| 1. |
- Ameur, Adam, et al.
(författare)
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SweGen : a whole-genome data resource of genetic variability in a cross-section of the Swedish population
- 2017
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Ingår i: European Journal of Human Genetics. - : NATURE PUBLISHING GROUP. - 1018-4813 .- 1476-5438. ; 25:11, s. 1253-1260
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Tidskriftsartikel (refereegranskat)abstract
- Here we describe the SweGen data set, a comprehensive map of genetic variation in the Swedish population. These data represent a basic resource for clinical genetics laboratories as well as for sequencing-based association studies by providing information on genetic variant frequencies in a cohort that is well matched to national patient cohorts. To select samples for this study, we first examined the genetic structure of the Swedish population using high-density SNP-array data from a nation-wide cohort of over 10 000 Swedish-born individuals included in the Swedish Twin Registry. A total of 1000 individuals, reflecting a cross-section of the population and capturing the main genetic structure, were selected for whole-genome sequencing. Analysis pipelines were developed for automated alignment, variant calling and quality control of the sequencing data. This resulted in a genome-wide collection of aggregated variant frequencies in the Swedish population that we have made available to the scientific community through the website https://swefreq.nbis.se. A total of 29.2 million single-nucleotide variants and 3.8 million indels were detected in the 1000 samples, with 9.9 million of these variants not present in current databases. Each sample contributed with an average of 7199 individual-specific variants. In addition, an average of 8645 larger structural variants (SVs) were detected per individual, and we demonstrate that the population frequencies of these SVs can be used for efficient filtering analyses. Finally, our results show that the genetic diversity within Sweden is substantial compared with the diversity among continental European populations, underscoring the relevance of establishing a local reference data set.
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| 2. |
- Dahlberg, C. Johan, et al.
(författare)
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Correlations between plant climate optima across different spatial scales
- 2020
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Ingår i: Environmental and Experimental Botany. - : Elsevier BV. - 0098-8472 .- 1873-7307. ; 170
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Tidskriftsartikel (refereegranskat)abstract
- Identifying the factors determining the abundance and distribution of species is a fundamental question in ecology. One key issue is how similar the factors determining species' distributions across spatial scales are (here we focus especially on spatial extents). If the factors are similar across extents, then the large scale distribution pattern of a species may provide information about its local habitat requirements, and vice versa. We assessed the relationships between landscape and national optima as well as landscape and continental optima for growing degree days, maximum temperature and minimum temperature for 96 bryophytes and 50 vascular plants. For this set of species, we derived landscape optima from abundance weighted temperature data using species inventories in central Sweden and a fine-grained temperature model (50 m), national optima from niche centroid modelling based on GBIF data from Sweden and the same fine-grained climate model, and continental optima using the same method as for the national optima but from GBIF data from Europe and Worldclim temperatures (c. 1000 m). The landscape optima of all species were positively correlated with national as well as continental optima for maximum temperature (r = 0.45 and 0.46, respectively), weakly so for growing degree days (r = 0.30 and r = 0.28), but sometimes absent for minimum temperature (r = 0.26 and r = 0.04). The regression slopes of national or continental optima on local optima did not differ between vascular plants and bryophytes for GDD and Tmax. However, the relationship between the optima of Tmin differed between groups, being positive in vascular plants but absent in bryophytes. Our results suggest that positive correlations between optima at different spatial scales are present for some climatic variables but not for others. Moreover, our results for vascular plants and bryophytes suggest that correlations might differ between organism groups and depend on the ecology of the focal organisms. This implies that it is not possible to routinely up- or downscale distribution patterns based on environmental correlations, since drivers of distribution patterns might differ across spatial extents.
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| 3. |
- Dahlberg, C. Johan, 1978-, et al.
(författare)
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Performance of Forest Bryophytes with Different Geographical Distributions Transplanted across a Topographically Heterogeneous Landscape
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- Most species distribution models assume a close link between climatic conditions and species distributions. Yet, we know little about the link between species’ geographical distributions and the sensitivity of performance to local environmental factors. We studied the performance of three bryophyte species transplanted at south- and north-facing slopes in a boreal forest landscape in Sweden. At the same sites, we measured both air and ground temperature. We hypothesized that the two southerly distributed species Eurhynchium angustirete and Herzogiella seligeri perform better on south-facing slopes and in warm conditions, and that the northerly distributed species Barbilophozia lycopodioides perform better on north-facing slopes and in relatively cool conditions. The northern, but not the two southern species, showed the predicted relationship with slope aspect. However, the performance of one of the two southern species was still enhanced by warm temperatures. An important reason for the inconsistent results can be that microclimatic gradients across landscapes are complex and influenced by many climate-forcing factors. Therefore, comparing only north- and south-facing slopes might not capture the complexity of microclimatic gradients. Population growth rates and potential distributions are the integrated results of all vital rates. Still, the study of selected vital rates constitutes an important first step to understand the relationship between population growth rates and geographical distributions and is essential to better predict how climate change influences species distributions.
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| 4. |
- Dahlberg, C. Johan, 1978-, et al.
(författare)
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Plant landscape climatic optima correlate with their continental range optima
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Aim Factors determining species’ distributions at smaller scales may inform us about larger scale distributions, and vice versa. We predicted that landscape and continental climatic optima for plants are positively correlated, and that species that have their optima outside a given focal landscape will cluster at the warmest or coldest landscape patches. Also, we predicted that the correlations of temperature optima are stronger for vascular plants than for bryophytes, since bryophytes may be regulated also by air moisture.LocationÅngermanland, Sweden (landscape scale); Europe (continental scale).MethodsWe derived landscape optima from fine-grained temperature models (50 m) and species inventories, and continental optima from MaxEnt niche modelling based on GBIF occurrences and Worldclim temperatures (c. 1000 m), for 96 bryophytes and 50 vascular plants. Optima were derived for growing degree days, and maximum and minimum temperature.ResultsThe landscape and continental optima of all species were positively correlated for growing degree days and maximum temperature (r = 0.19 and r = 0.44), but not for minimum temperature (r = -0.010). Species with their continental optima outside the focal landscape did not clearly cluster in the most extreme parts of the landscape. For vascular plants the correlation was positive for both growing degree days and maximum temperature (r = 0.50 and r = 0.64), but for bryophytes only for maximum temperature (r = 0.34).Main conclusionsThe optima correlations for maximum temperature and growing degree days indicate that we can infer large scale distribution patterns of plants from their local scale distributions, and suggest in which environments species occur if we only know their continental scale optima. The lack of clustering of southern and northern species limits the possibility for conservation actions targeting microrefugia. Lastly, the correlations indicate that the distributions of vascular plants were more influenced by temperature than bryophytes.
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| 5. |
- Dahlberg, C. Johan, 1978-, et al.
(författare)
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Population dynamics of moss transplants across microclimatic gradients
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In order to determine the response of a species to climatic change it is important to study how climatic factors influence its vital rates and population growth rate across climatic gradients. We investigated how microclimate influence the population dynamics of transplants from northern and more southern populations of the forest bryophyte Hylocomiastrum umbratum. We predicted that its population growth rate is favored by moist microclimates with colder maximum temperatures, longer snow cover duration and less evaporation, and that annual shoots (segments) will be shorter under drier conditions. We also predicted that northern populations will have higher population growth rate and larger segments than southern populations when transplanted to the northern range. We placed transplants from three northern and three southern populations of H. umbratum at 30 forested sites in central Sweden differing in microclimate. We marked and followed the growth of individual shoots during two years, and calculated population growth rates and stable stage distributions of segment size classes using transition matrix models for northern and southern transplants, respectively, at each locality. Population growth rate was lower and shorter segments developed at sites with higher evaporation, corresponding to our hypothesis. There were no significant difference in population growth rate and stable stage segment length between southern and northern populations. Higher evaporation during the summer result in lower population growth rates of H. umbratum by affecting vital rates, in terms of less segment growth. Both climate change and forestry may alter evaporation conditions across the landscape and, thus, the future distribution of the species.
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| 6. |
- Dahlberg, C. Johan, 1978-
(författare)
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The role of microclimate for the performance and distribution of forest plants
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microclimatic gradients may have large influence on individual vital rates and population growth rates of species, and limit their distributions. Therefore, I focused on the influence of microclimate on individual performance and distribution of species. Further, I examined differences in how microclimate affect species with contrasting distributions or different ecophysiological traits, and populations within species. More specifically, I investigated the performance of northern and southern distributed forest bryophytes that were transplanted across microclimatic gradients, and the timing of vegetative and reproductive development among northern, marginal and more southern populations of a forest herb in a common garden. Also, I compared the landscape and continental distributions across forest bryophytes and vascular plants and, thus, their distribution limiting factors at different spatial scales. Lastly, I examined the population dynamics across microclimatic gradients of transplants from northern and southern populations of a forest moss. The effects of microclimatic conditions on performance differed among bryophytes with contrasting distributions. There were no clear differences between northern and southern populations in the timing of development of a forest herb or in the population dynamics of a moss. However, within each region there was a differentiation of the forest herb populations, related to variation in local climatic conditions and in the south also to proportion of deciduous trees. The continental distributions of species were reflected in their landscape distributions and vice versa, in terms of their occurrence optima for climatic variables. The variation in landscape climatic optima was, however, larger than predicted, which limit the precision for predictions of microrefugia. Probably, the distributions of vascular plants were more affected by temperature than the distributions of bryophytes. Bryophytes are sensitive to moisture conditions, which was demonstrated by a correlation between evaporation and the population growth rate of a forest moss. We might be able to predict species’ landscape scale distributions by linking microclimatic conditions to their population growth rates, via their vital rates, and infer larger scale distribution patterns.
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| 7. |
- Dahlberg, Johan, et al.
(författare)
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Arteria : An automation system for a sequencing core facility
- 2019
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Ingår i: GigaScience. - : Oxford University Press (OUP). - 2047-217X. ; 8:12
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Tidskriftsartikel (refereegranskat)abstract
- Background: In recent years, nucleotide sequencing has become increasingly instrumental in both research and clinical settings. This has led to an explosive growth in sequencing data produced worldwide. As the amount of data increases, so does the need for automated solutions for data processing and analysis. The concept of workflows has gained favour in the bioinformatics community, but there is little in the scientific literature describing end-to-end automation systems. Arteria is an automation system that aims at providing a solution to the data-related operational challenges that face sequencing core facilities.Findings: Arteria is built on existing open source technologies, with a modular design allowing for a community-driven effort to create plug-and-play micro-services. In this article we describe the system, elaborate on the underlying conceptual framework, and present an example implementation. Arteria can be reduced to 3 conceptual levels: orchestration (using an event-based model of automation), process (the steps involved in processing sequencing data, modelled as workflows), and execution (using a series of RESTful micro-services). This creates a system that is both flexible and scalable. Arteria-based systems have been successfully deployed at 3 sequencing core facilities. The Arteria Project code, written largely in Python, is available as open source software, and more information can be found at https://arteria-project.github.io/.Conclusions: We describe the Arteria system and the underlying conceptual framework, demonstrating how this model can be used to automate data handling and analysis in the context of a sequencing core facility.
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| 8. |
- Dahlberg, Lena, 1970-, et al.
(författare)
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Ensamhet bland äldre personer i Norden
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten presenterar översikter av tidigare forskning och analyser av känslan av ensamhet bland äldre personer. Överlag finns det kunskap om ensamhetens konsekvenser för ohälsa, men det behövs ytterligare forskning där starkare slutsatser kan dras om sambandens riktning, och ett tydligare fokus på ensamhet i gruppen äldre personer. En systematisk översikt visar att det finns god kunskap om en del faktorer som ökar risken för ensamhet, men mer forskning behövs om andra potentiella riskfaktorer. Analyserna visar en relativt låg och stabil förekomst av ensamhet bland äldre personer i Norden, samt att ohälsa och olika indikatorer för social exkludering (t.ex. bristande sociala relationer, otillräcklig inkomst, samt otrygghet i närområdet) har samband med ensamhet. Slutligen konstateras att forskningen om nordiska interventioner för att minska ensamhet bland äldre personer är begränsad.
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| 9. |
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| 10. |
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| 11. |
- Lembrechts, Jonas J., et al.
(författare)
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Global maps of soil temperature
- 2022
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28:9, s. 3110-3144
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Tidskriftsartikel (refereegranskat)abstract
- Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean=3.0±2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6±2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7±2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.
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| 12. |
- Liu, Johan, 1960, et al.
(författare)
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Stem Cell Growth and Migration on Nanofibrous Polymer Scaffolds and Micro-Fluidic Channels on Silicon-Chip
- 2009
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Ingår i: Proceedings of the 2009 Electronic Components and Technology Conference. - 0569-5503. - 9781424444762 ; , s. 1080-1085
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Konferensbidrag (refereegranskat)abstract
- Stem cell growth and migration on nanofibrous scaffolds and micro-fluidic channels on Silicon-Chip were studied by using neural stem cells isolated from adult rats' brain. Electrospinning and lithographic technique were used for developing nanofibrous-polylactic acid (PLA) and polyurethane (PU) based-scaffolds and micro-fluidic channels on Si-Chips respectively. Immunocytochemical and morphological analysis showed better cell-matrix interaction with profound adhesion, proliferation and migration on the developed scaffolds. Cell culture assay with microfluidic channel revealed the ability of developed channel system in guiding neuronal stem cell growth towards specified directions. These studies extend the possibility of using developed nanofibrous scaffolds and micro-fluidic channel system for future electrical signal transmission based on living neural stem cells.
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| 13. |
- Merinero, Sonia, et al.
(författare)
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Intraspecific variation influences performance of moss transplants along microclimate gradients
- 2020
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 101:5
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Tidskriftsartikel (refereegranskat)abstract
- Identifying the environmental drivers of population dynamics is crucial to predict changes in species abundances and distributions under climate change. Populations of the same species might differ in their responses as a result of intraspecific variation. Yet the importance of such differences remains largely unexplored. We examined the responses of latitudinally distant populations of the forest moss Hylocomiastrum umbratum along microclimate gradients in Sweden. We transplanted moss mats from southern and northern populations to 30 sites with contrasting microclimates (i.e., replicated field common gardens) within a forest landscape, and recorded growth and survival of individual shoots over 3 yr. To evaluate the importance of intraspecific variation in responses to environmental factors, we assessed effects of the interactions between population origin and microclimate drivers on growth and survival. Effects on overall performance of transplanted populations were estimated using the product of survival and growth. We found differences between southern and northern populations in the response to summer temperature and snowmelt date in one of three yearly transitions. In this year, southern populations performed better in warm, southern-like conditions than in cold, northern-like conditions; and the reverse pattern was true for northern populations. Survival of all populations decreased with evaporation, consistent with the high hydric demands and poikilohydric nature of mosses. Our results are consistent with population adaptation to local climate, and suggest that intraspecific variation among populations can have important effects on the response of species to microclimate drivers. These findings highlight the need to account for differential responses in predictions of species abundance and distribution under climate change.
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| 14. |
- Tyden, Eva, et al.
(författare)
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Deep amplicon sequencing of preselected isolates of Parascaris equorum in beta-tubulin codons associated with benzimidazole resistance in other nematodes
- 2014
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Ingår i: Parasites & Vectors. - : Springer Science and Business Media LLC. - 1756-3305. ; 7, s. 410-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The development of anthelmintic resistance (AR) to macrocyclic lactones in the equine roundworm Parascaris equorum has resulted in benzimidazoles now being the most widely used substance to control Parascaris infections. However, over-reliance on one drug class is a risk factor for the development of AR. Consequently, benzimidazole resistance is widespread in several veterinary parasites, where it is associated with single nucleotide polymorphisms (SNPs) in drug targets encoded by the beta-tubulin genes. The importance of these SNPs varies between different parasitic nematodes, but it has been hypothesised that they occur, at low allele frequencies, even in unselected populations. This study investigated whether these SNPs exist in the P. equorum population and tested the hypothesis that BZ resistance can develop from pre-existing SNPs in codons 167, 198 and 200 of the beta-tubulin isotype 1 and 2 genes, reported to be associated with AR in strongylids. The efficacy of the oral paste formula fenbendazole on 11 farms in Sweden was also assessed. Methods: Two isotype-specific primer pairs were designed, one on either side of the codon 167 and one on either side of codons 198 and 200. A pool of 100 000 larvae was sequenced using deep amplicon sequencing by Illumina HiSeq. Faecal egg count reduction test was used to assess the efficacy of fenbendazole. Results: No SNPs were observed in codons 167, 198 or 200 of the beta-tubulin isotype 1 or 2 genes of P. equorum, even though 100 000 larvae were sequenced. Faecal egg count reduction testing of fenbendazole showed that this anthelmintic was still 100% effective, meaning that the likelihood of finding high allele frequency of SNPs associated with benzimidazoles resistance in P. equorum was low. Unexpectedly, the allele frequencies observed in single worms were comparable to those in pooled samples. Conclusions: We concluded that fenbendazole does not exert selection pressure on the beta-tubulin genes of isotypes 1 and 2 in P. equorum. The fact that no pre-existing SNPs were found in codons 167, 198 and 200 in P. equorum also illustrates the difficulties in generalising about AR mechanisms between different taxonomic groups of nematodes.
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| 15. |
- Alfredsson, Bo, et al.
(författare)
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The role of a single surface asperity in rolling contact fatigue
- 2008
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 264:9-10, s. 757-762
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Tidskriftsartikel (refereegranskat)abstract
- The effect of contact loading of single surface irregularities, i.e. asperities, as an underlying mechanism for surface initiated rolling contact fatigue was investigated numerically using FEM. Spalls in the teeth flanks of driving gear wheels were investigated for typical spalling crack initiation properties. The spalling entry angle was documented and some spalls with a convex entry tip were found. The residual surface stresses of the used teeth, with spalls, were measured with the hole drilling technique. The gear contact close to the rolling circle was modelled as two rolling cylinders. A single asperity was introduced into the contact surface of one of them. Due to the presence of the asperity a three dimensional contact model was required. The material description included J(2)-plasticity with isotropic and linear hardening. The simulation included residual stresses from material heat treatment. The first roll cycle introduced plastic deformation which altered the residual stresses. Thus, the stress results were captured during a second roll cycle. The most important result was that asperities will serve as local stress raisers in the contact surfaces. The computed stress cycle at the asperity was compared to stress cycles that gave ring/cone cracks at point loaded experiments. The principal stress trajectory into the material was compared to the cross-section profiles of the spalling entry and ring/cone crack. The surface stress profile at the asperity was compared to the convex surface profiles of the spalling tip and ring/cone crack. The asperity deformation and change in residual surface stresses from moderate plastic deformation during rolling were estimated.
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| 16. |
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| 17. |
- Ameur, Adam, et al.
(författare)
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De Novo Assembly of Two Swedish Genomes Reveals Missing Segments from the Human GRCh38 Reference and Improves Variant Calling of Population-Scale Sequencing Data
- 2018
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Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 9:10
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Tidskriftsartikel (refereegranskat)abstract
- The current human reference sequence (GRCh38) is a foundation for large-scale sequencing projects. However, recent studies have suggested that GRCh38 may be incomplete and give a suboptimal representation of specific population groups. Here, we performed a de novo assembly of two Swedish genomes that revealed over 10 Mb of sequences absent from the human GRCh38 reference in each individual. Around 6 Mb of these novel sequences (NS) are shared with a Chinese personal genome. The NS are highly repetitive, have an elevated GC-content, and are primarily located in centromeric or telomeric regions. Up to 1 Mb of NS can be assigned to chromosome Y, and large segments are also missing from GRCh38 at chromosomes 14, 17, and 21. Inclusion of NS into the GRCh38 reference radically improves the alignment and variant calling from short-read whole-genome sequencing data at several genomic loci. A re-analysis of a Swedish population-scale sequencing project yields > 75,000 putative novel single nucleotide variants (SNVs) and removes > 10,000 false positive SNV calls per individual, some of which are located in protein coding regions. Our results highlight that the GRCh38 reference is not yet complete and demonstrate that personal genome assemblies from local populations can improve the analysis of short-read whole-genome sequencing data.
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| 18. |
- Anderberg, Mats, 1961-, et al.
(författare)
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Mer än varannan ungdom med alkohol- och narkotikaproblem i öppenvården har erfarenhet av utsatthet i barndomen
- 2019
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Ingår i: Socialmedicinsk Tidskrift. - Stockholm : Karolinska Institutet. - 0037-833X. ; 96:6, s. 786-799
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Tidskriftsartikel (refereegranskat)abstract
- Det finns idag få svenska studier som undersöker erfarenheter av utsattheti barndom hos ungdomar med drogproblem, särskilt inom öppenvården.Den här studien analyserade erfarenheter av försummelse och övergreppunder barndomen hos ungdomar (medelålder 18 år) som påbörjat öppenvårdsbehandlingför drogproblem. Resultaten visade att många ungdomarhade erfarenheter av försummelse och övergrepp i barndomen. Erfarenhetav utsatthet i barndomen var också relaterat till upplevda problem i uppväxtfamiljen,t.ex. ekonomiska svårigheter, missbruk, psykisk ohälsa och våld ifamiljen. Resultaten pekar på att det är angeläget att även utreda utsattheti barndomen bland ungdomar i behandling för drogproblem, särskilt då det idag finns god evidens för att psykiatrisk samsjuklighet (t.ex. traumareaktionoch drogproblem) bör behandlads samtidigt för att uppnå bäst effekt.
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| 19. |
- Anderberg, Mats, et al.
(författare)
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Mer än varannan ungdom med alkohol- och narkotikaproblem i öppenvården har erfarenhet av utsatthet i barndomen
- 2019
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Ingår i: Socialmedicinsk Tidskrift. - 0037-833X. ; 96:6, s. 786-799
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Tidskriftsartikel (refereegranskat)abstract
- Few Swedish studies investigated experiences of childhood maltreatment in adolescents with substance use problems, especially in outpatient care. This study analyzed experiences of neglect and abuse during childhood in adol- escents (mean age 18 years) who started outpatient treatment for substance use problems. The results showed that several of them had experience of child maltreatment. Child maltreatment was also related to perceived pro- blems in the upbringing family, e.g. financial difficulties, substance use pro- blems, mental illness and violence in the family. This indicate the importance to investigate experiences of child maltreatment among adolescents in tre- atment for substance use problems, especially since there is evidence to- day that psychiatric co-morbidity (e.g. trauma reaction and drug problems) should be treated simultaneously to achieve the best effect.
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| 20. |
- Angelstam, Per, et al.
(författare)
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Evidence-Based Knowledge Versus Negotiated Indicators for Assessment of Ecological Sustainability : The Swedish Forest Stewardship Council Standard as a Case Study
- 2013
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 42:2, s. 229-240
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Tidskriftsartikel (refereegranskat)abstract
- Assessing ecological sustainability involves monitoring of indicators and comparison of their states with performance targets that are deemed sustainable. First, a normative model was developed centered on evidence-based knowledge about (a) forest composition, structure, and function at multiple scales, and (b) performance targets derived by quantifying the habitat amount in naturally dynamic forests, and as required for presence of populations of specialized focal species. Second, we compared the Forest Stewardship Council (FSC) certification standards' ecological indicators from 1998 and 2010 in Sweden to the normative model using a Specific, Measurable, Accurate, Realistic, and Timebound (SMART) indicator approach. Indicator variables and targets for riparian and aquatic ecosystems were clearly under-represented compared to terrestrial ones. FSC's ecological indicators expanded over time from composition and structure towards function, and from finer to coarser spatial scales. However, SMART indicators were few. Moreover, they poorly reflected quantitative evidence-based knowledge, a consequence of the fact that forest certification mirrors the outcome of a complex social negotiation process.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Boson, Karin, 1984, et al.
(författare)
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Adolescents with substance use problems in outpatient treatment: a one-year prospective follow-up study focusing on mental health and gender differences
- 2022
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Ingår i: Substance Abuse Treatment, Prevention, and Policy. - : Springer Science and Business Media LLC. - 1747-597X. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Although several studies have found a high incidence of coexisting mental health problems among adolescents with substance use problems, follow-up studies addressing how these conditions change over time are rare. The study will describe and analyze indications of mental health problems and how various risk factors predict outcomes 1 year after initial treatment contact. In addition, gender-specific risk factors are explored. Methods A clinical sample of 455 adolescents (29% girls, median age 17 years) answered a structural interview at baseline and were followed up using official records 1 year after initiated treatment. Bivariate associations and logistic regressions were conducted to analyse the links between risk factors at the individual, social, and structural levels as well as links between various mental illness symptoms at treatment start and indications of mental health problems 1 year later were analysed. Results The results show that mental health problems among adolescents largely persisted 1 year after start of outpatient care for substance use problems. Forty-two per cent of the sample displayed indications of mental health problems at follow-up, and registrations for both outpatient treatment and psychiatric medication were more common among the girls. Girls also reported more mental illness symptoms at treatment start than boys did, especially anxiety. Depression and suicidal thoughts had predictive values regarding indications of mental health problems and small cumulative effects were found for 6-10 co-occurring risk factors. Conclusions Adolescents with depression and suicidal thoughts at treatment start should yield attention among clinicians as these general risk factors could predict indication of mental health problems at 1 year follow-up effectively. Also, patients with more than six co-occurring risk factors seem more vulnerable for continued mental health problems. Generally, girls displayed a greater mental health and psychosocial burden at treatment initiation and were more likely to show indication of mental health problems at follow-up. These results suggests that girls are more likely to get psychiatric out-treatment parallel to, or after, substance abuse treatment. We recommend further investigation of gender differences and gender-specific needs in substance use treatment.
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| 25. |
- Caldenby, Claes, 1946, et al.
(författare)
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Architecture and Engineering - 10 Years Anniversary Book
- 2016
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A Jubilee Book will tell our story, a common share of moments and activities, thoughts and reflections, from 10 years of Architecture and Engineering, in short AT. A creative mixture of strong professional cultures, a desire and an enthusiasm for searching out and taking on the challanges of the future in architecture and engineering of the built environment.
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| 26. |
- Callaghan, Terry, et al.
(författare)
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Multi-Decadal Changes in Tundra Environments and Ecosystems : Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)
- 2011
-
Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:6, s. 705-716
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the responses of tundra systemsto global change has global implications. Most tundraregions lack sustained environmental monitoring and oneof the only ways to document multi-decadal change is toresample historic research sites. The International PolarYear (IPY) provided a unique opportunity for such researchthrough the Back to the Future (BTF) project (IPY project#512). This article synthesizes the results from 13 paperswithin this Ambio Special Issue. Abiotic changes includeglacial recession in the Altai Mountains, Russia; increasedsnow depth and hardness, permafrost warming, andincreased growing season length in sub-arctic Sweden;drying of ponds in Greenland; increased nutrient availabilityin Alaskan tundra ponds, and warming at mostlocations studied. Biotic changes ranged from relativelyminor plant community change at two sites in Greenland tomoderate change in the Yukon, and to dramatic increasesin shrub and tree density on Herschel Island, and in subarcticSweden. The population of geese tripled at one sitein northeast Greenland where biomass in non-grazed plotsdoubled. A model parameterized using results from a BTFstudy forecasts substantial declines in all snowbeds andincreases in shrub tundra on Niwot Ridge, Colorado overthe next century. In general, results support and provideimproved capacities for validating experimental manipulation,remote sensing, and modeling studies.
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| 27. |
- Christensen, Love, et al.
(författare)
-
Changes and Fluctuations in Issue Ownership: The Case of Sweden, 1979–2010
- 2015
-
Ingår i: Scandinavian Political Studies. - : Wiley. - 0080-6757 .- 1467-9477. ; 38:2, s. 137-157
-
Tidskriftsartikel (refereegranskat)abstract
- Issue ownership (IO) is an important concept in the analysis of party behaviour, party strategy and party competition for several decades. More recently, it has also been of growing interest to research on voting behaviour. Traditionally, IO has been regarded as a stable phenomenon where parties have different profiles and are advantaged by different political issues or issueareas. However, recently many studies have reported change and fluctuations concerning IO, and the same studies also makes it clear that we know surprisingly little about what might cause, or facilitate, change in issue ownership. In fact, we do not even have systematic studies of how stable issue ownership usually is, or how frequent clear shifts in issue ownership actually are.The aim of this article is to explore the extent of change and stability in issue ownership in Sweden. For this purpose, the Swedish national election studies from 1979 to 2010 are utilised. Hence, in light of more recent research that has delivered some tentative indications of that changes in issue ownership have increased over time, this is nothing that is supported in the Swedish case. Instead, issue ownership seems never to have been a particularly stable phenomenon in general. Moreover, these results demonstrate that the ownership in economic issues are more volatile compared to others kind of issues, something which is well in line with the theoretical expectations outlined in the article since performance issues should be more sensitive to changes in voter evaluations.
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| 28. |
- Dahlberg, Anders, et al.
(författare)
-
786 svampar på 2015 års rödlista
- 2015
-
Ingår i: Svensk Mykologisk Tidskrift. - 1653-0357. ; 36, s. 91-97-
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- A new Swedish Red List was published April 28th 2015 by the Swedish Species Information Centre in which 786 species of fungi are listed. Compared to the previous Red List published in 2010, 11 species have been down-listed, 51 species have been added and 35 species have changed names or taxonomic rank, thus the list has increased by 41. The changes are mainly due to increased knowledge of taxonomy, ecology and distribution, not to changes in the sta-tus of the species. Here, the members of the Species Specialist Group for Fungi 2011 – 2015 summarize the results of the red listing.
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| 29. |
- Dahlberg, Anders, et al.
(författare)
-
Modelled impact of Norway spruce logging residue extraction on biodiversity in Sweden
- 2011
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Ingår i: Canadian Journal of Forest Research. - 0045-5067 .- 1208-6037. ; 41, s. 1220-1232
-
Tidskriftsartikel (refereegranskat)abstract
- Logging residues are increasingly being extracted for bioenergy purposes. This study estimates how extraction of fine woody debris (FWD) may affect the overall habitat availability for 577 species of wood-and bark-inhabiting basidiomycetes, beetles, and lichens in Sweden using Norway spruce (Picea abies (L.) Karst.) as their primary substrate. We combined modeling of (i) the amount of various types of woody debris available throughout a forest rotation in managed forests with (ii) a classification of each species' associations with different types of wood. In three different regions, we compared a scenario with no logging residue extraction with three different levels of extraction. Our results suggest that the extraction may cause a 35%-45% reduction in aboveground FWD and a more than 20% decline in the potential amount of substrate for about 50% of the species (affecting basidiomycetes and beetles more than lichens). The intensified forestry during the last century has, however, steadily increased the production of FWD. Furthermore, no red-listed species is primarily associated with logging residues of Norway spruce. Therefore, the current situation in Sweden with extraction of 70% of Norway spruce FWD on 50% of the clearcuts probably constitutes a minor contribution to the regional extinction risks.
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| 30. |
- Dahlberg, Anders, et al.
(författare)
-
Svampar Fungi
- 2020
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Ingår i: Rödlistade arter i Sverige 2020. - 9789187853548 ; , s. 67-88
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 31. |
- Dahlberg, Anders, et al.
(författare)
-
Svampar Fungi
- 2015
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Ingår i: Rödlistade arter i Sverige 2015. - 9789187853104 ; , s. 53-71
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 32. |
- Dahlberg, C. Johan, 1978-, et al.
(författare)
-
Population differentiation in timing of development in a forest herb associated with local climate and canopy closure
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Our knowledge of how plant seasonal development is related to local versus larger-scale environmental variation is limited. We investigated differentiation in the timing of vegetative and reproductive development among populations of the forest herb Lathyrus vernus over different spatial scales. We predicted earlier development and shorter development time for populations from a colder, northern region compared to populations from a warmer, southern region. Also, we predicted earlier and shorter development within regions to be associated with colder temperatures and higher proportions of deciduous trees at their sites of origin. Lastly, we predicted that earlier flowering is strongly correlated with earlier start of development. To examine these predictions, we conducted a common garden study, and compared the development of 10 northern and 10 southern Swedish L. vernus populations. Start of development, development time and start of flowering did not differ between populations from the two regions in contrast to our prediction. Within the southern region, start of flowering was earlier in populations from colder sites, while start of development was earlier with colder temperatures within the northern region. Start of flowering occurred earlier in southern populations from sites with higher proportion of deciduous trees. Thus, the prediction for the timing of development within regions was partly confirmed. However, vegetative and reproductive development was not simultaneously influenced by temperature and proportion of deciduous trees within regions, possibly due to the negative correlation between vegetative growth and development time. This implies that earlier start of development or shorter development time not necessarily correspond to earlier start of flowering or vice versa. Overall, the results suggest that smaller scale effects within region, such as temperature and interspecific competition for light, was more important for the timing of development than the larger scale gradients between regions. Lastly, the population differentiation across gradients of temperature and proportion of deciduous trees implies that populations may adapt to long-term changes in light or climatic conditions, and differ in their short-term response to climate change.
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| 33. |
- Dahlberg-Grundberg, Michael, 1983-, et al.
(författare)
-
Extending the local : activist types and forms of social media use in the case of an anti-mining struggle
- 2017
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Ingår i: Social Movement Studies. - : Informa UK Limited. - 1474-2837 .- 1474-2829. ; 16:3, s. 309-322
-
Tidskriftsartikel (refereegranskat)abstract
- As political activists increasingly use social media in local protests, scholars must redirect attention from large-scale campaigns to scrutinize the ways in which geographically confined actors use social media to engage in protests. This paper analyses how a 2013 anti-mining campaign in Kallak, Sweden, combined on-site resistance with social media strategies via Facebook-pages. The study examines which activist roles and forms of social media use that emerged and aims to explore what larger practical and theoretical implications one can derive from this specific case of place-based struggles. Results show that three typologically distinct activist roles emerged during the protests: local activists, digital movement intellectuals and digital distributors. These different types of actors were involved in four different forms of social media use: mobilization, construction of the physical space, extension of the local and augmentation of local and translocal bonds. Based on our findings, we argue that the coming together of these different activist roles and the different uses of social media added a translocal dimension to the peripheral and physically remote political conflict in Kallak. Media users were able to extend a locally and physically situated protest by linking it to a global contentious issue such as the mining boom and its consequences for indigenous populations.
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| 34. |
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| 35. |
- Dahlberg, Josef, et al.
(författare)
-
Absence of changes in the milk microbiota during Escherichia coli endotoxin induced experimental bovine mastitis
- 2023
-
Ingår i: Veterinary research (Print). - : BioMed Central (BMC). - 0928-4249 .- 1297-9716. ; 54
-
Tidskriftsartikel (refereegranskat)abstract
- Changes in the milk microbiota during the course of mastitis are due to the nature of a sporadic occurring disease difficult to study. In this study we experimentally induced mastitis by infusion of Escherichia coli endotoxins in one udder quarter each of nine healthy lactating dairy cows and assessed the bacteriological dynamics and the milk microbiota at four time points before and eight time points after infusion. As control, saline was infused in one udder quarter each of additionally nine healthy cows that followed the same sampling protocol. The milk microbiota was assessed by sequencing of the 16 S rRNA gene and a range of positive and negative controls were included for methodological evaluation. Two different data filtration models were used to identify and cure data from contaminating taxa. Endotoxin infused quarters responded with transient clinical signs of inflammation and increased SCC while no response was observed in the control cows. In the milk microbiota data no response to inflammation was identified. The data analysis of the milk microbiota was largely hampered by laboratory and reagent contamination. Application of the filtration models caused a marked reduction in data but did not reveal any associations with the inflammatory reaction. Our results indicate that the microbiota in milk from healthy cows is unaffected by inflammation.
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| 36. |
- Dahlberg, Johan, et al.
(författare)
-
An uncertain uphill battle : experiences and consequences of living with lipedema
- 2024
-
Ingår i: International Journal of Qualitative Studies on Health and Well-being. - : Taylor & Francis. - 1748-2623 .- 1748-2631. ; 19:1
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To describe and analyse experiences of living with lipedema. Methods: Individual, semi-structured interviews with a purposive sample of 12 women diagnosed with lipedema and analysed by qualitative content analysis utilizing an inductive approach.Results: The overarching theme, “An uncertain uphill battle against a divergent body and societal ignorance”, covers the experiences of living with lipedema and is based on five categories; “Captivated by a disintegrating body”, “Face the impairments of a chronic condi-tion”, “Experience social exclusion”, “Need emotional support to go on” and “Mull over an insecure future”. The women felt entrapped within their bodies and experienced social exclusion due to the chronic symptoms and the progressive body shape alteration caused by their illness. Having experienced deficient information on the illness, varying support from other people, and a deteriorating economic situation, the women face an uncertain future.Conclusions: Symptoms and restrictions caused by lipedema affect women’s livelihood and future, as there are no indications for disease improvement. Preventive work aimed at reducing health deterioration should be a priority. More research is needed to raise health-care awareness regarding difficulties experienced by patients with lipedema.
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| 37. |
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| 38. |
- Dahlberg, Johan, et al.
(författare)
-
Changing seasonal variation in births by sociodemographic factors : a population-based register study
- 2018
-
Ingår i: Human Reproduction Open. - : Oxford University Press (OUP). - 2399-3529. ; :4
-
Tidskriftsartikel (refereegranskat)abstract
- STUDY QUESTION: Have seasonal variations in births by factors related to maternal education, age, parity and re-partnering changedover a 72-year period? SUMMARY ANSWER: Seasonal variation in births has been reduced overall but also changed its pattern over the last seven decades. WHAT IS KNOWN ALREADY: The number of births varies markedly by season, but the causes of this variation are not fully understood.Seasonality of births is, in some populations, strongly influenced by sociodemographic factors. STUDY DESIGN SIZE, DURATION: A longitudinal study design was used by analysing the seasonal variation in live births between 1940and 2012, and relating it to mothers’ sociodemographic characteristics at the time of childbirth (maternal education, age, parity and repartnering). PARTICIPANTS/MATERIALS, SETTING, METHODS: Register data on 6 768 810 live births in Sweden between 1940 and 2012were used. Information on biological parents are available for more than 95% of all births. Multinomial logistic regressions were used to calculatepredicted probabilities of giving birth for each calendar month. MAIN RESULTS AND THE ROLE OF CHANCE: Between 1940 and 1999, Swedish birth rates showed the typical seasonal variationwith high numbers of births during the spring, and low numbers of births during the last quarter of the year. However, during the 21st century,the seasonal variation in fertility declined so that only minor variation in birth rates between February and September now remains. Still, thepattern of low birth rates at the end of the year remains and has even become more pronounced from the 1980s onwards. The characteristic‘Christmas effect’ that used to be visible in September has vanished over the last 30 years. The roles in seasonal variation of maternal education,the mother’s age, parity and instances where the mother has re-partnered between subsequent births changed during the second half ofthe 20th century. From 1980s onwards, the decline in birth rates during the last quarter of the year became particularly pronounced amonghighly educated mothers. Over the 72 years studied, the seasonal variation among first-time mothers declined steadily and has almost disappearedat the end of the study period. Using data that cover ~180 000 births in each month, all meaningful results are statistically significant. LIMITATIONS REASONS FOR CAUTION: The study uses data from one Nordic country only, making it difficult to draw conclusionsthat may hold for other countries. WIDER IMPLICATIONS OF THE FINDINGS: The typical seasonal variation reported for Sweden between 1940 and 1999, with highnumbers of births during the spring and low numbers of births during the last quarter of the year, is in line with results from most otherEuropean countries during the same time period. However, the significant decline in seasonal variation in the early 21st century is a noveldevelopment. The study underlines that in a society with low fertility and efficient birth control, active choices and behaviours associated withan individual’s sociodemographic characteristics tend to matter more for the seasonal timing of childbearing than environmental factorsrelated to the physiological ability to reproduce and cultural–behavioural factors related to the frequency of intercourse.
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| 39. |
- Dahlberg, Johan, 1978-
(författare)
-
Death Is Not the End : A Register-Based Study of the Effect of Parental Death on Adult Children’s Childbearing Behavior in Sweden
- 2020
-
Ingår i: Omega. - : SAGE Publications. - 0030-2228 .- 1541-3764. ; 81:1, s. 80-106
-
Tidskriftsartikel (refereegranskat)abstract
- Macro-level studies have shown that rapid increases in mortality can affect fertility rates. Parental death has also been linked to negative psychological and physical outcomes, reduced relationship quality, and making bereaved children attach more importance to their families. No prior study has examined whether parental death influences adult children’s fertility at the microlevel. This study applies event history techniques to Swedish multigeneration registers listing 1.5 million individuals with micro data on mortality and fertility to investigate short-term (first birth risk) and long-term (childlessness at age 45) effects of parental death on adult children’s fertility. The principal finding is that parental death during reproductive age affects children’s fertility and this effect is mainly short term. The effects differ to some degree between men and women and depend on the stage of the life course in which the bereavement occurs. Younger individuals experiencing a parental death have a significantly higher first birth risk after the parental death compared with peers who did not experience a parental death. Individuals older than 23 who experience a parental death have no or lower first birth risk after the parental death compared with baseline. Men, compared with women, are more likely to end childless if they experience a parental death.
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| 40. |
- Dahlberg, Johan, 1978-
(författare)
-
Does Parental Death Affect Fertility? A Register-Based Study of the Effect of Parental Death on Adult Children's Childbearing Behavior in Sweden
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Even though fertility and mortality are two of demography’s most researched topics, no prior study has examined at the micro level whether parental death influencesadult children’s fertility. Macro-level studies have shown that rapid increases in mortality can affect fertility rates. Parental death has also been linked to negative psychological and physical outcomes, reduced relationship quality, and making a bereaved child attach more importance to his/her family. This study applies event history techniques to Swedish multi-generation registers containing 1.5 million individuals with to micro data on mortality and fertility to investigate short-term (first birth risk) and long-term (childlessness at age 45) effects of parental death on adult children's fertility. The principal finding is that parental death during reproductive age affects children’s fertility and this effect is mainly short-term. The effects differ to some degree between men and women and depend on when in the life course the bereavement happens.
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| 41. |
- Dahlberg, Johan, 1978-, et al.
(författare)
-
Explaining Swedish sibling similarity in fertility : Parental fertility behavior vs. social background
- 2018
-
Ingår i: Demographic Research. - 1435-9871. ; 39, s. 883-896
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of this descriptive study is to determine which of the family-specific factors, parental fertility behavior or social background, matters most for the intergenerational transmission of fertility.Methods: Brother and sister correlations in age at first birth and final family size were estimated using multilevel linear regression on data covering 242,976 Swedish men and women born between 1958 and 1967. To explore how much of siblings’ similarity in fertility can be explained by parental fertility behavior (age at parenthood and number of children) and social background, we analyzed the decrease in sibling correlation when these family-specific factors were added to the unconditional models.Results: We found that most of siblings’ similarity in fertility could not be explained by parental fertility behavior and social background, but that they explained a substantive part of siblings’ similarities in age at first birth and a smaller but non-negligible part of siblings’ similarities in completed fertility. Parental fertility behavior and social background explain as much (about 36%) of brothers’ and sisters’ similarities in age at first birth. Parental fertility behavior matters more than social background for sisters’ similarities in completed family size. Parental fertility behavior and social background explain about the same (5%) for brothers’ similarities in completed family size.Contribution: This study contributes to the existing understanding of intergenerational transmission of fertility; both methodologically, by introducing a new method to estimate the impact of specific factors shared by siblings, and by determining how much of siblings’ resemblance in fertility can be explained by parental fertility behavior and social background.
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| 42. |
- Dahlberg, Johan, 1978-
(författare)
-
Family influence in fertility : A longitudinal analysis of sibling correlations in first birth risk and completed fertility among Swedish men and women
- 2013
-
Ingår i: Demographic Research. - 1435-9871. ; 29, s. 233-246
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND The intergenerational transmission of fertility has received much attention in demography. This has been done by estimating the correlation between parents' and offsprings' fertility. An alternative method that provides a more comprehensive account of the role of family background - sibling correlations - has not been used before. OBJECTIVE I estimate the overall importance of family background on entry into parenthood and completed fertility and whether it changed over time. Furthermore, I compare the intergenerational correlation in completed fertility with corresponding sibling correlations. METHODS Brother and sister correlations in first birth hazard and in final family size were estimated using multi-level event-history and multi-level linear regression on Swedish longitudinal register data. RESULTS The overall variation in fertility that can be explained by family of origin is approximately 15%-25% for women and 10%-15% for men. The overall importance of the family of origin has not changed over the approximately twenty birth cohorts that were studied (1940-63 for women, 1940-58 for men). Parents' completed fertility accounts for only a small share of the total family background effect on completed fertility. CONCLUSIONS This study contributes to the existing understanding of intergenerational transition of fertility, both methodologically, by introducing a new and powerful method to study the overall importance of family of origin, and substantially, by estimating the overall importance of family of origin and its development over time. A non-negligible proportion of the variation in fertility can be attributed to family of origin and this effect has remained stable over twenty birth cohorts.
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| 43. |
- Dahlberg, Johan, et al.
(författare)
-
Fecundity and human birth seasonality in Sweden : a register-based study
- 2019
-
Ingår i: Reproductive Health. - : Springer Science and Business Media LLC. - 1742-4755. ; 16
-
Tidskriftsartikel (refereegranskat)abstract
- Background: It is well-established that couples' fecundities vary widely. Each couple has a relatively constant monthly probability of conceiving, which can vary from zero to quite high. This underlying probability is usually expressed as the time (number of menstrual cycles) the couple requires to conceive. Couples with high fecundity will, on average, need fewer cycles than couples with low fecundity. It is also well-documented that almost all human populations exhibit seasonal variation in births. Most European countries show seasonal variation that usually peak in the spring and are the lowest during the last quarter of the year. The increasingly strong pattern of depressed birth rates in November and December is likely explained by the December-January cut-off threshold for Swedish pupils' school entry and their parents increasing awareness of the negative effects on school outcomes for children who are juniors in the school-entry cohort they belong to. To actively plan births for a specific time of the year, couples need to have some knowledge of the time required for them to conceive.Methods: We use the duration between marriage of childless couples and first birth as a proxy measure of couples' fecundity. Based on this time-to-pregnancy measure we study to what extent couples' capacity to conceive affects the seasonality of their second births. We hypothesize that in a society with highly controlled fertility and a strong norm of having at least two children, sub-fertile couples will on average show less seasonal variation in second births. Sub-fertile couples, requiring more time to conceive the first time, will be less likely to try to target a desired birth month for their second child because doing so could jeopardize fulfilling their desired family size. We apply multinomial logistic regressions on 81,998 Swedish couples who married while being childless and subsequently gave birth to at least two children between 1990 and 2012, to investigate fecundity's role in seasonal variation in second births.Results: We found that seasonal variation in second births was strongly associated with couples' observed fecundity, measured as the duration between marriage formation and first birth. Our results support the hypothesis that sub-fertile couples, requiring more time to conceive the first time, show less seasonal variation in second births. The seasonal variations in second order births among couples with normal fecundity shows some similarities to traditional patterns as seen in agricultural and industrial societies of the past, with high numbers of births during the spring, and low numbers during the last quarter of the year. However, two important differences are notable. The characteristic Christmas peak in September has vanished, and the low birth rates in November and December come out much stronger than in the past.Conclusions: The birth seasonality among couples with normal fecundity are what we would expect if couples actively plan their births according to the cut-off date for Swedish pupils' school entry. We argue that our findings support the notion that scheduled childbirth is a reality in contemporary sociality.
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| 44. |
- Dahlberg, Johan, 1988-
(författare)
-
Genetic Cartography at Massively Parallel Scale
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Massively parallel sequencing (MPS) is revolutionizing genomics. In this work we use, refine, and develop new tools for the discipline.MPS has led to the discovery of multiple novel subtypes in Acute Lymphoblastic Leukemia (ALL). In Study I we screen for fusion genes in 134 pediatric ALL patients, including patients without an assigned subtype. In approximately 80% of these patients we detect novel or known fusion gene families, most of which display distinct methylation and expression patterns. This shows the potential for improvements in the clinical stratification of ALL. Large sample sizes are important to detect recurrent somatic variation. In Study II we investigate if a non-index overlapping pooling schema can be used to increase sample size and detect somatic variation. We designed a schema for 172 ALL samples and show that it is possible to use this method to call somatic variants.Around the globe there are many ongoing and completed genome projects. In Study III we sequenced the genome of 1000 Swedes to create a reference data set for the Swedish population. We identified more than 10 million variants that were not present in publicly available databases, highlighting the need for population-specific resources. Data, and the tools developed during this study, have been made publicly available as a resource for genomics in Sweden and abroad.The increased amount of sequencing data has created a greater need for automation. In Study IV we present Arteria, a computational automation system for sequencing core facilities. This system has been adopted by multiple facilities and has been used to analyze thousands of samples. In Study V we developed CheckQC, a program that provides automated quality control of Illumina sequencing runs. These tools make scaling up MPS less labour intensive, a key to unlocking the full future potential of genomics.The tools, and data presented here are a valuable contribution to the scientific community. Collectively they showcase the power of MPS and genomics to bring about new knowledge of human health and disease.
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| 45. |
- Dahlberg, Johan, et al.
(författare)
-
Influence of a single axisymmetric asperity on surface stresses during dry rolling contact
- 2007
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Ingår i: International Journal of Fatigue. - : Elsevier BV. - 0142-1123 .- 1879-3452. ; 29:5, s. 909-921
-
Tidskriftsartikel (refereegranskat)abstract
- The effect from contact loading of some single axisymmetric asperities as a potential mechanism for surface initiated rolling contact fatigue was investigated numerically using FEM. Computational results were compared to properties of some rolling contact fatigue craters, or spalls, in the teeth surfaces of four driving gear wheels. The gears were geometrically identical but had experienced slightly varying load conditions. The residual surface stresses of a used teeth with spalls were measured using the hole drilling technique. The combined cylinder asperity contact was first modelled with a stationary model in which an asperity was introduced at the contact rim. By varying asperity height, width, position and contact load dangerous asperity configurations were sought for. The gear contact close to the rolling circle was modelled as two rolling cylinders. A single asperity was introduced into the contact surface of one of them. Due to the presence of the asperity a three-dimensional contact model was required. The simulation included residual stresses from heat treatment and plastic deformation due to the first roll cycle. Thus, the stress results were computed from the second roll cycle. The important overall conclusion was that a single asperity may serve as a stress raiser in the contact surfaces. Furthermore, the computed values of the increased surface stresses were comparable to those that are reported in the literature to give cracks. Example of dangerous asperity dimensions were noted and changes in residual stresses from moderate plastic deformation during rolling were estimated. The asperity deformed plastically during over-roll but remained sufficiently high. The trajectory of the largest principal stress was computed, starting from the position in front of a loaded asperity with maximum tensile stress. The trajectory was compared to the spalling entry angle of a representative spall. For some asperity-cylinder configurations a convex region with large stress was found in the surface. The presence of such a convex stress region was compared to the convex shaped of the spalling tip that sometimes could be found.
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| 46. |
- Dahlberg, Josef, et al.
(författare)
-
Microbiota data from low biomass milk samples is markedly affected by laboratory and reagent contamination
- 2019
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Discoveries of bacterial communities in environments that previously have been described as sterile have in recent years radically challenged the view of these environments. In this study we aimed to use 16S rRNA sequencing to describe the composition and temporal stability of the bacterial microbiota in bovine milk from healthy udder quarters, an environment previously believed to be sterile. Sequencing of the 16S rRNA gene is a technique commonly used to describe bacterial composition and diversity in various environments. With the increased use of 16S rRNA gene sequencing, awareness of methodological pitfalls such as biases and contamination has increased although not in equal amount. Evaluation of the composition and temporal stability of the microbiota in 288 milk samples was largely hampered by background contamination, despite careful and aseptic sample processing. Sequencing of no template control samples, positive control samples, with defined levels of bacteria, and 288 milk samples with various levels of bacterial growth, revealed that the data was influenced by contaminating taxa, primarily Methylobacterium. We observed an increasing impact of contamination with decreasing microbial biomass where the contaminating taxa became dominant in samples with less than 10 4 bacterial cells per mL. By applying a contamination filtration on the sequence data, the amount of sequences was substantially reduced but only a minor impact on number of identified taxa and by culture known endogenous taxa was observed. This suggests that data filtration can be useful for identifying biologically relevant associations in milk microbiota data.
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| 47. |
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| 48. |
- Dahlberg, Josef, et al.
(författare)
-
Microbiota of bovine milk, teat skin, and teat canal: Similarity and variation due to sampling technique and milk fraction
- 2020
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 103, s. 7322-7330
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the effect of sampling technique and milk fraction on bovine milk microbiota data and to compare the microbiota in milk to microbiota on the teat end and in the teat canal. Representative milk samples are highly important for assessment of bacteriological findings and microbiota in milk. Samples were obtained from 5 healthy lactating dairy cows at udder quarter level during 1 milking. Swab samples from the teat. end and teat canal, and milk samples collected using different techniques and in different milk fractions were included. Milk was collected by hand stripping and through a teat canal cannula before and after machine milking, through a trans-teat wall needle aspirate after milking, and from udder quarter composite milk. The microbiota of the samples was analyzed with sequencing of the V1-V3 region of the 16S rRNA gene. In addition, somatic cell counts and bacterial cultivability were analyzed in the milk samples. Microbiota data were analyzed using multivariate methods, and differences between samples were tested using analysis of similarity (ANOSIM). Differences between samples were further explored via individual studies of the 10 most abundant genera. The microbiota on the teat end, in the teat canal, and in udder quarter composite milk, collected using a milking machine, differed in composition from the microbiota in milk collected directly from the udder quarter. No differences in milk microbiota composition were detected between hand-stripped milk samples, milk samples taken through a teat canal cannula, or milk samples taken as a trans-teat wall needle aspirate before or after milking. We conclude that for aseptic milk samples collected directly from the lactating udder quarter, sampling technique or milk fraction has minor effect on the microbiota composition.
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| 49. |
- Dahlberg, Johan, 1977-
(författare)
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On the asperity point load mechanism for rolling contact fatigue
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rolling contact fatigue is a damage process that may arise in mechanical applications with repeated rolling contacts. Some examples are: gears; cams; bearings; rail/wheel contacts. The resulting damage is often visible with the naked eye as millimeter sized surface craters. The surface craters are here denoted spalls and the gear contact served as a case study.The work focused on the asperity point load mechanism for initiation of spalls. It was found that the stresses at asperity level may be large enough to initiate surface cracking, especially if the complete stress cycle was accounted for.The gear contact is often treated as a cylindrical contact. The thesis contains experimental and numerical results connected to rolling contact fatigue of cylindrical contacts. At the outset a stationary cylindrical contact was studied experimentally. The stationary test procedure was used instead of a rolling contact. In this way the number of contact parameters was minimized. The cylindrical contact resulted in four different contact fatigue cracks. The two cracks that appeared first initiated below the contact. The other two cracks developed at the contact surface when the number of load cycles and the contact load increased.The influence of a surface irregularity (asperity) was studied numerically with the Finite Element Method (FEM). Firstly, the stationary contact was modelled and investigated numerically. At the cylindrical contact boundary a single axisymmetric was included. The partially loaded asperity introduced a tensile surface stress, which seen from the asperity centre was radially directed. Secondly, FE simulations were performed where a single axisymmetric asperity was over-rolled by a cylindrical contact. The simulations were performed for pure rolling and rolling with slip. For both situations, tensile forward directed stresses in front of the asperity were found. The presence of slip and a surface traction greatly increased the stresses in front of the asperity. Finally, when rolling started from rest with applied slip, the distance to steady-state rolling was determined for elastic similar cylindrical rollers.
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| 50. |
- Dahlberg, Johan, 1978-
(författare)
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Parents, Children and Childbearing
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis provides a set of studies of social influences on fertility timing. Swedish register data are used to link individuals to their parents and siblings, thereby allowing the study of impacts of family of origin, social background, and parental death on fertility. The Swedish Medical Birth Register is used to investigate the effect of mode of delivery on higher order births. The thesis consists of an introductory chapter with an overview of the consequences and predictors of the timing of childbearing, and a theoretical framework to explain these relationships. This chapter also includes a section where the contribution to existing knowledge, the relation of the findings to life course theory, and suggestion for further research are discussed. This chapter is followed by four original empirical studies. The first study applies sister and brother correlations to investigate and estimate the impact of family of origin on fertility. It shows that family of origin matters for fertility timing and final family size. The study also shows that the overall importance of family of origin has not changed over the approximately twenty birth cohorts that were studied. The second study introduces three dimensions of social background - occupational class, status, and education - into fertility research. It suggests that social background, independent of individuals’ own characteristics, matters for the timing of first birth and the risk of childlessness. The study also shows that different dimensions of social background should not be used interchangeably. The third study uses the Swedish Medical Birth Register to investigate the effect of mode of delivery on the propensity and birth interval of subsequent childbearing. It demonstrates that mode of delivery has an impact on the progression to the second and third births but that a first delivery by vacuum extraction does not reduce the propensity of subsequent childbearing to the same extent as a first delivery by emergency or elective caesarean section. The fourth study explores the effects of parental death on adult children's fertility. The findings reveal that parental death during reproductive ages can affect children’s fertility. The effects are moderated by the gender of the child and when in the life course bereavement occurs. The combined output of these four studies provides evidence that human fertility behavior is embedded in social relationships with kin and friends throughout life. Family of origin, social background, an older sibling's birth, and bereavement following parental death influence the adult child's fertility. These findings add knowledge to previous research on intergenerational and social network influences in fertility.
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