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Träfflista för sökning "WFRF:(Charman A. E.) "

Sökning: WFRF:(Charman A. E.)

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1.
  • Ahmadi, M., et al. (författare)
  • An improved limit on the charge of antihydrogen from stochastic acceleration
  • 2016
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 529:7586, s. 373-
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Antimatter continues to intrigue physicists because of its apparent absence in the observable Universe. Current theory requires that matter and antimatter appeared in equal quantities after the Big Bang, but the Standard Model of particle physics offers no quantitative explanation for the apparent disappearance of half the Universe. It has recently become possible to study trapped atoms(1-4) of antihydrogen to search for possible, as yet unobserved, differences in the physical behaviour of matter and antimatter. Here we consider the charge neutrality of the antihydrogen atom. By applying stochastic acceleration to trapped antihydrogen atoms, we determine an experimental bound on the antihydrogen charge, Qe, of vertical bar Q vertical bar &lt; 0.71 parts per billion (one standard deviation), in which e is the elementary charge. This bound is a factor of 20 less than that determined from the best previous measurement(5) of the antihydrogen charge. The electrical charge of atoms and molecules of normal matter is known(6) to be no greater than about 10(-21)e for a diverse range of species including H-2, He and SF6. Charge-parity-time symmetry and quantum anomaly cancellation(7) demand that the charge of antihydrogen be similarly small. Thus, our measurement constitutes an improved limit and a test of fundamental aspects of the Standard Model. If we assume charge superposition and use the best measured value of the antiproton charge(8), then we can place a new limit on the positron charge anomaly (the relative difference between the positron and elementary charge) of about one part per billion (one standard deviation), a 25-fold reduction compared to the current best measurement(8),(9).</p>
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2.
  • Amole, C., et al. (författare)
  • An experimental limit on the charge of antihydrogen
  • 2014
  • Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 5, s. 3955
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The properties of antihydrogen are expected to be identical to those of hydrogen, and any differences would constitute a profound challenge to the fundamental theories of physics. The most commonly discussed antiatom- based tests of these theories are searches for antihydrogen- hydrogen spectral differences (tests of CPT (charge- parity- time) invariance) or gravitational differences (tests of the weak equivalence principle). Here we, the ALPHA Collaboration, report a different and somewhat unusual test of CPT and of quantum anomaly cancellation. A retrospective analysis of the influence of electric fields on antihydrogen atoms released from the ALPHA trap finds a mean axial deflection of 4.1 +/- 3.4mm for an average axial electric field of 0.51Vmm1. Combined with extensive numerical modelling, this measurement leads to a bound on the charge Qe of antihydrogen of Q (+/- 1.3 +/- 1.1 +/- 0.4)10 8. Here, e is the unit charge, and the errors are from statistics and systematic effects.</p>
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3.
  • de Bildt, A, et al. (författare)
  • Autism Diagnostic Interview-Revised (ADI-R) Algorithms for Toddlers and Young Preschoolers : Application in a Non-US Sample of 1,104 Children
  • 2015
  • Ingår i: Journal of Autism and Developmental Disorders. - Springer. - 0162-3257. ; 45:7, s. 91-2076
  • Tidskriftsartikel (refereegranskat)abstract
    • The current study aimed to investigate the Autism Diagnostic Interview-Revised (ADI-R) algorithms for toddlers and young preschoolers (Kim and Lord, J Autism Dev Disord 42(1):82-93, 2012) in a non-US sample from ten sites in nine countries (n = 1,104). The construct validity indicated a good fit of the algorithms. The diagnostic validity was lower, with satisfactorily high specificities but moderate sensitivities. Young children with clinical ASD and lower language ability were largely in the mild-to-moderate or moderate-to-severe concern ranges of the ADI-R, nearly half of the older and phrase speech ASD-group fell into the little-to-no concern range. Although broadly the findings support the toddler algorithms, further work is required to understand why they might have different properties in different samples to further inform research and clinical use.
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4.
  • Charman, D. J., et al. (författare)
  • Climate-related changes in peatland carbon accumulation during the last millennium
  • 2013
  • Ingår i: Biogeosciences. - Copernicus Publications. - 1726-4189. ; 10:2, s. 929-944
  • Tidskriftsartikel (refereegranskat)abstract
    • Peatlands are a major terrestrial carbon store and a persistent natural carbon sink during the Holocene, but there is considerable uncertainty over the fate of peatland carbon in a changing climate. It is generally assumed that higher temperatures will increase peat decay, causing a positive feedback to climate warming and contributing to the global positive carbon cycle feedback. Here we use a new extensive database of peat profiles across northern high latitudes to examine spatial and temporal patterns of carbon accumulation over the past millennium. Opposite to expectations, our results indicate a small negative carbon cycle feedback from past changes in the long-term accumulation rates of northern peatlands. Total carbon accumulated over the last 1000 yr is linearly related to contemporary growing season length and photosynthetically active radiation, suggesting that variability in net primary productivity is more important than decomposition in determining long-term carbon accumulation. Furthermore, northern peatland carbon sequestration rate declined over the climate transition from the Medieval Climate Anomaly (MCA) to the Little Ice Age (LIA), probably because of lower LIA temperatures combined with increased cloudiness suppressing net primary productivity. Other factors including changing moisture status, peatland distribution, fire, nitrogen deposition, permafrost thaw and methane emissions will also influence future peatland carbon cycle feedbacks, but our data suggest that the carbon sequestration rate could increase over many areas of northern peatlands in a warmer future.
5.
  • Schmitt, Jochen, et al. (författare)
  • Towards global consensus on outcome measures for atopic eczema research: results of the HOME II meeting
  • 2012
  • Ingår i: Allergy. - Wiley-Blackwell. - 1398-9995. ; 67:9, s. 1111-1117
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of nonstandardized and inadequately validated outcome measures in atopic eczema trials is a major obstacle to practising evidence-based dermatology. The Harmonising Outcome Measures for Eczema (HOME) initiative is an international multiprofessional group dedicated to atopic eczema outcomes research. In June 2011, the HOME initiative conducted a consensus study involving 43 individuals from 10 countries, representing different stakeholders (patients, clinicians, methodologists, pharmaceutical industry) to determine core outcome domains for atopic eczema trials, to define quality criteria for atopic eczema outcome measures and to prioritize topics for atopic eczema outcomes research. Delegates were given evidence-based information, followed by structured group discussion and anonymous consensus voting. Consensus was achieved to include clinical signs, symptoms, long-term control of flares and quality of life into the core set of outcome domains for atopic eczema trials. The HOME initiative strongly recommends including and reporting these core outcome domains as primary or secondary endpoints in all future atopic eczema trials. Measures of these core outcome domains need to be valid, sensitive to change and feasible. Prioritized topics of the HOME initiative are the identification/development of the most appropriate instruments for the four core outcome domains. HOME is open to anyone with an interest in atopic eczema outcomes research.
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6.
  • Tillmann, J., et al. (författare)
  • Evaluating Sex and Age Differences in ADI-R and ADOS Scores in a Large European Multi-site Sample of Individuals with Autism Spectrum Disorder
  • 2018
  • Ingår i: Journal of Autism and Developmental Disorders. - Springer. - 0162-3257. ; 48:7, s. 2490-2505
  • Tidskriftsartikel (refereegranskat)abstract
    • Research on sex-related differences in Autism Spectrum Disorder (ASD) has been impeded by small samples. We pooled 28 datasets from 18 sites across nine European countries to examine sex differences in the ASD phenotype on the ADI-R (376 females, 1763 males) and ADOS (233 females, 1187 males). On the ADI-R, early childhood restricted and repetitive behaviours were lower in females than males, alongside comparable levels of social interaction and communication difficulties in females and males. Current ADI-R and ADOS scores showed no sex differences for ASD severity. There were lower socio-communicative symptoms in older compared to younger individuals. This large European ASD sample adds to the literature on sex and age variations of ASD symptomatology.
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9.
  • Gallego-Sala, Angela, et al. (författare)
  • Latitudinal limits to the predicted increase of the peatland carbon sink with warming
  • 2018
  • Ingår i: Nature Climate Change. - 1758-678X .- 1758-6798. ; 8:10, s. 907-
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The carbon sink potential of peatlands depends on the balance of carbon uptake by plants and microbial decomposition. The rates of both these processes will increase with warming but it remains unclear which will dominate the global peatland response. Here we examine the global relationship between peatland carbon accumulation rates during the last millennium and planetary-scale climate space. A positive relationship is found between carbon accumulation and cumulative photosynthetically active radiation during the growing season for mid- to high-latitude peatlands in both hemispheres. However, this relationship reverses at lower latitudes, suggesting that carbon accumulation is lower under the warmest climate regimes. Projections under Representative Concentration Pathway (RCP)2.6 and RCP8.5 scenarios indicate that the present-day global sink will increase slightly until around AD 2100 but decline thereafter. Peatlands will remain a carbon sink in the future, but their response to warming switches from a negative to a positive climate feedback (decreased carbon sink with warming) at the end of the twenty-first century.</p>
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10.
  • Gallego-Sala, Angela V., et al. (författare)
  • Latitudinal limits to the predicted increase of the peatland carbon sink with warming
  • 2018
  • Ingår i: Nature Climate Change. - 1758-678X .- 1758-6798. ; 8:10, s. 907-913
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The carbon sink potential of peatlands depends on the balance of carbon uptake by plants and microbial decomposition. The rates of both these processes will increase with warming but it remains unclear which will dominate the global peatland response. Here we examine the global relationship between peatland carbon accumulation rates during the last millennium and planetary-scale climate space. A positive relationship is found between carbon accumulation and cumulative photosynthetically active radiation during the growing season for mid- to high-latitude peatlands in both hemispheres. However, this relationship reverses at lower latitudes, suggesting that carbon accumulation is lower under the warmest climate regimes. Projections under Representative Concentration Pathway (RCP)2.6 and RCP8.5 scenarios indicate that the present-day global sink will increase slightly until around ad 2100 but decline thereafter. Peatlands will remain a carbon sink in the future, but their response to warming switches from a negative to a positive climate feedback (decreased carbon sink with warming) at the end of the twenty-first century.</p>
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