| 1. |
- Fernández C, Sandra
(författare)
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Farewell to peasantry? : (Post)modernising rural Mexico - The case of the ejido peasants in the Isthmus of Tehuantepec
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis deals with a classical issue, that of the fate of the peasantry, in particular the process of the transformation of the peasantry. The aim is to explore whether there is a place for the smallholding peasantry in the future, or if the process of dissolution is inevitable. The discussion of this broad question is approached by first deconstructing the peasantry into economic actors and sociopolitical actors so as to understand their livelihood, actions, thinking and projects, and then by reconstructing the peasantry as we see them in contemporary times in a specific region. First, the relationship between the state and the peasantry is described in a Mexican context, and the peasantry’s responses to state rural development projects in times of liberalisation are identified. The political dimension of the peasantry is then explored. Finally, I present my interpretation of an alternative project for rural modernisation that is emerging among the ejido peasants in the Isthmus of Tehuantepec. The theoretical approach is interdisciplinary and includes political economy, radical human geography and postmodernist perspectives. Concepts of modernity and postmodernity are discussed in connection with the peasants in the Isthmus to highlight the complexity of that social reality with emphasis on the analytical categories of class, ethnicity, gender and sustainability. The theoretical framework is generated from the data constructed through the fieldwork, and both theories and data have been subjected to continuous inquiry. Hence, the methodology used here is based on grounded theory. The thesis places great importance on the empirical material, but claims that theory construction cannot be separated from data since it is an iterative process where the researcher is moving continuously between the conceptual and the empirical world. Theory and the empirical material combine so as to construct a conceptual model that describes and interprets the peasants comprehensively. The methods used are semistructured interviews, in-depth interviews, participant observation and archive studies. The voices of the peasants are interpreted by the author and presented as portraits or quotations, using the procedures and techniques of qualitative research when constructing, coding, analysing and presenting the information. A total of 135 semistructured interviews were undertaking in 1998, 1999, 2000 and 2001 in six ejidos in the Isthmus of Tehuantepec. The concluding remarks outlined in Chapter Seven present three scenarios for the outcome for these ejido peasants where their fate is approached through their own visions, fears and expectations expressed in their own words. The scenarios are not clear-cut. There is no single answer to the central question. Depeasantisation is an unpredictable and complex process and, most of all, it is an issue that should be approached empirically and contextually.
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| 2. |
- Fjellgaard Mikalsen, Ragni
(författare)
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Fighting flameless fires : Initiating and extinguishing self-sustainedsmoldering fires in wood pellets
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Smoldering fires represent domestic, environmental and industrial hazards. This flameless form of combustion is more easily initiated than flaming, and is also more persistent and difficult to extinguish. The growing demand for non-fossil fuels has increased the use of solid biofuels such as biomass. This represents a safety challenge, as biomass self-ignition can cause smoldering fires, flaming fires or explosions.Smoldering and extinguishment in granular biomass was studied experimentally. The set-up consisted of a cylindrical fuel container of steel with thermally insulated side walls. The container was closed at the bottom, open at the top and heated from below by a hot surface. Two types of wood pellets were used as fuel, with 0.75-1.5 kg samples.Logistic regression was used to determine the transition region between non-smoldering and self-sustained smoldering experiments, and to determine the influence of parameters. Duration of external heating was most important for initiation of smoldering. Sample height was also significant, while the type of wood pellet was near-significant and fuel container height was not.The susceptibility of smoldering to changes in air supply was studied. With a small gap at the bottom of the fuel bed, the increased air flow in the same direction as the initial smoldering front (forward air flow) caused a significantly more intense combustion compared to the normal set-up with opposed air flow.Heat extraction from the combustion was studied using a water-cooled copper pipe. Challenges with direct fuel-water contact (fuel swelling, water channeling and runoff) were thus avoided. Smoldering was extinguished in 7 of 15 cases where heat extraction was in the same range as the heat production from combustion. This is the first experimental proof-of-concept of cooling as an extinguishment method for smoldering fires.Marginal differences in heating and cooling separated smoldering from extinguished cases; the fuel bed was at a heating-cooling balance point. Lower cooling levels did not lead to extinguishment, but cooling caused more predictable smoldering, possibly delaying the most intense combustion. Also observed at the balance point were pulsating temperatures; a form of long-lived (hours), macroscopic synchronization not previously observed in smoldering fires.For practical applications, cooling could be feasible for prevention of temperature escalation from self-heating in industrial storage units. This study provides a first step towards improved fuel storage safety for biomass.
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| 3. |
- Lindroth, Karin, 1975-
(författare)
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Maturation of humoral immune responses : Studies on the effects of antigen type, apoptosis and age
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The humoral immune response is dependent on the formation of antibodies. Antibodies are produced by terminally differentiated B cells, plasma cells. Plasma cells are generated either directly from antigen challenged B cells, memory cells or from cells that have undergone the germinal center (GC) reaction. The GC is the main site for class switch, somatic hypermutation and generation of memory cells.Different factors, both internal and external, shape the outcome of the immune response. In this thesis, we have studied a few factors that influence the maturation of the humoral response. We have studied how age affects the response, and we show that responses against thymus dependent antigens (TD) are more affected than responses to thymus independent (TI) antigens, in concordance with the view that the T cell compartment is more affected by age than the B cell compartment. Furthermore, we demonstrate that priming early in life have a big influence on the immune response in the aged individual. Priming with a TI form of the carbohydrate dextran B512 (Dx) induces a reduction of IgG levels in later TD responses against Dx. We have evaluated possible mechanisms for this reduction. The reduction does not seem to be caused by clonal exhaustion or antibody mediated mechanisms. We also showed that the reduced TD response after TI priming can be induced against another molecule than Dx. With the hypothesis that TI antigens induce a plasma cell biased maturation of the responding B cells, we examined the presence of Blimp-1, a master regulator of plasma cell differentiation, in GCs induced by TD and TI antigen. Blimp-1 was found earlier in GCs induced by TI antigen and the staining intensity in these GCs was stronger than in TD antigen induced GCs, indicating that plasma cells might be continuously recruited from these GCs.B cells undergoing the GC reaction are thought to be under a strict selection pressure that removes cells with low affinity for the antigen and also cells that have acquired self-reactivity. We investigated the effect of apoptotic deficiencies on the accumulation of somatic mutations in GC B cells. In mice lacking the death receptor Fas, lpr mice, the frequency of mutations was increased but the pattern of the mutations did not differ from wild type mice. In contrast, mice over-expressing the anti-apoptotic protein Bcl-2, had a lowered frequency of mutations and the mutations introduced had other characteristics.
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