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- Lacour, S., et al.
(författare)
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The mass of β Pictoris c from β Pictoris b orbital motion
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 654
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet.Methods. We combined previous astrometry of β Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of β Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, β Pictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations.Results. From the astrometry of planet b only, we can (i) detect the presence of β Pictoris c and (ii) constrain its mass to 10.04(-3.10)(+4.53) M-Jup. If one adds the astrometry of β Pictoris c, the mass is narrowed down to 9.15(-1.06)(+1.08) M-Jup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89(-0.75)(+0.75) M-Jup. With a semimajor axis of 2.68 +/- 0.02 au, a period of 1221 +/- 15 days, and an eccentricity of 0.32 +/- 0.02, the orbital parameters of β Pictoris c are now constrained as precisely as those of β Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
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| 3. |
- Tomaz, S. A., et al.
(författare)
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Gross motor skills of South African preschool-aged children across different income settings
- 2019
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Ingår i: Journal of Science and Medicine in Sport. - : Elsevier. - 1440-2440 .- 1878-1861. ; 22:6, s. 689-694
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: No studies have investigated gross motor skill (GMS) proficiency of preschool-aged children across different income settings in South Africa. Research from high-income countries suggests that children from low-income settings display poorer GMS proficiency compared to higher-income peers. This study aimed to (1) describe GMS proficiency of preschool-aged children in urban high-income (UH), urban low-income (UL) and rural low-income (RL) settings; and (2) explore differences in proficiency between income settings and sex.Design: Descriptive cross-sectional study.Methods: The Test of Gross Motor Development-Edition 2 (TGMD-2) was used to assess GMS. The TGMD-2 gross motor quotient, standardised scores and raw scores were used to describe proficiency.Results: GMS proficiency was assessed in n = 259 3-6-year-old children (n = 46 UH, n = 91 UL, n =122 RL). Overall, 93% of the children were classified as having 'average' or better GMS. According to TGMD-2 standardised scores, the RL children performed significantly better than UH and UL children (p = 0.028 and p= 0.009, respectively). RL children were significantly more proficient than UH and UL children in the strike and horizontal jump when comparing raw scores. Overall, boys performed significantly better than girls in the strike, stationary dribble, kick and leap when comparing raw scores (all p <0.001).Conclusions: This study reports high GMS proficiency in preschool-aged children across income settings in South Africa. The factors associated with higher GMS in low-income settings are not immediately obvious. Thus, future research should explore potential factors and identify opportunities to ensure that GMS proficiency is capitalised on as preschool-aged children enter formal schooling. (C) 2018 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
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| 4. |
- Nilsson, Ricky, et al.
(författare)
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Project 1640 Observations of Brown Dwarf GJ 758 B : Near-infrared Spectrum and Atmospheric Modeling
- 2017
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 838:1
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Tidskriftsartikel (refereegranskat)abstract
- The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of l less than or similar to 30 au, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution (R similar to 50) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5 m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the Y, J, and H bands (similar to 9521770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with chi(2) minimization suggesting a best fit for spectral type T7.0 +/- 1.0, but with a shallow minimum over T5T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature T-eff = 741 +/- 25 K and surface gravity log g=4.3 +/- 0.5 dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date.
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| 6. |
- Hinkley, T., et al.
(författare)
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Early Childhood Electronic Media Use as a Predictor of Poorer Well-being A Prospective Cohort Study
- 2014
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Ingår i: JAMA pediatrics. - : American Medical Association (AMA). - 2168-6203 .- 2168-6211. ; 168:5, s. 485-492
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Identifying associations between preschool-aged children's electronic media use and their later well-being is essential to supporting positive long-term outcomes. OBJECTIVE To investigate possible dose-response associations of young children's electronic media use with their later well-being. DESIGN, SETTING, AND PARTICIPANTS The IDEFICS (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants) study is a prospective cohort study with an intervention component. Data were collected at baseline from September 1, 2007, through June 30, 2008, and at follow-up from September 1, 2009, through May 31, 2010, in 8 European countries participating in the IDEFICS study. This investigation is based on 3604 children aged 2 to 6 years who participated in the longitudinal component of the IDEFICS study only and not in the intervention. MAIN OUTCOMES AND MEASURES The following 6 indicators of well-being from 2 validated instruments were used as outcomes at follow-up: Peer problems and Emotional problems subscales from the Strengths and Difficulties Questionnaire and Emotional well-being, Self-esteem, Family functioning, and Social networks subscales from the KINDLR (Questionnaire for Measuring Health-Related Quality of Life in Children and Adolescents-Revised Version). Each scale was dichotomized to identify those children at risk for poorer outcomes. Indicators of electronic media use (weekday and weekend television and electronic game [e-game]/computer use) from baseline were used as predictors. RESULTS Associations varied between boys and girls; however, associations suggested that increased levels of electronic media use predicted poorer well-being outcomes. Television viewing on weekdays or weekends was more consistently associated with poorer outcomes than e-game/computer use. Across associations, the likelihood of adverse outcomes in children ranged from a 1.2- to 2.0-fold increase for emotional problems and poorer family functioning for each additional hour of television viewing or e-game/computer use depending on the outcome examined. CONCLUSIONS AND RELEVANCE Higher levels of early childhood electronic media use are associated with children being at risk for poorer outcomes with some indicators of well-being. Further research is required to identify potential mechanisms.
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| 7. |
- Tremblay, Mark S, et al.
(författare)
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Sedentary Behavior Research Network (SBRN) - Terminology Consensus Project process and outcome.
- 2017
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Ingår i: The international journal of behavioral nutrition and physical activity. - : Springer Science and Business Media LLC. - 1479-5868. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- The prominence of sedentary behavior research in health science has grown rapidly. With this growth there is increasing urgency for clear, common and accepted terminology and definitions. Such standardization is difficult to achieve, especially across multi-disciplinary researchers, practitioners, and industries. The Sedentary Behavior Research Network (SBRN) undertook a Terminology Consensus Project to address this need.First, a literature review was completed to identify key terms in sedentary behavior research. These key terms were then reviewed and modified by a Steering Committee formed by SBRN. Next, SBRN members were invited to contribute to this project and interested participants reviewed and provided feedback on the proposed list of terms and draft definitions through an online survey. Finally, a conceptual model and consensus definitions (including caveats and examples for all age groups and functional abilities) were finalized based on the feedback received from the 87 SBRN member participants who responded to the original invitation and survey.Consensus definitions for the terms physical inactivity, stationary behavior, sedentary behavior, standing, screen time, non-screen-based sedentary time, sitting, reclining, lying, sedentary behavior pattern, as well as how the terms bouts, breaks, and interruptions should be used in this context are provided.It is hoped that the definitions resulting from this comprehensive, transparent, and broad-based participatory process will result in standardized terminology that is widely supported and adopted, thereby advancing future research, interventions, policies, and practices related to sedentary behaviors.
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