Faculty of Science and Technology / Fakulteten för naturvetenskap och teknik

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Space-Safe Transformations and Usage Analysis for Call-by-Need Languages
(2001) Gustavsson, Jörgen
This thesis is concerned with the resource consumption of lazy functional languages. It touches upon two aspects: how to reason about the space-safety of program transformations, and how to apply usage analysis for compiler optimisation. The thesis is a collection of articles. In the rst paper we study the notion of space improvement. We say that that a program fragment is space improved by another if and only if when we replace the former by the latter in any whole program the space behaviour is improved. We will refer to the induced equivalence as space equivalence. We show that many of the extensional equivalences that lazy functional languages enjoy carry over as space equivalences, and we demonstrate that the space improvement theory can be used to show space properties of some interesting small programs. We also show that many extensionally equivalent program fragments are (sometimes surprisingly) not space equivalent by giving examples of whole programs where the asymptotic space behaviour changes if one replaces a program fragment by the another extensionally equivalent one. An example of a transformation that is not a space equivalence in general is the inlining of function calls, i.e., replacing a function call with a copy of the body of the function with the arguments substituted for the formal parameters. In the second paper of thesis we study a class of automatic methods called usage analyses which can infer that an argument to a function is used at most once, and show that usage analyses can be used to guarantee the work and space safety of inlining. Another application of usage analysis is compiler optimisation. In particular usage analysis can be used to avoid unnecessary closure updates. In the third paper of the thesis we present a usage analysis for this purpose which also provides additional information which can be used to optimise the bookkeeping of updates by avoiding unnecessary update marker checks. In the fourth paper of the thesis we present a context sensitive usage analysis based on bounded usage polymorphic types. To implement the analysis e ciently we introduce a new form of constraint and in the fth paper we show how the new form of constraints can be solved. The techniques can be applied not only to usage analysis but also to similar analyses. As an example of such, we present a flow analysis with flow subtyping, flow polymorphism and flow-polymorphic recursion, and show how it can be implemented in O(n3) time where n is the size of the explicitly typed program.
August Holmbergs byggnadslära
(Nordiska museets förlag, 2006) Holmberg, August; Palmqvist, Lena; Sjömar, Peter; Wall, Maria; Institutionen för Kulturvård/Hantverksskolan Dacapo vid Göteborgs universitet; Länsstyrelserna och länsmuseerna i Kronobergs län, Hallands län, Blekinge län och Region Skåne
Kunskapen om den folkliga träbyggnadskonsten som traderades från en generation till nästa återfinner vi inte i byggnadsläror och handböcker. Den har följt timmermannen och hantverkaren. Men i Nordiska museets arkiv finns ett stort uppteckningsmaterial från 1920-talet och framåt där människor runt om i landet delger oss sina kunskaper, erfarenheter och värderingar. Timmermannen och byggmästaren August Holmberg från Blekinge började svara på Nordiska museets frågelistor i början av 1930-talet. Han har bidragit med drygt 140 utförliga berättelser som har visat sig vara mycket användbara. En nutida läsare förstår hantverkets olika arbetsmoment och återfår kunskaper som gått förlorade. I samarbete med DaCapo hantverksskola i Mariestad/Göteborgs universitet, byggnadsantikvarier och länsantikvarier i södra och västra Sverige har Nordiska museet sammanställt textmaterialet med kommentarer och illustrationer. Det presenteras nu i August Holmbergs byggnadslära.
Allometry and ecomorphology of Scandinavian raptors
(2006) Florén, Per; Göteborgs universitet, Zoologiska institutionen
Ända sedan Charles Darwin observerade de berömda finkarna på Galapagosöarna har zoologer arbetat med att försöka förstå hur olika arters form och funktion (functional morphology) kan förstås i ljuset av deras livsstil och livsmiljö (ecology). Genom att använda den allometriska ekvationen kan det genomsnittliga sambandet mellan generell kroppsstorlek och storlek på en viss karaktär, t.ex. längden eller diametern på överarmsbenet humerus beräknas. Detta generella samband, som beskriver hur en viss karaktär förändras med ökad kroppsmassa hos ett antal arter, kan också säga en del om vilka krafter som verkar på just den kroppsdelen. Detta är ämnet för artikel I. I andra artikeln används de allometriska sambanden för att studera skillnaderna mellan hanar och honor för ett antal skandinaviska rovfåglar. Resultatet visar att honan i så gott som samtliga fall har kortare skelettelement i både vinge och ben jämfört med vad som skulle förväntas med tanke på hennes vikt. Detta stärker hypotesen att behovet av en större bål är en viktig faktor bakom honans större storlek. I tredje artikeln jämförs respektive art och kön med den generella linjen och avvikelser från denna linje ställs mot respektive arts specifika livsmiljö och livsstil. Det visas bland annat att fåglar som glidflyger mycket har längre överarmsben (humerus) och mindre yta på bröstbenskammen (carina sterni) än genomsnittet medan aktiva flygare har större yta på carina sterni och kortare vingben. Det konstateras också att fåglar som slår sitt byte har kortare och tjockare tarsometatarsus och tibiotarsus i benen medan de som griper efter sitt byte har längre och smalare. Den i detta samanhang lite udda bivråken, som gräver efter byte har, som förväntat, avsevärt kraftigare tarsometatarsus än genomsnittet.
The intestinal epithelium of salmonids : transepithelial transport, barrier function and bacterial interactions
(2006) Jutfelt, Fredrik
The salmonid intestinal epithelium is important for growth and health of the fish. The epithelium is exposed to a multitude of internal and external factors that can influence its function. During the parr-smolt transformation and subsequent seawater transfer, the epithelium adapts for an osmoregulatory role and the fish starts drinking seawater (SW). Endocrine signals increases the intestinal water uptake partly through an up-regulation of Na+,K+-ATPase activity. It is shown that the epithelial paracellular permeability decrease concurrent with the increase in water transport, suggesting that water flow is directed from a paracellular to a more transcellular route. The rational for this could be the increase in epithelial exposure to the environment at SW entrance. Tightening the paracellular route could be a mechanism to reduce paracellular transfer of harmful substances and pathogens. A major salmonid pathogen is the bacterium Aeromonas salmonicida, which cause losses in both aquaculture and in wild populations. It is not known, however, by which route the A. salmonicida enters the fish. A. salmonicida has been positively demonstrated in the intestinal lumen but it has been controversial whether or not the bacteria cross the epithelial barriers. It is demonstrated that A. salmonicida can translocate across the intestinal barrier, indicating the intestine as a functional route for bacterial infection in salmonids. It is concluded that A. salmonicida employs many virulence mechanisms, such as exotoxins, endotoxin and cell bound factors, to disrupts epithelial morphology and function and promote translocation. During the later phases of parr-smolt transformation the epithelial barrier integrity decreased and translocation of pathogens increased. The increased disease susceptibility during this life stage could thus partly be caused by a decreased barrier function. Vegetable lipids are used as replacement for fish oil in salmonid aquaculture, but there are concerns about how the new diets affect the intestinal epithelium. The epithelial functions presently investigated indicate a slight increase in permeability, supporting earlier histological reports of epithelial disruptions but not to the same extent. Nutrient uptake and barrier function during the parr-smolt transformation was significantly improved by a vegetable lipid-containing diet, indicating that this inclusion may be beneficial in the freshwater (FW) stage. The fatty acid profile of the natural diet for salmonids in FW is more similar to a blend of vegetable oils than to the profile of marine feed ingredients, routinely used in salmonid aquaculture. This may be the rationale for the positive effects. Salmon fed sunflower oil, however, showed long term elevation of plasma cortisol levels indicating a chronic stress. As chronic stress is known to depress immune function, specific vegetable lipids potentially stressful to the fish may also affect their health and welfare. Thus, while vegetable lipids at certain life stages are feasible substitutes for fish oil, possible long term stress effects by vegetable oils should be considered. In conclusion, the salmonid intestinal epithelium is a sensitive and dynamic tissue which is affected by external factors, such as pathogen bacteria, environment and diet, but which also can be endogenously regulated to compensate for this disturbance.
Disruptive technology : effects of technology regulation on democracy
(2006) Klang, Mathias
This work develops the thesis that there is a strong relationship between the regulation of disruptive technology and the Internet-based participatory democracy. In other words, attempts to regulate disruptive technology have an impact upon the citizen’s participation in democracy. This work will show what this relationship is and its effects on democratic participation. Taking its starting point from the recent theoretical developments in regulation, disruptive technology and role of ICT in participatory democracy, this work is the application of theoretical discussions on the field of the Internet-based participatory democracy. These theoretical discussions are used in the empirical exploration of six areas: virus writing and dissemination, civil disobedience in online environments, privacy and the role of spyware, the re-interpretation of property in online environments, software as infrastructure and finally state censorship of online information. The purpose of these studies is to explore the effects of these social and technical innovations upon the core democratic values of Participation, Communication, Integrity, Property, Access and Autonomy. The overall research question for this thesis is therefore: How do attempts to regulate disruptive technology affect Internetbased participatory democracy? The specific contribution of this thesis is the development of extended understanding of the way in which we regulate disruptive technology. This understanding helps us to better regulate that which is new and threatens that which is established. Additionally, the extended understanding in this field can then be applied to all domains where regulation of technology may occur. This thesis contributes towards a richer understanding in the research areas of e-democracy, technology regulation and disruptive technology.
Imaging Optodes
(2006) Strömberg, Niklas 1974-
Heterogeneous IT Innovation. Developing Industrial Architectural Knowledge
(2007) Andersson, Magnus
Multiple information technologies are converging. Crucial to organizations’ relentless struggle to remain competitive, IT innovation processes must now increasingly take into consideration a multitude of stationary, mobile, and even embedded information technologies and their associated use contexts. In assembling such ubiquitous computing environments, multiple organizations with diverging interests and capabilities are involved. Indeed, heterogeneous component technologies are frequently associated with independent markets lacking a dominant actor knowledgeable about more than fragments of the combined capabilities present. A resulting lack of architectural knowledge poses a challenge to organizations attempting to assemble innovative computing environments spanning these boundaries. In this thesis, heterogeneous IT innovation processes are conceptualized as dependent on dispersed component technologies and associated competencies bound together by boundary-spanning architectural knowledge. This perspective is formalized as a research model assessed over a five-year action research project in the Swedish transport industry. The research project involved an industry network of independent technology vendors and user organizations experiencing a mobile-stationary divide in attempts to assemble ubiquitous computing environments. Seeking to understand the role and nature of architectural knowledge in heterogeneous IT innovation processes this thesis contributes implications for both research and strategy. First, architectural knowledge in heterogeneous IT innovation is found to rely on technology capability awareness, use context sensitivity, and business model understanding. However, in order to be successfully enacted in practice, the emergence of boundary-spanning competence is crucial. It is imperative to collectively define mutual boundaries between components of an architecture with respect to technology capabilities, use contexts, and business models. Through this process, architectural knowledge emerges as actors gain an increased capability to appreciate the conditions present in other components. This creates a crucial foundation for boundary spanning innovation. However, such boundary definitions must reflect a viable common denominator. Any resulting formalized architecture should not pose an immediate threat to perceived core markets of any involved component IT base. The need for open boundaryspanning component capabilities and requirements of innovation leeway for individual firms within their core IT base pose a balancing challenge. This can be achieved by black-boxing disputed technology capabilities of the component IT bases, acknowledging the innovation prerogative of organizations within that particular component market.
Medeltida tak : bevarade takkonstruktioner i svenska medeltidskyrkor : Del 1: Rapport om kunskapsläget 2006
(Göteborgs universitet. Institutionen för kulturvård i Mariestad, 2007) Linscott, Kristina
Introduced marine macroalgae and habitat modifiers : their ecological role and significant attributes
(2007) Nyberg, Cecilia D.
Invasive, non-indigenous species (NIS) have become an increasing problem worldwide, with impacts on the diversity and ecosystem functioning of native communities. Marine invasive NIS also have a negative economical impact through increased abundance of toxic species, fouling of man-made underwater structures, and reduced recreational values of beaches. Only a small proportion of the NIS becomes invasive (i.e., having a negative ecological and/or economical impact), but once a species has been established much effort and resources are needed to remove it. In the present thesis I discuss possible factors determining the success of macroalgal introductions and their impacts. A species of special concern in this thesis is the non-indigenous marine red alga Gracilaria vermiculophylla (Ohmi) Papenfuss, seen for the first time in the archipelago of Göteborg, Sweden, in the summer of 2003. Firstly, I highlight some positive and negative impacts caused by NIS as habitat modifiers. Secondly, I describe, by quantitative ranking, whether there are any common patterns of species traits increasing the likelihood of macroalgal NIS, introduced into a new area, becoming established and spread. In general, introduced and invasive species were ranked more hazardous than the native and non-invasive species introduced in Europe. Applying the quantitative species traits ranking on G. vermiculophylla rendered it among the most invasive red algae in Europe. Thirdly, I show the ability of G. vermiculophylla to withstand an emerged situation of more than five months, e.g. simulating transportation in a dredger or among fishing nets. The results indicate that G. vermiculophylla can easily survive long transportation in darkness such as in a ballast tank, and without being submerged in water. It also survived salinities down to 2 in a laboratory experiment, indicating that this species can survive in the innermost parts of the Baltic Sea (the Bothnian Bay). With the help of an event tree I illustrate the potential impact an establishment of G. vermiculophylla could have in the Baltic Sea. Fourthly, I show the distribution pattern within 150 km of the Swedish west coast in two years time for G. vermiculophylla. Furthermore, I describe the community associated with this species collected from Sweden, Denmark and the United States. In total, nearly 100 different taxa in twelve phyla were found associated with G. vermiculophylla. Finally, the impact of G. vermiculophylla on the native eelgrass, Zostera marina, was assessed using a modelling approach. The model output showed a negative effect on Z. marina already at low densities of G. vermiculophylla. This thesis contributes to a wider understanding of macroalgal introductions in general and of the ecology and ecophysiology of the invasive red alga G. vermiculophylla in particular. Such knowledge is important for management and stresses the importance of monitoring the Swedish coastline for early detection of NIS.
Klimatvariationer och påverkan i Östersjöregionen
(2007-11-20T15:27:26Z) Omstedt, Anders
Isens uppbyggnad och känslighet för förändring
(2007-11-21T12:15:56Z) Omstedt, Anders
Oxidative Damage in Fish Used as Biomarkers in Field and Laboratory Studies
(2008) Carney Almroth, Bethanie
Many toxic xenobiotics entering into the aquatic environment exert their effects through redox cycling. Oxidative stress, incorporating both antioxidant defences as well as oxidative damage, is a common effect in organisms exposed to xenobiotics in their environment. The studies included in this dissertation evaluate the effects of different types of environmental pollution on oxidative stress biomarkers in teleost fishes. Effects of aging, alone or in combination with oxidative stress, on protein carbonylation were also addressed. Antioxidant enzyme activities were measured in rainbow trout (Oncorhynchus mykiss) caged in a river polluted by sewage treatment plant (STP) effluent as well as highly contaminated sediment, and in corkwing wrasse (Symphodus melops) collected at heavy metal contaminated and PAH contaminated sites. Antioxidant enzymes showed very few changes in these fish. Glutathione levels were affected by STP effluent exposure in rainbow trout and by PAH exposure in corkwing wrasse. Protein carbonylation was elevated in plasma of the corkwing wrasse captured at the heavy metal site and in plasma of rainbow trout caged near the STP effluent. Lipid peroxidation was elevated in the livers of these rainbow trout. Oxidative damage biomarkers were also measured in eelpout (Zoarces viviparus) captured in a polluted harbor, before, during and after a dredging campaign, as well as following an oil spill. Protein carbonyl levels in livers of eelpout were affected by exposure to pollution in the harbor, though this was measured both as increases and as decreases, indicating a complicated relationship between prooxidant exposure and protein carbonyl accumulation. Lipid peroxidation in eelpout was unaffected by pollutant exposure. Western blot analyses of protein carbonylation in corkwing wrasse exposed to heavy metals and in rainbow trout exposed to paraquat (PQ) suggest that albumin may be the plasma protein most likely to undergo carbonylation in these fish. Brown trout (Salmo trutta) were used in a laboratory study to investigate the effects of aging on oxidative stress parameters, i.e. protein carbonylation, 20S proteosome activity and glutathione levels. All parameters were affected by aging, as was the response to PQ exposure, where 1 year old fish were more sensitive than 0+ fish. To conclude, the results presented here indicate that antioxidant enzymes may not provide a good biomarker of exposure to xenobiotics in the field. However, oxidative damage products, i.e. protein carbonyls and lipid peroxidation, seem to be useful as biomarkers. Care should be taken to consider age of the exposed individuals. Oxidative stress is a complex phenomenon to measure in the field. Antioxidant enzyme activities may be altered after an acute exposure and then return to normal levels but damage products can persist even after the initial stress has stabilized.
Relationships between nomenclature, phylogenetics and systematics
(2008-09-01T11:58:15Z) Bertrand, Yann
Systematists have become increasingly aware of the limits imposed by the current system of nomenclature for accurately representing evolutionary relationships and managing efficiently names associated with clades. In reaction, a new system of nomenclature, the PhyloCode is being developed that fully recognizes the historical nature of taxonomy and the importance of the cladistics revolution. As a consequence, questions emerge about the new historical entities of systematics, questions that can be apprehended through the lens of epistemology, philosophy of language and metaphysics. What is the ontological nature of entities that lack any other essential features besides spatiotemporal properties? How to depart from the fixed realm of immutable and transcendental essence into a worldview wherein all biological entities are characterized by their temporality and materiality? What are the consequences of nomenclatural decisions on other sectors of biology? With the ever growing sequencing capacity and tree reconstructing abilities, our conceptualization of phylogenetic relationships is changing at an unprecedented pace. Then it begs the question, what prevents communication break down when the references of clades’ names are changing almost on a daily basis. These are some of the fundamental issues I am tackling in the present work. Addressing the ontological issue, I argue that species and clades are best perceived as mereological sums of individuals, which means that each biological individual is the unique individual composed of all its less inclusive individuals and nothing more. I propose to separate the meanings of “clade” and “monophyletic group”. I suggest to use “monophyletic” for an epithet referring to a defining property of a set (a natural kind) and “clade” for a noun which corresponds to a historical entity (an individual) resulting from evolutionary process. I present the idea that a phyloname is not attached to a single clade but to a natural kind containing as members the clades that would be selected in counterfactual phylogenies. The defining properties of this natural kind are provided by the phylogenetic definition. Finally I stress that taxonomists are also driven by the will to narrate the same sort of history, when they adjust the reference of names in light of new phylogenetic data, which leads me to submit that taxa can also be perceived as narratives.
Studies on the gamma radiation environment in Sweden with special reference to 137Cs
(2008-09-05T08:29:06Z) Almgren, Sara
Gamma radiation in the environment today mainly originates from naturally occurring radionuclides, but anthropogenic radionuclides, such as 137Cs, contribute in some areas. In order to assess population exposure in case of fallout from nuclear weapons (NWF) or accidents, knowledge and monitoring of external gamma radiation and radionuclide concentrations in the environment is important. For this purpose 34 sampling sites were established in western Sweden and repeated soil sampling, field gamma spectrometry (in situ measurements), and dose rate measurements were performed. The variations in the activities between the different sampling occasions were found to be quite large. The naturally occurring radionuclides were the main source of outdoor dose rates. The uranium and thorium decay series contributed about equally to the total dose while the contribution from 40K was somewhat higher. The dose rates were mainly correlated to the ground cover, with higher levels on asphalt and cobble stones than on grass. The large scale deposition densities from NWF and the Chernobyl accident could be relatively well estimated by a model including the amount of precipitation and measured deposition at few reference sites. The deposition density from nuclear weapons tests in Sweden between 1962 and 1966 was found to be 1.42-2.70 kBq/m2 and the deposition density from Chernobyl in western Sweden ranged between 0.82-2.61 kBq/m2. The vertical migration of 137Cs was studied at the sampling sites in western Sweden and a solution to the convection–diffusion equation (CDE) was fitted to depth profiles. The vertical migration of 137Cs was found to be very slow and diffusive transport was dominant at most locations. The apparent convection velocity and diffusion coefficient were found to be 0–0.35 cm/year and 0.06–2.63 cm2/year, respectively. The average depth of the maximum activity was 5.4±2.2 cm. The fitted depth distributions for each location were used to correct in situ measurements and the results agreed relatively well with the 137Cs inventories in soil samples. A widespread deposition of radionuclides was caused by the Chernobyl accident and parts of Sweden were highly affected. Today, approximately 20 years since the latest deposition, 137Cs can still be measured in the environment and contributes to additional doses to people. However, today people generally spend much time in their dwellings, and therefore, the radiation environment indoors is more important for the personal exposure. Dwelling and personal dose rate measurements in western Sweden (means: 0.099±0.035 µSv/h and 0.094±0.017 µSv/h, respectively) showed that concrete dwellings yield higher dose rates than those of wood. Measurements in a region with a high 137Cs deposition (Hille in eastern Sweden) showed somewhat higher dose rates in wooden dwellings than in western Sweden (0.033 µSv/h and 0.025 µSv/h higher, respectively). The additional contribution from the Chernobyl 137Cs fallout in Hille was estimated to be about 0.2 mSv/year.
The evolution of flat periwinkles Littorina fabalis and L. obtusata emhasizing mitochondrial introgression and restricted recombination
(2008-09-12T11:16:50Z) Kemppainen, Petri
The evolution of species takes in general very long time and different mechanisms are likely to operate during the various stages of this process. Accordingly speciation should be studied at different levels of species divergence. In this thesis I have studied ecological and genetical differentiation between two ecotypes of Littorina fabalis as well as between L. fabalis and L. obtusata - two closely related, directly developing, marine, intertidal gastropods. In L. fabalis size is about 25% larger in moderately exposed habitats compared to sheltered habitats and in this thesis I present data showing that this genetically inherited size different is maintained by an interaction of several selective forces, including life history optimisation, size selective crab predation, fucoid algae functioning as refuges from crab predation and wave-induced dislodgement. The two ecotypes of L. fabalis differ also in the protein arginine kinase (Ark) and a Randomly Amplified Polymorphic DNA (RAPD) locus and this linkage disequilibrium persists in locations where both ecotypes are present suggesting that recombination is strongly suppressed between Ark, the RAPD locus and one or several loci influencing size. Chromosomal rearrangement, in particular inversions are very effective in restricting recombination and if locally adapted alleles in at least two loci on the same chromosome occur in heterogeneous environments, an inversion may immediately protect these from being mixed up with alleles (introduced by migration) that are locally adapted for other microhabitats. This model predicts that differential selection on these alleles exist before an inversion appears and I have tested this by sequencing an intron of Ark. The SS-ecotype was nearly fixed for one haplotype while the diversity among LM-ecotypes was much higher supporting a scenario where a recently derived inversion (or other kind of chromosomal rearrangement) restricts recombination between Ark and one or several loci that influence size. In this thesis a novel method used for the sequencing of the Ark intron that does not require the cloning of each sample individually (which is both time consuming and expensive) is also presented. Littorina fabalis and L. obtusata are considered as well defined species with clear differences in ecology, morphology and nuclear DNA (allozymes) and with microsatellites I could show that hybridisation between these species has not been occurring at least during the last 10,000 years (they are easily identified in the field by both size and coloration). Despite this they show no consistent differences in the mitochondrial cyt-b gene, which could either be due to incomplete lineage sorting or introgression. The idea that mitochondrial DNA can be used as a barcode in species identification is attractive but has in recent years gained criticism because the nature of the mitochondrial molecule makes it specifically prone for introgression between species. Locally restricted mitochondrial introgressions are common among closely related species but the flat periwinkle case study in this thesis clearly shows that a lack of mitochondrial divergence can also exist throughout the whole distribution range for a geographically wide spread species (L. fabalis and L. obtusata occur sympatrically from Spain to Iceland and the White Sea, Russia)
When the Rubber Meets the Road -Ecotoxicological Hazard and Risk Assessment of Tire Wear Particles
(2008-09-18T08:22:32Z) Wik, Anna
Large amounts of rubber particles are dispersed into the environment due to tire wear. The rubber contains a wide range of chemicals, including several of environmental concern. The purpose of this thesis, which is based on six papers [I–VI], was to assess the ecotoxicological hazard and risk associated with tire wear particles, with a main focus on the aquatic environment. A method was developed that enables rapid screening of the toxicity of tire particle leachates [I]. Acute and chronic toxicity of tire particle leachates to aquatic organisms was found to occur at concentrations ranging from 10 to >10 000 mg/l [I–IV]. The toxicity of wear material from different tires was found to vary with more than two orders of magnitude [I¬¬–II]. Toxicity identification studies (TIEs) identified organic compounds [II–IV] and Zn [IV] as the toxic components of tire particle leachates. Zn was also identified as the contaminant in the sediments of detention ponds, receiving road runoff, posing the highest threat to surrounding water bodies, and tire wear particles are a main source of this Zn contamination [V]. The Predicted No Effect Concentration (PNEC) was calculated, according to European chemical risk assessment guidelines, based on long term tests with the cladoceran Ceriodaphnia dubia and the microalgae Pseudokirchneriella subcapitata [IV]. The PNECs are 3.9 mg/l and 0.3 g/kg dw for water and sediments, respectively [VI]. A literature review of markers for tire wear in the environment showed tire particles to be present in surface waters, soils/sediments, air, and biota [VI]. Most of the tire particles are deposited on or close to the road surface and are then further transported by runoff water to receiving waters and sediments. The maximum Predicted Environmental Concentrations (PECs) of tire wear particles in surface water range from 0.03 to 56 mg/l, and the maximum PECs in sediments range from 0.3 to 155 g/kg dw [VI]. Thus, the upper range for PEC/PNEC ratios exceeds unity in both surface waters and sediments, meaning that tire wear particles constitute potential risks for aquatic organisms. The risk for the terrestrial environment is suggested to be restricted to the immediate road surroundings, and it is suggested that more research should be directed towards evaluating the health aspects associated with the inhalation of airborne tire particles [VI]. To conclude, the work presented in this thesis has shown that the contamination from tire wear particles needs to be reduced in order to protect receiving surface waters. This could be achieved by developing tires with more environmentally friendly constituents. Road runoff detention ponds are primary recipients of tire wear particles, and, therefore it is important that construction, environmental monitoring and management of such ponds receive increased attention.
High-resolution phenotypic profiling of a eukaryotic ribosome
(2008-09-19T06:27:32Z) Esguerra, Jonathan LS
All living cells contain ribosomes, complex macromolecular assemblies of ribonucleic acid (RNA) and proteins, responsible for synthesizing polypeptides in a process called translation. High-resolution three-dimensional ribosomal structures coupled with biochemical studies have paved the way in understanding the various mechanistic events during protein synthesis. However, a systematic study dealing with the individual components and features of the ribosome is lacking. Specifically, the functional connection of each ribosomal protein and individual ribosomal RNA (rRNA) modification to cellular processes outside the domains of translation has not been fully explored. Using the yeast Saccharomyces cerevisiae as a model eukaryotic organism, I investigated the contribution of individual ribosomal proteins and rRNA modifications to cellular fitness during growth in optimal and stress environments. I performed high-resolution phenotypic profiling on isogenic yeast strains with individual deletions in 110 cytoplasmic ribosomal protein (cRP) genes, 67 mitochondrial ribosomal protein (mRP) genes and 65 small nucleolar RNA genes (snoRNA). SnoRNAs facilitate site-specific rRNA modifications hence, their removal results to the absence of modification on the corresponding target site on the rRNA. I utilized a high-throughput phenotyping approach wherein the growth behaviors of individual deletion mutants were monitored in liquid micro-culture environmental arrays. Three physiologically-relevant growth variables, growth lag, growth rate and growth efficiency, extracted from high-resolution growth curves allowed for the precise quantification of marginal phenotypic consequences of deletions not detectable by standard, more qualitative approaches. Detailed analysis of growth dynamics in a plethora of perturbed environments revealed a surprising range of hitherto unknown phenotypic diversity in the ribosome ranging from extreme sensitivity to extreme resistance in essentially every tested environment. Identification of dominant trends in the chemogenetic landscape allowed for the separation of the deletion mutants into distinct stress sub clusters, resolving the phenotypes into effects on different aspects of cellular physiology. Notable was the identification of phenotypes in all the sets of deletion mutants (cRP, mRP and snoRNA knockouts) exhibiting varying degrees of sensitivity to alternative carbon sources, strongly linking many of them to respiratory functions. The mix of cRP, mRP and snoRNA deletion mutants in some stress-specific sub cluster, such as the oxidative stress sub cluster, also indicated greater than expected functional overlap. The functional specialization within the yeast ribosome revealed a new level of translational complexity suggesting the existence of compositionally distinct ribosomes which are customized according to environmental cues. The direct participation of some ribosomal protein components and snoRNAs in cellular stress response was also envisioned. The implication of these hypotheses is significant not only in the basic understanding of the inner workings of the ribosome but also in providing new avenues in explaining the underlying mechanisms in the growing number of human diseases linked to defective components of the translational machinery.
Lidar Studies of Tropospheric Aerosols and Clouds
(2008-09-22T06:42:03Z) Olofson, Frans
An improved description of aerosol and cloud processes is a prerequisite for successful prediction of future climate change. The climate on Earth is controlled by the radiation budget, i.e. the relation between the radiation going into and out from the atmosphere. Aerosols are said to have two main effects on the climate. The direct effect refers to cooling and warming by reflection of incoming solar radiation and absorption of outgoing thermal radiation, respectively. The indirect effect concerns the ability of aerosols to influence cloud formation and to change the optical and physical properties of clouds. Clouds normally occupy at least 50% of the sky on a global scale. The presence of clouds greatly increases the portion of the solar radiation reflected back to space, but on the other hand clouds may absorb outgoing thermal radiation from Earth and in the same way as a greenhouse gas partly counteract the cooling effect. The Intergovernmental Panel on Climate Change has identified clouds as the key uncertainty in predicting climate change: “The single largest uncertainty in determining the climate sensitivity to either natural or anthropogenic changes is clouds and their effects on radiation and their role in the hydrological cycle”. The overall aim of the present thesis is to contribute to an increased understanding of climate effects as well as air quality issues related to aerosol and clouds. The radiative properties of clouds are determined by the microphysics, i.e. refractive index, shape, and size distribution. In this thesis the construction and development of a bistatic lidar set-up for polarisation measurements throughout the troposphere is described and the results obtained with this system are presented. From the measurements of optically thin or mildly opaque high latitude clouds substantial depolarisation was observed. Ray tracing calculations for hexagonal ice columns were able to produce all the experimental values if a suitable degree of surface roughness was introduced. The results show that it is important to account for non-spherical shapes for the assessment of the radiative impact of Arctic ice clouds, and that the bistatic lidar technique may provide a useful complementary technique to be used together with existing lidar setups. Lidar measurements were also conducted with the aim to study particulate air pollution in Göteborg. The limited insolation in wintertime sometimes resulted in near neutral boundary layer conditions and inefficient ventilation during the day. Considerable variation in the rate of rising polluted air subsequent to inversion layer break-up was observed, ranging from 200 to 800 m/h. Recently formed particles were observed around midday subsequent to surface layer ventilation. The boundary layer dynamics are concluded to have a strong impact on the properties of the urban aerosol and to a large extent determine the severity of the wintertime urban air pollution episodes to human health.
Proceedings of the 3rd Educators Symposium at MODELS
(2008-09-24T09:30:38Z) Staron, Miroslaw
Proceedings of the 7th Conference on Software Engineering Research and Practice in Sweden
(2008-09-24T09:34:21Z) Arts, Thomas

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