3,168 research outputs found
The racist bodily imaginary: the image of the body-in-pieces in (post)apartheid culture
This paper outlines a reoccurring motif within the racist imaginary of (post)apartheid culture: the black body-in-pieces. This disturbing visual idiom is approached from three conceptual perspectives. By linking ideas prevalent in Frantz Fanonâs description of colonial racism with psychoanalytic concepts such as Lacanâs notion of the corps morcelĂ©, the paper offers, firstly, an account of the black body-in-pieces as fantasmatic preoccupation of the (post)apartheid imaginary. The role of such images is approached, secondly, through the lens of affect theory which eschews a representational âreadingâ of such images in favour of attention to their asignifying intensities and the role they play in effectively constituting such bodies. Lastly, Judith Butlerâs discussion of war photography and the conditions of grievability introduces an ethical dimension to the discussion and helps draw attention to the unsavory relations of enjoyment occasioned by such images
The Second APM UKST Colour Survey for z>4 Quasars
We present the spectra, positions, and finding charts for 31 bright (R4.5. The majority are in the southern sky (dec 2.5) colours from UK or POSSII Schmidt Plates scanned at the Automated Plate Measuring facility in Cambridge. Low resolution (~> 10A) spectra were obtained to identify the quasars, primarily at the Las Campanas Observatory. The highest redshift quasar in our survey is at z ~ 4.8 (R = 18.7) and its spectrum shows a damped Lyman-alpha absorption system at z = 4.46. This is currently the highest redshift damped Lyman-alpha absorber detected. Five of these quasars exhibit intrinsic broad absorption line features. Combined with the previously published results from the first part of the APM UKST survey we have now surveyed a total of ~8000 squ deg of sky i.e. 40% of the high galactic latitude (|b|>30 deg) sky, resulting in 59 optically selected quasars in the redshift range 3.85 to 4.78; 49 of which have z>=4.00
A framework for the prospective analysis of super-diversity coming from high levels of immigration
Background
Pressures to keep immigration rates at relatively high levels are likely to persist in most developed countries. At the same time, immigrant cohorts are becoming more and more diverse, leading host societies to become increasingly heterogeneous across multiple dimensions. For scholars who study demographic or socio-economic behaviours, the need to account for ethnocultural âsuper-diversityâ brings new challenges and complications.
Objective
The main objective of this paper is to present a framework for the prospective analysis of super-diversity in several high immigration countries.
Methods
We developed microsimulation models that simultaneously project several population-dimensions for Canada, the United States and countries of the European Union, with the aim of studying the consequences of alternate future population and migration trends.
Results
The paper presents the projected progression of three indicators of diversity for Canada, the USA and the EU28: percentage of foreign-born population, percentage of the population using a non-official language at home and percentage of non-Christians under the reference scenario. Results from alternative scenarios show the potential impact of modifying the composition of migrant cohorts. The paper also examines the projected changes in the labour force for each region by education level and language. Finally, the paper proposes a new longitudinal indicator that counts the number of years lived as active and inactive over the life course for foreign- and native-born cohorts.
Contribution
The microsimulation models provide much more informative results than more traditional cohort-component or multi-state models to study the future effects of ethnocultural super-diversity on high immigration countries
A survey for high-redshift radio-loud quasars: optical spectroscopy of S > 0.2 Jy, flat-spectrum radio sources
We present optical spectroscopic data for a complete sample of 161 S_5GHz >=
0.2 Jy, flat-spectrum radio sources. The sources were observed as part of a
survey for high redshift, radio-loud quasars, and were selected for
spectroscopic follow-up based on criteria of red optical colour and unresolved
optical counterpart, as measured from APM scans of POSS-I plates. 13 objects
from the spectroscopic sample were found to be radio-loud quasars with z > 3,
of which two were previously known. We give positions, E (red) magnitudes, O-E
colours, 5GHz radio fluxes, radio spectral indices, optical spectra and
redshifts where possible for the spectroscopic sample. We also give finding
charts for the z > 3 QSOs. The highest redshift object found is a QSO with z =
4.30 (GB1508+5714, the subject of an earlier Letter). The sample also contains
a z = 3.05 QSO, GB1759+7539, which is optically very luminous (E=16.1). In
addition, spectra are given for 18 S_5GHz >= 0.2 Jy, flat-spectrum radio
sources that do not form part of the complete sample.Comment: 14 pages including tables and figures, except Figs. 3 and 4 (spectra)
which are available from http://panisse.lbl.gov/public/isobelpage/ . To
appear in MNRA
Radio Properties of z>4 Optically-Selected Quasars
We report on two programs to address differential evolution between the
radio-loud and radio-quiet quasar populations at high (z>4) redshift. Both
programs entail studying the radio properties of optically-selected quasars.
First, we have observed 32 optically-selected, high-redshift (z>4) quasars with
the VLA at 6 cm (5 GHz). These sources comprise a statistically complete and
well-understood sample. We detect four quasars above our 3-sigma limit of ~0.15
mJy, which is sufficiently sensitive to detect all radio-loud quasars at the
probed redshift range. Second, we have correlated 134 z>4 quasars, comprising
all such sources that we are aware of as of mid-1999, with FIRST and NVSS.
These two recent 1.4 GHz VLA sky surveys reach 3-sigma limits of approximately
0.6 mJy and 1.4 mJy respectively. We identify a total of 15 z>4 quasars, of
which six were not previously known to be radio-loud. The depth of these
surveys does not reach the radio-loud/radio-quiet demarcation luminosity
density (L(1.4 GHz) = 10^32.5 h(50)^(-2) ergs/s/Hz) at the redshift range
considered; this correlation therefore only provides a lower limit to the
radio-loud fraction of quasars at high-redshift. The two programs together
identify eight new radio-loud quasars at z>4, a significant increase over the
seven currently in the published literature. We find no evidence for radio-loud
fraction depending on optical luminosity for -25 > M_B > -28 at z~2, or for
-26>M_B>-28 at z>4. Our results also show no evolution in the radio-loud
fraction between z~2 and z>4 (-26>M_B>-28).Comment: 19 pages, 7 figures; to appear in The Astronomical Journal (April
2000
The Gemini Deep Deep Survey: II. Metals in Star-Forming Galaxies at Redshift 1.3<z<2
The goal of the Gemini Deep Deep Survey (GDDS) is to study an unbiased sample
of K<20.6 galaxies in the redshift range 0.8<z<2.0. Here we determine the
statistical properties of the heavy element enrichment in the interstellar
medium (ISM) of a subsample of 13 galaxies with 1.34<z<1.97 and UV absolute
magnitude M_2000 < -19.65. The sample contains 38% of the total number of
identified galaxies in the first two fields of the survey with z>1.3. The
selected objects have colors typical of irregular and Sbc galaxies. Strong
[OII] emission indicates high star formation activity in the HII regions
(SFR~13-106 M_sun/yr). The high S/N composite spectrum shows strong ISM MgII
and FeII absorption, together with weak MnII and MgI lines. The FeII column
density, derived using the curve of growth analysis, is logN_FeII =
15.54^{+0.23}_{-0.13}. This is considerably larger than typical values found in
damped Ly-alpha systems (DLAs) along QSO sight lines, where only 10 out of 87
(~11%) have logN_FeII > 15.2. High FeII column densities are observed in the
z=2.72 Lyman break galaxy cB58 (logN_FeII ~ 15.25) and in gamma-ray burst host
galaxies (logN_FeII ~ 14.8-15.9). Given our measured FeII column density and
assuming a moderate iron dust depletion (delta_Fe ~ 1 dex), we derive an
optical dust extinction A_V ~ 0.6. If the HI column density is log N(HI)<21.7
(as in 98% of DLAs), then the mean metallicity is Z/Z_sun > 0.2. The high
completeness of the GDDS sample implies that these results are typical of
star-forming galaxies in the 1<z<2 redshift range, an epoch which has
heretofore been particularly challenging for observational programs.Comment: ApJ in press, corrected HI column density estimat
Heparan sulfate proteoglycans are concentrated on the sinusoidal plasmalemmal domain and in intracellular organelles of hepatocytes
Magnetodielectric coupling in Mn3O4
We have investigated the dielectric anomalies associated with spin ordering
transitions in the tetragonal spinel MnO, using thermodynamic,
magnetic, and dielectric measurements. We find that two of the three magnetic
ordering transitions in MnO lead to decreases in the temperature
dependent dielectric constant at zero applied field. Applying a magnetic field
to the polycrystalline sample leaves these two dielectric anomalies practically
unchanged, but leads to an increase in the dielectric constant at the
intermediate spin-ordering transition. We discuss possible origins for this
magnetodielectric behavior in terms of spin-phonon coupling. Band structure
calculations suggest that in its ferrimagnetic state, MnO corresponds
to a semiconductor with no orbital degeneracy due to strong Jahn-Teller
distortion.Comment: 6 pages, 7 figure
Twenty-Five Years of Landsat Thermal Band Calibration
Landsat-7 Enhanced Thematic Mapper+ (ETM+), launched in April 1999, and Landsat-5 Thematic Mapper (TM), launched in 1984, both have a single thermal band. Both instruments thermal band calibrations have been updated previously: ETM+ in 2001 for a pre-launch calibration error and TM in 2007 for data acquired since the current era of vicarious calibration has been in place (1999). Vicarious calibration teams at Rochester Institute of Technology (RIT) and NASA/Jet Propulsion Laboratory (JPL) have been working to validate the instrument calibration since 1999. Recent developments in their techniques and sites have expanded the temperature and temporal range of the validation. The new data indicate that the calibration of both instruments had errors: the ETM+ calibration contained a gain error of 5.8% since launch; the TM calibration contained a gain error of 5% and an additional offset error between 1997 and 1999. Both instruments required adjustments in their thermal calibration coefficients in order to correct for the errors. The new coefficients were calculated and added to the Landsat operational processing system in early 2010. With the corrections, both instruments are calibrated to within +/-0.7K
Red Parkes-Quasars: Evidence for Soft X-ray Absorption
The Parkes Half-Jansky Flat Spectrum Sample contains a large number of
sources with unusually red optical-to-near-infrared continua. If this is to be
interpreted as extinction by dust in the line-of-sight, then associated
material might also give rise to absorption in the soft X-ray regime. This
hypothesis is tested using broadband (0.1-2.4 keV) data from the {\it ROSAT}
All-Sky Survey provided by Siebert et al. (1998). Significant (
confidence level) correlations between optical (and near-infrared)--to--soft
X-ray continuum slope and optical extinction are found in the data, consistent
with absorption by material with metallicity and a range in gas-to-dust ratio
as observed in the local ISM. Under this simple model, the soft X-rays are
absorbed at a level consistent with the range of extinctions (
magnitudes) implied by the observed optical reddening. Excess X-ray absorption
by warm (ionised) gas, (ie. a `warm absorber') is not required.Comment: 23 pages of text, 3 figures, to appear in Jan 10 (1999) issue of The
Astrophysical Journa
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