47,183 research outputs found
Fuelling Active Galactic Nuclei
We suggest that most nearby active galactic nuclei are fed by a series of
small--scale, randomly--oriented accretion events. Outside a certain radius
these events promote rapid star formation, while within it they fuel the
supermassive black hole. We show that the events have a characteristic time
evolution. This picture agrees with several observational facts. The expected
luminosity function is broadly in agreement with that observed for
moderate--mass black holes. The spin of the black hole is low, and aligns with
the inner disc in each individual feeding event. This implies radio jets
aligned with the axis of the obscuring torus, and uncorrelated with the
large--scale structure of the host galaxy. The ring of young stars observed
about the Galactic Centre are close to where our picture predicts that star
formation should occur.Comment: MNRAS, in pres
Reflections On Contributing To “Big Discoveries” About The Fly Clock: Our Fortunate Paths As Post-Docs With 2017 Nobel Laureates Jeff Hall, Michael Rosbash, And Mike Young
In the early 1980s Jeff Hall and Michael Rosbash at Brandeis University and Mike Young at Rockefeller University set out to isolate the period (per) gene, which was recovered in a revolutionary genetic screen by Ron Konopka and Seymour Benzer for mutants that altered circadian behavioral rhythms. Over the next 15 years the Hall, Rosbash and Young labs made a series of groundbreaking discoveries that defined the molecular timekeeping mechanism and formed the basis for them being awarded the 2017 Nobel Prize in Physiology or Medicine. Here the authors recount their experiences as post-docs in the Hall, Rosbash and Young labs from the mid-1980s to the mid-1990s, and provide a perspective of how basic research conducted on a simple model system during that era profoundly influenced the direction of the clocks field and established novel approaches that are now standard operating procedure for studying complex behavior
Doing it differently: Engaging interview participants with imaginative variation
Imaginative variation was identified by Husserl (1936/1970) as a phenomenological technique for the purpose of elucidating the manner in which phenomena appear to consciousness. Briefly, by engaging in the phenomenological reduction and using imaginative variation, phenomenologists are able to describe the experience of consciousness, having stepped outside of the natural attitude through the epochē. Imaginative variation is a stage aimed at explicating the structures of experience, and is best described as a mental experiment. Features of the experience are imaginatively altered in order to view the phenomenon under investigation from varying perspectives. Husserl argued that this process will reveal the essences of an experience, as only those aspects that are invariant to the experience of the phenomenon will not be able to change through the variation.
Often in qualitative research interviews, participants struggle to articulate or verbalise their experiences. The purpose of this article is to detail a radical and novel way of using imaginative variation with interview participants, by asking the participants to engage with imaginative variation, in order to produce a rich and insightful experiential account of a phenomenon. We will discuss how the first author successfully used imaginative variation in this way in her study of the erotic experience of bondage, discipline, dominance & submission, and sadism & masochism (BDSM), before considering the usefulness of this technique when applied to areas of study beyond sexuality
Ink Drying in Inkjet Printers
The first problem put to the Study Group for Maths in Industry by Domino UK Ltd
concerns ink drying and blocking nozzles in a printer. The goals were as follows:
1. To propose mechanisms for the growth of a plug of dried ink in the open end of a Drop-on-Demand drop generator,
2. To suggest cures to this problem,
3. To consider why oscillating the meniscus appears to alleviate the problem
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