| 1. |
- Gaines, Hans, et al.
(författare)
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Six-week follow-up after HIV-1 exposure: a position statement from the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy
- 2016
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Ingår i: Infectious Diseases. - : Informa UK Limited. - 2374-4235 .- 2374-4243. ; 48:2, s. 93-98
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Forskningsöversikt (refereegranskat)abstract
- In 2014 the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy (RAV) conducted a review and analysis of the state of knowledge on the duration of follow-up after exposure to human immunodeficiency virus (HIV). Up until then a follow-up of 12 weeks after exposure had been recommended, but improved tests and new information on early diagnosis motivated a re-evaluation of the national recommendations by experts representing infectious diseases and microbiology, county medical officers, the RAV, the Public Health Agency, and other national authorities. Based on the current state of knowledge the Public Health Agency of Sweden and the RAV recommend, starting in April 2015, a follow-up period of 6 weeks after possible HIV-1 exposure, if HIV testing is performed using laboratory-based combination tests detecting both HIV antibody and antigen. If point-of-care rapid HIV tests are used, a follow-up period of 8 weeks is recommended, because currently available rapid tests have insufficient sensitivity for detection of HIV-1 antigen. A follow-up period of 12 weeks is recommended after a possible exposure for HIV-2, since presently used assays do not include HIV-2 antigens and only limited information is available on the development of HIV antibodies during early HIV-2 infection. If pre- or post-exposure prophylaxis is administered, the follow-up period is recommended to begin after completion of prophylaxis. Even if infection cannot be reliably excluded before the end of the recommended follow-up period, HIV testing should be performed at first contact for persons who seek such testing.
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| 2. |
- Lindh, Anders, et al.
(författare)
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A model for granite evolution based on non-equilibrium magma separation : evidence from the Gharib and Qattar fluorite-bearing granites, Eastern Desert, Egypt
- 2019
-
Ingår i: International Journal of Earth Sciences. - : Springer Science and Business Media LLC. - 1437-3254 .- 1437-3262. ; 108:4, s. 1201-1232
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Tidskriftsartikel (refereegranskat)abstract
- We present 77 new granite whole-rock analyses from the Qattar and Gharib areas, Eastern Desert, Egypt. Both areas include a “normal” granite and either a hypersolvus (Gharib) or an almost plagioclase-free granite (Qattar) enriched in fluorite. According to earlier results, F influences element distribution in granitic melts forming complexes with specific elements as Nb, Ta, Ga, Hf, Th, Zn, Sn, whereas F excludes Ba and Sr. We use principal component analyses to split the granite into chemical groups allowing an unbiased study of the inter-group element distribution. This adds the heavy REEs and Y to the earlier lists of elements with an affinity for F. The light REEs show a decreasing affinity with decreasing atomic mass; fluorine separates Sm from Nd, whereas Zr follows La. Opposite to some, but in accordance with other earlier results, the ratio Nb/Ta is higher in the fluorite-enriched than in the other granite. Weak tetrad effects are present. Zircon in the hypersolvus granite is high in common lead. We suggest F to be instrumental for separating Pb 2+ from Pb 4+ . Two hypotheses may explain the occurrence of the two contrasting granites: they have either different sources, or they are co-magmatic, but the magma was split into two discrete types. We apply the second hypothesis as our working hypothesis. The liquidus has a gentler slope with pressure than the diapir requiring crystallisation to be most important in the lower part of the magma chamber. Our hypothesis suggests that globules of magma, enriched in volatile components, form during crystallisation due to slow diffusion rates in the crystallizing magma. Elements accompanying F are distributed into this magma batch, which has a lowered density and viscosity than the rest of the magma due to its increased contents of volatile components. A mushroom-formed diapir rises, forming the hypersolvus (or almost plagioclase-free) granite. Due to an edge effect, it is concentrated close to the wall of the magma chamber. The size and form of the outcropping granite depend on the intersection of the diapir with the erosion surface. Fluorine only makes it possible to follow the process. The model may be generalised to explain the diversification of non-F enriched granite, since the buoyancy of a magma batch several thousand m 3 in size has a much larger impact on the system than the small negative buoyancy of crystals or small crystal aggregates. A-type granite classified merely from its trace element content may form from separated F-enriched magma batches. This may be the reason for their high frequency in the Eastern Desert.
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| 3. |
- Persson, Anders, et al.
(författare)
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Trophic interactions
- 2018
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Ingår i: Biology and ecology of pike. - Boca Raton : CRC Press. - 9781482262902
-
Bokkapitel (refereegranskat)
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| 4. |
- Wang, Tao, et al.
(författare)
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Mineral surface-reactive metabolites secreted during fungal decomposition contribute to the formation of soil organic matter
- 2017
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912. ; 19:12, s. 5117-5129
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Tidskriftsartikel (refereegranskat)abstract
- Soil organic matter (SOM) constitutes the largest terrestrial C pool. An emerging, untested, view is that oxidation and depolymerization of SOM by microorganisms promote the formation of SOM-mineral associations that is critical for SOM stabilization. To test this hypothesis, we performed laboratory-scale experiments involving one ectomycorrhizal and one saprotrophic fungus that represent the two major functional groups of microbial decomposers in the boreal forest soils. Fungal decomposition enhanced the retention of SOM on goethite, partly because of oxidative modifications of organic matter (OM) by the fungi. Moreover, both fungi secreted substantial amounts (> 10% new biomass C) of aromatic metabolites that also contributed to an enhanced mineral retention of OM. Our study demonstrates that soil fungi can form mineral-stabilized SOM not only by oxidative conversion of the SOM but also by synthesizing mineral surface-reactive metabolites. Metabolites produced by fungal decomposers can play a yet overlooked role in the formation and stabilization of SOM.
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| 5. |
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| 6. |
- Ahlberg, Erik, et al.
(författare)
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"Vi klimatforskare stödjer Greta och skolungdomarna"
- 2019
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Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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| 7. |
- Andersson, Malin, et al.
(författare)
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How to measure renal artery stenosis - a retrospective comparison of morphological measurement approaches in relation to hemodynamic significance
- 2015
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Ingår i: BMC Medical Imaging. - : BioMed Central. - 1471-2342. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although it is well known that renal artery stenosis may cause renovascular hypertension, it is unclear how the degree of stenosis should best be measured in morphological images. The aim of this study was to determine which morphological measures from Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA) are best in predicting whether a renal artery stenosis is hemodynamically significant or not. Methods: Forty-seven patients with hypertension and a clinical suspicion of renovascular hypertension were examined with CTA, MRA, captopril-enhanced renography (CER) and captopril test (Ctest). CTA and MRA images of the renal arteries were analyzed by two readers using interactive vessel segmentation software. The measures included minimum diameter, minimum area, diameter reduction and area reduction. In addition, two radiologists visually judged the diameter reduction without automated segmentation. The results were then compared using limits of agreement and intra-class correlation, and correlated with the results from CER combined with Ctest (which were used as standard of reference) using receiver operating characteristics (ROC) analysis. Results: A total of 68 kidneys had all three investigations (CTA, MRA and CER + Ctest), where 11 kidneys (16.2 %) got a positive result on the CER + Ctest. The greatest area under ROC curve (AUROC) was found for the area reduction on MRA, with a value of 0.91 (95 % confidence interval 0.82-0.99), excluding accessory renal arteries. As comparison, the AUROC for the radiologists' visual assessments on CTA and MRA were 0.90 (0.82-0.98) and 0.91 (0.83-0.99) respectively. None of the differences were statistically significant. Conclusions: No significant differences were found between the morphological measures in their ability to predict hemodynamically significant stenosis, but a tendency of MRA having higher AUROC than CTA. There was no significant difference between measurements made by the radiologists and measurements made with fuzzy connectedness segmentation. Further studies are required to definitely identify the optimal measurement approach.
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| 8. |
- Andreasson, Ida
(författare)
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Regional plan för infrastuktur för elfordon och förnybara drivmedel : Kronobergs län Rapport 2019-12-18
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige har som mål att vara klimatneutralt senast år 2045. Transporterna står för en stor del av våra klimatpåverkande utsläpp nationellt och regionalt. Inom transportsektorn ska utsläppen minska med 70 procent till år 2030 jämfört med år 2010 – ett av de mest ambitiösa klimatmålen i världen. För att nå målet är samhället i behov en snabb övergång till förnybara drivmedel inom transportsektorn. Omställningen kräver engagemang, innovationer och handlingskraft från samhällets alla berörda aktörer. För att nå målet kommer det behövas flera förnybara drivmedel inom den nuvarande och framtida fordonsflottan. En väl fungerande publik infrastruktur för förnybara drivmedel med god geografisk täckning är därför en helt avgörande förutsättning för omställningen till en fossilfri fordonspark.Denna plan är en del av Länsstyrelsens regleringsbrevsuppdrag 3.19 för budgetåren 2018 och 2019. Uppdraget har genomförts i dialog med Länsstyrelserna, Energimyndigheten och Trafikverket, länets kommuner, Region Kronoberg, Energikontor sydost, Miljöfordon Sverige, Småländska bränslen, Eon samt Bee Charging. Samverkan kring framtagande av planen har skett med närliggande länsstyrelser i Blekinge, Kalmar och Jönköpings län.I utredningen ”Strategisk plan för transportsektorns omställning till fossilfrihet” har sex nationella myndigheter lagt fram ett antal förslag kring insatser som behövs för transportsektorns omställning. Enligt utredningen står omställning till fossilfrihet på tre ben – ett mer transporteffektivt samhälle, energieffektiva och fossilfria fordon samt högre andel förnybara drivmedel. Med transporteffektivt samhälle menas att transportarbetet med personbil, lastbil och flyg ska minska. Detta kan ske genom att transporter överflyttas till mer ener-gieffektiva trafikslag, kortas eller ersättas helt. Energieffektiva och fossilfria fordon fås genom att ställa krav på nya fordons koldioxidutsläpp. Högre andel förnybara drivmedel realiseras i en kombination av insatser inom produktion distribut-ion och användning.I utredningen lämnades förslag om upprättande av regionala planer till stöd för in-frastruktur för förnybara drivmedel (förslag och åtaganden 2.1.10).
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| 9. |
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| 10. |
- Cronberg, Tobias, et al.
(författare)
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Neurologic Function and Health-Related Quality of Life in Patients Following Targeted Temperature Management at 33 degrees C vs 36 degrees C After Out-of-Hospital Cardiac Arrest A Randomized Clinical Trial
- 2015
-
Ingår i: JAMA Neurology. - : American Medical Association. - 2168-6149 .- 2168-6157. ; 72:6, s. 634-641
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Brain injury affects neurologic function and quality of life in survivors after cardiac arrest. OBJECTIVE To compare the effects of 2 target temperature regimens on long-term cognitive function and quality of life after cardiac arrest. DESIGN, SETTING, AND PARTICIPANTS In this multicenter, international, parallel group, assessor-masked randomized clinical trial performed from November 11, 2010, through January 10, 2013, we enrolled 950 unconscious adults with cardiac arrest of presumed cardiac cause from 36 intensive care units in Europe and Australia. Eleven patients were excluded from analysis for a total sample size of 939. INTERVENTIONS Targeted temperature management at 33 degrees C vs 36 degrees C. MAIN OUTCOMES AND MEASURES Cognitive function was measured by the Mini-Mental State Examination (MMSE) and assessed by observers through the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Patients reported their activities in daily life and mental recovery through Two Simple Questions and their quality of life through the Medical Outcomes Study 36-Item Short Form Health Survey, version 2. RESULTS In the modified intent-to-treat population, including nonsurvivors, the median MMSE score was 14 in the 33 degrees C group (interquartile range [IQR], 0-28) vs 17 in the 36 degrees C group (IQR, 0-29) (P = .77), and the IQCODE score was 115 (IQR, 79-130) vs 115 (IQR, 80-130) (P = .57) in the 33 degrees C and 36 degrees C groups, respectively. The median MMSE score for survivors was within the reference range and similar (33 degrees C group median, 28; IQR, 26-30; vs 36 degrees C group median, 28; IQR, 25-30; P = .61). The median IQCODE score was within the minor deficit range (33 degrees C group median, 79.5; IQR, 78.0-85.9; vs 36 degrees C group median, 80.7; IQR, 78.0-86.9; P = .04). A total of 18.8% vs 17.5% of survivors reported needing help with everyday activities (P = .71), and 66.5% in the 33 degrees C group vs 61.8% in the 36 degrees C group reported that they thought they had made a complete mental recovery (P = .32). The mean (SD) mental component summary score was 49.1 (12.5) vs 49.0 (12.2) (P = .79), and the mean (SD) physical component summary score was 46.8 (13.8) and 47.5 (13.8) (P = .45), comparable to the population norm. CONCLUSIONS AND RELEVANCE Quality of life was good and similar in patients with cardiac arrest receiving targeted temperature management at 33 degrees C or 36 degrees C. Cognitive function was similar in both intervention groups, but many patients and observers reported impairment not detected previously by standard outcome scales.
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| 11. |
- Ellström, Magnus, et al.
(författare)
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The carbon starvation response of the ectomycorrhizal fungus Paxillus involutus.
- 2015
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 1574-6941. ; 91:4
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Tidskriftsartikel (refereegranskat)abstract
- The amounts of carbon allocated to the fungal partner in ectomycorrhizal associations can vary substantially depending on the plant growth and the soil nutrient conditions, and the fungus may frequently be confronted with limitations in carbon. We used chemical analysis and transcriptome profiling to examine the physiological response of the ectomycorrhizal fungus Paxillus involutus to carbon starvation during axenic cultivation. Carbon starvation induced a decrease in the biomass. Concomitantly, ammonium, cell-wall material (chitin) and proteolytic enzymes were released into the medium, which suggest autolysis. Compared with the transcriptome of actively growing hyphae, about 45% of the transcripts analyzed were differentially regulated during C-starvation. Induced during starvation were transcripts encoding extracellular enzymes such as peptidases, chitinases, and laccases. In parallel, transcripts of N-transporters were upregulated, which suggest that some of the released nitrogen compounds were re-assimilated by the mycelium. The observed changes suggest that the carbon-starvation response in P. involutus is associated with complex cellular changes that involves autolysis, recycling of intracellular compounds by autophagy and reabsorption of the extracellular released material. The study provides molecular markers that can be used to examine the role of autolysis for the turnover and survival of the ectomycorrhizal mycelium in soils.
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| 12. |
- Fraser, Magdalena
(författare)
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People of the Dolmens and Stone Cists : An archaeogenetic Investigation of Megalithic Graves from the Neolithic Period on Gotland
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of ancient genomics of pre-historic human remains has in recent years offered unprecedented knowledge regarding pre-historic migration and population structure on the European continent which has fundamentally altered the current views in the archaeological community. However, the merging of the two fields, archaeology and genetics, is still in its infancy and much work is still needed in order for these fields to integrate. In this thesis I explore how genetic analyses, in combination with contextual radiocarbon dating and isotopic analyses for diet and mobility can be used to investigate demographic events on a local and regional level. This is done through the investigation of people buried in five previously excavated megalithic tombs on the Island of Gotland dated to the Neolithic period. I present the genomic population structure and archaeological background for the pre-historic European reference data and show how this is used to investigate population continuity, demographic shifts, cultural duality, and admixture for local and regional contexts. I present new data and explore the Strontium-baseline for the Gotland biosphere which is used for the mobility analyses. I show that mitochondrial haplogroup data is especially useful in combination with isotopic data, and radiocarbon dating for investigation of demographic shifts on a larger scale. I also show that genomic data gives unique insights into the individuals’ life history which, together with the established demographic background allows for fine scale investigation of population demographic events within and between different archaeological contexts. Finally I show that the different Neolithic contexts on Gotland to a large extent involves immigration of new groups to the island, and that the contextual breaks seen in the archaeological record during the Neolithic period are connected with cultural and population demographic shifts. This dissertation demonstrates that genomic analyses, in combination with archaeology and isotopic analyses, as well as contextual osteological analyses and radiocarbon dating, present unique insights into the life history of the actual people who lived the lives we try to understand.
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| 13. |
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| 14. |
- Gentile, Luigi, et al.
(författare)
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Ferrihydrite Nanoparticle Aggregation Induced by Dissolved Organic Matter
- 2018
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 122:38, s. 7730-7738
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Tidskriftsartikel (refereegranskat)abstract
- Ferrihydrite (Fh) nanoparticles are omnipresent in nature and often highly mobile because of their colloidal stability. Thus, Fh serves as a vector for iron as well as associated nutrients and contaminants. Here, we demonstrate, using small-angle X-ray scattering combined with cryo-transmission electron microscopy (cryo-TEM), that dissolved organic matter (DOM), extracted from a boreal forest soil, induce aggregation of Fh nanoparticles, of radius 3 nm, into fractal aggregates, having a fractal dimension D = 1.7. The DOM consists of both fractal-like colloids (>100 nm) and small molecular DOM, but the attractive Fh interparticle interaction was mediated by molecular DOM alone as shown by cryo-TEM. This highlights the importance of using soil extracts, including all size fractions, in studies of the colloidal behavior of DOM-mineral aggregates. The Fh nanoparticles also self-assemble during synthesis into aggregates with the same fractal dimension as the DOM-Fh aggregates. We propose that, in both the absence and presence of DOM, the aggregation is controlled by the Fh particle charge, and the process can be viewed as a linear polymerization into a self-avoiding random walk structure. The theoretical D value for this is 5/3, which is in close agreement with our Fh and DOM-Fh results.
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| 15. |
- Idborg, Helena, et al.
(författare)
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Circulating Levels of Interferon Regulatory Factor-5 Associates With Subgroups of Systemic Lupus Erythematosus Patients
- 2019
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Ingår i: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Systemic Lupus Erythematosus (SLE) is a heterogeneous autoimmune disease, which currently lacks specific diagnostic biomarkers. The diversity within the patients obstructs clinical trials but may also reflect differences in underlying pathogenesis. Our objective was to obtain protein profiles to identify potential general biomarkers of SLE and to determine molecular subgroups within SLE for patient stratification. Plasma samples from a cross-sectional study of well-characterized SLE patients (n = 379) and matched population controls (n = 316) were analyzed by antibody suspension bead array targeting 281 proteins. To investigate the differences between SLE and controls, Mann-Whitney U-test with Bonferroni correction, generalized linear modeling and receiver operating characteristics (ROC) analysis were performed. K-means clustering was used to identify molecular SLE subgroups. We identified Interferon regulating factor 5 (IRF5), solute carrier family 22 member 2 (SLC22A2) and S100 calcium binding protein A12 (S100A12) as the three proteins with the largest fold change between SLE patients and controls (SLE/Control = 1.4, 1.4, and 1.2 respectively). The lowest p-values comparing SLE patients and controls were obtained for S100A12, Matrix metalloproteinase-1 (MMP1) and SLC22A2 (p(adjusted) = 3 x 10(-9), 3 x 10(-6), and 5 x 10(-6) respectively). In a set of 15 potential biomarkers differentiating SLE patients and controls, two of the proteins were transcription factors, i.e., IRF5 and SAM pointed domain containing ETS transcription factor (SPDEF). IRF5 was up-regulated while SPDEF was found to be down-regulated in SLE patients. Unsupervised clustering of all investigated proteins identified three molecular subgroups among SLE patients, characterized by (1) high levels of rheumatoid factor-IgM, (2) low IRF5, and (3) high IRF5. IRF5 expressing microparticles were analyzed by flow cytometry in a subset of patients to confirm the presence of IRF5 in plasma and detection of extracellular IRF5 was further confirmed by immunoprecipitation-mass spectrometry (IP-MS). Interestingly IRF5, a known genetic risk factor for SLE, was detected extracellularly and suggested by unsupervised clustering analysis to differentiate between SLE subgroups. Our results imply a set of circulating molecules as markers of possible pathogenic importance in SLE. We believe that these findings could be of relevance for understanding the pathogenesis and diversity of SLE, as well as for selection of patients in clinical trials.
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| 16. |
- Johnson, Linda S.B., et al.
(författare)
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Irregularity and lack of p waves in short tachycardia episodes predict atrial fibrillation and ischemic stroke
- 2018
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Ingår i: Heart Rhythm. - : Elsevier BV. - 1547-5271. ; 15:6, s. 805-811
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Tidskriftsartikel (refereegranskat)abstract
- Background: Atrial fibrillation (AF) is defined as an irregular supraventricular tachycardia (SVT) without p waves, with duration >30 seconds. Whether AF characteristics during short SVT episodes predict AF and stroke is not known. Objective: The purpose of this study was to determine whether irregularity and lack of p waves, alone or in combination, during short SVT episodes increase the risk of incident AF and ischemic stroke. Methods: The population-based Malmö Diet and Cancer study includes 24-hour ECG screening of 377 AF-free individuals (mean age 64.5 years; 43% men) who were prospectively followed for >13 years. There were 65 AF events and 25 ischemic stroke events during follow-up. Subjects with an SVT episode ≥5 beats were identified, and the longest SVT episode was assessed for irregularity and lack of p waves. The association between SVT classification and AF and stroke was assessed using multivariable adjusted Cox regression. Results: The incidence of AF increased with increasing abnormality of the SVTs. The risk-factor adjusted hazard ratio for AF was 4.95 (95% confidence interval 2.06–11.9; P <.0001) for those with short irregular SVTs (<70 beats) without p waves. The incidence of ischemic stroke was highest in the group with regular SVT episodes without p waves (hazard ratio 14.2; 95% confidence interval 3.76–57.6; P <.0001, adjusted for age and sex). Conclusion: Characteristics of short SVT episodes detected at 24-hour ECG screening are associated with incident AF and ischemic stroke. Short irregular SVTs without p waves likely represent early stages of AF or atrial myopathy. Twenty-four–hour ECG could identify subjects suitable for primary prevention efforts.
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| 17. |
- Karlsson, Linda H., et al.
(författare)
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Atomically resolved microscopy of ion implantation induced dislocation loops in 4H-SiC
- 2016
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Ingår i: Materials letters (General ed.). - : Elsevier. - 0167-577X .- 1873-4979. ; 181, s. 325-327
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Tidskriftsartikel (refereegranskat)abstract
- During high temperature electrical activation of ion-implanted dopant species in SiC, extrinsic dislocation loops are formed on the basal planes of the SiC lattice. Investigations have suggested Si-based loops are caused in accordance with the well-known +1 model. Herein we apply aberration corrected STEM to resolve the atomic structure of these loops. It is shown that the dislocation loops formed during annealing of Al-implanted SiC consist of an extra inserted Si-C bilayer of the (0001) polar sense, which upon insertion into the lattice causes a local extrinsic stacking fault. The +1 model thus needs to be expanded for binary systems. (C) 2016 Elsevier B.V. All rights reserved.
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| 18. |
- Kashuba, Natalija, et al.
(författare)
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Ancient DNA from mastics solidifies connection between material culture and genetics of mesolithic hunter-gatherers in Scandinavia
- 2019
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Human demography research in grounded on the information derived from ancient DNA and archaeology. For example, the study on the early postglacial dual-route colonisation of the Scandinavian Peninsula is largely based on associating genomic data with the early dispersal of lithic technology from the East European Plain. However, a clear connection between material culture and genetics has been lacking. Here, we demonstrate that direct connection by analysing human DNA from chewed birch bark pitch mastics. These samples were discovered at Huseby Klev in western Sweden, a Mesolithic site with eastern lithic technology. We generated genome-wide data for three individuals, and show their affinity to the Scandinavian hunter-gatherers. Our samples date to 9880-9540 calBP, expanding the temporal range and distribution of the early Scandinavian genetic group. We propose that DNA from ancient mastics can be used to study environment and ecology of prehistoric populations.
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| 19. |
- Kristiansen, Per Eugen, et al.
(författare)
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Nuclear Magnetic Resonance Structure and Mutational Analysis of the Lactococcin A Immunity Protein.
- 2016
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 1520-4995 .- 0006-2960. ; 55:45, s. 6250-6257
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Tidskriftsartikel (refereegranskat)abstract
- The class IId bacteriocin lactococcin A and the pediocin-like bacteriocins induce membrane leakage and cell death by specifically binding the mannose phophotransferase system (man-PTS) on their target cells. The bacteriocins' cognate immunity proteins that protect the producer cell from its own bacteriocin recognize and bind to the bacteriocin-man-PTS complex and thereby block membrane leakage. In this study, we have determined the three-dimensional structure of the lactococcin A immunity protein (LciA) by the use of nuclear magnetic resonance spectroscopy. LciA forms a four-helix bundle structure with a flexible C-terminal tail. Despite the low degree of sequence similarity between LciA and the pediocin-like immunity proteins, they share the same fold. However, there are certain differences between the structures. The C-terminal helix in LciA is considerably shorter than that observed in the pediocin-like immunity proteins, and the surface potentials of the immunity proteins differ. Truncated variants of LciA in which 6 or 10 of the C-terminal residues were removed yielded a reduced degree of protection, indicating that the unstructured C-terminal tail is important for the functionality of the immunity proteins.
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| 20. |
- Krumina, Lelde, et al.
(författare)
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Oxidation of a Dimethoxyhydroquinone by Ferrihydrite and Goethite Nanoparticles : Iron Reduction versus Surface Catalysis
- 2017
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 51:16, s. 9053-9061
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Tidskriftsartikel (refereegranskat)abstract
- Hydroquinones are important mediators of electron transfer reactions in soils with a capability to reduce Fe(III) minerals and molecular oxygen, and thereby generating Fenton chemistry reagents. This study focused on 2,6-dimethoxy hydroquinone (2,6-DMHQ), an analogue to a common fungal metabolite, and its reaction with ferrihydrite and goethite under variable pH and oxygen concentrations. Combined wet-chemical and spectroscopic analyses showed that both minerals effectively oxidized 2,6-DMHQ in the presence of oxygen. Under anaerobic conditions the first-order oxidation rate constants decreased by one to several orders of magnitude depending on pH and mineral. Comparison between aerobic and anaerobic results showed that ferrihydrite promoted 2,6-DMHQ oxidation both via reductive dissolution and heterogeneous catalysis while goethite mainly caused catalytic oxidation. These results were in agreement with changes in the reduction potential (EH) of the Fe(III) oxide/Fe(II)aq redox couple as a function of dissolved Fe(II) where EH of goethite was lower than ferrihydrite at any given Fe(II) concentration, which makes ferrihydrite more prone to reductive dissolution by the 2,6-DMBQ/2,6-DMHQ redox couple. This study showed that reactions between hydroquinones and iron oxides could produce favorable conditions for formation of reactive oxygen species, which are required for nonenzymatic Fenton-based decomposition of soil organic matter.
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| 21. |
- Larsson, Ida, 1978-, et al.
(författare)
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Development of a screening test based on isothermal calorimetry for determination of self-heating potential of biomass pellets
- 2017
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Ingår i: Fire and Materials. - : John Wiley & Sons. - 0308-0501 .- 1099-1018. ; 41:8, s. 940-952
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Tidskriftsartikel (refereegranskat)abstract
- For the risk for spontaneous combustion in storage of biomass pellets to be assessed, it is important to know how prone the fuel is to self-heating. There are traditional methods that are used to determine self-heating characteristics of fuels, eg, basket heating tests. The results from basket heating tests indirectly give the reactivity from a series of tests at high temperatures. This paper presents a sensitive screening test procedure for biomass pellets using isothermal calorimetry for direct measurement of the heat production rate at typical bulk storage temperatures. This method can be used to directly compare the reactivity of different batches of biomass pellets. The results could be used, eg, by storage security managers to gain better knowledge of their fuels propensity for self-heating and thereby for safer storage. A large number of tests have been performed to develop the test procedure presented. Different parameters, such as temperature, type of the test sample (powder/crushed or pellets), mass of test sample, and preheating time, have been varied. Furthermore, gas concentrations in the sample ampoule have been measured before and after some tests to study the oxygen consumption and the formation of CO and CO2. Three different types of pellets with different characteristics were tested to assess the variation in behaviour. Based on these tests, a screening test procedure is presented with a test temperature of 60°C, a sample size of 4 g, a 15-minute preheating period at the test temperature, and 24-hour test duration.
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| 22. |
- Larsson, Ida, et al.
(författare)
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Measurement of self‐heating potential of biomass pellets with isothermal calorimetry
- 2017
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Ingår i: Fire and Materials. - : John Wiley & Sons. - 0308-0501 .- 1099-1018. ; 41:8, s. 1007-1015
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the risk for spontaneous combustion of biomass pellets during storage it is important to know how prone the fuel is to self-heating, i.e. to determine the reactivity. This article presents the results from isothermal calorimetry tests performed on 31 different biomass pellet batches. The purpose of the tests has been to characterize pellets by measuring the reactivity and investigate how the pellet composition influences the heat release rate and thereby the self-heating potential of pellets. The results from the tests clearly indicate that there is a significant difference in reactivity between different types of pellets. The tested high reactive pellet batches reached maximum specific heat release rates (HRRmax) of 0.61-1.06 mW/g while pellet batches with low reactivity showed HRRmax of 0.05-0.18 mW/g. The tested batches were primarily ranked based on HRRmax but an alternative ranking based on specific total heat release rate during the test period was also used for comparison. The test results also indicate that pine/spruce mix pellets are significantly more reactive than all other types of pellets tested and that pellets consisting of 100 % pine are more reactive than pellets consisting of 100 % spruce. Pellets produced from wine pruning/grape pomace (winery wastes), straw or eucalyptus are not very reactive compared to pellets consisting of pine/spruce. The results also show that the reactivity of the pellets can be reduced by either introducing certain kinds of anti-oxidants into the pellets or by extracting lipids from the raw material of pellets.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Lyngsie, Gry, et al.
(författare)
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Generation of hydroxyl radicals from reactions between a dimethoxyhydroquinone and iron oxide nanoparticles
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The hydroxyl radical (·OH) is a powerful oxidant that is produced in a wide range of environments via the Fenton reaction (Fe2+ + H2O2 → Fe3+ + ·OH + OH-). The reactants are formed from the reduction of Fe3+ and O2, which may be promoted by organic reductants, such as hydroquinones. The aim of this study was to investigate the extent of ·OH formation in reactions between 2,6-dimethoxyhydroquinone (2,6-DMHQ) and iron oxide nanoparticles. We further compared the reactivities of ferrihydrite and goethite and investigated the effects of the O2 concentration and pH on the generation of ·OH. The main finding was that the reactions between 2,6-DMHQ and iron oxide nanoparticles generated substantial amounts of ·OH under certain conditions via parallel reductive dissolution and catalytic oxidation reactions. The presence of O2 was essential for the catalytic oxidation of 2,6-DMHQ and the generation of H2O2. Moreover, the higher reduction potential of ferrihydrite relative to that of goethite made the former species more susceptible to reductive dissolution, which favored the production of ·OH. The results highlighted the effects of surface charge and ligand competition on the 2,6-DMHQ oxidation processes and showed that the co-adsorption of anions can promote the generation of ·OH.
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| 28. |
- Lönnermark, Anders, et al.
(författare)
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Brandsäkerhet vid lagring av avfallsbränslen
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med detta projekt har varit att ge ökad kunskap kring olika förekommande brandrisker och råd om hur dessa kan reduceras med olika åtgärder, primärt baserat på praktiska erfarenheter från genomfört säkerhetsarbete samt uppkomna bränder ute i olika anläggningar. Målet är att de samlade kunskaperna och erfarenheterna kan komma till nytta för hela branschen, övriga berörda intressenter och myndigheter och på sikt ligga till grund för t.ex. framtida branschrekommendationer.Projektet kan delas in metodmässigt i; statistik, workshoppar samt analys av anläggningsspecifik information.Analysen av insatsstatistik från Myndigheten för samhällsskydd och beredskap (MSB) pekar på att det inträffar i storleksordningen 60–70 bränder årligen i avfallsanläggningar och att brandorsaken i de flesta fall är självantändning eller okänd anledning. Tittar man på "brand ej i byggnad" med relevanta bränder för avfallsanläggningar så ser man en svagt ökande trend i antal bränder 2012–2015. De vanligaste materialfraktionerna som enligt statistik från MSB är kopplade till bränder i avfallsanläggningar är sopor, kompost, fluff, papper, trädgårdsavfall, däckgranulat, annat, skrot, återvinningscontainrar. Även en del av flisbränderna kan vara relaterade till RT-trä.Från avfallsindustrins sida ansågs bark, returträ, flisat material och GROT (grenar och toppar) kunna ge problem med självuppvärmning. Även krossning av avfall angavs som ett generellt problem av flera deltagare.Många incidenter och bränder anses bero på felsorterat eller feldeklarerat avfall och kontrollen av inkommande gods är därför väldigt viktig. Det är också viktigt att kommunicera uppströms i leveranskedjan för att öka chanserna att komma tillrätta med problemen. Många deltagare identifierade batterier (speciellt litiumbatterier) som ett växande problem.Hanteringen av förorenat släckvatten varierar mycket. Man påpekar att samma krav över hela landet vore bra. Man önskar tydligare riktlinjer för släckvattenanalyser, kunskap om vad vattnet kan innehålla och information om reningsmetoder för släckvatten.Det påpekas att det finns många standarder och normer att förhålla sig till så det vore därför bra att ha en lägsta nivå av krav som bestäms i samarbete med branschen som man kan förhålla sig till och någon form av vägledning från myndigheterna för göra hanteringen mer lik över riket.Diskussionerna under workshopparna och tillsammans med projektets referensgrupp har lett fram till 33 rekommendationer uppdelade på olika områden. För varje rekommendation ges i rapporten ytterligare förklaringar. Dessa rekommendationer kan ligga till grund för framtida riktlinjer.
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| 29. |
- Nicolás, César, et al.
(författare)
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Chemical changes in organic matter after fungal colonization in a nitrogen fertilized and unfertilized Norway spruce forest
- 2017
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 419:1-2, s. 113-126
-
Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Decomposition and transformation of organic matter (OM) in forest soils are conducted by the concomitant action of saprotrophic and mycorrhizal fungi. Here, we examine chemical changes in OM after fungal colonization in nitrogen fertilized and unfertilized soils from a Norway spruce forest. Methods: Sand-filled bags amended with composted maize leaves were placed in the forest soil and harvested after 17 months. Infrared and near edge X-ray absorption fine structure spectroscopies were used to study the chemical changes in the OM. Fungal community composition of the bags was also evaluated. Results: The proportion of ectomycorrhizal fungi declined in the fertilized plots, but the overall fungal community composition was similar between N treatments. Decomposition of the OM was, independently of the N level or soil horizon, accompanied by an increase of C/N ratio of the mesh-bag content. Moreover, the proportions of carboxylic compounds in the incubated OM increased in the mineral horizon, while heterocyclic-N compounds decreased, especially in unfertilized plots with higher N demand from the trees. Conclusions: Our results indicate that more oxidized organic C and less heterocyclic-N proportions in the OM remain after fungal colonization in the mineral layers, and suggest that ectomycorrhizal fungi transfer less heterocyclic-N from the mesh bags to the host trees under high N levels.
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| 30. |
- Nicolás, César, et al.
(författare)
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The soil organic matter decomposition mechanisms in ectomycorrhizal fungi are tuned for liberating soil organic nitrogen
- 2018
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Ingår i: ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370.
-
Tidskriftsartikel (refereegranskat)abstract
- Many trees form ectomycorrhizal symbiosis with fungi. During symbiosis, the tree roots supply sugar to the fungi in exchange for nitrogen, and this process is critical for the nitrogen and carbon cycles in forest ecosystems. However, the extents to which ectomycorrhizal fungi can liberate nitrogen and modify the soil organic matter and the mechanisms by which they do so remain unclear since they have lost many enzymes for litter decomposition that were present in their free-living, saprotrophic ancestors. Using time-series spectroscopy and transcriptomics, we examined the ability of two ectomycorrhizal fungi from two independently evolved ectomycorrhizal lineages to mobilize soil organic nitrogen. Both species oxidized the organic matter and accessed the organic nitrogen. The expression of those events was controlled by the availability of glucose and inorganic nitrogen. Despite those similarities, the decomposition mechanisms, including the type of genes involved as well as the patterns of their expression, differed markedly between the two species. Our results suggest that in agreement with their diverse evolutionary origins, ectomycorrhizal fungi use different decomposition mechanisms to access organic nitrogen entrapped in soil organic matter. The timing and magnitude of the expression of the decomposition activity can be controlled by the below-ground nitrogen quality and the above-ground carbon supply.
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| 31. |
- Op De Beeck, Michiel, et al.
(författare)
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Fenton reaction facilitates organic nitrogen acquisition by an ectomycorrhizal fungus
- 2018
-
Ingår i: New Phytologist. - : Wiley. - 0028-646X. ; 218:1, s. 335-343
-
Tidskriftsartikel (refereegranskat)abstract
- Boreal trees rely on their ectomycorrhizal fungal symbionts to acquire growth-limiting nutrients, such as nitrogen (N), which mainly occurs as proteins complexed in soil organic matter (SOM). The mechanisms for liberating this N are unclear as ectomycorrhizal fungi have lost many genes encoding lignocellulose-degrading enzymes present in their saprotrophic ancestors. We hypothesized that hydroxyl radicals (bullOH), produced by the ectomycorrhizal fungus Paxillus involutus during growth on SOM, are involved in liberating organic N. Paxillus involutus was grown for 7 d on N-containing or N-free substrates that represent major organic compounds of SOM. bullOH production, ammonium assimilation, and proteolytic activity were measured daily. bullOH production was strongly induced when P. involutus switched from ammonium to protein as the main N source. Extracellular proteolytic activity was initiated shortly after the oxidation. Oxidized protein substrates induced higher proteolytic activity than unmodified proteins. Dynamic modeling predicted that bullOH production occurs in a burst, regulated mainly by ammonium and ferric iron concentrations. We propose that the production of bullOH and extracellular proteolytic enzymes are regulated by similar nutritional signals. Oxidation works in concert with proteolysis, improving N liberation from proteins in SOM. Organic N mining by ectomycorrhizal fungi has, until now, only been attributed to proteolysis.
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| 32. |
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| 33. |
- Sahlgren, Magnus, et al.
(författare)
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The Gavagai Living Lexicon
- 2016
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Ingår i: 10th edition of the Language Resources and Evaluation Conference, 23-28 May 2016, Portorož (Slovenia). - : ELRA.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the Gavagai Living Lexicon, which is an online distributional semantic model currently available in 14 different languages. We describe the underlying distributional semantic model, and how we have solved some of the challenges in applying such a model to large amounts of streaming data. We also describe the architecture of our implementation, and discuss how we deal with continuous quality assurance of the lexicon.
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| 34. |
- Sarwar, Martuza, et al.
(författare)
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Targeted suppression of AR-V7 using PIP5K1 alpha inhibitor overcomes enzalutamide resistance in prostate cancer cells
- 2016
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 7:39, s. 63065-63081
-
Tidskriftsartikel (refereegranskat)abstract
- One mechanism of resistance of prostate cancer (PCa) to enzalutamide (MDV3100) treatment is the increased expression of AR variants lacking the ligand binding-domain, the best characterized of which is AR-V7. We have previously reported that Phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5K alpha), is a lipid kinase that links to CDK1 and AR pathways. The discovery of PIP5K alpha inhibitor highlight the potential of PIP5K1 alpha as a drug target in PCa. In this study, we show that AR-V7 expression positively correlates with PIP5K1 alpha in tumor specimens from PCa patients. Overexpression of AR-V7 increases PIP5K1 alpha, promotes rapid growth of PCa in xenograft mice, whereas inhibition of PIP5K1 alpha by its inhibitor ISA-2011B suppresses the growth and invasiveness of xenograft tumors overexpressing AR-V7. PIP5K1 alpha is a key co-factor for both AR-V7 and AR, which are present as protein-protein complexes predominantly in the nucleus of PCa cells. In addition, PIP5K1 alpha and CDK1 influence AR-V7 expression also through AKT-associated mechanism dependent on PTEN-status. ISA-2011B disrupts protein stabilization of AR-V7 which is dependent on PIP5K1 alpha, leading to suppression of invasive growth of AR-V7-high tumors in xenograft mice. Our study suggests that combination of enzalutamide and PIP5K1 alpha may have a significant impact on refining therapeutic strategies to circumvent resistance to antiandrogen therapies.
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| 35. |
- Sarwar, Martuza, et al.
(författare)
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Targeted suppression of AR-V7 using PIP5K1α inhibitor overcomes enzalutamide resistance in prostate cancer cells
- 2016
-
Ingår i: Oncotarget. - : Impact Journals. - 1949-2553. ; 7:39, s. 63065-63081
-
Tidskriftsartikel (refereegranskat)abstract
- One mechanism of resistance of prostate cancer (PCa) to enzalutamide (MDV3100) treatment is the increased expression of AR variants lacking the ligand binding-domain, the best characterized of which is AR-V7. We have previously reported that Phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5Kα), is a lipid kinase that links to CDK1 and AR pathways. The discovery of PIP5Kα inhibitor highlight the potential of PIP5K1α as a drug target in PCa. In this study, we show that AR-V7 expression positively correlates with PIP5K1α in tumor specimens from PCa patients. Overexpression of AR-V7 increases PIP5K1α, promotes rapid growth of PCa in xenograft mice, whereas inhibition of PIP5K1α by its inhibitor ISA-2011B suppresses the growth and invasiveness of xenograft tumors overexpressing AR-V7. PIP5K1α is a key co-factor for both AR-V7 and AR, which are present as protein-protein complexes predominantly in the nucleus of PCa cells. In addition, PIP5K1α and CDK1 influence AR-V7 expression also through AKT-associated mechanism dependent on PTEN-status. ISA-2011B disrupts protein stabilization of AR-V7 which is dependent on PIP5K1α, leading to suppression of invasive growth of AR-V7-high tumors in xenograft mice. Our study suggests that combination of enzalutamide and PIP5K1α may have a significant impact on refining therapeutic strategies to circumvent resistance to antiandrogen therapies
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| 36. |
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| 37. |
- Shah, Firoz, et al.
(författare)
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Involutin is a Fe3+ reductant Secreted by the Ectomycorrhizal Fungus Paxillus involutus during Fenton-based Decomposition of Organic Matter.
- 2015
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 81:24, s. 8427-8433
-
Tidskriftsartikel (refereegranskat)abstract
- Ectomycorrhizal fungi play a key role in mobilizing nutrients embedded in recalcitrant organic matter complexes, thereby increasing nutrient accessibility to the host plant. Recent study have shown that during assimilation of nutrients, the ectomycorrhizal fungus Paxillus involutus decomposes organic matter using an oxidative mechanism involving Fenton chemistry (Fe(2+) + H2O2 + H(+) → Fe(3+) + •OH + H2O) similar to that of brown-rot wood-decaying fungi. In such fungi, secreted metabolites are one of the components that drive one-electron reductions of Fe(3+) and O2, generating Fenton chemistry reagents. Here, we investigated whether such a mechanism is also implemented by P. involutus during organic matter decomposition. Activity-guided purification was performed to isolate the Fe(3+)-reducing principle secreted by P. involutus during growth on maize compost extract. The Fe(3+)-reducing activity correlated with the presence of one compound. Mass spectrometry and NMR identified this compound as the diarylcyclopentenone involutin. A major part of the involutin produced by P. involutus during organic matter decomposition was secreted into the medium and the metabolite was not detected when the fungus was grown on a mineral nutrient medium. We also demonstrated that in the presence of H2O2, involutin has the capacity to drive an in vitro Fenton reaction via Fe(3+) reduction. Our results show that the mechanism for reducing Fe(3+) and generating hydroxyl radicals via Fenton chemistry by ectomycorrhizal fungi during organic matter decomposition is similar to that expressed by the evolutionarily related brown-rot saprotrophs during wood decay.
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| 38. |
- Toren, Kjell, et al.
(författare)
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Vital capacity and COPD : the Swedish CArdioPulmonary bioImage Study (SCAPIS)
- 2016
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Ingår i: The International Journal of Chronic Obstructive Pulmonary Disease. - : DOVE MEDICAL PRESS LTD. - 1176-9106 .- 1178-2005. ; 11, s. 927-933
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Tidskriftsartikel (refereegranskat)abstract
- Background: Spirometric diagnosis of chronic obstructive pulmonary disease (COPD) is based on the ratio of forced expiratory volume in 1 second (FEV1)/vital capacity (VC), either as a fixed value <0.7 or below the lower limit of normal (LLN). Forced vital capacity (FVC) is a proxy for VC. The first aim was to compare the use of FVC and VC, assessed as the highest value of FVC or slow vital capacity (SVC), when assessing the FEV1/VC ratio in a general population setting. The second aim was to evaluate the characteristics of subjects with COPD who obtained a higher SVC than FVC. Methods: Subjects (n=1,050) aged 50-64 years were investigated with FEV1, FVC, and SVC after bronchodilation. Global Initiative for Chronic Obstructive Lung Disease (GOLD) COPDFVC was defined as FEV1/FVC <0.7, GOLDCOPD(VC) as FEV1/VC <0.7 using the maximum value of FVC or SVC, LLNCOPDFVC as FEV1/FVC below the LLN, and LLNCOPDVC as FEV1/VC below the LLN using the maximum value of FVC or SVC. Results: Prevalence of GOLDCOPD(FVC) was 10.0% (95% confidence interval [CI] 8.2-12.0) and the prevalence of LLNCOPDFVC was 9.5% (95% CI 7.8-11.4). When estimates were based on VC, the prevalence became higher; 16.4% (95% CI 14.3-18.9) and 15.6% (95% CI 13.5-17.9) for GOLDCOPD(VC) and LLNCOPDVC, respectively. The group of additional subjects classified as having COPD based on VC, had lower FEV1, more wheeze and higher residual volume compared to subjects without any COPD. Conclusion: The prevalence of COPD was significantly higher when the ratio FEV1/VC was calculated using the highest value of SVC or FVC compared with using FVC only. Subjects classified as having COPD when using the VC concept were more obstructive and with indications of air trapping. Hence, the use of only FVC when assessing airflow limitation may result in a considerable under diagnosis of subjects with mild COPD.
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| 39. |
- Wang, Tao, et al.
(författare)
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Influence of ammonium on formation of mineral-associated organic carbon by an ectomycorrhizal fungus
- 2019
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 85:10
-
Tidskriftsartikel (refereegranskat)abstract
- The interactions between dissolved organic matter (DOM) and mineral particles are critical for the stabilization of soil organic matter (SOM) in terrestrial ecosystems. The processing of DOM by ectomycorrhizal fungi contributes to the formation of mineral-stabilized SOM by two contrasting pathways: the extracellular transformation of DOM (ex vivo pathway) and the secretion of mineral-surface-reactive metabolites (in vivo pathway). In this study, we examined how changes in nitrogen (N) availability affected the formation of mineral-associated carbon (C) from these two pathways. DOM was extracted from forest soils. The processing of this DOM by the ectomycorrhizal fungus Paxillus involutus was examined in laboratory-scale studies with different levels of ammonium. At low levels of ammonium (i.e., under N-limited conditions), the DOM components were slightly oxidized, and fungal C metabolites with iron-reducing activity were secreted. Ammonium amendments decreased the amount of C metabolites, and no additional oxidation of the organic matter was detected. In contrast, the hydrolytic activity and the secretion of N-containing compounds increased, particularly when high levels of ammonium were added. Under these conditions, C, but not N, limited fungal growth. Although the overall production of mineral-associated organic C was not affected by ammonium concentrations, the observed shifts in the activities of the ex vivo and in vivo pathways affected the composition of organic matter adsorbed onto the mineral particles. Such changes will affect the properties of organic matter-mineral associations and, thus, ultimately, the stabilization of SOM.
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| 40. |
- Zhu, Baiwei, 1990-, et al.
(författare)
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A study of formation and growth of the anodised surface layer on Al-Si casting alloys based on different analytical techniques
- 2015
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Konferensbidrag (refereegranskat)abstract
- One of the major limitations in the application of anodizing of aluminum casting alloys is the non-uniform thickness of the oxide layer. Previous researches have studied the formation of the oxide film during anodizing in detail. These investigations have mainly been limited to aluminum and wrought aluminum alloys, and only a few papers have given some insights about the formation of the oxide layer on cast aluminum alloys. The majority of cast aluminum alloys contains relatively higher amounts of Si and other elements (e.g. Cu and Fe) than wrought alloys. This paper aims to investigate the mechanisms of formation and growth of the anodized surface layer on Al-Si casting alloys by applying different analytical techniques such as optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray computer tomography (X-ray CT) scanning. Three different Al alloys with various Si content (2.4%, 3.5% and 5.5%) were investigated. Si morphological modification by Sr addition, as well as gradient solidification was used to vary the microstructural coarseness in a controlled manner to study the influence of these parameters on the growth of the oxide layer. The microstructure features of the anodized layer and the interface between matrix and the oxide layer were studied, employing optical microscopy (figure 1), and SEM/EDS (figure 2). X-Ray CT-scanning (figure 3) was used to examine the high density phases (Fe and Cu bearing phases) and also to give a 3-D view of the anodized oxide surface. Furthermore, TEM was used to examine the general filming behavior of anodized layer and the local effects associated with Si particles in the matrix.It was found that: (i) during anodizing, the oxide front grew around the Si particles and tends to engulf them; (ii) the oxide front grew inwards but did expand in other directions in the eutectic areas; (iii) a scalloped interface between substrate and oxide indicated different anodizing rates in dendrites and eutectic phases. The oxide front was moving faster in the primary dendrite Al-phase than in the eutectic, and the growth rate was particularly slow in larger eutectic areas; (iv) different anodizing rates in dendrite and eutectic phases resulted in thinner layers in specimens with lower SDAS (secondary dendrite arm spacing); and (v) a more uniform layer thickness in Sr-modified specimens illustrates that oxide growth speed was faster in modified eutectic phase. However, diffusion of Si or long distance between Si particles after modification could even results in the adverse situation with a bad anodized surface appearance.
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| 41. |
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| 42. |
- Zhu, Baiwei, 1990-, et al.
(författare)
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A study of formation and growth of the anodised surface layer on cast Al-Si alloys based on different analytical techniques
- 2016
-
Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 101, s. 254-262
-
Tidskriftsartikel (refereegranskat)abstract
- This paper aims to investigate the mechanisms of formation and growth of the anodised surface layer on Al-Si castings by applying different analytical techniques such as optical microscopy, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and X-ray computer tomography (X-ray CT) scanning. Three different Al alloys with various Si content (2.43%, 3.53% and 5.45%) were investigated. Si particle morphological modification by Sr addition, as well as directional solidification, was used to vary the microstructural coarseness in a controlled manner to study the influence of these parameters on the growth behaviour of the oxide layer. This study observed residual unanodised Al phases trapped beneath or between Si particles in the oxide layer. It was found, depending on the geometry and morphology of Si particles, that Al can be shielded by Si particles and prevented from oxidising.
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| 43. |
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