Modelling the evolution of cerebral aneurysms: biomechanics, mechanobiology and multiscale modelling

Intracranial aneurysms (IAs) are abnormal dilatations of the cerebral vasculature. Computational modelling may shed light on the aetiology of the disease and lead to improved criteria to assist diagnostic decisions. We briefly review models of aneurysm evolution to date and present a novel fluid-solid-growth (FSG) framework for patient-specific modelling of IA evolution. We illustrate its application to 4 clinical cases depicting an IA. The section of arterial geometry containing the IA is removed and replaced with a cylindrical section: this represents an idealised section of healthy artery upon which IA evolution is simulated. The utilisation of patient-specific geometries enables G&R to be explicitly linked to physiologically realistic spatial distributions and magnitudes of haemodynamic stimuli. In this study, we investigate the hypothesis that elastin degradation is driven by locally low wall shear stress (WSS). In 3 out of 4 cases, the evolved model IA geometry is qualitatively similar to the corresponding in vivo IA geometry. This suggests some tentative support for the hypothesis that low WSS plays a role in the mechanobiology of IA evolution

Modelling volumetric growth in a thick walled fibre reinforced artery

A novel framework for simulating growth and remodelling (G&R) of a fibre-reinforced artery, including volumetric adaption, is proposed. We show how to implement this model into a finite element framework and propose and examine two underlying assumptions for modelling growth, namely constant individual density (CID) or adaptive individual density (AID). Moreover, we formulate a novel approach which utilises a combination of both AID and CID to simulate volumetric G&R for a tissue composed of several different constituents. We consider a special case of the G&R of an artery subjected to prescribed elastin degradation and we theorise on the assumptions and suitability of CID, AID and the mixed approach for modelling arterial biology. For simulating the volumetric changes that occur during aneurysm enlargement, we observe that it is advantageous to describe the growth of collagen using CID whilst it is preferable to model the atrophy of elastin using AID

Cell adhesion and growth factor regulation of Akt

Akt is a protein kinase that contains a C-terminal pleckstrin homology (PH) domain and an N-terminal kinase domain. The activity of Akt is regulated by PI3-kinases that generate 3 phosphoinositides. Akt activation requires the binding of 3 phosphoinositides to the pleckstrin homology (PH) domain and phosphorylation at residues Thr308 and Ser473. Phosphospecific antibodies that recognise the phosphorylated sites and green fluorescent protein (GFP) fusions with mutated or truncated forms of Akt were used to follow the activation of Akt. Confocal microscopy showed that membrane translocation is required for Akt phosphorylation and is dependent on the PH domain but not kinase activity. A GFP fusion with the PH domain of Akt, termed GFP-AH, was assessed and used as a probe for sites of PI3-kinase activity in cells. GFP- AH was used to locate 3 phosphoinositides in epithelial cells that were plated on collagen to investigate extracellular matrix induced cell survival. GFP-AH localised to sites of cell-cell and cell-matrix contact, distinct from focal adhesions. This suggests that the attachment induced, PI3-kinase mediated, survival signal in epithelial cells is generated not only by cell-matrix but also by cell-cell contact. PI3-kinase activity was monitored during the disruption and formation of cell-cell junctions. Disruption of the junctions by calcium removal decreased PI3-kinase activity, whereas the formation of junctions preceded PI3-kinase activity. Akt became phosphorylated 4 h after junction formation was initiated and correlated with the tyrosine phosphorylation of the cell-cell junctional proteins y-catenin and p120 catenin. As p120 catenin is a substrate of activated Src and Src family kinase inhibitors reduced the cell-cell adhesion induced phosphorylation of Akt, this suggests a role for Src family kinases in the regulation of cell-cell adhesion induced PI3-kinase activity

Acetonitrile­bis­(2,9-dimethyl-1,10-phen­an­throline)copper(II) bis­(tetra­fluorido­borate)

The title compound, [Cu(CH3CN)(C12H12N2)2](BF4)2, crystallizes with two copper-containing cations and four tetra­fluoro­borate anions in the asymmetric unit. The structure represents a second crystal form of the salt, the first being an acetonitrile solvate [Watton (2009 ▶). Acta Cryst. E65, m585–m586]. The complex cation has a distorted trigonal-bipyramidal geometry, whereas the previous structure exhibits a distorted square-pyramidal geometry. One of the four BF4 − counter-ions is disordered, with a refined site occupancy of 0.8615 (17):0.1385 (17)

Improving the design of golf course communities as wildlife habitats

Golf course community developments present a unique opportunity to preserve and create wildlife habitat. Golf course management and development industries have become particularly cognizant of their environmental responsibilities in recent times and are responsive to new research. The specific focus of this thesis research is to provide guidance and encouragement for landscape architects designing wildlife habitat areas within golf course community developments. Specifically, I analyze the size, shape, and orientation of a selected number of wildlife habitat areas within the unique context of golf course community land usage. My hypothesis is that the spatial characteristics of a habitat area influence the resulting wildlife habitation. Therefore, designers can influence the habitation of designated wildlife habitat through design decisions. This thesis produces a set of guidelines for the design of wildlife habitat areas within golf course communities in addition to substantiating the importance of incorporating wildlife habitat within large-scale developments, especially golf course communities

A MULTIDISCIPLINARY ASSESSMENT OF HYALOCLASTITE DEPOSITS IN PETROLEUM SYSTEMS USING FIELD STUDIES, DRILL CORE, BOREHOLE IMAGE AND WIRE-LINE LOG DATASETS

This thesis aims to document hyaloclastite deposits in different depositional environments from field outcrops in Iceland to characterise lithofacies heterogeneity enabling comparison to subsurface datasets. Field hyaloclastite datasets from Stóri-Núpur (subaerial-marine transition) and Hjörleifshöfði (an emergent Surtseyan volcano) are used to support the interpretation of hyaloclastite and associated volcanic deposits in core, borehole image logs and wire-line log datasets from Hawaii (Hawaiian Scientific Drilling Project II – HSDP II borehole) and the Faroe-Shetland Basin (LOPRA1/1A well and the Rosebank field). This study provides additional constraints on lava delta formation in predominantly basaltic systems where hyaloclastite depositional profiles reflect localised extrusion pathways and syn-sediment reworking which control 3D lithofacies architecture. Furthermore this thesis documents the evolution of Hjörleifshöfði using field mapping and major/trace element geochemistry. Hjörleifshöfði can split into five phases of deposition charting the submarine to emergent building of the volcano, unique as it also records a phase of silicic volcanism (Sólheimar Ignimbrite) which dates late stage volcanism to no earlier than 12,383 C14 years BP. Petrophysical and petrographic observations suggest hyaloclastite deposits are unique in terms of their velocity/density and P and S wave relationships due to palagonite formation, basalt clast support, phenocryst and zeolite component amongst others which impacts on depth conversion and the calculation of reflection coefficients. Wire-line log response gamma-ray (GR), resistivity (RES), P-wave sonic velocity (Vp) is also closely linked to the dominant interstitial secondary minerals and phenocryst components of sideromelane glass. Borehole image log analysis of mixed volcanic and volcaniclastic rocks allows the accurate characterisation of distinct internal lava flow features, contact relationships and joint networks enabling better characterisation of volcanic sequences in the subsurface via careful comparison with field examples. Field, core and wire-line log data is combined to form a multidisciplinary assessment of hyaloclastite deposits in the subsurface suggesting that the complexity and scaling issues in hyaloclastite rocks is generally overlooked which may impact on future petroleum exploration in volcanic basins

Acetonitrile­bis­(2-methyl-1,10-phenanthroline)copper(II) tetra­fluoridoborate

In the title compound, [Cu(CH3CN)(C13H10N2)2](BF4)2, the fivefold-coordinate CuII atom is located on a twofold rotation axis, imposing twofold symmetry to the complete cation. The structure exhibits disorder of the anion, which was successfully refined using a two-site model with 0.810 (3):0.190 (3) occupancy. The methyl group of the acetonitrile ligand is likewise disordered, here about the twofold rotation axis in a 1:1 ratio

Infrastructures et réseaux dans le développement économique de la Hongrie

Infrastructures and networks in Hungary's economic development. Technical networks and service infrastructures represent a major obstacle in the development of Hungary, according to the author. Studies have revealed lack of equipment and functional incapacity. This situation is partly the result of a long-term crisis. But it is also the reflection of the structure of centralized authority, set up after WWII, which could neither imagine nor maintain independent networks. The recent political changes, as well as expansion towards a market economy, has raised new, contradictory questions: the role of the State, methods for establishing real costs, the respective place of self-regulation and public intervention. The author feels that the solution is not to restructure the country according to the models imported from the West; rather, the public authorities still have a role to play in the control and regulation of these sectors. Résumé Les réseaux techniques et les infrastructures de services représentent un blocage majeur du développement de la Hongrie, selon l'auteur. Des enquêtes font apparaître des retards d'équipement et des dysfonctionnements. Cette situation tient pour une partie à l'héritage de longue période. C'est aussi le reflet de la structure de pouvoir centralisée mise en place après la seconde guerre mondiale qui ne peut concevoir ou maintenir des réseaux indépendants. Les changements politiques comme l'ouverture économique en direction du marché posent de nouvelles questions contradictoires: rôle de l'Etat, méthodes de mesure des coûts, places respectives de l'autorégulation et de l'intervention publique. Plutôt que de considérer que tout doit être reconstruit selon un modèle importé de l'ouest, l'auteur pense que la puissance publique a encore sa place dans la régulation de ces secteurs

Leadership identity:using artefacts (and storytelling) to discover new insights.

Artefacts are used in management education to reflect upon the experiences of participants. Story-telling has a leadership influence that is long recognised in the leadership literature. However, artefacts and story-telling have not been used concurrently in leadership and management development programmes. We used artefacts combined with story-telling to help participants understand their leadership identity. Louisa’s story and artefact are the basis of this research. We found that the story-teller gained a clearer image of their leadership identity; and engaged in more effective leadership. We also found that the audience members gained a clearer notion of their leadership identity. Implications for organizational leadership and management development programmes are posited

Ecological studies on:(a) the use of colonisation samplers in relation to biological surveillance of river water quality (b) the requirements of freshwater gastropoda

Some of the factors affecting colonisation of a colonisation sampler, the Standard Aufwuchs Unit (S. Auf. U.) were investigated, namely immersion period, whether anchored on the bottom or suspended, and the influence of riffles. It was concluded that a four-week immersion period was best. S. Auf. U. anchored on the bottom collected both more taxa and individuals than suspended ones. Fewer taxa but more individuals colonised S. Auf. U. in the potamon zone compared to the rhithron zone with a consequent reduction in the values of pollution indexes and diversity. It was concluded that a completely different scoring system was necessary for lowland rivers. Macroinvertebrates colonising S. Auf. U. in simulated streams, lowland rivers and the R. Churnet reflected water quality. A variety of pollution and diversity indexes were applied to results from lowland river sites. Instead of these, it was recommended that an abbreviated species - relative abundance list be used to summarise biological data for use in lowland river surveillance. An intensive study of gastropod populations was made in simulated streams. Lynnaea peregra increased in abundance whereas Potamopyrgas jenkinsi decreased with increasing sewage effluent concentration. No clear-cut differences in reproduction were observed. The presence/absence of eight gastropod taxa was compared with concentrations of various pollutants in lowland rivers. On the basis of all field work it appeared that ammonia, nitrite, copper and zinc were the toxicants most likely to be detrimental to gastropods and that P. jenkinsi and Theodoxus fluviatilis were the least tolerant taxa. 96h acute toxicity tests of P. jenkinsi using ammonia and copper were carried out in a flow-through system after a variety of static range finding tests. P. jenkinsi was intolerant to both toxicants compared to reports on other taxa and the results suggested that these toxicants would affect distribution of this species in the field