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  • Zou, Xiaochen (Helsingin yliopisto, 2015)
    Leaf angle distribution (LAD) is one of the most important parameters used to describe the structure of horizontally homogeneous vegetation canopies, such as field crops. LAD affects how incident photosynthetically active radiation is distributed on plant leaves, thus directly affecting plant productivity. However, the LAD of crops is difficult to quantify; usually it is assumed to be spherical. The purpose of this dissertation is to develop leaf angle estimation methods and study their effect on leaf area index (LAI) and chlorophyll a and b content (Cab) measured from optical observation. The study area was located in Viikki agricultural experimental field, Helsinki, Finland. Six crop species, faba bean, narrow-leafed lupin, turnip rape, oat, barley and wheat, were included in this study. A digital camera was used to take photographs outside the plot to record crop LAD. LAI and Cab were determined for each plot. Airborne imaging spectroscopy data was acquired using an AISA Eagle II imaging spectrometer covering the spectral range in visible and near-infrared (400 1000 nm). A recently developed method for the determination of leaf inclination angle was applied in field crops. This method was previously applied only to small and flat leaves of tree species. The error of LAI determination caused by the assumption of spherical LAD varied between 0 and 1.5 LAI units. The highest correlation between leaf mean tilt angle (MTA) and spectral reflectance was found at a wavelength of 748 nm. MTA was retrieved from imaging spectroscopy data using two algorithms. One method was to retrieve MTA from reflectance at 748 nm using a look-up table. The second method was to estimate MTA using the strong dependence of blue (479 nm) and red (663 nm) on MTA. The two approaches provide a new means to determine crop canopy structure from remote sensing data. LAI and MTA effects on Cab sensitive vegetation indices were examined. Three indices (REIP, TCARI/OSAVI and CTR6) showed strong correlations with Cab and similar performance in model-simulated and empirical datasets. However, only two (TCARI/OSAVI and CTR6) were independent from LAI and MTA. These two indices were considered as robust proxies of crop leaf Cab. Keywords: leaf angle; leaf area index; leaf chlorophyll; digital photograph; imaging spectroscopy; PROSAIL model; vegetation indices
  • Sillanpää, Maarit (Helsingin yliopisto, 2003)
  • Khazaei, Hamid (Helsingin yliopisto, 2014)
    The potential for use of faba bean (Vicia faba L.) is increasing worldwide due to its positive environmental impact and nutritional interest, but there are many challenges for faba bean breeding and cultivation. These include its mixed breeding system, its unknown origin and wild progenitor, its large genome being the biggest diploid genome among field crops, and its relative sensitivity to biotic and abiotic stresses (e.g., drought). Little is known about the ecological adaptation of faba bean germplasm, or about the locations and effects of genes that influence traits related to drought adaptation, especially stomatal morphology and function as key characters for gas exchange between plant and atmosphere. Thus, the current study had two main goals, a) to examine whether faba bean germplasm from drought-prone and drought-free environments differed in leaf traits related to drought adaptation while testing a novel genetic resources utilization tool, and b) to screen the genome for regions and candidate genes controlling morpho-physiological traits related to drought adaptation. Two sets of faba bean germplasm each containing 201 accessions from dry and wet regions of the world were chosen according to the principles of FIGS (the Focused Identification of Germplasm Strategy). Leaf morpho-physiological traits related to drought response (e.g., stomatal characteristics and water status) were measured under well watered conditions in a climate-controlled greenhouse. Thereafter, two subsets of 10 accessions each were exposed to water deficit. The significance of the difference between the two sets indicated the potential of FIGS to search for traits related to abiotic stress adaptation. Machine-learning algorithms and multivariate statistics showed that the discrimination between the two sets could be based on pertinent physiological traits, particularly leaf temperature and relative water content. When the plants exposed to water deficit, leaf temperature was the most responsive trait. Four bi-parental populations were developed, of which Mélodie/2 × ILB938/2 showed the highest number of polymorphic single nucleotide polymorphisms (SNPs) and was advanced to the F5 generation, in which 211 individuals were tested for 222 SNPs derived from Medicago truncatula sequence information. The population was phenotyped for several morpho-physiological traits during 2013 and 2014. In total, 188 polymorphic SNPs were assigned to nine linkage groups that covered ~ 928 cM with an average inter-marker distance of 5.8 cM. The map showed a high degree of synteny with the genome of M. truncatula. Most of the detected QTLs for stomatal morphology and function were in a single region of faba bean chromosome II syntenic with a segment of M. truncatula chromosome IV that harbours receptor-like protein kinase. Furthermore, a novel locus, ssp1, for stipule pigmentation was mapped in a well conserved region of M. truncatula chromosome V containing some candidate Myb and bHLH transcription factor genes. The difference between the leaf temperatures of the two FIGS sets (the wet and dry set) allowed us to find a reliable and cost-efficient phenotyping tool for screening drought adaptation related traits in this species. Furthermore, using an appropriate mapping population and using novel M. truncatula-derived SNPs all brought success to detect the genetic regions and to indicate candidate genes. Furthermore, our results confirm the genomic data from model plant species can easily be translated to faba bean. Finally, breeding faba bean for drought adaptation can be made more straightforward by combining the use of germplasm tools such as FIGS, rapidly assessed phenotypes such as canopy temperature, and genomic tools for detecting candidate genes.
  • Heinonen, Riku (2015)
    Tämän tutkielman tarkoituksena on tutkia, kuinka kohteena olevasta ohjelmistokehitysprojektista voidaan havainnoida hukkaa, minkä tyyppisiä ja kuinka paljon mitäkin hukkaa havaitaan ja kuinka näitä hukkia voidaan poistaa. Tutkielmassa esitellään myös yksi lähestymistapa hukan lähteiden poistamisen priorisointia varten. Tutkielmassa alussa tutustutaan Lean-ajatteluun yleisesti ja tarkemmin sen soveltamiseen ohjelmistokehityksessä. Erityisenä mielenkiinnon kohteena on Lean määritysten mukainen hukka sekä kuinka sitä voidaan havaita ja poistaa ohjelmistokehitysprosessista. Tutkielmassa myös esitellään käytetyt tutkimusmenetelmät, menetelmien tulokset ja analysoidaan niitä. Tarkastelun kohteena oli erään valtiollisen toimijan IT-yksikön ohjelmistokehitysprojekti, joka alkoi joulukuussa 2011 ja päättyi vuoden 2015 maaliskuussa. Projektissa käytettiin monia ketteriä kehitysmenetelmiä, mutta ei Lean-menetelmiä suoranaisesti. Tutkielman aineisto kerättiin kartoittamalla arvovirtoja sekä muistioiden, raporttien, haastatteluiden ja kyselyn sisältöanalyysillä. Havaitut hukan lähteet jaoteltiin ohjelmistokehitykseen sovellettuihin 7 hukan luokkaan ja niiden aiheuttamasta hukasta pyrittiin keräämään mahdollisimman paljon vertailukelpoista tietoa. Luokkien mitattua hukkaa myös verrattiin koettuun hukkaan, jota mitattiin kyselyllä. Projektista pystyttiin havainnoimaan jokaisen luokan mukaista hukkaa. Suurimmasta osasta saatiin kuitenkin vain viitteellistä tietoa, eikä näiden määrää tai vaikutusta pystytty projektista kerätyistä tiedoista osoittamaan. Ne hukat, jotka saatiin mitattua, olivat kyselylomakkeella kerätyn aineiston mukaan paljon hukkaa aiheuttavia. Vastavuoroisesti jotain merkittäviksi koettuja hukkia ei pystytty mitta-aineistosta havaitsemaan. Kerättyjen tietojen perusteella voitiin tehdä selviä johtopäätöksiä hukista ja antaa suosituksia näiden poistamiseksi tai niiden vaikutuksen vähentämiseksi. Jatkotutkimuksen kohteiksi tunnistettiin esimerkiksi annettujen suositusten vaikutuksen tarkasteleminen.
  • Ma, Qian (Helsingin yliopisto, 2014)
    Objectives. This research addressed the problems and prospects of Lean Six Sigma (LSS), one of the world's most popular organizational development methods at present. The study enriched this method by suggesting a more sustainable way of organizational development. The previous research on LSS mainly focused on the technical tools in utilizing the production process. Drawing on the theory of Expansive Learning, this research evaluated the learning process of LSS by focusing on the practitioners. The purpose of the research was twofold. First, it analyzed the contradictions of LSS project activity in the research site. It was expected to uncover the problems that jeopardized the learning process of the practitioners. Second, it discussed the zone of proximal development (ZPD) of LSS project activity for the research site, with the purpose of shedding light on the possibilities of future development and learning. Methods. The research site was an international aircraft manufacturer in China. Eleven LSS practitioners were interviewed, including eight Green Belts, one Black Belt, one Master Black Belt and one Green Belt team member. The data were analyzed by adopting three methods: the analysis of conceptions, the Analysis of discursive manifestations of contradictions, and the analysis of action-activity transformation in expansive learning. The ZPD was sketched from two dimensions: the first one by analyzing the action-activity transformation of the practitioners; the second one by evaluating the conception of “what have expanded” in the practitioners due to the project experiences. Results and conclusions. The analysis uncovered eight contradictions in LSS project activity system. Five were scattered in the project activity itself between or within varied elements of activity. Three were between the project activity, the department-based work activity and the LSS training activity. One case in which the GB's trials in breaking the constraints in his own project resulted in collective expansive learning efforts cross projects was analyzed as the representation of action-activity transformation. In addition, some practitioners had re-conceptualized their work motivation through the project experience, seeing Lean Six Sigma as a conceptual tool for understanding strategic work planning and gaining long-term work motivation. In conclusion, two dimensions of the ZPD were suggested: first, an integrated top-down and bottom-up approaches for organizational transformation; second, transcending from LSS as the “concrete tool in individual skill appropriation” to the “conceptual tool in collective work reconceptualization”. The organizations adopting the LSS method can reflect on this thesis to improve their LSS practices by paying attention to the “critical transition agent” for cross-functional processes’ interaction, the employees’ learning initiatives and work motivation.
  • Ikonen, Marko (Helsingin yliopisto, 2011)
    The history of software development in a somewhat systematical way has been performed for half a century. Despite this time period, serious failures in software development projects still occur. The pertinent mission of software project management is to continuously achieve more and more successful projects. The application of agile software methods and more recently the integration of Lean practices contribute to this trend of continuous improvement in the software industry. One such area warranting proper empirical evidence is the operational efficiency of projects. In the field of software development, Kanban as a process management method has gained momentum recently, mostly due to its linkages to Lean thinking. However, only a few empirical studies investigate the impacts of Kanban on projects in that particular area. The aim of this doctoral thesis is to improve the understanding of how Kanban impacts on software projects. The research is carried out in the area of Lean thinking, which contains a variety of concepts including Kanban. This article-type thesis conducts a set of case studies expanded with the research strategy of quasi-controlled experiment. The data-gathering techniques of interviews, questionnaires, and different types of observations are used to study the case projects, and thereby to understand the impacts of Kanban on software development projects. The research papers of the thesis are refereed, international journal and conference publications. The results highlight new findings regarding the application of Kanban in the software context. The key findings of the thesis suggest that Kanban is applicable to software development. Despite its several benefits reported in this thesis, the empirical evidence implies that Kanban is not all-encompassing but requires additional practices to keep development projects performing appropriately. Implications for research are given, as well. In addition to these findings, the thesis contributes in the area of plan-driven software development by suggesting implications both for research and practitioners. As a conclusion, Kanban can benefit software development projects but additional practices would increase its potential for the projects.
  • Toiviainen, Hanna (Helsingin yliopisto, 2003)
  • Pereira Querol, Marco Antonio (Helsingin yliopisto, 2011)
    This study is about the challenges of learning in the creation and implementation of new sustainable technologies. The system of biogas production in the Programme of Sustainable Swine Production (3S Programme) conducted by the Sadia food processing company in Santa Catarina State, Brazil, is used as a case example for exploring the challenges, possibilities and obstacles of learning in the use of biogas production as a way to increase the environmental sustainability of swine production. The aim is to contribute to the discussion about the possibilities of developing systems of biogas production for sustainability (BPfS). In the study I develop hypotheses concerning the central challenges and possibilities for developing systems of BPfS in three phases. First, I construct a model of the network of activities involved in the BP for sustainability in the case study. Next, I construct a) an idealised model of the historically evolved concepts of BPfS through an analysis of the development of forms of BP and b) a hypothesis of the current central contradictions within and between the activity systems involved in BP for sustainability in the case study. This hypothesis is further developed through two actual empirical analyses: an analysis of the actors senses in taking part in the system, and an analysis of the disturbance processes in the implementation and operation of the BP system in the 3S Programme. The historical analysis shows that BP for sustainability in the 3S Programme emerged as a feasible solution for the contradiction between environmental protection and concentration, intensification and specialisation in swine production. This contradiction created a threat to the supply of swine to the food processing company. In the food production activity, the contradiction was expressed as a contradiction between the desire of the company to become a sustainable company and the situation in the outsourced farms. For the swine producers the contradiction was expressed between the contradictory rules in which the market exerted pressure which pushed for continual increases in scale, specialisation and concentration to keep the production economically viable, while the environmental rules imposed a limit to this expansion. Although the observed disturbances in the biogas system seemed to be merely technical and localised within the farms, the analysis proposed that these disturbances were formed in and between the activity systems involved in the network of BPfS during the implementation. The disturbances observed could be explained by four contradictions: a) contradictions between the new, more expanded activity of sustainable swine production and the old activity, b) a contradiction between the concept of BP for carbon credits and BP for local use in the BPfS that was implemented, c) contradictions between the new UNFCCC1 methodology for applying for carbon credits and the small size of the farms, and d) between the technologies of biogas use and burning available in the market and the small size of the farms. The main finding of this study relates to the zone of proximal development (ZPD) of the BPfS in Sadia food production chain. The model is first developed as a general model of concepts of BPfS and further developed here to the specific case of the BPfS in the 3S Programme. The model is composed of two developmental dimensions: societal and functional integration. The dimension of societal integration refers to the level of integration with other activities outside the farm. At one extreme, biogas production is self-sufficient and highly independent and the products of BP are consumed within the farm, while at the other extreme BP is highly integrated in markets and networks of collaboration, and BP products are exchanged within the markets. The dimension of functional integration refers to the level of integration between products and production processes so that economies of scope can be achieved by combining several functions using the same utility. At one extreme, BP is specialised in only one product, which allows achieving economies of scale, while at the other extreme there is an integrated production in which several biogas products are produced in order to maximise the outcomes from the BP system. The analysis suggests that BP is moving towards a societal integration, towards the market and towards a functional integration in which several biogas products are combined. The model is a hypothesis to be further tested through interventions by collectively constructing the new proposed concept of BPfS. Another important contribution of this study refers to the concept of the learning challenge. Three central learning challenges for developing a sustainable system of BP in the 3S Programme were identified: 1) the development of cheaper and more practical technologies of burning and measuring the gas, as well as the reduction of costs of the process of certification, 2) the development of new ways of using biogas within farms, and 3) the creation of new local markets and networks for selling BP products. One general learning challenge is to find more varied and synergic ways of using BP products than solely for the production of carbon credits. Both the model of the ZPD of BPfS and the identified learning challenges could be used as learning tools to facilitate the development of biogas production systems. The proposed model of the ZPD could be used to analyse different types of agricultural activities that face a similar contradiction. The findings could be used in interventions to help actors to find their own expansive actions and developmental projects for change. Rather than proposing a standardised best concept of BPfS, the idea of these learning tools is to facilitate the analysis of local situations and to help actors to make their activities more sustainable.
  • Kontinen, Tiina (Helsingin yliopisto, 2007)
    Non-governmental organisations (NGOs) have gained an important role in development co-operation during the last two decades. The development funding channelled through NGOs has increased and the number of NGOs engaged in development activities, both North and South, has been growing. Supporting NGOs has been seen as one way to strengthen civil society in the South and to provide potential for enhancing more effective development than the state, and to exercise participatory development and partnership in their North-South relationships. This study focuses on learning in the co-operation practices of small Finnish NGOs in Morogoro, Tanzania. Drawing on the cultural-historical activity theory and the theory of expansive learning, in this study I understand learning as a qualitative change in the actual co-operation practices. The qualitative change, for its part, emerges out of attempts to deal with the contradictions in the present activity. I use the concept of developmental contradiction in exploring the co-operation of the small Finnish NGOs with their Tanzanian counterparts. Developmental contradiction connects learning to actual practice and its historical development. By history, in this study I refer to multiple developmental trajectories, such as trajectories of individual participants, organisations, co-operation practices and the institutional system in which the NGO-development co-operation is embedded. In the empirical chapters I explore the co-operation both in the development co-operation projects and in micro-level interaction between partners taking place within the projects. I analyse the perceptions of the Finnish participants about the different developmental trajectories, the tensions, inclusions and exclusions in the evolving object of co-operation in one project, the construction of power relations in project meetings in three projects, and the collision of explicated partnership with the emerging practice of trusteeship in one project. On the basis of the empirical analyses I elaborate four developmental contradictions and learning challenges for the co-operation. The developmental contradictions include: 1) implementing a ready-made Finnish project idea vs. taking the current activities of Tanzanian NGO as a starting point; 2) gaining experiences and cultural interaction vs. access to outside funding; 3) promoting the official tools of development co-operation in training vs. use of tools and procedures taken from the prior activities of both partners in actual practice; and 4) asymmetric relations between the partners vs. rhetoric of equal partnership. Consequently, on the basis of developmental contradictions four learning challenges are suggested: a shift from legitimation of Finnish ideas to negotiation, transcending the separate objects and finding a partly joint object, developing locally shared tools for the co-operation, and identification and reflection of the power relations in the practice of co-operation. Keywords: activity theory; expansive learning; NGO development co-operation; partnership; power
  • Korpela, Laura (Helsingfors universitet, 2013)
    Tavoite: CLIL, sisältöpainotteinen kieltenopetus, on yleistynyt Suomessa 1980-luvulta lähtien. Sillä viitataan opetusmuotoon, jossa sisältöjä opiskellaan vieraalla kielellä. Vieras kieli on sekä oppimisen kohde että väline. CLIL voidaan toteuttaa joko pelkkänä sisällönopetuksena tai siten, että oppilaat osallistuvat myös formaaliin kielenopetukseen. Oppimistulokset ovat olleet rohkaisevia niin kielen- kuin sisällönoppimisen osalta. Vieraan kielen rakenteiden ja kieliopin hallinnan on kuitenkin todettu olevan CLIL-oppilailla heikompaa kuin perinteisesti kieltä opiskelleilla oppilailla. Aiemmista tutkimuksista monet on tehty ympäristöissä, joissa CLIL-oppilaat eivät osallistu lainkaan formaaliin kohdekielen opetukseen. Tämä tutkimus pyrkii selvittämään, onko oppilasryhmien kieliopin hallinnassa eroja sellaisessa ympäristössä, jossa CLIL-oppilaat ovat osallistuneet alusta lähtien myös formaaliin kielenopetukseen, sillä tutkimusten mukaan tämä tukee kielen rakenteiden omaksumista. Tutkimuksen tarkoitus on analysoida, kuvailla ja tulkita mitä eroja on CLIL-oppilaiden ja perinteisesti kieltä opiskelleiden oppilaiden englannin kieliopin hallinnassa. Tutkimuskohteena ovat sekä implisiittinen kielitaito että tuottamistaidot kirjoitetussa kielessä. Tutkimuksen perimmäisenä tavoitteena on lisätä tietoa vieraan kielen oppimisen luonteesta ja haasteista CLIL-kontekstissa sekä CLIL-opetuksen kehitystarpeista. Tutkimusmenetelmät: Tutkimuksen vastaajina oli yhteensä 30 alakoulun oppilasta, joista 14 kävi kaksikielistä (CLIL) viidettä luokkaa ja 16 suomenkielistä kuudetta luokkaa. Kyseessä oli tapaustutkimus. Aineisto kerättiin keväällä 2013 kahdeksansivuisen kielikokeen avulla. Kielikokeen neljä osiota mittasivat implisiittistä kielitaitoa, rakenteiden hallintaa sekä kirjallisia tuottamistaitoja. Aineisto analysoitiin tilastollisin menetelmin SPSS-ohjelman avulla. Lisäksi oppilaiden tuottamat virheet käännöstehtävässä ja luovissa kirjoitelmissa analysoitiin kuvailevan virheanalyysin menetelmällä. Tulokset: Tulokset osoittivat, että CLIL-oppilaiden implisiittinen kielitaito ja kirjalliset tuottamistaidot englannin kielessä olivat kokonaisuudessaan paremmat kuin suomenkielisen luokan oppilailla. CLIL-oppilailla oli parempi implisiittinen kieliopin hallinta ja englannin rakenteiden tuntemus, ja he tuottivat virheettömämpää ja idiomaattisempaa tekstiä niin käännöstehtävässä kuin luovassa kirjoitelmassa. Virheanalyysi osoitti, että suomenkielisen luokan oppilailla oli taipumus käyttää CLIL-oppilaita yleisemmin puutteellisia (omissions) tai virheellisiä rakenteita (false concepts hypothesized), virheellisiä yleistyksiä (overgeneralizations) ja suomen kielen sanajärjestystä (transfer from L1). Molemmat ryhmät tekivät yleisesti prosessointiongelmista (processing problems) johtuvia virheitä, mutta CLIL-oppilailla nämä juontuivat selvemmin sanojen ääntämisasusta, minkä voi tulkita osoitukseksi suuremmasta suullisesta altistuksesta kohdekielelle. Aineisto osoitti myöskin, että CLIL-oppilaat olivat englannin taitotasoltaan suomenkielisten luokkien oppilaita homogeenisempi ryhmä. Tämä voi johtua paitsi toimivasta CLIL-opetuksesta, suuremmasta päivittäisestä altistuksesta kohdekielelle, kuin myös soveltuvuuskokeesta, jonka perusteella CLIL-oppilaat valikoidaan kaksikielisille luokille. Kaiken kaikkiaan tutkimustulokset osoittivat, että kohdekielen oppimistulokset ovat lupaavia sellaisessa CLIL-opetuksessa, jossa yhdistetään sisällönopetusta ja formaalia kohdekielen opetusta.
  • Ryynänen, Max (Helsingin yliopisto, 2009)
    Learning from Venice is a philosophical learning diary on what a highly original city can teach urban aesthetics. Throughout history, classical cities have been interpreted and experienced in various ways. But aesthetics has never been accentuated as much as today. Venice has been an important center of commerce, a naval power, and it has had a lot of influence in arts and culture. But in our days it is a tourist trap and a cluster of so called world heritage. The development of tourism is the main reason for the fact that many old cities have become venues for leisure and entertainment, sometimes so that everyday life itself has been pushed to the margins. There is a lot one can learn by studying the history of the aesthetic appreciation of a city. Sometimes the way a city has been enjoyed has changed following the development of traffic. In Venice water buses have replaced the slow and silent gondolas, and since the building of the railway tourists have been approaching the city from a new direction, so that her façade which was built for seafarers has almost become forgotten. There are also themes of change and mobility which are peculiarly Venetian. What is the nature of a city where there are more tourists than inhabitants? And how does one experience a city where water dominates? These questions, and many more, are discussed in Learning from Venice, and side by side with applied aesthetics, the work of philosophers like Walter Benjamin, Gianni Vattimo, and John Dewey, among many others, enter a dialogue with this extraordinary city. Themes discussed include also e.g. walking, surface and depth, Venice as kitsch, and Venice as a museum.
  • Luukkonen, Petri Samuel (2015)
    In this thesis, a theoretical background of algorithms called NLS-BB-NMF and K-SVD for computing the image dictionary have been introduced. The NLS-BB-NMF algorithm computes the matrix factorization V ≈ WH of the training data matrix V (in our case the set of image patches from training image) using gradient descent methods by applying non-negative constraint on matrices W and H. The K-SVD in turn computes the matrix factorization WH applying sparsity constraint on the coefficient matrix H using Orthogonal Matching Pursuit (OMP) and Singular Value Decomposition (SVD). In the factorization, matrix W is the so called dictionary and it contains features, also called atoms, of the data V . The atoms serve as a building blocks of the original data, and they are also assumed to represent data that is similar to the training data V . The testing of the methods were carried in two phases. Initially, in the so called training phase, the dictionary was learned by the algorithms from a training image. The visual structure of the atoms learned by the algorithms were notably different although the approximations WH made by both dictionaries were visually very close to the original image. The visual difference between the learned dictionaries was seen as a consequence of the sparsity constraint that was forced for the coefficient matrix in K-SVD but not in NLS-BB-NMF. Secondly, in the test phase, a test image with various noise levels was approximated using the learned dictionary. The algorithms were able to produce approximations that were closer to the clean test image than the noisy test image. This was seen as the effect of dictionaries whose atoms were representing only the features of clean images. This observation led to a second test where the algorithms were tested to compute the denoised reconstructions of the test image with varying noise levels by using an extended dictionary contai- ning additionally atoms learned from a noise sample. The qualities of the reconstructions were evaluated by using the Frobenius matrix norm and Struc- tural Similarity (ssim) index that has been observed to adapt better the visual perception of human eyes.
  • Lindgren, Jussi T (Helsingin yliopisto, 2008)
    The paradigm of computational vision hypothesizes that any visual function -- such as the recognition of your grandparent -- can be replicated by computational processing of the visual input. What are these computations that the brain performs? What should or could they be? Working on the latter question, this dissertation takes the statistical approach, where the suitable computations are attempted to be learned from the natural visual data itself. In particular, we empirically study the computational processing that emerges from the statistical properties of the visual world and the constraints and objectives specified for the learning process. This thesis consists of an introduction and 7 peer-reviewed publications, where the purpose of the introduction is to illustrate the area of study to a reader who is not familiar with computational vision research. In the scope of the introduction, we will briefly overview the primary challenges to visual processing, as well as recall some of the current opinions on visual processing in the early visual systems of animals. Next, we describe the methodology we have used in our research, and discuss the presented results. We have included some additional remarks, speculations and conclusions to this discussion that were not featured in the original publications. We present the following results in the publications of this thesis. First, we empirically demonstrate that luminance and contrast are strongly dependent in natural images, contradicting previous theories suggesting that luminance and contrast were processed separately in natural systems due to their independence in the visual data. Second, we show that simple cell -like receptive fields of the primary visual cortex can be learned in the nonlinear contrast domain by maximization of independence. Further, we provide first-time reports of the emergence of conjunctive (corner-detecting) and subtractive (opponent orientation) processing due to nonlinear projection pursuit with simple objective functions related to sparseness and response energy optimization. Then, we show that attempting to extract independent components of nonlinear histogram statistics of a biologically plausible representation leads to projection directions that appear to differentiate between visual contexts. Such processing might be applicable for priming, \ie the selection and tuning of later visual processing. We continue by showing that a different kind of thresholded low-frequency priming can be learned and used to make object detection faster with little loss in accuracy. Finally, we show that in a computational object detection setting, nonlinearly gain-controlled visual features of medium complexity can be acquired sequentially as images are encountered and discarded. We present two online algorithms to perform this feature selection, and propose the idea that for artificial systems, some processing mechanisms could be selectable from the environment without optimizing the mechanisms themselves. In summary, this thesis explores learning visual processing on several levels. The learning can be understood as interplay of input data, model structures, learning objectives, and estimation algorithms. The presented work adds to the growing body of evidence showing that statistical methods can be used to acquire intuitively meaningful visual processing mechanisms. The work also presents some predictions and ideas regarding biological visual processing.
  • Kääriäinen, Matti (Helsingin yliopisto, 2004)
  • El-Najjar, Nahed (Helsingin yliopisto, 2010)
    Colorectal cancer (CRC) is a major health concern and demands long-term efforts in developing strategies for screening and prevention. CRC has become a preventable disease as a consequence of a better understanding of colorectal carcinogenesis. However, current therapy is unsatisfactory and necessitates the exploration of other approaches for the prevention and treatment of cancer. Plant based products have been recognized as preventive with regard to the development of colon cancer. Therefore, the potential chemopreventive use and mechanism of action of Lebanese natural product were evaluated. Towards this aim the antitumor activity of Onopordum cynarocephalum and Centaurea ainetensis has been studied using in vitro and in vivo models. In vitro, both crude extracts were non cytotoxic to normal intestinal cells and inhibited the proliferation of colon cancer cells in a dose-dependent manner. In vivo, both crude extracts reduced the number of tumors by an average of 65% at weeks 20 (adenomas stage) and 30 (adenocarcinomas stage). The activity of the C. ainetensis extract was attributed to Salograviolide A, a guaianolide-type sesquiterpene lactone, which was isolated and identified through bio-guided fractionation. The mechanism of action of thymoquinone (TQ), the active component of Nigella sativa, was established in colon cancer cells using in vitro models. By the use of N-acetyl cysteine, a radical scavenger, the direct involvement of reactive oxygen species in TQ-induced apoptotic cells was established. The analytical detection of TQ from spiked serum and its protein binding were evaluated. The average recovery of TQ from spiked serum subjected to several extraction procedures was 2.5% proving the inability of conventional methods to analyze TQ from serum. This has been explained by the extensive binding (>98%) of TQ to serum and major serum components such as bovine serum albumin (BSA) and alpha-1-acid glycoprotein (AGP). Using mass spectrometry analysis, TQ was confirmed to bind covalently to the free cysteine in position 34 and 147 of the amino acid sequence of BSA and AGP, respectively. The results of this work put at the disposal for future development new plants with anti-cancer activities and enhance the understanding of the pharmaceutical properties of TQ, a prerequisite for its future clinical development.
  • Eskelinen, Helena (Helsingfors universitet, 2006)
    Tutkielman aiheena on ekfrasis Gabriele D'Annunzion romaanissa Il Piacere (1889). Lähtökohtana on selvittää, millaisissa muodoissa ekfrasis esiintyy romaanissa sekä miten ekfrasis vaikuttaa teoksen tulkintatradition esille tuomaan tematiikkaan. Pyrkimyksenä on myös selkeyttää ekfrasiksen käsitettä, jonka ongelmana ovat sanaan eri aikakausina liitetyt eri merkitykset. Tärkeimpiä lähdeteoksia ovat James A.W. Heffernanin Museum of Words (1993) ja W.J.T. Mitchellin Picture Theory (1994), Marinella Cantelmon Il Piacere dei leggitori: D'Annunzio e la comunicazione letteraria (1996) sekä John Hollanderin artikkeli "The Poetics of Ekphrasis" (1988). Tutkielman avainkäsitteenä on Heffernanin määritelmä, jonka mukaan ekfrasis on sanallinen esitys kuvallisesta esityksestä. Määritelmää sovellettaessa on otettu huomioon representaatiokäsityksen avautuminen, jolloin vastaanottaja, ympäristö etc. ovat osa esitystä. Korpuksen muodostavat tapahtumaympäristöä, taideteoksia, esineistöä ja henkilöhahmoja kuvaavat ekfrastiset katkelmat. Luokittelussa toimivat alakäsitteinä Valerie Robillardin kuvaileva, attributiivinen ja assosiatiivinen ekfrasis sekä Tamar Yacobin ekfrastinen vertaus. Analyysi osoittaa, että kuvaileva ekfrasis on yleisin, mutta vain kuvitteellisten teosten yhteydessä. Katkelmissa on näkyvissä ekfrasikselle luonteenomainen kerronnallinen impulssi. Ekfrasis osallistuu tunnetun ja uuden elementin vuoropuheluun ankkuroimalla kuvitteelliset taideteokset lukijalle tuttuun ympäristöön, jolloin myös uusi tulee toden kaltaiseksi. Attributiivinen ekfrasis takaa välittömän tunnistettavuuden. Henkilöhahmot, erityisesti keskeiset naishahmot, on määritelty ekfrastisten vertausten kautta. Ekfrasis ilmentää osaltaan naishahmojen vaihdettavuuden tematiikkaa. Kyseessä on myös toiseuden haltuunotto. Kuvallisen viittaussuhteen ansiosta ekfrasis toimii tehokeinona. Tekstuaalisena strategiana ekfrasis luo siteitä tapahtumien välille ja rytmittää teoksen vaiheita. Ekfrastiset katkelmat tarjoavat myös väylän vaihtoehtoiselle tulkinnalle haastamalla tekstin totuuskäsityksen. Kuvallinen ja sanallinen esitys tuovat tekstiin omat merkityksensä, jolloin merkityskenttä laajenee. Il Piacere on intertekstuaalinen kollaasi, jossa kokonaiskuva muodostuu eri elementtien vuorovaikutuksesta. D'Annunzion mielestä kauneus on taiteen ensisijainen tarkoitus, ja ekfrasis retorisena keinona on osa pyrkimystä tavoittaa täydellinen muoto.