| 1. |
- Smits, Mark M., et al.
(författare)
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Biliary effects of liraglutide and sitagliptin, a 12-week randomized placebo-controlled trial in type 2 diabetes patients
- 2016
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Ingår i: Diabetes, Obesity and Metabolism. - : Wiley. - 1462-8902 .- 1463-1326. ; 18, s. 1217-1225
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Tidskriftsartikel (refereegranskat)abstract
- © 2016 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd. Aims: Treatment with glucagon-like peptide (GLP)-1 receptor agonists or dipeptidyl peptidase (DPP)-4 inhibitors might increase gallstone formation; however, the mechanisms involved are unknown. We aimed to assess the effects of these drugs on gallbladder volume and bile acid profile. Materials and methods: A total of 57 type 2 diabetes patients (mean ± SD age, 62.8 ± 6.9 years; BMI, 31.8 ± 4.1 kg/m2; HbA1c, 7.3% ± 0.6%), treated with metformin and/or sulfonylureas, were included in this 12-week randomized, placebo-controlled, double-blind, single-centre trial between July 2013 and August 2015 at the VU University Medical Center, the Netherlands. Patients received the GLP-1 receptor agonist liraglutide, the DPP-4 inhibitor sitagliptin or matching placebo for 12 weeks. Gallbladder fasting volume and ejection fraction were measured using ultrasonography after a high-fat meal. Serum bile acids were measured in the fasting and postprandial state and in faecal samples. The trial was registered at ClinicalTrials.gov (NCT01744236). Results: Neither liraglutide nor sitagliptin had an effect on gallbladder fasting volume and ejection fraction (p >.05). Liraglutide increased serum levels of deoxycholic acid in the fasting state [0.20 µmol/L (95% CI 0.027-0.376), p = 0.024] and postprandial state [AUC 40.71 (13.22-68.21), p = 0.005] and in faeces [ratio 1.5 (1.03-2.19); p = 0.035]. Sitagliptin had no effect on serum bile acids, but increased faecal levels of chenodeoxycholic acid [ratio 3.42 (1.33-8.79), p = 0.012], cholic acid [ratio 3.32 (1.26-8.87), p = 0.017] and ursodeoxycholic acid [ratio 3.81 (1.44-10.14), p = 0.008]. Conclusions: Neither liraglutide nor sitagliptin has an effect on gallbladder volume. Observed changes in bile acids with liraglutide suggest alterations in the intestinal microbiome, while sitagliptin appears to increase hepatic bile acid production.
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| 2. |
- Adebahr, B., et al.
(författare)
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The Apertif science verification campaign: Characteristics of polarised radio sources
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 663
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Tidskriftsartikel (refereegranskat)abstract
- Context. The characteristics of the polarised radio sky are a key ingredient in constraining evolutionary models of magnetic fields in the Universe and their role in feedback processes. The origin of the polarised emission and the characteristics of the intergalactic medium on the line of sight can be investigated using large samples of polarised sources. Ancillary infrared (IR) and optical data can be used to study the nature of the emitting objects. Aims. We analyse five early science datasets from the APERture Tile in Focus (Apertif) phased array feed system to verify the polarisation capabilities of Apertif in view of future larger data releases. We aim to characterise the source population of the polarised sky in the L-Band using polarised source information in combination with IR and optical data. Methods. We use automatic routines to generate full field-of-view Q- and U-cubes and perform rotation measure (RM)-Synthesis, source finding, and cross-matching with published radio, optical, and IR data to generate polarised source catalogues. All sources were inspected individually by eye for verification of their IR and optical counterparts. Spectral energy distribution (SED)-fitting routines were used to determine photometric redshifts, star-formation rates, and galaxy masses. IR colour information was used to classify sources as active galactic nuclei (AGN) or star-forming-dominated and early- or late-type. Results. We surveyed an area of 56 deg2 and detected 1357 polarised source components in 1170 sources. The fraction of polarised sources is 10.57% with a median fractional polarisation of 4.70 ± 0.14%. We confirmed the reliability of the Apertif measurements by comparing them with polarised cross-identified NVSS sources. Average RMs of the individual fields lie within the error of the best Milky Way foreground measurements. All of our polarised sources were found to be dominated by AGN activity in the radio regime with most of them being radio-loud (79%) and of the Fanaroff-Riley (FR)II class (87%). The host galaxies of our polarised source sample are dominated by intermediate disc and star-forming disc galaxies. The contribution of star formation to the radio emission is on the order of a few percent for 10% of the polarised sources while for 90% it is completely dominated by the AGN. We do not see any change in fractional polarisation for different star-formation rates of the AGN host galaxies. Conclusions. The Apertif system is suitable for large-area high-sensitivity polarised sky surveys. The data products of the polarisation analysis pipeline can be used to investigate the Milky Way magnetic field on projected scales of several arcminutes as well as the origin of the polarised emission in AGN and the properties of their host galaxies.
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| 3. |
- Bilous, A. V., et al.
(författare)
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Dual-frequency single-pulse study of PSR B0950+08
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 658
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Tidskriftsartikel (refereegranskat)abstract
- PSR B0950+08 is a bright nonrecycled pulsar whose single-pulse fluence variability is reportedly large. Based on observations at two widely separated frequencies, 55 MHz (NenuFAR) and 1.4 GHz (Westerbork Synthesis Radio Telescope), we review the properties of these single pulses. We conclude that they are more similar to ordinary pulses of radio emission than to a special kind of short and bright giant pulses, observed from only a handful of pulsars. We argue that a temporal variation of the properties of the interstellar medium along the line of sight to this nearby pulsar, namely the fluctuating size of the decorrelation bandwidth of diffractive scintillation makes an important contribution to the observed single-pulse fluence variability. We further present interesting structures in the low-frequency single-pulse spectra that resemble the "sad trombones"seen in fast radio bursts (FRBs); although for PSR B0950+08 the upward frequency drift is also routinely present. We explain these spectral features with radius-to-frequency mapping, similar to the model developed by Wang et al. (2019, ApJ, 876, L15) for FRBs. Finally, we speculate that μs-scale fluence variability of the general pulsar population remains poorly known, and that its further study may bring important clues about the nature of FRBs.
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| 4. |
- Boersma, O. M., et al.
(författare)
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A search for radio emission from double-neutron star merger GW190425 using Apertif
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 650
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Tidskriftsartikel (refereegranskat)abstract
- Context Detection of the electromagnetic emission from coalescing binary neutron stars (BNS) is important for understanding the merger and afterglow. Aims. We present a search for a radio counterpart to the gravitational-wave (GW) source GW190425, a BNS merger, using Apertif on the Westerbork Synthesis Radio Telescope (WSRT). Methods We observed a field of high probability in the associated localisation region for three epochs at ΔTâ€., =â€., 68, 90, 109 d post merger. We identified all sources that exhibit flux variations consistent with the expected afterglow emission of GW190425. We also looked for possible transients. These are sources that are only present in one epoch. In addition, we quantified our ability to search for radio afterglows in the fourth and future observing runs of the GW detector network using Monte Carlo simulations. Results We found 25 afterglow candidates based on their variability. None of these could be associated with a possible host galaxy at the luminosity distance of GW190425. We also found 55 transient afterglow candidates that were only detected in one epoch. All of these candidates turned out to be image artefacts. In the fourth observing run, we predict that up to three afterglows will be detectable by Apertif. Conclusions While we did not find a source related to the afterglow emission of GW190425, the search validates our methods for future searches of radio afterglows.
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| 5. |
- Hoffland, Ellis, et al.
(författare)
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The role of fungi in weathering
- 2004
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Ingår i: Frontiers in Ecology and Environment. - 1540-9295 .- 1540-9309. ; 2:5, s. 258-264
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Tidskriftsartikel (refereegranskat)abstract
- No rock at the Earth’s surface escapes weathering. This process is the primary source of all the essential elements for organisms, except nitrogen and carbon. Since the onset of terrestrial life, weathering has been accelerated under the influence of biota. The study of biological weathering started at the end of the 19th century. Although the role of bacteria (Eubacteria, Archaea) has attracted a lot of interest, until recently the role of fungi has largely been neglected. More recently, however, fungal weathering has become an increasingly important focus of biogeochemical research.
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| 6. |
- Lakens, Daniel, et al.
(författare)
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Justify your alpha
- 2018
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Ingår i: Nature Human Behaviour. - : Nature Publishing Group. - 2397-3374. ; 2:3, s. 168-171
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Tidskriftsartikel (refereegranskat)abstract
- In response to recommendations to redefine statistical significance to P ≤ 0.005, we propose that researchers should transparently report and justify all choices they make when designing a study, including the alpha level.
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| 7. |
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| 8. |
- Minns, Sean, et al.
(författare)
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Immersive 3D exposure-based treatment for spider fear : A randomized controlled trial
- 2018
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Ingår i: Journal of Anxiety Disorders. - : Elsevier. - 0887-6185 .- 1873-7897. ; 58, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Stereoscopic 3D gives the viewer the same shape, size, perspective and depth they would experience viewing the real world and could mimic the perceptual threat cues present in real life. This is the first study to investigate whether an immersive stereoscopic 3D video exposure-based treatment would be effective in reducing fear of spiders. Participants with a fear of spiders (N = 77) watched two psychoeducational videos with facts about spiders and phobias. They were then randomized to a treatment condition that watched a single session of a stereoscopic 3D immersive video exposure-based treatment (six 5-min exposures) delivered through a virtual reality headset or a psychoeducation only control condition that watched a 30-min neutral video (2D documentary) presented on a computer monitor. Assessments of spider fear (Fear of Spiders Questionnaire [FSQ], Behavioral Approach Task [BAT], & subjective ratings of fear) were completed pre- and post-treatment. Consistent with prediction, the stereoscopic 3D video condition outperformed the control condition in reducing fear of spiders showing a large between-group effect size on the FSQ (Cohen's d = 0.85) and a medium between group effect size on the BAT (Cohen's d = 0.47). This provides initial support for stereoscopic 3D video in treating phobias.
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| 9. |
- Minns, Sean, et al.
(författare)
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Immersive 3D exposure-based treatment for spider fear : A randomized controlled trial
- 2019
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Ingår i: Journal of Anxiety Disorders. - : Elsevier BV. - 0887-6185 .- 1873-7897. ; 61, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- Stereoscopic 3D gives the viewer the same shape, size, perspective and depth they would experience viewing the real world and could mimic the perceptual threat cues present in real life. This is the first study to investigate whether an immersive stereoscopic 3D video exposure-based treatment would be effective in reducing fear of spiders. Participants with a fear of spiders (N = 77) watched two psychoeducational videos with facts about spiders and phobias. They were then randomized to a treatment condition that watched a single session of a stereoscopic 3D immersive video exposure-based treatment (six 5-minute exposures) delivered through a virtual reality headset or a psychoeducation only control condition that watched a 30-minute neutral video (2D documentary) presented on a computer monitor. Assessments of spider fear (Fear of Spiders Questionnaire [FSQ], Behavioral Approach Task [BAT], & subjective ratings of fear) were completed pre- and post-treatment. Consistent with prediction, the stereoscopic 3D video condition outperformed the control condition in reducing fear of spiders showing a large between-group change effect size on the FSQ (Cohen's d = 0.85) and a medium between-group effect size on the BAT (Cohen's d = 0.47). This provides initial support for stereoscopic 3D video in treating phobias.
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| 10. |
- Nicolás, César, et al.
(författare)
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The soil organic matter decomposition mechanisms in ectomycorrhizal fungi are tuned for liberating soil organic nitrogen
- 2018
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Ingår i: ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370.
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Tidskriftsartikel (refereegranskat)abstract
- Many trees form ectomycorrhizal symbiosis with fungi. During symbiosis, the tree roots supply sugar to the fungi in exchange for nitrogen, and this process is critical for the nitrogen and carbon cycles in forest ecosystems. However, the extents to which ectomycorrhizal fungi can liberate nitrogen and modify the soil organic matter and the mechanisms by which they do so remain unclear since they have lost many enzymes for litter decomposition that were present in their free-living, saprotrophic ancestors. Using time-series spectroscopy and transcriptomics, we examined the ability of two ectomycorrhizal fungi from two independently evolved ectomycorrhizal lineages to mobilize soil organic nitrogen. Both species oxidized the organic matter and accessed the organic nitrogen. The expression of those events was controlled by the availability of glucose and inorganic nitrogen. Despite those similarities, the decomposition mechanisms, including the type of genes involved as well as the patterns of their expression, differed markedly between the two species. Our results suggest that in agreement with their diverse evolutionary origins, ectomycorrhizal fungi use different decomposition mechanisms to access organic nitrogen entrapped in soil organic matter. The timing and magnitude of the expression of the decomposition activity can be controlled by the below-ground nitrogen quality and the above-ground carbon supply.
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