8 research outputs found

    Light Curves and Colors of the Ejecta from Dimorphos after the DART Impact

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    On 26 September 2022 the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, a satellite of the asteroid 65803 Didymos. Because it is a binary system, it is possible to determine how much the orbit of the satellite changed, as part of a test of what is necessary to deflect an asteroid that might threaten Earth with an impact. In nominal cases, pre-impact predictions of the orbital period reduction ranged from ~8.8 - 17.2 minutes. Here we report optical observations of Dimorphos before, during and after the impact, from a network of citizen science telescopes across the world. We find a maximum brightening of 2.29 ±\pm 0.14 mag upon impact. Didymos fades back to its pre-impact brightness over the course of 23.7 ±\pm 0.7 days. We estimate lower limits on the mass contained in the ejecta, which was 0.3 - 0.5% Dimorphos' mass depending on the dust size. We also observe a reddening of the ejecta upon impact.Comment: Accepted by Natur

    Raven Hydrological Modelling Framework

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    <p>This version has been improved with a handful of modelling features, new algorithms, quality checks on inputs, and minor bug fixes. Notably, the following features have been added:</p> <p>• New Models Added – full (level 1) emulation support for the HYMOD2 hydrological model (Roy et al., 2017). • Radiation/ET/Rain-snow partitioning Algorithms – added new algorithms for estimating PET, LW incoming radiation, and partitioning between rain and snow • Lake Freezing – simple treatment of lake freezing and snow accumulation on frozen lakes with the :LakeFreeze command • Improved Stream Temperature simulation – better handling of longwave radiation, support for sensible heat exchange and groundwater mixing during in-catchment routing , support for gridded rainfall temperature inputs, • Basic Model Interface (BMI) interoperability – Raven can now be compiled as a linked library and interface directly with other BMI-compliant applications • Other – correction factors for wind speed and relative humidity; Spearman ranked correlation coefficient diagnostic, improved support for EnKF in a FEWS environment, improved handling of orographic corrections when using gridded precipitation/temperature data, temperature bias correction, writing of reservoir mass balance file in netCDF format, some previously hard-coded parameters now exposed to users; support for multiple water demands from a single subbasin • Notable Bug Fixes – repairs to handling of daily-averaged PET estimates, default estimation of longwave radiation, handling lake evaporation when :HRUID not supplied to reservoir, fix to rainfall on reservoirs when :LakeStorage is something other than SURFACE_WATER, repair of reservoir stage assimilation via direct insertion, fixes of netCDF issues when elevation attributes are provided • Improvements/updates to the Raven documentation and to Raven input quality checking.</p&gt

    Reliability of routinely collected anthropometric measurements in primary care

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    Background Measuring body mass index (BMI) has been proposed as a method of screening for preventive primary care and population surveillance of childhood obesity. However, the accuracy of routinely collected measurements has been questioned. The purpose of this study was to assess the reliability of height, length and weight measurements collected during well-child visits in primary care relative to trained research personnel. Methods A cross-sectional study of measurement reliability was conducted in community pediatric and family medicine primary care practices. Each participating child, ages 0 to 18 years, was measured four consecutive times; twice by a primary care team member (e.g. nurses, practice personnel) and twice by a trained research assistant. Inter- and intra-observer reliability was calculated using the technical error of measurement (TEM), relative TEM (%TEM), and a coefficient of reliability (R). Results Six trained research assistants and 16 primary care team members performed measurements in three practices. All %TEM values for intra-observer reliability of length, height, and weight were classified as ‘acceptable’ ( 99% for both intra- and inter-observer reliability. Length measurements in children Conclusion There was agreement between routine measurements and research measurements although there were some differences in length measurement reliability between practice staff and research assistants. These results provide justification for using routinely collected data from selected primary care practices for secondary purposes such as BMI population surveillance and research.</p

    Maternal ethnicity and iron status in early childhood in Toronto, Canada: a cross-sectional study

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    Objectives This study aimed to evaluate the association between maternal ethnicity and iron deficiency (ID) in early childhood, and to evaluate whether infant feeding practices linked to ID differ between maternal ethnic groups.Methods This was a cross-sectional study of healthy children 1–3 years of age. Adjusted multivariable logistic regression analyses were used to evaluate the association between maternal ethnicity and ID (serum ferritin &lt;12 µg/L) and the association between maternal ethnicity and five infant feeding practices (breastfeeding duration; bottle use beyond 15 months; current formula use; daily cow’s milk intake &gt;2 cups; meat consumption).Results Of 1851 children included, 12.2% had ID. Compared with the European referent group, we found higher odds of ID among children of South Asian and West Asian/North African maternal ethnicities, and lower odds of ID among children of East Asian maternal ethnicity. Statistically significant covariates associated with higher odds of ID included longer breastfeeding duration and daily cow’s milk intake &gt;2 cups. Current infant formula use was associated with lower odds of ID. Children of South Asian maternal ethnicity had higher odds of bottle use beyond 15 months of age and lower odds of meat consumption.Conclusions We found increased odds of ID among children of South Asian and West Asian/Northern African maternal ethnicities. We found a higher odds of feeding practices linked to ID in children of South Asian maternal ethnicity, but not in children of West Asian/North African maternal ethnicity. Culturally tailored approaches to providing guidance to parents on healthy infant feeding practices may be important to prevent ID in early childhood.Trial registration number NCT01869530

    Prospective cohort study of vitamin D and autism spectrum disorder diagnoses in early childhood

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