Browsing by Title

Sort by: Order: Results:

Now showing items 5307-5326 of 25615
  • Melkas, Helinä (1999)
    The thesis analyses gender inequality in the labour market, in particular Occupational segregation by sex in Finland, Norway and Sweden from the 1970s to the 1990s. The thesis focuses on the divergence between the general perception of equality and the reality of inequality in the Nordic labour markets. The Nordic countries are in many ways model countries as far as gender equality is concerned, but women's position in the world of work is still considerably weaker than men's. The background part of the thesis describes the impact of occupational segregation on women, theories on occupational segregation, the characteristics of Nordic labour markets as compared to other OECD countries and elements of Nordic equality policies. The statistical analysis of the thesis is based on census data for 1970, 1980 and 1990 compiled by the Central Statistical Offices. The original national data include approximately 300 occupations. In order to increase comparability in this thesis, a common occupational classification with 187 occupations was created for all three countries. This was possible owing to the sufficiently similar national occupational classifications. The statistical analysis shows how the segregation situation of Finland, Norway and Sweden differs from other industrialised countries and how these three Nordic countries differ from each other in terms of segregation. Statistics are presented on gender-dominated occupations, segregation indices, monetization of household work (i.e. transfer of typical household work to the labour market to be done as paid work) and women and men in certain closely related occupations where there are distinguishable differences in status. The analysis also tests the explanatory force of segregation theories in the Nordic context. The analysis confirms that the level of occupational segregation by sex has been, and remains, high in Finland, Norway and Sweden - both in absolute terms as well as relative to levels found in other industrialized countries. However, the level of segregation decreased from 1970 to 1990. Women have been more eager to cross the occupational gender barriers than men, who have preferred to stay in traditional "male" occupations. The extent to which women still work in traditional "female" occupations causes Nordic countries to have the relatively high level of segregation. These "female" occupations are consistent with gender stereotypes in society and the types of abilities and characteristics that are typically attributed to women. Women are also concentrated. in lower status and lower paid occupations than men, even if they work in the same field. The thesis is largely based on the author's monograph with the same title (Melkas & Anker, 1998). The most important sources in the study are labour market statistics and occupational classification systems. As to the methodology of research on segregation, central sources are the works of Siltanen, Jarman & Blackburn, 1995 and Anker, 1998.
  • Repo, Jemima (Helsingin yliopisto, 2006)
    This thesis contributes to the development of poststructuralist feminist International Relations analyses about the US War on Terrorism. Gender is significantly involved in the justification and conduct of wars and militarism, established and supported by a particular hierarchal structure of masculinities and femininities. Hierarchal power relations prioritise the bodies and values of some, and demean, attack or conceal those of others. These are expressed in discourses of the various masculinities and femininities of the US self and its enemy Other, which are deconstructed and analysed by Foucauldian discourse analysis and theories of representation. Discourses of a male-performed 11 September 2001 terrorist attacks and US rescue response endowed hegemonic masculinity on the muscular masculinity of fire fighters. This was subsequently extended to soldiers of the US military, who fought in retaliation to the humiliation of feminised US nationhood, remasculinising the US national identity. This necessitated the representation of terrorists and Muslim men as morally and sexually deviant, homosexual, woman-oppressive demons. Likewise, Muslim women were victimised as helpless sufferers to be unveiled and rescued by a macho US crusade against terrorism. On the other hand, female terrorists confused the men-lifetakers/ women-lifegivers dichotomy, and were depicted as excessively violent, hypersexual beings, who were nonetheless victims of the seductions of manipulative Muslim men. Disciplinary action was taken against Muslim men in Guantánamo Bay and Abu Ghraib, which especially in the latter case resulted in scandals that evoked public pity for the unfortunate and uncivilised detainees who endured the torture of cruel un-American men and irrational women of the US Military Police. Meanwhile, the discourses of US soldiers in Iraq are examined through their own autobiographical voices, demonstrating that the military is indeed a misogynistic boy's club. The fate of Private Jessica Lynch and the autobiographical works of soldiers also unsympathetic to the Iraqi population, continuing the Othering discourses established on 11 September. At the US home front, military mothers, both pro and anti-war, are supportive of the well being and honouring of their sons. There is a complex set of dominant discourses in continuous fluctuation sustaining the gender hierarchies that support war by privileging the bodies of some and discriminating and harming the bodies others. There is hope for change however, as the malleability of gender enables possibilities for resistance through counter discourses and female empowerment. Key words US foreign policy, Militarisation, Feminist International Relations, War on Terrorism, Discourse analysis
  • Repo, Jemima Isabel (2006)
    This thesis contributes to the development of poststructuralist feminist International Relations analyses about the US War on Terrorism. Gender is significantly involved in the justification and conduct of wars and militarism, established and supported by a particular hierarchal structure of masculinities and femininities. Hierarchal power relations prioritise the bodies and values of some, and demean, attack or conceal those of others. These are expressed in discourses of the various masculinities and femininities of the US self and its enemy Other, which are deconstructed and analysed by Foucauldian discourse analysis and theories of representation. Discourses of a male-performed 11 September 2001 terrorist attacks and US rescue response endowed hegemonic masculinity on the muscular masculinity of fire fighters. This was subsequently extended to soldiers of the US military, who fought in retaliation to the humiliation of feminised US nationhood, remasculinising the US national identity. This necessitated the representation of terrorists and Muslim men as morally and sexually deviant, homosexual, woman-oppressive demons. Likewise, Muslim women were victimised as helpless sufferers to be unveiled and rescued by a macho US crusade against terrorism. On the other hand, female terrorists confused the men-lifetakers/ women-lifegivers dichotomy, and were depicted as excessively violent, hypersexual beings, who were nonetheless victims of the seductions of manipulative Muslim men. Disciplinary action was taken against Muslim men in Guantánamo Bay and Abu Ghraib, which especially in the latter case resulted in scandals that evoked public pity for the unfortunate and uncivilised detainees who endured the torture of cruel un-American men and irrational women of the US Military Police. Meanwhile, the discourses of US soldiers in Iraq are examined through their own autobiographical voices, demonstrating that the military is indeed a misogynistic boy’s club. The fate of Private Jessica Lynch and the autobiographical works of soldiers also unsympathetic to the Iraqi population, continuing the Othering discourses established on 11 September. At the US home front, military mothers, both pro and anti-war, are supportive of the well being and honouring of their sons. There is a complex set of dominant discourses in continuous fluctuation sustaining the gender hierarchies that support war by privileging the bodies of some and discriminating and harming the bodies others. There is hope for change however, as the malleability of gender enables possibilities for resistance through counter discourses and female empowerment.
  • Kassea, B. Raul (Department of Social Psychology, 2006)
    Gender perceptions, religious belief systems, and political thought have excluded women from politics, for ages, around the world. Combining feminist and modernisation theorists in my theoretical framework, I examine the trends in patriarchal Europe and I highlight the gender-sensitive model of the Nordic countries. Retracing local gender patterns from precolonial to postcolonial eras in sub-Saharan Africa, I explore the links between perceptions, needs, resources, education and women's political participation in Cameroon. Democratisation is supposed to open up political participation, to grant equal opportunities to all adults. One ironic feature of the liberalisation process in Cameroon has been the decrease of women in parliamentarian representation (14% in 1988, 6% in 1992, 5% in 1997 and 10% in 2002). What social, cultural and institutional mechanisms produced this paradoxical outcome, the exclusion of half the population? The gender complementarity of the indigenous context has been lost to male prevalence privileged by education, church, law, employment, economy and politics in the public sphere; most women are marginalised in the private sphere. Nation building and development have failed; ethnicism and individualism are growing. Some hope lies in the growing civil society. From two surveys and 21 focus groups across Cameroon, in 2000 and 2002, some significant results of the processed empirical data reveal low electoral registration (34.5% women and 65.9% men), contrasted by the willingness to run for municipal elections (33.3 % women and 45.2% men). The co-existence of customary and statutory laws, the corrupt political system and fraudulent practices, contribute to the marginalisation of women and men who are interested in politics. A large majority of female respondents consider female politicians more trustworthy and capable than their male counterparts; they even foresee the appointment of a female Prime Minister. The Nordic countries have institutionalised gender equality in their legislation, policies and practices. France has improved women's political inclusion with the parity laws; Rwanda is another model of women's representation, thanks to its post-conflict constitution. From my analysis, Cameroonian institutions, men and more so women, may learn and borrow from these experiences, in order to design and implement a sustainable and gender-balanced democracy. Keywords: democratisation, politics, gender equality, feminism, citizenship, Cameroon, Nordic countries, Finland, France, United Kingdom, quotas, societal social psychology.
  • Nguyen, Tam (2015)
    This thesis studies a case of female Vietnamese immigrants in Finland and the structure of new gender roles due to the adaptation in the new land. Considering gender roles are practiced differently in different cultures and societies (Lindsey, 1990; Spain, 1993), it is sensible to study the changes of gender roles in families occurring as the result of adaptation when Vietnamese immigrants move from prevalent Confucius culture to Nordic one. The main objective of this thesis is to find out how Vietnamese female immigrants have defined their familial roles after migrating to Finland. Following the framework adopted from Foner (1997), this thesis analyzes the data taken from in-depth interviews with 10 lately-arrived female immigrants and supplementary information from 3 male immigrants, field notes and biographical questions. The research determines that these women experience new types of gender roles, which are formed by both some elements brought from home country and newly-learnt practices in Finland. The results show that although the main features of traditional gender relations are maintained, radical changes in different aspects including familial model, kin relationship, division of labour and decision-making power, could be noticed. Adapting to Finland, Vietnamese families in Finland have been transformed from traditional extended to nuclear family model, which has had a major effect on traditional familial relationships and defining gender roles. These Vietnamese women lose the position of co-breadwinners, therefore, they maintain the traditional role as homemakers. However, as a strategy of coping with the lack of support and influence of external family members, Vietnamese women seem to have more power in making decision and benefit better involvement of husbands in domestic work and child-care.
  • Heikkinen, Merja (Helsingin yliopisto, 2012)
    Tutkielmassa tarkastellaan kvalitatiivisesti Markus Kajon pakinoiden geneerisiä persoonailmauksia. Kajon pakinat ovat yleensä sivun mittaisia tekstejä, joissa käsitellään usein arkipäiväisiä ilmiöitä sekä pienistä suuriin mittasuhteisiin kasvavia mitä jos? -ajatuksesta liikkeelle lähteviä skenaarioita. Koska monet pakinoiden kuvaamat ilmiöt esitetään yleisinhimillisinä eli sellaisina, että ne voivat sattua kenelle tahansa, tämä ilmenee myös persoonapronominien tasolla. Aineiston perusteella tutkimuksen tarkastelun kohteeksi ovat valikoituneet nollapersoona, geneerinen yksikön ja monikon ensimmäinen ja toinen persoona sekä substantiivi-ilmaukset kuten ihminen ja henkilö. Tutkimuksessa sivutaan myös niitä keinoja, joilla pakinoiden toimijoita kategorisoidaan ryhmiksi. Aineiston kielellisiä valintoja tarkastellaan kognitiivisen kielentutkimuksen periaatteiden kautta. Havaintoja vertaillaan sekä suomenkieliseen että kansainväliseen geneeristen persoonailmausten teoriaan. Aineiston analyysissä hyödynnetään myös labovilaista kertomusskeemaa, jota vasten pronominivalintoja ja niiden mahdollista vaihtelua tutkitaan silloin, kun pakinan rakenne sopii siihen. Tutkimus on tehty analysoimalla Kajon pakinoiden geneerisiä persoonailmauksia tekstikontekstissaan. Vaikka geneerisiä persoonailmauksia voi pitää periaatteessa samaviitteisinä ne kaikki voisi yleensä korvata tekstikontekstissa parafraasilla kuka tahansa niillä voi tulosten perusteella havaita olevan retorisia eroja. Niiden avulla voidaan esimerkiksi kategorisoida toimijoita sisä- ja ulkoryhmiin tai tuoda ilmi sitä, miten toisinaan affektinen kertojanääni suhteuttaa yleisön itseensä. Myös nollapersoonan rakenteelliset rajoitukset saattavat motivoida muiden geneeristen muotojen käyttöä. Tämän lisäksi pakinoiden tarkastelu kertomusskeeman kautta osoittaa, että kertomusrakenteella näyttää olevan vaikutusta erilaisten geneeristen muotojen variaatioon. Esimerkiksi nollapersoona esiintyy usein johdattelevissa ja arvioivissa osuuksissa, kun taas geneeristen persoonapronominien kuten yksikön toisen persoonan avulla voidaan ikään kuin zoomata lähemmäs toimintaan.
  • Julkunen, Veli-Pekka (2006)
    Valuuttakriisit ovat yksi tämän päivän vakavimmista maailmantalouden vakautta uhkaavista ilmiöistä. Vaikka valuuttakriisejä on ollut niin kauan, kun kansainvälistä kauppaa on käyty, ovat niiden lukumäärä lisääntynyt viimeisen 20 vuoden aikana etenkin kehittyvien talouksien kohdalla. Valuuttakriisit, kuten monet muutkin taloudelliset ilmiöt ovat hyvin monimutkaisia ja vaikeasti ymmärrettäviä, jolloin niiden ennustaminen ja niihin johtavien syiden selvittäminen on erittäin vaikeaa. Koska valuuttakriisit johtavat usein reaalitaloudellisiin ongelmiin, on niiden ymmärtämiseen ja ennustamiseen uhrattu valtavasti resursseja. Valuuttakriisien ennustettavuuden paraneminen voisi etenkin sijoittajien kohdalla johtaa suuriin taloudellisiin tuottoihin, ja toisaalta tarkempien ennustemallien perusteella voitaisiin ryhtyä kriisejä ehkäiseviin toimiin jo ennen kuin kriisi edes kerkeäisi puhjeta ja näin kriisiltä saatettaisiin välttyä kokonaan. Tutkielmassa esitellään neuroverkot uutena menetelmänä valuuttakriisien ennustamisessa. Neuroverkkoja on käytetty laajasti mm. tekniikan alalla jo vuosia, mutta taloustieteissä menetelmää on sovellettu suhteellisen vähän. Valitettavasti useissa kansantaloudellisia ilmiöitä käsitelleissä tutkimuksissa, joissa neuroverkkojen tehokkuutta on vertailtu perinteisiin menetelmiin, on ollut selkeitä puutteita. Tällöin ei ole ollut mahdollista sanoa onko neurolaskennasta taloustieteiden alalla todellista hyötyä. Tutkielman tarkoituksena onkin selvittää, voiko neuroverkkomallien avulla päästä tarkempiin ennustetuloksiin kuin niin sanotuilla perinteisillä menetelmillä (joita tutkielmassa edustavat erilaiset logit-mallit) kehittyvien talouksien valuuttakriisien ennustamisesssa. Lisäksi tutkielmassa esitellään menetelmiä, joiden avulla eri mallien toimintaa yritetään tehostaa. Perinteisien mallien ennustetarkkuutta yritetään parantaa erilaisin muuttujamuunnoksin ja neuroverkkomallien toiminnan tehostamiseksi käytetään puolestaan geneettisten algoritmien nimellä tunnettuja optimointimenetelmiä sekä kehittyneempiä estimointialgoritmeja. Saatujen tutkimustulosten perusteella voidaan todeta, että neuroverkkomalleilla voidaan päästä merkittävästi parempiin tuloksiin kuin ilman muuttujamuunnoksin estimoiduilla logit-malleilla. Toisaalta muuttujamuunnoksilla pystyttiin logit-mallien ennustetarkkuutta parantamaan selvästi, jolloin perinteisten- ja neuroverkkomallien välinen ero ennustetarkkuudessa oli lopulta suhteellisen pieni. Tärkeimmät lähteet: HASSOUN, M. (1995): Fundamentals of artificial neural networks. The MIT press, Cambridge. KOMULAINEN, T. – LUKKARILA, J. (2003): What drives financiel crises in emerging markets? Emerging markets review, 4, 248–272. BISHOP, C. (1995): Neural networks for pattern recognition. Clarendon press, Oxford.
  • Muniandy, Maheswary (2014)
    The study of obesity has drawn wide-spread interest because of its far-reaching consequences. Obesity is on the rise and has been linked to several clinical complications such as type 2 diabetes and hypertension. Obesity is defined as a condition in which body mass index (BMI) is greater than 3m2/kg. BMI itself is highly heritable with the rate of heritability in twin and adoption studies ranging from 45%–85%. The study was designed to analyze the differences in gene expression in MZ twin pairs discordant for BMI. A total of 26 twin pairs were selected based on a within-pair BMI difference of more than 3 kg/m2 when compared to his or her twin. The twins for this study belonged to either FinnTwin16 (birth cohort 1975‐1979) or FinnTwin12 (birth cohort 1983‐1987). Samples were extracted from the participants and used in microarray experiments. The resulting data was processed using various packages of the Bioconductor software. The quality control process identified one sample as faulty and as a result the sample as well as the sample of the twin were discarded. This resulted in a sample size of 50 twins. Differential analysis carried out using the limma package of Bioconductor revealed 980 genes that were differentially expressed. These genes were then processed further in the Ingenuity Pathway Analysis (IPA) tool as well as the BiNGO tool. This revealed the molecular networks, gene pathways and gene annotations that were pertinent to the genes uploaded. IPA also provided a list of functions and diseases these genes were involved in. As the final step, the prevalent themes across these results were summarized. This analysis provided many leads that should be investigated further in future studies. It is suggested that future studies start with precise, concrete biological questions that narrow down the scope of biological analysis. This is in view of the extensive amount of data available via microarray studies and the myriad of hypothesizes that can be investigated.
  • Greco, Dario (Helsingin yliopisto, 2009)
    The time of the large sequencing projects has enabled unprecedented possibilities of investigating more complex aspects of living organisms. Among the high-throughput technologies based on the genomic sequences, the DNA microarrays are widely used for many purposes, including the measurement of the relative quantity of the messenger RNAs. However, the reliability of microarrays has been strongly doubted as robust analysis of the complex microarray output data has been developed only after the technology had already been spread in the community. An objective of this study consisted of increasing the performance of microarrays, and was measured by the successful validation of the results by independent techniques. To this end, emphasis has been given to the possibility of selecting candidate genes with remarkable biological significance within specific experimental design. Along with literature evidence, the re-annotation of the probes and model-based normalization algorithms were found to be beneficial when analyzing Affymetrix GeneChip data. Typically, the analysis of microarrays aims at selecting genes whose expression is significantly different in different conditions followed by grouping them in functional categories, enabling a biological interpretation of the results. Another approach investigates the global differences in the expression of functionally related groups of genes. Here, this technique has been effective in discovering patterns related to temporal changes during infection of human cells. Another aspect explored in this thesis is related to the possibility of combining independent gene expression data for creating a catalog of genes that are selectively expressed in healthy human tissues. Not all the genes present in human cells are active; some involved in basic activities (named housekeeping genes) are expressed ubiquitously. Other genes (named tissue-selective genes) provide more specific functions and they are expressed preferably in certain cell types or tissues. Defining the tissue-selective genes is also important as these genes can cause disease with phenotype in the tissues where they are expressed. The hypothesis that gene expression could be used as a measure of the relatedness of the tissues has been also proved. Microarray experiments provide long lists of candidate genes that are often difficult to interpret and prioritize. Extending the power of microarray results is possible by inferring the relationships of genes under certain conditions. Gene transcription is constantly regulated by the coordinated binding of proteins, named transcription factors, to specific portions of the its promoter sequence. In this study, the analysis of promoters from groups of candidate genes has been utilized for predicting gene networks and highlighting modules of transcription factors playing a central role in the regulation of their transcription. Specific modules have been found regulating the expression of genes selectively expressed in the hippocampus, an area of the brain having a central role in the Major Depression Disorder. Similarly, gene networks derived from microarray results have elucidated aspects of the development of the mesencephalon, another region of the brain involved in Parkinson Disease.
  • Nuutila, Kristo (Helsingin yliopisto, 2013)
    Information on the molecular details of human skin wound healing has been limited due to several types of challenges faced when data from basic research are adapted for use in clinical studies. Comprehensive genomewide data on gene behaviour during the various phases of wound healing have not been available, although many techniques, such as gene expression microarrays and RNA sequencing would, have made it possible. The aim of my doctoral thesis was to examine human skin regeneration and to develop ways to enhance wound healing, especially in burn wound treatment. The main goal was to characterize the gene expression transcriptome of human donor site wounds over time. Skin biopsies were collected from patients before and after split-thickness skin graft harvesting. The first biopsy of intact skin was obtained immediately before the site was wounded by the graft harvest. Immediately thereafter, a second biopsy was performed to serve as a sample an of acute wound. Later, the next biopsies were obtained on the 3rd, 7th, 14th and 21st postoperative days. The skin graft donor site wound was chosen because it is controllably made in the operating room and represents a normal, uncomplicated, and consistently healing superficial skin wound. Negative pressure was applied to some of the donor sites to clarify the effects of this widely used therapy on gene expression in a healing wound. Moreover, this approach enabled the initial evaluation of the gene expression profiling principle for clinical research purposes. The tissue samples collected were homogenized, and ribonucleic acid (RNA) was isolated. Thereafter, genomewide microarrays were performed on all samples. The gene profiles at different time points were compared, and data were presented as fold-change alterations in gene expression. As a result, the data reveals various types of gene expression patterns relating to, loss of expression due to tissue removal, down-regulation or induction of expression as the wound-healing cascade advances or regain of expression according to tissue regeneration. The results also give molecular level information on the effects of negative-pressure wound therapy. These studies provide the first insights into the transcriptome during normal human superficial cutaneous wound healing. The data reveal novel genes associated with epidermal wound healing. Moreover, they provide a fundamental background for future studies that can be utilized in the clinical evaluation of the effects of therapies.
  • Kuparinen, Anna (Helsingin yliopisto, 2007)
    The future use of genetically modified (GM) plants in food, feed and biomass production requires a careful consideration of possible risks related to the unintended spread of trangenes into new habitats. This may occur via introgression of the transgene to conventional genotypes, due to cross-pollination, and via the invasion of GM plants to new habitats. Assessment of possible environmental impacts of GM plants requires estimation of the level of gene flow from a GM population. Furthermore, management measures for reducing gene flow from GM populations are needed in order to prevent possible unwanted effects of transgenes on ecosystems. This work develops modeling tools for estimating gene flow from GM plant populations in boreal environments and for investigating the mechanisms of the gene flow process. To describe spatial dimensions of the gene flow, dispersal models are developed for the local and regional scale spread of pollen grains and seeds, with special emphasis on wind dispersal. This study provides tools for describing cross-pollination between GM and conventional populations and for estimating the levels of transgenic contamination of the conventional crops. For perennial populations, a modeling framework describing the dynamics of plants and genotypes is developed, in order to estimate the gene flow process over a sequence of years. The dispersal of airborne pollen and seeds cannot be easily controlled, and small amounts of these particles are likely to disperse over long distances. Wind dispersal processes are highly stochastic due to variation in atmospheric conditions, so that there may be considerable variation between individual dispersal patterns. This, in turn, is reflected to the large amount of variation in annual levels of cross-pollination between GM and conventional populations. Even though land-use practices have effects on the average levels of cross-pollination between GM and conventional fields, the level of transgenic contamination of a conventional crop remains highly stochastic. The demographic effects of a transgene have impacts on the establishment of trangenic plants amongst conventional genotypes of the same species. If the transgene gives a plant a considerable fitness advantage in comparison to conventional genotypes, the spread of transgenes to conventional population can be strongly increased. In such cases, dominance of the transgene considerably increases gene flow from GM to conventional populations, due to the enhanced fitness of heterozygous hybrids. The fitness of GM plants in conventional populations can be reduced by linking the selectively favoured primary transgene to a disfavoured mitigation transgene. Recombination between these transgenes is a major risk related to this technique, especially because it tends to take place amongst the conventional genotypes and thus promotes the establishment of invasive transgenic plants in conventional populations.
  • Myrskylä, Mikko (Helsingin yliopisto, 2007)
    This study examines the properties of Generalised Regression (GREG) estimators for domain class frequencies and proportions. The family of GREG estimators forms the class of design-based model-assisted estimators. All GREG estimators utilise auxiliary information via modelling. The classic GREG estimator with a linear fixed effects assisting model (GREG-lin) is one example. But when estimating class frequencies, the study variable is binary or polytomous. Therefore logistic-type assisting models (e.g. logistic or probit model) should be preferred over the linear one. However, other GREG estimators than GREG-lin are rarely used, and knowledge about their properties is limited. This study examines the properties of L-GREG estimators, which are GREG estimators with fixed-effects logistic-type models. Three research questions are addressed. First, I study whether and when L-GREG estimators are more accurate than GREG-lin. Theoretical results and Monte Carlo experiments which cover both equal and unequal probability sampling designs and a wide variety of model formulations show that in standard situations, the difference between L-GREG and GREG-lin is small. But in the case of a strong assisting model, two interesting situations arise: if the domain sample size is reasonably large, L-GREG is more accurate than GREG-lin, and if the domain sample size is very small, estimation of assisting model parameters may be inaccurate, resulting in bias for L-GREG. Second, I study variance estimation for the L-GREG estimators. The standard variance estimator (S) for all GREG estimators resembles the Sen-Yates-Grundy variance estimator, but it is a double sum of prediction errors, not of the observed values of the study variable. Monte Carlo experiments show that S underestimates the variance of L-GREG especially if the domain sample size is minor, or if the assisting model is strong. Third, since the standard variance estimator S often fails for the L-GREG estimators, I propose a new augmented variance estimator (A). The difference between S and the new estimator A is that the latter takes into account the difference between the sample fit model and the census fit model. In Monte Carlo experiments, the new estimator A outperformed the standard estimator S in terms of bias, root mean square error and coverage rate. Thus the new estimator provides a good alternative to the standard estimator.
  • Raerinne, Jani (Helsingin yliopisto, 2011)
    The question at issue in this dissertation is the epistemic role played by ecological generalizations and models. I investigate and analyze such properties of generalizations as lawlikeness, invariance, and stability, and I ask which of these properties are relevant in the context of scientific explanations. I will claim that there are generalizable and reliable causal explanations in ecology by generalizations, which are invariant and stable. An invariant generalization continues to hold or be valid under a special change called an intervention that changes the value of its variables. Whether a generalization remains invariant during its interventions is the criterion that determines whether it is explanatory. A generalization can be invariant and explanatory regardless of its lawlike status. Stability deals with a generality that has to do with holding of a generalization in possible background conditions. The more stable a generalization, the less dependent it is on background conditions to remain true. Although it is invariance rather than stability of generalizations that furnishes us with explanatory generalizations, there is an important function that stability has in this context of explanations, namely, stability furnishes us with extrapolability and reliability of scientific explanations. I also discuss non-empirical investigations of models that I call robustness and sensitivity analyses. I call sensitivity analyses investigations in which one model is studied with regard to its stability conditions by making changes and variations to the values of the model s parameters. As a general definition of robustness analyses I propose investigations of variations in modeling assumptions of different models of the same phenomenon in which the focus is on whether they produce similar or convergent results or not. Robustness and sensitivity analyses are powerful tools for studying the conditions and assumptions where models break down and they are especially powerful in pointing out reasons as to why they do this. They show which conditions or assumptions the results of models depend on. Key words: ecology, generalizations, invariance, lawlikeness, philosophy of science, robustness, explanation, models, stability
  • Tornberg, Janne (Helsingin yliopisto, 2006)
    The cation-Cl- cotransporter (CCC) family comprises of Na+-Cl- cotransporter (NCC), Na+-K+-2Cl- cotransporters (NKCC1-2), and four K+-Cl- cotransporters (KCC1-4). These proteins are involved in several physiological activities, such as cell volume regulation. In neuronal tissues, NKCC1 and KCC2 are important in determining the intracellular Cl- levels and hence the neuronal responses to inhibitory neurotransmitters GABA and glycine. One aim of the work was to elucidate the roles for CCC isoforms in the control of nervous system development. KCC2 mRNA was shown to be developmentally up-regulated and follow neuronal maturation, whereas NKCC1 and KCC4 transcripts were highly expressed in the proliferative zones of subcortical regions. KCC1 and KCC3 mRNA displayed low expression throughout the embryogenesis. These expression profiles suggest a role for CCC isoforms in maturation of synaptic responses and in the regulation of neuronal proliferation during embryogenesis. The major aim of this work was to study the biological consequences of KCC2-deficiency in the adult CNS, by generating transgenic mice retaining 15-20% of normal KCC2 levels. In addition, by using these mice as a tool for in vivo pharmacological analysis, we investigated the requirements for KCC2 in tonic versus phasic GABAA receptor-mediated inhibition. KCC2-deficient mice displayed normal reproduction and life span, but showed several behavioral abnormalities, including increased anxiety-like behavior, impaired performance in water maze, alterations in nociceptive processing, and increased seizure susceptibility. In contrast, the mice displayed apparently normal spontaneous locomotor activity and motor coordination. Pharmacological analysis of KCC2-deficient mice revealed reduced sensititivity to diazepam, but normal gaboxadol-induced sedation, neurosteroid hypnosis and alcohol-induced motor impairment. Electrophysiological recordings from CA1-CA3 subregions of the hippocampus showed that KCC2 deficiency affected the reversal potentials of both the phasic and tonic GABA currents, and that the tonic conductance was not affected. The results suggest that requirement for KCC2 in GABAergic neurotransmission may differ among several functional systems in the CNS, which is possibly due to the more critical role of KCC2 activity in phasic compared to tonic GABAergic inhibition.