Social work education, training and standards in the Asia-Pacific region

This article discusses the joint project between the International Association of Schools of Social Work (IASSW) and the International Federation of Social Workers (IFSW) to establish guidelines for the training and standard setting that elucidates what social work represents on a global level. While it is impossible to address all the issues that might be significant in such a large scope, attention is given to the challenges establishing global standards might encounter in a region as diverse as the Asia-Pacific

The electronic spectra of protonated PANH molecules

Aims. This study was designed to examine the viability of protonated nitrogen-substituted polycyclic aromatic hydrocarbons (H+PANHs) as candidates for the carriers of the diffuse interstellar bands (DIBs). Methods. We obtained the electronic spectra of two protonated PANH cations, protonated acridine and phenanthridine, using parent ion photo-fragment spectroscopy and generated theoretical electronic spectra using ab initio calculations. Results. We show that the spectra of the two species studied here do not correspond to known DIBs. However, based on the general properties derived from the spectra of these small protonated nitrogen-substituted PAHs, we propose that larger H+PANH cations represent good candidates for DIB carriers due to the expected positions of their electronic transitions in the UV-visible and their narrow spectral bands.Comment: 7 pages, 2 figures, accepted for publication in A&

Termites have a Minor Role in the Decomposition of Senescent Grass Tussocks in a Semi-Arid Woodland in Eastern Australia

Decomposition of dead tussocks of 2 grass species (Eragrostis eriopoda and Thyridolepis mitchellima) was studied with and without termites present, both in the absence of large ve.rtebrate herbivores, After 3 years, little tussock residues of either species remained icrespective of treatment, but E. er/opoda decayed much more rapidly than T. mitchellia11a during the first 8 months post mortem (c. 275 cf, 13 kg/ha/month respectively). Thereafter, rate of decay differed little between species. Overall, removal of termites had no significant effect, The data presented in this paper therefore suggest that abiotic processes are dominant influences mediating litter decomposition of above-ground litter in these semi-arid ecosystems.

Inductive and Electrostatic Acceleration in Relativistic Jet-Plasma Interactions

We report on the observation of rapid particle acceleration in numerical simulations of relativistic jet-plasma interactions and discuss the underlying mechanisms. The dynamics of a charge-neutral, narrow, electron-positron jet propagating through an unmagnetized electron-ion plasma was investigated using a three-dimensional, electromagnetic, particle-in-cell computer code. The interaction excited magnetic filamentation as well as electrostatic plasma instabilities. In some cases, the longitudinal electric fields generated inductively and electrostatically reached the cold plasma wave-breaking limit, and the longitudinal momentum of about half the positrons increased by 50% with a maximum gain exceeding a factor of 2 during the simulation period. Particle acceleration via these mechanisms occurred when the criteria for Weibel instability were satisfied.Comment: Revised for Phys. Rev. Lett. Please see publised version for best graphic

The excluded 3-minors for vf-safe delta-matroids

Vf-safe delta-matroids have the desirable property of behaving well under certain duality operations. Several important classes of delta-matroids are known to be vf-safe, including the class of ribbon-graphic delta-matroids, which is related to the class of ribbon graphs or embedded graphs in the same way that graphic matroids correspond to graphs. In this paper, we characterize vf-safe delta-matroids and ribbon-graphic deltamatroids by finding the minimal obstructions, called excluded 3-minors, to membership in the class. We find the unique (up to twisted duality) excluded 3-minor within the class of set systems for the class of vf-safe delta-matroids. In the literature, binary delta-matroids appear in many different guises, with appropriate notions of minor operations equivalent to that of 3-minors, perhaps most notably as graphs with vertex minors. We give a direct explanation of this equivalence and show that some well-known results may be expressed in terms of 3-minors

Composition and sensory properties of Cabernet Sauvignon wine aged in French versus American oak barrels

Cabernet Sauvignon wine aged in similarly coopered, lightly charred French and American oak barrels had increased titratable acidity and decreased pH values over the control glass-aged wine, which was primarily the result of extraction of acid from the wood. Extracted volatile acids accounted for 22.5 and 27.5 % of the increase in titratable acidity in American and French barrels, respectively. As with the pH and titratable acidity changes, the increase in total and nonflavonoid phenols extracted from the barrels was greater in the French than in the American oak-aged wines. Potassium increased significantly with barre! aging in the American oak samples, with no significant difference occuring between the control and the French. In sensory difference tests, all oak-aged wines could be discriminated from the glass-aged control. However, in comparing wines aged in French and American oak for the same time, only those aged for 115 d were significantly different (P < 0.05).Zusammensetzung und sensorische Eigenschaften von Cabernet-Sauvignon-Wein nach Lagerung in französischen und amerikanischen EichenfässernKalifornischer Cabernet-Sauvignon-Wein des Jahrgangs 1980 wurde 115, 239 und 338 d lang in neuen Eichenfässern (228 1) gelagert, die in den USA (Missouri) und Frankreich (Nevers) nach ähnlichen Verfahren gefertigt worden waren. Wein, der in 19-1-Glasballons unter denselben Bedingungen gelagert wurde, diente als Kontrolle. Die Eichenfaß-gelagerten Weine besaßen signifikant höhere Gehalte an titrierbarer Säure (TA), flüchtiger Säure (VA), Äthanol, Gesamtphenolen (TP), polymeren Phenolen (PP) und nicht-flavonoiden Phenolen (NFP) als die Kontrolle. In französischen Eichenfässern gelagerter Wein zeigte einen signifikant niedrigeren Kaliumspiegel und signifikant höhere Gehalte an TA, VA, TP und NFP als Wein aus amerikanischen Fässern. Während die erhöhte Äthanolkonzentration durch die Verdunstung von Wasser zustande kam, stieg der Gehalt an TA, VA, TP und NFP hauptsächlich infolge der Extraktion aus dem Eichenholz an. Die signifikant höheren Werte der PP waren das Ergebnis einer schnelleren Polymerisierung von flavonoiden Weinphenolen in den Eichengebinden. Im sensorischen Triangeltest unterschied sich der Kontrollwein signifikant von beiden faßgelagerten Weinen; ein Vergleich der Weine, die gleich lang in französischen und amerikanischen Eichenfässern lagerten, zeigte nur bei den 115 d lang gelagerten Weinen einen signifikanten Unterschied

Radiative Models of Sagittarius A* and M87 from Relativistic MHD Simulations

Ongoing millimeter VLBI observations with the Event Horizon Telescope allow unprecedented study of the innermost portion of black hole accretion flows. Interpreting the observations requires relativistic, time-dependent physical modeling. We discuss the comparison of radiative transfer calculations from general relativistic MHD simulations of Sagittarius A* and M87 with current and future mm-VLBI observations. This comparison allows estimates of the viewing geometry and physical conditions of the Sgr A* accretion flow. The viewing geometry for M87 is already constrained from observations of its large-scale jet, but, unlike Sgr A*, there is no consensus for its millimeter emission geometry or electron population. Despite this uncertainty, as long as the emission region is compact, robust predictions for the size of its jet launching region can be made. For both sources, the black hole shadow may be detected with future observations including ALMA and/or the LMT, which would constitute the first direct evidence for a black hole event horizon.Comment: 8 pages, 2 figures, submitted to the proceedings of AHAR 2011: The Central Kiloparse

Influence of the ice structure on the soft UV photochemistry of PAHs embedded in solid water

The UV photoreactivity of polycyclic aromatic hydrocarbons (PAHs) in porous amorphous solid water has long been known to form both oxygenated photoproducts and photofragments. The aim of this study was to examine the influence of the ice structure upon reactivity under soft UV irradiation conditions. Mixtures of PAHs with amorphous solid water (porous and compact) and crystalline (cubic and hexagonal) ices were prepared in a high vacuum chamber and irradiated using a mercury lamp for up to 2.5 hours. The results show that the production of oxygenated PAHs is efficient only in amorphous water ice, while fragmentation can occur in both amorphous and crystalline ices. We conclude that the reactivity is driven by PAH-water interactions in favourable geometries, notably where dangling bonds are available at the surface of pores. These results suggest that the formation of oxygenated PAH molecules is most likely to occur in interstellar environments with porous (or compact) amorphous solid water and that this reactivity could considerably influence the inventory of aromatics in meteorites.Comment: Accepted for publication in A&

Robustness of the Blandford-Znajek mechanism

The Blandford-Znajek mechanism has long been regarded as a key ingredient in models attempting to explain powerful jets in AGNs, quasars, blazzars etc. In such mechanism, energy is extracted from a rotating black hole and dissipated at a load at far distances. In the current work we examine the behaviour of the BZ mechanism with respect to different boundary conditions, revealing the mechanism robustness upon variation of these conditions. Consequently, this work closes a gap in our understanding of this important scenario.Comment: 7 pages, accepted in CQ