| 1. |
- Abbott, Benjamin W., et al.
(författare)
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Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire : an expert assessment
- 2016
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
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| 2. |
- Frazier-Wood, Alexis C., et al.
(författare)
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Genetic variants associated with subjective well-being, depressive symptoms, and neuroticism identified through genome-wide analyses
- 2016
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Ingår i: Nature Genetics. - : Nature Research (part of Springer Nature). - 1061-4036 .- 1546-1718. ; 48, s. 624-
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Tidskriftsartikel (refereegranskat)abstract
- Very few genetic variants have been associated with depression and neuroticism, likely because of limitations on sample size in previous studies. Subjective well-being, a phenotype that is genetically correlated with both of these traits, has not yet been studied with genome-wide data. We conducted genome-wide association studies of three phenotypes: subjective well-being (n = 298,420), depressive symptoms (n = 161,460), and neuroticism (n = 170,911). We identify 3 variants associated with subjective well-being, 2 variants associated with depressive symptoms, and 11 variants associated with neuroticism, including 2 inversion polymorphisms. The two loci associated with depressive symptoms replicate in an independent depression sample. Joint analyses that exploit the high genetic correlations between the phenotypes (vertical bar(p) over cap vertical bar approximate to 0.8) strengthen the overall credibility of the findings and allow us to identify additional variants. Across our phenotypes, loci regulating expression in central nervous system and adrenal or pancreas tissues are strongly enriched for association.
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| 3. |
- Haas, Brian J., et al.
(författare)
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Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans
- 2009
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 461:7262, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on human history, resulting in famine and population displacement(1). To this day, it affects world agriculture by causing the most destructive disease of potato, the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world's population(1). Current annual worldwide potato crop losses due to late blight are conservatively estimated at $6.7 billion(2). Management of this devastating pathogen is challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars(3,4). Here we report the sequence of the P. infestans genome, which at similar to 240 megabases (Mb) is by far the largest and most complex genome sequenced so far in the chromalveolates. Its expansion results from a proliferation of repetitive DNA accounting for similar to 74% of the genome. Comparison with two other Phytophthora genomes showed rapid turnover and extensive expansion of specific families of secreted disease effector proteins, including many genes that are induced during infection or are predicted to have activities that alter host physiology. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome. This probably plays a crucial part in the rapid adaptability of the pathogen to host plants and underpins its evolutionary potential.
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| 4. |
- Lindblad-Toh, Kerstin, et al.
(författare)
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Genome sequence, comparative analysis and haplotype structure of the domestic dog.
- 2005
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 438:7069, s. 803-19
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Tidskriftsartikel (refereegranskat)abstract
- Here we report a high-quality draft genome sequence of the domestic dog (Canis familiaris), together with a dense map of single nucleotide polymorphisms (SNPs) across breeds. The dog is of particular interest because it provides important evolutionary information and because existing breeds show great phenotypic diversity for morphological, physiological and behavioural traits. We use sequence comparison with the primate and rodent lineages to shed light on the structure and evolution of genomes and genes. Notably, the majority of the most highly conserved non-coding sequences in mammalian genomes are clustered near a small subset of genes with important roles in development. Analysis of SNPs reveals long-range haplotypes across the entire dog genome, and defines the nature of genetic diversity within and across breeds. The current SNP map now makes it possible for genome-wide association studies to identify genes responsible for diseases and traits, with important consequences for human and companion animal health.
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| 5. |
- Smith, Jennifer A, et al.
(författare)
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Genome-wide association study identifies 74 loci associated with educational attainment
- 2016
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Ingår i: Nature (London). - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 533:7604, s. 539-542
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Tidskriftsartikel (refereegranskat)abstract
- Educational attainment is strongly influenced by social and other environmental factors, but genetic factors are estimated to account for at least 20% of the variation across individuals. Here we report the results of a genome-wide association study (GWAS) for educational attainment that extends our earlier discovery sample of 101,069 individuals to 293,723 individuals, and a replication study in an independent sample of 111,349 individuals from the UK Biobank. We identify 74 genome-wide significant loci associated with the number of years of schooling completed. Single-nucleotide polymorphisms associated with educational attainment are disproportionately found in genomic regions regulating gene expression in the fetal brain. Candidate genes are preferentially expressed in neural tissue, especially during the prenatal period, and enriched for biological pathways involved in neural development. Our findings demonstrate that, even for a behavioural phenotype that is mostly environmentally determined, a well-powered GWAS identifies replicable associated genetic variants that suggest biologically relevant pathways. Because educational attainment is measured in large numbers of individuals, it will continue to be useful as a proxy phenotype in efforts to characterize the genetic influences of related phenotypes, including cognition and neuropsychiatric diseases.
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| 6. |
- Tiensuu, Kiira, et al.
(författare)
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RAVEN: a student rocket program at Luleå University of Technology, Sweden
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72nd International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- RAVEN, Rocketry and Aerospace Vehicle Engineering in Norrbotten, is the first rocket project at Luleå University of Technology (LTU), Sweden. The project started in early 2020, and it aims to design, build, test and launch a hybrid propulsion rocket. The initial objectives are to reach an altitude of 10 km with an accompanying payload of 10 kg. The RAVEN team is based at the Kiruna Space Campus and consists of approximately 30 graduate students. The main goal of the first RAVEN rocket is to demonstrate its technology. The team is designing the entire rocket from scratch, including the hybrid propulsion system that uses nitrous oxide as the oxidising agent and paraffin as the solid fuel component, to produce approximately 6 kN of thrust. A modular rocket structure will offer customisation, enabling simple design changes in future iterations. Thus, the layout allows individual subsystems to be re-designed without changes directly affecting others. The project is meant to create a foundation for future student and research rocket projects at LTU. The follow-up developments could further iterate on the first rocket design, increasing hands-on education and providing more collaboration opportunities between the university and the aerospace industry – and eventually provide an in-house platform for research and education at the university or even for commercial start-ups. The infrastructure and resources, such as the proximity to the Esrange Space Center launch facility and support from the university and industry, make Northern Sweden an ideal location to establish a continuous rocket program.
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| 7. |
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| 8. |
- Ahlberg, Erik, et al.
(författare)
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No particle mass enhancement from induced atmospheric ageing at a rural site in northern Europe
- 2019
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- A large portion of atmospheric aerosol particles consists of secondary material produced by oxidation reactions. The relative importance of secondary organic aerosol (SOA) can increase with improved emission regulations. A relatively simple way to study potential particle formation in the atmosphere is by using oxidation flow reactors (OFRs) which simulate atmospheric ageing. Here we report on the first ambient OFR ageing experiment in Europe, coupled with scanning mobility particle sizer (SMPS), aerosol mass spectrometer (AMS) and proton transfer reaction (PTR)-MS measurements. We found that the simulated ageing did not produce any measurable increases in particle mass or number concentrations during the two months of the campaign due to low concentrations of precursors. Losses in the reactor increased with hydroxyl radical (OH) exposure and with increasing difference between ambient and reactor temperatures, indicating fragmentation and evaporation of semivolatile material.
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| 9. |
- Becker, Joel, et al.
(författare)
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Resource profile and user guide of the Polygenic Index Repository
- 2021
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Ingår i: Nature Human Behaviour. - : Nature Research (part of Springer Nature). - 2397-3374. ; 51:6, s. 694-695
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Tidskriftsartikel (refereegranskat)abstract
- Polygenic indexes (PGIs) are DNA-based predictors. Their value for research in many scientific disciplines is growing rapidly. As a resource for researchers, we used a consistent methodology to construct PGIs for 47 phenotypes in 11 datasets. To maximize the PGIs’ prediction accuracies, we constructed them using genome-wide association studies—some not previously published—from multiple data sources, including 23andMe and UK Biobank. We present a theoretical framework to help interpret analyses involving PGIs. A key insight is that a PGI can be understood as an unbiased but noisy measure of a latent variable we call the ‘additive SNP factor’. Regressions in which the true regressor is this factor but the PGI is used as its proxy therefore suffer from errors-in-variables bias. We derive an estimator that corrects for the bias, illustrate the correction, and make a Python tool for implementing it publicly available. © 2021, The Author(s), under exclusive licence to Springer Nature Limited.
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| 10. |
- Beichman, Annabel C, et al.
(författare)
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Aquatic Adaptation and Depleted Diversity : A Deep Dive into the Genomes of the Sea Otter and Giant Otter.
- 2019
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 36:12, s. 2631-2655
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Tidskriftsartikel (refereegranskat)abstract
- Despite its recent invasion into the marine realm, the sea otter (Enhydra lutris) has evolved a suite of adaptations for life in cold coastal waters, including limb modifications and dense insulating fur. This uniquely dense coat led to the near-extinction of sea otters during the 18th-20th century fur trade and an extreme population bottleneck. We used the de novo genome of the southern sea otter (E. l. nereis) to reconstruct its evolutionary history, identify genes influencing aquatic adaptation, and detect signals of population bottlenecks. We compared the genome of the southern sea otter with the tropical freshwater-living giant otter (Pteronura brasiliensis) to assess common and divergent genomic trends between otter species, and with the closely related northern sea otter (E. l. kenyoni) to uncover population-level trends. We found signals of positive selection in genes related to aquatic adaptations, particularly limb development and polygenic selection on genes related to hair follicle development. We found extensive pseudogenization of olfactory receptor genes in both the sea otter and giant otter lineages, consistent with patterns of sensory gene loss in other aquatic mammals. At the population level, the southern sea otter and the northern sea otter showed extremely low genomic diversity, signals of recent inbreeding, and demographic histories marked by population declines. These declines may predate the fur trade and appear to have resulted in an increase in putatively deleterious variants that could impact the future recovery of the sea otter.
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| 11. |
- Berlin, Jonas, et al.
(författare)
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Trajectory Generation for Mobile Robots in a Dynamic Environment using Nonlinear Model Predictive Control
- 2021
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Ingår i: IEEE International Conference on Automation Science and Engineering. - 2161-8070 .- 2161-8089. ; 2021-August, s. 942-947
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Konferensbidrag (refereegranskat)abstract
- This paper presents an approach to collision-free, long-range trajectory generation for a mobile robot in an industrial environment with static and dynamic obstacles. For the long-range planning a visibility graph together with A is used to find a collision-free path with respect to the static obstacles. This path is used as a reference path to the trajectory planning algorithm that in addition handles dynamic obstacles while complying with the robot dynamics and constraints. A Nonlinear Model Predictive Control (NMPC) solver generates a collision-free trajectory by staying close to the initial path but at the same time obeying all constraints. The NMPC problem is solved efficiently by leveraging the new numerical optimization method Proximal Averaged Newton for Optimal Control (PANOC). The algorithm was evaluated by simulation in various environments and successfully generated feasible trajectories spanning hundreds of meters in a tractable time frame.
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| 12. |
- Bouchene, Salim, 1984-, et al.
(författare)
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A Whole-Body Physiologically Based Pharmacokinetic Model for Colistin and Colistin Methanesulfonate in Rat
- 2018
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - : Wiley. - 1742-7835 .- 1742-7843. ; 123:4, s. 407-422
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Tidskriftsartikel (refereegranskat)abstract
- Colistin is a polymyxin antibiotic used to treat patients infected with multidrug-resistant Gram-negative bacteria (MDR-GNB). The objective of this work was to develop a whole-body physiologically based pharmacokinetic (WB-PBPK) model to predict tissue distribution of colistin in rat. The distribution of a drug in a tissue is commonly characterized by its tissue-to-plasma partition coefficient, K-p. Colistin and its prodrug, colistin methanesulfonate (CMS) K-p priors, were measured experimentally from rat tissue homogenates or predicted in silico. The PK parameters of both compounds were estimated fitting invivo their plasma concentration-time profiles from six rats receiving an i.v. bolus of CMS. The variability in the data was quantified by applying a nonlinear mixed effect (NLME) modelling approach. A WB-PBPK model was developed assuming a well-stirred and perfusion-limited distribution in tissue compartments. Prior information on tissue distribution of colistin and CMS was investigated following three scenarios: K-p was estimated using in silico K-p priors (I) or K-p was estimated using experimental K-p priors (II) or K-p was fixed to the experimental values (III). The WB-PBPK model best described colistin and CMS plasma concentration-time profiles in scenario II. Colistin-predicted concentrations in kidneys in scenario II were higher than in other tissues, which was consistent with its large experimental K-p prior. This might be explained by a high affinity of colistin for renal parenchyma and active reabsorption into the proximal tubular cells. In contrast, renal accumulation of colistin was not predicted in scenario I. Colistin and CMS clearance estimates were in agreement with published values. The developed model suggests using experimental priors over in silico K-p priors for kidneys to provide a better prediction of colistin renal distribution. Such models might serve in drug development for interspecies scaling and investigate the impact of disease state on colistin disposition.
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| 13. |
- Bouchene, Salim, 1984-, et al.
(författare)
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Application of a whole-body physiologically based pharmacokinetic model to describe the plasma and urine disposition of colistin and colistin methanesulfonate (CMS) in healthy volunteers
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: The primary aim of this work was to develop a whole-body physiologically based pharmacokinetic (WBPBPK) model to describe CMS and colistin disposition in human plasma and urine. The secondary aim of this analysis was to use the WBPBPK model to predict CMS and colistin tissue distribution in typical individuals with different pathophysiological changes and receiving different dosing regimens.Methods: Twelve healthy males were included in the analysis. They received a single dose of 80 mg CMS (1 million unit) through a 1-h intravenous infusion. Venous blood was collected between 0 and 18 h post dose. Fractionated urine samples were collected between 0 and 24 h after dose. A WBPBPK model initially developed in rat was further detailed with the addition of a specific urinary tract (UT) model. The Kp values of CMS and colistin were estimated for all tissues using experimental Kp prior values from rat tissue homogenates.Results: The model adequately described CMS and colistin concentrations over time in plasma and in urine. A shared first order elimination rate constant was estimated to depict the hydrolysis of CMS in plasma and tissues. A separate hydrolysis rate constant for CMS was estimated in urine, and was lower than in plasma and tissues. A shared non-renal elimination rate constant of colistin was estimated in plasma and in tissues. CMS and colistin disposition in urine was well characterized by the UT model. The tubular reabsorption of colistin was best described by a saturable model estimating the colistin affinity constant, KM. Non-specific binding of colistin in the UT lumen was accounted for using a linear relationship.Conclusion: The WBPBPK developed in this study characterized plasma and urine PK of CMS and colistin in human well. This model was used as a new framework to predict colistin exposure in the tissues of interest under different physiological conditions. The model can be easily refined when new data are available and can be combined to PKPD models to increase the understanding of the concentration-effect relationship at target sites.
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| 14. |
- Bouchene, Salim, et al.
(författare)
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Development of a Whole-Body Physiologically Based Pharmacokinetic Model for Colistin and Colistin methanesulfonate (CMS) in Rat
-
Tidskriftsartikel (refereegranskat)abstract
- Colistin is a polymyxin antibiotic which is used to treat patients infected with multidrug resistant Gram negative bacteria (MDR-GNB). The objective of this work was to develop a whole-body physiologically based pharmacokinetic (WBPBPK) model in rat for colistin and its prodrug, CMS. The Kp prior values of colisin and CMS used in the WBPBPK model were either measured ex vivo in rat tissue homogenates or calculated using an in silico model. The PK parameters were estimated fitting plasma concentrations from rats receiving an i.v. bolus of CMS. In the WBPBPK model, the tissue distribution was assumed to be well-stirred and perfusion-limited. Three scenarios were investigated: estimating the Kp values using in silico Kp prior values (I), estimating the Kp values using the Kp prior values from ex vivo experiments (II) and fixing the Kp values to the experimental ex vivo Kp values (III). The WBPBPK model well described CMS and colistin plasma concentration-time profiles. Colistin Kp values in kidneys were higher than in the other tissues. The predicted concentrations in tissue were highest for kidneys and brain which might be due to a high affinity for these tissues and/or active transport processes that remain poorly elucidated. The clearance estimates of CMS and colistin were in agreement with previously reported values in the literature. The model developed in this study might be a valuable tool in drug development to understand the disposition of colistin or new polymyxin candidates as well as to guide for optimal dosing regimens.
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| 15. |
- Bouchene, Salim, 1984-, et al.
(författare)
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Development of an interspecies whole-body physiologically based pharmacokinetic (WBPBPK) model for colistin methanesulfonate (CMS) and colistin in five animal species and evaluation of its predictive ability in human
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background and purposeColistin is a last-line antibiotic administered as the prodrug colistin methanesulfonate (CMS) for the treatment of multidrug resistant Gram-negative bacterial infections. Whole-body physiologically based pharmacokinetic (WBPBPK) models are valuable tools to understand and characterize drug disposition, predict tissue distribution and interpret exposure-response relationship. The aim of this work was to develop a WBPBPK model for colistin and CMS in five animal species and evaluate the utility of the model for predicting colistin and CMS disposition in human.MethodsA nonlinear mixed-effects WBPBPK model previously developed in rats was extended to describe CMS and colistin plasma data of animals from 5 different species (40 mice, 6 rats, 3 rabbits, 3 baboons and 2 pigs) that had received single doses of CMS. CMS renal clearance and hydrolysis to colistin were allometrically scaled based on glomerular filtration rate (GFR) and tissue volumes, respectively. For the non-renal colistin clearance, three scaling models were evaluated: volume based allometric scaling, volume and maximum lifespan potential (MLP) based allometric scaling, and estimation of specie-specific parameters. Tissue concentrations were predicted for all species. The WBPBPK model was then used to predict human plasma concentrations, which were compared to observed human plasma PK data extracted from literature.ResultsThe description of the plasma PK of CMS and colistin in mice, rats, rabbits, baboons and pigs was satisfactory. The volume and MLP based allometric scaling of the non-renal clearance of colistin was best at characterizing colistin concentration-time course, even if a misprediction remained in pigs. In human however, allometric scaling without MLP was closest to the observed data, with satisfactory prediction of the CMS plasma profiles and a slight overprediction of colistin plasma PK profiles.ConclusionsInterspecies WBPBPK models were developed to describe the disposition of CMS and colistin across five animal species and human plasma concentrations of CMS and colistin were predicted in the right ranges.
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| 16. |
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| 17. |
- Chamoun, Mylad, et al.
(författare)
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Rechargeability of aqueous sulfate Zn/MnO2 batteries enhanced by accessible Mn2+ ions
- 2018
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Ingår i: Energy Storage Materials. - : Elsevier BV. - 2405-8289 .- 2405-8297. ; 15, s. 351-360
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Tidskriftsartikel (refereegranskat)abstract
- The Zn/MnO2 battery is safe, low cost and comes with a high energy density comparable to Li-ion batteries. However, irreversible spinel phases formed at the MnO2 electrode limits its cyclability. A viable solution to overcome this inactive phase is to use an aqueous ZnSO4-based electrolyte, where pH is mildly acidic leading to a different reaction mechanism. Most importantly, the addition of MnSO4 achieves excellent cyclability. How accessible Mn2+ ions in the electrolyte enhances the reversibility is presented. With added Mn2+, the capacity retention is significantly improved over 100 cycles. Zn2+ insertion plays an important role on the reversibility and a hydrated layered Zn-buserite structure formed during charge is reported. Furthermore, Zn4SO4(OH)(6) center dot 5H(2)O precipitates during discharge but is not involved in the electrochemical reaction. This precipitate both buffers the pH and partly insulates the surface. Described in operando study show how the phase transformations and the failure mechanisms depend on the presence of Mn2+-ions in the electrolyte. These results give insight necessary to improve this battery further to make it a worthy contender to the Li-ion battery in large scale energy storage solutions.
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| 18. |
- Christmas, Matthew, et al.
(författare)
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Evolutionary constraint and innovation across hundreds of placental mammals
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6643
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Tidskriftsartikel (refereegranskat)abstract
- Zoonomia is the largest comparative genomics resource for mammals produced to date. By aligning genomes for 240 species, we identify bases that, when mutated, are likely to affect fitness and alter disease risk. At least 332 million bases (similar to 10.7%) in the human genome are unusually conserved across species (evolutionarily constrained) relative to neutrally evolving repeats, and 4552 ultraconserved elements are nearly perfectly conserved. Of 101 million significantly constrained single bases, 80% are outside protein-coding exons and half have no functional annotations in the Encyclopedia of DNA Elements (ENCODE) resource. Changes in genes and regulatory elements are associated with exceptional mammalian traits, such as hibernation, that could inform therapeutic development. Earth's vast and imperiled biodiversity offers distinctive power for identifying genetic variants that affect genome function and organismal phenotypes.
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| 19. |
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| 20. |
- Corcoran, William, 1983, et al.
(författare)
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Mitigation of Nonlinear Impairments on QPSK Data in Phase-Sensitive Amplified Links
- 2013
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Ingår i: 39th European Conference on Optical Communication and Exhibition, ECOC 2013, London, 22-26 September 2013. - : Institution of Engineering and Technology. - 9781849197595 ; 2013:622 CP, s. 486-488
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Konferensbidrag (refereegranskat)abstract
- We investigate the mitigation of nonlinear impairments via phase-sensitive amplification. We show in simulation and experiment that this effect can be optimized through engineering link dispersion. A phase-sensitive amplified link is measured to reduce nonlinear penalties by over 3dB compared to a phase-insensitive amplified link.
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| 21. |
- Corcoran, William, 1983, et al.
(författare)
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Noise beating in hybrid phase-sensitive amplifier systems
- 2014
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Ingår i: Optics Express. - : The Optical Society. - 1094-4087 .- 1094-4087. ; 22:5, s. 5762-5771
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of noise loading in a hybrid phase-sensitive amplifier system, analyzing the effect of noise beating between the signal and idler waves coupled in a parametric amplifier. Through analyzing input and output optical signal to noise ratios, we find that system performance of a phase-sensitive amplifier is 3 to 6 dB improved over a phase-insensitive amplifier, depending on the ratio of loaded noise power to that of vacuum fluctuations. (C) 2014 Optical Society of America
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| 22. |
- Corcoran, William, 1983, et al.
(författare)
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Phase-Sensitive Optical Pre-Amplifier Implemented in an 80km DQPSK Link
- 2012
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Ingår i: Optics InfoBase Conference Papers. - Washington, D.C. : OSA. - 2162-2701.
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Konferensbidrag (refereegranskat)abstract
- We present the first demonstration of a phase-sensitive fiber optic parametric amplifier successfully implemented over an 80 km dispersion managed link. We measure 1.3 dB higher sensitivity with this amplifier system against a comparable conventional EDFA-based link.
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| 23. |
- Ellborg, Katarina, 1975-
(författare)
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Envisioning entrepreneurship : Using photographs to elicit students’ preconceptions of entrepreneurship
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nowadays, entrepreneurship is taught on a ‘university-wide’ basis, implying that thesubject is introduced to multiple students from a diversity of backgrounds. At thesame time, a student-centred movement has been noted in the field, focusing ontailored education based on students’ preconceptions of entrepreneurship. However, studies of students’ preconceptions of entrepreneurship are scarce. Thus far,entrepreneurship education literature has primarily examined what to teach or how to teach. This has taken place in accordance with the Anglo-American didactictradition in which ‘didactics’ is a form of instruction rather than a way of combining ‘what’, ‘how’ and ‘why’ questions from various perspectives. As a consequence, distinguished authors in the field are calling for more advanced theoretical links between entrepreneurship education research and education science. This study develops and examines a visual-based exercise as a means of studyingstudents’ preconceptions of entrepreneurship and as a novel educational tool. Thisis conducted in accordance with the German didaktik tradition that presumes thatstudents, the learning content and the teacher are interdependently related. The purpose is to elicit students’ preconceptions of entrepreneurship using a visual-based exercise, as well as to offer knowledge of how this affects didaktik relationships in entrepreneurship education. To address this purpose, phenomenographic didaktik is used to discuss a subject-specific ‘entrepreneurship didaktik’, characterised by astudent-centred perspective. Photographs were used in a visual-based exercise to elicit students’ preconceptions and interviews with teachers and students were conducted in order to evaluate the exercise from a didaktik perspective.The results of the study show that students’ preconceptions of entrepreneurshipare multifaceted and that there are both similarities and differences between students’ preconceptions of entrepreneurship and established understandings of entrepreneurship. From a practical perspective, the study introduces a visual-based exercise that contributes to both students’ and teachers’ understandings of where entrepreneurship education starts from a student perspective, thereby helping students to link new knowledge to their contemporary understandings and helping teachers to base their education on students’ preconceptions in order to enhancetheir learning. On a theoretical level, this work contributes to the student-centred movement in entrepreneurship education by demonstrating how the relational perspective in the German didaktik tradition can advance the link betweenentrepreneurship education and education science.
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| 24. |
- Estrada, Karol, et al.
(författare)
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Genome-wide meta-analysis identifies 56 bone mineral density loci and reveals 14 loci associated with risk of fracture.
- 2012
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Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 44:5, s. 491-501
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Tidskriftsartikel (refereegranskat)abstract
- Bone mineral density (BMD) is the most widely used predictor of fracture risk. We performed the largest meta-analysis to date on lumbar spine and femoral neck BMD, including 17 genome-wide association studies and 32,961 individuals of European and east Asian ancestry. We tested the top BMD-associated markers for replication in 50,933 independent subjects and for association with risk of low-trauma fracture in 31,016 individuals with a history of fracture (cases) and 102,444 controls. We identified 56 loci (32 new) associated with BMD at genome-wide significance (P < 5 × 10(-8)). Several of these factors cluster within the RANK-RANKL-OPG, mesenchymal stem cell differentiation, endochondral ossification and Wnt signaling pathways. However, we also discovered loci that were localized to genes not known to have a role in bone biology. Fourteen BMD-associated loci were also associated with fracture risk (P < 5 × 10(-4), Bonferroni corrected), of which six reached P < 5 × 10(-8), including at 18p11.21 (FAM210A), 7q21.3 (SLC25A13), 11q13.2 (LRP5), 4q22.1 (MEPE), 2p16.2 (SPTBN1) and 10q21.1 (DKK1). These findings shed light on the genetic architecture and pathophysiological mechanisms underlying BMD variation and fracture susceptibility.
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| 25. |
- Foley, Nicole M., et al.
(författare)
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A genomic timescale for placental mammal evolution
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6643, s. 365-
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Tidskriftsartikel (refereegranskat)abstract
- The precise pattern and timing of speciation events that gave rise to all living placental mammals remain controversial. We provide a comprehensive phylogenetic analysis of genetic variation across an alignment of 241 placental mammal genome assemblies, addressing prior concerns regarding limited genomic sampling across species. We compared neutral genome-wide phylogenomic signals using concatenation and coalescent-based approaches, interrogated phylogenetic variation across chromosomes, and analyzed extensive catalogs of structural variants. Interordinal relationships exhibit relatively low rates of phylogenomic conflict across diverse datasets and analytical methods. Conversely, X-chromosome versus autosome conflicts characterize multiple independent clades that radiated during the Cenozoic. Genomic time trees reveal an accumulation of cladogenic events before and immediately after the Cretaceous-Paleogene (K-Pg) boundary, implying important roles for Cretaceous continental vicariance and the K-Pg extinction in the placental radiation.
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| 26. |
- Genereux, Diane P., et al.
(författare)
-
A comparative genomics multitool for scientific discovery and conservation
- 2020
-
Ingår i: Nature. - : NATURE RESEARCH. - 0028-0836 .- 1476-4687. ; 587:7833, s. 240-245
-
Tidskriftsartikel (refereegranskat)abstract
- A whole-genome alignment of 240 phylogenetically diverse species of eutherian mammal-including 131 previously uncharacterized species-from the Zoonomia Project provides data that support biological discovery, medical research and conservation. The Zoonomia Project is investigating the genomics of shared and specialized traits in eutherian mammals. Here we provide genome assemblies for 131 species, of which all but 9 are previously uncharacterized, and describe a whole-genome alignment of 240 species of considerable phylogenetic diversity, comprising representatives from more than 80% of mammalian families. We find that regions of reduced genetic diversity are more abundant in species at a high risk of extinction, discern signals of evolutionary selection at high resolution and provide insights from individual reference genomes. By prioritizing phylogenetic diversity and making data available quickly and without restriction, the Zoonomia Project aims to support biological discovery, medical research and the conservation of biodiversity.
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| 27. |
- George, William, 1945, et al.
(författare)
-
A Similarity Theory for the Plane Wall Jet
- 1999
-
Ingår i: Journal of Fluid Mechanics. ; 425, s. 361-411
-
Tidskriftsartikel (refereegranskat)abstract
- A new theory for the turbulent plane wall jet without external stream is proposed based on a similarity analysis of the governing equations. The asymptotic invariance principle (AIP) is used to require that properly scaled profiles reduce to similarity solutions of the inner and outer equations separately in the limit of infinite Reynolds number. Application to the inner equations shows that the appropriate velocity scale is the friction velocity, u[low asterisk], and the length scale is v/u[low asterisk]. For finite Reynolds numbers, the profiles retain a dependence on the length-scale ratio, y+1/2 = u[low asterisk]y1/2/v, where y1/2 is the distance from the wall at which the mean velocity has dropped to 1/2 its maximum value. In the limit as y+1/2 [rightward arrow] [infty infinity], the familiar law of the wall is obtained. Application of the AIP to the outer equations shows the appropriate velocity scale to be Um, the velocity maximum, and the length scale y1/2; but again the profiles retain a dependence on y+1/2 for finite values of it. The Reynolds shear stress in the outer layer scales with u2*, while the normal stresses scale with U2m. Also Um [similar] yn1/2 where n
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| 28. |
- Haghighi, Mona, et al.
(författare)
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A Comparison of Rule-based Analysis with Regression Methods in Understanding the Risk Factors for Study Withdrawal in a Pediatric Study
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Regression models are extensively used in many epidemiological studies to understand the linkage between specific outcomes of interest and their risk factors. However, regression models in general examine the average effects of the risk factors and ignore subgroups with different risk profiles. As a result, interventions are often geared towards the average member of the population, without consideration of the special health needs of different subgroups within the population. This paper demonstrates the value of using rule-based analysis methods that can identify subgroups with heterogeneous risk profiles in a population without imposing assumptions on the subgroups or method. The rules define the risk pattern of subsets of individuals by not only considering the interactions between the risk factors but also their ranges. We compared the rule-based analysis results with the results from a logistic regression model in The Environmental Determinants of Diabetes in the Young (TEDDY) study. Both methods detected a similar suite of risk factors, but the rule-based analysis was superior at detecting multiple interactions between the risk factors that characterize the subgroups. A further investigation of the particular characteristics of each subgroup may detect the special health needs of the subgroup and lead to tailored interventions.
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| 29. |
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| 30. |
- Holmén, Jessica, 1971, et al.
(författare)
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Mucins and their O-Glycans from human bronchial epithelial cell cultures.
- 2004
-
Ingår i: American journal of physiology. Lung cellular and molecular physiology. - : American Physiological Society. - 1040-0605 .- 1522-1504. ; 287:4
-
Tidskriftsartikel (refereegranskat)abstract
- A longstanding question in obstructive airway disease is whether observed changes in mucin composition and/or posttranslational glycosylation are due to genetic or to environmental factors. We tested whether the mucins secreted by second-passage primary human bronchial epithelial cell cultures derived from noncystic fibrosis (CF) or CF patients have intrinsically different specific mucin compositions, and whether these mucins are glycosylated differently. Both CF and non-CF cultures produced MUC5B, predominantly, as judged by quantitative agarose gel Western blots with mucin-specific antibodies: MUC5B was present at approximately 10-fold higher levels than MUC5AC, consistent with our previous mRNA studies (Bernacki SH, Nelson AL, Abdullah L, Sheehan JK, Harris A, William DC, and Randell SH. Am J Respir Cell Mol Biol 20: 595-604, 1999). O-linked oligosaccharides released from purified non-CF and CF mucins and studied by HPLC mass spectrometry had highly variable glycan structures, and there were no observable differences between the two groups. Hence, there were no differences in either the specific mucins or their O-glycans that correlated with the CF phenotype under the noninfected/noninflammatory conditions of cell culture. We conclude that the differences observed in the mucins sampled directly from patients are most likely due to environmental factors relating to infection and/or inflammation.
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| 31. |
- Hong, Mun-Gwan, et al.
(författare)
-
A genome-wide assessment of variability in human serum metabolism
- 2013
-
Ingår i: Human Mutation. - : Hindawi Limited. - 1059-7794 .- 1098-1004. ; 34:3, s. 515-524
-
Tidskriftsartikel (refereegranskat)abstract
- The study of the genetic regulation of metabolism in human serum samples can contribute to a better understanding of the intermediate biological steps that lead from polymorphism to disease. Here, we conducted a genome-wide association study (GWAS) to discover metabolic quantitative trait loci (mQTLs) utilizing samples from a study of prostate cancer in Swedish men, consisting of 402 individuals (214 cases and 188 controls) in a discovery set and 489 case-only samples in a replication set. A global nontargeted metabolite profiling approach was utilized resulting in the detection of 6,138 molecular features followed by targeted identification of associated metabolites. Seven replicating loci were identified (PYROXD2, FADS1, PON1, CYP4F2, UGT1A8, ACADL, and LIPC) with associated sequence variants contributing significantly to trait variance for one or more metabolites (P = 10(-13) -10(-91)). Regional mQTL enrichment analyses implicated two loci that included FADS1 and a novel locus near PDGFC. Biological pathway analysis implicated ACADM, ACADS, ACAD8, ACAD10, ACAD11, and ACOXL, reflecting significant enrichment of genes with acyl-CoA dehydrogenase activity. mQTL SNPs and mQTL-harboring genes were over-represented across GWASs conducted to date, suggesting that these data may have utility in tracing the molecular basis of some complex disease associations.
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| 32. |
- Johansson, Anders J, et al.
(författare)
-
Medical Implant Communication Systems
- 2006
-
Ingår i: Antennas and Propagation for Body-centric Wireless Coomunications. - 1580534937 ; , s. 241-270
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 33. |
- Karlsson, Charlie, 1945-, et al.
(författare)
-
Infrastructure Measurement and Management – An Introduction
- 2007
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Ingår i: Management and Measurement of Infrastructure. Performance, Efficiency and Innovation. - Cheltenham : Edward Elgar Publishing. - 9781845426439 ; , s. 1-21
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 34. |
- Karlsson, Elinor K, et al.
(författare)
-
Genome-wide analyses implicate 33 loci in heritable dog osteosarcoma, including regulatory variants near CDKN2A/B
- 2013
-
Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X .- 1474-7596. ; 14:12
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Canine osteosarcoma is clinically nearly identical to the human disease, but is common and highly heritable, making genetic dissection feasible.RESULTS: Through genome-wide association analyses in three breeds (greyhounds, Rottweilers, and Irish wolfhounds), we identify 33 inherited risk loci explaining 55% to 85% of phenotype variance in each breed. The greyhound locus exhibiting the strongest association, located 150 kilobases upstream of the genes CDKN2A/B, is also the most rearranged locus in canine osteosarcoma tumors. The top germline candidate variant is found at a >90% frequency in Rottweilers and Irish wolfhounds, and alters an evolutionarily constrained element that we show has strong enhancer activity in human osteosarcoma cells. In all three breeds, osteosarcoma-associated loci and regions of reduced heterozygosity are enriched for genes in pathways connected to bone differentiation and growth. Several pathways, including one of genes regulated by miR124, are also enriched for somatic copy-number changes in tumors.CONCLUSIONS: Mapping a complex cancer in multiple dog breeds reveals a polygenic spectrum of germline risk factors pointing to specific pathways as drivers of disease.
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| 35. |
- Karlsson, Hans O, et al.
(författare)
-
Theoretical calculation of photodetachment intensities for H3O-
- 1996
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 105:13, s. 5387-5396
-
Tidskriftsartikel (refereegranskat)abstract
- We have calculated total and arrangement-selected photodetachment intensities for the H3O- anion (and its deuterated form, D3O-) using a Green's function in a discrete variable representation with absorbing boundary conditions. A multiply-shifted quasiminimal residual method is used to obtain the Green's function for many energies at once. We present spectra obtained by explicitly treating two and four degrees of freedom. Comparison with experiment indicates that the bending angles in the anion and neutral are more similar than in the current potential energy surfaces. The calculated spectra are also consistent with the suggestion that the barrier should be ''earlier.'
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| 36. |
- Karlsson, Johan, et al.
(författare)
-
Fast Missing-Data IAA With Application to Notched Spectrum SAR
- 2014
-
Ingår i: IEEE Transactions on Aerospace and Electronic Systems. - 0018-9251 .- 1557-9603. ; 50:2, s. 959-971
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, the spectral estimation method known as the iterative adaptive approach (IAA) has been shown to provide higher resolution and lower sidelobes than comparable spectral estimation methods. The computational complexity is higher than methods such as the periodogram (matched filter method). Fast algorithms have been developed that considerably reduce the computational complexity of IAA by using Toeplitz and Vandermonde structures. For the missing-data case, several of these structures are lost, and existing fast algorithms are only efficient when the number of available samples is small. In this work, we consider the case in which the number of missing samples is small. This allows us to use low-rank completion to transform the problem to the structured problem. We compare the computational speed of the algorithm with the state of the art and demonstrate the utility in a frequency-notched synthetic aperture radar imaging problem.
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| 37. |
- Karlsson, Miriam, et al.
(författare)
-
New proposals for testing drugs with IKr-blocking activity to determine their teratogenic potential
- 2007
-
Ingår i: Current pharmaceutical design. - : Bentham Science Publishers Ltd.. - 1381-6128 .- 1873-4286. ; 13:29, s. 2979-2988
-
Forskningsöversikt (refereegranskat)abstract
- Drugs blocking the potassium current IKr, either as an intended pharmacologic effect (eg antiarrhythmics dofetilide and almokalant) or as an unwanted side-effect (eg antihistamine astemizole, propulsive drug cisapride, antidepressive drugs and macrolide antibiotics) are potential human teratogens. It is the contention of this paper that the existing repeat dose regimen used in teratology studies to fulfil regulatory requirements, does not properly identify the teratogenic risk of these drugs. Results from conventional studies for dofetilide and almokalant showed high rates of postimplantation embryonic death with few malformed fetuses. For astemizole and cisapride only embryonic death was seen. These latter results were not considered important because they occurred either in the presence of maternal toxicity and/or at high doses. Subsequent studies have shown that IKr-blockers are highly teratogenic when administered on single gestational days (GD) during a sensitive period of rat pregnancy (GD 10-14) when they induce a high incidence of stage-specific malformations. This teratogenic activity of astemizole and cisapride was missed in the original teratology studies. Mechanistically IKr-blockers cause bradycardia and arrhythmia of the embryonic heart and while an embryo may be able to survive a single day exposure to a teratogenic dose, repeat dosing often leads to death of the embryo. With this review we suggest that new drugs identified at the preclinical stage of development as having IKr-blocking properties, should undergo more comprehensive teratology testing including single GD dosing and studies using embryo culture. This would further help identify and characterise their teratogenic potential.
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| 38. |
- Karlsson, Omar, et al.
(författare)
-
Socioeconomic and gender inequalities in neonatal, postneonatal and child mortality in India : A repeated cross-sectional study, 2005-2016
- 2019
-
Ingår i: Journal of Epidemiology and Community Health. - : BMJ. - 0143-005X .- 1470-2738. ; 73:7, s. 660-667
-
Tidskriftsartikel (refereegranskat)abstract
- Background: In India, excess female under-5 mortality is well documented. Under-5 mortality is also known to be patterned by socioeconomic factors. This study examines sex differentials and sex-specific wealth gradients in neonatal, postneonatal and child mortality in India. Methods: Repeated cross-sectional study of nationally representative samples of 298 955 children 0-60 months old from the National Family Health Surveys conducted in 2005-2006 and 2015-2016. The study used logistic regression models as well as Cox proportional hazards models. Results: Overall, boys had greater neonatal mortality than girls and the difference increased between 2005-2006 and 2015-2016. Girls had greater postneonatal and child mortality, but the difference decreased between the surveys and was not statistically significant for child mortality in 2015-2016. A negative wealth gradient was found for all mortality outcomes. Neonatal mortality was persistently greater for boys. Girls had higher child mortality than boys at low levels of wealth and greater postneonatal mortality over much of the wealth distribution. The wealth gradient in neonatal mortality increased between surveys. Females had a stronger wealth gradient than boys for child mortality. Conclusion: Not distinguishing between neonatal, postneonatal and child mortality masks important gender-specific and wealth-specific disparities in under-5 mortality in India. Substantial gains towards the Sustainable Development Goals can be made by combating neonatal mortality, especially at low levels of wealth. Although impressive improvements have been made in reducing the female disadvantage in postneonatal and child mortality, concerted engagements are necessary to eliminate the gender gap - especially in poor households and in north India.
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| 39. |
- Karlsson, Omar, et al.
(författare)
-
The relationship of household assets and amenities with child health outcomes: an exploratory cross-sectional study in India 2015–2016
- 2020
-
Ingår i: SSM - Population Health. - : Elsevier BV. - 2352-8273. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Healthy development of children in India is far from ensured. Proximate determinants of poor child health outcomes are infectious diseases and undernutrition, which are linked to socioeconomic status. In low- and middle-income countries, researchers rely on wealth indices, constructed from information on households’ asset ownership and amenities, to study socioeconomic disparities in child health. Some of these wealth index items can, however, directly affect the proximate determinants of child health. This paper explores the independent association of each item used to construct the Demographic and Health Surveys’ wealth index with diverse child health outcomes. This cross-sectional study used nationally representative sample of 245,866 children, age 0–59 months, from the Indian National Family Health Surveys conducted in 2015–16. The study used conditional Poisson regression models as well as a range of sensitivity specifications. After controlling for socioeconomic status, health care use, maternal factors, community-level factors, and all wealth index items, the following wealth index items were the most consistently associated with child health; type of toilet facilities, water source, refrigerator, pressure cooker, type of cooking fuel, having a bank account, land usable for agriculture, floor material, roof material, mobile phone, and motorcycle/scooter. The association with type of toilet facilities and water source was particularly strong for mortality, showing a 16-35% and 14-26% lower mortality, respectively. Most items used to construct the Demographic and Health Surveys’ wealth index only indicate household socioeconomic status, while a few items may affect child health directly, and can be useful targets for policy intervention.
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| 40. |
- Kenworthy, Matthew A., et al.
(författare)
-
High contrast imaging for the enhanced resolution imager and spectrometer (ERIS)
- 2018
-
Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY VII. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9781510619586
-
Konferensbidrag (refereegranskat)abstract
- ERIS is a diffraction limited thermal infrared imager and spectrograph for the Very Large Telescope UT4. One of the science cases for ERIS is the detection and characterization of circumstellar structures and exoplanets around bright stars that are typically much fainter than the stellar diffraction halo. Enhanced sensitivity is provided through the combination of (i) suppression of the diffraction halo of the target star using coronagraphs, and (ii) removal of any residual diffraction structure through focal plane wavefront sensing and subsequent active correction. In this paper we present the two coronagraphs used for diffraction suppression and enabling high contrast imaging in ERIS.
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| 41. |
- Khalili, Bita, et al.
(författare)
-
Associations between common genetic variants and income provide insights about the socioeconomic health gradient
- 2024
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We conducted a genome-wide association study (GWAS) on income among individuals of European descent and leveraged the results to investigate the socio-economic health gradient (N=668,288). We found 162 genomic loci associated with a common genetic factor underlying various income measures, all with small effect sizes. Our GWAS-derived polygenic index captures 1 - 4% of income variance, with only one-fourth attributed to direct genetic effects. A phenome-wide association study using this polygenic index showed reduced risks for a broad spectrum of diseases, including hypertension, obesity, type 2 diabetes, coronary atherosclerosis, depression, asthma, and back pain. The income factor showed a substantial genetic correlation (0.92, s.e. = .006) with educational attainment (EA). Accounting for EA's genetic overlap with income revealed that the remaining genetic signal for higher income related to better mental health but reduced physical health benefits and increased participation in risky behaviours such as drinking and smoking.
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| 42. |
- Kim, HyeJin, et al.
(författare)
-
Towards a better future for biodiversity and people : Modelling Nature Futures
- 2023
-
Ingår i: Global Environmental Change. - 0959-3780 .- 1872-9495. ; 82
-
Tidskriftsartikel (refereegranskat)abstract
- The Nature Futures Framework (NFF) is a heuristic tool for co-creating positive futures for nature and people. It seeks to open up a diversity of futures through mainly three value perspectives on nature - Nature for Nature, Nature for Society, and Nature as Culture. This paper describes how the NFF can be applied in modelling to support decision-making. First, we describe key considerations for the NFF in developing qualitative and quantitative scenarios: i) multiple value perspectives on nature as a state space where pathways improving nature toward a frontier can be represented, ii) mutually reinforcing key feedbacks of social-ecological systems that are important for nature conservation and human wellbeing, iii) indicators of multiple knowledge systems describing the evolution of complex social-ecological dynamics. We then present three approaches to modelling Nature Futures scenarios in the review, screening, and design phases of policy processes. This paper seeks to facilitate the integration of relational values of nature in models and strengthen modelled linkages across biodiversity, nature's contributions to people, and quality of life.
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| 43. |
- Klaus, Marcus, et al.
(författare)
-
Evaluations of Climate and Land Management Effects on Lake Carbon Cycling Need to Account Temporal Variability in CO2 Concentration
- 2019
-
Ingår i: Global Biogeochemical Cycles. - : American Geophysical Union (AGU). - 0886-6236 .- 1944-9224. ; 33:3, s. 243-265
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide (CO2) concentrations in lakes vary strongly over time. This variability is rarely captured by environmental monitoring but is crucial for accurately assessing the magnitude of lake CO2 emissions. However, it is unknown to what extent temporal variability needs to be captured to understand important drivers of lake carbon cycling such as climate and land management. We used environmental monitoring data of Swedish forest lakes collected in autumn (n = 439) and throughout the whole open water season (n = 22) from a wet and a dry year to assess temporal variability in effects of climate and forestry on CO2 concentrations across lakes. Effects differed depending on the season and year sampled. According to cross-lake comparisons based on autumn data, CO2 concentrations increased with annual mean air temperature (dry year) or catchment forest productivity (wet year) but were not related to colored dissolved organic matter concentrations. In contrast, open water-season averaged CO2 concentrations were similar across temperature and productivity gradients but increased with colored dissolved organic matter. These contradictions resulted from scale mismatches in input data, lead to weak explanatory power (R-2 = 9-32%), and were consistent across published data from 79 temperate, boreal, and arctic lakes. In a global survey of 144 published studies, we identified a trade-off between temporal and spatial coverage of CO2 sampling. This trade-off clearly determines which conclusions are drawn from landscape-scale CO(2 )assessments. Accurate evaluations of the effects of climate and land management require spatially and temporally representative data that can be provided by emerging sensor technologies and forms of collaborative sampling.
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| 44. |
- Klaus, Marcus, 1988-, et al.
(författare)
-
Neglecting seasonality causes biased view of climate and forestry impacts on lake CO2 cycling
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Lakes emit carbon dioxide (CO2) at globally significant rates. These emissions may be controlled by land use and climate. Disentangling these interactions is a prerequisite to accurately predicting anthropogenic impacts on carbon cycling in lake rich regions. We used environmental monitoring data of lakes collected in autumn (n = 439) and throughout the whole open-water season (n = 22) from a wet and a dry year in Swedish forest catchments to evaluate direct and indirect effects of temperature, precipitation, wind speed, forest productivity and forest clearcutting on lake CO2 concentrations. We found that trends in CO2 concentrations along climate and forestry gradients do not always correspond between autumn and open-water season averages, implying the need of validation of patterns derived from snap-shot data alone. According to spatially resolved data, autumn CO2 concentrations increased with mean annual air temperature (dry year) or catchment forest productivity (wet year) but were not coupled to colored dissolved organic matter (CDOM) concentrations. In contrast, open-water season averaged CO2 concentrations were constant across temperature and productivity gradients but increased with CDOM. These antagonistic results suggest that our fundamental understanding of the controls of CO2 in lakes depends on whether spatially or temporally resolved data is used. Hence, trade-offs in sampling efforts clearly limit the questions that can be addressed regarding climate and land use effects on lake carbon cycling.
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| 45. |
- Lees, William D., et al.
(författare)
-
AIRR community curation and standardised representation for immunoglobulin and T cell receptor germline sets
- 2023
-
Ingår i: Immunoinformatics. - : Elsevier BV. - 2667-1190. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Analysis of an individual's immunoglobulin or T cell receptor gene repertoire can provide important insights into immune function. High-quality analysis of adaptive immune receptor repertoire sequencing data depends upon accurate and relatively complete germline sets, but current sets are known to be incomplete. Established processes for the review and systematic naming of receptor germline genes and alleles require specific evidence and data types, but the discovery landscape is rapidly changing. To exploit the potential of emerging data, and to provide the field with improved state-of-the-art germline sets, an intermediate approach is needed that will allow the rapid publication of consolidated sets derived from these emerging sources. These sets must use a consistent naming scheme and allow refinement and consolidation into genes as new information emerges. Name changes should be minimised, but, where changes occur, the naming history of a sequence must be traceable. Here we outline the current issues and opportunities for the curation of germline IG/TR genes and present a forward-looking data model for building out more robust germline sets that can dovetail with current established processes. We describe interoperability standards for germline sets, and an approach to transparency based on principles of findability, accessibility, interoperability, and reusability.
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| 46. |
- Liptzin, Daniel, et al.
(författare)
-
Spatial and Temporal Patterns in Atmospheric Deposition of Dissolved Organic Carbon
- 2022
-
Ingår i: Global Biogeochemical Cycles. - : American Geophysical Union (AGU). - 0886-6236 .- 1944-9224. ; 36:10
-
Tidskriftsartikel (refereegranskat)abstract
- Atmospheric deposition of dissolved organic carbon (DOC) to terrestrial ecosystems is a small, but rarely studied component of the global carbon (C) cycle.Emissions of volatile organic compounds (VOC) and organic particulates are the sources of atmospheric C and deposition represents a major pathway for the removal of organic C from the atmosphere.Here, we evaluate the spatial and temporal patterns of DOC deposition using 70 data sets at least one year in length ranging from 40° south to 66° north latitude. Globally, the median DOC concentration in bulk deposition was 1.7 mg L −1. The DOC concentrations were significantly higher in tropical (<25°) latitudes compared to temperate (>25°) latitudes.DOC deposition was significantly higher in the tropics because of both higher DOC concentrations and precipitation. Using the global median or latitudinal specific DOC concentrations leads to a calculated global deposition of 202 or 295 Tg C yr −1 respectively.Many sites exhibited seasonal variability in DOC concentration. At temperate sites, DOC concentrations were higher during the growing season; at tropical sites, DOC concentrations were higher during the dry season. Thirteen of the thirty-four long-term (>10 years) data sets showed significant declines in DOC concentration over time with the others showing no significant change.Based on the magnitude and timing of the various sources of organic C to the atmosphere, biogenic VOCs likely explain the latitudinal pattern and the seasonal pattern at temperate latitudes while decreases in anthropogenic emissions are the most likely explanation for the declines in DOC concentration.
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| 47. |
- Lundgren, Markus, et al.
(författare)
-
Analgesic antipyretic use among young children in the TEDDY study : No association with islet autoimmunity
- 2017
-
Ingår i: BMC Pediatrics. - : Springer Science and Business Media LLC. - 1471-2431. ; 17:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The use of analgesic antipyretics (ANAP) in children have long been a matter of controversy. Data on their practical use on an individual level has, however, been scarce. There are indications of possible effects on glucose homeostasis and immune function related to the use of ANAP. The aim of this study was to analyze patterns of analgesic antipyretic use across the clinical centers of The Environmental Determinants of Diabetes in the Young (TEDDY) prospective cohort study and test if ANAP use was a risk factor for islet autoimmunity. Methods: Data were collected for 8542 children in the first 2.5 years of life. Incidence was analyzed using logistic regression with country and first child status as independent variables. Holm's procedure was used to adjust for multiplicity of intercountry comparisons. Time to autoantibody seroconversion was analyzed using a Cox proportional hazards model with cumulative analgesic use as primary time dependent covariate of interest. For each categorization, a generalized estimating equation (GEE) approach was used. Results: Higher prevalence of ANAP use was found in the U.S. (95.7%) and Sweden (94.8%) compared to Finland (78.1%) and Germany (80.2%). First-born children were more commonly given acetaminophen (OR 1.26; 95% CI 1.07, 1.49; p = 0.007) but less commonly Non-Steroidal Anti-inflammatory Drugs (NSAID) (OR 0.86; 95% CI 0.78, 0.95; p = 0.002). Acetaminophen and NSAID use in the absence of fever and infection was more prevalent in the U.S. (40.4%; 26.3% of doses) compared to Sweden, Finland and Germany (p < 0.001). Acetaminophen or NSAID use before age 2.5 years did not predict development of islet autoimmunity by age 6 years (HR 1.02, 95% CI 0.99-1.09; p = 0.27). In a sub-analysis, acetaminophen use in children with fever weakly predicted development of islet autoimmunity by age 3 years (HR 1.05; 95% CI 1.01-1.09; p = 0.024). Conclusions: ANAP use in young children is not a risk factor for seroconversion by age 6 years. Use of ANAP is widespread in young children, and significantly higher in the U.S. compared to other study sites, where use is common also in absence of fever and infection.
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| 48. |
- Lundström, Carl Peter, 1982, et al.
(författare)
-
Fiber optic parametric amplifier with 10-dB net gain without pump dithering
- 2013
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 25:3, s. 234-237
-
Tidskriftsartikel (refereegranskat)abstract
- We present a stimulated Brillouin Scattering (SBS)-suppressed fiber optic parametric amplifier/wavelength converter constructed from four highly nonlinear fiber pieces with applied strain gradients and separated by isolators. The effective total SBS threshold increase is about 11 dB, and a net parametric gain of 10 dB is obtained without any pump dithering.
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| 49. |
- Lundström, Carl Peter, 1982, et al.
(författare)
-
Fiber-optic parametric amplifiers without pump dithering
- 2013
-
Ingår i: Optics InfoBase Conference Papers. - Washington, D.C. : OSA. - 2162-2701.
-
Konferensbidrag (refereegranskat)abstract
- We present passively stimulated Brillouin scattering-suppressed highly nonlinear fiber cascades, and use them to implement fiber-optic parametric amplifiers capable of up to 10 dB net parametric gain without pump dithering.
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| 50. |
- Lundström, Carl Peter, 1982, et al.
(författare)
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Phase and amplitude characteristics of a phase-sensitive amplifier operating in gain saturation
- 2012
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 20:19, s. 21400-21412
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Tidskriftsartikel (refereegranskat)abstract
- We investigate a non-degenerate phase-sensitive amplifier (PSA) operating in gain saturation experimentally and numerically using the three-wave model. The phase-dependent gain and phase-to-phase transfer functions are obtained for different levels of saturation with good agreement between experimental and numerical data when higher-order FWM is small. Moreover, we identify an operating point where the PSA is found to be able to significantly reduce both phase-and amplitude noise simultaneously.
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