| 1. |
- Hampton, Stephanie E., et al.
(författare)
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Ecology under lake ice
- 2017
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 20:1, s. 98-111
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Forskningsöversikt (refereegranskat)abstract
- Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer ‘growing seasons’. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.
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| 2. |
- Johansson, Elias, et al.
(författare)
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Recurrent stroke in symptomatic carotid stenosis awaiting revascularization : A pooled analysis
- 2016
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Ingår i: Neurology. - : Wolters Kluwer. - 0028-3878 .- 1526-632X. ; 86:6, s. 498-504
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Tidskriftsartikel (refereegranskat)abstract
- Objective: We aimed to quantify the risk and predictors of ipsilateral ischemic stroke in patients with symptomatic carotid stenosis awaiting revascularization (carotid endarterectomy [CEA] or carotid artery stenting) by pooling individual patient data from recent prospective studies with high rates of treatment with modern stroke prevention medications.Methods: Data were included from 2 prospective hospital-based registries (Umea, Barcelona) and one prospective population-based study (Dublin). Patients with symptomatic 50%-99% carotid stenosis eligible for carotid revascularization were included and followed for early recurrent ipsilateral stroke or retinal artery occlusion (RAO).Results: Of 607 patients with symptomatic 50%-99% carotid stenosis, 377 met prespecified inclusion criteria. Ipsilateral recurrent ischemic stroke/RAO risk pre-revascularization was 2.7% (1 day), 5.3% (3 days), 11.5% (14 days), and 18.8% (90 days). On bivariate analysis, presentation with a cerebral vs ocular event was associated with higher recurrent stroke risk (log-rank p = 0.04). On multivariable Cox regression, recurrence was associated with older age (adjusted hazard ratio [HR] per 10-year increase 1.5, p = 0.02) with a strong trend for association with cerebral (stroke/TIA) vs ocular symptoms (adjusted HR 2.7, p = 0.06), but not degree of stenosis, smoking, vascular risk factors, or medications.Conclusions: We found high risk of recurrent ipsilateral ischemic events within the 14-day time period currently recommended for CEA. Randomized trials are needed to determine the benefits and safety of urgent vs subacute carotid revascularization within 14 days after symptom onset.
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| 3. |
- Patterson, Nick, et al.
(författare)
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Large-scale migration into Britain during the Middle to Late Bronze Age
- 2022
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; , s. 588-594
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Tidskriftsartikel (refereegranskat)abstract
- Present-day people from England and Wales harbour more ancestry derived from Early European Farmers (EEF) than people of the Early Bronze Age1. To understand this, we generated genome-wide data from 793 individuals, increasing data from the Middle to Late Bronze and Iron Age in Britain by 12-fold, and Western and Central Europe by 3.5-fold. Between 1000 and 875 BC, EEF ancestry increased in southern Britain (England and Wales) but not northern Britain (Scotland) due to incorporation of migrants who arrived at this time and over previous centuries, and who were genetically most similar to ancient individuals from France. These migrants contributed about half the ancestry of Iron Age people of England and Wales, thereby creating a plausible vector for the spread of early Celtic languages into Britain. These patterns are part of a broader trend of EEF ancestry becoming more similar across central and western Europe in the Middle to Late Bronze Age, coincident with archaeological evidence of intensified cultural exchange2-6. There was comparatively less gene flow from continental Europe during the Iron Age, and Britain's independent genetic trajectory is also reflected in the rise of the allele conferring lactase persistence to ~50% by this time compared to ~7% in central Europe where it rose rapidly in frequency only a millennium later. This suggests that dairy products were used in qualitatively different ways in Britain and in central Europe over this period.
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| 4. |
- Santangelo, James S., et al.
(författare)
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Global urban environmental change drives adaptation in white clover
- 2022
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375
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Tidskriftsartikel (refereegranskat)abstract
- Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural dines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.
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| 5. |
- Vaïopoulou, Maria, et al.
(författare)
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The 2016–2018 Greek-Swedish archaeological project at Thessalian Vlochos, Greece
- 2020
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Ingår i: Opuscula: Annual of the Swedish Institutes at Athens and Rome. - : Editorial Committee of the Swedish Institutes at Athens and Rome (ECSI). - 2000-0898. ; 13, s. 7-72
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Tidskriftsartikel (refereegranskat)abstract
- The Vlochos Archaeological Project (2016–2018) was a Greek-Swedish archaeological investigation of the remains of the ancient urban site at Vlochos in western Thessaly, Greece. Employing a wide array of non-invasive methods, the project succeeded in completely mapping the visible remains, which had previously not been systematically investigated. The extensive remains of multi-period urban fortifications, a Classical-Hellenistic city, a Roman town, and a Late Antique fortress were identified, evidence of the long history of habitation on this site. Since comparatively little fieldwork has been conducted in the region, the results significantly increase our knowledge of the history and archaeology of Thessaly.
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| 6. |
- Wells, Daniel J., et al.
(författare)
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Observations of phase changes in monoolein during high viscous injection
- 2022
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Ingår i: Journal of Synchrotron Radiation. - : International Union Of Crystallography. - 0909-0495 .- 1600-5775. ; 29:3, s. 602-614
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Tidskriftsartikel (refereegranskat)abstract
- Serial crystallography of membrane proteins often employs high-viscosity injectors (HVIs) to deliver micrometre-sized crystals to the X-ray beam. Typically, the carrier medium is a lipidic cubic phase (LCP) media, which can also be used to nucleate and grow the crystals. However, despite the fact that the LCP is widely used with HVIs, the potential impact of the injection process on the LCP structure has not been reported and hence is not yet well understood. The self-assembled structure of the LCP can be affected by pressure, dehydration and temperature changes, all of which occur during continuous flow injection. These changes to the LCP structure may in turn impact the results of X-ray diffraction measurements from membrane protein crystals. To investigate the influence of HVIs on the structure of the LCP we conducted a study of the phase changes in monoolein/water and monoolein/buffer mixtures during continuous flow injection, at both atmospheric pressure and under vacuum. The reservoir pressure in the HVI was tracked to determine if there is any correlation with the phase behaviour of the LCP. The results indicated that, even though the reservoir pressure underwent (at times) significant variation, this did not appear to correlate with observed phase changes in the sample stream or correspond to shifts in the LCP lattice parameter. During vacuum injection, there was a three-way coexistence of the gyroid cubic phase, diamond cubic phase and lamellar phase. During injection at atmospheric pressure, the coexistence of a cubic phase and lamellar phase in the monoolein/water mixtures was also observed. The degree to which the lamellar phase is formed was found to be strongly dependent on the co-flowing gas conditions used to stabilize the LCP stream. A combination of laboratory-based optical polarization microscopy and simulation studies was used to investigate these observations.
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