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53 result(s) for "Anders Erikson"
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Transit detection of the long-period volatile-rich super-Earth nu(2) Lupi d with CHEOPS
Exoplanets transiting bright nearby stars are key objects for advancing our knowledge of planetary formation and evolution. The wealth of photons from the host star gives detailed access to the atmospheric, interior and orbital properties of the planetary companions. nu(2) Lupi (HD 136352) is a naked-eye (V = 5.78) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6 and 107.6 d via radial-velocity monitoring(1). The two inner planets (b and c) were recently found to transit(2), prompting a photometric follow-up by the brand new Characterising Exoplanets Satellite (CHEOPS). Here, we report that the outer planet d is also transiting, and measure its radius and mass to be 2.56 +/- 0.09 R-circle plus and 8.82 +/- 0.94 M-circle plus, respectively. With its bright Sun-like star, long period and mild irradiation (similar to 5.7 times the irradiation of Earth), nu(2) Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization. We refine the properties of all three planets: planet b probably has a rocky mostly dry composition, while planets c and d seem to have retained small hydrogen-helium envelopes and a possibly large water fraction. This diversity of planetary compositions makes the nu(2) Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.
PLATO’s signal and noise budget
ESA’s PLATO mission aims the detection and characterization of terrestrial planets around solar-type stars as well as the study of host star properties. The noise-to-signal ratio (NSR) is the main performance parameter of the PLATO instrument, which consists of 24 Normal Cameras and 2 Fast Cameras. In order to justify, verify and breakdown NSR-relevant requirements the software simulator PINE was developed. PINE models the signal pathway from a target star to the digital output of a camera based on physical models and considers the major noise contributors. In this paper, the simulator’s coarse mode is introduced which allows fast performance analyses on instrument level. The added value of PINE is illustrated by exemplary applications.
Leg stiffness measures depend on computational method
Leg stiffness is often computed from ground reaction force (GRF) registrations of vertical hops to estimate the force-resisting capacity of the lower-extremity during ground contact, with leg stiffness values incorporated in a spring–mass model to describe human motion. Individual biomechanical characteristics, including leg stiffness, were investigated in 40 healthy males. Our aim is to report and discuss the use of 13 different computational methods for evaluating leg stiffness from a double-legged repetitive hopping task, using only GRF registrations. Four approximations for the velocity integration constant were combined with three mathematical expressions, giving 12 methods for computing stiffness using double integrations. One frequency-based method that considered ground contact times was also trialled. The 13 methods thus defined were used to compute stiffness in four extreme cases, which were the stiffest, and most compliant, consistent and variable subjects. All methods provided different stiffness measures for a given individual, but the between-method variations in stiffness were consistent across the four atypical subjects. The frequency-based method apparently overestimated the actual stiffness values, whereas double integrations’ measures were more consistent. In double integrations, the choice of the integration constant and mathematical expression considerably affected stiffness values, as variations during hopping were more or less emphasized. Stating a zero centre of mass position at take-off gave more consistent results, and taking a weighted-average of the force or displacement curve was more forgiving to variations in performance. In any case, stiffness values should always be accompanied by a detailed description of their evaluation methods, as our results demonstrated that computational methods affect calculated stiffness.
The Berlin Exoplanet Search Telescope System
We describe a small telescope system, the Berlin Exoplanet Search Telescope (BEST), dedicated to the search for planetary transits of Jupiter‐sized planets on close‐in orbits. This system consists of a commercial 20 cm telescope equipped with a \\documentclass{aastex} \\usepackage{amsbsy} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{bm} \\usepackage{mathrsfs} \\usepackage{pifont} \\usepackage{stmaryrd} \\usepackage{textcomp} \\usepackage{portland,xspace} \\usepackage{amsmath,amsxtra} \\usepackage[OT2,OT1]{fontenc} \\newcommand\\cyr{ \\renewcommand\\rmdefault{wncyr} \\renewcommand\\sfdefault{wncyss} \\renewcommand\\encodingdefault{OT2} \\normalfont \\selectfont} \\DeclareTextFontCommand{\\textcyr}{\\cyr} \\pagestyle{empty} \\DeclareMathSizes{10}{9}{7}{6} \\begin{document} \\landscape $2048\\times 2048$ \\end{document} pixel CCD. Observations have been performed for almost 2 years, including a commissioning phase and regular observations. Planetary transit candidates have been found and followed further with radial velocity measurements. One example is discussed here: transit events detected around GSC 3566‐1556 have been identified as being caused by a binary system consisting of a G0 V primary orbited by an M star. The radii of both stars have been determined.
Management of neuronopathic Gaucher disease: Revised recommendations
The original guidelines drawn up for the management of the neuronopathic forms of Gaucher disease were felt to be in need of revision; in particular, the role of high-dose enzyme replacement therapy (120 IU/kg of body weight every 2 weeks) in stabilizing neurological disease. The existing published evidence was analysed; it was concluded that it did not support the role of high-dose ERT, although this might be required to treat severe visceral disease.
Prospects of Long-Time-Series Observations from Dome C for Transit Search
The detection of transiting extrasolar planets requires high-photometric quality and long-duration photometric stellar time series. In this paper, we investigate the advantages provided by the Antarctic observing platform Dome C for planet transit detections during its long winter period, which allows for relatively long uninterrupted time series. Our calculations include limiting effects due to the Sun and Moon, cloud coverage, and the effect of reduced photometric quality for high extinction of target fields. We compare the potential for long time series from Dome C with a single site in Chile, a three-site low-latitude network as well as combinations of Dome C with Chile and the network, respectively. Dome C is one of the prime astronomical sites on Earth for obtaining uninterrupted long-duration observations in terms of prospects for a high observational duty cycle. The duty cycle of a project can, however, be significantly improved by integrating Dome C into a network of sites.
Transit detection of the long-period volatile-rich super-Earth \\nu^2 Lupi d with CHEOPS
Exoplanets transiting bright nearby stars are key objects for advancing our knowledge of planetary formation and evolution. The wealth of photons from the host star gives detailed access to the atmospheric, interior, and orbital properties of the planetary companions. $\\nu^2$ Lupi (HD 136352) is a naked-eye ($V = 5.78$) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6, and 107.6 days via radial velocity monitoring (Udry et al. 2019). The two inner planets (b and c) were recently found to transit (Kane et al. 2020), prompting a photometric follow-up by the brand-new $CHaracterising\\:ExOPlanets\\:Satellite\\:(CHEOPS)$. Here, we report that the outer planet d is also transiting, and measure its radius and mass to be $2.56\\pm0.09$ $R_{\\oplus}$ and $8.82\\pm0.94$ $M_{\\oplus}$, respectively. With its bright Sun-like star, long period, and mild irradiation ($\\sim$5.7 times the irradiation of Earth), $\\nu^2$ Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization. We refine the properties of all three planets: planet b likely has a rocky mostly dry composition, while planets c and d seem to have retained small hydrogen-helium envelopes and a possibly large water fraction. This diversity of planetary compositions makes the $\\nu^2$ Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.
Ataxia, autism, and the cerebellum: a clinical study of 32 individuals with congenital ataxia
The suggested link between autism and cerebellar dysfunction formed the background for a Swedish clinical study in 2001. Thirty-two children (17 females, 15 males; mean age 12y, SD 3y 10mo; range 6 to 21y) with a clinical suspicion of non-progressive congenital ataxia were examined, and parents were interviewed about the presence of neuropsychiatric problems in the child. Twelve children had simple ataxia, eight had ataxic diplegia, and 12 had ‘borderline’ ataxia. All but one of the 32 children had a mild to moderate gross motor disability according to Gross Motor Function Classification System (15 were categorized as level I, 16 as level II, and one child as level IV). Neuroimaging and neuropsychological testing were achieved in most cases. There was a strong association between learning disability and autism spectrum disorder (often combined with hyperactivity disorder) on the one hand, and both simple and borderline ‘ataxia’ on the other, but a weaker link between ataxic diplegia and neuropsychiatric disorders. A correlation between cerebellar macropathology on neuroimaging and neuropsychiatric disorders was not supported. Congenital ataxia might not be a clear-cut syndrome of cerebellar disease, but one of many signs of prenatal events or syndromes, leading to a complex neurodevelopmental disorder including autism and learning disability.
Next Generation Transit Survey (NGTS)
The Next Generation Transit Survey (NGTS) is a new ground-based survey for transiting exoplanets. Our primary goal is to find the first statistically-significant sample of Neptunes and super-Earths that are bright enough for radial velocity confirmation. By measuring precise masses and radii we will constrain the bulk composition and internal structure of planets that span the transition between the gas giants and terrestrial planets. Our brightest exoplanets will also be suitable for atmospheric characterisation with large facilities such as the VLT, JWST and the E-ELT. NGTS construction began in June 2013, and the survey is due to commence in 2014.
Ataxia, autism, and the cerebellum: a clinical study of 32 individuals with congenital ataxia
The suggested link between autism and cerebellar dysfunction formed the background for a Swedish clinical study in 2001. Thirty‐two children (17 females, 15 males; mean age 12y, SD 3y 10mo; range 6 to 21y) with a clinical suspicion of non‐progressive congenital ataxia were examined, and parents were interviewed about the presence of neuropsychiatric problems in the child. Twelve children had simple ataxia, eight had ataxic diplegia, and 12 had‘borderline’ataxia. All but one of the 32 children had a mild to moderate gross motor disability according to Gross Motor Function Classification System (15 were categorized as level I,16 as level II, and one child as level IV). Neuroimaging and neuropsychological testing were achieved in most cases. There was a strong association between learning disability* and autism spectrum disorder (often combined with hyperactivity disorder) on the one hand, and both simple and borderline‘ataxia’on the other, but a weaker link between ataxic diplegia and neuropsychiatric disorders. A correlation between cerebellar macropathology on neuroimaging and neuropsychiatric disorders was not supported. Congenital ataxia might not be a clear‐cut syndrome of cerebellar disease, but one of many signs of prenatal events or syndromes, leading to a complex neurodevelopmental disorder including autism and learning disability.