Institution
Dordt College
Education•Sioux Center, Iowa, United States•
About: Dordt College is a education organization based out in Sioux Center, Iowa, United States. It is known for research contribution in the topics: Faith & Primary education. The organization has 427 authors who have published 707 publications receiving 5469 citations.
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TL;DR: The spectral properties of ultra hot Jupiters were investigated in this article, where the authors used the SPARC/MITgcm spectral model to model the atmospheres of the four ultra hot supergiants and discussed more thoroughly the case of WASP-121b.
Abstract: Context A new class of exoplanets has emerged: the ultra hot Jupiters, the hottest close-in gas giants. The majority of them have weaker-than-expected spectral features in the 1.1−1.7 μm bandpass probed by HST/WFC3 but stronger spectral features at longer wavelengths probed by Spitzer. This led previous authors to puzzling conclusions about the thermal structures and chemical abundances of these planets. Aims We investigate how thermal dissociation, ionization, H− opacity, and clouds shape the thermal structures and spectral properties of ultra hot Jupiters. Methods We use the SPARC/MITgcm to model the atmospheres of four ultra hot Jupiters and discuss more thoroughly the case of WASP-121b. We expand our findings to the whole population of ultra hot Jupiters through analytical quantification of the thermal dissociation and its influence on the strength of spectral features. Results We predict that most molecules are thermally dissociated and alkalies are ionized in the dayside photospheres of ultra hot Jupiters. This includes H2O, TiO, VO, and H2 but not CO, which has a stronger molecular bond. The vertical molecular gradient created by the dissociation significantly weakens the spectral features from H2O while the 4.5 μm CO feature remains unchanged. The water band in the HST/WFC3 bandpass is further weakened by the continuous opacity of the H− ions. Molecules are expected to recombine before reaching the limb, leading to order of magnitude variations of the chemical composition and cloud coverage between the limb and the dayside. Conclusions Molecular dissociation provides a qualitative understanding of the lack of strong spectral features of water in the 1−2 μm bandpass observed in most ultra hot Jupiters. Quantitatively, our model does not provide a satisfactory match to the WASP-121b emission spectrum. Together with WASP-33b and Kepler-33Ab, they seem the outliers among the population of ultra hot Jupiters, in need of a more thorough understanding.
294 citations
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The George Institute for Global Health1, Uppsala University2, University of Cambridge3, Dordt College4, Harvard University5, Wageningen University and Research Centre6, University of Minnesota7, National Taiwan University8, University of Texas System9, Wake Forest University10, University of Eastern Finland11, Cancer Council Victoria12, United States Department of Agriculture13, University of British Columbia14, University of Bordeaux15, Stanford University16, Indiana University17, New York Academy of Medicine18, National Institutes of Health19, VU University Amsterdam20, University of Montpellier21, University of Washington22, University of South Dakota23, Karolinska Institutet24, Dalarna University25, Tufts University26
TL;DR: Findings suggest that linoleic acid has long-term benefits for the prevention of type 2 diabetes and that arachidonic acid is not harmful.
180 citations
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University of New South Wales1, Uppsala University2, University of Cambridge3, Stanford University4, University of Washington5, Wageningen University and Research Centre6, Tufts University7, Dordt College8, Umeå University9, University of Alabama at Birmingham10, Baylor College of Medicine11, University of Texas Health Science Center at Houston12, Aalborg University13, Karolinska Institutet14, University of Eastern Finland15, University of British Columbia16, National University of Singapore17, University of Bordeaux18, University of Melbourne19, National Taiwan University20, University of Minnesota21, University of Michigan22, Utrecht University23, VU University Amsterdam24, Harvard University25, Florida International University26, University of Iceland27, United States Department of Agriculture28, Johns Hopkins University29, National Institutes of Health30, University of South Dakota31, Indiana University32, Aarhus University33, Kaiser Permanente34, New York Academy of Medicine35, University of Dundee36, University of Oxford37, University of Pittsburgh38
TL;DR: In this paper, the authors evaluated how in vivo circulating and tissue levels of linoleic acid (LA) and arachidonic acid (AA) relate to incident cardiovascular disease (CVD) across multiple international studies.
Abstract: BACKGROUND: Global dietary recommendations for and cardiovascular effects of linoleic acid, the major dietary omega-6 fatty acid, and its major metabolite, arachidonic acid, remain controversial. To address this uncertainty and inform international recommendations, we evaluated how in vivo circulating and tissue levels of linoleic acid (LA) and arachidonic acid (AA) relate to incident cardiovascular disease (CVD) across multiple international studies. METHODS: We performed harmonized, de novo, individual-level analyses in a global consortium of 30 prospective observational studies from 13 countries. Multivariable-adjusted associations of circulating and adipose tissue LA and AA biomarkers with incident total CVD and subtypes (coronary heart disease, ischemic stroke, cardiovascular mortality) were investigated according to a prespecified analytic plan. Levels of LA and AA, measured as the percentage of total fatty acids, were evaluated linearly according to their interquintile range (ie, the range between the midpoint of the first and fifth quintiles), and categorically by quintiles. Study-specific results were pooled using inverse-variance-weighted meta-analysis. Heterogeneity was explored by age, sex, race, diabetes mellitus, statin use, aspirin use, omega-3 levels, and fatty acid desaturase 1 genotype (when available). RESULTS: In 30 prospective studies with medians of follow-up ranging 2.5 to 31.9 years, 15 198 incident cardiovascular events occurred among 68 659 participants. Higher levels of LA were significantly associated with lower risks of total CVD, cardiovascular mortality, and ischemic stroke, with hazard ratios per interquintile range of 0.93 (95% CI, 0.88-0.99), 0.78 (0.70-0.85), and 0.88 (0.79-0.98), respectively, and nonsignificantly with lower coronary heart disease risk (0.94; 0.88-1.00). Relationships were similar for LA evaluated across quintiles. AA levels were not associated with higher risk of cardiovascular outcomes; in a comparison of extreme quintiles, higher levels were associated with lower risk of total CVD (0.92; 0.86-0.99). No consistent heterogeneity by population subgroups was identified in the observed relationships. CONCLUSIONS: In pooled global analyses, higher in vivo circulating and tissue levels of LA and possibly AA were associated with lower risk of major cardiovascular events. These results support a favorable role for LA in CVD prevention.
173 citations
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TL;DR: Kataria et al. as mentioned in this paper presented results from an atmospheric circulation study of nine hot Jupiters that comprise a large transmission spectral survey using the Hubble and Spitzer Space Telescopes.
Abstract: Author(s): Kataria, Tiffany; Sing, David K; Lewis, Nikole K; Visscher, Channon; Showman, Adam P; Fortney, Jonathan J; Marley, Mark S | Abstract: We present results from an atmospheric circulation study of nine hot Jupiters that comprise a large transmission spectral survey using the Hubble and Spitzer Space Telescopes. These observations exhibit a range of spectral behavior over optical and infrared wavelengths which suggest diverse cloud and haze properties in their atmospheres. By utilizing the specific system parameters for each planet, we naturally probe a wide phase space in planet radius, gravity, orbital period, and equilibrium temperature. First, we show that our model "grid" recovers trends shown in traditional parametric studies of hot Jupiters, particularly equatorial superrotation and increased day-night temperature contrast with increasing equilibrium temperature. We show how spatial temperature variations, particularly between the dayside and nightside and west and east terminators, can vary by hundreds of K, which could imply large variations in Na, K, CO and CH4 abundances in those regions. These chemical variations can be large enough to be observed in transmission with high-resolution spectrographs, such as ESPRESSO on VLT, METIS on the E-ELT, or with MIRI and NIRSpec aboard JWST. We also compare theoretical emission spectra generated from our models to available Spitzer eclipse depths for each planet, and find that the outputs from our solar-metallicity, cloud-free models generally provide a good match to many of the datasets, even without additional model tuning. Although these models are cloud-free, we can use their results to understand the chemistry and dynamics that drive cloud formation in their atmospheres.
156 citations
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University of Cambridge1, University of Washington2, Uppsala University3, Harvard University4, National Taiwan University5, University of Eastern Finland6, Wake Forest University7, University of Bordeaux8, Baylor College of Medicine9, Cancer Council Victoria10, University of British Columbia11, Dordt College12, Public Health Research Institute13, Stanford University14, Brigham and Women's Hospital15, Wageningen University and Research Centre16, University of Melbourne17, University of South Dakota18, University of Iowa19, New York Academy of Medicine20, Tilburg University21, University of Minnesota22, The George Institute for Global Health23, Tufts University24
TL;DR: Higher levels of 15:0, 17: 0, and t16:1n-7 were associated with a lower risk of T2D, and similar associations were present in both genders but stronger in women than in men.
Abstract: BACKGROUND: We aimed to investigate prospective associations of circulating or adipose tissue odd-chain fatty acids 15:0 and 17:0 and trans-palmitoleic acid, t16:1n-7, as potential biomarkers of dairy fat intake, with incident type 2 diabetes (T2D). METHODS AND FINDINGS: Sixteen prospective cohorts from 12 countries (7 from the United States, 7 from Europe, 1 from Australia, 1 from Taiwan) performed new harmonised individual-level analysis for the prospective associations according to a standardised plan. In total, 63,682 participants with a broad range of baseline ages and BMIs and 15,180 incident cases of T2D over the average of 9 years of follow-up were evaluated. Study-specific results were pooled using inverse-variance-weighted meta-analysis. Prespecified interactions by age, sex, BMI, and race/ethnicity were explored in each cohort and were meta-analysed. Potential heterogeneity by cohort-specific characteristics (regions, lipid compartments used for fatty acid assays) was assessed with metaregression. After adjustment for potential confounders, including measures of adiposity (BMI, waist circumference) and lipogenesis (levels of palmitate, triglycerides), higher levels of 15:0, 17:0, and t16:1n-7 were associated with lower incidence of T2D. In the most adjusted model, the hazard ratio (95% CI) for incident T2D per cohort-specific 10th to 90th percentile range of 15:0 was 0.80 (0.73-0.87); of 17:0, 0.65 (0.59-0.72); of t16:1n7, 0.82 (0.70-0.96); and of their sum, 0.71 (0.63-0.79). In exploratory analyses, similar associations for 15:0, 17:0, and the sum of all three fatty acids were present in both genders but stronger in women than in men (pinteraction < 0.001). Whereas studying associations with biomarkers has several advantages, as limitations, the biomarkers do not distinguish between different food sources of dairy fat (e.g., cheese, yogurt, milk), and residual confounding by unmeasured or imprecisely measured confounders may exist. CONCLUSIONS: In a large meta-analysis that pooled the findings from 16 prospective cohort studies, higher levels of 15:0, 17:0, and t16:1n-7 were associated with a lower risk of T2D.
145 citations
Authors
Showing all 431 results
Name | H-index | Papers | Citations |
---|---|---|---|
Kay-Tee Khaw | 174 | 1389 | 138782 |
Channon Visscher | 27 | 54 | 3953 |
Paulo F. Ribeiro | 27 | 88 | 3437 |
Clifford G. Christians | 27 | 104 | 3919 |
Nathan L. Tintle | 25 | 58 | 2192 |
Lee R. DeHaan | 24 | 62 | 2473 |
Mark A. Noll | 22 | 102 | 2250 |
Douglas R. Allen | 22 | 53 | 1374 |
Kyle J. Van Arendonk | 19 | 49 | 1320 |
Gerrit Glas | 15 | 116 | 861 |
Nathan L. Tintle | 15 | 76 | 677 |
Theda Perdue | 13 | 28 | 846 |
Karen Hunger Parshall | 13 | 81 | 695 |
Matthew R. Dressler | 11 | 21 | 1032 |
David S Caudill | 10 | 78 | 678 |