The Herschel view of circumstellar discs: a multi-wavelength study of Chamaeleon I

We present the results of a multi-wavelength study of circumstellar discs around 44 young stellar objects in the 3 Myr old nearby Chamaeleon I star-forming region. In particular, we explore the far-infrared/submm regime using Herschel fluxes. We show that Herschel fluxes at 160-500$\,\mu$m can be used to derive robust estimates of the disc mass. The median disc mass is 0.005$M_{\odot}$ for a sample of 28 Class IIs and 0.006$M_{\odot}$ for 6 transition disks (TDs). The fraction of objects in Chamaeleon-I with at least the `minimum mass solar nebula' is 2-7%. This is consistent with previously published results for Taurus, IC348, $\rho$ Oph. Diagrams of spectral slopes show the effect of specific evolutionary processes in circumstellar discs. Class II objects show a wide scatter that can be explained by dust settling. We identify a continuous trend from Class II to TDs. Including Herschel fluxes in this type of analysis highlights the diversity of TDs. We find that TDs are not significantly different to Class II discs in terms of far-infrared luminosity, disc mass or degree of dust settling. This indicates that inner dust clearing occurs independently from other evolutionary processes in the discs.Comment: 16 pages, 13 figures. Accepted for publication in MNRA

Spatially Resolved Observations of the Bipolar Optical Outflow from the Brown Dwarf 2MASSJ12073347-3932540

Studies of brown dwarf (BD) outflows provide information pertinent to questions on BD formation, as well as allowing outflow mechanisms to be investigated at the lowest masses. Here new observations of the bipolar outflow from the 24 M$_{JUP}$ BD, 2MASSJ12073347-3932540 are presented. The outflow was originally identified through the spectro-astrometric analysis of the [OI]$\lambda$6300 emission line. Follow-up observations consisting of spectra and [SII], R-band and I-band images were obtained. The new spectra confirm the original results and are used to constrain the outflow PA at $\sim$ 65$^{\circ}$. The [OI]$\lambda$6300 emission line region is spatially resolved and the outflow is detected in the [SII] images. The detection is firstly in the form of an elongation of the point spread function along the direction of the outflow PA. Four faint knot-like features (labelled {\it A-D}) are also observed to the south-west of 2MASSJ12073347-3932540 along the same PA suggested by the spectra and the elongation in the PSF. Interestingly, {\it D}, the feature furthest from the source is bow-shaped with the apex pointing away from 2MASSJ12073347-3932540. A color-color analysis allows us to conclude that at least feature {\it D} is part of the outflow under investigation while {\it A} is likely a star or galaxy. Follow-up observations are needed to confirm the origin of {\it B} and {\it C}. This is a first for a BD, as BD optical outflows have to date only been detected using spectro-astrometry. This result also demonstrates for the first time that BD outflows can be collimated and episodic.Comment: Accepted by ApJ, ref ApJ89096R

Odorants for surveillance and control of the Asian Citrus Psyllid (Diaphorina citri).

BackgroundThe Asian Citrus Psyllid (ACP), Diaphorina citri, can transmit the bacterium Candidatus Liberibacter while feeding on citrus flush shoots. This bacterium causes Huanglongbing (HLB), a major disease of citrus cultivation worldwide necessitating the development of new tools for ACP surveillance and control. The olfactory system of ACP is sensitive to variety of odorants released by citrus plants and offers an opportunity to develop new attractants and repellents.ResultsIn this study, we performed single-unit electrophysiology to identify odorants that are strong activators, inhibitors, and prolonged activators of ACP odorant receptor neurons (ORNs). We identified a suite of odorants that activated the ORNs with high specificity and sensitivity, which may be useful in eliciting behavior such as attraction. In separate experiments, we also identified odorants that evoked prolonged ORN responses and antagonistic odorants able to suppress neuronal responses to activators, both of which can be useful in lowering attraction to hosts. In field trials, we tested the electrophysiologically identified activating odorants and identified a 3-odor blend that enhances trap catches by ∼230%.ConclusionThese findings provide a set of odorants that can be used to develop affordable and safe odor-based surveillance and masking strategies for this dangerous pest insect

BREAKING THE IRON LAW: IMPLEMENTING COST EFFECTIVE, GREEN ICT IN THE UK PUBLIC SECTOR

Public sector information and communication technologies (ICT) cost taxpayers in the United Kingdom (UK) over £16 billion annually and are responsible for between 35-38% of ICT-related Greenhouse Gas (GHG) emissions. While the UK\u27s Greening Government ICT Strategy is regarded as an exemplar in regard to the latter, the Government ICT Strategy addresses the former in terms of eliminating the unnecessary proliferation of ICT applications and infrastructures that resulted from recent e-Government and Transformational Government strategies. Thus, given the crisis in public finances, the Government ICT Strategy aims to reduce ICT-related costs and to improve service delivery, while reducing GHG emissions. This paper\u27s field study of the UK government\u27s ICT strategies draws upon institutional theory for its mechanism-based conceptual framework. The findings of this study delineate the institutional mechanisms that underpin strategy implementation and enable the attainment of strategic objectives. While the study has several significant implications for research and practice, one notable finding is that contrary to the \u27iron law\u27 of climate policy, the UK government\u27s focus on ICT-enabled GHG emissions reductions did not diminish with the economic downturn, as the cost savings associated with the introduction of efficient, Green ICT provided sufficient justification for the required infrastructure investment

Alignment of the Western and Eastern Passage Tombs at Knowth Tomb 1

This report presents a summary account of two surveys undertaken by the authors to determine and interpret the alignments of the western and eastern passage tombs at Knowth, Co. Meath. The findings indicate that contrary to earlier suggestions, the eastern passage and the western passage (inner and outer) are not aligned towards sunrise and sunset respectively at the period of the vernal and autumnal equinoxes

Diophantine stability for elliptic curves on average

Let $K$ be a number field and $\ell\geq 5$ be a prime number. Mazur and Rubin introduced the notion of diophantine stability for a variety $X_{/K}$ at a prime $\ell$. Under the hypothesis that all elliptic curves $E_{/\mathbb{Q}}$ have finite Tate-Shafarevich group, we show that there is a positive density set of elliptic curves $E_{/\mathbb{Q}}$ of rank $1$, such that $E_{/K}$ is diophantine stable at $\ell$. This result has implications to Hilbert's tenth problem for number rings.Comment: 11 page

Self-management & social skills strategies to support student success

This presentation will describe research-based self-management and social skills instructional strategies to promote social and academic skills for students with disabilities, including self-recording strategies designed to facilitate academic productivity and social skills instruction designed to increase compliance to teacher requests. These strategies are pragmatic and can be used by school/clinical personnel, as well as parents