12 resultados para pulp zone
em Helda - Digital Repository of University of Helsinki
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.
Application of Modern NMR Spectroscopic Techniques to Structural Studies of Wood and Pulp Components
Resumo:
The Politics of Pulp Investment and the Brazilian Landless Movement (MST) The paper industry has been moving more heavily to the global South at the beginning of the 21st century. In a number of cases the rural populations of the global South have engaged in increasingly important resistance in their scuffle with the large-scale tree plantation-relying pulp investment model. The resistance had generally not yet managed to slow down Southern industrial tree plantation expansion until 2004. After all, even the MST, perhaps the strongest of the Southern movements, has limited power in comparison to the corporations pushing for plantation expansion. This thesis shows how, even against these odds, depending on the mechanisms of contention and case-specific conflict dynamics, in some cases the movements have managed to slow and even reverse plantation expansion. The thesis is based on extensive field research in the Brazilian countryside. It outlines a new theory of contentious agency promotion, emphasizing its importance in the shaping of corporate resource exploitation. The thesis includes a Qualitative Comparative Analysis of resistance influence on the economic outcomes of all (14) Brazilian large-scale pulp projects between 2004-2008. The central hypothesis of the thesis is that corporate resource exploitation can be slowed down more effectively and likely when the resistance is based on contentious agency. Contentious agency is created by the concatenation of five mutually supporting mechanisms of contention: organizing and politicizing a social movement; heterodox framing of pulp projects; protesting; networking; and embedding whilst maintaining autonomy. The findings suggest that contentious agency can slow or even reverse the expansion of industrial plantations, whereas when contentious agency promotion was inactive, fast or even unchecked plantation expansion was always the outcome. The rule applied to all the assessed 14 pulp conflict cases. The hypothesis gained strong support even in situations where corporate agency promotion was simultaneously active. In previous studies on social movements, there has been a lack of contributions that help us understand the causal mechanisms of contention influencing economic outcomes. The thesis answers to the call by merging a Polanyian analysis of the political economy with the Dynamics of Contention research program and making a case for the impact of contentious agency on capital accumulation. The research concludes that an efficient social movement can utilize mechanisms of contention to promote the potential of activism among its members and influence investment outcomes. Protesting, for example via pioneering land occupations, seemed to be particularly important. Until now, there has been no comprehensive theory on when and how contentious agency can slow down or reverse the expansion of corporate resource exploitation. The original contribution of this research is to provide such a theory, and utilize it to offer an extensive explanation on the conflicts over pulp investment in Brazil, the globalization of the paper industry, and slowing of industrial plantation expansion in the global South.
Resumo:
Lignin is a hydrophobic polymer that is synthesised in the secondary cell walls of all vascular plants. It enables water conduction through the stem, supports the upright growth habit and protects against invading pathogens. In addition, lignin hinders the utilisation of the cellulosic cell walls of plants in pulp and paper industry and as forage. Lignin precursors are synthesised in the cytoplasm through the phenylpropanoid pathway, transported into the cell wall and oxidised by peroxidases or laccases to phenoxy radicals that couple to form the lignin polymer. This study was conducted to characterise the lignin biosynthetic pathway in Norway spruce (Picea abies (L.) Karst.). We focused on the less well-known polymerisation stage, to identify the enzymes and the regulatory mechanisms that are involved. Available data for lignin biosynthesis in gymnosperms is scarce and, for example, the latest improvements in precursor biosynthesis have only been verified in herbaceous plants. Therefore, we also wanted to study in detail the roles of individual gene family members during developmental and stress-induced lignification, using EST sequencing and real-time RT-PCR. We used, as a model, a Norway spruce tissue culture line that produces extracellular lignin into the culture medium, and showed that lignin polymerisation in the tissue culture depends on peroxidase activity. We identified in the culture medium a significant NADH oxidase activity that could generate H2O2 for peroxidases. Two basic culture medium peroxidases were shown to have high affinity to coniferyl alcohol. Conservation of the putative substrate-binding amino acids was observed when the spruce peroxidase sequences were compared with other peroxidases with high affinity to coniferyl alcohol. We also used different peroxidase fractions to produce synthetic in vitro lignins from coniferyl alcohol; however, the linkage pattern of the suspension culture lignin could not be reproduced in vitro with the purified peroxidases, nor with the full complement of culture medium proteins. This emphasised the importance of the precursor radical concentration in the reaction zone, which is controlled by the cells through the secretion of both the lignin precursors and the oxidative enzymes to the apoplast. In addition, we identified basic peroxidases that were reversibly bound to the lignin precipitate. They could be involved, for example, in the oxidation of polymeric lignin, which is required for polymer growth. The dibenzodioxocin substructure was used as a marker for polymer oxidation in the in vitro polymerisation studies, as it is a typical substructure in wood lignin and in the suspension culture lignin. Using immunolocalisation, we found the structure mainly in the S2+S3 layers of the secondary cell walls of Norway spruce tracheids. The structure was primarily formed during the late phases of lignification. Contrary to the earlier assumptions, it appears to be a terminal structure in the lignin macromolecule. Most lignin biosynthetic enzymes are encoded for by several genes, all of which may not participate in lignin biosynthesis. In order to identify the gene family members that are responsible for developmental lignification, ESTs were sequenced from the lignin-forming tissue culture and developing xylem of spruce. Expression of the identified lignin biosynthetic genes was studied using real-time RT-PCR. Candidate genes for developmental lignification were identified by a coordinated, high expression of certain genes within the gene families in all lignin-forming tissues. However, such coordinated expression was not found for peroxidase genes. We also studied stress-induced lignification either during compression wood formation by bending the stems or after Heterobasidion annosum infection. Based on gene expression profiles, stress-induced monolignol biosynthesis appeared similar to the developmental process, and only single PAL and C3H genes were specifically up-regulated by stress. On the contrary, the up-regulated peroxidase genes differed between developmental and stress-induced lignification, indicating specific responses.
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.
Resumo:
Despite the central role of legitimacy in social and organizational life, we know little of the subtle meaning-making processes through which organizational phenomena, such as industrial restructuring, are legitimated in contemporary society. Therefore, this paper examines the discursive legitimation strategies used when making sense of global industrial restructuring in the media. Based on a critical discourse analysis of extensive media coverage of a revolutionary pulp and paper sector merger, we distinguish and analyze five legitimation strategies: (1) normalization, (2) authorization, (3) rationalization, (4) moralization, and (5) narrativization. We argue that while these specific legitimation strategies appear in individual texts, their recurring use in the intertextual totality of the public discussion establishes the core elements of the emerging legitimating discourse.
Resumo:
The present study evaluates the feasibility of undelimbed Scots pine (Pinus sylvestris L.) for integrated production of pulp and energy in a kraft pulp mill from the technical, economic and environmental points of view, focusing on the potential of bundle harvesting. The feasibility of tree sections for pulp production was tested by conducting an industrial wood-handling experiment, laboratory cooking and bleaching trials, using conventional small-diameter Scots pine pulpwood as a reference. These trials showed that undelimbed Scots pine sections can be processed in favourable conditions as a blend with conventional small-diameter pulpwood without reducing the pulp quality. However, fibre losses at various phases of the process may increase when using undelimbed material. In the economic evaluation, both pulp production and wood procurement costs were considered, using the relative wood paying capability of a kraft pulp mill as a determinant. The calculations were made for three Scots pine first-thinning stands with the breast-height diameter of the removal (6 12 cm) as the main distinctive factor. The supply chains included in the comparison were based on cut-to-length harvesting, whole-tree harvesting and bundle harvesting (whole-tree bundling). With the current ratio of pulp and energy prices, the wood paying capability declines with an increase in the proportion of the energy fraction of the raw material. The supply system based on the cut-to-length method was the most efficient option, resulting in the highest residual value at stump in most cases. A decline in the pulp price and an increase in the energy price improved the competitiveness of the whole-tree systems. With short truck transportation distances and low pulp prices, however, the harvesting of loose whole trees can result in higher residual value at stump in small-diameter stands. While savings in transportation costs did not compensate for the high cutting and compaction costs by the second prototype of the bundle harvester, an increase in transportation distances improved its competitiveness. Since harvesting undelimbed assortments increases nutrient export from the site, which can affect soil productivity, the whole-tree alternatives included in the present study cannot be recommended on infertile peatlands and mineral soils. The harvesting of loose whole trees or bundled whole trees implies a reduction in protective logging residues and an increase in site traffic or payloads. These factors increase the risk of soil damage, especially on peat soils with poor bearing capacity. Within the wood procurement parameters which were examined, the CO2 emissions of the supply systems varied from 13 27 kg m3. Compaction of whole trees into bundles reduced emissions from transportation by 30 39%, but these reductions were insufficient to compensate for the increased emissions from cutting and compaction.