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  • Venäläinen, Perttu (2023)
    Finnish school choice policy is primarily an urban phenomenon. In practice, it is only possible in a few municipalities that have sufficient infrastructure for school markets. The municipalities in the capital region in particular face challenges of growing segregation manifested in socio-economic disparities, residential areas, and schools. The municipalities in the capital region have ended up with very different solutions when evaluating the most suitable school choice environment for their respective municipalities. One significant recent factor in shaping the current state of Finnish school choice policy is the Basic Education Act of 1999, which has partly enabled the development of various school choice environments between municipalities. The focus of the study is on the types of solutions that have been made in the municipalities of the capital region regarding the school choice environment, the desired future of the school choice environment in the municipalities, and how these goals are justified. For my Master's thesis, I used interview data collected in the School Markets and Segregation - The Societal Cost of School Choice research project. The data is the most recent interview material available, and it includes interviews with educational policy actors in the capital region. A total of nine educational policy actors from the capital region were interviewed for the study. Of the interviewees, three hold senior positions in metropolitan municipalities, three are in administrative positions in different municipalities, and three are members of municipal education boards. In analyzing the interview data, I employed two concepts by Kenneth Burke: "the Idea of the Negative" and the "Dramatistic Pentad" as analytical tools. Overall, the school choice environments in the examined municipalities differed from each other, and the current school choice environment seemed to be linked to the desired future school choice environments in the municipalities. The new frameworks for school choice environments formulated by the interviewees in the interview data varied to some extent based on the current school choice environment in the municipalities. The new frameworks for school choice environments outlined by the municipalities differed from each other. However, despite the current frameworks for school choice environments, there were a few common aspects that connected all municipalities regarding the new frameworks as well. None of the municipalities desired the public disclosure of school-specific learning outcomes or a completely unrestricted and unregulated new school choice environment.
  • Lajunen, Anna (2016)
    The aim of this thesis was to define optimal packaging conditions for four fresh ready-to-cook and pre-cut vegetable mixes. The packaging conditions consisted of perforated and non-perforated film which were investigated in two different gas mixtures. One of the gas mixtures consisted of modified atmosphere which was chosen in advance and the other gas mixture consisted of normal atmosphere. The literature study focused on the negative influences of processing methods on the physiological properties of vegetables. The main principles of packaging solutions by which negative influences of fresh-cut produce could be minimized with were also mentioned. The main target of the experimental study was to examine if perforated films could be used for avoiding of in-package anaerobic respiration which is a common reason for vegetable spoilage. The respiration rates of the products were measured and with the results an optimally perforated film was defined for each product. The gas concentrations were measured electronically and the quality of the products were evaluated with sensory evaluations and microbiological determinations. Electronically measured gas concentrations were verified gas chromatographically and also the water vapour transmission properties of the films were studied. With perforated film and modified atmosphere gas concentrations remained most constant and they were mainly held in aerobic respiration level. With other packaging solutions very low oxygen levels and very high carbon dioxide levels were observed which was also noticed in the sensory evaluations where off-odours and off-flavours were discovered. With perforated film and modified atmosphere the growth of yeasts, molds and bacteria was smaller than with perforated film and normal atmosphere. The verification of the gas measurements was successful and gas concentrations which were measured both electronically and gas chromatographically were on the same range though minor differences in the accuracy of the results were discovered. The most optimal packaging solution for tested products was achieved with perforated film and modified atmosphere.
  • Pulsa, Veikka (2023)
    The scholarship allotment problem describes the goal of strategically offering scholarships to prospective students of a university in a way that optimises the expected return for that investment. The goal of this thesis is to formulate the scholarship allotment problem in multiple variations of increasing complexity while also introducing algorithms to solve those variations optimally as efficiently as possible. The thesis also offers some insight into the way more complex variations and generalisations heighten the difficulty of finding an optimal solution in a reasonable amount of time. The main focus and the main tool used to tackle these problems is the classic knapsack algorithm and different variations of it, like multiple-choice knapsack and multidimensional knapsack. In addition to the theoretical side, the thesis contains an empirical study into the performance and feasibility of the algorithms introduced. Concrete implementations of the algorithms discussed are all available on a public GitHub repository online: https://github.com/SirVeggie/scholarship-allotment.
  • Assmuth, Aino (2015)
    This study applies two novel forest economic models to analyze the effect of optimal carbon storage on the choice between clearcuts and continuous cover forestry. Unlike previous studies, we determine the economically optimal management regime endogenously, by optimization. We study a policy where the society pays forest owners a Pigouvian subsidy for the carbon that is sequestered by the stand as it grows. The focus of our analysis is a subsidy system that also takes into account the carbon both stored in and released from wood products. In the first part of the thesis, the question of optimal carbon storage is studied using a continuous time biomass model that does not include any a priori assumptions on clearcuts vs. continuous cover forestry. We show analytically that subsidized carbon sequestration postpones thinning and increases optimal stand volume along the rotation. With high carbon price the shadow value of stand volume becomes negative. Numerical results show that carbon prices within a realistic range may switch the optimal management regime from clearcuts to continuous cover management. A higher interest rate can lead to a higher stand volume and a longer optimal rotation, which contrasts the results of the classic Faustmann model. Next, the question is studied applying a more detailed size-structured transition matrix model based on empirically estimated Scandinavian growth data. This approach produces a more accurate description of the complex dynamics of uneven-aged stands and optimization of harvesting activities. According to numerical results, thinning is invariably carried out from above, and the size of the harvested trees increases with carbon price. Optimal rotation age increases with carbon price, and moderate carbon pricing is sufficient to switch the management regime to continuous cover management. Optimal rotation age also increases with interest rate. Clearcut management is the more competitive, the more productive is the site type. Both models suggest that carbon storage has a significant effect on optimal forest management, and that it typically favors continuous cover forestry. Similar analysis on optimal carbon storage in forestry has not been presented before. We also discuss various carbon subsidy systems in the context of developing climate policy.
  • Järvenpää, Lari (2014)
    The need to understand causes behind business cycles and inflation, and their link to prevailing monetary policy is today essential. During recent years, the family of Dynamic Stochastic General Equilibrium (DSGE) models has emerged as the workhorse for characterizing these phenomena and their interlinkage, allowing a detailed, structurally microfounded modelling of economys general equilibrium and its dynamic response to exogenous, stochastic shocks. Traditionally, a central bank is assumed to be able to carry out its monetary policy influence towards the economy by altering the value of its conventional instrument, the nominal short-term interest rate. In the light of the recent financial crisis pushing those interest rates very low towards their zero lower bound, there has been a need, and correspondingly significant research towards designing unconventional instruments, with which a control could be retained also in the event of short-term interest rates becoming ineffective. One of these alternatives is called quantitative easing, which involves buying of government issued bonds. This Thesis presents a stylized, closed economy DSGE macromodel with nominal Calvo rigidities both in prices and wages. The model also incorporates a stylized financial sector. It then discusses how monetary policy instruments, namely the conventional nominal short-term interest rate, but also more unconventional government asset purchases, can be used in steering the economy in the presence of an exogenous shock shifting it away from its initial equilibrium. We simulate the developed macrosystem in the presence of exogenous shocks, and optimize the rules according to which the central bank uses its two instruments. Our results indicate that co-ordination between interest rate setting and quantitative easing is optimal, but before concluding on any specific policy principles, care should be taken in calibrating both the model of the economy and the metric evaluating welfare effects of the policy.
  • Ojala, Inari (2019)
    Forests have a significant role in preventing climate change. Forests work as a carbon sink and produce also other non-timber amenity values alongside commercial timber. Taking these non-timber amenity values into account while calculating the value of forest will have an effect on choosing an optimal forest management regimes. The Faustmann formula and its extensions are widely explored among forest economists. Most notable extensions of the Faustmann formula include the Hartman extension of non-timber amenity values and the inclusion of carbon storage. Both the Hartman model and the Faustmann model with carbon storage, have previously only been analytically studied separately. In this study, the original Faustmann model, Faustmann model with carbon storage, Hartman model and Hartman model with carbon storage is covered. The entirely novel optimal conditions for the unique and finite rotations for these models are presented. In addition, based on empirically estimated ecological growth models, the numerical examples for all of the economic models included in this study is presented. According to the results, extending the classical Faustmann model to cover carbon storage or (and) non-timber amenity values, lengthens the optimal rotation and increases the bare lad value. Additionally, weaker growing conditions always increase the optimal rotation. Moreover, increasing the interest rate may increase or decrease the rotation, depending on the carbon price.
  • Jin, Qi (2013)
    The optimal harvesting for a set of even-aged Dahurian Larch (Larix gmelinii) stands located in Aershan area of the northeast of Inner Mongolia, China, are studied. The effects of catastrophic pest outbreaks (i.e. Siberian moth) on the optimal harvesting plan are also studied, and the comparison on these two cases, namely deterministic and stochastic, are analyzed. The simulation is based on an individual-tree diameter growth model, an individual-tree height model, and model for the tree mortality for the coming 5-year period. Combined with the simulation system, the optimization model modified from Hyytiäinen et al. (2005) is able to find the number of thinnings, intensity of thinning, type of thinning, subject to given rotation lengths. In even-aged management, the objective variable is the bare land value with 3.5% discount rate. In addition, a scenario approach is applied when simulating the effects of catastrophes, i.e., pest outbreaks. Stochasticity here is represented by a set of scenarios. The timing of an insect outbreak is random. In order to know the frequency of insect outbreak, an exponential model is applied. The numerical results indicate that the probability that an outbreak at epidemic level will occur within an interval of 5 years is about 0.39. Within a 10-year interval the probability is about 0.63. It is nearly certain that an outbreak at epidemic level occurs within 45 years. The optimal solutions are presented separately for deterministic and stochastic cases. For the deterministic case, the results indicate that high bare land values were associated with stands of high basal area, tree diameters and height. Typically, the higher the mean annual increment and the site quality, the higher the bare land value. Meanwhile, the results show that the optimal rotation may vary considerably (40-58 yrs) at 3.5% interest rate depending on the initial stand state. In the stochastic case, considering the effect of catastrophe of pest outbreak, numerical results show that the optimum roation is shortened and the mean values of bare land value are about 14.8% to 25.6% lower compared with the deterministic case.
  • Malmström, Miika (2013)
    This thesis studies the economically optimal timing of thinnings and final harvest on Costa Rican Tectona grandis plantations. Consequently this thesis studies the profitability of the plantations and makes a comparison to previous studies. Optimization is based on programming with AMPL with Knitro optimizing software. The objective function used is the Faustmann formula. Different rates of interest are used. The ecological functions used for the modeling were obtained from previous studies by Pérez and Kanninen (2005a). The economic data such as planting and thinning costs and log prices were obtained from a T. grandis plantation specialist. The results of the study show that the optimal harvesting regime in T. grandis plantations differs from what is suggested in literature. The main findings are that the optimal rotation length is shorter and both timing and intensity of the thinnings vary depending on the rate of interest used. In addition the maximized bare land values under optimal management regimes are notably higher than bare land values under previously suggested management regimes. The management regime is highly sensitive to the rate of interest used. The management regime is less sensitive to the changes in price than expected. This thesis suggests that the initial density of 816 ha-1 trees results into higher bare land values than 1111 ha-1 trees . However, the difference is minor and possible increase in silvicultural costs is not considered. In addition a simple test is carried out to see the possible effects on heartwood proportion growth to the optimal management regime. The shortcomings and possibilities to improve the model are discussed. It is noted that the price data for T. grandis is not coherent, and that the ecological model could be improved in order to increase its accuracy.
  • Rämö, Janne (2013)
    This study analyzes the optimal harvesting of single species uneven-aged Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and birch (Betula pendula Roth. and B. pubescens Ehrh.) stands, in addition to mixed species stands with all three species. The analysis is based on an economic description of uneven-aged forestry using a size-structured transition matrix model and a single-tree model. The optimization problem is solved in its general dynamic form using gradient-based interior point methods. Similar analysis on uneven-aged birch, Scots pine and mixed species stands in Nordic conditions has not been published. Increasing the harvesting interval decreases the average annual volume yield. Assuming natural regeneration, this suggests that volume yield is maximized by uneven-aged rather than even-aged management. The present value of stumpage revenues is maximized after saw timber and pulpwood prices, interest rate, and a 15-year harvesting interval are included. The economically optimal solution with a 3% interest rate produces an annual yield of 1.9, 5.5 and 2.9 cubic meters (m3) for Scots pine, Norway spruce, and birch respectively in single species stands at site with average productivity. At less productive sites, the mixed species stand is heavily dominated by Norway spruce regardless of interest rate. At more productive sites on the other hand, increasing interest rate increases species diversity. Both the optimal volume yield and net present value maximization solutions converge to unique species- and site-type-specific steady-states with constant harvests. The transition matrix model typically used in optimization studies is computationally less demanding than the single-tree model, but the differences in optimal solutions are more remarkable than earlier studies show. Additionally, it appears that the investmentefficient optimization model may result in steady-state solutions that significantly differ from the correct solutions.
  • Holma, Maija (2011)
    The objective of this thesis is to examine the economic effects in the conflict between grey seal population and the salmon fishery in the Baltic Sea. We will formulate a bioeconomic model which provides new insights on the optimal management of Atlantic salmon with respect to the effects brought about by the grey seal population. As the catch losses caused by seals have an effect on salmon fishery in Baltic, we will study how seal population affects the present value of the salmon fishery. The study considers the Finnish coastal trap net fishery. The bioeconomic model considers a scenario of sole salmon fishery and a scenario of salmon fishery affected by the grey seal population. On the basis of these scenarios, a seal compensation scheme is introduced. We can observe a significant economic seal-induced effect on the salmon fishery. The results suggest that the present seal compensation scheme emploid by the Finnish government is suboptimal. This thesis is part of the TARMO –project, in which the conflict between grey seal population and salmon fishery is studied using the methods of environmental economics.
  • Räsänen, Jenni (2013)
    The purpose of this study was to define economically optimal stand structures and harvesting cycles for uneven-aged Scots pine (Pinus sylvestris L.) in Finland. According to a recent proposal by Ministry of Agriculture and Forestry, uneven-aged management will be included in the new Forest Act as an alternative for future forest management in Finland. Uneven-aged management is also planned to be included in the Forest management practice recommendations by the year 2014. However, only little knowledge exists on optimal uneven-aged management in Finland, particularly on uneven-aged Scots pine. This thesis aimed at filling the gap in knowledge regarding economically optimal management of uneven-aged Scots pine. So far, economic studies on uneven-aged Scots pine have been conducted only in a static optimization framework, where optimal stand structure is constrained with a classic “reversed-J” diameter distribution, and transition cuttings are limited to one single harvest. In this work, stand structures and harvesting cycles were optimized for maximum volume yield and maximum stumpage revenues by applying both static and dynamic optimization. Until now, no dynamic optimization has been conducted on uneven-aged Scots pine. Static optimization was applied for different growth sites from mesic sites in Southern Finland (MT1300) to sub-xeric sites in Central Finland (VT1100). Mesic sites in Southern Finland were also optimized in a dynamic framework. A density-dependent individual tree model with latest ecological growth models was applied in optimization. The large-scale nonlinear problems were solved by means of numerical computing with discrete-time formulations. Present value of stumpage revenues was maximized applying 1% and 3% discount rates. Economically optimal harvesting cycle became 40 years in Southern Finland (site MT1300), and even longer at more northern and less fertile site types. Results imply that it is not economically optimal to manage Scots pine with a traditional selection method with short harvesting cycles, but rather with a heavy harvesting regime including low after cut basal areas. When maximizing present value of stumpage revenues, optimal after cut basal areas in Southern Finland were as low as 5 m2 (1% discount rate) and 3.2 m2 (3% discount rate) per hectare. A proposal of Ministry of Agriculture and Forestry suggests minimum after cut basal areas of 10–11 m2 per hectare for Southern Finland, which clearly exceed the optima of this study. Contrary to the existing results for uneven-aged Scots pine, economically optimal stand structure did not follow the classic reversed-J diameter distribution.
  • Nieminen, Emmi (2011)
    The aim of the thesis is to assess the fishery of Baltic cod, herring and sprat by simulation over 50 years time period. We form a bioeconomic multispecies model for the species. We include species interactions into the model because especially cod and sprat stocks have significant effects on each other. We model the development of population dynamics, catches and profits of the fishery with current fishing mortalities, as well as with the optimal profit maximizing fishing mortalities. Thus, we see how the fishery would develop with current mortalities, and how the fishery should be developed in order to yield maximal profits. Especially cod stock has been quite low recently and by optimizing the fishing mortality it could get recovered. In addition, we assess what would happen to the fisheries of the species if more favourable environmental conditions for cod recruitment dominate in the Baltic Sea. The results may yield new information for the fisheries management. According to the results the fishery of Baltic cod, herring and sprat are not at the most profitable level. The fishing mortalities of each species should be lower in order to maximize the profits. By fishing mortality optimizing the net present value would be almost three times higher in the simulation period. The lower fishing mortality of cod would result in a cod stock recovery. If the environmental conditions in the Baltic Sea improved, cod stock would recover even without a decrease in the fishing mortality. Then the increased cod stock would restrict herring and sprat stock remarkably, and harvesting of these species would not be as profitable anymore.
  • Airaksinen, Janne (2021)
    Aquaculture is seen as an answer to the future’s projected demand increase of seafood. This offers possibilities for the Finnish society to benefit economically. Globally, environmental concerns are set to the pressure the future demand, since the sector’s production is jointly linked to creating negative outputs, nutrient emissions. These problems are especially present in Finland, which’s offshore aquaculture production occurs geographically in one of the world’s most eutrophicated seas, the Baltic Sea. Finnish aquaculture regulation is currently a type of “command and control”, which is seen as one of the main reasons why the domestic production has decreased drastically in 21st century. Continuing to utilize feed quotas may not sufficient and incentivizing for the producers which creates need to review other possible economic instruments. This research studies the possibility of utilizing auctioned emission permits. The work contributes to auction theory of incomplete information games while adding Baltic Sea elements such as abatement costs to our analyzed model. This thesis addresses three questions: How can the chosen auction models support sustainable growth of aquaculture in economically efficient way? What is the level of optimal price floor? Which auction form is expected to create highest revenue surplus for the society? The policy maker is interested in assessing which of the chosen auction models is best allocation tool under present asymmetrical information. To combat the missing information on production values per kilogram of nitrate, Monte Carlo-simulation is utilized to generate values for the bidding producers. The analysis creates premise of including price floor in the mechanism designs to guarantee sustainability. The price floor guarantees that the value of allocated permit will be at least the size of our adopted abatement costs, which originate from certain mussel cultivation farm located in Sankt Anna, Sweden. The effects of two potential price floors are analyzed. First, which secures sustainability and second, which maximizes expected revenue surplus. Our modelled results follow the findings of the theory. All chosen auction designs are expected to create similar results in allocating the emission permits. To secure that the allocated permits are sustainable, and that the allocation maximize society’s revenue surplus, the social planner should implement price floor which is strictly higher than his personal valuation of the permit. This removes the possibility of auction being ex-ante efficient. Even though in the chosen model setting the price floor’s level was not dependent on the level of buyers, the social planner should not ignore the aspect of competition. By designing a mechanism that enables easy entry for bidders to participate, the auctions are expected to attract higher levels of competition which can create results that are closer to competitive markets. This can decrease the role of price floor, which may ease mechanism designing. To get more accurate results in the Finnish scene, more detailed information on possible domestic aquaculture production values is needed
  • Ikonen, Joni (2016)
    Quantum computers store and manipulate information in individual quantized energy levels. These devices, not yet realized in their full potential, have the ability to perform certain computational tasks more efficiently than any classical computer. One possible way to implement a quantum computer is to use superconducting circuits controlled by single-mode electromagnetic fields. These circuits constitute the physical quantum bits, or qubits, that are used to store quantum information. A complete, fault-tolerant quantum computer potentially consists of at least millions of physical qubits which are grouped to form fault-tolerant logical qubits. Controlling each physical qubit individually requires a great amount of energy, and hence a future challenge is to reduce the energy consumption in qubit control while maintaining the high precision. In this thesis, we derive a fundamental upper bound for the gate fidelity of a single-qubit not gate implemented with a single resonant driving pulse. It is shown that the upper bound approaches unity inversely proportionally to the increasing mean photon number of the pulse. Furthermore, we find that the upper bound is achieved with an optimal superposition of squeezed states. The typically employed coherent state produces twice as high gate error as the corresponding optimal state. In addition, we present and numerically study a correction protocol that allows using the same drive state for multiple qubit operations. This sustained state is refreshed by sequentially coupling ancillary qubits to it, effectively resetting it and removing entanglement with the previously operated qubits. Thus our protocol allows using the same drive state to implement not gates for different qubits indefinitely, and hence provides a possible route to energy-efficient large-scale quantum computing.
  • Eskin, Thomas (2013)
    In this thesis we study the notion of non-negative Ricci curvature for compact metric measure spaces introduced by Lott and Villani in their article (2009): Ricci curvature for metric measure spaces via optimal transport. We also define and prove the required prerequisites concerning length spaces, convex analysis, measure theory, and optimal transportation.
  • Ekblom, Madeleine (2017)
    Numeriska väderprognosmodeller (NWP, numerical weather prediction) innehåller variabler, såsom vindvektorer, temperatur och tryck, samt modellparametrar. Modellparametrar är en oundviklig del av en NWP då de behövs i parametriseringsscheman av småskaliga fysikaliska processer. Modellparametrarna har betydelse för modellens förmåga att prognostisera vädret och det är därav av stor vikt att parametrarna har optimala värden. Värdet på parametrarna bestäms manuellt med hjälp av observationer och expertkunskap, vilket är en arbetsdryg process. För att minska på arbetsbördan och frigöra resurser för annat är det möjligt att använda sig av algoritmer för att bestämma de optimala värdena på modellparametrarna. I den här studien undersöker vi en statistisk algoritm som används i ett ensembleprognossystem. Algoritmen grundar sig på att uppdatera och förbättra parametervärdena baserat på observationer och en kostnadsfunktion. Tidigare resultat har visat att algoritmen ger goda resultat med en ensemble på 50 medlemmar. I den här studien undersöks huruvida det är möjligt att minska ensemblestorleken vid optimering av två parametrar och samtidigt uppnå goda resultat. I experimenten används Lorenz96-modellen för att emulera NWP och ensemblestorleken varieras mellan två och 50. Resultaten tyder på att en ensemblestorlek på fyra ger goda resultat då utgångsläget är optimalt och vid mindre optimala förhållanden krävs flera ensemblemedlemmar; i det här fallet tio. Baserat på de här experimenten kan vi dra slutsatsen att algoritmen inte begränsas av ensemblestorleken utan snarare av modellen och utgångsläget vid parameteroptimering. Ju bättre utgångsläget är, desto mindre ensemble är möjlig att använda. Experimenten indikerar på att motsvarande resultat är att vänta för NWP.
  • Kanerva, Suvi (2023)
    Filamentous fungus Trichoderma reesei (teleomorph Hypocrea jecorina) is a crucial production organism for enzymes used in industrial applications, such as in feed, food, textile, and biofuel production, due to its ability to secrete high amounts of homologous and heterologous enzymes. Therefore, development of genetic tools to improve the properties of industrial T. reesei strains for even better production yields is essential. In this study, a polyethylene glycol mediated CRISPR-Cas9 transformation method for industrial T. reesei production strains was aimed to be optimised by testing an alternative Cas9 enzyme and varying the stoichiometry and total amount of Cas9 enzyme and single guide RNA in the ribonucleoprotein complex. Correct integration of the gene constructions in the obtained transformants was determined by colony PCR and Southern blot analysis. In addition, two selected background activity encoding genes, endoglucanase 6 and α-glucuronidase 1, were individually deleted from T. reesei xylanase production strain utilising the improved CRISPR-Cas9 transformation protocol. The effect of background activity deletions on the strain growth and protein production were analysed from culture supernatants by pH measurement, Bradford protein assay, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and enzyme activity assays. An improved CRISPR-Cas9 transformation protocol for T. reesei was successfully established basing on high number of transformants and improved DNA integration fidelity. No negative effects were observed in the growth or protein production properties of the background activity deletion strains compared to the xylanase production strain. Thus, further cleansing of T. reesei secretome can be continued to refine the industrial production strains.
  • Corner, Joona (2023)
    The aim of this work is to develop and optimise an atmospheric inverse modelling system to estimate local methane (CH4) emissions in peatlands. Peatlands are a major source of CH4 regionally in boreal areas and they have significance on a global scale as a soil carbon storage. Data assimilation in the inverse modelling system is based on an ensemble Kalman filter (EnKF) which is widely used in global and regional atmospheric inverse models. The EnKF in this study is an implementation of the EnKF used in the global atmospheric inversion model CarbonTracker Europe-CH4 (CTE-CH4) applied to local setting in the peatland. Consistency of the methodology with regional and global models means that it is possible to expand the system in scale. Siikaneva fen in Southern Finland is used as a testbed for the optimisation of the system. Prior natural CH4 fluxes in Siikaneva are acquired from the HelsinkI Model of MEthane buiLd-up and emIssion for peatland (HIMMELI) which simulates exchange of gases in peatlands. In addition to the peatland fluxes, anthropogenic fluxes at the site are estimated as well in the inversion. For the assimilation of atmospheric CH4 concentration observations, the CH4 fluxes are transformed into atmospheric concentration with a simple one-dimensional box model. The optimisation of the system was done by changing parameters in the model which affect the data assimilation. In model optimisation tests it was discovered that the performance of the modelling system is unstable. There was large variability in the produced estimates between consecutive model runs. Model evaluation statistics did not indicate improvement of the estimates after the inversion. No exact reason for the unstability was able to be determined. Posterior estimates of CH4 fluxes for years 2012–2015 did not differ much from prior estimates and they had large uncertainty. However, evaluation against flux measurements showed reasonable agreement and posterior concentration estimates were within the uncertainty range of the observed concentration.
  • Raatikainen, Riikka (2022)
    Tutkielma käsittelee optimismivinouman esiintymistä tulevaisuusskenaarioissa, joiden aiheena on ilmastonmuutos. Siinä missä skenaariomenetelmän käyttö voi vähentää tiettyjen kognitiivisten vinoumien vaikutusta tulevaisuutta koskevissa arvioissa, toiset vinoumat voivat puolestaan haitata skenaarioiden laatimista ja arviointia. On arveltu, että useissa eri konteksteissa esiintyvä optimismivinouma näyttäytyisi myös skenaariomenetelmän yhteydessä. Tutkimus selvittää kokeellisesti, esiintyykö ilmastonmuutosaiheisten skenaarioiden arvioinneissa optimismivinoumaa, eli pitävätkö koehenkilöt positiivisia skenaarioita muita todennäköisempinä. Lisäksi tarkastellaan, onko skenaario-optimismi yhteydessä optimismivinoumaan toisessa kontekstissa mitattuna sekä muihin muuttujiin. Tutkimuskysymysten selvittämiseksi koostettiin kyselylomake, joka lähetettiin Helsingin yliopiston ainejärjestöjen sähköpostilistoille. Kyselyyn tuli 182 vastausta. Tutkittaville esitettiin neljä skenaariota, jotka vaihtelivat positiivisesta negatiiviseen, ja ne käsittelivät saimaannorpan selviytymistä ja kannan kokoa 50 vuoden päästä. Koehenkilöiden tuli asettaa skenaariot todennäköisyysjärjestykseen, jonka pohjalta kullekin vastaajalle laskettiin tietty optimistisuuden taso. Keskimäärin vastaajat olivat pessimistisiä arvioissaan, ja tämä optimistisuuslukema jäi alle neutraalina pidetyn arvon. Skenaarioarvioissa ei siis esiintynyt optimismivinoumaa. Optimismivinoumaa mitattiin myös laittamalla koehenkilöt arvioimaan eri elämäntapahtumien todennäköisyyksiä omalla kohdallaan verrattuna muihin. Näissä kysymyksissä optimismivinoumaa esiintyi, sillä vastaajat arvelivat keskimäärin kokevansa positiivisia tapahtumia muita todennäköisemmin ja negatiivisia muita epätodennäköisemmin. Elämäntapahtumaoptimismin määrä myös korreloi positiivisesti skenaario-optimismin kanssa. Lomakkeella selvitettiin myös muiden muuttujien yhteyttä skenaarioarviointien mahdolliseen optimismivinoumaan. Yleisen optimismin tasoa selvitettiin valmiilla kyselyllä, mutta tämä ei korreloinut skenaario-optimismin kanssa. Ilmastonmuutosasenne puolestaan korreloi negatiivisesti skenaario-optimismin kanssa, eli ilmastonmuutokseen vakavasti suhtautuvat arvioivat skenaarioita pessimistisemmin. Vastaajien ikä, sukupuoli tai saimaannorppatiedon määrä ei vaikuttanut skenaarioarviointeihin. Optimismivinouman puute skenaarioarvioissa oli yllättävä tulos, jonka tarkkaa syytä ei voida sanoa täsmällisesti. Tämä voi johtua joko skenaariomenetelmän kognitiivisia vinoumia vähentävästä vaikutuksesta tai skenaarioiden aiheena olleen ilmastonmuutoksen herättämistä negatiivisista mielikuvista. Olisikin tarvetta tutkia aihetta lisää edustavammalla otoksella sekä tutkimusasetelmalla, joka erottelisi skenaariomenetelmän ja ilmastonmuutosaiheen vaikutukset toisistaan. Skenaarioiden käytön kannalta optimismivinouman puute voidaan kuitenkin nähdä hyvänä asiana.
  • Riihimäki, Lotta Eveliina (2022)
    Severe acute respiratory syndrome coronavirus 2 is the pathogen behind COVID-19, a contagious disease that has caused millions of deaths since the beginning of the global pandemic in 2019. It is essential to gain more knowledge about the factors affecting viral entry and infection to understand prevention and treatment possibilities for the pathogen. Initially, an immunostaining assay was set up and showed that at eight hours post-infection, the virus had entered the target cells and started protein production. Five host genes of interest, identified by collaborators, were transiently silenced using small interfering RNA knockdown of cell lines. Once the silencing had been optimized, the effect on SARS-CoV-2 infection was monitored at eight and 24 h post-infection. The main pipeline used to follow the cell entry and replication was an extraction of total RNA, reverse transcription reaction followed by quantitative digital droplet polymerase chain reaction, showing the concentrations of the expressed target genes in the cells. The protocols of the transfection and ddPCR were tested and optimized to provide reproducible and reliable results. Out of six tested transfection reagents, DharmaFECT 2 showed the most effective results, decreasing the expression of target genes DDX3X and PDE4A by more than 75% after a 24 h incubation. The produced knockdown cells were infected with a produced and purified stock of SARS-CoV-2. Plaque assays were made from samples collected 24 hours post-infection, but no difference could be seen in the titer of the virus between the transfected cells and negative control cells. In conclusion, using digital droplet polymerase chain reaction to follow the effect of host gene knockdown on virus replication is possible as long as the initial gene expression is high enough.