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Predator-prey interactions are a primary structuring force in aquatic systems. A change in the predator-prey interactions may cause a change in the strength of trophic cascades and even resulting in ecosystem shifts. However, individual properties of predators and prey, as well as environmental conditions, may affect the relative strength of predator-prey interactions. In our studies we observed
The structure, hydration, and dynamics of concentrated DNA-amphiphile complexes were investigated by small-angle X-ray diffraction, sorption calorimetry, and nuclear magnetic resonance. A concentrated, electroneutral, DNA-amphiphile complex can be formed by mixing charge-stoichiometric solutions. The effect is a strong association of DNA with the oppositely charged amphiphile resulting in the form
Through deforestation and conversion of natural ecosystems to croplands and pastures, have humans released vast amounts of carbon (C) dioxide (CO2) into the atmosphere. Roughly one third of the cumulative anthropogenic emissions until today stem from these practices, the remainder being mostly due to fossil fuel combustion. The extra CO2 has caused an increase in global air temperature, and both t
The effect of short time vibration exposure and tourniquet compression on nerve regeneration in rats was studied with special reference to cell activation. One of the hindlimbs was conditioned by either vibration exposure (5 hours / day - 5 consecutive days) or compression (150-300 mmHg for 30-120 minutes), which was followed by a recovery period of 0-7 days. Test crush lesions or a transplantatio
Carbon credits are used as an instrument for climate change mitigation. Each credit represents a reduction in greenhouse gas emissions (GHGs) equivalent of 1 ton of carbon dioxide. Crediting mechanisms and the Clean Development Mechanism (CDM) of the Kyoto Protocol in particular have been important for the international efforts to limit GHG emissions and the engagement of developing countries in m
In an industrial context when the product development cycles are shortened and constraints on technical innovations are high, it is very important to provide a very efficient and effective engineering design activity. In the current engineering design literature, most methodologies are by and large based on the so-called systematic engineering design approach. This approach is characterized by an
This thesis investigates different methods for treating strongly correlated systems, and discusses their respective strengths and weaknesses. Many of the results presented in this thesis come from comparing the different methods and approximations to exact results. Paper I: We studied the real-time dynamics of a trapped fermion gas, as it expands after removal of a trapping potential. Paper II: We
This study explores the role of brain-derived neurotrophic factor (BDNF) for neuronal vulnerability and neurogenesis following cerebral ischemia in the rat. Cerebral ischemia results in selective neuronal cell loss in specific brain regions. We here demonstrate the rank order of vulnerability in two regions affected by global forebrain ischemia, i.e., hippocampus and striatum, by combining specifi
Recent studies indicate that experience dependent mechanisms shape the pain system during the development. In view of that painful stimuli are rare during development it is not clear how this is accomplished. In this thesis it is confirmed, using a battery of sensory deprivations in the rat, that the development of an essential component of the pain system, the nociceptive withdrawal reflexes (NWR
This thesis is concerned with a family of bacterial surface proteins expressed by different strains of the anaerobic Gram-positive, commensal and human pathogen Peptostreptococcus magnus. These proteins have been studied with respect to their role in virulence, function, structure, and evolution. Strains isolated from patients with vaginosis have previously been shown to be associated with express
After transient global cerebral ischemia, selected populations of neurons in the brain will die after a period of 2-3 days, a phenomenon termed delayed neuronal death. This is of clinical importance as delayed neuronal death has been found to occur in humans as well. The mechanism that kills a neuron 2-3 days after the initial insult is unclear, but transcriptional steps have been implicated. The
The sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) are present in human cerebral, meningeal and temporal arteries, as are peptides associated with the sympathetic (neuropeptide Y, NPY) and parasympathetic (vasoactive intestinal peptide, VIP) nervous system. NPY is a vasoconstrictor in cerebral and meningeal arteries and potentiates noradrenaline (NA) as a vasocon
This thesis focuses on the study of thin-film sensor technologies, novel microfabrication technologies, and thin-film technology in general. The work discusses electrochemical sensors and mechanical sensor technologies as well as fabrication strategies for them. Also included are mechano-chemical studies of the vancomycin DAla (Bacteria membrane analogue motif ) binding reaction in different chemica
The relationship between intracellular free calcium ([Ca2+]i) and force in smooth muscle was investigated in receptor-coupled permeabilized preparations and by fluorimetry of the calcium indicator Fura 2 in intact smooth muscle. The time integral of spontaneous [Ca2+]i transients in the intact rat portal vein was decreased by cyanide and, during tonic contraction, cyanide reduced force without cha
Food chain theory is based on consumption; that is, presupposing that the only important interaction between organisms is that they actually meet in an unstructured environment and that one of them is consumed. Recently, studies, including biomanipulation projects, have indicated that trophic interactions are more complex than predicted by food chain theory. In this thesis I examine the role of yo
Systems for on-line monitoring of bioprocesses were developed, consisting of a membrane-based sampling unit, a liquid chromatographic (LC) separation step, and a detector. Two sampling units, a tangential flow filtration (TFF) module and a microdialysis probe, were characterised and evaluated for use in different types of bioprocesses. When using the TFF module, an additional sample clean-up step
The influence of different reaction parameters on enzyme selectivity was investigated. The reaction conditions studied were solvent dependence, water activity and reaction temperature. The improved selectivity was observed as higher synthetic yields in a-chymotrypsin and subtilisin catalyzed peptide synthesis respectively, and as higher enantioselectivity in the asymmetric reduction of ketones cat
