Magnetic properties of nickel filament polymer-matrix composites

The magnetic properties of polyethersulfone-matrix composites with 3-19 vol.% polycrystalline nickel filaments (0.4 (im diam) were investigated. These filaments were found to exhibit hysteresis energy loss 10800 J/m³ of nickel and coercive force 16.9 kA/m, compared to corresponding values of 4930 J/m³ and 4.7 kA/m for 2 μ.m diam polycrystalline nickel fibers, 1020 J/m³ and 0.5 kA/m for 20 μm diam polycrystalline nickel fibers, and 1280 J/m³ and 2.3 kA/m for solid polycrystalline nickel.     

The genetic relationship between the Finns and the Finnish Saami (Lapps): analysis of nuclear DNA and mtDNA

The genetic relationships between two Finno-Ugric-speaking populations, the Finns and the Finnish Saami (Lapps), were studied by using PCR for six nuclear-DNA marker loci, mitochondrial restriction-site polymorphism, and sequence variation of a 360-bp segment of the mitochondrial control region. The allele frequencies of each of the nuclear-DNA marker loci and the frequencies of mtDNA restriction haplotypes were significantly different between the populations. The Saami showed exceptionally low variation in their mtDNA restriction sites. The 9-bp deletion common in East Asian populations was not observed, nor did the haplotype data fit into the haplogroup categorization of Torroni et al. The average number of nucleotide substitutions from the mtDNA haplotype data indicated that the Finnish Saami may be closer to the Finns than to the other reference populations, whereas nuclear DNA suggested that the Finns are more closely related to the European reference populations than to the Finnish Saami. The similarity of the Finns to the other Europeans was even more pronounced according to the sequence data. We were unable to distinguish between the Finns and either the Swiss or Sardinian reference populations, whereas the Finnish Saami clearly stood apart. The Finnish Saami are distinct from other Circumarctic populations, although two of the lineages found among the Saami showed closer relationship to the Circumarctic than to the European lineages. The sequence data indicated an exceptionally high divergence for the Saami mtDNA control lineages. The distribution of the pairwise nucleotide differences in the Saami suggested that this population has not experienced an expansion similar to what was indicated for the Finns and the reference populations.     

Going under to stay on top, revisited: Results of a colloquium on underground space utilization

This report summarizes the results of a three-day colloquium, held in Minnesota in July 1995, to address issues related to underground space utilization. The colloquium was convened by the Underground Space Center, with major support from the National Science Foundation, Directorate for Engineering, and the Federal Highway Administration.     

Computer-aided simulation for bone surgery

A system for evaluating bone deformities using a 3-D model directly recovered from 2-D images and for simulating surgery is described. It derives a 3-D object representation from only two X-ray images. It also offers user-friendly simulation of bone surgery with low-cost hardware and software. The system exhibits satisfactory behavior for reconstructing the bone shape, providing suitable data for the simulation and evaluation of bone surgery. Although the spline interpolation of the bone surface does not produce a realistic 3-D visualization of the tibia, which is used as an example, the reconstruction is useful in solving problems inherent in the pathology considered     

Characterization of solid-phase welds between Ti---6A1---2Sn---4Zr---2Mo---0.1Si and Ti---13.5A1---21.5Nb titanium aluminide

Dissimilar-alloy welds have been produced between Ti---6Al---2Sn---Z4---2Mo---0.1Si (wt. %) and Ti---13.5Al---21.5 NB (wt.%) titanium aluminde using the three different solid-phase welding processes that create significantly different thermo-mechanical conditions at the weld interface. Exposure to supertransus temperatures, appreciable deformation and rapid cooling of the weld interface region during linear-friction welding promote dynamic recrystallization of beta grains and beta decomposition to fine martensitic products. In contrast, diffusion welding at temperatures below the base metal beta transus temperatures and at relatively low pressures minimizes deformation and microstructural variations in the weld interface region relative to the unaffected base metal. During capacitor-discharge resistance spot welding, extremely rapid heating of the weld interface region to near-solidus temperatures, and subsequent rapid cooling, result in the formation of a metastable, ordered-beta microstructure in the Ti---s13.5Al---21.6Nb and fine alpha-prime martensite in the Ti---6Al---2Sn---4Zr---2Mo-0.1Si.