52 resultados para seemingly unrelated regressions
em Helda - Digital Repository of University of Helsinki
Resumo:
This thesis report attempts to improve the models for predicting forest stand structure for practical use, e.g. forest management planning (FMP) purposes in Finland. Comparisons were made between Weibull and Johnson s SB distribution and alternative regression estimation methods. Data used for preliminary studies was local but the final models were based on representative data. Models were validated mainly in terms of bias and RMSE in the main stand characteristics (e.g. volume) using independent data. The bivariate SBB distribution model was used to mimic realistic variations in tree dimensions by including within-diameter-class height variation. Using the traditional method, diameter distribution with the expected height resulted in reduced height variation, whereas the alternative bivariate method utilized the error-term of the height model. The lack of models for FMP was covered to some extent by the models for peatland and juvenile stands. The validation of these models showed that the more sophisticated regression estimation methods provided slightly improved accuracy. A flexible prediction and application for stand structure consisted of seemingly unrelated regression models for eight stand characteristics, the parameters of three optional distributions and Näslund s height curve. The cross-model covariance structure was used for linear prediction application, in which the expected values of the models were calibrated with the known stand characteristics. This provided a framework to validate the optional distributions and the optional set of stand characteristics. Height distribution is recommended for the earliest state of stands because of its continuous feature. From the mean height of about 4 m, Weibull dbh-frequency distribution is recommended in young stands if the input variables consist of arithmetic stand characteristics. In advanced stands, basal area-dbh distribution models are recommended. Näslund s height curve proved useful. Some efficient transformations of stand characteristics are introduced, e.g. the shape index, which combined the basal area, the stem number and the median diameter. Shape index enabled SB model for peatland stands to detect large variation in stand densities. This model also demonstrated reasonable behaviour for stands in mineral soils.
Resumo:
Tutkimuksessa analysoidaan kaaosteorian vaikutusta kaunokirjallisuudessa ja kirjallisuudentutkimuksessa ja esitetään, että kaaosteorian roolia kirjallisuuden kentällä voidaan parhaiten ymmärtää sen avaamien käsitteiden kautta. Suoran soveltamisen sijaan kaaosteorian avulla on käyty uudenlaisia keskusteluja vanhoista aiheista ja luonnontieteestä ammennetut käsitteet ovat johtaneet aiemmin tukkeutuneiden argumenttien avaamiseen uudesta näkökulmasta käsin. Väitöskirjassa keskitytään kolmeen osa-alueeseen: kaunokirjallisen teoksen rakenteen teoretisointiin, ihmisen (erityisesti tekijän) identiteetin hahmottamiseen ja kuvailemiseen sekä fiktion ja todellisuuden suhteen pohdintaan. Tutkimuksen tarkoituksena on osoittaa, kuinka kaaosteorian kautta näitä aiheita on lähestytty niin kirjallisuustieteessä kuin kaunokirjallisissa teoksissakin. Väitöskirjan keskiössä ovat romaanikirjailija John Barthin, dramatisti Tom Stoppardin ja runoilija Jorie Grahamin teosten analyysit. Nämä kirjailijat ammentavat kaaosteoriasta keinoja käsitteellistää rakenteita, jotka ovat yhtä aikaa dynaamisia prosesseja ja hahmotettavia muotoja. Kaunokirjallisina teemoina nousevat esiin myös ihmisen paradoksaalisesti tunnistettava ja aina muuttuva identiteetti sekä lopullista haltuunottoa pakeneva, mutta silti kiehtova ja tavoiteltava todellisuus. Näiden kirjailijoiden teosten analyysin sekä teoreettisen keskustelun kautta väitöskirjassa tuodaan esiin aiemmassa tutkimuksessa varjoon jäänyt, koherenssia, ymmärrettävyyttä ja realismia painottava humanistinen näkökulma kaaosteorian merkityksestä kirjallisuudessa.
Resumo:
A Revival in a Village and its Households. The Village of Oravisalo in Rääkkylä Parish and the Renqvistist Revivalism in the 1820s. My purpose is to apply the science of religion and the study of past communities to the study of religious revivalism. Revivalism will be considered a religious phenomenon as well as a cultural and social phenomenon. What makes this study unique is the possibility to reconstruct a list of participating revivalists based on entries in the communion book of the time. The conflict between the revivalists and the chaplain of Rääkkylä also generated other documentary material. The community in Oravisalo was relatively stratified. People lived in complex and varying forms of households. They also had plentiful contacts both with unrelated inhabitants of Oravisalo and with the neighbouring villages. Through these contacts the inhabitants of Oravisalo were introduced to revivalism. In Oravisalo, the revival for the most part fell into a certain social stratum and did not severely damage existing relationships within families or among acquaintances. The revivalists formed a new community within the village but the community was neither very tightly-knit nor was it closed. The revival was an individual phenomenon affected by general factors. First, there were factors that brought about a quest for an applicable system of meanings. These factors included at least three important issues: the Great Partition of land, the crisis of slash-and-burn cultivation, and a population growth that increased the proportion of the landless in the village. As a result, many of the revivalists had low status and poor expectations for the future. Second, there were factors that appealed to the people in the message and character of the preacher, Henrik Renqvist. Third, the proximity of the village to Liperi, where the revival got its start, was crucial to revivalism s spread to Oravisalo. Culturally, the revival meant a change in the system of symbols or meanings, so it was not solely a matter of intensified religious fervour. For instance, Communion, prayer, reading, and perhaps baptism symbolised different things to the revivalists than to other villagers. However, the revivalists do not seem to have started any moral revolution in their village. The religious aspect defined the limits of the protest and the resistance towards authorities. The revivalists wanted only to have the right to follow their conscience. The freedom granted the female members was limited to the religious sphere. No social or economic claims were made. The revival altered the situation of its members only on a symbolic level, yet it also offered them status within their own group.
Resumo:
The series of studies addresses several everyday beliefs about food and health from the perspective of everyday thinking and paranormal beliefs. They are "you are what you eat" beliefs, attitudes towards genetically modified and organic foods, and belief in alternative medicine. The survey studies included from 239 to 3261 Finnish participants. It was found that food consumption can have far-stretching consequences for the impressions of the eater in a "you are what you eat" manner. The results also demonstrated that belief in alternative medicine was related to belief in the paranormal, as were to a lesser degree attitudes towards genetically modified and organic foods. The study also addressed paranormal beliefs and belief in alternative medicine from the perspective of category observance. Paranormal believers as well as believers in alternative medicine were much more liberal than skeptics in violating categorical boundaries and attributed, for example, intentionality (mental) to body growth (biological) and life (biological) to energy (physical). In addition, the study addressed the relation of these attitudes and beliefs with preferred thinking style. The results demonstrated that belief in alternative medicine was especially appealing to intuitive thinkers, while rational thinking was unrelated to it. The same pattern was demonstrated for negative attitudes towards genetically modified food and positive attitudes towards organic food. In addition, it was demonstrated, however, that such unscientific notions may exist not instead of but parallel with "better knowledge". In sum, the present thesis contributes to the understanding of superstitious elements in various everyday attitudes and beliefs, and investigates their relationship with general inclinations towards belief in the paranormal. It appears that some very common everyday beliefs and attitudes about food and health contain elements of a superstitious nature. Involving conceptual enmeshment they go beyond mere associations, and can coincide with scientifically valid views on the same topic.
Resumo:
Semantic processing can be studied with semantic priming. Target words that are preceded by semantically related prime words are recognized faster and more accurately than targets preceded by unrelated prime words. Semantic priming also affects the magnitude of the N400 event-related potential. The response is smaller to a target word when it is preceded by a related than an unrelated prime word. The effect is called the N400 effect. It is not yet clear, however, how attention modulates semantic priming and the N400 effect. This study investigated how the direction of attention affects the semantic processing of speech. The N400 effect was studied in experimental conditions in which the subjects attention was directed 1) away from the speech stimuli, 2) to phonological features of the speech stimuli, and 3) to semantic features of the speech stimuli. The first aim of the study was to investigate whether the N400 effect for spoken words is dependent on attention to the auditory information. The second aim was to study the differences in the N400 effect when attention is directed to the semantic or other features of speech stimuli. The results showed an N400 effect even when attention was directed away from the speech stimuli. The N400 effect was, however, stronger in conditions during which the speech stimuli were attended. The magnitude of the behavioral semantic priming and the N400 effect did not differ between the conditions during which attention was directed to the semantic or phonological features of the words. The findings indicate that the semantic processing of spoken words is not dependent on attention to auditory information. Furthermore, the results suggest that whether or not semantic processing is relevant for the task performance does not affect the semantic processing of attended spoken words.
Resumo:
This study explored the possibilities the psychophysiological methodology offer to flow research. Facial electromyography has often been used to index valence, and electrodermal activity to index arousal, the two basic dimensions of emotion. It was hypothesized that these measures can also be used to examine enjoyment, a basic component of flow experiment. A digital game was used to induce flow, and physiological activity of 32 subjects was measured continuously. Flow State Scale was used to assess flow. Activity of corrugator supercilii muscle, an index of negative valence, was negatively correlated with flow reports, as hypothesized. Contrary to hypothesis, skin conductance level, an index of arousal, was unrelated to self-reported flow. The results for association between flow and zygomaticus major and orbicularis oculi muscle activities, indices of positive valence, were inconclusive, possibly due to experimental design where only tonic measures were available. Psychophysiological methods are recommended for future studies of flow. Specifically, the time series approach may be particularly viable in examining the temporal aspects of flow, an area currently unexplored. Furthermore, it is suggested that digital game research would benefit from psychophysiological study of game-related flow.
Resumo:
The purpose of the present study was to investigate the possibilities and interconnec-tions that exist concerning the relationship between the University of Applied Sci-ences and the Learning by Developing action model (LbD), on the one hand, and education for sustainable development and high-quality learning as a part of profes-sional competence development on the other. The research and learning environment was the Coping at Home research project and its Caring TV project, which provided the context of the Physiotherapy for Elderly People professional study unit. The re-searcher was a teacher and an evaluator of her own students learning. The aims of the study were to monitor and evaluate learning at the individual and group level using tools of high-quality learning − improved concept maps − related to understanding the projects core concept of successful ageing. Conceptions were evaluated through aspects of sustainable development and a conceptual basis of physiotherapy. As edu-cational research this was a multi-method case study design experiment. The three research questions were as follows. 1. What kind of individual conceptions and conceptual structures do students build concerning the concept of successful ageing? How many and what kind of concepts and propositions do they have a) before the study unit, b) after the study unit, c) after the social-knowledge building? 2. What kind of social-knowledge building exists? a) What kind of social learn-ing process exists? b) What kind of socially created concepts, propositions and conceptual structures do the students possess after the project? c) What kind of meaning does the social-knowledge building have at an individual level? 3. How do physiotherapy competences develop according to the results of the first and second research questions? The subjects were 22 female, third-year Bachelor of Physiotherapy students in Laurea University of Applied Sciences in Finland. Individual learning was evaluated in 12 of the 22 students. The data was collected as a part of the learning exercises of the Physiotherapy for Elderly People study unit, with improved concept maps both at individual and group levels. The students were divided into two social-knowledge building groups: the first group had 15 members and second 7 members. Each group created a group-level concept map on the theme of successful ageing. These face-to-face interactions were recorded with CMapTools and videotaped. The data consists of both individually produced concept maps and group-produced concept maps of the two groups and the videotaped material of these processes. The data analysis was carried out at the intersection of various research traditions. Individually produced data was analysed based on content analysis. Group-produced data was analysed based on content analysis and dialogue analysis. The data was also analysed by simple statistical analysis. In the individually produced improved concept maps the students conceptions were comprehensive, and the first concept maps were found to have many concepts unrelated to each other. The conceptual structures were between spoke structures and chain structures. Only a few professional concepts were evident. In the second indi-vidual improved concept maps the conception was more professional than earlier, particulary from the functional point of view. The conceptual structures mostly re-sembled spoke structures. After the second individual concept mapping social map-ping interventions were made in the two groups. After this, multidisciplinary concrete links were established between all concepts in almost all individual concept maps, and the interconnectedness of the concepts in different subject areas was thus understood. The conceptual structures were mainly net structures. The concepts in these individual concept maps were also found to be more professional and concrete than in the previ-ous concept maps of these subjects. In addition, the wider context dependency of the concepts was recognized in many individual concept maps. This implies a conceptual framework for specialists. The social-knowledge building was similar to a social learning process. Both socio-cultural processes and cognitive processes were found to develop students conceptual awareness and the ability to engage in intentional learning. In the knowl-edge-building process two aspects were found: knowledge creation and pedagogical action. The discussion during the concept-mapping process was similar to a shared thinking process. In visualising the process with CMapTools, students easily comple-mented each others thoughts and words, as if mutually telepathic . Synthesizing, supporting, asking and answering, peer teaching and counselling, tutoring, evaluating and arguing took place, and students were very active, self-directed and creative. It took hundreds of conversations before a common understanding could be found. The use of concept mapping in particular was very effective. The concepts in these group-produced concept maps were found to be professional, and values of sustainable development were observed. The results show the importance of developing the contents and objectives of the European Qualification Framework as well as education for sustainable development, especially in terms of the need for knowledge creation, global responsibility and systemic, holistic and critical thinking in order to develop clinical practice. Keywords: education for sustainable development, learning, knowledge building, improved concept map, conceptual structure, competence, successful ageing
Resumo:
In line with major demographic changes in other Northern European and North American countries and Australia, being nonmarried is becoming increasingly common in Finland, and the proportion of cohabiters and of persons living alone has grown in recent decades. Official marital status no longer reflects an individual s living arrangement, as single, divorced and widowed persons may live alone, with a partner, with children, with parents, with siblings, or with unrelated persons. Thus, more than official marital status, living arrangements may be a stronger discriminator of one s social bonds and health. The general purpose of this study was to deepen our current understanding of the magnitude, trends, and determinants of ill health by living arrangements in the Finnish working-age population. Distinct measures of different dimensions of poor health, as well as an array of associated factors, provided a comprehensive picture of health differences by living arrangements and helped to assess the role of other factors in the interpretation of these differences . Mortality analyses were based on Finnish census records at the end of 1995 linked with cause-of-death registers for 1996 2000. The data included all persons aged 30 and over. Morbidity analyses were based on two comparable cross-sectional studies conducted twenty years apart (the Mini-Finland Survey in 1978 80 and the Health 2000 Survey in 2000 01). Both surveys were based on nationally representative samples of Finns aged 30 and over, and benefited from high participation rates. With the exception of mortality analyses, this study focused on health differences among the working-age population (mortality in age groups 30-64 and 65 and over, self-rated health and mental health in the age group 30-64, and unhealthy alcohol use in the age group 30-54). Compared with all nonmarried groups, married men and women exhibited the best health in terms of mortality, self-rated health, mental health and unhealthy alcohol use. Cohabiters did not differ from married persons in terms of self-rated health or mental health, but did exhibit excess unhealthy alcohol use and high mortality, particularly from alcohol-related causes. Compared with the married, persons living alone or with someone other than a partner exhibited elevated mortality as well as excess poor mental health and unhealthy alcohol use. By all measures of health, men and women living alone tended to be in the worst position. Over the past twenty years, SRH had improved least among single men and women and widowed women, and most among cohabiting women. The association between living arrangements and health has many possible explanations. The health-related selection theory suggests that healthy people are more likely to enter and maintain a marriage or a consensual union than those who are unhealthy (direct selection) or that a variety of health-damaging behavioural and social factors increase the likelihood of ill health and the probability of remaining without a partner or becoming separated from one s partner (indirect selection). According to the social causation theory, marriage or cohabitation has a health-promoting effect, whereas living alone or with others than a partner has a detrimental effect on health. In this study, the role of other factors that are mainly assumed to reflect selection, appeared to be rather modest. Social support, which reflects social causation, contributed only modestly to differences in unhealthy alcohol use by living arrangements, but had a larger effect on differences in poor mental health. Socioeconomic factors and health-related behaviour, which reflect both selection and causation, appeared to play a more important role in the excess poor health of cohabiters and of persons living alone or with someone other than a partner, than of married persons. Living arrangements were strongly connected to various dimensions of ill health. In particular, alcohol consumption appeared to be of great importance in the association between living arrangements and health. To the extent that the proportion of nonmarried persons continues to grow and their health does not improve at the same rate as that of married persons, the challenges that currently nonmarried persons pose to public health will likely increase.
Resumo:
Objective and background. Tobacco smoking, pancreatitis and diabetes mellitus are the only known causes of pancreatic cancer, leaving ample room for yet unidentified determinants. This is an empirical study on a Finnish data on occupational exposures and pancreatic cancer risk, and a non-Bayesian and a hierarchical Bayesian meta-analysis of data on occupational factors and pancreatic cancer. Methods. The case-control study analyzed 595 incident cases of pancreatic cancer and 1,622 controls of stomach, colon, and rectum cancer, diagnosed 1984-1987 and known to be dead by 1990 in Finland. The next-of-kin responded to a mail questionnaire on job and medical histories and lifestyles. Meta-analysis of occupational risk factors of pancreatic cancer started off with 1,903 identified studies. The analyses were based on different subsets of that database. Five epidemiologists examined the reports and extracted the pertinent data using a standardized extraction form that covered 20 study descriptors and the relevant relative risk estimates. Random effects meta-analyses were applied for 23 chemical agents. In addition, hierarchical Bayesian models for meta-analysis were applied to the occupational data of 27 job titles using job exposure matrix as a link matrix and estimating the relative risks of pancreatic cancer associated with nine occupational agents. Results. In the case-control study, logistic regressions revealed excess risks of pancreatic cancer associated with occupational exposures to ionizing radiation, nonchlorinated solvents, and pesticides. Chlorinated hydrocarbon solvents and related compounds, used mainly in metal degreasing and dry cleaning, are emerging as likely risk factors of pancreatic cancer in the non-Bayesian and the hierarchical Bayesian meta-analysis. Consistent excess risk was found for insecticides, and a high excess for nickel and nickel compounds in the random effects meta-analysis but not in the hierarchical Bayesian meta-analysis. Conclusions. In this study occupational exposure to chlorinated hydrocarbon solvents and related compounds and insecticides increase risk of pancreatic cancer. Hierarchical Bayesian meta-analysis is applicable when studies addressing the agent(s) under study are lacking or very few, but several studies address job titles with potential exposure to these agents. A job-exposure matrix or a formal expert assessment system is necessary in this situation.
Resumo:
The neuronal ceroid lipofuscinoses (NCLs) are a group of mostly autosomal recessively inherited neurodegenerative disorders. The aim of this thesis was to characterize the molecular genetic bases of these, previously genetically undetermined, NCL forms. Congenital NCL is the most aggressive form of NCLs. Previously, a mutation in the cathepsin D (CTSD) gene was shown to cause congenital NCL in sheep. Based on the close resemblance of the phenotypes between congenital NCLs in sheep and human, CTSD was considered as a potential candidate gene in humans as well. When screened for mutations by sequencing, a homozygous nucleotide duplication creating a premature stop codon was identified in CTSD in one family with congenital NCL. While in vitro the overexpressed truncated mutant protein was stable although inactive, the absence of CTSD staining in brain tissue samples of patients indicated degradation of the mutant CTSD in vivo. A lack of CTSD staining was detected also in another, unrelated family with congenital NCL. These results imply that CTSD deficiency underlies congenital NCL. While initially Turkish vLINCL was considered a distinct genetic entity (CLN7), mutations in the CLN8 gene were later reported to account for the disease in a subset of Turkish patients with vLINCL. To further dissect the genetic basis of the disease, all known NCL genes were screened for homozygosity by haplotype analysis of microsatellite markers and/or sequenced in 13 mainly consanguineous, Turkish vLINCL families. Two novel, family-specific homozygous mutations were identified in the CLN6 gene. In the remaining families, all known NCL loci were excluded. To identify novel gene(s) underlying vLINCL, a genomewide single nucleotide polymorphism scan, homozygosity mapping, and positional candidate gene sequencing were performed in ten of these families. On chromosome 4q28.1-q28.2, a novel major facilitator superfamily domain containing 8 (MFSD8) gene with six family-specific homozygous mutations in vLINCL patients was identified. MFSD8 transcript was shown to be ubiquitously expressed with a complex pattern of alternative splicing. Our results suggest that MFSD8 is a novel lysosomal integral membrane protein which, as a member of the major facilitator superfamily, is predicted to function as a transporter. Identification of MFSD8 emphasizes the genetic heterogeneity of Turkish vLINCL. In families where no MFSD8 mutations were detected, additional NCL-causing genes remain to be identified. The identification of CTSD and MFSD8 increases the number of known human NCL-causing genes to eight, and is an important step towards the complete understanding of the genetic spectrum underlying NCLs. In addition, it is a starting point for dissecting the molecular mechanisms behind the associated NCLs and contributes to the challenging task of understanding the molecular pathology underlying the group of NCL disorders.
Resumo:
Primary pulmonary hypertension (PPH), or according to the recent classification idiopathic pulmonary hypertension (IPAH), is a rare, progressive disease of pulmonary vasculature leading to pulmonary hypertension and right heart failure. Most of the patients are sporadic but in about 6% of cases the disease is familial (FPPH). In 2000 two different groups identified the gene predisposing to PPH. This gene, Bone morphogenetic protein receptor type 2 (BMPR2), encodes a subunit of transforming growth factor β (TGF-β) receptor complex. There is a genetic connection between PPH and hereditary hemorrhagic telangiectasia (HHT), a bleeding disorder characterized by local telangiectasias and sometimes with pulmonary hypertension. In HHT, mutations in ALK1 (activin like kinase type 1) and Endoglin, another members of the TGF-β signaling pathway are found. In this study we identified all of the Finnish PPH patients for the years 1986-1999 using the hospital discharge registries of Finnish university hospitals. During this period we found a total of 59 confirmed PPH patients: 55 sporadic and 4 familial representing 3 different families. In 1999 the prevalence of PPH was 5.8 per million and the annual incidence varied between 0.2-1.3 per million. Among 28 PPH patients studied, heterozygous BMPR2 mutations were found in 12% (3/26) of sporadic patients and in 33% of the PPH families (1/3). All the mutations found were different. Large deletions of BMPR2 were excluded by single-stranded chain polymomorphism analysis. As a candidate gene approach we also studied ALK1, Endoglin, Bone Morphogenetic Receptor Type IA (BMPR1A or ALK3), Mothers Against Decapentaplegic Homolog 4 (SMAD4) and Serotonine Transporter Gene (SLC6A4) using single-strand conformational polymorphism (SSCP) analysis and direct sequencing. Among patients and family members studied, we found two mutations in ALK1 in two unrelated samples. We also identified all the HHT patients treated at the Department of Otorhinolaryngology at Helsinki University Central Hospital between the years of 1990-2005 and 8 of the patients were studied for Endoglin and ALK1 mutations using direct sequencing. A total of seven mutations were found and all the mutations were different. The absence of a founder mutation in the Finnish population in both PPH and HHT was somewhat surprising. This suggests that the mutations of BMPR2, ALK1 and Endoglin are quite young and the older mutations have been lost due to repetitive genetic bottlenecks and/or negative selection. Also, other genes than BMPR2 may be involved in the pathogenesis of PPH. No founder mutations were found in PPH or HHT and thus no simple genetic test is available for diagnostics.
Defects in tricarboxylic acid cycle enzymes Fumarate hydratase and Succinate dehydrogenase in cancer
Resumo:
Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a recently characterized cancer syndrome which predisposes to cutaneous and uterine leiomyomas as well as renal cell carcinoma (RCC). Uterine leiomyosarcoma (ULMS) has also been observed in certain Finnish HLRCC families. The predisposing gene for this syndrome, fumarate hydratase (FH), was identified in 2002. The well-known function of FH is in the tricarboxylic acid cycle (TCAC) in the energy metabolism of cells. As FH is a novel cancer gene, the role of FH mutations in tumours is in general unknown. Similarly, the mechanisms through which defective FH is associated with tumourigenesis are unclear. The loss of a wild type allele has been observed in virtually all HLRCC patients tumours and the FH enzyme activities are either totally lost or remarkably reduced in the tissues of mutation carrier patients. Therefore, FH is assumed to function as a tumour suppressor. Mutations in genes encoding subunits of other TCAC enzyme SDH have also been reported recently in tumours: mutations in SDHB, SDHC, and SDHD genes predispose to paraganglioma and pheochromocytoma. In the present study, mutations in the SDHB gene were observed to predispose to RCC. This was the first time that mutations in SDHB have been detected in extra-paraganglial tumours. Two different SDHB mutations were observed in two unrelated families. In the first family, the index patient was diagnosed with RCC at the age of 24 years. Additionally, his mother with a paraganglioma (PGL) of the heart and his maternal uncle with lung cancer were both carriers of the mutation. The RCC of the index patient and the PGL of his mother showed LOH. In the other family, an SDHB mutation was detected in two siblings who were both diagnosed with RCC at the ages of 24 and 26 years. Both of the siblings also suffered PGL. All these tumours showed LOH. Therefore, we concluded that mutations in SDHB predispose also for RCC in certain families. Several tumour types were analysed for FH mutations to define the role of FH mutations in these tumour types. In addition, patients with a putative cancer phenotype were analysed to identify new HLRCC families. Three FH variants were detected, of which two were novel. One of the variants was observed in a patient diagnosed with ULMS at the age of 41 years. However, LOH was not detected in the tumour tissue. The FH enzyme activity of the mutated protein was clearly reduced, being 43% of the activity of the normal protein. Together with the results from an earlier study we calculated that the prevalence of FH mutations in Finnish non-syndromic ULMS is around 2.4%. Therefore, FH mutations seem to have a minor role in the pathogenesis on non-syndromic ULMS. Two other germline variants were detected in a novel tumour type, ovarian mucinous cystadenoma. However, tumour tissues of the patients were not available for LOH studies and therefore LOH status remained unclear. Therefore, it is possible that FH mutations predispose also for ovarian tumours but further studies are needed to verify this result. A novel variant form of the FH gene (FHv) was identified and characterized in more detail. FHv contains an alternative first exon (1b), which appeared to function as 5 UTR sequence. The translation of FHv is initiated in vitro from exons two and three. The localization of FHv is both cytosolic and nuclear, in contrast to the localization of FH in mitochondria. FHv is expressed at low levels in all human tissues. Interestingly, the expression was induced after heat shock treatment and in chronic hypoxia. Therefore, FHv might have a role e.g. in the adaptation to unfavourable growth conditions. However, this remains to be elucidated.
Resumo:
The Parechoviruses (HPEV) belong to the family Picornaviridae of positive-stranded RNA viruses. Although the parechovirus genome shares the general properties of other picornaviruses, the genus has several unique features when compared to other family members. We found that HPEV1 attaches to αv integrins on the cell surface and is internalized through the clathrin-mediated endocytic pathway. During he course of the infection, the Golgi was found to disintegrate and the ER membranes to swell and loose their ribosomes. The replication of HPEV1 was found to take place on small clusters of vesicles which contained the trans-Golgi marker GalT as well as the viral non-structural 2C protein. 2C was additionally found on stretches of modified ER-membranes, seemingly not involved in RNA replication. The viral non-structural 2A and 2C proteins were studied in further detail and were found to display several interesting features. The 2A protein was found to be a RNA-binding protein that preferably binds to positive sense 3 UTR RNA. It was found to bind also duplex RNA containing 3 UTR(+)-3 UTR(-), but not other dsRNA molecules studied. Mutagenesis revealed that the N-terminal basic-rich region as well as the C-terminus, are important for RNA-binding. The 2C protein on the other hand, was found to have both ATP-diphosphohydrolase and AMP kinase activities. Neither dATP nor other NTP:s were suitable substrates. Furthermore, we found that as a result of theses activities the protein is autophosphorylated. The intracellular changes brought about by the individual HPEV1 non-structural proteins were studied through the expression of fusion proteins. None of the proteins expressed were able to induce membrane changes similar to those seen during HPEV1 infection. However, the 2C protein, which could be found on the surface of lipid droplets but also on diverse intracellular membranes, was partly relocated to viral replication complexes in transfected, superinfected cells. Although Golgi to ER traffic was arrested in HPEV1-infected cells, none of the individually expressed non-structural proteins had any visible effect on the anterograde membrane traffic. Our results suggest that the HPEV1 replication strategy is different from that of many other picornaviruses. Furthermore, this study shows how relatively small differences in genome sequence result in very different intracellular pathology.
Resumo:
The purpose of this study was to extend understanding of how large firms pursuing sustained and profitable growth manage organisational renewal. A multiple-case study was conducted in 27 North American and European wood-industry companies, of which 11 were chosen for closer study. The study combined the organisational-capabilities approach to strategic management with corporate-entrepreneurship thinking. It charted the further development of an identification and classification system for capabilities comprising three dimensions: (i) the dynamism between firm-specific and industry-significant capabilities, (ii) hierarchies of capabilities and capability portfolios, and (iii) their internal structure. Capability building was analysed in the context of the organisational design, the technological systems and the type of resource-bundling process (creating new vs. entrenching existing capabilities). The thesis describes the current capability portfolios and the organisational changes in the case companies. It also clarifies the mechanisms through which companies can influence the balance between knowledge search and the efficiency of knowledge transfer and integration in their daily business activities, and consequently the diversity of their capability portfolio and the breadth and novelty of their product/service range. The largest wood-industry companies of today must develop a seemingly dual strategic focus: they have to combine leading-edge, innovative solutions with cost-efficient, large-scale production. The use of modern technology in production was no longer a primary source of competitiveness in the case companies, but rather belonged to the portfolio of basic capabilities. Knowledge and information management had become an industry imperative, on a par with cost effectiveness. Yet, during the period of this research, the case companies were better in supporting growth in volume of the existing activity than growth through new economic activities. Customer-driven, incremental innovation was preferred over firm-driven innovation through experimentation. The three main constraints on organisational renewal were the lack of slack resources, the aim for lean, centralised designs, and the inward-bound communication climate.
Resumo:
Buffer zones are vegetated strip-edges of agricultural fields along watercourses. As linear habitats in agricultural ecosystems, buffer strips dominate and play a leading ecological role in many areas. This thesis focuses on the plant species diversity of the buffer zones in a Finnish agricultural landscape. The main objective of the present study is to identify the determinants of floral species diversity in arable buffer zones from local to regional levels. This study was conducted in a watershed area of a farmland landscape of southern Finland. The study area, Lepsämänjoki, is situated in the Nurmijärvi commune 30 km to the north of Helsinki, Finland. The biotope mosaics were mapped in GIS. A total of 59 buffer zones were surveyed, of which 29 buffer strips surveyed were also sampled by plot. Firstly, two diversity components (species richness and evenness) were investigated to determine whether the relationship between the two is equal and predictable. I found no correlation between species richness and evenness. The relationship between richness and evenness is unpredictable in a small-scale human-shaped ecosystem. Ordination and correlation analyses show that richness and evenness may result from different ecological processes, and thus should be considered separately. Species richness correlated negatively with phosphorus content, and species evenness correlated negatively with the ratio of organic carbon to total nitrogen in soil. The lack of a consistent pattern in the relationship between these two components may be due to site-specific variation in resource utilization by plant species. Within-habitat configuration (width, length, and area) were investigated to determine which is more effective for predicting species richness. More species per unit area increment could be obtained from widening the buffer strip than from lengthening it. The width of the strips is an effective determinant of plant species richness. The increase in species diversity with an increase in the width of buffer strips may be due to cross-sectional habitat gradients within the linear patches. This result can serve as a reference for policy makers, and has application value in agricultural management. In the framework of metacommunity theory, I found that both mass effect(connectivity) and species sorting (resource heterogeneity) were likely to explain species composition and diversity on a local and regional scale. The local and regional processes were interactively dominated by the degree to which dispersal perturbs local communities. In the lowly and intermediately connected regions, species sorting was of primary importance to explain species diversity, while the mass effect surpassed species sorting in the highly connected region. Increasing connectivity in communities containing high habitat heterogeneity can lead to the homogenization of local communities, and consequently, to lower regional diversity, while local species richness was unrelated to the habitat connectivity. Of all species found, Anthriscus sylvestris, Phalaris arundinacea, and Phleum pretense significantly responded to connectivity, and showed high abundance in the highly connected region. We suggest that these species may play a role in switching the force from local resources to regional connectivity shaping the community structure. On the landscape context level, the different responses of local species richness and evenness to landscape context were investigated. Seven landscape structural parameters served to indicate landscape context on five scales. On all scales but the smallest scales, the Shannon-Wiener diversity of land covers (H') correlated positively with the local richness. The factor (H') showed the highest correlation coefficients in species richness on the second largest scale. The edge density of arable field was the only predictor that correlated with species evenness on all scales, which showed the highest predictive power on the second smallest scale. The different predictive power of the factors on different scales showed a scaledependent relationship between the landscape context and local plant species diversity, and indicated that different ecological processes determine species richness and evenness. The local richness of species depends on a regional process on large scales, which may relate to the regional species pool, while species evenness depends on a fine- or coarse-grained farming system, which may relate to the patch quality of the habitats of field edges near the buffer strips. My results suggested some guidelines of species diversity conservation in the agricultural ecosystem. To maintain a high level of species diversity in the strips, a high level of phosphorus in strip soil should be avoided. Widening the strips is the most effective mean to improve species richness. Habitat connectivity is not always favorable to species diversity because increasing connectivity in communities containing high habitat heterogeneity can lead to the homogenization of local communities (beta diversity) and, consequently, to lower regional diversity. Overall, a synthesis of local and regional factors emerged as the model that best explain variations in plant species diversity. The studies also suggest that the effects of determinants on species diversity have a complex relationship with scale.