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(2016)The main focus of this study is a Finnish family, in which four out of eight children presented with an unidentified disease causing a grave developmental disorder. A genetic cause for this disorder was sought by utilizing whole exome sequencing. Both parents, two affected siblings and one healthy sibling were sequenced. After variant filtering and analysis, only the candidate gene UBA5 passed the filtering criteria. The results were validated using Sanger sequencing. Both affected individuals were shown to have compound heterozygous variants of this gene, with one of the variants being novel. No cases of disease in humans associated with UBA5 have prior to this study been reported. However, other unrelated patients with a similar phenotype have since been found to possess pathogenic variants in the gene UBA5, which confirms the claim that it's the disease-causing gene. Therefore, this study enhances our knowledge of the gene's physiological significance.
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(2023)Plant-based milks can be unstable during storage due to the colloidal structure of these drinks. In general, e-coded additives are used to increase the viscosity of the drinks and hence, improve stability. Oat beta-glucan, microbially or enzymatically produced exopolysaccharides, such as dextran, and flaxseed mucilage are natural hydrocolloids that are known to have the ability to increase viscosity. These hydrocolloids could potentially be used to replace e-coded additives. The aim of this thesis was to study the stabilizing potential of oat beta-glucan, exopolysaccharides, and flaxseed mucilage in oat drinks. Oat drinks with added hydrocolloids were compared to control samples that were oat drink without added hydrocolloids and oat drinks with pectin at concentrations of 0.2% and 0.4%. Oat beta-glucan, exopolysaccharides, and flaxseed mucilage were added to the prepared drinks by replacing 10% of water with the extracts. Additionally, stabilizing properties of isolated and freeze-dried microbially produced dextran was studied by adding it to the drinks at concentrations of 1.5%, 1.0% and 0.5%. Stability of the oat drinks was assessed during a 14−day storage period by measuring the viscosity, pH, and phase separation. Results of this study demonstrated the stabilizing potential of the natural hydrocolloids. The addition of hydrocolloids increased the viscosity in all samples. The inclusion of natural hydrocolloids led to a similar stability, and in some cases also significantly lower viscosity, compared to pectin added drinks. Oat beta-glucan had a remarkable positive impact on the stability of oat drinks. This was most likely due to the network formation of oat beta-glucan molecules, which decreased the sedimentation of colloidal particles. Enzymatically produced dextran also improved the stability of oat drinks, which might be attributed to the viscosity-increasing -capacity of dextran. However, the stabilizing role of microbially produced exopolysaccharides was not shown. For future study, the molecular interactions of natural hydrocolloids in the colloidal solution should be investigated.
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(2016)APECED (autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy) on suomalaiseen tautiperimään kuuluva harvinainen monogeeninen autoimmuunisyndrooma, joka aiheutuu AIRE-geenin mutaatioista. AIRE:a ilmennetään pääasiassa kateenkorvassa, jossa se ohjaa kudosspesifien antigeenien ekspressiota ja esittelyä kehittyville tymosyyteille. AIRE:n mu-taatiot johtavat tymosyyttien negatiivisen selektion häiriintymiseen, jolloin autoreaktiivisia T-soluklooneja pääsee kehittymään. APECED-potilaiden perifeerisen veren CD8+ T-solupopulaatiossa on havaittu patologisia poikkeavuuksia, CD4+ säätelijä-T-solut toimivat puutteellisesti ja autovasta-aineet häiritsevät Th17-auttajasolujen toimintaa. Tutkimme CD4+ auttaja-T-solujen toimintaa kymmenessä APECED-potilaassa ja terveessä verrokissa solustimulaatioilla, virtaussytometrialla ja transkriptomianalyysilla. Effektori/muistisolujen osuus oli suurentunut, kun taas naiiveja soluja oli vähemmän. Naiivit solut vaikuttivat poikkeavasti aktivoituneilta, sillä ne tuottivat kypsille auttaja-T-soluille tyypillisiä sytokiinejä. Erityisesti interferoni gamman (IFN-γ) tuotanto oli lisääntynyt, mikä sopii yhteen CD8+ T-solujen häiriön kanssa, sillä IFN-γ stimuloi CD8+ T-soluja. Myös vastikään kateenkorvasta lähteneissä auttaja-T-soluissa havaittiin samoja poikkeavuuksia effektori/muistisolujen ja naiivien solujen suhteissa sekä sytokiinituotannossa. Löydökset viittaavat auttaja-T-solujen häiriöön ja ennenaikaiseen aktivaatioon, joka alkaa jo kateenkorvassa tapahtuvan kehityksen aikana.
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(2018)Nearly 250 Finnish companies, i.e. as many as the amount of listed companies in Finland, receive private equity investments annually. The purpose of private equity funds that make these investments is to develop their target companies and conduct a successful exit at some point. Further, a Finnish company expanding its business abroad may have many alternative or complementary reasons for the expansion. However, wider opportunities to obtain funding and to scale up a business are most likely some of the main ones. Therefore, it could be imagined that especially the companies owned wholly or partially by private equity funds may aim to expand to the US markets because the expansion provides a solution to achieve the private equity funds’ purpose. Nowadays, in addition to the larger markets, the United States is ranked as the most attractive venture capital and private equity country of the world. There is a notable lack of information if different markets, their opportunities and the legislations related to them are not being researched. Such asymmetric information leads to the truthful overall view of range of options being lost when the market players receive only information of certain opportunities. Logically, if market players i.e. companies receive information of EU, limited to that extent, they allocate their operations to the EU area only. This, accordingly, distorts the effective functioning of the global markets. This study aims to provide a practical approach to expanding a Finnish business to the United States from the tax perspective by taking into consideration the main issues related to taxation of such business expansion. This contains identifying the applicable tax implications imposed by the tax laws of Finland and the United States. The issue is examined from a private equity firm’s perspective due to the significance of the private equity investments in the financial markets, i.e. many companies currently have a private equity fund or investor as their shareholder. The theoretical frame of this study consists of the fundamentals of both international taxation and functioning of private equity firms as a part of a private equity fund in order to understand the tax implications occurring to all the parties involved in the company structure and special characteristics of private equity firms that reflect to their business operations. With regard to the findings of this study, it may be stated that the tax neutrality should exist in the Finnish-US cross-border business expansion cases. The tax burden is the same despite of the selected company form or of the choice of either a branch or a subsidiary. No issues causing “more burdensome taxation” as stated in the tax treaty between the United States and Finland were found. However, this statement is valid only under the current legal practice. Further, the effectivity of the obligations related to non-discrimination set in the tax treaty between Finland and the United State may be questionable. The corporate income tax laws of the United States do not provide exactly the same tax treatment for a branch than to subsidiaries. But, similar treatment is not required by either the Finnish-US tax treaty or the OECD MTC. No case law concerning differences occurred in the tax treatment of a branch or a subsidiary was found in the Finnish-US relations. Therefore, the tax treatment in practice may be different than in theory and the question of “more burdensome taxation” may arise later.
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(2015)Objectives. Cleantech, as an emerging new industry, its development involves the influences from various aspects. As a small to medium-sized cleantech company, the activity in China can be very challenge to study holistically. This research is aimed to provide a holistic view of the challenges and possibilities of a small to medium-size cleantech company's activity in China from the expansive learning perspectives. The purpose of this research is threefold. Firstly, it analyzes the object and network to uncover the three historical phases of GreenStream's long trajectory leaning process. Secondly, it analyzes learning actions and contradictions to uncover the driving forces of development and the expansiveness of the activity. Thirdly, based on the historical analysis an analysis of expansive learning cycles is made, with the purpose to sketch the zone of proximal development across the learning cycles and address the future possibilities and challenges. Methods. The research case Company is GreenStream, a small to medium-sized Finnish cleantech company in China. 8 Interviewees were chose from the different parties involved in its China activity. 4 of the interviewees from the case company GreenStream, 1 interviewee from its Chinese partner, and 3 interviewees from the third parties. The data is firstly analyzed by the historical analysis, namely analysis of object of activity system and analysis of network, following the analysis of expansive learning cycles, namely analysis of learning steps and analysis of learning actions and analysis of developmental contradictions. The zone of proximal development is sketched based on the historical analysis and analysis of expansive learning cycles. Results and conclusions. Interesting findings emerge through the systematic analysis. Three historical analyses reveals the object and network transformed in 3 phases. The object has transformed in 3 historical phases with the unchanged main motivation, the evolving economic imperative, and other emerging forces from different element of the activity. The partnership activity emerged and consolidated with the network development. Object formation and network development thus form the criteria to divide the 3 historical phases from "Small Spark in China", to " Great Success in China" and then to "Standing on Two Feet in China". Analysis of expansive learning cycles reveals that the 3 historical phases contours 3 expansive learning cycles. The first learning cycle was disrupted, the second learning cycle completed and expanded, and the third learning cycle is under development. Each learning cycle has its own character, and within each learning cycle, different levels of contradictions emerged as the driving forces of the development of GreenStream. Through tracing different levels of contradictions through the 3 expansive learning cycles, the expansiveness of GreenStream's activity could be detected with regard to the expansion of the object and expansion over interruption. Object formation, partnership and policy over clean-tech industry become important three elements for the zone of proximal development of GreenStream's activity in China. Through the understanding of these dynamics and momentum of the China activity in the past and present by means of expansive learning aspects, the subject can better master and build the development of the activity system in the future.
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(2016)The conventional understanding and model of development is based on economic growth. This dominant way of creating development has consequences to natural, cultural and social environments, which cannot be overlooked. The transformations within these environments are increasingly connected to the prevailing socio-economic model of neoliberalism, but are often not considered in its contextualization at a local scale. The processes of production of space and nature under the neoliberal doctrine have led to economic restructuration and to conformation of geographies of neoliberal environment, which together transform localities. There is an increasing need to investigate how the local inhabitants understand and experience these processes and their outcomes. In this research, place is introduced as an insight to observe these problematics. Place in this research is understood as a changing and dynamic terrain, which articulates experiences of development. This research is qualitative case study which investigates the consequences of production of space and nature in Curepto, Chile. Curepto is one of the localities where the implementation of a normative framework for economic growth has resulted in extensive areas of foreign tree species monoculture and important physical and socio-spatial transformations related to them. The primary aim of this research is to investigate the local inhabitants' accounts of these transformations. The thesis investigates how the locality has changed, but focuses on what these changes have meant for the local community and their sense of place. Physical, sociocultural and emotive dimensions of place as well as their transformations were investigated using qualitative methods, mainly semi-structured interviews. Residents were interviewed both in urban and rural districts. The findings of this research indicate that the forest industry and tree plantations have been important drivers behind the physical and socio-spatial transformations. The extensive plantations of pine and eucalyptus have changed the physical environment and these transformations are reflected in the social and cultural geography. Environmental degradation, changed circumstances of land property, loss of native forests and drought constitute transformations that affect livelihoods negatively especially in the rural districts, and come in parallel with a loss of local tradition and culture. The meaningful space the inhabitants experience diminishes and is made more one-sided, as access to the natural environment becomes more difficult and the interaction with it is lost. Although transformations within place are considered negative, the meaningful relation inhabitants have with place remains positive. Participants redetermine their practices and livelihoods, and re-articulate the relation with their surroundings in order to stay in their place. The local community lives in a space that is both familiar and foreign to them, loved and hated at the same time.
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(2019)When international students from mainland China go abroad and start their new life in Finland, they have the choice of using social media platforms such as Facebook and Twitter which have been blocked by mainland China for many years. Additionally, they may keep using platforms that of their native language, like WeChat and Sina Weibo. The current research studies Chinese international students’ perception of their cultural adaptation to Finnish society, with a particular focus on the role of social media usage during their process of adaptation. This study also aims to give attention to intercultural adaptation in the Finnish context. The study conducts a semi-structured interview among eight Chinese mainland students who study in Finland. Interviews are audio-recorded. All data collected are transcribed in Chinese and then translated into English. The qualitative research of content analysis is employed in this study for analysing the research data. The analysis indicates that most Chinese students have positive feelings about Finland. However, the ties between Chinese students and Finnish natives are weak due to various reasons including languages, cultural differences and personalities. These findings further state that the social media usage patterns and preferences of Chinese students are different depending on their length of stay in Finland and the gratification of social media. The analysis demonstrates that the majority of Chinese students prefer to use social media platforms that of their native language, other than Facebook and Twitter. The analysis also highlights different perceptions of cultural adaptation from Chinese students, which reveals that each respondent has his/her way of adapting to Finland.
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(2020)Software testing is an important process when ensuring a program's quality. However, testing has not traditionally been a very substantial part of computer science education. Some attempts to integrate it into the curriculum has been made but best practices still prove to be an open question. This thesis discusses multiple attempts of teaching software testing during the years. It also introduces CrowdSorcerer, a system for gathering programming assignments with tests from students. It has been used in introductory programming courses in University of Helsinki. To study if the students benefit from creating assignments with CrowdSorcerer, we analysed the number of assignments and tests they created and if they correlate with their performance in a testing-related question in the course exam. We also gathered feedback from the students on their experiences from using CrowdSorcerer. Looking at the results, it seems that more research on how to teach testing would be beneficial. Improving CrowdSorcerer would also be a good idea.
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(2022)This study was conducted with the participation of HOAS and AYY residents at the two biggest Universities in the Helsinki metropolitan area (HMA), Finland. A total of 187 residents took part in an online survey. The aim of the study is to investigate the association between experiences of nature, environmental identity, and environmental concern. This master’s thesis explores how the experiences of nature (EoN) defined by Clayton and others (2017), as well as the environmental identity, determined by Clayton (2003), were associated with environmental concern. The survey consisted of questions about environmental identity and experiences of nature. The self-estimation about the environmental concern was also taken into consideration. The data were analyzed both via quantitative and qualitative methods, so mixed methods were applied in this study. Factor analysis from multivariate methods was conducted as a part of the quantitative analysis. Content analysis with topic modeling was performed as part of the qualitative analysis. Survey results from the quantitative analysis showed that the residents of HOAS and AYY experience nature mostly as integrated into their daily lives and routines. Yet, the qualitative analysis revealed that more complex nature connections were experienced during vacation times such as leisure time activities (e.g., boating and trekking). Also, experiences of nature are themed under three themes using the results of the factor analysis. Overall, the survey participants were very concerned about the environmental crisis, and they showed a very strong environmental identity. The correlation between EoN and environmental concern was the weakest, and there were stronger correlations between environmental identity and EoN or environmental concern. The result of this study supports Clayton’s (2003) theoretical model that there is a connection between environmental identity and environmental concern.
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Experiencias de los alumnos de primaria finlandesa sobre el aprendizaje de español extracurricular (2019)Tutkielma käsittelee suomalaisen alakoulun oppilaiden kokemuksia espanjan kielen opiskelusta kerhossa. Tavoitteena on tutkia lasten osallistumiseen vaikuttaneita tekijöitä, oppimismotivaatiota ja tapaa oppia vierasta kieltä. Tutkimus tuo uutta tietoa espanjan kielen oppimisen kokemuksista ja toiminnallisesta kielenopetuksesta lapsen näkökulmasta. Tutkielma koostuu viidestä osasta. Ensimmäinen osa käsittelee suomalaisissa kouluissa pidettävien kerhojen pedagogiikkaa ja suomalaista kielten opetusta sekä kyseessä olevan kielikerhon opetusmetodeja ja tuntien sisältöjä. Toisessa osassa esitellään tutkielman teoriataustaa yleisesti ja erityisesti vieraan kielen oppimisen motivaatioteorioita. Tutkimuksen metodologia ja aineisto kuvataan kolmannessa osassa ja neljäs osa koostuu tulosten esittelystä ja niiden analyysista sekä pohdinnasta. Viidennessä ja viimeisessä osassa tarkastellaan tutkimuksen luotettavuuteen liittyviä tekijöitä ja lopuksi tehdään johtopäätökset tutkielmasta. Aineisto kerättiin haastattelemalla espanjan kerhon oppilaita. Haastateltaviksi pyydettiin niitä oppilaita, jotka olivat osallistuneet aktiivisesti kerhon tunneille. Haastattelu perustui vapaaehtoisuuteen. Tutkimukseen osallistui 11 oppilasta; kolme 3.-luokkalaista, neljä 4.-luokkalaista ja neljä 5.-luokkalaista. Tutkielmassa käytettiin fenomenologista lähestymistapaa eli tutkimuskohdetta lähestyttiin ilman ennakko-olettamuksia ja tarkasti rajattua teoreettista viitekehystä. Tutkimusmenetelmänä käytettiin laadullista eli kvalitatiivista analyysia. Tutkimuksen keskeisimmät tulokset liittyivät oppilaiden motivaatioon opiskella, työskentelytapoihin ja heidän käsitykseensä espanjan kielestä. Tulosten perusteella voitiin havaita, että oppilailla oli omakohtainen halu oppia espanjan kieltä ja kiinnostus kieltä kohtaan. Kieli koettiin erikoisena ja erilaisena verrattuna aikaisempiin kielikokemuksiin ja sen oppiminen oli oppilaiden mielestä hauskaa. Mieluisin työskentelytapa oli yhdessä työskentely, kuten pari- tai ryhmätyöt. Oppiminen erilaisten leikkien ja pelien avulla nousi myös tutkimukseen osallistuneiden oppilaiden keskuudessa näkyvästi esiin positiivisena kokemuksena.
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(2017)Tämä tutkielma tarkastelee termejä, joita evidentiaalisuuskategorioista on käytetty kieliopeissa ja muissa kielten kuvauksissa. Evidentiaalisuus on funktionaalinen domeeni, joka tarkoittaa tiedonlähteen tai tiedon saannin il-maisua: puhuja on voinut saada tietonsa esimerkiksi näkemällä tapahtuman, päättelemällä sen jäljelle jääneistä merkeistä tai kuulemalla siitä muilta. Kaikki kielet voivat ilmaista evidentiaalisuutta, mutta vain joissakin sen kieliopillistunut omaksi kategoriakseen. Tutkielma tarkastelee juuri kieliopillisia evidentiaalisuuskategorioita ja niistä käytettyjä termejä. Aihetta lähestytään niin kieltenvälisen vertailun kuin terminologian näkökulmasta. Lisäksi tutkielmassa esitellään myös evidentiaalisuutta ilmiönä sekä sen tutkimushistoriaa: erityisesti keskitytään evidentiaalisuuden määrittelyn näkökulmiin ja ongelmiin. Kielten vertailuun vaikuttaa näkemys kategorioista. Universalistisen näkö-kulman mukaan kielten kategoriat ovat pohjimmiltaan samoja, mutta partikularistisen näkemyksen, jota tässä tutkielmassa noudatetaan, kielten kategoriat ovat aina erilaisia, mutta voivat olla samankaltaisia. Tällöin vertailu toteutetaan käyttämällä vertailukäsitteitä, jotka perustuvat semanttisiin ja funktionaalisiin ominaisuuksiin. Kiel-ten yksilölliset kategoriat, jotka on kuvattu ja määritelty kunkin kielen omilla ehdoilla, ovat sen sijaan kuvauska-tegorioita. Käytännön syistä olisi hyvä, jos vertailukäsitteistä ja kuvauskategorioista käytettäisiin samoja termejä, mutta toisaalta on toivottavaa, että kuvauskategorioiden termit kuvastaisivat juuri kyseistä kategoriaa. Lisäksi on yleisiä terminologisia ihanteita, kuten erottuvuus ja monosemia, eli termien tulisi erottua toisistaan ja kutakin käsitettä tulisi vastata yksi termi ja kutakin termiä yksi käsite. Tutkielma tarkastelee myös tällaisten kriteerien toteutumista evidentiaalisuuden terminologiassa. Tutkielman aineistona on 51 kielen evidentiaalisuusjärjestelmät, joiden tiedot on kerätty 57 eri kieliopista tai muusta kuvauksesta. Kieliopeista poimitaan evidentiaalisuuskategorioiden termit ja niiden määritelmiä verra-taan eri evidentiaalisuuskategorioiden vertailukäsittesiin, minkä jälkeen kuhunkin vertailukäsitteisiin sopivien kategorioiden termit kerätään yhteen ja niitä verrataan toisiinsa. Tutkielmassa selviää, että evidentiaalisuuskategorioista käytetty terminologia on runsasta ja vaihtelevaa. Polysemiaa ja etenkin synonymiaa esiintyy paljon, mikä haittaa termien ymmärrettävyyttä ja erottuvuutta. Ter-mien runsaus selittyy osittain evidentiaalisuuden lyhyehköllä tutkimushistorialla, jonka takia termit eivät ole ehti-neet vakiintua. On myös mahdollista, että evidentiaalisuus ilmiönä on edelleenkin heikommin tunnettu kuin jotkin toiset kieliopilliset ilmiöt, jolloin myös käsitteistön vakiintumattomuus synnyttää terminologista vaihtelua. Toi-saalta, kielten kategorioissa on eroja, minkä on syytä heijastua myös terminologiaan. Runsasta terminologista vaihtelua löytyykin ei-visuaalisen sensorisen evidentiaalisuuden sekä eri päättelytyyppien kategorioissa, jotka ovat semanttisesti monitahoisia. Tutkielman aineistosta löytyi myös yllättävän monta yleistiedon ja ego-evidentiaalisuuden kategoriaa, vaikka näitä kategorioita ei välttämättä ole otettu huomioon evidentiaalisuustypo-logioissa.
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(2011)The Hodgkin and Huxley (HH) model of action potential has become a central paradigm of neuroscience. Despite its ability to predict action potentials with remarkable accuracy, it fails to explain several biophysical findings related to the initiation and propagation of the nerve impulse. The isentropic heat release and optical phenomena demonstrated by various experiments suggest that action potential is accompanied by a transient phase change in the axonal membrane. In this study a method was developed for preparing a giant axon from the crayfish abdominal cord for studying the molecular mechanisms of action potential simultaneously by electrophysiological and optical methods. Also an alternative setup using a single-cell culture of an Aplysia sensory neuron is presented. In addition to the description of the method, the preliminary results on the effect of phloretin, a dipole potential lowering compound, on the excitability of a crayfish giant axon are presented.
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(2015)Perovskites are a class of materials that possess many interesting properties with a wide range of technological applications in the field of optoelectronics and photovoltaics. In recent years, perovskites have gained considerable attention as an inexpensive and easy-to-synthesize light absorbing material for so-called organic-inorganic solar cells. In this study we wish to examine the structural and electronic properties of CH3NH3PbI3 organohalide lead perovskites. Charge transport behaviour between the light harvesting perovskite and the underlying electron transport mesostructure are some of the factors that affect the Power Conversion Efficiencies (PCE) of these devices. Therefore, advanced characterization methods were used to investigate the structural and electronic changes that may occur at the interface. Scanning electron microscopy (SEM) was used to survey the structure and morphology of the samples. It was found that the titania grain sizes were 20-25 nm in size and the perovskite grain sizes from 200 nm to 500 nm. The samples were prepared using a solution processing method, which is widely considered as one of the most cost effective ways for crystal growth. However, our studies show that this method does not provide a full perovskite coverage of the surface (14.4% of surface uncovered) which reduces the light harvesting yield. X-ray diffraction (XRD) was employed to study the crystal structure of the sample. It was concluded that the titania was in the anatase phase and the perovskite in a tetragonal crystal system (space group: I4/mcm), with a cell size of a=8.89 A and c=12.68 A. Moreover, our XRD results reveal the existence of a PbI2 crystal phase, indicating an incomplete conversion of the precursors to the perovskite phase. In order to probe the changes that occur at the interface and to elucidate the electron transport mechanisms, X-ray photoelectron spectroscopy (XPS) was conducted and the core-level spectra was investigated. A shift of 0.44 eV in the binding energy of the Ti 2p line was observed between the titania samples and the titania/perovskite. We hypothesize the origin of this shift to be due to a local screening effect, or the formation of a barrier between the perovskite and the titania that is hindering charge transport and is preventing the compensation for the surface charges lost during photoionization. Based on the findings presented in this thesis we suggest, as a possible research direction for the future, UV Photoelectron Spectroscopy (UPS) for constructing the band alignment schemes with the PbI2 layer included and a thorough investigation of the substrate effects and the synthesis routes on the charge transport dynamics of these systems.
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(2020)Inductively coupled mass spectrometry (ICP-MS) is a state-of-the-art technique for elemental analysis. The technique allows fast and simultaneous analysis of multiple elements with a wide dynamic range and low detection limits. However, multiple adjustable parameters and the complex nature ICP-MS instruments can make the development of new analysis methods a tedious process. Design of experiments (DOE) or experimental design is a statistical approach for conducting multi- variate experiments in a way that gives maximal amount of information from each experiment. By using DOE the number of experiments needed for analytical method optimization can be minimized and information about interrelations of di↵erent experimental variables can be obtained. The aim of this thesis is to address the utilization of DOE for ICP-MS method developement as a more e cient mean to optimize analytical methods. The first part of this two part thesis gives an overview on the basics of ICP-MS and DOE. Then a literature review on applying experimental design for ICP-MS method optimization is given and the current state of the research is discussed. In the second part, two new ICP-MS methods for simultaneous determination of 28 elements from six middle distillate fuels, diluted with xylene or kerosine, are presented. The method developement involved optimization of the integration times and optimization of test sample dilution ratios and viscosities using univariate techniques. In addition, experimental designs were succesfully utilized together with desirability approach in multivariate optimizations of the plasma conditions and sample matrix compositions to achieve the best possible analyte recoveries from various matrices.
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(2020)Earlier, vast majority of the experiment were performed with PIXE exclusively, with protons as an impinging particle. Due to the concurrence of various phenomena in nuclear and atomic physics like the significant development of the theory of the inner-shell ionization in ion-atom collision, higher sensitivity due to heavy-ions, larger scattering cross-section and larger stopping cross-section HIXE turns out to be a useful technique. While cross-section of heavy-ion beam at energy few MeV and above have been measured and reported, experimental data for high-energy heavy ions against heavy targets are lack. In this study, X-ray production cross-section induced by iodine ions with energies from 15MeV to 45MeV, produced by 5MV tandem accelerator, have been measured for multiple compounds of thin targets of Ti, Cu, Zn, Ru, Nb, Ta, W and Au in a direct way. Simultaneous measurement of the X-ray data and ERDA data were taken with the help of the x-ray detector and ERDA detector placed at an angle of 1200 and 300 respectively. Measured cross-section was compared against the ECPSSR and ECPSSR-UA cross-section calculated by the program ISICS11. Experimental cross-section was found above both of the ECPSSR and ECPSSR-UA data. Thickness of the target from ERDA data were used for the direct calculation of the X-ray production cross-section for 15MeV iodine energy beam. Additionally, measured cross-section along with the ECPSSR data was compared against the average reduced velocity parameter.
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(2015)During the recent years, there has been an increasing interest among both biologists and mathematicians to model and understand gene regulatory mechanisms that drive cell differentiation processes. Mathematical modeling of these processes is often based on the assumption of homogeneous cell population. However, in many applications the cell populations of interest can be heterogeneous. For example, CD4+ T cell populations that are studied in this thesis may consist of many distinct T helper (Th) cell subtypes. Consequently, cell populations in cell differentiation studies are inevitably heterogeneous. In this thesis, we develop a new modeling approach that takes the possibility of a heterogeneous population into account and apply this approach to study the Th17 cell differentiation. More specifically, we design ordinary differential equation (ODE) models that take the heterogeneity into account by describing approximative subpopulations that evolve in parallel within a population and have cell type specific regulatory mechanisms and dynamics. In our application, we allow the cell population to be split into two subpopulations, an activated T helper (Th0) cell subpopulation and an actively differentiating Th17 cell subpopulation. Both Th0 and Th17 cell dynamics share the same rate parameters to describe the common reaction mechanisms within the subtypes. Three models, homogeneous population (M1), replicate-independent heterogeneous population (M2) and replicate-dependent heterogeneous population (M3), are constructed. In order to infer Th17 cell differentiation dynamics and to detect possible heterogeneity during differentiation in a data-driven manner, we combine mathematical modeling with RNA sequencing (RNA-Seq) data using statistical modeling. To carry out posterior analysis, we use Bayesian inference with population-based Markov chain Monte Carlo (popMCMC) sampling method. Our results show strong evidence for the replicate-dependent heterogeneous population model (M3) evolving in Th17 lineage polarizing condition. In addition, the model makes it possible to predict the resulting molecular dynamics.
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(2021)High-intensity and -amplitude focused ultrasound has been used to induce cavitation for decades. Well known applications are medical (lithotripsy and histotripsy) and industrial ones (particle cleaning, erosion, sonochemistry). These applications often use low frequencies (0.1-5 MHz), which limits the spatial precision of the actuation, and the chaotic nature of inertial cavitation is rarely monitored or compensated for, constituting a source of uncertainty. We demonstrate the use of high-frequency (12 MHz) high-intensity (ISPTA=90 W/cm2 ) focused-ultrasound- induced cavitation to locally remove solid material (pits with a diameter of 20 µm to 200 µm) for non- contact sampling. We demonstrate breaking cohesion (aluminium) and adhesion (thin film on a substrate, i.e. marker ink on microscope glass). The eroded surfaces were analyzed with a scanning acoustic microscope (SAM). We present the assembly and the characterization of a focused ultrasound transducer and show quantification of the effect of different sonication parameters (amplitude, cycle count, burst count, defocus) on the size and shape of the resulting erosion pits. The quantitative precision of this method is achieved by systematic calibration measurements, linking the resulting erosion to acoustic parameters to ensure repeatability (sufficient probability of cavitation), and inertial cavitation monitoring of the focal echoes. We discuss the usability of this method for localized non-contact sampling.
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(2013)Nowadays, home gateways such as Wireless Access Points(APs), Cable or DSL modems are widely deployed for residential and Small Office/Home Office (SOHO) customers to access Internet services. The home gateways typically act as middleboxes performing various higher-layer functions, such as network address translation (NAT), traffic filtering or advanced application layer operations. The exact behavior of these functions are not standardized, and they are often undocumented by the home gateway vendors. However, such middleboxes are known to have undesired interactions with normal protocol operation, and they substantially hinder and complicate new protocol development and prevent new protocol extensions from working. For this reason, it is important to learn the deployed middlebox characteristics to allow network engineers design protocols that can be deployed in realistic environments that typically include middleboxes. In this thesis, the main purpose is to explore the characteristics and unknown behavior of various home gateways which are already widely deployed everywhere. In order to achieve this goal, numerous home gateways from different vendors are deployed into our home gateway test-bed and a set of well-designed software is developed to reveal the realistic behavior of these devices under various circumstances and conditions. Also, in order to simplify the experimental procedures, the home gateway test system automation is utilized to intelligently and systematically organize multiple measurements on all the devices in our testbed. Our experiments emphasize on the latest protocols such as Lightweight User Datagram Protocol (UDP-Lite), Data Congestion Control Protocol (DCCP), Stream Control Transmission and Datagram Protocol (UDP). Moreover, the maximum number of UDP bindings, UDP throughput performance and UDP broadcast experiments are included to comprehensively learn how the home gateway handles UDP traffic in practise. The experimental results indicate that NAT functionality indeed prevents new protocols such as SCTP, DCCP and UDP-Lite from operating over current home gateway devices. In addition, home gateways significantly influence the UDP throughput performance for the residential users. Moreover, the experimental results indicates that the widely deployed home gateway devices perform a variety of NAT mapping, filtering and hairpinning behavior. Hence, it is extremely crucial to understand and benchmark the NAT behavior, while the existence of middleboxes should also not be ignored by protocol designers.
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(2022)Biological soil crust, biocrust, is a significant contributor to biogeochemical cycles through nitrogen and carbon cycling. Further, it stabilizes soil, facilitates water infiltration, and mitigates soil erosion. The global biocrust cover is believed to decrease by about 25-40% in the next 60 years due to climate change and intensification in land use. Research on biocrust in arctic and subarctic regions is limited, much of the knowledge comes from lower latitudes in arid and semiarid ecosystems. Cold-adapted biocrust might respond differently to increasing temperatures when compared with warm-adapted biocrust. Therefore, it is fundamental to research biocrust in arctic and subarctic regions when looking at how fast the climate is changing in the Northern hemisphere. Temporal variations of soil respiration in subarctic biocrust have not been studied systematically before. This research project focuses on the effects of warming on soil respiration in biocrust, on a diurnal and a seasonal scale. It also focuses on species composition changes of vascular plants in the warming experiment where warming was induced with open-top chambers (OTCs). Soil respiration, temperature, soil water content, as well as plant species composition changes were measured during three field trips that each lasted four days during the growing season of 2021. The results show that soil respiration was lower in September when compared with measurements done in June and July. The highest values of soil respiration were observed during mid-day and the lowest during evenings and nights. The temperatures of OTC plots were, on average, 1.16 °C higher than control plots, and OTC plots had significantly lower soil water content than control plots. During this research, the soil respiration increased with higher temperature but was not different between control and OTC plots during any time of day or month measured. Soil water content did not affect soil respiration significantly, while temperature did. These findings might be explained by less soil water content within warmer plots, but warmth and moisture have been shown to increase soil respiration. In other words, less soil water content might countereffect the increase of soil respiration due to warming. Some vascular plant species were more likely to be found within or outside the warming plots. Dwarf willow, Salix herbacea, decreased in cover within OTC plots. Previous research has shown that warming significantly reduces pollen shed and time of pollen shedding for S. herbacea, which might decrease its abundance within OTC plots. Alpine bistort, Bistorta vivipara, increased in cover within OTC plots compared to control plots. Warming experiments on B. vivipara have shown positive effects on reproductive parameters, which might increase its abundance within warmed OTC plots. Sheep also prefer grazing on B. vivipara. Therefore, it might have less cover in control plots, given that OTCs exclude grazing and that many sheep roam the studied site during the growing season. Vascular plant cover was greater within control plots when compared with warmed plots. Previous results at the same site after one year of warming, from summer 2019, showed more vascular plant cover within the OTC plots when compared with control plots. The results of this research might indicate that vascular plants are gradually affected by the warming and are transitioning towards a new equilibrium. The results of this research are ground for further studies on subarctic ecosystems dominated by biocrust. Many biotic and abiotic factors affect carbon cycles. For future modelling of predicted effects of climate change, having better knowledge on how subarctic ecosystems respond to warming is essential for a better understanding of the functions and feedbacks in a global context.
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