The structure of consolidated rapidly solidified powders of Ni3Al

Rapidly solidified powders of stoichiometric Ni₃Al and Ni₃Al containing boron and titanium have each been consolidated by two distinct routes, namely hot extrusion or hot compaction. The resulting microstructures have been examined by optical microscopy, scanning electron microscopy and transmission electron microscopy. The consolidated material did not retain the non-equilibrium structure of the rapidly solidified powders. The addition of titanium and boron produced material with a larger final grain size, a decreased incidence of twinning and, in the extruded material, led to cracking. Although all processing was performed in inert atmospheres, oxides were present in all consolidated products.     

The incongruity effect in memory for generated targets: Fact or artifact?

Investigated the conditions under which the incongruity effect was obtained in the free recall of generated targets in 2 experiments using 80 undergraduates. In Exp I, Ss were free to generate a response of their own choosing, and the incongruity effect was obtained; in Exp II, the generated response was predetermined, and the incongruity effect disappeared. It is concluded that the incongruity effect is an artifact of idiosyncratic item selection effects. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Advances in CTIX Accelerator Study

Several new experiments have been conducted on the UC Davis repetitive-pulsed spheromak-like compact toroid (SCT) accelerator (CTIX). (1) SCT density and kinetic energy density has been increased by gas puffing in the acceleration section. With gas puffing, SCT electrical to kinetic energy conversion efficiency has been increased to >20%. (2) SCT interaction with targets has been recorded with a fast visible imaging system, combined with target-region helium gas puffing for increased brightness. Images of both coherent waves and turbulent flow patterns were observed in the target region after the interaction. (3) A laser deflection density diagnostic has been improved to obtain better reliability and resolution. Operated with high-density gas-puffed SCTs, the second-generation diagnostic has successfully measured axial as well as radial deflection. The measured line averaged densities are in good agreement with a conventional quadrature laser interferometer.     

A Cloud Rise Model for Dust and Soot from High Explosive Detonations

Traditionally, the evolution and rise of the dust and soot cloud resulting from high explosive detonations has been divided into two stages, with specific models used for each stage. In this study, based on the assumption that cloud formation progresses smoothly from stage to stage, a simple cloud rise model has been developed based on three sets of field tests of high explosive detonations (25×10⁻³ to 4.5 kg of detasheet and C‐4). This model provides a good fit to observations and measurements of clouds from detonations both at ground level and 1 m above the ground. It was also found that the detonation height has a noticeable influence on cloud rise before reaching its effective height, but the influence is minor on the subsequent cloud rise.     

Powering sensor networks

This paper describes the sensor networks that are wireless systems in which large number of sensors can be deployed. A snapshot of the first-generation hardware and software for sensor networks, the requirements of the sensor nodes by their capabilities, and an outlook on future implementations are focused. These networks have been enabled in part by advancements in silicon sensor technology, low-power microcontrollers, chip-based radios, ad-hoc networking protocols, and operating systems and languages for embedded systems.     

Fatigue behavior of Zr52.5Al10Ti5Cu17.9Ni14.6 bulk metallic glass

In the present study, fatigue tests were conducted on a zirconium-based bulk metallic glass (BMG), BMG-11 (Zr–10Al–5Ti–17.9Cu–14.6Ni, atomic percent), in air and vacuum to elucidate the possible environmental effects. In air, the fatigue endurance limit and the fatigue ratio were found to be 907 MPa and 0.53, respectively. These values are better than many conventional high-strength crystalline alloys. Unexpectedly, the fatigue lifetimes in vacuum were found to be lower than in air. Additional testing indicated that dissociation of residual water vapor to atomic hydrogen in the vacuum via a hot-tungsten-filament ionization gauge, and subsequent hydrogen embrittlement of the BMG-11, could have been a factor causing the lower fatigue lifetimes observed in vacuum.     

Effects of frame-of-reference training and information configuration on memory organization and rating accuracy.

It was hypothesized that encoding conditions would substitute for, or neutralize, the effects of frame-of-reference (FOR) training on rating accuracy by encouraging or impeding the person organization of behavior in memory. Undergraduates (N?=?121) were trained with FOR or control procedures, observed videotaped manager performance in a blocked or a mixed order, rated the managers on 3 performance dimensions, and free-recalled target performance vignettes. FOR training and blocked information improved rating accuracy and led to person-based recall; however, person organization was uncorrelated with accuracy. Results are discussed in terms of R. S. Wyer and T. K. Srull's (1989) model of person memory and judgment from which it is proposed that memory organization for behaviors may be unnecessary for rating accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Membrane binding of human immunodeficiency virus type 1 matrix protein in vivo supports a conformational myristyl switch mechanism

The interaction of the human immunodeficiency virus (HIV) Gag protein with the plasma membrane of a cell is a critical event in the assembly of HIV particles. The matrix protein region (MA) of HIV type 1 (HIV-1) Pr55Gag has previously been demonstrated to confer membrane-binding properties on the precursor polyprotein. Both the myristic acid moiety and additional determinants within MA are essential for plasma membrane binding and subsequent particle formation. In this study, we demonstrated the myristylation-dependent membrane interaction of MA in an in vivo membrane-binding assay. When expressed within mammalian cells, MA was found both in association with cellular membranes and in a membrane-free form. In contrast, the intact precursor Pr55Gag molecule analyzed in an identical manner was found almost exclusively bound to membranes. Both membrane-bound and membrane-free forms of MA were myristylated and phosphorylated. Differential membrane binding was not due to the formation of multimers, as dimeric and trimeric forms of MA were also found in both membrane-bound and membrane-free fractions. To define the requirements for membrane binding of MA, we analyzed the membrane binding of a series of MA deletion mutants. Surprisingly, deletions within alpha-helical regions forming the globular head of MA led to a dramatic increase in overall membrane binding. The stability of the MA-membrane interaction was not affected by these deletions, and no deletion eliminated membrane binding of the molecule. These results establish that myristic acid is a primary determinant of the stability of the Gag protein-membrane interaction and provide support for the hypothesis that a significant proportion of HIV-1 MA molecules may adopt a conformation in which myristic acid is hidden and unavailable for membrane interaction.