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  • Li, Ning (Helsingfors universitet, 2009)
    This exploratory study aims to analyze the CR reporting by eleven largest forest products companies in North America. Both annual reports and sustainability reports produced in year 2006 by eleven largest forest products companies in North America were chosen for this very study. To ensure the comparability of the results, the study adopts the similar variables in operationalizations by Routto (2008), who studied the CR reporting of European forest products companies. The methodology applied in the study is content analysis. Mean, T-test and One-way Anova analysis were used in data analysis. Though all the three pillars of CR (economic, environmental, and social) were covered in their CR reporting, the North American companies seem to give more weight to Social Focus, followed by Economic Focus and Environmental Focus respectively, whereas the largest European companies considered Environmental Focus as the most important area, Social Focus the second, whereas Economic Focus was least emphasized. A number of notable differences and similarities between the European companies and the North American companies towards CR reporting were also identified. For example, the North American companies obviously seek for more efforts to co-operate with interest groups and business partners to ensure responsible actions than the European companies. The European companies emphasize energy consumption more frequently than the North American companies. Neither the European companies nor the North American companies perceived environmental welfare at the expense of corporate profits an important element concerning Economic Focus. It would be interesting to note that neither the European companies nor the North American companies considered shareholders, NGOs and forest owners as primary target audience groups in their CR reporting, since the communication benefits were not frequently mentioned for these stakeholder groups. The study also observes some variation of CR practices within a common industrial and cultural environment. The results suggest that the US companies seem to particularly emphasize a number of issues more than the Canadian companies, namely: 1) Business behavior, 2) Social principles & guidelines, 3) Internal communication, 4) Social focus, 5) External communication, and 6) Audience. No significant difference was found concerning Social & ethical accounting and Economic focus between the US companies and the Canadian companies. Sector of Integrated forest products placed notably much more weight on Social & ethical accounting than Sectors of Consumer products and Sector of Pulp & paper & packaging in this study, whereas no other significant difference was indicated by the pair-wise comparison of means between Sector and the nine summative variables respectively. In addition, sustainability reports seem to have much clear focus on environmental-related issues than annual reports, whereas issues concerning Social Focus and External Communication received more attention in annual reports than in sustainability reports. No further significant difference was suggested between Type of report and the nine summative variables in this study. In short, the comparison between the reports by North American companies and those by the European companies showed some regional variations in CR reporting. These regional characteristics include 1) the emphasis on Social Focus by North American companies, and Environmental Focus by European companies, 2) the emphasis on partnership by North American companies, and workplace safety by European companies, 3) the emphasis on employees’ benefits by North American companies, and customers’ benefits by European companies, 4) the emphasis on commitment of top management to CR by North American companies, and existence of CR policy statements by European companies, 5) the emphasis on recycled raw materials by North American companies, and energy consumption by European companies, and 6) the emphasis on profitability by North American companies, and investing to socially/environmentally responsible targets by European companies. Such differences could also be argued to be related to the different institutional arrangements in the regions. The comparison between different sectors suggests that, Sector of Integrated forest products emphasized Social & Ethical Accounting more than Sector of Consumer products and Sector of Pulp & paper & packaging, whereas Sector of Consumer products paid more attention to Economic Focus issues than the other two sectors. The results also suggests that, sustainability reports emphasized Environmental Focus more than annual reports, whereas annual reports clearly focused on Social Focus and External Communication more than sustainability reports.
  • Nippala, Jaakko (Helsingfors universitet, 2014)
    Corporate social responsibility and sustainability have become increasingly important in modern business practices. The purpose of this study was to examine the corporate social responsibility (CSR) and sustainability practices and perceptions of small and medium-sized forest products companies in North Carolina (NC). These companies have less than 500 employees and most of the forest products companies operating in NC fall into this category. Research was carried out in two parts: first by conducting a content analysis of 22 websites of NC companies and second by conducting twelve semi-structured in-depth interviews with different company representatives to gain a deeper understanding of the practices and perceptions. The most frequently mentioned aspect in the websites was sustainability (48.6%), followed by CSR (19.8%). Most often mentioned CSR practices from the websites were safety and promotion of responsible forestry. Interviews identified social aspects of CSR as the most important for respondents. This is interesting since, according to earlier research, the forest industry tends to emphasize environmental aspects. The main drivers for CSR and sustainability were the owners and, to some extent, customers. Other stakeholders were not identified as important drivers. Interviews revealed that the company size is not really a defining aspect on implementation of CSR and sustainability, but it is instead a company specific initiative. Identifying and describing these effective patterns and practices of CSR and sustainability could help other small businesses create competitive advantages in forest products marketing. These practices can then be used as building blocks for sustainable and responsible business strategy.
  • Yi, Xinxin (2015)
    Problem: Helsinki psychotherapy study (HPS) is a quasi-experimental clinical trial, which is designed to compare the effects of different treatments (i.e. psychotherapy and psychoanalysis) on patients with mood and anxiety disorders. During its 5-year follow-ups from the year 2000 to 2005, repeated measurements were carried out at 0, 12, 24, 36, 48, 60 months. However, some individuals did not show up at certain data collection points or dropped out of the study forever, leading to the occurrence of missing values. This will prevent the applications of further statistical methods and violate the intention-to-treat (ITT) principle in longitudinal clinical trials (LCT). Method: Multiple Imputation (MI) has many claimed advantages in handling missing values. This research will compare different MI methods i.e. Markov chain Monte Carlo (MCMC), Bayesian Linear Regression (BLR), Predictive Mean Matching (PMM), Regression Tree (RT), Random Forest (RF) in their treatments of HPS missing data. The statistical software is SAS PROC MI procedure (version 9.3) and R MICE package (version 2.9). Results: MI has better performance than the ad-hoc methods such as listwise deletion in the detections of potential relationships and the reduction of potential biases in parameter estimations if missing completely at random (MCAR) assumption is not satisfied. PMM, RT and RF have better performance in generating imputed values inside the range of the observed data than BLR and MCMC. The machine learning methods i.e. RT and RF are preferable than the regression methods such as PMM and BLR since the imputed data have quite similar distribution curves and other features (e.g. median, interguatile, skewness of distribution) as the observed data. Implications: It is suggestive to use MI methods to replace those ad-hoc methods in the treatments of missing data, if additional efforts and time are not a problem. The machine learning methods such as RT and RF are more preferable than those relatively arbitrary user-specified regression methods such as PMM and BLR according to our data, but further research are required to approve this indication. R is more flexible than SAS where RT and RF can be applied.
  • Lehtinen, Jukka (Helsingin yliopisto, 2015)
    Need for higher productivity motivates and forces farmers to adapt new technological solutions. Global Navigation Satellite Systems (GNSS) have enabled several solutions to increase efficiency specially in field operations in terms of assisted or automatic steering, yield monitoring and precision farming. Accuracy of raw GNSS-data is poor and not suitable for any field operation. Methods to minimize error caused by different sources are in conclusive role to adapt positioning solutions to agriculture and to field operations. Aim of this study was to compare different GNSS correction methods by means of static and dynamic measurements. Results of the measurements occurred that high precision is achievable. Ground Based Augmentation Systems (GBAS) were more precise (RTK base station, AgriVRS and Centerpoint RTX) than Space Based Augmentation Systems (SBAS) (Omnistar G2 and Egnos). RMS values in 8 hour static measurements were between 0.004 and 0.406 m. Autonomic positioning RMS value was 1.014 m. In dynamic measurements scale was from 1.610 m to 0.015 m. Correction methods performed better in relative positioning than in repeating same position in subsequent days. Automatic steering is possible with every correction method. When using paid license corrections accuracy rises. Accuracy should be chosen by need of the field work, for example seeding needs higher accuracy than broadcasting of fertilizer. Due to Northern location of Finland SBAS are not available everywhere. Correction sent from satellite can be blocked for example by tree line. Also radio signal is hard to utilise in data transfer due to scattered field structure. Finland has excellent cellular network. Corrections loaded via cellular to receiver were available in test sites most practically.
  • Koponen, Kristine (2013)
    The cross-country co-movements of economic variables have been documented in the macroeconomic research. This phenomenon has puzzled researchers in the field of dynamic stochastic general equilibrium (DSGE) models because the early DSGE models have had challenges in replicating the co-movements of outputs. The thesis approaches the cross-country co-movements of output cycles in DSGE models by introducing correlation to technology shocks. The objective is to study if the correlation in the technology shocks enhances the model's ability to capture the cross-country correlations of empirical data. The thesis presents a two-country DSGE model that is constructed using the results of Galí and Monacelli (2005). The original model of Galí and Monacelli is a small-country model, and in the thesis it is demonstrated how the model is re-constructed as consisting of two large economic regions. Another important modification to the original model is that the thesis presents a distinctive shock process that allows the technology shocks to correlate. This is done by adding a foreign technology shock variable to the domestic technology shock process. The final model is presented as a system of thirteen equations and, as a solution to the system, the dynamics of the model are observed. The results from the model show that the two-country model with correlated shock processes is able to replicate the cross-country correlations of empirical data well. This result is compared to the benchmark model with no shock correlations and the comparison reveals that although the benchmark model succeeds in replicating the cross-country correlations between inflations and nominal interest rates, it does not produce as high output gap correlation as the model with correlated shock processes. The difference between these models is caused by the distinctive shock processes. The technology shocks affect directly the potential output and the real output adjusts slowly as a response to the changes in the expectations. This causes the dynamics in the output cycle. The results of the thesis show evidence that introducing correlation between country-specific technology shocks can enhance the models ability to produce realistic cross-country output co-movements. This result should apply to other models that follow the framework of Galí and Monacelli. The generalization of the results could still be studied further. In addition, including new features to the model would allow for examination of wider variety of shocks.
  • Pöyhönen, Aino (2001)
    Kyvystä tuottaa innovaatioita on tullut yritysten tärkein menestystekijä. Tietotyöntekijät ovat avainasemassa kilpailuetua tuottavien uudistusten luomisessa. Tämä tutkimus käsitteli innovaation edellytyksiä tietotyöntekijöistä koostuvissa tiimeissä. Tavoitteena oli selvittää millä tavoin tietotyötiimien innovatiivisuus on yhteydessä tiimin sekakoosteisuuteen, tiimin sisäiseen vuorovaikutukseen sekä yhteistyöhön tiimin ulkopuolisten tahojen kanssa. Innovaatioista tietotyötiimeissä on olemassa varsin vähän aikaisempaa tutkimusta. Niinpä tämän tutkimuksen teoreettinen viitekehys pyrittiin rakentamaan monipuoliseksi, jotta se kattaisi mahdollisimman laajasti ne ryhmätasoiset tekijät jotka vaikuttavat tiimien kykyyn tuottaa innovaatioita. Tiimin innovatiivisuutta, tiimin sekakoosteisuutta, tiimin sisäistä vuorovaikutusta sekä ulkoisia yhteistyösuhteita kartoitettiin useasta näkökulmasta. Tiimin innovatiivisuutta tarkasteltiin sekä ulkopuolisten asiantuntijoiden arvioiden että tiimin jäsenten näkemysten avulla. Tiimin sekakoosteisuus jaoteltiin kahteen luokkaan: sekakoosteisuuteen joka perustuu työhön liittyviin ominaisuuksiin, sekä sekakoosteisuuteen joka perustuu näkyviin ominaisuuksiin. Tiimin sisäistä vuorovaikutusta tarkasteltiin tiimin ilmapiirin ja tiimin sisäisen luottamuksen kautta. Yhteistyötä tiimin ulkopuolisten kanssa käsiteltiin sekä yhteistyösuhteiden määrän että niiden sisällön kannalta. Tutkimuksen otos koostui 20 tietotyötiimistä suomalaisessa telekommunikaatiokonsernissa. Aineisto kerättiin kyselylomakkeilla. Aineisto analysoitiin pääasiassa tilastollisin menetelmin. Vastaukset avoimiin kysymyksiin luokiteltiin kvalitatiivisesti, jolloin tarkoituksena oli varmistaa tutkimuksessa kartoitettavien tekijöiden kattavuus ja ekologinen pätevyys. Tutkimuksen tulokset osoittivat, että sosiaalisilla tekijöillä on merkittävä vaikutus tietotyötiimien innovatiivisuuteen. Koska tutkimus oli ensimmäinen, jossa tutkittiin empiirisesti luottamuksen ja tiimin innovatiivisuuden välistä suhdetta, oli tutkimuksen tärkein yksittäinen tulos, että luottamus on yhteydessä korkeaan tiimin innovatiivisuuden asteeseen. Samoin tiimin ilmapiiri oli yhteydessä korkeaan innovatiivisuuteen. Näkyviin ominaisuuksiin perustuva erilaisuus liittyi matalaan innovatiivisuuteen. Oletuksia vastoin yhteistyö tiimin ulkopuolisten kanssa oli yhteydessä matalaan innovatiivisuuteen, paitsi silloin, kun yhteistyösuhteen sisältö liittyi yleiseen tiedonhankintaan ja ideoiden keräämiseen. Tiimin sisäiset prosessit olivat yhteydessä innovatiivisuuteen merkittävämmin kuin ulkopuoliset suhteet.
  • Pöyhönen, Aino (2001)
    The ability to constantly produce innovations has become the major driver of corporate success and economic growth. Within the workforce, knowledge workers are in the key position to create renewals that produce competitive advantage. This research examined antecedents of innovation in knowledge worker teams. The aim was to find out how knowledge worker team innovation is related with team diversity, within-team interaction and collaboration with external parties. As the subject of knowledge worker team innovation has received relatively little attention in the earlier literature, a theoretical framework was constructed with the intention of covering extensively the group-level factors influential to the phenomenon. Team innovation, team diversity, within-team interaction and external collaboration were all studied from several viewpoints. The level of team innovation was assessed by both external experts and the team members themselves. Two types of team diversity were addressed: diversity based on highly job-related attributes and diversity based on highly visible attributes. Within-team interaction was approached via team climate and interpersonal trust. External collaboration was examined by studying the amount of external collaboration and the content of external relationships. The sample of the research consisted of 20 knowledge worker teams representing different functions of a large Finnish telecommunications corporation. Data was gathered with questionnaires. Analysis was conducted mainly with statistical methods, although qualitative classification was also conducted for responses to open-ended questions in order to assure the ecological validity and exhaustiveness of the theoretical framework. Overall, the results demonstrated that social factors are highly influential for knowledge worker team innovation. As this research was the first one to empirically examine the significance of trust to team innovation, the most important single result was that interpersonal trust was related with high levels of team innovation. Also team climate was connected with high team innovation. Team diversity based on highly visible attributes was negatively related with team innovation. Surprisingly, also external collaboration had negative associations with team innovation, except for when it was aimed at general scanning for ideas and information. In addition, internal team processes were found to be more significant for team innovation than external processes.
  • Kumar, Ajay Anand (2012)
    Due to next generation of sequencing technologies the amount of public sequence data is exponentially growing, however the rate of sequence annotation is lagging behind. There is need for development of robust computational tools for correct assignment of annotation to protein sequences. Sequence homology based inference of molecular function assignment and subsequent transfer of the annotation is the traditional way of annotating genome sequences. TF-IDF based methodology of mining informative description of high quality annotated sequences can be used to cluster functionally similar and dissimilar protein sequences. The aim of this thesis work is to perform the correlation analysis of TF-IDF methodology with standard methods of Gene Ontology (GO) semantic similarity measures. We have developed and implemented a high-throughput tool named GOParGenPy for effective and faster analysis related to Gene Ontology. It incorporates any Gene Ontology linked annotation file and generates corresponding data matrices, which provides a useful interface for any downstream analysis associated with Gene Ontology across various mathematical platforms. Finally, the correlation evaluation between TF-IDF and standard Gene Ontology semantic similarity methods validates the effectiveness of TF-IDF methodology in order to cluster functionally similar protein sequences.
  • Lovio, Riikka (Helsingin yliopisto, 2013)
    Dyslexia is a highly heritable neurobiological disorder defined as a persistent difficulty in learning to read. Phonological processing skills, associating letters to sounds, and word retrieval are deficient in many children with dyslexia. Poor reading accuracy and slow reading speed are, in turn, characteristic for adults with dyslexia. Intact processing of even minor differences in speech sounds is essential for language development and reading skills. Speech perception requires sound discrimination and phoneme identification, despite the variation in their acoustical features. Accurate phonological representations are also important for learning the connection between sounds and letters. Difficulties in auditory processing are common in individuals with dyslexia. Cortical auditory processing can be investigated by recording the electroencephalography (EEG). The detection of changes in the regularities of the auditory input gives rise to neural activity in the brain that is seen as a mismatch negativity (MMN) response of the event-related potential (ERP) recorded by EEG. As the recording of MMN requires neither a subject s behavioural response nor attention towards the sounds, it is suitable for studies of even young children. Despite its advantages over behavioural measures, a major obstacle to the use of the MMN method has been the relatively long duration of its recording. However, the multi-feature MMN paradigm with several types of sound changes was recently developed in order to obtain a comprehensive profile of auditory sensory memory and discrimination accuracy in a short recording time. The present thesis investigated cortical multi-attribute auditory processing in dyslexia and the efficacy of intervention on reading-related skills and cortical speech sound discrimination. Moreover, the feasibility of the multi-feature paradigm for dyslexia research, and studies in children was tested for the first time. In this thesis, the multi-feature paradigm was found to be well suited for studies investigating central auditory processing in dyslexia and in children. The results showed that cortical auditory processing is aberrant in dyslexia. In children at risk for dyslexia, auditory processing seems to be deficient even at the initial phase of sound encoding. Furthermore, these children also showed a widespread pattern of abnormal cortical auditory discrimination processes. Adults with dyslexia, in turn, have difficulties in discriminating sound frequency and duration features in a complex auditory environment. Early intervention can influence the developmental path of dyslexia, however. The results of this thesis show that even a short intervention with audio-visual letter-sound exercises improves children s reading-related skills and cortical discrimination of vowel contrasts.
  • Brattico, Elvira (Helsingin yliopisto, 2006)
    In a musical context, the pitch of sounds is encoded according to domain-general principles not confined to music or even to audition overall but common to other perceptual and cognitive processes (such as multiple pattern encoding and feature integration), and to domain-specific and culture-specific properties related to a particular musical system only (such as the pitch steps of the Western tonal system). The studies included in this thesis shed light on the processing stages during which pitch encoding occurs on the basis of both domain-general and music-specific properties, and elucidate the putative brain mechanisms underlying pitch-related music perception. Study I showed, in subjects without formal musical education, that the pitch and timbre of multiple sounds are integrated as unified object representations in sensory memory before attentional intervention. Similarly, multiple pattern pitches are simultaneously maintained in non-musicians' sensory memory (Study II). These findings demonstrate the degree of sophistication of pitch processing at the sensory memory stage, requiring neither attention nor any special expertise of the subjects. Furthermore, music- and culture-specific properties, such as the pitch steps of the equal-tempered musical scale, are automatically discriminated in sensory memory even by subjects without formal musical education (Studies III and IV). The cognitive processing of pitch according to culture-specific musical-scale schemata hence occurs as early as at the sensory-memory stage of pitch analysis. Exposure and cortical plasticity seem to be involved in musical pitch encoding. For instance, after only one hour of laboratory training, the neural representations of pitch in the auditory cortex are altered (Study V). However, faulty brain mechanisms for attentive processing of fine-grained pitch steps lead to inborn deficits in music perception and recognition such as those encountered in congenital amusia (Study VI). These findings suggest that predispositions for exact pitch-step discrimination together with long-term exposure to music govern the acquisition of the automatized schematic knowledge of the music of a particular culture that even non-musicians possess.
  • Kujala, Anu (Helsingin yliopisto, 2006)
    Comprehension of a complex acoustic signal - speech - is vital for human communication, with numerous brain processes required to convert the acoustics into an intelligible message. In four studies in the present thesis, cortical correlates for different stages of speech processing in a mature linguistic system of adults were investigated. In two further studies, developmental aspects of cortical specialisation and its plasticity in adults were examined. In the present studies, electroencephalographic (EEG) and magnetoencephalographic (MEG) recordings of the mismatch negativity (MMN) response elicited by changes in repetitive unattended auditory events and the phonological mismatch negativity (PMN) response elicited by unexpected speech sounds in attended speech inputs served as the main indicators of cortical processes. Changes in speech sounds elicited the MMNm, the magnetic equivalent of the electric MMN, that differed in generator loci and strength from those elicited by comparable changes in non-speech sounds, suggesting intra- and interhemispheric specialisation in the processing of speech and non-speech sounds at an early automatic processing level. This neuronal specialisation for the mother tongue was also reflected in the more efficient formation of stimulus representations in auditory sensory memory for typical native-language speech sounds compared with those formed for unfamiliar, non-prototype speech sounds and simple tones. Further, adding a speech or non-speech sound context to syllable changes was found to modulate the MMNm strength differently in the left and right hemispheres. Following the acoustic-phonetic processing of speech input, phonological effort related to the selection of possible lexical (word) candidates was linked with distinct left-hemisphere neuronal populations. In summary, the results suggest functional specialisation in the neuronal substrates underlying different levels of speech processing. Subsequently, plasticity of the brain's mature linguistic system was investigated in adults, in whom representations for an aurally-mediated communication system, Morse code, were found to develop within the same hemisphere where representations for the native-language speech sounds were already located. Finally, recording and localization of the MMNm response to changes in speech sounds was successfully accomplished in newborn infants, encouraging future MEG investigations on, for example, the state of neuronal specialisation at birth.
  • Lepistö, Tuulia (Helsingin yliopisto, 2008)
    Autism and Asperger syndrome (AS) are neurodevelopmental disorders characterised by deficient social and communication skills, as well as restricted, repetitive patterns of behaviour. The language development in individuals with autism is significantly delayed and deficient, whereas in individuals with AS, the structural aspects of language develop quite normally. Both groups, however, have semantic-pragmatic language deficits. The present thesis investigated auditory processing in individuals with autism and AS. In particular, the discrimination of and orienting to speech and non-speech sounds was studied, as well as the abstraction of invariant sound features from speech-sound input. Altogether five studies were conducted with auditory event-related brain potentials (ERP); two studies also included a behavioural sound-identification task. In three studies, the subjects were children with autism, in one study children with AS, and in one study adults with AS. In children with autism, even the early stages of sound encoding were deficient. In addition, these children had altered sound-discrimination processes characterised by enhanced spectral but deficient temporal discrimination. The enhanced pitch discrimination may partly explain the auditory hypersensitivity common in autism, and it may compromise the filtering of relevant auditory information from irrelevant information. Indeed, it was found that when sound discrimination required abstracting invariant features from varying input, children with autism maintained their superiority in pitch processing, but lost it in vowel processing. Finally, involuntary orienting to sound changes was deficient in children with autism in particular with respect to speech sounds. This finding is in agreement with previous studies on autism suggesting deficits in orienting to socially relevant stimuli. In contrast to children with autism, the early stages of sound encoding were fairly unimpaired in children with AS. However, sound discrimination and orienting were rather similarly altered in these children as in those with autism, suggesting correspondences in the auditory phenotype in these two disorders which belong to the same continuum. Unlike children with AS, adults with AS showed enhanced processing of duration changes, suggesting developmental changes in auditory processing in this disorder.
  • Ylinen, Sari (Helsingin yliopisto, 2006)
    Different languages use temporal speech cues in different linguistic functions. In Finnish, speech-sound duration is used as the primary cue for the phonological quantity distinction ― i.e., a distinction between short and long phonemes. For the second-language (L2) learners of Finnish, quantity is often difficult to master if speech-sound duration plays a less important role in the phonology of their native language (L1). The present studies aimed to investigate the cortical representations for phonological quantity in native speakers and L2 users of Finnish by using behavioral and electrophysiological methods. Since long-term memory representations for different speech units have been previously shown to participate in the elicitation of the mismatch negativity (MMN) brain response, MMN was used to compare the neural representation for quantity between native speakers and L2 users of Finnish. The results of the studies suggested that native Finnish speakers' MMN response to quantity was determined by the activation of native-language phonetic prototypes rather than by phoneme boundaries. In addition, native speakers seemed to process phoneme quantity and quality independently from each other by separate brain representations. The cross-linguistic MMN studies revealed that, in native speakers of Finnish, the MMN response to duration or quantity-degree changes was enhanced in amplitude selectively in speech sounds, whereas this pattern was not observed in L2 users. Native speakers' MMN enhancement is suggested to be due to the pre-attentive activation of L1 prototypes for quantity. In L2 users, the activation of L2 prototypes or other L2 learning effects were not reflected in the MMN, with one exception. Even though L2 users failed to show native-like brain responses to duration changes in a vowel that was similar in L1 and L2, their duration MMN response was native-like for an L2 vowel with no counterpart in L1. Thus, the pre-attentive activation of L2 users' representations was determined by the degree of similarity of L2 sounds to L1 sounds. In addition, behavioral experiments suggested that the establishment of representations for L2 quantity may require several years of language exposure.
  • Sirola, Roosa (2013)
    Visual working memory (VWM) maintains information for future usage. Several studies show that the cortical oscillations in the γ-frequency band (from 30 to 120 Hz) are modulated by the VWM performance. However, less is known about the cortical sources underlying the modulation of these oscillations in VWM. To address this question, we recorded human neuronal activity with magneto- and electroencephalography (M/EEG) during a delayed-matching-to-sample VWM task with three different task conditions, within which participants were instructed to focus on different object features in turn. In addition, anatomical data was acquired with magnetic resonance imaging for source modeling purposes. We then estimated the cortical amplitude dynamics across frequencies from three to 90 Hz during the VWM retention period for these three different conditions. We found that the amplitudes of the γ –frequency band oscillations were strengthened in the occipito-temporal cortical areas during the VWM for shapes but not for color or spatial locations. These data suggest that γ –band oscillations are fundamental in VWM, especially for visual stimuli requiring perceptual feature binding. Furthermore, cortical γ –band oscillations were found to be load dependently strengthened in the frontal cortex, where the central executive and attention associated processes are believed to take place. These data support the previous hypotheses stating that γ –band oscillations contribute to the maintenance of object representations in VWM.
  • Niskanen, Tuula (Helsingin yliopisto, 2008)
    Cortinarius is the largest genus of Agaricales with a worldwide distribution. So far, over 4000 Cortinarius names and combinations have been published. Cortinarius spp. form ectomycorrhizae with different trees and shrubs. A majority of the Cortinarius species have narrow ecological preferences and many form ectomycorrhiza with only one or few host species. The subgenus Telamonia sensu lato (s. lat.), comprising the greatest number of species, is the most poorly known of the subgenera of Cortinarius. The centre of diversity is in the northern hemisphere, although some species of the group are also recognized in the southern hemisphere. The aim of this thesis was to study the taxonomy of Cortinarius subgenus Telamonia p.p. species based on morphological and molecular data, as well as to study the ecology and distribution of the species in North Europe. The taxonomical problems encountered and the difficulty in finding and studying all the relevant names and types slowed down the study. The diversity of the subgenus Telamonia s. lat. in North Europe (excluding sect. Hydrocybe, Icrustati and Anomali) was found to be far greater than previously thought. Even many of the common species have not yet been described. So far, ca. 200 species have been recognised from the Nordic countries, but the sampling in most groups does not cover the whole diversity and especially the southern deciduous forest species are underrepresented in our study. In most cases phylogenetic (only based on ITS data) and morphological species recognition were in concordance, but in a few cases morphologically delimited species had almost identical ITS sequences, raising the question as to whether ITS is always variable enough for species recognition. The opposite situation, in which a morphologically uniform species included two phylogenetically distinct lineages, however, was also encountered, suggesting the possibility of cryptic species in Cortinarius. In our studies no taxa below species level were recognised and the aforementioned results indicate that presumably they can only be recognised genetically. Based on our preliminary results a revision of the infrageneric classification in Cortinarius subgenus Telamonia s. lat. is needed, and more sections should be established for a meaningful and functional classification. Many groups have turned out to be artificial, and it seems evident that many characteristics have been over- or underemphasised. Many morphological characteristics, however, are useful in the identification of telamonioid species and e.g. some spore characteristics have often been overlooked. Our studies have concentrated on North Europe, but we have found some similarities with North European and North American taxa.
  • Säntti, Auvo A. (1933)
  • Paveliev, Mikhail (2008)
    Neurotrophic factors (NTFs) and the extracellular matrix (ECM) are important regulators of axonal growth and neuronal survival in mammalian nervous system. Understanding of the mechanisms of this regulation is crucial for the development of posttraumatic therapies and drug intervention in the injured nervous system. NTFs act as soluble, target-derived extracellular regulatory molecules for a wide range of physiological functions including axonal guidance and the regulation of programmed cell death in the nervous system. The ECM determines cell adhesion and regulates multiple physiological functions via short range cell-matrix interactions. The present work focuses on the mechanisms of the action of NTFs and the ECM on axonal growth and survival of cultured sensory neurons from dorsal root ganglia (DRG). We first examined signaling mechanisms of the action of the glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) on axonal growth. GDNF, neurturin (NRTN) and artemin (ART) but not persephin (PSPN) promoted axonal initiation in cultured DRG neurons from young adult mice. This effect required Src family kinase (SFK) activity. In neurons from GFRalpha2-deficient mice, NRTN did not significantly promote axonal initiation. GDNF and NRTN induced extensive lamellipodia formation on neuronal somata and growth cones. This study suggested that GDNF, NRTN and ARTN may serve as stimulators of nerve regeneration under posttraumatic conditions. Consequently we studied the convergence of signaling pathways induced by NTFs and the ECM molecule laminin in the intracellular signaling network that regulates axonal growth. We demonstrated that co-stimulation of DRG neurons with NTFs (GDNF, NRTN or nerve growth factor (NGF)) and laminin leads to axonal growth that requires activation of SFKs. A different, SFK-independent signaling pathway evoked axonal growth on laminin in the absence of the NTFs. In contrast, axonal branching was regulated by SFKs both in the presence and in the absence of NGF. We proposed and experimentally verified a Boolean model of the signaling network triggered by NTFs and laminin. Our results put forward an approach for predictable, Boolean logics-driven pharmacological manipulation of a complex signaling network. Finally we found that N-syndecan, the receptor for the ECM component HB-GAM was required for the survival of neonatal sensory neurons in vitro. We demonstrated massive cell death of cultured DRG neurons from mice deficient in the N-syndecan gene as compared to wild type controls. Importantly, this cell death could not be prevented by NGF the neurotrophin which activates multiple anti-apoptotic cascades in DRG neurons. The survival deficit was observed during first postnatal week. By contrast, DRG neurons from young adult N-syndecan knock-out mice exhibited normal survival. This study identifies a completely new syndecan-dependent type of signaling that regulates cell death in neurons.
  • Keisalo-Galván, Marianna (Helsingin yliopisto, 2011)
    Cosmic Clowns: Convention, Invention, and Inversion in the Yaqui Easter Ritual is an ethnographic study of masked clown figures called Chapayekas. They represent Judas and the Roman soldiers in the Passion play that forms the narrative core of the Easter ritual of the Yaquis, an indigenous group in Sonora, Mexico. The study looks at how the Chapayeka is created as a ritual figure, how their performance is constructed, and what the part of the clown is in the dynamics of the ritual. The material was gathered over three periods of anthropological fieldwork in Cócorit, Sonora during Easter in 2004, 2006 and 2007. The Chapayeka masks portray foreigners, animals, mythological figures, and even figures from television and movies. They combine two kinds of performance: they perform set, conventional actions, and improvise and invent new ones. This creates dialectics of invention and convention that allow the figure to mediate between the ritual and its context and different kinds of beings within the Yaqui cosmology. The conventional side of their performance is a cycle of death and rebirth that is an inversion of the cycle of Jesus. Through invention, they separate themselves from the other performers and make themselves powerful. Alternation between the two modes enhances that power and brings it into the conventions of the ritual; ultimately the Chapayekas revitalize the entire ritual. The study finds that the clowns are extremely important to the continuity of both ritual and culture, as the combination of continuity and change, convention and invention, is what makes it possible to recreate the conventions of Yaqui culture as powerful and compelling in various contexts. Another factor is the prevalence of dialectical mediation, which relates concepts by defining them against each other as opposites, and makes it possible to cross a boundary while keeping it intact. Clowns embody and create dialectics to mediate boundaries while guarding against relativization, the disappearance of distinctions. The Chapayekas create and constitute boundaries between the self and other, microcosm and macrocosm, sacred and profane. The study argues that all clown and trickster figures are characterized by constantly alternating between invention and convention; this is what connects them to the collective and moral aspect of culture and, at the same time, makes them unpredictable and powerful. It is possible to do justice to the opposed aspects of these ambiguous and paradoxical figures by taking into account the different foundations and contextual effects of the different modes of symbolization.
  • Sandhu, Jaspreet (2013)
    This thesis aims to cover the central aspects of the current research and advancements in cosmic topology from a topological and observational perspective. Beginning with an overview of the basic concepts of cosmology, it is observed that though a determinant of local curvature, Einstein’s equations of relativity do not constrain the global properties of space-time. The topological requirements of a universal space time manifold are discussed, including requirements of space-time orientability and causality. The basic topological concepts used in classification of spaces, i.e. the concept of the Fundamental Domain and Universal covering spaces are discussed briefly. The manifold properties and symmetry groups for three dimensional manifolds of constant curvature for negative, positive and zero curvature manifolds are laid out. Multi-connectedness is explored as a possible explanation for the detected anomalies in the quadrupole and octopole regions of the power spectrum, pointing at a possible compactness along one or more directions in space. The statistical significance of the evidence, however, is also scrutinized and I discuss briefly the bayesian and frequentist interpretation of the posterior probabilities of observing the anomalies in a ΛCDM universe. Some of the major topologies that have been proposed and investigated as possible candidates of a universal manifold are the Poincare Dodecahedron and Bianchi Universes, which are studied in detail. Lastly, the methods that have been proposed for detecting a multi-connected signature are discussed. These include ingenious observational methods like the circles in the sky method, cosmic crystallography and theoretical methods which have the additional advantage of being free from measurement errors and use the posterior likelihoods of models. As of the recent Planck mission, no pressing evidence of a multi connected topology has been detected.