A statistical analysis of spot variation using the two-dimensional polyacrylamide gel electrophoresis

For the development of valid algorithms for matching protein spots between two-dimensional gels, it is essential that one has an understanding of the relative roles of the many sources of variability affecting the location of spots. We first consider the contribution of observers to the measurement variability of spot location, arriving at a simple model for these effects. Next we present an analysis of the variability in spot locations for a sample of gels containing duplicate gels for each sample. Our data indicate that both differences between duplicates and between samples are considerable, and that the size of the effects depends on the region of the gel being considered. In the discussion we examine several matching strategies that match large groups of gels based on algorithms which match two gels at a time.     

Qualitative analysis of one class of population models with commensal interaction

The qualitative analysis of a class of dynamic population models that are in commensal relationships and compete for one substrate is carried out. The stability of all the stationary conditions is analyzed. All the singularities are found analytically and constraints are obtained for species growth characteristics and initial flows of the substrate and product. The qualitative changes in the dynamics due to variations of several system parameters are analyzed and bifurcation diagrams are constructed for all the singular points.     

Mol 7C experiments on local fault propagation in irradiated LMFBR fuel subassemblies

The consequences of local cooling disturbances in irradiated fuel pin bundles of Liquid Metal Fast Breeder Reactors (LMFBRs) were investigated in two in-pile experiments in the BR2 reactor at Mol/Belgium. A porous local blockage was used to initiate the fault. This caused severe local fuel pin damage, but there was no fault propagation to major parts of the bundles during four hours of full power operation. If such events occurred in a LMFBR, the delayed neutron detection (DND) signals generated by the fault would be sufficient to initiate reliable automatic shutdown of the reactor.     

RBS analysis of front contacts for surface-barrier detectors

Surface-barrier detector structures based on Au, WTi and Au/WTi contacts on (111) n-Si were analysed. The metal layers were deposited by evaporation or sputtering to 40–100 nm thicknesses. The aim was to improve the thermal stability of the surface-barrier structures and retain the favourable detector properties of the Au/Si system. Contact structures which contain WTi layers have shown a much better thermal stability compared to the Au/Si system, but the properties of the detectors were poorer. The probable reasons are the reactivity of W and Ti with the thin oxide layer on the silicon surface and perhaps the higher energy of adatoms during sputter-deposition. Both effects can influence the degradation of the surface-barrier properties.     

Corrosion of tungsten-base pseudoalloys in elegas

Conclusions Pseudoalloys based on tungsten and copper (silver) possess good resistance to corrosion by dry elegas, and may be recommended for the manufacture of electrical parts intended for operation in hermetic systems filled with elegas. In humid elegas pseudoalloys based on tungsten and copper (silver) become covered with films forming by the reactions of the surfaces of these materials with water and the hydrolysis products of impurities in elegas.Translated from Poroshkovaya Metallurgiya, No. 10(214), pp. 40–43, October, 1980.     

Audience-induced inhibition of overt practice during learning.

Three experiments with 204 undergraduates examined the hypothesis that an audience can inhibit overt practice and thereby impair learning of unfamiliar words and enhance learning of familiar words. This hypothesis was derived from an analysis of motoric and symbolic mediation during learning. In comparison with learning while alone, the results show that the audience inhibited overt practice of unfamiliar and familiar words and that reduced practice was detrimental to learning unfamiliar words. Inhibition of overt practice with an audience enhanced learning of familiar words in only 1 of the experiments. Instructions to practice overtly reduced the audience-inhibition effect in learning unfamiliar words. The studies are discussed in the context of drive-theory explanations for social facilitation effects in learning. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Plastic flow and fracture of metallic glass

The tensile flow and fracture behavior of three Pdo.₈Sio2-based alloys in the glassy, “microcrystalline,” and fully crystalline condition has been studied. The glassy alloys flow plastically to a total strain of approximately 0.5 pct e, and exhibit proportional limit stresses of approximatelyE x 10~² whereE is Young’s modulus. This plastic flow is accompanied by the formation of shear deformation bands on the specimen surfaces. Fully crystalline alloys are extremely brittle and fracture via intergranular cracking. Fracture surfaces of the amorphous and “microcrystalline” alloys are inclined at 45 deg to the tensile axis and exhibit two morphologically distinct zones. One zone is relatively featureless while the other contains a “river” pattern of local necking protrusions. Detailed comparison of opposing surfaces indicates that fracture is preceded by large local plastic shear which produces the smooth zone while the local necking pattern is produced during rupture. These observations form the basis for the hypothesis that plastic flow in the glassy material occurs via localized strain concentrations and that fracture is initiated by catastrophic, “adiabatic” shear. Formerly Postdoctoral Associate, Yeshiva University, New York, N. Y.