24 resultados para escape behavior


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As globalization and capital free movement has increased, so has interest in the effects of that global money flow, especially during financial crises. The concern has been that large global money flows will affect the pricing of small local markets by causing, in particular, overreaction. The purpose of this thesis is to contribute to the body of work concerning short-term under- and overreaction and the short-term effects of foreign investment flow in the small Finnish equity markets. This thesis also compares foreign execution return to domestic execution return. This study’s results indicate that short-term under- and overreaction occurs in domestic-buy portfolios (domestic net buying) rather than in foreign-buy portfolios. This under- and overreaction, however, is not economically meaningful after controlling for the bid-ask bounce effect. Based on this finding, one can conclude that foreign investors do not have a destabilizing effect in the short-term in the Finnish markets. Foreign activity affects short-term returns. When foreign investors are net buyers (sellers) there are positive (negative) market adjusted returns. Literature related to nationality and institutional effect leads us to expect these kind of results. These foreign flows are persistent at a 5 % to 21 % level and the persistence of foreign buy flow is higher than the foreign sell flow. Foreign daily trading execution is worse than domestic execution. Literature which quantifies foreign investors as liquidity demanders and literature related to front-running leads us to expect poorer foreign execution than domestic execution.

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This doctoral thesis is about the solar wind influence on the atmosphere of the planet Venus. A numerical plasma simulation model was developed for the interaction between Venus and the solar wind to study the erosion of charged particles from the Venus upper atmosphere. The developed model is a hybrid simulation where ions are treated as particles and electrons are modelled as a fluid. The simulation was used to study the solar wind induced ion escape from Venus as observed by the European Space Agency's Venus Express and NASA's Pioneer Venus Orbiter spacecraft. Especially, observations made by the ASPERA-4 particle instrument onboard Venus Express were studied. The thesis consists of an introductory part and four peer-reviewed articles published in scientific journals. In the introduction Venus is presented as one of the terrestrial planets in the Solar System and the main findings of the work are discussed within the wider context of planetary physics. Venus is the closest neighbouring planet to the Earth and the most earthlike planet in its size and mass orbiting the Sun. Whereas the atmosphere of the Earth consists mainly of nitrogen and oxygen, Venus has a hot carbon dioxide atmosphere, which is dominated by the greenhouse effect. Venus has all of its water in the atmosphere, which is only a fraction of the Earth's total water supply. Since planets developed presumably in similar conditions in the young Solar System, why Venus and Earth became so different in many respects? One important feature of Venus is that the planet does not have an intrinsic magnetic field. This makes it possible for the solar wind, a continuous stream of charged particles from the Sun, to flow close to Venus and to pick up ions from the planet's upper atmosphere. The strong intrinsic magnetic field of the Earth dominates the terrestrial magnetosphere and deflects the solar wind flow far away from the atmosphere. The region around Venus where the planet's atmosphere interacts with the solar wind is called the plasma environment or the induced magnetosphere. Main findings of the work include new knowledge about the movement of escaping planetary ions in the Venusian induced magnetosphere. Further, the developed simulation model was used to study how the solar wind conditions affect the ion escape from Venus. Especially, the global three-dimensional structure of the Venusian particle and magnetic environment was studied. The results help to interpret spacecraft observations around the planet. Finally, several remaining questions were identified, which could potentially improve our knowledge of the Venus ion escape and guide the future development of planetary plasma simulations.

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The relationship between hosts and parasites is one of the most studied interactions between living organisms, and it is both universal and common in nature. Parasitoids are special type of parasites whose offspring develop attached to or within a single host organism that it ultimately consumes and kills. Hosts are arthropods and most parasitoids belong to the insect order Hymenoptera. For almost two decades metapopulation research on the Glanville fritillary butterfly (Melitaea cinxia) has been conducted in the Åland Islands, Finland. The studies have been concerned with the population dynamics, evolution, genetics, behavior, natural history and life history characteristics of M. cinxia, as well as with species interacting with the butterfly. The parasitoids of M. cinxia have been under long term studies and much has been learned about specific host-parasitoid interactions during the past decade. The research for this Master s thesis was done in the Åland Islands during summer 2010. I conducted a reciprocal transplant style experiment in order to compare the performance of host butterflies (M. cinxia) under attack by different parasitoid wasps (C. melitaearum). I used hosts and parasitoids from five origins around the Baltic Sea: Öland, Uppland, Åland, Saaremaa and Pikku-Tytärsaari. The host-parasitoid relationship was studied in terms of host susceptibility and parasitoid virulence, addressing specifically the possible effects of inbreeding and local adaptation of both parasitoids and their hosts. I compared various factors such as host defence ratio, parasitoid development rate, cocoon production rate etc. I also conducted a small scale C. melitaearum egg development experiment and C. melitaearum external morphology comparison between different parasitoid populations. The results show that host resistance and parasitoid virulence differ between both host and parasitoid populations. For example, Öland hosts were most susceptible to parasitoids and especially vulnerable to Pikku-Tytärsaari wasps. Pikku-Tytärsaari wasps were most successful in terms of parasitoids virulence and efficiency except in Saaremaa hosts, where the wasp did not succeed. Saaremaa hosts were resistant except towards Åland parasitoids. I did not find any simple pattern concerning host resistance and parasitoid virulence between inbred and outbred populations. Also, the effect of local adaptation was not detected, perhaps because metapopulation processes disturb local adaptation of the studied populations. Morphological comparisons showed differences between studied wasp populations and sexual dimorphism was obvious with females being bigger that males. There were also interesting differences among populations in male and female wing shapes. The results raise many further questions. Especially interesting were Pikku-Tytärsaari wasps that did well in terms of efficiency and virulence. Pikku-Tytärsaari is a small, isolated island in the Gulf of Finland and both the host and parasitoids are extremely inbred. For the host and parasitoid to persist in the island, the host has to have some mechanisms to escape the parasitoid. Further research will be done on the subject to discover the mechanisms of Pikku-Tytärsaari host s ability to escape parasitism. Also, genetic analyses will be conducted in the near future to determine the relatedness of used C. melitaearum populations.

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The aim of this study was to investigate powder and tablet behavior at the level of mechanical interactions between single particles. Various aspects of powder packing, mixing, compression, and bond formation were examined with the aid of computer simulations. The packing and mixing simulations were based on spring forces interacting between particles. Packing and breakage simulations included systems in which permanent bonds were formed and broken between particles, based on their interaction strengths. During the process, a new simulation environment based on Newtonian mechanics and elementary interactions between the particles was created, and a new method for evaluating mixing was developed. Powder behavior is a complicated process, and many of its aspects are still unclear. Powders as a whole exhibit some aspects of solids and others of liquids. Therefore, their physics is far from clear. However, using relatively simple models based on particle-particle interaction, many powder properties could be replicated during this work. Simulated packing densities were similar to values reported in the literature. The method developed for describing powder mixing correlated well with previous methods. The new method can be applied to determine mixing in completely homogeneous materials, without dividing them into different components. As such, it can describe the efficiency of the mixing method, regardless of the powder's initial setup. The mixing efficiency at different vibrations was examined, and we found that certain combinations of amplitude, direction, and frequencies resulted in better mixing while using less energy. Simulations using exponential force potentials between particles were able to explain the elementary compression behavior of tablets, and create force distributions that were similar to the pressure distributions reported in the literature. Tablet-breaking simulations resulted in breaking strengths that were similar to measured tablet breaking strengths. In general, many aspects of powder behavior can be explained with mechanical interactions at the particle level, and single particle properties can be reliably linked to powder behavior with accurate simulations.

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International strategic alliances (ISAs) have become increasingly important for the stability, growth, and long-term viability of modern business organizations. Alliance partnerships as inter-firm cooperative ventures represent an influential mechanism for asserting corporate strategic control among autonomous multinational enterprises. These different cooperative arrangements are made of equity investments or contractually-based partnerships. Different alliance forms represent different approaches that partner firms adopt to control their mutual dependence on the alliance and on other partners. Earlier research shows that the partner characteristics could provide an explanation for alliance strategic behavior and see alliances as alternative forms to markets or hierarchies for addressing specific strategic needs linked to partners’ characteristics and their subsequent strategic motives. These characteristics of the partners’ and subsequent strategic motives are analyzed as knowledge sharing factors and how these influence inter-firm control in alliances within the context of the focal-firm STMicroelectronics and its alliance partners Nokia, Ericsson and IBM. This study underline that as contracts are incomplete, they are therefore required to maintain mutual dependence based control mechanisms in addition to a contract. For example, mutual dependence based control mechanisms could be joint financial investments and the building of an ownership structure between the parties (e.g., JVs). However, the present study clarifies that subsequent inter-firm control is also exercised through inter-firm knowledge sharing. The present study contributes by presenting a dynamic interplay between competitive and cooperative rent seeking behavior. Such coopetition behavior describes the firm's strategic orientation to achieve a dynamic balance between competitive and cooperative strategies. This balance is seen in knowledge sharing based cooperation and competition behavior. Thus this study clarifies coopetition strategies by introducing the role of inter-firm cooperation and the competitive nature of knowledge sharing. Simultaneous cooperative and competitive behavior is also seen as synergetic rent-seeking behavior. Therefore, this study extends the perspective of previous studies on competitive and cooperative seeking behavior.