| 1. |
- Larsson, Bengt, et al.
(författare)
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Molecular oxygen in the rho Ophiuchi cloud
- 2007
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 466:3, s. 5-
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Tidskriftsartikel (refereegranskat)abstract
- Context: Molecular oxygen, O2, has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O2 emission.Aims: The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium. Methods: The Odin satellite carries a 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O2. Starting in 2002, the star forming molecular cloud core ρ Oph A was observed with Odin for 34 days during several observing runs.Results: We detect a spectral line at v_LSR =+3.5 km s-1 with Δ v_FWHM=1.5 km s-1, parameters which are also common to other species associated with ρ Oph A. This feature is identified as the O2 (NJ = 11 - 1_0) transition at 118 750.343 MHz.Conclusions: The abundance of molecular oxygen, relative to H{2} , is 5 × 10-8 averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits.Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Étude Spatiale (CNES). The Swedish Space Corporation has been the industrial prime contractor and also is operating the satellite. Appendix A is only available in electronic form at http://www.aanda.org
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| 2. |
- Berggren, Lars, et al.
(författare)
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Förord
- 2009
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Ingår i: Arbetarhistoria idag : Rapport från arbetarhistorikermötet i Landskrona i maj 2007 - Rapport från arbetarhistorikermötet i Landskrona i maj 2007. - 1654-2908. - 9789163346385 ; 3, s. 5-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Olofsson, Ingvar, 1943, et al.
(författare)
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Sustainable Bridges: Tillämpning av erfarenheter från ett EU-projekt, slutrapport
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the project was to systematically collect and analyse knowledge about the weaknesses and identified problems of the present European stock of railway bridges. The intention was to further analyse, develop and use this knowledge as a basis for improved design and construction methods of new bridges in Sweden, railway bridges as well asroad bridges.Basic background data is collected within the European project “Sustainable Bridges”, funded by the European Commission within its sixth framework programme, where the project members are actively participating in areas of strategic importance. Background data regarding the Swedish bridges is collected also through the recently launched Swedish bridge management system BaTMan, which is developed, owned and managed by the Swedish Road Administration and The Swedish Railway Authorities. The system is not a final system and some suggestions for improvement are presented.The results of the present project (enhanced methods for design and construction, improved detailing, proposals for amendments to standards etc) may be directly applied by contractors and design consultants and will be beneficial to the end users of the products, i.e. the owners of the bridges. The activities within “Sustainable Bridges” were started 1st of December 2003, with a superficial identification of “lack of knowledge”, as defined by the European railwayowners. A mapping of the European bridge demography was carried out and reported together with a specification of the most frequent problems of the existing bridges. Development work for enhanced assessment methods and improved methods for inspection and monitoring of the bridges followed. In the final phases of “Sustainable Bridges” the activities were concentrated on the identified problem areas and the degree of detailing was at the same time increased.The identified problem areas, as specified by the European railway owners, appear to be very similar to the needs of the Swedish bridge owners in spite of the fact that the studied bridges are geographically distributed over all Europe and its major climate zones. The same conclusion is valid for the defined improvement areas. The results achieved within “Sustainable Bridges” are therefore highly relevant for further development and application also to Swedish bridges and to the design and construction of new Swedish bridges.
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| 5. |
- Aunapuu, Maano, et al.
(författare)
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Spatial patterns and dynamic responses of arctic food webs corroborate the exploitation ecosystems hypothesis (EEH)
- 2008
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Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 171:2, s. 249-262
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Tidskriftsartikel (refereegranskat)abstract
- According to the exploitation ecosystems hypothesis (EEH), productive terrestrial ecosystems are characterized by community‐level trophic cascades, whereas unproductive ecosystems harbor food‐limited grazers, which regulate community‐level plant biomass. We tested this hypothesis along arctic‐alpine productivity gradients at the Joatka field base, Finnmark, Norway. In unproductive habitats, mammalian predators were absent and plant biomass was constant, whereas herbivore biomass varied, reflecting the productivity of the habitat. In productive habitats, predatory mammals were persistently present and plant biomass varied in space, but herbivore biomass did not. Plant biomass of productive tundra scrublands declined by 40% when vegetation blocks were transferred to predation‐free islands. Corresponding transfer to herbivore‐free islands triggered an increase in plant biomass. Fertilization of an unproductive tundra heath resulted in a fourfold increase in rodent density and a corresponding increase in winter grazing activity, whereas the total aboveground plant biomass remained unchanged. These results corroborate the predictions of the EEH, implying that the endotherm community and the vegetation of the North European tundra behaves dynamically as if each trophic level consisted of a single population, in spite of local co‐occurrence of >20 plant species representing different major taxonomic groups, growth forms, and defensive strategies.
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| 6. |
- Belitsky, Victor, 1955, et al.
(författare)
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Facility Heterodyne Receiver for the Atacama Pathfinder Experiment Telescope
- 2007
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Ingår i: Proceedings of Joint 32nd International Conference on Infrared Millimeter Waves and 15th International conference on Terahertz Electronics, Sept 3-7, 2007, City Hall, Cardiff, Wales, UK. ; , s. 326-328
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Konferensbidrag (refereegranskat)
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| 7. |
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| 8. |
- Djupvik, A. A., et al.
(författare)
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A multi-wavelength census of star formation activity in the young embedded cluster around Serpens/G3-G6
- 2006
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 458:3, s. 789-803
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Tidskriftsartikel (refereegranskat)abstract
- Aims.The aim of this paper is to characterise the star formation activity in the poorly studied embedded cluster Serpens/G3-G6, located ~45 arcmin (3 pc) to the south of the Serpens Cloud Core, and to determine the luminosity and mass functions of its population of Young Stellar Objects (YSOs).Methods: .Multi-wavelength broadband photometry was obtained to sample the near and mid-IR spectral energy distributions to separate YSOs from field stars and classify the YSO evolutionary stage. ISOCAM mapping in the two filters LW2 (5-8.5 μm) and LW3 (12-18 μm) of a 19 arcmin × 16 arcmin field was combined with JHKS data from 2MASS, KS data from Arnica/NOT, and L arcmin data from SIRCA/NOT. Continuum emission at 1.3 mm (IRAM) and 3.6 cm (VLA) was mapped to study the cloud structure and the coldest/youngest sources. Deep narrow band imaging at the 2.12 μm S(1) line of H2 from NOTCam/NOT was obtained to search for signs of bipolar outflows.Results: .We have strong evidence for a stellar population of 31 Class II sources, 5 flat-spectrum sources, 5 Class I sources, and two Class 0 sources. Our method does not sample the Class III sources. The cloud is composed of two main dense clumps aligned along a ridge over ~0.5 pc plus a starless core coinciding with absorption features seen in the ISOCAM maps. We find two S-shaped bipolar collimated flows embedded in the NE clump, and propose the two driving sources to be a Class 0 candidate (MMS3) and a double Class I (MMS2). For the Class II population we find a best age of ~2 Myr and compatibility with recent Initial Mass Functions (IMFs) by comparing the observed Class II luminosity function (LF), which is complete to 0.08 Lȯ, to various model LFs with different star formation scenarios and input IMFs.
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| 9. |
- Dochev, Dimitar Milkov, 1981, et al.
(författare)
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Nb3Al thin film deposition for low-noise terahertz electronics
- 2008
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Ingår i: Journal of Physics : Conference Series. ; 97:1, s. 012072 (6 pp.)-
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Tidskriftsartikel (refereegranskat)abstract
- Higher energy gap superconducting materials were always interesting for low-noise mixer applications such as superconductor-insulator-superconductor tunnel junctions (SIS) and hot-electron bolometer (HEB) used in sub-millimeter and terahertz parts of electro-magnetic spectrum. Here, we report a novel approach for producing Nb3Al thin film by co-sputtering from two confocally arranged Nb and Al dc-magnetrons onto substrate heated up to 830°C. Characterization of the deposited films revealed presence of the A15 phase and measured critical temperature was up to 15.7 K with the transition width 0.2-0.3 K for a 300 nm thick film. We measured the film critical magnetic field and studied influence of annealing on the film properties. We have investigated compositional depth profile of the deposited films by spectroscopy of reflected electrons.
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| 10. |
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