This led to the development of nonzero-dispersion fibers (NZ-DSF). As we shall see, these penalties are reduced if a little chromatic dispersion is present in the fiber because the different interacting waves then travel with different group velocities. Nonzero-Dispersion FiberĪlthough dispersion-shifted fiber overcomes the problems due to chromatic dispersion in the 1.55 μm wavelength window, unfortunately it is not suitable for use with WDM because of severe penalties due to four-wave mixing and other nonlinearities (see Section 5.8). We discuss the salient characteristics of these fibers in this section. Just as dispersion-shifted fibers were developed to reduce the pulse spreading due to chromatic dispersion in the 1.55 μm band, other fiber types have been developed to mitigate the effects of nonlinearities on optical communication systems. Sasaki, in Optical Networks (Third Edition), 2010 2.5.9 Fiber Types to Mitigate Nonlinear Effects Using similar techniques, transmission of 101 WDM channels at 10 Gb/s each over 9000 km has also been demonstrated. By careful span engineering using a large effective area fiber followed by a carefully tailored dispersion compensating fiber, to minimize the dispersion slope, transmission of 120 WDM channels at 20 Gb/s each over 6200 km has been demonstrated. The use of reduced slope fiber increases this length. The ultimate limits of link lengths before the wavelengths need to be demultiplexed and compensated individually are set by the variation in dispersion slope since dispersion slope cannot usually be compensated exactly for all the channels. In addition to chromatic dispersion compensation, chromatic dispersion slope also needs to be compensated. Systems employing NZ-DSF can span longer lengths before chromatic dispersion compensation is required. In systems that have to operate over standard single-mode fiber, chromatic dispersion must be compensated frequently along the link, since the total chromatic dispersion usually cannot be allowed to accumulate beyond a few thousand ps/nm. Sasaki, in Optical Networks (Third Edition), 2010 5.12.3 Chromatic Dispersion Compensation Since neither peak force nor time to peak force of the movement differed in the two tasks, it was concluded that the increased NS' was due to a psychological change associated with execution of the purposive movement.Rajiv Ramaswami. In addition, enhancement of the RP was specific to the negative slope (NS'). The RP preceding the purposive movement was larger than that preceding the non-purposive movement. After two sessions in the non-purposive movement task, the subjects were submitted to the purposive movement task, and were requested to pull the trigger in an attempt to produce target force, the range of which was decided individually on the basis of mean force level in the second session of the non-purposive movement task. In the non-purposive task, the subjects were instructed to pull the trigger at their own pace and at an easily-exerted force level. In this study we defined simple trigger pull as non-purposive, and target force production by pulling the trigger as purposive. We investigated two tasks, non-purposive and purposive movement tasks. Readiness potentials (RPs) preceding a trigger pulling movement were recorded in 9 right-handed male subjects.
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