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Sökning: WFRF:(Maher B) > Naturvetenskap

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1.
  • Munn-Chernoff, M. A., et al. (författare)
  • Shared genetic risk between eating disorder- and substance-use-related phenotypes: Evidence from genome-wide association studies
  • 2021
  • Ingår i: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 26:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Eating disorders and substance use disorders frequently co-occur. Twin studies reveal shared genetic variance between liabilities to eating disorders and substance use, with the strongest associations between symptoms of bulimia nervosa and problem alcohol use (genetic correlation [r(g)], twin-based = 0.23-0.53). We estimated the genetic correlation between eating disorder and substance use and disorder phenotypes using data from genome-wide association studies (GWAS). Four eating disorder phenotypes (anorexia nervosa [AN], AN with binge eating, AN without binge eating, and a bulimia nervosa factor score), and eight substance-use-related phenotypes (drinks per week, alcohol use disorder [AUD], smoking initiation, current smoking, cigarettes per day, nicotine dependence, cannabis initiation, and cannabis use disorder) from eight studies were included. Significant genetic correlations were adjusted for variants associated with major depressive disorder and schizophrenia. Total study sample sizes per phenotype ranged from similar to 2400 to similar to 537 000 individuals. We used linkage disequilibrium score regression to calculate single nucleotide polymorphism-based genetic correlations between eating disorder- and substance-use-related phenotypes. Significant positive genetic associations emerged between AUD and AN (r(g) = 0.18; false discovery rate q = 0.0006), cannabis initiation and AN (r(g) = 0.23; q < 0.0001), and cannabis initiation and AN with binge eating (r(g) = 0.27; q = 0.0016). Conversely, significant negative genetic correlations were observed between three nondiagnostic smoking phenotypes (smoking initiation, current smoking, and cigarettes per day) and AN without binge eating (r(gs) = -0.19 to -0.23; qs < 0.04). The genetic correlation between AUD and AN was no longer significant after co-varying for major depressive disorder loci. The patterns of association between eating disorder- and substance-use-related phenotypes highlights the potentially complex and substance-specific relationships among these behaviors.
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2.
  • 2019
  • Tidskriftsartikel (refereegranskat)
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4.
  • Hillier, Ladeana W, et al. (författare)
  • Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
  • 2004
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 432:7018, s. 695-716
  • Tidskriftsartikel (refereegranskat)abstract
    • We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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5.
  • Silva-Tamayo, Juan Carlos, et al. (författare)
  • Global perturbation of the marine calcium cycle during the Permian-Triassic transition
  • 2018
  • Ingår i: Geological Society of America Bulletin. - 0016-7606. ; 130:7-8, s. 1323-1338
  • Tidskriftsartikel (refereegranskat)abstract
    • A negative shift in the calcium isotopiccomposition of marine carbonate rocksspanning the end-Permian extinction horizonin South China has been used to arguefor an ocean acidification event coincidentwith mass extinction. This interpretationhas proven controversial, both because theexcursion has not been demonstrated acrossmultiple, widely separated localities, and becausemodeling results of coupled carbon andcalcium isotope records illustrate that calciumcycle imbalances alone cannot accountfor the full magnitude of the isotope excursion.Here, we further test potential controlson the Permian-Triassic calcium isotoperecord by measuring calcium isotope ratiosfrom shallow-marine carbonate successionsspanning the Permian-Triassic boundary inTurkey, Italy, and Oman. All measured sectionsdisplay negative shifts in δ44/40Ca of upto 0.6‰. Consistency in the direction, magnitude,and timing of the calcium isotope excursionacross these widely separated localitiesimplies a primary and global δ44/40Ca signature.Based on the results of a coupled boxmodel of the geological carbon and calciumcycles, we interpret the excursion to reflect aseries of consequences arising from volcanicCO2 release, including a temporary decreasein seawater δ44/40Ca due to short-lived oceanacidification and a more protracted increasein calcium isotope fractionation associatedwith a shift toward more primary aragonitein the sediment and, potentially, subsequentlyelevated carbonate saturation statescaused by the persistence of elevated CO2delivery from volcanism. Locally, changingbalances between aragonite and calcite productionare sufficient to account for the calciumisotope excursions, but this effect alonedoes not explain the globally observed negativeexcursion in the δ13C values of carbonatesediments and organic matter as well. Onlya carbon release event and related geochemicalconsequences are consistent both withcalcium and carbon isotope data. The carbonrelease scenario can also account for oxygenisotope evidence for dramatic and protractedglobal warming as well as paleontologicalevidencefor the preferential extinction ofmarine animals most susceptible to acidification,warming, and anoxia.
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6.
  • Bansal, Sheel, et al. (författare)
  • Practical Guide to Measuring Wetland Carbon Pools and Fluxes
  • 2023
  • Ingår i: Wetlands (Wilmington, N.C.). - : SPRINGER. - 0277-5212 .- 1943-6246. ; 43:8
  • Forskningsöversikt (refereegranskat)abstract
    • Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C. Sampling approaches range in their representation of wetland C from short to long timeframes and local to landscape spatial scales. This review summarizes common and cutting-edge methodological approaches for quantifying wetland C pools and fluxes. We first define each of the major C pools and fluxes and provide rationale for their importance to wetland C dynamics. For each approach, we clarify what component of wetland C is measured and its spatial and temporal representativeness and constraints. We describe practical considerations for each approach, such as where and when an approach is typically used, who can conduct the measurements (expertise, training requirements), and how approaches are conducted, including considerations on equipment complexity and costs. Finally, we review key covariates and ancillary measurements that enhance the interpretation of findings and facilitate model development. The protocols that we describe to measure soil, water, vegetation, and gases are also relevant for related disciplines such as ecology. Improved quality and consistency of data collection and reporting across studies will help reduce global uncertainties and develop management strategies to use wetlands as nature-based climate solutions.
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7.
  • Brown, Dylan R., et al. (författare)
  • Hypersaline tidal flats as important "blue carbon" systems : a case study from three ecosystems
  • 2021
  • Ingår i: Biogeosciences. - : COPERNICUS GESELLSCHAFT MBH. - 1726-4170 .- 1726-4189. ; 18:8, s. 2527-2538
  • Tidskriftsartikel (refereegranskat)abstract
    • Hypersaline tidal flats (HTFs) are coastal ecosystems with freshwater deficits often occurring in arid or semiarid regions near mangrove supratidal zones with no major fluvial contributions. Here, we estimate that organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) were buried at rates averaging 21 (+/- 6), 1.7 (+/- 0.3) and 1.4 (+/- 0.3) gm(-2) yr(-1), respectively, during the previous century in three contrasting HTF systems, one in Brazil (eutrophic) and two in Australia (oligotrophic). Although these rates are lower than those from nearby mangrove, saltmarsh and seagrass systems, the importance of HTFs as sinks for OC, TN and TP may be significant given their extensive coverage. Despite the measured short-term variability between net air-saltpan CO2 influx and emission estimates found during the dry and wet season in the Brazilian HTF, the only site with seasonal CO2 flux measurements, the OC sedimentary profiles over several decades suggest efficient OC burial at all sites. Indeed, the stable isotopes of OC and TN (delta C-13 and delta N-1(5)) along with C : N ratios show that microphytobenthos are the major source of the buried OC in these HTFs. Our findings highlight a previously unquantified carbon as well as a nutrient sink and suggest that coastal HTF ecosystems could be included in the emerging blue carbon framework.
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8.
  • Maher, A., et al. (författare)
  • Solubility of the metastable polymorph of piracetam (Form II) in a range of solvents
  • 2012
  • Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 57:12, s. 3525-3531
  • Tidskriftsartikel (refereegranskat)abstract
    • The solid-liquid solubility of the polymorph known as Form II of 2-oxo-1-pyrolidine acetamide (Piracetam) has been determined gravimetrically in different solvents. Form II is the metastable polymorph of piracetam at ambient conditions and has been isolated and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Monitoring the solution concentration and the polymorphic composition of the solid phase displayed that this metastable form has a sufficient lifetime when in contact with the solvents to allow measurement of its solubility over the temperature range (278 to 323) K. Four solvents are included: ethanol, 2-propanol, acetone, and 1,4-dioxane. The results show that the solubility of Form II increases with increasing solvent polarity and solvent acidity. Form II has a slightly higher solubility than the stable Form III in all solvents at all temperatures, but the solubility difference is very small. Since Form II is known to transform to Form I below its melting point, a set of regression equations which can be used to extrapolate solubility data to the melting point of Form II were applied to the collected data.
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9.
  • Sparkes, Robert B., et al. (författare)
  • Carbonaceous material export from Siberian permafrost tracked across the Arctic Shelf using Raman spectroscopy
  • 2018
  • Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 12:10, s. 3293-3309
  • Tidskriftsartikel (refereegranskat)abstract
    • Warming-induced erosion of permafrost from Eastern Siberia mobilises large amounts of organic carbon and delivers it to the East Siberian Arctic Shelf (ESAS). In this study Raman spectroscopy of carbonaceous material (CM) was used to characterise, identify and track the most recalcitrant fraction of the organic load: 1463 spectra were obtained from surface sediments collected across the ESAS and automatically analysed for their Raman peaks. Spectra were classified by their peak areas and widths into disordered, intermediate, mildly graphitised and highly graphitised groups and the distribution of these classes was investigated across the shelf. Disordered CM was most prevalent in a permafrost core from Kurungnakh Island and from areas known to have high rates of coastal erosion. Sediments from outflows of the Indigirka and Kolyma rivers were generally enriched in intermediate CM. These different sediment sources were identified and distinguished along an E-W transect using their Raman spectra, showing that sediment is not homogenised on the ESAS. Distal samples, from the ESAS slope, contained greater amounts of highly graphitised CM compared to the rest of the shelf, attributable to degradation or, more likely, winnowing processes offshore. The presence of all four spectral classes in distal sediments demonstrates that CM degrades much more slowly than lipid biomarkers and other traditional tracers of terrestrial organic matter and shows that alongside degradation of the more labile organic matter component there is also conservative transport of carbon across the shelf toward the deep ocean. Thus, carbon cycle calculations must consider the nature as well as the amount of carbon liberated from thawing permafrost and other erosional settings.
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10.
  • Walden, L., et al. (författare)
  • Multi-scale mapping of Australia's terrestrial and blue carbon stocks and their continental and bioregional drivers
  • 2023
  • Ingår i: Communications Earth & Environment. - 2662-4435. ; 4:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Multi-scale spatial machine learning of soil carbon stocks in Australia's terrestrial and coastal marine ecosystems reveals eight bio-regions and their underlying subregional drivers that can help inform strategies for conservation and climate change mitigation. The soil in terrestrial and coastal blue carbon ecosystems is an important carbon sink. National carbon inventories require accurate assessments of soil carbon in these ecosystems to aid conservation, preservation, and nature-based climate change mitigation strategies. Here we harmonise measurements from Australia's terrestrial and blue carbon ecosystems and apply multi-scale machine learning to derive spatially explicit estimates of soil carbon stocks and the environmental drivers of variation. We find that climate and vegetation are the primary drivers of variation at the continental scale, while ecosystem type, terrain, clay content, mineralogy and nutrients drive subregional variations. We estimate that in the top 0-30 cm soil layer, terrestrial ecosystems hold 27.6 Gt (19.6-39.0 Gt), and blue carbon ecosystems 0.35 Gt (0.20-0.62 Gt). Tall open eucalypt and mangrove forests have the largest soil carbon content by area, while eucalypt woodlands and hummock grasslands have the largest total carbon stock due to the vast areas they occupy. Our findings suggest these are essential ecosystems for conservation, preservation, emissions avoidance, and climate change mitigation because of the additional co-benefits they provide.
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