19 resultados para Shear transformation zone

em Helda - Digital Repository of University of Helsinki


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The dissertation analyzes and elaborates upon the changing map of U.S. ethno-racial formation from the vantage point of North American Studies, multi-disciplinary cultural studies, and the criticism of visual culture. The focus is on four contemporary Mexican American (Chicana) women photographers, whose art production is discussed, on the one hand, in the context of the Euro-American history of photographic genres and, on the other hand, in the context of so-called decolonizing cultural and academic discourses produced by Mexican Americans themselves. The manuscript consists of two parts. Part I outlines the theoretical and methodological domain of the study, positioning it in the interstices of American studies, European postmodern criticism, postcolonial feminist theory, and the theories of visual culture, particularly of art photography. In addition, the main issues and paradigms of Chicano Studies (Mexican American ethnic studies) are introduced. Part II consists of seven essays, each of which discusses rather independently a particular photographic work or a series of photographs, formulating and defending arguments about their meaning, position in the history of photographic genres, and their cultural and socio-political significance. The study closes with a discussion about ethno-racial identity formation and the role of Chicana photography therein - in embodying and reproducing new subjectivities, alternative categories of knowledge, and open ended historical narratives. It is argued that, symbolically, the "Wild Zone" of gendered and race-specific knowledge becomes associated with the body of the mother, a recurrent image in Chicana art works under discussion. Embedded in this image, the construction of an alternative notion of a family thus articulates the parameters of a matrifocal ethno-racial community unified by the proliferation of differences rather than by conformities typical of nationalistic ideologies. While focusing on art photography, the study as a whole simultaneously constructs, from a European vantage point, a "thick" description of Mexican American history, identities, communities, cultural practices, and self-representations about which very little is known in Finland.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Olkiluoto Island is situated in the northern Baltic Sea, near the southwestern coast of Finland, and is the proposed location of a spent nuclear fuel repository. This study examined Holocene palaeoseismicity in the Olkiluoto area and in the surrounding sea areas by computer simulations together with acoustic-seismic, sedimentological and dating methods. The most abundant rock type on the island is migmatic mica gneiss, intruded by tonalites, granodiorites and granites. The surrounding Baltic Sea seabed consists of Palaeoproterozoic crystalline bedrock, which is to a great extent covered by younger Mesoproterozoic sedimentary rocks. The area contains several ancient deep-seated fracture zones that divide it into bedrock blocks. The response of bedrock at the Olkiluoto site was modelled considering four future ice-age scenarios. Each scenario produced shear displacements of fractures with different times of occurrence and varying recovery rates. Generally, the larger the maximum ice load, the larger were the permanent shear displacements. For a basic case, the maximum shear displacements were a few centimetres at the proposed nuclear waste repository level, at proximately 500 m b.s.l. High-resolution, low-frequency echo-sounding was used to examine the Holocene submarine sedimentary structures and possible direct and indirect indicators of palaeoseismic activity in the northern Baltic Sea. Echo-sounding profiles of Holocene submarine sediments revealed slides and slumps, normal faults, debris flows and turbidite-type structures. The profiles also showed pockmarks and other structures related to gas or groundwater seepages, which might be related to fracture zone activation. Evidence of postglacial reactivation in the study area was derived from the spatial occurrence of some of the structures, especial the faults and the seepages, in the vicinity of some old bedrock fracture zones. Palaeoseismic event(s) (a single or several events) in the Olkiluoto area were dated and the palaeoenvironment was characterized using palaeomagnetic, biostratigraphical and lithostratigraphical methods, enhancing the reliability of the chronology. Combined lithostratigraphy, biostratigraphy and palaeomagnetic stratigraphy revealed an age estimation of 10 650 to 10 200 cal. years BP for the palaeoseismic event(s). All Holocene sediment faults in the northern Baltic Sea occur at the same stratigraphical level, the age of which is estimated at 10 700 cal. years BP (9500 radiocarbon years BP). Their movement is suggested to have been triggered by palaeoseismic event(s) when the Late Weichselian ice sheet was retreating from the site and bedrock stresses were released along the bedrock fracture zones. Since no younger or repeated traces of seismic events were found, it corroborates the suggestion that the major seismic activity occurred within a short time during and after the last deglaciation. The origin of the gas/groundwater seepages remains unclear. Their reflections in the echo-sounding profiles imply that part of the gas is derived from the organic-bearing Litorina and modern gyttja clays. However, at least some of the gas is derived from the bedrock. Additional information could be gained by pore water analysis from the pockmarks. Information on postglacial fault activation and possible gas and/or fluid discharges under high hydraulic heads has relevance in evaluating the safety assessment of a planned spent nuclear fuel repository in the region.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Ectomycorrhizal formation between the host tree, Pinus sylvestris and fungal symbiont, Suillus bovinus was investigated at the molecular level by isolating genes regulating the organization of the actin cytoskeleton in the fungal partner S. bovinus. An Agrobacterium tumefaciens mediated transformation (ATMT) system was developed for the ectomycorrhizal fungi in order to assign specific functions to the cloned molecules. The developed ATMT system was also used to transform a plant pathogenic fungus, Helminthosporium turcicum, to hygromycin B resistance. Small GTPases Cdc42 and Rac1, the regulators of actin cytoskeleton in eukaryotes were isolated from S. bovinus. Sbcdc42 and Sbrac1, are both expressed in vegetative and in the symbiotic hyphae of S. bovinus . Using IIF microscopy, Cdc42 and actin were co-localized at the tips of vegetative hyphae and were visualized in association with the plasma membrane in swollen cells typical to the symbiotic hyphae. These results suggest that the small GTPases Cdc42 may play a significant role in the polarized growth of S. bovinus hyphae and regulate fungal morphogenesis during ectomycorrhiza formation through reorganization of the actin cytoskeleton. The functional equality of Cdc42 was tested in yeast complementation experiments using a Saccharomyces cerevisiae temperature sensitive mutant, cdc42-1ts. The genomic clone of CDC42 was isolated from S. bovinus genomic DNA via specific primers for Cdc42. The analogous S. cerevisiae cdc42 mutations, dominant active G12V and dominant negative D118A, were generated in the Sbcdc42 gene by in-vitro mutagenesis. The ectomycorrhizal fungi, S. bovinus, P. involutus and H. cylindroporum were transformed using ATMT and phleomycin as a selectable marker. PCR screeing suggested that the T-DNA was inserted in all the three fungal genomes but the fate of integration could not be proved by Southern blot analysis. An alternative Agrobacterium strain, AGL-1 and selection marker, hygromycin was used to transform our model fungus S. bovinus. PCR and Southern analysis suggested an improved efficiency of transformation. All the transformed fungal colonies selected for hygromycin gave positives in PCR and the Southerns showed multiple or single copy T-DNA integrations into the S. bovinus genome. Using the same Agrobacterium strain and the selectable marker, a maize pathogen, H. turcicum was also subjected to ATMT. The H. turcicum transformation data suggested the single copy T-DNA integrations into the genome of the screened transformants that further confirms wider applicability of the ATMT. The plasmids carrying the wild-type (pHGCDC42) and the mutated Sbcdc42 alleles (pHGGV; pHGDA) under Agaricus bisporus gpd promoter were constructed in an A. tumefaciens vector. ATMT was used to transform S. bovinus with the plasmids carrying the wild-type and mutated Sbcdc42 alleles. The isolation of Sbcdc42 and Sbrac1 genes and some other functionally related genes from ectomycorrhizal fungus, S. bovinus will form the basis of future work to resolve the signalling pathway leading to ectomycorrhizal symbiosis. The development of ATMT system will be a valuable tool in analysing the exact function of signalling pathway components in ectomycorrhizal symbiosis or in plant pathogenic interactions. The transformation frequency and broad applicability along with the simplicity of T-DNA integration make Agrobacterium a valuable, new and a powerfull tool for targeted and insertional mutagenesis in these plant associated fungi. The developed ATMT systems should therefore make it possible to generate large number of transformants with tagged genes which could then be screened for their specific roles in symbiosis and pathogenecity, respectively.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This research has been prompted by an interest in the atmospheric processes of hydrogen. The sources and sinks of hydrogen are important to know, particularly if hydrogen becomes more common as a replacement for fossil fuel in combustion. Hydrogen deposition velocities (vd) were estimated by applying chamber measurements, a radon tracer method and a two-dimensional model. These three approaches were compared with each other to discover the factors affecting the soil uptake rate. A static-closed chamber technique was introduced to determine the hydrogen deposition velocity values in an urban park in Helsinki, and at a rural site at Loppi. A three-day chamber campaign to carry out soil uptake estimation was held at a remote site at Pallas in 2007 and 2008. The atmospheric mixing ratio of molecular hydrogen has also been measured by a continuous method in Helsinki in 2007 - 2008 and at Pallas from 2006 onwards. The mean vd values measured in the chamber experiments in Helsinki and Loppi were between 0.0 and 0.7 mm s-1. The ranges of the results with the radon tracer method and the two-dimensional model were 0.13 - 0.93 mm s-1 and 0.12 - 0.61 mm s-1, respectively, in Helsinki. The vd values in the three-day campaign at Pallas were 0.06 - 0.52 mm s-1 (chamber) and 0.18 - 0.52 mm s-1 (radon tracer method and two-dimensional model). At Kumpula, the radon tracer method and the chamber measurements produced higher vd values than the two-dimensional model. The results of all three methods were close to each other between November and April, except for the chamber results from January to March, while the soil was frozen. The hydrogen deposition velocity values of all three methods were compared with one-week cumulative rain sums. Precipitation increases the soil moisture, which decreases the soil uptake rate. The measurements made in snow seasons showed that a thick snow layer also hindered gas diffusion, lowering the vd values. The H2 vd values were compared to the snow depth. A decaying exponential fit was obtained as a result. During a prolonged drought in summer 2006, soil moisture values were lower than in other summer months between 2005 and 2008. Such conditions were prevailing in summer 2006 when high chamber vd values were measured. The mixing ratio of molecular hydrogen has a seasonal variation. The lowest atmospheric mixing ratios were found in the late autumn when high deposition velocity values were still being measured. The carbon monoxide (CO) mixing ratio was also measured. Hydrogen and carbon monoxide are highly correlated in an urban environment, due to the emissions originating from traffic. After correction for the soil deposition of H2, the slope was 0.49±0.07 ppb (H2) / ppb (CO). Using the corrected hydrogen-to-carbon-monoxide ratio, the total hydrogen load emitted by Helsinki traffic in 2007 was 261 t (H2) a-1. Hydrogen, methane and carbon monoxide are connected with each other through the atmospheric methane oxidation process, in which formaldehyde is produced as an important intermediate. The photochemical degradation of formaldehyde produces hydrogen and carbon monoxide as end products. Examination of back-trajectories revealed long-range transportation of carbon monoxide and methane. The trajectories can be grouped by applying cluster and source analysis methods. Thus natural and anthropogenic emission sources can be separated by analyzing trajectory clusters.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The thesis examines urban issues arising from the transformation from state socialism to a market economy. The main topics are residential differentiation, i.e., uneven spatial distribution of social groups across urban residential areas, and the effects of housing policy and town planning on urban development. The case study is development in Tallinn, the capital city of Estonia, in the context of development of Central and Eastern European cities under and after socialism. The main body of the thesis consists of four separately published refereed articles. The research question that brings the articles together is how the residential (socio-spatial) pattern of cities developed during the state socialist period and how and why that pattern has changed since the transformation to a market economy began. The first article reviews the literature on residential differentiation in Budapest, Prague, Tallinn and Warsaw under state socialism from the viewpoint of the role of housing policy in the processes of residential differentiation at various stages of the socialist era. The paper shows how the socialist housing provision system produced socio-occupational residential differentiation directly and indirectly and it describes how the residential patterns of these cities developed. The second article is critical of oversimplified accounts of rapid reorganisation of the overall socio-spatial pattern of post-socialist cities and of claims that residential mobility has had a straightforward role in it. The Tallinn case study, consisting of an analysis of the distribution of socio-economic groups across eight city districts and over four housing types in 1999 as well as examining the role of residential mobility in differentiation during the 1990s, provides contrasting evidence. The third article analyses the role and effects of housing policies in Tallinn s residential differentiation. The focus is on contemporary post-privatisation housing-policy measures and their effects. The article shows that the Estonian housing policies do not even aim to reduce, prevent or slow down the harmful effects of the considerable income disparities that are manifest in housing inequality and residential differentiation. The fourth article examines the development of Tallinn s urban planning system 1991-2004 from the viewpoint of what means it has provided the city with to intervene in urban development and how the city has used these tools. The paper finds that despite some recent progress in planning, its role in guiding where and how the city actually developed has so far been limited. Tallinn s urban development is rather initiated and driven by private agents seeking profit from their investment in land. The thesis includes original empirical research in the three articles that analyse development since socialism. The second article employs quantitative data and methods, primarily index calculation, whereas the third and the fourth ones draw from a survey of policy documents combined with interviews with key informants. Keywords: residential differentiation, housing policy, urban planning, post-socialist transformation, Estonia, Tallinn

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The purpose of this study is to examine how transformation is defining feminist bioethics and to determine the nature of this transformation. Behind the quest for transformation is core feminism and its political implications, namely, that women and other marginalized groups have been given unequal consideration in society and the sciences and that this situation is unacceptable and should be remedied. The goal of the dissertation is to determine how feminist bioethicists integrate the transformation into their respective fields and how they apply the potential of feminism to bioethical theories and practice. On a theoretical level, feminist bioethicists wish to reveal how current ways of knowing are based on inequality. Feminists pay special attention especially to communal and political contexts and to the power relations endorsed by each community. In addition, feminist bioethicists endorse relational ethics, a relational account of the self in which the interconnectedness of persons is important. On the conceptual level, feminist bioethicists work with beliefs, concepts, and practices that give us our world. As an example, I examine how feminist bioethicists have criticized and redefined the concept of autonomy. Feminist bioethicists emphasize relational autonomy, which is based on the conviction that social relationships shape moral identities and values. On the practical level, I discuss stem cell research as a test case for feminist bioethics and its ability to employ its methodologies. Analyzing these perspectives allowed me first, to compare non-feminist and feminist accounts of stem cell ethics and, second, to analyze feminist perspectives on the novel biotechnology. Along with offering a critical evaluation of the stem cell debate, the study shows that sustainable stem cell policies should be grounded on empirical knowledge about how donors perceive stem cell research and the donation process. The study indicates that feminist bioethics should develop the use of empirical bioethics, which takes the nature of ethics seriously: ethical decisions are provisional and open for further consideration. In addition, the study shows that there is another area of development in feminist bioethics: the understanding of (moral) agency. I argue that agency should be understood to mean that actions create desires.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The productivity of a process is related to how effectively input resources are transformed into value for customers. For the needs of manufacturers of physical products there are widely used productivity concepts and measurements instruments. However, in service processes the underlying assumptions of these concepts and models do not hold. For example, manufacturing-based productivity models assume that an altered configuration of input resources in the production process does not lead to quality changes in outputs (the constant-quality assumption). However, in a service context changes in the production resources and productions systems do affect the perceived quality of services. Therefore, using manufacturing-oriented productivity models in service contexts are likely to give managers wrong directions for action. Research into the productivity of services is still scarce, because of the lack of viable models. The purpose of the present article is to analyse the requirements for the development of a productivity concept for service operations. Based on the analysis, a service productivity model is developed. According to this model, service productivity is a function of 1) how effectively input resources into the service (production) process are transformed to outputs in the form of services (internal or cost efficiency), 2) how well the quality of the service process and its outcome is perceived (external or revenue efficiency), and 3) how effectively the capacity of the service process is utilised (capacity efficiency). In addition, directions for developing measurement models for service productivity are discussed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this article I shall argue that understandings of what constitutes narrative, how it functions, and the contexts in which it applies have broadened in line with cultural, social and intellectual trends which have seen a blurring, if not the dissolution, of boundaries between ‘fact’ and ‘fiction’; ‘literary’ and ‘non-literary’ narrative spaces; history and story; concepts of time and space, text and image, teller and tale, representation and reality.To illustrate some of the ways in which the concept of narrative has travelled across disciplinary and generic boundaries, I shall look at The Art of Travel (de Botton 2003), with a view to demonstrating how the blending of genres works to produce a narrative that is at once personal and philosophical; visual and verbal; didactic and poetic. I shall show that such a text constitutes a site of interrogation of concepts of narrative, even as it depends on the reader’s ability to narrativize experience.