814 research outputs found
NEW VISIONS OF THE PAST – TECHNOLOGY AND THE CREATION OF MEMORY SPACE IN SOUTH AFRICAN MUSEUMS
Post-Apartheid South Africa is demanding a revised approach to the construction of museums
and memory space, seeking to identify a new form of museum that assists in reflecting the
history of Apartheid while facilitating community growth and commonality. This paper examines
two differing approaches: The Apartheid Museum in Johannesburg; and The Red Location
Museum near Port Elizabeth. Both museums present evolving solutions to the challenge of
creating meaningful museum space and exemplify how design technology is responding to
emerging questions of how to deal with recent and emotionally raw historical events. The
Apartheid Museum follows the experientially based linear model to create a simulated sense of
history incorporating persuasive architecture with digital technology. In so doing a slick,
international package of the past is produced. In contrast, The Red Museum re-thinks the mode
of construction, materiality and linear narrative tradition in museums to create a new kind of
space, open and flexible, which is situated in the heart of the township it serves. Dignified and
refined, this museum re-positions the past as an entity in the present, acknowledging and
celebrating a uniquely African mode of understanding and conveying history. Both regarded as
highly successful in their own right, the museums identify ways in which new technology can be
applied in the construction of current historical narratives and reveal how technologies can be
redirected to allow for the emergence of new perspectives. In this respect, architecture
contributes to the construction of new political narratives, using space and technology to subtly
convey emotive messages around historical events
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Learning together: Lessons from a collaborative curriculum design project
Based on an action research project implemented at two South African universities, we argue that content and language integration (ICL) collaborative partnerships benefit not only from collaboration between language and content specialists, but in addition, from collaboration between language specialists, general education specialists and content specialists from a variety of disciplines. However, as we illustrate below, these benefits may be accompanied by substantial challenges. We make a further claim, for the value of a transformative approach towards collaboration for content and language integration, in which the teacher/researchers engage in their practice in a critical and reflexive manner, and by so doing, foster their own deep learning, as well as the deep learning of the students
Rematerialising Heritage
The Rocks is one of Sydney's premier tourist locations; its identity largely founded on the perception of it as a historically significant site. This perception is steeped in complex notions of the `authentic tourist experience offered at The Rocks, which arguably originates from the retention of some of the early streets and architectures of the area. However, implicit in the act of retention is also the act of deletion. Throughout the area of The Rocks, gaps exist. These are the spaces where buildings, houses, outhouses, lanes and indeed whole streets have been eradicated to make way for urban progress or to redefine areas of the city according to political or economic aims. Heritage here is constructed, not only from that which is retained and preserved but also from that which is deleted and destroyed. This paper seeks to examine the fate of one particular street in the Rocks Princes Street that was eradicated in 1927 to make way for the Sydney Harbour Bridge. The physical demolition of the street and subsequent erasure of any material sign of it has effectively allowed the street to disappear. The predominant historical narrative that results reveals the extent to which current notions of the past are fundamentally understood through the existence of the material artefact. Yet this paper argues that definitions of the past can be drawn, not only from the material or architectural object that operates as historical proof but also from the social, performative and touristic acts that might be undertaken around the object, the architecture or even its representation
Point X-ray sources in the SNR G 315.4-2.30 (MSH 14-63, RCW 86)
We report the results of a search for a point X-ray source (stellar remnant)
in the southwest protrusion of the supernova remnant G 315.4-2.30 (MSH 14-63,
RCW 86) using the archival data of the Chandra X-ray Observatory. The search
was motivated by a hypothesis that G 315.4-2.30 is the result of an
off-centered cavity supernova explosion of a moving massive star, which ended
its evolution just near the edge of the main-sequence wind-driven bubble. This
hypothesis implies that the southwest protrusion in G 315.4-2.30 is the
remainder of a pre-existing bow shock-like structure created by the interaction
of the supernova progenitor's wind with the interstellar medium and that the
actual location of the supernova blast center is near the center of this
hemispherical structure. We have discovered two point X-ray sources in the
"proper" place. One of the sources has an optical counterpart with the
photographic magnitude , while the spectrum of the source can be
fitted with an optically thin plasma model. We interpret this source as a
foreground active star of late spectral type. The second source has no optical
counterpart to a limiting magnitude . The spectrum of this source can
be fitted almost equally well with several simple models (power law: photon
index ; two-temperature blackbody: keV, km and
keV, km; blackbody plus power law: keV,
photon index ). We interpret this source as a candidate stellar remnant
(neutron star), while the photon index and non-thermal luminosity of the source
(almost the same as those of the Vela pulsar and the recently discovered pulsar
PSR J 0205+6449 in the supernova remnant 3C 58) suggest that it can be a young
"ordinary" pulsar.Comment: 7 pages, 6 figures,revised version accepted for publication in A&
Identification of the Mass Donor Star's Spectrum in SS 433
We present spectroscopy of the microquasar SS 433 obtained near primary
eclipse and disk precessional phase Psi = 0.0, when the accretion disk is
expected to be most ``face-on''. The likelihood of observing the spectrum of
the mass donor is maximized at this combination of orbital and precessional
phases since the donor is in the foreground and above the extended disk
believed to be present in the system. The spectra were obtained over four
different runs centered on these special phases. The blue spectra show clear
evidence of absorption features consistent with a classification of A3-7 I. The
behavior of the observed lines indicates an origin in the mass donor. The
observed radial velocity variations are in anti-phase to the disk, the
absorption lines strengthen at mid-eclipse when the donor star is expected to
contribute its maximum percentage of the total flux, and the line widths are
consistent with lines created in an A supergiant photosphere. We discuss and
cast doubt on the possibility that these lines represent a shell spectrum
rather than the mass donor itself. We re-evaluate the mass ratio of the system
and derive masses of 10.9 +/- 3.1 Msun and 2.9 +/- 0.7 Msun for the mass donor
and compact object plus disk, respectively. We suggest that the compact object
is a low mass black hole.
In addition, we review the behavior of the observed emission lines from both
the disk/wind and high velocity jets.Comment: submitted to ApJ, 24 pages, 7 figure
Null Geodesics in Five Dimensional Manifolds
We analyze a class of 5D non-compact warped-product spaces characterized by
metrics that depend on the extra coordinate via a conformal factor. Our model
is closely related to the so-called canonical coordinate gauge of Mashhoon et
al. We confirm that if the 5D manifold in our model is Ricci-flat, then there
is an induced cosmological constant in the 4D sub-manifold. We derive the
general form of the 5D Killing vectors and relate them to the 4D Killing
vectors of the embedded spacetime. We then study the 5D null geodesic paths and
show that the 4D part of the motion can be timelike -- that is, massless
particles in 5D can be massive in 4D. We find that if the null trajectories are
affinely parameterized in 5D, then the particle is subject to an anomalous
acceleration or fifth force. However, this force may be removed by
reparameterization, which brings the correct definition of the proper time into
question. Physical properties of the geodesics -- such as rest mass variations
induced by a variable cosmological ``constant'', constants of the motion and 5D
time-dilation effects -- are discussed and are shown to be open to experimental
or observational investigation.Comment: 19 pages, REVTeX, in press in Gen. Rel. Gra
The 69 ms Radio Pulsar Near the Supernova Remnant RCW 103
We report the detection of the radio pulsar counterpart to the 69 ms X-ray
pulsar discovered near the supernova remnant RCW 103 (G332.4-0.4). Our
detection confirms that the pulsations arise from a rotation-powered neutron
star, which we name PSR J1617-5055. The observed barycentric period derivative
confirms that the pulsar has a characteristic age of only 8 kyr, the sixth
smallest of all known pulsars. The unusual apparent youth of the pulsar and its
proximity to a young remnant requires that an association be considered.
Although the respective ages and distances are consistent within substantial
uncertainties, the large inferred pulsar transverse velocity is difficult to
explain given the observed pulsar velocity distribution, the absence of
evidence for a pulsar wind nebula, and the symmetry of the remnant. Rather, we
argue that the objects are likely superposed on the sky; this is reasonable
given the complex area. Without an association, the question of where is the
supernova remnant left behind following the birth of PSR J1617-5055 remains
open. We also discuss a possible association between PSR J1617-5055 and the
gamma-ray source 2CG 333+01. Though an association is energetically plausible,
it is unlikely given that EGRET did not detect 2CG 333+01.Comment: 18 pages, 2 encapsulated Postscript figures, uses AAS LaTeX style
files. Accepted for publication in The Astrophysical Journal Letter
Formation of a disk-structure and jets in the symbiotic prototype Z And during its 2006-2010 active phase
We present an analysis of spectrophotometric observations of the latest cycle
of activity of the symbiotic binary Z And from 2006 to 2010. We estimate the
temperature of the hot component of Z And to be \approx 150000 - 170000 K at
minimum brightness, decreasing to \approx 90000 K at the brightness maximum.
Our estimate of the electron density in the gaseous nebula is
N_{e}=10^{10}-10^{12} cm^{-3} in the region of formation of lines of neutral
helium and 10^6-10^7 cm^{-3} in the region of formation of the [OIII] and
[NeIII] nebular lines. A trend for the gas density derived from helium lines to
increase and the gas density derived from [OIII] and [NeIII] lines to
simultaneously decrease with increasing brightness of the system was observed.
Our estimates show that the ratios of the theoretical and observed fluxes in
the [OIII] and [NeIII] lines agree best when the O/Ne ratio is similar to its
value for planetary nebulae. The model spectral energy distribution showed
that, in addition to a cool component and gaseous nebula, a relatively cool
pseudophotosphere (5250-11 500 K) is present in the system. The simultaneous
presence of a relatively cool pseudophotosphere and high-ionization spectral
lines is probably related to a disk-like structure of the pseudophotosphere.
The pseudophotosphere formed very rapidly, over several weeks, during a period
of increasing brightness of Z And. We infer that in 2009, as in 2006, the
activity of the system was accompanied by a collimated bipolar ejection of
matter. In contrast to the situation in 2006, the jets were detected even
before the system reached its maximum brightness. Moreover, components with
velocities close to 1200 km/s disappeared at the maximum, while those with
velocities close to 1800 km/s appeared.Comment: 18 pages, 19 figures, Accepted for publication in Astronomy Report
Older Babies - More Active Mothers? How Maternal Labor Supply Changes as the Child Grows
Female labor market activity is dependent on the presence and the age of a child, but how do the determinants develop in magnitude and significance with the child's age? Using German SOEP data from 1991 to 2006 for mothers with young children, the change in maternal labor supply when the child is one, two, and three years old is explicitly addressed. According to the tobit regression results for precise working hours, maternal labor supply becomes increasingly responsive to economic incentives - mainly to imputed wages - as the child grows
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