859 research outputs found
Stop making sense: learning, community, digital citizenship and the massive in a post-MOOC world
Harnessing the power of the 'Massive': an innovative approach to participation, digital citizenship and open learning on-line.
In January 2015, the London School of Economics and Political Science (UK) launched an innovative civic engagement project, which aimed to crowd source the United Kingdom Constitution. One of the key intentions of the project was to leverage and magnify the power of the community and the ‘massive’ in order to empower participants to engage in debate, identify solutions and come to a common agreement about the need for and the content of a UK Constitution. Involving over 1500 participants and generating tens of thousands of on-line interactions that increased as opposed to decreased over the 14 week duration of the ‘course’, Crowd Sourcing the UK Constitution challenged some of the dominant paradigms of Massive Open On-line Learning. We will present the findings arising from a critical evaluation of the project and pose a number of questions that emerged from both our engagement with the project and from the participants themselves centred on enhancing the effectiveness of a pedagogical design to harness the power of the massive, a large community of engaged participants working together in order to solve a problem, effect change or develop capacity
BSE versus StarTrack: implementations of new wind, remnant-formation, and natal-kick schemes in NBODY7 and their astrophysical consequences
The masses of stellar-remnant black holes (BH), as a result of their
formation via massive single- and binary-stellar evolution, is of high interest
in this era of gravitational-wave detection from binary black hole (BBH) and
binary neutron star (BNS) mergers. Here we present new developments in the
N-body evolution program NBODY7 in regards to its stellar-remnant formation and
related schemes. We demonstrate that the newly-implemented stellar-wind and
remnant-formation schemes in the NBODY7 code's BSE sector, such as the 'rapid'
and the 'delayed' supernova (SN) schemes along with an implementation of
pulsational-pair-instability and pair-instability supernova (PPSN/PSN), now
produces neutron star (NS) and BH masses that agree nearly perfectly, over
large ranges of zero-age-main sequence (ZAMS) mass and metallicity, with those
from the StarTrack population-synthesis program. We also demonstrate the new
implementations of various natal-kick mechanisms on NSs and BHs such as the
'convection-asymmetry-driven', 'collapse-asymmetry-driven', and
'neutrino-emission-driven' kicks, in addition to a fully consistent
implementation of the standard, fallback-dependent, momentum-conserving natal
kick. We find that the SN material fallback causes the convection-asymmetry
kick to effectively retain similar number and mass of BHs in clusters as for
the standard, momentum-conserving kick. The collapse-asymmetry kick would cause
nearly all BHs to retain in clusters irrespective of remnant formation model
and metallicity, whereas the inference of a large number of BHs in GCs would
potentially rule out the neutrino-driven kick mechanism. Pre-SN mergers of
massive primordial binaries would cause BH masses to deviate from the
single-star ZAMS mass-remnant mass relation. Such mergers, at low
metallicities, can produce low-spinning BHs within the PSN mass gap that can be
retained in a stellar cluster.Comment: 27 pages, 15 figures, 2 tables. Accepted for publication in Astronomy
and Astrophysic
The absorption of 2-acetyl-1-pyrroline during cooking of rice (Oryza sativa L.) with Pandan (Pandanus amaryllifolius Roxb.) leaves)
AbstractRice (Oryza sativa L.) is a staple food for about half of the population in the world. Aroma is one of the most important rice sensory quality characteristics. The chemical compound that contributes mostly to the aroma profile of aromatic rice (e.g. basmati rice) is 2-acetyl-1-pyrroline (2-AP). This highly volatile compound has been found to occur naturally in Pandan leaves. Adding fresh Pandan leaves to enhance the flavour profile of non-aromatic rice is as an old practice in South-East Asia. However, there has been little work done on how 2-AP is extracted from Pandan leaves and the phenomena taking place during cooking. The aim of this study was to investigate the mechanism of absorption of 2-AP from non-aromatic rice mixed with Pandan leaves during cooking. Non-aromatic rice was cooked with fresh Pandan leaves using optimal and excess water conditions. The amount of 2-AP in rice grain was found to decrease at 10min (optimal water) and 5min (excess water) of cooking. A possible explanation of this phenomena could be linked to starch gelatinization and the effect it has on interaction with 2-AP from the rice grains
Coffee bean particle motion in a rotating drum measured using Positron Emission Particle Tracking (PEPT)
Spectra and Light Curves of Failed Supernovae
Astronomers have proposed a number of mechanisms to produce supernova
explosions. Although many of these mechanisms are now not considered primary
engines behind supernovae, they do produce transients that will be observed by
upcoming ground-based surveys and NASA satellites. Here we present the first
radiation-hydrodynamics calculations of the spectra and light curves from three
of these "failed" supernovae: supernovae with considerable fallback, accretion
induced collapse of white dwarfs, and energetic helium flashes (also known as
type .Ia supernovae).Comment: 33 pages, 14 figure
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