No description available.

A first-principles linear scaling real-space method for investigating non-collinear magnetic behaviour of nanostructured materials has been developed. With this method, the magnetic structures of small supported transition metal clusters have been examined. The geometric constraints imposed on the clusters by the underlying surface is found to cause non-collinear behaviour for V, Cr, and Mn clusters on Cu(111). Fe clusters supported on Cu and Ni have been studied and both spin and orbital moments are found to be enhanced for the Fe atoms, which is attributed to the recuced symmetry present at the surface. Atoms in Co clusters have been found to order antiferromagnetically, and some times in a non-collinear fasion, when deposited on a W surface. Small clusters of fcc Fe embedded in Cu have been examined and a new type of ordering, not present in larger fcc Fe systems was found. Several theoretical studies of Fe and Co based nanostructures consisting of multilayers or embedded clusters have been conducted, with the aim of predicting high moment materials for use in data storage applications. In agreement with previous experiments an enhancement of the magnetic moment is found compared to the magnetic moment of bcc Fe. The enhancement has been shown to be caused by increased spin moments for Fe atoms in close proximity with Co atoms, and this enhancement depends on the number of Co neighbours. As a result of these studies, a possible method of increasing the magnetic moment of cluster based materials has been proposed. Fermi surface analysis have been performed both on bulk materials, in order to investigate mechanisms for stabilizing non-collinear magnetic states, and in layered structures where the effect of the Fermi surface on the interlayer exchange coupling has been investigated. In addition to the development of a real-space electronic structure method for non-collinear magnetism, a density matrix purification method has been implemented in the framework of linear muffin-tin orbitals.

Social science researchers are increasingly using multi-group confirmatory factor analysis (MG-CFA) to compare different groups' latent variable means. To ensure that a MG-CFA model is identified, two approaches are commonly used to set the scale of the latent variable. The reference indicator (RI) strategy, which involves constraining one loading per factor to a value of one across groups, assumes that the RI has equal factor loadings across groups. The second approach involves constraining each factor's variance to a value of one across groups and, thus, assumes that the factor variances are equal across groups. Latent mean differences may be tested and described using Gonzalez and Griffin's (2001) likelihood ratio test (LRT[subscript k]) and Hancock's (2001) standardized latent mean difference effect size measure ([delta subscript k]), respectively. Applied researchers using the LRT[subscript k] and/or the [delta subscript k] when comparing groups' latent means may not explicitly test the assumptions underlying the two factor scaling methods. To date, no study has examined the impact of violating the assumptions associated with the two scaling methods on latent mean comparisons. The purpose of this study was to assess the performance of the LRT[subscript k] and the [delta subscript k] when violating the assumptions underlying the RI strategy and/or the factor variance scaling method. Type I error and power of the LRT[subscript k] as well as relative parameter bias and parameter bias of the [delta subscript k] were examined when varying loading difference magnitude, factor variance ratio, factor loading pattern and sample size ratio. Rejection rates of model fit indices, including the x² test, RMSEA, CFI, TLI and SRMR, under these varied conditions were also examined. The results indicated that violating the assumptions underlying the RI strategy did not affect the LRT[subscript k] or the [delta subscript k]. However, violating the assumption underlying the factorvariance scaling method influenced Type I error rates of the LRT[subscript k], particularly in unequal sample size conditions. Results also indicated that the four factors manipulated in this study had an impact on correct model rejection rates of the model fit indices. It is hoped that this study provides useful information to researchers concerning the use of the LRT[subscript k] and [delta subscript k] under factor scaling method assumption violations. / text

La compréhension des enzymes et de leurs mécanismes catalytiques est d'une grande importance dans le développement de médicaments plus efficaces Pour mieux appréhender ces phénomènes, différentes approches théoriques comme les méthodes QM, MM-MD et QM/MM, peuvent être utilisées. L'objectif principal de cette thèse est d'obtenir une meilleure compréhension des mécanismes de réactivité et de la dynamique de l'enzyme GABA-AT (y-aminobutyric acid aminotransferase), un modèle d'enzyme dépendante au phosphate pyridoxal (PLP). Notre travail a consisté en 5 étapes vers une plus grande compréhension de GABA-AT. 1) la réaction et le mode d'attachement du substrat naturel GABA ont été étudié pour différents isomères à l'aide de systèmes modèles et de la DFT. 2) l'enzyme a été simulée par dynamique moléculaire classique dans les cas de l'apoenzyme, l'holoenzyme et l'holoenzyme inactivée. Nos résultats montrent que plusieurs résidus du site actif jouent un rôle important et que leur état de protonation ainsi que celui du PLP sont cruciaux dans l'activité de GABA-AT. 3) l'influence des résidus du site actif sur la réactivité a été étudiée par la modélisation quantique de clusters moléculaires. Le plus gros cluster comprenait 165 atomes entouré d'un solvant implicite. 4) de nouvelles routines de diagonalisation pour SEBOMD ont été incorporées dans la suite AMBER à travers l'utilisation des bibliothèques LAPACK et SCALAPACK. Ces nouvelles routines ont été testées et leur efficacité a été évaluée. 5) des énergies libres de réaction ont été évaluées par dynamiques SEBOMD sur des intermédiaires réactionnels GABA-PLP / Understanding enzymes and their catalytic mechanisms is very important in order to develop more effective drugs having little to no side effects. In order to decipher the catalytic behavior of enzymes, different approaches such as QM, MM-MD, and QM/MM can be used and their results can be correlated. The main aim of this thesis is to get a deeper understanding of the mechanistic insights of the reactivity and of the dynamics of the pyridoxal-5-phosphate (PLP) dependent enzyme y-aminobutyric acid aminotransferase (GABA-AT). Because GABA-AT resembles many other PLP-dependent enzymes, understanding it could be of importance for the broad community of biochemists and computational chemists who study such class of proteins. Our work has consisted of five stages to pursuit the comprehension of GABA-AT. First, the reaction and the preferred binding mode of the natural substrate GABA has been elucidated with different isomers by means of model systems with DFT. Second, the dynamics and the behavior of the enzyme has been studied with MM-MD through the use of apoenzyme, holoenzyme and holoenzyme with an inactivator. Third, the effect of the active site residues in the inactivation mechanism has been investigated with the modelling of clusters at the QM level involving key residues. Fourth, new diagonalization routines for the SEBOMD (SemiEmpirical Born-Oppenheimer Molecular Dynamics) approach implemented in the Amber suite of programs, have been incorporated using LAPACK and SCALAPACK libraries, tested and evaluated to optimize the diagonalization procedure of the Fock matrix. Fifth, reaction free energies of PLP containing systems have been investigated with SEBOMD simulations

Collaboration appears to be a magical solution for many problems when there is scarcity of resources, lack of knowledge or skills, and/or environmental threats. However, there is little knowledge about the nature of collaboration. A holistic conceptual framework was developed for the collaborative process, and the conceptualization process used systems thinking approach. The author has selectively chosen conceptualizations and/or research by a limited subset of scholars whose ideas appeared to be the most relevant and useful to explore the type of collaboration studied here. In other words, the selection of the literature was based on an eclectic selection. Multiple cases were used in this research to understand the factors that are components of collaborative effort among non-profit organizations and the relationships among those factors. This study also investigated the stages of collaborative process. Data were collected from 54 participants who were partners in collaborate projects funded by the Institute of Museum and Library Services (IMLS). Among these 54 participants, 50 answered the online questionnaire and 38 received the telephone interviews. The data collected was analyzed using cluster analysis, multidimensional scaling, internal consistency reliability, and descriptive statistics. The component factors of collaboration were grouped by the following seven concepts: trustworthiness, competence, dependency, misunderstanding and/or conflict, complexity, commitment and mechanism of coordination. This study showed twelve relationships among these factors. For instance, different points of view and partners' capacity to maintain inter-organizational relationships were found to be opposite concepts. In addition, the findings in this study indicate that 84% of participants reported the presence of the five pre-defined stages: execution, networking, definition, relationship, and common evaluation.

Companies are constantly challenged to maintain but also to expand their market position. According to a study it’s problematic to carry out successful IT-projects. Dependencies, coordination and long term planning are three factors which has shown are difficult to master in bigger projects. The aim with the study is to in- vestigate how these aspects work in one case, through a case study on an IT com- pany. The goal is to contribute with research to the subject of long term planning in IT-projects where agile methods usually is used today. Previous research and theories as project management, agile project management, planning methods, scaling methods, coordination methods and change management are used as a base for the study. An exploratory qualitative study has been performed at the case company, the generated result composes of interviews with personnel from the company. The result showed how the methods and theories where used in the case company mainly focusing on long-term planning and workflows. Generally, the same thoughts where shared among the personnel, but because of the open questions the responder got encouraged to elaborate and explain their opinion leading to new information and aspects even when they agreed on the topic. When analyzing the result, I show that a clear framework, implementing of sim- ple work methods and the project management were all important to be able to conduct long-term planning and handle dependencies in projects. The conclusion was to implement the scaling method SAFe but also to use coordination methods. An important aspect is to include change management processes and theories when implementing or changing something. Further studies suggest that research in this article should be carried out on more companies and studies if the imple- mentation of the agila scaling method SAFe has a positive effect in a company. / Varje dag utmanas företag för att bibehålla men även utöka deras marknadspo- sition. Enligt en studie så är det problematiskt att genomföra lyckade IT-projekt. Beroenden, koordinering och långsiktig planering är tre faktorer som det visat sig vara svårt med i större projekt. Syftet med studien är att undersöka hur dessa aspekter fungerar på ett visst fall, genom en fallstudie på ett IT-företag. Målet är att kunna bidra med forskning till ämnet gällande långsiktig planering i IT-pro- jekt där agila metoder vanligtvis idag används. Tidigare forskning och teorier som projektledning, agil projektledning, planeringsmetoder, skalningsmetoder, koordineringsmetoder samt förändringsledning ligger till grund för studien. En explorativ kvalitativ studie har genomförts på fallföretaget. Det genererade re- sultatet baseras på intervjuer med personal på företaget. Resultatet visade hur det fungerade på fallföretaget gällande långsiktig planering och arbetssätt. I stora drag framfördes liknande tankar och åsikter, men då de ställda frågorna var öppet ställda så framkom även olika nyanser och delar från de olika respon- denterna. Analysen av resultatet visade att tydligare ramverk, implementering av arbetssätt och ledning var viktiga för att kunna planera långsiktigt och han- tera beroenden. Slutsatsen som drogs var att implementera skalningsmetoden SAFe men också använda sig av koordineringsmetoder. En viktig aspekt att inte förglömma är även förändringsarbetet vid införandet eller förändring av något. För vidare forskning skulle studien kunna göras på fler företag och även en stu- die på implementeringen av den agila skalningsmetoden SAFe skulle kunna gö- ras för att se om det skulle ge en positiv effekt för företaget.