Massive stars exploding in a He-rich circumstellar medium - III. SN 2006jc: infrared echoes from new and old dust in the progenitor CSM

We present near- (NIR) and mid-infrared (MIR) photometric data of the Type Ibn supernova (SN) 2006jc obtained with the United Kingdom Infrared Telescope (UKIRT), the Gemini North Telescope and the Spitzer Space Telescope between days 86 and 493 post-explosion. We find that the IR behaviour of SN 2006jc can be explained as a combination of IR echoes from two manifestations of circumstellar material. The bulk of the NIR emission arises from an IR echo from newly condensed dust in a cool dense shell (CDs) produced by the interaction of the ejecta Outward shock with a dense shell of circumstellar material ejected by the progenitor in a luminous blue variable (LBV)-like outburst about two years prior to the SN explosion. The CDs dust mass reaches a modest 3.0 x 10(-4) M-circle dot by day 230. While dust condensation within a CDs formed behind the ejecta inward shock has been proposed before for one event (SN 1998S), SN 2006jc is the first one showing evidence for dust condensation in a CDs formed behind the ejecta outward shock in the circumstellar material. At later epochs, a substantial and growing contribution to the IR fluxes arises from an IR echo from pre-existing dust in the progenitor wind. The mass of the pre-existing circumstellar medium (CSM) dust is at least similar to 8 x 10(-3) M-circle dot. This paper therefore adds to the evidence that mass-loss from the progenitors of core-collapse SNe could be a major source of dust in the Universe. However, yet again, we see no direct evidence that the explosion of an SN produces anything other than a very modest amount of dust.

The journey of a ‘green’ micro-enterprise – The Green Planet

This teaching case explores the longitudinal evolution of a small environmental micro-enterprise, The Green Planet retail store. Exploring two decades of business history it analyses the development of this business as sustainability issues and greener consumer goods mainstreamed in society. The case presents one of the first explorations of the individual trade-offs that owners make between economic, environmental and social criteria, alongside an exploration of the role that the personal values of the owner played in the evolution of this business. Also presented is a sample of other environmental enterprises profiled alongside The Green Planet in the early 1990s. This additional dataset provides a rich resource for readers, and a number of indicative discussion themes are identified. Readers interested in topics such as marketing, business strategy, innovation, entrepreneurship, corporate social responsibility and environmental management will find this case a valuable addition to their teaching resources.

Chemistry in oxygen-rich circumstellar envelopes

We have considered the chemistry occuring in the circumstellar envelope surrounding an oxygen-rich AGE star and have specifically modelled 4 sources; R Dor, TX Cam, OH231.8+4.2 and IK Tau. Methane has been assumed to be a parent molecule and the resulting carbon chemistry is investigated. We find that carbon chain molecules up to C2H4 can be abundant as can CH3CN and CH3OH. Our model extends previous work by including the chemistry of silicon, chlorine and phosphorus. The presence of CH4 as a parent and hence its daughter species CH3 and CH3+ leads to other carbon-bearing species such as H2CS, SiCH2, H2CN and CCl.

FORMALDEHYDE IN OXYGEN-RICH CIRCUMSTELLAR ENVELOPES

We test the hypothesis that methane is the source of the carbon observed in carbon-bearing molecules around oxygen-rich stars, by considering the synthesis of formaldehyde which is formed in the reaction between oxygen atoms and methyl radicals. We find that, provided that the parent methane abundance is large enough, millimetre-wave emission lines of H2CO should be detectable in such stars. We also consider the formation of other species, notably H2CN and H2CS, from methyl radicals, but conclude that they will be at least one order of magnitude less abundant than H2CO and therefore not detectable with current instrumentation.

Qatar-1b: a hot Jupiter orbiting a metal-rich K dwarf star

We report the discovery and initial characterization of Qatar-1b, a hot Jupiter-orbiting metal-rich K dwarf star, the first planet discovered by the Qatar Exoplanet Survey. We describe the strategy used to select candidate transiting planets from photometry generated by the Qatar Exoplanet Survey camera array. We examine the rate of astrophysical and other false positives found during the spectroscopic reconnaissance of the initial batch of candidates. A simultaneous fit to the follow-up radial velocities and photometry of Qatar-1b yields a planetary mass of 1.09 ± 0.08 MJ and a radius of 1.16 ± 0.05 RJ. The orbital period and separation are 1.420 033 ± 0.000 016 d and 0.023 43 ± 0.000 26 au for an orbit assumed to be circular. The stellar density, effective temperature and rotation rate indicate an age greater than 4 Gyr for the system.

A Robust Co-Localisation Measurement Utilising Z-Stack Image Intensity Similarities for Biological Studies

Background: Co-localisation is a widely used measurement in immunohistochemical analysis to determine if fluorescently labelled biological entities, such as cells, proteins or molecules share a same location. However the measurement of co-localisation is challenging due to the complex nature of such fluorescent images, especially when multiple focal planes are captured. The current state-of-art co-localisation measurements of 3-dimensional (3D) image stacks are biased by noise and cross-overs from non-consecutive planes.

Method: In this study, we have developed Co-localisation Intensity Coefficients (CICs) and Co-localisation Binary Coefficients (CBCs), which uses rich z-stack data from neighbouring focal planes to identify similarities between image intensities of two and potentially more fluorescently-labelled biological entities. This was developed using z-stack images from murine organotypic slice cultures from central nervous system tissue, and two sets of pseudo-data. A large amount of non-specific cross-over situations are excluded using this method. This proposed method is also proven to be robust in recognising co-localisations even when images are polluted with a range of noises.

Results: The proposed CBCs and CICs produce robust co-localisation measurements which are easy to interpret, resilient to noise and capable of removing a large amount of false positivity, such as non-specific cross-overs. Performance of this method of measurement is significantly more accurate than existing measurements, as determined statistically using pseudo datasets of known values. This method provides an important and reliable tool for fluorescent 3D neurobiological studies, and will benefit other biological studies which measure fluorescence co-localisation in 3D.

Expertise is perceived from both sound and body movement in musical performance

Music is a rich form of nonverbal communication, in which the movements that expert musicians make during performance can influence the perception of expressive and structural features of the music. Whether the actual skill of a musician is perceivable from vision of movement was examined. In Experiment 1, musicians and non-musicians rated performances by novice, intermediate and expert clarinettists from point-light animations of their movements, sound recordings, or both. Performances by clarinettists of more advanced skill level were rated significantly higher from vision of movements, although this effect was stronger when sound was also presented. In Experiment 2, movements and sound from the novice and expert clarinettists' performances were switched for half the presentations, and were matched for the rest. Ratings of novice music were significantly higher when presented with expert movements, although the opposite was not found for expert sound presented with novice movements. No perceptual effect of raters' own level of musicianship was found in either experiment. These results suggest that expertise is perceivable from vision of musicians' body movements, although perception of skill from sound is dominant. The results from Experiment 2 further indicate a cross-modal effect of vision and audition on the perception of musical expertise. © 2012 Elsevier B.V.

N-acetylgalactosamine kinase: a naturally promiscuous small molecule kinase

N-acetylgalactosamine kinase is a member of the GHMP family of small molecule kinases which catalyses the ATP-dependent phosphorylation of N-acetylgalactosamine. It is highly similar in structure and sequence to galactokinase. Alteration of galactokinase at a key tyrosine residue (Tyr-379 in the human enzyme) has been shown to dramatically enhance the substrate range of this enzyme. Here, we investigated the substrate specificity of the wild type N-acetylgalactosamine kinase and demonstrated that it can also catalyse the phosphorylation of N-acetylglucosamine and N-acetylmannosamine. In human N-acetylgalactosamine kinase, the equivalent residue to Tyr-379 in galactokinase is Phe-444. Alteration of this residue did not result in dramatic changes to the specificity of the enzyme. The more relaxed substrate specificity of N-acetylgalactosamine kinase, compared to galactokinase, can be explained by the greater flexibility of a glycine rich loop in the active site of the enzyme. These results suggest that N-acetylgalactosamine kinase is a potential biocatalyst for the phosphorylation of N-acetyl sugars. However, it is unlikely that it will be possible to further broaden the substrate range by alteration of Phe-444.

Towards Charity Accountability: Narrowing the gap between provision and needs?

Although charities currently play a rich and varied role in modern society, their continued success is dependent upon the public's trust. With respect to charity accountability, two key questions emerge: to whom is a charity accountable; and what form should that account take? Despite the widespread acceptance that charities should discharge accountability, there is limited knowledge of the relative importance of different stakeholder groups and whether the information currently being disclosed meets their needs. Using extensive document analysis and a survey of stakeholders, this research explores these issues in the context of the top 100 UK fundraising charities. Furthermore, it compares the results with much earlier research to identify changes over time.

Massive stars exploding in a He-rich circumstellar medium - I. Type Ibn (SN 2006jc-like) events

We present new spectroscopic and photometric data of the Type Ibn supernovae 2006jc, 2000er and 2002ao. We discuss the general properties of this recently proposed supernova family, which also includes SN 1999cq. The early-time monitoring of SN 2000er traces the evolution of this class of objects during the first few days after the shock breakout. An overall similarity in the photometric and spectroscopic evolution is found among the members of this group, which would be unexpected if the energy in these core-collapse events was dominated by the interaction between supernova ejecta and circumstellar medium. Type Ibn supernovae appear to be rather normal Type Ib/c supernova explosions which occur within a He-rich circumstellar environment. SNe Ibn are therefore likely produced by the explosion of Wolf-Rayet progenitors still embedded in the He-rich material lost by the star in recent mass-loss episodes, which resemble known luminous blue variable eruptions. The evolved Wolf-Rayet star could either result from the evolution of a very massive star or be the more evolved member of a massive binary system. We also suggest that there are a number of arguments in favour of a Type Ibn classification for the historical SN 1885A (S-Andromedae), previously considered as an anomalous Type la event with some resemblance to SN 1991bg.