493 research outputs found
Towards a Foucauldian Urban Political Ecology of water: Rethinking the hydro-social cycle and scholars' critical engagement
Thirty years after the death of Michel Foucault, notwithstanding the fact that his thought has profoundly shaped the contemporary reflection and contributed to move beyond structuralism, the Urban Political Ecology in general and the Urban Political Ecology of water in particular are still dominated by Marxist-inspired theoretical frameworks.
This paper aims to provide a theoretical rationale for the development and implementation of a Foucauldian approach to the UPE of water. We show how a Foucauldian approach could shed light on the hydro-social cycle and could be the basis of a specific form of scholarly political engagement
How to govern the urban hydrosocial cycle : archaeo-genealogy of hydromentalities in the Swiss urban water sector between 1850 and 1950
Switzerland appears to be a privileged place to investigate the urban political ecology of tap water because of the specificities of its political culture and organization and the relative abundance of drinking water in the country. In this paper, we refer to a Foucauldian theorization of power that is increasingly employed in the social sciences, including in human geography and political ecology. We also implement a Foucauldian methodology. In particular, we propose an archaeo-genealogical analysis of discourse to apprehend the links between urban water and the forms of governmentality in Switzerland between 1850 and 1950. Results show that two forms of governmentality, namely biopower and neoliberal governmentality, were present in the water sector in the selected period. Nonetheless, they deviate from the models proposed by Foucault, as their periodization and the classification of the technologies of power related to them prove to be much more blurred than Foucault's work, mainly based on France, might have suggested
VLBI observations of weak extragalactic radio sources for the alignment of the future GAIA frame with the ICRF
The space astrometry mission GAIA will construct a dense optical QSO-based
celestial reference frame. For consistency between the optical and radio
positions, it will be important to align the GAIA frame and the International
Celestial Reference Frame (ICRF) with the highest accuracy. Currently, it is
found that only 10% of the ICRF sources are suitable to establish this link,
either because they are not bright enough at optical wavelengths or because
they have significant extended radio emission which precludes reaching the
highest astrometric accuracy. In order to improve the situation, we have
initiated a VLBI survey dedicated to finding additional high-quality radio
sources for aligning the two frames. The sample consists of about 450 sources,
typically 20 times weaker than the current ICRF sources, which have been
selected by cross-correlating optical and radio catalogues. This paper presents
the observing strategy and includes preliminary results of observation of 224
of these sources with the European VLBI Network in June 2007
RX J1643.7+3402: a new bright cataclysmic variable
We report the discovery of a new bright (V12.6) cataclysmic variable star identified with the ROSAT X-ray source RX J1643.7+3402. Spectroscopic and photometric observations show it to be a novalike variable sharing some of the characteristics of the SW Sex sub-class of novalike CVs. The spectroscopic period may be either 2\fh575 or 2\fh885, within the period "gap." A photometric modulation with a probable period of 2\fh595 and an amplitude of 0.1 mag in V is present on most nights and could be either a "positive" or a "negative" superhump modulation (depending on the exact spectroscopic period), indicating the presence of a precessing accretion disk in this system. Rapid variations of 0.1 to 0.2 mag amplitude in V repeat with a time scale of 15 min
A non exhaustive bibliography on gravitational lensing
The authors present a non exhaustive bibliography on "gravitational lensing", totalizing more than 1000 titles. Books (related to) and conference proceedings fully devoted to "gravitational lensing" are listed separately
The optical emission line spectrum of Mark 110
We analyse in detail the rich emission line spectrum of Mark 110 to determine
the physical conditions in the nucleus of this object, a peculiar NLS1 without
any detectable Fe II emission associated with the broad line region and with a
line ratio unusually large for a NLS1. We use 24 spectra
obtained with the Marcario Low Resolution Spectrograph attached at the prime
focus of the 9.2 m Hobby-Eberly telescope at the McDonald observatory. We
fitted the spectrum by identifying all the emission lines (about 220) detected
in the wavelength range 4200-6900 \AA (at rest). The narrow emission lines are
probably produced in a region with a density gradient in the range
10 cm with a rather high column density (5
cm). In addition to a narrow line system, three major broad line systems
with different line velocity and width are required. We confirm the absence of
broad Fe II emission lines. We speculate that Mark 110 is in fact a BLS1 with
relatively "narrow" broad lines but with a BH mass large enough compared to its
luminosity to have a lower than Eddington luminosity.Comment: 13 pages, 5 figures, accepted by A&
The Double Quasar Q2138-431: Lensing by a Dark Galaxy?
We report the discovery of a new gravitational lens candidate Q2138-431AB,
comprising two quasar images at a redshift of 1.641 separated by 4.5 arcsecs.
The spectra of the two images are very similar, and the redshifts agree to
better than 115 km.sec. The two images have magnitudes and
, and in spite of a deep search and image subtraction procedure, no
lensing galaxy has been found with . Modelling of the system
configuration implies that the mass-to-light ratio of any lensing galaxy is
likely to be around , with an absolute lower limit of
for an Einstein-de Sitter universe. We conclude that
the most likely explanation of the observations is gravitational lensing by a
dark galaxy, although it is possible we are seeing a binary quasar.Comment: 17 pages (Latex), 8 postscript figures included, accepted by MNRA
The unusual emission line spectrum of IZw1
Most Seyfert 1s show strong Fe II lines in their spectrum having the velocity
and width of the broad emission lines. To remove the Fe II contribution in
these objects, an accurate template is necessary. We used very high
signal-to-noise, medium resolution archive optical spectra of I Zw 1 to build
such a template.
I Zw 1 is a bright narrow-line Seyfert 1 galaxy. As such it is well suited
for a detailed analysis of its emission line spectrum. Furthermore it is known
to have a very peculiar spectrum with, in addition to the usual broad and
narrow line regions, two emission regions emitting broad and blue shifted [O
III] lines making it a peculiarly interesting object. While analysing the
spectra, we found that the narrow-line region is, unlike the NLR of most
Seyfert 1 galaxies, a very low excitation region dominated by both permitted
and forbidden Fe II lines. It is very similar to the emission spectrum of a
blob in Carinae which is a low temperature (T6 500 K),
relatively high density (N=10 cm) cloud. The Fe II lines
in this cloud are mainly due to pumping via the stellar continuum radiation
field (Verner et al. \cite{verner02}). We did not succeed in modelling the
spectrum of the broad-line region, and we suggest that a non radiative heating
mechanism increases the temperature in the excited H I region, thus providing
the necessary additional excitation of the Fe II lines. For the low-excitation
narrow-line region, we are able to settle boundaries to the physical conditions
accounting for the forbidden and permitted Fe II lines (10N cm; 10U).Comment: 16 pages, 7 figures, 10 tables, 1 ascii file, accepted in A&
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