Comparing endoscopic systems on two simulated tasks

Endoscopes are slender instruments for performing medical procedures through small incisions or natural body orifices. Three experiments examined the performance effects of various endoscope systems when naive participants executed tasks in a bladder-like environment. The systems involved a direct endoscope, requiring the user to look through a lens at the outer part of the endoscope, and a video endoscope that picks up the image via a camera attached to the endoscope and displays it on a video monitor. The results indicate that the participants performed the tasks better with video than with direct endoscopes, and showed more transfer of practice with video endoscopic surgery from a small to a large task environment than vice versa. The optimal position of the monitor with video endoscopic surgery appeared to involve a reasonable angle relative to the operating area (45 degrees was used). Performance was less at a greater angle (90 degrees), but also at a small angle (10 degrees). It did not matter whether the monitor was located left, right or above the operating area. As performance did not fully transfer to differently sized task environments, endoscopists should initially train with task environments of different, and especially small, sizes.     

Buffer loading and chunking in sequential keypressing.

Thirty-six participants practiced a task in which they continuously cycled through a fixed series of nine keypresses, each carried out by a single finger (cf. Keele & Summers, 1976). The results of the first experimental phase, the practice phase, support the notion that pauses between successive keypresses at fixed locations induces the development of integrated sequence representations (i.e., motor chunks) and reject the idea that a rhythm is learned. When different sequences were produced in the transfer phase, performance dropped considerably unless the sequence was relatively short and there was ample time for preparation. This demonstrates that motor chunks are content specific and that the absence of motor chunks shows when there is no time for advance loading of the motor buffer or the capacity of the motor buffer is insufficient to contain the entire keypressing sequence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detecting short periods of elevated workload: A comparison of nine workload assessment techniques.

The present experiment tested the merits of 9 common workload assessment techniques with relatively short periods of workload in a car-driving task. Twelve participants drove an instrumented car and performed a visually loading task and a mentally loading task for 10, 30, and 60 s. The results show that 10-s periods of visual and mental workload can be measured successfully with subjective ratings and secondary task performance. With respect to longer loading periods (30 and 60 s), steering frequency was found to be sensitive to visual workload, and skin conductance response (SCR) was sensitive to mental workload. The results lead to preliminary guidelines that will help applied researchers to determine which techniques are best suited for assessing visual and mental workload. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deep trapping of implanted Na+ and Li+ ions near the Si/SiO2 interface in metal-oxide-silicon structures

Na⁺ and Li⁺ ions have been implanted in the oxide layer of MOS structures with doses ranging from 3 × 10¹¹ to 3 × 10¹³ ions/cm². Part of the implanted ions can be retraced as mobile ions: this fraction decreased with increasing dose. The trapping of the mobile ions near the Si/SiO₂ interface has been investigated by means of the thermally stimulated ionic current (TSIC) technique. The average energy depth of the ionic traps appeared to increase with increasing dose. Moreover, we found that Li⁺ ions are trapped deeper than Na⁺ ions under equivalent experimental conditions. The influence of the applied electric field on the detrapping has been studied. In the case of 3 × 10¹³ Na⁺ implantation, the barrier lowering corresponds with the Poole-Frenkel theory. We have also paid attention to the effects of bias-temperature stress treatments on the trapping kinetics. We observed a decrease of the mobile ion current after long BTS treatments.     

Preventing drowsiness accidents by an alertness maintenance device

The reported experiment investigated in an advanced driving simulator whether drivers' alertness can be maintained in drowsiness-inducing conditions by a special game-like system, a 'gamebox'. Drowsiness was assessed by self-rating and eye-closures. Mental effort was assessed by a subjective workload rating scale and by a physiological measure (the 0.1 Hz component of heart rate). Driving quality and safety were assessed by steering movements, time-to-line crossings, and by the occurrence of safety-related driving errors--solid line crossings, driving off-road incidents and accidents. When driving with the gamebox, drivers reported a lower degree of drowsiness and fewer instances of sleep episodes as compared to a control condition. Driving with the device resulted in fewer incidents and accidents, and these occurred later in the session. The quality of vehicle control deteriorated progressively over the course of the session, but less so in the gamebox condition. Hence, the results corroborate the notion that mental activity counteracts drowsiness in prolonged driving.     

Evidence for a multistage model of practice in a sequential movement task.

This study explored the effects of practice when discrete keypress sequences were produced in response to a stimulus. Eighteen students practiced 3 sequences with consistent stimulus-sequence mappings and 2 sequences with varied mappings in a 2,500-trial practice phase. In 2 subsequent transfer phases, the performance effects were assessed of a preceding serial reaction time task and of reversal of 2 consistently practiced stimulus-sequence mappings. The results are explained by the development of 3 types of memory codes (stimulus-response associations, stimulus-response rules, and motor chunks) that are used at 2 independent stages in a serial information-processing stage architecture. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Drift of the breakdown voltage in p-n junctions in silicon (walk-out)

A quantitative model for the time behaviour of the walk-out phenomenon in planar p-n junctions is given. The injection of hot carriers into SiO₂ and subsequent trapping of part of them is assumed to be the origin of the walk-out. The model is found to be in reasonable agreement with the experimental results on both p⁺?n and n⁺?p junctions. The parameters in the model are discussed in relation with the experiments.     

Reward and Aversive Stimuli Produce Similar Nonphotic Phase Shifts.

Circadian rhythms in rodents respond to arousing, nonphotic stimuli that contribute to daily patterns of entrainment. To examine whether the motivational significance of a stimulus is important for eliciting nonphotic circadian phase shirts in Syrian hamsters (Mesocricetus auratus), the authors compared responses to a highly rewarding stimulus (lateral hypothalamic brain stimulation reward [BSR]) and a highly aversive stimulus (footshock). Animals were housed on a 14:10-hr light-dark cycle until test day, when they were given a 1-hr BSR session (trained animals) or a 1-mA electric footshock at 1 of 8 circadian times, and were maintained in constant dark thereafter. Both BSR pulses and footshock produced nonphotic phase response curves. These results support the hypothesis that arousal resulting from the motivational significance of a stimulus is a major factor in nonphotic phase shifts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ESD in integrated circuits

A review of the effects of electrostatic discharge (ESD) on semiconductor integrated circuits is presented. The principles of the human body model (HBM), the machine model (MM) and the charged device model (CDM) test methods are outlined, and their relative merits and drawbacks are discussed. Techniques, such as the transmission line pulse method, which may be used to characterise ESD protection circuit elements are also presented. The concept of ESD protection circuit designs and some typical ESD protection circuit elements are presented. The main design and process parameters are identified, and the main categories of damage under ESD conditions are shown. Models of the behaviour of the protection circuit elements under high current conditions are presented, and the boundary conditions for damage are discussed. The issues that will influence ESD protection circuit behaviour in the future are discussed.     

On-line driver workload estimation. Effects of road situation and age on secondary task measures

In order to develop a driver-car interface that adapts the presentation of messages generated by in-vehicle information systems to driver workload, two experiments investigated potential determinants of driver visual and mental workload as indicated by performance on two secondary tasks. Experiment 1 suggested that road situation is a major determinant of visual and mental workload of the driver and that the processing resources of older drivers are somewhat more limited than those of younger and middle-aged drivers. Familiarity with the area of driving (when guided) and time of day (associated with traffic density) showed no secondary task effects. Experiment 2 showed that the categorization of road situations, proposed in Experiment 1, could underlie adaptation of visually loading messages to the workload incurred by driving. This was not found with respect to mentally loading messages.