4,010 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
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
IFN-gamma-mediated suppression of coronavirus replication in glial-committed progenitor cells.
The neurotropic JHM strain of mouse hepatitis virus (JHMV) replicates primarily within glial cells following intracranial inoculation of susceptible mice, with relative sparing of neurons. This study demonstrates that glial cells derived from neural progenitor cells are susceptible to JHMV infection and that treatment of infected cells with IFN-gamma inhibits viral replication in a dose-dependent manner. Although type I IFN production is muted in JHMV-infected glial cultures, IFN-beta is produced following IFN-gamma-treatment of JHMV-infected cells. Also, direct treatment of infected glial cultures with recombinant mouse IFN-alpha or IFN-beta inhibits viral replication. IFN-gamma-mediated control of JHMV replication is dampened in glial cultures derived from the neural progenitor cells of type I receptor knock-out mice. These data indicate that JHMV is capable of infecting glial cells generated from neural progenitor cells and that IFN-gamma-mediated control of viral replication is dependent, in part, on type I IFN secretion
Common Naturopathic Therapies for Chronic Conditions
Complementary and Alternative Medicine has started to achieve greater public prominence – many patients report satisfaction and believe these therapies are cost effective. Allopathic physicians are largely unfamiliar with the supplements prescribed by naturopathic doctors, and have trouble integrating these therapies into traditional treatment plans. Patients are not trained to evaluate the safety or efficacy of their medication regimens, and rely on their primary care physicians to provide that service -– even if the majority of their medications are supplements recommended by an alternative provider.https://scholarworks.uvm.edu/fmclerk/1021/thumbnail.jp
What Types of Jets does Nature Make: A New Population of Radio Quasars
We use statistical results from a large sample of about 500 blazars, based on
two surveys, the Deep X-ray Radio Blazar Survey (DXRBS), nearly complete, and
the RASS-Green Bank survey (RGB), to provide new constraints on the spectral
energy distribution of blazars, particularly flat-spectrum radio quasars
(FSRQ). This reassessment is prompted by the discovery of a population of FSRQ
with spectral energy distribution similar to that of high-energy peaked BL
Lacs. The fraction of these sources is sample dependent, being ~ 10% in DXRBS
and ~ 30% in RGB (and reaching ~ 80% for the Einstein Medium Sensitivity
Survey). We show that these ``X-ray strong'' radio quasars, which had gone
undetected or unnoticed in previous surveys, indeed are the strong-lined
counterparts of high-energy peaked BL Lacs and have synchrotron peak
frequencies, nu_peak, much higher than ``classical'' FSRQ, typically in the UV
band for DXRBS. Some of these objects may be 100 GeV - TeV emitters, as are
several known BL Lacs with similar broadband spectra. Our large, deep, and
homogeneous DXRBS sample does not show anti-correlations between nu_peak and
radio, broad line region, or jet power, as expected in the so-called ``blazar
sequence'' scenario. However, the fact that FSRQ do not reach X-ray-to-radio
flux ratios and nu_peak values as extreme as BL Lacs and the elusiveness of
high nu_peak - high-power blazars suggest that there might be an intrinsic,
physical limit to the synchrotron peak frequency that can be reached by
strong-lined, powerful blazars. Our findings have important implications for
the study of jet formation and physics and its relationship to other properties
of active galactic nuclei.Comment: 15 pages, 12 figures. Accepted for publication in The Astrophysical
Journal (May 1 2003 issue). Postscript file also available at
http://www.stsci.edu/~padovani/unif_papers.htm
Month-Timescale Optical Variability in the M87 Jet
A previously inconspicuous knot in the M87 jet has undergone a dramatic
outburst and now exceeds the nucleus in optical and X-ray luminosity.
Monitoring of M87 with the Hubble Space Telescope and Chandra X-ray Observatory
during 2002-2003, has found month-timescale optical variability in both the
nucleus and HST-1, a knot in the jet 0.82'' from the nucleus. We discuss the
behavior of the variability timescales as well as spectral energy distribution
of both components. In the nucleus, we see nearly energy-independent
variability behavior. Knot HST-1, however, displays weak energy dependence in
both X-ray and optical bands, but with nearly comparable rise/decay timescales
at 220 nm and 0.5 keV. The flaring region of HST-1 appears stationary over
eight months of monitoring. We consider various emission models to explain the
variability of both components. The flares we see are similar to those seen in
blazars, albeit on longer timescales, and so could, if viewed at smaller
angles, explain the extreme variability properties of those objects.Comment: 4 pages, 3 figures, ApJ Lett., in pres
Mega-strategies for mega-cities: a project to accelerate the generation of effective social and technological innovation
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