| 1. |
- Jensen, Anna M
(författare)
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Effects of facilitation and competition on oak seedlings : using shrubs as nurse-plants to facilitate growth and reduce browsing from large herbivores
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plant–plant interactions have been indicated as a potential means to facilitate oak seedling establishment and reduce herbivory when restoring oak forests. The aim of this thesis was to investigate mechanisms and outcomes of competitive and indirectly facilitative interactions between oak (Quercus robur and Q. petraea) seedlings and neighboring plants, primarily shrubs. The associational resistance of planted oak seedlings to larger herbivores provided by naturally occurring shrubs was tested in ten temperate broadleaved forests across southern Sweden. The results showed that shrubs reduced ungulate browsing frequency and intensity by concealing the oak seedlings and by sharing enemies (i.e. ungulate herbivores) with surrounding and more preferred shrub species, thus providing numeric dilution and associational plant refuges. The occurrence of naturally regenerated oak seedlings, five years after a conservation-oriented thinning, was negatively influenced by the presence of tall ground vegetation and positively influenced by high soil moisture. For oak seedlings planted in an open field, shrubs indirectly facilitated biomass accumulation by reducing competition from herbaceous vegetation. However, shrubs became net competitors three years after planting. The oak seedling response, in terms of biomass accumulation, transpiration and photosynthesis, to competition from shrubs was proportional to resource availability. Aboveground competition for light had a greater effect on oak seedling growth than belowground competition. Nevertheless, oak seedlings were able to produce a second shoot flush, over-topping the shrub canopy. This periodic flushing enabled light-acclimation in a stratified light environment. In conclusion, management of shrubs has the potential to reduce browsing and herbaceous competitors during oak regeneration, particularly during the first years after planting. Although shrubs alone may not replace fences as an effective means of reducing browsing on oaks, they provide a complement to improve the growth of seedlings during the early stages of establishment.
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| 2. |
- Lungu-Mitea, Sebastian
(författare)
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Toxicity pathways in zebrafish cell lines : an ecotoxicological perspective on "toxicity testing in the 21st century"
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Standard toxicological in vivo testing has been challenged as the procedures are time-consuming, expensive, and require a large number of animals; given the number of problematic chemicals. Novel toxicological frameworks, such as "toxicity testing in the 21st century", proposed the use of "new approach methods" (in vitro and in silico techniques), that can be applied in high-throughput setups and would allow for the testing of a large number of compounds. However, such new approach methods need to be designed and evaluated first. Especially within ecotoxicology, the coverage of species-specific bioanalytical tools, e.g. for fish, is rather scarce. Currently, mainly in vitro assays of mammalian and bacterial origin are used. This thesis outlines how to design and scrutinise fish transient reporter gene assays. We have established transient reporter gene assays in permanent zebrafish fibroblasts and hepatocytes of the oxidative stress response and the xenobiotic metabolism toxicity pathways. We identified non-specific effects caused by transient transfection itself and suggested preventive strategies. Further, we identified toxicity pathways’ cross-talk as a significant driver of uncertainty in regards to the assessment of receptor-mediated toxicity. Additionally, we evaluated the correlation between cytotoxicity in cultured zebrafish cells and the acute toxicity observed in zebrafish embryos. When using chemical distribution models to derive bioavailable concentrations, we observed a good positive correlation between the two test systems. The results advocate an intensified use of fish in vitro assays in integrated testing strategies. Conclusively, new approach methods, as developed and applied in this thesis, show great potential in future toxicity testing and environmental monitoring.
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| 3. |
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| 4. |
- Lamei, Sepideh
(författare)
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The effect of honeybee-specific lactic acid bacteria on american foulbrood disease of honeybees
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The honeybee, Apis mellifera, is one of the most economically important pollinators and highly valued for its honey and wax production. Managed honeybees occupy an increasingly critical role in agricultural productivity and food security. American foulbrood (AFB) is a highly contagious and destructive bacterial honeybee brood disease caused by Paenibacillus larvae that affects beekeeping worldwide. However, only a minority of bacteria associated with honeybees are harmful. Honeybee-specific Lactic Acid Bacteria (hbs-LAB), a defined group of beneficial bacteria inhabiting the honey crop, have strong antimicrobial properties important for honey production and honeybee health that could be exploited for combating diseases such as AFB. The aim of this thesis was to investigate the effect of hbs-LAB on P. larvae and AFB, both in culture, in individual larval bioassays, and at colony level. First we showed that the laboratory cultivation of the 13 distinct hbs-LAB was significantly improved by the addition of L-cysteine and fructose to the medium and optimized a culture-independent molecular technique for the detection and identification of the individual hbs-LAB species. Secondly the effect of the cell free supernatant, the secretome, from a culture mix of the 13 hbs-LAB species was investigated on P. larvae growth and associated larval mortality. The results showed that this secretome strongly inhibited the multiplication of P. larvae vegetative cells but that spore germination appeared to be unaffected, and that it decreased the mortality of P. larvae infected larvae. Finally it was shown that oral administration of hbs-LAB supplement to honeybee colonies had no influence on colony-level P. larvae spore levels or colony strength. Furthermore, the results showed that although the antibiotic tylosin decreased AFB symptoms in colonies, it had no effect on P. larvae spore levels. In conclusion, the colony-level results do not contradict the antagonistic effects observed in individual larvae in laboratory studies, but rather suggest that supplementary administration of live bacteria may not be the most effective way to harness such effects in a useful application.
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| 5. |
- Nilsson, Kerstin
(författare)
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To work or not to work in an extended working life? Factors in working and retirement decisions
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In most of the industrialised world, the proportion of older and retired people in the population is continuously increasing. This will have budgetary implications for maintaining the welfare state, because the active working section of the population must fund the non-active and old population. Aim: The overall aim of this thesis was to obtain knowledge about older workers’ work and life situation in association with their planning and decision to retire from working life. Method: The thesis includes one qualitative and three quantitative studies conducted in Sweden. Result: Self-rated health was found to be a better measure than diagnosed disease of whether older workers believed they could work until 65 years or beyond. Health seems not to be a general impediment to working in old age if older workers are satisfied with their work situation and have enough time and opportunities to recover from fatigue. In one of Sweden’s most hazardous work environments, older workers were not injured significantly more often than younger workers. Good mental and physical work environment, moderate working pace and working time, and the right competence and possibility for skills development were factors determining whether older workers believed they can extend their working life. Attitude to older workers in the organisation, motivation and work satisfaction were factors determining whether older workers want to extend working life. Health, personal economic incentives, family/leisure pursuits and attitude to pension in society affected both whether people believed they can and wanted to extend their working life. In their final retirement decision, older workers considered: i) their possibility to balance and adapt functional ageing and health to a sustainable work situation; ii) their economic situation; iii) possibilities for social inclusion and coherence; and iv) possibilities for meaningful activities. Whether these requirements were best fulfilled in or outside working life determined the decision to continue working or to retire. Conclusion: If it is desirable for society that people will to extend their working life, both the “can work” and the “want to work” factors need to be met. It is important to provide a good fit inside working life. This requires a focus not only on older workers, but also on organisations and managers in order to provide incentives that keep older workers in the work force.
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| 6. |
- Aballay, Erwin
(författare)
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Rhizobacteria associated to Vitis vinifera and their effect on the control of Xiphinema index, Meloidogyne ethiopica and Vitis growth
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plant-parasitic nematodes are one of the most important pests affecting the growth of vineyards due to the destruction of new roots. Several species are associated with this problem, the most important being the ectoparasite Xiphinema index and the endoparasite Meloidogyne ethiopica. The search for new pest and disease control methods based on bioantagonist microorganisms is an important aspect of modern agriculture and the development of tools based on the use of rhizobacteria is becoming a widely evaluated alternative. The present study on suppressive soils started with a survey undertaken in productive Chilean vineyards to explore the younger roots of grapevines and identify the presence of rhizobacteria. More than 1800 soils were surveyed and a set of 11 vineyards were selected and considered suitable for bacteria isolation, as they showed low densities of plant-parasitic nematodes. A total of 400 bacterial isolates in 25 genera were obtained using tryptic soy broth agar and identified with fatty acid profiling. Two of the most frequently isolated species were Pseudomonas putida (35.1%) and P. fluorescens (6.1%). The effect of these isolates on the parasitism and reproduction of X. index was assessed through assays using potted vine plants (cv. Thompson Seedless) and a bacterial suspension containing 1×106 CFU/mL. Some isolates from Bacillus megaterium, B. brevis, B. mycoides, B. sphaericus, B. thuringiensis, Pseudomonas corrugata, P. putida, P. alcaligenes, P. savastanoi, P. fluorescens, P. pseudoalcaligenes, P. viridiflava, Stenotrophomonas maltophilia, Serratia plymuthica, Cytophaga johnsonae, Rahnella aquatilis, Stenotrophomonas sp., Variovorax paradoxus and Curtobacterium flaccumfaciens reduced root damage and suppressed populations. Isolates of B. brevis, Comamonas acidovorans, B. megaterium, Pantoea agglomerans and P. savastanoi increased plant growth or root weight, but did not control nematodes. Most of the culture filtrates obtained from isolates from four vineyards were effective in killing X. index and decreasing egg hatching, which was not related to damage or population control. It was estimated that 89, 32 and 16% of the isolates were effective against X. index under supernatant conditions, in potted plants growing in sterile substrate and in potted plants growing in field soil, respectively. Sixteen bacterial isolates previously assessed were also evaluated on M. ethiopica in vine cv. Chardonnay. Seven isolates (Serratia marcescens, C. acidovorans, P. agglomerans, Sphingobacterium spiritivorum, B. mycoides, Alcaligenes piechaudii and S. plymuthica) decreased damage or reproduction, showing that different species of nematodes can respond differently to a particular isolate.
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| 7. |
- Abd El-Daim, Islam Ahmed Moustafa
(författare)
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Use of rhizobacteria for the alleviation of plant stress
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plant growth promoting rhizobacteria are beneficial microbes able to induce plant stress tolerance and antagonise plant pathogens. The present study showed that wheat seedlings pre-treated with Bacillus thuringiensis AZP2 had better tolerance to severe drought stress and showed 78% greater plant biomass and five-fold higher survivorship compared to wheat seedlings not treated with the bacterium. The effect of B. thuringiensis AZP2 also resulted in improved net assimilation and reduced emission of stress volatiles. The study investigated the effect of the inactivation of sfp-type phosphopantetheinyl transferase in plant growth promoting bacterium Paenibacillus polymyxa A26. The inactivation of the sfp gene resulted in loss of NRP/PK production such fusaricidins and polymyxins. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. Its biofilm promotion is directly mediated by NRP/PK, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Further, increased biofilm formation was connected with enhanced ability of the sfp inactivated strain to remarkably protect wheat seedlings by improving its survival and biomass under severe drought stress conditions compared to wild type. Fusarium graminearum and F. culmorum are the causing agents of a destructive disease known as Fusarium head blight (FHB). The disease is the leading cause of contamination of grain with Fusarium mycotoxins that are severe threat to humans and animals. Biological control has been suggested as one of the integrated management strategies to control FHB causing agents. The present study showed that P. polymyxa A26 is a potent antagonistic agent against F. graminearum and F. culmorum. In order to optimize strain A26 production, formulation and application strategies traits important for its compatibility need to be revealed. Hence, a toolbox comprising of dual culture plate assays and wheat kernel assays including simultaneous monitoring of the FHB causing pathogens, A26 and mycotoxins produced was developed in the present study. Using this system results showed that, besides the involvement of lipopeptide antibiotic production by P. polymyxa in the antagonism process, biofilm formation ability may play a crucial role in the case of A26 F. culmorum antagonism.
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| 8. |
- Aboshady, Hadeer Moursy
(författare)
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Genomic variation and molecular mechanisms of the host response to gastrointestinal nematodes in small ruminants
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gastrointestinal nematode (GIN) infections are one of the major constrains for sheep and goat production worldwide. One of the promising control strategies is the genetic selection for resistant animals as there are no issues due to anthelmintic resistance and it aligns to demands for chemical-free food. Exploring possible phenotypic and genomic markers that could be used in breeding scheme besides understanding the mechanisms responsible for resistance were the main goals of this thesis. Thesis consists of General introduction, a brief description of GIN biology and methods to control GIN with focus on phenotypic and genomic markers, four papers and General discussion. In paper Ⅰ, a systematic review and meta-analysis were conducted to re-analyse and summarize the findings on immunoglobulins response to GIN in the literature and discuss the potential to use immunoglobulins as biomarkers of the host resistance. A conceptual model summarizing the role of immunoglobulins in resistance to GIN is proposed. In paper Ⅱ, transcriptome profiling of the abomasal mucosa and lymph node tissues were compared between non-infected, resistant and susceptible Creole goats experimentally infected with Haemonchus contortus. Results indicated that the maintenance of the integrity of the mucosa has probably the priority for the host at late infection stage. In paper Ⅲ, the dynamics of the response of the abomasal mucosa of resistant and susceptible Creole goats experimentally infected with H. contortus were compared. The immune response was activated through many relevant pathways including the Th1 immune response at different time post-infection. Interestingly, the results showed a simultaneous time series activation of Th2 related genes in resistant compared to susceptible kids. In paper Ⅳ, the genomic variants of Creole goats resistant and susceptible to H. contortus were discovered from RNAsequencing data at four different times post-infection. Single nucleotide polymorphisms, insertions and deletions that distinguish the resistant and the susceptible groups were identified and characterized through functional analysis. The T cell receptor signalling pathway was one of the top significant pathways that distinguish the resistant from the susceptible group with genomic variants in 78% of genes in this pathway.
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| 9. |
- Abrahamsson, Malin
(författare)
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Patterning during embryo development in Pinus : with special emphasis on somatic embryogenesis in Scots pine (Pinus sylvestris L.)
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Somatic embryogenesis is an attractive method to propagate conifers vegetatively. However, many species belonging to Pinus are recalcitrant to somatic embryo development. The overall aim of this thesis has been to gain a better understanding of the developmental pathway leading to cotyledonary somatic embryos of Scots pine (Pinus sylvestris). By comparing the developmental pathway of somatic embryos in a normal and in an abnormal cell line, differences between the cell lines were identified. An important difference was the high ratio of early and late embryos carrying supernumerary suspensor cells in the abnormal cell line compared to embryos in the normal cell line. This unbalanced ratio between the embryonal mass and the suspensor is at least partly caused by a disturbed polar auxin transport. Furthermore, a high proportion of early and late embryos degenerated in both cell lines. The degenerating embryos in the normal cell line were eliminated in a similar way as subordinate embryos in the seed. Contrastingly, the degenerating embryos in the abnormal cell line were not eliminated; instead the degenerated embryos started to differentiate new embryos creating a loop of embryo degeneration and embryo differentiation. During initiation of embryogenic tissue, the protruding early zygotic embryo(s) started to degenerate before a proliferating embryogenic culture was established, indicating that the initiation of embryogenic cultures is not a direct continuation of cleavage polyembryony. The results further suggest that there is a high risk that cell lines initiated from early zygotic embryos at the stage of cleavage develop abnormally. To be able to use more differentiated tissues as explants for initiation of embryogenic cultures, more knowledge is needed about totipotence and embryogenic potential. Treatment with the histone deacetylase inhibitor trichostatin A (TSA) during maturation of somatic embryos of Norway spruce inhibited the maturation progression of the embryos. Furthermore, although TSA-treatment maintained the embryogenic potential in germinating somatic embryos, it did not enable the embryos to regain embryogenic potential after it was lost. By analysing global changes in gene expression during early zygotic embryo development in Scots pine, we identified genes and processes that might be important for regulating the cleavage process and for the development of a dominant embryo. Together these results contribute to the knowledge that in turn can lead to improved protocols for large scale propagation of Pinus species via somatic embryos.
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| 10. |
- Abrahamsson, Sara
(författare)
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Genetic dissection of quantitative traits in Scots pine
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The phenotypic expressions of Scots pine, have been extensively studied over the years, but the gene regulation behind the traits has only just begun to be elucidated. The overall aim of this thesis was to start dissecting the genetics behind a number of adaptive traits in Scots pine and examine how they are influenced by relatedness using different molecular tools. In a full-sib family of Scots pine the genetic variation in autumn frost hardiness and height growth was revelead by measuring open-pollinated offspring. A significant genetic variation for both traits was found, a prerequisite to identify quantitative trait loci (QTL). A conceptual statistical model in the Bayesian framework for identifying QTLs in dynamic traits i.e. traits that vary over time, was developed and applied in a QTL study based on a full-sib family of 250 trees. A set of 160 AFLPs were utilized. QTLs for three latent traits were identified: one for the slope (growth) and two for the quadratic term (growth cessation). As a tool to identify candidate genes for the study of quantitative adaptive traits, gene regulation under continuous red (cR) and far-red (cFR) light was studied in hypocotyls from open-pollinated seeds from a natural population in northern Sweden using microarray technology. The gene expression patterns for the light response pathway in Scots pine under cFR show clear differences from those of angiosperms, wherein we observed up-regulation of cryptochrome1. This gene has, therefore, become a strong candidate gene that deserves further studies to elucidate the genetics behind Scots pine adaptation. Not knowing the genetic relationship and inbreeding of trees, and how it influences the phenotypic expression, can lead to over- or underestimation of additive genetic values resulting in biased heritability estimates. A natural population of Scots pine, earlier identified as being highly inbreed, was used to investigate the influence of inbreeding by the correlation between heterozygosity and propotion of sound seed (PSS), average seed weight and proportion of rare alleles (PRA). Heterozygosity fitness correlation (HFC) was found positive for PSS and negative for PRA most likely due to recessive deleterious alleles purged in homozygotes. The study provided evidence that, as predicted by theory, inbreeding enhances HFC in a species with high outbreeding rate and high number of lethal equivalents as Scots pine.
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| 11. |
- Abro, Rani
(författare)
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Digestion and metabolism of carbohydrates in fish
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the digestion and metabolism of carbohydrates in Arctic charr, Eurasian perch and tilapia. Two sources of carbohydrates, native starch (wheat) and chitin (zygomycete biomass), were evaluated. Gut tissue of Arctic charr displayed significant chitinase activity, of both endo- and exo-chitinase forms. Moreover, the distribution pattern along the gastrointestinal tract of Arctic charr differed between endo-chitinase and exo-chitinase. The endo-chitinase activity in stomach tissue and in the distal intestine was several hundred-fold higher than the exo-chitinase activity in stomach tissue. The greatest exo-chitinase activity was found in the distal intestine fed a zygomycete-based diet. Disturbed intestinal integrity and increased uptake rate of the amino acid lysine were observed in the distal, but not proximal, intestine of fish fed the zygomycete-based feed. A ¹HNMR metabolomics approach revealed no differences in metabolic profile in liver tissues of Arctic charr fingerlings fed a zygomycete-based diet and a fish-meal based diet. The inclusion of wheat starch did not affect α-amylase activity in gut tissue of Arctic charr and Eurasian perch. Overall, α-amylase activity was correlated with the trends obtained for starch digestibility. The apparent digestibility (AD) of crude protein, starch, crude fat and energy differed between the fish species, with on average higher values for all parameters in Eurasian perch than in Arctic charr. Within fish species, dietary starch level had no effect on AD of dry matter, crude protein, crude fat and energy. Studies of the metabolic response to wheat starch inclusion in Arctic charr and tilapia using ¹HNMR base metabolomics indicated metabolic effects in tilapia, while inclusion of starch in the diet of Arctic charr resulted in partial or negligible metabolism effects. Thus there are species-related differences in the metabolic response to dietary starch inclusion.
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| 12. |
- Abro, Shahid, hussain
(författare)
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Molecular characterization and detection of infectious bronchitis virus
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the molecular characterization and detection of infectious bronchitis virus (IBV), an important pathogen that causes heavy losses in the poultry populations worldwide. The aim of the research was to better understand the molecular characteristics of the virus and to investigate the factors behind the continuous emergence of new genetic variants and the occurrence of outbreaks. The studies showed that the viral genome is under a continuous evolution, due to mutations, strong selective pressure and recombination events. These forces lead to a wide genetic diversity and the generation of new variants of this virus. The viral genes encoding the spike, envelope and membrane proteins can be considered the main genomic regions, which are indicating the evolution processes of IBV. The various strains contain specific structural and functional motifs in their genes and the alterations in these motifs may affect the infection biology of the virus. The constant emergence of new variants in Sweden is likely due to the introduction of novel IBV strains from other European countries through the import of poultry products, or by the continuous migration of wild birds. The in silico investigations of the spike glycoprotein coding regions of the Massachusetts and QX-like genotypes demonstrated molecular differences between these genotypic variants. It is hypothesized that the genetic diversity in the spike gene of IBV and of other avian coronaviruses, as well as of human, bat, and other animal coronaviruses could be associated with the adaptation and host specificity of these infectious agents. The data obtained by molecular characterization approach was also used for the development of a new molecular method for the improved detection and genotyping of this virus. A microarray platform was developed for the simultaneous detection and rapid typing of IBV variants. This assay provides a practical tool for better diagnosis, for studying the effectiveness of vaccination and for performing large-scale epidemiological studies.
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| 13. |
- Abubaker, Jamal
(författare)
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Effects of fertilisation with biogas residues on crop yield, soil microbiology and greenhouse gas emissions : recycling of plant nutrients from bioenergy production
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The amount of residues generated by biogas production has increased dramatically due to worldwide interest in using renewable energy. Biogas residues (BRs) originate from anaerobic degradation of different types of rural and urban organic wastes and have been proposed as organic fertilisers because of their high content of ammonium and other valuable macro- and micro-nutrients. However, application of BRs to agricultural soils may be accompanied by environmental risks, since they may contain heavy metals and organic pollutants. Therefore the effects of BRs on crop production and on the soil ecosystem and environment urgently need to be investigated before their wider use. This thesis evaluated and compared different types of BRs against cattle slurry, pig slurry, compost and mineral fertiliser with respect to their (1) ability to provide plants with necessary nutrients, (2) impact on the soil microbial ecosystem and (3) effects on emissions of the greenhouse gas nitrous oxide (N₂O). The results from short-term laboratory experiments and a long-term field trial showed that BRs increased crop yield to the same extent or more than conventional mineral fertiliser and compost, but less than pig slurry. BRs generated from source-separated organic household waste had a tendency to give higher crop yield and soil microbial activities than other BRs. BRs had no general negative effect on soil respiration, but substrate-induced respiration decreased significantly in organic soil on addition of BRs. Although all BRs initially inhibited potential ammonium oxidation and potential denitrification activity, no long-term negative effects were detected. BRs stimulated ammonium assimilation, which can temporarily decrease nitrogen availability to the plant. Furthermore, the bacterial community structure in the sandy soil was altered by BRs and cattle slurry, but no significant change was seen in the community structure of clay and organic soil. Application of BRs and animal slurry increased N₂O emissions, but the total losses and flux patterns were affected by fertiliser type and soil type. In conclusion, the fertiliser value of BRs should be regarded as high and they apparently have no long-term adverse effects on soil microbial functions and structures. Thus the problematic amounts of residues associated with expansion of biogas production could be turned to advantage, as these residues seem to be safe and competitive fertilisers.
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| 14. |
- Adevi, Anna
(författare)
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Supportive nature - and stress : wellbeing in connection to our inner and outer landscape
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many benefits are claimed for the interplay between humans and nature, such as nature’s potentially positive effect on wellbeing and health. The main aim with the present work was to increase the understanding of how nature nvironments can support and contribute to health improvement from stress related experiences. Different landscape types’ effect on stress was studied in Sweden. Single case-studies focused on factors considered being essential in the recovery process for people diagnosed with exhaustion disorder within a stress rehabilitation-program through garden therapy in Alnarp, Sweden. A simplified conclusion of the thesis would be that the childhood landscape seems to play a significant role affecting the choice of the adult’s recreational setting - and recreational activity when stress is included. People feel more at home in the type of landscape they grew up in and more often chose to settle down in this type of landscape; even if they have moved from their childhood region. People also prefer qualities connected to their childhood landscape, but seem to attach more easily to qualities suggested having innate significance. The stress-recovery process within the garden therapy seems to be supported, hastened and deepened because of a multisensory change in awareness when contact with nature is combined with therapeutic interventions. Different psycho-physiological processes are discussed as well as the importance of self-chosen places in the garden based on present mood and the significance of the interaction between symbolic and concrete activities. The garden, the caregivers, and the group of participants together make up an arena which combines structure with freedom of action, in which the participants get the chance to regulate their needs and desires. Two hypotheses are presented, which might contribute to filling some current gaps in knowledge regarding the potential benefits of human interactions with nature.
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| 15. |
- Adler, Karl
(författare)
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Digital soil mapping and portable X-ray fluorescence prediction of cadmium, copper and zinc concentrations as decision support for crop production
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Trace element concentrations in agricultural soil are important for crop production. Certain trace elements, e.g. copper (Cu) and zinc (Zn), are essential for crops to complete their life cycle. Other trace elements, e.g. cadmium (Cd), can be harmful to crops or the end-consumer. Hence, it is important to have maps of soil concentrations of trace elements or methods for determining concentrations in soil samples. This thesis investigated the possibility of predicting trace element concentrations (Zn, Cu, Cd) in soil samples using portable X-ray fluorescence (PXRF) measurements. It also examined usefulness of digital soil mapping (DSM) to create maps of Cu and Cd concentrations in agricultural topsoil in Sweden.Portable X-ray fluorescence models were validated at national and farm level. Predicted Zn concentrations were found to be comparable to those obtained in conventional laboratory analysis, while predicted Cd and Cu concentrations were less accurate. The most accurate PXRF models were created using non-linear machine learning algorithms, e.g. random forest.Digital soil mapping of Cd concentrations in Skåne County, combined with data from grain sampling, revealed that low Cd concentrations in winter wheat grain were associated with predicted low concentrations in soil. The map could thus be used to identify arable soils suitable for producing winter wheat for products with strict quality criteria, e.g. baby food. Digital soil mapping of Cu concentrations at national level revealed that 47% of arable soils are highly likely not at risk of Cu deficiency. Covariate importance analysis indicated importance of airborne gamma radiation measurement data in DSM of Cu and Cd concentrations.
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| 16. |
- Adom, Philip Kofi
(författare)
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Energy demand management in selected African countries
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis contains five empirical papers that contribute to the energy demand management literature on Africa. It investigates the following policy issues – business cycle and energy conservation, government fuel subsidies and energy efficiency, economic growth and environmental quality, structural effects in parameters, the transition between energy efficiency and energy inefficiency, forecast of energy demand, shifts in demand behaviour, and the persistence profile of energy demand to shocks – using data from five countries: Algeria, Nigeria, South Africa, Cameroon and Ghana. In terms of contribution, this thesis provides the first empirical attempt to investigate the transition between energy efficiency and energy inefficiency; provides a comprehensive analysis of road transport energy demand and the implications of structural breaks for model parameters; provides evidence to support the fact that economic growth and environmental quality are jointly achievable, and argues that there is an income state that drives investment in energy efficiency. The main results of the thesis are as follows. First, low income state does not promote investment in energy efficiency. Second, reducing or withdrawing government fuel subsidies will enhance energy efficiency. Third, investment in technology in the industrial sector is a likely panacea to integrate the goals of economic growth and environmental quality. Fourth, the existence of structural breaks in the data significantly changes how price of crude oil, FDI, economic structure and trade openness promote energy efficiency. Fifth, the characteristics of industries and technology absorptive capacity of countries significantly facilitate energy savings in FDI. Sixth, the duration of an energy inefficient state is about twice as long as an energy efficient state, mainly due to fuel subsidies, low income, high corruption, regulatory inefficiencies, poorly developed infrastructure and undeveloped markets. Finally, diesel and gasoline fuels differ in many respects which suggest that a discriminatory tax policy would be an appropriate tax policy than a uniform tax policy.
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| 17. |
- Adu, George
(författare)
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Studies on economic growth and inflation : theory and empirics
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of four independent papers. Paper I examines the effect of environmental policy on economic growth in a small open economy in a neoclassical framework with pollution as an input. We show that the effect of environmental policy on growth is stronger in the open economy case relative to the closed economy model if the country has strong aversion to pollution and thus serves as a net exporter of capital in the international capital market. On the other hand, if the agents in the economy have low aversion to pollution and thus import capital, the effect of environmental care on growth is stronger in the closed economy relative to the open economy. Paper II analyses the effect of asymmetry in factor endowments between resource-rich and resource-poor countries on equilibrium bias of technology development and adoption possibilities. First, we show that the bias in equilibrium technology in the resource-poor North is determined by its relative abundance of human capital and physical capital. Secondly, we show that the equilibrium bias in technology in the resource abundant South is dependent positively (negatively) on the relative abundance (scarcity) of skilled (unskilled) labour and the relative abundance (scarcity) of physical (natural) capital in the North. This force is dampened by the relative scarcity of skilled labour and physical capital in the South. These forces drive wage inequality, high cost of capital and skill technology mismatch in the South, all of which are bad for growth. These effects cumulatively, explains part of the observed differences in growth performance between resource -rich and resource-poor countries. Paper III investigated the relationship between long run economic growth in Ghana and natural resource abundance using time series econometric techniques. Using a number of indicators that could proxy for resource abundance in eight alternative specifications, the results rejected the resource curse hypothesis. Paper IV provides an empirical analysis of the factors accounting for inflation dynamics in Ghana using the bounds test and other econometric approaches. We find that real output, nominal exchange rate, broad money supply, nominal interest rate and fiscal deficit play a dominant role in the inflationary process in Ghana.
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| 18. |
- Agostinelli, Marta
(författare)
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Fungal assemblages in forest trees : influence of internal and external conditions
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Forest trees host a plethora of microorganisms (bacteria, viruses, fungi) whose roles and diversity are still poorly understood despite the increased scientific interest for the past decades. The thesis focuses on the diversity of endophytic and epiphytic fungi in the aerial tissues of broadleaved trees. It tests a basic hypothesis that the diversity and frequency of endophytic and epiphytic fungi vary depending on the vitality and disease susceptibility of the host. Additionally the thesis explores if the chemical variation in trees may relate to differences in fungal community. Particularly, the aim was to describe how the fungal communities of three broadleaved species relate to the general vitality or specific pathogen resistance of the trees, and if herbivory or fertilization influence the fungi through altered levels of potentially antimicrobial metabolites, condensed tannins. Culture-based and culture-independent (NGS) techniques were used to capture the fungal community in the twigs of pedunculate oak (Quercus robur L), in the leaves of aspen (Populus tremula L), and in the leaves and twigs of European ash (Fraxinus excelsior L). The secondary metabolites were studied with HPLC, LC-MS, and GC-MS analyses. The results showed that the fungal assemblages are influenced by a complex network of factors related to the status of the host (internal factors: health, chemotype) and its environment (season, site, nitrogen, herbivory). Trees with different vitality or different phenotypic response to pathogen hosted quantitatively and qualitatively diverse fungal communities. Tissue type and seasonal variation were confirmed to be highly selective factors in shaping fungal communities of forest trees. The endophytic communities associated with xylem seemed to be shaped by the tree vitality more readily than the fungi associated with leaf or bark. Condensed tannins, nitrogen fertilization, and herbivory did not explain the structure of fungal communities in aspen leaves. Leaf phenolic metabolites reflected well the general vitality phenotype of the trees, but the relationship between fungi and phenolics may not be straightforward. The technological advances and the use of different methods to survey fungal communities may help disclosing the unknown fungal biodiversity hosted by forest trees. Further studies on fungal communities are needed to reveal the ecological relevance that fungal assemblages have in the regulation of major ecological cycles. Understanding the mechanisms regulating the establishment of fungal communities may contribute to the possibility of using fungal assemblages in forest practices to help forest coping with sudden changes and be able to provide different ecosystem services.
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| 19. |
- Agstam, Oskar
(författare)
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Restoration of Nutrient Rich Lakes - Towards Better Understanding of Sediment Phosphorus Availability and Management
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lakes are important for many reasons as they provide valuable ecological and human services, such as drinking water and recreational use. Eutrophication, a result of excess nutrients (e.g. phosphorus (P)) in lakes, is a threat to these resources, causing impairment of water quality. Excess P loading to lakes accumulates in the sediment, consequently making sediment a potential source of P via release (internal loading). One way of counteracting effects caused by internal loading is to inactivate the pool of potentially available P in the sediment. Better information is needed for optimizing most in-lake P reduction methods, including aluminum (Al)-treatment. One of these areas is better knowledge about the availability of different P fractions, and which fractions to target with a specific dose of Al under certain environmental conditions such as bioturbation (e.g. sediment mixing by carp). We also need to deepen the knowledge about modern Altreatment methods, with respect to both treatment techniques and dosing. Knowledge about factors affecting how long the positive effects from an Al-treatment last also needs to be improved. This thesis presents results concerning optimization of Al application methods, where a novel application method that injects Al into the sediment was evaluated and a model for optimal Al dose determination is presented. Factors affecting treatment longevity were evaluated, using historical water quality records and knowledge about a previously assumed recalcitrant P form being bioavailable due to bioturbation by benthic feeding fish like carp and bream. Al-treatment methods, including practical Al application methods as well as dosing methods are developing rapidly and being applied in the field, and further work is needed to keep up with evaluating the progress of lake restoration results using methods like Al-treatment.
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| 20. |
- Aguilera Nuñez, Guillermo
(författare)
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Local and landscape-level impacts of agricultural intensification on arthropod communities and their interaction networks
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Arthropods play a central role in agricultural landscapes being responsible for the delivery of many ecosystem services such as pollination, biological pest control, and nutrient cycling. But the current global decline of arthropods is intensified by habitat modification, loss and fragmentation, pesticide use and other intensive management practices. Thus, it is crucial to understand how such impacts affect ecosystem services provisioning. In this thesis, I aim to explore how the management of local crop fields and landscape composition affect beneficial arthropod communities at different levels, including abundances and diversity of species and species interaction networks. I focus on predaceous and parasitic insects that provide biological pest control and pollinators. I assess i) how crop diversity affects arthropod diversity, ii) how fertilisation affects the local predator community and pest control, iii) how crop type (annual vs perennial) and landscape composition affect the predator-prey and host-parasitoid interaction networks and the implications for pest control. I found that increasing crop diversity in landscapes with a high proportion of seminatural habitats can enhance the diversity of beneficial arthropods. I also detected that organic fertilisation can benefit the abundance of local predators while specialist predators that move into the crop from the surrounding habitats boost biological pest control. I also found that crop type and landscape composition have effects beyond community species composition as also the interaction networks were altered, modifying the network stability and pest control potential. My findings suggest that the main drivers of change in agricultural landscapes affect arthropod communities at different levels. Effects of habitat type and local management can be observed not only in the community composition, but some of the consequences were also reflected in the species interaction networks. Finally, I show that food web ecology can link community composition and ecosystem service provisioning.
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| 21. |
- Ahlberg, Viktor
(författare)
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Innate immune responses to a saponin adjuvant in the pig : application of gene expression profiling
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vaccination is one of the most powerful ways to prevent infectious diseases. Successful vaccines produce a long-term immunity including effector T and B lymphocytes. In this context, adjuvants have a key role in vaccines by stimulating the innate immunity and thereby enhancing and shaping the subsequent adaptive immune response. The aim of this thesis was to elucidate the early innate immune response to the saponin-based adjuvant Matrix-M in the pig. Gene expression profiling was applied to monitor the global transcriptional response to Matrix-M in vivo. The innate immune response was further characterized by quantitative PCR analysis in vivo and in vitro and the early immunomodulatory effect of Matrix-M was evaluated in a contact exposure model. A mild inflammation and a cellular influx were recorded at the injection site and in the draining lymph node 24 hours after intramuscular injection of Matrix-M in pigs. In accordance, microarray analysis detected transcriptional alterations of genes for cytokines, chemokines and pattern recognition receptors in both tissues. Interferon- regulated genes were significantly overrepresented in these tissues, accompanied by increased gene expression for interferon-β in in the draining lymph node and interferon-α in blood. Transcriptional responses to Matrix-M in vitro were generally low but increased culture and exposure time affected genes for pro-inflammatory cytokines and TH cytokines in lymphocytes. Low levels of interferon-α gene expression were also detected in monocyte-derived dendritic cells. A contact exposure model was established to mimic field conditions when allocating grower pigs, by mixing pigs of various health statuses. After transport and mixing with conventionally reared pigs, all specific pathogen free (SPF) pigs in this model developed respiratory disease. Systemic symptoms that correlated with granulocyte counts, serum amyloid A levels and transcription of IL18 and TLR2 were provoked in two out of four SPF pigs that received saline prior to exposure, but not in those given Matrix-M. Taken together, the application of gene expression profiling successfully identified the induction of innate immune responses in porcine tissues and indicated that Matrix-M primes the host for further immune regulation. Thus, Matrix-M or similar saponin formulations are potentially useful clinical immunomodulators or adjuvants in emergency vaccines.
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| 22. |
- Ahlbäck Widenfalk, Lina
(författare)
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Springtails in space : factors structuring Collembola populations and communities, revealed by trait-based analyses
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The relative influence of environmental conditions, biotic interactions and dispersal limitation for community structure and diversity patterns is a reoccurring theme in community ecology. In studies of soil fauna communities, small-scale horizontal and vertical variations in environmental variables and biotic interactions have often been disregarded, despite these being key factors to understanding the diversity of soil fauna communities. In this thesis I examined the spatial distribution patterns of springtail (Collembola) species and communities in three different ecosystems: a salt marsh, mature pine forests and a high Arctic tundra meadow. The different systems consisted of a, to the human eye, homogeneous habitat. Still, they had different regimes and small-scale heterogeneity in environmental variables. In the three first studies the focus was on species and trait composition and diversity, at scales from 10 cm to 300 km. In the fourth paper I question the use of species-level analyses of distribution patterns, as different age classes within a species might be structured by different factors. I found that when habitat conditions were kept as similar as possible, the pine forest Collembola communities had similar functional diversity, although there was a high species turnover both between samples within study sites and between sites. The functional similarity between samples was lower in the salt marsh habitat, a habitat characterized by frequent inundation events. The small-scale variation in species and trait composition was best explained by spatial variables in the stable mature pine forest floor, while in the dynamic salt marsh environmental variation was most important. Coexisting species showed a higher difference in traits than expected in the pine forest, while coexisting species were similar in traits in the salt marsh. This indicates that species interactions can have a large impact on the community composition of springtails at small spatial scales. Small-scale niche partitioning may be one explanation for the high local diversity observed in many soil communities. I found that incorporating species-specific trait information in studies greatly helps our understanding of the mechanisms structuring communities, despite the finding that in some species of collembolans different age classes may use space differently. To improve our understanding of Collembola communities both these factors should be considered in future studies.
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| 23. |
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| 24. |
- Ahlman, Therese
(författare)
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Organic dairy production : herd characteristics and genotype by environment interactions
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to gain further knowledge about the performance of cows in organic dairy production and their ability to adapt to the organic production environment. Milk production traits, fertility traits, somatic cell count (SCC) and longevity traits were analysed in organic and conventional herds and the reasons for culling in the two systems were investigated. Furthermore, the genetic correlation between traits expressed in organic and conventional production was estimated to assess the occurrence of genotype by environment interaction (GxE). The data contained records from almost all organic and conventional herds in Sweden. This thesis shows that performance of organically managed dairy cows differs from conventionally managed cows. Cows in organic herds had lower production, better fertility and higher SCC than cows in conventional herds. However, the performance of cows in organic production depended to a large extent on the lower milk production level. At a given production level, organically managed cows had slightly worse fertility but equal SCC as cows in conventional herds. Cows stayed longer in organic herds than in conventional herds and the main reason for culling differed between the production systems. The main reason for culling in organic production was poor udder health followed by low fertility. In conventional production the main reason for culling was low fertility followed by poor udder health. The results indicate that organic farmers are more concerned about udder health than conventional farmers are. Genetic correlations for production, fertility, SCC and longevity, estimated in organic and conventional dairy production were in general close to unity. The results indicate that current breeding values for Swedish Red bulls, estimated in conventional production, are adequate for organic production. Weak GxE was found for fertility traits in Swedish Holstein cows, indicating that some cows of this breed are better suited for organic production than others. However, the magnitude of GxE does not justify development of a separate breeding programme for the organic population today.
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| 25. |
- Ahlström, Martin
(författare)
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Stand development and growth in uneven-aged Norway spruce and multi-layered Scots pine forests in boreal Sweden
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of the selection system has always been a marginal part of Swedish forestry, and so has research about the system under Swedish conditions. However, the interest in Sweden for uneven-aged forest management has increased because of a rising concern for the ecological and aesthetical consequences from use of the dominating rotation forests system, which creates even-aged forest and has clear-cutting as primary harvesting method. In this thesis I have studied the possibilities and limitations of the selection system in Swedish boreal forests. Stand development, ingrowth and volume increment has been studied in both Norway spruce (Picea abies (L.) H. Karst.), and Scots pine (Pinus sylvestris L.) forests. My studies of uneven-aged Norway spruce show that 1) these forests have the capacity to spontaneously create and maintain an uneven-aged stand structure, 2) there is a positive relation between standing volume and volume increment, and 3) there is no clear relation between the level of ingrowth and stand density. My studies of multi-layered Scots pine forests show that 1) a multi-layered stand structure is more likely the result of size stratification and not of continuous ingrowth, 2) There is positive relation between standing volume and volume increment, and 3) that a low stand density is seems required for ingrowth to occur on a sustainable level. The results imply that for boreal Norway spruce forests, a high standing volume would be recommended when the selection system is applied, whereas for boreal Scots pine forest, uneven-aged management should be motivated by other values than stem production, e.g. aesthetical or ecological.
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