| 1. |
- Axelsson, Erik, et al.
(författare)
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Natural selection in protein-coding genes expressed in avian brain
- 2008
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 17:12, s. 3008-3017
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of birds from theropod dinosaurs took place approximately 150 million years ago, and was associated with a number of specific adaptations that are still evident among extant birds, including feathers, song and extravagant secondary sexual characteristics. Knowledge about the molecular evolutionary background to such adaptations is lacking. Here, we analyse the evolution of > 5000 protein-coding gene sequences expressed in zebra finch brain by comparison to orthologous sequences in chicken. Mean d(N)/d(S) is 0.085 and genes with their maximal expression in the eye and central nervous system have the lowest mean d(N)/d(S) value, while those expressed in digestive and reproductive tissues exhibit the highest. We find that fast-evolving genes (those which have higher than expected rate of nonsynonymous substitution, indicative of adaptive evolution) are enriched for biological functions such as fertilization, muscle contraction, defence response, response to stress, wounding and endogenous stimulus, and cell death. After alignment to mammalian orthologues, we identify a catalogue of 228 genes that show a significantly higher rate of protein evolution in the two bird lineages than in mammals. These accelerated bird genes, representing candidates for avian-specific adaptations, include genes implicated in vocal learning and other cognitive processes. Moreover, colouration genes evolve faster in birds than in mammals, which may have been driven by sexual selection for extravagant plumage characteristics.
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| 2. |
- Baranowska, Izabella, et al.
(författare)
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Sensory ataxic neuropathy in golden retriever dogs is caused by a deletion in the mitochondrial tRNATyr gene
- 2009
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 5:5, s. e1000499-
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Tidskriftsartikel (refereegranskat)abstract
- Sensory ataxic neuropathy (SAN) is a recently identified neurological disorder in golden retrievers. Pedigree analysis revealed that all affected dogs belong to one maternal lineage, and a statistical analysis showed that the disorder has a mitochondrial origin. A one base pair deletion in the mitochondrial tRNA(Tyr) gene was identified at position 5304 in affected dogs after re-sequencing the complete mitochondrial genome of seven individuals. The deletion was not found among dogs representing 18 different breeds or in six wolves, ruling out this as a common polymorphism. The mutation could be traced back to a common ancestor of all affected dogs that lived in the 1970s. We used a quantitative oligonucleotide ligation assay to establish the degree of heteroplasmy in blood and tissue samples from affected dogs and controls. Affected dogs and their first to fourth degree relatives had 0-11% wild-type (wt) sequence, while more distant relatives ranged between 5% and 60% wt sequence and all unrelated golden retrievers had 100% wt sequence. Northern blot analysis showed that tRNA(Tyr) had a 10-fold lower steady-state level in affected dogs compared with controls. Four out of five affected dogs showed decreases in mitochondrial ATP production rates and respiratory chain enzyme activities together with morphological alterations in muscle tissue, resembling the changes reported in human mitochondrial pathology. Altogether, these results provide conclusive evidence that the deletion in the mitochondrial tRNA(Tyr) gene is the causative mutation for SAN.
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| 3. |
- Cao, Danfeng, et al.
(författare)
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Tunable electroactive biomimetic bone-like surfaces for bone marrow-on-chips
- 2023
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Ingår i: 2023 IEEE BIOSENSORS CONFERENCE, BIOSENSORS. - : IEEE. - 9798350346046 - 9798350346114
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Konferensbidrag (refereegranskat)abstract
- Electro-stimulation is an effective way to manipulate the presentation of bio-factors at the materials interface. This study aimed to develop electrochemically-modified trabecular bone-like surfaces for manipulation of mesenchymal and hematopoietic cells. The electroactive surface was based on the conducting polymer polypyrrole for dynamic control of the presentation and mineralisation of chondrocyte-derived plasma membrane nanofragments (PMNFs) covalently immobilized on the surface. Electrochemical redox switching resulted in the PMNF-based formation of bone minerals with different morphologies, which further demonstrated to have distinct effects on the survival of mouse bone marrow-derived mesenchymal and hematopoietic cell populations cultured on the surface. This tunable electroactive surface could be a valuable tool for dynamically sensing and/or controlling stem cell functions in more suitable biomimetic microenvironments housing a stem cell niche.
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| 4. |
- Dahlqvist, Johanna, 1979-, et al.
(författare)
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Identification and functional characterization of a novel susceptibility locus for small vessel vasculitis with MPO-ANCA
- 2022
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Ingår i: Rheumatology. - Oxford, United Kingdom : Oxford University Press (OUP). - 1462-0324 .- 1462-0332. ; 61:8, s. 3461-3470
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Tidskriftsartikel (refereegranskat)abstract
- Objective To identify and characterize genetic loci associated with the risk of developing ANCA-associated vasculitides (AAV). Methods Genetic association analyses were performed after Illumina sequencing of 1853 genes and subsequent replication with genotyping of selected single nucleotide polymorphisms in a total cohort of 1110 Scandinavian cases with granulomatosis with polyangiitis or microscopic polyangiitis, and 1589 controls. A novel AAV-associated single nucleotide polymorphism was analysed for allele-specific effects on gene expression using luciferase reporter assay. Results PR3-ANCA(+) AAV was significantly associated with two independent loci in the HLA-DPB1/HLA-DPA1 region [rs1042335, P = 6.3 x 10(-61), odds ratio (OR) 0.10; rs9277341, P = 1.5 x 10(-44), OR 0.22] and with rs28929474 in the SERPINA1 gene (P = 2.7 x 10(-10), OR 2.9). MPO-ANCA(+) AAV was significantly associated with the HLA-DQB1/HLA-DQA2 locus (rs9274619, P = 5.4 x 10(-25), OR 3.7) and with a rare variant in the BACH2 gene (rs78275221, P = 7.9 x 10(-7), OR 3.0), the latter a novel susceptibility locus for MPO-ANCA(+) granulomatosis with polyangiitis/microscopic polyangiitis. The rs78275221-A risk allele reduced luciferase gene expression in endothelial cells, specifically, as compared with the non-risk allele. Conclusion We identified a novel susceptibility locus for MPO-ANCA(+) AAV and propose that the associated variant is of mechanistic importance, exerting a regulatory function on gene expression in specific cell types.
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| 5. |
- Hultin, Hanna
(författare)
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Generative models of limit order books
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis generative models in machine learning are developed with the overall aim to improve methods for algorithmic trading on high-frequency electronic exchanges based on limit order books. The thesis consists of two papers.In the first paper a new generative model for the dynamic evolution of a limit order book, based on recurrent neural networks, is developed. The model captures the full dynamics of the limit order book by decomposing the probability of each transition of the limit order book into a product of conditional probabilities of order type, price level, order size, and time delay. Each such conditional probability is modeled by a recurrent neural network. In addition several evaluation metrics for generative models related to order execution are introduced. The generative model is successfully trained to fit both synthetic data generated by a Markov model and real data from the Nasdaq Stockholm exchange.The second paper explores reinforcement learning methods to find optimal policies for trading execution in Markovian models. A number of different approaches are implemented and compared, including a baseline time-weighted average price (TWAP) strategy, tabular Q-learning, and deep Q-learning based on predefined features as well as with the entire limit order book as input. The results indicate that it is preferable to use deep Q-learning with the entire limit order book as input to design efficient execution policies. In order to improve the understanding of the decisions taken by the agent, the learned action-value function for the deep Q-learning with predefined features is visualized as a function of selected features.
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| 6. |
- Hultin, Kim, 1976-
(författare)
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Primary Marine Aerosol Production : Studies using bubble-bursting experiments
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aerosol particles affect the Earth’s climate, although their impact is associated with large uncertainties. Primary marine aerosol represents a significant fraction of the global aerosol budget considering the Earth’s 70-percentage coverage by oceans. They are produced when bubbles burst at the ocean surface and can consist of sea salt, organic matter and bacteria. An experimental approach was here used to investigate the primary marine aerosol production from the bubble-bursting mechanism using water from four different geographical locations. The main findings include: Similar and stable aerosol number size distributions at all locations, centered close to 0.2 μm. Largely varying aerosol organic fractions, both with size and location. Clear tendency for increased water temperature to negatively influence the aerosol production. No covariance between surface water chlorophyll α and aerosol production on a 10-minute time scale, although decreased aerosol production was observed at times of elevated phytoplankton activity on longer time scales. Mainly external mixtures of sea salt and organics was observed. A high tendency for colony-forming marine bacteria to use bubble-bursting to reach the atmosphere. A clear diurnal cycle in aerosol production was found for both laboratory produced aerosol and in-situ aerosol fluxes, probably biologically driven. The first near coastal sea spray fluxes with limited fetch and low salinity. While the primary marine aerosol spectral shape is stable, emission concentration varies with environmental parameters. Above that, the organic fraction of the aerosol varies largely between locations. This shows that observations of primary marine aerosol emissions not necessarily can be applied to large time- or spatial scales.
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| 7. |
- Hultin, Magnus, et al.
(författare)
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Spontaneous Conversions of Supraventricular Tachycardia to Sinus Rhythm in Children After Premedication With Intranasal Dexmedetomidine : A Case Report
- 2018
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Ingår i: A&A Practice. - 2575-3126. ; 11:8, s. 219-220
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Tidskriftsartikel (refereegranskat)abstract
- Intranasal dexmedetomidine administered as premedication before anesthesia and cardioversion appears to have the potential to facilitate the return of sinus rhythm. Two children, 3.5 and 1.5 years old, with recurrent supraventricular tachycardia in need of cardioversion have now on several occasions spontaneously returned to sinus rhythm within 20-40 minutes after intranasal administration of dexmedetomidine (4 µg/kg) with a mucosal atomization device. Both children were observed on all occasions at the pediatric outpatient clinic and could return home within 2 hours of cardioversion. For children with supraventricular tachycardia, a selective alpha2-agonist might be a valuable alternative to cardioversion with adenosine.
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| 8. |
- Hultin, Magnus, et al.
(författare)
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Vi tror provet ger ett bra resultat
- 2017
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Ingår i: Dagens Medicin. - : Bonnier Business Media Sweden. - 1104-7488.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Vår förhoppning är att det nya systemet ger förutsättningar för fler att få arbeta med det som han eller hon är utbildad för och med det som svensk hälso- och sjukvård så tydligt efterfrågar, skriver Magnus Hultin och Erik Magnusson i ett svar till ett tidigare debattinlägg.
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| 9. |
- Khalilian, Maryam, et al.
(författare)
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Dislocation-Free and Atomically Flat GaN Hexagonal Microprisms for Device Applications
- 2020
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Ingår i: Small. - : Wiley-VCH Verlag. - 1613-6810 .- 1613-6829. ; 16:30
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Tidskriftsartikel (refereegranskat)abstract
- III-nitrides are considered the material of choice for light-emitting diodes (LEDs) and lasers in the visible to ultraviolet spectral range. The development is hampered by lattice and thermal mismatch between the nitride layers and the growth substrate leading to high dislocation densities. In order to overcome the issue, efforts have gone into selected area growth of nanowires (NWs), using their small footprint in the substrate to grow virtually dislocation-free material. Their geometry is defined by six tall side-facets and a pointed tip which limits the design of optoelectronic devices. Growth of dislocation-free and atomically smooth 3D hexagonal GaN micro-prisms with a flat, micrometer-sized top-surface is presented. These self-forming structures are suitable for optical devices such as low-loss optical cavities for high-efficiency LEDs. The structures are made by annealing GaN NWs with a thick radial shell, reforming them into hexagonal flat-top prisms with six equivalents either m- or s-facets depending on the initial heights of the top pyramid and m-facets of the NWs. This shape is kinetically controlled and the reformation can be explained with a phenomenological model based on Wulff construction that have been developed. It is expected that the results will inspire further research into micron-sized III-nitride-based devices. © 2020 The Authors.
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| 10. |
- Magnusson, Erik, et al.
(författare)
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Längre skrivtid och nya chanser i det nya kunskapsprovet för läkare
- 2017
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Ingår i: Läkartidningen. - : Sveriges läkarförbund. - 0023-7205 .- 1652-7518. ; 114:08
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Socialstyrelsen och Umeå universitet förlänger provtiden till fyra timmar för det teoretiska delprovet i det nya kunskapsprovet för läkare. Dessutom behöver de med underkända resultat vid de första två provtillfällena inte räkna in dem i de maximalt tre försök de har på sig att klara provet. Socialstyrelsen kommer att kontakta berörda.
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