Interpretation of Recent Temperature Trends in California (open access)

Interpretation of Recent Temperature Trends in California

Regional-scale climate change and associated societal impacts result from large-scale (e.g. well-mixed greenhouse gases) and more local (e.g. land-use change) 'forcing' (perturbing) agents. It is essential to understand these forcings and climate responses to them, in order to predict future climate and societal impacts. California is a fine example of the complex effects of multiple climate forcings. The State's natural climate is diverse, highly variable, and strongly influenced by ENSO. Humans are perturbing this complex system through urbanization, irrigation, and emission of multiple types of aerosols and greenhouse gases. Despite better-than-average observational coverage, we are only beginning to understand the manifestations of these forcings in California's temperature record.
Date: September 21, 2007
Creator: Duffy, P B; Bonfils, C & Lobell, D
Object Type: Article
System: The UNT Digital Library
Microscopic Approaches to Nuclear Structure: Configuration Interaction (open access)

Microscopic Approaches to Nuclear Structure: Configuration Interaction

The configuration interaction (CI) approach to solving the nuclear many-body problem, also known as the interacting shell model, has proven to be powerful tool in understanding the structure of nuclei. The principal criticism of past applications of the shell model is the reliance on empirical tuning to interaction matrix elements. If an accurate description of nuclei far from the valley of stability, where little or no data is available, a more fundamental approach is needed. This starts with recent ab initio approaches with effective interactions in the no-core shell model (NCSM). Using effective-field theory for guidance, fully ab initio descriptions of nuclei up to {sup 16}O with QCD based NN, NNN, and NNNN interactions will be possible within the next five years. An important task is then to determine how to use these NCSM results to develop effective interactions to describe heavier nuclei without the need to resort to an empirical retuning with every model space. Thus, it is likely that more traditional CI applications utilizing direct diagonalization and more fundamental interactions will be applicable to nuclei with perhaps up to one hundred constituents. But, these direct diagonalization CI applications will always be computationally limited due to the rapid increase …
Date: September 21, 2007
Creator: Ormand, W E
Object Type: Article
System: The UNT Digital Library
Negative Transconductance in Apertured Electron Guns (open access)

Negative Transconductance in Apertured Electron Guns

Passing an electron beam through an aperture can serve to reduce the beam current or change the transverse beam profile. For a sufficiently intense beam, space charge will drive a radial expansion of the beam, which may cause the current passing through the aperture to increase even though the current arriving at the aperture is decreasing. When a gridded electron gun is used, this may be expressed by stating that the transconductance of the apertured gun is negative. Here we explain this effect, and explore some of the key factors governing when it can occur and influencing its strength.
Date: September 21, 2007
Creator: Harris, J R & O'Shea, P G
Object Type: Article
System: The UNT Digital Library
Soil Sampling to Demonstrate Compliance with Department of Energy Radiological Clearance Requirements for the McGee Ranch-Riverlands and North Slope Units of the Hanford Reach National Monument (open access)

Soil Sampling to Demonstrate Compliance with Department of Energy Radiological Clearance Requirements for the McGee Ranch-Riverlands and North Slope Units of the Hanford Reach National Monument

The Hanford Reach National Monument (HRNM) was created by presidential proclamation in 2000. It is located along the Columbia River in south central Washington and consists of five distinct units. The McGee Ranch-Riverlands and the North Slope units are addressed in this report. North Slope refers to two of the HRNM units: the Saddle Mountain Unit and the Wahluke Slope Unit. The Saddle Mountain and Wahluke Slope Units are located north of the Columbia River, while the McGee Ranch-Riverlands Unit is located south of the Columbia River and north and west of Washington State Highway 24. To fulfill internal U.S. Department of Energy (DOE) requirements prior to any radiological clearance of land, the DOE must evaluate the potential for residual radioactive contamination on this land and determine compliance with the requirements of DOE Order 5400.5. Authorized limits for residual radioactive contamination were developed based on the DOE annual exposure limit to the public (100 mrem) using future potential land-use scenarios. The DOE Office of Environmental Management approved these authorized limits on March 1, 2004. Historical soil monitoring conducted on and around the HRNM indicated soil concentrations of radionuclides were well below the authorized limits (Fritz et al. 2003). However, the …
Date: September 21, 2007
Creator: Fritz, Brad G.; Dirkes, Roger L. & Napier, Bruce A.
Object Type: Report
System: The UNT Digital Library
Kansas Advanced Semiconductor Project (open access)

Kansas Advanced Semiconductor Project

KASP (Kansas Advanced Semiconductor Project) completed the new Layer 0 upgrade for D0, assumed key electronics projects for the US CMS project, finished important new physics measurements with the D0 experiment at Fermilab, made substantial contributions to detector studies for the proposed e+e- international linear collider (ILC), and advanced key initiatives in non-accelerator-based neutrino physics.
Date: September 21, 2007
Creator: Baringer, P.; Bean, A.; Bolton, T.; Horton-Smith, G.; Maravin, Y.; Ratra, B. et al.
Object Type: Report
System: The UNT Digital Library
DOE-DARPA High-Performance Corrosion-Resistant Materials (HPCRM), Annual HPCRM Team Meeting & Technical Review (open access)

DOE-DARPA High-Performance Corrosion-Resistant Materials (HPCRM), Annual HPCRM Team Meeting & Technical Review

The overall goal is to develop high-performance corrosion-resistant iron-based amorphous-metal coatings for prolonged trouble-free use in very aggressive environments: seawater & hot geothermal brines. The specific technical objectives are: (1) Synthesize Fe-based amorphous-metal coating with corrosion resistance comparable/superior to Ni-based Alloy C-22; (2) Establish processing parameter windows for applying and controlling coating attributes (porosity, density, bonding); (3) Assess possible cost savings through substitution of Fe-based material for more expensive Ni-based Alloy C-22; (4) Demonstrate practical fabrication processes; (5) Produce quality materials and data with complete traceability for nuclear applications; and (6) Develop, validate and calibrate computational models to enable life prediction and process design.
Date: September 21, 2007
Creator: Farmer, J; Brown, B; Bayles, B; Lemieux, T; Choi, J; Ajdelsztajn, L et al.
Object Type: Report
System: The UNT Digital Library
Design, Construction, Alignment, and Calibration of a Compact Velocimetry Experiment (open access)

Design, Construction, Alignment, and Calibration of a Compact Velocimetry Experiment

A velocimetry experiment has been designed to measure shock properties for small cylindrical metal targets (8-mm-diameter by 2-mm thick). A target is accelerated by high explosives, caught, and retrieved for later inspection. The target is expected to move at a velocity of 0.1 to 3 km/sec. The complete experiment canister is approximately 105 mm in diameter and 380 mm long. Optical velocimetry diagnostics include the Velocity Interferometer System for Any Reflector (VISAR) and Photon Doppler Velocimetry (PDV). The packaging of the velocity diagnostics is not allowed to interfere with the catchment or an X-ray imaging diagnostic. A single optical relay, using commercial lenses, collects Doppler-shifted light for both VISAR and PDV. The use of fiber optics allows measurement of point velocities on the target surface during accelerations occurring over 15 mm of travel. The VISAR operates at 532 nm and has separate illumination fibers requiring alignment. The PDV diagnostic operates at 1550 nm, but is aligned and focused at 670 nm. The VISAR and PDV diagnostics are complementary measurements and they image spots in close proximity on the target surface. Because the optical relay uses commercial glass, the axial positions of the optical fibers for PDV and VISAR are offset …
Date: September 21, 2007
Creator: Kaufman, Morris I.; Malone, Robert M.; Frogget, Brent C.; Esquibel, David L.; Romero, Vincent T.; Lare, Gregory A. et al.
Object Type: Article
System: The UNT Digital Library
The IceCube Data Acquisition Software: Lessons Learned during Distributed, Collaborative, Multi-Disciplined Software Development. (open access)

The IceCube Data Acquisition Software: Lessons Learned during Distributed, Collaborative, Multi-Disciplined Software Development.

In this experiential paper we report on lessons learned during the development ofthe data acquisition software for the IceCube project - specifically, how to effectively address the unique challenges presented by a distributed, collaborative, multi-institutional, multi-disciplined project such as this. While development progress in software projects is often described solely in terms of technical issues, our experience indicates that non- and quasi-technical interactions play a substantial role in the effectiveness of large software development efforts. These include: selection and management of multiple software development methodologies, the effective useof various collaborative communication tools, project management structure and roles, and the impact and apparent importance of these elements when viewed through the differing perspectives of hardware, software, scientific and project office roles. Even in areas clearly technical in nature, success is still influenced by non-technical issues that can escape close attention. In particular we describe our experiences on software requirements specification, development methodologies and communication tools. We make observations on what tools and techniques have and have not been effective in this geographically disperse (including the South Pole) collaboration and offer suggestions on how similarly structured future projects may build upon our experiences.
Date: September 21, 2007
Creator: Beattie, Keith S.; Beattie, Keith; Day, Christopher; Glowacki, Dave; Hanson, Kael; Jacobsen, John et al.
Object Type: Article
System: The UNT Digital Library
Evaluation of Salmon Spawning Below Bonneville Dam, Annual Report October 2005 - September 2006. (open access)

Evaluation of Salmon Spawning Below Bonneville Dam, Annual Report October 2005 - September 2006.

Since FY 2000, scientists at Pacific Northwest National Laboratory (PNNL) have conducted research to assess the extent of spawning by chum salmon (Oncorhynchus keta) and fall Chinook salmon (O. tshawytscha) in the lower mainstem Columbia River. Their work supports a larger project funded by the Bonneville Power Administration (BPA) aimed at characterizing the physical habitat used by mainstem fall Chinook and chum salmon populations. Multiple collaborators in addition to PNNL are involved in the BPA project--counterparts include the Washington Department of Fish and Wildlife (WDFW), U.S. Fish and Wildlife Service (USFWS), Pacific States Marine Fisheries Commission (PSMFC), U.S. Geological Survey (USGS), and Oregon Department of Fish and Wildlife (ODFW). Data resulting from the individual tasks each agency conducts are providing a sound scientific basis for developing strategies to operate the Federal Columbia River Power System (FCRPS) in ways that will effectively protect and enhance the chum and tule fall Chinook salmon populations--both listed as threatened under the Endangered Species Act (ESA). Fall Chinook salmon, thought to originate from Bonneville Hatchery, were first noted to be spawning downstream of Bonneville Dam by WDFW biologists in 1993. Known spawning areas include gravel beds on the Washington side of the river near Hamilton …
Date: September 21, 2007
Creator: Arntzen, Evan V.; Mueller, Robert P. & Murray, Christopher J.
Object Type: Report
System: The UNT Digital Library
e^+e^- Annihilations into Quasi-two-body Final States at 10.58 GeV (open access)

e^+e^- Annihilations into Quasi-two-body Final States at 10.58 GeV

We report the first observation of e{sup +}e{sup -} annihilations into hadronic states of positive C-parity, {rho}{sup 0}{rho}{sup 0} and {phi}{rho}{sup 0}. The angular distributions support two-virtual-photon annihilation production. We also report the observations of e{sup +}e{sup -} {yields} {phi}{eta} and a preliminary result on e{sup +}e{sup -} Z{yields} {rho}{sup +}{rho}{sup -}.
Date: September 21, 2007
Creator: Yi, Kai
Object Type: Article
System: The UNT Digital Library
AdS/CFT and Exclusive Processes in QCD (open access)

AdS/CFT and Exclusive Processes in QCD

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. One can use holography to map the amplitude describing the hadronic state in the fifth dimension of Anti-de Sitter space AdS5 to the light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons in QCD at the amplitude level. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable {var_sigma} which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. New relativistic light-front equations in ordinary space-time can then be derived which reproduce the results obtained using the 5-dimensional theory. The effective light-front equations possess elegant algebraic structures and integrability properties. This connection between the AdS and the light-front representations allows one to compute the analytic form of the frame-independent light-front wavefunctions, the fundamental entities which encode hadron properties and allow the computation of decay constants, form factors, deeply virtual Compton scattering, exclusive heavy hadron decays …
Date: September 21, 2007
Creator: Brodsky, Stanley J. & de Teramond, Guy F.
Object Type: Article
System: The UNT Digital Library
Analysis of a Ferric Uptake Regulator (Fur) Mutant ofDesulfovibrio vulgaris Hildenborough (open access)

Analysis of a Ferric Uptake Regulator (Fur) Mutant ofDesulfovibrio vulgaris Hildenborough

Previous experiments examining the transcriptional profileof the anaerobe Desulfovibrio vulgaris demonstrated up-regulation of theFur regulon in response to various environmental stressors. To test theinvolvement of Fur in the growth response and transcriptional regulationof D. vulgaris, a targeted mutagenesis procedure was used for deletingthe fur gene. Growth of the resulting ?fur mutant (JW707) was notaffected by iron availability, but the mutant did exhibit increasedsensitivity to nitrite and osmotic stresses compared to the wild type.Transcriptional profiling of JW707 indicated that iron-bound Fur acts asa traditional repressor for ferrous iron uptake genes (feoAB) and othergenes containing a predicted Fur binding site within their promoter.Despite the apparent lack of siderophore biosynthesis genes within the D.vulgaris genome, a large 12-gene operon encoding orthologs to TonB andTolQR also appeared to be repressed by iron-bound Fur. While other genespredicted to be involved in iron homeostasis were unaffected by thepresence or absence of Fur, alternative expression patterns that could beinterpreted as repression or activation by iron-free Fur were observed.Both the physiological and transcriptional data implicate a globalregulatory role for Fur in the sulfate-reducing bacterium D.vulgaris.
Date: September 21, 2007
Creator: Bender, Kelly S.; Yen, Huei-Che Bill; Hemme, Christopher L.; Yang, Zamin K.; He, Zhili; He, Qiang et al.
Object Type: Article
System: The UNT Digital Library
Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance (open access)

Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

The major thrust of this project, led by the University of Kansas (Prof. Kristin Bowman-James), entails an exploration of the basic determinants of anion recognition and their application to the design, synthesis, and testing of novel sulfate extractants. A key scientific inspiration for the work comes from the need, codified in simple-to-appreciate terms by the Oak Ridge National Laboratory component of the team (viz. Dr. Bruce Moyer), for chemical entities that can help in the extractive removal of species that have low solubilities in borosilicate glass. Among such species, sulfate anion, has been identified as particularly insidious. Its presence interferes with the vitrification process, thus rendering the remediation of tank waste from, e.g., the Hanford site far more difficult and expensive. The availability of effective extractants, that would allow for the separation of separating sulfate from the major competing anions in the waste, especially nitrate, could allow for pre-vitrification removal of sulfate via liquid-liquid extraction. The efforts at The University of Texas, the subject of this report, have thus concentrated on the development of new sulfate receptors. These systems are designed to increase our basic understanding of anion recognition events and set the stage for the development of viable sulfate …
Date: September 21, 2007
Creator: Sessler, Jonathan L.
Object Type: Report
System: The UNT Digital Library