Photodamage to Oxygen Evolving Complex - An Initial Event in Photoinhibition of Photosystem II.

Photosystem II (PSII) of oxygenic photosynthesis is susceptible to photoinhibition. Photoinhibition is defined as light induced damage resulting in turnover of the D1 protein subunit of the reaction center of PSII. Both visible and ultraviolet (UV) light cause photoinhibition. Photoinhibition induced by UV light damages the oxygen evolving complex (OEC) via absorption of UV photons by the Mn ion(s) of OEC. Under visible light, most of the earlier hypotheses assume that photoinhibition occurs when the rate of photon absorption by PSII antenna exceeds the use of the absorbed energy in photosynthesis. However, photoinhibition occurs at all light intensities with the same efficiency per photon. The aim of my thesis work was to build a model of photoinhibition that fits the experimental features of photoinhibition. I studied the role of electron transfer reactions of PSII in photoinhibition and found that changing the electron transfer rate had only minor influence on photoinhibition if light intensity was kept constant. Furthermore, quenching of antenna excitations protected less efficiently than it would protect if antenna chlorophylls were the only photoreceptors of photoinhibition. To identify photoreceptors of photoinhibition, I measured the action spectrum of photoinhibition. The action spectrum showed resemblance to the absorption spectra of Mn model compounds suggesting that the Mn cluster of OEC acts as a photoreceptor of photoinhibition under visible light, too. The role of Mn in photoinhibition was further supported by experiments showing that during photoinhibition OEC is damaged before electron transfer activity at the acceptor side of PSII is lost. Mn enzymes were found to be photosensitive under visible and UV light indicating that Mn-containing compounds, including OEC, are capable of functioning as photosensitizers both in visible and UV light. The experimental results above led to the Mn hypothesis of the mechanism of continuous-light-induced photoinhibition. According to the Mn hypothesis, excitation of Mn of OEC results in inhibition of electron donation from OEC to the oxidized primary donor P680+ both under UV and visible light. P680 is oxidized by photons absorbed by chlorophyll, and if not reduced by OEC, P680+ may cause harmful oxidation of other PSII components. Photoinhibition was also induced with intense laser pulses and it was found that the photoinhibitory efficiency increased in proportion to the square of pulse intensity suggesting that laser-pulse-induced photoinhibition is a two-photon reaction. I further developed the Mn hypothesis suggesting that the initial event in photoinhibition under both continuous and pulsed light is the same: Mn excitation that leads to the inhibition of electron donation from OEC to P680+. Under laser-pulse-illumination, another Mn-mediated inhibitory photoreaction occurs within the duration of the same pulse, whereas under continuous light, secondary damage is chlorophyll mediated. A mathematical model based on the Mn hypothesis was found to explain photoinhibition under continuous light, under flash illumination and under the combination of these two.

Finnish embryo transfer breeding program "ASMO" : description of the goals and a summary of the results of initial selection

Selostus: Alkionsiirtojalostusohjelma "ASMO", sen tavoitteet ja yhteenveto alkuvalinnan tuloksista

The initial oxidation of transition metal surfaces

Due to their numerous novel technological applications ranging from the example of exhaust catalysts in the automotive industry to the catalytic production of hydro- gen, surface reactions on transition metal substrates have become to be one of the most essential subjects within the surface science community. Although numerous applications exist, there are many details in the different processes that, after many decades of research, remain unknown. There are perhaps as many applications for the corrosion resistant materials such as stainless steels. A thorough knowledge of the details of the simplest reactions occuring on the surfaces, such as oxidation, play a key role in the design of better catalysts, or corrosion resistant materials in the future. This thesis examines the oxidation of metal surfaces from a computational point of view mostly concentrating on copper as a model material. Oxidation is studied from the initial oxidation to the oxygen precovered surface. Important parameters for the initial sticking and dissociation are obtained. The saturation layer is thoroughly studied and the calculated results arecompared with available experimental results. On the saturated surface, some open questions still remain. The present calculations demonstrate, that the saturated part of the surface is excluded from being chemically reactive towards the oxygen molecules. The results suggest, that the reason for the chemical activity of the saturated surface is due to a strain effect occuring between the saturated areas of the surface.

Social ventures : the development of the theory of sustainable contributive advantage and initial empirical tests

This thesis attempts to fill gaps in both a theoretical basis and an operational and strategic understanding in the areas of social ventures, social entrepreneurship and nonprofit business models. This study also attempts to bridge the gap in strategic and economic theory between social and commercial ventures. More specifically, this thesis explores sustainable competitive advantage from a resource-based theory perspective and explores how it may be applied to the nonmarket situation of nonprofit organizations and social ventures. It is proposed that a social value-orientation of sustainable competitive advantage, called sustainable contributive advantage, provides a more realistic depiction of what is necessary in order for a social venture to perform better than its competitors over time. In addition to providing this realistic depiction, this research provides a substantial theoretical contribution in the area of economics, social ventures, and strategy research, specifically in regards to resource-based theory. The proposed model for sustainable contributive advantage uses resource-based theory and competitive advantage in order to be applicable to social ventures. This model proposes an explanation of a social venture’s ability to demonstrate consistently superior performance. In order to determine whether sustainable competitive advantage is in fact, appropriate to apply to both social and economic environments, quantitative analyses are conducted on a large sample of nonprofit organizations in a single industry and then compared to similar quantitative analyses conducted on commercial ventures. In comparing the trends and strategies between the two types of entities from a quantitative perspective, propositions are developed regarding a social venture’s resource utilization strategies and their possible impact on performance. Evidence is found to support the necessity of adjusting existing models in resource-based theory in order to apply them to social ventures. Additionally supported is the proposed theory of sustainable contributive advantage. The thesis concludes with recommendations for practitioners, researchers and policy makers as well as suggestions for future research paths.

Successful IFRS standard change implementation process after the initial IFRS implementation

The main objective of the study was to form a strategic process model and project management tool to help IFRS change implementation projects in the future. These research results were designed based on the theoretical framework of Total Quality Management and leaning on the facts that were collected during the empirical case study of IAS 17 change. The us-age of the process oriented approach in IFRS standard change implementation after the initial IFRS implementation is rationalized with the following arguments: 1) well designed process tools lead to optimization of resources 2) With the help of process stages and related tasks it is easy to ensure the efficient way of working and managing the project as well as make sure to include all necessary stakeholders to the change process. This research is following the qualitative approach and the analysis is in describing format. The first part of the study is a literature review and the latter part has been conducted as a case study. The data has been col-lected in the case company with interviews and observation. The main findings are a process model for IFRS standard change process and a check-list formatted management tool for up-coming IFRS standard change projects. The process flow follows the main cornerstones in IASB’s standard setting process and the management tool has been divided to stages accordingly.

Internal Changes in International New Ventures During Initial Internationalization: Finnish SMEs Operating in Dynamic High-tech Industries

The purpose of this qualitative research is to study how international new ventures change internally during initial internationalization. Based on the analysis of seven INV firms, a framework illustrating this change process, will be developed. This research will also develop earlier theories, and create a solid combination of existing theories to explain the phenomenon. INV firms internationalize more rapidly and aggressively than traditional MNEs. At the same, external and internal drivers cause changes in INVs culture, resources, capabilities, strategic management, and output decisions inside the company. Organizational learning and resource acquisition through international business networks explain how INVs are able to cope with the dynamic high-technology industry and be able to adapt. Internationalization of INVs proceeds through several phases, which may be gone through rapidly due to the network effects and INVs’ special characteristics. The results of this research revealed that INVs internal change process proceeds through four phases; pre-incorporation phase, product development phase, internationalization and growth phase, and maturation phase. INVs culture, resources, capabilities, strategic management, and outputs change significantly during initial internationalization, and INVs develop from small start-ups into fully established companies.