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Selected Works

2014

Articles 61 - 73 of 73

Full-Text Articles in Physical Sciences and Mathematics

Statistical Mechanics Of Wormlike Polymers From A New Generating Function. Ii. The Force-Elongation Relationship, Gustavo Carri Apr 2014

Statistical Mechanics Of Wormlike Polymers From A New Generating Function. Ii. The Force-Elongation Relationship, Gustavo Carri

Gustavo A. Carri

No abstract provided.

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Development Of A Rotational Stage For Operation At 4k Temperature, Thushara Perera, Huy Do, '16 Apr 2014

Development Of A Rotational Stage For Operation At 4k Temperature, Thushara Perera, Huy Do, '16

Thushara A. Perera

No abstract provided.

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Dark Matter As An Integral Part Of An Alternative Gravity Model, Hontas Farmer Apr 2014

Dark Matter As An Integral Part Of An Alternative Gravity Model, Hontas Farmer

Hontas F Farmer

The purpose of this paper is to reconcile observations of dark matter effects on the galactic and cosmological scales with the null results of astroparticle physics observations such as CDMS and ANTARES. This paper will also provide a candidate unified and simpler mathematical formulation for the Lambda CDM model. Unification is achieved by a combination of the f(R) approach, with the standard LCDM approach and inflationary models. It is postulated that dark matter-energy fields depend on the Ricci curvature R. Standard methods of classical and quantum field theory on curved space time are applied. When this model is treated as …

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Composite Fermions And Integer Partitions, Arthur Benjamin, Jennifer Quinn, John Quinn, Arkadiusz Wojs Feb 2014

Composite Fermions And Integer Partitions, Arthur Benjamin, Jennifer Quinn, John Quinn, Arkadiusz Wojs

Jennifer J. Quinn

We utilize the KOH theorem to prove the unimodality of integer partitions with at most a parts, all parts less than or equal to b, that are required to contain either repeated or consecutive parts. We connect this result to an open question in quantum physics relating the number of distinct total angular momentum multiplets of a system of N fermions, each with angular momentum ℓ, to those of a system in which each Fermion has angular momentum ℓ*=ℓ−N+1.

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The Fermion–Boson Transformation In Fractional Quantum Hall Systems, John Quinn, Arkadiusz Wojs, Jennifer Quinn, Arthur Benjamin Feb 2014

The Fermion–Boson Transformation In Fractional Quantum Hall Systems, John Quinn, Arkadiusz Wojs, Jennifer Quinn, Arthur Benjamin

Jennifer J. Quinn

A Fermion to Boson transformation is accomplished by attaching to each Fermion a single flux quantum oriented opposite to the applied magnetic field. When the mean field approximation is made in the Haldane spherical geometry, the Fermion angular momentum l_F is replaced by l_B - l_F - 1/2(N-1). The set of allowed total angular momentum multiplets is identical in the two different pictures. The Fermion and Boson energy spectra in the presence of many body interactions are identical if and only if the pseudopotential is "harmonic" in form. However, similar low energy bands of states with Laughlin correlations occur in …

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Competition Between Ferromagnetic Metallic And Paramagnetic Insulating Phases In Manganites, G. Li, H. Zhou, S. Feng, Xiaojuan Fan, X. Li, Z. Wang Feb 2014

Competition Between Ferromagnetic Metallic And Paramagnetic Insulating Phases In Manganites, G. Li, H. Zhou, S. Feng, Xiaojuan Fan, X. Li, Z. Wang

Xiaojuan Fan

La0.67Ca0.33Mn1−xCuxO3(x=0 and 0.15) epitaxial thin films were grown on the (100) LaAlO3 substrates, and the temperature dependence of their resistivity was measured in magnetic fields up to 12 T by a four-probe technique. We found that the competition between the ferromagnetic metallic (FM) and paramagnetic insulating (PI) phases plays an important role in the observed colossal magnetoresistance(CMR) effect. Based on a scenario that the doped manganites approximately consist of phase-separated FM and PI regions, a simple phenomenological model was proposed to describe the CMR effect. Using this model, we calculated the resistivity as functions of temperature and magnetic field. The …

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Polymer Gel Templating Of Free-Standing Inorganic Monoliths For Photocatalysis, Xiaojuan Fan, Honghan Fei, David Demaree, Daniel Brennan, Jessica St. John, Scott Oliver Feb 2014

Polymer Gel Templating Of Free-Standing Inorganic Monoliths For Photocatalysis, Xiaojuan Fan, Honghan Fei, David Demaree, Daniel Brennan, Jessica St. John, Scott Oliver

Xiaojuan Fan

We have developed a simple, low-cost process to fabricate free-standing porous metal oxide monoliths. Various swollen polymers and hydrogels possessing an open network structure are infiltrated with pure liquid metal alkoxide. Hydrolysis followed by chemical or thermal degradation of the polymer leads to bulk porous monoliths, TiO2 and SiO2 as initial examples. The titania solids were subsequently employed as photocatalysts under UV light and monitored for adsorption. The materials show efficient reusable photocatalytic ability as compared to pure-phase nanoparticle titanium oxide.

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Constraint-Preserving Sommerfeld Conditions For The Harmonic Einstein Equations, Maria Babiuc-Hamilton, H-O. Kreiss, Jeffrey Winicour Feb 2014

Constraint-Preserving Sommerfeld Conditions For The Harmonic Einstein Equations, Maria Babiuc-Hamilton, H-O. Kreiss, Jeffrey Winicour

Maria Babiuc-Hamilton

The principle part of Einstein equations in the harmonic gauge consists of a constrained system of 10 curved space wave equations for the components of the space-time metric. A new formulation of constraint-preserving boundary conditions of the Sommerfeld-type for such systems has recently been proposed. We implement these boundary conditions in a nonlinear 3D evolution code and test their accuracy.

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Harmonic Initial-Boundary Evolution In General Relativity, Maria Babiuc-Hamilton, B´Ela Szil´Agyi, Jeffrey Winicour Feb 2014

Harmonic Initial-Boundary Evolution In General Relativity, Maria Babiuc-Hamilton, B´Ela Szil´Agyi, Jeffrey Winicour

Maria Babiuc-Hamilton

Computational techniques which establish the stability of an evolution-boundary algorithm for a model wave equation with shift are incorporated into a well-posed version of the initial-boundary value problem for gravitational theory in harmonic coordinates. The resulting algorithm is implemented as a 3-dimensional numerical code which we demonstrate to provide stable, convergent Cauchy evolution in gauge wave and shifted gauge wave testbeds. Code performance is compared for Dirichlet, Neumann, and Sommerfeld boundary conditions and for boundary conditions which explicitly incorporate constraint preservation. The results are used to assess strategies for obtaining physically realistic boundary data by means of Cauchy-characteristic matching.

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Transport Evidence Of Robust Topological Surface State In Bitecl Single Crystals, The First Strong Inversion Asymmetric Topological Insulator, F Xiang Jan 2014

Transport Evidence Of Robust Topological Surface State In Bitecl Single Crystals, The First Strong Inversion Asymmetric Topological Insulator, F Xiang

F X Xiang

Three-dimensional (3D) topological insulators (TIs) are new forms of quantum matter that are characterized by their insulating bulk state and exotic metallic surface state, which hosts helical Dirac fermions1-2. Very recently, BiTeCl, one of the polar semiconductors, has been discovered by angle-resolved photoemission spectroscopy to be the first strong inversion asymmetric topological insulator (SIATI). In contrast to the previously discovered 3D TIs with inversion symmetry, the SIATI are expected to exhibit novel topological phenomena, including crystalline-surface-dependent topological surface states, intrinsic topological p-n junctions, and pyroelectric and topological magneto-electric effects3. Here, we report the first transport evidence for the robust topological …

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Fermi-Surface Topology And Low-Lying Electronic Structure Of The Iron-Based Superconductor Ca₁₀(Pt₃As₈)(Fe₂As₂)₅, Madhab Neupane, Chang Liu, Su-Yang Xu, Yung-Jui Wang, Ni Ni, J. Allred, N. Alidoust, Hsin Lin, R. Markiewicz, A. Bansil, R. Cava, M. Hasan Jan 2014

Fermi-Surface Topology And Low-Lying Electronic Structure Of The Iron-Based Superconductor Ca₁₀(Pt₃As₈)(Fe₂As₂)₅, Madhab Neupane, Chang Liu, Su-Yang Xu, Yung-Jui Wang, Ni Ni, J. Allred, N. Alidoust, Hsin Lin, R. Markiewicz, A. Bansil, R. Cava, M. Hasan

Hsin Lin

We report a study of low-energy electronic structure and Fermi surface topology for the recently discovered iron-based superconductor Ca₁₀(Pt₃As₈)(Fe₂As₂)₅(the 10-3-8 phase, with Tc∼8 K), via angle-resolved photoemission spectroscopy (ARPES). Despite its triclinic crystal structure, ARPES results reveal a fourfold symmetric band structure with the absence of Dirac-cone-like Fermi dots (related to magnetism) found around the Brillouin zone corners in other iron-based superconductors. Considering that the triclinic lattice and structural supercell arise from the Pt₃As₈ intermediary layers, these results indicate that those layers couple only weakly to the FeAs layers in this new superconductor at least near the surface, which has …

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Carrier Lifetime Enhancement In A Tellurium Nanowire/Pedot:Pss Nanocomposite By Sulfur Passivation, James Heyman, Ayaskanta Sahu, Nelson Coates, Brittany Ehmann, Jeffery Urban Dec 2013

Carrier Lifetime Enhancement In A Tellurium Nanowire/Pedot:Pss Nanocomposite By Sulfur Passivation, James Heyman, Ayaskanta Sahu, Nelson Coates, Brittany Ehmann, Jeffery Urban

James Heyman

No abstract provided.

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Ultrafast Thz Faraday Rotation In Graphene, James Heyman, R. Foo Kune, B. Alebachew, M. Nguyen, J. Robinson Dec 2013

Ultrafast Thz Faraday Rotation In Graphene, James Heyman, R. Foo Kune, B. Alebachew, M. Nguyen, J. Robinson

James Heyman

No abstract provided.

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