Aphasia rehabilitation and the strange neglect of speed.

Timing data is infrequently reported in aphasiological literature and time taken is only a minor factor, where it is considered at all, in existing aphasia assessments. This is not surprising because reaction times are difficult to obtain manually, but it is a pity, because speed data should be indispensable in assessing the severity of language processing disorders and in evaluating the effects of treatment. This paper argues that reporting accuracy data without discussing speed of performance gives an incomplete and potentially misleading picture of any cognitive function. Moreover, in deciding how to treat, when to continue treatment and when to cease therapy, clinicians should have regard to both parameters: Speed and accuracy of performance. Crerar, Ellis and Dean (1996) reported a study in which the written sentence comprehension of 14 long-term agrammatic subjects was assessed and treated using a computer-based microworld. Some statistically significant and durable treatment effects were obtained after a short amount of focused therapy. Only accuracy data were reported in that (already long) paper, and interestingly, although it has been a widely read study, neither referees nor subsequent readers seemed to miss "the other side of the coin": How these participants compared with controls for their speed of processing and what effect treatment had on speed. This paper considers both aspects of the data and presents a tentative way of combining treatment effects on both accuracy and speed of performance in a single indicator. Looking at rehabilitation this way gives us a rather different perspective on which individuals benefited most from the intervention. It also demonstrates that while some subjects are capable of utilising metalinguistic skills to achieve normal accuracy scores even many years post-stroke, there is little prospect of reducing the time taken to within the normal range. Without considering speed of processing, the extent of this residual functional impairment can be overlooked.

Performance evaluation of the RPL Protocol in fixed and mobile sinks low-power and lossy networks.

Low-Power and Lossy-Network (LLN) are usually composed of static nodes, but the increase demand for mobility in mobile robotic and dynamic environment raises the question how a routing protocol for low-power and lossy-networks such as (RPL) would perform if a mobile sink is deployed. In this paper we investigate and evaluate the behaviour of the RPL protocol in fixed and mobile sink environments with respect to different network metrics such as latency, packet delivery ratio (PDR) and energy consumption. Extensive simulation using instant Contiki simulator show significant performance differences between fixed and mobile sink environments. Fixed sink LLNs performed better in terms of average power consumption, latency and packet delivery ratio. The results demonstrated also that RPL protocol is sensitive to mobility and it increases the number of isolated nodes.