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Reviewers Comments on the 5th Symposium and the Status of Fusion Research 2003 (open access)

Reviewers Comments on the 5th Symposium and the Status of Fusion Research 2003

Better to understand the status of fusion research in the year 2003 we will first put the research in its historical context. Fusion power research, now beginning its sixth decade of continuous effort, is unique in the field of scientific research. Unique in its mixture of pure and applied research, unique in its long-term goal and its promise for the future, and unique in the degree that it has been guided and constrained by national and international governmental policy. Though fusion research's goal has from the start been precisely defined, namely, to obtain a net release of energy from controlled nuclear fusion reactions between light isotopes (in particular those of hydrogen and helium) the difficulty of the problem has spawned in the past a very wide variety of approaches to the problem. Some of these approaches have had massive international support for decades, some have been pursued only at a ''shoestring'' level by dedicated groups in small research laboratories or universities. In discussing the historical and present status of fusion research the implications of there being two distinctly different approaches to achieving net fusion power should be pointed out. The first, and oldest, approach is the use of strong magnetic …
Date: February 3, 2005
Creator: Post, R F
System: The UNT Digital Library
Solid State NMR Measurements for Preliminary Lifetime Assessments in (gamma)-Irradiated and Thermally Aged Siloxane Elastomers (open access)

Solid State NMR Measurements for Preliminary Lifetime Assessments in (gamma)-Irradiated and Thermally Aged Siloxane Elastomers

Siloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. Nuclear magnetic resonance (NMR) parameters such as transverse (T{sub 2}) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and magnetic resonance imaging (MRI) results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.
Date: February 3, 2005
Creator: Chinn, S C; Herberg, J L; Sawvel, A M & Maxwell, R S
System: The UNT Digital Library
Stable isotopic composition of deep sea gorgonian corals (Primnoa spp.): a new archive of surface processes. (open access)

Stable isotopic composition of deep sea gorgonian corals (Primnoa spp.): a new archive of surface processes.

The deep-sea gorgonian coral Primnoa spp. lives in the Atlantic and Pacific Oceans at depths of 65-3200 m. This coral has an arborescent growth form with a skeletal axis composed of annual rings made from calcite and gorgonin. It has a lifespan of at least several hundred years. It has been suggested that isotopic profiles from the gorgonin fraction of the skeleton could be used to reconstruct long-term, annual-scale variations in surface productivity. We tested assumptions about the trophic level, intra-colony isotopic reproducibility, and preservation of isotopic signatures in a suite of modern and fossil specimens. Measurements of gorgonin {Delta}{sup 14}C and {delta}{sup 15}N indicate that Primnoa spp. feed mainly on zooplankton and/or sinking particulate organic matter (POM{sub SINK}), and not on suspended POM (POM{sub SUSP}) or dissolved organic carbon (DOC). Gorgonin {delta}{sup 13}C and {delta}{sup 15}N in specimens from NE Pacific shelf waters, NW Atlantic slope waters, the Sea of Japan, and a South Pacific (Southern Ocean sector) seamount were strongly correlated with Levitus 1994 surface apparent oxygen utilization (AOU; the best available measure of surface productivity), demonstrating coupling between skeletal isotopic ratios and biophysical processes in surface water. Time-series isotopic profiles from different sections along the same colony …
Date: February 3, 2005
Creator: Sherwood, O. A.; Heikoop, J. M.; Scott, D. B.; Risk, M. J.; Guilderson, T. P. & McKinney, R. A.
System: The UNT Digital Library
FORWARD PHYSICS AND BRAHMS RESULTS. (open access)

FORWARD PHYSICS AND BRAHMS RESULTS.

We report here the BRAHMS measurements of particle production in d+Au and p+p collisions at RHIC. The results presented here are compared to previous p+A measurements at lower energies in fixed target mode. Some preliminary results on abundances of identified particles at high rapidity are also presented.
Date: February 3, 2005
Creator: DEBBE, R. & COLLABORATION), (FOR THE BRAHMS
System: The UNT Digital Library