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- Castro-González, A., et al.
(författare)
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The K2-OjOS Project*New and revisited planets and candidates in K2 campaigns 5, 16, & 18
- 2022
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 509:1, s. 1075-1095
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Tidskriftsartikel (refereegranskat)abstract
- We present the first results of K2-OjOS, a collaborative project between professional and amateur astronomers primarily aimed to detect, characterize, and validate new extrasolar planets. For this work, 10 amateur astronomers looked for planetary signals by visually inspecting the 20 427 light curves of K2 campaign 18 (C18). They found 42 planet candidates, of which 18 are new detections and 24 had been detected in the overlapping C5 by previous works. We used archival photometric and spectroscopic observations, as well as new high-spatial resolution images in order to carry out a complete analysis of the candidates found, including a homogeneous characterization of the host stars, transit modelling, search for transit timing variations and statistical validation. As a result, we report four new planets (K2-355 b, K2-356 b, K2-357 b, and K2-358 b) and 14 planet candidates. Besides, we refine the transit ephemeris of the previously published planets and candidates by modelling C5, C16 (when available) and C18 photometric data jointly, largely improving the period and mid-transit time precision. Regarding individual systems, we highlight the new planet K2-356 b and candidate EPIC 211537087.02 being near a 2:1 period commensurability, the detection of significant TTVs in the bright star K2-184 (V = 10.35), the location of K2-103 b inside the habitable zone according to optimistic models, the detection of a new single transit in the known system K2-274, and the disposition reassignment of K2-120 b, which we consider as a planet candidate as the origin of the signal cannot be ascertained.
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| 2. |
- Coya, R, et al.
(författare)
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Circulating non-22 kDa growth hormone isoforms after a repeated GHRH stimulus in normal subjects.
- 2005
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Ingår i: Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. - : Elsevier BV. - 1096-6374. ; 15:2, s. 123-9
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the proportion of non-22 kDa GH isoforms in relation to total GH concentration after a repeated GHRH stimulus in healthy subjects. We studied 25 normal volunteers (12 males and 13 females, mean age 13.1 years, range 6-35), who received two GHRH bolus (1.5 mug/kg body weight, i.v.) administered separately by an interval of 120 minutes. The proportion of non-22 kDa GH was determined by the 22 kDa GH exclusion assay (GHEA), which is based on immunomagnetic extraction of monomeric and dimeric 22 kDa GH from serum, and quantitation of non-22 kDa GH isoforms using a polyclonal GH assay. Samples were collected at baseline and at 15-30 min intervals up to 240 min for total GH concentration. Non-22 kDa GH isoforms were measured in samples where peak GH after GHRH was observed. Total GH peaked after the first GHRH bolus in all subjects (median 37.2 ng/ml; range: 10.4-94.6). According to GH response to the second GHRH stimulus, the study group was divided in "non-responders" (n=7; 28%), with GH peak levels lower than 10 ng/ml (median GH: 8.7 ng/ml; range 7.3-9.6) and "responders" (n=18; 72%), who showed a GH response greater than 10 ng/ml (median 17 ng/ml; range 10.1-47.0). The median proportion of non-22 kDa GH on the peak of GH secretion after the first GHRH administration was similar in both groups ("responders" median: 8.6%, range 7-10.9%; "non-responders" median: 8.7%, range 6.7-10.3%), independently of the type of response after the second GHRH. In contrast, the median proportion of non-22 kDa GH was greater at time of GH peak after the second GHRH bolus in the "non-responders" (median 11.4%; range 9.1-14.3%) in comparison with the "responders" (median 9.1%; range 6.7-11.9%; p=0.003). A significant negative correlation between the total GH secreted and the percentage of non-22 kDa isoforms was seen in the "non-responders" (p=0.003). These differences in GH response to repeated GHRH stimulation and in the pattern of GH isoforms at GH peak among subjects might be due to distinct recovery patterns of somatrotrophic function and/or differences in metabolic clearance of GH isoforms.
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