Reconstructing Ocean Circulation using Coral (triangle)14C Time Series (open access)

Reconstructing Ocean Circulation using Coral (triangle)14C Time Series

We utilize monthly {sup 14}C data derived from coral archives in conjunction with ocean circulation models to address two questions: (1) how does the shallow circulation of the tropical Pacific vary on seasonal to decadal time scales and (2) which dynamic processes determine the mean vertical structure of the equatorial Pacific thermocline. Our results directly impact the understanding of global climate events such as the El Nino-Southern Oscillation (ENSO). To study changes in ocean circulation and water mass distribution involved in the genesis and evolution of ENSO and decadal climate variability, it is necessary to have records of climate variables several decades in length. Continuous instrumental records are limited because technology for continuous monitoring of ocean currents (e.g. satellites and moored arrays) has only recently been available, and ships of opportunity archives such as COADS contain large spatial and temporal biases. In addition, temperature and salinity in surface waters are not conservative and thus can not be independently relied upon to trace water masses, reducing the utility of historical observations. Radiocarbon in sea water is a quasi-conservative water mass tracer and is incorporated into coral skeletal material, thus coral {sup 14}C records can be used to reconstruct changes in shallow …
Date: February 23, 2001
Creator: Kashgarian, M. & Guilderson, T. P.
Object Type: Report
System: The UNT Digital Library
Biogeochemical Proxies in Scleractinian Corals used to Reconstruct Ocean Circulation (open access)

Biogeochemical Proxies in Scleractinian Corals used to Reconstruct Ocean Circulation

We utilize monthly {sup 14}C data derived from coral archives in conjunction with ocean circulation models to address two questions: (1) how does the shallow circulation of the tropical Pacific vary on seasonal to decadal time scales and (2) which dynamic processes determine the mean vertical structure of the equatorial Pacific thermocline. Our results directly impact the understanding of global climate events such as the El Nino-Southern Oscillation (ENSO). To study changes in ocean circulation and water mass distribution involved in the genesis and evolution of ENSO and decadal climate variability, it is necessary to have records of climate variables several decades in length. Continuous instrumental records are limited because technology for continuous monitoring of ocean currents has only recently been available, and ships of opportunity archives such as COADS contain large spatial and temporal biases. In addition, temperature and salinity in surface waters are not conservative and thus can not be independently relied upon to trace water masses, reducing the utility of historical observations. Radiocarbon ({sup 14}C) in sea water is a quasi-conservative water mass tracer and is incorporated into coral skeletal material, thus coral {sup 14}C records can be used to reconstruct changes in shallow circulation that would …
Date: February 23, 2001
Creator: Guilderson, T. P.; Kashgarian, M. & Schrag, D. P.
Object Type: Article
System: The UNT Digital Library
Biogeochemical Proxies in Scleractinian Corals used to Reconstruct Ocean Circulation (open access)

Biogeochemical Proxies in Scleractinian Corals used to Reconstruct Ocean Circulation

We utilize monthly {sup 14}C data derived from coral archives in conjunction with ocean circulation models to address two questions: (1) how does the shallow circulation of the tropical Pacific vary on seasonal to decadal time scales and (2) which dynamic processes determine the mean vertical structure of the equatorial Pacific thermocline. Our results directly impact the understanding of global climate events such as the El Nino-Southern Oscillation (ENSO). To study changes in ocean circulation and water mass distribution involved in the genesis and evolution of ENSO and decadal climate variability, it is necessary to have records of climate variables several decades in length. Continuous instrumental records are limited because technology for continuous monitoring of ocean currents has only recently been available, and ships of opportunity archives such as COADS contain large spatial and temporal biases. In addition, temperature and salinity in surface waters are not conservative and thus can not be independently relied upon to trace water masses, reducing the utility of historical observations. Radiocarbon ({sup 14}C) in sea water is a quasi-conservative water mass tracer and is incorporated into coral skeletal material, thus coral {sup 14}C records can be used to reconstruct changes in shallow circulation that would …
Date: February 23, 2001
Creator: Guilderson, Thomas P.; Kashgarian, Michaele & Schrag, Daniel P.
Object Type: Article
System: The UNT Digital Library
Hybrid Paper/Electronic Archival Collecting, Processing, and Reference: A View from SLAC (open access)

Hybrid Paper/Electronic Archival Collecting, Processing, and Reference: A View from SLAC

Real-time archiving of mixed paper and digital collections presents challenges not encountered in the primarily paper environment. A few recent examples from the archives of the Stanford Linear Accelerator Center highlight obstacles encountered, and attempted and contemplated solutions.
Date: May 23, 2008
Creator: Deken, Jean M.
Object Type: Article
System: The UNT Digital Library
Sustaining the Productivity and Function of Intensively Managed Forests - Final Report (open access)

Sustaining the Productivity and Function of Intensively Managed Forests - Final Report

The main goal of this study is to ensure sustainable management of wetland forests in the southeastern United States. The study is projected to measure soil, hydrology, and forest responses to several management scenarios across a complete forest cycle. From August 1997 to August 2000 the study has received funding as one of the Agenda 2020 projects, from the U.S. Department of Energy (Cooperative Agreement Number DE-FC07-97ID13551), the National Council of the Paper Industry for Air and Stream Improvement, and Westvac Corporation. Quarterly progress reports were submitted regularly to the Department and all project participants. This final report summarizes the project results and progress achieved during this 3-year period. Over the past three years all research objectives planned for this project were completed.
Date: March 23, 2001
Creator: Burger, James A. & Xu, Yi-Jun
Object Type: Report
System: The UNT Digital Library
RECONSTRUCTION OF DOSE TO THE RESIDENTS OF OZERSK FROM THE OPERATION OF THE MAYAK PRODUCTION ASSOCIATION: 1948-2002: Progress Report on Project 1.4 (open access)

RECONSTRUCTION OF DOSE TO THE RESIDENTS OF OZERSK FROM THE OPERATION OF THE MAYAK PRODUCTION ASSOCIATION: 1948-2002: Progress Report on Project 1.4

This Progress Report for Project 1.4 of the U.S.–Russia Joint Coordinating Committee on Radiation Effects Research continues in the abbreviated format of providing details only on the work accomplished during this six-month reporting period.
Date: October 23, 2009
Creator: Mokrov, Y.; Rovny, Sergey I.; Anspaugh, L. R. & Napier, Bruce A.
Object Type: Report
System: The UNT Digital Library
The distribution and contaminant exposure of Rafinesque's Big-Eared Bats in South Carolina with an emphasis on bridge surveys. (open access)

The distribution and contaminant exposure of Rafinesque's Big-Eared Bats in South Carolina with an emphasis on bridge surveys.

Rafinesque's big-eared bat (Corynorhinus rafinesquii), an insectivorous mammal indigenous to the southern United States, has long been referred to as one of the least known bats in North America. Although there has been a moderate increase in the number of peer-reviewed articles published on this species in the past 6 years, the basic ecology and status of Rafinesque's big-eared bat remains largely obscure. Prior to 1996, when the United States Fish and Wildlife Service (USFWS) discontinued the list of Candidate Species, Rafinesque's big-eared bat was listed as a Federal Category 2 Candidate species. Currently, Rafinesque's big-eared bat is recognized as a ''species of special concern'' across most of its range but receives no legal protection. Nonetheless, the USFWS and numerous state agencies remain concerned about this species. Further biological research and field study are needed to resolve the conservation status of this taxona. In response to the paucity of information regarding the status and distribution of Rafinesque's big-eared bat, statewide survey of highway bridges used as roost sites was conducted.
Date: October 23, 2003
Creator: Bennett, F.M.; Loeb, S.C. & Bowerman, W.W.
Object Type: Report
System: The UNT Digital Library
Out-of-band exposure characterization with the SEMATECH Berkeley 0.3-NA microfield exposure tool (open access)

Out-of-band exposure characterization with the SEMATECH Berkeley 0.3-NA microfield exposure tool

For the commercialization of extreme ultraviolet lithography (EUVL), discharge or laser produced, pulsed plasma light sources are being considered. These sources are known to emit into a broad range of wavelengths that are collectively referred to as the out-of-band (OOB) radiation by lithographers. Multilayer EUV optics reflect OOB radiation emitted by the EUV sources onto the wafer plane resulting in unwanted background exposure of the resist (flare) and reduced image contrast. The reflectivity of multilayer optics at the target wavelength of 13.5 nm is comparable to that of their reflectivity in the deep ultraviolet (DUV) and UV regions from 100-350 nm. The aromatic molecular backbones of many of the resists used for EUV are equally absorptive at specific DUV wavelengths as well. In order to study the effect of these wavelengths on imaging performance in a real system, we are in the process of integrating a DUV source into the SEMATECH Berkeley 0.3-NA Microfield Exposure Tool (MET). The MET plays an active role in advanced research in resist and mask development for EUVL and as such, we will utilize this system to systematically evaluate the imaging impact of DUV wavelengths in a EUV system. In this paper, we present the …
Date: February 23, 2009
Creator: George, Simi A.; Nauleau, Patrick; Rekawa, Senajith; Gullikson, Eric & Kemp, Charles D.
Object Type: Article
System: The UNT Digital Library
Detecting and monitoring UCG subsidence with InSAR (open access)

Detecting and monitoring UCG subsidence with InSAR

The use of interferometric synthetic aperture radar (InSAR) to measure surface subsidence caused by Underground Coal Gasification (UCG) is tested. InSAR is a remote sensing technique that uses Synthetic Aperture Radar images to make spatial images of surface deformation and may be deployed from satellite or an airplane. With current commercial satellite data, the technique works best in areas with little vegetation or farming activity. UCG subsidence is generally caused by roof collapse, which adversely affects UCG operations due to gas loss and is therefore important to monitor. Previous studies have demonstrated the usefulness of InSAR in measuring surface subsidence related to coal mining and surface deformation caused by a coal mining roof collapse in Crandall Canyon, Utah is imaged as a proof-of-concept. InSAR data is collected and processed over three known UCG operations including two pilot plants (Majuba, South Africa and Wulanchabu, China) and an operational plant (Angren, Uzbekistan). A clear f eature showing approximately 7 cm of subsidence is observed in the UCG field in Angren. Subsidence is not observed in the other two areas, which produce from deeper coal seams and processed a smaller volume. The results show that in some cases, InSAR is a useful tool …
Date: March 23, 2012
Creator: Mellors, R J; Foxall, W & Yang, X
Object Type: Report
System: The UNT Digital Library
Seasonally Resolved Surface Water (delta)14C Variability in the Lombok Strait: A Coralline Perspective (open access)

Seasonally Resolved Surface Water (delta)14C Variability in the Lombok Strait: A Coralline Perspective

We have explored surface water mixing in the Lombok Strait through a {approx}bimonthly resolved surface water {Delta}{sup 14}C time-series reconstructed from a coral in the Lombok Strait that spans 1937 through 1990. The prebomb surface water {Delta}{sup 14}C average is -60.5{per_thousand} and individual samples range from -72{per_thousand} to 134{per_thousand}. The annual average post-bomb maximum occurs in 1973 and is 122{per_thousand}. The timing of the post-bomb maximum is consistent with a primary subtropical source for the surface waters in the Indonesian Seas. During the post-bomb period the coral records regular seasonal cycles of 5-20{per_thousand}. Seasonal high {Delta}{sup 14}C occur during March-May (warm, low salinity), and low {Delta}{sup 14}C occur in September (cool, higher salinity). The {Delta}{sup 14}C seasonality is coherent and in phase with the seasonal {Delta}{sup 14}C cycle observed in Makassar Strait. We estimate the influence of high {Delta}{sup 14}C Makassar Strait (North Pacific) water flowing through the Lombok Strait using a two endmember mixing model and the seasonal extremes observed at the two sites. The percentage of Makassar Strait water varies between 16 and 70%, and between 1955 and 1990 it averages 40%. During La Nina events there is a higher percentage of Makassar Strait (high {Delta}{sup 14}C) water …
Date: April 23, 2008
Creator: Guilderson, T. P.; Fallon, S. J.; Moore, M. D.; Schrag, D. P. & Charles, C. D.
Object Type: Article
System: The UNT Digital Library
Macromolecular Structure Database. Final Progress Report (open access)

Macromolecular Structure Database. Final Progress Report

The central activity of the PDB continues to be the collection, archiving and distribution of high quality structural data to the scientific community on a timely basis. In support of these activities NIST has continued its roles in developing the physical archive, in developing data uniformity, in dealing with NMR issues and in the distribution of PDB data through CD-ROMs. The physical archive holdings have been organized, inventoried, and a database has been created to facilitate their use. Data from individual PDB entries have been annotated to produce uniform values improving tremendously the accuracy of results of queries. Working with the NMR community we have established data items specific for NMR that will be included in new entries and facilitate data deposition. The PDB CD-ROM production has continued on a quarterly basis, and new products are being distributed.
Date: September 23, 2003
Creator: Gilliland, Gary L.
Object Type: Report
System: The UNT Digital Library
Age Dating of SRM U050: LLNL Results (open access)

Age Dating of SRM U050: LLNL Results

None
Date: August 23, 2013
Creator: Williams, R. W.; Gaffney, A. M.; Schorzman, K. C. & Villa, A. C.
Object Type: Report
System: The UNT Digital Library
Computational Modeling in Support of National Ignition Facility Operations (open access)

Computational Modeling in Support of National Ignition Facility Operations

Numerical simulation of the National Ignition Facility (NIF) laser performance and automated control of laser setup process are crucial to the project's success. These functions will be performed by two closely coupled computer codes: the virtual beamline (VBL) and the laser operations performance model (LPOM).
Date: October 23, 2001
Creator: Shaw, M J; Sacks, R A; Haynam, C A & Williams, W H
Object Type: Article
System: The UNT Digital Library
Organization and performance of the neutral beam system for the Tandem Mirror Experiment-Upgrade (TMX-U) (open access)

Organization and performance of the neutral beam system for the Tandem Mirror Experiment-Upgrade (TMX-U)

The Tandem Mirror Experiment-Upgrade (TMX-U) at Lawrence Livermore National Laboratory (LLNL) uses 24 neutral-beam injectors to heat and fuel the experimental plasmas. This system is unique because TMX-U operates four times more injectors than any other fusion experiment. These injectors deliver an average of 50 A (accel) at 17 keV for 75 ms. Source conditioning time has been reduced to approximately four days for the entire system after extended machine air cycles. TMX-U is also unique because it has 35 usable injector assemblies for the 24 power systems. This quantity of injectors makes possible the development of new hardware and injector modifications, and the reconditioning of damaged sources without affecting machine operation. Efficient operation of a system of this size requires coordinated interaction between the injector service groups and the physics organization. We describe the current state of TMX-U performance and the aspects of group interaction essential to a project of this size.
Date: November 23, 1983
Creator: Kane, R. J.; Hibbs, S. M.; Kerr, R. G. & Poulsen, P.
Object Type: Article
System: The UNT Digital Library
[Computer Science and Telecommunications Board activities] (open access)

[Computer Science and Telecommunications Board activities]

The board considers technical and policy issues pertaining to computer science, telecommunications, and associated technologies. Functions include providing a base of expertise for these fields in NRC, monitoring and promoting health of these fields, initiating studies of these fields as critical resources and sources of national economic strength, responding to requests for advice, and fostering interaction among the technologies and the other pure and applied science and technology. This document describes its major accomplishments, current programs, other sponsored activities, cooperative ventures, and plans and prospects.
Date: February 23, 1993
Creator: Blumenthal, M. S.
Object Type: Report
System: The UNT Digital Library
[Computer Science and Telecommunications Board activities] (open access)

[Computer Science and Telecommunications Board activities]

The board considers technical and policy issues pertaining to computer science, telecommunications, and associated technologies. Functions include providing a base of expertise for these fields in NRC, monitoring and promoting health of these fields, initiating studies of these fields as critical resources and sources of national economic strength, responding to requests for advice, and fostering interaction among the technologies and the other pure and applied science and technology. This document describes its major accomplishments, current programs, other sponsored activities, cooperative ventures, and plans and prospects.
Date: February 23, 1993
Creator: Blumenthal, M. S.
Object Type: Report
System: The UNT Digital Library
Iterative Dense Correspondence Correction Through Bundle Adjustment Feedback-Based Error Detection (open access)

Iterative Dense Correspondence Correction Through Bundle Adjustment Feedback-Based Error Detection

A novel method to detect and correct inaccuracies in a set of unconstrained dense correspondences between two images is presented. Starting with a robust, general-purpose dense correspondence algorithm, an initial pose estimate and dense 3D scene reconstruction are obtained and bundle-adjusted. Reprojection errors are then computed for each correspondence pair, which is used as a metric to distinguish high and low-error correspondences. An affine neighborhood-based coarse-to-fine iterative search algorithm is then applied only on the high-error correspondences to correct their positions. Such an error detection and correction mechanism is novel for unconstrained dense correspondences, for example not obtained through epipolar geometry-based guided matching. Results indicate that correspondences in regions with issues such as occlusions, repetitive patterns and moving objects can be identified and corrected, such that a more accurate set of dense correspondences results from the feedback-based process, as proven by more accurate pose and structure estimates.
Date: November 23, 2009
Creator: Hess-Flores, M A; Duchaineau, M A; Goldman, M J & Joy, K I
Object Type: Article
System: The UNT Digital Library
Economic and Energy Development in China: Policy Options and Implications for Climate Change (open access)

Economic and Energy Development in China: Policy Options and Implications for Climate Change

The Harvard University Center for the Environment and partner institutions in China established a multidisciplinary program of integrated research on energy-related environmental issues, local air pollution and global climate change, in China and their role in U.S.-Chinese relations. Major research streams included: (a) developing a dynamic, multi-sector model of the Chinese economy that can estimate energy use, emission, and health damages from pollution, and using this model to simulate broad economic effects of market-based pollution-control policies; (b) developing a regionally disaggregated model of technology and investment choice in the Chinese electric power sector; (c) applying an atmospheric chemical tracer transport model to investigate carbon uptake in Eurasis (notably China) and North America, and to inform observational strategies for CO{sub 2} in China and elsewhere.
Date: January 23, 2003
Creator: McElroy, M. B. & Nielsen, C.
Object Type: Report
System: The UNT Digital Library
Quantum robots plus environments. (open access)

Quantum robots plus environments.

A quantum robot is a mobile quantum system, including an on board quantum computer and needed ancillary systems, that interacts with an environment of quantum systems. Quantum robots carry out tasks whose goals include making specified changes in the state of the environment or carrying out measurements on the environment. The environments considered so far, oracles, data bases, and quantum registers, are seen to be special cases of environments considered here. It is also seen that a quantum robot should include a quantum computer and cannot be simply a multistate head. A model of quantum robots and their interactions is discussed in which each task, as a sequence of alternating computation and action phases,is described by a unitary single time step operator T {approx} T{sub a} + T{sub c} (discrete space and time are assumed). The overall system dynamics is described as a sum over paths of completed computation (T{sub c}) and action (T{sub a}) phases. A simple example of a task, measuring the distance between the quantum robot and a particle on a 1D lattice with quantum phase path dispersion present, is analyzed. A decision diagram for the task is presented and analyzed.
Date: July 23, 1998
Creator: Benioff, P.
Object Type: Article
System: The UNT Digital Library
LLNL Middle East and North Africa research database (open access)

LLNL Middle East and North Africa research database

The Lawrence Livermore National Laboratory (LLNL) Comprehensive Nuclear-Test-Ban Treaty Research and Development (CTBT R and D) program has made significant progress populating a comprehensive seismic research database (RDB) for seismic events and derived research products in the Middle East and North Africa (MENA). Our original ME/NA study region has enlarged and is now defined as an area including the Middle East, Africa, Europe, Southwest Asia, the Former Soviet Union and the Scandinavian/Arctic region. The LLNL RDB will facilitate calibration of all International Monitoring System (IMS) stations (primary and auxiliary) or their surrogates (if not yet installed) as well as a variety of gamma stations. The RDB provides not only a coherent framework in which to store and organize large volumes of collected seismic waveforms and associated event parameter information, but also provides an efficient data processing/research environment for deriving location and discrimination correction sur faces and capabilities. In order to accommodate large volumes of data from many sources with diverse formats the RDB is designed to be flexible and extensible in addition to maintaining detailed quality control information and associated metadata. Station parameters, instrument responses, phase pick information, and event bulletins were compiled and made available through the RDB. For …
Date: July 23, 1999
Creator: Dodge, D.; Hauk, T.; Moore, R. M.; O'Boyle, J. & Ruppert, S.
Object Type: Article
System: The UNT Digital Library
Tank 241-U-105 push mode core sampling and analysis plan. Revision 1 (open access)

Tank 241-U-105 push mode core sampling and analysis plan. Revision 1

This document reports the core sampling and analysis event for tank 241-U-105
Date: October 23, 1995
Creator: Bell, K. E.
Object Type: Report
System: The UNT Digital Library
Contaminant Uptake and Demography of the Loggerhead Shrike (Lanius ludovicianus) at the Lawrence Livermore National Laboratory, Site 300 (open access)

Contaminant Uptake and Demography of the Loggerhead Shrike (Lanius ludovicianus) at the Lawrence Livermore National Laboratory, Site 300

Concentrations of eleven potential environmental contaminants (metals) in the blood and retrice feathers of fledged-Hatch Year and adult loggerhead shrikes (Lanius ludovicianus) were examined at Lawrence Livermore National Laboratory's Site 300 and a control site, in San Joaquin and Contra Costa Counties, California. The purpose of this pilot study was to determine, through non-lethal means, if loggerhead shrikes are exposed to metals at Site 300 and whether specific demographic variables (i.e., clutch size, fledgling success, etc.) are affected. Loggerhead shrikes at Site 300 had higher blood concentrations of metals, especially birds on the west side of the site, when compared to control site birds. Metal concentrations in the feathers of control site birds tended to be higher than Site 300 shrikes. Blood concentrations of metals in loggerhead shrikes from both Site 300 and the control site were well below the Most Tolerant Dietary Level (MTDL) for domestic birds for all metals except selenium. Clutch size was similar to other populations but one deformed embryo was discovered in a failed egg. The results of this pilot study suggest further work is needed to understand possible synergistic effects related to other contaminants of concern found at Site 300 and overall population variability.
Date: February 23, 2005
Creator: van Hattem, M G & Santolo, G
Object Type: Report
System: The UNT Digital Library
Dissemination of Climate Model Output to the Public and Commercial Sector (open access)

Dissemination of Climate Model Output to the Public and Commercial Sector

Climate is defined by the Glossary of Meteorology as the mean of atmospheric variables over a period of time ranging from as short as a few months to multiple years and longer. Although the term climate is often used to refer to long-term weather statistics, the broader definition of climate is the time evolution of a system consisting of the atmosphere, hydrosphere, lithosphere, and biosphere. Physical, chemical, and biological processes are involved in interactions among the components of the climate system. Vegetation, soil moisture, and glaciers are part of the climate system in addition to the usually considered temperature and precipitation (Pielke, 2008). Climate change refers to any systematic change in the long-term statistics of climate elements (such as temperature, pressure, or winds) sustained over several decades or longer. Climate change can be initiated by external forces, such as cyclical variations in the Earth's solar orbit that are thought to have caused glacial and interglacial periods within the last 2 million years (Milankovitch, 1941). However, a linear response to astronomical forcing does not explain many other observed glacial and interglacial cycles (Petit et al., 1999). It is now understood that climate is influenced by the interaction of solar radiation with …
Date: September 23, 2010
Creator: Robert Stockwell, PhD
Object Type: Report
System: The UNT Digital Library
Carboxysomal carbonic anhydrases: Structure and role in microbial CO2 fixation (open access)

Carboxysomal carbonic anhydrases: Structure and role in microbial CO2 fixation

Cyanobacteria and some chemoautotrophic bacteria are able to grow in environments with limiting CO2 concentrations by employing a CO2-concentrating mechanism (CCM) that allows them to accumulate inorganic carbon in their cytoplasm to concentrations several orders of magnitude higher than that on the outside. The final step of this process takes place in polyhedral protein microcompartments known as carboxysomes, which contain the majority of the CO2-fixing enzyme, RubisCO. The efficiency of CO2 fixation by the sequestered RubisCO is enhanced by co-localization with a specialized carbonic anhydrase that catalyzes dehydration of the cytoplasmic bicarbonate and ensures saturation of RubisCO with its substrate, CO2. There are two genetically distinct carboxysome types that differ in their protein composition and in the carbonic anhydrase(s) they employ. Here we review the existing information concerning the genomics, structure and enzymology of these uniquely adapted carbonic anhydrases, which are of fundamental importance in the global carbon cycle.
Date: June 23, 2010
Creator: Cannon, Gordon C.; Heinhorst, Sabine & Kerfeld, Cheryl A.
Object Type: Article
System: The UNT Digital Library