Articulatory constraints on interpersonal postural coordination.

Cooperative conversation has been shown to foster interpersonal postural coordination. The authors investigated whether such coordination is mediated by the influence of articulation on postural sway. In Experiment 1, talkers produced words in synchrony or in alternation, as the authors varied speaking rate and word similarity. Greater shared postural activity was found for the faster speaking rate. In Experiment 2, the authors demonstrated that shared postural activity also increases when individuals speak the same words or speak words that have similar stress patterns. However, this increase in shared postural activity is present only when participants' data are compared with those of their partner, who was present during the task, but not when compared with the data of a member of a different pair speaking the same word sequences as those of the original partner. The authors' findings suggest that interpersonal postural coordination observed during conversation is mediated by convergent speaking patterns. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DC System Resonance Analysis

DC filters and dc smoothing reactors are primarily designed to meet performance requirements with regard to telephone interference levels and commutation failure frequency. Other factors, however, place constraints on the size of the dc filter capacitance and the smoothing reactor inductance. The principal constraint is the avoidance of resonance conditions on the dc side at a low order harmonic of the commutating voltage. This paper discusses the factors which must be considered when analyzing dc side resonance. Specific considerations for the Intermountain Power Project are given.     

Articulated science teaching and balanced emphasis

The set of scientific thinking tools described is based on dramatized, exaggerated patterns of logical structures. What these patterns have in common is an overall invariance relationship that makes something true even though the details may differ in different situations? and a knowledge of that relationship leads to simple solutions of apparently complex problems. Articulated science teaching is defined as a method of getting the invariance concept across to the student by using selected puzzles and games as exercises in logical thinking. The end result should be to improve rational reasoning ability both in science and in everyday life.     

Divided attention during adaptation to visual-motor rotation in an endoscopic surgery simulator

We investigated how cognitive demand affects the acquisition of adaptive hand–eye coordination in a low-fidelity endoscopic simulator. Participants performed a peg transfer task. In the pre-exposure and post-exposure phases participants moved objects between pegs with forceps while directly viewing the pegboard. In the exposure phase participants completed that task while indirectly viewing the pegboard through a camera and monitor with a 90° clockwise visual rotation. A control group completed the experiment as described whereas an experimental group concurrently performed a short-term memory task (digit rehearsal) during the exposure phase. Performance was significantly disrupted during early exposure-phase performance for both groups. The cognitive task caused an additional initial performance decrement for the experimental group, but their performance quickly converged on control-group performance. Both groups performance improved over trials. Competition for attentional resources imposed by memory demands can impair simulator performance, but performers can quickly learn to compensate for the increased attentional demand.     

The Effect of Submicron Second-Phase Particles on the Rate of Grain Refinement in a Copper-Oxygen Alloy During Cold Spray

The effect of non-deformable submicron second-phase particles (d = 200-500 nm) on microstructural refinement during cold spray was examined. Using single particle impact testing, two types of splats were fabricated using two different feedstocks: a Cu-0.21wt.%O powder containing Cu₂O second-phase particles and a single-phase Cu. Microstructural evolution analysis using high-resolution electron backscatter diffraction shows grain refinement occurred at a higher rate in the Cu-0.21wt.%O powder. That was due to dynamic recrystallization initiated by particle-stimulated nucleation (PSN). High-strain-rate deformation of cold spray was found to be the key to activate PSN. The present study suggests cold spray is a possible technique to fabricate ultrafine-grained materials by using feedstock containing second-phase particles.     

Barriers and commitment of facilities management profession to the sustainability agenda

The practice of sustainable facilities management (FM) is rapidly evolving with the increasing interest in the discourse of sustainable development. This paper examines a recent survey of the experiences of facilities managers in the rapidly growing and evolving industry in regard to the barriers and their commitment to the sustainability agenda. The survey results show that time constraints, lack of knowledge and lack of senior management commitment are the main barriers for the implementation of consistent and comprehensive sustainable FM policy and practice. The paper concludes that the diversity of the FM role and the traditional undervaluation of the contribution it makes to the success of organisations are partially responsible for lack of success in achieving sustainable facilities. The overwhelming barrier for sustainable FM practice is the lack of understanding, focus and commitment of senior executives in appreciating the opportunities, threats and need for strategic leadership and direction in driving essential change, and hence further the sustainability agenda.     

Impact of order and load knowledge on trunk kinematics during repeated lifting tasks

OBJECTIVE: To determine if lifting random unknown weights is more detrimental than lifting sequences of unknown weights and to investigate whether load knowledge impacts the effect of lifting random box weights. BACKGROUND: Much research has investigated lifting under known load conditions, but few studies have investigated unknown loads, especially when presented in random order. There has been some documentation of alteration in trunk mechanics when there is an overestimation of the unknown load. METHOD: Ten men and 10 women performed three lifting tasks: random unknown, random known, and same weight. A lumbar motion monitor was used to collect kinematic data, and Borg's Rating of Perceived Exertion (RPE) and a task risk rating were also assessed. RESULTS: Both presentation order and load knowledge impacted trunk kinematics during repeated lifting tasks. However, these differences were relatively low in magnitude. Furthermore, kinematic response and perceived risk and exertion for these conditions varied between genders. CONCLUSION: Lifting random unknown loads appears to alter kinematic responses, particularly for men. Women attempt to modify the effect of random unknown loads by changing the lifting style through alterations in upper limb motions (e.g., drag box toward them prior to lifting). However, a need remains for a more comprehensive biomechanical investigation (e.g., spine loading) into the effects of random unknown loads because many of the effect sizes were small. APPLICATION: Small kinematic adaptations resulting from tasks involving unknown and random loads may be mediated by the use of visual cues, order of presentation, or a change in lifting style.     

The Effect of Deposition Conditions on Adhesion Strength of Ti and Ti6Al4V Cold Spray Splats

Cold spray is a complex process where many parameters have to be considered in order to achieve optimized material deposition and properties. In the cold spray process, deposition velocity influences the degree of material deformation and material adhesion. While most materials can be easily deposited at relatively low deposition velocity (<700 m/s), this is not the case for high yield strength materials like Ti and its alloys. In the present study, we evaluate the effects of deposition velocity, powder size, particle position in the gas jet, gas temperature, and substrate temperature on the adhesion strength of cold spayed Ti and Ti6Al4V splats. A micromechanical test technique was used to shear individual splats of Ti or Ti6Al4V and measure their adhesion strength. The splats were deposited onto Ti or Ti6Al4V substrates over a range of deposition conditions with either nitrogen or helium as the propelling gas. The splat adhesion testing coupled with microstructural characterization was used to define the strength, the type and the continuity of the bonded interface between splat and substrate material. The results demonstrated that optimization of spray conditions makes it possible to obtain splats with continuous bonding along the splat/substrate interface and measured adhesion strengths approaching the shear strength of bulk material. The parameters shown to improve the splat adhesion included the increase of the splat deposition velocity well above the critical deposition velocity of the tested material, increase in the temperature of both powder and the substrate material, decrease in the powder size, and optimization of the flow dynamics for the cold spray gun nozzle. Through comparisons to the literature, the adhesion strength of Ti splats measured with the splat adhesion technique correlated well with the cohesion strength of Ti coatings deposited under similar conditions and measured with tubular coating tensile (TCT) test.