Gel Electrophoresis of Gold-DNA Nano-Conjugates (open access)

Gel Electrophoresis of Gold-DNA Nano-Conjugates

Single stranded DNA of different lengths and different amounts was attached to colloidal phosphine stabilized Au nanoparticles. The resulting conjugates were investigated in detail by a gel electrophoresis study based on 1200 gels. We demonstrate how these experiments help to understand the binding of DNA to Au particles. In particular we compare specific attachment of DNA via gold-thiol bonds with nonspecific adsorption of DNA. The maximum number of DNA molecules that can be bound per particle was determined. We also compare several methods to used gel electrophoresis for investigating the effective diameter of DNA-Au conjugates, such as using a calibration curve of particles with known diameters and Ferguson plots.
Date: January 10, 2006
Creator: Pellegrino, T.; Sperling, R. A.; Alivisatos, A. P. & Parak, W. J.
System: The UNT Digital Library
Semi-inclusive DIS: Factorization (open access)

Semi-inclusive DIS: Factorization

In this talk, we will present a QCD factorization theorem for the semi-inclusive deep-inelastic scattering with hadrons in the current fragmentation region detected at low transverse momentum. There has been considerable experimental and theoretical interest in semi-inclusive hadron production in deep inelastic scattering (SIDIS) processes. For example, by studying the polarized and unpolarized SIDIS, one will be able to identify the sea quark distribution and polarization in nucleon, and the experimental results from the HERMES collaboration have revealed nontrivial sea structure in nucleon [1]. More recently, SIDIS opened a new window to study the transverse momentum dependent (TMD) parton distributions and fragmentation functions from the low transverse momentum hadron production. The transverse momentum distribution of the final state hadron is directly related to the transverse momentum dependence of the parton distributions and fragmentation. These studies will provide new opportunities to explore the partonic structure of nucleon, especially the three-dimension distribution of partons inside nucleon. The DIS experiments, including HERMES, COMPAS, and JLab Hall B collaborations, have studied various azimuthal asymmetries in SIDIS. In particular, the HERMES collaboration found sizable single spin asymmetries in these processes involving nontrivial QCD effects and hadron structure.
Date: December 10, 2008
Creator: Yuan, Feng
System: The UNT Digital Library
HIGH ENERGY HADRON POLARIMETRY. (open access)

HIGH ENERGY HADRON POLARIMETRY.

Proton polarimetry at RHIC uses the interference of electromagnetic (EM) and hadronic scattering amplitudes. The EM spin-flip amplitude for protons is responsible for the proton's anomalous magnetic moment, and is large. This then generates a significant analyzing power for small angle elastic scattering. RHIC polarimetry has reached a 5% uncertainty on the beam polarization, and seem capable of reducing this uncertainty further. Polarized neutron beams ax also interesting for RHIC and for a polarized electron-polarized proton/ion collider in the fume. In this case, deuterons, for example, have a very small anomalous magnetic moment, making the approach used for protons impractical. Although it might be possible to use quasielastic scattering from the protons in the deuteron to monitor the polarization. 3-He beams can provide polarized neutrons, and do have a large anomalous magnetic moment, making a similar approach to proton polarimetry possible.
Date: September 10, 2007
Creator: BUNCE,G.
System: The UNT Digital Library
Barium in Twilight Zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific (open access)

Barium in Twilight Zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific

This study focuses on the fate of exported organic carbon in the twilight zone at two contrasting environments in the North Pacific: the oligotrophic ALOHA site (22 degrees 45 minutes N 158 degrees W; Hawaii; studied during June-July 2004) and the mesotrophic Subarctic Pacific K2 site (47 degrees N, 161 degrees W; studied during July-August 2005). Earlier work has shown that non-lithogenic, excess particulate Ba (Ba{sub xs}) in the mesopelagic water column is a potential proxy of organic carbon remineralization. In general Ba{sub xs} contents were significantly larger at K2 than at ALOHA. At ALOHA the Ba{sub xs} profiles from repeated sampling (5 casts) showed remarkable consistency over a period of three weeks, suggesting that the system was close to being at steady state. In contrast, more variability was observed at K2 (6 casts sampled) reflecting the more dynamic physical and biological conditions prevailing in this environment. While for both sites Ba{sub xs} concentrations increased with depth, at K2 a clear maximum was present between the base of the mixed layer at around 50m and 500m, reflecting production and release of Ba{sub xs}. Larger mesopelagic Ba{sub xs} contents and larger bacterial production in the twilight zone at the K2 site …
Date: April 10, 2008
Creator: Dehairs, F.; Jacquet, S.; Savoye, N.; Van Mooy, B. A. S.; Buesseler, K.; Bishop, J. K. B. et al.
System: The UNT Digital Library
Absolute Polarimetry at RHIC (open access)

Absolute Polarimetry at RHIC

Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.
Date: September 10, 2007
Creator: Okada, H.; Bravar, A.; Bunce, G.; Gill, R.; Huang, H.; Makdisi, Y. et al.
System: The UNT Digital Library
Sona transition studies in the RHIC OPPIS. (open access)

Sona transition studies in the RHIC OPPIS.

In Optically Pumped Polarized Ion Sources (OPPIS), the atomic beam is first electron polarized, and then this polarization is transferred to the nucleus by a suitable perturbing magnetic field. In the BNL OPPIS, the electron polarized atomic beam experiences the perturbing field when it traverses a region where the axial magnetic field reverses direction in a controlled manner, strength and gradient. This is the so-called Sona Transition region, named after P. G. Sona, who fist suggested the technique. We have extensively studied how the magnetic field profile in the Sona region affects beam polarization. In these studies, we have observed oscillations in polarization for certain field profiles, and tried to explain them. We report on these studies.
Date: September 10, 2007
Creator: Kponou,A.; Zelenski, A.; Kokhanovski, S. & Zubets, V.
System: The UNT Digital Library
Examination of Uranium(VI) Leaching During Ligand Promoted Dissolution of Waste Tank Sludge Surrogates (open access)

Examination of Uranium(VI) Leaching During Ligand Promoted Dissolution of Waste Tank Sludge Surrogates

The dissolution of synthetic boehmite (?-AlOOH) by 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) was examined in a series of batch adsorption/dissolution experiments. Additionally, the leaching behavior of {sup 233}U(VI) from boehmite was examined as a function of pH and HEDPA concentration. The results are discussed in terms of sludge washing procedures that may be utilized during underground tank waste remediation. In the pH range 4 to 10, complexation of Al(III) by HEDPA significantly enhanced dissolution of boehmite. This phenomenon was especially pronounced in the neutral pH region where the solubility of aluminum, in the absence of complexants, is limited by the formation of sparsely soluble aluminum hydroxides. At pH higher than 10, dissolution of synthetic boehmite was inhibited by HEDPA, likely due to sorption of Al(III):HEDPA complexes. Addition of HEDPA to equilibrated U(VI)-synthetic boehmite suspensions yielded an increase in the aqueous phase uranium concentration. Partitioning of uranium between the solid and aqueous phase is described in terms of U(VI):HEDPA speciation and dissolution of the boehmite solid phase.
Date: June 10, 2008
Creator: Powell, Brian; Powell, Brian A.; Rao, Linfeng & Nash, Kenneth. L.
System: The UNT Digital Library
Shape optimization of a sheet swimming over a thin liquid layer (open access)

Shape optimization of a sheet swimming over a thin liquid layer

Motivated by the propulsion mechanisms adopted by gastropods, annelids and other invertebrates, we consider shape optimization of a flexible sheet that moves by propagating deformation waves along its body. The self-propelled sheet is separated from a rigid substrate by a thin layer of viscous Newtonian fluid. We use a lubrication approximation to model the dynamics and derive the relevant Euler-Lagrange equations to simultaneously optimize swimming speed, efficiency and fluid loss. We find that as the parameters controlling these quantities approach critical values, the optimal solutions become singular in a self-similar fashion and sometimes leave the realm of validity of the lubrication model. We explore these singular limits by computing higher order corrections to the zeroth order theory and find that wave profiles that develop cusp-like singularities are appropriately penalized, yielding non-singular optimal solutions. These corrections are themselves validated by comparison with finite element solutions of the full Stokes equations, and, to the extent possible, using recent rigorous a-priori error bounds.
Date: December 10, 2008
Creator: Wilkening, J. & Hosoi, A.E.
System: The UNT Digital Library
A balancing domain decomposition method by constraints for advection-diffusion problems (open access)

A balancing domain decomposition method by constraints for advection-diffusion problems

The balancing domain decomposition methods by constraints are extended to solving nonsymmetric, positive definite linear systems resulting from the finite element discretization of advection-diffusion equations. A pre-conditioned GMRES iteration is used to solve a Schur complement system of equations for the subdomain interface variables. In the preconditioning step of each iteration, a partially sub-assembled finite element problem is solved. A convergence rate estimate for the GMRES iteration is established, under the condition that the diameters of subdomains are small enough. It is independent of the number of subdomains and grows only slowly with the subdomain problem size. Numerical experiments for several two-dimensional advection-diffusion problems illustrate the fast convergence of the proposed algorithm.
Date: December 10, 2008
Creator: Tu, Xuemin & Li, Jing
System: The UNT Digital Library
A method for quick assessment of CO2 storage capacity in closed and semi-closed saline formations (open access)

A method for quick assessment of CO2 storage capacity in closed and semi-closed saline formations

Saline aquifers of high permeability bounded by overlying/underlying seals may be surrounded laterally by low-permeability zones, possibly caused by natural heterogeneity and/or faulting. Carbon dioxide (CO{sub 2}) injection into and storage in such 'closed' systems with impervious seals, or 'semi-closed' systems with nonideal (low-permeability) seals, is different from that in 'open' systems, from which the displaced brine can easily escape laterally. In closed or semi-closed systems, the pressure buildup caused by continuous industrial-scale CO{sub 2} injection may have a limiting effect on CO{sub 2} storage capacity, because geomechanical damage caused by overpressure needs to be avoided. In this research, a simple analytical method was developed for the quick assessment of the CO{sub 2} storage capacity in such closed and semi-closed systems. This quick-assessment method is based on the fact that native brine (of an equivalent volume) displaced by the cumulative injected CO{sub 2} occupies additional pore volume within the storage formation and the seals, provided by pore and brine compressibility in response to pressure buildup. With nonideal seals, brine may also leak through the seals into overlying/underlying formations. The quick-assessment method calculates these brine displacement contributions in response to an estimated average pressure buildup in the storage reservoir. The CO{sub …
Date: February 10, 2008
Creator: Zhou, Q.; Birkholzer, J.; Tsang, C. F. & Rutqvist, J.
System: The UNT Digital Library
The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot (open access)

The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot

We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number of iteration steps until convergence decreases by about a factor of 4 compared to previous calculations.
Date: May 10, 2006
Creator: Vomel, Christof; Tomov, Stanimire Z.; Wang, Lin-Wang; Marques,Osni A. & Dongarra, Jack J.
System: The UNT Digital Library
Influence of interface exchange coupling in perpendicular anisotropy [Pt/Co]50/TbFe bilayers (open access)

Influence of interface exchange coupling in perpendicular anisotropy [Pt/Co]50/TbFe bilayers

We present the magnetization evolution of perpendicular anisotropy TbFe and [Co/Pt]{sub 50} thin films either in direct contact resulting in antiferromagnetic interfacial coupling or separated by a thick Pt layer. Magnetometry and x-ray magnetic circular dichroism spectroscopy determine the spatially averaged magnetic properties. Resonant magnetic x-ray small-angle scattering and magnetic soft X-ray transmission microscopy probed the domain configurations and correlations in the reversal processes. While the Co/Pt multilayer reverses by domain propagation, the TbFe magnetization reversal is found to be dominated either by coherent magnetization reversal processes or by lateral domain formation depending on the interface exchange coupling. In the presence of lateral domains, dipolar field induced domain replication phenomena are observed.
Date: October 10, 2007
Creator: Mangin, S.; Hauet, T.; Fischer, P.; Kim, D.H.; Kortright, J.B.; Chesnel, K. et al.
System: The UNT Digital Library
Cyclic and Linear Polarization of Yttrium-Containing Iron-Based Amorphous Alloys (open access)

Cyclic and Linear Polarization of Yttrium-Containing Iron-Based Amorphous Alloys

Iron-based amorphous alloys are produced by rapid solidification from the melt. These alloys may possess unique mechanical and corrosion resistant properties. The chemical composition of the alloy may influence the cooling rate that is necessary for the alloys to be completely vitreous. At the same time, the corrosion resistance of the amorphous alloys may also depend on their chemical composition. This paper examines the anodic behavior of iron-based amorphous alloys containing three different concentrations (1, 3 and 5 atomic %) of yttrium (Y) in several electrolyte solutions. Results from polarization resistance potentiodynamic polarization show that when the alloy contains 5% atomic Y, the corrosion resistance decreases.
Date: August 10, 2007
Creator: Day, S D; Lian, T; Farmer, J C & Rebak, R B
System: The UNT Digital Library
Constitutive modeling of Radiation effects on the Permanent Set in a silicone elastomer (open access)

Constitutive modeling of Radiation effects on the Permanent Set in a silicone elastomer

When a networked polymeric composite under high stress is subjected to irradiation, the resulting chemical changes like chain scissioning and cross-link formation can lead to permanent set and altered elastic modulus. Using a commercial silicone elastomer as a specific example we show that a simple 2-stage Tobolsky model in conjunction with Fricker's stress-transfer function can quantitatively reproduce all experimental data as a function of radiation dosage and the static strain at which radiation is turned on, including permanent set, stress-strain response, and net cross-linking density.
Date: March 10, 2008
Creator: Maiti, A.; Gee, R.; Weisgraber, T.; Chinn, S. & Maxwell, R.
System: The UNT Digital Library
Recent Development in Proton Spin Physics (open access)

Recent Development in Proton Spin Physics

In the naive model of the proton, its 1/2 spin is carried by its quark constituents. However, experiments over the last several decades have shown that the quark spin only contribute a small portion of the proton spin. In this talk, I will present recent developments exploring this proton spin puzzle, and focus on the progress made in the last few years on the longitudinal spin physics, the generalized parton distribution physics, and the transverse spin physics.
Date: December 10, 2008
Creator: Yuan, Feng
System: The UNT Digital Library
The RHIC Optically-Pumped Polarized H Ion Source. (open access)

The RHIC Optically-Pumped Polarized H Ion Source.

The depolarization factors in the multi-step spin-transfer polarization technique and basic limitations on maximum polarization in the OPPIS (Optically-Pumped Polarized H{sup -} Ion Source) are discussed. Detailed studies of polarization losses in the RHIC OPPIS and the source parameters optimization resulted in the OPPIS polarization increase to 86-90%. This contributed to increasing polarization in the AGS and RHIC to 65-70%.
Date: September 10, 2007
Creator: Zelenski,A.; Zelenski, A.; Kokhanovski, S.; Kponou, A.; Ritter, J. & Zubets, V.
System: The UNT Digital Library
US Support Program Topical Meetings 1999 to 2008 (open access)

US Support Program Topical Meetings 1999 to 2008

In 1999, the International Safeguards Project Office began organizing topical workshops to explore technical issues facing the International Atomic Energy Agency's Department of Safeguards. Representatives from IAEA member states including the United States, national laboratories and companies were invited to the workshops to discuss the technical issues. In some cases professional facilitators were hired to lead the discussions and in some cases business gaming techniques were employed. Since 1999, the following topics have been addressed Data Communication Technologies (1999), Information Security (2000), Design and Testing for High Reliability (2001), Standardization and Integration of Unattended and Remote Monitoring Systems (2002), Roadmapping: Surveillance (2003), IAEA Seals Technology Roadmapping Workshop (2004), Turning Information Into Knowledge (2004), Safeguards Tools of the Future (2005), and Advanced Sensors for Safeguards (2007). This paper will review the scope of the workshops and summarize their results.
Date: June 10, 2008
Creator: Pepper,S.
System: The UNT Digital Library
The Effect of Extending the Length of the Coupling Coils in a MuonIonization Cooling Channel (open access)

The Effect of Extending the Length of the Coupling Coils in a MuonIonization Cooling Channel

RF cavities are used to re-accelerate muons that have beencooled by absorbers that are in low beta regions of a muon ionizationcooling channel. A superconducting coupling magnet (or magnets) arearound or among the RF cavities of a muon ionization-cooling channel. Thefield from the magnet guides the muons so that they are kept within theiris of the RF cavities that are used to accelerate the muons. Thisreport compares the use of a single short coupling magnet with anextended coupling magnet that has one or more superconducting coils aspart of a muon-cooling channel of the same design as the muon ionizationcooling experiment (MICE). Whether the superconducting magnet is shortand thick or long and this affects the magnet stored energy and the peakfield in the winding. The magnetic field distribution also affects is themuon beam optics in the cooling cell of a muon coolingchannel.
Date: November 10, 2007
Creator: Green, Michael A.
System: The UNT Digital Library
Preseismic Velocity Changes Observed from Active Source Monitoringat the Parkfield SAFOD Drill Site (open access)

Preseismic Velocity Changes Observed from Active Source Monitoringat the Parkfield SAFOD Drill Site

Measuring stress changes within seismically active fault zones has been a long-sought goal of seismology. Here we show that such stress changes are measurable by exploiting the stress dependence of seismic wave speed from an active source cross-well experiment conducted at the SAFOD drill site. Over a two-month period we observed an excellent anti-correlation between changes in the time required for an S wave to travel through the rock along a fixed pathway--a few microseconds--and variations in barometric pressure. We also observed two large excursions in the traveltime data that are coincident with two earthquakes that are among those predicted to produce the largest coseismic stress changes at SAFOD. Interestingly, the two excursions started approximately 10 and 2 hours before the events, respectively, suggesting that they may be related to pre-rupture stress induced changes in crack properties, as observed in early laboratory studies.
Date: June 10, 2008
Creator: Daley, Thomas; Niu, Fenglin; Silver, Paul G.; Daley, Thomas M.; Cheng, Xin & Majer, Ernest L.
System: The UNT Digital Library
Risks of Mortality and Morbidity from Worldwide Terrorism: 1968-2004 (open access)

Risks of Mortality and Morbidity from Worldwide Terrorism: 1968-2004

Worldwide data on terrorist incidents between 1968 and 2004 gathered by the RAND corporation and the Oklahoma City National Memorial Institute for the Prevention of Terrorism (MIPT) were assessed for patterns and trends in morbidity/mortality. Adjusted data analyzed involve a total of 19,828 events, 7,401 ''adverse'' events (each causing {ge}1 victim), and 86,568 ''casualties'' (injuries) of which 25,408 were fatal. Most terror-related adverse events, casualties and deaths involved bombs and guns. Weapon-specific patterns and terror-related risk levels in Israel (IS) have differed markedly from those of all other regions combined (OR). IS had a fatal fraction of casualties about half that of OR, but has experienced relatively constant lifetime terror-related casualty risks on the order of 0.5%--a level 2 to 3 orders of magnitude more than those experienced in OR that increased {approx}100-fold over the same period. Individual event fatality has increased steadily, the median increasing from 14 to 50%. Lorenz curves obtained indicate substantial dispersion among victim/event rates: about half of all victims were caused by the top 2.5% (or 10%) of harm-ranked events in OR (or IS). Extreme values of victim/event rates were approximated fairly well by generalized Pareto models (typically used to fit to data on forest …
Date: February 10, 2005
Creator: Bogen, K. T. & Jones, E. D.
System: The UNT Digital Library
MODIFIED BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE (open access)

MODIFIED BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE

This paper reports the results in the effort to destabilize lithium borohydride for reversible hydrogen storage. A number of metals, metal hydrides, metal chlorides and complex hydrides were selected and evaluated as the destabilization agents for reducing dehydriding temperature and generating dehydriding-rehydriding reversibility. It is found that some additives are effective. The Raman spectroscopic analysis shows the change of B-H binding nature.
Date: May 10, 2006
Creator: Au, Ming
System: The UNT Digital Library
Bottom-up, decision support system development : a wetlandsalinity management application in California's San Joaquin Valley (open access)

Bottom-up, decision support system development : a wetlandsalinity management application in California's San Joaquin Valley

Seasonally managed wetlands in the Grasslands Basin ofCalifornia's San Joaquin Valley provide food and shelter for migratorywildfowl during winter months and sport for waterfowl hunters during theannual duck season. Surface water supply to these wetland contain saltwhich, when drained to the San Joaquin River during the annual drawdownperiod, negatively impacts downstream agricultural riparian waterdiverters. Recent environmental regulation, limiting discharges salinityto the San Joaquin River and primarily targeting agricultural non-pointsources, now addresses return flows from seasonally managed wetlands.Real-time water quality management has been advocated as a means ofmatching wetland return flows to the assimilative capacity of the SanJoaquin River. Past attempts to build environmental monitoring anddecision support systems to implement this concept have failed forreasons that are discussed in this paper. These reasons are discussed inthe context of more general challenges facing the successfulimplementation of environmental monitoring, modelling and decisionsupport systems. The paper then provides details of a current researchand development project which will ultimately provide wetland managerswith the means of matching salt exports with the available assimilativecapacity of the San Joaquin River, when fully implemented. Manipulationof the traditional wetland drawdown comes at a potential cost to thesustainability of optimal wetland moist soil plant habitat in thesewetlands - hence the project …
Date: May 10, 2006
Creator: Quinn, Nigel W.T.
System: The UNT Digital Library
Continuous active-source seismic monitoring of CO2 injection in abrine aquifer (open access)

Continuous active-source seismic monitoring of CO2 injection in abrine aquifer

Continuous crosswell seismic monitoring of a small-scale CO2injection was accomplished with the development of a noveltubing-deployed piezoelectric borehole source. This piezotube source wasdeployed on the CO2 injection tubing, near the top of the saline aquiferreservoir at 1657-m depth, and allowed acquisition of crosswellrecordings at 15-minute intervals during the multiday injection. Thechange in traveltime recorded at various depths in a nearby observationwell allowed hour-by-hour monitoring of the growing CO2 plume via theinduced seismic velocity change. Traveltime changes of 0.2 to 1.0 ms ( upto 8 percent ) were observed, with no change seen at control sensorsplaced above the reservoir. The traveltime measurements indicate that theCO2 plume reached the top of the reservoir sand before reaching theobservation well, where regular fluid sampling was occuring during theinjection, thus providing information about the in situ buoyancy ofCO2.
Date: December 10, 2006
Creator: Daley, Thomas M.; Solbau, Ray D.; Ajo-Franklin, Jonathan B. & Benson, Sally M.
System: The UNT Digital Library
The "Athena Framework": Solving the World-wide Climate and Energy Problem (open access)

The "Athena Framework": Solving the World-wide Climate and Energy Problem

The energy systems we have enjoyed for the last 100 years has resulted in the advanced standard of living in the developed world and a major emerging problem with climate change. Now we face a simultaneous realization that our reliance on fossil fuels is a source of conflict and economic disruption as well as causing potentially catastrophic global climate change. It is time to give serious thought to how to collectively solve this problem. Collective action is critical since individual effort by one or only a few nations cannot adequately address the issue.
Date: October 10, 2005
Creator: Long, J S
System: The UNT Digital Library