Features of the geomagnetic field during the Holocene and Proterozoic

The geomagnetic field is one of the most fundamental geophysical properties of the Earth and has significantly contributed to our understanding of the internal structure of the Earth and its evolution. Paleomagnetic and paleointensity data have been crucial in shaping concepts like continental drift, magnetic reversals, as well as estimating the time when the Earth's core and associated geodynamo processes begun. The work of this dissertation is based on reliable Proterozoic and Holocene geomagnetic field intensity data obtained from rocks and archeological artifacts. New archeomagnetic field intensity results are presented for Finland, Estonia, Bulgaria, Italy and Switzerland. The data were obtained using sophisticated laboratory setups as well as various reliability checks and corrections. Inter-laboratory comparisons between three laboratories (Helsinki, Sofia and Liverpool) were performed in order to check the reliability of different paleointensity methods. The new intensity results fill up considerable gaps in the master curves for each region investigated. In order to interpret the paleointensity data of the Holocene period, a novel and user-friendly database (GEOMAGIA50) was constructed. This provided a new tool to independently test the reliability of various techniques and materials used in paleointensity determinations. The results show that archeological artifacts, if well fired, are the most suitable materials. Also lavas yield reliable paleointensity results, although they appear more scattered. This study also shows that reliable estimates are obtained using the Thellier methodology (and its modifications) with reliability checks. Global paleointensity curves during Paleozoic and Proterozoic have several time gaps with few or no intensity data. To define the global intensity behavior of the Earth's magnetic field during these times new rock types (meteorite impact rocks) were investigated. Two case histories are presented. The Ilyinets (Ukraine) impact melt rocks yielded a reliable paleointensity value at 440 Ma (Silurian), whereas the results from J��nisj��rvi impact melts (Russian Karelia, ca. 700 Ma) might be biased towards high intensity values because of non-ideal magnetic mineralogy. The features of the geomagnetic field at 1.1 Ga are not well defined due to problems related to reversal asymmetries observed in Keweenawan data of the Lake Superior region. In this work new paleomagnetic, paleosecular variation and paleointensity results are reported from coeval diabases from Central Arizona and help understanding the asymmetry. The results confirm the earlier preliminary observations that the asymmetry is larger in Arizona than in Lake Superior area. Two of the mechanisms proposed to explain the asymmetry remain plausible: the plate motion and the non-dipole influence.

Experiments on homogeneous nucleation and physicochemical properties related to atmospheric new particle formation

Aerosol particles play a role in the earth ecosystem and affect human health. A significant pathway of producing aerosol particles in the atmosphere is new particle formation, where condensable vapours nucleate and these newly formed clusters grow by condensation and coagulation. However, this phenomenon is still not fully understood. This thesis brings an insight to new particle formation from an experimental point of view. Laboratory experiments were conducted both on the nucleation process and physicochemical properties related to new particle formation. Nucleation rate measurements are used to test nucleation theories. These theories, in turn, are used to predict nucleation rates in atmospheric conditions. However, the nucleation rate measurements have proven quite difficult to conduct, as different devices can yield nucleation rates with differences of several orders of magnitude for the same substances. In this thesis, work has been done to have a greater understanding in nucleation measurements, especially those conducted in a laminar flow diffusion chamber. Systematic studies of nucleation were also made for future verification of nucleation theories. Surface tensions and densities of substances related to atmospheric new particle formation were measured. Ternary sulphuric acid + ammonia + water is a proposed candidate to participate in atmospheric nucleation. Surface tensions of an alternative candidate to nucleate in boreal forest areas, sulphuric acid + dimethylamine + water, were also measured. Binary compounds, consisting of organic acids + water are possible candidates to participate in the early growth of freshly nucleated particles. All the measured surface tensions and densities were fitted with equations, thermodynamically consistent if possible, to be easily applied to atmospheric model calculations of nucleation and subsequent evolution of particle size.

Sticking and erosion at carbon-containing plasma-facing materials in fusion reactors

Controlled nuclear fusion is one of the most promising sources of energy for the future. Before this goal can be achieved, one must be able to control the enormous energy densities which are present in the core plasma in a fusion reactor. In order to be able to predict the evolution and thereby the lifetime of different plasma facing materials under reactor-relevant conditions, the interaction of atoms and molecules with plasma first wall surfaces have to be studied in detail. In this thesis, the fundamental sticking and erosion processes of carbon-based materials, the nature of hydrocarbon species released from plasma-facing surfaces, and the evolution of the components under cumulative bombardment by atoms and molecules have been investigated by means of molecular dynamics simulations using both analytic potentials and a semi-empirical tight-binding method. The sticking cross-section of CH3 radicals at unsaturated carbon sites at diamond (111) surfaces is observed to decrease with increasing angle of incidence, a dependence which can be described by a simple geometrical model. The simulations furthermore show the sticking cross-section of CH3 radicals to be strongly dependent on the local neighborhood of the unsaturated carbon site. The erosion of amorphous hydrogenated carbon surfaces by helium, neon, and argon ions in combination with hydrogen at energies ranging from 2 to 10 eV is studied using both non-cumulative and cumulative bombardment simulations. The results show no significant differences between sputtering yields obtained from bombardment simulations with different noble gas ions. The final simulation cells from the 5 and 10 eV ion bombardment simulations, however, show marked differences in surface morphology. In further simulations the behavior of amorphous hydrogenated carbon surfaces under bombardment with D^+, D^+2, and D^+3 ions in the energy range from 2 to 30 eV has been investigated. The total chemical sputtering yields indicate that molecular projectiles lead to larger sputtering yields than atomic projectiles. Finally, the effect of hydrogen ion bombardment of both crystalline and amorphous tungsten carbide surfaces is studied. Prolonged bombardment is found to lead to the formation of an amorphous tungsten carbide layer, regardless of the initial structure of the sample. In agreement with experiment, preferential sputtering of carbon is observed in both the cumulative and non-cumulative simulations

Trade Liberalization, Heterogeneous Firms and Industrial Dynamics

This master thesis studies how trade liberalization affects the firm-level productivity and industrial evolution. To do so, I built a dynamic model that considers firm-level productivity as endogenous to investigate the influence of trade on firm���s productivity and the market structure. In the framework, heterogeneous firms in the same industry operate differently in equilibrium. Specifically, firms are ex ante identical but heterogeneity arises as an equilibrium outcome. Under the setting of monopolistic competition, this type of model yields an industry that is represented not by a steady-state outcome, but by an evolution that rely on the decisions made by individual firms. I prove that trade liberalization has a general positive impact on technological adoption rates and hence increases the firm-level productivity. Besides, this endogenous technology adoption model also captures the stylized facts: exporting firms are larger and more productive than their non-exporting counterparts in the same sector. I assume that the number of firms is endogenous, since, according to the empirical literature, the industrial evolution shows considerably different patterns across countries; some industries experience large scale of firms��� exit in the period of contracting market shares, while some industries display relative stable number of firms or gradually increase quantities. The special word ���shakeout��� is used to describe the dramatic decrease in the number of firms. In order to explain the causes of shakeout, I construct a model where forward-looking firms decide to enter and exit the market on the basis of their state of technology. In equilibrium, firms choose different dates to adopt innovation which generate a gradual diffusion process. It is exactly this gradual diffusion process that generates the rapid, large-scale exit phenomenon. Specifically, it demonstrates that there is a positive feedback between firm���s exit and adoption, the reduction in the number of firms increases the incentives for remaining firms to adopt innovation. Therefore, in the setting of complete information, this model not only generates a shakeout but also captures the stability of an industry. However, the solely national view of industrial evolution neglects the importance of international trade in determining the shape of market structure. In particular, I show that the higher trade barriers lead to more fragile markets, encouraging the over-entry in the initial stage of industry life cycle and raising the probability of a shakeout. Therefore, more liberalized trade generates more stable market structure from both national and international viewpoints. The main references are Ederington and McCalman(2008,2009).

On the force potential of strategy texts: a critical discourse analysis of a strategic plan and its power effects in a city organization

Despite increasing interest in the discursive aspects of strategy, few studies have examined strategy texts and their power effects. We draw from Critical Discourse Analysis to better understand the power of strategic plans as a directive genre. In our empirical analysis, we examined the creation of the official strategic plan of the City of Lahti in Finland. As a result of our inductive analysis, we identified five central discursive features of this plan: self-authorization, special terminology, discursive innovation, forced consensus and deonticity. We argue that these features can, with due caution, be generalized and conceived as distinctive features of the strategy genre. We maintain that these discursive features are not trivial characteristics; they have important implications for the textual agency of strategic plans, their performative effects, impact on power relations and ideological implications.

Poetics of the Nameless Middle : Japan and the West in Philosophy and Music of the Twentieth Century

This study investigates the affinities between philosophy, aesthetics, and music of Japan and the West. The research is based on the structuralist notion (specifically, on that found in the narratology of Algirdas Julius Greimas), that the universal grammar functions as an abstract principle, underlying all kinds of discourse. The study thus aims to demonstrate how this grammar is manifested in philosophical, aesthetic, and musical texts and how the semiotic homogeneity of these texts can be explained on this basis. Totality and belongingness are the key philosophical concepts presented herein. As distinct from logocentrism manifested as substantializations of the world of ideas , god or mind, which was characteristic of previous Western paradigms, totality was defined as the coexistence of opposites. Thus Heidegger, Merleau-Ponty, D��gen, and Nishida often illustrated it by identifying fundamental polarities, such as being and nothing, seer and seen, truth and illusion, etc. Accordingly, totality was schematically presented as an all-encompassing middle of the semiotic square. Similar values can be found in aesthetics and arts. Instead of dialectic syntagms, differentiated unity is considered as paradigmatic and the study demonstrates how this is manifested in traditional Japanese and Heideggerian aesthetics, as well as in the aspects of music of Claude Debussy and T��ru Takemitsu.

Trade Blocs and the Cold War : The CMEA and the EC challenge, 1969-1976

The coherence of the Soviet bloc was seriously tested at the turn of the 1970s, as the Soviet Union and its allies engaged in intensive negotiations over their relations with the European Communities (EC). In an effort to secure their own national economic interests many East European countries began independent manoeuvres against the wishes of their bloc leader. However, much of the intra-bloc controversy was kept out of the public eye, as the battle largely took place behind the scenes, within the organisation for economic cooperation, the Council for Mutual Economic Assistance (CMEA). The CMEA policy-making process vis-��-vis the EC is described in this study with reference to primary archival materials. This study investigates the negotiating positions and powers of the CMEA member states in their efforts to deal with the economic challenge created by the progress of the EC, as it advanced towards the customs union. This entails an analysis of the functioning principles and performance of the CMEA machinery. The study traces the CMEA negotiations that began in 1970 over its policy toward the EC. The policy was finally adopted in 1974, and was followed by the first official meeting between the two organisations in early 1975. The story ends in 1976, when the CMEA s efforts to enter into working relations with the EC were seemingly frustrated by the latter. The first major finding of the study is that, contrary to much of the prior research, the Soviet Union was not in a hegemonic position vis-��-vis its allies. It had to use a lot of its resources to tame the independent manoeuvring of its smaller allies. Thus, the USSR was not the kind of bloc leader that the totalitarian literature has described. Because the Soviet Union had to spend so much attention on its own bloc-politics, it was not able to concentrate on formulating a policy vis-��-vis the EC. Thus, the Soviet leadership was dependent on its allies in those instances when the socialist countries needed to act as a bloc. This consequently opened up the possibility for the USSR s allies to manoeuvre. This study also argues that when the CMEA did manage to find a united position, it was a force that the EC had to reckon with in its policy-making. This was particularly the case in the implementation of the EC Common Commercial Policy. The other main finding of the study is that, although it has been largely neglected in the previous literature on the history of West European integration, the CMEA did in fact have an effect on EC decision-making. This study shows how for political and ideological reasons the CMEA members did not acknowledge the EC s supranational authority. Therefore the EC had no choice but to refrain from implementing its Common Commercial Policy in full.