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(2016)Bézout's theorem, at least the original version, concerns the number of intersection points of two curves in projective plane. The main purpose of this thesis, apart from proving the classical version of Bézout's theorem, is to give multiple generalizations for it. The first proper chapter, Chapter 2, is devoted to the proof of classical Bézout's theorem. In the first two sections of the chapter we define projective and affine plane curves, and show some of their basic properties. In the third section we define the resultant of two polynomials, and use the newly acquired tool to prove the upper bound version of Bézout's theorem. The fourth section discusses the multiplicity of a point of intersection. This multiplicity, dependent of algebraic data associated to the intersection, is needed for stating the equality version of the classical Bézout's theorem. In the fifth section we prove this using properties of the intersection multiplicity proved in the fourth section. The third chapter extends the classical Bézout's theorem beyond its original scope. In Section 3.1 we define a crucial tool, Hilbert polynomial, which allows us to keep track of algebraic information associated to the projective scheme cut out by a homogeneous ideal. This polynomial is not an invariant of the scheme itself; rather it should be thought as containing information concerning both the intrinsic structure of the subscheme, and about how the subscheme is located in the ambient projective space. The second section of the third chapter quickly summarizes the parts of modern algebraic geometry that are of most use later. Section 3.3 gives the first proper generalization of Bézout's theorem. This generalization is more a quantitative than a qualitative one, as it deals with intersections of projective hyperplanes. The fourth chapter gives a generalization of the upper bound version of the Bézout's theorem to a very general case. We define the geometric multiplicity of a closed subscheme of a projective space, and show that it behaves well under intersections. The geometric multiplicity gives an upper bound for the number of components, hence the generalization of inequality version of Bézout. In the final section, 3.5, we define Serre's multiplicity of a component of intersection, and show that the multiplicities given by this formula satisfy the equality version of Bézout's theorem in proper intersections of equidimensional subchemes.
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(2015)Tietovarannoissa esiintyy monesti useita tietueita, jotka kuvaavat samaa objektia. Tässä tutkielmassa on vertailtu näiden tietueiden löytämiseen käytettäviä menetelmiä. Kokeet on suoritettu aineistolla, jossa on 6,4 miljoonaa bibliografista tietuetta. Menetelmien vertailussa käytettiin aineistossa olevien teosten nimekkeitä. Eri menetelmien kahta keskeistä piirrettä on mitattu: löydettyjen duplikaattien lukumäärää ja niiden suhdetta muodostettujen kandidaattien lukumäärään. Kahden menetelmän yhdistelmä osoittautui parhaaksi aineiston deduplikointiin. Järjestetyllä naapurustolla löytyi eniten varsinaisia duplikaatteja, mutta myös eniten irrelevantteja kandidaatteja. Suffiksitauluryhmittelyn avulla löytyi lisäksi joukko duplikaatteja joita muilla menetelmillä ei löytynyt. Yhdessä nämä kaksi menetelmää löysivät lähes kaikki duplikaatit mitä kaikki tutkielmassa verratut menetelmät löysivät. Levenshtein-etäisyyteen perustuvat virhesietoiset menetelmät osoittautuivat tehottomiksi nimekkeiden deduplikoinnissa.
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(2015)Big data creates variety of business possibilities and helps to gain competitive advantage through predictions, optimization and adaptability. Impact of errors or inconsistencies across the different sources, from where the data is originated and how frequently data is acquired is not considered in much of the big data analysis. This thesis examines big data quality challenges in the context of business analytics. The intent of the thesis is to improve the knowledge of big data quality issues and testing big data. Most of the quality challenges are related to understanding the data, coping with messy source data and interpreting analytical results. Producing analytics requires subjective decisions along the analysis pipeline and analytical results may not lead to objective truth. Errors in big data are not corrected like in traditional data, instead the focus of testing is moved towards process oriented validation.
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(2019)The number of bike-sharing systems has increased rapidly during the last decade. These systems expand urban mobility options and provide a solution to the so-called “last-mile” problem. While new bike-sharing systems are opened and current ones expanded in Finland and elsewhere in large numbers, it is important to understand how these systems are used and by whom. Despite the wealth of bike-sharing literature, usage patterns by different user groups are still not yet well studied. This knowledge is needed to ensure that the benefits of bike-sharing systems distribute as evenly as possible to the citizens. In this study, I have employed a person-based approach to study mobility patterns of bike-sharing users in Helsinki. The system in Helsinki was opened in 2016 and the urban bikes quickly became popular among citizens. I have aimed to understand how equally the bike-sharing system in Helsinki is serving the citizens and how different user groups have differed from each other in their use. I have also studied how the system is linking to public transport in Helsinki and compared the bike-sharing system usage and users in Helsinki to other systems internationally. These specific questions stem from the systematic literature review on bike-sharing (n=799), which I carried out before the empirical study. In this study, I have used a dataset provided by Helsinki Region Transport, which contained all the bike-sharing trips (~1.5 million) from 2017. Besides the trip information, the dataset contained the basic demographic information of the user. The results of literature review show bike-sharing systems have been an active and extensive study topic even though the study areas are mostly concentrated to certain cities. Based on the empirical data-analysis, majority of bike-sharing users are young adults between 25-35 years old whereas the share of over 50 year olds is only 12 %. Both men and women use urban bikes actively but men are overrepresented both in the number of users and trips. The use of bikes is not equal but a small minority of users have generated the majority of trips. The users who live inside the bike station coverage area make around 80 % of the trips implying that the proximity of a station has a considerable impact on the use. Trip profiles of those living inside the system coverage area differ considerably from those who live outside the area. For example, the users living inside the area seem to combine urban bikes less with public transport and they use urban bikes relatively more on weekends compared to the other group. The subscription type and use activity are also important factors shaping usage patterns. Then again, age and gender are more important in determining whether someone chooses to become a user than in shaping usage patterns. The use of bike-sharing system in Helsinki has been high even when compared internationally. The results of this study show that the high usage rates still do not necessarily mean that the system would be equally used by citizens. Based on the systematic review, equity is a critical topic to address in relation to bike-sharing users. The user profiles in Helsinki seem to follow similar patterns of bike sharing as found in other cities with an overrepresentation of certain population groups. The use of young adults might promise well for the change of urban mobility. However, it is important to keep promoting cycling to a wider range of the population. The bike-sharing system in Helsinki will expand in 2019 to new areas. Based on the results of this study the expansion seems reasonable as a large part of the users live close to a bike-sharing station. The expansion will then bring the full benefits of bike sharing accessible to a larger group of people in Helsinki. The system seems both to replace and extend the public transport system, which is common to bike-sharing systems in many cities. From the data perspective, the origin-destination type of trip data, which was used in this study, provided a great deal of useful information about users and usage profiles. Even when accounting for limitations in this data type, it is still an excellent addition complementing existing cycling data sources.
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(2020)Tässä pro gradu -tutkielmassa käsitellään binomijakauman luottamusjoukkojen analysointimenetelmiä laajentaen niitä multinomijakauman luottamusjoukkojen tarkasteluun. Tutkielman tarkoituksena on vertailla valikoituja binomi- ja multinomijakaumien luottamusjoukkoja sekä binomijakauman luottamusjoukkojen vertailukriteereitä yleistäen niitä multinomijakauman luottamusjoukoille soveltuvin osin. Luottamusjoukkojen määrittelyssä on käytetty frekventististä päättelyä. Vertailuun valikoitujen vakiintuneiden binomijakauman luottamusjoukkojen lisäksi tyossä määritellään kaksi muuta luottamusjoukkoa. Näitä luottamusjoukkoja vertaillaan kahdeksan esitellyn vertailukriteerin perusteella. Luottamusjoukkojen tutkimisessa erityisesti peittotodennäköisyys osoittautuu hyödylliseksi menetelmäksi. Multinomijakauman luottamusjoukkoja esitellään kolme yleisesti käytössä olevaa sekä yksi vertailuun kehitetty luottamusjoukko. Multinomijakauman luottamusjoukoille yleistetään peittotodennäköisyys, jonka avulla luottamusjoukkoja analysoidaan. Esiteltyjä luottamusjoukkoja vertaillaan yhden yleistetyn kriteerin avulla. Tuloksina käydään läpi esitellyt luottamusjoukot, sekä arvioidaan niiden soveltuvuutta erilaisiin tutkimustilanteisiin pienillä havaintomäärillä. Luottamusjoukkojen peittotodennäköisyyden avulla joukkojen erilaiset ominaisuudet erottuvat selkeästi. Arvioidut vertailukriteerit yleistyvät multinomijakauman luottamusjoukoille pääosin hyvin.
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(2021)Carbon monoxide (CO) is a chemically reactive trace gas in the atmosphere, indirectly affecting radiative balance. The oxidation of CO with hydroxyl radical (OH) is the large sink of atmospheric CO. The reactions of CO and OH decrease the atmospheric capacity to oxidize atmospheric methane (CH4), hence indirectly extends the lifetime of CH4 in the atmosphere. In addition, CO oxidation increases the abundance of tropospheric ozone (O3). CH4 and O3 are both very strong greenhouse gases, and it has been estimated that the cumulative indirect radiative forcing of CO can be even more significant than the third most powerful greenhouse gas, nitrous oxide. This study studied CO fluxes in four different ecosystems: a boreal forest, a boreal fen, a cropland in the boreal region, and a sisal plantation in the semi-arid tropical zone. All the ecosystems were CO sources during the growing season from May to August, and ecosystems showed strong seasonal variation. Fluxes had a regular diurnal cycle, peaking at noon and zero flux or small uptake at night. The main drivers for the CO emissions were radiation and air temperature. The strong correlation between radiation and CO flux proved that photodegradation was an important process in biogenic CO emissions. Radiation and air temperature were used in a simple linear regression model to estimate the biogenic CO emissions in the study sites. The model was trained for Hyytiälä data in 2016, tested for the rest of the data from Hyytiälä in 2015 and 2017 and other sites. The chamber measurements showed that soils were CO sinks and CO emissions were mainly from vegetation. Generally, in many upscaling models of CO, soil consumption is considered significantly larger than photodegradation. This study showed that many terrestrial ecosystems can be sources of CO, even though there are generally considered as a sink of CO. There is a need for ecosystem-scale flux measurements in other ecosystems and latitudes to understand better the global CO budget.
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(2020)Biogenic Volatile Organic Compounds play a major role in the atmosphere by acting as precursors in the formation of secondary organic aerosols and by also affecting the concentration of ozone. The chemical diversity of BVOCs is vast but global emissions are dominated by isoprene and monoterpenes. The emissions of BVOCs from plants are affected by environmental parameters with temperature and light having significant impacts on the emissions. The Downy birch and Norway spruce trees consist of heavy and low volatile compounds but published results are limited up to observing sesquiterpenoid emissions from these two trees. In this study, the Vocus proton-transfer-reaction time-of-flight mass spectrometer is deployed in the field to examine BVOC emissions from Downy birch and Norway spruce trees. With higher mass resolution, shorter time response and lower limits of detection than conventional PTR instruments, the Vocus can effectively measure a broader range of VOCs. For the first time, real-time emissions of diterpenes and 12 different oxygenated compounds were observed from birch and spruce trees. The emission spectrum of birch was dominated by C10H17+, while for spruce C5H9+ contributed the most. The sum emissions of oxygenated compounds contributed significantly to the observed total emissions from both the trees. The emission rates of all compounds varied dramatically throughout the period due to fluctuations in temperature and light. Due to lack of data from spruce, conclusive results for temperature and light response on terpene emissions could not be drawn. For birch, the emission rates were well explained by the temperature and temperature-light algorithms. The terpene emissions modelled using both algorithms correlated similarly with experimental data making it difficult to decisively conclude if the emissions originated from synthesis or pools.
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(2020)Tutkielman kirjallisuusosuudessa on käyty läpi erilaisia kaupallisia biopolymeerejä, niiden synteesiä, käyttöä ja biohajoamista. Tutkielman pääpaino on erilaisten materiaalien biohajoamisessa ja näiden materiaalien kaupallisessa käytössä. Biohajoamisen evaluointiin tarkoitettuja standardeja, tutkimusmenetelmiä ja hyväksyntäkriteerejä on esitelty laajasti. Tutkimusosuudessa on valmistettu PLA:n ja PBAT:n seoksesta puukomposiitti ja materiaalin termomekaaniset ominaisuudet on karakterisoitu. Tavoitteena oli luoda biohajoava materiaali, jonka ominaisuudet ovat sellaisia, että sen kaupallinen hyödyntäminen kertakäyttömuovin korvikkeena on järkevää. Materiaalin mekaaniset ominaisuudet karakterisoitiin lopputuotteen kestävyyden, ja sulaominaisuudet kaupallisen tuotannon mahdollistamisen takia. Termomekaanisia analyysejä tehtiin materiaalin säilyvyyden ja lämpöominaisuuksien karakterisoimiseksi. Työssä on tutkittu myös puhtaan PLA/puukomposiitin biohajoamista meriympäristössä. Tutkimuksen tuloksena saatiin luotua riittävällä nopeudella biohajoava puukomposiitti, jonka mekaaniset ominaisuudet ovat riittäviä korvaamaan erilaisia kertakäyttöisiä muovituotteita ja joka on prosesoitavissa nykyisillä ekstruusiolaitteistoilla.
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(2021)Acute lymphoblastic leukemia (ALL) is a hematological malignancy that is characterized by uncontrolled proliferation and blocked maturation of lymphoid progenitor cells. It is divided into B- and T-cell types both of which have multiple subtypes defined by different somatic genetic changes. Also, germline predisposition has been found to play an important role in multiple hematological malignancies and several germline variants that contribute to the ALL risk have already been identified in pediatric and familial settings. There are only few studies including adult ALL patients but thanks to the findings in acute myeloid leukemia, where they found the germline predisposition to consider also adult patients, there is now more interest in studying adult patients. The prognosis of adult ALL patients is much worse compared to pediatric patients and many are still lacking clear genetic markers for diagnosis. Thus, identifying genetic lesions affecting ALL development is important in order to improve treatments and prognosis. Germline studies can provide additional insight on the predisposition and development of ALL when there are no clear somatic biomarkers. Single nucleotide variants are usually of interest when identifying biomarkers from the genome, but also structural variants can be studied. Their coverage on the genome is higher than that of single nucleotide variants which makes them suitable candidates to explore association with prognosis. Copy number changes can be detected from next generation sequencing data although the detection specificity and sensitivity vary a lot between different software. Current approach is to identify the most likely regions with copy number change by using multiple tools and to later validate the findings experimentally. In this thesis the copy number changes in germline samples of 41 adult ALL patients were analyzed using ExomeDepth, CODEX2 and CNVkit.
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(2016)Litteraturgranskningen i denna pro gradu behandlar oxidation av inerta C-H-bindningar med järnbaserade icke-hemkomplex. Naturligt förekommande enzymers aktiva centrum har använts som inspiration vid utveckling av katalytiska komplex. Forskningsområdet har attraherat stort intresse en längre tid eftersom kemiindustrins utgångsämnen är huvudsakligen ofunktionaliserade kolväten som utvinns ur råolja. Ett stort genombrott gjordes år 2001 då det syntetiserades ett järnkomplex vars katalytiska cykel involverade en metallcentrerad FeV=O-oxidant. Kolväten oxiderades avsevärt effektivare jämfört med tidigare komplex som oxiderade substrat via fria radikaler. Sedan dess har utvecklingen skett snabbt. Det har bevisats att ligandgeometrin påverkar kraftigt den katalytiska aktiviteten. Komplex med cis-α-geometri har den bästa aktiviteten. Oxidationsselektiviteten baserar sig på sterisk växelverkan mellan substrat och ligand, samt elektroniska och stereoelektoniska egenskaper hos substratet. Dessa faktorer kan överskridas om substratet har en dirigerande karboxylsyra. Steriskt hindrade ligander förlänger den katalytiska livstiden och förbättrar oxidationsselektiviteten. Det har nyligen föreslagits en alternativ katalytisk cykel som involverar en FeIV=O-intermediär för komplex med en trigonal bipyramidstruktur. I framtiden kommer det att vara relevant att indela icke-hemkomplex i två olika undergrupper på basen av geometri och oxidationstillståndet av järn. I den experimentella delen presenteras syntesen för nya ligander. Dessa jämfördes med kommersiella ligander vid järnkatalyserad oxidation av etylbensen och cyklohexan. Oxidation av C-H-bindningar skedde enbart i närvaro av järn. Utbytet förbättrades varken av de nya eller kommersiella liganderna. Produktprofilen tydde inte på en metallcentrerad oxidant. Sannolikt bildades det långlivade alkylradikaler såsom i Gif-kemi.
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(2015)The evolution of biominerals, including teeth, has been an important step in the evolutionary diversification of organisms. For an organism, biominerals allow various advantages, such as ion storage, protection, food capture and processing, and locomotion. In mammals, tooth enamel is the hardest and most mineralized part of the body. Although tooth development is better known than that of many other organs, the maturation of enamel is still not completely understood. Enamel formation is a slow process biologically. In humans, the mineralization of the enamel in the first permanent molars starts at the time of birth, and the process continues even after the eruption of the teeth at the age of six years. Any disturbances during the enamel formation or other damage later in life will become permanent, as enamel does not reform. The aim of this work is to document the maturation of domestic pig molars, and use mineralogical and physics research methods to study enamel growth. The domestic pig (Sus scrofa domesticus) is a plant-dominated herbivore with large, bunodont molars. The relatively fast development of pig teeth together with their large size makes pig teeth a suitable model for comparisons of different methods. One of the methodological interests was to test if mineral grains can be used in computational microtomography for relative calibration of the absorption models. Three minerals (fluorapatite, quartz and siderite) were chosen by their physical and chemical features. The calibrated absorption models were compared with the results of more traditional methods, such as thin sections and hardness tests. X-ray diffraction and scanning electron microscopy were also used for structural studies. The results show that the microtomography is a valuable starting point for the traditional destructive methods used in the study of biomineralization, but does not substitute for the other methods. The mineral calibration was an efficient method for the microtomography-absorption models. Additionally, the calibration minerals allowed detection of microtomography artifacts better than using teeth only.
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(2012)Astrobiology is an interdisciplinary research field which studies the origin of life. One of the great challenges of modern observational astronomy in this area is to find building blocks of life in interstellar molecular clouds. These so-called biomolecules are under study in this thesis. First I present some fundamentals of radio spectroscopy and molecular structure. Then emphasis is put on observations made with the SEST- and APEX-telescopes of the objects NGC 6334F and IRAS 16293-2422. These objects represent the so-called hot cores. They are concentrations of gas and dust inside a molecular cloud where a new star is being born. One of the objectives in studying these hot sources is to find glycine NH2CH2COOH. Glycine is the most simple amino acid which means it is also a building block of our DNA. It has been hypothesised that several reaction chains may lead to glycine, either in gas phase or solid phase. Molecules that are part of the reaction chains that lead to glycine, are called precursors. Possible precursos of glycine are, for example, acetic acid and formic acid. The objective of this thesis is to find some of these precursors or their isomers. I have endeavoured to identify all molecular lines in the observed rotation spectra. This is done with the GILDAS/CLASS software package and specifically with its new Weeds extension. This has required estimation of the column density and then modifying its value until Weeds' model fits the observations. A lot of organic molecules were found. Glycine was not found and of its precursors only formic acid and methyl formate were found. However, the most interesting result was the detection of aminoethanol (NH2CH2CH2OH), which is a precursor of amino acid alanine (CH3NH2CHCOOH). Although this is only a tentative detection, it justifies a thorough investigation of future observations. Many of the observed spectral lines are blended so better resolution is needed. Many lines are also weak and are lost amid all the noise. The new ALMA interferometer will prove to be an invaluable tool in searching for new biomolecules. ALMA has very high angular and spectral resolution, high sensitivity, and large bandwidth. These properties are needed if we are to confirm or refute this new detection of aminoethanol.
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(2012)Plant-plant interactions, i.e. biotic interactions, shape plant communities and the vegetation's succession along abiotic environmental factors. Positive interactions (e.g. facilitation) may expand species niches and enhance growth and reproduction. Negative interactions (e.g. competition, allelopathy) can interfere with growth and reproduction, even out competing some species from their niches. Negative and positive interactions co-occur, but research has shown that positive interactions are generally more common and important than negative ones in harsh environments. The theory of change of net-interaction from negative to positive along an environmental gradient is called the stress gradient hypothesis (=SGH). This work examines nordic crowberry's (Empetrum nigrum ssp. hermaphroditum) effect on arctic-alpine species' sexual reproduction under different environmental stress levels. Crowberry is a dominant species in low-nutrient, acidic arctic-alpine ecosystems. Its competitive ability is based on allelopathic characteristics and a forming of dense mats. It is also unpalatable for herbivores. The species facilitative characteristics include providing shelter from the wind and maintaining an ericoidmycorrhiza community. In this research environmental stress is represented by geomorphological disturbance and soil moisture, with the interactions between crowberry and other species are examined as the relationship between crowberry cover and the fitness measures (e.g. abundance of flowers or fruits) of study species. Explanation for the variation in the effects of crowberry is tried to find from the traits of the study species. Data was collected in May 2011 from Kilpisjärvi, northernmost Finland. The study area comprised 960 1m2 cells. In each cell the cover of each species (including crowberry), the abundance of each species flowers or fruits, the cover of geomorfological disturbance and soil moisture were recorded. Generalized linear models (=GLM) were run for all species to identify the best model for predicting fitness (as selected by the AIC-criterion). Spatial autocorrelation was accounted for by repeating analyses using generalized estimation equation models (GEE), which explicitly account for the spatial structure of data. 17 species were included to the research based on the abundance of their flowers and berries in the research area. Crowberry is included in the best fit model for 14 out of 17 species. The effect of crowberry was positive for four species and negative for ten species based on the modeling results. Interactions of the crowberry and one of the environmental variables are included to the models 19 times. In ten of these cases the interactions agreed with the predictions of the SGH (i.e. effect of crowberry became less negative with increasing abiotic stress). No species traits were consistently related to the outcome of interaction between crowberry and environmental variable, although crowberry effects on dwarf shrub species appeared to be more commonly positive than on other growthforms. According to these results, crowberry has dominant role in arctic-alpine plant communities. The species effect on sexual reproduction of other plant species is commonly negative, but the effect can change to positive along environmental stress gradients, supporting the SGH. Dwarf shrubs may interact positively with crowberry because of sharing the same mycorrhiza type, while more generally species may benefit from crowberry due to its provisioning of shelter from the wind and increased soil moisture. The negative effect of crowberry might be related to its production of allelopathic compounds or its dense growth. The reason for crowberry having a facilitative affect under disturbed conditions might be an indirect effect of disturbance decreasing crowberry's allelopathic effects. These results show that the roles of crowberry and biotic interactions in arctic-alpine vegetation are important. Therefore understanding their effects and mechanisms is important in predicting how this vegetation will respond to changing climate.
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(2013)Uusien mittaustekniikoiden nopea kehittyminen tuo mukanaan yhä paremmat mahdollisuudet tutkia biologisten molekyylien välisiä vuorovaikutuksia. Erityisesti lääkkeiden kehityksessä on ensiarvoisen tärkeää saada tietoa lääkeaineen ja biologisten molekyylien välisistä vuorovaikutuksista, sillä esimerkiksi lääkeaineen sitoutuminen plasman proteiineihin vaikuttaa merkittävästi lääkeaineen imeytymiseen, leviämiseen, metaboliaan ja eliminaatioon kehossa. Tärkeää on myös saada tietoa proteiini-hiilihydraatti ja vasta-aine-antigeeni vuorovaikutuksista, sillä ne liittyvät biologisiin prosesseihin, kuten hormonien toimintaan ja tunnistamiseen sekä biologisten molekyylien varastointiin. Biologisten molekyylien analytiikka on haastavaa, koska niiden aktiivisuus ja ominaisuudet usein muuttuvat niitä käsiteltäessä. Näistä mainittakoon mm. entsyymin aktiivisuus, joka saattaa kadota ja proteiinien denaturoituminen. Biosensori on analyyttinen laite, jossa biologista tai biologisesti johdettua materiaalia on joko sidottu tai kokonaan integroitu fysikaalis-kemialliseen anturiin. Biosensorien kehittämisen tavoitteena on valmistaa systeemejä, joiden avulla voidaan tutkia soluja, solukalvoja ja niiden ympäristöä reaaliajassa. Tarkoitus on saada biologisista prosesseista luotettavaa tietoa, jota hyödynnetään ihmisten hyvinvoinnin parantamiseksi. Biosensorien pitäisi olla edullisia, kestäviä, luotettavia ja lääketieteelliseen tutkimukseen soveltuvia. Tämän pro gradu -tutkielman kirjallisessa osassa tarkastellaan kvartsikidemikrovaa'an (QCM) hyödyntämistä biosensorina. QCM on laite, joka mittaa elektrodiin liitetyn kvartsikiteen värähtelytaajuutta. Kun sensorin massa muuttuu, myös sen värähtelytaajuus muuttuu. Värähtelytaajuuden muutoksesta voidaan tehdä johtopäätöksiä elektrodin pinnalla tapahtuvista muutoksista. Itsemuodostuvien pintakerrosten (SAM) avulla sensoripintaa voidaan muokata biologisten molekyylien havaitsemiseksi. SAM-pintojen käyttö perustuu kullan ja tioliyhdisteiden väliseen voimakkaaseen ja spontaaniin vuorovaikutukseen. Tioliyhdisteet muodostavat kullan pinnalle tasaisen ja stabiilin molekyylikerroksen. Tämän kerroksen ominaisuuksia muokkaamalla voidaan vaikuttaa pinnan kemiallisiin ja fysikaalisiin ominaisuuksiin. Kirjallisessa osassa käsitellään QCM:n soveltuvuutta biosensoriksi immunoglobuliini E:n ja kloramfenikolin kvantitointiin, R- ja S-enantiomeerien erotukseen, solutukirankaan sitoutuvien lääkeaineiden tutkimiseen sekä seerumin vasta-ainemääritykseen. Tulokset ovat varsin lupaavia, vaikka QCM-laitteiston herkkyys ei vielä monissa sovelluksissa oikein riitä kvantitatiiviseen määritykseen. Myös sensoripinnan uudelleenkäyttö aiheuttaa vielä ongelmia. Pro gradu -tutkielman kokeellisessa osassa sovellettiin kapillaarielektrokromatografiaa (CEC) matalatiheyksisen lipoproteiinin (LDL) ominaisuuksien tutkimuksiin. CEC:ssä käytettävien 50 µm halkaisijan avoputkisilikakapillaarien sisäpinta päällystettiin LDL:llä, joka toimi stationaarifaasina. Kehitetyllä menetelmällä tutkittiin mm. LDL:ssa tapahtuvia muutoksia sokerikäsittelyn ja hapettumisen jälkeen. Tutkimuksissa hyödynnettiin elektro-osmoottista liikkuvuutta pinnassa tapahtuvien muutosten indikaattorina. CEC osoittautui hyväksi tekniikaksi biologisella materiaalilla helposti muokattavien kapillaaripintojen, lyhyiden analyysiaikojen ja vähäisten reagenssi- ja näytemäärien ansiosta.
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(2013)Multiple anthropogenic stressors on lake ecosystems demand effective measures towards improved protection and management of water bodies. The Water Framework Directive defines a common goal for sound water management and obliges EU member countries to monitor and protect the ecological status and water quality of all relevant surface waters. However, major problems hindering the attempts for effective water management are the lack of long-term observational data on reference status and an inadequate understanding of the responses of lake ecosystems to environmental pressures. With this regard, paleolimnological techniques are invaluable as they provide means to seek for past analogies of lake-environment interactions. Long-term development in the water quality and ecological status of Lake Storträsk, located in southern Finland, was assessed using a variety of paleolimnological proxies. The aim was to determine the reference status of this dystrophic lake, and to attain holistic understanding of late Holocene environmental changes and their influences on the lake's status. The principal hypothesis of the study was that late Holocene climate changes, catchment development and contemporary human activities have affected the status of the lake leaving records in the abiotic and biotic features of the sediment deposits. A 43-cm sediment core was obtained from the lake basin and studied for its physicochemical and biological attributes. The core was dated with radiometric methods, and a time frame of ca. 4500 years was established for the sediment sequence. Loss-on-ignition and magnetic susceptibility were measured and the elemental content of the sediment was assessed by ICP-MS- and CNS-analyses. Fossil diatom assemblages were studied to reconstruct long-term development in lake-water pH. Ordination techniques and diversity indices were applied to identify temporal patterns and relationships in the bioassemblages, and Spearman's correlation coefficients were calculated to assess statistical relationships between the studied abiotic and biotic parameters. The results reveal that, whereas long-term climate changes have had the most profound impact on the water quality and ecology of Lake Storträsk, the status of the lake has also been altered by early catchment disturbances and historical human activities as well as more intensive anthropogenic disturbances after the establishment of intensive agriculture in the area. The base of the sediment core reflects the transition from the warm and dry Holocene Thermal Maximum to the cooling and increasingly humid late Holocene. After the initial phase, a more stable development took place, disrupted by possible signs of forest fires and early clearance periods in the area. From the late Middle Ages onwards, human activities within the vicinity of the lake became more intensive leaving highly distinct marks in the sediment, but were receded towards the present. Regardless of the current location of Lake Storträsk in a conservation area, and the apparent inability of the barren catchment to support any intensive agricultural practices, it is clear that human influences on the lake have been significant. The results of this study highlight the importance of long-term perspective in the assessment of lake reference conditions since lake ontogeny is often far from linear. Furthermore, this study emphasizes the importance of combining information from multiple paleolimnological proxies as they provide a more robust and holistic basis for understanding lake-environment dynamics particularly in humic boreal lakes which often respond to environmental change in distinct ways.
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(2021)Due to the harsh conditions in high latitude alpine and arctic regions, climate or land use changes make them very vulnerable. Thus, it is vital to study the habitats of these regions and increase our understanding of what factors impact species distributions. Species distribution modelling can be used to predict possible habitats for species and further inspect the relationships between different environmental variables and species. Generally, these species distribution models have been created using variables describing the topographical and climatic conditions of the study area. Recently there has been more evidence supporting the inclusion of biotic variables to species distribution models at all scales. Including biotic variables can be difficult, as these relationships can be challenging to quantify. This study uses the Normalized Difference Vegetation Index (NDVI) as a surrogate for plant biomass, thus representing biotic interactions. This study aims to answer what are the relationships between environmental variables and the predicted distributions and will including a biotic variable improve the species distribution models. The study data includes observational data from 683 arctic and alpine plant species from Norway, Sweden, and Finland. The observation data were collected from the three national databanks of Norway, Sweden and Finland and completed with observations from the Global Biodiversity Information Facility and observation data collected by the BioGeoClimate Modelling Lab. The cohesive study area was outlined with the biogeographical regions defined by the European Environment Agency. Overall, six environmental variables are used in this study: annual mean temperature, the maximum temperature of the warmest month, annual precipitation, elevation difference in a cell, bedrock class, and NDVI. The NDVI data was gathered by NASA’s MODIS sensors. The observations and the environmental variables were projected into a grid consisting of 1 x 1 km cells covering the whole study area. This study uses the ensemble modelling technique with four individual modelling methods: generalized linear models (GLM), generalized additive models (GAM), generalized boosted models (GBM) and random forests (RF). The modelling process consisted of two modelling rounds so that the impact of NDVI could be evaluated. The first modelling round included all the environmental variables except NDVI (the topoclimate model) and the second modelling round included all the environmental variables (the full model). The two temperature variables, annual mean temperature and the maximum temperature of the warmest month, had the highest mean variable importance values. With the topoclimate model, annual precipitation ranked third with the rest of the climate variables, but when NDVI was added to the models, it rose above annual precipitation. Overall, among the studied arctic and alpine species, the variable importance values of both the edaphic and topographical variables were low. In general, both the topoclimate models and full models performed very well. The mean AUC- and TSS-values were all higher for the full models, indicating that including a biotic variable improved the models. When the binary predictions of both modelling rounds were compared, it was clear that NDVI refined the projected distributions for most species. The results from this study confirm the discovery that including a biotic variable, such as NDVI, has the potential to increase the predictive power of species distribution models. One of the main problems with including biotic variables in species distribution models has been the difficulty of quantifying biotic interactions. NDVI can thus be a promising tool to overcome these difficulties, as it is one of the most direct variables to describe ecosystem productivity, can be acquired at various scales, and as remotely sensed data, it can also cover areas that are difficult to access.
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(2021)Tämän tutkielman tarkoitus on esitellä ja todistaa eräs topologisiin ryhmiin liittyvä lause. Lause kertoo topologisen ryhmän oleva metristyvä avaruus, mikäli ryhmän neutraalialkiolla on numeroituva ympäristökanta. Tutkielmassa käsitellään tarkemmin topologisiin ryhmiin liittyviä tuloksia ja niiden seurauksia. Ensimmäinen kappale on varattu johdannolle. Heti alussa käydään läpi miksi tutkielman tulos on merkittävä ja miksi siihen on järkevää paneutua. Tutkielmassa esitellään oleelliset lähtötiedot, jotta lukijan on helpompi tutustua varsinaiseen aiheeseen. Toisessa kappaleessa kerrotaan tärkeimmät käsitteet ja ne yritetään mahdollisimman selvästi selittää lukijalle. Tässä kappaleessa käydään myös läpi tutkielmassa käytettyjä merkintätapoja. Kolmannessa kappaleessa tutustutaan topologisiin ryhmiin ja niihin liittyviin tuloksiin. Kappaleessa on lyhyesti esiteltynä topologisen ryhmän määritelmä, pohjaten algebran määrittelemään ryhmän käsitteeseen ja yleisen topologian määräämiin ehtoihin. Topologisille ryhmille johdetaan kaksi lausetta, jotka ovat tutkielman päätuloksen todistusta varten oleellisia. Ensimmäinen lauseista kertoo, että neutraalialkiolle voidaan rakentaa symmetrisiä ympäristöjä niin, että niiden tulo kuuluu aina johonkin toiseen ympäristöön. Toinen lauseista taas antaa tiedon siitä kuinka neutraalialkiolle löytyy ympäristöjä johon jokin toinen alkio ei kuulu. Nämä lauseet antavat työkalut rakentamaan ryhmän alkioille avoimia ympäristöjä, joita käytetään taas edelleen sopivia ympäristökantoja rakennettaessa. Tässä kappaleessa käydään läpi kaikki tarvittava päätulosta varten. Tutkielman varsinainen päätulos esitellään lyhyesti kappaleen neljä alussa. Kappaleessa todistetaan vaihe vaiheelta topologisen ryhmän neutraalialkiolle rakennetun numeroituvan ympäristökannan avulla, että löydetään metriikka joka määrittää avoimet joukot siten, että ne ovat samoja kuin topologian määräämät avoimet joukot. Tulos on merkittävä siksi, että se antaa työkalun tarkastella topologisten ja metristen avaruuksien yhteyksiä. Lähtökohta työlle oli kirjoittajan oma kiinnostus topologisiin ryhmiin ja niihin liittyviin tuloksiin. Tavoitteena oli todistaa tärkeä tulos topologian alalta, joka auttaa linkittämään topologiset ja metriset avaruudet toisiinsa.
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(2021)LHC is the highest energy particle collider ever built and it is employed to study elementary particles by colliding protons together. One intriguing study subject at LHC is the stability of the electroweak vacuum in our universe. The current prediction suggests that the vacuum is in the metastable state. The stability of the vacuum is dependent on the mass of the top quark, and it is possible that more precise measurement of the mass could shift the prediction to the border of the metastable and stable states. In order to measure the mass of the top quark more precisely, we need to measure the bottom (b) quarks decaying from it at high precision, as top quark decays predominantly into a W boson and a b quark. Due to the phenomenon called hadronisation, we can not measure the quarks directly, but rather as sprays of collimated particles called jets. The jets originating from b quarks (b jet) can be identified by b-tagging. The precise measurement and calibration of the b jet energy is crucial for top quark mass measurement. This thesis studies the b jets and their energy calibration at the CMS, which is one of the general purpose detectors along the LHC. Especially the b jet energy scale (bJES) is under the investigation and the various phenomena affecting to it. For example, large fraction of b jets contain neutrinos, which cannot be measured directly. This increases uncertainties related to the energy measurement. Also there are problems how precisely the formation and evolution of the b jets can be modelled by Monte Carlo event generators, such as Pythia8, which was utilized in this thesis. The aim of this thesis is to evaluate how big effect on the bJES is caused by the various different phenomena, which presumably weaken the precision of the b jet measurements. The studied phenomena are the semileptonic branching ratios of b hadrons, branching ratios of b hadron to c hadron decays, b hadron production fraction and parameterization of the b quark fragmentation function. The combined effect of all four different rescaling features mentioned above, suggests that bJES is known at 0.2% level. A small shift of -0.1% in the Missing transverse energy Projection Fraction (MPF) response scale is detected at low pt values, which vanishes as the pt increases. This improves remarkably 0.4-0.5% JES accuracy achieved during at CMS during Run 1 of the LHC. However, there are still many ways we can improve the performance presented here. Definitely there is a need for further studies of the rescaling methods before results could be utilized in the corrections of bJES to do precision measurement of the top quark mass.
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(2022)Ilmatieteen laitoksella on otettu käyttöön eri säämallien ennusteita yhdistelevä, niin sanotun konsensusennusteperiaatteen mukainen jälkikäsittelymenetelmä, joka tunnetaan nimellä Blend. Tämä tutkielman tarkoituksena on selvittää Blend-menetelmällä tuotetun tuuliennusteen toimivuutta Suomen merialueilla käyttämällä muutamaa yleiseen käyttöön vakiintunutta sääennusteiden verifiointimenetelmää. Verifiointi on toteutettu vertaamalla Blend-ennusteen tuulennopeusarvoja niin ikään jälkikäsittelyllä tuotettuihin potentiaalituuliarvoihin 25:llä Suomen merialueilla sijaitsevalla havaintoasemalla. Potentiaalituulta on päätetty käyttää alkuperäisten tuulihavaintojen sijasta, koska se parantaa eri sääasemilta tulevien mittaustulosten keskinäistä vertailukelpoisuutta ja näin ollen tekee verifiointituloksista paremmin koko alueelle yleistettäviä. Tulokset osoittavat odotetusti, että merkittävimmät Blend-tuuliennusteen toimivuuteen vaikuttavat tekijät ovat tuulennopeus ja ennustepituus – ennustevirhe kasvaa yleisesti suuremmilla tuulennopeuksilla ja pidemmillä ennustepituuksilla. Myös muilla muuttujilla, kuten vuorokauden- ja vuodenajalla sekä tuulen suunnalla, havaittiin olevan jonkin verran vaikutusta ennustevirheeseen. Useimmissa säätilanteissa Blend-ennusteen voidaan todeta olevan toimivuudeltaan varsin hyvä ja tasalaatuinen. Blend-ennusteen merkittävin ongelma on etenkin suurilla tuulennopeuksilla huomattavan suuri negatiivinen harha (bias), eli ennustetut tuulennopeudet ovat havaintoihin nähden selvästi liian heikkoja. Tästä johtuen Blend ei useimmissa tapauksessa kykene ennustamaan kovimpia tuulia, jotka ovat harvinaisuudestaan huolimatta operatiivisen sääennustamisen kannalta kaikista tärkeimpiä mm. merialueille annettavien tuulivaroitusten vuoksi. Menetelmä on kuitenkin kehityskelpoinen, ja jos ennusteharha pystytään jatkossa minimoimaan laskennassa paremmin, se saattaa kyetä tuottamaan jopa varsinaisia säämalleja parempia tuuliennusteita.
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(2023)Evolution can lead to changes in body size among mammals and when that occurs, organs usually scale along. Teeth are an organ that scale along with body size and therefore, investigating how the teeth are getting along when a mammal is subjected to a rapid reduction of body size is of value. During human evolution, body size has generally increased but jaw and teeth size has decreased. As of recent, human evolution witness a potential decrease of body size, due to the discovery of island-living hominins; Homo floresiensis and Homo luzonensis. The phenomenon of decreasing body size among large animals and increasing body size among small animals in an insular setting is so well-known that it has its own ecological rule, called the island rule or Foster’s rule. However, this phenomenon has not really been studied from the perspective of teeth. In this thesis I focus on the effects of body size decrease on teeth in the context of relatively rapid body size reduction. Researching the effect that a reduction of body size has on teeth is relevant for understanding morphological changes related to island dwarfism and the origins of island forms among humans. Dogs (Canis familiaris) provide an extreme example of rapid and large reduction of both body- and teeth size. Comparing dog molars to molars of their closest ancestor, the wolf (Canis lupus), can shed light on how the teeth behave when scaling down in size. This reduction in body size may be comparable to insular dwarfing as selective breeding of pure breed dogs is limiting the availability of mating partners in a similar way that a secluded island limits the availability of mating partners for insular animals. To answer my research questions, I measure and photograph dog molars and compare the results with data of wolf molars. Furthermore, if any patterns emerge, data of human molar is compared to the canid data to investigate if any similarities can be found. The results show that dog molars are overall smaller in size than wolf molars and that both species follow a pattern where m1 > m2 > m3. Furthermore, small dogs are more likely to have an absent m3 than big dogs and wolves. Moreover, the results show that the size relation between dog m1-m2 is a continuum of wolf m1-m2 relation. However, dogs have enlarged their m3 and therefore the m2-m3 size relation is not a continuum of wolf molar relation. When comparing the human data to the results of dog/wolf m1-m2 and m2-m3 size relation, the results show that Homo floresiensis molars are on the same trajectory as Homo erectus molars. This implies that dogs have done adjustments to their molars that diverge from their ancestors’ molars and that the change has happened during a short period of time. Therefore, dog molars cannot be seen as simply scaled down version of wolf molars, as far as size is concerned. The information gained from this thesis can be used to further investigate if molars of other rapidly dwarfed species may have behaved in a similar manner. It is however too early to say if dogs can be seen as an island rule simulation or if they can shed light on the origins of hominin island forms. More research, such as comparing the number of cusps between dog and wolf molars or investigating the upper carnassial and the following molars, needs to be done to be able to draw any further conclusions.
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