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Sökning: WFRF:(Sparkes A.)

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1.
  • Overview of the JET results
  • 2015
  • Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 55:10
  • Tidskriftsartikel (refereegranskat)
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2.
  • Morris, John A, et al. (författare)
  • An atlas of genetic influences on osteoporosis in humans and mice.
  • 2019
  • Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 51, s. 258-266
  • Tidskriftsartikel (refereegranskat)abstract
    • Osteoporosis is a common aging-related disease diagnosed primarily using bone mineral density (BMD). We assessed genetic determinants of BMD as estimated by heel quantitative ultrasound in 426,824 individuals, identifying 518 genome-wide significant loci (301 novel), explaining 20% of its variance. We identified 13 bone fracture loci, all associated with estimated BMD (eBMD), in ~1.2 million individuals. We then identified target genes enriched for genes known to influence bone density and strength (maximum odds ratio (OR)=58, P=1 × 10-75) from cell-specific features, including chromatin conformation and accessible chromatin sites. We next performed rapid-throughput skeletal phenotyping of 126 knockout mice with disruptions in predicted target genes and found an increased abnormal skeletal phenotype frequency compared to 526 unselected lines (P<0.0001). In-depth analysis of one gene, DAAM2, showed a disproportionate decrease in bone strength relative to mineralization. This genetic atlas provides evidence linking associated SNPs to causal genes, offers new insight into osteoporosis pathophysiology, and highlights opportunities for drug development.
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3.
  • Dunstan, R. H., et al. (författare)
  • Sweat facilitated amino acid losses in male athletes during exercise at 32-34°C
  • 2016
  • Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:12
  • Tidskriftsartikel (refereegranskat)abstract
    • Sweat contains amino acids and electrolytes derived from plasma and athletes can lose 1-2L of sweat per hour during exercise. Sweat may also contain contributions of amino acids as well as urea, sodium and potassium from the natural moisturizing factors (NMF) produced in the stratum corneum. In preliminary experiments, one participant was tested on three separate occasions to compare sweat composition with surface water washings from the same area of skin to assess contributions from NMF. Two participants performed a 40 minute self-paced cycle session with sweat collected from cleansed skin at regular intervals to assess the contributions to the sweat load from NMF over the period of exercise. The main study investigated sweat amino acid composition collected from nineteen male athletes following standardised endurance exercise regimes at 32-34°C and 20-30% RH. Plasma was also collected from ten of the athletes to compare sweat and plasma composition of amino acids. The amino acid profiles of the skin washings were similar to the sweat, suggesting that the NMF could contribute certain amino acids into sweat. Since the sweat collected from athletes contained some amino acid contributions from the skin, this fluid was subsequently referred to as "faux" sweat. Samples taken over 40 minutes of exercise showed that these contributions diminished over time and were minimal at 35 minutes. In the main study, the faux sweat samples collected from the athletes with minimal NMF contributions, were characterised by relatively high levels of serine, histidine, ornithine, glycine and alanine compared with the corresponding levels measured in the plasma. Aspartic acid was detected in faux sweat but not in the plasma. Glutamine and proline were lower in the faux sweat than plasma in all the athletes. Three phenotypic groups of athletes were defined based on faux sweat volumes and composition profiles of amino acids with varying relative abundances of histidine, serine, glycine and ornithine. It was concluded that for some individuals, faux sweat resulting from exercise at 32-34°C and 20-30% RH posed a potentially significant source of amino acid loss. © 2016 Dunstan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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4.
  • Dunstan, R. H., et al. (författare)
  • Sweat facilitated losses of amino acids in Standardbred horses and the application of supplementation strategies to maintain condition during training
  • 2015
  • Ingår i: Comparative Exercise Physiology. - : Wageningen Academic Publishers. - 1755-2540 .- 1755-2559. ; 11:4, s. 201-212
  • Tidskriftsartikel (refereegranskat)abstract
    • Little is known about the amino acid composition of horse sweat, but significant fluid losses can occur during exercise with the potential to facilitate substantial nutrient losses. Sweat and plasma amino acid compositions for Standardbred horses were assessed to determine losses during a standardised training regime. Two cohorts of horses 2013 (n=5) and 2014 (n=6) were assessed to determine baseline levels of plasma and sweat amino acids. An amino acid supplement designed to counter losses in sweat during exercise was provided after morning exercise daily for 5 weeks (2013, n=5; 2014, n=4). After the supplementation period, blood and sweat samples were collected to assess amino acid composition changes. From baseline assessments of sweat in both cohorts, it was found that serine, glutamic acid, histidine and phenylalanine were present at up to 9 times the corresponding plasma concentrations and aspartic acid at 0-2.2 mu mol/l in plasma was measured at 154-262 mu mol/l in sweat. In contrast, glutamine, asparagine, methionine and cystine were conserved in the plasma by having lower concentrations in the sweat. The predominant plasma amino acids were glycine, glutamine, alanine, valine, serine, lysine and leucine. As the sweat amino acid profile did not simply reflect plasma composition, it was proposed that mechanisms exist to generate high concentrations of certain amino acids in sweat whilst selectively preventing the loss of others. The estimated amino acid load in 16 l of circulating plasma was 3.8-4.3 g and the calculated loss via sweat during high intensity exercise was 1.6-3.0 g. Following supplementation, total plasma amino acid levels from both cohorts increased from initial levels of 2,293 and 2,044 mu mol/l to post-supplementation levels of 2,674 and 2,663 mu mol/l respectively (P<0.05). It was concluded that the strategy of providing free amino acids immediately after exercise resulted in raising resting plasma amino acid levels.
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5.
  • Lindgren, Paula, et al. (författare)
  • Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returns
  • 2020
  • Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037. ; 289, s. 69-92
  • Tidskriftsartikel (refereegranskat)abstract
    • The CM carbonaceous chondrites have all been aqueously altered, and some of them were subsequently heated in a parent body environment. Here we have sought to understand the impact of short duration heating on a highly aqueously altered CM through laboratory experiments on Allan Hills (ALH) 83100. Unheated ALH 83100 contains 83 volume per cent serpentine within the fine-grained matrix and altered chondrules. The matrix also hosts grains of calcite and dolomite, which are often intergrown with tochilinite, Fe(Ni) sulphides (pyrrhotite, pentlandite), magnetite and organic matter. Some of the magnetite formed by replacement of Fe(Ni) sulphides that were accreted from the nebula. Laboratory heating to 400 °C has caused partial dehydroxylation of serpentine and loss of isotopically light oxygen leading to an increase in bulk δ18O and fall in Δ17O. Tochilinite has decomposed to magnetite, whereas carbonates have remained unaltered. With regards to infrared spectroscopy (4000–400 cm−1; 2.5–25 µm), heating to 400 °C has resulted in decreased emissivity (increased reflectance), a sharper and more symmetric OH band at 3684 cm−1 (2.71 µm), a broadening of the Si[sbnd]O stretching band together with movement of its minimum to longer wavenumbers, and a decreasing depth of the Mg[sbnd]OH band (625 cm−1; 16 µm). The Si[sbnd]O bending band is unmodified by mild heating. With heating to 800 °C the serpentine has fully dehydroxylated and recrystallized to ∼Fo60/70 olivine. Bulk δ18O has further increased and Δ17O decreased. Troilite and pyrrhotite have formed, and recrystallization of pentlandite has produced Fe,Ni metal. Calcite and dolomite were calcined at ∼700 °C and in their place is an un-named Ca-Fe oxysulphide. Heating changes the structural order of organic matter so that Raman spectroscopy of carbon in the 800 °C sample shows an increased (D1 + D4) proportional area parameter. The infrared spectrum of the 800 °C sample confirms the abundance of Fe-bearing olivine and is very similar to the spectrum of naturally heated stage IV CM Pecora Escarpment 02010. The temperature-related mineralogical, chemical, isotopic and spectroscopic signatures defined in ALH 83100 will help to track the post-hydration thermal histories of carbonaceous chondrite meteorites, and samples returned from the primitive asteroids Ryugu and Bennu.
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6.
  • Sparkes, R. B., et al. (författare)
  • GDGT distributions on the East Siberian Arctic Shelf : implications for organic carbon export, burial and degradation
  • 2015
  • Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 12:12, s. 3753-3768
  • Tidskriftsartikel (refereegranskat)abstract
    • Siberian permafrost contains a globally significant pool of organic carbon (OC) that is vulnerable to enhanced warming and subsequent release into the contemporary carbon cycle. OC release by both fluvial and coastal erosion has been reported in the region, but the behaviour of this material in the Arctic Ocean is insufficiently understood. The balance between OC deposition and degradation on the East Siberian Arctic Shelf (ESAS) influences the climate-carbon cycle feedback in this area. In this study we couple measurements of glycerol dialkyl glycerol tetraethers (GDGTs) with bulk geochemical observations to improve knowledge of the sources of OC to the ESAS, the behaviour of specific biomarkers on the shelf and the balance between delivery and removal of different carbon pools. Branched GDGT (brGDGT) concentrations were highest close to river mouths, yet low in 'ice complex' permafrost deposits, supporting recent observations that brGDGTs are mostly delivered by fluvial erosion, and may be a tracer for this in complex sedimentary environments. BrGDGT concentrations and the branched and isoprenoidal tetraether (BIT) index reduced quickly offshore, demonstrating a rapid reduction in river influence. Stable carbon isotope ratios changed at a different rate to the BIT index, suggesting not only that OC on the shelf is sourced from fluvial erosion but also that erosion of coastal sediments delivers substantial quantities of OC to the Arctic Ocean. A model of OC export from fluvial, coastal and marine sources is able to recreate the biomarker and bulk observations and provide estimates for the influence of fluvial and coastal OC across the whole shelf. The model shows that coastal erosion delivers 43 % of the OC and 87 % of the mineral sediment to the ESAS, but that rivers deliver 72 % of brGDGTs, indicating that brGDGTs can be used as a proxy for river-derived sediment.
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8.
  • Åkesdotter, Cecilia, et al. (författare)
  • Elite athletes seeking psychiatric treatment : Stigma, impression management strategies and the dangers of the performance narrative
  • 2024
  • Ingår i: Journal of Applied Sport Psychology. - : Taylor & Francis. - 1041-3200 .- 1533-1571. ; 36:1, s. 24-44
  • Tidskriftsartikel (refereegranskat)abstract
    • This study explores the reasons given by five elite athletes for choosing to seek psychiatric support and treatment outside, rather than inside, their own sport environments. Life story interviews were conducted with these athletes, who were recruited from an open psychiatric clinic in Stockholm, Sweden. The interviews were then subjected to a structural and a thematic narrative analysis. The former revealed the power of the performance narrative to frame the lives of the athletes by producing a single-minded focus on performance outcomes that justifies, and even demands, the exclusion of any form of psychological weakness or vulnerability. The latter revealed the relationship between the performance narrative and the process of stigmatization associated with psychiatric disorders in elite sport and how this pressures athletes to adopt specific Goffmanesque impression management strategies to protect themselves within their own sport environments. These strategies were as follows: wearing a mask (to hide their psychological suffering), adhering to a vow of silence (making stories of psychological suffering untellable in elite sport), and finding an alibi (a way of portraying suffering in an “acceptable” form). Finally, we reflect on implications for practice, including the potential of narrative care, to help elite athletes explore alternative narratives that might be supportive rather than dangerous companions when suffering from psychiatric disorders.Lay summary: Five elite athletes were interviewed about their experiences of living with psychiatric disorders, focusing on their choice to seek psychiatric treatment outside, rather than inside, their own sport environments. Stigma and adhering to a single-minded focus on performance forced the athletes to adopt different strategies to hide their psychological suffering.IMPLICATIONS FOR PRACTICEThe performance narrative, characterized by a single-minded focus on performance that demands the exclusion of any form of psychological weakness, stigmatizes elite athletes with psychiatric disorders, making their stories untellable within elite sport.To protect themselves from stigma, these athletes developed impression management strategies to hide their psychological suffering within elite sport.Knowledge of these impression management strategies among different mental health providers working to support athletes, and the use of narrative care to explore alternative narratives, may facilitate elite athletes in seeking support, help, and understanding for their psychiatric disorders.
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