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| 2. |
- Mallorquin, M., et al.
(författare)
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TOI-1801 b: A temperate mini-Neptune around a young M0.5 dwarf
- 2023
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 680
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery, mass, and radius determination of TOI-1801 b, a temperate mini-Neptune around a young M dwarf. TOI-1801 b was observed in TESS sectors 22 and 49, and the alert that this was a TESS planet candidate with a period of 21.3 days went out in April 2020. However, ground-based follow-up observations, including seeing-limited photometry in and outside transit together with precise radial velocity (RV) measurements with CARMENES and HIRES revealed that the true period of the planet is 10.6 days. These observations also allowed us to retrieve a mass of 5.74 +/- 1.46 M-circle plus, which together with a radius of 2.08 +/- 0.12 R-circle plus, means that TOI-1801 b is most probably composed of water and rock, with an upper limit of 2% by mass of H-2 in its atmosphere. The stellar rotation period of 16 days is readily detectable in our RV time series and in the ground-based photometry. We derived a likely age of 600-800 Myr for the parent star TOI-1801, which means that TOI-1801 b is the least massive young mini-Neptune with precise mass and radius determinations. Our results suggest that if TOI-1801 b had a larger atmosphere in the past, it must have been removed by some evolutionary mechanism on timescales shorter than 1 Gyr.
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| 3. |
- Turtelboom,, et al.
(författare)
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The TESS-Keck Survey. XI. Mass Measurements for Four Transiting Sub-Neptunes Orbiting K Dwarf TOI-1246
- 2022
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 163:6
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Tidskriftsartikel (refereegranskat)abstract
- Multiplanet systems are valuable arenas for investigating exoplanet architectures and comparing planetary siblings. TOI-1246 is one such system, with a moderately bright K dwarf (V = 11.6, K = 9.9) and four transiting sub-Neptunes identified by TESS with orbital periods of 4.31, 5.90, 18.66, and 37.92 days. We collected 130 radial velocity observations with Keck/HIRES and TNG/HARPS-N to measure planet masses. We refit the 14 sectors of TESS photometry to refine planet radii (2.97 +/- 0.06 R (circle plus), 2.47 +/- 0.08 R (circle plus), 3.46 +/- 0.09 R (circle plus), and 3.72 +/- 0.16 R (circle plus)) and confirm the four planets. We find that TOI-1246 e is substantially more massive than the three inner planets (8.1 +/- 1.1 M (circle plus), 8.8 +/- 1.2 M (circle plus), 5.3 +/- 1.7 M (circle plus), and 14.8 +/- 2.3 M (circle plus)). The two outer planets, TOI-1246 d and TOI-1246 e, lie near to the 2:1 resonance (P (e)/P ( d ) = 2.03) and exhibit transit-timing variations. TOI-1246 is one of the brightest four-planet systems, making it amenable for continued observations. It is one of only five systems with measured masses and radii for all four transiting planets. The planet densities range from 0.70 +/- 0.24 to 3.21 +/- 0.44 g cm(-3), implying a range of bulk and atmospheric compositions. We also report a fifth planet candidate found in the RV data with a minimum mass of 25.6 +/- 3.6 M (circle plus). This planet candidate is exterior to TOI-1246 e, with a candidate period of 93.8 days, and we discuss the implications if it is confirmed to be planetary in nature.
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| 4. |
- Beard, Corey, et al.
(författare)
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The TESS-Keck Survey. XVII. Precise Mass Measurements in a Young, High-multiplicity Transiting Planet System Using Radial Velocities and Transit Timing Variations
- 2024
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Ingår i: Astronomical Journal. - 1538-3881 .- 0004-6256. ; 167:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a radial velocity (RV) analysis of TOI-1136, a bright Transiting Exoplanet Survey Satellite (TESS) system with six confirmed transiting planets, and a seventh single-transiting planet candidate. All planets in the system are amenable to transmission spectroscopy, making TOI-1136 one of the best targets for intra-system comparison of exoplanet atmospheres. TOI-1136 is young (similar to 700 Myr), and the system exhibits transit timing variations (TTVs). The youth of the system contributes to high stellar variability on the order of 50 m s-1, much larger than the likely RV amplitude of any of the transiting exoplanets. Utilizing 359 High Resolution Echelle Spectrometer and Automated Planet Finder RVs collected as part of the TESS-Keck Survey, and 51 High-Accuracy Radial velocity Planetary Searcher North RVs, we experiment with a joint TTV-RV fit. With seven possible transiting planets, TTVs, more than 400 RVs, and a stellar activity model, we posit that we may be presenting the most complex mass recovery of an exoplanet system in the literature to date. By combining TTVs and RVs, we minimized Gaussian process overfitting and retrieved new masses for this system: (m b-g = 3.50-0.7+0.8 , 6.32-1.3+1.1 , 8.35-1.6+1.8 , 6.07-1.01+1.09 , 9.7-3.7+3.9 , 5.6-3.2+4.1 M circle plus). We are unable to significantly detect the mass of the seventh planet candidate in the RVs, but we are able to loosely constrain a possible orbital period near 80 days. Future TESS observations might confirm the existence of a seventh planet in the system, better constrain the masses and orbital properties of the known exoplanets, and generally shine light on this scientifically interesting system.
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| 5. |
- MacDougall, Andrew S., et al.
(författare)
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The Neolithic Plant Invasion Hypothesis : the role of preadaptation and disturbance in grassland invasion
- 2018
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 220:1, s. 94-103
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Forskningsöversikt (refereegranskat)abstract
- A long-standing hypothesis is that many European plants invade temperate grasslands globally because they are introduced simultaneously with pastoralism and cultivation, to which they are 'preadapted' after millennia of exposure dating to the Neolithic era ('Neolithic Plant Invasion Hypothesis' (NPIH)). These 'preadaptations' are predicted to maximize their performance relative to native species lacking this adaptive history. Here, we discuss the explanatory relevance of the NPIH, clarifying the importance of evolutionary context vs other mechanisms driving invasion. The NPIH makes intuitive sense given established connections between invasion and agricultural-based perturbation. However, tests are often incomplete given the need for performance contrasts between home and away ranges, while controlling for other mechanisms. We emphasize six NPIH-based predictions, centring on trait similarity of invaders between home vs away populations, and differing perturbation responses by invading and native plants. Although no research has integrated all six predictions, we highlight studies suggesting preadaptation influences on invasion. Given that many European grasslands are creations of human activity from the past, current invasions by these flora may represent the continuation of processes dating to the Neolithic. Ironically, European Neolithic-derived grasslands are becoming rarer, reflecting changes in management and illustrating the importance of human influences on these species.
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| 6. |
- Bennett, Charles L., et al.
(författare)
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Reassessments of ESAs for cancer treatment in the US and Europe
- 2010
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Ingår i: Oncology. - 0890-9091. ; 24:3, s. 260-268
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Tidskriftsartikel (refereegranskat)abstract
- Anemia is a widely prevalent complication among cancer patients. At the time of diagnosis, 30% to 40% of patients with non-Hodgkin lymphoma or Hodgkin lymphoma and up to 70% of patients with multiple myeloma are anemic; rates are higher among persons with myelodysplastic syndromes. Among patients with solid cancers or lymphomas, up to half develop anemia following chemotherapy. For almost 2 decades, erythropoiesis-stimulating agents (ESAs) were the primary treatment for cancer-related anemia. However, reassessments of benefits and risks of ESAs for cancer-associated anemia have occurred internationally. We reviewed guidelines and notifications from regulatory agencies and manufacturers, reimbursement policies, and utilization for ESAs in the cancer and chronic kidney disease settings within the United States, Europe, and Canada. In 2008 the US Food and Drug Administration (FDA) restricted ESAs from cancer patients seeking cure. Reimbursement is limited to hemoglobin levels < 10 g/dL. In the United States, ESA usage increased 340% between 2001 and 2006, and decreased 60% since 2007. The European Medicines Agency (EMEA) recommended that ESA benefits do not outweigh risks. In Europe between 2001 and 2006, ESA use increased 51%; since 2006, use decreased by 10%. In 2009, Canadian manufacturers recommended usage based on patient preferences. In Canada in 2007, approximately 20% of anemic cancer patients received ESAs, a 20% increase since 2004. In contrast to Europe, where ESA use has increased over time, reassessments of ESA-associated safety concerns in the United States have resulted in marked decrements in ESA use among cancer patients.
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| 7. |
- Heurgué-Hamard, V, Karimi, R, Mora, L, MacDougall, J, Leboeuf, C, Grentzmann, G, Ehrenberg, M, Buckingham, R.H.
(författare)
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Ribosome release factor RF4 and termination factor RF3 are involved in dissocation of peptidyl-tRNA from the ribosome
- 1998
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Ingår i: journal. - : EMBO J.. ; 17, s. 808-816
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Hon, Marc, et al.
(författare)
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A close-in giant planet escapes engulfment by its star
- 2023
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 618:7967, s. 917-920
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Tidskriftsartikel (refereegranskat)abstract
- When main-sequence stars expand into red giants, they are expected to engulf close-in planets(1-5). Until now, the absence of planets with short orbital periods around post-expansion, core-helium-burning red giants(6-8) has been interpreted as evidence that short-period planets around Sun-like stars do not survive the giant expansion phase of their host stars(9). Here we present the discovery that the giant planet 8 Ursae Minoris b(10) orbits a core-helium-burning red giant. At a distance of only 0.5 au from its host star, the planet would have been engulfed by its host star, which is predicted by standard single-star evolution to have previously expanded to a radius of 0.7 au. Given the brief lifetime of helium-burning giants, the nearly circular orbit of the planet is challenging to reconcile with scenarios in which the planet survives by having a distant orbit initially. Instead, the planet may have avoided engulfment through a stellar merger that either altered the evolution of the host star or produced 8 Ursae Minoris b as a second-generation planet(11). This system shows that core-helium-burning red giants can harbour close planets and provides evidence for the role of non-canonical stellar evolution in the extended survival of late-stage exoplanetary systems.
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| 9. |
- MacDougall, Andrew S., et al.
(författare)
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Context-dependent interactions and the regulation of species richness in freshwater fish
- 2018
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Species richness is regulated by a complex network of scale-dependent processes. This complexity can obscure the influence of limiting species interactions, making it difficult to determine if abiotic or biotic drivers are more predominant regulators of richness. Using integrative modeling of freshwater fish richness from 721 lakes along an 11 degrees latitudinal gradient, we find negative interactions to be a relatively minor independent predictor of species richness in lakes despite the widespread presence of predators. Instead, interaction effects, when detectable among major functional groups and 231 species pairs, were strong, often positive, but contextually dependent on environment. These results are consistent with the idea that negative interactions internally structure lake communities but do not consistently 'scale-up' to regulate richness independently of the environment. The importance of environment for interaction outcomes and its role in the regulation of species richness highlights the potential sensitivity of fish communities to the environmental changes affecting lakes globally.
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| 10. |
- Ong, Ken K., et al.
(författare)
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Pregnancy Insulin, Glucose, and BMI Contribute to Birth Outcomes in Nondiabetic Mothers
- 2008
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 31:11, s. 2193-2197
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE - We investigated the effects of normal variations in maternal glycemia on birth size and other birth outcomes. RESEARCH DESIGN AND METHODS - Women in two unselected birth cohorts, one retrospective (n = 3,158) and one prospective (n = 668), underwent an oral glucose challenge at 28 weeks of gestation. In the retrospective study, glycemia was linked to routine birth records. In the prospective study, offspring adiposity was assessed by skinfold thickness from birth to age 24 months. RESULTS - In the retrospective study, within the nondiabetic range (2.1-7.8 mmol/l), each 1 mmol/l rise in the mother's 60-min glucose level was associated with a (mean +/- SEM) 2.1 +/- 0.8% (P = 0.006) rise in absolute risk of assisted vaginal delivery, a 3.4 +/- 0.8% (P < 0.0001) rise in emergency cesarean delivery, a 3.1 +/- 0.7% (P < 0.0001) rise in elective cesarean delivery, and a 46 +/- 8 g (P < 0.0001) increase in offspring birth weight. in the prospective study, fetal macrosomia (birth weight >90th centile) was independently related to the mother's fasting glucose (odds ratio 2.61 per + 1 mmol/l [95% CI 1.15-5.93]) and prepregnancy BMI (1.10 per +1 kg/m(2) [1.04-1.18]). The mother's higher fasting glycemia (P = 0.004), lower insulin sensitivity (P = 0.01), and lower insulin secretion (P = 0.02) were independently related to greater offspring adiposity at birth. During postnatal follow-up, the correlation between the mother's glycemia and offspring adiposity disappeared by 3 months, whereas prepregnancy BMI was associated with offspring adiposity that was only apparent at 12 and 24 months (both P < 0.05). CONCLUSIONS - Prepregnancy BMI, pregnancy glycemia, insulin sensitivity, and insulin secretion all contribute to offspring adiposity and macrosomia and may be separate targets for intervention to optimize birth outcomes and later offspring health.
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