On the Increasing Fragility of Human Teeth with Age: ADeep-Ultraviolet Resonance Raman Study (open access)

On the Increasing Fragility of Human Teeth with Age: ADeep-Ultraviolet Resonance Raman Study

Ultraviolet resonance Raman spectroscopy (UVRRS) using 244nm excitation was used to investigate the impact of aging on humandentin. The intensity of a spectroscopic feature from the peptide bondsin the collagen increases with tissue age, similar to a finding reportedpreviously for human cortical bone.
Date: July 14, 2006
Creator: Ager, J. W., III; Nalla, R. K.; Balooch, G.; Kim, G.; Pugach, M.; Habelitz, S. et al.
Object Type: Article
System: The UNT Digital Library
X-Ray Digital Radiography and Computed Tomography of High Energy Density Physics (HEDP) Material, Subassemblies and Targets (open access)

X-Ray Digital Radiography and Computed Tomography of High Energy Density Physics (HEDP) Material, Subassemblies and Targets

None
Date: July 14, 2006
Creator: Brown, W. D. & Martz, H. E., Jr.
Object Type: Article
System: The UNT Digital Library
Probing Structure Property Relationships in Complex Engineering Silicones by 1H NMR (open access)

Probing Structure Property Relationships in Complex Engineering Silicones by 1H NMR

It is generally accepted that the properties of polymeric materials are controlled by the network structure and the reactions by which they have been constructed. These properties include the bulk moduli at creation, but also the properties as a function of age during use. In order to interpret mechanical properties and predict the time dependent changes in these properties, detailed knowledge of the effect of structural changes must be obtained. The degree and type of crosslinking, the molecular weight between crosslinks, the number of elastically ineffective chains (loops, dangling chain ends, sol-fraction) must be characterized. A number of theoretical and experimental efforts have been reported in the last few years on model networks prepared by endlinking reactions and the relationships of those structures with the ultimate mechanical properties. A range of experimental methods have been used to investigate structure including rheometric, scattering, infrared, {sup 29}Si MAS and CPMAS, {sup 1}H relaxation measurements, and recently {sup 1}H multiple quantum methods. Characterization of the growth of multiple quantum coherences have recently been shown to provide detailed insight into silicone network structure by the ability to selective probe the individual components of the polymer network, such as the polymer-filler interface or network chains. …
Date: July 14, 2006
Creator: Chinn, S. C.; Gjersing, E. L.; Maxwell, R. S.; Eastwood, E.; Bowen, D. & Stephens, T.
Object Type: Article
System: The UNT Digital Library
Collaborating for Multi-Scale Chemical Science (open access)

Collaborating for Multi-Scale Chemical Science

Advanced model reduction methods were developed and integrated into the CMCS multiscale chemical science simulation software. The new technologies were used to simulate HCCI engines and burner flames with exceptional fidelity.
Date: July 14, 2006
Creator: Green, William H.
Object Type: Report
System: The UNT Digital Library
Adversary Modeling for Allocation of Effort Across Countermeasures (open access)

Adversary Modeling for Allocation of Effort Across Countermeasures

None
Date: July 14, 2006
Creator: Lathrop, J F
Object Type: Article
System: The UNT Digital Library
Thermal and mechanical joints to cryo-cooled silicon monochromatorcrystals (open access)

Thermal and mechanical joints to cryo-cooled silicon monochromatorcrystals

We describe the performance of various materials used as thethermal interface between silicon to silicon and silicon to copper jointswhen operated at ~;120K and loaded with ~;20 watts of thermal power. Wefind that only the indium based silicon-to-silicon joint isreliable.
Date: July 14, 2006
Creator: MacDowell, A.; Fakra, S. & Morrison, G.
Object Type: Article
System: The UNT Digital Library
Large-scale turnover of functional transcription factor bindingsites in Drosophila (open access)

Large-scale turnover of functional transcription factor bindingsites in Drosophila

The gain and loss of functional transcription-factor bindingsites has been proposed as a major source of evolutionary change incis-regulatory DNA and gene expression. We have developed an evolutionarymodel to study binding site turnover that uses multiple sequencealignments to assess the evolutionary constraint on individual bindingsites, and to map gain and loss events along a phylogenetic tree. Weapply this model to study the evolutionary dynamics of binding sites ofthe Drosophila melanogaster transcription factor Zeste, using genome-widein vivo (ChIP-chip) binding data to identify functional Zeste bindingsites, and the genome sequences of D. melanogaster, D. simulans, D.erecta and D. yakuba to study their evolution. We estimate that more than5 percent of functional Zeste binding sites in D. melanogaster weregained along the D. melanogaster lineage or lost along one of the otherlineages. We find that Zeste bound regions have a reduced rate of bindingsite loss and an increased rate of binding site gain relative to flankingsequences. Finally, we show that binding site gains and losses areasymmetrically distributed with respect to D. melanogaster, consistentwith lineage-specific acquisition and loss of Zeste-responsive regulatoryelements.
Date: July 14, 2006
Creator: Moses, Alan M.; Pollard, Daniel A.; Nix, David A.; Iyer, VenkyN.; Li, Xiao-Yong; Biggin, Mark D. et al.
Object Type: Article
System: The UNT Digital Library
A Strong-Lens Survey in AEGIS: the Influence of Large Scale Structure (open access)

A Strong-Lens Survey in AEGIS: the Influence of Large Scale Structure

We report on the results of a visual search for galaxy-scale strong gravitational lenses over 650 arcmin2 of HST/ACS imaging in the Extended Groth Strip (EGS). These deep F606W- and F814W-band observations are in the DEEP2-EGS field. In addition to a previously-known Einstein Cross also found by our search (the ''Cross'', HSTJ141735+52264, with z{sub lens} = 0.8106 and a published z{sub source} = 3.40), we identify two new strong galaxy-galaxy lenses with multiple extended arcs. The first, HSTJ141820+52361 (the ''Dewdrop''; z{sub lens} = 0.5798), lenses two distinct extended sources into two pairs of arcs (z{sub source} = 0.9818 by nebular [O{sub II}] emission), while the second, HSTJ141833+52435 (the ''Anchor''; z{sub lens} = 0.4625), produces a single pair of arcs (source redshift not yet known). Four less convincing arc/counter-arc and two-image lens candidates are also found and presented for completeness. All three definite lenses are fit reasonably well by simple singular isothermal ellipsoid models including external shear, giving {chi}{sub {nu}}{sup 2}values close to unity. Using the three-dimensional line-of-sight (LOS) information on galaxies from the DEEP2 data, we calculate the convergence and shear contributions {kappa}{sub los} and {gamma}{sub los} to each lens, assuming singular isothermal sphere halos truncated at 200 h{sup -1} …
Date: July 14, 2006
Creator: Moustakas, Leonidas A.; Marshall, Phil J.; Newman, Jeffrey A.; Coil, Alison L.; Cooper, Michael C.; Davis, Marc et al.
Object Type: Report
System: The UNT Digital Library
EBS Radionuclide Transport Abstraction (open access)

EBS Radionuclide Transport Abstraction

The purpose of this report is to develop and analyze the engineered barrier system (EBS) radionuclide transport abstraction model, consistent with Level I and Level II model validation, as identified in Technical Work Plan for: Near-Field Environment and Transport: Engineered Barrier System: Radionuclide Transport Abstraction Model Report Integration (BSC 2005 [DIRS 173617]). The EBS radionuclide transport abstraction (or EBS RT Abstraction) is the conceptual model used in the total system performance assessment (TSPA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ). The EBS RT Abstraction conceptual model consists of two main components: a flow model and a transport model. Both models are developed mathematically from first principles in order to show explicitly what assumptions, simplifications, and approximations are incorporated into the models used in the TSPA. The flow model defines the pathways for water flow in the EBS and specifies how the flow rate is computed in each pathway. Input to this model includes the seepage flux into a drift. The seepage flux is potentially split by the drip shield, with some (or all) of the flux being diverted by the drip shield and some passing through breaches in the drip shield that …
Date: July 14, 2006
Creator: Prouty, J.
Object Type: Report
System: The UNT Digital Library
Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic (open access)

Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. The results of our modeling efforts were published this past summer in the Proceedings of the National Academy of Sciences. We are expanding on that work through a variety of laboratory and modeling efforts. In the laboratories at Columbia and at Harvard, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. We are currently preparing the results of these findings for publication. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but …
Date: July 14, 2006
Creator: Schrag, Daniel P.
Object Type: Report
System: The UNT Digital Library
Snake River Sockeye Salmon Habitat and Limnological Research: 2005 Annual Report. (open access)

Snake River Sockeye Salmon Habitat and Limnological Research: 2005 Annual Report.

In March 1990, the Shoshone-Bannock Tribes petitioned the National Marine Fisheries Service (NMFS) to list Snake River sockeye salmon (Oncorhynchus nerka) as endangered. Snake River sockeye salmon were officially listed as endangered in November 1991 under the Endangered Species Act (56 FR 58619). In 1991, the Snake River Sockeye Salmon Habitat and Limnological Research Project was implemented. This project is part of an interagency effort to prevent the extinction of the Redfish Lake stock of Snake River sockeye salmon. The Shoshone-Bannock Tribal goal for this project is two tiered: The immediate goal is to increase the population of Snake River sockeye salmon while preserving the unique genetic characteristics of the Evolutionarily Significant Unit (ESU). The Tribes long term goal is to maintain a viable population that warrants delisting and provides Tribal harvest opportunities. The Bonneville Power Administration (BPA) provides funding for this interagency recovery. Collaborators in the recovery effort include the National Oceanic and Atmospheric Administration (NOAA), the Idaho Department of Fish and Game (IDFG), the University of Idaho (UI), and the Shoshone-Bannock Tribes (SBT). This report summarizes activities conducted by Shoshone-Bannock Tribal Fisheries Department personnel during the 2005 calendar year. Project tasks include: (1) monitor limnological parameters of the …
Date: July 14, 2006
Creator: Taki, Doug; Kohler, Andre E.; Griswold, Robert G. & Gilliland, Kim
Object Type: Report
System: The UNT Digital Library
Ultrasensitive Searches for the Axion (open access)

Ultrasensitive Searches for the Axion

The axion, a hypothetical elementary particle arising from a compelling solution to the strong-CP problem, has eluded discovery for three decades. Experiments based on coherent axion-photon mixing in strong magnetic fields are just now reaching the sensitivity to detect it, either as the dark matter or as a component of the solar flux. Although of lower sensitivity, purely laboratory experiments hold potential for surprise.
Date: July 14, 2006
Creator: Van Bibber, K. A. & Rosenberg, L. J.
Object Type: Article
System: The UNT Digital Library
An Arbitrary Lagrangian Eulerian Formulation with Adaptive Mesh Refinement for Hydrodynamics and Material Modeling (open access)

An Arbitrary Lagrangian Eulerian Formulation with Adaptive Mesh Refinement for Hydrodynamics and Material Modeling

None
Date: July 14, 2006
Creator: Wang, P
Object Type: Article
System: The UNT Digital Library
Luminosity Function of Faint Globular Clusters in M87 (open access)

Luminosity Function of Faint Globular Clusters in M87

We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit Hubble Space Telescope (HST) WFPC2 imaging program. The very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before. We compare our luminosity function to those that have been observed in the past, and confirm the similarity of the turnover luminosity between M87 and the Milky Way. We also find with high statistical significance that the M87 luminosity function is broader than that of the Milky Way. We discuss how determining the mass function of the cluster system to low masses can constrain theoretical models of the dynamical evolution of globular cluster systems. Our mass function is consistent with the dependence of mass loss on the initial cluster mass given by classical evaporation, and somewhat inconsistent with newer proposals that have a shallower mass dependence. In addition, the rate of mass loss is consistent with standard evaporation models, and not with the much higher rates proposed by some recent studies of very young cluster systems. We also find that the mass-size relation has very little slope, …
Date: July 14, 2006
Creator: Waters, Christopher Z.; Zepf, Stephen E.; U., /Michigan State; Lauer, Tod R.; /NOAO, Tucson; Baltz, Edward A. et al.
Object Type: Report
System: The UNT Digital Library