Design and Implementation of a Radix-100 Division Unit

In this thesis, a novel radix-100 divider is designed and implemented. The proposed divider is 3% faster then the current decimal dividers

Revisiting sum of residues modular multiplication

the 1980s,when the introduction of public key cryptography spurred interest in modularmultiplication, many implementations performed modularmultiplication using a sumof residues. As the fieldmatured, sum of residues modularmultiplication lost favour to the extent that all recent surveys have either overlooked it or incorporated it within a larger class of reduction algorithms. In this paper, we present a new taxonomy of modular multiplication algorithms. We include sum of residues as one of four classes and argue why it should be considered different to the other, now more common, algorithms.We then apply techniques developed for other algorithms to reinvigorate sum of residues modular multiplication. We compare FPGA implementations of modular multiplication up to 24 bits wide. The Sum of Residues multipliers demonstrate reduced latency at nearly 50% compared to Montgomery architectures at the cost of nearly doubled circuit area. The new multipliers are useful for systems based on the Residue Number System (RNS).Yinan Kong and Braden Phillip

Analysis and implementation of decimal arithmetic hardware in nanometer CMOS technology

Scope and Method of Study: In today's society, decimal arithmetic is growing considerably in importance given its relevance in financial and commercial applications. Decimal calculations on binary hardware significantly impact performance mainly because most systems utilize software to emulate decimal calculations. The introduction of dedicated decimal hardware on the other hand promises the ability to improve performance by two or three orders of magnitude. The founding blocks of binary arithmetic are studied and applied to the development of decimal arithmetic hardware. New findings are contrasted with existent implementations and validated through extensive simulation.Findings and Conclusions: New architectures and a significant study of decimal arithmetic was developed and implemented. The architectures proposed include an IEEE-754 current revision draft compliant floating-point comparator, a study on decimal division, partial product reduction schemes using decimal compressor trees and a final implementation of a decimal multiplier using advanced techniques for partial product generation. The results of each hardware implementation in nanometer technologies are weighed against existent propositions and show improvements upon area, delay, and power

Investigating the Utility of the WMS-IV with Novel Procedures as an Assessment Tool for Accelerated Long Term Forgetting in Temporal Lobe Epilepsy

Research suggests some individuals with Temporal Lobe Epilepsy (TLE) experience an increased rate of forgetting for new information; currently defined as ‘Accelerated Long-Term Forgetting’ or ALF (Butler & Zeman, 2008). This novel construct goes undetected by standard neuropsychological measures and only becomes apparent after longer testing delays. However, as yet there have been no specific measures developed for the assessment of ALF. Consequentially, it is often undetected in TLE and research (relying on various novel or adapted measures) is yielding inconsistent findings. The present study aimed to build upon the findings of a previous research project (Crowley, 2014) by adapting an existing and widely used neuropsychological measure (Wechsler Memory Scale - Fourth UK Edition [WMS-IVUK]; Wechsler, 2010) in an attempt to assess its utility at detecting ALF in TLE. 25 TLE participants and 26 unaffected controls were administered selected WMS-IVUK subtests with an additional one-week recall and recognition delay. Participants also completed a comprehensive neuropsychological battery of cognitive and non-cognitive measures. Data was analysed at the group and individual level, and the contribution of non-memory cognitive and non-cognitive variables was considered. When analysed at the group level, TLE participants displayed evidence of verbal and visual ALF on selected WMS-IVUK subtests, even when the mediating role of non-memory variables was considered. Individual analysis revealed a range of memory profiles in the TLE group. Some participants displayed primary difficulty in the encoding/retrieval of new information, assessed across standard delays. It was unclear whether these individuals also experienced accelerated forgetting. Other individuals displayed a memory profile consistent with current definitions of ALF and performed worse than controls at the extended delay despite performance being comparable at the standard delay. Evidence of ALF was observed for all three WMS-IVUK subtests, on tasks of recall and recognition. Findings suggest the utility of the WMS-IVUK at detecting ALF in TLE

The feasibility of the dual-task paradigm as a framework for a clinical test of listening effort in cochlear implant users

The overall aim of this thesis is to evaluate the feasibility of using the behavioural framework of the dual-task paradigm as the basis of a clinical test of listening effort (LE) in cochlear implant (CI) users. It is hypothesised that, if a primary listening task is performed together with a secondary visual task, performance in the visual task will deteriorate as the listening task becomes harder. This deterioration in secondary visual task performance can then provide an index of LE. An initial series of six experiments progressively modified the dual-task design (in an attempt to optimise its sensitivity to LE), leading to the selection of British English Lexicon (BEL) sentences for the listening task and a digit stream visual task. A further three experiments applied this dual-task to 30 normal hearing (NH) participants listening to normal speech, 30 NH participants listening to CI simulations, and 25 CI users listening through their speech processors. Performance in quiet conditions was compared to that in different levels of background noise. Adaptive tracking procedures were used in an attempt to ensure that the challenge of noise was equal for all participants. This principle was also applied to equalise difficulty in terms of the number of channels used in the spectral resolution of the CI simulations. As expected, NH participants only exhibited significant deterioration in visual accuracy when noise was present (p<.001), suggesting increased LE. Interestingly, however, when CI simulations were applied, this significant visual deterioration occurred immediately in quiet (p<.001). The same result occurred in quiet for the CI users too (p<.001). Therefore, it appears that the degraded auditory input provided by CI induces LE even in optimal listening conditions. These results suggest that the dual-task paradigm could feasibly become a framework for developing a clinical test of LE in the CI user population

The effect of phospholipid supplementation on cognitive performance across the lifespan

Phospholipids (PLs) are found abundantly in mammalian cell membranes and support cellular health and function. Their composition and shape promotes asymmetry within membrane bilayers and affects membrane physiological properties. PLs have the potential to facilitate cognitive function. A systematic review identified ten PL supplementation studies, including two acute and eight chronic (≥ 2 week) interventions. Cognitive benefits, mainly memory enhancement, were reported for a single PL, phosphatidylserine, and a bovine milk-derived PL composite, which was used in the supplementation studies reported in this thesis. The quality of the empirical studies reviewed was compromised by poor study designs and/or analytical approach. Moreover, the review highlighted a lack of empirical studies considering PL supplementation in children and adolescents. The focus of this thesis was to investigate the potential for bovine milk-derived PLs to promote cognitive function. Study 1 (n=70) was the first randomised placebo-controlled trial of the effects of PLs on cognitive performance in school-aged children (6-8 years). This was a six week intervention trial during which the children were tested every 3 weeks on measures of memory, motor skills, executive function and processing speed. Subjective evaluations of appetite, mood, motivation and mental alertness were also measured. The impact of the supplement on cognitive performance was limited. There was also no discernible effect on subjective state. Study 2 (n=50) extended limited existing evidence to examine effects of PL supplementation in middle-aged/older adults with a subjective memory complaint. This randomised placebo controlled trial investigated the acute and chronic effects of PL supplementation over 12 weeks on cognitive measures of memory and executive function and self-reports on the Cognitive Failures Questionnaire. Cognitive performance and the frequency of cognitive failures was measured at week 0 (acute), week 6 and week 12 (chronic). Few effects on cognitive performance following both acute and chronic supplement consumption were observed. Cognitive failures were reduced in participants who received the active supplement and reported greater cognitive failures at baseline. Across both studies, participants’ demographic characteristics and baseline performance had a greater impact on cognitive performance than the active supplement. Overall, the findings from the PL intervention studies presented in this thesis add to the existing heterogeneous evidence of the potential for PLs to moderate cognitive performance. Despite strong mechanistic data suggesting PLs could confer beneficial and/or protective effects on cognition, this thesis did not find clear evidence of a benefit of PLs for cognition. Further examination of the potential benefits of PLs in other formulations for cognitive function in young and old samples is warranted