The superwind mass-loss rate of the metal-poor carbon star LI-LMC 1813 in the LMC cluster KMHK 1603

LI-LMC 1813 is a dust-enshrouded Asymptotic Giant Branch (AGB) star, located in the small open cluster KMHK 1603 near the rim of the Large Magellanic Cloud (LMC). Optical and infrared photometry between 0.5 and 60 micron is obtained to constrain the spectral energy distribution of LI-LMC 1813. Near-infrared spectra unambiguously show it to be a carbon star. Modelling with the radiation transfer code Dusty yields accurate values for the bolometric luminosity, L=1.5 x 10^4 Lsun, and mass-loss rate, Mdot=3.7(+/-1.2) x 10^-5 Msun/yr. On the basis of colour-magnitude diagrams, the age of the cluster KMHK 1603 is estimated to be t=0.9-1.0 Gyr, which implies a Zero-Age Main Sequence mass for LI-LMC 1813 of M(ZAMS)=2.2+/-0.1 Msun. This makes LI-LMC 1813 arguably the object with the most accurately and reliably determined (circum)stellar parameters amongst all carbon stars in the superwind phase.Comment: Accepted for publication in MNRAS (better quality figure 1 on request from jacco

X-ray Spectral Variability and Rapid Variability of the Soft X-ray Spectrum Seyfert 1 Galaxies Ark 564 and Ton S180

The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days and 12 days with ASCA and RXTE (and EUVE for Ton S180). The short time scale (hours-days) variability patterns were very similar across energy bands, with no evidence of lags between any of the energy bands studied. The fractional variability amplitude was almost independent of energy band. It is difficult to simultaneously explain soft Seyferts stronger variability, softer spectra, and weaker energy-dependence of the variability relative to hard Seyferts. The soft and hard band light curves diverged on the longest time scales probed, consistent with the fluctuation power density spectra that showed relatively greater power on long time scales in the softest bands. The simplest explanation is that a relatively hard, rapidly-variable component dominates the total X-ray spectrum and a slowly-variable soft excess is present in the lowest energy channels of ASCA. Although it would be natural to identify the latter with an accretion disk and the former with a corona surrounding it, a standard thin disk could not get hot enough to radiate significantly in the ASCA band, and the observed variability time scales are much too short. The hard component may have a more complex shape than a pure power-law. The most rapid factor of 2 flares and dips occurred within ~1000 sec in Ark 564 and a bit more slowly in Ton S180. The speed of the luminosity changes rules out viscous or thermal processes and limits the size of the individual emission regions to <~15 Schwarzschild radii (and probably much less), that is, to either the inner disk or small regions in a corona

Ultraviolet polarisation sensitivity in the stomatopod crustacean Odontodactylus scyllarus

The ommatidia of crustacean eyes typically contain two classes of photoreceptors with orthogonally oriented microvilli. These receptors provide the basis for two-channel polarisation vision in the blue–green spectrum. The retinae of gonodactyloid stomatopod crustaceans possess a great variety of structural specialisations for elaborate polarisation vision. One type of specialisation is found in the small, distally placed R8 cells within the two most ventral rows of the mid-band. These ultraviolet-sensitive photoreceptors produce parallel microvilli, a feature suggestive for polarisation-sensitive photoreceptors. Here, we show by means of intracellular recordings combined with dye-injections that in the gonodactyloid species Odontodactylus scyllarus, the R8 cells of mid-band rows 5 and 6 are sensitive to linear polarised ultraviolet light. We show that mid-band row 5 R8 cells respond maximally to light with an e-vector oriented parallel to the mid-band, whereas mid-band row 6 R8 cells respond maximally to light with an e-vector oriented perpendicular to the mid-band. This orthogonal arrangement of ultraviolet-sensitive receptor cells could support ultraviolet polarisation vision. R8 cells of rows 5 and 6 are known to act as quarter-wave retarders around 500 nm and thus are the first photoreceptor type described with a potential dual role in polarisation vision

The secret world of shrimps: polarisation vision at its best

Animal vision spans a great range of complexity, with systems evolving to detect variations in optical intensity, distribution, colour, and polarisation. Polarisation vision systems studied to date detect one to four channels of linear polarisation, combining them in opponent pairs to provide intensity-independent operation. Circular polarisation vision has never been seen, and is widely believed to play no part in animal vision. Polarisation is fully measured via Stokes' parameters--obtained by combined linear and circular polarisation measurements. Optimal polarisation vision is the ability to see Stokes' parameters: here we show that the crustacean \emph{Gonodactylus smithii} measures the exact components required. This vision provides optimal contrast-enhancement, and precise determination of polarisation with no confusion-states or neutral-points--significant advantages. We emphasise that linear and circular polarisation vision are not different modalities--both are necessary for optimal polarisation vision, regardless of the presence of strongly linear or circularly polarised features in the animal's environment.Comment: 10 pages, 6 figures, 2 table

The anisotropic XY model on the inhomogeneous periodic chain

The static and dynamic properties of the anisotropic XY-model $(s=1/2)$ on the inhomogeneous periodic chain, composed of $N$ cells with $n$ different exchange interactions and magnetic moments, in a transverse field $h,$ are determined exactly at arbitrary temperatures. The properties are obtained by introducing the Jordan-Wigner fermionization and by reducing the problem to a diagonalization of a finite matrix of $nth$ order. The quantum transitions are determined exactly by analyzing, as a function of the field, the induced magnetization 1/n\sum_{m=1}^{n}\mu_{m}\left ($j$ denotes the cell, $m$ the site within the cell, $\mu_{m}$ the magnetic moment at site $m$ within the cell) and the spontaneous magnetization $1/n\sum_{m=1}^{n}\left< S_{j,m}^{x},\right>$ which is obtained from the correlations $\left< S_{j,m}^{x}S_{j+r,m}^{x}\right>$ for large spin separations. These results, which are obtained for infinite chains, correspond to an extension of the ones obtained by Tong and Zhong(\textit{Physica B} \textbf{304,}91 (2001)). The dynamic correlations, $\left< S_{j,m}^{z}(t)S_{j^{\prime},m^{\prime}}^{z}(0)\right>$, and the dynamic susceptibility, $\chi_{q}^{zz}(\omega),$ are also obtained at arbitrary temperatures. Explicit results are presented in the limit T=0, where the critical behaviour occurs, for the static susceptibility $\chi_{q}^{zz}(0)$ as a function of the transverse field $h$, and for the frequency dependency of dynamic susceptibility $\chi_{q}^{zz}(\omega)$.Comment: 33 pages, 13 figures, 01 table. Revised version (minor corrections) accepted for publiction in Phys. Rev.

Trust, confidence, and equity affect the legitimacy of natural resource governance

ArticleSocial-ecological systems are often highly complex, making effective governance a considerable challenge. In large, heterogeneous systems, hierarchical institutional regimes may be efficient, but effective management outcomes are dependent on stakeholder support. This support is shaped by perceptions of legitimacy, which risks being undermined where resource users are not engaged in decision-making. Although legitimacy is demonstrably critical for effective governance, less is known about the factors contributing to stakeholders’ perceptions of legitimacy or how these perceptions are socially differentiated. We quantitatively assessed stakeholder perceptions of legitimacy (indicated by support for rules) and their contributory factors among 307 commercial fishers and tourism operators in Australia’s Great Barrier Reef Marine Park. Legitimacy was most strongly associated with trust in information from governing bodies, followed by confidence in institutional performance and the equity of management outcomes. Legitimacy differed both within and among resource user groups, which emphasizes the heterogeneous nature of commonly defined stakeholder groups. Overall, tourism operators perceived higher legitimacy than did commercial fishers, which was associated with higher trust in information from management agencies. For fishers, higher levels of trust were associated with: (1) engagement in fisheries that had high subsector cohesion and positive previous experiences of interactions with governing bodies; (2) location in areas with greater proximity to sources of knowledge, resources, and decision-making; and (3) engagement in a Reef Guardian program. These findings highlight the necessity of strategies and processes to build trust among all user groups in large social-ecological systems such as the Great Barrier Reef Marine Park. Furthermore, the social differentiation of perceptions that were observed within user groups underscores the importance of targeted strategies to engage groups that may not be heard through traditional governance channels.The Social and Ecological Long Term Monitoring Program (SELTMP) for the Great Barrier Reef Marine Park was established in 2011 with funding provided by the Australian Government under the National Environment Research Program (NERP). We thank the SELTMP team for their support and collaboration. We also sincerely thank the commercial fishers and tourism operators that were part of this research and the interviewers that were involved. The arguments presented here are the sole responsibility of the authors. This paper was developed in a workshop funded by the Julius Career Award, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), and the Environment and Sustainability theme of the University of Exeter’s Humanities and Social Science Strategy. The authors acknowledge additional support from the University of Exeter’s Outward Mobility Fund (R. T.), the Australian Research Council (T. M., A. A., B. J. B.), CSIRO (J. A.), and AusAID (A. A.)

The remnant of SN1987A revealed at (sub-)mm wavelengths

Context: Supernova 1987A (SN1987A) exploded in the Large Magellanic Cloud (LMC). Its proximity and rapid evolution makes it a unique case study of the early phases in the development of a supernova remnant. One particular aspect of interest is the possible formation of dust in SN1987A, as SNe could contribute significantly to the dust seen at high redshifts. Aims: We explore the properties of SN1987A and its circumburst medium as seen at mm and sub-mm wavelengths, bridging the gap between extant radio and infrared (IR) observations of respectively the synchrotron and dust emission. Methods: SN1987A was observed with the Australia Telescope Compact Array (ATCA) at 3.2 mm in July 2005, and with the Atacama Pathfinder EXperiment (APEX) at 0.87 mm in May 2007. We present the images and brightness measurements of SN1987A at these wavelengths for the first time. Results: SN1987A is detected as an unresolved point source of 11.2 +/- 2.0 mJy at 3.2 mm (5" beam) and 21 +/- 4 mJy at 0.87 mm (18" beam). These flux densities are in perfect agreement with extrapolations of the powerlaw radio spectrum and modified-blackbody dust emission, respectively. This places limits on the presence of free-free emission, which is similar to the expected free-free emission from the ionized ejecta from SN1987A. Adjacent, fainter emission is observed at 0.87 mm extending ~0.5' towards the south-west. This could be the impact of the supernova progenitor's wind when it was still a red supergiant upon a dense medium. Conclusions: We have established a continuous spectral energy distribution for the emission from SN1987A and its immediate surroundings, linking the IR and radio data. This places limits on the contribution from ionized plasma. Our sub-mm image reveals complexity in the distribution of cold dust surrounding SN1987A, but leaves room for freshly synthesized dust in the SN ejecta.Comment: Accepted for publication in Astronomy and Astrophysics Letters on 28 April 2011. A better quality figure 1 can be had from http://www.astro.keele.ac.uk/~jacco/research/SN1987A087mm.ep

Maximal work extraction from quantum systems

Thermodynamics teaches that if a system initially off-equilibrium is coupled to work sources, the maximum work that it may yield is governed by its energy and entropy. For finite systems this bound is usually not reachable. The maximum extractable work compatible with quantum mechanics (``ergotropy'') is derived and expressed in terms of the density matrix and the Hamiltonian. It is related to the property of majorization: more major states can provide more work. Scenarios of work extraction that contrast the thermodynamic intuition are discussed, e.g. a state with larger entropy than another may produce more work, while correlations may increase or reduce the ergotropy.Comment: 5 pages, 0 figures, revtex

The Molecular Gas Environment around Two Herbig Ae/Be Stars: Resolving the Outflows of LkHa 198 and LkHa 225S

Observations of outflows associated with pre-main-sequence stars reveal details about morphology, binarity and evolutionary states of young stellar objects. We present molecular line data from the Berkeley-Illinois-Maryland Association array and Five Colleges Radio Astronomical Observatory toward the regions containing the Herbig Ae/Be stars LkHa 198 and LkHa 225S. Single dish observations of 12CO 1-0, 13CO 1-0, N2H+ 1-0 and CS 2-1 were made over a field of 4.3' x 4.3' for each species. 12CO data from FCRAO were combined with high resolution BIMA array data to achieve a naturally-weighted synthesized beam of 6.75'' x 5.5'' toward LkHa 198 and 5.7'' x 3.95'' toward LkHa 225S, representing resolution improvements of factors of approximately 10 and 5 over existing data. By using uniform weighting, we achieved another factor of two improvement. The outflow around LkHa 198 resolves into at least four outflows, none of which are centered on LkHa 198-IR, but even at our resolution, we cannot exclude the possibility of an outflow associated with this source. In the LkHa 225S region, we find evidence for two outflows associated with LkHa 225S itself and a third outflow is likely driven by this source. Identification of the driving sources is still resolution-limited and is also complicated by the presence of three clouds along the line of sight toward the Cygnus molecular cloud. 13CO is present in the environments of both stars along with cold, dense gas as traced by CS and (in LkHa 225S) N2H+. No 2.6 mm continuum is detected in either region in relatively shallow maps compared to existing continuum observations.Comment: 14 pages, 10 figures (5 color), accepted for publication in Ap

Human rights and ethical reasoning : capabilities, conventions and spheres of public action

This interdisciplinary article argues that human rights must be understood in terms of opportunities for social participation and that social and economic rights are integral to any discussion of the subject. We offer both a social constructionist and a normative framework for a sociology of human rights which reaches beyond liberal individualism, combining insights from the work of Amartya Sen and from French convention theory. Following Sen, we argue that human rights are founded on the promotion of human capabilities as ethical demands shaped by public reasoning. Using French convention theory, we show how the terms of such deliberation are shaped by different constructions of collectively held values and the compromises reached between them. We conclude by demonstrating how our approach offers a new perspective on spheres of public action and the role these should play in promoting social cohesion, individual capabilities and human rights