MgII absorption systems with W_0 > 0.1 \AA for a radio selected sample of 77 QSOs and their associated magnetic fields at high redshifts

We present a catalogue of MgII absorption systems obtained from high resolution UVES/VLT data of 77 QSOs in the redshift range 0.6 < z < 2.0, and down to an equivalent width W_0 > 0.1 \AA. The statistical properties of our sample are found to be in agreement with those from previous work in the literature. However, we point out that the previously observed increase with redshift of dN/dz for weak absorbers, pertains exclusively to very weak absorbers with W_0 < 0.1 \AA. Instead, dN/dz for absorbers with W_0 in the range 0.1-0.3 \AA actually decreases with redshift, similarly to the case of strong absorbers. We then use this catalogue to extend our earlier analysis of the links between the Faraday Rotation Measure of the quasars and the presence of intervening MgII absorbing systems in their spectra. In contrast to the case with strong MgII absorption systems W_0 > 0.3 \AA, the weaker systems do not contribute significantly to the observed Rotation Measure of the background quasars. This is possibly due to the higher impact parameters of the weak systems compared to strong ones, suggesting that the high column density magnetized material that is responsible for the Faraday Rotation is located within about 50 kpc of the galaxies. Finally, we show that this result also rules out the possibility that some unexpected secondary correlation between the quasar redshift and its intrinsic Rotation Measure is responsible for the association of high Rotation Measure and strong intervening MgII absorption that we have presented elsewhere, since this would have produced an equal effect for the weak absorption line systems, which exhibit a very similar distribution of quasar redshifts.Comment: Accepted for publication in ApJ. 12 pages, 8 figure

The Kinematic Composition of MgII Absorbers

The study of galaxy evolution using quasar absorption lines requires an understanding of what components of galaxies and their surroundings are contributing to the absorption in various transitions. This paper considers the kinematic composition of the class of 0.4 < z < 1.0 MgII absorbers, particularly addressing the question of what fraction of this absorption is produced in halos and what fraction arises from galaxy disks. We design models with various fractional contributions from radial infall of halo material and from a rotating thick disk component. We generate synthetic spectra from lines of sight through model galaxies and compare the resulting ensembles of MgII profiles with the 0.4 < z < 1.0 sample observed with HIRES/Keck. We apply a battery of statistical tests and find that pure disk and pure halo models can be ruled out, but that various models with rotating disk and infall/halo contributions can produce an ensemble that is nearly consistent with the data. A discrepancy in all models that we considered requires the existence of a kinematic component intermediate between halo and thick disk. The variety of MgII profiles can be explained by the gas in disks and halos of galaxies not very much different than galaxies in the local Universe. In any one case there is considerable ambiguity in diagnosing the kinematic composition of an absorber from the low ionization high resolution spectra alone. Future data will allow galaxy morphologies, impact parameters, and orientations, FeII/MgII of clouds, and the distribution of high ionization gas to be incorporated into the kinematic analysis. Combining all these data will permit a more accurate diagnosis of the physical conditions along the line of sight through the absorbing galaxy.Comment: 34 pages including 14 postscript figures; Accepted by the Astrophysical Journal; URL http://www.astro.psu.edu/users/cwc/pubs.htm

Measuring Sustainability

Planning for sustainability is high on many agendas, and tools to measure sustainability have been developed. Sustainable processes are those whose rates are maintained over time without exceeding the innate ability of its surroundings to support the process. We present the necessary conditions along with a new algorithm for measuring the sustainability of processes that integrates the laws of thermodynamics with laws for rate processes. The algorithm permits the assessment of the degree of sustainability of any process, whether ecological, economic, or social, as well as chemical or biological. It is a dynamic approach that applies at any scale and takes into consideration the spatial and temporal factors of processes, thus permitting empirical applications that correspond to real world (dynamic, complex, evolving) conditions across space and time. These characteristics make it especially suitable for applications in the field of spatial planning

American Expatriates and the Building of Alternative Social Space in Toronto, 1965–1977

This article explores the history of U.S. expatriates and draft resisters in alternative political and cultural communities within Toronto during the late 1960s and early 1970s. As such these expatriates were important players in shaping and creating new social spaces, activist politics, and alternative forms of expression generated within the city’s counterculture communities and New Left movements. Aided by their class and racial privilege, many of these expatriates were able to participate in and engage the public culture of the city as few other migrants could. This ability to become part of the Toronto’s alternative neighbourhoods, scenes, and intentional communities was nonetheless facilitated by the transnational connections and objectives that linked local actions with global aspirations and collaborators.Cet article explore l’histoire des expatriés et insoumis américains dans les communautés politiques et culturelles alternatives de Toronto à la fin des années 60 et au début des années 70. Comme tels, ces expatriés ont été des acteurs importants dans l’élaboration et la création de nouveaux espaces sociaux, de la politique militante et d’autres formes d’expression issues du sein des communautés contre culturelles et des mouvements de la Nouvelle gauche. Aidés par la classe et le privilège racial, bon nombre de ces expatriés ont été en mesure de participer à la culture publique de la ville et de l’engager comme peu d’autres migrants. Cette capacité à intégrer les quartiers alternatifs de Toronto, ses scènes et ses communautés intentionnelles a néanmoins été facilitée par les connexions transnationales et les objectifs liant actions locales avec aspirations et collaborateurs mondiaux

An Ambiguous Welcome: Vietnam Draft Resistance, the Canadian State, and Cold War Containment

A significant portion of the growth in American immigration to Canada from the mid- 1960s to the mid-1970s was a consequence of the Vietnam War. For the Canadian government, the appearance of large numbers of draft resisters at the border was a boon. Draft resisters, if not deserters, tended to be young, middle-class, and educated — the very type of immigrant the government wanted. Allowing entry to draft resisters also reaped an important symbolic benefit in that it allowed the Canadian government to demonstrate its independence from the United States and its opposition to the war. In practice, however, not all young Americans resisting militarism were welcomed. Government officials argued contradictory interpretations of the policy on admitting draft resisters and deserters and their legal status in Canada. The Cold War and the increased domestic concerns generated by student and protest movements in the 1960s also solidified cooperation between the American and Canadian security states in maintaining a surveillance of draft resisters and deserters.La guerre du Vietnam explique en bonne partie l’augmentation du nombre d’immigrants américains franchissant la frontière canadienne du milieu des années 1960 jusqu’au milieu de la décennie suivante. Le gouvernement canadien s’est alors réjoui de voir apparaître à ses portes de si nombreux dissidents. C’est que les réfractaires à la conscription (s’agissant parfois même de déserteurs) étaient généralement jeunes, de classe moyenne et instruits. Pour le gouvernement canadien, il s’agissait là de l’immigrant idéal. Accueillir les réfractaires à la conscription lui a aussi procuré un bienfait symbolique de taille, celui de marquer son indépendance par rapport aux États-Unis et son opposition à la guerre. Mais dans les faits, les jeunes Américains résistant au militarisme n’étaient pas tous les bienvenus. Les fonctionnaires faisaient valoir des interprétations contradictoires de la politique d’admission au Canada des réfractaires à l’appel sous les drapeaux et des déserteurs et de leur statut juridique. Ajoutons à cela que la guerre froide et la multiplication des préoccupations intérieures suscitées par les mouvements étudiants et de protestation des années 1960 amenaient également les États américain et cana- dien à collaborer plus étroitement sur le plan de la sécurité pour surveiller les réfractaires et les déserteurs

Effect of pooling samples on the efficiency of comparative studies using microarrays

Many biomedical experiments are carried out by pooling individual biological samples. However, pooling samples can potentially hide biological variance and give false confidence concerning the data significance. In the context of microarray experiments for detecting differentially expressed genes, recent publications have addressed the problem of the efficiency of sample-pooling, and some approximate formulas were provided for the power and sample size calculations. It is desirable to have exact formulas for these calculations and have the approximate results checked against the exact ones. We show that the difference between the approximate and exact results can be large. In this study, we have characterized quantitatively the effect of pooling samples on the efficiency of microarray experiments for the detection of differential gene expression between two classes. We present exact formulas for calculating the power of microarray experimental designs involving sample pooling and technical replications. The formulas can be used to determine the total numbers of arrays and biological subjects required in an experiment to achieve the desired power at a given significance level. The conditions under which pooled design becomes preferable to non-pooled design can then be derived given the unit cost associated with a microarray and that with a biological subject. This paper thus serves to provide guidance on sample pooling and cost effectiveness. The formulation in this paper is outlined in the context of performing microarray comparative studies, but its applicability is not limited to microarray experiments. It is also applicable to a wide range of biomedical comparative studies where sample pooling may be involved.Comment: 8 pages, 1 figure, 2 tables; to appear in Bioinformatic