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Full-Text Articles in Physics

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 …


Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown Aug 2011

Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown

STAR Program Research Presentations

Astrophysicists use radiation to investigate the physics controlling a variety of celestial sources, including stellar atmospheres, black holes, and binary systems. By measuring the spectrum of the emitted radiation, astrophysicists can determine a source’s temperature and composition. Accurate atomic data are needed for reliably interpreting these spectra. Here we present an overview of how LLNL’s EBIT facility is used to put the atomic data on sound footing for use by the high energy astrophysics community.


Exploring Methods For Earthquake Prediction: The Effects Of Water On The Flow Of Stress-Activated Electric Currents In Igneous Rocks, Aaron M. Jahoda, Friedemann T. Freund Aug 2011

Exploring Methods For Earthquake Prediction: The Effects Of Water On The Flow Of Stress-Activated Electric Currents In Igneous Rocks, Aaron M. Jahoda, Friedemann T. Freund

STAR Program Research Presentations

Much of the devastation and damage of earthquakes can be attributed to the fact that they occur suddenly and without much warning, which limits the ability of people to evacuate and/or properly prepare. One method, however, that might be used to predict seismic events is the generation of electric currents in rocks when stresses are applied. It is observed in this research that the application of direct force onto samples of igneous rock causes the rocks to generate a measurable current, which is attributed to positive-hole charges moving within the oxygen sub-lattice. Because large and changing forces are acted upon …


Ozone Profile Observations In Houston, Texas (1994 - 2010) From Aircraft, Balloons, And Satellites, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Christopher Boxe, Scott Hersey, Valerie Thouret, Jean-Pierre Cammas, Bryan Johnson, Samuel Oltmans Apr 2011

Ozone Profile Observations In Houston, Texas (1994 - 2010) From Aircraft, Balloons, And Satellites, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Christopher Boxe, Scott Hersey, Valerie Thouret, Jean-Pierre Cammas, Bryan Johnson, Samuel Oltmans

Physics and Astronomy Faculty Presentations

Houston, Texas has long been an urban area plagued with high levels of surface ozone, particularly in spring and late summer. The combination of a large commuter population and one of the largest concentrations of petrochemical plants in the world results in abundant and nearly co-located sources of NOx and hydrocarbons. The location of Houston on the South Coast of the United States in a subtropical climate results in meteorological conditions that favor ozone production. Using MOZAIC (1994 - 2004), ozonesonde (2000, 2004 - 2010), and TES (2005 – 2010) data, we examine the evolution of ozone profiles over Houston …


Towards An Integrated Multiscale Simulation Of Turbulent Clouds On Petascale Computers, Lian-Ping Wang, Orlando Ayala, Hossein Parishani, Wojciech W. Grabowski, Andrzej A. Wyszogrodzki, Zbigniew Piotrowski, Guang R. Gao, Chandra Kambhamettu, Xiaoming Li, Louis Rossi Jan 2011

Towards An Integrated Multiscale Simulation Of Turbulent Clouds On Petascale Computers, Lian-Ping Wang, Orlando Ayala, Hossein Parishani, Wojciech W. Grabowski, Andrzej A. Wyszogrodzki, Zbigniew Piotrowski, Guang R. Gao, Chandra Kambhamettu, Xiaoming Li, Louis Rossi

Engineering Technology Faculty Publications

The development of precipitating warm clouds is affected by several effects of small-scale air turbulence including enhancement of droplet-droplet collision rate by turbulence, entrainment and mixing at the cloud edges, and coupling of mechanical and thermal energies at various scales. Large-scale computation is a viable research tool for quantifying these multiscale processes. Specifically, top-down large-eddy simulations (LES) of shallow convective clouds typically resolve scales of turbulent energy-containing eddies while the effects of turbulent cascade toward viscous dissipation are parameterized. Bottom-up hybrid direct numerical simulations (HDNS) of cloud microphysical processes resolve fully the dissipation-range flow scales but only partially the inertial …


Kinematic And Dynamic Pair Collision Statistics Of Sedimenting Inertial Particles Relevant To Warm Rain Initiation, Bogdan Rosa, Hossein Parishani, Orlando Ayala, Lian-Ping Wang, Wojciech W. Grabowski Jan 2011

Kinematic And Dynamic Pair Collision Statistics Of Sedimenting Inertial Particles Relevant To Warm Rain Initiation, Bogdan Rosa, Hossein Parishani, Orlando Ayala, Lian-Ping Wang, Wojciech W. Grabowski

Engineering Technology Faculty Publications

In recent years, direct numerical simulation (DNS) approach has become a reliable tool for studying turbulent collision-coalescence of cloud droplets relevant to warm rain development. It has been shown that small-scale turbulent motion can enhance the collision rate of droplets by either enhancing the relative velocity and collision efficiency or by inertia-induced droplet clustering. A hybrid DNS approach incorporating DNS of air turbulence, disturbance flows due to droplets, and droplet equation of motion has been developed to quantify these effects of air turbulence. Due to the computational complexity of the approach, a major challenge is to increase the range of …