Assessment of left ventricular (LV) function is one of the most common requests made to cardiac imaging services. This demand stems from a large body of evidence that shows abnormal LV systolic and, more recently, diastolic function has important prognostic and treatment related implications for patients with a wide range of cardiovascular diseases. The vast majority of information supporting the use of conventional measures of LV function, such as ejection fraction, originates from population studies and large clinical trials. However, the application of these measurements to individual patients is far less defined, especially when used for serial evaluation. Central to these concerns is the relative paucity of data surrounding the test-retest reliability of conventional measures in clinical settings. Newer measures of LV function have been developed over recent years, with several techniques becoming widely used in clinical practice (i.e. tissue Doppler imaging) and others remaining largely research tools (i.e. 3D echocardiography, tissue strain/strain rate). Possible benefits of new technologies include improved identification and early detection of myocardial disease, improved reliability for monitoring progression of disease, and the development of novel methods to assess response to therapy. Despite this potential, the application and clinical utility of these techniques above and beyond more conventional measures remains in many cases to be adequately characterized. This thesis addresses several of these issues: from variability of novel and conventional measures of LV function in clinical practice, to new applications of novel functional measures in clinical settings.

<p>The cardiac wall has complex three-dimensional fiber structures and mechanical properties that enable the heart to efficiently pump the blood through the body. By studying the myocardial strains induced during diastole, information about the pumping performance of the heart and what mechanisms that are responsible for this effective blood filling, can be achieved. Two different computation methods for myocardial strain, both based on data acquired from marker technique, were compared using a theoretical cylinder model. The non-homogeneous polynomial fitting method yielded higher accuracy than a homogeneous tetrahedron method, and was further used to investigate cardiac and fiber strains at different wall depths and myocardial regions in normal and ischemic ovine hearts. Large spatial and regional variations were found, as well as alterations, conveyed by ischemic conditions, of fiber mechanisms responsible for the circumferential expansion and wall thinning during diastole.</p>

<p>Kvantifisering av hjertets muskelfunksjon med tøyning og tøyningshastighet målt med ultralyd for vurdering av koronar sykdom.</p><p>Automatisert metode versus manuell ved akutt hjerteinfarkt og ultralyd stress test.</p><p>Vanligvis måles hjertets muskelfunksjon med ultralyd, en mye brukt metode for å diagnostisere hjertesykdommer. Vurderingen av muskelfunksjonen baserer seg i dag på en subjektiv visuell gradering av bevegelsen av hjertemuskelen, og dette krever erfaring. En ny automatisert diagnostisk ultralydsmetode basert på måling av hastigheten i hjertemuskelen gir et kvantitativt mål på muskelens tøyning og sammentrekning. Den nye metoden gir ny og mer detaljert informasjon om hjertets funksjon og om pasientens prognose enn vanlig ultralydsvurdering.</p><p>Den nye metoden er mer presis ved oppfølgning etter hjerteinfarkt. Et hjerteinfarkt gir nedsatt bevegelse av muskelen og måles med den nye metoden som nedsatt hastighet som muskelen forkortes med. Små forandringer i den skadde hjertemuskelen, ikke alltid synlige for øyet, kan mer nøyaktig følges over tid med den nye metoden. Utbredelsen av hjerteinfarktet kan også vurderes mer nøyaktig.</p><p>Det samme gjelder når angina vurderes under belastning. Når en pasient ikke kan sykle eller gå på tredemølle brukes en medisinsk belastningstest. Ved å belaste hjertet med et medikament som øker hjertemuskelens arbeid samtidig med en ultralydundersøkelse, kan vi oppdage redusert blodforsyningsreserve i hjertet. Stresstesten hjelper til med å vurdere om en trang blodåre bør åpnes etter et hjerteinfarkt, og til å vurdere pasienters risiko for hjertekomplikasjoner før en større operasjon. Den nye metoden gir i tillegg mer informasjon om den langsiktige prognosen sammenlignet med den gamle metoden. Vi har funnet at den nye ultralydsmetoden er mer presis (gir større diagnostisk treffsikkerhet i diagnostikk av koronarsykdom) sammenlignet med den gamle.</p><p>Måling av sammentrekningshastigheter i hjertemuskelen ble utviklet og testet på Institutt for sirkulasjon og bildediagnostikk ved NTNU av Andreas Heimdal og Asbjørn Støylen i 1998. Metoden trengte teknisk videreutvikling og testing i et større pasientmateriale. Metoden har ikke fått stor utbredelse på sykehusene pga støyfylte kurver og tidskrevende analyser, men med denne automatiserte metoden blir brukervennligheten større som muliggjør klinisk bruk.</p> / Paper I and II preprinted with kind permission of Elsevier, sciencedirect.com

<p>Bakgrund: Demenssjukdomar blir allt vanligare och en stigande ålder ökar risken för att få denna sjukdom. Att få en demenssjukdom innebär att språket, tankeförmågan liksom de kognitiva och intellektuella funktionerna är nedsatta. Målet i omvårdnaden är att vårdtagaren skall ha ett gott liv trots sjukdom. Vårdpersonalen upplever att de behöver mer kunskap för att ge personer med demenssjukdom en god omvårdnad. Syfte: Syftet är att beskriva hur vårdpersonalen upplever omvårdnaden av personer med demenssjukdom. Metod: En litteraturöversikt som grundade sig på tolv kvalitativa och kvantitativa vetenskapliga artiklar som söktes fram via elektroniska databaser och som därefter granskades och analyserades. Resultat: Resultatet visade att kunskap och utbildning saknades, att det var svårt att kommunicera med vårdtagare med demenssjukdom samt att vårdpersonalen gav vårdtagarna lugnande läkemedel för att hinna med sitt arbete. Diskussion: Att ha kunskap och utbildning om demenssjukdomar och hur omvårdnaden påverkar vårdtagaren kan leda till att kommunikationen förbättras och en positiv atmosfär erhålls med mycket humor och skratt mellan vårdtagare och vårdpersonal. Dessutom kan vårdtagarnas läkemedelsintag av lugnande mediciner minskas. En slutsats av denna litteraturstudie är att utbildning och kunskap är en viktig del i omvårdnaden av personer med demenssjukdom och att arbetsgivaren bör tillhandahålla kontinuerlig utbildning till vårdpersonalen.</p> / <p>Background: Dementia is becoming more common and the risk of developing this disease increases with age. Dementia impairs the language, thinking abilities as well asmore general cognitive and intellectual functions. Nursing aims to make life as good as possible despite the effects of the disease. Nurses have felt that they need more skills inorder to ensure that dementia patients get proper nursing. Purpose: The report describes how nurses perceive the care given to dementia patients. Method: The report is based on a literature review of twelve qualitative and quantitative scientific papers. The papers were selected through searches in electronicdatabases, and they are examined and analyzed. Results: Findings indicated that knowledge and training are missing, difficult to communicate with dementia patients. Nurses giving the patients sedatives so they couldwork in tranquility. Discussion: Knowledge and training in the dementia disease and in how the care influence the dementia patient can lead to several positive aspects: the communication between the nurses and the patient can improve, the atmosphere can become more beneficial with increased warmth and laughter, and the dosage of sedatives can be decreased. We conclude that knowledge and training are crucial in the care of dementia patients and that the employer should continuously provide training opportunities to the nurses.</p>

Graded InGaN buffers were employed to relax the strain arising from the lattice and thermal mismatch in GaN/InGaN epilayers grown on sapphire. An enhanced strain relaxation was observed in GaN grown on a stack of five InGaN layers, each 200 nm thick with the In content increased in each layer, and with an intermediate thin GaN layer, 10 nm thick inserted between the InGaN layers, as compared to the conventional two-step growth of GaN epilayer on sapphire. The function of the intermediate layer is to progressively relax the strain and to annihilate the dislocations that build up in the InGaN layer. If the InGaN layers were graded too rapidly, more dislocations will be generated. This increases the probability of the dislocations getting entangled and thereby impeding the motion of the dislocations to relax the strain in the InGaN layer. The optimum growth conditions of the intermediate layer play a major role in promoting the suppression and filling of the V-pits in the GaN cap layer, and were empirically found to be a thin 10 nm GaN grown at 750 0°C and annealed at 1000 0°C. / Singapore-MIT Alliance (SMA)

Plastic relaxation was observed in InᵡGa₁₋ᵡN/GaN epilayers grown on c-plane sapphire substrates. The relaxation obeys the universal hyperbolic relation between the strain and the reciprocal of the layer thickness. Plastic relaxation in this material system reveals that there is no discontinuous relaxation at critical thickness and once a layer starts to relieve, it follows the same strain-thickness dependence, unconstrained by the original misfit until the material system work hardens. From x-ray diffraction calibration, the in-plane and normal relaxation constants KP0 and KN0 for the InᵡGa₁₋ᵡN/GaN grown on sapphire were found to be −0.98 ± 0.03 and +0.51 ± 0.03 nm, respectively. / Singapore-MIT Alliance (SMA)

Graded InGaN buffers are employed to relax the strain arising from the lattice and thermal mismatches between GaN/InGaN epilayers grown on sapphire. The formation of V-pits in linearly graded InGaN/GaN bulk epilayers is illustrated. The V-pits were sampled using Atomic Force Microscopy and Scanning Electron Microscopy to examine their variation from the theoretical geometry shape. We discovered that the size of the V-pit opening in linearly graded InGaN, with and without GaN cap layer, has a Gaussian distribution. As such, we deduce that the V-pits are produced at different rates, as the growth of the InGaN layer progresses. In Stage I, the V-pits form at a slow rate at the beginning and then accelerate in Stage II when a critical thickness is reached before decelerating in Stage III after arriving at a mean size. It is possible to fill the V-pits by growing a GaN cap layer. It turns out that the filling of the V-pits is more effective at lower growth temperature of the GaN cap layer and the size of the V-pits opening, which is continued in to GaN cap layer, is not dependent on the GaN cap layer thickness. Furthermore, graded InGaN/GaN layers display better strain relaxation as compared to conventionally grown bulk GaN. By employing a specially design configuration, the V-pits can be eliminated from the InGaN epilayer. / Singapore-MIT Alliance (SMA)

We present an implicit a-posteriori finite element procedure to compute bounds for functional outputs of finite element solutions in large strain elasticity. The method proposed relies on the existence of a potential energy functional whose local minima, over a space of suitably chosen continuous functions, corresponds to the problem solution. The output of interest is cast as a constrained minimization problem over an enlarged discontinuous finite element space. A Lagrangian is formed were the multipliers are an adjoint solution, which enforces equilibrium, and hybrid fluxes, which constrain the solution to be continuous. By computing approximate values for the multipliers on a coarse mesh, strict upper and lower bounds for the output of interest on a suitably refined mesh, are obtained. This requires a minimization over a discontinuous space, which can be carried out locally at low cost. The computed bounds are uniformly valid regardless of the size of the underlying coarse discretization. The method is demonstrated with two applications involving large strain plane stress incompressible neo-hookean hyperelasticity. / Singapore-MIT Alliance (SMA)

Thesis (Ph.D. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007.

Thesis (M.A. (Industrial Psychology))--North-West University, Vaal Triangle Campus, 2005.