6,549 research outputs found
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
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 EichenfĂ€ssernKalifornischer Cabernet-Sauvignon-Wein des Jahrgangs 1980 wurde 115, 239 und 338 d lang in neuen EichenfĂ€ssern (228 1) gelagert, die in den USA (Missouri) und Frankreich (Nevers) nach Ă€hnlichen Verfahren gefertigt worden waren. Wein, der in 19-1-Glasballons unter denselben Bedingungen gelagert wurde, diente als Kontrolle. Die EichenfaĂ-gelagerten Weine besaĂen signifikant höhere Gehalte an titrierbarer SĂ€ure (TA), flĂŒchtiger SĂ€ure (VA), Ăthanol, Gesamtphenolen (TP), polymeren Phenolen (PP) und nicht-flavonoiden Phenolen (NFP) als die Kontrolle. In französischen EichenfĂ€ssern gelagerter Wein zeigte einen signifikant niedrigeren Kaliumspiegel und signifikant höhere Gehalte an TA, VA, TP und NFP als Wein aus amerikanischen FĂ€ssern. WĂ€hrend die erhöhte Ăthanolkonzentration durch die Verdunstung von Wasser zustande kam, stieg der Gehalt an TA, VA, TP und NFP hauptsĂ€chlich 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 faĂgelagerten Weinen; ein Vergleich der Weine, die gleich lang in französischen und amerikanischen EichenfĂ€ssern lagerten, zeigte nur bei den 115 d lang gelagerten Weinen einen signifikanten Unterschied
Beyond XSPEC: Towards Highly Configurable Analysis
We present a quantitative comparison between software features of the defacto
standard X-ray spectral analysis tool, XSPEC, and ISIS, the Interactive
Spectral Interpretation System. Our emphasis is on customized analysis, with
ISIS offered as a strong example of configurable software. While noting that
XSPEC has been of immense value to astronomers, and that its scientific core is
moderately extensible--most commonly via the inclusion of user contributed
"local models"--we identify a series of limitations with its use beyond
conventional spectral modeling. We argue that from the viewpoint of the
astronomical user, the XSPEC internal structure presents a Black Box Problem,
with many of its important features hidden from the top-level interface, thus
discouraging user customization. Drawing from examples in custom modeling,
numerical analysis, parallel computation, visualization, data management, and
automated code generation, we show how a numerically scriptable, modular, and
extensible analysis platform such as ISIS facilitates many forms of advanced
astrophysical inquiry.Comment: Accepted by PASP, for July 2008 (15 pages
A wave driver theory for vortical waves propagating across junctions with application to those between rigid and compliant walls
A theory is described for propagation of vortical waves across alternate rigid and compliant panels. The structure in the fluid side at the junction of panels is a highly vortical narrow viscous structure which is idealized as a wave driver. The wave driver is modelled as a âhalf source cum half sinkâ. The incoming wave terminates into this structure and the outgoing wave emanates from it. The model is described by half FourierâLaplace transforms respectively for the upstream and downstream sides of the junction. The cases below cutoff and above cutoff frequencies are studied. The theory completely reproduces the direct numerical simulation results of Davies & Carpenter (J. Fluid Mech., vol. 335, 1997, p. 361). Particularly, the jumps across the junction in the kinetic energy integral, the vorticity integral and other related quantities as obtained in the work of Davies & Carpenter are completely reproduced. Also, some important new concepts emerge, notable amongst which is the concept of the pseudo group velocity
Type II critical phenomena of neutron star collapse
We investigate spherically-symmetric, general relativistic systems of
collapsing perfect fluid distributions. We consider neutron star models that
are driven to collapse by the addition of an initially "in-going" velocity
profile to the nominally static star solution. The neutron star models we use
are Tolman-Oppenheimer-Volkoff solutions with an initially isentropic,
gamma-law equation of state. The initial values of 1) the amplitude of the
velocity profile, and 2) the central density of the star, span a parameter
space, and we focus only on that region that gives rise to Type II critical
behavior, wherein black holes of arbitrarily small mass can be formed. In
contrast to previously published work, we find that--for a specific value of
the adiabatic index (Gamma = 2)--the observed Type II critical solution has
approximately the same scaling exponent as that calculated for an
ultrarelativistic fluid of the same index. Further, we find that the critical
solution computed using the ideal-gas equations of state asymptotes to the
ultrarelativistic critical solution.Comment: 24 pages, 22 figures, RevTeX 4, submitted to Phys. Rev.
Asymptotically Matched Spacetime Metric for Non-Precessing, Spinning Black Hole Binaries
We construct a closed-form, fully analytical 4-metric that approximately
represents the spacetime evolution of non-precessing, spinning black hole
binaries from infinite separations up to a few orbits prior to merger. We
employ the technique of asymptotic matching to join a perturbed Kerr metric in
the neighborhood of each spinning black hole to a near-zone, post-Newtonian
metric farther out. The latter is already naturally matched to a far-zone,
post-Minkowskian metric that accounts for full temporal retardation. The result
is a 4-metric that is approximately valid everywhere in space and in a small
bundle of spatial hypersurfaces. We here restrict our attention to quasi-
circular orbits, but the method is valid for any orbital motion or physical
scenario, provided an overlapping region of validity or buffer zone exists. A
simple extension of such a metric will allow for future studies of the
accretion disk and jet dynamics around spinning back hole binaries
Dynamical response of the Hodgkin-Huxley model in the high-input regime
The response of the Hodgkin-Huxley neuronal model subjected to stochastic
uncorrelated spike trains originating from a large number of inhibitory and
excitatory post-synaptic potentials is analyzed in detail. The model is
examined in its three fundamental dynamical regimes: silence, bistability and
repetitive firing. Its response is characterized in terms of statistical
indicators (interspike-interval distributions and their first moments) as well
as of dynamical indicators (autocorrelation functions and conditional
entropies). In the silent regime, the coexistence of two different coherence
resonances is revealed: one occurs at quite low noise and is related to the
stimulation of subthreshold oscillations around the rest state; the second one
(at intermediate noise variance) is associated with the regularization of the
sequence of spikes emitted by the neuron. Bistability in the low noise limit
can be interpreted in terms of jumping processes across barriers activated by
stochastic fluctuations. In the repetitive firing regime a maximization of
incoherence is observed at finite noise variance. Finally, the mechanisms
responsible for spike triggering in the various regimes are clearly identified.Comment: 14 pages, 24 figures in eps, submitted to Physical Review
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Validation of Reinforced Concrete Modeling Capabilities for Seismic Response
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
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