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2017

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Full-Text Articles in Physics

Magnetocrystalline Anisotropy Of "-Fe2o3, Imran Ahamed, Rohilt Pathak, Arti Kashyap Dec 2017

Magnetocrystalline Anisotropy Of "-Fe2o3, Imran Ahamed, Rohilt Pathak, Arti Kashyap

Faculty Publications from Nebraska Center for Materials and Nanoscience

The epsilon Fe2O3 phase of iron oxide has been studied to understand the spin structure and the magnetocrystalline anisotropy in the bulk and in thin films of "-Fe2O3 and Co-doped "-Fe2O3. The preferential magnetization direction in the nanoparticles of "-Fe2O3 is along the a-axis [M. Gich et al., Chem. Mater. 18, 3889 (2006)]. Compared to the bulk band gap of 1.9 eV, the thin-film band gap is reduced to 1.3 eV in the Co-free films and to 0.7 eV in the film with partial ...


Measurement Of The Helicity Asymmetry E In ΩΠ+ΠΠ0 Photoproduction, Z. Akbar, P. Roy, S. Park, V. Crede, A. V. Anisovich, I. Denisenko, E. Klempt, V. A. Nikonov, A. V. Sarantsev, K. P. Adhikari, S. Adhikari, M. J. Amaryan, S. Anefalos Pereira, H. Avakian, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, S. Boiarinov, W. J. Briscoe, J. Brock, W. K. Brooks, V. D. Burkert, F. T. Cao, C. Carlin, D. S. Carman, A. Celentano, G. Charles, T. Chetry, G. Ciullo, Wesley P. Gohn Dec 2017

Measurement Of The Helicity Asymmetry E In Ω → Π+Π−Π0 Photoproduction, Z. Akbar, P. Roy, S. Park, V. Crede, A. V. Anisovich, I. Denisenko, E. Klempt, V. A. Nikonov, A. V. Sarantsev, K. P. Adhikari, S. Adhikari, M. J. Amaryan, S. Anefalos Pereira, H. Avakian, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, S. Boiarinov, W. J. Briscoe, J. Brock, W. K. Brooks, V. D. Burkert, F. T. Cao, C. Carlin, D. S. Carman, A. Celentano, G. Charles, T. Chetry, G. Ciullo, Wesley P. Gohn

Physics and Astronomy Faculty Publications

The double-polarization observable E was studied for the reaction γp using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, ωπ+ππ0, using a circularly polarized tagged-photon beam with energies ranging from the ω threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the 3/2+ partial wave near threshold, which is identified with the subthreshold N(1720)3/2 ...


Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver Anderson, Matthew Kramer, Wei Tang, Jeff Shield, David J. Sellmyer Dec 2017

Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver Anderson, Matthew Kramer, Wei Tang, Jeff Shield, David J. Sellmyer

Faculty Publications from Nebraska Center for Materials and Nanoscience

The effect of Y addition and magnetic field on texture and magnetic properties of arc-melted alnico 9 magnets has been investigated. Small additions of Y (1.5 wt.%) develop a (200) texture for the arc-melted alnico 9 magnet. Such a texture is hard to form in cast samples. To achieve this goal, we set up a high-field annealing system with a maximum operation temperature of 12500 C. This system enabled annealing in a field of 45 kOe with subsequent draw annealing for the solutionized buttons; we have been able to substantially increase remanence ratio and coercivity, from 0.70 ...


Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver E. Anderson, Matthew J. Kramer, Wei Tang, Jeff Shield, David J. Sellmyer Dec 2017

Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver E. Anderson, Matthew J. Kramer, Wei Tang, Jeff Shield, David J. Sellmyer

Ames Laboratory Accepted Manuscripts

The effect of Y addition and magnetic field on texture and magnetic properties of arc-melted alnico 9 magnets has been investigated. Small additions of Y (1.5 wt.%) develop a (200) texture for the arc-melted alnico 9 magnet. Such a texture is hard to form in cast samples. To achieve this goal, we set up a high-field annealing system with a maximum operation temperature of 1250 °C. This system enabled annealing in a field of 45 kOe with subsequent draw annealing for the solutionized buttons; we have been able to substantially increase remanence ratio and coercivity, from 0.70 and ...


Emergent Ising Degrees Of Freedom Above A Double-Stripe Magnetic Ground State, Guanghua Zhang, Rebecca Flint Dec 2017

Emergent Ising Degrees Of Freedom Above A Double-Stripe Magnetic Ground State, Guanghua Zhang, Rebecca Flint

Ames Laboratory Accepted Manuscripts

Double-stripe magnetism [ Q = ( π / 2 , π / 2 ) ] has been proposed as the magnetic ground state for both the iron-telluride and BaTi 2 Sb 2 O families of superconductors. Double-stripe order is captured within a J 1 − J 2 − J 3 Heisenberg model in the regime J 3 ≫ J 2 ≫ J 1 . Intriguingly, besides breaking spin-rotational symmetry, the ground-state manifold has three additional Ising degrees of freedom associated with bond ordering. Via their coupling to the lattice, they give rise to an orthorhombic distortion and to two nonuniform lattice distortions with wave vector ( π , π ) . Because the ground state is fourfold ...


Prediction Of A Mobile Two-Dimensional Electron Gas At The Lasco3/Basno3(001) Interface, Tula R. Paudel, Evgeny Y. Tsymbal Dec 2017

Prediction Of A Mobile Two-Dimensional Electron Gas At The Lasco3/Basno3(001) Interface, Tula R. Paudel, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

Two-dimensional electron gases (2DEG) at oxide interfaces, such as LaAlO3/SrTiO3 (001), have aroused significant interest due to their high carrier density (∼1014 cm−2) and strong lateral confinement (∼1 nm). However, these 2DEGs are normally hosted by the weakly dispersive and degenerate d bands (e.g., Ti-3d bands), which are strongly coupled to the lattice, causing mobility of such 2DEGs to be relatively low at room temperature (∼1 cm2/Vs). Here, we propose using oxide host materials with the conduction bands formed from s electrons to increase carrier mobility and soften its temperature dependence. Using ...


Low Frequency Electromagnetic Radiation From Gravitational Waves Generated By Neutron Stars, Preston Jones, Andri Gretarsson, Douglas Singleton Dec 2017

Low Frequency Electromagnetic Radiation From Gravitational Waves Generated By Neutron Stars, Preston Jones, Andri Gretarsson, Douglas Singleton

Publications

We investigate the possibility of observing very low frequency (VLF) electromagnetic radiation produced from the vacuum by gravitational waves. We review the calculations leading to the possibility of vacuum conversion of gravitational waves into electromagnetic waves and show how this process evades the well-known prohibition against particle production from gravitational waves. Using Newman-Penrose scalars, we estimate the luminosity of this proposed electromagnetic counterpart radiation coming from gravitational waves produced by neutron star oscillations. The detection of electromagnetic counterpart radiation would provide an indirect way of observing gravitational radiation with future spacecraft missions, especially lunar orbiting probes.


Extraction Of The Neutron Electric Form Factor From Measurements Of Inclusive Double Spin Asymmetries, V. Sulkosky, G. Jin, E. Long, Y. -W. Zhang, M. Mihovilovic, A. Kelleher, B. Anderson, D. W. Higinbotham, S. Širca, K. Allada, J. R. M. Annand, T. Averett, W. Bertozzi, W. Boeglin, P. Bradshaw, A. Camsonne, M. Canan, G. D. Cates, C. Chen, J. -P. Chen, E. Chudakov, R. De Leo, X. Deng, A. Deur, C. Dutta, L. El Fassi, D. Flay, S. Frullani, F. Garibaldi, Wolfgang Korsch Dec 2017

Extraction Of The Neutron Electric Form Factor From Measurements Of Inclusive Double Spin Asymmetries, V. Sulkosky, G. Jin, E. Long, Y. -W. Zhang, M. Mihovilovic, A. Kelleher, B. Anderson, D. W. Higinbotham, S. Širca, K. Allada, J. R. M. Annand, T. Averett, W. Bertozzi, W. Boeglin, P. Bradshaw, A. Camsonne, M. Canan, G. D. Cates, C. Chen, J. -P. Chen, E. Chudakov, R. De Leo, X. Deng, A. Deur, C. Dutta, L. El Fassi, D. Flay, S. Frullani, F. Garibaldi, Wolfgang Korsch

Physics and Astronomy Faculty Publications

Background: Measurements of the neutron charge form factor, GnE, are challenging because the neutron has no net charge. In addition, measurements of the neutron form factors must use nuclear targets which require accurately accounting for nuclear effects. Extracting GnE with different targets and techniques provides an important test of our handling of these effects.

Purpose: The goal of the measurement was to use an inclusive asymmetry measurement technique to extract the neutron charge form factor at a four-momentum transfer of 1 (GeV/c)2. This technique has very different systematic uncertainties than traditional exclusive measurements and ...


Origin Of The Exciton Mass In The Frustrated Mott Insulator Na2Iro3, Zhanybek Alpichshev, Edbert J. Sie, Fahad Mahmood, Gang Cao, Nuh Gedik Dec 2017

Origin Of The Exciton Mass In The Frustrated Mott Insulator Na2Iro3, Zhanybek Alpichshev, Edbert J. Sie, Fahad Mahmood, Gang Cao, Nuh Gedik

Physics and Astronomy Faculty Publications

We use a three-pulse ultrafast optical spectroscopy to study the relaxation processes in a frustrated Mott insulator Na2IrO3. By being able to independently produce the out-of-equilibrium bound states (excitons) of doublons and holons with the first pulse and suppress the underlying antiferromagnetic order with the second one, we were able to elucidate the relaxation mechanism of quasiparticles in this system. By observing the difference in the exciton dynamics in the magnetically ordered and disordered phases we found that the mass of this quasiparticle is mostly determined by its interaction with the surrounding spins.


Influence Of Classical Anisotropy Fields On The Properties Of Heisenberg Antiferromagnets Within Unified Molecular Field Theory, David C. Johnston Dec 2017

Influence Of Classical Anisotropy Fields On The Properties Of Heisenberg Antiferromagnets Within Unified Molecular Field Theory, David C. Johnston

Ames Laboratory Accepted Manuscripts

A comprehensive study of the influence of classical anisotropy fields on the magnetic properties of Heisenberg antiferromagnets within unified molecular field theory versus temperature T , magnetic field H , and anisotropy field parameter h A 1 is presented for systems comprised of identical crystallographically-equivalent local moments. The anisotropy field for collinear z -axis antiferromagnetic (AFM) ordering is constructed so that it is aligned in the direction of each ordered and/or field-induced thermal-average moment with a magnitude proportional to the moment, whereas that for XY anisotropy is defined to be in the direction of the projection of the moment onto the ...


R14(Au, M)51 (R = Y, La−Nd, Sm−Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In,Sn, Sb, Bi): Stability Ranges And Site Preference In The Gd14ag51 Structure Type, Chris Celania, Volodymyr Smetana, Alessia Provino, Pietro Manfrinetti, Anja-Verena Mudring Dec 2017

R14(Au, M)51 (R = Y, La−Nd, Sm−Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In,Sn, Sb, Bi): Stability Ranges And Site Preference In The Gd14ag51 Structure Type, Chris Celania, Volodymyr Smetana, Alessia Provino, Pietro Manfrinetti, Anja-Verena Mudring

Ames Laboratory Accepted Manuscripts

Twenty new ternary representatives of the Gd14Ag51 structure type have been synthesized within the R-Au-M family (R = Y, La–Nd, Sm–Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In, Sn, Sb, Bi) using solid state synthesis techniques. The list of post transition metals (M) involved in the formation of this type of structure could be augmented by five new representatives. All compounds crystallize in the hexagonal space group P6/m (#175) with the unit cell ranges of a = 12.3136(2)–12.918(1) Å and c = 8.9967(3)–9.385(1) Å, and incorporate different ...


Spin-Valley Coherent Phases Of The V = 0 Quantum Hall State In Bilayer Graphene, Ganpathy Murthy, Efrat Shimshoni, H. A. Fertig Dec 2017

Spin-Valley Coherent Phases Of The V = 0 Quantum Hall State In Bilayer Graphene, Ganpathy Murthy, Efrat Shimshoni, H. A. Fertig

Physics and Astronomy Faculty Publications

Bilayer graphene (BLG) offers a rich platform for broken-symmetry states stabilized by interactions. In this work, we study the phase diagram of BLG in the quantum Hall regime at filling factor ν = 0 within the Hartree-Fock approximation. In the simplest noninteracting situation, this system has eight (nearly) degenerate Landau levels near the Fermi energy, characterized by spin, valley, and orbital quantum numbers. We incorporate in our study two effects not previously considered: (i) the nonperturbative effect of trigonal warping in the single-particle Hamiltonian, and (ii) short-range SU(4) symmetry-breaking interactions that distinguish the energetics of the orbitals. We find within ...


Local Nematic Susceptibility In Stressed Bafe 2 As 2 From Nmr Electric Field Gradient Measurements, T. Kissikov, R. Sarkar, M. Lawson, B. T. Bush, Erik I. Timmons, Makariy A. Tanatar, Ruslan Prozorov, S. L. Bud’Ko, Paul C. Canfield, R. M. Fernandes, W. F. Goh, W. E. Pickett, N. J. Curro Dec 2017

Local Nematic Susceptibility In Stressed Bafe 2 As 2 From Nmr Electric Field Gradient Measurements, T. Kissikov, R. Sarkar, M. Lawson, B. T. Bush, Erik I. Timmons, Makariy A. Tanatar, Ruslan Prozorov, S. L. Bud’Ko, Paul C. Canfield, R. M. Fernandes, W. F. Goh, W. E. Pickett, N. J. Curro

Ames Laboratory Accepted Manuscripts

The electric field gradient (EFG) tensor at the 75As site couples to the orbital occupations of the As porbitals and is a sensitive probe of local nematicity in BaFe2As2. We use nuclear magnetic resonance to measure the nuclear quadrupolar splittings and find that the EFG asymmetry responds linearly to the presence of a strain field in the paramagnetic phase. We extract the nematic susceptibility from the slope of this linear response as a function of temperature and find that it diverges near the structural transition, in agreement with other measures of the bulk nematic susceptibility. Our work establishes an alternative ...


First-Principles Study On The Electronic, Optical, And Transport Properties Of Monolayer Α- And Β-Gese, Yuanfeng Xu, Hao Zhang, Hezhu Shao, Gang Ni, Jing Li, Hongliang Lu, Rongjun Zhang, Bo Peng, Yongyuan Zhu, Heyuan Zhu, Costas M. Soukoulis Dec 2017

First-Principles Study On The Electronic, Optical, And Transport Properties Of Monolayer Α- And Β-Gese, Yuanfeng Xu, Hao Zhang, Hezhu Shao, Gang Ni, Jing Li, Hongliang Lu, Rongjun Zhang, Bo Peng, Yongyuan Zhu, Heyuan Zhu, Costas M. Soukoulis

Ames Laboratory Accepted Manuscripts

The extraordinary properties and the novel applications of black phosphorene induce the research interest in the monolayer group-IV monochalcogenides. Here using first-principles calculations, we systematically investigate the electronic, transport, and optical properties of monolayer alpha- and beta-GeSe, revealing a direct band gap of 1.61 eV for monolayer alpha-GeSe and an indirect band gap of 2.47 eV for monolayer beta-GeSe. For monolayer beta-GeSe, the electronic/hole transport is anisotropic, with an extremely high electron mobility of 2.93 x 10(4) cm(2)/Vs along the armchair direction, comparable to that of black phosphorene. Furthermore, for beta-GeSe, robust band ...


Nematicity, Magnetism And Superconductivity In Fese, Anna E. Böhmer, Andreas Kreisel Dec 2017

Nematicity, Magnetism And Superconductivity In Fese, Anna E. Böhmer, Andreas Kreisel

Ames Laboratory Accepted Manuscripts

Iron-based superconductors are well known for their complex interplay between structure, magnetism and superconductivity. FeSe offers a particularly fascinating example. This material has been intensely discussed because of its extended nematic phase, whose relationship with magnetism is not obvious. Superconductivity in FeSe is highly tunable, with the superconducting transition temperature, T c, ranging from 8 K in bulk single crystals at ambient pressure to almost 40 K under pressure or in intercalated systems, and to even higher temperatures in thin films. In this topical review, we present an overview of nematicity, magnetism and superconductivity, and discuss the interplay of these ...


Diffusion Of Two-Dimensional Epitaxial Clusters On Metal (100) Surfaces: Facile Versus Nucleation-Mediated Behavior And Their Merging For Larger Sizes, King C. Lai, Da-Jiang Liu, James W. Evans Dec 2017

Diffusion Of Two-Dimensional Epitaxial Clusters On Metal (100) Surfaces: Facile Versus Nucleation-Mediated Behavior And Their Merging For Larger Sizes, King C. Lai, Da-Jiang Liu, James W. Evans

Ames Laboratory Accepted Manuscripts

For diffusion of two-dimensional homoepitaxial clusters of N atoms on metal (100) surfaces mediated by edge atom hopping, macroscale continuum theory suggests that the diffusion coefficient scales like DN∼N−β with β=3/2. However, we find quite different and diverse behavior in multiple size regimes. These include: (i) facile diffusion for small sizes N<9; (ii) slow nucleation-mediated diffusion with small β<1 for “perfect” sizes N=Np=L2 or L(L+1), for L=3,4, ... having unique ground-state shapes, for moderate sizes 9≤N≤O(102); the same also applies for N=Np+3, Np+4, ...(iii) facile diffusion but with large β>2 for N=Np+1 and Np+2 also for moderate sizes 9≤N≤O(102); (iv) merging of the above distinct branches and subsequent anomalous scaling with 1≲β<3/2, reflecting the quasifacetted structure of clusters, for larger N=O(102) to N=O(103); (v) classic scaling with β=3/2 for very large N=O(103) and above. The specified size ranges apply for typical model parameters. We focus on the moderate size regime where we show that diffusivity cycles quasiperiodically from the slowest branch for Np+3 (not Np) to the fastest branch for Np+1. Behavior is quantified by kinetic Monte Carlo simulation of an appropriate stochastic lattice-gas model. However, precise analysis must account for a strong enhancement of diffusivity for short time increments due to back correlation in the cluster motion. Further understanding of this enhancement, of anomalous size scaling behavior, and of the merging of various branches, is facilitated by combinatorial analysis of the number of the ground-state and low-lying excited state cluster configurations, and also of kink populations.


Similar Ultrafast Dynamics Of Several Dissimilar Dirac And Weyl Semimetals, Christopher P. Weber, Bryan S. Berggren, Madison G. Masten, Thomas C. Ogloza, Skylar Deckoff-Jones, Julien Madéo, Michael K. L. Man, Keshav M. Dani, Lingxiao Zhao, Genfu Chen, Jinyu Liu, Zhiqiang Mao, Leslie M. Schoop, Bettina V. Lotsch, Stuart S. P. Parkin, Mazhar Ali Dec 2017

Similar Ultrafast Dynamics Of Several Dissimilar Dirac And Weyl Semimetals, Christopher P. Weber, Bryan S. Berggren, Madison G. Masten, Thomas C. Ogloza, Skylar Deckoff-Jones, Julien Madéo, Michael K. L. Man, Keshav M. Dani, Lingxiao Zhao, Genfu Chen, Jinyu Liu, Zhiqiang Mao, Leslie M. Schoop, Bettina V. Lotsch, Stuart S. P. Parkin, Mazhar Ali

Physics

Recent years have seen the rapid discovery of solids whose low-energy electrons have a massless, linear dispersion, such as Weyl, line-node, and Dirac semimetals. The remarkable optical properties predicted in these materials show their versatile potential for optoelectronic uses. However, little is known of their response in the picoseconds after absorbing a photon. Here, we measure the ultrafast dynamics of four materials that share non-trivial band structure topology but that differ chemically, structurally, and in their low-energy band structures: ZrSiS, which hosts a Dirac line node and Dirac points; TaAs and NbP, which are Weyl semimetals; and Sr1–y ...


Ionic Depletion At The Crystalline Gibbs Layer Of Peg-Capped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin Dec 2017

Ionic Depletion At The Crystalline Gibbs Layer Of Peg-Capped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin

Ames Laboratory Accepted Manuscripts

In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolated-polyethylene-glycol–capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs2SO4) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray scattering. By taking advantage of element specificity with the GIXFS method, we find that the cation Cs+ concentration at the crystalline film is significantly reduced in parts of the PEG-AuNP film compared with that ...


Sdss-Iv Manga: Probing The Kinematic Morphology–Density Relation Of Early-Type Galaxies With Manga, J. E. Greene, A. Leauthaud, E. Emsellem, D. Goddard, J. Ge, B. H. Andrews, J. Brinkman, J. R. Brownstein, J. Greco, D. Law, Y. -T. Lin, K. L. Masters, M. Merrifield, S. More, N. Okabe, D. P. Schneider, D. Thomas, D. A. Wake, Renbin Yan, N. Drory Dec 2017

Sdss-Iv Manga: Probing The Kinematic Morphology–Density Relation Of Early-Type Galaxies With Manga, J. E. Greene, A. Leauthaud, E. Emsellem, D. Goddard, J. Ge, B. H. Andrews, J. Brinkman, J. R. Brownstein, J. Greco, D. Law, Y. -T. Lin, K. L. Masters, M. Merrifield, S. More, N. Okabe, D. P. Schneider, D. Thomas, D. A. Wake, Renbin Yan, N. Drory

Physics and Astronomy Faculty Publications

The "kinematic" morphology–density relation for early-type galaxies posits that those galaxies with low angular momentum are preferentially found in the highest-density regions of the universe. We use a large sample of galaxy groups with halo masses 1012.5 < Mhalo < 1014.5 h-1 M observed with the Mapping Nearby Galaxies at APO (MaNGA) survey to examine whether there is a correlation between local environment and rotational support that is independent of stellar mass. We find no compelling evidence for a relationship between the angular momentum content of early-type galaxies and either local overdensity or radial position within ...


Guidelines On Experimental Methods To Assess Mitochondrial Dysfunction In Cellular Models Of Neurodegenerative Diseases., Niamh M. Connolly, Pierre Theurey, Vera Adam-Vizi, Nicolas G. Bazan, Paolo Bernardi, Juan P. Bolaños, Carsten Culmsee, Valina L. Dawson, Mohanish Deshmukh, Michael R. Duchen, Heiko Düssmann, Gary Fiskum, Maria F. Galindo, Giles E. Hardingham, J Marie Hardwick, Mika B. Jekabsons, Elizabeth A. Jonas, Joaquin Jordán, Stuart A. Lipton, Giovanni Manfredi, Mark P. Mattson, Bethann Mclaughlin, Axel Methner, Anne N. Murphy, Michael P. Murphy, David G. Nicholls, Brian M. Polster, Tullio Pozzan, Rosario Rizzuto, Jorgina Satrústegui, Ruth S. Slack, Raymond A. Swanson, Russell H. Swerdlow, Yvonne Will, Zheng Ying, Alvin Joselin, Anna Gioran, Catarina Moreira Pinho, Orla Watters, Manuela Salvucci, Irene Llorente-Folch, David S. Park, Daniele Bano, Maria Ankarcrona, Paola Pizzo, Jochen Hm Prehn Dec 2017

Guidelines On Experimental Methods To Assess Mitochondrial Dysfunction In Cellular Models Of Neurodegenerative Diseases., Niamh M. Connolly, Pierre Theurey, Vera Adam-Vizi, Nicolas G. Bazan, Paolo Bernardi, Juan P. Bolaños, Carsten Culmsee, Valina L. Dawson, Mohanish Deshmukh, Michael R. Duchen, Heiko Düssmann, Gary Fiskum, Maria F. Galindo, Giles E. Hardingham, J Marie Hardwick, Mika B. Jekabsons, Elizabeth A. Jonas, Joaquin Jordán, Stuart A. Lipton, Giovanni Manfredi, Mark P. Mattson, Bethann Mclaughlin, Axel Methner, Anne N. Murphy, Michael P. Murphy, David G. Nicholls, Brian M. Polster, Tullio Pozzan, Rosario Rizzuto, Jorgina Satrústegui, Ruth S. Slack, Raymond A. Swanson, Russell H. Swerdlow, Yvonne Will, Zheng Ying, Alvin Joselin, Anna Gioran, Catarina Moreira Pinho, Orla Watters, Manuela Salvucci, Irene Llorente-Folch, David S. Park, Daniele Bano, Maria Ankarcrona, Paola Pizzo, Jochen Hm Prehn

Physiology and Medical Physics Articles

Neurodegenerative diseases are a spectrum of chronic, debilitating disorders characterised by the progressive degeneration and death of neurons. Mitochondrial dysfunction has been implicated in most neurodegenerative diseases, but in many instances it is unclear whether such dysfunction is a cause or an effect of the underlying pathology, and whether it represents a viable therapeutic target. It is therefore imperative to utilise and optimise cellular models and experimental techniques appropriate to determine the contribution of mitochondrial dysfunction to neurodegenerative disease phenotypes. In this consensus article, we collate details on and discuss pitfalls of existing experimental approaches to assess mitochondrial function in ...


Sdss-Iv Manga: Spatially Resolved Star Formation Main Sequence And Li(N)Er Sequence, B. C. Hsieh, Lihwai Lin, J. H. Lin, H. A. Pan, C. H. Hsu, S. F. Sánchez, M. Cano-Díaz, Kai Zhang, Renbin Yan, J. K. Barrera-Ballesteros, M. Boquien, R. Riffel, J. Brownstein, I. Cruz-González, A. Hagen, H. Ibarra, K. Pan, D. Bizyaev, D. Oravetz, A. Simmons Dec 2017

Sdss-Iv Manga: Spatially Resolved Star Formation Main Sequence And Li(N)Er Sequence, B. C. Hsieh, Lihwai Lin, J. H. Lin, H. A. Pan, C. H. Hsu, S. F. Sánchez, M. Cano-Díaz, Kai Zhang, Renbin Yan, J. K. Barrera-Ballesteros, M. Boquien, R. Riffel, J. Brownstein, I. Cruz-González, A. Hagen, H. Ibarra, K. Pan, D. Bizyaev, D. Oravetz, A. Simmons

Physics and Astronomy Faculty Publications

We present our study on the spatially resolved Hα and M* relation for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We show that the star formation rate surface density (ΣSFR), derived based on the Hα emissions, is strongly correlated with the M* surface density (Σ*) on kiloparsec scales for star-forming galaxies and can be directly connected to the global star-forming sequence. This suggests that the global main sequence may be a consequence of a more fundamental relation on small scales. On the other hand, our result suggests that ~20% of quiescent galaxies in ...


Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara Dec 2017

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara

Physics and Astronomy Faculty Publications

The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts ...


Photoelectron Angular Distributions From Rotationally Resolved Autoionizing States Of N2, Alexander M. Chartrand, Elizabeth F. Mccormack, Ugo Jacovella, David M P Holland, Berenger Gans, Xiaofeng Tang, Gustavo A. García, Laurent Nahon, Stephen T. Pratt Dec 2017

Photoelectron Angular Distributions From Rotationally Resolved Autoionizing States Of N2, Alexander M. Chartrand, Elizabeth F. Mccormack, Ugo Jacovella, David M P Holland, Berenger Gans, Xiaofeng Tang, Gustavo A. García, Laurent Nahon, Stephen T. Pratt

Physics Faculty Research and Scholarship

The single-photon, photoelectron-photoion coincidence spectrum of N2 has been recorded at high (~1.5 cm–1 ) resolution in the region between the N2+ X 2Σg+, v+ = 0 and 1 ionization thresholds by using a double-imaging spectrometer and intense vacuum-ultraviolet light from the Synchrotron SOLEIL. This approach provides the relative photoionization cross section, the photoelectron energy distribution, and the photoelectron angular distribution as a function of photon energy. The region of interest contains autoionizing valence states, vibrationally autoionizing Rydberg states converging to vibrationally excited levels of the N2+ X 2Σg+ ground state, and electronically ...


An Investigation Of The Alkali Metals In The Fcc Structure Using An Embedded-Atom-Method (Eam) Model, Marcus Jackman Dec 2017

An Investigation Of The Alkali Metals In The Fcc Structure Using An Embedded-Atom-Method (Eam) Model, Marcus Jackman

Physics Capstone Project

Embedded-atom-method models have been used in the calculation and prediction of many vibrational and thermal properties of materials. In 2012 Wilson and Riffe constructed a model that predicts dispersion relations and frequency-moment Debye temperatures of the alkali metals with a greater degree of accuracy than previous models. The Wilson-Riffe model was implemented using MATLAB code. Here that model is extended to model alkali metals in the close-packed fcc structure. Code development is discussed, and results are presented for dispersion relations, density of states, Debye temperatures and free energy. The vibrational free energy combined with a suitable constant representing the electronic ...


Demonstration Of Ultra-High Recyclable Energy Densities In Domain-Engineered Ferroelectric Films, Hongbo Cheng, Jun Ouyang, Yun-Xiang Zhang, David J. Ascienzo, Yao Li, Yu-Yao Zhao, Yuhang Ren Dec 2017

Demonstration Of Ultra-High Recyclable Energy Densities In Domain-Engineered Ferroelectric Films, Hongbo Cheng, Jun Ouyang, Yun-Xiang Zhang, David J. Ascienzo, Yao Li, Yu-Yao Zhao, Yuhang Ren

Publications and Research

Dielectric capacitors have the highest charge/discharge speed among all electrical energy devices, but lag behind in energy density. Here we report dielectric ultracapacitors based on ferroelectric films of Ba(Zr0.2,Ti0.8)O3 which display high-energy densities (up to 166 J cm–3) and efficiencies (up to 96%). Different from a typical ferroelectric whose electric polarization is easily saturated, these Ba(Zr0.2,Ti0.8)O3 films display a much delayed saturation of the electric polarization, which increases continuously from nearly zero at remnant in a multipolar state, to a large value under the maximum electric field, leading ...


Interaction-Free Effects Between Distant Atoms, Yakir Aharonov, Eliahu Cohen, Avshalom C. Elitzur, Lee Smolin Dec 2017

Interaction-Free Effects Between Distant Atoms, Yakir Aharonov, Eliahu Cohen, Avshalom C. Elitzur, Lee Smolin

Mathematics, Physics, and Computer Science Faculty Articles and Research

A Gedanken experiment is presented where an excited and a ground-state atom are positioned such that, within the former’s half-life time, they exchange a photonwith 50% probability.Ameasurement of their energy statewill therefore indicate in 50% of the cases that no photon was exchanged. Yet other measurements would reveal that, by the mere possibility of exchange, the two atoms have become entangled. Consequently, the “no exchange” result, apparently precluding entanglement, is non-locally established between the atoms by this very entanglement. This quantum-mechanical version of the ancient Liar Paradox can be realized with already existing transmission schemes, with the addition ...


The 13th Data Release Of The Sloan Digital Sky Survey: First Spectroscopic Data From The Sdss-Iv Survey Mapping Nearby Galaxies At Apache Point Observatory, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Friedrich Anders, Scott Anderson, Brett H. Andrews, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud, Eric Aubourg, Vladimir Avila-Reese, Carles Badenes, Stephen Bailey, Beatriz Barbuy, Kat Barger, Jorge Barrera-Ballesteros, Curtis Bartosz, Sarbani Basu, Dominic Bates, Giuseppina Battaglia, Falk Baumgarten, Julien Baur, Julian Bautista, Timothy C. Beers, Francesco Belfiore, Matthew Bershady, Sara Bertran De Lis, Jonathan C. Bird, Dmitry Bizyaev, Guillermo A. Blanc, Renbin Yan, Kai Zhang Dec 2017

The 13th Data Release Of The Sloan Digital Sky Survey: First Spectroscopic Data From The Sdss-Iv Survey Mapping Nearby Galaxies At Apache Point Observatory, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Friedrich Anders, Scott Anderson, Brett H. Andrews, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud, Eric Aubourg, Vladimir Avila-Reese, Carles Badenes, Stephen Bailey, Beatriz Barbuy, Kat Barger, Jorge Barrera-Ballesteros, Curtis Bartosz, Sarbani Basu, Dominic Bates, Giuseppina Battaglia, Falk Baumgarten, Julien Baur, Julian Bautista, Timothy C. Beers, Francesco Belfiore, Matthew Bershady, Sara Bertran De Lis, Jonathan C. Bird, Dmitry Bizyaev, Guillermo A. Blanc, Renbin Yan, Kai Zhang

Physics and Astronomy Faculty Publications

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. It ...


Sea Quarks Contribution To The Nucleon Magnetic Moment And Charge Radius At The Physical Point, Raza Sabbir Sufian, Yi-Bo Yang, Jian Liang, Terrence Draper, Keh-Fei Liu Dec 2017

Sea Quarks Contribution To The Nucleon Magnetic Moment And Charge Radius At The Physical Point, Raza Sabbir Sufian, Yi-Bo Yang, Jian Liang, Terrence Draper, Keh-Fei Liu

Physics and Astronomy Faculty Publications

We report a comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon magnetic moment, charge radius, and the electric and magnetic form factors. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We adopt a model-independent extrapolation of the nucleon magnetic moment and the charge radius. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light and strange disconnected-sea quarks contribution to the nucleon ...


Measuring Polarized Emission In Clusters In The Cmb S4 Era, Louis Thibaut, Emory F. Bunn, Benjamin Wandelt, Joseph Silk Dec 2017

Measuring Polarized Emission In Clusters In The Cmb S4 Era, Louis Thibaut, Emory F. Bunn, Benjamin Wandelt, Joseph Silk

Physics Faculty Publications

The next generation of CMB experiments (CMB Stage-4) will produce a Sunyaev-Zel’dovich (SZ) cluster catalog containing ∼105 objects, two orders of magnitudes more than currently available. In this paper, we discuss the detectability of the polarized signal generated by scattering of the CMB quadrupole on the cluster electron gas using this catalog. We discuss the possibility of using this signal to measure the relationship between cluster optical depth and mass. We find that the area of observation of S4 maximizes the signal-to-noise (S/N) on the polarized signal but that this S/N is extremely small for an individual ...


A Molecular Debye-Hückel Theory Of Solvation In Polar Fluids: An Extension Of The Born Model, Tiejun Xiao, Xueyu Song Dec 2017

A Molecular Debye-Hückel Theory Of Solvation In Polar Fluids: An Extension Of The Born Model, Tiejun Xiao, Xueyu Song

Ames Laboratory Accepted Manuscripts

A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of Debye-Hückel-like response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a Debye-Hückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated in ...