Operator orientation and compatibility in visual-motor task performance

This experiment assessed three alternative forms of directional compatibility between control and display movement, to examine their degree of dependence on the orientation of the operator. Subjects performed a target acquisition task in each of 11 conditions which embodied the three compatibility types alone or in combination. Visual-motor (VM) compatibility was defined as display movement in a given direction in the subject's visual field produced by control movement in the same direction in the subject's 'virtual' visual field (i.e., were he or she looking at the control rather than the display). Control-display (CD) compatibility referred to congruence between control and display movements. Visual-trunk (VT) compatibility was present if a control movement was in the same direction relative to the operator's trunk as the movement of the display in the visual field. VM compatibility produced performance superior to that under CD or VT compatible conditions in all phases of the task, and was independent of the subject's physical orientation and of the target direction. Visual-motor compatibility appears to reflect a basic and general relationship between visual and motor codes in the central nervous system, and may prove a useful basis for reducing errors and enhancing performance in certain human-machine systems.     

纳米技术及其应用

纳米技术是21世纪的关键技术,它带动激励了许多产业．特别对于纺织行业。纳米颗粒包括各种元素和化合物．以二氧化钛纳米颗粒为例,解释了它们有趣的各种表面性能．给纺织品的创新提供了路线。     

Behavior of internal stakeholders in project portfolio management and its impact on success

Stakeholder behavior and stakeholder management are key success factors within project portfolio management (PPM). This empirical study of 197 project portfolios investigates the effect of the intensity of engagement (IoE) of portfolio-internal stakeholders on project portfolio success. We show that the effect of stakeholders is phase-specific and that role clarity as a measure of PPM maturity affects the nature of the relationship between the IoE of stakeholders and portfolio success. The effects of the IoE of senior managers on success are not clearly positive with regard to strategic portfolio structuring and are even negative in operative portfolio steering in established PPM systems. In immature PPM systems, line managers tend to take advantage of their position in resource management. Surprisingly, the influence of portfolio managers in portfolio steering is insignificant. Altogether, this paper shows the diverse effect of the IoE of stakeholders on portfolio success. This study enriches project research by applying stakeholder theory to the project portfolio context and offers practical guidance for further professionalizing PPM.     

Abstraction and subsumption in modular verification of C programs

Formal Methods in System Design - The type-theoretic notions of existential abstraction, subtyping, subsumption, and intersection have useful analogues in separation-logic proofs of imperative...     

Analysis of yield of winter wheat grown at increasing levels of potassium

Winter wheat was grown in pots receiving 0 (K₀), 60 (K₁) and 120 (K₂) mg K 100 g^?1 soil to investigate the effect of potassium (K) supply on the following yield components: number of ears, number of grains per ear and single grain weight. Mature grain yield increased from 34.5 g per pot at K₀ to 81 g at K₁ and 89.9 g per pot at K₂. Straw yield increased from 35.4 (K₀) to 123.2 g per pot (K₂), reflecting an increase in leaf area and photosynthesis. K fertiliser lengthened the period of grain filling by 3-4 weeks both by advancing anthesis and delaying senescence. The longer grain filling period fed by more abundant assimilates resulted in single grain weights of about 40 mg in central and lower spikelets and as much as 30 mg in the apical spikelets.     

Directional stimulus-response compatibility: a test of three alternative principles

The basis of directional stimulus-response compatibility was studied using a task in which 128 participants moved a cursor into targets with a joystick, resembling the operation of certain industrial and construction equipment. Compatible and incompatible versions of three alternative compatibility principles were compared in all combinations. Visual Field (VF) compatibility was present if cursor and controlling limb movement were in the same direction in the visual field, Control Display (CD) compatibility meant that the control motion was in the same direction as, and parallel to, cursor motion, and Muscle Synergy (MS) compatibility was defined as use of the muscle synergy normally associated with the required direction as seen in the visual field. VF-compatible conditions had significantly shorter reaction, movement and homing times, and fewer reversal errors, for males and females, in two testing sites. These advantages were maintained over practice. VF compatibility was confirmed as a robust spatial compatibility principle that is affected by neither the orientation of the operator's limb or head nor the muscle synergy used in executing the task. It offers not only more rapid performance, but also a markedly reduced rate of potentially dangerous directional errors. The relationship between this finding and theoretical aspects of stimulus-response compatibility is discussed.     

Pharmacokinetics of once-daily amikacin dosing in patients with cystic fibrosis

PURPOSE: To report the injection of tissue plasminogen activator into a retinal vein to treat central retinal vein occlusion. METHODS: An 81-year-old woman with visual loss of the right eye secondary to central retinal vein occlusion developed central retinal vein occlusion and visual loss in her left eye. Treatment of her left eye with topical ocular hypotensive medications, pentoxifylline, and laser chorioretinal anastomosis was without benefit. Thereafter, she underwent vitreoretinal surgery, including tissue plasminogen activator injection into a branch retinal vein of her left eye. RESULTS: The patient reported subjective improvement in the vision of her left eye. Ophthalmoscopic and fluorescein angiographic improvement were also noted. CONCLUSION: The feasibility of cannulating a retinal vein for treatment has been demonstrated.     

Design and performance of a diffusion-suppressed streamer chamber

We have designed, built, and tested a high-resolution streamer chamber that employs a novel diffusion suppression scheme. The chamber operates at 60 atm, uses a few-nanoseconds-wide 250 kV high-voltage pulse, has a maximum repetition rate of 10 Hz, and has an active volume of 13.5 × 4.5 × 0.7 cm³. Under these conditions we measure the rms deviation of streamer centers from fitted track trajectories to be about 12 ωm in space, and a two-track resolution of approximately 50 ωm.     

A comparative evaluation of calculator watch data entry technologies: Keyboards to chalkboards

Future limitations on the usable complexity of wrist-worn digital devices will depend upon the flexibility and data transmission rate/accuracy of the user-system interface. Three candidate interface types were evaluated as represented by current calculator watch technology. These included hardware keys, software keys and figural recognition. While the figural recognition device theoretically required the least training to operate, other factors degraded operator performance considerably. Specifically, entry rates were slower for this device and error rates higher than for the other two types of devices. It was concluded that the most promising inteface for future applications of this type will require technological advances before it becomes competitive with the other interface types.