4,817 research outputs found
Parsing the Urban Poverty Puzzle A Multi-generational Panel Study in Rio de Janeiro’s Favelas, 1968–2008
This paper describes the methodology of a longitudinal multi-generational study in the favelas (shantytowns) of Rio de Janeiro from 1968 to 2008. Major political transformations took place in Brazil during this interval: from dictatorship to ‘opening’ to democracy; major economic transformations from ‘miracle’ boom to hyperinflation and crisis, and to relative stability; and major policy changes from the removal of favelas to their upgrading and integration. However, despite the cumulative effects of these contextual changes, poverty programmes and community efforts, the favela population has continued to grow faster than the rest of the city and the number and size of the favelas has consistently increased over these decades.urbanization, Brazil, poverty, community, slums
Globalization and the urban poor
The focus of this paper is the effect of contemporary globalization on poverty and inequality in cities of the ‘global south’. Specifically it addresses the impact of globalization on marginalized communities—slums, squatter settlements and shantytowns—collectively called ‘informal settlements’. This is a timely issue given that over the next 25 years virtually all of the population growth worldwide will be in the cities of developing countries largely concentrated in such settlements. The paper takes a critical look at current assumptions about globalization, urban poverty, and inequality, distinguishing between different constructs and aspects of globalization and separating causality from co-terminality. It questions how the informal sector would fare in the face of advanced capitalism and technological transformations, absent the global component. Using Brazil as an example the paper draws comparisons between the lives of the poor during the isolationist period of ‘import substitution’ and the military dictatorship and their current lives in the context of pervasive globalization of ideas, icons, and identities. The findings are based on a longitudinal panel study conducted in the favelas of Rio de Janeiro between 1968 and 2005, examining the changes over time, space and generations. The presumed effects of globalization on the lives of the urban poor, on the levels of inequality between them and the rest of the city and on public policy are thrown into question. The answers are sought in the people’s perceptions of the impact of globalization on their lives, in the historic transformations of the country and city, and in the life history, survey data and open-ended interviews collected over this 35- year period
Detection of Exceptional X-Ray Spectral Variability in the TeV BL Lac 1ES 2344+514
We present the results of six BeppoSAX observations of 1ES 2344+514, five of
which were taken within a week. 1ES 2344+514, one of the few known TeV BL Lac
objects, was detected by the BeppoSAX Narrow Field Instruments between 0.1 to
\~50 keV. During the first five closely spaced observations 1ES 2344+514 showed
large amplitude luminosity variability, associated with spectacular spectral
changes, particularly when compared to the last observation when the source was
found to be several times fainter, with a much steeper X-ray spectrum. The
energy dependent shape of the lightcurve and the spectral changes imply a large
shift (factor of 30 or more in frequency) of the peak of the synchrotron
emission. At maximum flux the peak was located at or above 10 keV, making 1ES
2344+514 the second blazar (after MKN501) with the synchrotron peak in the hard
X-ray band. The shift, and the corresponding increase in luminosity, might be
due to the onset of a second synchrotron component extending from the soft to
the hard X-ray band where most of the power is emitted. Rapid variability on a
timescale of approximately 5000 seconds has also been detected when the source
was brightest.Comment: 7 pages, LaTeX, 6 PostScript figures. Accepted by MNRA
The Deep X-ray Radio Blazar Survey (DXRBS). II. New Identifications
We have searched the archived, pointed ROSAT Position Sensitive Proportional
Counter data for blazars by correlating the WGACAT X-ray database with several
publicly available radio catalogs, restricting our candidate list to
serendipitous X-ray sources with a flat radio spectrum (alpha_r <= 0.70). This
makes up the Deep X-ray Radio Blazar Survey (DXRBS). Here we present new
identifications and spectra for 106 sources, including 86 radio-loud quasars,
11 BL Lacertae objects, and 9 narrow-line radio galaxies. Together with our
previously published objects and already known sources, our sample now contains
298 identified objects: 234 radio-loud quasars (181 flat-spectrum quasars: FSRQ
[alpha_r <= 0.50] and 53 steep-spectrum quasars: SSRQ), 36 BL Lacs, and 28
narrow-line radio galaxies. Redshift information is available for 96% of these.
Thus our selection technique is ~ 90% efficient at finding radio-loud quasars
and BL Lacs. Reaching 5 GHz radio fluxes ~ 50 mJy and 0.1-2.0 keV X-ray fluxes
a few x 10^-14 erg/cm^2/s, DXRBS is the faintest and largest flat-spectrum
radio sample with nearly complete (~ 85%) identification. We review the
properties of the DXRBS blazar sample, including redshift distribution and
coverage of the X-ray-radio power plane for quasars and BL Lacs. Additionally,
we touch upon the expanded multiwavelength view of blazars provided by DXRBS.
By sampling for the first time the faint end of the radio and X-ray luminosity
functions, this sample will allow us to investigate the blazar phenomenon and
the validity of unified schemes down to relatively low powers.Comment: 33 pages, 5 figures. Accepted for publication in MNRAS. Postscript
file also available at http://www.stsci.edu/~padovani/survey.htm
Murine cytomegalovirus genomic material in marrow cells; relation to altered leukocyte counts during sublethal infection of mice
Discovery of a very X-ray luminous galaxy cluster at z=0.89 in the WARPS survey
We report the discovery of the galaxy cluster ClJ1226.9+3332 in the Wide
Angle ROSAT Pointed Survey (WARPS). At z=0.888 and L_X=1.1e45 erg/s (0.5-2.0
keV, h_0=0.5) ClJ1226.9+3332 is the most distant X-ray luminous cluster
currently known. The mere existence of this system represents a huge problem
for Omega_0=1 world models.
At the modest (off-axis) resolution of the ROSAT PSPC observation in which
the system was detected, ClJ1226.9+3332 appears relaxed; an off-axis HRI
observation confirms this impression and rules out significant contamination
from point sources. However, in moderately deep optical images (R and I band)
the cluster exhibits signs of substructure in its apparent galaxy distribution.
A first crude estimate of the velocity dispersion of the cluster galaxies based
on six redshifts yields a high value of 1650 km/s, indicative of a very massive
cluster and/or the presence of substructure along the line of sight. While a
more accurate assessment of the dynamical state of this system requires much
better data at both optical and X-ray wavelengths, the high mass of the cluster
has already been unambiguously confirmed by a very strong detection of the
Sunyaev-Zel'dovich effect in its direction (Joy et al. 2001).
Using ClJ1226.9+3332 and ClJ0152.7-1357 (z=0.835), the second-most distant
X-ray luminous cluster currently known and also a WARPS discovery, we obtain a
first estimate of the cluster X-ray luminosity function at 0.8<z<1.4 and
L_X>5e44 erg/s. Using the best currently available data, we find the comoving
space density of very distant, massive clusters to be in excellent agreement
with the value measured locally (z<0.3), and conclude that negative evolution
is not required at these luminosities out to z~1. (truncated)Comment: accepted for publication in ApJ Letters, 6 pages, 2 figures, uses
emulateapj.st
Large-Scale Regular Morphological Patterns in the Radio Jet of NGC 6251
We report on large-scale, regular morphological patterns found in the radio
jet of the nearby radio galaxy NGC 6251. Investigating morphological properties
of this radio jet from the nucleus to a radial distance of 300 arcsec
( 140 kpc) mapped at 1662 MHz and 4885 MHz by Perley, Bridle, &
Willis, we find three chains, each of which consists of five radio knots. We
also find that eight radio knots in the first two chains consist of three small
sub-knots (the triple-knotty substructures). We discuss the observational
properties of these regular morphological patterns.Comment: 8 figures, 15 pages, accepted for publication in A
Critical view of WKB decay widths
A detailed comparison of the expressions for the decay widths obtained within
the semiclassical WKB approximation using different approaches to the tunneling
problem is performed. The differences between the available improved formulae
for tunneling near the top and the bottom of the barrier are investigated.
Though the simple WKB method gives the right order of magnitude of the decay
widths, a small number of parameters are often fitted. The need to perform the
fitting procedure remaining consistently within the WKB framework is emphasized
in the context of the fission model based calculations. Calculations for the
decay widths of some recently found super heavy nuclei using microscopic
alpha-nucleus potentials are presented to demonstrate the importance of a
consistent WKB calculation. The half-lives are found to be sensitive to the
density dependence of the nucleon-nucleon interaction and the implementation of
the Bohr-Sommerfeld quantization condition inherent in the WKB approach.Comment: 18 pages, Late
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