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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
841

Loading Rate Effects and Sulphate Resistance of Fibre Reinforced Cement-based Foams

Mamun, Muhammad 11 1900 (has links)
This study describes the strength, toughness and strain-rate sensitivity of fibre-reinforced cement-based foams subjected to variable loading rates. Drop-weight impact tests were conducted on beams with cast density between 475 - 1200 kg/cu.m. The study shows that under quasi-static loading, the compressive strength, elastic modulus and the modulus of rupture of plain mixes scale with the square of the relative density. On the other hand, the flexural toughness factor scaled linearly with it. Fibres were seen to increase the flexural strength at all rates of loading, regardless of cast density. Further, cement based foams were seen to be strain-rate sensitive. The resistance of cement-based foams to sulphate exposure was also investigated. Heavier cement-based foams are more susceptible to sulphate attack and perform poorly with an increase in the duration of exposure when compared to the lightest mix which showed improved responses up to 30 days of exposure due to self-healing. / Structural Engineering
842

Studies of the Insulator-Metal Transition in La1-xCaxMnO3 and Thin Film Growth of Nd0.2Sr0.8MnO3

Neupane, Krishna Prasad 13 May 2009 (has links)
Two experimental projects involving perovskite manganese oxide compounds are presented. The first involved dielectric and transport studies of the insulator-metal transition as a function of charge-carrier doping in La1-xCaxMnO3 (0 < x < 0.15) bulk samples. The results provide new insight into the role of competing magnetic, lattice and Coulomb energies in determining the insulator-metal transition near x=0.22. The second project involved the growth, structural characterization, and resistive anisotropy of a-axis oriented Nd0.2Sr0.8MnO3 thin films with thicknesses t in the range 10 nm< t < 150 nm. Thicker films develop regular crack arrays which are the origin of a highly anisotropic in-plane electrical resistance. These cracks form parallel to the crystallographic c-axis on films with tensile strain deposited on NdGaO3 (100) and La0.3Sr0.7Al0.65Ta0.35O3 (110) substrates. Films grown under compressive strain on LaAlO3 (110) substrates have no cracks.
843

Slow Slip Beneath the Nicoya Peninsula, Costa Rica and Its Effect on the Interseismic Cycle

Outerbridge, Kimberly C. 04 January 2011 (has links)
The close proximity of the Nicoya Peninsula to the Cocos-Caribbean Subduction zone plate boundary makes it a prime location to use GPS to study episodic tremor and slip. Nicoya Peninsula currently has operating networks of both continuous GPS (CGPS) and seismic stations designed to identify and characterize the pattern of episodic tremor and slip (ETS) events along the seismogenic zone under Costa Rica's Pacific Margin. The occurrence of slow slip events has been previously postulated in this region based on correlated fluid flow and seismic tremor events recorded near the margin wedge in 2000 and from sparse GPS observations in 2003. Paucity of data prevented details of these events from being resolved. In May 2007 a slow slip event was recorded on our densified GPS network. This slow slip event was also accompanied by seismic tremor, worked up by colleagues at the University of California - San Diego. I will present the GPS time series, correlated with the seismic tremor for the event in May 2007. I will also present the inferred pattern of slip on the plate interface from elastic half space inversion modeling compared with the tremor and Low Frequency Earthquake (LFE) locations. The geodetic slip and seismic tremor co-locate temporally very well. Spatially the seismic tremor and LFE locations are offset but not independent of both the up dip and down dip patches of geodetic slip. The identification of these slow slip events enhances our understanding of the nuances of the interseismic period. Previous studies of the interseismic strain accumulation patterns in the region of the Nicoya Peninsula have not accounted for the occurrence of slow slip, thus underestimating the magnitude of locking on the fault plane. My study resolves this bias by using our CGPS network to estimate the interseismic surface velocity field, accounting for the May 2007 slow slip event. I will present the results of this velocity field estimation and the results of inversions for locking patterns on the fault plane. My study has also elucidated a potential temporal variability in the locking pattern on the fault plane beneath Nicoya.
844

Investigation and modeling of processing-microstructure-property relations in ultra-fine grained hexagonal close packed materials under strain path changes

Yapici, Guney Guven 15 May 2009 (has links)
Ultra-fine grained (UFG) materials have attracted considerable interest due to the possibility of achieving simultaneous increase in strength and ductility. Effective use of these materials in engineering applications requires investigating the processing-microstructure-property inter-relations leading to a comprehensive understanding of the material behavior. Research efforts on producing UFG hexagonal close packed (hcp) materials have been limited in spite of their envisaged utilization in various technologies. The present study explores multiple UFG hcp materials to identify the general trends in their deformation behaviors, microstructural features, crystallographic texture evolutions and mechanical responses under strain path changes. UFG hcp materials, including commercial purity Ti, Ti-6Al-4V alloy and high purity Zr, were fabricated using equal channel angular extrusion (ECAE) as a severe plastic deformation (SPD) technique following various processing schedules. Several characterization methods and a polycrystal plasticity model were utilized in synergy to impart the relationships between the UFG microstructure, the texture and the post-ECAE flow behavior. Pure UFG hcp materials exhibited enhanced strength properties, making them potential substitutes for coarse-grained high strength expensive alloys. Incorporation of post-ECAE thermo-mechanical treatments was effective in further improvement of the strength and ductility levels. Strong anisotropy of the post-ECAE flow response was evident in all the materials studied. The underlying mechanisms for anisotropy were identified as texture and processing-induced microstructure. Depending on the ECAE route, the applied strain level and the specific material, the relative importance of these two mechanisms on plastic flow anisotropy varied. A viscoplastic self-consistent approach is presented as a reliable model for predicting the texture evolutions and flow behaviors of UFG hcp materials in cases where texture governs the plastic anisotropy. Regardless of the material, the initial billet texture and the extrusion conditions, ECAE of all hcp materials revealed similar texture evolutions. Accurate texture and flow behavior predictions showed that basal slip is the responsible mechanism for such texture evolution in all hcp materials independent of their axial ratio. High strength of the UFG microstructure was presented as a triggering mechanism for the activation of unexpected deformation systems, such as high temperature deformation twinning in Ti-6Al-4V and room temperature basal slip in pure Zr.
845

Samband mellan upplevd stress och självtillit på arbetsplatsen : En studie utförd på kvinnor i arbetsrelaterade situationer

Thunander, Pia, Anbratt, Manjula January 2008 (has links)
<p>Sammanfattning</p><p>Syftet med denna studie var att söka samband mellan upplevd stress och självtillit hos kvinnor i arbetsrelaterade situationer. Frågeställning: Finns det ett samband mellan upplevd stress och självtillit hos kvinnor i arbetsrelaterade situationer? Vår hypotes var att det finns ett samband mellan en kvinnas upplevda stress och självtillit i arbetsrelaterade situationer.</p><p>För vår undersökning krävdes att vi kan mäta två variabler; stressnivå och självtillit hos en individ. Vi har genomfört en kvantitativ studie där vi har använt oss av en webbaserad enkät. Vi har valt att studera yrkesverksamma kvinnor och har tillfrågat 100 kvinnor som alla har någon form av relation till oss. 62 % av kvinnorna svarade på enkäten vilket gav oss ett externt bortfall på 38 %. Det interna bortfallet eliminerade vi genom att utforma enkäten så att deltagarna antingen svarade på alla frågor eller ej registrerades.</p><p>Våra resultat valde vi att sammanställa i Excel och statistikprogrammet SPSS. Vi fick fram en korrelationskoefficient på -0,326 med en signifikansnivå på 0,010. Detta visar att korrelationen var svag men signifikant och att det fanns ett statistiskt säkerställt negativt samband mellan upplevd stress och självtillit. 60 % av kvinnorna som deltog i studien upplevde sitt arbete stressande ofta eller alltid och 90 % av studiedeltagarna upplevde att de ibland hade för mycket att göra på sitt arbete. 52 % av kvinnorna kände att de ofta eller alltid fick det stöd de behövde för att klara sina arbetsuppgifter. 50 % uppgav att de alltid eller ofta hade tillräckligt med tid att koppla av medan 29 % kände att de ibland hade tillräckligt med tid att koppla av.</p><p>Vi kan konstatera att det finns ett troligt samband mellan upplevd stress och självtillit hos kvinnor i arbetsrelaterade situationer då både tidigare forskning och vår undersökning tyder på detta förhållande. I vår studie hade studiedeltagarna generellt en hög självtillit och en relativt låg upplevd stressnivå. Den stress som deltagarna upplevde verkar kompenseras genom upplevelsen av kontroll över sitt arbete och möjligheten till återhämtning. Vi kan således konstatera att det kan vara positivt för en arbetsgivare att främja balans mellan medarbetarnas krav och kontroll.</p><p>I framtiden kan det vara av intresse att studera orsakssambandet mellan de undersökta faktorerna då det i vår studie inte var möjligt.</p> / <p>Abstract</p><p>The aim of this study was to find out whether there is a correlation between experienced strain and self-efficacy for women in work related situations. Question at issue: Is there a correlation between experienced strain and self-efficacy for women in workrelated situations?</p><p>To make the wanted comparison we had to be able to measure two variables; ones experienced strain level and the extent of self-efficacy. We have carried out a quantitative study by using a questionnaire. The population for the study consisted of 100 women in work related situations. 62 % decided to participate which gave us an external loss of 38 %. We were able to eliminate the internal loss by designing the questionnaire so that the participants either answered all the questions or where not registered.</p><p>We have compiled the result of the study in Excel and in the statistics program SPSS. That gave us the correlation coefficient -0,326 at a signification level of 0,010. This shows that the correlation was weak but significant and that the relation between strain and self-efficacy was negative. 60 % of the women in the study found their work to be stressful often or always and 90 % of the participants in the study found that they sometimes had too much to do at work. 52 % of the women found that they often or always received the support they needed to manage their work. 50 % stated that they always or often had time to relax whereas 29 % felt that they sometimes had time to relax.</p><p>We can establish that there is a possible correlation between strain and self-efficacy for women in work related situations. Both prior research and our study showed this relationship.</p><p>In our study the participants generally showed high levels of self-efficacy and relatively low levels of strain. The strain that the participants were experiencing seems to be compensated by high levels of control of their work situation and the possibility of recovery. Thus it may be positive for an employer to promote a balance between demands and control.</p><p>Further ahead it may be of interest to study the relation of cause between strain and self-efficacy as this was not possible in our study.</p>
846

Contribution to the local approach of fracture in solid dynamics.

Zhu, Yongyi 18 December 1992 (has links)
This study aims at the description, modelling and numerical prediction of ductile fracture in inelastic solids undergoing thermomechanical static or dynamic loading. Several research areas of contemporary interest in computer analysis of solids and structures are covered. The theoretical methodologies, computer implementations and practical applications will be treated. This thesis summarizes my recent research works since 1989 at the MSM Department of the University of Liège. However, it should also be useful to those who are interested in the most recent developments in finite element methods and in applying these techniques to the analysis of real industrial problems. Numerous references to original sources are included. For the convenience of the reader, each chapter of the thesis is designed to be self-contained, starts with a summary of the topic addressed, and finishes with an outline of the main results presented. Numerical examples are organized at the end of chapter 2 to 8 to assess the performance and applicability of the proposed mechanical and finite element models developed in each of them. Hereafter, a brief overview of the thesis is given. After a brief introduction in chapter 1, the numerical tools that are necessary to perform large strain thermomechanical static or dynamic analysis of solids are presented. In chapter 2, a general strategy for nonlinear dynamic finite element formulation is presented, including explicit and implicit time integration schemes. A special emphasis is placed on the application of high-speed metalforming and frictional contact-impact problems. Chapter 3 describes a strategy for solving problems involving transient thermal and thermomechanical analysis. A class of unified and mixed solid, thermal and coupled thermomechanical finite elements by assumed strain method is developed in chapter 4. Special care is taken to hourglass ans locking control. Once these developments are validated and their efficiency tested, it is then possible to tackle the problem of ductile fracture prediction and propagation. In chapter 5, a bibliographic research on the "local approach of ductile fracture" is presented. The implementation of six fracture criteria into various constitutive laws for predicting fracture initiation sites is also shown. A fully coupled elasto(-visco)-plastic damage model for isotropic material is developed in chapter 6. This model is based on irreversible thermodynamics theory and on the energy equivalence hypothesis. Chapter 7 presents the theoretical and experimental comparison for isotropic ductile material at fracture. Finally in chapter 8, the isotropic damage model of chapter 6 is extended to the case of anisotropic solids in which the damage growth itself is also anisotropic. The above developments have been implemented to an existing finite element code LAGAMINE developed since 1982 at the MSM Department of the University of Liège and are applied to many real engineering problems such as high speed rolling, magnetoforming, impact upsetting, dynamic forging, deep drawing of axisymmetric ans square cups, hot upsetting, warm folding of 3D sheet, non-isothermal hemispherical punch stretching, and other contact-impact examples.
847

Der Berufseinstieg von ÄrztInnen als normatives kritisches Lebensereignis : eine Längsschnittuntersuchung / The career entry of physicians as a normative critical life event : a longitudinal study

Felber, Juliane January 2011 (has links)
Im Rahmen einer prospektiven Längsschnittuntersuchung wurde der Berufseinstieg von ÄrztInnen (N = 185) als normatives kritisches Lebensereignis untersucht. Dazu wurden sie insgesamt drei Mal im Abstand von jeweils sechs Monaten im ersten Jahr nach ihrem Studiumsabschluss befragt (T1: in den ersten zwei Wochen nach dem Staatsexamen, T2: kurzzeitig nach dem Berufseinstieg, T3: im Schnitt 9.5 Monate nach dem Berufseinstieg). Die Ergebnisse zeigten zunächst, dass unlängst examinierte Jung-ÄrztInnen, die sich vergleichsweise schlechter auf den Beruf durch das Studium vorbereitet fühlten, ihren bevorstehenden Berufseinstieg negativer bewerteten und schon vor diesem beanspruchter waren. Die Bewertung des Berufseinstiegs vermittelte dabei den Zusammenhang zwischen einer schlechten Vorbereitung und der Beanspruchung. Arbeitsspezifische Copingfunktionalität wiederum pufferte den Zusammenhang zwischen einer schlechten Vorbereitung und der Bewertung des Berufseinstiegs. Das Problem einer als schlecht empfundenen Vorbereitung verdeutlichte sich in der Längsschnittanalyse – sie sagte eine höhere Beanspruchung zum zweiten Messzeitpunkt, d.h. nach dem Berufseinstieg, vorher. In der Untersuchung der Beanspruchungsentwicklung über die drei Messzeitpunkte hinweg fanden sich nur wenige Veränderungen. Es ließ sich zwar eine deutliche Zunahme der mittleren Depressivitäts-Ausprägungen über den Berufseinstieg hinweg herausstellen (T1-T2); auf anderen Beanspruchungsindikatoren zeigte sich jedoch kein direkter Effekt des Arbeitsbeginns bzw. fand sich auch keine Adaptation der Jung-ÄrztInnen an ihre neue Situation im Sinne einer sich verringernden Beanspruchung im weiteren Verlauf (T2-T3). In der Erklärung interindividueller Unterschiede in der Beanspruchung im Untersuchungszeitraum zeigte sich, dass die sich mit dem Berufseinstieg einstellende Arbeitsbelastung zum zweiten und dritten Messzeitpunkt erwartungsgemäß positiv mit Beanspruchung assoziiert war. Die Arbeitsbelastungs-Beanspruchungs-Beziehung bestand jedoch nur im Querschnitt; in der Längsschnittanalyse fand sich kein Effekt der T2-Arbeitsbelastung auf die T3-Beanspruchung. Ausgangsunterschiede in psychischen Ressourcen wirkten einerseits direkt auf die Beanspruchung zu T2, zum Teil moderierten sie aber auch den Zusammenhang zwischen der Arbeitsbelastung und Beanspruchung: Eine höhere Resilienz und die Wahrnehmung sozialer Unterstützung sagten eine geringere Beanspruchung nach dem Berufseinstieg vorher. Jung-ÄrztInnen, die sich durch eine stärkere Arbeitsbelastung auszeichneten, aber über ein funktionaleres Bewältigungsverhalten im Arbeitskontext verfügten, waren kurzzeitig nach dem Berufseinstieg weniger beansprucht als stark arbeitsbelastete Jung-ÄrztInnen mit weniger funktionalem Coping. Verringerungen in den psychischen Ressourcen über den Berufseinstieg hinweg wirkten sich direkt, d.h. per se ungünstig auf die Beanspruchung zum dritten Messzeitpunkt aus. Zudem interagierten sie mit der zu diesem Zeitpunkt bestehenden Arbeitsbelastung in Vorhersage der Beanspruchung. Stärker arbeitsbelastete Jung-ÄrztInnen, deren Copingfunktionalität und Wahrnehmung sozialer Unterstützung vom ersten zum dritten Messzeitpunkt abgenommen hatte, waren am Ende des Untersuchungszeitraums am stärksten beansprucht. Hinsichtlich der Auswirkungen des Berufseinstiegs auf die Persönlichkeit der Jung-ÄrztInnen fanden sich ungünstige Veränderungen: Sowohl die Ausprägungen psychischer Ressourcen (Widerstandsfähigkeit, Wahrnehmung sozialer Unterstützung hinsichtlich der Arbeitstätigkeit) als auch die der Big Five-Faktoren nahmen im Mittel ab. Interindividuelle Unterschiede in den Veränderungen ließen sich auf die Beanspruchung kurzzeitig nach dem Berufseinstieg (T2) bzw. auf deren Entwicklung in den Folgemonaten (T2-T3) zurückführen: Jene Jung-ÄrztInnen, die vergleichsweise stark beansprucht auf den Berufseinstieg reagiert hatten bzw. deren Beanspruchung im weiteren Verlauf zunahm, zeigten entsprechend ungünstige Veränderungen. Die Ergebnisse zusammengefasst verdeutlicht sich folgende Problematik: Jung-ÄrztInnen, die weniger gut, d.h. persönlichkeitsbasiert geschützt den Berufseinstieg absolvieren, reagieren stärker beansprucht und sind dann auch diejenigen, deren Persönlichkeit sich in den ersten Arbeitsmonaten ungünstig verändert. Jung-ÄrztInnen mit geringen psychischen Ressourcen sind folglich nicht nur besonders vulnerabel für die Entwicklung von Beanspruchung angesichts belastender Arbeitsbedingungen, sondern ihre vergleichsweise hohe Beanspruchung bedingt eine weitere Verringerung des Schutz- und Pufferpotenzials ihrer Persönlichkeit. Es kommt zu einer ungünstigen Akzentuierung der ohnehin schon vergleichsweise ressourcenschwachen Persönlichkeit, welche die Vulnerabilität für zukünftige Beanspruchung erhöht. Aus den Ergebnissen lässt sich ein Unterstützungsbedarf junger ÄrztInnen in der sensiblen und wegweisenden Berufseinstiegsphase ableiten. Neben einer Verbesserung ihrer Arbeitsbedingungen stellen eine rechtzeitige Sensibilisierung junger ÄrztInnen für den Arbeitsbelastungs-Beanspruchungs-Zusammenhang, ihre regelmäßige Supervision sowie vor allem aber auch kompetenzorientiertes und ressourcenstärkendes Feedback von den Mentoren und Vorgesetzten die Grundlage dafür dar, dass die Jung-MedizinerInnen selbst gesund bleiben und sie die ärztliche Tätigkeit trotz ihres wohl stets hohen Belastungspotenzials als erfüllend und zufriedenstellend erleben. / The career entry of physicians (N = 185) as a normative critical life event was examined in a longitudinal study. They were surveyed three times within the first year after their final exams (T1: 1-2 weeks after the final exam, T2: six months later and post career entry, T3: on average 9.5 months after career entry). The results showed that young physicians who felt insufficiently prepared for work by their medical studies anticipated the career entry less positive and reported more strain at T1 already. The anticipation of the career entry mediated the relationship between poor preparation and strain. Work-related coping buffered the relationship between poor preparation and anticipation of the career entry. A poor preparation furthermore predicted higher levels of strain at T2. Analyzing the development of strain indicators over time (T1-T2-T3) and on average, little change was found. Only depression-levels increased; a decrease in strain from T2 to T3, indicating adaptation to the new circumstances, was not detected. With regard to individual differences in strain, work-related stressors were positively associated with strain at T2 and T3. However, the stressor-strain-relationship was observed only cross-sectionally but not over time (T2-T3). T1-personality resources had a direct impact on T2-strain but furthermore moderated the T2-stressor-strain-relationship: Resilience and perceived social support were associated with lower levels of strain. Young physicians with poor working conditions but functional coping strategies reported less strain than those with poor working conditions and dysfunctional coping. Decreasing resources from T1 to T3 had a direct negative impact on T3-strain but also interacted with T3-work related stressors: Young physicians with poor working conditions at T3 and a T1-T3-decline in coping functionality and perceived social support reported the highest strain levels at T3. Over the career entry period, adverse personality change was observed: On average, resilience and social support decreased. Furthermore, non-normative change was observed on all Big Five-factors. Inter-individual differences within personality change were due to strain shortly after career entry (T2) and to its further development (T2-T3): Young physicians who had reported high levels of strain shortly after career entry, as well as those with increasing strain levels throughout the following months, were at higher risk for declines in protective traits and the Big Five-factors. Summing up the results, it can be concluded that young physicians with low personality resources do not only report higher strain levels in response to their career entry, but because of their higher strain they are also at a higher risk of decreasing protective traits. This means that young physicians with low resources are more vulnerable to work-related stressors and, consequently, their high levels of strain lead to a further decrease of the buffer potential of their personality. The detrimental accentuation of their weak protective personality potential heightens the risk for future strain. The results illustrate the need for supporting young physicians in this sensitive and significant transition phase. In addition to an improvement of their working conditions, they should be made aware of the stressor-strain-relationship at an early stage. Furthermore, they should be constantly supervised and receive competence-focused and resource-consolidating feedback from their mentors and supervisors. For young physicians, these are prerequisites for sustaining their own health under stressful working conditions and for experiencing the practice of medicine as fulfilling and satisfying.
848

Durability of Embedded Fibre Optic Sensors in Composites

Levin, Klas January 2001 (has links)
This thesis concerns various aspects of the durability offibre optic sensors embedded in composite. Since repair orreplacement of embedded sensors is not generally possible, thefunctional reliability of embedded sensors is one of the mostimportant prerequisites for successful use. The main researchobjective was to investigate the interaction between the sensorand the composite, and how this is affecting the mechanical andoptical sensor response. Fibre optic sensors embedded incomposite structures induce local stress concentrations whenthe composite is subjected to mechanical loads andenvironmental changes such as temperature and moisture. Acomplex transfer of stresses through the interfaces between theembedded sensor and the composite occurs and can result inlarge local stresses in the composite and a significant changein the response of the embedded sensor. These stressconcentrations make the interfaces susceptible todebonding. The sensor performance was studied experimentally andnumerically. Some basic results were generated for the EFPI andBragg grating sensors. The phase-strain response was determinedduring static and fatigue loading. The results showed that thesensors were more reliable in compression than in tensilestatic and fatigue loading. Generally, the sensor reliabilityduring loading was significantly improved for the Bragg gratingsensors over that of the EFPI sensor, as an effect of thesensor geometry. This was also demonstrated in theinvestigations on impacts. Impacts do not necessarily result indamage in the composite, but might cause debonding or otherfailure modes in the sensor area. Large, local stressconcentrations occur at several positions in the EFPI sensor,which pointed out that this sensor type was not suitable forembedded applications. The shift in focus from the sensor concept based on the EFPIsensor to that based on the Bragg grating sensor manifesteditself in several studies. The calculated deformation fieldaround an embedded optical fibre was verified in experimentsusing a high-resolution moiré interferometric technique.Furthermore, the improvement in the coating technology wasverified. A significant higher interfacial strength wasobtained with the silane-treated glass surface. The resultsindicated that at least a twofold improvement of the shearstrength was obtained. To simultaneously measure the in-plane strain components andthe temperature change, embedded Bragg grating sensors werearranged in a rosette configuration. The relationship betweenthe optical response from each sensor and the strains in thelaminate was numerically and analytically established. Damage lead to stress redistribution in the sensor region,which may influence the output from the embedded Bragg gratingsensor. The effect was numerically evaluated for interfacialdamage, and was compared to that of a sensor with undamagedinterface. The results showed that debonding might have asignificant influence, in particular for combined thermal andmechanical loading. <b>Keywords</b>: composites, fibre optic sensor, embedded, EFPIsensor, Bragg grating sensor, durability, fatigue, impact,strain measurement, interface, stress analysis
849

Quantification of regional myocardial function by strain rate and strain for evaluation of coronary artery disease : Automated versus manual analysis during acute myocardial infarction and dobutamine stress echocardiography

Ingul, Charlotte Björk January 2006 (has links)
Kvantifisering av hjertets muskelfunksjon med tøyning og tøyningshastighet målt med ultralyd for vurdering av koronar sykdom. Automatisert metode versus manuell ved akutt hjerteinfarkt og ultralyd stress test. 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. 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. 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. 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. / Paper I and II preprinted with kind permission of Elsevier, sciencedirect.com
850

Vårdpersonalens upplevelser av omvårdnaden hos personer med demenssjukdom : en litteraturstudie

Wihlborg, Helen, Wänman, Maria January 2010 (has links)
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. / 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.

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