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Articles 1 - 24 of 24
Full-Text Articles in Physical Sciences and Mathematics
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, Suwit Suthirakun, Salai Cheettu Ammal, Guoliang Xiao, Fanglin Chen, Andreas Heyden, Hans-Conrad Zur Loye
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, Suwit Suthirakun, Salai Cheettu Ammal, Guoliang Xiao, Fanglin Chen, Andreas Heyden, Hans-Conrad Zur Loye
Faculty Publications
The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO …
Consequences Of Neutrino Lorentz Violation For Leptonic Meson Decays, Brett David Altschul
Consequences Of Neutrino Lorentz Violation For Leptonic Meson Decays, Brett David Altschul
Faculty Publications
If the observation by OPERA of apparently superluminal neutrinos is correct, the Lagrangian for second-generation leptons must break Lorentz invariance. We calculate the effects of an energy-independent change in the neutrino speed on another observable, the charged pion decay rate. The rate decreases by an factor [1 - 3/(1 - (m_mu)^2 / (m_pi) ^ 2) (< v_(nu) > - 1)], where < v_(nu) > is the (directionally averaged) neutrino speed in the pion's rest frame. This provides a completely independent experimental observable that is sensitive to the same forms of Lorentz violation as a neutrino time of flight measurement.
The Regulation Of Skeletal Muscle Protein Turnover During The Progression Of Cancer Cachexia In The ApcMin/+ Mouse, James P. White, John W. Baynes, Stephen L. Welle, Matthew C. Kostek, Lydia E. Matesic, Shuichi Sato, James A. Carson
The Regulation Of Skeletal Muscle Protein Turnover During The Progression Of Cancer Cachexia In The ApcMin/+ Mouse, James P. White, John W. Baynes, Stephen L. Welle, Matthew C. Kostek, Lydia E. Matesic, Shuichi Sato, James A. Carson
Faculty Publications
Muscle wasting that occurs with cancer cachexia is caused by an imbalance in the rates of muscle protein synthesis and degradation. The Apc(Min/+) mouse is a model of colorectal cancer that develops cachexia that is dependent on circulating IL-6. However, the IL-6 regulation of muscle protein turnover during the initiation and progression of cachexia in the Apc(Min/+) mouse is not known. Cachexia progression was studied in Apc(Min/+) mice that were either weight stable (WS) or had initial (≤5%), intermediate (6-19%), or extreme (≥20%) body weight loss. The initiation of cachexia reduced %MPS 19% and a further ∼50% with additional weight …
Time Reversal Invariance Violating And Parity Conserving Effects In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Time Reversal Invariance Violating And Parity Conserving Effects In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Faculty Publications
Time reversal invariance violating and parity conserving effects for low-energy elastic neutron-deuteronscattering are calculated for meson exchange and effective field theory type potentials in a distorted wave-bornapproximation using realistic hadronic wave functions, obtained by solving three-body Faddeev equations inconfiguration space.
Dynamics Of Spin Relaxation In Finite-Size Two-Dimensional Systems: An Exact Solution, Valeriy A. Slipko, Yuriy V. Pershin
Dynamics Of Spin Relaxation In Finite-Size Two-Dimensional Systems: An Exact Solution, Valeriy A. Slipko, Yuriy V. Pershin
Faculty Publications
We find an exact solution for the problem of electron spin relaxation in a two-dimensional (2D) circle with Rashba spin-orbit interaction. Our analysis shows that the spin relaxation in finite-size regions involves three stages and is described by multiple spin relaxation times. It is important that the longest spin relaxation time increases with the decrease in system radius but always remains finite. Therefore, at long times, the spin polarization in small 2D systems decays exponentially with a size-dependent rate. This prediction is supported by results of Monte Carlo simulations.
Bounding Lorentz Violation At Particle Colliders By Tracking The Motion Of Charged Particles, Brett David Altschul
Bounding Lorentz Violation At Particle Colliders By Tracking The Motion Of Charged Particles, Brett David Altschul
Faculty Publications
In the presence of Lorentz violation, the motion of a charged particle in a magnetic field is distorted. By measuring the eccentricities of particles’ elliptical orbits and studying how those eccentricities vary with the absolute orientation of the laboratory, it is possible to constrain the Lorentz-violating cJK parameters. For each observed species, this method can provide constraints on four linear combinations of coefficients for which, in some species, there are presently no two-sided bounds.
Efficient Quantum Trajectory Representation Of Wavefunctions Evolving In Imaginary Time, Sophya V. Garashchuk, James Mazzuca, Tijo Vazhappilly
Efficient Quantum Trajectory Representation Of Wavefunctions Evolving In Imaginary Time, Sophya V. Garashchuk, James Mazzuca, Tijo Vazhappilly
Faculty Publications
The Boltzmann evolution of a wavefunction can be recast as imaginary-time dynamics of the quantum trajectory ensemble. The quantum effects arise from the momentum-dependent quantum potential – computed approximately to be practical in high-dimensional systems – influencing the trajectories in addition to the external classical potential [S. Garashchuk, J. Chem. Phys.132, 014112 (2010)]. For a nodelesswavefunction represented as ψ(x, t) = exp ( − S(x, t)/ℏ) with the trajectory momenta defined by ∇S(x, t), analysis of the Lagrangian and Eulerian evolution shows that for bound potentials the former …
Time Reversal Invariance Violation In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Time Reversal Invariance Violation In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Faculty Publications
Time reversal invariance-violating (TRIV) effects in low-energy elastic neutron-deuteron scattering arecalculated using meson exchange and EFT-type TRIV potentials in a distorted-wave Born approximation withrealistic hadronic strong interaction wave functions, obtained by solving the three-body Faddeev equations inconfiguration space. The relation between TRIV and parity-violating observables is discussed.
Growth Direction Modulation And Diameter-Dependent Mobility In Inn Nanowires, Goutam Koley, Zhihua Cai, Ehtesham Bin Quddus, Jie Liu, Muhammad Qazi, Richard A. Webb
Growth Direction Modulation And Diameter-Dependent Mobility In Inn Nanowires, Goutam Koley, Zhihua Cai, Ehtesham Bin Quddus, Jie Liu, Muhammad Qazi, Richard A. Webb
Faculty Publications
Diameter-dependent electrical properties of InN nanowires (NWs) grown by chemical vapor deposition have been investigated. The NWs exhibited interesting properties of coplanar deflection at specific angles, either spontaneously, or when induced by other NWs or lithographically patterned barriers. InN NW-based back-gated field effect transistors (FETs) showed excellent gate control and drain current saturation behaviors. Both NW conductance and carrier mobility calculated from the FET characteristics were found to increase regularly with a decrease in NW diameter. The observed mobility and conductivity variations have been modeled by considering NW surface and core conduction paths.
A Layer Correlation Technique For Pion Energy Calibration At The 2004 Atlas Combined Beam Test, E. Abat, J M. Abdallah, T N. Addy, P Adragna, M Aharrouche, A Ahmad, T Pa Akesson, M Aleksa, C Alexa, K Anderson, A Andreazza, F Anghinolfi, A Antonaki, G Arabize, E Arik, T Atkinson, J Baines, O K. Baker, D Banfi, S Baron, Roberto Petti, Et. Al.
A Layer Correlation Technique For Pion Energy Calibration At The 2004 Atlas Combined Beam Test, E. Abat, J M. Abdallah, T N. Addy, P Adragna, M Aharrouche, A Ahmad, T Pa Akesson, M Aleksa, C Alexa, K Anderson, A Andreazza, F Anghinolfi, A Antonaki, G Arabize, E Arik, T Atkinson, J Baines, O K. Baker, D Banfi, S Baron, Roberto Petti, Et. Al.
Faculty Publications
A new method for calibrating the hadron response of a segmented calorimeter is developed and successfully applied to beam test data. It is based on a principal component analysis of energy deposits in the calorimeter layers, exploiting longitudinal shower development information to improve the measured energy resolution. Corrections for invisible hadronic energy and energy lost in dead material in front of and between the calorimeters of the ATLAS experiment were calculated with simulated Geant4 Monte Carlo events and used to reconstruct the energy of pions impinging on the calorimeters during the 2004 Barrel Combined Beam Test at the CERN H8 …
Spontaneous Emergence Of A Persistent Spin Helix From Homogeneous Spin Polarization, Valeriy A. Slipko, Ibrahim Savran, Yuriy V. Pershin Dr
Spontaneous Emergence Of A Persistent Spin Helix From Homogeneous Spin Polarization, Valeriy A. Slipko, Ibrahim Savran, Yuriy V. Pershin Dr
Faculty Publications
We demonstrate that a homogeneous spin polarization in one-dimensional structures of finite length in the presence of Bychkov-Rashba spin-orbit coupling decays spontaneously toward a persistent spin helix. Such a strikingly different and simple method enables us to generate robust spin structures whose properties can be tuned by the strength of the spin-orbit interaction and/or the structure’s length. We generalize our results for the two-dimensional case predicting the formation of a persistent spin helix in two-dimensional channels from homogeneous spin polarization. An analysis of the formation of a spin helical state is presented within an approach based on a mapping of …
Renormalization Of Scalar And Yukawa Field Theories With Lorentz Violation, Alejandro Ferrero, Brett David Altschul
Renormalization Of Scalar And Yukawa Field Theories With Lorentz Violation, Alejandro Ferrero, Brett David Altschul
Faculty Publications
We consider a theory of scalar and spinor fields, interacting through Yukawa and ϕ4 interactions, with Lorentz-violating operators included in the Lagrangian. We compute the leading quantum corrections in this theory. The renormalizability of the theory is explicitly shown up to one-loop order. In the pure scalar sector, the calculations can be generalized to higher orders and to include finite terms, because the theory can be solved in terms of its Lorentz-invariant version.
A Bis-Urea Naphthalene Macrocycle Displaying Two Crystal Structures With Parallel Ureas, Michael F. Geer, Mark D. Smith, Linda S. Shimizu
A Bis-Urea Naphthalene Macrocycle Displaying Two Crystal Structures With Parallel Ureas, Michael F. Geer, Mark D. Smith, Linda S. Shimizu
Faculty Publications
Herein we synthesized a bis-urea macrocycle from 2,7-dimethylnaphthalene that displays an unusual parallel urea conformation. The naphthalenes also adopt a bowl shape over the anticipated parallel planar orientation. Crystallization of the macrocycle from different solvent systems affords two solvated forms. 1·DMSO·(H2O)2 has an extended columnar structure where parallel macrocycles are linked by intervening hydrogen bonded water molecules. In 1·(MeOH)2direct hydrogen-bonds link the macrocycles into chains, which hydrogen-bond with methanolmolecules to form a layered structure.
Measurements And Three-Dimensional Modeling Of Nearshore Circulation On A South Carolina Beach, Nirnimesh Kumar, George Voulgaris, John C. Warner
Measurements And Three-Dimensional Modeling Of Nearshore Circulation On A South Carolina Beach, Nirnimesh Kumar, George Voulgaris, John C. Warner
Faculty Publications
A numerical modeling system for simulating nearshore surf zone conditions and tidal processes is presented and evaluated with in situ data. The modeling system is comprised of the Regional Ocean Modeling System (ROMS v 3.0), a three-dimensional numerical ocean model, coupled with Simulating Waves Nearshore (SWAN), a spectral wave propagation model. The system has been modified with a new vertical distribution of radiation stress terms for applications in very shallow waters. The model performance is evaluated by comparing simulations to hydrodynamic data (wave height, direction, longshore and cross-shore currents) collected in the surf zone in northern South Carolina, U.S. Model …
Photon Reconstruction In The Atlas Inner Detector And Liquid Argon Barrel Calorimeter At The 2004 Combined Test Beam, E. Abat, J. M. Abdallah, T. N. Addy, P. Adragna, M. Aharrouche, A. Ahmad, T. P. Akesson, M. Aleksa, C. Alexa, K. Anderson, A. Andreazza, F. Anghinolf, A. Antonaki, G. Arabidze, E. Arik, T. Atkinson, J. Baines, O. K. Baker, D. Banfi, S. Baron, Roberto Petti, Et. Al.
Photon Reconstruction In The Atlas Inner Detector And Liquid Argon Barrel Calorimeter At The 2004 Combined Test Beam, E. Abat, J. M. Abdallah, T. N. Addy, P. Adragna, M. Aharrouche, A. Ahmad, T. P. Akesson, M. Aleksa, C. Alexa, K. Anderson, A. Andreazza, F. Anghinolf, A. Antonaki, G. Arabidze, E. Arik, T. Atkinson, J. Baines, O. K. Baker, D. Banfi, S. Baron, Roberto Petti, Et. Al.
Faculty Publications
The reconstruction of photons in the ATLAS detector is studied with data taken during the 2004 Combined Test Beam, where a full slice of the ATLAS detector was exposed to beams of particles of known energy at the CERN SPS. The results presented show significant differences in the longitudinal development of the electromagnetic shower between converted and unconverted photons as well as in the total measured energy. The potential to use the reconstructed converted photons as a means to precisely map the material of the tracker in front of the electromagnetic calorimeter is also considered. All results obtained are compared …
Two-Stepping Into The Icehouse: East Antarctic Weathering During Progressive Ice-Sheet Expansion At The Eocene–Oligocene Transition, Howie Scher, Steven M. Bohaty, James C. Zachos, Margaret L. Delaney
Two-Stepping Into The Icehouse: East Antarctic Weathering During Progressive Ice-Sheet Expansion At The Eocene–Oligocene Transition, Howie Scher, Steven M. Bohaty, James C. Zachos, Margaret L. Delaney
Faculty Publications
In conjunction with increasing benthic foraminiferal 18O values at the Eocene–Oligocenetransition (EOT; ca. 34 Ma), coarse-grained ice-rafted debris (IRD; >425 μm) appearsabruptly alongside fossil fi sh teeth with continentally derived neodymium (Nd) isotope ratios( Nd) in Kerguelen Plateau (Southern Ocean) sediments. Increased Antarctic weathering fl ux,as inferred from two steps to less radiogenic Nd values, coincides with two steps in benthicforaminiferal 18O values. These results indicate that two distinct surges of weathering weregenerated by East Antarctic ice growth during the EOT. Weathering by ice sheets during aprecursor glaciation at 33.9 Ma did not produce signifi cant IRD accumulation during the …
Electrospinning Fabrication, Structural And Mechanical Characterization Of Rod-Like Virus-Based Composite Nanofibers, Laying Wu, Jianfeng Zang, L. Andrew Lee, Zhongwei Niu, Gary C. Horvatha, Vaughn Braxtona, Arief C. Wibowo, Michael A. Bruckman, Soumitra Ghoshroy, Hans-Conrad Zur Loye, Xiaodong Li, Qian Wang
Electrospinning Fabrication, Structural And Mechanical Characterization Of Rod-Like Virus-Based Composite Nanofibers, Laying Wu, Jianfeng Zang, L. Andrew Lee, Zhongwei Niu, Gary C. Horvatha, Vaughn Braxtona, Arief C. Wibowo, Michael A. Bruckman, Soumitra Ghoshroy, Hans-Conrad Zur Loye, Xiaodong Li, Qian Wang
Faculty Publications
Tobacco mosaic virus (TMV) was electrospun with polyvinyl alcohol (PVA) into continuous TMV–PVA composite nanofibers to form a biodegradable nonwoven fibrous mat as an extracellular matrix (ECM) mimetic. Morphological characterizations by electron microscopyshowed that the addition of varying amounts of TMV resulted in homogeneous nanofibers without phase separation and did not change the diameter of the composite nanofibers. The orientation of TMV in as-spun fibers could be readily controlled and post-processing of the nonwoven TMV–PVA mat significantly improved its water resistance. In addition, tensile tests were performed on individual nanofibers, which revealed that the TMV–PVA composite nanofibers achieved a comparable …
Parametric Resonance Enhancement In Neutron Interferometry And Application For The Search For Non-Newtonian Gravity, Vladimir Gudkov, Hirohiko M. Shimizu, Geoffrey L. Greene
Parametric Resonance Enhancement In Neutron Interferometry And Application For The Search For Non-Newtonian Gravity, Vladimir Gudkov, Hirohiko M. Shimizu, Geoffrey L. Greene
Faculty Publications
The parametric resonance enhancement of the phase of neutrons due to non-Newtonian anomalous gravitationis considered. The existence of such resonances is confirmed by numerical calculations. A possible experimentalscheme for observing this effect is discussed based on an existing neutron interferometer design.
Detecting Toxic Diatom Blooms From Ocean Color And A Regional Ocean Model, Clarissa R. Anderson, Raphael M. Kudela, Claudia R. Benitez-Nelson, Emily Sekula-Wood, Christopher T. Burrell, Yi Chao, Gregg Langlois, Jo Goodman, David A. Siegel
Detecting Toxic Diatom Blooms From Ocean Color And A Regional Ocean Model, Clarissa R. Anderson, Raphael M. Kudela, Claudia R. Benitez-Nelson, Emily Sekula-Wood, Christopher T. Burrell, Yi Chao, Gregg Langlois, Jo Goodman, David A. Siegel
Faculty Publications
[1] An apparent link between upwelling‐related physical signatures, macronutrients, and toxic diatom blooms in the various “hotspots” throughout California has motivated attempts to forecast harmful algal blooms (HABs) as a function of select environmental variables. Empirical models for predicting toxic Pseudo‐nitzschia blooms in one such region, the Santa Barbara Channel (SBC), are tested in a nowcast mode using predictions based on merging data from MODIS ocean color geophysical products and the Regional Ocean Modeling System (ROMS) applied to the Southern California Bight. Thresholds for each model generate event forecasts. Spatially‐explicit, monthly HAB maps are compared to shipboard observations and California …
Limits On The Time Variation Of The Fermi Constant G_F Based On Type Ia Supernova Observations, Alejandro Ferrero, Brett David Altschul
Limits On The Time Variation Of The Fermi Constant G_F Based On Type Ia Supernova Observations, Alejandro Ferrero, Brett David Altschul
Faculty Publications
The light curve of a type Ia supernova decays at a rate set by the beta-decay lifetimes of the 56N iand Co56 produced in the explosion. This makes such a light curve sensitive to the value of the Fermi constant GF at the time of the supernova. Using data from the CfA Supernova Archive, we measure the dependence of the light curve decay rate on redshift and place a bound on the time variation of GF of |(dG_F/dt)/G_F| < 10-9 / y1.
Parity Violation In Low-Energy Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Parity Violation In Low-Energy Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Faculty Publications
Parity-violating effects for low-energy elastic neutron deuteron scattering are calculated for Desplanques,Donoghue, and Holstein (DDH) and effective field theory types of weak potentials in a distorted-wave Bornapproximation, using realistic hadronic strong interaction wave functions, obtained by solving three-bodyFaddeev equations in configuration space. The resulting relation between physical observables and low-energyconstants can be used to fix low-energy constants from experiments. Potential model dependencies ofparity-violating effects are discussed.
Explicit Constructions Of Rip Matrices And Related Problems, Jean Bourgain, S J. Dilworth, Kevin Ford, Sergei Konyagin, Denka Kutzarova
Explicit Constructions Of Rip Matrices And Related Problems, Jean Bourgain, S J. Dilworth, Kevin Ford, Sergei Konyagin, Denka Kutzarova
Faculty Publications
We give a new explicit construction of n×N matrices satisfying the Restricted Isometry Property (RIP). Namely, for someε > 0, largeN, and any n satisfyingN1−ε ≤ n ≤ N, we construct RIP matrices of order k ≥ n1/2+ε and constant δ = n−ε. This overcomesthe natural barrier k = O(n1/2) for proofs based on small coherence, which areused in all previous explicit constructions of RIP matrices. Key ingredients in ourproof are new estimates for sumsets in product sets and for exponential sums with theproducts of sets possessing special additive structure. We also give a construction ofsets of n complex numbers whose …
Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason R. Hattrick-Simpers, Wilbur S. Hurst, Sesha S. Srinivasan, James E. Maslar
Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason R. Hattrick-Simpers, Wilbur S. Hurst, Sesha S. Srinivasan, James E. Maslar
Faculty Publications
An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storagematerials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element …
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Cheettu Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Cheettu Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden
Faculty Publications
The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO3 to a non-Sr-deficient phase …