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The Energy Budget of Steady-State Photosynthesis

Description: Our work developed a unique set of in vivo spectroscopic tools that have allowed us to probe the importance of 1) The effects of storage of proton motive force (pmf ) in the form of both electric field (Δψ) and pH difference (ΔpH); 2) alteration in the stoichiometry of proton pumping to electron transfer at key steps; 3) the influence of changes in the conductivity for proton efflux from the thylakoid of the ATP synthase; 4) the mechanisms of steps of the electron transfer process that pump protons; and 5) the mechanisms by which reactive O{sub 2} is generated as a side reaction to photosynthesis, and how these processes are minimized.
Date: June 30, 2007
Creator: Kramer, David
Partner: UNT Libraries Government Documents Department

Multiscale Atomistic Simulation of Metal-Oxygen Surface Interactions: Methodological Development, Theoretical Investigation, and Correlation With Experiment - Final Report

Description: Our long-term vision is for a comprehensive and fundamental understanding of a critical gas-surface reaction, nano-oxidation— from the adsorption of oxygen atoms on the metal surface to the coalescence of the bulk oxide—via coordinated multi-scale theoretical and in situ experimental efforts. Reaching this goal necessitates close collaborations between theorists and experimentalists, and the development and utilization of unique and substantial theoretical and experimental tools. Achievement of this goal will be a major breakthrough in dynamic surface/interface reactions that will dramatically impact several scientific fields. Many of these are of interest to DOE, such as thin films and nanostructures that use oxidation for processing, heteroepitaxy, oxidation and corrosion, environmental stability of nano-devices, catalysis, fuel cells and sensors. The purpose of this specific DOE program was the support for the theoretical effort. Our focus for the first round of funding has been the development of a Kinetic Monte Carlo (KMC) code to simulate the complexities of oxygen interactions with a metal surface. Our primary deliverable is a user-friendly, general and quite versatile KMC program, called Thin Film Oxidation (TFOx). TFOx-2D presently simulates the general behavior of irreversible 2-dimensional nucleation and growth of epitaxial islands on a square or rectangular lattice. The TFOx model explicitly considers a very large range of elementary steps, including deposition, adsorption, dissociation of gas molecules (such as O2), surface diffusion, aggregation, desorption and substrate-mediated indirect interactions between static adatoms. This capability allows for the description of the numerous physical processes involved in nucleation and growth. The large number of possible input parameters used in this program provides a rich environment for the simulation of epitaxial growth or oxidation of thin films. As a first demonstration of the power of TFOx-2D, the input parameters were systematically altered to observe how various physical processes impact morphologies. It was noted that ...
Date: September 30, 2007
Creator: Yang, Judith C.; McGaughey, Alan; Sinnott, Susan & Philpot, Simon
Partner: UNT Libraries Government Documents Department

LANGEVIN DYNAMICS OF THE TWO STAGE MELTING TRANSITION OF VORTEX MATTER IN Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} IN THE PRESENCE OF STRAIGHT AND OF TILTED COLUMNAR DEFECTS

Description: In this paper we use London Langevin molecular dynamics simulations to investigate the vortex matter melting transition in the highly anisotropic high-temperature superconductor material Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}#14; in the presence of low concentration of columnar defects (CDs). We reproduce with further details our previous results obtained by using Multilevel Monte Carlo simulations that showed that the melting of the nanocrystalline vortex matter occurs in two stages: a first stage melting into nanoliquid vortex matter and a second stage delocalization transition into a homogeneous liquid. Furthermore, we report on new dynamical measurements in the presence of a current that identifies clearly the irreversibility line and the second stage delocalization transition. In addition to CDs aligned along the c-axis we also simulate the case of tilted CDs which are aligned at an angle with respect to the applied magnetic field. Results for CDs tilted by 45{degree} with respect to c-axis show that the locations of the melting and delocalization transitions are not affected by the tilt when the ratio of flux lines to CDs remains constant. On the other hand we argue that some dynamical properties and in particular the position of the irreversibility line should be affected.
Date: August 7, 2007
Creator: Goldschmidt, Yadin Y. & Liu, Jin-Tao
Partner: UNT Libraries Government Documents Department

Final Report for DOE Grant DE-FG02-03ER54712, Experimental Studies of Collisionless Reconnection Processes in Plasmas

Description: The Grant DE-FG-02-00ER54712, ?Experimental Studies of Collisionless Reconnection Processes in Plasmas?, financed within the DoE/NSF, spanned a period from September , 2003 to August, 2007. It partly supported an MIT Research scientist, two graduate students and material expenses. The grant enabled the operation of a basic plasma physics experiment (on magnetic reconnection) at the MIT Plasma Science and Fusion Center and the MIT Physics Department. A strong educational component characterized this work throughout, with the participation of a large number of graduate and undergraduate students and interns to the experimental activities. The study of the collisionless magnetic reconnection constituted the primary work carried out under this grant. The investigations utilized two magnetic configurations with distinct boundary conditions. Both configurations were based upon the Versatile Toroidal Facility (VTF). The first configuration is characterized by open boundary conditions where the magnetic field lines interface directly with the vacuum vessel walls. The reconnection dynamics for this configuration has been methodically characterized and it has been shown that kinetic effects related to trapped electron trajectories are responsible for the high rates of reconnection observed [7]. This type of reconnection has not been investigated before. Nevertheless, the results are directly relevant to observations by the Wind spacecraft of fast reconnection deep in the Earth magnetotail [9]. The second configuration was developed to be specifically relevant to numerical simulations of magnetic reconnection, allowing the magnetic field-lines to be contained inside the device. The configuration is compatible with the presence of large current sheets in the reconnection region and reconnection is observed in fast powerful bursts. These reconnection events facilitate the first experimental investigations of the physics governing the spontaneous onset of fast reconnection [12]. In this Report we review the general motivation of this work, the experimental set-up, and the main physics results. The details of ...
Date: November 30, 2007
Creator: Porkolab, Miklos & Egedal, Jan
Partner: UNT Libraries Government Documents Department

Methods for Developing Emissions Scenarios for Integrated Assessment Models

Description: The overall objective of this research was to contribute data and methods to support the future development of new emissions scenarios for integrated assessment of climate change. Specifically, this research had two main objectives: 1. Use historical data on economic growth and energy efficiency changes, and develop probability density functions (PDFs) for the appropriate parameters for two or three commonly used integrated assessment models. 2. Using the parameter distributions developed through the first task and previous work, we will develop methods of designing multi-gas emission scenarios that usefully span the joint uncertainty space in a small number of scenarios. Results on the autonomous energy efficiency improvement (AEEI) parameter are summarized, an uncertainty analysis of elasticities of substitution is described, and the probabilistic emissions scenario approach is presented.
Date: August 20, 2007
Creator: Prinn, Ronald & Webster, Mort
Partner: UNT Libraries Government Documents Department

VisPort: Web-Based Access to Community-Specific Visualization Functionality [Shedding New Light on Exploding Stars: Visualization for TeraScale Simulation of Neutrino-Driven Supernovae (Final Technical Report)]

Description: The VisPort visualization portal is an experiment in providing Web-based access to visualization functionality from any place and at any time. VisPort adopts a service-oriented architecture to encapsulate visualization functionality and to support remote access. Users employ browser-based client applications to choose data and services, set parameters, and launch visualization jobs. Visualization products – typically images or movies – are viewed in the user’s standard Web browser. VisPort emphasizes visualization solutions customized for specific application communities. Finally, VisPort relies heavily on XML, and introduces the notion of visualization informatics -“ the formalization and specialization of information related to the process and products of visualization.
Date: June 30, 2007
Creator: Baker, M Pauline
Partner: UNT Libraries Government Documents Department

Precision Measurement of the proton neutral weak form factors at Q{sup 2} ~ 0.1 GeV{sup 2}

Description: This thesis reports the HAPPEX measurement of the parity-violating asymmetry for longitudinally polarized electrons elastically scattered from protons in a liquid hydrogen target. The measurement was carried out in Hall A at Thomas Jefferson National Accelerator Facility using a beam energy E = 3 GeV and scattering angle <θ{sub lab}> = 6◦. The asymmetry is sensitive to the weak neutral form factors from which we extract the strange quark electric and magnetic form factors (G{sup s}{sub E} and G{sup s}{sub M}) of the proton. The measurement was conducted during two data-taking periods in 2004 and 2005. This thesis describes the methods for controlling the helicity-correlated beam asymmetries and the analysis of the raw asymmetry. The parity-violating asymmetry has been measured to be A{sub PV} = −1.14± 0.24 (stat)±0.06 (syst) ppm at <Q{sup 2}> = 0.099 GeV{sup 2} (2004), and A{sub PV} = −1.58±0.12 (stat)±0.04 (syst) ppm at <Q{sup 2}> = 0.109 GeV{sup 2} (2005). The strange quark form factors extracted from the asymmetry are G{sup s}{sub E} + 0.080G{sup s}{sub M} = 0.030 ± 0.025 (stat) ± 0.006 (syst) ± 0.012 (FF) (2004) and G{sup s}{sub E} +0.088G{sup s}{sub M} = 0.007±0.011 (stat)±0.004 (syst)±0.005 (FF) (2005). These results place the most precise constraints on the strange quark form factors and indicate little strange dynamics in the proton.
Date: February 1, 2007
Creator: Kaufman, Lisa
Partner: UNT Libraries Government Documents Department

Reaction-based Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

Description: This research sought to examine biogeochemical processes likely to take place in the less conductive materials above and below the gravel during the in situ ethanol biostimulation experiment conducted at Area 2 during 2005-2006. The in situ experiment in turn examined the hypothesis that injection of electron donor into this layer would induce formation of a redox barrier in the less conductive materials, resulting in decreased mass transfer of uranium out these materials and attendant declines in groundwater U(VI) concentration. Our project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This report summarizes research activities conducted at The University of Central Florida (2004-2007), the development of biogeochemical and reactive transport models and the conduction of numerical simulations at laboratory, column, and field scales.
Date: December 21, 2007
Creator: Tsyh Yeh, Gour
Partner: UNT Libraries Government Documents Department

Initial Development in Joining of ODS Alloys Using Friction Stir Welding

Description: Solid-state welding of oxide-dispersion-strengthened (ODS) alloy MA956 sheets using friction stir welding (FSW) was investigated. Butt weld was successfully produced. The weld and base metals were characterized using optical microscopy, scanning electronic microscopy, transmission electronic microscopy, and energy dispersion x-ray spectrum. Microhardness mapping was also conducted over the weld region. Analyses indicate that the distribution of the strengthening oxides was preserved in the weld. Decrease in microhardness of the weld was observed but was insignificant. The preliminary results seem to confirm the envisioned feasibility of FSW application to ODS alloy joining. For application to Gen IV nuclear reactor heat exchanger, further investigation is suggested.
Date: August 1, 2007
Creator: Ren, Weiju & Feng, Zhili
Partner: UNT Libraries Government Documents Department

Updated laser safety&hazard analysis for the ARES laser system based on the 2007 ANSI Z136.1 standard.

Description: A laser safety and hazard analysis was performed for the temperature stabilized Big Sky Laser Technology (BSLT) laser central to the ARES system based on the 2007 version of the American National Standards Institute's (ANSI) Standard Z136.1, for Safe Use of Lasers and the 2005 version of the ANSI Standard Z136.6, for Safe Use of Lasers Outdoors. The ARES laser system is a Van/Truck based mobile platform, which is used to perform laser interaction experiments and tests at various national test sites.
Date: August 1, 2007
Creator: Augustoni, Arnold L.
Partner: UNT Libraries Government Documents Department

Accommodating complexity and human behaviors in decision analysis.

Description: This is the final report for a LDRD effort to address human behavior in decision support systems. One sister LDRD effort reports the extension of this work to include actual human choices and additional simulation analyses. Another provides the background for this effort and the programmatic directions for future work. This specific effort considered the feasibility of five aspects of model development required for analysis viability. To avoid the use of classified information, healthcare decisions and the system embedding them became the illustrative example for assessment.
Date: November 1, 2007
Creator: Backus, George A.; Siirola, John Daniel; Schoenwald, David Alan; Strip, David R.; Hirsch, Gary B.; Bastian, Mark S. et al.
Partner: UNT Libraries Government Documents Department

Air Quality Scoping Study for Beatty, Nevada (EMSI April 2007)

Description: The Desert Research Institute (DRI) is performing a scoping study as part of the U.S. Department of Energy’s Yucca Mountain Environmental Monitoring Systems Initiative (EMSI). The main objective is to obtain baseline air quality information for Yucca Mountain and an area surrounding the Nevada Test Site (NTS). Air quality and meteorological monitoring and sampling equipment housed in a mobile trailer (shelter) is collecting data at seven sites outside the NTS, including Ash Meadows National Wildlife Refuge, Sarcobatus Flat, Beatty, Rachel, Caliente, Pahranagat National Wildlife Refuge, and Crater Flat, and at four sites on the NTS. The trailer is stationed at any one site for approximately eight weeks at a time. Letter reports provide summaries of air quality and meteorological data, on completion of each site’s sampling program.
Date: April 1, 2007
Creator: Johann Engelbrecht, Ilias Kavouras, Dave Campbell, Scott Campbell, Steven Kohl and David Shafer
Partner: UNT Libraries Government Documents Department

Air Quality Scoping Study for Rachel, Nevada (EMSI April 2007)

Description: The Desert Research Institute (DRI) is performing a scoping study as part of the U.S. Department of Energy’s Yucca Mountain Environmental Monitoring Systems Initiative (EMSI). The main objective is to obtain baseline air quality information for Yucca Mountain and an area surrounding the Nevada Test Site (NTS). Air quality and meteorological monitoring and sampling equipment housed in a mobile trailer (shelter) is collecting data at seven sites outside the NTS, including Ash Meadows National Wildlife Refuge, Sarcobatus Flat, Beatty, Rachel, Caliente, Pahranagat National Wildlife Refuge, and Crater Flat, and at four sites on the NTS. The trailer is stationed at any one site for approximately eight weeks at a time. Letter reports provide summaries of air quality and meteorological data, on completion of each site’s sampling program.
Date: April 1, 2007
Creator: Johann Engelbrecht, Ilias Kavouras, Dave Campbell, Scott Campbell, Steven Kohl and David Shafer
Partner: UNT Libraries Government Documents Department

Air Quality Scoping Study for Sarcobatus Flat, Nevada (EMSI April 2007)

Description: The Desert Research Institute (DRI) is performing a scoping study as part of the U.S. Department of Energy’s Yucca Mountain Environmental Monitoring Systems Initiative (EMSI). The main objective is to obtain baseline air quality information for Yucca Mountain and an area surrounding the Nevada Test Site (NTS). Air quality and meteorological monitoring and sampling equipment housed in a mobile trailer (shelter) is collecting data at seven sites outside the NTS, including Ash Meadows National Wildlife Refuge, Sarcobatus Flat, Beatty, Rachel, Caliente, Pahranagat National Wildlife Refuge, and Crater Flat, and at four sites on the NTS. The trailer is stationed at any one site for approximately eight weeks at a time. Letter reports provide summaries of air quality and meteorological data, on completion of each site’s sampling program.
Date: April 1, 2007
Creator: Johann Engelbrecht, Ilias Kavouras, Dave Campbell, Scott Campbell, Steven Kohl and David Shafer
Partner: UNT Libraries Government Documents Department