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- Morales, J. C., et al.
(author)
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A giant exoplanet orbiting a very-low-mass star challenges planet formation models
- 2019
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 365:6460, s. 1441-1445
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Journal article (peer-reviewed)abstract
- Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.
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| 2. |
- Sebastian, D., et al.
(author)
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The EBLM project - IX. Five fully convective M-dwarfs, precisely measured with CHEOPS and TESS light curves
- 2023
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 519:3, s. 3546-3563
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Journal article (peer-reviewed)abstract
- Eclipsing binaries are important benchmark objects to test and calibrate stellar structure and evolution models. This is especially true for binaries with a fully convective M-dwarf component for which direct measurements of these stars' masses and radii are difficult using other techniques. Within the potential of M-dwarfs to be exoplanet host stars, the accuracy of theoretical predictions of their radius and effective temperature as a function of their mass is an active topic of discussion. Not only the parameters of transiting exoplanets but also the success of future atmospheric characterization relies on accurate theoretical predictions. We present the analysis of five eclipsing binaries with low-mass stellar companions out of a subsample of 23, for which we obtained ultra-high-precision light curves using the CHEOPS satellite. The observation of their primary and secondary eclipses are combined with spectroscopic measurements to precisely model the primary parameters and derive the M-dwarfs mass, radius, surface gravity, and effective temperature estimates using the PYCHEOPS data analysis software. Combining these results to the same set of parameters derived from TESS light curves, we find very good agreement (better than 1 percent for radius and better than 0.2 percent for surface gravity). We also analyse the importance of precise orbits from radial velocity measurements and find them to be crucial to derive M-dwarf radii in a regime below 5 percent accuracy. These results add five valuable data points to the mass-radius diagram of fully convective M-dwarfs.
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| 3. |
- Swayne,, et al.
(author)
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The EBLM project - VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves
- 2021
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 506:1, s. 306-322
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Journal article (peer-reviewed)abstract
- The accuracy of theoretical mass, radius, and effective temperature values for M-dwarf stars is an active topic of debate. Differences between observed and theoretical values have raised the possibility that current theoretical stellar structure and evolution models are inaccurate towards the low-mass end of the main sequence. To explore this issue, we use the CHEOPS satellite to obtain high-precision light curves of eclipsing binaries with low-mass stellar companions. We use these light curves combined with the spectroscopic orbit for the solar-type companion to measure the mass, radius, and effective temperature of the M-dwarf star. Here, we present the analysis of three eclipsing binaries. We use the pycheops data analysis software to fit the observed transit and eclipse events of each system. Two of our systems were also observed by the TESS satellite - we similarly analyse these light curves for comparison. We find consistent results between CHEOPS and TESS, presenting three stellar radii and two stellar effective temperature values of low-mass stellar objects. These initial results from our on-going observing programme with CHEOPS show that we can expect to have similar to 24 new mass, radius, and effective temperature measurements for very low-mass stars within the next few years.
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| 4. |
- Swayne, M.I., et al.
(author)
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The EBLM Project– XI. Mass, radius, and effective temperature measurements for 23 M-dwarf companions to solar-type stars observed with CHEOPS
- 2024
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In: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 528:4, s. 5703-5722
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Journal article (peer-reviewed)abstract
- Observations of low-mass stars have frequently shown a disagreement between observed stellar radii and radii predicted by theoretical stellar structure models. This ‘radius inflation’ problem could have an impact on both stellar and exoplanetary science. We present the final results of our observation programme with the CHaracterising ExOPlanet Satellite (CHEOPS) to obtain high-precision light curves of eclipsing binaries with low-mass stellar companions (EBLMs). Combined with the spectroscopic orbits of the solar-type companions, we can derive the masses, radii, and effective temperatures of 23 M-dwarf stars. We use the PYCHEOPS data analysis software to analyse their primary and secondary occultations. For all but one target, we also perform analyses with Transiting Exoplanet Survey Satellite (TESS) light curves for comparison. We have assessed the impact of starspot-induced variation on our derived parameters and account for this in our radius and effective temperature uncertainties using simulated light curves. We observe trends in inflation with both metallicity and orbital separation. We also observe a strong trend in the difference between theoretical and observational effective temperatures with metallicity. There is no such trend with orbital separation. These results are not consistent with the idea that the observed inflation in stellar radius combines with lower effective temperature to preserve the luminosity predicted by low-mass stellar models. Our EBLM systems provide high-quality and homogeneous measurements that can be used in further studies of radius inflation.
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| 5. |
- Kanstrup, Marie, et al.
(author)
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A simple cognitive task intervention to prevent intrusive memories after trauma in patients in the Emergency Department : A randomized controlled trial terminated due to COVID-19
- 2021
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In: BMC Research Notes. - : BioMed Central (BMC). - 1756-0500. ; 14:1
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Journal article (peer-reviewed)abstract
- ObjectiveThis randomised controlled trial (RCT) aimed to investigate the effects of a simple cognitive task intervention on intrusive memories ("flashbacks") and associated symptoms following a traumatic event. Patients presenting to a Swedish emergency department (ED) soon after a traumatic event were randomly allocated (1:1) to the simple cognitive task intervention (memory cue + mental rotation instructions + computer game "Tetris" for at least 20 min) or control (podcast, similar time). We planned follow-ups at one-week, 1-month, and where possible, 3- and 6-months post-trauma. Anticipated enrolment was N = 148.ResultsThe RCT was terminated prematurely after recruiting N = 16 participants. The COVID-19 pandemic prevented recruitment/testing in the ED because: (i) the study required face-to-face contact between participants, psychology researchers, ED staff, and patients, incurring risk of virus transmission; (ii) the host ED site received COVID-19 patients; and (iii) reduced flow of patients otherwise presenting to the ED in non-pandemic conditions (e.g. after trauma). We report on delivery of study procedures, recruitment, treatment adherence, outcome completion (primary outcome: number of intrusive memories during week 5), attrition, and limitations. The information presented and limitations may enable our group and others to learn from this terminated study.
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| 6. |
- Kanstrup, Marie, et al.
(author)
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Reducing intrusive memories after trauma via a brief cognitive task intervention in the hospital emergency department : an exploratory pilot randomised controlled trial
- 2021
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In: Translational Psychiatry. - : Springer Nature. - 2158-3188. ; 11:1
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Journal article (peer-reviewed)abstract
- Intrusive memories are common after trauma, and can cause significant distress. Interventions to prevent/reduce the occurrence of this core clinical feature of posttraumatic stress disorder are needed; they should be easy to deliver, readily disseminated and scalable. A novel one-session intervention by Iyadurai et al. 2018, Molecular Psychiatry, resulted in intrusion reduction over the subsequent week. Its feasibility in a different setting and longer-term effects (>1 month) need investigation. We conducted an exploratory open-label pilot randomised controlled trial (RCT) to investigate the feasibility and effects of a brief behavioural intervention to reduce intrusive memories in trauma-exposed patients in a Swedish hospital emergency department (ED). Participants (final N = 41) were randomly allocated to either intervention (including memory reminder cue then visuospatial cognitive task “Tetris” with mental rotation instructions) or active control (podcast) condition within 72 h of presenting to the ED (both conditions using their smartphone). Findings were examined descriptively. We estimated between-group effect sizes for the number of intrusive memories post-intervention at week 1 (primary outcome) and week 5 (secondary outcome). Compared to the control condition, participants in the intervention condition reported fewer intrusive memories of trauma, both at week 1 and week 5. Findings extend the previous evaluation in the UK. The intervention was readily implemented in a different international context, with a mixed trauma sample, with treatment gains maintained at 1 month and associated with some functional improvements. Findings inform future trials to evaluate the capacity of the cognitive task intervention to reduce the occurrence of intrusive memories after traumatic events.
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| 7. |
- Mody, Kabir, et al.
(author)
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A phase I study of the safety and tolerability of VLX600, an Iron Chelator, in patients with refractory advanced solid tumors
- 2019
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In: Investigational new drugs. - : SPRINGER. - 0167-6997 .- 1573-0646. ; 37:4, s. 684-692
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Journal article (peer-reviewed)abstract
- Introduction VLX600 is a novel iron chelator designed to interfere with intracellular iron metabolism, leading to inhibition of mitochondrial respiration and bioenergetic catastrophe and resultant tumor cell death. Methods We conducted a multicenter, phase 1, dose escalation study to determine the safety and adverse event profile and the maximum tolerated dose and recommended phase 2 dose of VLX600. Other endpoints included pharmacokinetics, and preliminary evidence of anti-cancer efficacy as assessed according to RECIST 1.1 criteria. VLX600 was administered intravenously on days 1, 8, and 15 of each 28-day treatment cycle. Results Nineteen patients were enrolled, and seventeen received at least one dose of VLX600. Dose increments were reduced to 50% after dose level 3 (40mg) due to the occurrence of a grade 3 pulmonary embolism. The study was then closed early due to slow recruitment. No maximum tolerated dose (MTD) nor RP2D had been identified at the time of study closure. Overall, the drug was well tolerated and no DLTs were observed. Fourteen patients experienced drug-related adverse events of any grade. The most frequently reported drug-related AEs were fatigue, nausea, constipation, vomiting, increased alkaline phosphatase, anemia, and decreased appetite. No formal efficacy or survival analyses were performed. No objective responses were observed, though six patients (32%) had stable disease as best response. Conclusion VLX600 was reasonably well tolerated and, together with preclinical data, there is support for further efforts to explore its activity as single agent and in combination with drugs or radiation.
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