| 1. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 2. |
- Björkman, Anne, 1981, et al.
(författare)
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Plant functional trait change across a warming tundra biome
- 2018
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 562:7725, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature–trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming.
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| 3. |
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| 4. |
- Güsten, R., et al.
(författare)
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APEX - The Atacama Pathfinder Experiment
- 2006
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 6267 I
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Konferensbidrag (refereegranskat)abstract
- APEX, the Atacama Pathfinder Experiment, has been successfully commissioned and is in operation now. This novel submillimeter telescope is located at 5107 m altitude on Llano de Chajnantor in the Chilean High Andes, on what is considered one of the world's outstanding sites for submillimeter astronomy. The primary reflector with 12 m diameter has been carefully adjusted by means of holography. Its surface smoothness of 17-18 μm makes APEX suitable for observations up to 200 μm, through all atmospheric submm windows accessible from the ground.
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| 5. |
- Ivashina, Marianna, 1975, et al.
(författare)
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System noise performance of ultra-wideband feeds for future radio telescopes: Conical-Sinuous Antenna and Eleven Antenna
- 2014
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Ingår i: 2014 31th URSI General Assembly and Scientific Symposium, URSI GASS 2014, Beijing, China, 16-23 August 2014. - 9781467352253 ; , s. Art. no. 6930063-
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Konferensbidrag (refereegranskat)abstract
- Next generation radio telescopes can greatly benefit from reflector antenna feeds that demonstrate very wide frequency bandwidth and can potentially realize low noise performance of the receivers. In this paper, we provide an overview of the current developments at the national radio observatories in Sweden and USA that make use of novel multi-port antenna feeds, such as the Sinuous Antenna and Eleven Antenna. The focus of this overview is on the system performance, when using this technology at high or very low frequencies, i.e. when the feed-receiver system is fully or partially (cryogenically) cooled.
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| 6. |
- Klein, Benjamin, 1981, et al.
(författare)
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Development of a detailed system model of the Eleven feed receiver using the CAESAR software
- 2012
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Ingår i: 6th European Conference on Antennas and Propagation, EuCAP 2012; Prague; Czech Republic; 26 March 2012 through 30 March 2012. - 9781457709180 ; , s. 3416-3420
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Konferensbidrag (refereegranskat)abstract
- A mathematically general method is presented for exporting the far-field patterns, radiation efficiency and impedance data, for multi-port antennas, from EM solvers to the microwave circuit simulator of the CAESAR software in order to perform the analysis of a multi-port antenna-receiver system. This hybrid modelling approach offers a few important advantages over the early developed modelling methods and standard simulation tools; including the capability to predict the correlated noise contributions due to both internal and external noise sources, while exploiting the translation/rotation symmetry of the antenna structure to reduce computation time. This approach is validated using folded dipole antennas and applied to model a more complex antenna-receiver system the Eleven antenna feed operating from 2 to 12 GHz which consists of four log-periodic dipole arrays co-integrated with LNAs, a balun and hybrid combining network. The Eleven feed receiver model is verified by comparing the simulation results with the measurements performed with a practical system.
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| 7. |
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| 8. |
- Klein, Benjamin, 1981, et al.
(författare)
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System noise calculations over the decade bandwidth of the Eleven feed for radio telescope applications
- 2010
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Ingår i: 2010 IEEE International Symposium on Antennas and Propagation, Toronto, July 11-17, 2010. - 1522-3965. - 9781424449682
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Konferensbidrag (refereegranskat)abstract
- The ability to cool the entire system improves system performance by a factor of two to four times; for the cooled case. This requires ambient systems to increase reflector diameters in proportion to achieve similar sensitivity. Additionally, the requirements on matching are relaxed in cooled systems, as the not-included variation of the LNA due to the noise mismatch is much smaller in a cooled system than in a non-cooled system. The calculations presented provide a meaningful reference to quickly compare systems, for both engineers and scientists. However, further work is ongoing into more accurate noise models and computer simulations. There is also ongoing work to verify results experimentally.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Pantaleev, Miroslav, 1970, et al.
(författare)
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Onsala Space Observatory – IVS Technology Development Center
- 2011
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Ingår i: International VLBI Service for Geodesy and Astrometry 2010 Annual Report, edited by D. Behrend and K.Baver. ; :NASA/TP-2011-215880, s. 280-283
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This report briefly describes the technical development relevant for geodetic/astrometric VLBI done during 2010 at the Onsala Space Observatory.
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| 13. |
- Parmar, Priyanka, et al.
(författare)
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Association of maternal prenatal smoking GFI1-locus and cardiometabolic phenotypes in 18,212 adults
- 2018
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Ingår i: EBioMedicine. - : Elsevier BV. - 2352-3964. ; 38, s. 206-216
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Tidskriftsartikel (refereegranskat)abstract
- Background: DNA methylation at the GFI1-locus has been repeatedly associated with exposure to smoking from the foetal period onwards. We explored whether DNA methylation may be a mechanism that links exposure to maternal prenatal smoking with offspring's adult cardio-metabolic health. Methods: We meta-analysed the association between DNA methylation at GFI1-locus with maternal prenatal smoking, adult own smoking, and cardio-metabolic phenotypes in 22 population-based studies from Europe, Australia, and USA (n= 18,212). DNA methylation at the GFI1-locus was measured in whole-blood. Multivariable regression models were fitted to examine its association with exposure to prenatal and own adult smoking. DNA methylation levels were analysed in relation to body mass index (BMI), waist circumference (WC), fasting glucose (FG), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), diastolic, and systolic blood pressure (BP). Findings: Lower DNA methylation at three out of eight GFI1-CpGs was associated with exposure to maternal prenatal smoking, whereas, all eight CpGs were associated with adult own smoking. Lower DNA methylation at cg14179389, the strongest maternal prenatal smoking locus, was associated with increased WC and BP when adjusted for sex, age, and adult smoking with Bonferroni-corrected P < 0.012. In contrast, lower DNA methylation at cg09935388, the strongest adult own smoking locus, was associated with decreased BMI, WC, and BP (adjusted 1 x 10(-7) < P < 0.01). Similarly, lower DNA methylation at cg12876356, cg18316974, cg09662411, and cg18146737 was associated with decreased BMI and WC (5 x 10(-8) < P < 0.001). Lower DNA methylation at all the CpGs was consistently associated with higher TG levels. Interpretation: Epigenetic changes at the GFI1 were linked to smoking exposure in-utero/in-adulthood and robustly associated with cardio-metabolic risk factors. Fund: European Union's Horizon 2020 research and innovation programme under grant agreement no. 633595 DynaHEALTH.
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| 14. |
- Wild, W., et al.
(författare)
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Millimetron—a large Russian-European submillimeter space observatory
- 2009
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 23:1, s. 221-244
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Tidskriftsartikel (refereegranskat)abstract
- Millimetron is a Russian-led 12 m diameter submillimeter and far-infrared space observatory which is included in the Space Plan of the Russian Federation for launch around 2017. With its large collecting area and state-of-the-art receivers, it will enable unique science and allow at least one order of magnitude improvement with respect to the Herschel Space Observatory. Millimetron will be operated in two basic observing modes: as a single-dish observatory, and as an element of a ground-space very long baseline interferometry (VLBI) system. As single-dish, angular resolutions on the order of 3 to 12 arc sec will be achieved and spectral resolutions of up to a million employing heterodyne techniques. As VLBI antenna, the chosen elliptical orbit will provide extremely large VLBI baselines (beyond 300,000 km) resulting in micro-arc second angular resolution.
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| 15. |
- Yang, Jian, 1960, et al.
(författare)
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Cryogenic 2-13 GHz Eleven feed for reflector antennas in future wideband radio telescopes
- 2011
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 59:6, s. 1918-1934
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Tidskriftsartikel (refereegranskat)abstract
- The system design of a cryogenic 2-13 GHz feed is considered with emphasis on its application in future wideband radio telescope systems. The feed is based on the so-called Eleven antenna and the design requires careful integration of various sub-designs in order to realize cryogenic operation. The various sub-designs include the electrical design of the Eleven antenna, design of the critical center puck, alternative solutions for integrating the Eleven antenna with low-noise amplifiers (LNAs), mechanical and cryogenic design and tests, and system noise temperature estimation and measurements. A great deal of simulated and measured results are presented throughout this paper, including the electrical, mechanical and cryogenic performance, and an assessment of the system noise temperature. The objective of this work is to present a good feed candidate that is well-suited for VLBI2010 and SKA radio telescopes. Further developments needed to completely fulfill the requirements for these future wideband radio telescopes are also discussed.
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| 16. |
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| 17. |
- Yang, Jian, 1960, et al.
(författare)
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Development of the cryogenic 2-14 GHz eleven feed system for VLBI2010
- 2012
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Ingår i: 6th European Conference on Antennas and Propagation, EuCAP 2012; Prague; Czech Republic; 26 March 2012 through 30 March 2012. - 9781457709180 ; , s. 621-625
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Konferensbidrag (refereegranskat)abstract
- We present an overview of the recent developments of a cryogenic 2-14 GHz feed system for the Very Long Baseline Interferometry 2010 (VLBL2010) project. The developments include a new balun feeding network, a new circular Eleven feed, system noise temperature modeling and testing, integration with different low noise amplifiers (LNAs), and cryostat design and integration.
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| 18. |
- Yang, Jian, 1960, et al.
(författare)
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Review of recent developments of the eleven feed for future decade bandwidth radio telescopes
- 2011
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Ingår i: 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011, Istanbul, 13-20 August 2011. - 9781424451173 ; , s. Art. no. 6051291-
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Konferensbidrag (refereegranskat)abstract
- The Eleven feed is a compact, low-profile decade-bandwidth log-periodic dual-dipole array antenna. It has many advantages: a constant phase center location, constant beam width over a decade bandwidth, high BOR1 efficiency, low cross polar level and good reflection coefficient, all over a decade bandwidth. This paper reviews the recent developments on the Eleven feed technology, which covers several important issues for the applications of the feed in decade bandwidth radio telescopes.
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| 19. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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