PubMed · 10660355
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A A Freehafer. 1999. Reconstructive hand surgery.. https://doi.org/10.1038/sj.sc.3100944
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In previous studies, subjects did not hit slowly moving objects as quickly as fast ones, despite being instructed to hit them all as quickly as possible. In those studies the targets moved at constant but unpredictable velocities, and it has been suggested that subjects were unable to adjust the hand's path to suit the velocity of the target. To compensate for this, they adjusted the speed of their hand to that of the target (speed coupling). According to this hypothesis, speed coupling is necessary only when subjects are unable to correctly predict the next target velocity and only if they have to be accurate. We show here that decreasing the uncertainty about the upcoming target's velocity or enlarging the tip of the hitting weapon does not make speed coupling disappear. Moreover, there is a negative correlation between hand velocity and strength of speed coupling, whereas the hypothesis predicts a positive correlation. The hypothesis is therefore rejected. We propose that speed coupling is a result of different speed-accuracy tradeoffs applying to different target velocities.
BACKGROUND: Advanced laparoscopic surgery is complex and time-consuming. Achieving consistent efficacy and safety throughout the entire procedure is always a problem. For this reason, hand-assisted laparoscopic surgery (HALS) was developed. METHODS: Devices were designed to allow manual access to the abdomen through the utility laparotomy. By using one hand in the abdomen during laparoscopy, the surgeon regains direct tactile sensation and acquires improved hand-eye coordination. The safety of the individual devices has been tested in RCT for the registration of the individual devices. An index known as Surgical Action Efficiency was calculated for in six patients undergoing laparoscopic colon resection and six patients with hand-assisted colon resections. RESULTS: All of the registered devices are safe. Surgical Action Efficiency for the laparoscopy group was 55 +/- 14%; for the HALS group, it was 71 +/- 4%. This result is statistically significant (p < 0.05). CONCLUSION: HALS is a safe and efficient method by which it is possible to combine the established convenience and safety of open surgery with the advantages of minimally invasive surgery.
Primary palmar hyperhidrosis (HH) is a pathological condition of overperspiration caused by excessive secretion of the eccrine sweat glands, the etiology of which is unknown. This disorder affects a small but significant proportion of the young population all over the world. Neither systemic nor topical drugs have been found to satisfactorily alleviate the symptoms. Although the topical injection of botulinum has recently been reported to reduce the amount of local perspiration, long-term results are required before a definitive evaluation of this method can be made. Hypnosis, psychotherapy, and biofeedback have been beneficial in a limited-number of cases. While radiation achieves atrophy of the sweat glands, its detrimental effects prohibit its use. Iontophoresis has attained some satisfactory results but it has not been assessed long term. Percutaneous computed tomography-guided phenol sympathicolysis achieves excellent immediate results, but its long-term failure rate is prohibitive. Furthermore, percutaneous radiofrequency sympathicolysis may be an effective procedure, but its long-term results are not superior to surgical sympathectomy. On the other hand, surgical upper dorsal (T2-T3) sympathectomy achieves excellent long-term results and the thoracoscopic approach has supplanted the open procedures. Despite some sequelae, mainly in the form of neuralgia and compensatory sweating which cannot be predicted and may be distressing, surgical sympathectomy remains the best treatment for palmar hyperhidrosis.