United States Postal Service: Opportunities to Strengthen IT Investment Management Capabilities (open access)

United States Postal Service: Opportunities to Strengthen IT Investment Management Capabilities

A chapter report issued by the General Accounting Office with an abstract that begins "The U.S. Postal Service invests hundreds of millions of dollars in information technology (IT) each year to support its mission of providing prompt, reliable, and efficient mail service to all areas of the country. It must support these operations through the revenues it earns for its services. Growing operating expenses and capital needs in the face of reduced revenues highlight the need for the Postal Service to invest its IT dollars wisely. Accordingly, the Senate Committee on Governmental Affairs and its Subcommittee on International Security, Proliferation, and Federal Services asked GAO to evaluate how well the Postal Service manages its IT investments."
Date: October 15, 2002
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Defense Management: Munitions Requirements and Combatant Commanders' Needs Require Linkage (open access)

Defense Management: Munitions Requirements and Combatant Commanders' Needs Require Linkage

A letter report issued by the General Accounting Office with an abstract that begins "The Department of Defense (DOD) planned to spend $7.9 billion on acquiring munitions in fiscal year 2002. Ongoing military operations associated with the global war on terrorism have heightened concerns about the unified combatant commands having sufficient quantities of munitions. Since 1994, the DOD Inspector General and GAO have issued numerous reports identifying weaknesses and expressing concerns about the accuracy of the process used by the department to determine munitions requirements. DOD has improved its munitions requirements process by eliminating most of the systematic problems--correcting questionable and inconsistently applied data, completing target templates, and resolving issues involving the level of detail that should be included in planning guidance. However, a fundamental problem remains unaddressed--inadequate linkage between the near-term munitions needs of the combatant commands and the purchases made by the military services based on computations derived from the department's munitions requirement determination process. The department's munitions requirements process provides varied answers for current munitions acquisitions questions because of the aforementioned disjunction. As a result, the services, in the short term, are purchasing some critically needed munitions based on available funding and contractors' production capacity. Although this …
Date: October 15, 2002
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Telecommunications: Issues in Providing Cable and Satellite Television Services (open access)

Telecommunications: Issues in Providing Cable and Satellite Television Services

A letter report issued by the General Accounting Office with an abstract that begins "Direct broadcast satellite (DBS) television service has grown to become the principal competitor to cable television systems. In October 2001, the two primary DBS companies, EchoStar and DirecTV, proposed a merger plan that is pending before the Department of Justice and that the Federal Communications Commission (FCC) recently announced that it had declined to approve. GAO was asked to examine several issues related to competition in providing subscription video services, including the competitive impact of the availability of cable modem Internet access, and the effects on cable prices and DBS penetration rates of DBS' offering local broadcast channels. GAO also examined the technical capability of the individual DBS companies to expand local channel services into more television markets. This report offers no opinion on the merits of the proposed merger."
Date: October 15, 2002
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Financial Management: Survey of Capitalization Threshold and Other Policies for Property, Plant, and Equipment (open access)

Financial Management: Survey of Capitalization Threshold and Other Policies for Property, Plant, and Equipment

A letter report issued by the General Accounting Office with an abstract that begins "In passing the 1990 Chief Financial Officers Act and a range of other financial management reform legislation, Congress has sought to overcome the historical lack of reliable, useful, and timely information with which to make informed decisions, measure and control costs, manage for results, and ensure financial accountability on an ongoing basis. Reported capitalization threshold levels at the 14 agencies GAO surveyed ranged from zero to $250,000. Despite the sharp increase in the capitalization threshold, all but one of the 14 agencies responded that they maintained property records for the government's general property, plant, and equipment (PP&E) not capitalized on the balance sheet, citing safeguarding of PP&E and supporting agency operations as the key reasons for maintaining such information. Federal capitalization thresholds are significantly higher than those reported by the private sector entities GAO surveyed. In some cases, the federal capitalization thresholds for real property were up to 50 times higher than those noted in the private sector. In contrast to the wide variance between federal agency and private sector capitalization threshold policies, federal agency useful life policies were generally similar to those found in the …
Date: October 15, 2002
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Global Expression Studies of Yersinia Pestis Pathogenicity (open access)

Global Expression Studies of Yersinia Pestis Pathogenicity

The aim of these studies continues to be the investigation into the molecular mechanisms that underlie the virulence process in Yersinia pestis. In particular, the focus of this work centers on the identification of novel genes and pathways responsible for the pathogenic properties of this organism. In spite of more than four decades of intense investigation in this field, the dilemma as to what makes Y. pestis such a virulent and lethal pathogen remains unanswered. The method being employed makes use microarray technology (DNA chip) that enables the examination of the global activities of the whole complement of genes in this pathogen. Two primary resources available to the investigators (one directly obtained from a separate CBNP-funded project) make these studies possible: (1) Whole genome comparisons of the genes in Y. pestis and its near neighbors with attenuated or non pathogenic characteristics, and (2) the ability to duplicate in vitro, conditions that mimic the infection process of this pathogen. This year we have extended our studies from the original work of characterizing the global transcriptional regulation in Y. pestis triggered during temperature transition from 26 C to 37 C (roughly conditions found in the flea vector and the mammalian host, respectively) …
Date: October 15, 2002
Creator: Garcia, E; Motin, V; Brubaker, R & Fitch, P
System: The UNT Digital Library
Evaluation of Roof Bolting Requirements Based on In-Mine Bolter Drilling Progress Report (open access)

Evaluation of Roof Bolting Requirements Based on In-Mine Bolter Drilling Progress Report

Roof bolting is the most popular method for underground openings in the mining industry, especially in the bedded deposits such as coal, potash, salt etc. In fact, all U.S. underground coal mine entries are roof-bolted as required by law. However, roof falls still occur frequently in the roof bolted entries. The two possible reasons are: the lack of knowledge of and technology to detect the roof geological conditions in advance of mining, and lack of roof bolting design criteria for modern roof bolting systems. This research is to develop a method for predicting the roof geology and stability condition in real time during roof bolting operation. Based on such information, roof bolting design criteria for modern roof bolting systems will be developed for implementation in real time. Additional field tests have been performed in this quarter. The development of the data interpretation methodology and other related tasks are still continuing.
Date: October 15, 2002
Creator: Peng, Syd S.
System: The UNT Digital Library
Tank 41 Movable Pump System Material Compatibility Report (open access)

Tank 41 Movable Pump System Material Compatibility Report

This report is a compilation of the communications during the design phase regarding material compatibility.
Date: October 15, 2002
Creator: Crosby, S.
System: The UNT Digital Library
The National Spherical Torus Experiment (NSTX) Research Program and Progress Towards High Beta, Long Pulse Operating Scenarios (open access)

The National Spherical Torus Experiment (NSTX) Research Program and Progress Towards High Beta, Long Pulse Operating Scenarios

A major research goal of the National Spherical Torus Experiment is establishing long-pulse, high-beta, high-confinement operation and its physics basis. This research has been enabled by facility capabilities developed over the last two years, including neutral-beam (up to 7 MW) and high-harmonic fast-wave heating (up to 6 MW), toroidal fields up to 6 kG, plasma currents up to 1.5 MA, flexible shape control, and wall preparation techniques. These capabilities have enabled the generation of plasmas with <beta {sub T}> up to 35%. Normalized beta values often exceed the no wall limit, and studies suggest that passive wall mode stabilization is enabling this for broad pressure profiles characteristic of H-mode plasmas. The viability of long, high bootstrap-current fraction operations has been established for ELMing H-mode plasmas with toroidal beta values in excess of 15% and sustained for several current relaxation times. Improvements in wall conditioning and fueling are likely contributing to a reduction in H-mode power thresholds. Electron thermal conduction is the dominant thermal loss channel in auxiliary-heated plasmas examined thus far. High-harmonic fast-wave (HHFW) effectively heats electrons, and its acceleration of fast beam ions has been observed. Evidence for HHFW current drive is by comparing of the loop voltage evolution …
Date: October 15, 2002
Creator: Synakowski, E. J.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W. et al.
System: The UNT Digital Library
Enhanced Conversion of Thermal Electron Bernstein Waves to the Extraordinary Electromagnetic Mode on the National Spherical Torus Experiment (NSTX) (open access)

Enhanced Conversion of Thermal Electron Bernstein Waves to the Extraordinary Electromagnetic Mode on the National Spherical Torus Experiment (NSTX)

A four-fold increase in the conversion of thermal electron-Bernstein waves (EBW) to the extraordinary mode (X-mode) was measured when the density scale length (L subscript ''n'') was progressively shortened by a local Boron nitride limiter in the scrape-off of an ohmically heated National Spherical Torus Experiment (NSTX) plasma [M. Ono, S. Kaye, M. Peng, et al., Proceedings 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol. 3, p. 1135]. The maximum conversion efficiency approached 50% when L subscript ''n'' was reduced to 0.7 cm, in agreement with theoretical predictions that used locally measured L subscript ''n''. Calculations indicate that it is possible to establish L subscript ''n'' < 0.3 cm with a local limiter, a value predicted to attain approximately 100% EBW conversion to the X-mode in support of proposed EBW heating and current drive scenarios.
Date: October 15, 2002
Creator: Taylor, G.; Efthimion, P. C.; Jones, B.; LeBlanc, B. P.; Wilson, J. R.; Wilgen, J. B. et al.
System: The UNT Digital Library
Measurements of Prompt and MHD-Induced Fast Ion Loss from National Spherical Torus Experiment Plasmas (open access)

Measurements of Prompt and MHD-Induced Fast Ion Loss from National Spherical Torus Experiment Plasmas

A range of effects may make fast ion confinement in spherical tokamaks worse than in conventional aspect ratio tokamaks. Data from neutron detectors, a neutral particle analyzer, and a fast ion loss diagnostic on the National Spherical Torus Experiment (NSTX) indicate that neutral beam ion confinement is consistent with classical expectations in quiescent plasmas, within the {approx}25% errors of measurement. However, fast ion confinement in NSTX is frequently affected by magnetohydrodynamic (MHD) activity, and the effect of MHD can be quite strong.
Date: October 15, 2002
Creator: Darrow, D. S.; Medley, S. S.; Roquemore, A. L.; Heidbrink, W. W.; Alekseyev, A.; Cecil, F. E. et al.
System: The UNT Digital Library
BOILER MATERIALS FOR ULTRASUPERCRITICAL COAL POWER PLANTS (open access)

BOILER MATERIALS FOR ULTRASUPERCRITICAL COAL POWER PLANTS

The principal objective of this project is to develop materials technology for use in ultrasupercritical (USC) plant boilers capable of operating with 760 C (1400 F), 35 MPa (5000 psi) steam. In the 21st century, the world faces the critical challenge of providing abundant, cheap electricity to meet the needs of a growing global population while at the same time preserving environmental values. Most studies of this issue conclude that a robust portfolio of generation technologies and fuels should be developed to assure that the United States will have adequate electricity supplies in a variety of possible future scenarios. The use of coal for electricity generation poses a unique set of challenges. On the one hand, coal is plentiful and available at low cost in much of the world, notably in the U.S., China, and India. Countries with large coal reserves will want to develop them to foster economic growth and energy security. On the other hand, traditional methods of coal combustion emit pollutants and CO{sub 2} at high levels relative to other generation options. Maintaining coal as a generation option in the 21st century will require methods for addressing these environmental issues. This project has established a government/industry consortium …
Date: October 15, 2002
Creator: Viswanathan, R. & Coleman, K.
System: The UNT Digital Library
Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions (open access)

Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions

The principal objective of the project is to develop an acoustic probe for determining the weight fraction of particles in a flowing suspension. The suspension can be solid-liquid (S-L) or solid-gas-liquid (S-G-L). The work will include testing the theory of acoustic wave propagation in suspensions and demonstrating the application of the probe by installing it on a flow loop through which a suspension is flowing and determining the particle weight fraction. The signal from the probe must be processed such that the noise arising from the presence of gas bubbles is removed to yield an accurate estimate of the particle weight fraction. Particular attention will be given to testing suspensions with low particle weight fractions since slurries to be transported in nuclear waste processing will have low particle weight fractions. Originally, the probe was to be developed and tested at Syracuse University (SU) then installed and tested at Oak Ridge National Laboratories (ORNL) for surrogate slurries from the Hanford Nuclear site. However, after discussions between SU and ORNL in June 2002 it was agreed that all tests would be conducted at SU.
Date: October 15, 2002
Creator: Tavlarides, L. L.; Sangani, A.; Shcherbakov, A.; Lee, J. S. & Dievendorf, E.
System: The UNT Digital Library
Equilibria and Stability of JET Discharges with Zero Core Current Density (open access)

Equilibria and Stability of JET Discharges with Zero Core Current Density

Injection of Lower Hybrid Heating and Current Drive (LHCD) into the current ramp-up phase of JET [Joint European Torus] discharges can produce extremely reversed q-profiles characterized by a core region of near zero current density (within Motional Stark Effect diagnostic measurement errors). Non-inductive, off-axis co-current drive induces a back electromotive force inside the non-inductive current radius that drives a negative current in the plasma core. The core current density does not go negative, although current diffusion calculations indicate that there is sufficient LHCD to cause this. The clamping of the core current density near zero is consistent with n=0 reconnection events redistributing the core current soon after it goes negative. This is seen in reduced MHD simulations and in nonlinear resistive MHD simulations which predict that these discharges undergo n=0 reconnection events that clamp the core current near zero.
Date: October 15, 2002
Creator: Stratton, B. C.; Hawkes, N. C.; Huysmans, G. T. A.; Breslau, J. A.; Zakharov, L. E.; Alper, B. et al.
System: The UNT Digital Library
Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 2001 Annual Report (open access)

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 2001 Annual Report

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including concentrations of carbon dioxide (CO{sub 2}) and other radiatively active gases in the atmosphere; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; emissions of CO{sub 2} and other trace gases to the atmosphere; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels. CDIAC is located within the Environmental Sciences Division (ESD) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. CDIAC is co-located with ESD researchers investigating global-change topics, such as the global carbon cycle and the effects …
Date: October 15, 2002
Creator: Cushman, R.M.
System: The UNT Digital Library
Active flow control for maximizing performance of spark ignited stratified charge engines. Final report (open access)

Active flow control for maximizing performance of spark ignited stratified charge engines. Final report

Reducing the cycle-to-cycle variability present in stratified-charge engines is an important step in the process of increasing their efficiency. As a result of this cycle-to-cycle variability, fuel injection systems are calibrated to inject more fuel than necessary, in an attempt to ensure that the engines fire on every cycle. When the cycle-to-cycle variability is lowered, the variation of work per cycle is reduced and the lean operating limit decreases, resulting in increased fuel economy. In this study an active flow control device is used to excite the intake flow of an engine at various frequencies. The goal of this excitation is to control the way in which vortices shed off of the intake valve, thus lowering the cycle-to-cycle variability in the flow field. This method of controlling flow is investigated through the use of three engines. The results of this study show that the active flow control device did help to lower the cycle-to-cycle variability of the in-cylinder flow field; however, the reduction did not translate directly into improved engine performance.
Date: October 15, 2002
Creator: Fedewa, Andrew; Stuecken, Tom; Timm, Edward; Schock, Harold J.; Shih, Tom-I.P.; Koochesfahani, Manooch et al.
System: The UNT Digital Library
Selecting Compositions for Phase 1 of the Product Consistency Test (PCT) Assessment Study (open access)

Selecting Compositions for Phase 1 of the Product Consistency Test (PCT) Assessment Study

The purpose of this task is to generate the glass property/composition data and model necessary for enhancing operational processing windows. This effort is intended to be both generally applicable to all Department of Energy (DOE) High-Level Waste (HLW) glasses and specific to individual waste processing plants such as the DWPF and the planned High-Level and Low Activity Waste (HLW and LAW) plants at Hanford. Phase 1 consists of determining the glass compositional region where the existing durability model is not dependable in identifying durable glasses. Phase 2 will be devoted to developing a method of ensuring that durable glass compositions are not excluded from processing.
Date: October 15, 2002
Creator: Cozzi, A.D.
System: The UNT Digital Library
Airport Finance: Using Airport Grant Funds for Security Projects Has Affected Some Development Projects (open access)

Airport Finance: Using Airport Grant Funds for Security Projects Has Affected Some Development Projects

A letter report issued by the General Accounting Office with an abstract that begins "The events of September 11, 2001 created several new challenges for the aviation industry in ensuring the safety and security of the national airport system. Chief among them is deciding to what extent Airport Improvement Program (AIP) grant funds should be used to finance the new security requirements at the nation's airports. Although many in the aviation industry believe that funding security projects has become even more important in the aftermath of September 11, they also recognize the need to continue funding other airport development projects, such as those designed to enhance capacity in the national airport system. During fiscal year 2002, the Federal Aviation Association (FAA) awarded a total of $561 million, 17 percent of the $3.3 billion available for grants, in AIP grant funds to airports for security projects related to the events of September 11, 2001. This amount is the largest amount awarded to airports for security projects in a single year since the program began in 1982. Based on data provided by FAA, all of the security projects funded with AIP grants since the events of September 11, 2001, met the legislative …
Date: October 15, 2002
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Oboe Transparency Results - Oboes 1-9 (open access)

Oboe Transparency Results - Oboes 1-9

The motivation for the ''Transparency'' experiment is that DOE/DP would like to have data available to show to interested parties, such as the JASONs. The U1a subcritical experiments are consistent with U.S. policy on nuclear testing. This would be done in a spirit of ''Transparency'' if doubts should arise. Thus, the objective of the ''Transparency'' measurements on the Oboe series is to place an upper bound on the nuclear energy released in the subcritical experiments. Two separate experimental packages cover the transparency measurement issue thoroughly. These are: (1) Neutron Track-Etch Dosimetry. (2) Scintillator Fission Neutron/Gamma Rate Measurement. Because the containment barrier is only 1-inch steel, plus 6-inch shotcrete, it is quite transparent to fission neutrons and, thus, both experiments can be mounted outside the containment barrier and can be recovered post shot. An additional group of dosimeters was placed on the lid of the vessel for greater sensitivity.
Date: October 15, 2002
Creator: Heinle, R A
System: The UNT Digital Library
On Line Spectrophotometric Measurement of Uranium and Nitrate in H Canyon (open access)

On Line Spectrophotometric Measurement of Uranium and Nitrate in H Canyon

This report describes the on-line instrumentation developed by the Analytical Development Section of Savannah River Technology Center in support of Highly Enriched Uranium Blend Down processing in H Canyon.
Date: October 15, 2002
Creator: Lascola, R.J.
System: The UNT Digital Library
Discovery of Disposal of Low-Level Waste in Slit Trench Segments Shallower than Analyzed in Performance Assessment (open access)

Discovery of Disposal of Low-Level Waste in Slit Trench Segments Shallower than Analyzed in Performance Assessment

The effect of disposing of low-level waste in slit trenches that are shallower than those analyzed in the revised performance assessment for the E-Area low-level waste facility is evaluated. The conclusion of the evaluation is that such disposal is bounded by the performance assessment if all of the disposed waste packages meet the slit trench Waste Acceptance Criteria and if at least four feet of soil is placed over the disposed waste packages.
Date: October 15, 2002
Creator: Cook, J. R.
System: The UNT Digital Library
Analysis of Tank 43H Samples at the Conclusion of Uranyl Carbonate Addition (open access)

Analysis of Tank 43H Samples at the Conclusion of Uranyl Carbonate Addition

Tank 43H serves as the feed Tank to the 2H evaporator. In the months of July and August 2001, about 21,000 gallons of a depleted uranyl carbonate solution were added to Tank 43H and agitated with two Flygt mixers. The depleted uranium addition served to decrease the U-235 enrichment in the Tank 43H supernate so that the supernate could be evaporated with no risk of accumulating enriched uranium.
Date: October 15, 2002
Creator: Oji, L.N.
System: The UNT Digital Library
Impact of Water pH on Zebra Mussel Mortality (open access)

Impact of Water pH on Zebra Mussel Mortality

The experiments conducted this past quarter have suggested that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels throughout the entire range of pH values tested (7.2 to 8.6). Highest mortality was achieved at pH values characteristic of preferred zebra mussel waterbodies, i.e., hard waters with a range of 7.8 to 8.6. In all water types tested, however, ranging from very soft to very hard, considerable mussel kill was achieved (83 to 99% mean mortality), suggesting that regardless of the pH or hardness of the treated water, significant mussel kill can be achieved upon treatment with P. fluorescens strain CL0145A. These results further support the concept that this bacterium has significant potential for use as a zebra mussel control agent in power plant pipes receiving waters with a wide range of physical and chemical characteristics.
Date: October 15, 2002
Creator: Molloy, Daniel P.
System: The UNT Digital Library
Liquid Lithium Limiter Effects on Tokamak Plasmas and Plasma-Liquid Surface Interactions (open access)

Liquid Lithium Limiter Effects on Tokamak Plasmas and Plasma-Liquid Surface Interactions

We present results from the first experiments with a large area liquid lithium limiter in a magnetic fusion device, and its effect on improving plasma performance by reducing particle recycling. Using large area liquid metal surfaces in any major fusion device is unlikely before a test on a smaller scale. This has motivated its demonstration in the CDX-U spherical torus with a unique, fully toroidal lithium limiter. The highest current discharges were obtained with a liquid lithium limiter. There was a reduction in recycling, as indicated by a significant decrease in the deuterium-alpha emission and oxygen radiation. How these results might extrapolate to reactors is suggested in recycling/retention experiments with liquid lithium surfaces under high-flux deuterium and helium plasma bombardment in PISCES-B. Data on deuterium atoms retained in liquid lithium indicate retention of all incident ions until full volumetric conversion to lithium deuteride. The PISCES-B results also show a material loss mechanism that lowers the maximum operating temperature compared to that for the liquid surface equilibrium vapor pressure. This may restrict the lithium temperature in reactors.
Date: October 15, 2002
Creator: Kaita, R.; Majeski, R.; Doerner, R.; Antar, G.; Baldwin, M.; Conn, R. et al.
System: The UNT Digital Library
The Geologic Basis for Volcanic Hazard Assessment for the Proposed High-Level Radioactive Waste Repository at Yucca Mountain, Nevada (open access)

The Geologic Basis for Volcanic Hazard Assessment for the Proposed High-Level Radioactive Waste Repository at Yucca Mountain, Nevada

Studies of volcanic risk to the proposed high-level radioactive waste repository at Yucca Mountain have been ongoing for 25 years. These studies are required because three episodes of small-volume, alkalic basaltic volcanism have occurred within 50 km of Yucca Mountain during the Quaternary. Probabilistic hazard estimates for the proposed repository depend on the recurrence rate and spatial distribution of past episodes of volcanism in the region. Several independent research groups have published estimates of the annual probability of a future volcanic disruption of the proposed repository, most of which fall in the range of 10{sup -7} to 10{sup -9} per year; similar conclusions were reached. through an extensive expert elicitation sponsored by the Department of Energy in 1995-1996. The estimated probability values are dominated by a regional recurrence rate of 10{sup -5} to 10{sup -6} volcanic events per year (equating to recurrence intervals of several hundred thousand years). The recurrence rate, as well as the spatial density of volcanoes, is low compared to most other basaltic volcanic fields in the western United States, factors that may be related to both the tectonic history of the region and a lithospheric mantle source that is relatively cold and not prone to melting. …
Date: October 15, 2002
Creator: Perry, F.
System: The UNT Digital Library