Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Selected Works

2016

Discipline
Institution
Keyword
Publication
File Type

Articles 211 - 225 of 225

Full-Text Articles in Physics

The Electric Field At The Chargeless Interface Between Two Regions Of Space, Asim Gangopadhyaya, Robert Mcnees Jan 2016

The Electric Field At The Chargeless Interface Between Two Regions Of Space, Asim Gangopadhyaya, Robert Mcnees

Robert A McNees IV

A common method for solving Poisson's equation in electrostatics is to patch together two or more solutions of Laplace's equation using boundary conditions on the potential and its gradient. Other methods may generate solutions without the need to check these conditions explicitly, and reconciling these solutions with the appropriate boundary conditions can be surprisingly subtle. As a result, a student may arrive at paradoxical conclusions—even in the case of elementary problems—that seem to be at odds with basic physical intuition. We illustrate this issue by showing how the potential of a uniformly charged ring appears to violate continuity of the …


Cosmological Constant As Confining U(1) Charge In Two-Dimensional Dilaton Gravity, Daniel Grumiller, Robert Mcnees, Jakob Salzer Jan 2016

Cosmological Constant As Confining U(1) Charge In Two-Dimensional Dilaton Gravity, Daniel Grumiller, Robert Mcnees, Jakob Salzer

Robert A McNees IV

The cosmological constant is treated as a thermodynamical parameter in the framework of two-dimensional dilaton gravity. We find that the cosmological constant behaves as a U(1) charge with a confining potential, and that such potentials require a novel Born-Infeld boundary term in the action. The free energy and other thermodynamical quantities of interest are derived, from first principles, in a way that is essentially model independent. We discover that there is always a Schottky anomaly in the specific heat and explain its physical origin. Finally, we apply these results to specific examples, like anti-de Sitter–Schwarzschild–Tangherlini black holes, Bañados-Teitelboim-Zanelli black holes …


Boundary Terms Unbound! Holographic Renormalization Of Asymptotically Linear Dilaton Gravity, Robert Mcnees, Robert Mann Jan 2016

Boundary Terms Unbound! Holographic Renormalization Of Asymptotically Linear Dilaton Gravity, Robert Mcnees, Robert Mann

Robert A McNees IV

A variational principle is constructed for gravity coupled to an asymptotically linear dilaton and a p-form field strength. This requires the introduction of appropriate surface terms—also known as 'boundary counterterms'—in the action. The variation of the action with respect to the boundary metric yields a boundary stress tensor, which is used to construct conserved charges that generate the asymptotic symmetries of the theory. In most cases a minimal set of assumptions leads to a unique set of counterterms. However, for certain examples we find families of actions that depend on one or more continuous parameters. We show that the conserved …


Archive - A Data Management Program, James H. Devilbiss, C. Steven Whisnant, Yasmeen Shorish Jan 2016

Archive - A Data Management Program, James H. Devilbiss, C. Steven Whisnant, Yasmeen Shorish

Yasmeen Shorish

To meet funding agency requirements, a portable data management solution is presented for small research groups. The database created is simple, searchable, robust, and can reside across multiple hard drives. Employing a standard metadata schema for all data, the database ensures a high level of standardization, findability, and organization. The software is written in Perl, runs on UNIX, and presents a web-based user interface. It uses a fast, portable log-in scheme, making it easy to export to other locations. As research continues to move towards more open data sharing and reproducibility, this database solution is agile enough to accommodate external …


Boom Or Bust? Mapping Out The Known Unknowns Of Global Shale Gas Production Potential, Jérôme Hilaire, Nico Bauer, Robert Brecha Jan 2016

Boom Or Bust? Mapping Out The Known Unknowns Of Global Shale Gas Production Potential, Jérôme Hilaire, Nico Bauer, Robert Brecha

Robert J. Brecha

To assess the global production costs of shale gas, we combine global top-down data with detailed bottom-up information. Studies solely based on top-down approaches do not adequately account for the heterogeneity of shale gas deposits and hence, are unlikely to appropriately capture the extraction costs of shale gas. We design and provide an expedient bottom-up method based on publicly available US data to compute the levelized costs of shale gas extraction. Our results indicate the existence of economically attractive areas but also reveal a dramatic cost increase as lower-quality reservoirs are exploited. At the global level, our best estimate suggests …


Electrical Control Of Chiral Phases In Electrotoroidic Nanocomposites, Raymond T. Walter, Sergei Prokhorenko, Zhigang Gui, Yousra Nahas, Laurent Bellaiche Jan 2016

Electrical Control Of Chiral Phases In Electrotoroidic Nanocomposites, Raymond T. Walter, Sergei Prokhorenko, Zhigang Gui, Yousra Nahas, Laurent Bellaiche

Raymond Walter

Molecular dynamics in a first-principle-based effective Hamiltonian scheme show that optical rotation of polarized light as measured by gyrotropic coefficient is maximized at room temperature for some applied DC electric field in a ferroelectric nanocomposite consisting of BaTiO3 nanowires in an SrTiO3 medium that exhibits electrical vortices. Together with a phase diagram obtained from Monte Carlo simulation, this characterizes optical applications of electrical vortices.


Customizable Electron Beams From Optically Controlled Laser Plasma Acceleration For Γ-Ray Sources Based On Inverse Thomson Scattering, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick Jan 2016

Customizable Electron Beams From Optically Controlled Laser Plasma Acceleration For Γ-Ray Sources Based On Inverse Thomson Scattering, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick

Serge Youri Kalmykov

Laser wakefield acceleration of electrons in the blowout regime can be controlled by tailoring the laser pulse phase and the plasma target. The100nm-scale bandwidth and negative frequency chirp of the optical driver compensate for the nonlinear frequency red-shift imparted by wakefield excitation.This mitigates pulse self-steepening and suppresses continuous injection. The plasma channel suppresses diffraction of the pulse leading edge, further reducing self-steepening, making injection even quieter. Besides, the channel destabilizes the pulse tail confined within the accelerator cavity (the electron density “bubble”), causing oscillations in the bubble size. The resulting periodic injection generates background-free comb-like beams – sequences of synchronized, …


Shape Invariance And Its Connection To Potential Algebra, Asim Gangopadhyaya, Jeffrey Mallow, Uday Sukhatme Jan 2016

Shape Invariance And Its Connection To Potential Algebra, Asim Gangopadhyaya, Jeffrey Mallow, Uday Sukhatme

Asim Gangopadhyaya

Exactly solvable potentials of nonrelativistic quantum mechanics are known to be shape invariant. For these potentials, eigenvalues and eigenvectors can be derived using well known methods of supersymmetric quantum mechanics. The majority of these potentials have also been shown to possess a potential algebra, and hence are also solvable by group theoretical techniques. In this paper, for a subset of solvable problems, we establish a connection between the two methods and show that they are indeed equivalent.


Procesy Cieplne I Aparaty (Lab), Wojciech M. Budzianowski Jan 2016

Procesy Cieplne I Aparaty (Lab), Wojciech M. Budzianowski

Wojciech Budzianowski

-


Inżynieria Chemiczna Lab., Wojciech M. Budzianowski Jan 2016

Inżynieria Chemiczna Lab., Wojciech M. Budzianowski

Wojciech Budzianowski

-


Approaching A Universal Scaling Relationship Between Fracture Stiffness And Fluid Flow, David Nolte, Laura Pyrak-Nolte Dec 2015

Approaching A Universal Scaling Relationship Between Fracture Stiffness And Fluid Flow, David Nolte, Laura Pyrak-Nolte

David D Nolte

A goal of subsurface geophysical monitoring is the detection and characterization of fracture
alterations that affect the hydraulic integrity of a site. Achievement of this goal requires a link
between the mechanical and hydraulic properties of a fracture. Here we present a scaling
relationship between fluid flow and fracture-specific stiffness that approaches universality.
Fracture-specific stiffness is a mechanical property dependent on fracture geometry that can
be monitored remotely using seismic techniques. A Monte Carlo numerical approach
demonstrates that a scaling relationship exists between flow and stiffness for fractures with
strongly correlated aperture distributions, and continues to hold for fractures deformed …


Electrical Control Of Chiral Phases In Electrotoroidicnanocomposites, Raymond Walter, Sergei Prokhorenko, Zhigang Gui, Yousra Nahas, Laurent Bellaiche Dec 2015

Electrical Control Of Chiral Phases In Electrotoroidicnanocomposites, Raymond Walter, Sergei Prokhorenko, Zhigang Gui, Yousra Nahas, Laurent Bellaiche

Raymond Walter

Molecular dynamics in a first-principle-based effective Hamiltonian scheme show that optical rotation of polarized light as measured by gyrotropic coefficient is maximized at room temperature for some applied DC electric field in a ferroelectric nanocomposite consisting of BaTiO3nanowires in an SrTiO3 medium that exhibits electrical vortices. Together with a phase diagram obtained from Monte Carlo simulation, this characterizes optical applications of electrical vortices.


Revisiting Galvanomagnetic Effects In Conducting Ferromagnets, Raymond Walter, Michel Viret, Surendra Singh, Laurent Bellaiche Dec 2015

Revisiting Galvanomagnetic Effects In Conducting Ferromagnets, Raymond Walter, Michel Viret, Surendra Singh, Laurent Bellaiche

Raymond Walter

The recently proposed coupling between the angular momentum density and magnetic moments is shown
to provide a straightforward alternative explanation for galvanomagnetic eects, i.e., for both anisotropic
magnetoresistance (AMR) and planar Hall eect (PHE). Such coupling naturally reproduces the general
formula associated with AMR and PHE and allows for the occurrence of so-called `negative AMR'. This
coupling also provides a unifying link between AMR, PHE and the anomalous Hall eect (AHE) since this
same coupling was previously found to give rise to AHE (Bellaiche et al 2013 Phys. Rev. B 88 161102).


Interrogating Metabolism In Brain Cancer, Travis Salzillo, Jingzhe Hu, Linda Nguyen, Nicholas Whiting, Jaehyuk Lee, Joseph Weygand, Prasanta Dutta, Shivanand Pudakalakatti, Niki Zacharias Millward, Seth Gammon, Frederick F. Lang, Amy B. Heimberger, Pratip Bhattacharya Dec 2015

Interrogating Metabolism In Brain Cancer, Travis Salzillo, Jingzhe Hu, Linda Nguyen, Nicholas Whiting, Jaehyuk Lee, Joseph Weygand, Prasanta Dutta, Shivanand Pudakalakatti, Niki Zacharias Millward, Seth Gammon, Frederick F. Lang, Amy B. Heimberger, Pratip Bhattacharya

Nicholas Whiting

Many existing and emerging techniques of interrogating metabolism in brain cancer are at an early stage of development. A few clinical trials that employ these techniques are in progress in patients with brain cancer to establish the clinical efficacy of these techniques. It is likely that in vivo metabolomics and metabolic imaging is the next frontier in brain cancer diagnosis and assessing therapeutic efficacy.


Assessing The Impact Of Representational And Contextual Problem Features On Student Use Of Right-Hand Rules, Mary Bridget Kustusch Dec 2015

Assessing The Impact Of Representational And Contextual Problem Features On Student Use Of Right-Hand Rules, Mary Bridget Kustusch

Mary Bridget Kustusch

Students in introductory physics struggle with vector algebra and these challenges are often associated
with contextual and representational features of the problems. Performance on problems about cross product
direction is particularly poor and some research suggests that this may be primarily due to misapplied right-
hand rules. However, few studies have had the resolution to explore student use of right-hand rules in detail.
This study reviews literature in several disciplines, including spatial cognition, to identify ten contextual and
representational problem features that are most likely to influence performance on problems requiring a
right-hand rule. Two quantitative measures of performance (correctness …