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- Anguiano, B., et al.
(författare)
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Comprehensive comparison between APOGEE and LAMOST Radial velocities and atmospheric stellar parameters
- 2018
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 620
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Tidskriftsartikel (refereegranskat)abstract
- Context. In the era of massive spectroscopy surveys, automated stellar parameter pipelines and their validation are extremely important for an efficient scientific exploitation of the spectra. Aims. We undertake a critical and comprehensive comparison of the radial velocities and the main stellar atmosphere parameters for stars in common between the latest data releases from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE) and the Large sky Area Multi-Object Spectroscopic Telescope (LAMOST) surveys. Methods. APOGEE is a high-resolution (R = 22500) spectroscopic survey with high signal-to-noise ratio that is part of the Sloan Digital Sky Survey (SDSS). The latest data release, SDSS DR14, comprises APOGEE spectra for 263 444 stars, together with main stellar parameters and individual abundances for up to 20 chemical species. LAMOST is a low-resolution (R = 1800) optical spectroscopic survey also in the Northern Hemisphere, where 4000 fibers can be allocated simultaneously. LAMOST DR3 contains 3 177 995 stars. Results. A total of 42 420 dwarfs and giants stars are in common between the APOGEE DR14 - LAMOST DR3 stellar catalogs. A comparison between APOGEE and LAMOST RVs shows a clear offset of 4.54 +/- 0.03 km s(-1), with a dispersion of 5.8 km s(-1), in the sense that APOGEE radial velocities are higher. We observe a small offset in the effective temperatures of about 13 K, with a scatter of 155 K. A small offset in [Fe/H] of about 0.06 dex together with a scatter of 0.13 dex is also observed. We note that the largest offset between the surveys occurs in the surface gravities. Using only surface gravities in calibrated red giants from APOGEE DR14, with which there are 24 074 stars in common, a deviation of 0.14 dex is found with substantial scatter (0.25 dex). There are 17 482 red giant stars in common between APOGEE DR14 and those in LAMOST tied to APOGEE DR12 via the code called the Cannon. There is generally good agreement between the two data-sets. However, we find that the differences in the stellar parameters depend on effective temperature. For metal-rich stars, a different trend for the [Fe/H] discrepancies is found. Surprisingly, we see no correlation between the internal APOGEE DR14 - DR12 differences in T-eff and those in DR14 - LAMOST tied to DR12, where a correlation should be expected since LAMOST has been calibrated to APOGEE DR12. We find no correlation either between the [Fe/H] discrepancies, suggesting that LAMOST/Cannon is not well coupled to the APOGEE DR12 stellar parameter scale. An [Fe/H] dependence between the stellar parameters in APOGEE DR12 and those in DR14 is reported. We find a weak correlation in the differences between APOGEE DR14 - DR12 and LAMOST on DR12 surface gravity for stars hotter than 4800 K and in the log g range between 2.0 and 2.8 dex. We do not observe an [Fe/H] dependency in the gravity discrepancies.
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| 2. |
- Boeckxstaens, G. E., et al.
(författare)
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Phenotyping of subjects for large scale studies on patients with IBS
- 2016
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Ingår i: Neurogastroenterology and Motility. - : Wiley. - 1350-1925 .- 1365-2982. ; 28:8, s. 1134-1147
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Tidskriftsartikel (refereegranskat)abstract
- Background: Irritable bowel syndrome (IBS) is a complex condition with multiple factors contributing to its aetiology and pathophysiology. Aetiologically these include genetics, life-time events and environment, and physiologically, changes in motility, central processing, visceral sensitivity, immunity, epithelial permeability and gastrointestinal microflora. Such complexity means there is currently no specific reliable biomarker for IBS, and thus IBS continues to be diagnosed and classified according to symptom based criteria, the Rome Criteria. Carefully phenotyping and characterisation of a ‘large’ pool of IBS patients across Europe and even the world however, might help identify sub-populations with accuracy and consistency. This will not only aid future research but improve tailoring of treatment and health care of IBS patients. Purpose: The aim of this position paper is to discuss the requirements necessary to standardize the process of selecting and phenotyping IBS patients and how to organise the collection and storage of patient information/samples in such a large multi-centre pan European/global study. We include information on general demographics, gastrointestinal symptom assessment, psychological factors, quality of life, physiological evaluation, genetic/epigenetic and microbiota analysis, biopsy/blood sampling, together with discussion on the organisational, ethical and language issues associated with implementing such a study. The proposed approach and documents selected to be used in such a study was the result of a thoughtful and thorough four-year dialogue amongst experts associated with the European COST action BM1106 GENIEUR (www.GENIEUR.eu). © 2016 John Wiley & Sons Ltd
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| 4. |
- Keevallik, Leelo, 1969-
(författare)
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The grammar-interaction interface of negative questions in Estonian
- 2009
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Ingår i: SKY Journal of Linguistics. - Helsinki : Suomen kielitieteellinen yhdistys. - 1456-8438 .- 1796-279X. ; 22, s. 139-173
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Tidskriftsartikel (refereegranskat)abstract
- Grammatically negative questions have been considered tricky because out of context it is basically impossible to predict whether they are conducive of a positive or negative answer (e.g. Sadock and Zwicky 1985). Furthermore, some of them convey reverse polarity affirmations rather than ask for information (Koshik 2002). The current study looks systematically at all negative polar questions found in Estonian spoken language corpora and shows that in actual usage, they are predominantly conducive of a confirming answer. However, a confirming answer may in some cases be either in a positive or negative form. Conduciveness of a negative question as well as its linguistic format depend on the action the question implements in a conversational sequence. The paper shows that each of the five negative question formats in Estonian regularly implement different kinds of social action ranging from challenging and topic initiation to requests for information and confirmation.
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| 6. |
- Yengoh, Genesis Tambang, et al.
(författare)
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Explaining low yields and low food production in Cameroon : A farmers' perspective
- 2014
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Ingår i: GeoJournal. - : Springer Science and Business Media LLC. - 0343-2521 .- 1572-9893. ; 79:3, s. 279-295
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Tidskriftsartikel (refereegranskat)abstract
- While a bottom-up approach to identifying problems affecting food production among small-scale farmers has been urged as an appropriate means of finding sustainable solutions, few studies have determined the practical process of doing so and measured the outcomes of such an approach. This paper uses information gained mainly through focus groups with small-scale farmers and semi-structured interviews, to identify farmers' perceptions of reasons behind low yields and low agricultural production in three communities of Cameroon's North West region. Three biophysical factors are identified as the main reasons of low production: the long and more frequent dry spells and late start of the start of the rainy season. Three socio-economic reasons are identified as most important: land scarcity, money to invest in agriculture and labour scarcity. Farmers rank their reasons based on the importance to their agricultural production in their local area. Some of the important claims made by farmers are tested using field data and statistical analysis. These include the claims that: (1) the rainy season is increasingly starting later than it used to; and (2) the length of dry spells are increasingly longer than they used to be. The results of these statistical tests are significant, showing that farmers' knowledge of some of the local problems affecting their activities can serve as an important input into formal research and policy design. Peoples' understanding of a problem affects the way they will act on it-in terms of searching for solutions and implementing change. Farmers can therefore provide useful insights on why they think there are large yield gaps within their local production environments. The current agricultural development policy of the Cameroon government is advocating greater public-private engagement and can benefit from farmers' inputs and opinions in the design of relevant policies. In the same light, nonlocal based researchers and research institutions can draw on farmers' knowledge to create and accumulate knowledge on sustainable solutions to problems of low yields and low food production in Cameroon.
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