| 1. |
- van Dishoeck, E. F., et al.
(författare)
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Water in Star-forming Regions with the Herschel Space Observatory (WISH). I. Overview of Key Program and First Results
- 2011
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 123:900, s. 138-170
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Tidskriftsartikel (refereegranskat)abstract
- Water In Star-forming regions with Herschel (WISH) is a key program on the Herschel Space Observatory designed to probe the physical and chemical structures of young stellar objects using water and related molecules and to follow the water abundance from collapsing clouds to planet-forming disks. About 80 sources are targeted, covering a wide ranee of luminosities-from low ( 10(5) L-circle dot)-and a wide range of evolutionary stages-from cold prestellar cores to warm protostellar envelopes and outflows to disks around young stars. Both the HIFI and PACS instruments are used to observe a variety of lines of H2O, (H2O)-O-18 and chemically related species at the source position and in small maps around the protostars and selected outflow positions. In addition, high-frequency lines of CO, (CO)-C-13, and (CO)-O-18 are obtained with Herschel and are complemented by ground-based observations of dust continuum, HDO, CO and its isotopologs, and other molecules to ensure a self-consistent data set for analysis. An overview of the scientific motivation and observational strategy of the program is given, together with the modeling approach and analysis tools that have been developed. Initial science results are presented. These include a lack of water in cold gas at abundances that are lower than most predictions, strong water emission from shocks in protostellar environments, the importance of UV radiation in heating the gas along outflow walls across the full range of luminosities, and surprisingly widespread detection of the chemically related hydrides OH+ and H2O+ in outflows and foreground gas. Quantitative estimates of the energy budget indicate that H2O is generally not the dominant coolant in the warm dense gas associated with protostars. Very deep limits on the cold gaseous water reservoir in the outer regions of protoplanetary disks are obtained that have profound implications for our understanding of grain growth and mixing in disks.
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| 2. |
- Salter, Matthew E., et al.
(författare)
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On the seawater temperature dependence of the sea spray aerosol generated by a continuous plunging jet
- 2014
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Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 119:14, s. 9052-9072
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Tidskriftsartikel (refereegranskat)abstract
- Breaking waves on the ocean surface produce bubbles which, upon bursting, deliver seawater constituents into the atmosphere as sea spray aerosol particles. One way of investigating this process in the laboratory is to generate a bubble plume by a continuous plunging jet. We performed a series of laboratory experiments to elucidate the role of seawater temperature on aerosol production from artificial seawater free from organic contamination using a plunging jet. The seawater temperature was varied from -1.3 degrees C to 30.1 degrees C, while the volume of air entrained by the jet, surface bubble size distributions, and size distribution of the aerosol particles produced was monitored. We observed that the volume of air entrained decreased as the seawater temperature was increased. The number of surface bubbles with film radius smaller than 2 mm decreased nonlinearly with seawater temperature. This decrease was coincident with a substantial reduction in particle production. The number concentrations of particles with dry diameter less than similar to 1 mu m decreased substantially as the seawater temperature was increased from -1.3 degrees C to similar to 9 degrees C. With further increase in seawater temperature (up to 30 degrees C), a small increase in the number concentration of larger particles (dry diameter >similar to 0.3 mu m) was observed. Based on these observations, we infer that as seawater temperature increases, the process of bubble fragmentation changes, resulting in decreased air entrainment by the plunging jet, as well as the number of bubbles with film radius smaller than 2 mm. This again results in decreased particle production with increasing seawater temperature.
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| 3. |
- Mann, P. J., et al.
(författare)
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The biogeochemistry of carbon across a gradient of streams and rivers within the Congo Basin
- 2014
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Ingår i: Journal of Geophysical Research: Biogeosciences. - 2169-8953. ; 119:4, s. 687-702
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Tidskriftsartikel (refereegranskat)abstract
- Dissolved organic carbon (DOC) and inorganic carbon (DIC, pCO(2)), lignin biomarkers, and theoptical properties of dissolved organic matter (DOM) were measured in a gradient of streams and rivers within the Congo Basin, with the aim of examining how vegetation cover and hydrology influences the composition and concentration of fluvial carbon (C). Three sampling campaigns (February 2010, November 2010, and August 2011) spanning 56 sites are compared by subbasin watershed land cover type (savannah, tropical forest, and swamp) and hydrologic regime (high, intermediate, and low). Land cover properties predominately controlled the amount and quality of DOC, chromophoric DOM (CDOM) and lignin phenol concentrations (Sigma(8)) exported in streams and rivers throughout the Congo Basin. Higher DIC concentrations and changing DOM composition (lower molecular weight, less aromatic C) during periods of low hydrologic flow indicated shifting rapid overland supply pathways in wet conditions to deeper groundwater inputs during drier periods. Lower DOC concentrations in forest and swamp subbasins were apparent with increasing catchment area, indicating enhanced DOC loss with extended water residence time. Surface water pCO(2) in savannah and tropical forest catchments ranged between 2,600 and 11,922 mu atm, with swamp regions exhibiting extremely high pCO(2) (10,598-15,802 mu atm), highlighting their potential as significant pathways for water-air efflux. Our data suggest that the quantity and quality of DOM exported to streams and rivers are largely driven by terrestrial ecosystem structure and that anthropogenic land use or climate change may impact fluvial C composition and reactivity, with ramifications for regional C budgets and future climate scenarios.
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| 4. |
- Perkmann, M., et al.
(författare)
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Academic engagement and commercialisation: A review of the literature on university-industry relations
- 2013
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Ingår i: Research Policy. - : Elsevier BV. - 0048-7333 .- 1873-7625. ; 42:2, s. 423-442
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Tidskriftsartikel (refereegranskat)abstract
- A considerable body of work highlights the relevance of collaborative research, contract research, consulting and informal relationships for university–industry knowledge transfer. We present a systematic review of research on academic scientists’ involvement in these activities to which we refer as ‘academic engagement’. Apart from extracting findings that are generalisable across studies, we ask how academic engagement differs from commercialisation, defined as intellectual property creation and academic entrepreneurship. We identify the individual, organisational and institutional antecedents and consequences of academic engagement, and then compare these findings with the antecedents and consequences of commercialisation. Apart from being more widely practiced, academic engagement is distinct from commercialisation in that it is closely aligned with traditional academic research activities, and pursued by academics to access resources supporting their research agendas. We conclude by identifying future research needs, opportunities for methodological improvement and policy interventions.
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| 5. |
- Schneider-Zapp, K., et al.
(författare)
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An automated gas exchange tank for determining gas transfer velocities in natural seawater samples
- 2014
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Ingår i: Ocean Science. - : Copernicus GmbH. - 1812-0784 .- 1812-0792. ; 10:4, s. 587-600
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Tidskriftsartikel (refereegranskat)abstract
- In order to advance understanding of the role of seawater surfactants in the air-sea exchange of climatically active trace gases via suppression of the gas transfer velocity (k(w)), we constructed a fully automated, closed air-water gas exchange tank and coupled analytical system. The system allows water-side turbulence in the tank to be precisely controlled with an electronically operated baffle. Two coupled gas chromatographs and an integral equilibrator, connected to the tank in a continuous gas-tight system, allow temporal changes in the partial pressures of SF6, CH4 and N2O to be measured simultaneously in the tank water and headspace at multiple turbulence settings, during a typical experimental run of 3.25 h. PC software developed by the authors controls all operations and data acquisition, enabling the optimisation of experimental conditions with high reproducibility. The use of three gases allows three independent estimates of k(w) for each turbulence setting; these values are subsequently normalised to a constant Schmidt number for direct comparison. The normalised k(w) estimates show close agreement. Repeated experiments with Milli-Q water demonstrate a typical measurement accuracy of 4% for k(w). Experiments with natural seawater show that the system clearly resolves the effects on k(w) of spatial and temporal trends in natural surfactant activity. The system is an effective tool with which to probe the relationships between k(w), surfactant activity and biogeochemical indices of primary productivity, and should assist in providing valuable new insights into the air-sea gas exchange process.
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| 6. |
- Schneider-Zapp, K., et al.
(författare)
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Technical Note : Comparison of storage strategies of sea surface microlayer samples
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10:7, s. 4927-4936
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Tidskriftsartikel (refereegranskat)abstract
- The sea surface microlayer (SML) is an important biogeochemical system whose physico-chemical analysis often necessitates some degree of sample storage. However, many SML components degrade with time so the development of optimal storage protocols is paramount. We here briefly review some commonly used treatment and storage protocols. Using freshwater and saline SML samples from a river estuary, we investigated temporal changes in surfactant activity (SA) and the absorbance and fluorescence of chromophoric dissolved organic matter (CDOM) over four weeks, following selected sample treatment and storage protocols. Some variability in the effectiveness of individual protocols most likely reflects sample provenance. None of the various protocols examined performed any better than dark storage at 4 degrees C without pre-treatment. We therefore recommend storing samples refrigerated in the dark.
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