High Resolution Spectroscopy of Balmer-Dominated Shocks in the RCW 86, Kepler and SN 1006 Supernova Remnants

We report results from high resolution optical spectroscopy of three non-radiative galactic supernova remnants, RCW 86, Kepler's supernova remnant and SN 1006. We have measured the narrow component H-alpha line widths in Balmer-dominated filaments in RCW 86 and SN 1006, as well as the narrow component width in a Balmer-dominated knot in Kepler's SNR. The narrow component line widths measured in RCW 86 and Kepler's SNR show FWHM of 30-40 km/s, similar to what has been seen in other Balmer-dominated remnants. Of the remnants in our sample, SN 1006 is the fastest shock (~3000 km/s). The narrow component H-alpha and H-beta lines in this remnant have a FWHM of merely 21 km/s. Comparing the narrow component widths measured in our sample with those measured in other remnants shows that the width of the narrow component does not correlate in a simple way with the shock velocity. The implications for the pre-heating mechanism responsible for the observed line widths are discussed.Comment: Accepted by A&

Phase-field crystal study of grain-boundary premelting

We study the phenomenon of grain-boundary premelting for temperatures below the melting point in the phase-field crystal model of a pure material with hexagonal ordering in two dimensions. We investigate the structures of symmetric tilt boundaries as a function of misorientation for two different inclinations and compute in the grand canonical ensemble the disjoining potential V(w) that governs the fundamental interaction between crystal-melt interfaces as a function of the premelted layer width w. The results reveal qualitatively different behaviors for high-angle grain boundaries that are uniformly wetted, with w diverging logarithmically as the melting point is approached from below, and low-angle boundaries that are punctuated by liquid pools surrounding dislocations, separated by solid bridges. This qualitative difference between high and low angle boundaries is reflected in the w-dependence of the disjoining potential that is purely repulsive (V'(w)<0 for all w) above a critical misorientation, but switches from repulsive at small w to attractive at large w for low angles. In the latter case, V(w) has a minimum that corresponds to a premelted boundary of finite width at the melting point. Furthermore, we find that the standard wetting condition (the grain boundary energy is equal to twice the solid-liquid free energy) gives a much too low estimate of the critical misorientation when a low-temperature value of the grain boundary energy is used. In contrast, a reasonable estimate is obtained if the grain boundary energy is extrapolated to the melting point, taking into account both the elastic softening of the material at high temperature and local melting around dislocations.Comment: 24 pages, 13 figures, some figure files with reduced resolution because of submission size limitations. In the 2nd version, some parts (and figures) have been modified, especially in Sec. V (discussion

A qualitative study of the health experience of gypsy travellers in the UK with a focus on terminal illness

Aim To understand the experience of terminal care and health care access for Gypsy Travellers, to inform palliative and primary care service provision. Background Little contemporary research of UK English Romany Gypsy Travellers is available. This ethnic group is often overlooked in ethnic minority health research. Methods Access to Gypsy Traveller communities was through non-health care channels and required the development of trust through repeated contact over time. English Romany Gypsy Travellers at two Traveller sites participated in face-to-face contacts. Data collection was through field observation and seven semistructured interviews with Gypsy Traveller women who had experience of caring for relatives who were dying. In addition, data were collected over two years through discussion in a members-only Gypsy and Traveller interest e-mail forum. Findings The culture of Gypsy Travellers is distinct but diverse. Hygiene is important as is discretion and sensitivity to the information requirements of the patient and family. Gypsy Travellers are aware that their mobility (voluntary or enforced) can negatively impact on health care. Home care for the terminally ill is often preferred to hospital care often due to poor understanding of their cultural and personal needs by health care professionals and due to an aversion to ‘bricks and mortar’. Care may be provided by the extended family. Palliative care provision should consider the needs of Gypsy Travellers including respect for their culture and support for caring at home

Good Management Practice in Sustainable Fisheries: The Nature of Success in Fisheries Management

The fisheries and aquaculture sector is of fundamental importance to the Asia-Pacific region providing opportunities for revenue generation and employment, and contributing to food security. This document reviews the current status of inland and marine fisheries resources and their contribution to national economies and food security. Regional fishery data and information stored in FAO databases are analysed to provide a comprehensive picture of production trends of fisheries and aquaculture in the Asia-Pacific region, which is further illustrated by a detailed view of sub-regions and aquaculture production by species groups. It also touches upon issues that require closer attention in order for the fisheries resources to be managed in a responsive and sustainable manner

Few-photon Transport in Fano-resonance waveguide geometries

We present a theoretical study of Fano interference effects in few-photon transport. Under appropriate conditions, a local defect in an optical waveguide induces a highly asymmetric transmission lineshape, characteristic of Fano interference. For a two-level emitter placed adjacent to such a defect, here modeled as a partially transmitting element, we find an analytical expression for the full time evolution of single-photon wavepackets and the emitter excitation probability. We show how the partially transmitting element affects the emitter lifetime and shifts the spectral position of the effective system resonances. Using input-output formalism, we determine the single and two-photon $S$-matrices for both a two-level emitter and a cavity-emitter system coupled to a waveguide with a partially transmitting element. We show how the Fano interference effect can be exploited for the implementation of a Hong-Ou-Mandel switch in analogy with a tunable linear or nonlinear beam splitter.Comment: 19 pages (incl. a 6 pages long appendix), 5 figure