| 1. |
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| 2. |
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| 3. |
- Cernicharo, J., et al.
(författare)
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Detection of anhydrous hydrochloric acid, HCl, in IRC+10216 with the Herschel SPIRE and PACS spectrometers Detection of HCI in IRC+10216
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L136-
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Tidskriftsartikel (refereegranskat)abstract
- We report on the detection of anhydrous hydrochloric acid (hydrogen chlorine, HCl) in the carbon-rich star IRC+10216 using the spectroscopic facilities onboard the Herschel satellite. Lines from J = 1-0 up to J = 7-6 have been detected. From the observed intensities, we conclude that HCl is produced in the innermost layers of the circumstellar envelope with an abundance relative to H-2 of 5 x 10(-8) and extends until the molecules reach its photodissociation zone. Upper limits to the column densities of AlH, MgH, CaH, CuH, KH, NaH, FeH, and other diatomic hydrides have also been obtained.
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| 4. |
- Decin, L., et al.
(författare)
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Silicon in the dust formation zone of IRC+10216
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L143-
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Tidskriftsartikel (refereegranskat)abstract
- The interstellar medium is enriched primarily by matter ejected from evolved low and intermediate mass stars. The outflows from these stars create a circumstellar envelope in which a rich gas-phase and dust-nucleation chemistry takes place. We observed the nearest carbon-rich evolved star, IRC + 10216, using the PACS (55-210 mu m) and SPIRE (194-672 mu m) spectrometers on board Herschel. We find several tens of lines from SiS and SiO, including lines from the v = 1 vibrational level. For SiS these transitions range up to J = 124-123, corresponding to energies around 6700 K, while the highest detectable transition is J = 90-89 for SiO, which corresponds to an energy around 8400 K. Both species trace the dust formation zone of IRC + 10216, and the broad energy ranges involved in their detected transitions permit us to derive the physical properties of the gas and the particular zone in which each species has been formed. This allows us to check the accuracy of chemical thermodynamical equilibrium models and the suggested depletion of SiS and SiO due to accretion onto dust grains.
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| 5. |
- Decin, L., et al.
(författare)
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Warm water vapour in the sooty outflow from a luminous carbon star
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 467:7311, s. 64-67
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Tidskriftsartikel (refereegranskat)abstract
- The detection(1) of circumstellar water vapour around the ageing carbon star IRC + 10216 challenged the current understanding of chemistry in old stars, because water was predicted(2) to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit around the star(1), grain surface reactions(3), and photochemistry in the outer circumstellar envelope(4). With a single water line detected so far from this one carbon-rich evolved star, it is difficult to discriminate between the different mechanisms proposed. Here we report the detection of dozens of water vapour lines in the far-infrared and sub-millimetre spectrum of IRC + 10216 using the Herschel satellite(5). This includes some high-excitation lines with energies corresponding to similar to 1,000 K, which can be explained only if water is present in the warm inner sooty region of the envelope. A plausible explanation for the warm water appears to be the penetration of ultraviolet photons deep into a clumpy circumstellar envelope. This mechanism also triggers the formation of other molecules, such as ammonia, whose observed abundances(6) are much higher than hitherto predicted(7).
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| 6. |
- Ladjal, D., et al.
(författare)
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Herschel PACS and SPIRE imaging of CW Leonis
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L141-
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Tidskriftsartikel (refereegranskat)abstract
- Herschel PACS and SPIRE images have been obtained over a 30' x 30' area around the well-known carbon star CW Leo (IRC + 10 216). An extended structure is found in an incomplete arc of similar to 22' diameter, which is cospatial with the termination shock due to interaction with the interstellar medium (ISM) as defined by Sahai & Chronopoulos from ultraviolet GALEX images. Fluxes are derived in the 70, 160, 250, 350, and 550 mu m bands in the region where the interaction with the ISM takes place, and this can be fitted with a modified black body with a temperature of 25 +/- 3 K. Using the published proper motion and radial velocity for the star, we derive a heliocentric space motion of 25.1 km s(-1). Using the PACS and SPIRE data and the analytical formula of the bow shock structure, we infer a de-projected standoff distance of the bow shock of R-0 = (8.0 +/- 0.3) x 10(17) cm. We also derive a relative velocity of the star with respect to the ISM of (106.6 +/- 8.7)/ root n(ISM) km s (1), where n(ISM) is the number density of the local ISM.
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| 7. |
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| 8. |
- van Dessel, L., et al.
(författare)
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Pulmonary Hemodynamics and Outcome in a Large Cohort of Patients with Sinus Venosus Septal Defect
- 2020
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Ingår i: Congenital Heart Disease. - : Computers, Materials and Continua (Tech Science Press). - 1747-079X. ; 15:2, s. 69-78
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Tidskriftsartikel (refereegranskat)abstract
- Background: Left-to-right shunt in sinus venosus septal defect (SVSD) may affect resistive (pulmonary vascular resistance-PVR) and elastic (pulmonary artery compliance-PAC) pulmonary artery properties. This study aimed at evaluating (1) impact of age, (2) pulmonary hemodynamics, and (3) outcome in a large cohort of SVSD patients. Methods: This study included 136 patients with SVSD (median age at diagnosis 14 (IQR 5-48) years, 47% male) of which 87 underwent catheterization. Pressures were measured and cardiac output was evaluated using the Fick principle at diagnosis. PVR, PAC and their product (RC time) were calculated. Results: Surgical repair was performed in 128 (94%) at a median age of 13 (IQR 5- 43) years. During a median follow-up time of 31 (IQR 17-55) years, 12 (9%) patients died, 13 (10%) developed heart failure, 4 (3%) Eisenmenger syndrome, 19 (14%) atrial arrhythmia, 6 (4%) sick sinus syndrome and 7 (5%) required pacemaker implantation In those who underwent catheterization, median shunt ratio was 2.5 (IQR 2.0-2.9). Thirty (34%) had mean PA pressure >= 25 mmHg. PVR indexed, PAC indexed, and RC time was 3.5 (IQR 2.4-7.5) WU.m(2) , 1.8 (IQR 1.3-2.5) mL/mmHg.m(2) and 0.39 (0.26-0.53) sec with an inverse hyperbolic relationship between PVR and PAC. Mean PA pressure (P < 0.0001); wedge pressure (P = 0.001), PVR indexed (P = 0.002) and PAC indexed (P = 0.002) changed significantly with age at diagnosis, but shunt ratio did not. Conclusion: SVSD has good long-term outcome, albeit with late morbidities. Thirty-four percent has mean PA pressure >= 25 mmHg, but Eisenmenger syndrome is rare (3%). PVR and PAC are inversely related and change significantly with older age.
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| 9. |
- van Hoof, P. A. M., et al.
(författare)
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Herschel images of NGC 6720 : H-2 formation on dust grains
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L137-
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Tidskriftsartikel (refereegranskat)abstract
- Herschel PACS and SPIRE images have been obtained of NGC 6720 (the Ring nebula). This is an evolved planetary nebula with a central star that is currently on the cooling track, due to which the outer parts of the nebula are recombining. From the PACS and SPIRE images we conclude that there is a striking resemblance between the dust distribution and the H-2 emission, which appears to be observational evidence that H-2 forms on grain surfaces. We have developed a photoionization model of the nebula with the Cloudy code which we used to determine the physical conditions of the dust and investigate possible formation scenarios for the H-2. We conclude that the most plausible scenario is that the H-2 resides in high density knots which were formed after the recombination of the gas started when the central star entered the cooling track. Hydrodynamical instabilities due to the unusually low temperature of the recombining gas are proposed as a mechanism for forming the knots. H-2 formation in the knots is expected to be substantial after the central star underwent a strong drop in luminosity about one to two thousand years ago, and may still be ongoing at this moment, depending on the density of the knots and the properties of the grains in the knots.
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| 10. |
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| 11. |
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| 12. |
- Lewandowska, A. M., et al.
(författare)
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The influence of balanced and imbalanced resource supply on biodiversity-functioning relationship across ecosystems
- 2016
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Ingår i: Philosophical Transactions of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 371:1694
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity ecosystern functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common pattems and differences in biodiversity functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity.
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| 13. |
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| 14. |
- Royer, P., et al.
(författare)
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PACS and SPIRE spectroscopy of the red supergiant VY CMa
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L145-
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Tidskriftsartikel (refereegranskat)abstract
- With a luminosity > 10(5) L-circle dot and a mass-loss rate of similar to 2 x 10(-4) M-circle dot yr(-1), the red supergiant VY CMa truly is a spectacular object. Because of its extreme evolutionary state, it could explode as supernova any time. Studying its circumstellar material, into which the supernova blast will run, provides interesting constraints on supernova explosions and on the rich chemistry taking place in such complex circumstellar envelopes. We have obtained spectroscopy of VY CMa over the full wavelength range offered by the PACS and SPIRE instruments of Herschel, i.e. 55-672 micron. The observations show the spectral fingerprints of more than 900 spectral lines, of which more than half belong to water. In total, we have identified 13 different molecules and some of their isotopologues. A first analysis shows that water is abundantly present, with an ortho-to-para ratio as low as similar to 1.3:1, and that chemical non-equilibrium processes determine the abundance fractions in the inner envelope.
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| 15. |
- Sibthorpe, B., et al.
(författare)
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The Vega debris disc: A view from Herschel
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L130
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Tidskriftsartikel (refereegranskat)abstract
- We present five band imaging of the Vega debris disc obtained using the Herschel Space Observatory. These data span a wavelength range of 70-500 mu m with full-width half-maximum angular resolutions of 5.6-36.9 ''. The disc is well resolved in all bands, with the ring structure visible at 70 and 160 mu m. Radial profiles of the disc surface brightness are produced, and a disc radius of 11 '' (similar to 85AU) is determined. The disc is seen to have a smooth structure thoughout the entire wavelength range, suggesting that the disc is in a steady state, rather than being an ephemeral structure caused by the recent collision of two large planetesimals.
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| 16. |
- Vandenbussche, B., et al.
(författare)
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The beta Pictoris disk imaged by Herschel PACS and SPIRE
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L133
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Tidskriftsartikel (refereegranskat)abstract
- We obtained Herschel PACS and SPIRE images of the thermal emission of the debris disk around the A5V star beta Pic. The disk is well resolved in the PACS filters at 70, 100, and 160 mu m. The surface brightness profiles between 70 and 160 mu m show no significant asymmetries along the disk, and are compatible with 90% of the emission between 70 and 160 mu m originating in a region closer than 200 AU to the star. Although only marginally resolving the debris disk, the maps obtained in the SPIRE 250-500 mu m filters provide full-disk photometry, completing the SED over a few octaves in wavelength that had been previously inaccessible. The small far-infrared spectral index (beta = 0.34) indicates that the grain size distribution in the inner disk (
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| 17. |
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| 18. |
- Daene, M, et al.
(författare)
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Outcome of Down patients with repaired versus unrepaired atrioventricular septal defect
- 2023
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Ingår i: International Journal of Cardiology Congenital Heart Disease. - : Elsevier BV. - 2666-6685. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims Patients with Down Syndrome (DS) are frequently born with an atrioventricular septal defect (AVSD). Surgical repair of the defect aims to minimize mortality and morbidity. However, a surgical intervention, specifically in DS patients, is not without risk and a subgroup of patients underwent only conservative non-surgical treatment. Outcome data of these different approaches are scarce. The aim of this retrospective study was to compare the long-term outcome of DS patients with and without surgery for AVSD. Methods DS patients registered with AVSD in the hospital's database from January 1980 till December 2020 were selected. Patient characteristics, peri-operative if appropriate, and follow-up data were obtained from the medical files. Results In total, 72 unrepaired (36 male, 50%) and 134 repaired patients (61 male, 46%) were included. After a maximum of 60 years of follow-up, the all-cause mortality was 45.8% and 17.1%, respectively. Thirty-six percent and 13%, respectively, were labeled as non-cardiovascular death. Mean survival time for unrepaired AVSD was 40.7 years (95% CI 36.1–45.2) and for repaired AVSD 38.5 years (95% CI 35.3–41.6) (Log rank p = 0.465). However, the survival rate 35 years after birth was 62.1% for unrepaired patients versus 81.7% for repaired patients. Mortality rates were the highest the first months after surgical repair. Conclusions The mean survival rate of Down patients, born with an AVSD, did not differ between repair or not. However, long-term survival rate was higher in patients who underwent surgical repair. Mortality was highest the first months after surgery.
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| 19. |
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| 20. |
- Stroud, J.T., et al.
(författare)
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Priority effects transcend scales and disciplines in biology
- 2024
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Ingår i: Trends in Ecology & Evolution. - : Elsevier. - 0169-5347 .- 1872-8383.
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Forskningsöversikt (refereegranskat)abstract
- Although primarily studied through the lens of community ecology, phenomena consistent with priority effects appear to be widespread across many different scenarios spanning a broad range of spatial, temporal, and biological scales. However, communication between these research fields is inconsistent and has resulted in a fragmented co-citation landscape, likely due to the diversity of terms used to refer to priority effects across these fields. We review these related terms, and the biological contexts in which they are used, to facilitate greater cross-disciplinary cohesion in research on priority effects. In breaking down these semantic barriers, we aim to provide a framework to better understand the conditions and mechanisms of priority effects, and their consequences across spatial and temporal scales.
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| 21. |
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| 22. |
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| 23. |
- Acke, B., et al.
(författare)
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Herschel images of Fomalhaut An extrasolar Kuiper belt at the height of its dynamical activity
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 540, s. Article Number: A125 -
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Tidskriftsartikel (refereegranskat)abstract
- Context. Fomalhaut is a young (2 +/- 1 x 10(8) years), nearby (7.7 pc), 2 M-circle dot star that is suspected to harbor an infant planetary system, interspersed with one or more belts of dusty debris. Aims. We present far-infrared images obtained with the Herschel Space Observatory with an angular resolution between 5.7 '' and 36.7 '' at wavelengths between 70 mu m and 500 mu m. The images show the main debris belt in great detail. Even at high spatial resolution, the belt appears smooth. The region in between the belt and the central star is not devoid of material; thermal emission is observed here as well. Also at the location of the star, excess emission is detected. We aim to construct a consistent image of the Fomalhaut system. Methods. We use a dynamical model together with radiative-transfer tools to derive the parameters of the debris disk. We include detailed models of the interaction of the dust grains with radiation, for both the radiation pressure and the temperature determination. Comparing these models to the spatially resolved temperature information contained in the images allows us to place strong constraints on the presence of grains that will be blown out of the system by radiation pressure. We use this to derive the dynamical parameters of the system. Results. The appearance of the belt points toward a remarkably active system in which dust grains are produced at a very high rate by a collisional cascade in a narrow region filled with dynamically excited planetesimals. Dust particles with sizes below the blow-out size are abundantly present. The equivalent of 2000 one-km-sized comets are destroyed every day, out of a cometary reservoir amounting to 110 Earth masses. From comparison of their scattering and thermal properties, we find evidence that the dust grains are fluffy aggregates, which indicates a cometary origin. The excess emission at the location of the star may be produced by hot dust with a range of temperatures, but may also be due to gaseous free-free emission from a stellar wind.
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| 24. |
- Cuenca-Cambronero, M., et al.
(författare)
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Challenges and opportunities in the use of ponds and pondscapes as Nature-based Solutions
- 2023
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Ingår i: Hydrobiologia. - : Springer Nature. - 0018-8158 .- 1573-5117. ; 850:15, s. 3257-3271
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Tidskriftsartikel (refereegranskat)abstract
- Ponds and "pondscapes" (networks of ponds) are crucial habitats for biodiversity and for delivering multiple benefits to humans, so-called "Nature's Contribution to People", such as climate mitigation and adaptation to climate change, creation, and maintenance of habitat for biodiversity, water purification, flood mitigation and cultural benefits (e.g., recreational possibilities). However, ponds are not often considered as Nature-based Solutions to provide all these benefits. In addition, there is insufficient knowledge on how to manage and restore ponds to maximise their role to increase the resilience of ecosystems and society to climate change. To facilitate improved implementation of ponds as Nature-based Solutions for the delivery of a wide range of Nature Contributions to People, it is important to generate and integrate biodiversity, ecosystems, societal, economic and policy knowledge. Hence, there is a need for evidence-based guidance to support the broader use of ponds. Here, we review the role of ponds and pondscapes in delivering Nature's Contributions to People and provide an overview of the challenges and opportunities for their broader implementation as Nature-based Solutions. Finally, we propose a conceptual framework that can help the implementation of pond Nature-based Solutions, and that outlines future research needs.
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| 25. |
- Guzman, Laura Melissa, et al.
(författare)
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Accounting for temporal change in multiple biodiversity patterns improves the inference of metacommunity processes
- 2022
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Ingår i: Ecology. - : John Wiley & Sons. - 0012-9658 .- 1939-9170. ; 103:6
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Tidskriftsartikel (refereegranskat)abstract
- In metacommunity ecology, a major focus has been on combining observational and analytical approaches to identify the role of critical assembly processes, such as dispersal limitation and environmental filtering, but this work has largely ignored temporal community dynamics. Here, we develop a "virtual ecologist" approach to evaluate assembly processes by simulating metacommunities varying in three main processes: density-independent responses to abiotic conditions, density-dependent biotic interactions, and dispersal. We then calculate a number of commonly used summary statistics of community structure in space and time and use random forests to evaluate their utility for inferring the strength of these three processes. We find that (i) both spatial and temporal data are necessary to disentangle metacommunity processes based on the summary statistics we test, and including statistics that are measured through time increases the explanatory power of random forests by up to 59% compared to cases where only spatial variation is considered; (ii) the three studied processes can be distinguished with different descriptors; and (iii) each summary statistic is differently sensitive to temporal and spatial sampling effort. Including repeated observations of metacommunities over time was essential for inferring the metacommunity processes, particularly dispersal. Some of the most useful statistics include the coefficient of variation of species abundances through time and metrics that incorporate variation in the relative abundances (evenness) of species. We conclude that a combination of methods and summary statistics is probably necessary to understand the processes that underlie metacommunity assembly through space and time, but we recognize that these results will be modified when other processes or summary statistics are used.
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| 26. |
- Kosten, Sarian, et al.
(författare)
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Warmer climates boost cyanobacterial dominance in shallow lakes
- 2012
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 18:1, s. 118-126
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Tidskriftsartikel (refereegranskat)abstract
- Dominance by cyanobacteria hampers human use of lakes and reservoirs worldwide. Previous studies indicate that excessive nutrient loading and warmer conditions promote dominance by cyanobacteria, but evidence from global scale field data has so far been scarce. Our analysis, based on a study of 143 lakes along a latitudinal transect ranging from subarctic Europe to southern South America, shows that although warmer climates do not result in higher overall phytoplankton biomass, the percentage of the total phytoplankton biovolume attributable to cyanobacteria increases steeply with temperature. Our results also reveal that the percent cyanobacteria is greater in lakes with high rates of light absorption. This points to a positive feedback because restriction of light availability is often a consequence of high phytoplankton biovolume, which in turn may be driven by nutrient loading. Our results indicate a synergistic effect of nutrients and climate. The implications are that in a future warmer climate, nutrient concentrations may have to be reduced substantially from present values in many lakes if cyanobacterial dominance is to be controlled.
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| 27. |
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| 28. |
- Shafer, Aaron B. A., et al.
(författare)
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Genomics and the challenging translation into conservation practice
- 2015
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Ingår i: Trends in Ecology & Evolution. - : Elsevier. - 0169-5347 .- 1872-8383. ; 30:2, s. 78-87
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Tidskriftsartikel (refereegranskat)abstract
- The global loss of biodiversity continues at an alarming rate. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights. However, the generation of genomic data and subsequent analyses and interpretations remain challenging and largely confined to academic research in ecology and evolution. This generates a gap between basic research and applicable solutions for conservation managers faced with multifaceted problems. Before the real-world conservation potential of genomic research can be realized, we suggest that current infrastructures need to be modified, methods must mature, analytical pipelines need to be developed, and successful case studies must be disseminated to practitioners.
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| 29. |
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| 30. |
- Shafer, Aaron B A, et al.
(författare)
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Reply to Garner et al
- 2016
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Ingår i: Trends in Ecology & Evolution. - : Elsevier BV. - 0169-5347 .- 1872-8383. ; 31:2, s. 83-84
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Tidskriftsartikel (refereegranskat)
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| 31. |
- Wright, Gillian, et al.
(författare)
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The Mid-infrared Instrument for JWST and Its In-flight Performance
- 2023
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Ingår i: Publications of the Astronomical Society of the Pacific. - 0004-6280 .- 1538-3873. ; 135:1046
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Tidskriftsartikel (refereegranskat)abstract
- The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ∼ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI.
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