The present thesis aimed to investigate the source of interference in recognition memory. There are two primary alternatives – the item noise approach, in which interference comes about as a consequence of the other items on the study list, and the context noise approach, wherein interference arises from the previous contexts in which an item has been encountered. Alternatively, interference may occur through a combination of both item and context noise. There are many mathematical models designed to simulate the recognition process that incorporate either item or context noise, or both. Item noise models predict a significant list length effect, that is, that memory for an item that was part of a short list at study is better than that for an item that was part of a long list. Context noise models no not predict a significant difference in memory based on the length of the study list. The presence or absence of the list length effect can therefore be used as a mechanism by which to differentiate item and context noise models. The list length effect is among the most documented and replicated findings in the recognition memory literature (Gronlund & Elam, 1994). Yet, while many experiments have been conducted which have identified a significant list length effect in recognition (e.g. Bowles & Glanzer, 1983; Cary & Reder, 2003; Murnane & Shiffrin, 1991; Ohrt & Gronlund, 1999; Strong, 1912; Underwood, 1978), a number of published studies have failed to identify the effect (e.g. Dennis & Humphreys, 2001; Dennis, Lee & Kinnell, 2008; Jang & Huber, 2008; Murnane & Shiffrin, 1991; Schulman, 1974). Dennis and Humphreys (2001) argued that studies that had identified a significant effect of list length on recognition performance had done so because of a failure to control for four potentially confounding variables; retention interval, attention, displaced rehearsal and contextual reinstatement. The possible confounding effects of retention interval and displaced rehearsal are already well established in the literature and most studies employ some controls for these. Dennis et al. (2008) also found that while the role of contextual reinstatement had a pronounced influence on the detection of the list length effect it did not appear to be the most influential of the potential confounds. Thus, a major aim of the present thesis was to investigate the role of attention in the identification of the list length effect. Experiment 1 (N=160) involved two manipulations of attention. The first was to use either a retroactive or proactive design, with differential lapses of attention likely to be more pronounced in the latter. Second, in one condition participants were asked to perform a pleasantness rating task at study, a common technique to encourage participants to attend to the stimulus, while in the other condition they were asked to simply read the words. Results indicated that attention modulates the list length effect and that it is the retroactive versus proactive distinction which is most important as a significant effect of list length was found only when the proactive design was used. The encoding task had little effect. The design of Experiment 2 (N=80) was based on Cary and Reder's (2003) Experiment 3 which itself was a partial replication of Dennis and Humphreys' (2001) experiments. Cary and Reder introduced the Remember-Know (RK) task into the test list in their experiments and identified a significant effect of list length in the presence of controls for the four confounds where Dennis and Humphreys had not. The RK task is thought to index the relative contributions of familiarity and recollection in the recognition process (Gardiner, 1988). To the extent that the RK task encourages a recall-like process (see Clark, 1999; Diana, Reder, Arndt & Park, 2006) it may influence the results regarding the list length effect, in that the effect is widely accepted to occur in recall. Experiment 2 compared recognition memory with or without RK instructions. One condition involved the standard yes/no recognition paradigm, while the other made us of the RK task following all “yes” responses. Controls for the four potential confounds of Dennis and Humphreys were implemented. No significant effect of list length was identified in the accuracy data of either condition, however there was a small but significant effect on median response latency for correct responses in the RK task condition. The results of Experiments 1 and 2 suggest that the effect of list length on recognition performance is negligible and nonsignificant when controls for the four potential confounds of list length are in place. However, both of these experiments, and almost all previous experiments investigating the list length effect, used words as the stimuli. The remaining four experiments in the present thesis (N=40 in each) sought to investigate the list length effect using stimuli other than words in an attempt to identify the boundary conditions of the effect. Each of these experiments followed the same basic method as Experiments 1 and 2. Four different kinds of stimuli were investigated, word pairs, images of novel faces, fractals and photographs. Results indicated a nonsignificant effect of list length for word pairs and photographs, however, there was a significant list length effect when faces (in the accuracy data) and fractals (in the response latency data) were used as the stimuli. However, all of the experiments in the present thesis used a within subjects manipulation of list length in order to maximise experimental power. This design may be an additional confound of the list length effect. The nature of the within subjects design means that by the end of the second study list, all participants will have studied the same number of items, thereby potentially removing any list length manipulation from the experiment. In addition, participants who studied the long list first may be more likely to be affected by lapses in attention than participants who began with the short list with this, rather than interference, the potential cause of any list length differences. In order to investigate this potential confounding, the results from all experiments of the present thesis were re-analysed using a between subjects analysis based on only the first list studied by each participant. The qualitative conclusions drawn from the majority of conditions remained unchanged. The between subjects analysis generally revealed larger effect sizes than did the within subjects analysis, although with the exception of the proactive conditions, these effects can be considered negligible to small at most. The pattern of results across the six experiments of the present thesis are problematic for existing mathematical models of recognition memory. While context noise models are able to account for negligible and nonsignificant effects of list length when words, word pairs and photographs are used as the stimuli, they are unable to predict a slightly larger and significant list length effect when the stimuli are novel faces or fractals. Conversely, while item noise models are able to account for a significant list length effect for faces and fractals, they are unable to predict a nonsignificant list length effect for words and word pairs. The results question whether either item or context noise can be taken as the sole source of interference in recognition memory. Rather, a combination of interference from different sources may be at work, with the precise nature of this combination dependent on the nature of the stimuli involved. However, it is important to note that these models must be able to all but eliminate interference from other items under certain conditions to obtain the negligible list length effect findings reported here. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474563 / Thesis (Ph.D.) -- University of Adelaide, School of Psychology, 2009

When using timber for construction purposes it is important to know its strength. One way to do this is by sorting the boards into strength classes that are defined by European standards.  A commonly used method for strength grading is based on dynamic excitation in the longitudinal direction of the board to obtain an average dynamic longitudinal modulus of elasticity (MOE). This in turn correlates with the bending strength of the board in such a way that it can be used as an indicating property (IP) to bending strength. The use of MOE as an IP has proven to give the highest coefficient of determination (R2) to both bending and tensile strength in boards. Through the research described in this thesis, one might find that both reducing the length of a board to half its initial length and by removing the part containing the lowest local MOE in edgewise bending provided similar results, the axial dynamic MOE remaining within a 1% tolerance whereas the lowest IP based on local MOE in edgewise bending increased by 6–7%.

Interactions of simvastatin with zwitterionic dipalmitoyl phosphotidylcholine (DPPC) multilamellar liposomes were investigated as a function of temperature and simvastatin concentration. And acyl chain length effect on the simvastatin-model membrane interactions was monitored with DPPC and dimyristoyl phosphotidylcholine (DMPC) lipids. All studies were carried out by two non-invasive techniques, namely Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). The results showed that as simvastatin concentration increased, the main phase transition temperature decreased, the main phase transition curve broadened, and the characteristic pretransition was disappeared for both DMPC and DPPC model membranes. All concentrations of simvastatin disordered and decreased the fluidity of phospholipid membranes. Analysis of C=O stretching band showed that simvastatin either strengthen the existing hydrogen bonds of the glycerol skeleton closer to the head groups or caused the formation of new hydrogen bonds. A dehydration effect caused by simvastatin around the PO2- functional groups in the polar part of the lipids was monitored. This dehydration effect in the gel phase was more profound than in the liquid crystalline phase for 1, 6, and 12 mol% of simvastatin concentrations. DSC peaks broadened and shifted to lower temperature values by increasing the simvastatin concentration. For both lipids, simvastatin-induced lateral phase separation was observed in the DSC thermograms. Any change caused by the acyl chain length difference of DMPC and DPPC lipids was not observed on the simvastatin-membrane interactions. Also, for both of the lipids similar trends were observed in the FTIR and DSC results. More profound effects of simvastatin on the less stable DMPC membranes were observed.

No description available.

Visual processing is the earliest core process required to support a normal reading system. However, little attention has been given to its role in any of the existing cognitive/computational models of reading. The ultimate goal of this thesis is to create a large-scale model of reading, which can generate phonology and semantics from print. Building such a model will allow for the exploration of a number of theoretically important cognitive phenomena in both normal and impaired reading including: font and size invariance; letter confusability; length effects; and pure alexic reading patterns. To achieve this goal, there are a number of important sub-goals that need to be achieved: (1) to develop a visual processing component which is capable of recognising letters in different fonts and sizes; (2) to produce a model that can develop useful intermediate (orthographic) representations as a consequence of learning; (3) to develop a set of semantic representations compact enough to allow efficient learning but that can still capture realistic semantic similarity relationships; (4) to integrate all the components together into a large-scale recurrent reading model; and (5) to extend the model to support picture naming, and to explore whether damage to the visual system can produce symptoms similar to those found in PA patients. Chapter 2 started by developing a simple feedforward network for letter recognition. The model was trained with letters in various transformations, which allowed the model to learn to deal with size and shape invariance problems as well as accounting for letter confusability effects and generalising to previously unseen letters. The model achieved this by extracting key features from visual input which could be used to support accurate letter recognition. Chapter 3 incorporated the letter recognition component developed in Chapter 2 into a word reading model. The reading model was trained on the mappings between print and phonology, with the orthographic representations which learn to emerge over training. The model could support accurate nonword naming and simulated the length by lexicality interaction observed in normal reading. A system of semantic representations was developed in Chapter 4 by using co-occurrence statistics to generate semantic codes that preserved realistic similarity relationships. Chapter 5 integrated all the components developed in the previous chapters together into a large-scale recurrent reading model. Finally, Chapter 6 extended the reading model to perform object recognition along with the reading task. When the model's visual system was damaged it was able to simulate the abnormal length effect typically seen in PA patients. The damaged model also showed impaired reaction times in object naming and preserved sensitivity to lexical/semantic variables in reading. The picture naming performance was modulated by visual complexity. In summary, the results highlight the importance of incorporating visual information into computational models of single word reading, and suggest that doing so will enable the exploration of a wide range of effects that were previously inaccessible to these types of connectionist models.

This research thesis reports experimental work done to design a stable magneticmicroemulsion of ionic liquid in 2-ethylhexyl laurate with the help of an ionic surfactant andan alcohol co-surfactant. The ionic liquids tested were based on a 1,3-dialkylimidazoliumcation with different alkyl chain lengths and a tetrachloroferrate anion ([FeCl4]+) to ensure theemulsion is sensitive to applied magnetic fields. Tests of solubility of these ionic liquids havebeen performed in different solvents and oils. Emulsification tests have been done withdifferent dispersing medium, surfactants as well as with different components quantities tofind the best composition possible. Polarity and chain length of alkyl radicals in ionic liquidsand hydrocarbons in alcohol co-surfactants were proved to affect the emulsification process.Shorter chains, and higher polarity of [C1C2im]+ [FeCl4]- (at 1wt%) combined with [C1C12im]+[FeCl4]- surfactant (between 3 and 5wt%) and non-polar 1-Hexanol co-surfactant (at 10 wt%)were the best combination to create a stable magnetic microemulsion in 2-ethylhexyl laurate. Applications for this microemulsion could vary from improved oil recovery to transport ofmaterials in liquid medium for examples and have all in common a better and tunablecontrollability of the used liquid via magnetic fields. / Denna forskningsuppsats rapporterar experimentellt arbete som gjorts för att designa enstabil magnetisk mikroemulsion av jonisk vätska i 2-EtylHexyllaurat med hjälp av ett jonisktytaktivt ämne och ett alkoholsamverkande ytaktivt ämne. De joniska vätskorna som testadesvar baserade på en 1,3-dialkylimidazoliumkatjon med olika alkylkedjelängder och entetraklorferratanjon ([FeCl4]+) för att säkerställa att emulsionen är känslig för applicerademagnetfält. Tester av lösligheten av dessa joniska vätskor har utförts i olika lösningsmedel ocholjor. Emulgeringstester har gjorts med olika dispergeringsmedium, ytaktiva ämnen samt medolika mängd komponenter för att hitta bästa möjliga sammansättning. Polaritet ochkedjelängd för alkylradikaler i joniska vätskor och kolväten i alkoholsamverkande ytaktivaämnen visade sig påverka emulgeringsprocessen. Kortare kedjor och högre polaritet för[C1C2im]+[FeCl4]- (vid 1 wt%) kombinerat med [C1C12im]+[FeCl4]- ytaktivt ämne (mellan 3 och 5 wt%) och opolär 1-hexanol medytaktivt medel (vid 10 wt% var den bästa kombinationen föratt skapa en stabil magnetisk mikroemulsion i 2-EtylHexyllaurat. Tillämpningar för denna mikroemulsion kan variera från förbättrad oljeutvinning tilltransport av material i flytande medium till exempel och har alla gemensamt en bättre ochavstämbar styrbarhet av den använda vätskan via magnetfält.