| 1. |
- Hudson, Lawrence N, et al.
(författare)
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The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
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Tidskriftsartikel (refereegranskat)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
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| 2. |
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| 3. |
- Barack, Leor, et al.
(författare)
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Black holes, gravitational waves and fundamental physics : a roadmap
- 2019
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Ingår i: Classical and quantum gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 36:14
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Forskningsöversikt (refereegranskat)abstract
- The grand challenges of contemporary fundamental physics dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics'.
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| 4. |
- Cedeno, Daniel Grings, et al.
(författare)
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An experimental study on smectites as nitrogen conveyors in subduction zones
- 2019
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Ingår i: Applied Clay Science. - : Elsevier. - 0169-1317 .- 1872-9053. ; 168, s. 409-420
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Tidskriftsartikel (refereegranskat)abstract
- We performed high pressure and high temperature (HPHT) experiments on NH4-doped montmorillonite (similar to 2 wt % of NH4) under pressures of 2.5, 4.0, and 7.7 GPa and temperatures from 200 to 700 degrees C. Each experiment was analyzed with XRD, FTIR, CHN elemental analysis, and SEM in order to determine the NH4-Smectite phase changes and their morphology, and the presence of ammonium in the runs. Our results show that smectite can easily transport nitrogen, speciated as ammonium (NH4+), incorporated into the smectite interlayer in mildly reducing environments to deeper levels in the Earth through cold thermal regime subduction zones. NH4-Smectite transforms into NH4-enriched micaceous phase (tobelite) through a NH4+-enriched interlayered I/S phase in relatively low pressures and temperatures (around 2.5 GPa and 500 degrees C). Tobelite is stable until more extreme conditions (7.7 GPa and 700 degrees C), together with lesser amounts of buddingtonite (an ammonium-bearing feldspar) kyanite, and garnet. Our experiments also show the effect of nitrogen in the feldspar stability, as potassic and sodic feldspar are stable up to similar to 5 GPa, while buddingtonite, is observed to be stable up to 7.7 GPa. Nitrogen can return to the surface once the stability of these nitrogen-enriched minerals is reached due to pressure or temperature increasing.
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| 5. |
- Issaoun, S., et al.
(författare)
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The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz: First VLBI with ALMA
- 2019
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 871:1
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Tidskriftsartikel (refereegranskat)abstract
- The Galactic center supermassive black hole Sagittarius A∗ (Sgr A∗) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm (86 GHz), the emission from Sgr A∗ is resolvable with the Global Millimeter VLBI Array (GMVA). We present the first observations of Sgr A∗ with the phased Atacama Large Millimeter/submillimeter Array (ALMA) joining the GMVA. Our observations achieve an angular resolution of ∼87 μas, improving upon previous experiments by a factor of two. We reconstruct a first image of the unscattered source structure of Sgr A∗ at 3.5 mm, mitigating the effects of interstellar scattering. The unscattered source has a major-axis size of 120 ±34 μas (12 ±3.4 Schwarzschild radii) and a symmetrical morphology (axial ratio of ), which is further supported by closure phases consistent with zero within 3σ. We show that multiple disk-dominated models of Sgr A∗ match our observational constraints, while the two jet-dominated models considered are constrained to small viewing angles. Our long-baseline detections to ALMA also provide new constraints on the scattering of Sgr A∗, and we show that refractive scattering effects are likely to be weak for images of Sgr A∗ at 1.3 mm with the Event Horizon Telescope. Our results provide the most stringent constraints to date for the intrinsic morphology and refractive scattering of Sgr A∗, demonstrating the exceptional contribution of ALMA to millimeter VLBI.
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| 6. |
- Kim, J. Y., et al.
(författare)
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Spatially resolved origin of millimeter-wave linear polarization in the nuclear region of 3C 84
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 622
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Tidskriftsartikel (refereegranskat)abstract
- We report results from a deep polarization imaging of the nearby radio galaxy 3C 84 (NGC 1275). The source was observed with the Global Millimeter VLBI Array (GMVA) at 86 GHz at an ultrahigh angular resolution of 50 μas (corresponding to ∼200Rs). We also add complementary multiwavelength data from the Very Long Baseline Array (VLBA; 15 and 43 GHz) and from the Atacama Large Millimeter/submillimeter Array (ALMA; 97.5, 233.0 and 343.5 GHz). At 86 GHz, we measured a fractional linear polarization of ∼2% in the VLBI core region. The polarization morphology suggests that the emission is associated with an underlying limb-brightened jet. The fractional linear polarization is lower at 43 and 15 GHz (∼0.3-0.7% and <0.1%, respectively). This suggests an increasing linear polarization degree toward shorter wavelengths on VLBI scales. We also obtain a large rotation measure (RM) of ∼10 5-6 rad m 2 in the core at 43 GHz. Moreover, the VLBA 43 GHz observations show a variable RM in the VLBI core region during a small flare in 2015. Faraday depolarization and Faraday conversion in an inhomogeneous and mildly relativistic plasma could explain the observed linear polarization characteristics and the previously measured frequency dependence of the circular polarization. Our Faraday depolarization modeling suggests that the RM most likely originates from an external screen with a highly uniform RM distribution. To explain the large RM value, the uniform RM distribution and the RM variability, we suggest that the Faraday rotation is caused by a boundary layer in a transversely stratified jet. Based on the RM and the synchrotron spectrum of the core, we provide an estimate for the magnetic field strength and the electron density of the jet plasma.
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| 7. |
- Kim, J. Y., et al.
(författare)
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The limb-brightened jet of M87 down to the 7 Schwarzschild radii scale
- 2018
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 616
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Tidskriftsartikel (refereegranskat)abstract
- Messier 87 (M 87) is one of the nearest radio galaxies with a prominent jet extending from sub-pc to kpc scales. Because of its proximity and the large mass of its central black hole (BH), it is one of the best radio sources for the study of jet formation. We study the physical conditions near the jet base at projected separations from the BH of ∼7-100 Schwarzschild radii (Rsch). Global mm-VLBI Array (GMVA) observations at 86 GHz (λ = 3.5 mm) provide an angular resolution of ∼50 μas, which corresponds to a spatial resolution of only 7 Rschand reach the small spatial scale. We use five GMVA data sets of M 87 obtained from 2004 to 2015 and present new high angular resolution VLBI maps at 86 GHz. In particular, we focus on the analysis of the brightness temperature, the jet ridge lines, and the ratio of jet to counter-jet. The imaging reveals a parabolically expanding limb-brightened jet which emanates from a resolved VLBI core of ∼(8-13) Rschin size. The observed brightness temperature of the core at any epoch is ∼(1-3) × 1010K, which is below the equipartition brightness temperature and suggests magnetic energy dominance at the jet base. We estimate the diameter of the jet at its base to be ∼5 Rschassuming a self-similar jet structure. This suggests that the sheath of the jet may be anchored in the very inner portion of the accretion disk. The image stacking reveals faint emission at the center of the edge-brightened jet on sub-pc scales. We discuss its physical implication within the context of the spine-sheath structure of the jet.
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| 8. |
- Langefeld, Carl D., et al.
(författare)
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Transancestral mapping and genetic load in systemic lupus erythematosus
- 2017
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Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Systemic lupus erythematosus (SLE) is an autoimmune disease with marked gender and ethnic disparities. We report a large transancestral association study of SLE using Immunochip genotype data from 27,574 individuals of European (EA), African (AA) and Hispanic Amerindian (HA) ancestry. We identify 58 distinct non-HLA regions in EA, 9 in AA and 16 in HA (similar to 50% of these regions have multiple independent associations); these include 24 novel SLE regions (P < 5 x 10(-8)), refined association signals in established regions, extended associations to additional ancestries, and a disentangled complex HLA multigenic effect. The risk allele count (genetic load) exhibits an accelerating pattern of SLE risk, leading us to posit a cumulative hit hypothesis for autoimmune disease. Comparing results across the three ancestries identifies both ancestry-dependent and ancestry-independent contributions to SLE risk. Our results are consistent with the unique and complex histories of the populations sampled, and collectively help clarify the genetic architecture and ethnic disparities in SLE.
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| 9. |
- Morales Salinas, Alberto, et al.
(författare)
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Clinical Perspective on Antihypertensive Drug Treatment in Adults With Grade 1 Hypertension and Low-to-Moderate Cardiovascular Risk : An International Expert Consultation
- 2017
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Ingår i: Current problems in cardiology. - : Elsevier. - 0146-2806 .- 1535-6280. ; 42:7, s. 198-225
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Forskningsöversikt (refereegranskat)abstract
- Hypertension is a leading risk factor for disease burden globally. An unresolved question is whether grade 1 hypertension (140-159/90-99 mm Hg) with low (cardiovascular mortality < 1% at 10 years) to moderate (cardiovascular mortality ≥ 1% and <5% at 10 years) absolute total cardiovascular risk (CVR) should be treated with antihypertensive agents. A virtual international consultation process was undertaken to summarize the opinions of select experts. After holistic analysis of all epidemiological, clinical, psychosocial, and public health elements, this consultation process reached the following consensus in hypertensive adults aged < 80 years: (1) The question of whether drug treatment in grade 1 should be preceded by a period of some weeks or months during which only lifestyle measures are recommended cannot be evidence based, but the consensus opinion is to have a period of lifestyle alone reserved only to patients with grade 1 "isolated" hypertension (grade 1 uncomplicated hypertension with low absolute total CVR, and without other major CVR factors and risk modifiers). (2) The initiation of antihypertensive drug therapy in grade 1 hypertension with moderate absolute total CVR should not be delayed. (3) Men ≥ 55 years and women ≥ 60 years with uncomplicated grade 1 hypertension should automatically be classified within the moderate absolute total CVR category, even in the absence of other major CVR factors and risk modifiers. (4) Statins should be considered along with blood-pressure lowering therapy, irrespective of cholesterol levels, in patients with grade 1 hypertensive with moderate CVR.
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| 10. |
- Nair, Dhanya G., et al.
(författare)
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Global millimeter VLBI array survey of ultracompact extragalactic radio sources at 86 GHz
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 622
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Forskningsöversikt (refereegranskat)abstract
- Context. Very long baseline interferometry (VLBI) observations at 86 GHz (wavelength, λ = 3 mm) reach a resolution of about 50 μas, probing the collimation and acceleration regions of relativistic outflows in active galactic nuclei (AGN). The physical conditions in these regions can be studied by performing 86 GHz VLBI surveys of representative samples of compact extragalactic radio sources. Aims. To extend the statistical studies of compact extragalactic jets, a large global 86 GHz VLBI survey of 162 compact radio sources was conducted in 2010-2011 using the Global Millimeter VLBI Array (GMVA). Methods. The survey observations were made in a snapshot mode, with up to five scans per target spread over a range of hour angles in order to optimize the visibility coverage. The survey data attained a typical baseline sensitivity of 0.1 Jy and a typical image sensitivity of 5 mJy beam-1, providing successful detections and images for all of the survey targets. For 138 objects, the survey provides the first ever VLBI images made at 86 GHz. Gaussian model fitting of the visibility data was applied to represent the structure of the observed sources and to estimate the flux densities and sizes of distinct emitting regions (components) in their jets. These estimates were used for calculating the brightness temperature (Tb) at the jet base (core) and in one or more moving regions (jet components) downstream from the core. These model-fit-based estimates of Tb were compared to the estimates of brightness temperature limits made directly from the visibility data, demonstrating a good agreement between the two methods. Results. The apparent brightness temperature estimates for the jet cores in our sample range from 2.5 × 109 K to 1.3 × 1012 K, with the mean value of 1.8 × 1011 K. The apparent brightness temperature estimates for the inner jet components in our sample range from 7.0 × 107 K to 4.0 × 1011 K. A simple population model with a single intrinsic value of brightness temperature, T0, is applied to reproduce the observed distribution. It yields T0 = (3.77-0.14+0.10) × 1011 K for the jet cores, implying that the inverse Compton losses dominate the emission. In the nearest jet components, T0 = (1.42-0.19+0.16) × 1011 K is found, which is slightly higher than the equipartition limit of ∼5 × 1010 K expected for these jet regions. For objects with sufficient structural detail detected, the adiabatic energy losses are shown to dominate the observed changes of brightness temperature along the jet.
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