116 research outputs found
Beyond a state-centric approach to urban informality: Interactions between Delhi’s middle class and the informal service sector
Since the ‘discovery’ of the informality in the early 1970s, its conceptualization has been significantly expanded beyond economic activity to include land-use and service provision. While informality often refers to that which is beyond the reach of the state, urban scholars focused on cities in the global South have shown that governments actively contribute to its production. This article presents original research on relations between
middle class residents and informal-sector workers in Delhi, India. It demonstrates that middle-class associations establish localized regimes that confer legitimacy on the work of street hawkers and waste workers, their use of urban space and the provision of services (e.g. waste collection). Thus, the state is one actor among many that seeks to govern cities, and in many cases localized governance regimes are imposed by non-state actors. I argue that the state should not serve as a key reference point for identifying informality. Instead scholars should focus on governance regimes imposed by state and non-state powerbrokers, and conceptualize informality as that which remains unregulated
Spurious Shear in Weak Lensing with LSST
The complete 10-year survey from the Large Synoptic Survey Telescope (LSST)
will image 20,000 square degrees of sky in six filter bands every few
nights, bringing the final survey depth to , with over 4 billion
well measured galaxies. To take full advantage of this unprecedented
statistical power, the systematic errors associated with weak lensing
measurements need to be controlled to a level similar to the statistical
errors.
This work is the first attempt to quantitatively estimate the absolute level
and statistical properties of the systematic errors on weak lensing shear
measurements due to the most important physical effects in the LSST system via
high fidelity ray-tracing simulations. We identify and isolate the different
sources of algorithm-independent, \textit{additive} systematic errors on shear
measurements for LSST and predict their impact on the final cosmic shear
measurements using conventional weak lensing analysis techniques. We find that
the main source of the errors comes from an inability to adequately
characterise the atmospheric point spread function (PSF) due to its high
frequency spatial variation on angular scales smaller than in the
single short exposures, which propagates into a spurious shear correlation
function at the -- level on these scales. With the large
multi-epoch dataset that will be acquired by LSST, the stochastic errors
average out, bringing the final spurious shear correlation function to a level
very close to the statistical errors. Our results imply that the cosmological
constraints from LSST will not be severely limited by these
algorithm-independent, additive systematic effects.Comment: 22 pages, 12 figures, accepted by MNRA
Rudolf Otto’s ‘The Absolute Other’ and a radical postsecular urban contextualization
This article proposes an idea of radical urban contextualisation that follows Rudolf Otto’s discussion on an encounter with the Absolute Other. The article critically reviews current applications of postsecularism to urban theory formulated in a general framework of Jurgen Habermas’ intervention in the early 21st century. The article argues that contemporary postsecular urban theory cannot fully answer fundamental challenges that contemporary cities are facing – both political and environmental – mostly because it focuses on linguistic and cultural aspects of a city. The article proposes the ‘radicalization’ of postsecularism, engaging directly with the ‘religious experience’ defined by Rudolf Otto as an encounter with The Absolute Other – the unknown and unpredictable. The Absolute Other notion allows to ultimately contextualize every urban situation in order to formulate conditions for future-oriented (post-capitalist) urbanism
Informal rental housing in Colombia: an essential option for low-income households
Around the world, rental housing is frequently seen as secondary to home ownership; yet it plays a crucial role in many countries. In particular, rental housing in urban informal neighbourhoods has a critical but consistently overlooked role in housing the most vulnerable households in the Global South. If better policy and practice are to be pursued, there is a need for improved data on rental housing in urban informal settlements, and in particular, better understanding of ‘the lived experiences of the poor’. This paper responds to these empirical gaps in debates on informality and rental housing with qualitative research on residents’ experiences of informal rented housing in two Colombian cities, Bogotá and Cali. The paper frames informal rental housing as an essential option for diverse low-income households for whom ownership is not accessible or attractive. In this way, it also contributes to policy and theoretical debates calling for a better understanding of the dynamics, possibilities and potential of informal housing
Evidence for the presence of dust in intervening QSO absorbers from the Sloan Digital Sky Survey
We find evidence for dust in the intervening QSO absorbers from the spectra
of QSOs in the Sloan Digital Sky Survey Data Release 1. No evidence is found
for the 2175 A feature which is present in the Milky Way dust extinction curve.
The extinction curve resembles the SMC extinction curve. The observed
Delta(g-i) excess for QSOs with strong absorption systems appears to be a
result of the reddening due to dust in the intervening absorbers.Comment: Poster paper presented at the IAU Colloquium #199 on "Probing
Galaxies through Quasar Absorption Lines" held in Shanghai, China from March
14th to 18th, 200
Transnational migration and urban informality: Ethnicity in Buenos Aires' informal settlements
The Sloan Digital Sky Survey Reverberation Mapping Project: Key Results
We present the final data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping (RM) project, a precursor to the SDSS-V Black Hole Mapper RM program. This data set includes 11 yr photometric and 7 yr spectroscopic light curves for 849 broad-line quasars over a redshift range of 0.1 < z < 4.5 and a luminosity range of L bol = 1044−47.5 erg s−1, along with spectral and variability measurements. We report 23, 81, 125, and 110 RM lags (relative to optical continuum variability) for broad Hα, Hβ, Mg ii, and C iv using the SDSS-RM sample, spanning much of the luminosity and redshift ranges of the sample. Using 30 low-redshift RM active galactic nuclei with dynamical-modeling black hole masses, we derive a new estimate of the average virial factor of logf=0.62±0.07 for the line dispersion measured from the rms spectrum. The intrinsic scatter of individual virial factors is 0.31 ± 0.07 dex, indicating a factor of 2 systematic uncertainty in RM black hole masses. Our lag measurements reveal significant R–L relations for Hβ and Mg ii at high redshift, consistent with the latest measurements based on heterogeneous samples. While we are unable to robustly constrain the slope of the R–L relation for C iv given the limited dynamic range in luminosity, we found substantially larger scatter in C iv lags at fixed L 1350. Using the SDSS-RM lag sample, we derive improved single-epoch (SE) mass recipes for Hβ, Mg ii, and C iv, which are consistent with their respective RM masses as well as between the SE recipes from two different lines, over the luminosity range probed by our sample. The new Hβ and Mg ii recipes are approximately unbiased estimators at given RM masses, but there are systematic biases in the C iv recipe. The intrinsic scatter of SE masses around RM masses is ∼0.45 dex for Hβ and Mg ii, increasing to ∼0.58 dex for C iv
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Ins and outs of the cultural polis: informality, culture and governance in the global South
This paper provides an epistemological critique of informality by focusing on cultural governance in two cities of the global South, Rio de Janeiro, Brazil, and Dakar, Senegal. Aiming to enrich debates about urban creativity and urban cultural policy, which are still mainly focused on and articulated from the global North, we consider the broad field of ‘informality’ research as an entry point for such a discussion. Using case studies from African and Latin American contexts, we focus on the interstices of cultural policy and the borderlands of (in)formality, examining how governmental institutions are entangled in informal processes, and how grassroots cultural interventions become part of mainstream cultural circuits. The analysis sheds light on how these creative spaces of cultural production, located in Southern contexts of urban extremes, contribute to the vitality of informal urbanisms and unsettle predominant views that see them merely as sites ofinfrastructural poverty and social exclusion. The paper suggests that a creative remapping of informality, through an inquiry of the ‘ins’ and ‘outs’ of the cultural polis, could improve our translating capacity of academic discourse into institutional/policy-related operations
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