32 research outputs found

    The Observational Effects and Signatures of Tidally Distorted Solid Exoplanets

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    Our work examines the detectability of tidally distorted solid exoplanets in synchronous rotation. Previous work has shown that tidally distorted shapes of close-in gas giants can give rise to radius underestimates and subsequently density overestimates for those planets. We examine the assumption that such an effect is too minimal for rocky exoplanets and find that for smaller M Class stars there may be an observationally significant tidal distortion effect at very close-in orbits. We quantify the effect for different stellar types and planetary properties using some basic assumptions. Finally, we develop a simple analytic expression to test if there are detectable bulge signatures in the photometry of a system. We find that close in for smaller M Class stars there may be an observationally significant signature that may manifest itself in both in-transit bulge signatures and ellipsoidal variations.Comment: 8 pages, 5 figures, accepted for publication in MNRA

    An improved method to measure head echoes using a meteor radar

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    We present an improved methodology to obtain absolute position and velocity of meteor head echoes, which can yield orbital information, generally limited to the use of High-Power, Large-Aperture radars, using an advanced-designed specular meteor radar. The observations, which were performed during a period when an outburst of the β-Taurid meteor shower was expected, were performed with the Southern Argentine Agile MEteor Radar. Three different methodologies are utilized to confirm our results: an improved interferometric solver building on previous work, and two different target localization techniques using remote receiving stations. In addition, we performed simultaneous optical observations during the meteor shower period. Overall, 71 radar head echo events were detected and analyzed using interferometry, while 12 of those events have detected signals strong enough to be analyzed using localization methods at the remote sites. Due to poor weather, however, the optical cameras only observed two events simultaneously with the radar. Results from these events are in agreement with the radar results. We find that interferometry methods from both radar and optical data resulted in the most accurate estimation of meteor properties, while target localization techniques derived similar results, albeit with larger uncertainty. We also computed heliocentric meteoroid orbits, and while a fraction was hyperbolic, we believe these to be due to uncertainty. Two events are suspected to be β-Taurid shower members

    Atomic Oxygen Retrieved From the SABER 2.0- and 1.6-μm Radiances Using New First-Principles Nighttime OH( v ) Model

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    The recently discovered fast, multiquantum OH(v)+O(³P) vibrational‐to‐electronic relaxation mechanism provided new insight into the OH(v) Meinel band nighttime emission formation. Using a new detailed OH(v) model and novel retrieval algorithm, we obtained O(³P) densities in the nighttime mesosphere and lower thermosphere (MLT) from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) 2.0‐ and 1.6‐μm radiances. We demonstrate how critical the new OH(v) relaxation mechanism is in the estimation of the abundance of O(³P) in the nighttime MLT. Furthermore, the inclusion of this mechanism enables us to reconcile historically large discrepancies with O(³P) results in the MLT obtained with different physical models and retrieval techniques from WIND Imaging Interferometer, Optical Spectrograph and Infrared Imager System, and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography observations of other airglow emissions. Whereas previous SABER O(³P) densities were up to 60% higher compared to other measurements the new retrievals agree with them within the range (±25%) of retrieval uncertainties. We also elaborate on the implications of this outcome for the aeronomy and energy budget of the MLT region

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

    Results of Meteor Head Echo Study

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    Modeling the CH4 3.3 µm non-LTE emissions in Jupiter and Saturn

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    International audienceThe homopause divides planetary atmospheres into the high-pressure region where chemical species are well mixed by eddy diffusion and the low-pressure region where molecular diffusion separates species according to their individual masses. In Jupiter and Saturn, the homopause pressure level controls the methane abundance vertical profile, as methane is heavier than the two dominant species, H<SUB>2</SUB> and He. Methane plays a critical role in establishing the thermal structure on these planets. It is the prime near-infrared absorber that warms the Jovian and Kronian upper atmospheres, and its photolysis by solar UV radiation triggers the production of ethane, acetylene, and heavier hydrocarbons that are the prime far-infrared coolants in these upper atmospheres. Hence the homopause level drives the heating rates, and, as ethane is mainly produced by the three-body methyl recombination (2CH<SUB>3</SUB> M -> C<SUB>2</SUB>H<SUB>6</SUB> M) whose reaction rate highly varies with pressure, the homopause level also controls the cooling rates. The determination of the methane homopause level in Jupiter and Saturn through solar occultations has been notoriously difficult as different studies and authors led to different results (see Moses et al. (2004), Fouchet et al. (2009) for reviews). Greathouse et al. (2010) even suggested that the Jovian homopause might vary spatially and/or temporally. Here we present a detailed non-LTE model of CH<SUB>4</SUB> 3.3 µm emissions for Jupiter and Saturn's atmosphere. The model accounts for various mechanisms of non-thermal excitation of CH<SUB>4</SUB> molecules as well as inter- and intra-molecular vibrational-vibrational (VV) and vibrational-translational (VT) energy exchanges. With the help of this model, we studied the sensitivity of CH<SUB>4</SUB> 3.3 µm emissions to the temperature and methane abundance vertical profiles and compared integrated radiances with the corresponding Infrared Space Observatory (ISO) observations. We will discuss implications of these results to the interpretation of the homopause pressure level as well as opportunities the JWST telescope will provide to map the homopause across both planets
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