8,249 research outputs found

    Proper motions of the HH1 jet

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    We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of ∼20\sim 20~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in ∼450\sim 450~yr and at a distance of ∼80"\sim 80" from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

    Using Syndromic Surveillance to Assess the Impact of Environmental Factors on Asthma- and COPD- Related ED Visits in Douglas County, Nebraska

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    Background: Asthma and chronic obstructive pulmonary disease (COPD) are chronic diseases associated with health disparities in Douglas County, Nebraska and in the United States. Currently there is a lack of information describing the impact of environmental factors in Nebraska on the burden of emergency department (ED) visits or hospitalizations related to these chronic respiratory (CR) diseases. The aim of this study was to determine if there is an association between the numbers of seasonal viral respiratory (SVR)- related ED visits, outdoor air pollutants, aeroallergens, or meteorological factors on the number of CR- related ED visits in Douglas County, Nebraska. Methods: We analyzed electronic health record (EHR) data from 8 of 9 hospitals in Douglas County, NE for ED visits from February 28, 2016 to December 29, 2018. Syndromic surveillance definitions were used to identify CR- and SVR- related ED visits in EHR ED data. Aeroallergen, outdoor air pollutant and temperature data were obtained. Descriptive statistics were performed on EHR and environmental data. Negative binomial models were used to determine the association between the number of CR- related weekly ED visits and the environmental factors of interest. These models were stratified to account for possible cofounding effect of patient age and season. Patient age was stratified into 3 age groups: \u3c 18 yrs., 18-39 yrs., ≥ 40 yrs. Results: Significant associations were observed between the number of CR- related weekly ED visits and the weekly number of SVR-related ED visits, mean weed pollen counts, mean mold spore counts, mean minimum temperature, mean carbon monoxide levels and mean fine particulate matter (PM2.5) levels. Discrepancies in significant associations between the CR- related weekly ED visits and the environmental variables were observed after stratifying the model by season and age groups. For instance, SVR-related weekly ED visits were significantly associated with an increase in CR-related weekly ED visits among the \u3c 18 yrs. and 18 to 39 yrs. age groups in the summer, the ≥ 40 yrs. age group in the fall, and the 18 to 39 yrs. and the ≥ 40 yrs. age groups in the winter. Minimum temperature was significantly associated with the increase in CR- related weekly ED visits among the \u3c 18 yrs. and 18 to 39 yrs. age groups in the fall. Significant associations with an increase in CR- related weekly ED visits were also observed for PM2.5 among the 18 to 39 yrs. and ≥ 40 yrs. age groups in the spring, and the \u3c 18 yrs. and ≥ 40 yrs. age groups in the fall. Weed pollen and mold spores were also significantly associated with an increase in CR- related weekly ED visits. While significant associations were observed for weed pollen during the summer among the \u3c 18 yrs. age group, significant associations were observed for mold spores among all age groups during spring, and among the ≥ 40 yrs. age group during summer. Carbon monoxide was associated with a decrease in CR-related weekly ED visits for the 18 to 39 yrs. age group in the fall. Conclusions: Results of this study indicate the association between environmental factors and CR- related ED visits in Douglas County, Nebraska could be affected by not only by SVR disease cycles, temperature and other environmental factors, but also by age. Additional analyses may be needed to further explore these associations

    Magnetic and magnetorheological properties of nanofiber suspensions

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    International audienceIn this work the preparation and characterization of magnetorheological (MR) fluids constituted by CoNi nanofibers (56 nm length, 6.6 nm width) are reported. The properties of these new fluids were characterized by usual techniques (including magnetometry and magnetorheology). The results were compared with those obtained for conventional suspensions constituted by CoNi nanosperes

    Near-Infrared Polarimetric Adaptive Optics Observations of NGC 1068: A torus created by a hydromagnetic outflow wind

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    We present J' and K' imaging linear polarimetric adaptive optics observations of NGC 1068 using MMT-Pol on the 6.5-m MMT. These observations allow us to study the torus from a magnetohydrodynamical (MHD) framework. In a 0.5" (30 pc) aperture at K', we find that polarisation arising from the passage of radiation from the inner edge of the torus through magnetically aligned dust grains in the clumps is the dominant polarisation mechanism, with an intrinsic polarisation of 7.0%±\pm2.2%. This result yields a torus magnetic field strength in the range of 4−-82 mG through paramagnetic alignment, and 139−20+11^{+11}_{-20} mG through the Chandrasekhar-Fermi method. The measured position angle (P.A.) of polarisation at K′' is found to be similar to the P.A. of the obscuring dusty component at few parsec scales using infrared interferometric techniques. We show that the constant component of the magnetic field is responsible for the alignment of the dust grains, and aligned with the torus axis onto the plane of the sky. Adopting this magnetic field configuration and the physical conditions of the clumps in the MHD outflow wind model, we estimate a mass outflow rate ≤\le0.17 M⊙_{\odot} yr−1^{-1} at 0.4 pc from the central engine for those clumps showing near-infrared dichroism. The models used were able to create the torus in a timescale of ≥\geq105^{5} yr with a rotational velocity of ≤\leq1228 km s−1^{-1} at 0.4 pc. We conclude that the evolution, morphology and kinematics of the torus in NGC 1068 can be explained within a MHD framework.Comment: 14 pages, 4 figures, Accepted by MNRA

    A novel application of entropy analysis for assessing changes in movement variability during cumulative tackles in young elite rugby league players

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    The aim of this study was to identify between-position (forwards vs. backs) differences in movement variability in cumulative tackle events training during both attacking and defensive roles. Eleven elite adolescent male rugby league players volunteered to participate in this study (mean ± SD, age; 18.5 ± 0.5 years, height; 179.5 ± 5.0 cm, body mass; 88.3 ± 13.0 kg). Participants performed a drill encompassing four blocks of six tackling (i.e. tackling an opponent) and six tackled (i.e. being tackled by an opponent while carrying a ball) events (i.e. 48 total tackles) while wearing a micro-technological inertial measurement unit (WIMU, Realtrack Systems, Spain). The acceleration data were used to calculate sample entropy (SampEn) to analyse the movement variability during tackles performance. In tackling actions SampEn showed significant between-position differences in block 1 (p = 0.0001) and block 2 (p = 0.0003). Significant between-block differences were observed in backs (block 1 vs 3, p = 0,0021; and block 1 vs 4, p = 0,0001) but not in forwards. When being tackled, SampEn showed significant between-position differences in block 1 (p = 0.0007) and block 3 (p = 0.0118). Significant between-block differences were only observed for backs in block 1 vs 4 (p = 0,0025). Movement variability shows a progressive reduction with cumulative tackle events, especially in backs and when in the defensive role (tackling). Forwards present lower movement variability values in all blocks, particularly in the first block, both in the attacking and defensive role. Entropy measures can be used by practitioners as an alternative tool to analyse the temporal structure of variability of tackle actions and quantify the load of these actions according to playing position

    A carbohydrate-binding protein, B-GRANULE CONTENT 1, influences starch granule size distribution in a dose-dependent manner in polyploid wheat

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    In Triticeae endosperm (e.g. wheat and barley), starch granules have a bimodal size distribution (with A- and B-type granules) whereas in other grasses the endosperm contains starch granules with a unimodal size distribution. Here, we identify the gene, BGC1 (B-GRANULE CONTENT 1), responsible for B-type starch granule content in Aegilops and wheat. Orthologues of this gene are known to influence starch synthesis in diploids such as rice, Arabidopsis, and barley. However, using polyploid Triticeae species, we uncovered a more complex biological role for BGC1 in starch granule initiation: BGC1 represses the initiation of A-granules in early grain development but promotes the initiation of B-granules in mid grain development. We provide evidence that the influence of BGC1 on starch synthesis is dose dependent and show that three very different starch phenotypes are conditioned by the gene dose of BGC1 in polyploid wheat: normal bimodal starch granule morphology; A-granules with few or no B-granules; or polymorphous starch with few normal A- or B-granules. We conclude from this work that BGC1 participates in controlling B-type starch granule initiation in Triticeae endosperm and that its precise effect on granule size and number varies with gene dose and stage of development
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