| 1. |
- Dzansi, James
(författare)
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Essays on Financing and Returns on Investment
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation consists of an introductory chapter and three independent essays on financing investment and their returns. The first essay studies the impact of remittances on domestic investment. The analysis is carried out with a focus on the moderating roles of domestic financial development and institutional quality. The empirical results suggest that remittance inflows are associated with increased domestic investment spending, particularly under conditions of inadequate financial intermediation and poor institutional quality. The second essay evaluates whether remittance inflows into the developing world impedes or spurs manufacturing growth. This study uses manufacturing data on a sample of 40 remittance dependent economies over the period from 1991 to 2004. The results suggest that remittance inflows accelerate manufacturing growth. This evidence is robust to industry- and year-specific effects, a range of country level control variables, and a number of estimators. The final essay examines the monitoring role of large shareholders and returns on investment. Specifically, the paper investigates the relevance of intrinsic motives of the large shareholder to monitor management in order to induce optimal return on investment. The findings suggest that large shareholders are actuated by both intrinsic and extrinsic motives to minimize managerial opportunism and inefficiency.
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| 2. |
- Johansson, Sara, 1975-
(författare)
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Knowledge, Product Differentiation and Trade
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this thesis is to analyze the influence of knowledge on the export performance of firms in different regions. More specifically, this study focuses on the impact of knowledge on the structure of regional export flows, in terms of horizontal and vertical product differentiation, as well as the geographical distribution of export flows. The thesis consists of four separate papers, which contribute to the overall analysis of knowledge, product differentiation and international trade in different ways. The second chapter presents a study of the effects of regional accessibility to R&D on the diversity of export flows with regard to goods, firms and destination markets. Chapter 3 provides an empirical analysis of vertical product differentiation, i.e. differentiation in terms of product quality, and examines the impact of educated labor and R&D on regional comparative advantages in goods of relatively high product quality. Chapter 4 contains a study of how the regional endowment of highly educated workers affects the structure of export flows, i.e. how the endowment of educated workers impacts on the number of product varieties exported, the average price per variety and the average quantity shipped out. The final chapter presents a micro-level analysis of firms’ propensity to participate in international markets and their propensity to expand export activities by introducing new export products or establishing export links with new destination countries. In summary, the empirical results of this thesis convey the message that regional accessibility to knowledge, embodied in highly educated labor and/or developed through R&D activities, plays a fundamental role in shaping the content and structure of regional export flows. More specifically, the present empirical observations suggest that the regional endowment of knowledge stimulates the size of the export base in terms of exporting firms and number of product varieties. The recurring significance of the accessibility variables in explaining spatial export patterns show that the knowledge endowment of a region must be defined in such ways that it captures sources of potential knowledge spillovers from inside as well as outside its own regional boundaries. This outcome shows that regional variations in knowledge endowments originate both in the actual spatial distribution of a nation’s knowledge labor across regions, and in regional differences in the geographical accessibility to internal and external knowledge labor.
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| 3. |
- Andersson, David, 1978-
(författare)
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From the Electronic Structure of Point Defects to Functional Properties of Metals and Ceramics
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Point defects are an inherent part of crystalline materials and they influence important physical and chemical properties, such as diffusion, hardness, catalytic activity and phase stability. Increased understanding of point defects enables us to tailor the defect-related properties to the application at hand. Modeling and simulation have a prominent role in acquiring this knowledge. In this thesis thermodynamic and kinetic properties of point defects in metals and ceramics are studied using first-principles calculations based on density functional theory. Phenomenological models are used to translate the atomic level properties, obtained from the first-principles calculations, into functional materials properties. The next paragraph presents the particular problems under study. The formation and migration of vacancies and simple vacancy clusters in copper are investigated by calculating the energies associated with these processes. The structure, stability and electronic properties of the low-oxygen oxides of titanium, TiOx with 1/3 < x < 3/2, are studied and the importance of structural vacancies is demonstrated. We develop an integrated first-principles and Calphad approach to calculate phase diagrams in the titanium-carbon-nitrogen system, with particular focus on vacancy-induced ordering of the substoichiometric carbonitride phase, TiCxNy (x+y < 1). The possibility of forming higher oxides of plutonium than plutonium dioxide is explored by calculating the enthalpies for nonstoichiometric defect-containing compounds and the analysis shows that such oxidation is only produced by strong oxidants. For ceria (CeO2) doped with trivalent ions from the lanthanide series we probe the connection between the choice of a dopant and the improvement of ionic conductivity by studying the oxygen-vacancy formation and migration properties. The significance of minimizing the dopant-vacancy interactions is highlighted. We investigate the redox thermodynamics of CeO2-MO2 solid solutions with M being Ti, Zr, Hf, Th, Si, Ge, Sn or Pb and show that reduction is facilitated by small solutes. The results in this thesis are relevant for the performance of solid electrolytes, which are an integral part of solid oxide fuel cells, oxygen storage materials in automotive three-way catalysts, nuclear waste materials and cutting tool materials.
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| 4. |
- Arapan, Sergiu, 1973-
(författare)
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Understanding Physical Reality via Virtual Experiments
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis I have studied some problems of condensed matter at high pressures and temperatures by means of numerical simulations based on Density Functional Theory (DFT).The stability of MgCO3 and CaCO3 carbonates at the Earth's mantle conditions may play an important role in the global carbon cycle through the subduction of the oceanic crust. By performing ab initio electronic structure calculations, we observed a new high-pressure phase transition within the Pmcn structure of CaCO3. This transformation is characterized by the change of the sp-hybridization state of carbon atom and indicates a change to a new crystal-chemical regime. By performing ab initio Molecular Dynamics simulations we show the new phase to be stable at 250 GPa and 1000K. Thus, the formation of sp3 hybridized bonds in carbonates can explain the stability of MaCO3 and CaCO3 at pressures corresponding to the Earth's lower mantle conditions. We have also calculated phase transition sequence in CaCO3, SrCO3 and BaCO3, and have found that, despite the fact that these carbonates are isostructural and undergo the same type of aragonite to post-aragonite transition, their phase transformation sequences are different at high pressures.The continuous improvement of the high-pressure technique led to the discovery of new composite structures at high pressures and complex phases of many elements in the periodic table have been determined as composite host-guest incommensurate structures. We propose a procedure to accurately describe the structural parameters of an incommensurate phase using ab initio methods by approximating it with a set of analogous commensurate supercells and exploiting the fact that the total energy of the system is a function of structural parameters. By applying this method to the Sc-II phase, we have determined the incommensurate ratio, lattice parameters and Wyckoff positions of Sc-II in excellent agreement with the available experimental data. Moreover, we predict the occurrence of an incommensurate high-pressure phase in Ca from first-principle calculations within this approach.The implementation of DFT in modern electronic structure calculation methods proved to be very successful in predicting the physical properties of a solid at low temperature. One can rigorously describe the thermodynamics of a crystal via the collective excitation of the ionic lattice, and the ab initio calculations give an accurate phonon spectra in the quasi-harmonic approximation. Recently an elegant method to calculate phonon spectra at finite temperature in a self-consistent way by using first principles methods has been developed. Within the framework of self-consistent ab initio lattice dynamics approach (SCAILD) it is possible to reproduce the observed stable phonon spectra of high-temperature bcc phase of Ti, Zr and Hf with a good accuracy. We show that this method gives also a good description of the thermodynamics of hcp and bcc phases of Ti, Zr and Hf at high temperatures, and we provide a procedure for the correct estimation of the hcp to bcc phase transition temperature.
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| 5. |
- Baykov, Vitaly, 1977-
(författare)
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Point defect interactions and structural stability of compounds
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Theoretical studies of point defect interactions and structural stability of compounds have been performed using density functional theory. The defect-related properties, such as activation energy of diffusion, electronic and magnetic structure of selected materials have been studied. The major part of the present work is devoted to a very important material for semiconductor industry, GaAs. The formation energies of intrinsic point defects and the solution energies of 3d transitions in GaAs have been calculated from first principles. Based on the calculated energies, we analysed the site preference of defects in the crystal. The tendency of defects to form clusters has been investigated for the intrinsic defects as well as for impurities in GaAs. The magnetic moment of 3d impurities has been calculated as a function of the chemical environment. The possibility of increasing the Curie temperature in (Ga,Mn)As by co-doping it with Cr impurities has been examined on the basis of calculated total energy difference between the disordered local moment and the ferromagnetically ordered spin configurations. We found that, in order to reach the highest critical temperature, GaAs should be separately doped with either Cr or Mn impurities. Also, we have shown that diffusion barrier of interstitial Mn depends on the charge state of this impurity in (Ga, Mn)As. The formation of defect complexes between interstitial and substitutional Mn atoms, and their influence on the value of diffusion barrier for interstitial Mn, has been studied. The pair interactions energies between interstitial oxygen atoms in hcp Zr, Hf and Ti have been calculated using first principles. Based on the calculated energies, the oxygen ordering structures in IVB transition metal solid solutions have been explained. A prediction of nitrogen ordering in Hf-N solid solution has been made. The thermodynamic description of intermetallic compounds in the Zr-Sn binary system has been obtained. The conclusion has been made that Zr substitution on the Sn sites takes place in the Zr4Sn phase, which accounts for the unusual stoichiometry of this Cr3Si structure type compound. The influence of pressure on the phase stability in the Fe-Si system has been investigated. We have found instability of the hcp Fe0.9Si0.1 random alloy with respect to the decomposition onto the Si-poor hcp Fe alloy and the B2 FeSi under high pressure. The tendency of this decomposition becomes stronger with increasing the applied pressure.
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| 6. |
- Davis, Sergio
(författare)
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Atomistic Computer Simulations of Melting, Diffusion and Thermal Defects in High Pressure Solids
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present work describes the use of atomistic computer simulations in the area of Condensed Matter Physics, and speci cally its application to the study of two problems: the dynamics of the melting phase transition and the properties of materials at extremely high pressures and temperatures, problems which defy experimental measurements and purely analytical calculations. A good sampling of techniques including classical and rst-principles Molecular Dynamics, and Metropolis Monte Carlo simulation have been applied in this study. It includes the calculation of melting curves for a wide range of pressures for elements such as Xe and H2, the comparison of two di erent models for molecular interactions in ZrO2 with respect to their ability to reproduce the melting point of the stable cubic phase, the study of the elastic constants of Fe at the extreme conditions of the Earth's inner core, and the stability of its crystalline phases. One of the most interesting results in this work is the characterization of di usion and defects formation in generic models of crystalline solids (namely Lennard-Jones and Embedded-atom) at the limit of superheating, including the role they play in the triggering of the melting process itself.
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| 9. |
- Johansson, Catrin
(författare)
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Visioner och verkligheter : Kommunikationen om företagets strategi
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The starting point for this study is the question of why organizational visions are often interpreted by employees as unintelligible and insignificant. The knowledge gap in this area makes the study of communication about vision and goals both urgent and interesting.Accordingly, the purpose is to advance knowledge on communication processes in organizations through description and analysis of communication about strategy, encompassing vision, strategic objectives and common values, in a company.A case study design was chosen and a longitudinal qualitative study was conducted in the company, from April 1998 to January 2000. A combination of methods were used, including participant observation, discourse analysis and interviews.Communication about the strategy followed a typical top-down model, starting on group level and ending on department level. In this process, Balanced Scorecard was used as a tool to communicate the strategy.It was concluded that visions formulated by top managers met different realities constructed by managers at lower levels in the company. Managers’ attitudes, knowledge and interpretations were important individual factors that influenced communication about the strategy. Employees did not have the same detailed knowledge of the strategy as the managers, nor were they given the same opportunities to obtain it.The discourse analysis reveals power structures, conflicts, individual attitudes and perspectives. The study thus results in a deep understanding of communication problems in the organization.
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| 10. |
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