| 1. |
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| 2. |
- Serge, M. A., et al.
(författare)
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Testing the Effect of Relative Pollen Productivity on the REVEALS Model : A Validated Reconstruction of Europe-Wide Holocene Vegetation
- 2023
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Ingår i: Land. - : MDPI. - 2073-445X. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- Reliable quantitative vegetation reconstructions for Europe during the Holocene are crucial to improving our understanding of landscape dynamics, making it possible to assess the past effects of environmental variables and land-use change on ecosystems and biodiversity, and mitigating their effects in the future. We present here the most spatially extensive and temporally continuous pollen-based reconstructions of plant cover in Europe (at a spatial resolution of 1 degrees x 1 degrees) over the Holocene (last 11.7 ka BP) using the 'Regional Estimates of VEgetation Abundance from Large Sites' (REVEALS) model. This study has three main aims. First, to present the most accurate and reliable generation of REVEALS reconstructions across Europe so far. This has been achieved by including a larger number of pollen records compared to former analyses, in particular from the Mediterranean area. Second, to discuss methodological issues in the quantification of past land cover by using alternative datasets of relative pollen productivities (RPPs), one of the key input parameters of REVEALS, to test model sensitivity. Finally, to validate our reconstructions with the global forest change dataset. The results suggest that the RPPs.st1 (31 taxa) dataset is best suited to producing regional vegetation cover estimates for Europe. These reconstructions offer a long-term perspective providing unique possibilities to explore spatial-temporal changes in past land cover and biodiversity.
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| 3. |
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| 4. |
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| 5. |
- van Rheenen, W, et al.
(författare)
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Common and rare variant association analyses in amyotrophic lateral sclerosis identify 15 risk loci with distinct genetic architectures and neuron-specific biology
- 2021
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Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 53:12, s. 1636-
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Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with a lifetime risk of one in 350 people and an unmet need for disease-modifying therapies. We conducted a cross-ancestry genome-wide association study (GWAS) including 29,612 patients with ALS and 122,656 controls, which identified 15 risk loci. When combined with 8,953 individuals with whole-genome sequencing (6,538 patients, 2,415 controls) and a large cortex-derived expression quantitative trait locus (eQTL) dataset (MetaBrain), analyses revealed locus-specific genetic architectures in which we prioritized genes either through rare variants, short tandem repeats or regulatory effects. ALS-associated risk loci were shared with multiple traits within the neurodegenerative spectrum but with distinct enrichment patterns across brain regions and cell types. Of the environmental and lifestyle risk factors obtained from the literature, Mendelian randomization analyses indicated a causal role for high cholesterol levels. The combination of all ALS-associated signals reveals a role for perturbations in vesicle-mediated transport and autophagy and provides evidence for cell-autonomous disease initiation in glutamatergic neurons.
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| 6. |
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| 7. |
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| 8. |
- van Dongen, J, et al.
(författare)
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DNA methylation signatures of aggression and closely related constructs: A meta-analysis of epigenome-wide studies across the lifespan
- 2021
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Ingår i: Molecular psychiatry. - : Springer Science and Business Media LLC. - 1476-5578 .- 1359-4184. ; 26:6, s. 2148-2162
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Tidskriftsartikel (refereegranskat)abstract
- DNA methylation profiles of aggressive behavior may capture lifetime cumulative effects of genetic, stochastic, and environmental influences associated with aggression. Here, we report the first large meta-analysis of epigenome-wide association studies (EWAS) of aggressive behavior (N = 15,324 participants). In peripheral blood samples of 14,434 participants from 18 cohorts with mean ages ranging from 7 to 68 years, 13 methylation sites were significantly associated with aggression (alpha = 1.2 × 10−7; Bonferroni correction). In cord blood samples of 2425 children from five cohorts with aggression assessed at mean ages ranging from 4 to 7 years, 83% of these sites showed the same direction of association with childhood aggression (r = 0.74, p = 0.006) but no epigenome-wide significant sites were found. Top-sites (48 at a false discovery rate of 5% in the peripheral blood meta-analysis or in a combined meta-analysis of peripheral blood and cord blood) have been associated with chemical exposures, smoking, cognition, metabolic traits, and genetic variation (mQTLs). Three genes whose expression levels were associated with top-sites were previously linked to schizophrenia and general risk tolerance. At six CpGs, DNA methylation variation in blood mirrors variation in the brain. On average 44% (range = 3–82%) of the aggression–methylation association was explained by current and former smoking and BMI. These findings point at loci that are sensitive to chemical exposures with potential implications for neuronal functions. We hope these results to be a starting point for studies leading to applications as peripheral biomarkers and to reveal causal relationships with aggression and related traits.
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| 9. |
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| 10. |
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| 11. |
- Hannon, Stephen, et al.
(författare)
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H α morphologies of star clusters : a LEGUS study of H II region evolution time-scales and stochasticity in low-mass clusters
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 490:4, s. 4648-4665
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Tidskriftsartikel (refereegranskat)abstract
- The morphology of H II regions around young star clusters provides insight into the time-scales and physical processes that clear a cluster's natal gas. We study similar to 700 young clusters (<= 10 Myr) in three nearby spiral galaxies (NGC 7793, NGC 4395, and NGC 1313) using Hubble Space Telescope (HST) imaging from LEGUS (Legacy ExtraGalactic Ultraviolet Survey). Clusters are classified by their H alpha morphology (concentrated, partially exposed, no-emission) and whether they have neighbouring clusters (which could affect the clearing time-scales). Through visual inspection of the HST images, and analysis of ages, reddenings, and stellar masses from spectral energy distributions fitting, together with the (U - B), (V - I) colours, we find (1) the median ages indicate a progression from concentrated (similar to 3Myr), to partially exposed (similar to 4Myr), to no H alpha emission (>5Myr), consistent with the expected temporal evolution of H II regions and previous results. However, (2) similarities in the age distributions for clusters with concentrated and partially exposed H alpha morphologies imply a short time-scale for gas clearing (less than or similar to 1 Myr). Also, (3) our cluster sample's median mass is similar to 1000 M-circle dot, and a significant fraction (similar to 20 per cent) contain one or more bright red sources (presumably supergiants), which can mimic reddening effects. Finally, (4) the median E(B - V) values for clusters with concentrated H alpha and those without H alpha emission appear to be more similar than expected (similar to 0.18 versus similar to 0.14, respectively), but when accounting for stochastic effects, clusters without H alpha emission are less reddened. To mitigate stochastic effects, we experiment with synthesizing more massive clusters by stacking fluxes of clusters within each H alpha morphological class. Composite isolated clusters also reveal a colour and age progression for H alpha morphological classes, consistent with analysis of the individual clusters.
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| 12. |
- Hop, Paul J., et al.
(författare)
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Genome-wide study of DNA methylation shows alterations in metabolic, inflammatory, and cholesterol pathways in ALS
- 2022
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Ingår i: Science Translational Medicine. - : American Association for the Advancement of Science. - 1946-6234 .- 1946-6242. ; 14:633
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Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with an estimated heritability between 40 and 50%. DNA methylation patterns can serve as proxies of (past) exposures and disease progression, as well as providing a potential mechanism that mediates genetic or environmental risk. Here, we present a blood-based epigenome-wide association study meta-analysis in 9706 samples passing stringent quality control (6763 patients, 2943 controls). We identified a total of 45 differentially methylated positions (DMPs) annotated to 42 genes, which are enriched for pathways and traits related to metabolism, cholesterol biosynthesis, and immunity. We then tested 39 DNA methylation-based proxies of putative ALS risk factors and found that high-density lipoprotein cholesterol, body mass index, white blood cell proportions, and alcohol intake were independently associated with ALS. Integration of these results with our latest genome-wide association study showed that cholesterol biosynthesis was potentially causally related to ALS. Last, DNA methylation at several DMPs and blood cell proportion estimates derived from DNA methylation data were associated with survival rate in patients, suggesting that they might represent indicators of underlying disease processes potentially amenable to therapeutic interventions.
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| 13. |
- Albert, F. W., et al.
(författare)
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Targeted resequencing of a genomic region influencing tameness and aggression reveals multiple signals of positive selection
- 2011
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 107:3, s. 205-214
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Tidskriftsartikel (refereegranskat)abstract
- The identification of the causative genetic variants in quantitative trait loci (QTL) influencing phenotypic traits is challenging, especially in crosses between outbred strains. We have previously identified several QTL influencing tameness and aggression in a cross between two lines of wild-derived, outbred rats (Rattus norvegicus) selected for their behavior towards humans. Here, we use targeted sequence capture and massively parallel sequencing of all genes in the strongest QTL in the founder animals of the cross. We identify many novel sequence variants, several of which are potentially functionally relevant. The QTL contains several regions where either the tame or the aggressive founders contain no sequence variation, and two regions where alternative haplotypes are fixed between the founders. A re-analysis of the QTL signal showed that the causative site is likely to be fixed among the tame founder animals, but that several causative alleles may segregate among the aggressive founder animals. Using a formal test for the detection of positive selection, we find 10 putative positively selected regions, some of which are close to genes known to influence behavior. Together, these results show that the QTL is probably not caused by a single selected site, but may instead represent the joint effects of several sites that were targets of polygenic selection.
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| 14. |
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| 15. |
- Halme, P., et al.
(författare)
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Challenges of ecological restoration : Lessons from forests in northern Europe
- 2013
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 167, s. 248-256
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Forskningsöversikt (refereegranskat)abstract
- The alarming rate of ecosystem degradation has raised the need for ecological restoration throughout different biomes and continents. North European forests may appear as one of the least vulnerable ecosystems from a global perspective, since forest cover is not rapidly decreasing and many ecosystem services remain at high level. However, extensive areas of northern forests are heavily exploited and have lost a major part of their biodiversity value. There is a strong requirement to restore these areas towards a more natural condition in order to meet the targets of the Convention on Biological Diversity. Several northern countries are now taking up this challenge by restoring forest biodiversity with increasing intensity. The ecology and biodiversity of boreal forests are relatively well understood making them a good model for restoration activities in many other forest ecosystems. Here we introduce northern forests as an ecosystem, discuss the historical and recent human impact and provide a brief status report on the ecological restoration projects and research already conducted there. Based on this discussion, we argue that before any restoration actions commence, the ecology of the target ecosystem should be established with the need for restoration carefully assessed and the outcome properly monitored. Finally, we identify the most important challenges that need to be solved in order to carry out efficient restoration with powerful and long-term positive impacts on biodiversity: coping with unpredictability, maintaining connectivity in time and space, assessment of functionality, management of conflicting interests and social restrictions and ensuring adequate funding. © 2013 Elsevier Ltd.
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| 16. |
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| 17. |
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| 18. |
- Hannon, G E, et al.
(författare)
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Climate change and human settlement as drivers of late-Holocene vegetational change in the Faroe Islands
- 2005
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 15:5, s. 639-647
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Tidskriftsartikel (refereegranskat)abstract
- Changes in Faroese land surfaces during the late Holocene reflect intimate interactions between cultural and environmental development. Analyses of fossil wood, pollen and plant macrofossils indicate that the present open landscape replaced shrubby vegetation that was present from c. 6000 BC Up to c. AD 660. Conditions altered during the late Holocene, with loss of woody vegetation and increasing erosion: trends that were initiated prior to human settlement. AMS dating of sub-fossil Betula, Salix and Juniperus found buried in peat profiles from the islands of Suouroy, Sandoy, Eysturoy, Vagar and Streymoy, revealed that the islands had at least partial woody vegetation cover up to the time of continuous settlement. The settlement horizon, identified in a lacustrine sequence on the island of Eysturoy, dated to c. AD 570. It comprised pollen evidence for the cultivation of Hordeum, cultural macrofossil assemblages, charcoal fragments, diatom assemblage changes indicating lake nutrient enrichment and physical measurements showing increased sedimentation rates. The pollen record showed that heathland development was initiated prior to anthropogenic impact. The ecosystem impacts of settlement were therefore superimposed on landscape changes that began around AD 250. The earlier changes were most likely forced by increased storminess and declining atmospheric temperatures.
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| 19. |
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| 20. |
- Wofford, Aida, et al.
(författare)
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Candidate LBV stars in galaxy NGC 7793 found via HST photometry plus MUSE spectroscopy
- 2020
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 493:2, s. 2410-2428
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Tidskriftsartikel (refereegranskat)abstract
- Only about 19 Galactic and 25 extragalactic bonafide luminous blue variables (LBVs) are known to date. This incomplete census prevents our understanding of this crucial phase of massive star evolution which leads to the formation of heavy binary black holes via the classical channel. With large samples of LBVs one could better determine the duration and maximum stellar luminosity which characterize this phase. We search for candidate LBVs (cLBVs) in a new galaxy, NGC 7793. For this purpose, we combine high spatial resolution images from two Hubble Space Telescope (HST) programs with optical spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE). By combining PSF-fitting photometry measured on F547M, F657N, and F814W images, with restrictions on point-like appearance (at HST resolution) and Ha luminosity, we find 100 potential cLBVs, 36 of which fall in the MUSE fields. Five of the latter 36 sources are promising cLBVs which have M-V <= -7 and a combination of: H alpha with a P-Cygni profile; no [O I]lambda 6300 emission; weak or no [O III]lambda 5007 emission; large [N II]/H alpha relative to HII regions; and [S II]lambda 6716/[S II]lambda 6731 similar to 1. It is not clear if these five cLBVs are isolated from O-type stars, which would favour the binary formation scenario of LBVs. Our study, which approximately covers one fourth of the optical disc of NGC 7793, demonstrates how by combining the above HST surveys with multi-object spectroscopy from 8-m class telescopes, one can efficiently find large samples of cLBVs in nearby galaxies.
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| 21. |
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| 22. |
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| 23. |
- Chang, Dan, et al.
(författare)
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The evolutionary and phylogeographic history of woolly mammoths : a comprehensive mitogenomic analysis
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Near the end of the Pleistocene epoch, populations of the woolly mammoth (Mammuthus primigenius) were distributed across parts of three continents, from western Europe and northern Asia through Beringia to the Atlantic seaboard of North America. Nonetheless, questions about the connectivity and temporal continuity of mammoth populations and species remain unanswered. We use a combination of targeted enrichment and high-throughput sequencing to assemble and interpret a data set of 143 mammoth mitochondrial genomes, sampled from fossils recovered from across their Holarctic range. Our dataset includes 54 previously unpublished mitochondrial genomes and significantly increases the coverage of the Eurasian range of the species. The resulting global phylogeny confirms that the Late Pleistocene mammoth population comprised three distinct mitochondrial lineages that began to diverge ~1.0–2.0 million years ago (Ma). We also find that mammoth mitochondrial lineages were strongly geographically partitioned throughout the Pleistocene. In combination, our genetic results and the pattern of morphological variation in time and space suggest that male-mediated gene flow, rather than large-scale dispersals, was important in the Pleistocene evolutionary history of mammoths.
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| 24. |
- Choi, Y., et al.
(författare)
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Coordinated Regulation Among Progesterone, Prostaglandins, and EGF-Like Factors in Human Ovulatory Follicles
- 2017
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Ingår i: Journal of Clinical Endocrinology & Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 102:6, s. 1971-1982
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Tidskriftsartikel (refereegranskat)abstract
- Context: In animal models, the luteinizing hormone surge increases progesterone (P4) and progesterone receptor (PGR), prostaglandins (PTGs), and epidermal growth factor (EGF)-like factors that play essential roles in ovulation. However, little is known about the expression, regulation, and function of these key ovulatory mediators in humans. Objective: To determine when and how these key ovulatory mediators are induced after the luteinizing hormone surge in human ovaries. Design and Participants: Timed periovulatory follicles were obtained from cycling women. Granulosa/lutein cells were collected from in vitro fertilization patients. Main Outcome Measures: The in vivo and in vitro expression of PGR, PTG synthases and transporters, and EGF-like factors were examined at the level of messenger RNA and protein. PGR binding to specific genes was assessed. P4 and PTGs in conditioned media were measured. Results: PGR, PTGS2, and AREG expressions dramatically increased in ovulatory follicles at 12 to 18 hours after human chorionic gonadotropin (hCG). In human granulosa/lutein cell cultures, hCG increased P4 and PTG production and the expression of PGR, specific PTG synthases and transporters, and EGF-like factors, mimicking in vivo expression patterns. Inhibitors for P4/PGR and EGF-signaling pathways reduced hCG-induced increases in PTG production and the expression of EGF-like factors. PGR bound to the PTGS2, PTGES, and SLCO2A1 genes. Conclusions: This report demonstrated the time-dependent induction of PGR, AREG, and PTGS2 in human periovulatory follicles. In vitro studies indicated that collaborative actions of P4/PGR and EGF signaling are required for hCG-induced increases in PTG production and potentiation of EGF signaling in human periovulatory granulosa cells.
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| 25. |
- Hannon, Eilis, et al.
(författare)
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DNA methylation meta-analysis reveals cellular alterations in psychosis and markers of treatment-resistant schizophrenia
- 2021
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Ingår i: eLIFE. - : eLife Sciences Publications. - 2050-084X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- We performed a systematic analysis of blood DNA methylation profiles from 4483 participants from seven independent cohorts identifying differentially methylated positions (DMPs) associated with psychosis, schizophrenia, and treatment-resistant schizophrenia. Psychosis cases were characterized by significant differences in measures of blood cell proportions and elevated smoking exposure derived from the DNA methylation data, with the largest differences seen in treatment-resistant schizophrenia patients. We implemented a stringent pipeline to meta-analyze epigenome-wide association study (EWAS) results across datasets, identifying 95 DMPs associated with psychosis and 1048 DMPs associated with schizophrenia, with evidence of colocalization to regions nominated by genetic association studies of disease. Many schizophrenia-associated DNA methylation differences were only present in patients with treatment-resistant schizophrenia, potentially reflecting exposure to the atypical antipsychotic clozapine. Our results highlight how DNA methylation data can be leveraged to identify physiological (e.g., differential cell counts) and environmental (e.g., smoking) factors associated with psychosis and molecular biomarkers of treatment-resistant schizophrenia.
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| 26. |
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| 27. |
- Hannon, Gina E
(författare)
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Bokskogens historia och dynamik i Biskopstorp och Dömestorp: resultat från makrofossilstudier
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Paleoekologiska analyser har dokumenterat skogshistorien från två områden med gammal bokskog och höga nutida biologiska värden. I Biskopstorp, Halmstads kommun, sträcker sig fynden av växtmakrofossil tillbaka tills 1010 f.Kr. Skogen var då en blandad skog dominerad av lind, ek, hassel och tall. Fynd av kolpartiklar visar att brand var en del av störningsregimen och funna växtmakrofossil av markfloran pekar på att skogen var delvis öppen i struktur. Tall och ek tolererar brand bättre än många andra trädarter och hassel skjuter stubbskott efter brand. Bokpollen noterades först vid 300 e.Kr. men förekom med högre frekvens vid 1150 e.Kr. (Björkman, 2000). Fynden av makrofossil visar att när brandregimen upphörde, expanderade bok. Detta visar på en tydlig koppling mellan störning i landskap och denna trädtyp. Det visar också bokens känslighet för brand. Bok var det dominerade trädslaget över flera sekler och ersatte slutligen lind och ek. Det sista fyndet av tall förekommer ca 1375 e.Kr. Liknande fynd har gjorts på Killeröd löväng, (1150 e.Kr.) Bjärehalvön (Hannon och Hernborg, opublicerat) och Suserup Skov i Danmark (900 e.Kr.) (Hannon et al, 2000).I Dömestorp, Laholms kommun, sträcker sig de paleoekologiska fynden tillbaka till 500 f.Kr. Störningar i landskapet i form av brand påverkade skogen så att den blev delvis öppen med en rik markflora. Bok etablerade sig på undersökningslokalen ca 300 e.Kr., efter ett lager som innehåller många stora trädgrenar och kvistar som identiferas bl.a. som ask, ek och lind. Detta visar än en gång på lokal etablering av bok efter störningar.I såväl Biskopstorp som i Dömestorp minskade boken drastiskt under 1700- och 1800- talet när det var störst press på skogen delvis p.g.a. den kalla period som kallades Lilla Istiden. På undersökningslokalen i Biskopstorp hittar man då fortfarande makrorester av bok, men på de undersökta lokalerna i Dömestorp försvann bok under denna tid. Även om bok minskade eller försvann tillfälligt, fanns trädkontinuiteten kvar, fast med andra trädslag som al och björk. Denna skogliga kontinuitet över flera tusen år, fast med olika trädslagskomposition, kan vara en orsak till att de två områdena har så höga naturvården idag.
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| 28. |
- Hannon, Gina E., et al.
(författare)
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Dynamic early Holocene vegetation development on the Faroe Islands inferred from high-resolution plant macrofossil and pollen data
- 2010
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Ingår i: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 73:2, s. 163-172
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Tidskriftsartikel (refereegranskat)abstract
- Vegetation dynamics during the earliest part of the Holocene (11,250-10,250 cal yr BP) have been reconstructed from a lacustrine sequence on Sandoy, the Faroe Islands, using detailed plant macrofossil and pollen evidence. The plant macrofossils suggest the initial vegetation was sparse herb and shrub tundra, with Salix herbacea and open-ground species, followed by the development of a denser and more species-rich arctic heathland after 11,150 cal yr BP. Despite high pollen values for Betula nana, macrofossils are rare. The bulk of the macrofossils recorded are S. herbacea and Empetrum leaves with numerous herb taxa and an abundance of Racomitrium moss. Conditions start to change around 10,800 cal yr BP, with increased catchment erosion and sediment delivery to the lake from ca. 10,600 cal yr BP, and a transition to alternating Cyperaceae and Poaceae communities between ca. 10,450 and 10,250 cal yr BP. This vegetation change, which has been recorded throughout the Faroes, has previously been interpreted as a retrogressive shift from woody shrubs to a herbaceous community. The detailed plant macrofossil data show the shift is the replacement of an Empetrum arctic heathland by grassland and moist sedge communities. These taxa dominate the modern landscape. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.
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| 29. |
- Hannon, Gina E., et al.
(författare)
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Factors influencing late-Holocene vegetation dynamics and biodiversity on Hallands Väderö, SW Sweden : A statistical evaluation
- 2022
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Ingår i: Holocene. - : SAGE Publications. - 0959-6836. ; 32:11, s. 1317-1326
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Tidskriftsartikel (refereegranskat)abstract
- Forest composition characteristic of the Mid-Holocene has survived on Hallands Väderö, an island nature reserve off the south west coast of Sweden. Current veteran Tilia and Quercus trees contribute to a remarkably rich biodiversity of fungi, bryophytes, lichens and insects. Understanding which potential factors influence Holocene vegetation dynamics can support efforts to protect biodiversity, but the role of grazing and browsing has previously been difficult to evaluate because of the lack of long-term datasets. Palaeoecological analyses over the last c. 3000 years from a pond on the island reveal sustained presence of Quercus, Alnus, Tilia, Corylus and Ulmus, alongside increasing Fagus in recent centuries. Changes in grazing pressure have been documented since AD 1665 and a statistical approach was used to calculate the relative importance of grazing pressure, climate variability, and fire activity on the dynamics of selected taxa. Grazing was the main factor reducing population size of Fagus, Alnus, Tilia and Corylus on the island over the period AD 1665–1858, with warm winter temperatures and summer humidity having significant positive influences in the last millennium for Quercus, Alnus, Tilia and Corylus. The survival of large numbers of red-listed species is likely to be due to the continuity of large old trees, ancient forest composition and a distinctive disturbance history in a favourable climate.
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| 30. |
- Hannon, Gina E, et al.
(författare)
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The Bronze Age landscape of the Bjare peninsula, southern Sweden, and its relationship to burial mounds
- 2008
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Ingår i: Journal of Archaeological Science. - : Elsevier BV. - 1095-9238 .- 0305-4403. ; 35:3, s. 623-632
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Tidskriftsartikel (refereegranskat)abstract
- Palaeoecological analyses from a small fen deposit, combined with pollen analysis from buried soil profiles under prehistoric burial mounds, have been used to investigate the timing and vegetation change associated with the Holocene development of a cultural landscape in southern Sweden. Traditional pollen analysis is complemented with plant macrofossil analysis and soil pollen analysis from within and in close proximity to the burial mounds in the coastal Bjare peninsula, well known for its high density of well-preserved Bronze Age monuments. The vegetation development is linked to the construction of the burial mounds. A marked increase of cultural impact on the landscape is recorded during the Neolithic-Bronze Age transition and estimates of landscape openness suggest that by the onset of the Bronze Age, forest cover was only 20-40%, falling to 10% in the immediate vicinity of the burial mounds themselves. The coastal strip appears to have been affected by human activity to a greater extent and at an earlier date than sites from further inland in southern Sweden and the Bronze Age burial mounds were most likely designed to be visible in a largely deforested landscape.
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| 31. |
- Hannon, Gina E., et al.
(författare)
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The reconstruction of past forest dynamics over the last 13,500 years in SW Sweden
- 2018
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 28:11, s. 1791-1800
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Tidskriftsartikel (refereegranskat)abstract
- Evidence for unbroken continuity of tree taxa over the last c. 13,500 years is presented from a biodiversity ‘hotspot’ nature reserve in south-west Sweden.Forest composition, continuity, fire and disturbance events are reconstructed using palaeoecological methods. A lake record reveals that Pinus sylvestris,Betula spp., Salix spp., Populus tremula and Hippophae rhamnoides were the initial trees scattered in a semi-open, steppe environment. This developedinto forest with Pinus, Betula, Corylus, Alnus, Ulmus and Populus with evidence for frequent fires. Deciduous trees became more significant as fires becameless frequent and Quercus, Fraxinus and Tilia expanded. Fire frequencies increased again in the Bronze Age probably associated with anthropogenic useof the forest, and the first Fagus sylvatica pollen was recorded. Burning continued through the Iron Age, but charcoal is briefly absent for a period oftenreferred to as the ‘Late Iron Age Lull’. The forest re-expanded with successions involving Juniperus, but with an altered composition from the earlier mixeddeciduous community, to one dominated by Fagus. This is coincident with the first pollen records for Picea abies. The early Holocene mixed forest withfrequent low-intensity fires is potentially associated with the greatest diversity of red-listed insect species. Forest continuity and the fragmented reservoirpopulations of old deciduous trees in the Fagus-dominated forest today are likely to have been critical in preserving the present-day, species-rich, rareepiphytic flora, wood-inhabiting fungi and invertebrate communities. As many of these forest fragments may become more vulnerable with future climatechange, tree diversity with some disturbance may become essential for survival of the endangered saproxylic species.
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| 32. |
- Hannon, Gina E., et al.
(författare)
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Vegetation dynamics and Fire History in Färnebofjärden National Park, Central Sweden
- 2021
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 31:1, s. 28-37
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Tidskriftsartikel (refereegranskat)abstract
- Palaeoecological studies can identify past trends in vegetation communities and processes over long time scales. Pollen, plant macrofossils and charcoalanalyses are used to reconstruct vegetation over the last 6400 years and provide information about former human impact and disturbance regimesin Färnebofjärden National Park, Central Sweden. Three specific conservation planning topics were addressed: (1) the changing ratio of conifers tobroadleaved trees; (2) the origin and history of the river meadows and the biodiverse Populus tremula meadows; (3) the role of fire in the maintenanceof biological values. Early diverse mixed broadleaved forest assemblages with pine were followed by significant declines of the more thermophilic forestelements prior to the expansion of spruce in the Iron Age. The rise to dominance of spruce was a ‘natural’ process that has been exaggerated byanthropogenic disturbance to artificially high levels today. The initial river meadow communities were facilitated by fire and frequent flooding events, butsubsequent dynamics have more definitely been supported by human activities. Rural abandonment during the last 100 years has led to woody successions.Fire has been a continual disturbance factor with an influence on conservation issues such as Picea abies dominance and the maintenance of diverse, nonforestcommunities. Present occurrence of fire is unusually low, but natural fire frequencies are increasing in the region.
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| 33. |
- Hannon, P. R., et al.
(författare)
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Ovulatory Induction of SCG2 in Human, Nonhuman Primate, and Rodent Granulosa Cells Stimulates Ovarian Angiogenesis
- 2018
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 159:6, s. 2447-2458
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Tidskriftsartikel (refereegranskat)abstract
- The luteinizing hormone (LH) surge is essential for ovulation, but the intrafollicular factors induced by LH that mediate ovulatory processes (e.g., angiogenesis) are poorly understood, especially in women. The role of secretogranin II (SCG2) and its cleaved bioactive peptide, secretoneurin (SN), were investigated as potential mediators of ovulation by testing the hypothesis that SCG2/SN is induced in granulosa cells by human chorionic gonadotropin (hCG), via a downstream LH receptor signaling mechanism, and stimulates ovarian angiogenesis. Humans, nonhuman primates, and rodents were treated with hCG in vivo resulting in a significant increase in the messenger RNA and protein levels of SCG2 in granulosa cells collected early during the periovulatory period and just prior to ovulation (humans: 12 to 34 hours; monkeys: 12 to 36 hours; rodents: 4 to 12 hours post-hCG). This induction by hCG was recapitulated in an in vitro culture system utilizing granulosa-lutein cells from in vitro fertilization patients. Using this system, inhibition of downstream LH receptor signaling pathways revealed that the initial induction of SCG2 is regulated, in part, by epidermal growth factor receptor signaling. Further, human ovarian microvascular endothelial cells were treated with SN (1 to 100 ng/mL) and subjected to angiogenesis assays. SN significantly increased endothelial cell migration and new sprout formation, suggesting induction of ovarian angiogenesis. These results establish that SCG2 is increased in granulosa cells across species during the periovulatory period and that SN may mediate ovulatory angiogenesis in the human ovary. These findings provide insight into the regulation of human ovulation and fertility.
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| 34. |
- Hannon, Stephen, et al.
(författare)
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Star cluster classification using deep transfer learning with PHANGS-HST
- 2023
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Ingår i: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 526:2, s. 2991-3006
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Tidskriftsartikel (refereegranskat)abstract
- Currently available star cluster catalogues from the Hubble Space Telescope (HST) imaging of nearby galaxies heavily rely on visual inspection and classification of candidate clusters. The time-consuming nature of this process has limited the production of reliable catalogues and thus also post-observation analysis. To address this problem, deep transfer learning has recently been used to create neural network models that accurately classify star cluster morphologies at production scale for nearby spiral galaxies (D ≲ 20 Mpc). Here, we use HST ultraviolet (UV)–optical imaging of over 20 000 sources in 23 galaxies from the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) survey to train and evaluate two new sets of models: (i) distance-dependent models, based on cluster candidates binned by galaxy distance (9–12, 14–18, and 18–24 Mpc), and (ii) distance-independent models, based on the combined sample of candidates from all galaxies. We find that the overall accuracy of both sets of models is comparable to previous automated star cluster classification studies (∼60–80 per cent) and shows improvement by a factor of 2 in classifying asymmetric and multipeaked clusters from PHANGS-HST. Somewhat surprisingly, while we observe a weak negative correlation between model accuracy and galactic distance, we find that training separate models for the three distance bins does not significantly improve classification accuracy. We also evaluate model accuracy as a function of cluster properties such as brightness, colour, and spectral energy distribution (SED)-fit age. Based on the success of these experiments, our models will provide classifications for the full set of PHANGS-HST candidate clusters (N ∼ 200 000) for public release.
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| 35. |
- Kersten, CM, et al.
(författare)
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The Management of Asymptomatic Congenital Pulmonary Airway Malformation: Results of a European Delphi Survey
- 2022
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Ingår i: Children (Basel, Switzerland). - : MDPI AG. - 2227-9067. ; 9:8
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Tidskriftsartikel (refereegranskat)abstract
- Consensus on the optimal management of asymptomatic congenital pulmonary airway malformation (CPAM) is lacking, and comparison between studies remains difficult due to a large variety in outcome measures. We aimed to define a core outcome set (COS) for pediatric patients with an asymptomatic CPAM. An online, three-round Delphi survey was conducted in two stakeholder groups of specialized caregivers (surgeons and non-surgeons) in various European centers. Proposed outcome parameters were scored according to level of importance, and the final COS was established through consensus. A total of 55 participants (33 surgeons, 22 non-surgeons) from 28 centers in 13 European countries completed the three rounds and rated 43 outcome parameters. The final COS comprises seven outcome parameters: respiratory insufficiency, surgical complications, mass effect/mediastinal shift (at three time-points) and multifocal disease (at two time-points). The seven outcome parameters included in the final COS reflect the diversity in priorities among this large group of European participants. However, we recommend the incorporation of these outcome parameters in the design of future studies, as they describe measurable and validated outcomes as well as the accepted age at measurement.
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| 36. |
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| 37. |
- Molinari, Chiara, et al.
(författare)
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Fire-vegetation interactions during the last 11,000 years in boreal and cold temperate forests of Fennoscandia
- 2020
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 241
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Tidskriftsartikel (refereegranskat)abstract
- The long-term ecological interactions between fire and the composition of dominant trees and shrubs in boreal and cold temperate Fennoscandian forests are still under discussion. We hypothesized that fire-prone taxa should abound during periods and regions characterized by higher fire disturbance, while fire-intolerant taxa should dominate when and where fire activity is low. Biomass burning (BB) is here investigated based on 69 sedimentary charcoal records. For the same sites, the relative contribution of pollen-based reconstructions of dominant vegetation cover divided into three different fire-sensitivity classes is explored by means of a statistical approach. The overall patterns found across Fennoscandia suggest that Ericaceae (mainly Calluna), Pinus, Betula and Populus are strongly positively correlated with multi-millennial variability of BB in both boreal and cold temperate forests, confirming their fire-prone character (taxa adapted/favoured by burning). Positive but much weaker (and not always significant) relationships also exist between long-term trends in BB and Fagus, Quercus, Corylus, Alnus, Juniperus, Carpinus and Salix, fire-tolerant taxa that survive low/moderate intense fires because of specific functional traits or their rapid, enhanced regeneration after fire. A strong negative significant correlation is instead detected between BB and Picea, Ulmus Tilia, Fraxinus, which are fire-intolerant taxa and can locally disappear for a short time after a fire. This large-scale analysis supports our initial hypothesis that tree and shrub dominance was closely linked to biomass burning since the onset of the Holocene in the study regions. Fire was an important ecosystem disturbance in Fennoscandia influencing long-term vegetation dynamics and composition over the last 11,000 years, although human activities probably altered the strength of fire-vegetation interactions during more recent millennia.
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| 38. |
- Overballe-Petersen, Mette Venas, et al.
(författare)
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Long-term forest dynamics at Gribskov, eastern Denmark with early-Holocene evidence for thermophilous broadleaved tree species
- 2013
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 23:2, s. 243-254
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Tidskriftsartikel (refereegranskat)abstract
- We report on a full-Holocene pollen, charcoal and macrofossil record from a small forest hollow in Gribskov, eastern Denmark. The Fagus sylvatica pollen record suggests the establishment of a small Fagus population at Gribskov in the early Holocene together with early establishment of other thermophilous broadleaved trees, including Quercus sp., Tilia sp. and Ulmus sp. The macrofossils contribute to the vegetation reconstruction with evidence for local presence of species with low pollen productivity or easily degraded pollen types such as Populus. The charcoal record shows frequent burning during two periods of the early Holocene and from c. 3000 cal. BP to present. The early-Holocene part of the record indicates a highly disturbed forest ecosystem with frequent fires and abundant macrofossils of particularly Betula sp. and Populus sp. The sediment stratigraphy and age-depth relationships give no clear indication of post-depositional disturbance, although a possible short-lived hiatus occurs around 6500 cal. BP. The early pollen record from thermophilous trees could indicate that there may have been some downwash following sediment desiccation through wood peat layers deposited between c. 6500 and 10,000 cal. BP, but the overall biostratigraphy is consistent with other Danish small hollow records.
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| 39. |
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| 40. |
- Schinnerer, Eva, et al.
(författare)
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PHANGS-JWST First Results : Rapid Evolution of Star Formation in the Central Molecular Gas Ring of NGC 1365
- 2023
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 944:2
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale bars can fuel galaxy centers with molecular gas, often leading to the development of dense ringlike structures where intense star formation occurs, forming a very different environment compared to galactic disks. We pair ∼0.″3 (30 pc) resolution new JWST/MIRI imaging with archival ALMA CO(2-1) mapping of the central ∼5 kpc of the nearby barred spiral galaxy NGC 1365 to investigate the physical mechanisms responsible for this extreme star formation. The molecular gas morphology is resolved into two well-known bright bar lanes that surround a smooth dynamically cold gas disk (R gal ∼ 475 pc) reminiscent of non-star-forming disks in early-type galaxies and likely fed by gas inflow triggered by stellar feedback in the lanes. The lanes host a large number of JWST-identified massive young star clusters. We find some evidence for temporal star formation evolution along the ring. The complex kinematics in the gas lanes reveal strong streaming motions and may be consistent with convergence of gas streamlines expected there. Indeed, the extreme line widths are found to be the result of inter-“cloud” motion between gas peaks; ScousePy decomposition reveals multiple components with line widths of 〈σ CO,scouse〉 ≈ 19 km s−1 and surface densities of 〈 Σ H 2 , scouse 〉 ≈ 800 M ⊙ pc − 2 , similar to the properties observed throughout the rest of the central molecular gas structure. Tailored hydrodynamical simulations exhibit many of the observed properties and imply that the observed structures are transient and highly time-variable. From our study of NGC 1365, we conclude that it is predominantly the high gas inflow triggered by the bar that is setting the star formation in its CMZ.
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| 41. |
- Wastegård, Stefan, et al.
(författare)
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Towards a Holocene tephrochronology for the Faroe Islands, North Atlantic
- 2018
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 195, s. 195-214
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Tidskriftsartikel (refereegranskat)abstract
- The Faroe Islands hold a key position in the North Atlantic region for tephra studies due to their relative proximity to Iceland. Several tephras have been described over the last 50 years in peat and lake sediment sequences, including the type sites for the Saksunarvatn and Mjauvotn tephras. Here we present a comprehensive overview of Holocene tephras found on the Faroe Island. In total 23 tephra layers are described including visible macrotephras such as the Saksunarvatn and Hekla 4 tephras and several cryptotephras. The importance of tephras originally described from the Faroe Islands is highlighted and previously unpublished results are included. In addition, full datasets for several sites are published here for the first time. The Saksunarvatn Ash, now considered to be the result of several eruptions rather than one major eruption, can be separated into two phases on the Faroe Islands; one early phase with two precursor eruptions with lower MgO concentrations (4.5-5.0 wt%) than the main eruption and a later phase with higher MgO concentrations (5.5-6.0 wt%), including the visible Saksunarvatn Ash. The Tjornuvik Tephra, previously considered to be a primary deposit, is now interpreted as a reworked tephra with material from at least two middle Holocene eruptions of Hekla. Several of the tephras identified on the Faroe Islands provide useful isochrons for climate events during the Holocene.
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