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Missouri University of Science and Technology

2011

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Articles 1 - 30 of 131

Full-Text Articles in Physical Sciences and Mathematics

Prospects For Determination Of Thermal History After Inflation With Future Gravitational Wave Detectors, Sachiko Kuroyanagi, Kazunori Nakayama, Shun Saito Dec 2011

Prospects For Determination Of Thermal History After Inflation With Future Gravitational Wave Detectors, Sachiko Kuroyanagi, Kazunori Nakayama, Shun Saito

Physics Faculty Research & Creative Works

Thermal history of the Universe between inflation and big-bang nucleosynthesis has not yet been revealed observationally. It will be probed by the detection of primordial gravitational waves generated during inflation, which contain information on the reheating temperature as well as the equation of state of the Universe after inflation. Based on the Fisher information formalism, we examine how accurately the tensor-to-scalar ratio and reheating temperature after inflation can be simultaneously determined with space-based gravitational wave detectors such as the DECI-hertz Interferometer Gravitational-wave Observatory and the Big-Bang Observer. We show that the reheating temperature is best determined if it is around …


Assessment Of Corrosion Potential Of Coarse Backfill Aggregates For Mechanically Stabilized Earth Walls, Anita Thapalia, David M. Borrok, Soheil Nazarian, Jose Garibay Dec 2011

Assessment Of Corrosion Potential Of Coarse Backfill Aggregates For Mechanically Stabilized Earth Walls, Anita Thapalia, David M. Borrok, Soheil Nazarian, Jose Garibay

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The service life of mechanically stabilized earth walls depends on the rate of corrosion of the metallic reinforcements used in their construction. The assessment of corrosion potential requires an accurate evaluation of pH, resistivity, and sulfate and chloride concentrations of aqueous solutions in contact with the surrounding aggregate. Highway agencies tend to use larger aggregates that contain only a small amount of fine material (passing the Number 40 sieve) in the backfill. Evaluation of the electrochemical parameters of coarse aggregates is challenging because traditional evaluation methods call for the use of fine material. In this study, the suitability of traditional …


Surfactant Induced Reservoir Wettability Alteration: Recent Theoretical And Experimental Advances In Enhanced Oil Recovery, Yefei Wang, Huaimin Xu, Weizhao Yu, Baojun Bai, Xinwang Song, Jichao Zhang Dec 2011

Surfactant Induced Reservoir Wettability Alteration: Recent Theoretical And Experimental Advances In Enhanced Oil Recovery, Yefei Wang, Huaimin Xu, Weizhao Yu, Baojun Bai, Xinwang Song, Jichao Zhang

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Reservoir wettability plays an important role in various oil recovery processes. The origin and evolution of reservoir wettability were critically reviewed to better understand the complexity of wettability due to interactions in crude oil-brine-rock system, with introduction of different wetting states and their influence on fluid distribution in pore spaces. The effect of wettability on oil recovery of waterflooding was then summarized from past and recent research to emphasize the importance of wettability in oil displacement by brine. The mechanism of wettability alteration by different surfactants in both carbonate and sandstone reservoirs was analyzed, concerning their distinct surface chemistry, and …


Directional Limits On Persistent Gravitational Waves Using Ligo S5 Science Data, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2011

Directional Limits On Persistent Gravitational Waves Using Ligo S5 Science Data, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2 - 20 x 10-50 strain2 Hz-1 and 5 - 35 x 10-49 strain2Hz-1sr-1 for pointlike and extended sources, respectively. The latter result is the …


Thermal Correction To The Molar Polarizability Of A Boltzmann Gas, Ulrich D. Jentschura, Mariusz Puchalski, Peter J. Mohr Dec 2011

Thermal Correction To The Molar Polarizability Of A Boltzmann Gas, Ulrich D. Jentschura, Mariusz Puchalski, Peter J. Mohr

Physics Faculty Research & Creative Works

Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI), for which an accurate value of the Boltzmann constant is needed. Here we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when …


Magnetic Susceptibility As A Proxy For Investigating Microbially Mediated Iron Reduction, Farag M. Mewafy, Estella A. Atekwana, D. Dale Werkema, Lee D. Slater, Dimitrios Ntarlagiannis, Andre Revil, Magnus E. Skold, Geoffrey N. Delin Nov 2011

Magnetic Susceptibility As A Proxy For Investigating Microbially Mediated Iron Reduction, Farag M. Mewafy, Estella A. Atekwana, D. Dale Werkema, Lee D. Slater, Dimitrios Ntarlagiannis, Andre Revil, Magnus E. Skold, Geoffrey N. Delin

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

We investigated magnetic susceptibility (MS) variations in hydrocarbon contaminated sediments. Our objective was to determine if MS can be used as an intrinsic bioremediation indicator due to the activity of iron-reducing bacteria. A contaminated and an uncontaminated core were retrieved from a site contaminated with crude oil near Bemidji, Minnesota and subsampled for MS measurements. The contaminated core revealed enriched MS zones within the hydrocarbon smear zone, which is related to iron-reduction coupled to oxidation of hydrocarbon compounds and the vadose zone, which is coincident with a zone of methane depletion suggesting aerobic or anaerobic oxidation of methane is coupled …


Influence Of Gas Pressure On High-Order-Harmonic Generation Of Ar And Ne, Guoli Wang, Cheng Jin, Anh-Thu Le, C. D. Lin Nov 2011

Influence Of Gas Pressure On High-Order-Harmonic Generation Of Ar And Ne, Guoli Wang, Cheng Jin, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

We study the effect of gas pressure on the generation of high-order harmonics where harmonics due to individual atoms are calculated using the recently developed quantitative rescattering theory, and the propagation of the laser and harmonics in the medium is calculated by solving the Maxwell's wave equation. We illustrate that the simulated spectra are very sensitive to the laser focusing conditions at high laser intensity and high pressure since the fundamental laser field is severely reshaped during the propagation. By comparing the simulated results with several experiments we show that the pressure dependence can be qualitatively explained. The lack of …


Quantum Phase Transition Of The Sub-Ohmic Rotor Model, Manal Al-Ali, Thomas Vojta Nov 2011

Quantum Phase Transition Of The Sub-Ohmic Rotor Model, Manal Al-Ali, Thomas Vojta

Physics Faculty Research & Creative Works

We investigate the behavior of an N-component quantum rotor coupled to a bosonic dissipative bath having a sub-Ohmic spectral density J (ω) ∝ ωs with s < 1.With increasing dissipation strength, this system undergoes a quantum phase transition from a delocalized phase to a localized phase.We determine the exact critical behavior of this transition in the large-N limit. For 1 > s > 1/2, we find nontrivial critical behavior corresponding to an interacting renormalization group fixed point, while we find mean-field behavior for s < 1/2. The results agree with those of the corresponding long-range …


Investigating Combinatorial Approaches In Virtual Screening On Human Inducible 6-Phosphofructo-2-Kinase/Fructose-2,6-Bisphosphatase (Pfkfb3): A Case Study For Small Molecule Kinases, Robert B. Crochet, Michael C. Cavalier, Minsuh Seo, Jeong Do Kim, Young Sun Yim, Seung Jong Park, Yong Hwan Lee Nov 2011

Investigating Combinatorial Approaches In Virtual Screening On Human Inducible 6-Phosphofructo-2-Kinase/Fructose-2,6-Bisphosphatase (Pfkfb3): A Case Study For Small Molecule Kinases, Robert B. Crochet, Michael C. Cavalier, Minsuh Seo, Jeong Do Kim, Young Sun Yim, Seung Jong Park, Yong Hwan Lee

Computer Science Faculty Research & Creative Works

Efforts toward improving the predictiveness in tier-based approaches to virtual screening (VS) have mainly focused on protein kinases. Despite their significance as drug targets, small molecule kinases have been rarely tested with these approaches. In this paper, we investigate the efficacy of a pharmacophore screening-combined structure-based docking approach on the human inducible 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, an emerging target for cancer chemotherapy. Six out of a total 1364 compounds from NCI's Diversity Set II were selected as true actives via throughput screening. Using a database constructed from these compounds, five programs were tested for structure-based docking (SBD) performance, the MOE of which showed …


Infinite-Randomness Criticality In A Randomly Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Thomas Vojta Nov 2011

Infinite-Randomness Criticality In A Randomly Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Thomas Vojta

Physics Faculty Research & Creative Works

We study the ferromagnetic phase transition in a randomly layered Heisenberg magnet using large-scale Monte Carlo simulations. Our results provide numerical evidence for the infinite-randomness scenario recently predicted within a strong-disorder renormalization-group approach. Specifically, we investigate the finite-size scaling behavior of the magnetic susceptibility, which is characterized by a nonuniversal power-law divergence in the Griffiths phase. We also study the perpendicular and parallel spin-wave stiffnesses in the Griffiths phase. In agreement with the theoretical predictions, the parallel stiffness is nonzero for all temperatures T < Tc. In contrast, the perpendicular stiffness remains zero in part of the ordered phase, giving …


C(Naphthyl)-H Bond Activation By Rhodium: Isolation, Characterization And Td-Dft Study Of The Cyclometallates, Achintesh Narayan Biswas, Purak K. Das, Sandip K. Sengupta, Amitava Choudhury, Pinaki K. Bandyopadhyay Nov 2011

C(Naphthyl)-H Bond Activation By Rhodium: Isolation, Characterization And Td-Dft Study Of The Cyclometallates, Achintesh Narayan Biswas, Purak K. Das, Sandip K. Sengupta, Amitava Choudhury, Pinaki K. Bandyopadhyay

Chemistry Faculty Research & Creative Works

The C1(naphthyl)-H, C2(naphthyl)-H, C3(naphthyl)-H and C8(naphthyl)-H bonds of the naphthyl group present in a group of naphthylazo-2'-hydroxyarenes (H 2L) have been activated by [Rh(PPh 3) 3Cl] in a toluene medium. Here the cyclometallation is accompanied by metal centered oxidation [Rh(i)?Rh(iii)]. All the resulting cyclometallates [Rh(PPh 3) 2(L)Cl] (2-5) have been isolated in a pure form. The characterization of the cyclometallates [Rh(PPh 3) 2(L)Cl] have been done on the basis of spectral (IR, UV-vis, and FAB mass) data. The structures of the representative cyclometallates 2a, 3a, 4a, 4b and 5b have been determined by …


An Engineered Approach To Stem Cell Culture: Automating The Decision Process For Real-Time Adaptive Subculture Of Stem Cells, Dai Fei Elmer Ker, Lee E. Weiss, Silvina N. Junkers, Mei Chen, Zhaozheng Yin, Mike F. Sandbothe, Seungil Huh, Sungeun Eom, Ryoma Bise, Elvira Osuna-Highley, Takeo Kanade, Phil Gordon Campbell Nov 2011

An Engineered Approach To Stem Cell Culture: Automating The Decision Process For Real-Time Adaptive Subculture Of Stem Cells, Dai Fei Elmer Ker, Lee E. Weiss, Silvina N. Junkers, Mei Chen, Zhaozheng Yin, Mike F. Sandbothe, Seungil Huh, Sungeun Eom, Ryoma Bise, Elvira Osuna-Highley, Takeo Kanade, Phil Gordon Campbell

Computer Science Faculty Research & Creative Works

Current cell culture practices are dependent upon human operators and remain laborious and highly subjective, resulting in large variations and inconsistent outcomes, especially when using visual assessments of cell confluency to determine the appropriate time to subculture cells. Although efforts to automate cell culture with robotic systems are underway, the majority of such systems still require human intervention to determine when to subculture. Thus, it is necessary to accurately and objectively determine the appropriate time for cell passaging. Optimal stem cell culturing that maintains cell pluripotency while maximizing cell yields will be especially important for efficient, cost-effective stem cell-based therapies. …


Estimation Of The Depth Of Anisotropy Using Spatial Coherency Of Shear-Wave Splitting Parameters, Kelly H. Liu, Stephen S. Gao Oct 2011

Estimation Of The Depth Of Anisotropy Using Spatial Coherency Of Shear-Wave Splitting Parameters, Kelly H. Liu, Stephen S. Gao

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Shear-wave splitting (SWS) analyses are essential in understanding the structure and dynamics of the Earth's deep interior. While splitting measurements have excellent horizontal resolution relative to other anisotropy-measuring techniques, their vertical resolution is low due to the steep incidence angle of the seismic phases used by the analyses. Here, using synthetic and real data, we present and test a simple approach to estimate the optimal depth of anisotropy by measuring the spatial coherency of the splitting parameters. The approach searches for the optimal depth by computing a spatial variation factor. Tests using synthetic SWS data produced with varying number of …


Reply To "Comment On 'Counterintuitive Consequence Of Heating In Strongly-Driven Intrinsic Junctions Of Bi₂Sr₂Cacu₂O 8+Δ Mesas'", Cihan Kurter, Lutfi Ozyuzer, Thomas Proslier, John F. Zasadzinski, David G. Hinks, Kenneth E. Gray Oct 2011

Reply To "Comment On 'Counterintuitive Consequence Of Heating In Strongly-Driven Intrinsic Junctions Of Bi₂Sr₂Cacu₂O 8+Δ Mesas'", Cihan Kurter, Lutfi Ozyuzer, Thomas Proslier, John F. Zasadzinski, David G. Hinks, Kenneth E. Gray

Physics Faculty Research & Creative Works

The main criticism raised in the preceding Comment concerns our suggestion that sharp conduction peaks in Bi2Sr2CaCu2O 8+δ mesas, along with absent dip-hump features, may, in general, be a result of self-heating. The author points to the variety of experimental configurations, matrix-element effects, and doping dependencies that might allow a diversity of conductance spectra. We argue that numerous mesa studies (with fixed matrix elements) firmly establish the systematic development of sharp conductance peaks with increased self-heating, and thus, the issue of nonuniversality of tunneling characteristics is not relevant. The author mentions a number of studies that …


Orientation Dependence Of The Ionization Of Co And No In An Intense Femtosecond Two-Color Laser Field, H. Li, D. Ray, S. De, I. Znakovskaya, W. Cao, G. Laurent, Z. Wang, M. F. Kling, Anh-Thu Le, C. L. Cocke Oct 2011

Orientation Dependence Of The Ionization Of Co And No In An Intense Femtosecond Two-Color Laser Field, H. Li, D. Ray, S. De, I. Znakovskaya, W. Cao, G. Laurent, Z. Wang, M. F. Kling, Anh-Thu Le, C. L. Cocke

Physics Faculty Research & Creative Works

Two-color (800- and 400-nm) short (45-fs) linearly polarized pulses are used to ionize and dissociate CO and NO. The emission of Cq+, Nq+, and O⁺ fragments indicates that the higher ionization rate occurs when the peak electric field points from C to O in CO and from N to O in NO. This preferred direction is in agreement with that predicted by Stark-corrected strong-field-approximation calculations.


Generation Of Isolated Attosecond Pulses In The Far Field By Spatial Filtering With An Intense Few-Cycle Mid-Infrared Laser, Cheng Jin, Anh-Thu Le, Carlos A. Trallero-Herrero, C. D. Lin Oct 2011

Generation Of Isolated Attosecond Pulses In The Far Field By Spatial Filtering With An Intense Few-Cycle Mid-Infrared Laser, Cheng Jin, Anh-Thu Le, Carlos A. Trallero-Herrero, C. D. Lin

Physics Faculty Research & Creative Works

We report theoretical calculations of high-order harmonic generation (HHG) of Xe with the inclusion of multielectron effects and macroscopic propagation of the fundamental and harmonic fields in an ionizing medium. By using the time-frequency analysis we show that the reshaping of the fundamental laser field is responsible for the continuum structure in the HHG spectra. We further suggest a method for obtaining an isolated attosecond pulse (IAP) by using a filter centered on axis to select the harmonics in the far field with different divergence. We also discuss the carrier-envelope-phase dependence of an IAP and the possibility to optimize the …


Analysis And Finite Element Approximation Of A Coupled, Continuum Pipe-Flow/Darcy Model For Flow In Porous Media With Embedded Conduits, Yanzhao Cao, Max Gunzburger, Fei Hua, Xiaoming Wang Sep 2011

Analysis And Finite Element Approximation Of A Coupled, Continuum Pipe-Flow/Darcy Model For Flow In Porous Media With Embedded Conduits, Yanzhao Cao, Max Gunzburger, Fei Hua, Xiaoming Wang

Mathematics and Statistics Faculty Research & Creative Works

We consider the continuum Darcy/pipe flow model for flows in a porous matrix containing embedded conduits; such coupled flows are present in, e.g., karst aquifers. the mathematical well-posedness of the coupled problem as well as convergence rates of finite element approximation are established in the two-dimensional case. Computational results are also provided. © 2010 Wiley Periodicals, Inc.


Transport Properties In Antiferromagnetic Quantum Griffiths Phases, David Nozadze, Thomas Vojta Sep 2011

Transport Properties In Antiferromagnetic Quantum Griffiths Phases, David Nozadze, Thomas Vojta

Physics Faculty Research & Creative Works

We study the electrical resistivity in the quantum Griffiths phase associated with the antiferromagnetic quantum phase transition in a metal. The resistivity is calculated by means of the semi-classical Boltzmann equation. We show that the scattering of electrons by locally ordered rare regions leads to a singular temperature dependence. The rare-region contribution to the resistivity varies as Tλ with temperature T, where λ is the usual Griffiths exponent which takes the value zero at the critical point and increases with distance from criticality. We find similar singular contributions to other transport properties such as thermal resistivity, thermopower and the …


Double Ionization Of Helium By Highly-Charged-Ion Impact Analyzed Within The Frozen-Correlation Approximation, Marcelo F. Ciappina, Tom Kirchner, Michael Schulz Sep 2011

Double Ionization Of Helium By Highly-Charged-Ion Impact Analyzed Within The Frozen-Correlation Approximation, Marcelo F. Ciappina, Tom Kirchner, Michael Schulz

Physics Faculty Research & Creative Works

We apply the frozen-correlation approximation (FCA) to analyze double ionization of helium by energetic highly charged ions. In this model the double ionization amplitude is represented in terms of single ionization amplitudes, which we evaluate within the continuum distorted wave-eikonal initial state (CDW-EIS) approach. Correlation effects are incorporated in the initial and final states, but are neglected during the time the collision process takes place. We implement the FCA using the Monte Carlo event generator technique, which allows us to generate theoretical event files and to compare theory and experiment using the same analysis tools. The comparison with previous theoretical …


Microscopic Examination Of Hot Spots Giving Rise To Nonlinearity In Superconducting Resonators, Cihan Kurter, Alexander P. Zhuravel, Alexey V. Ustinov, Steven M. Anlage Sep 2011

Microscopic Examination Of Hot Spots Giving Rise To Nonlinearity In Superconducting Resonators, Cihan Kurter, Alexander P. Zhuravel, Alexey V. Ustinov, Steven M. Anlage

Physics Faculty Research & Creative Works

We investigate the microscopic origins of nonlinear rf response in superconducting electromagnetic resonators. Strong nonlinearity appearing in the transmission spectra at high input powers manifests itself through the emergence of jumplike features near the resonant frequency that evolve toward lower quality factor with higher insertion loss as the rf input power is increased. We directly relate these characteristics to the dynamics of localized normal regions (hot spots) caused by microscopic features in the superconducting material making up the resonator. A clear observation of hot-spot formation inside a Nb thin film self-resonant structure is presented by employing the microwave laser scanning …


Lattice Dynamics In The Fesb₃ Skutterudite, Anne Möchel, Ilya Sergueev, Ngoc Thanh Nguyen, Gary J. Long, Fernande Grandjean, D. C. Johnson, Raphäel P. Hermann Aug 2011

Lattice Dynamics In The Fesb₃ Skutterudite, Anne Möchel, Ilya Sergueev, Ngoc Thanh Nguyen, Gary J. Long, Fernande Grandjean, D. C. Johnson, Raphäel P. Hermann

Chemistry Faculty Research & Creative Works

Thin films of FeSb3 were characterized by electronic transport, magnetometry, x-ray diffraction, 57Fe and 121Sb nuclear inelastic scattering, and 57Fe Mössbauer spectroscopy. Resistivity and magnetometry measurements reveal semiconducting behavior with a 16.3(4) meV band gap and an effective paramagnetic moment of 0.57(6) B, respectively. A systematic comparison of the lattice dynamics with CoSb3 and EuFe 4Sb12 reveals that the Fe4Sb12 framework is softer than the Co4Sb12 framework, and that the observed softening and the associated lowering of the lattice thermal conductivity in the RFe4Sb12 filled skutterudites …


A Large-Scale Synthesis And Characterization Of Quaternary Cuinₓga₁₋ₓs₂ Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary J. Long, Cyril Bajracharya, Jerry D. Harris, Alexander Punnoose, René G. Rodriguez, Joshua J. Pak Aug 2011

A Large-Scale Synthesis And Characterization Of Quaternary Cuinₓga₁₋ₓs₂ Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary J. Long, Cyril Bajracharya, Jerry D. Harris, Alexander Punnoose, René G. Rodriguez, Joshua J. Pak

Chemistry Faculty Research & Creative Works

Various quaternary CuInxGa1-xS2 (0≤x≤1) chalcopyrite nanoparticles have been prepared from molecular single-source precursors via microwave decomposition. We were able to control the nanoparticle size, phase, stoichiometry, and solubility. Depending on the choice of surface modifiers used, we were able to tune the solubility of the resulting nanoparticles. This method has been used to generate up to 5g of nanoparticles and up to 150g from multiple batch reactions with excellent reproducibility. Data from UV-Vis, photoluminescence, X-ray diffraction, TEM, DSC/TGA-MS, and ICP-OES analyses have shown high reproducibility in nanoparticle size, composition, and bandgap.


Strong-Field Nonsequential Double Ionization Of Ar And Ne, Zhangjin Chen, Yaqiu Liang, Don H. Madison, Chiidong Lin Aug 2011

Strong-Field Nonsequential Double Ionization Of Ar And Ne, Zhangjin Chen, Yaqiu Liang, Don H. Madison, Chiidong Lin

Physics Faculty Research & Creative Works

We investigate the nonsequential double ionization (NSDI) of Ar and Ne based on quantitative rescattering theory (QRS). According to QRS theory, each elementary NSDI process can be calculated by multiplying the returning electron wave packet with appropriate differential electron-ion scattering cross sections. We include (e, 2e) and electron-impact excitation cross sections of Ar+ to obtain the correlated electron momentum spectra for the NSDI of Ar by few-cycle pulses to check the dependence of NSDI on the carrier-envelope phase. The results are compared to the ion momentum spectra from the recent experiment of Johnson [Phys. Rev. APLRAAN1050-294710.1103/ PhysRevA.83.013412 83, 013412 …


Mutual Projectile And Target Ionization In 1-Mev/Amu N⁴⁺ And N₅⁺+ He Collisions, Xincheng Wang, Katharina R. Schneider, Aditya H. Kelkar, Gunterschul Brenner, Michael Schulz, B. Najjari, Alexander B. Voitkiv, M. Gundmundsson, Manfred Grieser, Claude Krantz, Michael Lestinsky, Andreas R. Wolf, Siegbert Hagmann, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer Aug 2011

Mutual Projectile And Target Ionization In 1-Mev/Amu N⁴⁺ And N₅⁺+ He Collisions, Xincheng Wang, Katharina R. Schneider, Aditya H. Kelkar, Gunterschul Brenner, Michael Schulz, B. Najjari, Alexander B. Voitkiv, M. Gundmundsson, Manfred Grieser, Claude Krantz, Michael Lestinsky, Andreas R. Wolf, Siegbert Hagmann, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer

Physics Faculty Research & Creative Works

We have studied mutual projectile and target ionization in 1-MeV/amu N4+ and N5++He collisions in kinematically complete experiments by measuring the momenta of the recoil ion and both ejected electrons in coincidence with the charge-changed projectiles. By means of four-particle Dalitz plots, in which multiple differential cross sections are presented as a function of the momenta of all four particles, experimental spectra are compared with theoretical results from various models. The experimental data are qualitatively reproduced by higher-order calculations, where good agreement is achieved for N5++He collisions, while some discrepancies persist for N4++He …


A Parallel Robin-Robin Domain Decomposition Method For The Stokes-Darcy System, Wenbin Chen, Max Gunzburger, Fei Hua, Xiaoming Wang Jul 2011

A Parallel Robin-Robin Domain Decomposition Method For The Stokes-Darcy System, Wenbin Chen, Max Gunzburger, Fei Hua, Xiaoming Wang

Mathematics and Statistics Faculty Research & Creative Works

We propose a new parallel Robin-Robin domain decomposition method for the coupled Stokes-Darcy system with Beavers-Joseph-Saffman-Jones interface boundary condition. in particular, we prove that, with an appropriate choice of parameters, the scheme converges geometrically independent of the mesh size. © 2011 Society for Industrial and Applied Mathematics.


Classical Analogue Of Electromagnetically Induced Transparency With A Metal-Superconductor Hybrid Metamaterial, Cihan Kurter, Philippe Tassin, Lei Zhang, Thomas Koschny, Alexander P. Zhuravel, Alexey V. Ustinov, Steven Mark Anlage, Costas M. Soukoulis Jul 2011

Classical Analogue Of Electromagnetically Induced Transparency With A Metal-Superconductor Hybrid Metamaterial, Cihan Kurter, Philippe Tassin, Lei Zhang, Thomas Koschny, Alexander P. Zhuravel, Alexey V. Ustinov, Steven Mark Anlage, Costas M. Soukoulis

Physics Faculty Research & Creative Works

Metamaterials are engineered materials composed of small electrical circuits producing novel interactions with electromagnetic waves. Recently, a new class of metamaterials has been created to mimic the behavior of media displaying electromagnetically induced transparency (EIT). Here we introduce a planar EIT metamaterial that creates a very large loss contrast between the dark and radiative resonators by employing a superconducting Nb film in the dark element and a normal-metal Au film in the radiative element. Below the critical temperature of Nb, the resistance contrast opens up a transparency window along with a large enhancement in group delay, enabling a significant slowdown …


Bis[2-(1h-Imidazol-2-Yl-Κn³)-1h-Imidazol-3-Ium]Silver(I) Trinitrate, Shelonda R. Finch, J. P. Harper, Amitava Choudhury, Ekkehard Sinn, Harvest L. Collier Jul 2011

Bis[2-(1h-Imidazol-2-Yl-Κn³)-1h-Imidazol-3-Ium]Silver(I) Trinitrate, Shelonda R. Finch, J. P. Harper, Amitava Choudhury, Ekkehard Sinn, Harvest L. Collier

Chemistry Faculty Research & Creative Works

The synthesis of the title salt, [Ag(C 6H 7N 4) 2](NO 3) 3, was carried out employing a 1:2 molar ratio of 2,2'-biimidazole and silver nitrate respectively. The cation has crystallographically-imposed C2 symmetry with the metal atom in an almost linear coordination environment [N - Ag - N = 177.01 (17)°]. The crystal structure displays N - H⋯O and C - H⋯O hydrogen-bonding interactions.


Relativistic Reduced-Mass And Recoil Corrections To Vacuum Polarization In Muonic Hydrogen, Muonic Deuterium, And Muonic Helium Ions, Ulrich D. Jentschura Jul 2011

Relativistic Reduced-Mass And Recoil Corrections To Vacuum Polarization In Muonic Hydrogen, Muonic Deuterium, And Muonic Helium Ions, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

The reduced-mass dependence of relativistic and radiative effects in simple muonic bound systems is investigated. The spin-dependent nuclear recoil correction of order (Zα)4μ3/m2N is evaluated for muonic hydrogen and deuterium and muonic helium ions (μ is the reduced mass and mN is the nuclear mass). Relativistic corrections to vacuum polarization of order α(Zα)4μ are calculated, with a full account of the reduced-mass dependence. The results shift theoretical predictions. The radiative-recoil correction to vacuum polarization of order α(Zα)5-ln2(Zα) μ2/mN is obtained in leading logarithmic approximation. …


Young-Type Interference In Projectile-Electron Loss In Energetic Ion-Molecule Collisions, Alexander B. Voitkiv, B. Najjari, Daniel Fischer, Anton N. Artemyev, Andrey S. Surzhykov Jun 2011

Young-Type Interference In Projectile-Electron Loss In Energetic Ion-Molecule Collisions, Alexander B. Voitkiv, B. Najjari, Daniel Fischer, Anton N. Artemyev, Andrey S. Surzhykov

Physics Faculty Research & Creative Works

Under certain conditions an electron bound in a fast projectile ion, colliding with a molecule, interacts mainly with the nuclei and inner shell electrons of atoms forming the molecule. Because of their compact localization in space and distinct separation from each other, these molecular centers play in such collisions a role similar to that of optical slits in light scattering leading to pronounced interference in the spectra of the electron emitted from the projectile.


Composition-Tuned Smeared Phase Transitions, Fawaz Hrahsheh, David Nozadze, Thomas Vojta Jun 2011

Composition-Tuned Smeared Phase Transitions, Fawaz Hrahsheh, David Nozadze, Thomas Vojta

Physics Faculty Research & Creative Works

Phase transitions in random systems are smeared if individual spatial regions can order independently of the bulk system. In this paper, we study such smeared phase transitions (both classical and quantum) in substitutional alloys A 1-xB x that can be tuned from an ordered phase at composition x=0 to a disordered phase at x=1. We show that the ordered phase develops a pronounced tail that extends over all compositions x<1. Using optimal fluctuation theory, we derive the composition dependence of the order parameter and other quantities in the tail of the smeared phase transition. We also compare our results to computer simulations of a toy model, and we discuss experiments.