| 1. |
- Heywood, I., et al.
(författare)
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Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event
- 2019
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 573:7773, s. 235-237
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Tidskriftsartikel (refereegranskat)abstract
- The Galactic Centre contains a supermassive black hole with a mass of four million Suns1 within an environment that differs markedly from that of the Galactic disk. Although the black hole is essentially quiescent in the broader context of active galactic nuclei, X-ray observations have provided evidence for energetic outbursts from its surroundings2. Also, although the levels of star formation in the Galactic Centre have been approximately constant over the past few hundred million years, there is evidence of increased short-duration bursts3, strongly influenced by the interaction of the black hole with the enhanced gas density present within the ring-like central molecular zone4 at Galactic longitude |l| < 0.7 degrees and latitude |b| < 0.2 degrees. The inner 200-parsec region is characterized by large amounts of warm molecular gas5, a high cosmic-ray ionization rate6, unusual gas chemistry, enhanced synchrotron emission7,8, and a multitude of radio-emitting magnetized filaments9, the origin of which has not been established. Here we report radio imaging that reveals a bipolar bubble structure, with an overall span of 1 degree by 3 degrees (140 parsecs × 430 parsecs), extending above and below the Galactic plane and apparently associated with the Galactic Centre. The structure is edge-brightened and bounded, with symmetry implying creation by an energetic event in the Galactic Centre. We estimate the age of the bubbles to be a few million years, with a total energy of 7 × 1052 ergs. We postulate that the progenitor event was a major contributor to the increased cosmic-ray density in the Galactic Centre, and is in turn the principal source of the relativistic particles required to power the synchrotron emission of the radio filaments within and in the vicinity of the bubble cavities.
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| 2. |
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| 3. |
- Carney, J., et al.
(författare)
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Development of the International Spinal Cord Injury/Dysfunction Education Basic Data Set
- 2019
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Ingår i: Spinal cord series and cases. - : Nature Publishing Group. - 2058-6124. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Study design:Consensus among international experts.Objectives: The objective of this project was to develop the International Spinal Cord Injury/Dysfunction (SCI/D) Education Basic Data Set. Setting: International expert working group.Methods: The published guidelines for developing the International SCI Basic Data Sets were used to develop the International SCI/D Education Basic Data Set. Existing measures and literature on education and disability were reviewed to develop a preliminary draft of the basic education data set through iterative modifications via biweekly conference calls and email communication. The draft was disseminated to the larger International Workgroup for Development of Pediatric SCI/D Basic Data Sets and then to the members of the International Spinal Cord Society (ISCoS), American Spinal Injury Association (ASIA), and relevant expert groups and interested individuals for comments. All feedback received was taken into consideration before the final data set was approved by ISCoS and ASIA.Results: The finalized version of the International SCI/D Education Basic Data Set Version 1.0 contains 16 items divided into three domains: school setting/therapeutic services, school participation/academic success, and barriers/attitudes. Most of the variables have been adapted from established measures. This data set is intended for children and youth up to and including high school, but not for emerging adults in higher education or postsecondary vocational training or trade schools.Conclusion: The International SCI/D Education Basic Data Set has been developed for collection of a minimal amount of highly relevant information on the education experience in children and youth with SCI/D. Further validation work is needed.Sponsorship: This project was funded by the Rick Hansen Institute, Research Award #G2015-27 (Mulcahey, PI).
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| 4. |
- Niederberger, C., et al.
(författare)
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Forty years of IVF
- 2018
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Ingår i: Fertility and Sterility. - : Elsevier BV. - 0015-0282. ; 110:2
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Tidskriftsartikel (refereegranskat)abstract
- This monograph, written by the pioneers of IVF and reproductive medicine, celebrates the history, achievements, and medical advancements made over the last 40 years in this rapidly growing field.
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| 5. |
- Wei, X. F., et al.
(författare)
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Mitigation of under-expanded supersonic jet noise through stepped nozzles
- 2019
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Ingår i: Journal of Sound and Vibration. - : Academic Press. - 0022-460X .- 1095-8568. ; 459
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Tidskriftsartikel (refereegranskat)abstract
- An experimental investigation into noise reduction of supersonic jets through nozzle trailing-edge modifications was conducted, whereby far-field acoustic measurements were captured for two different stepped nozzles under two distinct under-expanded conditions. When compared to a baseline nozzle, results show that stepped nozzles lead to significant noise reductions at certain polar and azimuthal angles. In particular, a maximum noise reduction of 6 dB is observed for the longest stepped nozzle at a nozzle-pressure-ratio of 4 and 0 degrees azimuthal angle. Spectral analysis shows that the noise reduction is mainly due to reduction in broadband shock associated noise and elimination of jet screech phenomenon. Abrupt changes in nozzle lip lengths of the stepped nozzles appear to disrupt acoustic feedback loop, thus resulting in screech cessation. Qualitative schlieren imaging and quantitative schlieren measurements were subsequently performed to correlate the shock structures and density gradient fields with the resulting noise components. Unlike those produced by the baseline nozzle, shock structures generated by the stepped nozzles are highly irregular and the jet plumes undergo discernible deflections. Lastly, the reduction in broadband shock associated noise is related to the lower shock strengths, as demonstrated by the density gradient profiles.
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