Skip to main content
Login | Suomeksi | På svenska | In English

Browsing by Title

Sort by: Order: Results:

  • Luoma, Krista (2017)
    Maapallon ilmakehä sisältää mikroskooppisen pieniä aerosolihiukkasia, joilla on vaikutus ihmisten terveyteen sekä maapallon ilmastoon. Aerosolihiukkaset vaikuttavat ilmastoon vuorovaikuttamalla auringon säteilyn kanssa sekä osallistumalla pilvien muodostumisprosessiin. Tässä tutkielmassa keskitytään aerosolihiukkasten optisiin ominaisuuksiin, joilla tarkoitetaan niiden kykyä sirottaa sekä absorboida säteilyä eri aallonpituuksilla. Tutkielmassa käsitellään SMEAR II -asemalla suoritettuja in-situ mittauksia aerosolihiukkasten sironnasta, takaisinsironnasta ja absorptiosta, joita on saatavilla jo vuodesta 2006 alkaen. Mitattujen sironta-, takaisinsironta- sekä absorptiokertoimilla aerosolihiukkasille voidaan määrittää niiden kokojakaumaa ja koostumusta kuvaavia intensiivisiä suureita. Pitkäaikaisten mittausten avulla optisille ominaisuuksille nähtiin trendejä sekä selkeää vuodenaikaisvaihtelua. Vertaamalla optisia mittauksia kokojakauman mittauksiin, aerosolihiukkasille voitiin määrittää kompleksinen taitekerroin, jota käytetään mallinnettaessa Mie-sirontaa ja -absorptiota. Absorptiokertoimen mittauksia verrattiin lisäksi alkuainehiilen mittauksiin, jolloin voitiin määrittää aerosolihiukkasten massa-absorptioala. Massa-absorptioalan avulla voidaan määrittää mustan hiilen pitoisuus absorptiokertoimen mittauksista. SMEAR II -asemalla absorptiokerrointa on mitattu kolmella eri mittalaitteella (etalometri, Particle Soot Absorption Photometer (PSAP) sekä Multi-Angle Absorption Photometer (MAAP)), joita vertailtiin keskenään. Vertaamalla etalometrin sekä MAAPin mittaustuloksia toisiinsa määritettiin etalometrimittauksiin liittyville korjausalgoritmeille suodattimen moninkertaissirontaa kuvaavat parametrit SMEAR II -aseman olosuhteisiin. Tutkielmassa suoritettiin myös optinen sulkeuma ekstinktio-, sironta- sekä absorptiokertoimien mittaustuloksia vertailemalla. Tulosten perusteella ekstinktiota mittaavan Cavity Attenuated Phase Shift -ekstinktiomonitorin (CAPS) sekä sirontaa mittaavan integroivan nefelometrin mittaustarkkuudet eivät riitä mittaamaan aerosolifaasissa olevien hiukkasten absorptiota.
  • Jokela, Jesse (2018)
    Tämän pro gradu –tutkielman kirjallinen osuus on katsaus aerosolimassaspektrometrian kehitystä ja sen sovelluksia käsittelevään kirjallisuuteen viimeisen noin kymmenen vuoden ajalta. Aerosolimassaspektrometrialla tarkoitetaan massaspektrometrian soveltamista aerosolihiukkasten kokojaotellun kemiallisen koostumuksen mittaukseen. Erilaiset aerosolimassaspektrometrit on tutkielmassa jaoteltu kahteen ryhmään sen perusteella, analysoidaanko laitteella yksittäisiä hiukkasia vai kerrallaan ryhmittäin useita tietyn kokoisia lyhyen ajanjakson aikana kerättyjä hiukkasia. Hiukkasia ryhmittäin analysoivat aerosolimassaspektrometrit käyttävät yleensä lämpöhöyrystystä hiukkasten desorboimiseksi ennen ionisointia, kun taas yksittäisiä hiukkasia analysoivat aerosolimassaspektrometrit desorboivat hiukkaset yksi kerrallaan käyttäen tähän tyypillisesti pulssitettua laseria. Aerosolimassaspektrometreilla voidaan tehdä monenlaista ilmakehätutkimusta. Tutkielmassa on tuotu esille erityisesti orgaanisten aerosolien ja niiden alkuainekoostumuksen, merisuolan, metallien ja muiden hivenaineiden tutkimuksia. Omat kappaleensa on annettu aerosolihiukkasten kemiallista koostumusta mittaavalle monitorille sekä aerosolimassaspektrometriin liitettäville laitteille, joita ovat esimerkiksi lämpödesorptioaerosolikaasukromatografi, potentiaalinen aerosolimassakammio ja valonsironta-moduuli. Kirjallisuuskatsauksen lopussa on käsitelty lyhyesti aerosolien lähdeanalyysejä. Ilmakehän aerosolien nukleaation, kasvun ja ikääntymisen mekanismien ja kinetiikan kvantitointi ja selventäminen edelleen ovat tarpeen, koska ilmakehän aerosolihiukkasilla on vaikutuksia maapallon ilmastoon, paikallisiin ilmansaasteisiin ja ihmisten terveyteen. Aerosolimassaspektrometreilla on keskenään hyvin erilaisia ominaisuuksia, eikä ole olemassa yhtä jokaiseen tilanteeseen soveltuvaa aerosolimassaspektrometria. Mittaukset samanaikaisesti usealla eri tyyppisellä aerosolimassaspektrometrilla ja perinteisillä analyysilaitteistoilla täydentävät toisiaan ja parantavat kokonaisvaltaisesti ymmärrystä eri menetelmistä ja hiukkasten ominaisuuksista. Tutkielman kokeellisen osuuden tarkoituksena oli mitata hiukkasten kokojaoteltuja kemiallisia koostumuksia kaupunkiympäristössä näytteenkeräys- ja suoramittausmenetelmillä, ja verrata menetelmiä keskenään. Kenttämittauksia suoritettiin nokiaerosolimassaspektrometrilla (SP-AMS). Kaskadi-impaktorilla suodatinkalvoille kerättyjä kokojaoteltuja aerosolinäytteitä analysoitiin laboratoriossa ionikromatografilla (IC). Kokeellisen osuuden suoramittaus- ja näytteenkeräysmenetelmillä mitatut kokojakaumat vastasivat pääosin melko hyvin toisiaan. Suoramittausmenetelmien ylivertainen aikaresoluutio mahdollistaa ilmakehän pienhiukkasten luonnollisten lähteiden, ihmisen aiheuttamien päästöjen sekä sääolosuhteiden vaikutusten tutkimisen huomattavan tarkasti verrattuna näytteenkeräysmenetelmiin. Virheen määrittäminen on aerosolimassaspektrometrimittauksissa selvästi vaikeampaa kuin ionikromatografia-analyyseissä. Voidaan kuitenkin varmasti sanoa, että johtuen analyysivaiheiden lukumäärästä virhe IC- ja IC-MS –mittauksissa on huomattavasti suurempi kuin SP-AMS –mittauksissa.
  • Khansari, Marzieh (2018)
    The climate feedback is a response of the climate system to a perturbation through a number of mechanisms. Perturbations can be due to natural factors, like volcanic activity or changes in solar activity, or anthropogenic such as emissions of long-lived greenhouse gases and aerosol particles. Atmospheric aerosols affect the Earth’s radiation budget. The aerosols impact radiation directly by scattering and absorbing incoming solar radiation and indirectly by changing cloud properties via formation of cloud condensation nuclei. Here, the aerosol radiation feedback loop associated to the continental biosphere-aerosol-cloud-climate (COBACC) feedback loop, is suggested. This negative feedback loop connects increasing atmospheric CO2 concentration, rising temperatures, the formation of aerosol particles due to the emission of biogenic volatile organic compounds, changes in ratio of diffuse to global radiation in the clear sky condition, and changes in the plant gross primary production. In this study, in-situ atmospheric measurement data in Hyytiälä station, as well as satellite atmospheric measurement data (CERES (Clouds and the Earth’s Radiant Energy System) and MODIS (Moderate Resolution Imaging Spectroradiometer instrument)) around Hyytiälä station and a small area in the western plain of Siberia for clear sky conditions in June and July around noon, were used. Three methods for detecting clear-sky conditions were considered: brightness parameter, global radiation smoothing and lastly MODIS cloud mask method. Here, MODIS cloud mask method was selected as the most suitable method due to availability of data and global coverage. This study proved partly the existence of the aerosol radiation feedback loop by finding positive correlation between some of the components of the feedback loop, such as condensation sink(CS) and temperature, ratio of diffuse radiation to global radiation (R) and CS, and R and temperature. Additionally, it was shown that satellite-based data compares well with in-situ data. Hence, it is possible to use satellite-based data for the aerosol-radiation feedback loop. In addition, the impact of relative humidity on the relation between R and temperature was investigated. It was found that it is important to take into account the swelling effect in order to investigate the relation between R and temperature. In contrast, solar zenith angle does not have an impact on the relation during study period (June – July).
  • Kuna, Kamilla (2021)
    This research studies the environmental aesthetics of boredom in the light of post-soviet neighborhoods. While belonging to the grey zone in aesthetics, boredom is an integral part of mundane life that challenges us to notice the uniqueness of our everydayness. Even though mass housing provided an economically feasible solution for sheltering millions of people, it lacks the qualities that meet contemporary living and energy standards. Soviet mass housing architecture and microdistrict designs were led by the economic conditions in the first place. Mass housing was not meant to speak, whereas the residents should not be silenced because of it. We tend to preserve what we find aesthetically pleasing (Nassauer, 1997), yet, what is aesthetically pleasing and what about other values? In this project, preservation is essential for building a contemporary-oriented mindset that could lead to more sustainable and inclusive neighborhoods. The project aims to tackle the issue of Soviet districts through the eyes of its residents, contrasting the more often used top-down approach. Here I challenge the residents' perception of their neighborhood and create a moment for reflection. By offering this space, I amplify the voices of the real experts, the ones knowing their microdistrict inside out. Environmental aesthetics is a relatively new concept within the contemporary urban planning scholarship, giving a fresh take on subjective experiences of urban settings that unveil profoundly rooted and often disguised problems. The interdisciplinarity in the research is met by merging disciplines such as sociology, urban aesthetics, urban history, and philosophy. The term boredom belonging to positive or negative aesthetic values is questioned the same as the legacy of Soviet mass housing later in the research. The ideology behind Soviet blocks is discussed, creating a common ground for diverse readers. Inclusivity is brought with resident participation through the visual research method - photovoice. To avoid biased data, the resident experiences are supported with the city planner's point of view and secondary quantitative data. The findings include Laumas microdistrict resident photovoice analysis, putting the Laumas microdistrict residents as the primary information providers. Taking pictures of their everyday surroundings, residents are given space to show how they see their microdistrict, outlining the values they are proud of or giving perspective of what needs to be changed. Instead of one-sided creation, the curation is inclusive and more reflective of the urban environment's already existing residents' values of their neighborhood. Resident aesthetic preferences open broader discussion on the maintenance issues of microdistricts facing nowadays. Topics are various, but the primary outcomes discussed built environment aesthetics, renovation, communication, identity, resident initiative, automobile domination, and natural environment aesthetics. In the final part of the study, some possible directions for changing microdistrict are pointed out, and further research questions are presented. The project is incomplete until it reaches a broader audience and provides knowledge to politicians, city planners, and other residents.
  • Niu, Yimeng (2016)
    While health establishes the basis of our life, at times we need to visit doctors or hospitals. On that, patients may be faced with inequalities, for example, due to distances to the healthcare resources. With the development of telecommunications and the internet of things, telemedicine may assist in such cases, saving travel time and cost. This thesis suggests a telemedicine monitoring solution for both hospital based and personal users. The focus is on the architecture of the system, the role of wireless sensors in telemedicine and telemedicine key technologies (such as: Bluetooth and ZigBee). Further, the software structure for monitoring the patients' physiological state remotely at hospital and at home is suggested. This involves also the choice of suitable hardware for data acquisition and wireless transmission. In the end, other related scientific researches are discussed. Comparisons are made between the proposed solution and other similar designs in different angles depending on the focuses of other research work, such as processing performance, connectivity, usability, unit price, data security and decision making.
  • Linkola, Simo (2016)
    A measurement for how similar (or distant) two computer programs are has a wide range of possible applications. For example, they can be applied to malware analysis or analysis of university students' programming exercises. However, as programs may be arbitrarily structured, capturing the similarity of two non-trivial programs is a complex task. By extracting call graphs (graphs of caller-callee relationships of the program's functions, where nodes denote functions and directed edges denote function calls) from the programs, the similarity measurement can be changed into a graph problem. Previously, static call graph distance measures have been largely based on graph matching techniques, e.g. graph edit distance or maximum common subgraph, which are known to be costly. We propose a call graph distance measure based on features that preserve some structural information from the call graph without explicitly matching user defined functions together. We define basic properties of the features, several ways to compute the feature values, and give a basic algorithm for generating the features. We evaluate our features using two small datasets: a dataset of malware variants, and a dataset of university students' programming exercises, focusing especially on the former. For our evaluation we use experiments in information retrieval and clustering. We compare our results for both datasets to a baseline, and additionally for the malware dataset to the results obtained with a graph edit distance approximation. In our preliminary results we show that even though the feature generation approach is simpler than the graph edit distance approximation, the generated features can perform on a similar level as the graph edit distance approximation. However, experiments on larger datasets are still required to verify the results.
  • Karhuvaara, Henriikka (2020)
    Aiemmat tutkimukset osoittavat, että matematiikan oppimiseen vaikuttavat affektiiviset tekijät kehittyvät peruskoulun ja lukion aikana, mutta näkyvät myös korkeakouluopinnoissa. Erityisesti vähemmän matemaattisille aloille hakeutuvien opiskelijoiden aiemmat kokemukset matematiikan opiskelusta voivat olla negatiivisia, mikä voi vaikuttaa matematiikan opiskeluun esimerkiksi yliopistossa. Tutkimuksessa tarkasteltiin, miten Helsingin yliopiston maatalous-metsätieteellisen tiedekunnan kurssi Matematiikka I vaikuttaa opiskelijoiden affektivisiin kokemuksiin, kuten itsevarmuuteen, matematiikka-ahdistukseen, motivaatioon, opiskelun mielekkyyteen ja matematiikan arvostukseen. Tulosten perusteella kurssin opetusta pyritään kehittämään siten, että se ehkäisisi erityisesti negatiivisten kokemusten syntymistä, jotta opiskelijat eivät välttelisi matematiikan opiskelua ja käyttöä yliopistossa sekä tulevilla urillaan. Tutkimusaineisto kerättiin syksyn 2019 kurssilla. Affektiivisia kokemuksia käsittelevä aineisto kerättiin sekä kurssin alussa että lopussa kyselylomakkeella ja avoimilla kysymyksillä. Opiskelijoiden osaamitason vaikutuksia affektiivisiin tekijöihin selvitettiin kurssin alkutaitotestin ja loppukokeen avulla. Lisäksi seurattiin opiskelijoiden kurssin aikana tekemiä tehtäviä. Affektiivisten tekijöiden kehitystä ja kurssilla työskentelyä sekä suoriutumista seurattiin 40 opiskelijan otoksella. Tutkimuksesta selvisi, että Matematiikka I -kurssi vaikutti opiskelijoiden affektiivisiin kokemuksiin sekä positiivisesti että negatiivisesti. Opiskelijan lähtötaso oli yhteydessä siihen, miten opiskelijan itsevarmuus ja motivaatio kehittyivät kurssin aikana. Osaamisen lähtötaso vaikutti myös matematiikka-ahdistuksen kokemukseen. Opiskelun mielekkyyteen vaikutti eniten kurssin käytännönjärjestelyt. Matematiikan arvostuksen kehittymisen kannalta keskeistä oli, ymmärsivätkö opiskelijat kurssin myötä matematiikan merkityksen omalla alallaan. Tulokset osoittavat, että kurssin opetusta on järkevää kehittää siten, että se ehkäisee affektiivisten tekijöiden kehittymistä negatiiviseen suuntaan. Lähtötasoltaan kurssiin nähden heikommille opiskelijoille kannattaa järjestää riittävä mahdollisuus täydentää osaamistaan ennen kurssin alkua. Toisaalta opiskelijoiden erilainen lähtötaso tulee huomioida myös varsinaisen kurssin opetuksessa. Kurssisuunnitteluun on jatkossa varattava riittävästi aikaa. Myös viestintään on järkevää panostaa, jotta kurssin tavoitteet ja vaatimukset ovat opiskelijoille selkeitä. Kurssin suunnittelussa ja opetuksessa kannattaa mahdollisuuksien mukaan jatkossakin hyödyntää eri alojen osaajia, jotta kurssin matemaattisia sisältöjä saadaan asteittain tuotua lähemmäs opiskelijoiden omaa alaa.
  • Turkia, Mika (Helsingin yliopistoHelsingfors universitetUniversity of Helsinki, 2007)
    One of the most tangled fields of research is the field of defining and modeling affective concepts, i. e. concepts regarding emotions and feelings. The subject can be approached from many disciplines. The main problem is lack of generally approved definitions. However, e.g. linguists have recently started to check the consistency of their theories with the help of computer simulations. Definitions of affective concepts are needed for performing similar simulations in behavioral sciences. In this thesis, preliminary computational definitions of affects for a simple utility-maximizing agent are given. The definitions have been produced by synthetizing ideas from theories from several fields of research. The class of affects is defined as a superclass of emotions and feelings. Affect is defined as a process, in which a change in an agent's expected utility causes a bodily change. If the process is currently under the attention of the agent (i.e. the agent is conscious of it), the process is a feeling. If it is not, but can in principle be taken into attention (i.e. it is preconscious), the process is an emotion. Thus, affects do not presuppose consciousness, but emotions and affects do. Affects directed at unexpected materialized (i.e. past) events are delight and fright. Delight is the consequence of an unexpected positive event and fright is the consequence of an unexpected negative event. Affects directed at expected materialized (i.e. past) events are happiness (expected positive event materialized), disappointment (expected positive event did not materialize), sadness (expected negative event materialized) and relief (expected negative event did not materialize). Affects directed at expected unrealized (i.e. future) events are fear and hope. Some other affects can be defined as directed towards originators of the events. The affect classification has also been implemented as a computer program, the purpose of which is to ensure the coherence of the definitions and also to illustrate the capabilities of the model. The exact content of bodily changes associated with specific affects is not considered relevant from the point of view of the logical structure of affective phenomena. The utility function need also not be defined, since the target of examination is only its dynamics.
  • Hirvi, Emilia (2019)
    Tämän tutkielman aiheena on affiini geometria, jota esitellään ensimmäisessä luvussa. Aihetta lähestytään lineaarialgebran näkökulmasta. Luodakseen hyvän pohjan affiinin geometrian tarkastelulle toinen luku keskittyy lineaarialgebran perusmääritelmiin. Kolmannessa luvussa tutustutaan affiinin avaruuden käsitteeseen, jossa määritellään pisteiden ja vektoreiden välinen toiminta. Affiinissa avaruudessa suorien ja vektoreiden yhdensuuntaisuus on keskeinen asia. Toisaalta vektorin lähtöpisteellä ei ole merkitystä. Neljännessä luvussa esitellään lineaarikombinaation tapainen käsite: affiini kombinaatio eli painopiste. Affiini kombinaatio määritellään painoilla varustetulle pisteperheelle. Lisäksi painojen eli skalaarien summan on oltava yksi. Seuraavassa luvussa käsitellään affiineja aliavaruuksia. Kuten vektoriavaruuden aliavaruus sisältää kaikki virittäjävektorinsa lineaarikombinaatiot, affiini aliavaruus sisältää kaikki painoilla varustettujen pisteperheidensä affiinit kombinaatiot. Affiini aliavaruus on origosta pois siirretty aliavaruus. Kuudes luku keskittyy affiiniin riippumattomuuteen ja affiiniin kehykseen. Affiini riippumattomuus määritellään lineaarisen riippumattomuuden avulla ja affiini kehys vektoriavaruuden kannan avulla. Seitsemännessä luvussa määritellään affiini kuvaus, joka on lineaarikuvauksen ja siirtovektorin yhdistelmä. Affiinissa kuvauksessa ensin lineaarikuvaus kiertää tai venyttää pistejoukkoa ja sen jälkeen siirtovektori siirtää pistejoukon paikkaa. Affiinissa kuvauksessa yhdensuuntaiset suorat kuitenkin kuvautuvat yhdensuuntaisiksi suoriksi. Lopuksi tarkastellaan joitakin affiinin geometrian esimerkkejä.
  • Liangsupree, Thanaporn (2018)
    The literature part of this thesis contains the review of affinity chromatography using monolithic stationary supports in the separation and isolation of biomacromolecules, a technique known as affinity monolith chromatography (AMC). Affinity chromatography is a liquid separation technique operating on the principle of reversible binding of affinity ligands and target analytes. Experimentally, affinity chromatography involves the attachment of affinity ligands to the stationary support. By selecting appropriate ligands having high affinity and specificity towards the target, selective captures of analytes of interest are made possible, allowing their isolation from complex sample matrices. Subsequently, bound analyte species are released from the ligands by employing suitable elution solutions. In addition to the specificity, monolithic stationary phases offer a number of other benefits over conventional particulate supports, i.e., improved mass transfer characteristics, allowing convective rather than diffusional transport of analytes; and high permeability, permitting operations at high flow rates without suffering from backpressure. These benefits result in substantially reduced time requirements for isolation and separation while maintaining satisfactory separation efficiency. Different types of monolithic materials, including organic polymer-based monoliths (e.g., cryogels), inorganic monoliths (e.g., silica monoliths), and hybrid monoliths have been prepared and employed in AMC. A large range of affinity ligands, e.g., proteins, antibodies, immobilized metal ions, dye ligands, have been used with monolithic supports in different formats, and in different applications. The mentioned material-related topics, as well as recent applications of AMC, are discussed in detail in this review. The experimental part of this thesis deals with the isolation of lipoproteins, and low-density lipoprotein (LDL) in particular, from human blood plasma using a newly developed AMC technique. LDL, a globular and major lipid carrier in blood, is diagnostically a highly relevant subclass of lipoproteins due to its involvement in the genesis of atherosclerosis. The currently most frequently employed method for lipoprotein isolation from blood plasma is ultracentrifugation. However, this method suffers from drawbacks, such as being time-consuming, requiring expensive equipment, and the possible exchange of lipids and lipoprotein subclasses during sample processing. Therefore, the first goal was to develop a faster LDL isolation protocol, capable of yielding LDL with good functionality and purity. Thus, the first section reports on the isolation of low-density lipoprotein (LDL) from human blood plasma by employing affinity monolith chromatography method using Convective Interaction Media (CIM) monolithic disk columns as stationary supports. Specifically, anti-apoB100-monoclonal antibody (mAb) was immobilized onto a CIM monolithic disk, providing a suitable capture medium for LDL through its major apolipoprotein, apolipoprotein B100 (apoB100). Other lipoprotein classes, namely very low-density lipoprotein (VLDL) and intermediate-density lipoprotein (IDL), also carry apoB100 and thus may be captured. To discriminate against these lipoproteins, and to obtain LDL with satisfactory purity, an additional CIM monolithic column was immobilized with a glycosaminoglycan, namely chondroitin-6-sulfate (C6S), which also binds lipoproteins, albeit with different specificity and interactions. Both of these affinity media were evaluated for LDL binding either individually or in combination. The quality of the isolated LDL was confirmed with different characterization techniques, such as size exclusion chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), enzymatic cholesterol and triglyceride assays, and enzymatic-linked immunoassays (ELISAs) specific to apolipoprotein B100 and apolipoprotein E. The results from these multi-method characterizations confirmed the successful LDL isolation with good activity. The second section of the thesis was devoted to quartz crystal microbalance (QCM) biosensor studies of LDL samples isolated from different individuals by different methods (affinity chromatography and conventional ultracentrifugation). A QCM sensor chip immobilized with anti-apoB100 mAb was used and challenged series of different LDL concentrations. The resulting sensorgrams were analyzed with a new numerical algorithm, namely Adaptive Interaction Distribution Algorithm (AIDA), permitting the determination of the number of analyte-receptor binding sites and the underlying kinetics. It was found that the obtained rate constant distributions, and clustering of antibody-LDL complexes were almost identical for all LDL samples, irrespective of sources or isolation techniques. For all samples, a total of five major complex clusters were identified. The major contributions of the two dominating clusters may arise from specific, yet heterogeneous LDL interactions at the antibody binding sites, while the other three clusters observed reflect most likely nonspecific low-affinity interactions from various sources, such as mass transfer effects, and the use of a non-orienting ligand immobilization chemistry.
  • Koponen, Aila Helena (Helsingin yliopistoHelsingfors universitetUniversity of Helsinki, 2008)
    The conferencing systems in IP Multimedia (IM) networks are going through restructuring, accomplished in the near future. One of the changes introduced is the concept of floors and floor control in its current form with matching entity roles. The Binary Floor Control Protocol (BFCP) is a novelty to be exploited in distributed tightly coupled conferencing services. The protocol defines the floor control server (FCS), which implements floor control giving access to shared resources. As the newest tendency is to distribute the conferencing services, the locations of different functionality units play an important role in developing the standards. The floor control server location is not yet single-mindedly fixed in different standardization bodies, and the debate goes on where to place it within the media server, providing the conferencing service. The thesis main objective is to evaluate two distinctive alternatives in respect the Mp interface protocol between the respective nodes, as the interface in relation to floor control is under standardization work at the moment. The thesis gives a straightforward preamble in IMS network, nodes of interest including floor control server and conferencing. Knowledge on several protocols – BFCP, SDP, SIP and H.248 provides an important background for understanding the functionality changes introduced in the Mp interface and therefore introductions on those protocols and how they are connected to the full picture is given. The actual analysis on the impact of the floor control server into the Mp reference point is concluded in relation to the locations, giving basic flows, requirements analysis including a limited implementation proposal on supporting protocol parameters. The overall conclusion of the thesis is that even if both choices are seemingly useful, not one of the locations is clearly the most suitable in the light of this work. The thesis suggests a solution having both possibilities available to be chosen from in separate circumstances, realized with consistent standardization. It is evident, that if the preliminary assumption for the analysis is kept regarding to only one right place for the floor control server, more work is to be done in connected areas to discover the one most appropriate location.
  • Juvonen, Atte (2019)
    We present a new framework to evaluate the security of voting schemes. We utilize the framework to compare a wide range of voting schemes, including practical schemes in realworld use and academic schemes with interesting theoretical properties. In the end we present our results in a neat comparison table. We strive to be unambiguous: we specify our threat model, assumptions and scope, we give definitions to the terms that we use, we explain every conclusion that we draw, and we make an effort to describe complex ideas in as simple terms as possible. We attempt to consolidate all important security properties from literature into a coherent framework. These properties are intended to curtail vote-buying and coercion, promote verifiability and dispute resolution, and prevent denial-of-service attacks. Our framework may be considered novel in that trust assumptions are an output of the framework, not an input. This means that our framework answers questions such as ”how many authorities have to collude in order to violate ballot secrecy in the Finnish paper voting scheme?”
  • Dimakopoulos, Georgios (2022)
    The metamorphosed Kutemajärvi gold deposit is located near the town of Orivesi, at the eastern flank of the Tampere Schist Belt, which constitutes part of the Svecofennian domain of southern Finland, and it is hosted in the volcanic rocks of the Koskuenjärvi formation. Previous isotopic studies have mainly focused on the igneous and metamorphic rocks of the Tampere Schist Belt and only a few of them have presented ages for the area of Kutemajärvi. This study aims to shed light on the timing of mineralization by employing the single-grain U-Pb dating method of monazite and zircon, in order to evaluate the relationship between the ore and its host rocks. Based on the results from the SEM mineral identification, monazite grains are divided into metamorphic and hydrothermal grains. In the case of zircon grains, a third magmatic type has been identified. Results from U-Pb dating of single monazite and zircon grains are well constrained and document four distinct stages of geodynamic evolution in the region. Ages older than 1.91 Ga represent detrital material transported during the stage of rifting that led to the opening of the Tampere basin. Subsequent subduction resulted in active volcanism which is expressed with the extrusion of the Koskuenjärvi formation at 1904 Ma. At the late stages of subduction or at the outset of the collision stage, the subvolcanic Pukala porphyry intruded into the volcanic sequence of the Tampere Schist Belt at 1890 Ma, which provides the maximum mineralization age. Release of hydrothermal fluids, due to the crystallization of the Pukala intrusion caused pervasive hydrothermal alteration of the Kutemajärvi host rocks and deposition of epithermal gold and other elements. However, the participation of hydrothermal fluids, released by high-temperature metamorphism of the lower crust, cannot be ruled out. Ages between 1890‒1878 Ma record the syn-collision stage, during which the deposit, the Pukala intrusion and its adjoining rocks were deformed and metamorphosed at greenschist to lower-amphibolite facies. The majority of ages fall within the 1880‒1878 Ma time-interval, characterizing the metamorphic peak that marks the culmination of the Svecofennian orogeny and provides a minimum age of the mineralization. This major orogenic event is partly overlapped by the collision of the Central Svecofennian Arc Complex with the Southern Svecofennian Arc Complex that transpired at 1880‒1860 Ma, as indicated by ample age data. Monazite and zircon also yield lower ages (<1860 Ma), which record retrograde metamorphic and subordinate cooling events, and resonate recurring tectonothermal activity, associated with the syn- and post-collisional magmatism of Southern Svecofennia and the emplacement of rapakivi intrusions in southern Finland. Single-grain U-Pb dating of monazite and zircon from polished thin sections, in tandem with collation of the obtained ages with earlier published data, establishes a spatial and temporal framework with respect to the tectonometamorphic evolution of the Kutemajärvi gold deposit and the Tampere Schist Belt. Precise temporal constraints substantiate the intricate geological history of the area and can be used to discriminate magmatic, metamorphic and hydrothermal events, with a view to breaking ground on the exploration of other epithermal deposits in the metamorphic terranes of southern Finland.
  • Jimenez Reyes, Debanhi (2023)
    In Estonia and Gotland, Sweden Ordovician and Silurian rocks can be found in exposed outcrops, they have been studied for the past years to create a better understanding of the biological and geological events that transpire during the Ordovician and Silurian. Finland is not known to have sedimentary fossiliferous limestones, but the Åland Islands is one of the places where Ordovician and Silurian erratic limestones can be found. The limestones were glacially transported from the Bothnia Sea area. The erratic limestones found in the Åland Islands have not been studied and have not been dated. The goal of this research is to reconstruct the depositional age of the erratic crinoidal limestone from the Åland Islands through 13C, 87Sr/86Sr, and identification of microfossil proxies. We used in situ strontium isotope analysis by MC-ICP-MS and 13C analysis in different materials of the sample, the materials analyzed were cement, sediment matrix, and skeletal material (crinoid stem). The samples were sent to experts for microfossil identification. The Åland samples were compared with known samples from Estonia and Gotland. The samples from Niibi Estonia showed the most petrographical similarities and were also analyzed for strontium and carbon isotopes. The strontium analysis showed that the material had a different strontium signal, which then contributed to diagenetic alteration due to rubidium-87. It was observed that the sediment matrix was the most susceptible to any diagenetic alteration followed by the skeletal material and then the cement. There were conodonts found in the Åland samples that indicated that the erratic limestone is from the lower Haljala Regional Stage, Sandbian, Late Ordovician.
  • Salonen, Ella (2020)
    In this thesis we prove a generalized form of Mercer's theorem, and go through the underlying mathematics involved in the result. Mercer's theorem is an important result in the theory of integral equations, as it can be used as a tool in solving the trace of integral operators. With certain assumptions on a topological space X and measure space (X,dµ), the generalized theorem states that the trace of a positive and self-adjoint bounded integral operator on L^2(X,dµ) with a continuous kernel can be determined by integrating the diagonal of the kernel function. The integral operator being trace class depends then on whether the value of the integral is finite or not. We start the thesis by introducing the general settings we have for the theorem, and provide wider background for the main assumptions. We assume that X is a locally compact Hausdorff space that is σ-compact, and µ is a Radon measure on X with support equal to X. We also need the following technical assumption. Since X is σ-compact, then there exists an increasing sequence of compact subsets C_n with union equal to X. We assume that for each C_n there exists a sequence of increasingly fine partitions, compatible with the measure µ. We then go through the basics on Banach spaces, and we introduce the L^p spaces. Theory on Hilbert spaces is represented in greater detail. We introduce some classes of bounded linear operators on Hilbert spaces, including self-adjoint and positive operators. Some spectral theory is considered, first for Banach algebras in general, and then for the Banach algebra of bounded linear operators on a complex Banach space. The space of bounded linear operators on a Hilbert space can be seen as a C^*-algebra, and results for the spectrum of different kind of Hilbert space operators are given. Compact operators are first defined on Banach spaces. We prove that they form a closed, two-sided ideal in the algebra of bounded linear operators on a Banach space. We also consider compact operators on a Hilbert space, and of special interest are the Hilbert-Schmidt integral operators on the space L^2, which are proven to be compact. The existence of the canonical decomposition for compact operators is proven as this property is used in several proofs of the thesis. In the final chapter we focus on the theory of Hilbert-Schmidt operators and trace class operators on Hilbert spaces. We show that operators in these classes are compact. Considering the Hilbert-Schmidt operators on the space L^2, we prove that they then correspond to the Hilbert-Schmidt integral operators. A trace is first defined for a positive operator, and then for a trace class operator. Finally, in the last section, we construct a proof for the generalized form of Mercer's theorem. As a result, we find a way to determine the trace of an integral operator that satisfies the assumptions described in the first paragraph.
  • Page, Mathew (2021)
    Tiivistelmä – Referat – Abstract With rising income inequalities and increasing immigration in many European cities, residential segregation remains a key focus for city planners and policy makers. As changes in the socio-spatial configuration of cities result from the residential mobility of its residents, the basis on which this mobility occurs is an important factor in segregation dynamics. There are many macro conditions which can constrain residential choice and facilitate segregation, such as the structure and supply of housing, competition in real estate markets and legal and institutional forms of housing discrimination. However, segregation has also been shown to occur from the bottom-up, through the self-organisation of individual households who make decisions about where to live. Using simple theoretical models, Thomas Schelling demonstrated how individual residential choices can lead to unanticipated and unexpected segregation in a city, even when this is not explicitly desired by any households. Schelling’s models are based upon theories of social homophily, or social distance dynamics, whereby individuals are thought to cluster in social and physical space on the basis of shared social traits. Understanding this process poses challenges for traditional research methods as segregation dynamics exhibit many complex behaviours including interdependency, emergence and nonlinearity. In recent years, simulation has been turned to as one possible method of analysis. Despite this increased interest in simulation as a tool for segregation research, there have been few attempts to operationalise a geospatial model, using empirical data for a real urban area. This thesis contributes to research on the simulation of social phenomena by developing a geospatial agent-based model (ABM) of residential segregation from empirical population data for the Helsinki Metropolitan Area (HMA). The urban structure, population composition, density and socio-spatial distribution of the HMA is represented within the modelling environment. Whilst the operational parameters of the model remain highly simplified in order to make processes more transparent, it permits exploration of possible system behaviour by placing it in a manipulative form. Specifically, this study uses simulation to test whether individual preferences, based on social homophily, are capable of producing segregation in a theoretical system which is absent of discrimination and other factors which may constrain residential choice. Three different scenarios were conducted, corresponding to different preference structures and demands for co-group neighbours. Each scenario was simulated for three different potential sorting variables derived from the literature; socio-economic status (income), cultural capital (education level) and language groups (mother tongue). Segregation increases in all of the simulations, however there are considerable behavioural differences between the different scenarios and grouping variables. The results broadly support the idea that individual residential choices by households are capable of producing and maintaining segregation under the right theoretical conditions. As a relatively novel approach to segregation research, the components, processes, and parameters of the developed model are described in detail for transparency. Limitations of such an approach are addressed at length, and attention is given to methods of measuring and reporting on the evolution and results of the simulations. The potential and limitations of using simulation in segregation research is highlighted through this work.
  • Ruonala, Henna-Riikka (2017)
    A systematic literature review was conducted to examine the usage of agile methods in game development. A total of 23 articles were found which were analysed with the help of concept matrices. The results indicate that agile methods are used to varying degrees in game development. Agile methods lead to improved quality of games through a prototyping, playtesting, and feedback loop. Communication and ability of the team to take responsibility are also enhanced. Challenges arise from multidisciplinary teams, management issues, lack of training in agile methods, and quality of code.
  • Aintila, Eeva Katri Johanna (2016)
    Expected benefits from agile methodologies to project success have encouraged organizations to extend agile approaches to areas they were not originally intended to such as large scale information systems projects. Research regarding agile methods in large scale software development projects have existed for few years and it is considered as its own research area. This study investigates agile methods on the large scale software development and information systems projects and its goal is to produce more understanding of agile methods suitability and the conditions under which they would most likely contribute to project success. The goal is specified with three research questions; I) what are the characteristics specific to large scale software engineering projects or large scale Information Systems project, II) what are the challenges caused by these characteristics and III) how agile methodologies mitigate these challenges? In this study resent research papers related to the subject are investigated and characteristics of large scale projects and challenges associated to them are recognized. Material of the topic was searched starting from the conference publications and distributions sites related to the subject. Collected information is supplemented with the analysis of project characteristics against SWEBOK knowledge areas. Resulting challenge categories are mapped against agile practises promoted by Agile Alliance to conclude the impact of practises to the challenges. Study is not a systematics literature review. As a result 6 characteristics specific to large scale software development and IS projects and 10 challenge categories associated to these characteristics are recognized. The analysis reveals that agile practises enhance the team level performance and provide direct practises to manage challenges associated to high amount of changes and unpredictability of software process both characteristic to a large scale IS project but challenges still remain on the cross team and overall project level. As a conclusion it is stated that when seeking the process model with agile approach which would respond to all the characteristics of large scale project thus adding the likelihood of project success adaptations of current practises and development of additional practises are needed. To contribute this four areas for adaptations and additional practises are suggested when scaling agile methodologies over large scale project contexts; 1) adaptation of practises related to distribution, assignment and follow up of tasks, 2) alignment of practises related to software development process, ways of working and common principles over all teams, 3) developing additional practises to facilitate collaboration between teams, to ensure interactions with the cross functional project dimensions and to strengthen the dependency management and decision making between all project dimensions and 4) possibly developing and aligning practises to facilitate teams' external communication. Results of the study are expected to be useful for software development and IS project practitioners when considering agile method adoptions or adaptations in a large scale project context. ACM Computing Classification System (CCS) 2012: - Social and professional topics~Management of computing and information systems - Software and its engineering~Software creation and management
  • Haapa, Sanna K. (2018)
    The aim of the study is to inspect with GIS methods socio-economic structures in relation to homicides of youth in the context of Mexican Drug War. The escalation of violence has impacted youth, who fell victims to homicide more often since 2006. The study’s concentration is how the local conditions of poverty, marginalization risk of youth and violence of criminal organizations are related to elevated homicide rates of youth in 2005 and in 2010. Mexico was a relatively peaceful country before the escalation of violence since 2006. The crisis of violence has been branded by media as the Mexican Drug War, where over 200 000 people have died. Conflicts between criminal organizations and the changes in political atmosphere have been considered as main reasons for the escalation. However, the escalation of intentional homicides was recorded to exceed the areas where criminal organizations operate. The impact of increased violence on youth and the cost to the society underlie the importance of studying conditions of where violence takes place. There is no theoretical framework for conflicts where drug cartel related homicides and unrelated homicides increase at the same time, only other examples been recorded only in favelas of Brazil and to an extent in Columbia. Theoretical framework was drawn from comparing gang and criminologist studies to theories on civil conflicts. Through the literature, poverty has been theorized as a primary cause of increase in level of violence. The high marginalization risk of youth has been connected to criminal behaviour. The increased activity by criminal organizations has had an indisputable impact of murder rates. These three statements set the hypotheses for the thesis. The variables were collected to represent the municipal conditions of population, households and interest points of criminal organizations. The spatial analysis was conducted by using Ordinary Least Square Regression to represent the global impacts of variables across Mexico and Geographically Weighted Regression for the local variance. The results of analysis demonstrate that the spatial dimensions of violence have changed between 2005 and 2010. The homicides of youth have increased across the country, were more clustered in 2010 than in 2005. The results suggest that the increased number of homicides in 2010 are more strongly related to marginalization than to absolute poverty. The effect of variables for poverty fell in significance between 2005 and 2010. The marginalization on the other hand, seemed to have a greater explanatory power to local increase in young homicide victims in 2010, especially when concurring with bloodshed by criminal organizations. The violence between criminal organizations had the strongest increasing impact on homicide rates, non-existent in 2005 and eminent in 2010. The regression models’ performance was weaker in 2005 than in 2010. However, the moderately weak performance of regression models and the residuals suggest that the results are not comprehensive and further research is called for.
  • Viitanen, Akke Esa Tapio (2017)
    Active galactic nuclei (AGN) are compact, luminous objects found in the central region of many galaxies. In the standard paradigm, the AGN is fueled by accretion of matter into a supermassive black hole (SMBH). In fact, the properties of many galaxies and their respective SMBHs are linked, which hints at the importance of AGN as factors in galaxy formation and evolution. The bulk of the matter in the Universe is some form of dark matter, which is still poorly understood. AGN are biased tracers of the underlying dark matter distribution. By comparing the clustering of AGN with that of the dark matter, the bias may be quantified and further, the bias can be linked to a characteristic mass of the dark matter halo hosting the AGN. The advent of high-resolution X-ray telescopes, namely Chandra and XMM-Newton, has made unprecedently large samples available for study. With detailed spectroscopic follow-up programs, the study of X-ray selected AGN clustering has received a major boost. The clustering measurements tell of the typical environments that are likely to host AGN and thus shed light on what actually triggers the AGN. In this thesis, the clustering of ∼ 600 X-ray selected AGN with z < 2.5 (z = 1.19) in the COS- MOS (Cosmic evolution survey) field surveyed with XMM-Newton (XMM-COSMOS) is studied. The full sample is split into subsamples based on the host galaxy stellar mass M∗ and the ratio between the X-ray luminosity and the stellar mass LX/M∗ which is a proxy for the Eddington ratio. For the full sample the bias is 3.61+0.37−0.40, which corresponds to a characteristic halo mass of log M halo /h−1 M⊙ = 13.52+0.12−0.16 , consistent with the overall picture of X-ray selected AGN residing in massive haloes with 12.5 < logMhalo/h−1M⊙ < 13.5. The low M∗ and high M∗ samples have biases 3.53+0.58−0.70 and 4.13+0.85−1.07, respectively and the data do not support a difference in the typical masses of the hosting haloes. For the LX/M∗ subsamples, there is marginal evidence that low L X /M∗ AGN (logM halo /h−1M⊙ = 13.52+0.22−0.37) reside in more massive haloes than high L X /M∗ AGN (logM halo /h−1M⊙ = 13.29+0.28−0.58). One possible explanation would be that the environment of the low LX /M∗ AGN reduces the amount of gas available for accretion and thus results in lower accretion rates.