| 1. |
- Marcaide, J. M., et al.
(författare)
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Discovery of shell-like radio-structure in SN1993J
- 1995
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Ingår i: Nature. - London : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 373:6509, s. 44-45
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Tidskriftsartikel (refereegranskat)abstract
- SUPERNOVA explosions are poorly understood, partly because of difficulties in modelling them theoretically(1), and partly because there have been no supernovae observed in our Galaxy since the invention of the telescope. But the recent discovery(2) of supernova SN1993J in the nearby galaxy M81 offers an opportunity to investigate the evolution of the remnant, and its interaction with the surrounding interstellar medium, at high resolution. Here we present radio observations of SN1993J, made using very-long-baseline interferometry, which show the development of a shell structure. This 8-month-old radio shell is the youngest ever discovered in a supernova. The data suggest that the supernova explosion and the expanding shell of the remnant have nearly spherical symmetry, with small deviations where some parts of the shell are brighter than others. If these deviations arise because of variations in the density of the shell, this may reconcile earlier reports of symmetric radio emission(3) with the observed optical asymmetry(4,5), as the density variations could easily cause the latter. We infer that the radio emission is generated at the interface(6-9), where the surrounding gas is shocked by the ejecta.
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| 2. |
- Jones, D. L., et al.
(författare)
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High dynamic range VLBI observations of NGC 6251
- 1986
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Ingår i: Astrophysical Journal. - Philadelphia, United States : Institute of Physics Publishing, Inc. - 0004-637X .- 1538-4357. ; 305:2, s. 684-697
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Sutton, M. A., et al.
(författare)
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Dynamics of ammonia exchange with cut grassland : Strategy and implementation of the GRAMINAE Integrated Experiment
- 2009
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Ingår i: Biogeosciences. - : Copernicus Publications (on behalf of the European Geosciences Union). - 1726-4170 .- 1726-4189. ; 6:3, s. 309-331
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Tidskriftsartikel (refereegranskat)abstract
- A major international experiment on ammonia (NH3) biosphere-atmosphere exchange was conducted over intensively managed grassland at Braunschweig, Germany. The experimental strategy was developed to allow an integrated analysis of different features of NH3 exchange including: a) quantification of nearby emissions and advection effects, b) estimation of net NH3 fluxes with the canopy by a range of micrometeorological measurements, c) analysis of the sources and sinks of NH3 within the plant canopy, including soils and bioassay measurements, d) comparison of the effects of grassland management options on NH3 fluxes and e) assessment of the interactions of NH3 fluxes with aerosol exchange processes. Additional technical objectives included the inter-comparison of different estimates of sensible and latent heat fluxes, as well as continuous-gradient and Relaxed Eddy Accumulation (REA) systems for NH3 fluxes. The prior analysis established the spatial and temporal design of the experiment, allowing significant synergy between these objectives. The measurements were made at 7 measurement locations, thereby quantifying horizontal and vertical profiles, and covered three phases: a) tall grass canopy prior to cutting (7 days), b) short grass after cutting (7 days) and c) re-growing sward following fertilization with ammonium nitrate (10 days). The sequential management treatments allowed comparison of sources-sinks, advection and aerosol interactions under a wide range of NH3 fluxes. This paper describes the experimental strategy and reports the grassland management history, soils, environmental conditions and air chemistry during the experiment, finally summarizing how the results are coordinated in the accompanying series of papers.
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| 4. |
- Herrmann, B., et al.
(författare)
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Vertical structure and diurnal variability of ammonia exchange potential within an intensively managed grass canopy
- 2009
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Ingår i: Biogeosciences. - Kaltenburg-Lindau : Copernicus on behalf of the European Geosciences Union. - 1726-4170 .- 1726-4189. ; 6:1, s. 15-23
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal ammonia compensation points (χs) of grass species on a mixed fertilized grassland were determined by measurements of apoplastic [NH4+] and [H>+] in the field. Calculated χs values were compared with in-canopy atmospheric NH3 concentration (χa) measurements.Leaf apoplastic [NH4+] increased by a factor of two from the lowest level in the canopy to the top level. Bulk leaf [NH4+] and especially [NO3−] slightly increased at the bottom of the canopy and these concentrations were very high in senescent plant litter. Calculated χs values were below atmospheric χs at all canopy levels measured, indicating that the grassland was characterized by NH3 deposition before cutting. This was confirmed by the χa profile, showing the lowest χa close to the ground (15 cm above soil surface) and an increase in χa with canopy height. Neither χs nor χa could be measured close to the soil surface, however, the [NH4+] in the litter material indicated a high potential for NH3 emission.A diurnal course in apoplastic [NH4+] was seen in the regrowing grass growing after cutting, with highest concentration around noon. Both apoplastic and tissue [NH4+] increased in young grass compared to tall grass. Following cutting, in-canopy gradients of atmospheric χa showed NH3 emission but since calculated χs values of the cut grass were still lower than atmospheric NH3 concentrations, the emissions could not entirely be explained by stomatal NH3 loss. High tissue [NH4+] in the senescent plant material indicated that this fraction constituted an NH3 source. After fertilization, [NH4+] increased both in apoplast and leaf tissue with the most pronounced increase in the former compared to the latter. The diurnal pattern in apoplastic [NH4+] was even more pronounced after fertilization and calculated χs values were generally higher, but remained below atmospheric [NH3].
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| 5. |
- Mattsson, Marie, et al.
(författare)
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Contribution of different grass species to plant-atmosphere ammonia exchange in intensively managed grassland
- 2009
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Ingår i: Biogeosciences. - Kaltenburg-Lindau : European Geosciences Union. - 1726-4170 .- 1726-4189. ; 6:1, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- Species diversity in grasslands usually declines with increasing input of nitrogen from fertilizers or atmospheric deposition. Conversely, species diversity may also impact the build-up of soil and plant nitrogen pools. One important pool is NH3/NH4+ which also can be exchanged between plant leaves and the atmosphere. Limited information is available on how plant-atmosphere ammonia exchange is related to species diversity in grasslands. We have here investigated grass species abundance and different foliar nitrogen pools in 4-year-old intensively managed grassland. Apoplastic pH and NH4+ concentrations of the 8 most abundant species (Lolium perenne, Phleum pratense, Festuca pratensis, Lolium multiflorum, Poa pratensis, Dactylis glomerata, Holcus lanatus, Bromus mollis) were used to calculate stomatal NH3 compensation points. Apoplastic NH4+ concentrations differed considerably among the species, ranging from 13 to 117 μM, with highest values in Festuca pratensis. Also apoplastic pH values varied, from pH 6.0 in Phleum pratense to 6.9 in Dactylis glomerata. The observed differences in apoplastic NH4+ and pH resulted in a large span of predicted values for the stomatal NH3 compensation point which ranged between 0.20 and 6.57 nmol mol−1. Three species (Lolium perenne, Festuca pratensis and Dactylis glomerata) had sufficiently high NH3 compensation point and abundance to contribute to the bi-directional NH3 fluxes recorded over the whole field. The other 5 grass species had NH3 compensation points considerably below the atmospheric NH3 concentration and were thus not likely to contribute to NH3 emission but only to NH3 uptake from the atmosphere. Evaluated across species, leaf bulk-tissue NH4+ concentrations correlated well (r2=0.902) with stomatal NH3 compensation points calculated on the basis of the apoplastic bioassay. This suggests that leaf tissue NH4+ concentrations combined with data for the frequency distribution of the corresponding species can be used for predicting the NH3 exchange potential of a mixed grass sward.
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| 6. |
- Mawhinney, C., et al.
(författare)
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Changes in quadriceps femoris muscle perfusion following different degrees of cold-water immersion
- 2020
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Ingår i: Journal of applied physiology. - Rockville : American Physiological Society. - 8750-7587 .- 1522-1601. ; 128:5, s. 1392-1401
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Tidskriftsartikel (refereegranskat)abstract
- We examined the influence of graded cold-water immersion (CWI) on global and regional quadriceps muscle perfusion with positron emission tomography (PET) and [15O]H2O. In 30 healthy men [33 ± 8 yr; 81 ± 10 kg; 184 ± 5 cm; percentage body fat: 13 ± 5%; peak oxygen uptake (VO2peak): 47 ± 8 mL·kg-1·min-1] quadriceps perfusion, thigh and calf cutaneous vascular conductance (CVC), intestinal, muscle, and local skin temperatures, thermal comfort, mean arterial pressure, and heart rate were assessed before and after 10 min of CWI at 8°C, 15°C, or 22°C. Global quadriceps perfusion did not change beyond a clinically relevant threshold (0.75 mL·100 g·min-1) in any condition and was similar between conditions {range of differences [95% confidence interval (CI)]: 0.1 mL·100 g·min-1 (-0.9 to 1.2 mL·100 g·min-1) to 0.9 mL·100 g·min-1 (-0.2 to 1.9 mL·100 g·min-1)}. Muscle perfusion was greater in vastus intermedius (VI) compared with vastus lateralis (VL) (2.2 mL·100 g·min-1; 95% CI 1.5 to 3.0 mL·100 g·min-1) and rectus femoris (RF) (2.2 mL·100 g·min-1; 1.4 to 2.9 mL·100 g·min-1). A clinically relevant increase in VI muscle perfusion after immersion at 8°C and a decrease in RF muscle perfusion at 15°C were observed. A clinically relevant increase in perfusion was observed in VI in 8°C compared with 22°C water (2.3 mL·100 g·min-1; 1.1 to 3.5 mL·100 g·min-1). There were no clinically relevant between-condition differences in thigh CVC. Our findings suggest that CWI (8-22°C) does not reduce global quadriceps muscle perfusion to a clinically relevant extent; however, colder water increases (8°C) deep muscle perfusion and reduces (15°C) superficial muscle (RF) perfusion in the quadriceps muscle. NEW & NOTEWORTHY Using positron emission tomography, we report for the first time muscle perfusion heterogeneity in the quadriceps femoris in response to different degrees of cold-water immersion (CWI). Noxious CWI temperatures (8°C) increase perfusion in the deep quadriceps muscle, whereas superficial quadriceps muscle perfusion is reduced in cooler (15°C) water. Therefore, these data have important implications for the selection of CWI approaches used in the treatment of soft tissue injury, while also increasing our understanding of the potential mechanisms underpinning CWI. Copyright © 2020 the American Physiological Society.
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| 7. |
- Rohde, Mitchell M., et al.
(författare)
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An Interactive, physics-based unmanned ground vehicle simulator leveraging open source gaming technology : Progress in the development and application of the virtual autonomous navigation environment (VANE) desktop
- 2009
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Ingår i: Unmanned Systems Technology XI. - Bellingham, WA : SPIE - International Society for Optical Engineering. - 9780819475985 ; , s. Article number 73321C-
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Konferensbidrag (refereegranskat)abstract
- It is widely recognized that simulation is pivotal to vehicle development, whether manned or unmanned. There are few dedicated choices, however, for those wishing to perform realistic, end-to-end simulations of unmanned ground vehicles (UGVs). The Virtual Autonomous Navigation Environment (VANE), under development by US Army Engineer Research and Development Center (ERDC), provides such capabilities but utilizes a High Performance Computing (HPC) Computational Testbed (CTB) and is not intended for on-line, real-time performance. A product of the VANE HPC research is a real-time desktop simulation application under development by the authors that provides a portal into the HPC environment as well as interaction with wider-scope semi-automated force simulations (e.g. OneSAF). This VANE desktop application, dubbed the Autonomous Navigation Virtual Environment Laboratory (ANVEL), enables analysis and testing of autonomous vehicle dynamics and terrain/obstacle interaction in real-time with the capability to interact within the HPC constructive geo-environmental CTB for high fidelity sensor evaluations. ANVEL leverages rigorous physics-based vehicle and vehicle-terrain interaction models in conjunction with high-quality, multimedia visualization techniques to form an intuitive, accurate engineering tool. The system provides an adaptable and customizable simulation platform that allows developers a controlled, repeatable testbed for advanced simulations. ANVEL leverages several key technologies not common to traditional engineering simulators, including techniques from the commercial video-game industry. These enable ANVEL to run on inexpensive commercial, off-the-shelf (COTS) hardware. In this paper, the authors d escribe key aspects of ANVEL and its development, as well as several initial applications of the system. © 2009 SPIE.
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| 8. |
- Bennett, Sarah E., et al.
(författare)
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Assessing acceptability and identifying barriers and facilitators to implementation of the EULAR recommendations for patient education in inflammatory arthritis : a mixed-methods study with rheumatology professionals in 23 European and Asian countries
- 2022
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ Publishing Group Ltd. - 0003-4967 .- 1468-2060. ; 81:10, s. 1348-1357
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To disseminate and assess the level of acceptability and applicability of the European Alliance of Associations for Rheumatology (EULAR) recommendations for patient education among professionals in rheumatology across Europe and three Asian countries and identify potential barriers and facilitators to their application. Methods: A parallel convergent mixed-methods design with an inductive approach was used. A web-based survey, available in 20 different languages, was distributed to health professionals by non-probability sampling. The level of agreement and applicability of each recommendation was assessed by (0-10) rating scales. Barriers and facilitators to implementation were assessed using free-text responses. Quantitative data were analysed descriptively and qualitative data by content analysis and presented in 16 categories supported by quotes. Results: A total of 1159 completed the survey; 852 (73.5%) were women. Most of the professionals were nurses (n=487), rheumatologists (n=320), physiotherapists (n=158). For all recommendations, the level of agreement was high but applicability was lower. The four most common barriers to application were lack of time, lack of training in how to provide patient education, not having enough staff to perform this task and lack of evaluation tools. The most common facilitators were tailoring patient education to individual patients, using group education, linking patient education with diagnosis and treatment and inviting patients to provide feedback on patient education delivery.Conclusions: This project has disseminated the EULAR recommendations for patient education to health professionals across 23 countries. Potential barriers to their application were identified and some are amenable to change, namely training patient education providers and developing evaluation tools. © Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.
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| 9. |
- Mawhinney, Chris, et al.
(författare)
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Cool-Water Immersion Reduces Postexercise Quadriceps Femoris Muscle Perfusion More Than Cold-Water Immersion
- 2022
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Ingår i: Medicine & Science in Sports & Exercise. - Philadelphia, PA : Lippincott Williams & Wilkins. - 0195-9131 .- 1530-0315. ; 54:7, s. 1085-1094
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The muscle perfusion response to postexercise cold-water immersion (CWI) is not well understood. We examined the effects of graded postexercise CWI upon global and regional quadriceps femoris muscle perfusion using positron emission tomography and [15O]H2O. Methods: Using a matched-group design, 30 healthy men performed cycle ergometer exercise at 70% VO2peak to a core body temperature of 38°C, followed by either 10 min of CWI at 8°C, 22°C, or seated rest (control). Quadriceps muscle perfusion; thigh and calf cutaneous vascular conductance; intestinal, muscle, and local skin temperatures; thermal comfort; mean arterial pressure; and heart rate were assessed at preexercise, postexercise, and after CWI. Results: Global quadriceps perfusion was reduced beyond the predefined minimal clinically relevant threshold (0.75 mL per 100 g·min-1) in 22°C water versus control (difference (95% confidence interval (CI)), -2.5 (-3.9 to -1.1) mL per 100 g·min-1). Clinically relevant decreases in muscle perfusion were observed in the rectus femoris (-2.0 (-3.0 to -1.0) mL per 100 g·min-1) and vastus lateralis (-3.5 (-4.9 to -2.0) mL per 100 g·min-1) in 8°C water, and in the vastus lateralis (-3.3 (-4.8 to -1.9) mL per 100 g·min-1) in 22°C water versus control. The mean effects for vastus intermedius and vastus medialis perfusion were not clinically relevant. Clinically relevant decreases in thigh and calf cutaneous vascular conductance were observed in both cooling conditions. Conclusions: The present findings revealed that less noxious CWI (22°C) promoted clinically relevant postexercise decreases in global quadriceps muscle perfusion, whereas noxious cooling (8°C) elicited no effect. © Lippincott Williams & Wilkins
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