Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Hughes David) "

Sökning: WFRF:(Hughes David)

Sortera/gruppera träfflistan
  • Blunden, Jessica, et al. (författare)
  • State of the Climate in 2012
  • 2013
  • Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007. ; 94:8, s. S1-S258
  • Tidskriftsartikel (refereegranskat)abstract
    • For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern conditions. Nevertheless, other large-scale climate patterns and extreme weather events impacted various regions during the year. A negative phase of the Arctic Oscillation from mid-January to early February contributed to frigid conditions in parts of northern Africa, eastern Europe, and western Asia. A lack of rain during the 2012 wet season led to the worst drought in at least the past three decades for northeastern Brazil. Central North America also experienced one of its most severe droughts on record. The Caribbean observed a very wet dry season and it was the Sahel's wettest rainy season in 50 years. Overall, the 2012 average temperature across global land and ocean surfaces ranked among the 10 warmest years on record. The global land surface temperature alone was also among the 10 warmest on record. In the upper atmosphere, the average stratospheric temperature was record or near-record cold, depending on the dataset. After a 30-year warming trend from 1970 to 1999 for global sea surface temperatures, the period 2000-12 had little further trend. This may be linked to the prevalence of La Ni a-like conditions during the 21st century. Heat content in the upper 700 m of the ocean remained near record high levels in 2012. Net increases from 2011 to 2012 were observed at 700-m to 2000-m depth and even in the abyssal ocean below. Following sharp decreases in to the effects of La Ni a, sea levels rebounded to reach records highs in 2012. The increased hydrological cycle seen in recent years continued, with more evaporation in drier locations and more precipitation in rainy areas. In a pattern that has held since 2004, salty areas of the ocean surfaces and subsurfaces were anomalously salty on average, while fresher areas were anomalously fresh. Global tropical cyclone activity during 2012 was near average, with a total of 84 storms compared with the 1981-2010 average of 89. Similar to 2010 and 2011, the North Atlantic was the only hurricane basin that experienced above-normal activity. In this basin, Sandy brought devastation to Cuba and parts of the eastern North American seaboard. All other basins experienced either near-or below-normal tropical cyclone activity. Only three tropical cyclones reached Category 5 intensity-all in Bopha became the only storm in the historical record to produce winds greater than 130 kt south of 7 N. It was also the costliest storm to affect the Philippines and killed more than 1000 residents. Minimum Arctic sea ice extent in September and Northern Hemisphere snow cover extent in June both reached new record lows. June snow cover extent is now declining at a faster rate (-17.6% per decade) than September sea ice extent (-13.0% per decade). Permafrost temperatures reached record high values in northernmost Alaska. A new melt extent record occurred on 11-12 July on the Greenland ice sheet; 97% of the ice sheet showed some form of melt, four times greater than the average melt for this time of year. The climate in Antarctica was relatively stable overall. The largest maximum sea ice extent since records begain in 1978 was observed in September 2012. In the stratosphere, warm air led to the second smallest ozone hole in the past two decades. Even so, the springtime ozone layer above Antarctica likely will not return to its early 1980s state until about 2060. Following a slight decline associated with the global 2 emissions from fossil fuel combustion and cement production reached a record 9.5 +/- 0.5 Pg C in 2011 and a new record of 9.7 +/- 0.5 Pg C is estimated for 2012. Atmospheric CO2 concentrations increased by 2.1 ppm in 2012, to 392.6 ppm. In spring 2012, 2 concentration exceeded 400 ppm at 7 of the 13 Arctic observation sites. Globally, other greenhouse gases including methane and nitrous oxide also continued to rise in concentration and the combined effect now represents a 32% increase in radiative forcing over a 1990 baseline. Concentrations of most ozone depleting substances continued to fall.
  • Clark, Andrew G., et al. (författare)
  • Evolution of genes and genomes on the Drosophila phylogeny.
  • 2007
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 450:7167, s. 203-218
  • Tidskriftsartikel (refereegranskat)abstract
    • Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.
  • Fratiglioni, Laura, et al. (författare)
  • Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer's disease
  • 2017
  • Ingår i: Nature Genetics. - 1061-4036 .- 1546-1718. ; 49:9, s. 1373-
  • Tidskriftsartikel (refereegranskat)abstract
    • We identified rare coding variants associated with Alzheimer's disease in a three-stage case-control study of 85,133 subjects. In stage 1, we genotyped 34,174 samples using a whole-exome microarray. In stage 2, we tested associated variants (P < 1 x 10(-4)) in 35,962 independent samples using de novo genotyping and imputed genotypes. In stage 3, we used an additional 14,997 samples to test the most significant stage 2 associations (P < 5 x 10(-8)) using imputed genotypes. We observed three new genome-wide significant nonsynonymous variants associated with Alzheimer's disease: a protective variant in PLCG2 (rs72824905: p. Pro522Arg, P = 5.38 x 10(-10), odds ratio (OR) = 0.68, minor allele frequency (MAF) cases = 0.0059, MAFcontrols = 0.0093), a risk variant in ABI3 (rs616338: p. Ser209Phe, P = 4.56 x 10-10, OR = 1.43, MAFcases = 0.011, MAFcontrols = 0.008), and a new genome-wide significant variant in TREM2 (rs143332484: p. Arg62His, P = 1.55 x 10(-14), OR = 1.67, MAFcases = 0.0143, MAFcontrols = 0.0089), a known susceptibility gene for Alzheimer's disease. These protein-altering changes are in genes highly expressed in microglia and highlight an immune-related protein-protein interaction network enriched for previously identified risk genes in Alzheimer's disease. These genetic findings provide additional evidence that the microglia-mediated innate immune response contributes directly to the development of Alzheimer's disease.
  • Craddock, Nick, et al. (författare)
  • Genome-wide association study of CNVs in 16,000 cases of eight common diseases and 3,000 shared controls
  • 2010
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 464:7289, s. 713-720
  • Tidskriftsartikel (refereegranskat)abstract
    • Copy number variants (CNVs) account for a major proportion of human genetic polymorphism and have been predicted to have an important role in genetic susceptibility to common disease. To address this we undertook a large, direct genome-wide study of association between CNVs and eight common human diseases. Using a purpose-designed array we typed,19,000 individuals into distinct copy-number classes at 3,432 polymorphic CNVs, including an estimated similar to 50% of all common CNVs larger than 500 base pairs. We identified several biological artefacts that lead to false-positive associations, including systematic CNV differences between DNAs derived from blood and cell lines. Association testing and follow-up replication analyses confirmed three loci where CNVs were associated with disease-IRGM for Crohn's disease, HLA for Crohn's disease, rheumatoid arthritis and type 1 diabetes, and TSPAN8 for type 2 diabetes-although in each case the locus had previously been identified in single nucleotide polymorphism (SNP)-based studies, reflecting our observation that most common CNVs that are well-typed on our array are well tagged by SNPs and so have been indirectly explored through SNP studies. We conclude that common CNVs that can be typed on existing platforms are unlikely to contribute greatly to the genetic basis of common human diseases.
  • Jones, Gregory T., et al. (författare)
  • Meta-Analysis of Genome-Wide Association Studies for Abdominal Aortic Aneurysm Identifies Four New Disease-Specific Risk Loci
  • 2017
  • Ingår i: Circulation Research. - 0009-7330 .- 1524-4571. ; 120:2, s. 341-
  • Tidskriftsartikel (refereegranskat)abstract
    • Rationale: Abdominal aortic aneurysm (AAA) is a complex disease with both genetic and environmental risk factors. Together, 6 previously identified risk loci only explain a small proportion of the heritability of AAA. Objective: To identify additional AAA risk loci using data from all available genome-wide association studies. Methods and Results: Through a meta-analysis of 6 genome-wide association study data sets and a validation study totaling 10 204 cases and 107 766 controls, we identified 4 new AAA risk loci: 1q32.3 (SMYD2), 13q12.11 (LINC00540), 20q13.12 (near PCIF1/MMP9/ZNF335), and 21q22.2 (ERG). In various database searches, we observed no new associations between the lead AAA single nucleotide polymorphisms and coronary artery disease, blood pressure, lipids, or diabetes mellitus. Network analyses identified ERG, IL6R, and LDLR as modifiers of MMP9, with a direct interaction between ERG and MMP9. Conclusions: The 4 new risk loci for AAA seem to be specific for AAA compared with other cardiovascular diseases and related traits suggesting that traditional cardiovascular risk factor management may only have limited value in preventing the progression of aneurysmal disease.
  • Ade, Peter, et al. (författare)
  • The Simons Observatory : science goals and forecasts
  • 2019
  • Ingår i: Journal of Cosmology and Astroparticle Physics. - 1475-7516. ; :2
  • Tidskriftsartikel (refereegranskat)abstract
    • The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial con figuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping approximate to 10% of the sky to a white noise level of 2 mu K-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of sigma(r) = 0.003. The large aperture telescope will map approximate to 40% of the sky at arcminute angular resolution to an expected white noise level of 6 mu K-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources.
  • Akiyama, Kazunori, et al. (författare)
  • First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
  • 2019
  • Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 875:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at 1.3 mm wavelength. These images show a prominent ring with a diameter of similar to 40 mu as, consistent with the size and shape of the lensed photon orbit encircling the "shadow" of a supermassive black hole. The ring is persistent across four observing nights and shows enhanced brightness in the south. To assess the reliability of these results, we implemented a two-stage imaging procedure. In the first stage, four teams, each blind to the others' work, produced images of M87 using both an established method (CLEAN) and a newer technique (regularized maximum likelihood). This stage allowed us to avoid shared human bias and to assess common features among independent reconstructions. In the second stage, we reconstructed synthetic data from a large survey of imaging parameters and then compared the results with the corresponding ground truth images. This stage allowed us to select parameters objectively to use when reconstructing images of M87. Across all tests in both stages, the ring diameter and asymmetry remained stable, insensitive to the choice of imaging technique. We describe the EHT imaging procedures, the primary image features in M87, and the dependence of these features on imaging assumptions.
  • Akiyama, Kazunori, et al. (författare)
  • First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
  • 2019
  • Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 875:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The Event Horizon Telescope (EHT) has mapped the central compact radio source of the elliptical galaxy M87 at 1.3 mm with unprecedented angular resolution. Here we consider the physical implications of the asymmetric ring seen in the 2017 EHT data. To this end, we construct a large library of models based on general relativistic magnetohydrodynamic (GRMHD) simulations and synthetic images produced by general relativistic ray tracing. We compare the observed visibilities with this library and confirm that the asymmetric ring is consistent with earlier predictions of strong gravitational lensing of synchrotron emission from a hot plasma orbiting near the black hole event horizon. The ring radius and ring asymmetry depend on black hole mass and spin, respectively, and both are therefore expected to be stable when observed in future EHT campaigns. Overall, the observed image is consistent with expectations for the shadow of a spinning Kerr black hole as predicted by general relativity. If the black hole spin and M87's large scale jet are aligned, then the black hole spin vector is pointed away from Earth. Models in our library of non-spinning black holes are inconsistent with the observations as they do not produce sufficiently powerful jets. At the same time, in those models that produce a sufficiently powerful jet, the latter is powered by extraction of black hole spin energy through mechanisms akin to the Blandford-Znajek process. We briefly consider alternatives to a black hole for the central compact object. Analysis of existing EHT polarization data and data taken simultaneously at other wavelengths will soon enable new tests of the GRMHD models, as will future EHT campaigns at 230 and 345 GHz.
  • Akiyama, Kazunori, et al. (författare)
  • First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
  • 2019
  • Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 875:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using two independent sampling algorithms that consider distinct representations of the visibility data. We show that the crescent family of models is statistically preferred over other comparably complex geometric models that we explore. We calibrate the geometric model parameters using general relativistic magnetohydrodynamic (GRMHD) models of the emission region and estimate physical properties of the source. We further fit images generated from GRMHD models directly to the data. We compare the derived emission region and black hole parameters from these analyses with those recovered from reconstructed images. There is a remarkable consistency among all methods and data sets. We find that >50% of the total flux at arcsecond scales comes from near the horizon, and that the emission is dramatically suppressed interior to this region by a factor >10, providing direct evidence of the predicted shadow of a black hole. Across all methods, we measure a crescent diameter of 42 +/- 3 mu as and constrain its fractional width to be
  • Porth, Oliver, et al. (författare)
  • The Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project
  • 2019
  • Ingår i: Astrophysical Journal, Supplement Series. - 1538-4365 .- 0067-0049. ; 243:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent developments in compact object astrophysics, especially the discovery of merging neutron stars by LIGO, the imaging of the black hole in M87 by the Event Horizon Telescope, and high- precision astrometry of the Galactic Center at close to the event horizon scale by the GRAVITY experiment motivate the development of numerical source models that solve the equations of general relativistic magnetohydrodynamics (GRMHD). Here we compare GRMHD solutions for the evolution of a magnetized accretion flow where turbulence is promoted by the magnetorotational instability from a set of nine GRMHD codes: Athena++, BHAC, Cosmos++, ECHO, H-AMR, iharm3D, HARM-Noble, IllinoisGRMHD, and KORAL. Agreement among the codes improves as resolution increases, as measured by a consistently applied, specially developed set of code performance metrics. We conclude that the community of GRMHD codes is mature, capable, and consistent on these test problems.
Skapa referenser, mejla, bekava och länka
fritt online (27)
Typ av publikation
tidskriftsartikel (98)
forskningsöversikt (7)
annan publikation (3)
konferensbidrag (3)
bokkapitel (2)
Typ av innehåll
refereegranskat (97)
övrigt vetenskapligt (16)
populärvet., debatt m.m. (1)
Hughes, John P. (14)
Stawarz, Lukasz (13)
Axelsson, Magnus, (12)
Aharonian, Felix (12)
Akamatsu, Hiroki (12)
Akimoto, Fumie (12)
visa fler...
Allen, Steven W. (12)
Angelini, Lorella (12)
Audard, Marc (12)
Awaki, Hisamitsu (12)
Bamba, Aya (12)
Bautz, Marshall W. (12)
Blandford, Roger (12)
Brenneman, Laura W. (12)
Bulbul, Esra (12)
Cackett, Edward M. (12)
Chernyakova, Maria (12)
Chiao, Meng P. (12)
Coppi, Paolo S. (12)
Costantini, Elisa (12)
de Plaa, Jelle (12)
de Vries, Cor P. (12)
den Herder, Jan-Will ... (12)
Done, Chris (12)
Dotani, Tadayasu (12)
Ebisawa, Ken (12)
Eckart, Megan E. (12)
Enoto, Teruaki (12)
Ezoe, Yuichiro (12)
Fabian, Andrew C. (12)
Ferrigno, Carlo (12)
Foster, Adam R. (12)
Fujimoto, Ryuichi (12)
Fukazawa, Yasushi (12)
Furuzawa, Akihiro (12)
Galeazzi, Massimilia ... (12)
Gallo, Luigi C. (12)
Gandhi, Poshak (12)
Giustini, Margherita (12)
Goldwurm, Andrea (12)
Gu, Liyi (12)
Guainazzi, Matteo (12)
Haba, Yoshito (12)
Hagino, Kouichi (12)
Harrus, Ilana M. (12)
Hatsukade, Isamu (12)
Hayashi, Katsuhiro (12)
Hayashi, Takayuki (12)
Hayashida, Kiyoshi (12)
Hiraga, Junko S. (12)
visa färre...
Uppsala universitet (35)
Lunds universitet (24)
Stockholms universitet (24)
Karolinska Institutet (16)
Umeå universitet (14)
Göteborgs universitet (11)
visa fler...
Chalmers tekniska högskola (10)
Linköpings universitet (8)
Gymnastik- och idrottshögskolan (4)
Mittuniversitetet (3)
Kungliga Tekniska Högskolan (1)
Örebro universitet (1)
Södertörns högskola (1)
RISE (1)
Högskolan Dalarna (1)
Naturhistoriska riksmuseet (1)
visa färre...
Engelska (110)
Forskningsämne (UKÄ/SCB)
Medicin och hälsovetenskap (66)
Naturvetenskap (42)
Teknik (4)
Samhällsvetenskap (1)
Humaniora (1)


pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy