern within the coal mining industry. The explosion and subsequent fires caused by coal dust can result in significant property damage, loss of life in underground coal mines and damage to coal processing facilities. The United States Bureau of Mines conducted research on coal dust explosions until 1996 when it was dissolved. In the following years, the American Society for Testing and Materials (ASTM) developed a test standard, ASTM E1226, to provide a standard test method characterizing the “explosibility” of particulate solids of combustible materials suspended in air. The research presented herein ...


Gravitational Effects In G -Factor Measurements And High-Precision Spectroscopy: Limits Of Einstein's Equivalence Principle, Ulrich D. Jentschura Sep 2018

Gravitational Effects In G -Factor Measurements And High-Precision Spectroscopy: Limits Of Einstein's Equivalence Principle, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

We study the interplay of general relativity, the equivalence principle, and high-precision experiments involving atomic transitions and g-factor measurements. In particular, we derive a generalized Dirac Hamiltonian, which describes both the gravitational coupling for weak fields and the electromagnetic coupling, e.g., to a central Coulomb field. An approximate form of this Hamiltonian is used to derive the leading gravitational corrections to transition frequencies and g factors. The position dependence of atomic transitions is shown to be compatible with the equivalence principle, up to a very good approximation. The compatibility of g-factor measurements requires a deeper subtle analysis in order ...


Electronic Fingerprints Of Cr And V Dopants In The Topological Insulator Sb₂Te₃, Wenhan Zhang, Damien West, Seng Huat Lee, Yunsheng Qiu, Cui-Zu Chang, Jagadeesh S. Moodera, Yew San Hor, Shengbai Zhang, Weida Wu Sep 2018

Electronic Fingerprints Of Cr And V Dopants In The Topological Insulator Sb₂Te₃, Wenhan Zhang, Damien West, Seng Huat Lee, Yunsheng Qiu, Cui-Zu Chang, Jagadeesh S. Moodera, Yew San Hor, Shengbai Zhang, Weida Wu

Physics Faculty Research & Creative Works

By combining scanning tunneling microscopy/spectroscopy and first-principles calculations, we systematically study the local electronic states of magnetic dopants V and Cr in the topological insulator (TI) Sb2Te3. Spectroscopic imaging shows diverse local defect states between Cr and V, which agree with our first-principle calculations. The unique spectroscopic features of V and Cr dopants provide electronic fingerprints for the codoped magnetic TI samples with the enhanced quantum anomalous Hall effect. Our results also facilitate the exploration of the underlying mechanism of the enhanced quantum anomalous Hall temperature in Cr/V codoped TIs.


Scanning Tunneling Spectroscopy Investigations Of Superconducting-Doped Topological Insulators: Experimental Pitfalls And Results, Stefan Wilfert, Paolo Sessi, Zhiwei Wang, Henrik Schmidt, M. Carmen Martínez-Velarte, Seng Huat Lee, Yew San Hor, Alexander F. Otte, Yoichi Ando, Weida Wu, Matthias Bode Aug 2018

Scanning Tunneling Spectroscopy Investigations Of Superconducting-Doped Topological Insulators: Experimental Pitfalls And Results, Stefan Wilfert, Paolo Sessi, Zhiwei Wang, Henrik Schmidt, M. Carmen Martínez-Velarte, Seng Huat Lee, Yew San Hor, Alexander F. Otte, Yoichi Ando, Weida Wu, Matthias Bode

Physics Faculty Research & Creative Works

Recently, the doping of topological insulators has attracted significant interest as a potential route towards topological superconductivity. Because many experimental techniques lack sufficient surface sensitivity, however, definite proof of the coexistence of topological surface states and surface superconductivity is still outstanding. Here we report on highly surface sensitive scanning tunneling microscopy and spectroscopy experiments performed on Tl-doped Bi2Te3, a three-dimensional topological insulator which becomes superconducting in the bulk at TC=2.3 K. Landau level spectroscopy as well as quasiparticle interference mapping clearly demonstrated the presence of a topological surface state with a Dirac point energy ...


Extinction Transitions In Correlated External Noise, Alexander H. O. Wada, Matthew Small, Thomas Vojta Aug 2018

Extinction Transitions In Correlated External Noise, Alexander H. O. Wada, Matthew Small, Thomas Vojta

Physics Faculty Research & Creative Works

We analyze the influence of long-range correlated (colored) external noise on extinction phase transitions in growth and spreading processes. Uncorrelated environmental noise (i.e., temporal disorder) was recently shown to give rise to an unusual infinite-noise critical point [Europhys. Lett. 112, 30002 (2015)EULEEJ0295-507510.1209/0295-5075/112/30002]. It is characterized by enormous density fluctuations that increase without limit at criticality. As a result, a typical population decays much faster than the ensemble average, which is dominated by rare events. Using the logistic evolution equation as an example, we show here that positively correlated (red) environmental noise further enhances these ...


Quantum Critical Behavior Of A Three-Dimensional Superfluid-Mott Glass Transition, Jack Crewse, Cameron Lerch, Thomas Vojta Aug 2018

Quantum Critical Behavior Of A Three-Dimensional Superfluid-Mott Glass Transition, Jack Crewse, Cameron Lerch, Thomas Vojta

Physics Faculty Research & Creative Works

The superfluid to insulator quantum phase transition of a three-dimensional particle-hole symmetric system of disordered bosons is studied. To this end, a site-diluted quantum rotor Hamiltonian is mapped onto a classical (3+1)-dimensional XY model with columnar disorder and analyzed by means of large-scale Monte Carlo simulations. The superfluid-Mott insulator transition of the clean, undiluted system is in the four-dimensional XY universality class and shows mean-field critical behavior with logarithmic corrections. The clean correlation length exponent ν=1/2 violates the Harris criterion, indicating that disorder must be a relevant perturbation. For nonzero dilutions below the lattice percolation threshold ...


Dynamics Of Paramagnetic And Ferromagnetic Ellipsoidal Particles In Shear Flow Under A Uniform Magnetic Field, Christopher A. Sobecki, Jie Zhang, Yanzhi Zhang, Cheng Wang Aug 2018

Dynamics Of Paramagnetic And Ferromagnetic Ellipsoidal Particles In Shear Flow Under A Uniform Magnetic Field, Christopher A. Sobecki, Jie Zhang, Yanzhi Zhang, Cheng Wang

Mathematics and Statistics Faculty Research & Creative Works

We investigate the two-dimensional dynamic motion of magnetic particles of ellipsoidal shapes in shear flow under the influence of a uniform magnetic field. In the first part, we present a theoretical analysis of the rotational dynamics of the particles in simple shear flow. By considering paramagnetic and ferromagnetic particles, we study the effects of the direction and strength of the magnetic field on the particle rotation. The critical magnetic-field strength, at which particle rotation is impeded, is determined. In a weak-field regime (i.e., below the critical strength) where the particles execute complete rotations, the symmetry property of the rotational ...


Tuning A Random-Field Mechanism In A Frustrated Magnet, Shashikant Singh Kunwar, Arnab Sen, Thomas Vojta, Rajesh Narayanan Jul 2018

Tuning A Random-Field Mechanism In A Frustrated Magnet, Shashikant Singh Kunwar, Arnab Sen, Thomas Vojta, Rajesh Narayanan

Physics Faculty Research & Creative Works

We study the influence of spinless impurities on a frustrated magnet featuring a spin-density wave (stripe) phase by means of Monte Carlo simulations. We demonstrate that the interplay between the impurities and an order parameter that breaks a real-space symmetry triggers the emergence of a random-field mechanism which destroys the stripe-ordered phase. Importantly, the strength of the emerging random fields can be tuned by the repulsion between the impurity atoms; they vanish for perfect anticorrelations between neighboring impurities. This provides a way of controlling the phase diagram of a many-particle system. In addition, we also investigate the effects of the ...


Automated Design Of Network Security Metrics, Aaron Scott Pope, Daniel R. Tauritz, Robert Morning, Alexander D. Kent Jul 2018

Automated Design Of Network Security Metrics, Aaron Scott Pope, Daniel R. Tauritz, Robert Morning, Alexander D. Kent

Computer Science Faculty Research & Creative Works

Many abstract security measurements are based on characteristics of a graph that represents the network. These are typically simple and quick to compute but are often of little practical use in making real-world predictions. Practical network security is often measured using simulation or real-world exercises. These approaches better represent realistic outcomes but can be costly and time-consuming. This work aims to combine the strengths of these two approaches, developing efficient heuristics that accurately predict attack success. Hyper-heuristic machine learning techniques, trained on network attack simulation training data, are used to produce novel graph-based security metrics. These low-cost metrics serve as ...


Evolution Of Network Enumeration Strategies In Emulated Computer Networks, Sean Harris, Eric Michalak, Kevin Schoonover, Adam Gausmann, Hannah Reinbolt, Joshua Herman, Daniel R. Tauritz, Chris Rawlings, Aaron Scott Pope Jul 2018

Evolution Of Network Enumeration Strategies In Emulated Computer Networks, Sean Harris, Eric Michalak, Kevin Schoonover, Adam Gausmann, Hannah Reinbolt, Joshua Herman, Daniel R. Tauritz, Chris Rawlings, Aaron Scott Pope

Computer Science Faculty Research & Creative Works

Successful attacks on computer networks today do not often owe their victory to directly overcoming strong security measures set up by the defender. Rather, most attacks succeed because the number of possible vulnerabilities are too large for humans to fully protect without making a mistake. Regardless of the security elsewhere, a skilled attacker can exploit a single vulnerability in a defensive system and negate the benefits of those security measures. This paper presents an evolutionary framework for evolving attacker agents in a real, emulated network environment using genetic programming, as a foundation for coevolutionary systems which can automatically discover and ...


The Automated Design Of Probabilistic Selection Methods For Evolutionary Algorithms, Samuel N. Richter, Daniel R. Tauritz Jul 2018

The Automated Design Of Probabilistic Selection Methods For Evolutionary Algorithms, Samuel N. Richter, Daniel R. Tauritz

Computer Science Faculty Research & Creative Works

Selection functions enable Evolutionary Algorithms (EAs) to apply selection pressure to a population of individuals, by regulating the probability that an individual's genes survive, typically based on fitness. Various conventional fitness based selection methods exist, each providing a unique relationship between the fitnesses of individuals in a population and their chances of selection. However, the full space of selection algorithms is only limited by max algorithm size, and each possible selection algorithm is optimal for some EA configuration applied to a particular problem class. Therefore, improved performance may be expected by tuning an EA's selection algorithm to the ...


Dynamic Effects In Electron Momentum Spectroscopy Of Sulfur Hexafluoride, Xing Wang, Shenyue Xu, Chuangang Ning, O. Al-Hagan, Pengfei Hu, Yongtao Zhao, Zhongfen Xu, Jingkang Deng, Enliang Wang, Xueguang Ren, Alexander Dorn, Don H. Madison Jun 2018

Dynamic Effects In Electron Momentum Spectroscopy Of Sulfur Hexafluoride, Xing Wang, Shenyue Xu, Chuangang Ning, O. Al-Hagan, Pengfei Hu, Yongtao Zhao, Zhongfen Xu, Jingkang Deng, Enliang Wang, Xueguang Ren, Alexander Dorn, Don H. Madison

Physics Faculty Research & Creative Works

Electron momentum spectroscopy (EMS) results are presented for the sulfur hexafluoride (SF6) molecule using a high-resolution binary (e, 2e) spectrometer at incident energies (Ei) of 600, 1200, and 2400 eV plus the binding energy. The valence orbital momentum profiles were measured with a binding energy resolution of 0.68 eV and angular resolutions of Δθ = ±0.6⁰, ΔΦ = ±0.85⁰. Whereas the two higher incident energies are in the range where normally EMS measurements do not exhibit an impact-energy dependence, the current experimental data display a dynamic dependence on the impact energies. The measured momentum profiles are compared with predictions ...


Relativistic And Radiative Corrections To The Dynamic Stark Shift: Gauge Invariance And Transition Currents In The Velocity Gauge, Ulrich D. Jentschura, Chandra M. Adhikari Jun 2018

Relativistic And Radiative Corrections To The Dynamic Stark Shift: Gauge Invariance And Transition Currents In The Velocity Gauge, Ulrich D. Jentschura, Chandra M. Adhikari

Physics Faculty Research & Creative Works

We investigate the gauge invariance of the dynamic (ac) Stark shift under "hybrid" gauge transformations from the "length" (E·r ) to the "velocity" (A-·p ) gauge. By a "hybrid" gauge transformation, we understand a transformation in which the scalar and vector potentials are modified, but the wave function remains unaltered. The gauge invariance of the leading term is well known, while we here show that gauge invariance under perturbations holds only if one takes into account an additional correction to the transition current, which persists only in the velocity gauge. We find a general expression for this current, and apply ...


Scalable, Hydrophobic And Highly-Stretchable Poly(Isocyanurate-Urethane) Aerogels, Sadeq Malakooti, Saman Rostami, Habel Gitogo Churu, Huiyang Luo, Jenna Clark, Fabiola Casarez, Owen Rettenmaier, Soheil Daryadel, Majid Minary-Jolandan, Lia Sotiriou-Leventis, Nicholas Leventis, Hongbing Lu Jun 2018

Scalable, Hydrophobic And Highly-Stretchable Poly(Isocyanurate-Urethane) Aerogels, Sadeq Malakooti, Saman Rostami, Habel Gitogo Churu, Huiyang Luo, Jenna Clark, Fabiola Casarez, Owen Rettenmaier, Soheil Daryadel, Majid Minary-Jolandan, Lia Sotiriou-Leventis, Nicholas Leventis, Hongbing Lu

Chemistry Faculty Research & Creative Works

Scalable, low-density and flexible aerogels offer a unique combination of excellent mechanical properties and scalable manufacturability. Herein, we report the fabrication of a family of low-density, ambient-dried and hydrophobic poly(isocyanurate-urethane) aerogels derived from a triisocyanate precursor. The bulk densities ranged from 0.28 to 0.37 g cm-3 with porosities above 70% v/v. The aerogels exhibit a highly stretchable behavior with a rapid increase in the Young's modulus with bulk density (slope of log-log plot > 6.0). In addition, the aerogels are very compressible (more than 80% compressive strain) with high shape recovery rate (more than ...


Worker Activity Recognition In Smart Manufacturing Using Imu And Semg Signals With Convolutional Neural Networks, Wenjin Tao, Ze-Hao Lai, Ming-Chuan Leu, Zhaozheng Yin Jun 2018

Worker Activity Recognition In Smart Manufacturing Using Imu And Semg Signals With Convolutional Neural Networks, Wenjin Tao, Ze-Hao Lai, Ming-Chuan Leu, Zhaozheng Yin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In a smart manufacturing system involving workers, recognition of the worker's activity can be used for quantification and evaluation of the worker's performance, as well as to provide onsite instructions with augmented reality. In this paper, we propose a method for activity recognition using Inertial Measurement Unit (IMU) and surface electromyography (sEMG) signals obtained from a Myo armband. The raw 10-channel IMU signals are stacked to form a signal image. This image is transformed into an activity image by applying Discrete Fourier Transformation (DFT) and then fed into a Convolutional Neural Network (CNN) for feature extraction, resulting in ...


Overpumping Leads To California Groundwater Arsenic Threat, Ryan G. Smith, Rosemary Knight, Scott Fendorf Jun 2018

Overpumping Leads To California Groundwater Arsenic Threat, Ryan G. Smith, Rosemary Knight, Scott Fendorf

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Water resources are being challenged to meet domestic, agricultural, and industrial needs. To complement finite surface water supplies that are being stressed by changes in precipitation and increased demand, groundwater is increasingly being used. Sustaining groundwater use requires considering both water quantity and quality. A unique challenge for groundwater use, as compared with surface water, is the presence of naturally occurring contaminants within aquifer sediments, which can enter the water supply. Here we find that recent groundwater pumping, observed through land subsidence, results in an increase in aquifer arsenic concentrations in the San Joaquin Valley of California. By comparison, historic ...


The Future Possibility Of Consumer-Grade Quantum Computers, Peter Dolan May 2018

The Future Possibility Of Consumer-Grade Quantum Computers, Peter Dolan

Missouri S&T’s Peer to Peer

Quantum computers are rapidly evolving and are on the edge of becoming useful for the first time. The theoretical limit of computational speed for quantum computers would put even small-scale quantum computers well ahead of any classical computer. With more researchers attempting to build their own, it has become a race to see who can create the first truly useful quantum computer. Once such computers become both useful and prevalent, massive advancements in many fields of science can be achieved, leading to a scientific revolution. Advances in quantum computing lead some researchers and consumers to question whether the technology can ...


The Viability Of Quantum Computing, Brennan Michael King May 2018

The Viability Of Quantum Computing, Brennan Michael King

Missouri S&T’s Peer to Peer

Quantum computing is an upcoming computational technology that could be the key to advancing the field and ushering in a new era of innovation. In this paper examines the viability of quantum computing extensively using only highly credible peer-reviewed articles from the last few years. These peer-reviewed articles will provide relevant facts and data from prominent researchers in the field of computer engineering. A growing problem in the field of electronics and computers is the concept of Moore’s law. Moore’s law refers to the doubling of transistors every two years in integrated circuits. Recent research has suggested that ...


The Dangers Of Human-Like Bias In Machine-Learning Algorithms, Daniel James Fuchs May 2018

The Dangers Of Human-Like Bias In Machine-Learning Algorithms, Daniel James Fuchs

Missouri S&T’s Peer to Peer

Machine learning algorithms (MLAGs), frequently used in artificial intelligence (AI), rely on using patterns across sets of data to derive decision-making intelligence. In recent years, as society continues to give increasing authority to ML-driven AIs, these algorithms have demonstrated the ability to take on human-like discriminatory biases. Microsoft's "Tay," for example, a social media-based chatbot, went from resembling a normal teenage girl to displaying racist and sexist attitudes in a mere sixteen hours). Tay and many other ML-driven implementations across a wide variety of fields have replicated numerous human biases. In most cases, these human-like biases originated due to ...


Characteristics Of The Mantle Flow System Beneath The Indochina Peninsula Revealed By Teleseismic Shear Wave Splitting Analysis, Youqiang Yu, Stephen S. Gao, Kelly H. Liu, Ting Yang, Mei Xue, Khanh Phon Le, Jinyao Gao May 2018

Characteristics Of The Mantle Flow System Beneath The Indochina Peninsula Revealed By Teleseismic Shear Wave Splitting Analysis, Youqiang Yu, Stephen S. Gao, Kelly H. Liu, Ting Yang, Mei Xue, Khanh Phon Le, Jinyao Gao

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Numerous geoscientific investigations have been conducted on the southeastern Tibetan Plateau and adjacent areas for understanding crustal and mantle deformation associated with the indentation of the Indian Plate into Eurasia. A number of key issues, such as the causes of a sudden change of fast polarization orientations from N-S to almost E-W at approximately 26°N revealed by shear wave splitting (SWS) studies, and the geodynamic implications of the transition still remain enigmatic, partially due to the lack of sufficient SWS measurements on the Indochina Peninsula. Here we employ the SWS technique to systematically illuminate upper mantle anisotropy beneath the ...


Atomic Physics Constraints On The X Boson, Ulrich D. Jentschura, Istvan Nandori Apr 2018

Atomic Physics Constraints On The X Boson, Ulrich D. Jentschura, Istvan Nandori

Physics Faculty Research & Creative Works

Recently, a peak in the light fermion pair spectrum at invariant q)2 ≈ (16.7MeV)2 has been observed in the bombardment of 7Li by protons. This peak has been interpreted in terms of a protophobic interaction of fermions with a gauge boson (X boson) of invariant mass ≈16.7MeV which couples mainly to neutrons. High-precision atomic physics experiments aimed at observing the protophobic interaction need to separate the X boson effect from the nuclear-size effect, which is a problem because of the short range of the interaction (11.8 fm), which is commensurate with a "nuclear halo." Here ...


Following Coherent Multichannel Nuclear Wave Packets In Pump-Probe Studies Of O₂ With Ultrashort Laser Pulses, S. Xue, H. Du, B. Hu, C. D. Lin, Anh-Thu Le Apr 2018

Following Coherent Multichannel Nuclear Wave Packets In Pump-Probe Studies Of O₂ With Ultrashort Laser Pulses, S. Xue, H. Du, B. Hu, C. D. Lin, Anh-Thu Le

Physics Faculty Research & Creative Works

We reexamine the recent pump-probe experiment with O₂ using short intense infrared laser pulses theoretically. Using parameters that closely mimic the experimental conditions and taking into account the angle-dependent population redistribution due to resonant coupling between the relevant states, we show that the observed kinetic energy release spectra, including the energy-dependent structure and the quantum beat frequencies, can be accurately reproduced. Our results reveal additional important channels that were missed earlier. In particular, the strong contributions from O₂+a4Πu and b4Σb- states lead to the possibility of observing the interchannel beating. We further demonstrate ...


Improving The Total Organic Carbon Estimation Of The Eagle Ford Shale With Density Logs By Considering The Effect Of Pyrite, Shuxian Jiang, Mehdi Mokhtari, David M. Borrok, Jim Lee Apr 2018

Improving The Total Organic Carbon Estimation Of The Eagle Ford Shale With Density Logs By Considering The Effect Of Pyrite, Shuxian Jiang, Mehdi Mokhtari, David M. Borrok, Jim Lee

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Pyrite is a common mineral with a higher density than most other minerals in the Eagle Ford Shale formation. Hence, if pyrite is not considered in the total organic carbon (TOC) estimation, based on density logs, it may lead to errors. In order to improve the accuracy of the TOC estimation, we propose an updated TOC estimation method that incorporates the concentration of pyrite and organic porosity. More than 15 m of Eagle Ford Shale samples were analyzed using Rock-Eval pyrolysis, X-ray fluorescence (XRF), and X-ray diffraction (XRD). TOC, elemental concentration, and mineralogical data were analyzed for a better understanding ...


Platy Galena From The Viburnum Trend, Southeast Missouri: Character, Mine Distribution, Paragenetic Position, Trace Element Content, Nature Of Twinning, And Conditions Of Formation, Richard D. Hagni Mar 2018

Platy Galena From The Viburnum Trend, Southeast Missouri: Character, Mine Distribution, Paragenetic Position, Trace Element Content, Nature Of Twinning, And Conditions Of Formation, Richard D. Hagni

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Viburnum Trend of southeast Missouri is one of the world’s largest producers of lead. The lead occurs as galena, predominantly in two crystallographic forms, octahedrons and cubes. Many studies have shown that octahedral galena is paragentically early, the more abundant of the two crystal forms, and is commonly modified in the cube. Those studies also have shown that the cubic form is paragenetically later, less abundant than the octahedrons, and may exhibit minor octahedral modifications. Viburnum Trend galena crystals that exhibit a platy form have received almost no study. The reason for their lack of study is the ...


Femtosecond Laser Mass Spectrometry And High Harmonic Spectroscopy Of Xylene Isomers, Abdullah Alharbi, Andrewy E. Boguslavskiy, Dane Austin, Nicolas Thire, D. Wood, P. Hawkins, Felicity Mcgrath, A. S. Johnson, I. Lopez-Quintas, Bruno Schmidt, Francois Legare, J. P. Marangos, Anh-Thu Le, Ravi Bhardwaj Feb 2018

Femtosecond Laser Mass Spectrometry And High Harmonic Spectroscopy Of Xylene Isomers, Abdullah Alharbi, Andrewy E. Boguslavskiy, Dane Austin, Nicolas Thire, D. Wood, P. Hawkins, Felicity Mcgrath, A. S. Johnson, I. Lopez-Quintas, Bruno Schmidt, Francois Legare, J. P. Marangos, Anh-Thu Le, Ravi Bhardwaj

Physics Faculty Research & Creative Works

Structural isomers, molecules having the same chemical formula but with atoms bonded in different order, are hard to identify using conventional spectroscopy and mass spectrometry. They exhibit virtually indistinguishable mass spectra when ionized by electrons. Laser mass spectrometry based on photoionization of the isomers has emerged as a promising alternative but requires shaped ultrafast laser pulses. Here we use transform limited femtosecond pulses to distinguish the isomers using two methods. First, we probe doubly charged parent ions with circularly polarized light. We show that the yield of doubly charged ortho-xylene decreases while para-xylene increases over a range of laser intensities ...


Fractional Brownian Motion With A Reflecting Wall, Alexander H. O. Wada, Thomas Vojta Feb 2018

Fractional Brownian Motion With A Reflecting Wall, Alexander H. O. Wada, Thomas Vojta

Physics Faculty Research & Creative Works

Fractional Brownian motion, a stochastic process with long-time correlations between its increments, is a prototypical model for anomalous diffusion. We analyze fractional Brownian motion in the presence of a reflecting wall by means of Monte Carlo simulations. Whereas the mean-square displacement of the particle shows the expected anomalous diffusion behavior (x2) ~ tα, the interplay between the geometric confinement and the long-time memory leads to a highly non-Gaussian probability density function with a power-law singularity at the barrier. In the superdiffusive case α > 1, the particles accumulate at the barrier leading to a divergence of the probability density. For ...