The synthesis of sterically hindered olefins

Imperial Users onl

The effect of energy input on the aggregation rate in an oscillating multi-grid reactor

Includes bibliographical references.Aggregation is a size enlargement mechanism which can be either desirable or inconvenient depending on the process involved. It involves the coming together or collision of two or more particles to form a larger single particle. It is a mechanism which is poorly understood and much research is still required before the intricacies of the process are fully grasped. Although it is known that aggregation is influenced by energy input (amongst other factors), the relationship between the two has previously been measured in anisotropic turbulent environments. Thus although aggregation is a function of local energy input, it has yet to be measured in environments where the local energy dissipation is well understood, or else it has been studied in low Reynolds number environments. This thesis aims to address this deficiency by studying the effect of local energy input on the aggregation rate in a well characterised environment of isotropic and homogenous turbulence

Clustering functional data using forward search based on functional spatial ranks with medical applications

Cluster analysis of functional data is finding increasing application in the field of medical research and statistics. Here we introduce a functional version of the forward search methodology for the purpose of functional data clustering. The proposed forward search algorithm is based on the functional spatial ranks and is a data-driven non-parametric method. It does not require any preprocessing functional data steps, nor does it require any dimension reduction before clustering. The Forward Search Based on Functional Spatial Rank (FSFSR) algorithm identifies the number of clusters in the curves and provides the basis for the accurate assignment of each curve to its cluster. We apply it to three simulated datasets and two real medical datasets, and compare it with six other standard methods. Based on both simulated and real data, the FSFSR algorithm identifies the correct number of clusters. Furthermore, when compared with six standard methods used for clustering and classification, it records the lowest misclassification rate. We conclude that the FSFSR algorithm has the potential to cluster and classify functional data

Listening to parents of children with autistic spectrum disorder : using interpretative and critical research approaches to consider 'how parent experience of bringing up a child with autism can inform professional practice and provision'.

The main aim of the study was to consider how parents' experiences of bringing up a child with autism might inform professional practice and provision. The enquiry investigated how mothers made sense of their experiences and the effects of bringing up their child, including their coping mechanisms and the arising key messages for practice. The study was based in a LA context and was carried out by a practising Educational Psychologist (EP). This research practitioner orientation required critical or action research elements to merge with interpretative method. Thus, initial contact was made with autism parent groups to ground the study in a local context and to develop research and interview questions. Critical action planning resulted from concerns arising from these groups. Semi-structured interviews were carried out with six mothers whose circumstances in bringing up their child had been particularly challenging. Their children attended both mainstream and special autism provision in the primary and secondary school sectors. The themes emerging from the powerful joint interpretative account of the mothers highlighted a deconstruction and reconstruction of self and expectations with unfulfilled wishes and control as key themes. Life impacts involved the child as central focus, an all-pervasive constant battle with self and others, including family, professionals and provision with associated child management issues being present. These key themes impacted on professional practice; and provision so that the importance of informed professional awareness, truly listening professionals, accepting school identity and service trust were highlighted. Professionals and parents should develop an understanding and acceptance of the child and each other, which still enables challenge and change. The position of fathers in family support needs further research and careful professional consideration. Professionals, including EPs, need to address the way they listen to parents. Some recommendations for all agencies and parents are provided which should lead us to a deeper understanding of humanity

BDNF and JNK-signalling modulate cortical interneuron and perineuronal net development: implications for schizophrenia-linked 16p11.2 duplication syndrome

Schizophrenia is a neurodevelopmental disorder caused by the interaction of genetic and environmental risk factors. One of the strongest genetic risk variants is duplication of chr.16p11.2. Schizophrenia is characterised by cortical GABAergic interneuron dysfunction, and disruption to surrounding extracellular matrix structures, perineuronal nets (PNNs). Developmental maturation of GABAergic interneurons, and also the resulting closure of the critical period of cortical plasticity, is regulated by brain derived neurotrophic factor (BDNF), although the mechanisms involved are unknown. Here, we show that BDNF promotes GABAergic interneuron and PNN maturation through JNK signalling. In mice reproducing the 16p11.2 duplication, where the JNK upstream activator Taok2 is overexpressed, we find that JNK is overactive and there are developmental abnormalities in PNNs which persist into adulthood. Prefrontal cortex parvalbumin expression is reduced while PNN intensity is increased. Additionally, we report a unique role for TAOK2 signalling in the regulation of parvalbumin interneurons. Our work implicates TAOK2-JNK signalling in cortical interneuron and PNN development, and in the responses to BDNF. It also demonstrates that over-activation of this pathway in conditions associated with schizophrenia risk causes long-lasting disruption in cortical interneurons