Many items encoded into episodic memory are highly similar – seeing a stranger’s car may result in a memory representation which overlaps in many features with the memory of your friend’s car. To avoid falsely recognising the novel but similar car, it is important for the representations to be distinguished in memory. Even in healthy young adults failures of this mnemonic discrimination lead relatively often to false recognition, and such errors become substantially more frequent in older age. Whether an item’s representation is discriminated from similar memory representations depends critically on how it is encoded. However, the precise encoding mechanisms involved remain poorly understood. Establishing the determinants of successful mnemonic discrimination is essential for future research into strategies or interventions to prevent recognition errors, particularly in the context of age-related decline. A fuller understanding of age-related decline in mnemonic discrimination can also inform basic models of memory. This thesis evaluated the contribution of encoding processes to mnemonic discrimination both in young adults and in ageing, within the framework of two prominent accounts of recognition memory, the pattern separation account (Wilson et al., 2006) and Fuzzy Trace Theory (FTT; Brainerd & Reyna, 2002). Firstly, a functional magnetic resonance imaging study in young adults found evidence for differences in regions engaged at encoding of images according to the accuracy of later mnemonic discrimination, consistent with both pattern separation and FTT. Evidence of functional overlap between regions showing activity consistent with pattern separation, and activity associated with later accurate recognition was consistent with a role of cortical pattern separation in successful encoding, but there was no direct evidence that cortical pattern separation contributed to mnemonic discrimination. This first evidence of cortical pattern separation in humans was supported by findings that in the majority of pattern separation regions, response functions to stimuli varied in their similarity to previous items were consistent with predictions of computational models. Regional variation in the dimension(s) of similarity (conceptual/perceptual) driving pattern separation was indicative of variation in the type of mnemonic interference minimised by cortical pattern separation. Further evidence of encoding contributions to mnemonic discrimination was provided by an event-related potential study in young and older adults. Older adults showed less distinct waveforms than young adults at encoding of items whose similar lures were later correctly rejected compared to those falsely recognised, supporting the proposal that age-related encoding impairments contribute to the decline in mnemonic discrimination. Finally, a set of behavioural studies found that older adults’ mnemonic discrimination deficit is increased by conceptual similarity, supporting previous findings and consistent with FTT’s account of greater emphasis by older adults on gist processing. However, older adults required greater reduction in perceptual or conceptual similarity in order to successfully reject lures, as uniquely predicted by the pattern separation account. Together, the findings support the notion that encoding processes contribute directly to mnemonic discrimination and its age-related decline. An integrated view of the pattern separation account and FTT is discussed and developed in relation to the current findings.

La cavitation hydrodynamique, et plus particulièrement la cavitation à poche attachée, peut apparaitre et se développer dans des écoulements turbulents complexes à l’intérieur de décollements de la couche limite laminaire. Ce phénomène s’avère être également sensible aux autres gaz présents dans l’écoulement comme l’air. Pour mieux comprendre l’attachement de poches de cavitation dans des décollements laminaires et l’influence de l’air sur celles-ci, nous proposons d’étudier des écoulements laminaires décollés d’huiles silicones visqueuses, contenant une grande quantité d’air, autour d’une géométrie Venturi lisse. Dans notre étude nous observons l’apparition de plusieurs types de poches, d’air ou de vapeur, qui peuvent s’attacher dans différents décollements de l’écoulement laminaire. Le dégazage joue alors un rôle important à hautes pressions, générant des poches d’air attachées présentant des dynamiques particulièrement intéressantes.À très basses pressions, des poches de cavitations peuvent s’attacher provoquantselon la stabilité de l’écoulement une transition à un régime transitionnel laminaire/turbulent dans leurs sillage. Cette même transition peut également apparaitre de façon intermittente à plus hautes pressions dans le sillage d’une bulle d’air recirculante, caractéristique du dégazage dans les écoulement laminaires décollés. Le régime transitionnel laminaire/turbulent, beaucoup moins sensible au dégazage, est caractérisé par de la cavitation de tourbillons, générés à hautes fréquences, dans le sillage d’un bulbe de décollement laminaire “court” le long de la pente du Venturi. Le bulbe se développe jusqu’à transitionner brutalement en bulbe “long” pour une taille de poche assez élevée, on peut associer ce phénomène à la supercavitation. / Hydrodynamic cavitation, more specifically attached cavitation, can emerge et develop in complex turbulent flows within laminar boundary layer separations. This phenomenon might be extremely sensitive to the gaz content in the flow. For an easier understanding of the attachment of cavities into laminar separated flows within the influence of air content, we propose to focus our study on viscous silicon oil laminar separated flows, presenting high gas content, within a smooth Venturi geometry. In this study, the inception of several types of attached cavities, filled with air or oil vapor, can be observed into different laminar flow separations. For high pressures, the degassing phenomenon is dominant in the flow, generating attached cavities filled with air presenting interesting dynamics. For low pressures, attach vapor cavities can emerge inducing, if the flow is unstable, the transition to laminar/turbulent transitioning regime in their wake. This transition can also occurs intermittently at higher pressures in the wake of a recirculating air bubble, characteristic to degassing into laminar separated flows. The laminar/turbulent transitioning regime, less sensitive to degassing, is characterized by vortex cavitation, occurring at high frequencies, at the rear of a “short” laminar separation bubble along the divergent Venturi slope. The “short” laminar separation bubble grows until transitioning to a “long” bubble within an large attached cavity. This transition can be associate to thesupercavitation phenomenon.

In a rectangular cross-section wind tunnel a separated oblique shock reflection is set to interact with the turbulent boundary layer (oblique SBLI) both on the bottom wall and in the corner formed by the intersection of the floor with the side-walls. In such a scenario, shock-induced separation is often seen in each of the streamwise corners, resulting in a highly three-dimensional flow field in the near-wall region. To examine how the corner separations can affect the `quasi-two-dimensional' main interaction and by what mechanism this is achieved, an experimental investigation has been conducted. This examines how modifications to the corner separation influence an oblique shock reflection. The nature of the flow field is studied using flow visualisation, Pressure Sensitive Paint and Laser Doppler Anemometry. A nominal freestream Mach number of 2.5 is used for all experiments with a unit Reynolds number of $40\times10^6$m$^{-1}$, and the shock-generator angle is set to $8^\circ$. The flow conditions are chosen to result in substantial separations both in the corners and along the centreline for the baseline case, which is thought to be a good starting point for this study. The results show that the size and shape of central separation vary considerably when the onset and magnitude of corner separation change. The primary mechanism coupling these separated regions appears to be the generation of compression waves and expansion fans as a result of the displacement effect of the corner separation. The presence and strength of the expansion waves have been overlooked in previous studies. This is shown to modify the three-dimensional shock-structure and alter the adverse pressure gradient experienced by the tunnel floor boundary layer. It is suggested that a typical oblique SBLI in rectangular channels features several zones depending on the relative position of the corner waves and the main interaction domain. In particular, it has been shown that the position of the corner `shock' crossing point, found by approximating the corner compression waves by a straight line, is a critical factor determining the main separation size and shape. Thus, corner effects can substantially modify the central separation. This can cause significant growth or contraction of the separation length measured along the symmetry line from the nominally two-dimensional baseline value, giving a fivefold increase from the smallest to the largest observed value. Moreover, the shape and flow topology of the centreline separation bubble is also considerably changed by varying corner effects.

There is still a great deal that is unknown about various depressive conditions, though it is a very common affliction and cause of disability throughout the world. Not only do the underlying mechanisms of various types of depression remain uncertain, but the mystery of how different treatment options work and who will respond to them also persists. The aim of this study was to identify potential non-invasive biomarkers, to predict responsiveness to electroconvulsive therapy. Two hypotheses were investigated in this study. The first was that patient improvement from baseline on the neurocognitive, computer based pattern separation task prior to the third ECT treatment will correlate with a clinical antidepressant response. The second was that increased prefrontal slowing relative to baseline will correlate with a decrease in depressive symptoms. As a first step to validate this approach, a healthy control group performed both the pattern separation and EEG tasks once per week over the course of three weeks. Patient participants completed both tasks before their first ECT treatment, prior to their third treatment, and prior to their last treatment. A spectral analysis of EEG data was then conducted. Results indicated good test-retest reliability for the pattern separation task and EEG measurements across all three trials in the healthy control group. Results from patient data are inconclusive, but indicates that there is a change from baseline to subsequent trials for at least the EEG measurements. However, a larger sample size is needed to determine this. The limited results from this small patient sample suggest that these measurements may have clinical value in refining ECT treatment, and merit further study.

Cognitive performance declines in depression and increases with physical activity. These changes may in part be due to changes in the level of neurogenesis (the generation and survival of adult-born neurons), which decreases with depression and increases with physical activity. Pattern separation (the formation of distinct neural representations of incoming information through orthogonalizing similar patterns of activation) has also been linked to neurogenesis. This project explores pattern separation within these two populations through three experiments.Experiment 1. Previous research has found impaired pattern separation among individuals with higher depression scores, but who have not been diagnosed with Major Depressive Disorder (MDD). This experiment sought to expand these findings and evaluated behavioral differences during the performance of a continuous recognition pattern separation task among women with MDD and age- and education-matched controls. It was hypothesized that clinically depressed participants would have lower pattern separation scores and would be more likely to incorrectly identify lure stimuli as "old". Contrary to this prediction, clinically depressed participants had higher pattern separation scores, while controls were more likely to misidentify lure items as "old".Experiment 2. While there are many known benefits of regular physical activity, the majority of individuals in the United States do not engage in the recommended levels of fitness training. Furthermore, there have only been a limited number of studies evaluating the effect physical activity may have on cognitive abilities and neurological components and none have evaluated what effect the recommended levels of fitness may have on these areas. The second experiment evaluated differences between individuals with varying levels of physical activity using functional magnetic resonance imaging (fMRI) during the performance of a continuous recognition pattern separation task. It was hypothesized that participants with self-reported higher levels of physical activity would have greater activation in the CA3/dentate gyrus subregions of the hippocampus than those with lower fitness levels and sedentary individuals. Surprisingly, there were no activation differences across groups. Experiment 3. The final experiment explored diffusion tensor imaging (DTI) differences in physical activity levels with the same sample used in Experiment 2. It was hypothesized that participants with self-reported higher levels of physical activity would have indications of increased white matter integrity compared to those with lower fitness levels and sedentary individuals. There were significant differences across groups in DTI measures of white matter integrity (axial diffusivity or AD) in bilateral cingulum, the left temporal middle gyrus, and the right uncinate fasciculus.

ABSTRACT This thesis examines an incongruity that exists within Florida's ESOL program. While the curriculum standards direct teachers to "develop and integrate" skills in speaking, listening, reading and writing, student promotions to higher fluency levels are based solely on reading assessments. Listening assessments are also required to "determine instructional needs," but writing assessments are not required and, in most cases, not given. As a result, reading is prioritized, writing is subordinated, the connection between the two skills is broken, and the mutual benefits of integration are lost. Studies conducted during the last 50 years have consistently shown that the integration of reading and writing produces a symbiosis in which students learn to write from reading and learn to read from writing (Olson and Land pp 269, 289). Many educational programs have now adopted an integrated approach to instruction in reading and writing (Common Core 1). Others, like Florida's ESOL program, tout the idea of integration in the curriculum standards without promoting the practice of integration in the classroom. Without a program of de facto integration, curricular proclamations devolve into hollow platitudes. To reconnect the two skills and restore integration, Florida must require a writing assessment system. This thesis proposes several writing assessments from BEST Literacy, FCAT and the GED program that could be adapted for use. Not only would a writing assessment promote balance and integration, it would better prepare ESOL students to succeed in a world that requires proficiency, not only in reading, but also in writing (Graham 31).

Thesis (M.Sc. (Biochemistry)) -- University of Limpopo, 2012 / Various cytomorphologic and biochemical markers of apoptosis are found in different compartments (plasma membrane, cytoplasm, nucleus, and mitochondria) of target cells. Although the plasma membrane is an easily accessible cellular compartment, relatively little is known about the changes in the expression of plasma membrane glycoproteins during apoptosis, and whether these changes could be used for detection of apoptosis. A critical element of this study was to purify lectins from crude homogenate on glycoprotein-cryogel affinity matrices, and later use the lectins to detect changes on the cell surface of apoptotic cells. Pterocarpus angolensis seed lectin was extracted and fractionated using ammonium sulphate precipitation. The 60 % ammonium sulphate pellet was dissolved in saline azide and purified using Sephadex G-75 affinity chromatography. A 28 kDa lectin was retarded within the column and appeared as a short and broad peak on the chromatogram. Traditionally, Sephadex G-75 column are used predominantly for size exclusion, in this study, the column was used in a non-traditional way for affinity chromatography, as the purified protein is able to bind sugar moieties existing in the structure of Sephadex G-75. A single-step purification of P. angolensis seed lectin was achieved by directly applying unclarified P. angolensis crude extract to the pAAm-cryogel using fetuin as the affinity ligand. Pterocarpus angolensis extract fractionated into 2 peaks, which revealed a highly concentrated band on SDS-PAGE. The results also revealed that an increased binding of the lectin to the fetuin-cryogel matrices was also dependent on the time of incubation. This study suggested very low capacities of the cryogels for the protein due to low coupling sites on the matrix. Taking into account that lectins serve as invaluable tools in diverse area of biomedical research, this study proposed using specific plant lectins to follow the expression of plasma membrane glycoproteins during programmed cell death. Treatment of HL-60 cells with lithium and actinomycin D confirmed a time- and dose-dependent inhibition of proliferation and a decrease in proliferation, which suggest cell death of the treated cells. The observed cell death was further investigated for cellular and biochemical hallmark features of apoptosis, which has shown preferential binding of annexin V-FITC to phosphatidylserine and low molecular DNA ladder. Several FITC labelled lectins were used to detect changes in cell surface glycosylation that accompany apoptosis. This study xvii has shown amongst several FITC-labelled lectins that T. vulgaris lectin could intensively stain the membrane area of apoptotic cells suggesting that the expression of N-acetylglucosamine was significantly increased during actinomycin D induced apoptosis of HL-60 cells. Binding was shown to be specific because it was blocked by the corresponding inhibitory sugar. Thus, the method described in this study could be suitable for the detection of very early stages of apoptosis by recognizing the cell surface carbohydrates of apoptosis.

GaInAsSb is a promising material for mid-infrared devices such as lasers and detectors because it is a direct band gap material with large radiative coefficient and a cut-off wavelength that can be varied across the mid-infrared (from 1.7 to 4.9 μm) while remaining lattice matched to GaSb. On the other hand, the potential of the alloy is hampered by predicted ranges of concentration where the constituents of the alloy become immiscible when the crystal is grown near thermodynamic equilibrium at typical growth temperatures. There have been efforts to extend the wavelength of GaInAsSb alloys through such techniques as digital alloy growth and non-equilibrium growth, but most of the compositional range has for a long time been inaccessible due to immiscibility challenges. Theoretical studies also supported the existence of thermodynamic immiscibility gaps for non-equilibrium growth conditions. Lower growth temperatures lead to shorther adatom diffusion length. While a shorter adatom diffusion length suppresses phase separation, too short an adatom length is associated with increased defect formation and eventually loss of crystallinity. On the other hand, hotter growth temperatures move epitaxial growth closer to thermodynamic equilib- rium conditions, and will eventually cause phase separation to occur. In this study thick 2 μm; bulk GaInAsSb layers lattice-matched to GaSb substrates were grown across the entire (lattice-matched) compositional range at low growth temperatures (450°C), including the immiscibility region, when grown under non-equilibrium conditions with MBE. High quality epitaxial layers were grown for all compositions, as evidenced by smooth morphology (atomic force microscopy), high structural quality (X-ray diffraction), low alloy fluctuactions (electron dispersive spectroscopy in cross sectioned samples), and bright room temperature photoluminescence. Because initial theoretical efforts have suggessted that lattice strain can influence layer stability, we have studied effects of strain on alloy stability. Unstable and metastable alloys were grown hot enough for the onset of phase separation, then progressively strained and characterized. We show that strain is effective in suppressing phase separation. Finally, we performed time-resolved carrier lifetime measurements for InAsSb alloy with low concentrations of Ga to investigate the role of Ga in influencing nonradiative carrier recombination. There have been studies on non-Ga containing antimonide structures (InAsSb, InAs/InAsSb) that show long carrier lifetimes, which suggest that Ga plays a role in reducing carrier lifetime, because Ga-containing structures such as InAs/GaSb superlattices have much shorter carrier lifetimes. Ga may reduce carrier lifetime through native defects that increase background carrier concentration, or that create mid-gap electronic states. Here, a series of GaInAsSb alloys were grown with low to zero Ga concentration. No difference in carrier lifetime was observed between Ga and Ga-free structures, and minority carrier lifetimes > 600 ns were observed. Additional work remains to be done to obtain background carrier densities in the samples with Hall measurements.

College students were assessed as to ego identity status and perceptions of their relationships with parents during their first year away from home. Each parent was also asked to rate the relationship. There was general agreement between parents and adolescents although the data indicate that mothers and adolescents share a more similar view of their relationship than did the fathers and adolescents. The hypothesis that females would report more affection and communication with their parents than would males was partially supported. Daughters were more communicative with their mothers and were more affectionate toward both parents than were sons. Several proposed hypotheses were not supported at all. Males were not more independent nor more satisfied with their independence than the female subjects. Foreclosed youths did not visit home more frequently than the other youths, and individuals who frequently visited home were not less independent nor less affective than those who visited home infrequently. It was also hypothesized that foreclosed and identity achieved youths would report higher levels of affection, communication, and satisfaction with independence in their relationships with parents than would diffused or moratorium youths. One significant result was that foreclosed youths rated themselves as more affectionate than diffused youths toward their mothers.. Another significant finding was in the area of independence. It was hypothesized that the identity achieved and moratorium youths would be more independent from their parents than would the diffused and foreclosed youths. This hypothesis was supported by the adolescents' self-ratings and partially supported by the fathers' ratings. Overall, several sex and identity status differences were found. Only one identity status difference was found among the female subjects, while several identity status differences were found among the male subjects. Although no cause-and-effect relationships can be concluded, the results do indicate that differences in the relationships with parents do occur at the same time as identity status differences.

SAMMANFATTNING: Att skiljas/separera är inget ovanligt i Sverige. Som socialarbetare kan vi möta människor som befinner sig i kris efter en skilsmässa/separation. Dessa människor kan vi komma i kontakt med på olika arenor, exempelvis inom familjerådgivningen och familjerätten. Syftet med uppsatsen var att få en ökad förståelse för hur män och kvinnor som genomgått en skilsmässa/separation upplevt denna samt hur de hanterat situationen. Utöver genomgången av tidigare forskning gjordes sex kvalitativa intervjuer med tre män och tre kvinnor som gått igenom en skilsmässa/separation. Urvalet som användes var strategiskt urval. Resultatet visade att kontroll över skilsmässan/separationen var kopplat till ett tanke- och känslomässigt försprång i processen. Varför respondenterna hanterade situationen som de gjorde förklarades utifrån vilken kontext de befann sig i. Kontexten gav en bättre förklaring till hanteringssättet än vad variabeln kön gjorde. Avslutningsvis diskuterades våra förutfattade meningar och förförståelse i förhållande till studiens resultat och tidigare forskning.