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- Tinetti, Giovanna, et al.
(författare)
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The EChO science case
- 2015
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 40:2-3, s. 329-391
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Tidskriftsartikel (refereegranskat)abstract
- The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune-all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10(-4) relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 mu m with a goal of covering from 0.4 to 16 mu m. Only modest spectral resolving power is needed, with R similar to 300 for wavelengths less than 5 mu m and R similar to 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m(2) is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m(2) telescope, diffraction limited at 3 mu m has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300-3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright "benchmark" cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO's launch and enable the atmospheric characterisation of hundreds of planets.
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| 2. |
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| 3. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 4. |
- Ask, Maria, et al.
(författare)
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The Innovative Exploration Drilling and Data Acquisition Research School
- 2021
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Ingår i: NSG2021 27th European Meeting of Environmental and Engineering Geophysics. - : European Association of Geoscientists and Engineers.
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Konferensbidrag (refereegranskat)abstract
- The Innovative Exploration Drilling and Data Acquisition Research School (I-EDDA-RS) is aimed at educating emerging scientists and engineers in on-site drilling and geoscientific investigation technology for mining. I-EDDA-RS consists if a consortium of scientists and specialists from six universities and research institutes in Germany and Sweden. A central component of the research school is that the courses have hands-on components at drill sites, boreholes and repositories. In addition, a course on entrepreneurial skills required in the exploration industry is also included in I-EDDA-RS. The arrival of the Covid-19 pandemic resulted in altered plans. Instead of offering ten courses with strong field work, practical, and entrepreneurial components during 2020, four courses via distant learning were offered. While this was disappointing in many aspects, two of the courses attracted a larger group of students from a wider part of the world than original envisioned. Outreach via on-line and open webinars is also a route to explore, as a complement to meetings and conferences in real life. The I-EDDA-RS courses in 2021 welcomes students at MSc & PhD level, as well as experienced professionals for lifelong learning (c.f. https://www.iedda.eu/rs). The form and type of teaching is to be determined.
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| 5. |
- Rasmussen, F. Berg, et al.
(författare)
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The nitrogen-pair oxygen defect in silicon
- 1996
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5107 .- 1873-4944. ; 36:1-3, s. 91-95
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Tidskriftsartikel (refereegranskat)abstract
- The nitrogen-pair oxygen defect in silicon has been studied by infrared absorption spectroscopy on samples implanted with various combinations of 14N, 15N, 16O and 17O. The measurements give direct evidence for the involvement of nitrogen and oxygen in the defect and show that the impurity atoms comprising the defect are only weakly coupled. Ab initio cluster calculation on several models of the nitrogen-pair oxygen defect have been performed and are compared with experiment. Based on these investigations a model consisting of a bridging oxygen atom adjacent to the nitrogen pair is suggested
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| 6. |
- Rasmussen, F. Berg, et al.
(författare)
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The NNO defect in silicon
- 1995
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Ingår i: Proceedings of the 18th International Conference on Defects in Semiconductors. - : Trans Tech Publications Inc.. ; , s. 791-796
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Konferensbidrag (refereegranskat)abstract
- Nitrogen-oxygen complexes in silicon have been studied by infrared absorption spectroscopy on samples implanted with various combinations of O and N isotopes as well as O-rich samples doped with N during growth. Local vibrational modes at 805, 999 and 1030 cm-1 (14N, 16O) are directly shown to belong to a defect consisting of a N-pair interacting with an O interstitial. A recently proposed model of this NNO defect is further investigated by ab initio cluster calculations and found to account for the dynamical properties of the defect. A mode around 730 cm-1 predicted by the calculation is observed giving further support to the model.
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| 7. |
- Døssing, A., et al.
(författare)
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A Multidisciplinary UAV- and Ground-Geophysical Mapping of Complex Mineralisations in an Inter-Tidal Coastal Zone, Brittany (France)
- 2020
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Ingår i: NSG2020 3rd Conference on Geophysics for Mineral Exploration and Mining. - : European Association of Geoscientists and Engineers.
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Konferensbidrag (refereegranskat)abstract
- Getting reliable geophysical and geological 3D models of the subsurface is an absolute necessity for successful resources exploration. Here, we show how novel UAV-borne geophysical mapping can be extremely valuable for mapping potential new exploration areas that are difficult to access by foot, such as hard rock inter-tidal zones and boulder beaches. We show the results from a multidisciplinary geophysical campaign of highly magnetic dikes and granites along a boulder beach in Brittany, France. Our mapping is carried out using customized geophysical sensor systems with high quality sensors. These include in particular a special designed UAV-towed magnetometer bird and multispectral system for large area mapping purposes. The UAV-borne mapping is supplemented by ground-based gamma-ray spectrometry data and ground-based magnetic gradiomety data. The results clearly demonstrate the value of UAV-borne systems in difficult areas as compared to traditional mapping methods as well as the value of combining various geophysical sensors for exploring the economic geology. All UAV-borne data were collected during two days, while the ground-based data – covering only the inner and dry part of the beach - were collected over seven days.
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