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  • Peura, Einari (1999)
    During the 1970s the United States faced severe setbacks in its ideological battle with the Soviet Union. The U.S. failure to resist communism in Vietnam gave way to the rise of Marxist movements in the Third World. One of the several countries that saw a pro-Soviet regime coming to power during the decade was Nicaragua. Soon after its inauguration, the conservative administration of president Ronald Reagan started to secretly support the anti-Marxist guerrillas (contras) in Nicaragua. Beginning in 1983, the president started bidding the Congress to provide financial aid for the contras. The U.S. support to contras, who hurted innocent civilians in their fight against the basically legitimate government of Nicaragua, raised loud voices of opposition. The U.S. Congress terminated all aid to contras in 1984, but the president launched a high profile public campaign to persuade the public and the Congress. After a very long and intensive public debate, in the summer of 1986, the Congress finally granted a $100 million package of military and humanitarian aid for the contras. In this paper, I present the contra aid debate in the political community of Washington D.C. during the years 1981-1986. My focus is on the media and particularly on the Washington Times newspaper, which was the only major news organization which clearly supported Reagan's Nicaraguan policy. The major part of the thesis consists of a chronological investigation of the administration's contra aid campaign and the Washington Times coverage on the issue. In this thesis I seek to answer the question on how president Reagan managed to win congressional support for his unpopular Nicaraguan policy. A detailed study on the contra aid debate shows that the Washington Times was strongly supporting the president's contra aid campaign, and that it stood in a position where it could influence the opinions in the U.S. congress. Thus the Washington Times significantly contributed to Reagan's victory in the contra aid debate.
  • Liao, Li (Helsingin yliopisto, 2014)
    Atmospheric aerosol particles influence the Earth's climate system, affect air visibility, and harm human health. Aerosol particles originate from both anthropogenic and biogenic sources, either from direct emissions or secondary particle formation. Secondary particle formation from gas phase precursors constitutes the largest fraction of global aerosol budget, yet large uncertainties remain in its mechanisms. This thesis attempted to study the source, the formation mechanisms, and the sink of secondary particles based on data analysis of field measurements and chamber experiments. In addition, numerical simulations were performed to model the processes of secondary particle formation observed in the chamber experiments. We summarized our findings into five main conclusions: 1) Monoterpenes originated from anthropogenic sources (e.g. forest industry) can significantly elevate the local average concentrations and result in a corresponding increase in local aerosol loading; 2) Monoterpenes from biogenic emissions show direct link to secondary particle production: the secondary aerosol masses correlate well with the accumulated monoterpene emissions; 3) Temperature influences biogenic monoterpene emissions, resulting in an indirect effect on the biogenic secondary particle production and corresponding cloud condensation nuclei (CCN) formation; 4) Both data analysis and numerical simulation suggested that nucleation involving the oxidation products of biogenic volatile organic compounds (VOCs) and H2SO4 better explains the nucleation mechanism, yet the specific VOCs participating in the nucleation process remains uncertain; 5) The numerical simulation showed evidence of vapor wall loss effect on the yield of secondary particles from the chamber experiments; a reversible gas-wall partitioning had to be considered to properly capture the observed temporal evolution of particle number size distribution during the chamber experiments. The results of this thesis contribute to the understanding on the role of monoterpenes to secondary particle formation. This thesis raises caution on the parameterization of the temperature dependence of biogenic secondary particle formation in predicting the aerosol production potential due to rising temperatures in the future. This work also points out a way for improving the comprehensive numerical models to better understand the secondary particle formation processes and related climatic effects.
  • Yli-Jyrä, Anssi (Helsingin yliopisto, 2005)
    This dissertation is a theoretical study of finite-state based grammars used in natural language processing. The study is concerned with certain varieties of finite-state intersection grammars (FSIG) whose parsers define regular relations between surface strings and annotated surface strings. The study focuses on the following three aspects of FSIGs: (i) Computational complexity of grammars under limiting parameters In the study, the computational complexity in practical natural language processing is approached through performance-motivated parameters on structural complexity. Each parameter splits some grammars in the Chomsky hierarchy into an infinite set of subset approximations. When the approximations are regular, they seem to fall into the logarithmic-time hierarchyand the dot-depth hierarchy of star-free regular languages. This theoretical result is important and possibly relevant to grammar induction. (ii) Linguistically applicable structural representations Related to the linguistically applicable representations of syntactic entities, the study contains new bracketing schemes that cope with dependency links, left- and right branching, crossing dependencies and spurious ambiguity. New grammar representations that resemble the Chomsky-Schützenberger representation of context-free languages are presented in the study, and they include, in particular, representations for mildly context-sensitive non-projective dependency grammars whose performance-motivated approximations are linear time parseable. (iii) Compilation and simplification of linguistic constraints Efficient compilation methods for certain regular operations such as generalized restriction are presented. These include an elegant algorithm that has already been adopted as the approach in a proprietary finite-state tool. In addition to the compilation methods, an approach to on-the-fly simplifications of finite-state representations for parse forests is sketched. These findings are tightly coupled with each other under the theme of locality. I argue that the findings help us to develop better, linguistically oriented formalisms for finite-state parsing and to develop more efficient parsers for natural language processing. Avainsanat: syntactic parsing, finite-state automata, dependency grammar, first-order logic, linguistic performance, star-free regular approximations, mildly context-sensitive grammars
  • Nuotio, Lasse (Helsingin yliopisto, 2006)
    The monitoring and control of infectious animal diseases, limiting or prevention of their spread and efforts towards their eradication are central tasks of the veterinary civil service. In addition to the cost-effectiveness of prophylaxis over disease and treatment, the animal welfare aspect is also involved. The purpose of this work is to review, describe and assess the available control measures against selected viral infections or diseases of domestic ruminants. The selected infections or diseases are bovine viral diarrhoea / mucosal disease (BVD), infectious bovine rhinotracheitis / infectious pustular vulvovaginitis (IBR), enzootic bovine leukosis (EBL) and maedi-visna (MV) of sheep. Decisive control and eradication measures are necessarily based on the biological, veterinary and diagnostic characteristics of the afflictions, as well as on their epidemiology in terms of the intrinsic determinants of the hosts, host-agent relationships, transmission of the infection and occurrence of these infections or diseases. This information is compiled with special reference to available or possible control and eradication measures, and those employed in major cattle and sheep producing countries are outlined and assessed briefly. The domestic and EU legislation that forms the official framework for disease control and eradication, as well as the official measures and the voluntary programmes are reviewed. The first recorded entries of the occurrence of BVD and EBL in Finland date back to the 1960s, those of IBR to the beginning of the 1970s and of MV to the beginning of the 1980s. Large-scale surveillance and health monitoring among dairy, suckler-cow and beef herds and sheep flocks, starting during the first half of the 1990s, enabled the estimation of actual prevalences of these infections and diseases. The successful eradication of IBR and EBL in 1994 and 1996, respectively, and the significant reduction in the occurrences of BVD and MV from 1990 to date, are reported in detail. The efficacies of the official control and eradication measures and of the voluntary control programmes are analyzed further with a heuristic formulation for the infection reproduction number (R), i.e. the number of secondary cases produced by one infective animal. The influence of the measures is resolved into probability of transmission, frequency of infectious contacts and length of the infectious period, and the impact of the measures on each component is graded on a three-step scale. The conclusion is drawn that the official measures complemented by voluntary actions for control and eradication have for the most part been adequate. In the case of BVD the decisive measures for final eradication have only been available since 2004 and their impact will be seen in the next few years. The role of continued surveillance and health monitoring for both overseeing the situation with BVD and MV, and maintaining an IBR and EBL-free status is emphasized.
  • Kankkunen, Tarja (Helsingin yliopisto, 2002)
  • Ranki, Tuuli (Helsingin yliopisto, 2010)
    Despite progress in conventional cancer treatment regimes, metastatic disease essentially remains incurable and new treatment alternatives are needed. Virotherapy is a relatively novel approach in cancer treatment. It harnesses the natural ability of oncolytic viruses to kill the cells they proliferate in and to spread to neighboring cells, thereby amplifying the therapeutic effect of the initial input dose. The use of replicating, oncolytic viruses for cancer treatment necessitates introduction of various genetic modifications to the viral genome, thereby restraining replication exclusively to tumor cells and eventually obtaining selective eradication of the tumor without side effects to healthy tissue. Furthermore, various modifications can be applied to the viral capsid in hope of gaining effective transduction of target tissue. In other words, the entry of viruses into tumor tissue can be augmented by allowing the virus to utilize non-native receptors for entry. Genetic capsid modifications may also help to avoid some major hurdles in systemic delivery that ultimately lead to the rapid clearance of the virus from the blood and virus induced toxicity. In addition to genetic modifications that alter the phenotype of the virus, some pharmacologic agents may be utilized to enhance the virus entry to target site. Liver kupffer cells (KC) are responsible for the majority of viral clearance after systemic viral delivery and they play a major role in adenovirus induced acute toxicity. The therapeutic window could possibly be widened by transiently depleting KCs, allowing smaller viral input doses and diminishing KC related toxicity. The transductional efficacy of various capsid modified viruses was analyzed in vitro and in vivo in murine orthotopic breast cancer model. The effect of capsid modifications on the oncolytic efficacy, i.e. the ability of the viruses to kill cancer cells, was evaluated in vitro and in vivo in murine cancer models. We concluded that capsid modifications result in transductional enhancement, and that enhanced transduction translates into more potent oncolysis in vitro and in vivo. When KC depleting agents were used in vivo prior to viral injections, enhanced tumor transduction was seen, but this effect was not translated into enhanced antitumor activity. Transcriptional regulation of replicative oncolytic viruses is a prerequisite for virotherapy. Tumor or tissue specific promoters can be used to control the transcription of adenoviral early genes to gain cancer specific viral replication. Specific deletions in viral regions essential for virus replication in normal cells can further increase the safety by allowing viral genome replication in cancer cells featuring specific mutations. Genetically modified viruses were shown to be able to kill putative cancer stem cells that are thought to be responsible for post treatment relapses and metastasis. Further, pharmacologic intervention reduced viral replication and thereby might offer an additional safety switch in case viral replication related side effects are encountered.
  • Pajusto, Mervi (Helsingin yliopisto, 2005)
  • Kuusisto-Hjort, Paula (Helsingin yliopisto, 2009)
    Contamination of urban streams is a rising topic worldwide, but the assessment and investigation of stormwater induced contamination is limited by the high amount of water quality data needed to obtain reliable results. In this study, stream bed sediments were studied to determine their contamination degree and their applicability in monitoring aquatic metal contamination in urban areas. The interpretation of sedimentary metal concentrations is, however, not straightforward, since the concentrations commonly show spatial and temporal variations as a response to natural processes. The variations of and controls on metal concentrations were examined at different scales to increase the understanding of the usefulness of sediment metal concentrations in detecting anthropogenic metal contamination patterns. The acid extractable concentrations of Zn, Cu, Pb and Cd were determined from the surface sediments and water of small streams in the Helsinki Metropolitan region, southern Finland. The data consists of two datasets: sediment samples from 53 sites located in the catchment of the Stream Gräsanoja and sediment and water samples from 67 independent catchments scattered around the metropolitan region. Moreover, the sediment samples were analyzed for their physical and chemical composition (e.g. total organic carbon, clay-%, Al, Li, Fe, Mn) and the speciation of metals (in the dataset of the Stream Gräsanoja). The metal concentrations revealed that the stream sediments were moderately contaminated and caused no immediate threat to the biota. However, at some sites the sediments appeared to be polluted with Cu or Zn. The metal concentrations increased with increasing intensity of urbanization, but site specific factors, such as point sources, were responsible for the occurrence of the highest metal concentrations. The sediment analyses revealed, thus a need for more detailed studies on the processes and factors that cause the hot spot metal concentrations. The sediment composition and metal speciation analyses indicated that organic matter is a very strong indirect control on metal concentrations, and it should be accounted for when studying anthropogenic metal contamination patterns. The fine-scale spatial and temporal variations of metal concentrations were low enough to allow meaningful interpretation of substantial metal concentration differences between sites. Furthermore, the metal concentrations in the stream bed sediments were correlated with the urbanization of the catchment better than the total metal concentrations in the water phase. These results suggest that stream sediments show true potential for wider use in detecting the spatial differences in metal contamination of urban streams. Consequently, using the sediment approach regional estimates of the stormwater related metal contamination could be obtained fairly cost-effectively, and the stability and reliability of results would be higher compared to analyses of single water samples. Nevertheless, water samples are essential in analysing the dissolved concentrations of metals, momentary discharges from point sources in particular.
  • Nummelin, Aleksi (Helsingin yliopisto, 2012)
    The Meridional overturning circulation (MOC) is one crucial component in Earth's climate system, redistributing heat round the globe. The abyssal limb of the MOC is fed by the deep water formation near the poles. A basic requirement for any successful climate model simulation is the ability to reproduce this circulation correctly. The deep water formation itself, convection, occurs on smaller scales than the climate model grid size. Therefore the convection process needs to be parameterized. It is, however, somewhat unclear how well the parameterizations which are developed for turbulence can reproduce the deep convection and associated water mass transformations. The convection in the Greenland Sea was studied with 1-D turbulence model GOTM and with data from three Argo floats. The model was run over the winter 2010-2011 with ERA-Interim and NCEP/NCAR atmospheric forcings and with three different mixing parameterizations, k-e, k-kL (Mellor-Yamada) and KPP. Furthermore, the effects of mesoscale spatial variations in the atmospheric forcing data were tested by running the model with forcings taken along the floats' paths (Lagrangian approach) and from the floats' median locations (Eulerian approach). The convection was found to happen by gradual mixed layer deepening. It caused salinity decrease in the Recirculating Atlantic Water (RAW) layer just below the surface while in the deeper layers salinity and density increase was clearly visible. A slight temperature decrease was observed in whole water column above the convection depth. Atmospheric forcing had the strongest effect on the model results. ERA-interim forcing produced model output closer to the observations, but the convection begun too early with both forcings and both generated too low temperatures in the end. The salinity increase at mid-depths was controlled mainly by the RAW layer, but also atmospheric freshwater flux was found to affect the end result. Furthermore, NCEP/NCAR freshwater flux was found to be large enough (negative) to become a clear secondary driving factor for the convection. The results show that mixing parameterization mainly alters the timing of convection. KPP parameterization produced clearly too fast convection while k-e parameterization produced output which was closest to the observations. The results using Lagrangian and Eulerian approaches were ambiguous in the sense that neither of them was systematically closer to the observations. This could be explained by the errors in the reanalyzes arising from their grid size. More conclusive results could be produced with the aid of finer scale atmospheric data. The results, however, clearly indicate that atmospheric variability in scales of 100 km produces quantifiable differences in the results.
  • Koivistoinen, Sari (2006)
    This thesis concentrates on a concept of convergence, and thus it examines whether reduction of disparities between poor and rich countries is taking place and what are the most important factors contributing to such process. The main focus is on a group of more homogenous countries, namely the countries of the European Union due to its ongoing process of convergence and enlargement. Besides the theoretical analysis on convergence, some empirical evidence and analysis of whether trade liberalization has enhanced the convergence process is presented. The thesis discusses the enlargement of the EU and its effects on convergence, but also the history of convergence within the European countries. Sigma-convergence within the enlarged EU area has taken place during the examination period of 1993-2004, and therefore income disparities between countries appear to be declining. When analysing beta-convergence during the period, a negative relationship between the initial level of GDP per capita and its average growth rate can be found. As predicted by the neoclassical theory of convergence, the EU-10 countries are among the initially poorest and fastest growing countries, and the EU-15 countries have a slower growth rate. According to the estimation, the countries of the European Union converge in an absolute sense at a speed of 2.1 % per year. The results indicate that the expected duration of the convergence process must be measured in decades. When examining the relationship between sigma-convergence and economic integration, the liberalisation of trade was found to have an impact on convergence within the EEC. Also among the EU-15 is found evidence for that mutual trade is rather good indicator of sigma-convergence. As for the new member states of the EU, there is a positive relationship between the volume of trade and the degree of openness. Trade between the EU-25 countries has accelerated, which exhibits a propensity towards convergence. The most important references used are Barro, Robert J. and Sala-I-Martin, Xavier (1995), Sala-I-Martin, Xavier (1996) and Kaitila, Ville (2004) for the concept of convergence, Economic and Social Data Service dataset for empirical evidence, and Ben-David, Dan and Kimhi, Ayal (2004) for the relationship between trade and convergence.
  • Koivistoinen, Sari (2006)
    Tutkielmassa keskitytään konvergenssin käsitteeseen, ja tarkastellaan vähenevätkö rikkaiden ja köyhien maiden väliset tuloerot sekä mitkä ovat tärkeimmät siihen vaikuttavat tekijät. Pääpaino tarkastelussa on Euroopan Unionin mailla, ja viimeisimmän laajenemisen vaikutuksilla ryhmään homogeenisempia talouksia. Teoreettisen analyysin lisäksi esitellään empiirisiä havaintoja ja tarkastellaan sitä, onko maiden välinen kaupan vapauttaminen edesauttanut konvergenssia. Tutkielma käsittelee EU:n laajenemisen vaikutuksia konvergenssiin, mutta tarkastelee myös Euroopan maiden välistä konvergenssin historiaa. Vuosien 1993–2004 välisenä aikana EU-maiden sisällä on tapahtunut sigma-konvergenssia, joten tuloerot maiden välillä ovat kaventuneet. Beta-konvergenssia analysoitaessa saman ajanjakson aikana on löydettävissä negatiivinen suhde henkeä kohden mitatun BKT:n alkuperäisen arvon ja maiden keskimääräisen kasvuvauhdin välillä. Kuten uusklassinen teoria konvergenssista olettaakin, EU10-maat ovat nopeimmin kasvavien ja alkutilanteessa köyhimpien maiden joukossa, kun taas EU15-maiden kasvuvauhti on hitaampi. Estimoinnin perusteella EU-maat konvergoituvat absoluuttisella beta-konvergenssilla mitattuna 2,1 %:n vuosivauhtia. Tämä osoittaa, että konvergenssiprosessi tulee kestämään vuosikymmenien ajan. Tutkittaessa sigma-konvergenssin ja taloudellisen integraation välistä yhteyttä, kaupan liberalisoinnilla on havaittu olevan vaikutusta konvergenssiin EEC-maiden sisällä. Myös EU15-maiden välisellä kaupankäynnillä on havaittu olevan yhteyttä maiden välisten tuloerojen kanssa. Kun tarkastellaan EU:n viimeaikaisinta laajenemista, voidaan havaita positiivinen suhde kaupankäynnin volyymin ja maiden avoimuuden välillä. Kaupankäynti EU25 maiden välillä on vuosikymmenen aikana lisääntynyt, mikä lisää taipumusta konvergenssiin. Tärkeimmät käytetyt lähteet ovat Barro, Robert J. ja Sala-I-Martin, Xavier (1995), Sala-I-Martin, Xavier (1996) ja Kaitila, Ville (2004) tutkittaessa konvergenssin käsitettä, Economic and Social Data Service dataset empiiristen havaintojen pohjana, sekä Ben-David, Dan ja Kimhi, Ayal (2004) tutkittaessa kaupan ja konvergenssin välistä suhdetta.
  • Nisén, Pia (Helsingfors universitet, 2014)
    This study focuses on understanding the relationship between organic wine production and economic performance. The aim of this study is to clarify, what are the economic impacts that result from the conversion of wine production from conventional to organic. This is an interesting topic to be explored in more detail because despite the increasing demand of organic wine and share of vineyard area used for organic winemaking, the economic consequences of the conversion are still somewhat unclear. Understanding the economic impacts of the conversion process is very important for wine producers from an economic perspective and contributes to an up-to-date picture of the organic wine industry´s economic performance also for the scientific field. The theoretical framework of the study was built in order to investigate the relationship between environmental responsibility and economic performance. The environmental impacts of organic wine production have so far not been scientifically proved but the organic production is widely viewed as an environmentally sustainable way of producing wine. The theoretical review showed that environmentally responsible production may cause both direct cost impacts and also indirect cost and revenue impacts on the economy. Moreover, the net impact creates the final economic performance and influences the success of a company. The study is based on an empirical approach focusing on understanding an economic phenomenon in its real-life context. The data is collected from representatives of organic wine estates from different parts of the world, who have experience of the conversion from conventional to organic wine production. The empirical study was implemented during fall 2012 in two parts. The first dataset was collected through a survey sent via e-mail and the second dataset was through interviews that were organized in one of the studied estates. Both parts of the data collection were based on a qualitative semi-structured questionnaire. The questionnaire consisted of five sections, which all together covered four themes: vineyard, cellar, wine and business aspects. To accomplish the objectives of the study, first the focus was to understand the impacts of the conversion of production from conventional to organic on a wine estate in general. After this the impacts were categorized according to economic performance. The changes were classified into positive and negative cost and revenue impacts by using the existing theoretical knowledge about how environmental responsibility may affect a company´s economic performance. The findings indicated that most of the cost impacts, positive as well as negative, occurred in the early parts of the production chain, in vineyard and cellar procedures. The strongest cost increase was observed in the vineyard production processes, and slightly decreasing level of cost occurred in cellar production process. Varying revenue impacts were naturally indicated more frequently in later procedures, in wine and business themes. In overall, cost effects were considered both negative and positive, but the revenue impacts were mainly positive. Moreover, the cost impacts where more obvious, especially in the vineyard processes, than the changes that had impacts on revenue. Still any significant conclusions about net economic performance cannot be drawn because the findings do not offer any exact information on the magnitude of these impacts and the sample size is rather small. In general, the findings of this study seem to be consistent with other studies. This study was, however, able to offer more detailed information on the economic impacts of the conversion process than previous studies. In general, the representatives considered the organic wine business to have much positive potential, yet benefiting from the potential in economic term was little. The organic market is currently developing and growing faster than the conventional wine market, which creates a possibility to find new customers and increase the marketing channels. Still clear differentiation strategy that would potentially allow premium pricing and bring new customer segments was in use by only minority of the estates. Previous studies indicated that certification has an important role in organic wine marketing as well as in ensuring sustainable competition in the markets. Furthermore, organic wine production is a more risky business than the conventional one, and therefore developing insurance arrangements might be a useful mechanism for balancing the risks and an important factor in encouraging new estates to acquire certificates.
  • Verkasalo, Hannu (2006)
    The problem of double moral hazard is prevalent in venture capital financing. This рrоblem refers to the fact that there are two agents who can affect the value of an entrepreneurial project. First, an entrepreneur's effort is needed. Second, also the outside advising or management support exerted by a specialized venture capitalist can contribute to the project value. Because either of these agents can make private choices and not to exert a socially efficient level of effort, we call the problem of moral hazard in this special case of venture capital as a double-sided one. There are common characteristics in venture capital, such as the active participation of outside venture capital investors in the management of the company and the use of convertible securities in venture capital contracting, on which we have a lot of empirical evidence, and which relate to the рrоblem of douse-sided moral hazard. The purpose of the study is to present two analytical models which discuss the рrоblem of double-sided moral hazard and the remedies to overcome it. The key challenge is to mathematically present the рrоblem of double-sided moral hazard, and to study how convertibles could implement efficient contracts in venture capital. MODELS The thesis introduces two different models in venture capital financing. Catherine Casamatta's model is introduced first. Casamatta's model assumes that the efforts are allocated simultaneously. Casamatta's model sets out to study how outside financing and advising arise endogenously in the model, and how optimal contracts can be implemented under certain conditions through the use of convertibles. Klaus Schmidt's model is introduced next. Schmidt's model takes a more focused look at the use of convertibles, assuming that the efforts are allocated sequentially. RESULTS Both models show how efficient contracts can be implemented through the use of convertibles. In Casamatta's model we reach optimal second-best outcomes assuming a simultaneous nature of allocating effort. Casamatta also shows that it is not efficient to include outside financers, if they cannot provide complementary effort which contributes to the project value. Also, convertible securities should only be used by investors who have significant financing roles (i.e. venture capitalists, not business angels). Schmidt shows that convertibles can induce first-best levels of effort, if we allow for sequential nature of allocating effort. The role of convertibles is important.
  • Talponen, Jarno (Helsingin yliopisto, 2008)
    The topic of this dissertation is the geometric and isometric theory of Banach spaces. This work is motivated by the known Banach-Mazur rotation problem, which asks whether each transitive separable Banach space is isometrically a Hilbert space. A Banach space X is said to be transitive if the isometry group of X acts transitively on the unit sphere of X. In fact, some weaker symmetry conditions than transitivity are studied in the dissertation. One such condition is an almost isometric version of transitivity. Another investigated condition is convex-transitivity, which requires that the closed convex hull of the orbit of any point of the unit sphere under the rotation group is the whole unit ball. Following the tradition developed around the rotation problem, some contemporary problems are studied. Namely, we attempt to characterize Hilbert spaces by using convex-transitivity together with the existence of a 1-dimensional bicontractive projection on the space, and some mild geometric assumptions. The convex-transitivity of some vector-valued function spaces is studied as well. The thesis also touches convex-transitivity of Banach lattices and resembling geometric cases.
  • Jaatinen, Kim (Helsingin yliopisto, 2009)
    Interactions among individuals give rise to both cooperation and conflict. Individuals will behave selfishly or altruistically depending on which gives the higher payoff. The reproductive strategies of many animals are flexible and several alternative tactics may be present from which the most suitable one is applied. Generally, alternative reproductive tactics may be defined as a response to competition from individuals of the same sex. These alternative reproductive tactics are means by which individuals may fine-tune their fitness to the reigning circumstances and which are shaped by the environment individuals are occupying as well as by the behaviour of other individuals sharing the environment. By employing such alternative ways of achieving reproductive output, individuals may alleviate competition from others. Conspecific brood parasitism (CBP) is an alternative reproductive strategy found in several egg laying animal groups, and it is especially common among waterfowl. Within this alternative reproductive strategy, four reproductive options can be identified. These four options represent a continuum from low reproductive effort coupled with low fitness returns, to high reproductive effort and consequently high benefits. It may not be evident how individuals should allocate reproductive effort between eggs laid in their own nest vs. in nests of others, however. Limited fecundity will constrain the number of eggs donated by a parasite, but also the tendency for hosts to accept parasitic eggs may affect the allocation decision. Furthermore, kinship, individual quality and the costs of breeding may play a role in complicating the allocation decision. In this thesis, I view the seemingly paradoxical effects of kinship on conflict resolution in the context of alternative reproductive tactics, examining the resulting features of cooperation and conflict. Conspecific brood parasitism sets the stage for investigating these questions. By using both empirical and theoretical approaches, I examine the nature of CBP in a brood parasitic duck, the Barrow's goldeneye (Bucephala islandica). The theoretical chapter of this thesis gives rise to four main conclusions. Firstly, variation in individual quality plays a central role in shaping breeding strategies. Secondly, kinship plays a central role in the evolution of CBP. Thirdly, egg recognition ability may affect the prevalence of parasitism. If egg recognition is perfect, higher relatedness between host and parasite facilitates CBP. Finally, I show that the relative costs of egg laying and post-laying care play a so far underestimated role in determining the prevalence of parasitism. The costs of breeding may outweigh possible inclusive fitness benefits accrued from receiving eggs from relatives. Several of the patterns brought out by the theoretical work are then confirmed empirically in the following chapters. Findings include confirmation of the central role of relatedness in determining the extent of parasitism as well as inducing a counterintuitive host clutch reduction. Furthermore, I demonstrate a cost of CBP inflicted on hosts, as well as results suggesting that host age reflects individual quality, affecting the ability to overcome costs inflicted by CBP. In summary, I demonstrate both theoretically and empirically the presence of cooperation and conflict in the interactions between conspecific parasites and their hosts. The field of CBP research has traditionally been divided, but the first steps have now been taken toward the acceptance of the opposite side of the divide. Especially the theoretical findings of chapter 1 offer the possibility to view seemingly contrasting results of various studies within the same framework, and may direct future research toward more general features underlying differences in the patterns of CBP between populations or species.
  • Iho, Satu (2010)
    This thesis studies the evolution of conditional cooperation in a population where social norms are present. The model of Spichtig and Traxler (2007) is based in a public good setting where the members can choose to cooperate, contribute to the public good and adhere to the social norm or free-ride, not contribute towards the public good and thus break the social norm. Norm breaking sanctions imposed on any individual who chooses to behave in the latter manner. The exact degree of these norm sanctions on an individual's utility is determined by her individual norm sensitivity level, due to which some agents with a high norm sensitivity experience a higher utility loss from the norm sanctions in comparison with agents a lower degree of norm sensitivity. The model predicts for the population to evolve towards two equilibrium states which are characterised by a differing fraction of free-riders of the entire population. Two distinct models on learning are used to analyse further the learning mechanisms that might take place in such a population on an individual level. The model of Ellison and Fudenberg (1993) and the model of Banerjee and Fudenberg (2004) are similar in that they study a learning process of an individual in terms of new technology adoption. The former concentrates on horizontal learning which takes place within one generation and is based on mere observational clues whereas the latter analyses vertical learning taking place between generations and is based on more comlex word-of-mouth clues that are exchanged between members in the population and new entrants. Both of these models thereby us external clues as the means of learning of agents but differ in terms of what kind of learning is studied, intra-generational or inter-generational. The circumstances in and assumptions under which learning takes place in these two models are found to fit the model of the evolution of cooperation rather well and they could predict the learning mechanisms of this model in an individual level rather well.
  • Sugiyama, Nami (Helsingin yliopisto, 2013)
    Cancer metastasis is a stepwise process of cancer cell dissemination from a primary tumour into adjacent and distant tissues and causes around 90 % of cancer-associated mortality. Metastatic cancer dissemination is initiated and promoted by intracellular and intercellular signalling within tumour microenvironment. Extracellular matrix (ECM) degradation also promotes cancer cell invasion and metastasis in many types of cancer. Membrane type-1 matrix metalloproteinase (MT1-MMP) degrades variety of ECM components and cell surface proteins as well as modulates numerous intracellular signalling pathways to regulate cancer invasion. The molecular mechanisms of pro-invasive MT1-MMP activities are getting more attention to reveal cancer-associated cooperative signalling, which will aid in planning more efficient and effective therapeutic interventions for patients with cancer. In the current studies, we performed a genome-wide gain-of-function human kinome screen to identify cancer-associated upstream and co-operating signalling for MT1-MMP activities. We identified both known and novel positive regulators of MT1-MMP. Among the novel MT1-MMP regulators we focused on the functions of two receptor tyrosine kinases, namely fibroblast growth factor receptor 4 (FGFR4) and Eph receptor type A2 (EphA2) in cancer cell invasion. Overexpression and aberrant signalling of these kinases are linked to aggressive cancer progression and anti-cancer drug resistance. A single nucleotide polymorphism (SNP) of FGFR4 (G388R) associated with poor cancer prognosis was identified as a positive regulator of MT1-MMP activity. We revealed that the complexes of MT1-MMP and FGFR4-R388 risk variant stabilised and activated both MT1-MMP and FGFR4 proteins, resulting in enhancing FGF signalling and pericellular proteolytic activities of MT1-MMP. The FGFR4-R388-MT1-MMP axis induced epithelial-to-mesenchymal transition, promoting prostate carcinoma cell invasion and invasive growth within collagen matrix and in mouse xenograft models. In contrast, the FGFR4-G388 variant and MT1-MMP down-regulated each other. EphA2 was co-expressed with MT1-MMP in invasive breast carcinoma cells, where EphA2 signalling increased MT1-MMP transcription. MT1-MMP in turn cleaved EphA2 in protein complexes on the same cell-surface. This cleavage coupled with EphA2-dependent Src activation triggered intracellular EphA2 translocation and an increase in RhoA activity, leading to actomyosine contraction, cell-cell repulsion, and cell junction disassembly. These signalling events ultimately induced cell invasion phenotype transition from collective to single-cell within three-dimensional collagen matrix and in vivo. Taken together, these studies identified the FGFR4-R388 variant and EphA2 as novel co-operators for pro-invasive MT1-MMP activities in cancer invasion. FGFR4 genetic background affects the activity of an FGFR4-MT1-MMP complex in cancer progression, and an EphA2-MT1-MMP axis regulates cancer invasion plasticity. These findings provide novel insights into the cooperative molecular basis of pro-invasive capabilities of MT1-MMP and FGF and EphA2 signalling in cancer cell invasion.