Background: Dual pneumatic systems use two separate air line tubes to open and close the cutter and can achieve high cut rates. The purpose of this study is to evaluate the influence of gauge size, cut rate and aspiration on the flow rate performance of ultra high-speed cutters operated with a commercially available dual pneumatic vitrectomy system. Methods: Analysis of a high-speed video was used to determine duty cycle. Flow rates from 20-, 23- and 25-gauge cutters were calculated in predetermined conditions of aspiration levels and cut rates; water and fresh porcine vitreous samples were studied. Results: For all three gauges of cutters, the duty cycle and water flow showed an inverse correlation with increasing cut rates and a direct correlation with increasing aspiration levels (p < 0.05). Vitreous flow rates from all gauges increased with increasing aspiration and cut rates (p < 0.05). Conclusion: Larger gauges of the cutters as well as higher aspiration and cut rate levels resulted in improvement of the vitreous flow rates. A good understanding of the different flow rate settings is essential for the surgeon and optimizes the safety of surgical procedures.
Purpose
Determine the performance of dual pneumatic ultra high-speed 23-gauge cutters operated with variable duty cycle (DC) settings.
Methods
Frame-by-frame analysis of high-speed video was used to determine the DC in core, 50-50 and shave modes. Using three cutters at various cycles per minute (CPM) and aspiration levels, mass of water or vitreous removed from a vial was measured within a specified time period. Average flow rates were calculated for each aspiration level and cut-rate with the different DC options.
Results
The DC increased with increasing cut rate in shave mode, was relatively stable in the 50-50 mode and decreased for the core mode. The DC converged at 5000 CPM for the three different modes. Water flow curves followed the DC variation. Vitreous flow rates for all the DC modes increased with increasing cut rates and peaked at 5000 CPM (P<0.05). The results of the 50-50 mode, that had isolated the DC influence, showed that increasing aspiration and/or cut rate, independently increased the vitreous flow rate.
Conclusion
Progressive values of aspiration and/or cut rate, increases the vitreous flow rate, independently of the DC. DC control also has an important effect on the vitreous flow; but this effect was reduced at high cut rates due to convergence of the DC modes.
This study compares the potential of the methods of inventive principles (IPR) of TRIZ (MIPT) and BioTRIZ (MIPB) in relation to stimulating creativity in problem solving. The two methods were applied to different issues by groups of undergraduate students. The solutions were evaluated in terms of creativity, which was defined by the criteria of originality and utility. Quantitative analysis provided evidence that the two methods are equal in terms of creative contributions. However, further analyses indicate that the IPs derived from biological systems tend to provide a greater creative contribution compared to those based on technical systems. In addition, it was found that repeated inventive principles (IPR), that is, those indicated more than once by the applied methods, tend to introduce a greater potential for stimulating creativity compared to inventive principles (IPs) indicated only once.
The development of new and innovative products consists in a competitive advantage, allowing companies to overcome competitors, maintain or even increase its market share. As the product development cycle is shortening, a greater effort is required at the ideation of new technologies and products. In this context, the bio-inspired design has been receiving attention as a creativity strengthening method. However, the majority of methods and tools proposed in this field present biological stimuli in the form of literature extracts, requiring a great cognitive effort from the design teams in abstracting principles to generate ideas. In this paper a systematic approach to biological stimuli development is presented, as well as its contribution during the ideation process. An experiment was conducted on the context of a product design course. As result, it was evidenced that the biological stimulators contributed to the increase of the ideas' utility and variety, favoring the innovation process.
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