| 1. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 4. |
- Crowe, S., et al.
(författare)
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Near-infrared observations of outflows and young stellar objects in the massive star-forming region AFGL 5180
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 682
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Tidskriftsartikel (refereegranskat)abstract
- Context. Massive stars play important roles throughout the universe; however, their formation remains poorly understood. Observations of jets and outflows in high-mass star-forming regions, as well as surveys of young stellar object (YSO) content, can help test theoretical models of massive star formation. Aims. We aim at characterizing the massive star-forming region AFGL 5180 in the near-infrared (NIR), identifying outflows and relating these to sub-mm/mm sources, as well as surveying the overall YSO surface number density to compare to massive star formation models. Methods. Broad- and narrow-band imaging of AFGL 5180 was made in the NIR with the Large Binocular Telescope, in both seeing-limited (~0.5′) and high angular resolution (~0.09′) Adaptive Optics (AO) modes, as well as with the Hubble Space Telescope. Archival continuum data from the Atacama Millimeter/Submillimeter Array (ALMA) was also utilized. Results. At least 40 jet knots were identified via NIR emission from H2 and [FeII] tracing shocked gas. Bright jet knots outflowing from the central most massive protostar, S4 (estimated mass ~11 M⊙, via SED fitting), are detected towards the east of the source and are resolved in fine detail with the AO imaging. Additional knots are distributed throughout the field, likely indicating the presence of multiple driving sources. Sub-millimeter sources detected by ALMA are shown to be grouped in two main complexes, AFGL 5180 M and a small cluster ~15′ (0.15 pc in projection) to the south, AFGL 5180 S. From our NIR continuum images we identify YSO candidates down to masses of ~0.1 M⊙. Combined with the sub-mm sources, this yields a surface number density of such YSOs of N* ~ 103pc-2 within a projected radius of about 0.1 pc. Such a value is similar to those predicted by models of both core accretion from a turbulent clump environment and competitive accretion. The radial profile of N* is relatively flat on scales out to 0.2 pc, with only modest enhancement around the massive protostar inside 0.05 pc, which provides additional constraints on these massive star formation models. Conclusions. This study demonstrates the utility of high-resolution NIR imaging, in particular with AO, for detecting outflow activity and YSOs in distant regions. The presented images reveal the complex morphology of outflow-shocked gas within the large-scale bipolar flow of a massive protostar, as well as clear evidence for several other outflow driving sources in the region. Finally, this work presents a novel approach to compare the observed YSO surface number density from our study against different models of massive star formation.
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| 7. |
- Tiselius, Peter, 1958, et al.
(författare)
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Functional response of Oikopleura dioica to house clogging due to exposure to algae of different sizes
- 2003
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Ingår i: Marine Biology. - 0025-3162. ; 142:2, s. 253-261
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Tidskriftsartikel (refereegranskat)abstract
- The functional response of the appendicularian Oikopleura dioica was investigated with a unialgal diet (Isochrysis galbana, 0-1,600 mug Cl-1) and with additions of specific concentrations of algae either smaller than the incurrent filter mesh size (Rhodomonas baltica, 90 mug Cl-1; Thalassiosira weissflogii, 60 mug Cl-1) or larger algae (Ceratium lineatum, 8 mug Cl-1; C. tripos, 52 mug C l(-1)). Clearance ranged from 0.13 to 3.3 ml mug C-1 h(-1) and followed a Michaelis-Menten curve corresponding to a maximum filtration rate (particles collected by both animal and house), FRmax = 164 ng C mug C-1 h(-1) and K-m = 64 mug C l(-1). Maximum pellet production was 9 pellets ind(-1) h(-1) and occurred at 100 mugC (-1). Pellet production was proportional to filtration rate below this level, but declined at higher concentrations. House production ranged from 0.5 to 5.5 houses ind(-1) day(-1) and the corresponding curve fit resulted in H-max = 4.6 houses ind(-1) day(-1) and K-m house = 32 mug Cl-1. Addition of edible small algae caused increased internal clogging of the houses, evidenced by significantly higher pigment concentrations in abandoned houses than in houses produced with I.. galbana as a single food. House production was not affected. In contrast, larger algae caused a significantly higher house production, but the algae were not collected on the houses. Increased levels of edible algae will not have negative effects on O. dioica at ecologically realistic concentrations. Ambient bloom concentrations of larger algae may, however, have a negative effect on the growth of O. dioica populations, owing to the compensatory increased house production.
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| 8. |
- Tönnesson, Kajsa, 1971, et al.
(författare)
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Grazing impact of Oikopleura dioica and copepods on an autumn plankton community
- 2005
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Ingår i: Marine Biology Research. - : Informa UK Limited. - 1745-1000 .- 1745-1019. ; 1:5, s. 365-373
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Tidskriftsartikel (refereegranskat)abstract
- Copepods and appendicularians are major grazers in the pelagic environment. They have different retention efficiencies for prey and may therefore exert a variable grazing pressure on the spectrum of pico- to micro-plankton. We determined clearance rates of both groups at one station during 24 h in the Gullmar fjord, west Sweden, in autumn 1999. Total potential prey biomass ranged from 75 mu g C l(-1) at the surface to 14 mu g C l(-1) at 30 m with a dominance of larger dinoflagellates (10-25 mu m athecate species and Gymnodinium /Gyrodinium sp.) and the pennate diatom Pseudo -nitzschia sp. Grazer biomass was dominated by copepods (Acartia clausi, Paracalanus parvus) and appendicularians (Oikopleura dioica). O. dioica showed non-selective clearance rates of 0.7-1.8 ml mu g C-1 h(-1) on most diatoms, flagellates and ciliates, whereas Pseudo -nitzschia sp. and dinoflagellates and ciliates > 25 mu m were not removed by O. dioica. Appendicularian grazing impact was 0.06% d(-1) on the phytoplankton and 0.4% d(-1) on bacterial biomass. Despite a seven-fold higher biomass, the grazing impact of copepods on phytoplankton biomass was only 0.28% d(-1) indicating that O. dioica had a proportionally greater impact and, in contrast to copepods, also utilised bacteria. The low observed grazing impact was due to a low grazer biomass and a prey community largely unavailable to the investigated grazers.
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| 9. |
- Vargas, C. A., et al.
(författare)
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Importance of copepods versus appendicularians in vertical carbon fluxes in a Swedish fjord
- 2002
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 241, s. 125-138
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Tidskriftsartikel (refereegranskat)abstract
- We examined and quantified the contributions of copepods and appendicularians to the vertical flux of carbon during autumn and spring in Gullmar Fjord (west coast of Sweden). Faecal pellet-production rate was determined for major copepod and appendicularian species. In addition, house-production rates were estimated for the appendicularian Oikopleura dioica. Vertical flux of pigments, faecal carbon and appendicularian houses were measured using short-term (24 h) deployments of sediment traps at 2 depths (15 and 30 m). Copepods dominated the community biomass in both spring and autumn and their pellets dominated the faecal carbon flux. O. dioica houses with attached detritus were an important component of the biogenic carbon flux in October (15.3 mg C m(-2) d(-1)), equalling the contribution from copepods at 15 m and 50% of the flux at 30 m. At that time, we observed a loss rate of 70% d(-1) of the houses produced in the water column. In the spring, although Fritillaria borealis dominated the appendicularians, its houses did not appear to contribute to the biogenic flux. Our results suggest that oikopleurids and fritillariids may not operate equivalently in biogeochemical cycles. Because of the significant contribution of appendicularians to carbon fluxes, they should be incorporated in future flow models of coastal oceans.
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| 10. |
- Foessl, Ines, et al.
(författare)
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Bone Phenotyping Approaches in Human, Mice and Zebrafish – Expert Overview of the EU Cost Action GEMSTONE (“GEnomics of MusculoSkeletal traits TranslatiOnal NEtwork”)
- 2021
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Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 12
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Forskningsöversikt (refereegranskat)abstract
- A synoptic overview of scientific methods applied in bone and associated research fields across species has yet to be published. Experts from the EU Cost Action GEMSTONE (“GEnomics of MusculoSkeletal Traits translational Network”) Working Group 2 present an overview of the routine techniques as well as clinical and research approaches employed to characterize bone phenotypes in humans and selected animal models (mice and zebrafish) of health and disease. The goal is consolidation of knowledge and a map for future research. This expert paper provides a comprehensive overview of state-of-the-art technologies to investigate bone properties in humans and animals – including their strengths and weaknesses. New research methodologies are outlined and future strategies are discussed to combine phenotypic with rapidly developing –omics data in order to advance musculoskeletal research and move towards “personalised medicine”.
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