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Sökning: WFRF:(Holwerda B. W.)

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1.
  • Poyatos, R., et al. (författare)
  • Global transpiration data from sap flow measurements: the SAPFLUXNET database
  • 2021
  • Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 13:6, s. 2607-2649
  • Tidskriftsartikel (refereegranskat)abstract
    • Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.
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2.
  • de Blok, W.J.G., et al. (författare)
  • an overview of the MHONGOOSE survey: Observing nearby galaxies with MeerKAT
  • 2016
  • Ingår i: Proceedings of Science. - 1824-8039.
  • Konferensbidrag (refereegranskat)abstract
    • MHONGOOSE is a deep survey of the neutral hydrogen distribution in a representative sample of 30 nearby disk and dwarf galaxies with H I masses from ∼ 106 to ∼ 1011 M, and luminosities from MR ∼ 12 to MR ∼ −22. The sample is selected to uniformly cover the available range in log(MHI). Our extremely deep observations, down to H I column density limits of well below 1018 cm−2 — or a few hundred times fainter than the typical H I disks in galaxies — will directly detect the effects of cold accretion from the intergalactic medium and the links with the cosmic web. These observations will be the first ever to probe the very low-column density neutral gas in galaxies at these high resolutions. Combination with data at other wavelengths, most of it already available, will enable accurate modeling of the properties and evolution of the mass components in these galaxies and link these with the effects of environment, dark matter distribution, and other fundamental properties such as halo mass and angular momentum. MHONGOOSE can already start addressing some of the SKA-1 science goals and will provide a comprehensive inventory of the processes driving the transformation and evolution of galaxies in the nearby universe at high resolution and over 5 orders of magnitude in column density. It will be a Nearby Galaxies Legacy Survey that will be unsurpassed until the advent of the SKA, and can serve as a highly visible, lasting statement of MeerKAT’s capabilities.
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3.
  • Underwood, J, et al. (författare)
  • Validation of a Novel Multivariate Method of Defining HIV-Associated Cognitive Impairment
  • 2019
  • Ingår i: Open forum infectious diseases. - : Oxford University Press (OUP). - 2328-8957. ; 6:6, s. ofz198-
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundThe optimum method of defining cognitive impairment in virally suppressed people living with HIV is unknown. We evaluated the relationships between cognitive impairment, including using a novel multivariate method (NMM), patient– reported outcome measures (PROMs), and neuroimaging markers of brain structure across 3 cohorts.MethodsDifferences in the prevalence of cognitive impairment, PROMs, and neuroimaging data from the COBRA, CHARTER, and POPPY cohorts (total n = 908) were determined between HIV-positive participants with and without cognitive impairment defined using the HIV-associated neurocognitive disorders (HAND), global deficit score (GDS), and NMM criteria.ResultsThe prevalence of cognitive impairment varied by up to 27% between methods used to define impairment (eg, 48% for HAND vs 21% for NMM in the CHARTER study). Associations between objective cognitive impairment and subjective cognitive complaints generally were weak. Physical and mental health summary scores (SF-36) were lowest for NMM-defined impairment (P < .05).There were no differences in brain volumes or cortical thickness between participants with and without cognitive impairment defined using the HAND and GDS measures. In contrast, those identified with cognitive impairment by the NMM had reduced mean cortical thickness in both hemispheres (P < .05), as well as smaller brain volumes (P < .01). The associations with measures of white matter microstructure and brain-predicted age generally were weaker.ConclusionDifferent methods of defining cognitive impairment identify different people with varying symptomatology and measures of brain injury. Overall, NMM-defined impairment was associated with most neuroimaging abnormalities and poorer self-reported health status. This may be due to the statistical advantage of using a multivariate approach.
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4.
  • Windhorst, Rogier A., et al. (författare)
  • JWST PEARLS. Prime extragalactic areas for reionization and lensing science : project overview and first results
  • 2023
  • Ingår i: Astronomical Journal. - : Institute of Physics (IOP). - 0004-6256 .- 1538-3881. ; 165:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST “Prime Extragalactic Areas for Reionization and Lensing Science” (PEARLS) project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift protoclusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, active galactic nucleus (AGN) growth, and First Light. Five fields—the JWST NEP Time-Domain Field (TDF), IRAC Dark Field, and three lensing clusters—will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9–4.5 μm galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9–4.5 μm. PEARLS is designed to be of lasting benefit to the community.
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5.
  • Lee, Bumhyun, et al. (författare)
  • The Impact of the Group Environment on the Molecular Gas and Star Formation Activity
  • 2021
  • Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 17, s. 136-139
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • At least half of the local galaxies reside in galaxy groups, which indicates that the group is the common environment where galaxies evolve. Therefore, it is important to probe how significantly galaxies are affected by group environmental processes, in order to obtain a better understanding of galaxy evolution. We carried out a new CO imaging survey for 31 galaxies in the IC 1459 and NGC 4636 groups, using the Atacama Compact Array, to study the effect of the group environment on the molecular gas properties and the star formation activity. With our resolved CO data, combined with high-resolution H i images, we find asymmetric CO and H i distributions in the group galaxies. Compared to isolated galaxies, group members have relatively low molecular gas fraction and low star formation rate. These results suggest that the group environment can change the properties of cold gas components and star formation in group galaxies.
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7.
  • Braam, A. W., et al. (författare)
  • Depression, subthreshold depression and comorbid anxiety symptoms in older Europeans: Results from the EURODEP concerted action
  • 2014
  • Ingår i: Journal of Affective Disorders. - : Elsevier BV. - 0165-0327. ; 155, s. 266-272
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: In the epidemiology of late life depression, few insights are available on the co-occurrence of subthreshold depression and comorbicl symptoms of anxiety. The current study aims to describe prevalence patterns of comorbid anxiety symptoms across different levels of depression in old age, and to describe the burden of depressive symptoms and functional disability across patterns of comorbidity. Methods: Respondents were older adults in the community, age 65-104 (N=14,200), from seven European countries, with in total nine study centres, collaborating in the EURODEP concerted action. Depression and anxiety were assessed using the Geriatric Mental State examination (GMS-AGECAT package), providing subthreshold level and case level diagnoses. Presence of anxiety symptoms was defined as at least three distinct symptoms of anxiety. Number of depressive symptoms was assessed with the EURO-D scale. Results: The prevalence of anxiety symptoms amounts to 32% for respondents without depression, 67% for those with subthreshold depression, and 87% for those with case level depression. The number of depressive symptoms is similar for those with subthreshold level depression with cornorbid anxiety, compared to case level depression without symptoms of anxiety. In turn, at case level, comorbid symptoms of anxiety are associated with higher levels of depressive symptoms and more functional disability. Limitations: GMS-AGECAT is insufficiently cciuipped with diagnostic procedures to identify specific types of anxiety disorders. conclusions: Anxiety symptoms in late life depression are highly prevalent, and are likely to contribute to the burden of symptoms of the depression, even at subthreshold level. (C) 2013 Elsevier By. All rights reserved.
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