26 resultados para Singular Trajectories

em Helda - Digital Repository of University of Helsinki


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Tutkimuksen aihe on subjektipronominin ei-pakollinen käyttö finiittisten verbimuotojen yhteydessä espanjan ja portugalin kielessä. Tutkimuskohteena ovat yksikön ensimmäisen persoonan verbimuodot Espanjassa ja Portugalissa kerätyissä puhekielen korpuksissa. Tutkimuksen tarkoitus on selvittää, mitkä semanttiset ja pragmaattiset tekijät vaikuttavat subjektipronominin ei-pakollisen käytön yleisyyteen ja mitä systemaattisia eroja subjektipronominin käytössä on espanjan ja portugalin välillä. Tutkimus kuuluu korpuslingvistiikan alaan ja ensisijaisena tutkimusmetodina on kvantitatiivinen vertailu. Tutkimus osoittaa, että yksikön ensimmäisen persoonan subjektipronominin ei-pakollinen käyttö on käytännössä kaikissa konteksteissa yleisempää portugalissa kuin espanjassa. Tätä eroa voidaan selittää kielten konstituenttirakenteen typologisella erilaisuudella. Subjektin semanttinen rooli on tutkimuksen perusteella sidoksissa subjektipronominin käyttöön enemmän espanjassa kuin portugalissa, mutta kummassakaan kielessä subjektipronominin käyttöä ei voida selittää pelkästään subjektin semanttisella roolilla. Molemmissa kielissä samanviitteisyys edellisen subjektin kanssa vähentää subjektipronominin käyttöä, kun taas subjektipronominin ei-referentiaalinen käyttö ja toisaalta verbin ilmaiseman toiminnan irreaalisuus lisäävät sitä. Tutkimustulokset antavat aihetta lisätutkimukseen pronominien ja verbien ei-referentiaalisesta ja irreaalisesta käytöstä espanjassa ja portugalissa sekä typologi-seen tutkimukseen subjektipronominien käyttöön vaikuttavista tekijöistä eri kielissä.

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The topic of this dissertation lies in the intersection of harmonic analysis and fractal geometry. We particulary consider singular integrals in Euclidean spaces with respect to general measures, and we study how the geometric structure of the measures affects certain analytic properties of the operators. The thesis consists of three research articles and an overview. In the first article we construct singular integral operators on lower dimensional Sierpinski gaskets associated with homogeneous Calderón-Zygmund kernels. While these operators are bounded their principal values fail to exist almost everywhere. Conformal iterated function systems generate a broad range of fractal sets. In the second article we prove that many of these limit sets are porous in a very strong sense, by showing that they contain holes spread in every direction. In the following we connect these results with singular integrals. We exploit the fractal structure of these limit sets, in order to establish that singular integrals associated with very general kernels converge weakly. Boundedness questions consist a central topic of investigation in the theory of singular integrals. In the third article we study singular integrals of different measures. We prove a very general boundedness result in the case where the two underlying measures are separated by a Lipshitz graph. As a consequence we show that a certain weak convergence holds for a large class of singular integrals.

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The monograph dissertation deals with kernel integral operators and their mapping properties on Euclidean domains. The associated kernels are weakly singular and examples of such are given by Green functions of certain elliptic partial differential equations. It is well known that mapping properties of the corresponding Green operators can be used to deduce a priori estimates for the solutions of these equations. In the dissertation, natural size- and cancellation conditions are quantified for kernels defined in domains. These kernels induce integral operators which are then composed with any partial differential operator of prescribed order, depending on the size of the kernel. The main object of study in this dissertation being the boundedness properties of such compositions, the main result is the characterization of their Lp-boundedness on suitably regular domains. In case the aforementioned kernels are defined in the whole Euclidean space, their partial derivatives of prescribed order turn out to be so called standard kernels that arise in connection with singular integral operators. The Lp-boundedness of singular integrals is characterized by the T1 theorem, which is originally due to David and Journé and was published in 1984 (Ann. of Math. 120). The main result in the dissertation can be interpreted as a T1 theorem for weakly singular integral operators. The dissertation deals also with special convolution type weakly singular integral operators that are defined on Euclidean spaces.

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Fluid bed granulation is a key pharmaceutical process which improves many of the powder properties for tablet compression. Dry mixing, wetting and drying phases are included in the fluid bed granulation process. Granules of high quality can be obtained by understanding and controlling the critical process parameters by timely measurements. Physical process measurements and particle size data of a fluid bed granulator that are analysed in an integrated manner are included in process analytical technologies (PAT). Recent regulatory guidelines strongly encourage the pharmaceutical industry to apply scientific and risk management approaches to the development of a product and its manufacturing process. The aim of this study was to utilise PAT tools to increase the process understanding of fluid bed granulation and drying. Inlet air humidity levels and granulation liquid feed affect powder moisture during fluid bed granulation. Moisture influences on many process, granule and tablet qualities. The approach in this thesis was to identify sources of variation that are mainly related to moisture. The aim was to determine correlations and relationships, and utilise the PAT and design space concepts for the fluid bed granulation and drying. Monitoring the material behaviour in a fluidised bed has traditionally relied on the observational ability and experience of an operator. There has been a lack of good criteria for characterising material behaviour during spraying and drying phases, even though the entire performance of a process and end product quality are dependent on it. The granules were produced in an instrumented bench-scale Glatt WSG5 fluid bed granulator. The effect of inlet air humidity and granulation liquid feed on the temperature measurements at different locations of a fluid bed granulator system were determined. This revealed dynamic changes in the measurements and enabled finding the most optimal sites for process control. The moisture originating from the granulation liquid and inlet air affected the temperature of the mass and pressure difference over granules. Moreover, the effects of inlet air humidity and granulation liquid feed rate on granule size were evaluated and compensatory techniques used to optimize particle size. Various end-point indication techniques of drying were compared. The ∆T method, which is based on thermodynamic principles, eliminated the effects of humidity variations and resulted in the most precise estimation of the drying end-point. The influence of fluidisation behaviour on drying end-point detection was determined. The feasibility of the ∆T method and thus the similarities of end-point moisture contents were found to be dependent on the variation in fluidisation between manufacturing batches. A novel parameter that describes behaviour of material in a fluid bed was developed. Flow rate of the process air and turbine fan speed were used to calculate this parameter and it was compared to the fluidisation behaviour and the particle size results. The design space process trajectories for smooth fluidisation based on the fluidisation parameters were determined. With this design space it is possible to avoid excessive fluidisation and improper fluidisation and bed collapse. Furthermore, various process phenomena and failure modes were observed with the in-line particle size analyser. Both rapid increase and a decrease in granule size could be monitored in a timely manner. The fluidisation parameter and the pressure difference over filters were also discovered to express particle size when the granules had been formed. The various physical parameters evaluated in this thesis give valuable information of fluid bed process performance and increase the process understanding.

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This study reports a diachronic corpus investigation of common-number pronouns used to convey unknown or otherwise unspecified reference. The study charts agreement patterns in these pronouns in various diachronic and synchronic corpora. The objective is to provide base-line data on variant frequencies and distributions in the history of English, as there are no previous systematic corpus-based observations on this topic. This study seeks to answer the questions of how pronoun use is linked with the overall typological development in English and how their diachronic evolution is embedded in the linguistic and social structures in which they are used. The theoretical framework draws on corpus linguistics and historical sociolinguistics, grammaticalisation, diachronic typology, and multivariate analysis of modelling sociolinguistic variation. The method employs quantitative corpus analyses from two main electronic corpora, one from Modern English and the other from Present-day English. The Modern English material is the Corpus of Early English Correspondence, and the time frame covered is 1500-1800. The written component of the British National Corpus is used in the Present-day English investigations. In addition, the study draws supplementary data from other electronic corpora. The material is used to compare the frequencies and distributions of common-number pronouns between these two time periods. The study limits the common-number uses to two subsystems, one anaphoric to grammatically singular antecedents and one cataphoric, in which the pronoun is followed by a relative clause. Various statistical tools are used to process the data, ranging from cross-tabulations to multivariate VARBRUL analyses in which the effects of sociolinguistic and systemic parameters are assessed to model their impact on the dependent variable. This study shows how one pronoun type has extended its uses in both subsystems, an increase linked with grammaticalisation and the changes in other pronouns in English through the centuries. The variationist sociolinguistic analysis charts how grammaticalisation in the subsystems is embedded in the linguistic and social structures in which the pronouns are used. The study suggests a scale of two statistical generalisations of various sociolinguistic factors which contribute to grammaticalisation and its embedding at various stages of the process.

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In this study I offer a diachronic solution for a number of difficult inflectional endings in Old Church Slavic nominal declensions. In this context I address the perhaps most disputed and the most important question of the Slavic nominal inflectional morphology: whether there was in Proto-Slavic an Auslautgesetz (ALG), a law of final syllables, that narrowed the Proto-Indo-European vowel */o/ to */u/ in closed word-final syllables. In addition, the work contains an exhaustive morphological classification of the nouns and adjectives that occur in canonical Old Church Slavic. I argue that Proto-Indo-European */o/ became Proto-Slavic */u/ before word-final */s/ and */N/. This conclusion is based on the impossibility of finding credible analogical (as opposed to phonological) explanations for the forms supporting the ALG hypothesis, and on the survival of the neuter gender in Slavic. It is not likely that the */o/-stem nominative singular ending */-u/ was borrowed from the accusative singular, because the latter would have been the only paradigmatic form with the stem vowel */-u-/. It is equally unlikely that the ending */-u/ was borrowed from the */u/-stems, because the latter constituted a moribund class. The usually stated motivation for such an analogical borrowing, i.e. a need to prevent the merger of */o/-stem masculines with neuters of the same class, is not tenable. Extra-Slavic, as well as intra-Slavic evidence suggests that phonologically-triggered mergers between two semantically opaque genders do not tend to be prevented, but rather that such mergers lead to the loss of the gender opposition in question. On the other hand, if */-os/ had not become */-us/, most nouns and, most importantly, all adjectives and pronouns would have lost the formal distinction between masculines and neuters. This would have necessarily resulted in the loss of the neuter gender. A new explanation is given for the most apparent piece of evidence against the ALG hypothesis, the nominative-accusative singular of the */es/-stem neuters, e.g. nebo 'sky'. I argue that it arose in late Proto-Slavic dialects, replacing regular nebe, under the influence of the */o/- and */yo/-stems where a correlation had emerged between a hard root-final consonant and the termination -o, on the one hand, and a soft root-final consonant and the termination -e, on the other.

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Expressing generalized-personal meaning in Russian Based on data from Russian, this doctoral dissertation examines generalized-personal meaning that is, generic expressions referring to all human beings, people in general, each or any person (e.g. S vozrastom načinae cenit prostye ve či With age you start to appreciate simple things ). The study shares its basic theoretical orientation with functional approaches going from meaning to form . The objective of the thesis is to determine and describe the various linguistic means which can be used by the speaker to express generalized-personal meaning. The main material of the study consists of 2,000 examples collected from modern Russian literature, newspapers, and magazines. The linguistic means of expressing generalized-personal meaning are divided into three main classes. Morphological and lexico-grammatical means (22% of the material) include the use of personal pronouns and personal verbal endings. In Russian, all personal forms except the 3rd person singular can be used in a generalized-personal meaning. Lexical means (14% of the material) involve, above all, pronouns like vse all , ka dyj everyone , nikto no one , as well as the nouns čelovek man and ljudi people . In emotional speech, generalized-personal meaning can also be conveyed lexically by using utterances like da e idiot znaet even an idiot knows . In rhetorical questions the pronoun kto who can appear in this meaning (cf. Kto ne ljubit moro enoe?! Who doesn t like ice cream?! ). The third main class, syntactic means (64% of the material), consists of constructions in which the generic person is not expressed at the surface level. This class mainly includes two-component structures in which the infinitive relates to a modal predicative adverb (e.g. mo no can, be allowed to , nado must ), modal verb (e.g. stoit be worth(while) , sleduet must, be obliged to ), or predicative adverb ending in -о (e.g. trudno it is hard to , neprilično is not appropriate ). Other syntactic means are: one-component infinitive structures, so-called embedded structures, structures with a processual noun, passive constructions, and gerund constructions. The different forms of expression available in Russian are not interchangeable in all contexts. Even if a given context tolerates the substitution of one construction for another, the two expressions are never entirely synonymous. In addition to determining the range of forms which can express generalized-personal meaning, the study aims to compare these forms and to specify the conditions and possible restrictions (contextual, semantic, syntactic, stylistic, etc.) associated with the use of each construction. In Russian linguistics, the generalized-personal meaning has not been extensively studied from a functional perspective. The advantage of a meaning-based functional approach is that it gives a comprehensive picture of the diversity and distribution of the phenomenon.

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This study investigates the significance of art in Jean-Luc Nancy s philosophy. I argue that the notion of art contributes to some of Nancy s central ontological ideas. Therefore, I consider art s importance in its own right whether art does have ontological significance, and if so, how one should describe this with respect to the theme of presentation. According to my central argument, with his thinking on art Nancy attempts to give one viewpoint to what is called the metaphysics of presence and to its deconstruction. On which grounds, as I propose, may one say that art is not reducible to philosophy? The thesis is divided into two main parts. The first part, Presentation as a Philosophical Theme, is a historical genesis of the central concepts associated with the birth of presentation in Nancy s philosophy. I examine this from the viewpoint of the differentiation between the ontological notions of presentation and representation by concentrating on the influence of Martin Heidegger and Jacques Derrida, as well as of Hegel and Kant. I give an overview of the way in which being or sense for Nancy is to be described as a coming-into-presence or presentation . Therefore, being takes place in its singular plurality. I argue that Nancy redevelops Heidegger s account of being in two principal ways: first, in rethinking the ontico-ontological difference, and secondly, by striving to radicalize the Heideggerian concept of Mitsein, being-with . I equally wish to show the importance of Derrida s notion of différance and its inherence in Nancy s questioning of being that rests on the unfoundedness of existence. The second part, From Ontology to Art, draws on the importance of art and the aesthetic. If, in Nancy, the question of art touches upon its own limit as the limit of nothingness, how is art able to open its own strangeness and our exposure to this strangeness? My aim is to investigate how Nancy s thinking on art finds its place within the conceptual realm of its inherent difference and interval. My central concern is the thought of originary ungroundedness and the plurality of art and of the arts. As for the question of the difference between art and philosophy, I wish to show that what differentiates art from thought is the fact that art exposes what is obvious but not apparent, if apparent is understood in the sense of givenness. As for art s ability to deconstruct Nancy s ontological notions, I suggest that in question in art is its original heterogeneity and diversity. Art is a matter of differing art occurs singularly, as a local difference. With this in mind, I point out that in reflecting on art in terms of spacing and interval, as a thinker of difference Nancy comes closer to Derrida and his idea of différance than to the structure of Heidegger s ontological difference.

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In the last thirty years, primarily feminist scholars have drawn attention to and re-evaluated the philosophy of Simone de Beauvoir (1908 1986). Her philosophical practice has been described as non-systematic, and her literary writing has been viewed as part of her non-systematic mode of philosophising. This dissertation radically deepens the question concerning Beauvoir s philosophical motivations for turning to literature as a mode to express subjectivity. It explicates the central concepts of Beauvoir s philosophy of existence, which are subjectivity, ambiguity, paradox and temporality, and their background in the modern traditions of existential philosophy and phenomenology. It also clarifies Beauvoir s main reason to turn to literature in order to express subjectivity as both singular and universal: as a specific mode of communication, literature is able to make the universality of existence manifest in the concrete, singular and temporal texture of life. In addition, the thesis gives examples of how Beauvoir s literary works contribute to an understanding of the complexity of subjectivity. I use the expression poetics of subjectivity to refer to the systematic relation between Beauvoir s existential and phenomenological notion of subjectivity and her literary works, and to her articulations of a creative mode of using language, especially in the novel. The thesis is divided into five chapters, of which the first three investigate Beauvoir s philosophy of existence at the intersection of the modern traditions of thought that began with René Descartes and Søren Kierkegaard s intuitions about subjectivity. Chapter 1 interprets Beauvoir s notion of ambiguity, as compared to paradox, and argues that both determine her notion of existence. Chapters 2 and 3 investigate the phenomenological side of Beauvoir s philosophy through a study of her response to early French interpretations of transcendental subjectivity, especially in the works of Jean-Paul Sartre and Maurice Merleau-Ponty. My analysis shows that Edmund Husserl s distinction between different levels of subjective experience is central to Beauvoir s understanding of subjectivity and to the different ego concepts she uses. Chapter 4 is a study of Beauvoir s reflections on the expression of subjective thought, and, more specifically, her philosophical conceptions of the metaphysical novel and the autobiography as two modes of indirect communication. Chapter 5, finally, compares two modes of investigating concrete subjectivity; Beauvoir s conceptual study of femininity in Le deuxième sexe and her literary expression of subjectivity in the novel L Invitée. My analysis reveals and explicates Beauvoir s original contribution to a comprehensive understanding of the becoming and paradox of human existence: the fundamental insight that these phenomena are sexed, historically as well as imaginatively.

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The attempt to refer meaningful reality as a whole to a unifying ultimate principle - the quest for the unity of Being - was one of the basic tendencies of Western philosophy from its beginnings in ancient Greece up to Hegel's absolute idealism. However, the different trends of contemporary philosophy tend to regard such a speculative metaphysical quest for unity as obsolete. This study addresses this contemporary situation on the basis of the work of Martin Heidegger (1889-1976). Its methodological framework is Heidegger's phenomenological and hermeneutical approach to the history of philosophy. It seeks to understand, in terms of the metaphysical quest for unity, Heidegger's contrast between the first (Greek) beginning or "onset" (Anfang) of philosophy and another onset of thinking. This other onset is a possibility inherent in the contemporary situation in which, according to Heidegger, the metaphysical tradition has developed to its utmost limits and thereby come to an end. Part I is a detailed interpretation of the surviving fragments of the Poem of Parmenides of Elea (fl. c. 500 BC), an outstanding representative of the first philosophical beginning in Heidegger's sense. It is argued that the Poem is not a simple denial of apparent plurality and difference ("mortal acceptances," doxai) in favor of an extreme monism. Parmenides' point is rather to show in what sense the different instances of Being can be reduced to an absolute level of truth or evidence (aletheia), which is the unity of Being as such (to eon). What in prephilosophical human experience is accepted as being is referred to the source of its acceptability: intelligibility as such, the simple and undifferentiated presence to thinking that ultimately excludes unpresence and otherness. Part II interprets selected key texts from different stages in Heidegger's thinking in terms of the unity of Being. It argues that one aspect of Heidegger's sustained and gradually deepening philosophical quest was to think the unity of Being as singularity, as the instantaneous, context-specific, and differential unity of a temporally meaningful situation. In Being and Time (1927) Heidegger articulates the temporal situatedness of the human awareness of meaningful presence. His later work moves on to study the situational correlation between presence and the human awareness. Heidegger's "postmetaphysical" articulation seeks to show how presence becomes meaningful precisely as situated, in an event of differentiation from a multidimensional context of unpresence. In resigning itself to this irreducibly complicated and singular character of meaningful presence, philosophy also faces its own historically situated finitude. This resignation is an essential feature of Heidegger's "other onset" of thinking.

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Non-governmental organisations (NGOs) have gained an important role in development co-operation during the last two decades. The development funding channelled through NGOs has increased and the number of NGOs engaged in development activities, both North and South, has been growing. Supporting NGOs has been seen as one way to strengthen civil society in the South and to provide potential for enhancing more effective development than the state, and to exercise participatory development and partnership in their North-South relationships. This study focuses on learning in the co-operation practices of small Finnish NGOs in Morogoro, Tanzania. Drawing on the cultural-historical activity theory and the theory of expansive learning, in this study I understand learning as a qualitative change in the actual co-operation practices. The qualitative change, for its part, emerges out of attempts to deal with the contradictions in the present activity. I use the concept of developmental contradiction in exploring the co-operation of the small Finnish NGOs with their Tanzanian counterparts. Developmental contradiction connects learning to actual practice and its historical development. By history, in this study I refer to multiple developmental trajectories, such as trajectories of individual participants, organisations, co-operation practices and the institutional system in which the NGO-development co-operation is embedded. In the empirical chapters I explore the co-operation both in the development co-operation projects and in micro-level interaction between partners taking place within the projects. I analyse the perceptions of the Finnish participants about the different developmental trajectories, the tensions, inclusions and exclusions in the evolving object of co-operation in one project, the construction of power relations in project meetings in three projects, and the collision of explicated partnership with the emerging practice of trusteeship in one project. On the basis of the empirical analyses I elaborate four developmental contradictions and learning challenges for the co-operation. The developmental contradictions include: 1) implementing a ready-made Finnish project idea vs. taking the current activities of Tanzanian NGO as a starting point; 2) gaining experiences and cultural interaction vs. access to outside funding; 3) promoting the official tools of development co-operation in training vs. use of tools and procedures taken from the prior activities of both partners in actual practice; and 4) asymmetric relations between the partners vs. rhetoric of equal partnership. Consequently, on the basis of developmental contradictions four learning challenges are suggested: a shift from legitimation of Finnish ideas to negotiation, transcending the separate objects and finding a partly joint object, developing locally shared tools for the co-operation, and identification and reflection of the power relations in the practice of co-operation. Keywords: activity theory; expansive learning; NGO development co-operation; partnership; power

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One history in a multicomplex world The quintessence of history and grand historical narratives in the historical consciousness of class teacher students The study analyses the conception of history amongst class teacher students at the University of Helsinki. It also explores the expectations about the future that the students have on the basis of their views on history. The conceptions of the students are analysed against the background of the notion of one history which has been part of Western thought in the modern era and which is at the centre of the theoretical framework of this study. The Enlightenment project and the erosion of the role of the Church paved the way for the notion that history is an linear narrative of the progress of humankind and in which, implicitly, the Western countries are endowed with a special role as the vanguards of progress. In recent times these assumptions have been criticised by postmodernists and proponents of New History. The material of the study consists of interviews of twenty-two 19 26 years old class teacher students at the University of Helsinki. The topics in the interviews were the developments of the past and the future trajectories. The students conceived history as a field of knowledge that provides a unifying view on the world and helps to make today s world intelligible. Finnish history and global history were invested with features of a grand narrative of progress. In global history, progress and development were seen as characteristic of the Western world primarily. The students regarded the post-war Finnish history as a qualified success story in that they deplored the erosion of collectivist values and the rise of selfishness in recent decades. History was not conceived as a process of progress that would self-evidently continue in the future, but rather more as a field of contingency and cyclical change.The students regarded the increasing predominance of the market forces over democratically elected agencies, the antagonism between the West and the other parts of the world, and environmental risks as the major threats. Notwithstanding this general.pessimism about the future, the students had a very positive view of their own personal prospects. Keywords: historical consciouness, one history, future expectations

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This study highlights the formation of an artifact designed to mediate exploratory collaboration. The data for this study was collected during a Finnish adaptation of the thinking together approach. The aim of the approach is to teach pulps how to engage in educationally beneficial form of joint discussion, namely exploratory talk. At the heart of the approach lies a set of conversational ground rules aimed to promote the use of exploratory talk. The theoretical framework of the study is based on a sociocultural perspective on learning. A central argument in the framework is that physical and psychological tools play a crucial role in human action and learning. With the help of tools humans can escape the direct stimulus of the outside world and learn to control ourselves by using tools. During the implementation of the approach, the classroom community negotiates a set of six rules, which this study conceptualizes as an artifact that mediates exploratory collaboration. Prior research done about the thinking together approach has not extensively researched the formation of the rules, which give ample reason to conduct this study. The specific research questions asked were: What kind of negotiation trajectories did the ground rules form during the intervention? What meanings were negotiated for the ground rules during the intervention The methodological framework of the study is based on discourse analysis, which has been specified by adapting the social construction of intertextuality to analyze the meanings negotiated for the created rules. The study has town units of analysis: thematic episode and negotiation trajectory. A thematic episode is a stretch of talk-in-interaction where the participants talk about a certain ground rule or a theme relating to it. A negotiation trajectory is a chronological representation of the negotiation process of a certain ground rule during the intervention and is constructed of thematic episodes. Thematic episodes were analyzed with the adapted intertextuality analysis. A contrastive analysis was done on the trajectories. Lastly, the meanings negotiated for the created rules were compared to the guidelines provided by the approach. The main result of the study is the observation, that the meanings of the created rules were more aligned with the ground rules of cumulative talk, rather than exploratory talk. Although meanings relating also to exploratory talk were negotiated, they clearly were not the dominant form. In addition, the study observed that the trajectories of the rules were non identical. Despite connecting dimensions (symmetry, composition, continuity and explicitness) none of the trajectories shared exactly the same features as the others.

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This study evaluates how the advection of precipitation, or wind drift, between the radar volume and ground affects radar measurements of precipitation. Normally precipitation is assumed to fall vertically to the ground from the contributing volume, and thus the radar measurement represents the geographical location immediately below. In this study radar measurements are corrected using hydrometeor trajectories calculated from measured and forecasted winds, and the effect of trajectory-correction on the radar measurements is evaluated. Wind drift statistics for Finland are compiled using sounding data from two weather stations spanning two years. For each sounding, the hydrometeor phase at ground level is estimated and drift distance calculated using different originating level heights. This way the drift statistics are constructed as a function of range from radar and elevation angle. On average, wind drift of 1 km was exceeded at approximately 60 km distance, while drift of 10 km was exceeded at 100 km distance. Trajectories were calculated using model winds in order to produce a trajectory-corrected ground field from radar PPI images. It was found that at the upwind side from the radar the effective measuring area was reduced as some trajectories exited the radar volume scan. In the downwind side areas near the edge of the radar measuring area experience improved precipitation detection. The effect of trajectory-correction is most prominent in instant measurements and diminishes when accumulating over longer time periods. Furthermore, measurements of intensive and small scale precipitation patterns benefit most from wind drift correction. The contribution of wind drift on the uncertainty of estimated Ze (S) - relationship was studied by simulating the effect of different error sources to the uncertainty in the relationship coefficients a and b. The overall uncertainty was assumed to consist of systematic errors of both the radar and the gauge, as well as errors by turbulence at the gauge orifice and by wind drift of precipitation. The focus of the analysis is error associated with wind drift, which was determined by describing the spatial structure of the reflectivity field using spatial autocovariance (or variogram). This spatial structure was then used with calculated drift distances to estimate the variance in radar measurement produced by precipitation drift, relative to the other error sources. It was found that error by wind drift was of similar magnitude with error by turbulence at gauge orifice at all ranges from radar, with systematic errors of the instruments being a minor issue. The correction method presented in the study could be used in radar nowcasting products to improve the estimation of visibility and local precipitation intensities. The method however only considers pure snow, and for operational purposes some improvements are desirable, such as melting layer detection, VPR correction and taking solid state hydrometeor type into account, which would improve the estimation of vertical velocities of the hydrometeors.

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Our present-day understanding of fundamental constituents of matter and their interactions is based on the Standard Model of particle physics, which relies on quantum gauge field theories. On the other hand, the large scale dynamical behaviour of spacetime is understood via the general theory of relativity of Einstein. The merging of these two complementary aspects of nature, quantum and gravity, is one of the greatest goals of modern fundamental physics, the achievement of which would help us understand the short-distance structure of spacetime, thus shedding light on the events in the singular states of general relativity, such as black holes and the Big Bang, where our current models of nature break down. The formulation of quantum field theories in noncommutative spacetime is an attempt to realize the idea of nonlocality at short distances, which our present understanding of these different aspects of Nature suggests, and consequently to find testable hints of the underlying quantum behaviour of spacetime. The formulation of noncommutative theories encounters various unprecedented problems, which derive from their peculiar inherent nonlocality. Arguably the most serious of these is the so-called UV/IR mixing, which makes the derivation of observable predictions especially hard by causing new tedious divergencies, to which our previous well-developed renormalization methods for quantum field theories do not apply. In the thesis I review the basic mathematical concepts of noncommutative spacetime, different formulations of quantum field theories in the context, and the theoretical understanding of UV/IR mixing. In particular, I put forward new results to be published, which show that also the theory of quantum electrodynamics in noncommutative spacetime defined via Seiberg-Witten map suffers from UV/IR mixing. Finally, I review some of the most promising ways to overcome the problem. The final solution remains a challenge for the future.