Modifying the temperature dependence of magnetic garnet film coercivity by etching

The temperature dependence of the domain-wall coercive field of epitaxial magnetic garnet films was modified in a defined temperature range by removing the surface layer of the films. Outside the given temperature range the coercivity versus temperature curve did not change. The result supports a model of coercivity according to which different sets of material imperfections are responsible for pinning the domain walls in different temperature regions. Appropriate processing of the samples enables some of the pinning sets to be modified independently of each other

A debugging model for functional logic programs

This paper presents a box-oriented debugging model for the functional logic language ALF. Due to the sophisticated operational semantics of ALF which is based on innermost basic narrowing with simplification, the debugger must reflect the application of the different computation rules during program execution. Hence our debugging model includes not only one box type as in Byrd's debugging model for logic programs but several different kinds of boxes corresponding to the various computation rules of the functional logic language (narrowing, simplification etc.). Moreover, additional box types are introduced in order to allow skips over (sometimes) uninteresting program parts like proofs of the condition in a conditional equation. Since ALF is a genuine amalgamation of functional and logic languages, our debugging model subsumes operational aspects of both kinds of languages. As a consequence, it can be also used for pure logic languages, pure functional languages with eager evaluation, or functional logic languages with a less sophisticated operational semantics like SLOG or eager BABEL

Taking Quantitative Genomics into the Wild

A key goal in studies of ecology and evolution is understanding the causes of phenotypic diversity in nature. Most traits of interest, such as those relating to morphology, life-history, immunity and behaviour are quantitative, and phenotypic variation is driven by the cumulative effects of genetic and environmental variation. The field of quantitative genetics aims to quantify the additive genetic component of this trait variance (i.e. the "heritability"), often with the underlying assumption that trait variance is driven by many loci of infinitesimal effects throughout the genome. This approach allows us to understand the evolutionary potential of natural populations and can be extended to examine the genetic covariation with fitness to predict responses to selection. Therefore, quantitative genetic studies are fundamental to understanding evolution in the wild. Over the last two decades, there has been a wealth of studies investigating trait heritabilities and genetic correlations, but these were initially limited to long-term studies of pedigreed populations or common-garden experiments. However, genomic technologies have since allowed quantitative genetic studies in a more diverse range of wild systems and has increased the opportunities for addressing outstanding questions in ecology and evolution. In particular, genomic studies can uncover the genetic basis of fitness-related quantitative traits, allowing a better understanding of their evolutionary dynamics. We organised this special issue to highlight new work and review recent advances at the cutting edge of "Wild Quantitative Genomics". In this Editorial, we will present some history of wild quantitative genetic and genomic studies, before discussing the main themes in the papers published in this special issue and highlighting the future outlook of this dynamic field.Comment: 17 page (plus references) Editorial for a special issue of Proceedings of the Royal Society B: Biological Sciences. Revised submissio

Dissociable human perirhinal, hippocampal, and parahippocampal roles during verbal encoding

The precise contribution of perirhinal cortex to human episodic memory is uncertain. Human intracranial recordings highlight a role in successful episodic memory encoding, but encoding-related perirhinal activation has not been observed with functional imaging. By adapting functional magnetic resonance imaging scanning parameters to maximize sensitivity to medial temporal lobe activity, we demonstrate that left perirhinal and hippocampal responses during word list encoding are greater for subsequently recalled than forgotten words. Although perirhinal responses predict memory for all words, successful encoding of initial words in a list, demonstrating a primacy effect, is associated with parahippocampal and anterior hippocampal activation. We conclude that perirhinal cortex and hippocampus participate in successful memory encoding. Encoding-related parahippocampal and anterior hippocampal responses for initial, remembered words most likely reflects enhanced attentional orienting to these positionally distinctive items

A digital storybook project with mothers of grade four learners in support of literacy learning : A participatory action learning and action research study

According to the Progress in International Reading Literacy Study (PIRLS, 2016), 78% of grade four children in South Africa's poorest communities lack access to adequate educational resources and infrastructure, which prevents them from reading for meaning in any language. Children in South Africa lack the foundational reading abilities required to finish grade four in compliance with international standards. This project used the participatory action learning and action research (PALAR) approach to prepare mothers to create a digital storybook as learner support material and because participatory action research is a method of evaluation that generates data about an ongoing change process and encourages learning amongst the people most intimately connected to the change. The study centred on the use of digital storytelling as a literacy resource to create learning experiences in the literacy classroom, as well as to determine how PALAR can be used as a methodology to aid mothers in creating a digital storybook. The research objectives guided the workshops held over five weeks with twelve grade four learners’ mothers. I held a two to three-hour, one-day start-up workshop that was recorded and documented. The key advisory set (KAS) members received baseline checklists, which were then sent to the action learning set (ALS) members in their respective groups. The information received from the checklist was used as discussion points in the follow-up workshops. Critical discourse analysis (CDA) served as the foundation for the data analysis. The generated data was interpreted and analysed using Schneider’s (2013) ten work steps. The data-gathering method was based on a qualitative approach and the study was underpinned by critical theory and critical pedagogy that enabled a collective approach which results in greater epistemic justice. The principal, parents, and learning support specialists (LSSs) had informal pre-entry talks before the start of the official data collection. A total of twelve participants were chosen for this study based on their willingness to participate and their being parents or guardians of children in grade four. The research objectives informed three iterative cycles of planning, observing, and reflecting. The usage of both open and closed coding led to the emergence of three main themes, which were understanding literacy, communication between school and parents, and learning materials. iii New categories were created because of the continuous comparison and analysis that were employed between cycles to answer the sub- and main research questions. Data generated throughout the three cycles revealed the mothers' concerns, misconceptions and level of knowledge and commitment to the creation of literacy resources and the possibility of creating a digital storybook. Despite the workshops generating advancement and excitement, the findings indicate that the participants' assessments of their role in the creation of learning materials varied. The report indicates that the parents felt powerless to influence educational decisions based on their past and present experiences regarding their involvement and interaction with the school. It is necessary to employ strategies to put parents at ease and to reassure them that their opinions are important and required to ensure their children’s educational achievement. Essentially, this means ascertaining how to guarantee closer relationships between parents, teachers and learners. Recommendations are made regarding parental involvement in curriculum development based on the study's findings. The recommendations include effective parent-teacher communication through parental involvement in curriculum development, increased parent-teacher interaction to meet learners’ needs more effectively, and finally, an expansion of the study considering a larger sample size, a new study site, and an expansion of the goals beyond the digital storybook.Thesis (MEd) -- Faculty of Education, 202

An Algebra for Delay-Insensitive Circuits

A novel process algebra is presented; algebraic expressions specify delay-insensitive circuits in terms of voltage-level transitions on wires. The approach appears to have several advantages over traditional state-graph and production-rule based methods. The wealth of algebraic laws makes it possible to specify circuits concisely and facilitates the verification of designs. Individual components can be composed into circuits in which signals along internal wires are hidden from the environment

TEMPERATURE-DEPENDENCE OF DOMAIN-WALL COERCIVE FIELD IN MAGNETIC GARNET-FILMS

The coercive properties of magnetically uniaxial liquid-phase epitaxy garnet films were investigated between 10 K and the Neel temperature (T(N) less-than-or-equal-to 500 K). Two independent methods, the results of which are nearly identical (magnetical response of oscillating domain walls and the method of coercive loops measured in a vibrating sample magnetometer), were used. Besides the usual domain-wall coercive field, H(dw), the critical coercive pressure, p(dw), was also introduced as it describes in a direct way the interactions of the domain walls with the wall-pinning traps. Both H(dw) and p(dw) were found to increase exponentially with decreasing temperature. Three different types of wall-pinning traps were identified in the sample and their strength, their rate of change with temperature, and their temperature range of activity were determined

Mitigating susceptibility-induced distortions in high-resolution 3DEPI fMRI at 7T

Geometric distortion is a major limiting factor for spatial specificity in high-resolution fMRI using EPI readouts and is exacerbated at higher field strengths due to increased B0 field inhomogeneity. Prominent correction schemes are based on B0 field-mapping or acquiring reverse phase-encoded (reversed-PE) data. However, to date, comparisons of these techniques in the context of fMRI have only been performed on 2DEPI data, either at lower field or lower resolution. In this study, we investigate distortion compensation in the context of sub-millimetre 3DEPI data at 7T. B0 field-mapping and reversed-PE distortion correction techniques were applied to both partial coverage BOLD-weighted and whole brain MT-weighted 3DEPI data with matched distortion. Qualitative assessment showed overall improvement in cortical alignment for both correction techniques in both 3DEPI fMRI and whole-brain MT-3DEPI datasets. The distortion-corrected MT-3DEPI images were quantitatively evaluated by comparing cortical alignment with an anatomical reference using dice coefficient (DC) and correlation ratio (CR) measures. These showed that B0 field-mapping and reversed-PE methods both improved correspondence between the MT-3DEPI and anatomical data, with more substantial improvements consistently obtained using the reversed-PE approach. Regional analyses demonstrated that the largest benefit of distortion correction, and in particular of the reversed-PE approach, occurred in frontal and temporal regions where susceptibility-induced distortions are known to be greatest, but had not led to complete signal dropout. In conclusion, distortion correction based on reversed-PE data has shown the greater capacity for achieving faithful alignment with anatomical data in the context of high-resolution fMRI at 7T using 3DEPI