by Iris Frances Forster Benzie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 170-184.

Every year 400,000 - 600,000 people in the United States die from sudden cardiac death. Sudden cardiac death is often caused by irregular electrical impulses, or arrhythmias, in the heart. Arrhythmias can be corrected through pharmacological therapies, device therapies, or both. One type of device therapy, pacemakers, are inserted in the heart to correct arrhythmias. After a period of ventricular pacing, cardiac memory is defined by changes in the T-wave that are persistent upon return to normal activation pathways. During ventricular pacing, regional stroke work in areas closest to the pacing electrode is significantly decreased. We hypothesize that the mechanical function in the region around the pacing site will continue to have altered mechanical function after cession of pacing, in effect showing a mechanical cardiac memory. To test the hypothesis, nine canine models were implanted with pacing electrodes in both the atrium and ventricle. After a forty- minute stabilization period, baseline data were obtained during atrial pacing. Cardiac memory was induced in five canine models through a two-hour period of ventricular pacing followed immediately by atrial pacing. The remaining canine models served as controls, undergoing atrial pacing for two hours. High- density mapper (HDM) was used to determine mechanical function in a region centered approximately 1 cm away from the pacing electrode. No differences in global function (tau, developed pressure, dP/dtmax, dP/dtmin) were found after two hours of ventricular pacing upon return to normal activation pathways. There was a significant decrease in regional stroke work in an area close to the electrode between baseline (5.7 ± 2.6 %), during ventricular pacing (-3.8 ± 0.9 %)(p<0.05) and after two hours of ventricular pacing upon return to normal activation pathways (2.4 ± 1.6 %)(p<0.05). Further, systolic area contraction was also significantly different between baseline (5.0 ± 6.6 %) and after two hours of ventricular pacing upon return to normal activation pathways (0.2 ± 7.4 %)(p<0.05). Diastolic twist and diastolic twist rates showed no significant differences. Finally, contractile principal strain increased by inducing cardiac memory (-2.6 ± 0.3 %) as compared to baseline (-1.1 ± 0.5 %)(p<0.05). These findings suggest there is a mechanical correlation to electrical cardiac memory.

"It is well known that singularities occur when solving elliptic value problems with non-convex domains or when some part of the data or the coefficients of the PDE are not smooth. Such problems and correspondent singularities often arise in practice, for instance, in fracture mechanics, in the material science with heterogeneities, or when dealing with mixed boundary conditions. A great deal is known about the nature of the singularities, which arise in some of these problems. In this thesis, we consider the scalar transmission problems with straight interfaces and with cross points across coefficients and possibly on a non-convex region ($L$-shaped domain). It is known that only $H^{1+au}$ ($0 < au< 1$) regularity on the solution is obtained and therefore the use of finite element method with the piecewise linear continuous function space does not give optimal accuracy. In this thesis, we introduce a new algorithm which are second order accurate on the (weighted) $L_2$, first order accurate on the (weighted) $H_1$ norm and second order accurate for the Stress Intensive Factor (SIF). The new methods take advantage of Mortar techniques. The main feature of the proposed algorithms is that we use primal singular functions {it without} cutting-off functions. The old algorithms use cutting-off functions as a tool of satisfying boundary conditions. In algorithms proposed in this thesis, use instead Mortar finite element technique to match the boundary and interfaces conditions. In this thesis, we also consider non-matching meshes sizes for different coefficients. We note that a new Mortar Lagrange multiplier is required in order to obtain optimal consistence errors for transmission problems. The proposed algorithms are very appealing over other methods because they are very accurate, do not require complicated numerical quadratures or interpolations, it is simple to design PCGs, and it can be generalized to other PDEs and to higher order methods."

Molecular networks are commonly used to explore cellular organisation and disease mechanisms. Function is studied using molecular interaction networks, such as protein-protein networks. Although much biological insight has been gained using these models of molecular function, they are hindered by their reliance on available experimental data and an inability to capture the complexity of biological processes. Functional modules can be identified based on molecular network topology, making it essential that the edges accurately depict molecular interactions. However, these networks struggle to depict the temporal nature of interactions, giving the impression that all interactions are constant. This misrepresentation can result in functionally heterogeneous clusters. The notoriously inaccurate nature of experimental protein interaction data, along with variable conformity among network clusters and functional modules further impedes functional module extraction. Representation of genes by single nodes artificially merges the functions of pleiotropic genes, distorting the arrangement of function within molecular networks. This thesis therefore explores a more suitable model for representing function. Pathways are composed of sets of proteins that are known to interact within a particular cellular context, corresponding to a discernible biological function. Their representation of context dependent cellular activity makes them ideal for use as nodes within a new pathway level model. Using combinatorial algorithms a reduced redundancy pathway set was produced to represent global cellular systems. Enrichment analysis provides reliable functional annotations for each pathway node, attributing independent functions to pleiotropic genes. Edges are based on functional semantic similarity, generating a network representation of functional organisation. Both yeast and human biological systems are presented as functionally connected pathway networks. Pathway annotation and experimentation with semantic similarity measures provides insight into the cross-talk between biological processes. Pathway functional modules elucidate the intracellular implementation of processes. Disease modules highlight the effects of functional perturbations and disease mechanisms. The pathway model provides a complementary, high-level functional model that begins to bridge the gap between molecular data and phenotype. The utilisation of pathway data provides a large, well-validated data source, avoiding the inaccuracies inherent with molecular data. Pathway models better represent components of biological complexity such as pleiotropy and linear implementation of functions.

Executive Function (EF) comprises general purpose control processes that regulate thoughts and behaviours. Underlying core skills have been identified, including Shift: the ability to move between mental states, operations, or tasks. Research implicates EF (and Shift specifically) in academic achievement and broader life functioning throughout the life span. Most attempts to develop EF skills directly have focused on memory aspects and/or younger children. Reported benefits are controversial and perhaps limited. This research tackles a particular gap: intervention with adolescent core EF skills, with a focus on Shift, in a typical educational setting. All participant sampling was by convenience. Two experts in EF and three local stakeholders guided intervention development. 22 mainstream Year 8 students (one tutor group) trialled the resulting intervention prototype. A teaching assistant facilitated the implementation, with the form tutor present to occasionally assist. Being an exploratory evaluation, this research used mixed methods with an emphasis on qualitative data. Semi-structured group interviews with experts and a stakeholder focus group were used during the development phase. Standardised baseline and retest data were collected up to three weeks before and four weeks after the implementation phase respectively: a half term's trial during morning form-time. This was complemented by semi-structured feedback interviews with the participating adults and eight students. Transcripts were analysed with Thematic Analysis and the researcher's diary with Content Analysis. The quantitative data were summarised with descriptive statistics and additionally analysed with nonparametric inferential statistics. The study extends available data describing the near benefits of EF intervention. It explores the likely utility of EF intervention both theoretically and from an implementation perspective.

The study reported in this dissertation aimed at exploring relations between parental factors - parenting and maternal executive function (EF) - and preschool children's EF in the South Korean context (the Republic of Korea; Korea hereafter). Specifically, it investigated the replication in the Korean context of existing findings in Western cultures on the link between parenting and child EF. In addition, the present study explored parental aspects that have rarely been linked to child EF: 1) the relation of parental verbal input to child EF, 2) simultaneous relations of parenting and maternal EF to child EF, and 3) mediating roles played by parenting in the maternal EF-child EF link. Ten kindergartens located in different districts (middle- to upper-middle class households) in Seoul, Korea hosted the present study, and data were collected from a total of 92 mother-child dyads who volunteered to take part. The children were aged between 3 and 5 years, with 97 per cent of them being 4 years old, and they were reported not to have experienced developmental issues. The mothers were biological parents of child participants. Both the mothers and children performed on age-appropriate EF tasks. Three types of parenting dimensions were focused on in two contexts of mother-child interactions: maternal contingency and intrusiveness in a problem-solving context and maternal verbal input during a mother-child reminiscing conversation. Maternal verbal input was operationalized to consist of four constructs: maternal elaboration, semantic connection (maternal utterances that are semantically connected with the child's utterances), maternal mental-state references, and connected mental-state references (maternal mental-state references that are semantically connected with the child's utterances). As such, a total of 14 maternal traits during the two mother-child interactions were examined for their relations to the development of child EF. Mother-child interactions were videotaped for later analysis. As a result, 184 five-minute video clips were obtained and analysed by adopting a quantitative approach. Results showed that the positive relation between maternal contingency and child EF was successfully replicated in the Korean context. In addition, maternal connected mental-state references, particularly emotion references, were found as a significant factor explaining child EF, above and beyond three covariates of child EF (child age, child verbal ability and maternal educational attainment). However, maternal intrusiveness was found not to be significantly related to child EF in the Korean context. Next, the analysis of the simultaneous relations of maternal factors to child EF showed that maternal contingency accounted for unique variance in child EF more than any other parenting variables involved in the present study. In addition to maternal contingency, maternal EF (i.e., maternal shifting as measured by the Wisconsin Card Sorting Task) and maternal connected mental-state references were found to significantly account for unique variance in child EF. Finally, it was found that the maternal EF-child EF link was not explained by parenting behaviours explored in the present study. Instead, maternal contingency was found to mediate the link between child verbal ability and child EF and the link between maternal educational attainment and child EF. While the above mentioned results were the main findings of the present study, the difference in the results should be addressed between when using the whole sample (N=92 dyads) and only 4-year-olds (N=89 dyads). Child's age was found to account for less unique variance in child EF when using only 4-year-olds. In addition, the significant link between maternal EF and child EF when using the data from the whole sample became insignificant when using the data from only 4-year-olds. These findings are discussed in terms of universal or culture-specific links between maternal EF, parenting behaviours and child EF, adding to the literature by presenting the first empirical evidence on this research field in a non-Western context.

Age is associated with alterations in sensation and cognition, but little is known of how sensory-cognitive interactions change over time, especially during late middle age. This project examined the change in relations between sensation and cognition and their consistency with established models of neurocognitive aging. Three studies examined associations between visual contrast sensitivity (CS), auditory pure tone acuity (PTA), and cognition among male twins from the Vietnam Era Twin Study of Aging (VETSA), who were assessed twice (VETSA 1, x̅𝑎𝑔𝑒 = 56, n =1,237, VETSA 2, x̅𝑎𝑔𝑒 = 62, n =1,016). Study 1 examined sensory relations, with the hypothesis of more and stronger correlations between CS and PTA at VETSA 2 than at VETSA 1 and a larger genetic correlation at VETSA 2 than at VETSA 1. Heritability at VETSA 1 and VETSA 2 was significant for multiple CS and PTA frequencies, and heritability increased with age. At VETSA 2, there were more shared genes between CS and PTA than at VETSA 1. Studies 2 and 3 examined sensory-cognitive associations. The Study 2 hypotheses of more and stronger associations between CS and cognition at VETSA 2 than VETSA 1 were not supported. Performance in five of nine cognitive domains was correlated with low frequency CS at VETSA 1. Four of these five correlations were significant at VETSA 2. The Study 3 hypotheses of increasing associations between PTA and cognition also were not supported. Low frequency PTA correlated with performance in six cognitive domains at VETSA 1 and in four at VETSA 2. High frequency PTA and episodic memory significantly interacted with age. Neither CS nor PTA was associated with cognition dependent on the sensory modality in which the cognitive tests were presented. The hypothesis that correlations between CS and PTA would increase with age was partially supported, and the hypothesis that correlations between sensory function (vision, audition) and cognition would increase with age was not supported, in both cases because these correlations were independent of age. The results did not follow a single established model of cognitive aging, supporting a model-agnostic approach to future aging research.

The purpose of this paper is to examine the important topological properties of the function spaces BC(X,Y) and C(X,Y). Emphasis is given to the relationship between the metrizability of X and the separability of these function spaces. The paper is divided into three major parts: the preliminary definitions and theorems; the relationship between the topological properties of X and BC (X ,Y), for compact X; and the extension of the results of Part II for X not compact and for the case when we have C(X, Y).

In this paper we deduce a prime number theorem for the L-function L(s; AIE=Q() AIF=Q(0)) where and 0 are automorphic cuspidal representations of GLn=E and GLm=F, respectively, with E and F solvable algebraic number elds with a Galois invariance assumption on the representations. Here AIF=Q denotes the automorphic induction functor. We then use the proof of the prime number theorem to compute the n-level correlation function of a product of L-functions dened over cyclic algebraic number elds of prime degree.

The computation of a piecewise smooth function that approximates a finite set of data points may be decomposed into two decoupled tasks: first, the computation of the locally smooth models, and hence, the segmentation of the data into classes that consist on the sets of points best approximated by each model, and second, the computation of the normalized discriminant functions for each induced class. The approximating function may then be computed as the optimal estimator with respect to this measure field. We give an efficient procedure for effecting both computations, and for the determination of the optimal number of components.