4,447 research outputs found
The edge of the periphery: situating the ≠Khomani San of the Southern Kalahari in the political economy of Southern Africa
This is an Accepted Manuscript of an article published by Taylor & Francis in African Identities on 14/04/16, available online: http://www.tandfonline.com/10.1080/14725843.2016.1154813In this article, we situate the Southern Kalahari San within the political economy of Southern Africa and within the world system. Here we draw on and critique modernization theory as a model of explanation for the lack of development found locally. In the Southern Kalahari, the ≠Khomani San won a massive land claim that should have empowered and enabled local development. Yet they remain largely impoverished, while seeking out a meaningful life on the edge of the capitalist world system. Within states, contradictions remain as local diversity continues to be reproduced and modernity itself is reproduced as local diversity. The research is premised on empirical fieldwork conducted in the Southern Kalahari in 2013 and supported by a series of earlier field research over the previous five years. The San of the Southern Kalahari are not resisting modernity but drawing on aspects of it selectively for their own vision of meaningful development
Developing a Pipeline of African Global Surgery Scholars
Global surgery is developing as new discipline in many countries. Global surgery primarily aims to improve access to quality surgery in low-and-middle Income countries (LMICs). Thus, ensuring appropriate LMIC representation and leadership in global surgery research, projects, and innovations, is essential. There is a paucity of pathways for students and young clinicians in LMICs to attain training in and exposure to global surgery research and projects. If equity in global surgery leadership and scholarship is truly desired, steps need to be taken to ensure that more students and young clinicians in LMICs are exposed to global surgery as an academic discipline and are offered pathways to practice and leadership. This paper explores ways of ensuring this through increased exposure, increased training and increased funding
Mycobacterium bovis Strains Causing Smear-Positive Human Tuberculosis, Southwest Ireland
Mycobacterium bovis caused 3% of human tuberculosis cases in southwest Ireland during 1998–2006. Of 11 M. bovis strains genotyped, 9 belonged to common animal spoligotypes. Seven strains were from sputum and potential sources of human-centered disease transmission. Ten-locus variable-number tandem repeat typing gave unique strain profiles and would detect disease outbreaks
Inflationary models inducing non-Gaussian metric fluctuations
We construct explicit models of multi-field inflation in which the primordial
metric fluctuations do not necessarily obey Gaussian statistics. These models
are realizations of mechanisms in which non-Gaussianity is first generated by a
light scalar field and then transferred into curvature fluctuations. The
probability distribution functions of the metric perturbation at the end of
inflation are computed. This provides a guideline for designing strategies to
search for non-Gaussian signals in future CMB and large scale structure
surveys.Comment: 4 pages, 7 figure
Colors of 2625 Quasars at 0<z<5 Measured in the Sloan Digital Sky Survey Photometric System
We present an empirical investigation of the colors of quasars in the Sloan
Digital Sky Survey (SDSS) photometric system. The sample studied includes 2625
quasars with SDSS photometry. The quasars are distributed in a 2.5 degree wide
stripe centered on the Celestial Equator covering square degrees.
Positions and SDSS magnitudes are given for the 898 quasars known prior to SDSS
spectroscopic commissioning. New SDSS quasars represent an increase of over
200% in the number of known quasars in this area of the sky. The ensemble
average of the observed colors of quasars in the SDSS passbands are well
represented by a power-law continuum with (). However, the contributions of the bump
and other strong emission lines have a significant effect upon the colors. The
color-redshift relation exhibits considerable structure, which may be of use in
determining photometric redshifts for quasars. The range of colors can be
accounted for by a range in the optical spectral index with a distribution
(95% confidence), but there is a red tail in the
distribution. This tail may be a sign of internal reddening. Finally, we show
that there is a continuum of properties between quasars and Seyfert galaxies
and we test the validity of the traditional division between the two classes of
AGN.Comment: 66 pages, 15 figures (3 color), accepted by A
Optical and Radio Properties of Extragalactic Sources Observed by the FIRST and SDSS Surveys
We discuss the optical and radio properties of 30,000 FIRST sources
positionally associated with an SDSS source in 1230 deg of sky. The
majority (83%) of the FIRST sources identified with an SDSS source brighter
than r=21 are optically resolved. We estimate an upper limit of 5% for the
fraction of quasars with broad-band optical colors indistinguishable from those
of stars. The distribution of quasars in the radio flux -- optical flux plane
supports the existence of the "quasar radio-dichotomy"; 8% of all quasars with
i<18.5 are radio-loud and this fraction seems independent of redshift and
optical luminosity. The radio-loud quasars have a redder median color by 0.08
mag, and a 3 times larger fraction of objects with red colors. FIRST galaxies
represent 5% of all SDSS galaxies with r<17.5, and 1% for r<20, and are
dominated by red galaxies. Magnitude and redshift limited samples show that
radio galaxies have a different optical luminosity distribution than non-radio
galaxies selected by the same criteria; when galaxies are further separated by
their colors, this result remains valid for both blue and red galaxies. The
distributions of radio-to-optical flux ratio are similar for blue and red
galaxies in redshift-limited samples; this similarity implies that the
difference in their luminosity functions, and resulting selection effects, are
the dominant cause for the preponderance of red radio galaxies in flux-limited
samples. We confirm that the AGN-to-starburst galaxy number ratio increases
with radio flux, and find that radio emission from AGNs is more concentrated
than radio emission from starburst galaxies (abridged).Comment: submitted to AJ, color gif figures, PS figures available from
[email protected]
Can sacrificial feeding areas protect aquatic plants from herbivore grazing? Using behavioural ecology to inform wildlife management
Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor) to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i) food quantity, (ii) food quality, and (iii) the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems
Red and Reddened Quasars in the Sloan Digital Sky Survey
We investigate the continuum and emission line properties of 4576 SDSS
quasars as a function of their optical/UV SEDs. The optical/UV color
distribution of our sample is roughly Gaussian, but with a red tail; we
distinguish between 1) intrinsically blue (optically flat) quasars, 2)
intrinsically red (optically steep) quasars, and 3) the 273 (6%) of our quasars
whose continua are inconsistent with a single power-law and appear redder due
to SMC-like dust reddening rather than synchrotron emission. The color
distribution suggests that the population of moderately dust reddened
broad-line quasars is smaller than that of unobscured quasars, but we estimate
that a further 10% of the luminous quasar population is missing from the SDSS
sample because of dust extinction with E(B-V)<0.5. We also investigate the
emission and absorption line properties of these quasars as a function of color
with regard to Boroson & Green type eigenvectors. Intrinsically red (optically
steep) quasars tend to have narrower Balmer lines and weaker CIV, CIII], HeII
and 3000A bump emission as compared with bluer (optically flatter) quasars. The
change in strength of the 3000A bump appears to be dominated by the Balmer
continuum and not by FeII emission. The dust reddened quasars have even
narrower Balmer lines and weaker 3000A bumps, in addition to having
considerably larger equivalent widths of [OII] and [OIII] emission. The
fraction of broad absorption line quasars (BALQSOs) increases from ~3.4% for
the bluest quasars to perhaps as large as 20% for the dust reddened quasars,
but the intrinsic color distribution is affected by dust reddening. (abridged)Comment: 37 pages, 10 figures (3 color), 2 tables, accepted by AJ. For a
version with higher quality figures, see
ftp://astro.princeton.edu/gtr/redqsos/RichardsGT_redqsos.revised3.preprint.p
A cardinal role for cathepsin D in co-ordinating the host-mediated apoptosis of macrophages and killing of pneumococci
The bactericidal function of macrophages against pneumococci is enhanced by their apoptotic demise, which is controlled by the anti-apoptotic protein Mcl-1. Here, we show that lysosomal membrane permeabilization (LMP) and cytosolic translocation of activated cathepsin D occur prior to activation of a mitochondrial pathway of macrophage apoptosis. Pharmacological inhibition or knockout of cathepsin D during pneumococcal infection blocked macrophage apoptosis. As a result of cathepsin D activation, Mcl-1 interacted with its ubiquitin ligase Mule and expression declined. Inhibition of cathepsin D had no effect on early bacterial killing but inhibited the late phase of apoptosis-associated killing of pneumococci in vitro. Mice bearing a cathepsin D-/- hematopoietic system demonstrated reduced macrophage apoptosis in vivo, with decreased clearance of pneumococci and enhanced recruitment of neutrophils to control pulmonary infection. These findings establish an unexpected role for a cathepsin D-mediated lysosomal pathway of apoptosis in pulmonary host defense and underscore the importance of apoptosis-associated microbial killing to macrophage function
Are red 2MASS QSOs young?
We use photometric data from Spitzer to explore the mid- and far-IR
properties of 10 red QSOs (J-K>2, R-K>5) selected by combining the 2MASS in the
NIR with the SDSS at optical wavelengths. Optical and/or near-infrared spectra
are available for 8/10 sources. Modeling the SED from UV to far-IR shows that
moderate dust reddening (A_V=1.3-3.2) can explain the red optical and near-IR
colours of the sources in the sample. There is also evidence that red QSOs have
60/12micron luminosity ratio higher than PG QSOs (97% significance). This can
be interpreted as a higher level of star-formation in these systems (measured
by the 60micron luminosity) for a given AGN power (approximated by the 12micron
luminosity). This is consistent with a picture where red QSOs represent an
early phase of AGN evolution, when the supermassive black hole is enshrouded in
dust and gas clouds, which will eventually be blown out (possibly by AGN driven
outflows) and the system will appear as typical optically luminous QSO. There
is also tentative evidence significant at the 96% level that red 2MASS QSOs are
more often associated with radio emission than optically selected SDSS QSOs.
This may indicate outflows, also consistent with the young AGN interpretation.
We also estimate the space density of red QSOs relative to optically selected
SDSS QSOs, taking into account the effect of dust extinction and the intrinsic
luminosity of the sources. We estimate that the fraction of red QSOs in the
overall population increases from 3% at M_K=-27.5mag to 12% at M_K=-29.5mag.
This suggests that reddened QSOs become more important at the bright end of the
Luminosity Function. If red QSOs are transition objects on the way to becoming
typical optically luminous QSOs, the low fractions above suggest that these
systems spent <12% of their lifetime at the "reddened" stage.Comment: Accepted by MNRA
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