| 1. |
- Algaba, Juan-Carlos, et al.
(författare)
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Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
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| 2. |
- Xia, Qing, et al.
(författare)
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Click-free imaging of carbohydrate trafficking in live cells using an azido photothermal probe
- 2024
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 10:34
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Tidskriftsartikel (refereegranskat)abstract
- Real-time tracking of intracellular carbohydrates remains challenging. While click chemistry allows bio-orthogonal tagging with fluorescent probes, the reaction permanently alters the target molecule and only allows a single snapshot. Here, we demonstrate click-free mid-infrared photothermal (MIP) imaging of azide-tagged carbohydrates in live cells. Leveraging the micromolar detection sensitivity for 6-azido-trehalose (TreAz) and the 300-nm spatial resolution of MIP imaging, the trehalose recycling pathway in single mycobacteria, from cytoplasmic uptake to membrane localization, is directly visualized. A peak shift of azide in MIP spectrum further uncovers interactions between TreAz and intracellular protein. MIP mapping of unreacted azide after click reaction reveals click chemistry heterogeneity within a bacterium. Broader applications of azido photothermal probes to visualize the initial steps of the Leloir pathway in yeasts and the newly synthesized glycans in mammalian cells are demonstrated.
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| 3. |
- Yang, Tao, et al.
(författare)
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Navigating by Index and Guided Tour for Fact Finding
- 2012
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Ingår i: Proceedings of the 30th ACM international conference on Design of communication, SIGDOC'12. - New York : ACM Publications. - 9781450314978 ; , s. 181-190
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Konferensbidrag (refereegranskat)abstract
- The primary mechanism for navigating a website consists of pages with lists of links (or indexes). Such indexes are most effective when they convey the necessary hint (or scent) to anticipate the content they point to. When indexes fail to do so, users who are seeking specific information need to click on a link just to explore where it leads to, and then go back to the index to select another item. In a study with 150 participants, we explored whether guided tour navigation – which enables users to linearly browse items without going back to the index – could outperform scentless indexes in fact-finding tasks. Our results suggest that indexes remain a better solution than guided tours, even when lacking information scent. Guided tours, however, improve user’s performance when the target content is found in the first half of collection with 20 items. Implications for designing effective navigation patterns are discussed.
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