The satellite distribution of M31

(Abridged) The spatial distribution of the Galactic satellite system plays an important role in Galactic dynamics and cosmology, where its successful reproduction is a key test of simulations of galaxy halo formation. Here, we examine its representative nature by conducting an analysis of the 3-dimensional spatial distribution of the M31 subgroup of galaxies. We begin by a discussion of distance estimates and incompleteness concerns, before revisiting the question of membership of the M31 subgroup. Comparison of the distribution of M31 and Galactic satellites relative to the galactic disks suggests that the Galactic system is probably modestly incomplete at low latitudes by ~20%. We find that the radial distribution of satellites around M31 is more extended than the Galactic subgroup; 50% of the Galactic satellites are found within ~100kpc of the Galaxy, compared to ~200kpc for M31. We search for ``ghostly streams'' of satellites around M31, in the same way others have done for the Galaxy, and find several. The lack of M31-centric kinematic data, however, means we are unable to probe whether these streams represent real physical associations. Finally, we find that the M31 satellites are asymmetrically distributed with respect to our line-of-sight to this object, so that the majority of its satellites are on its near side with respect to our line-of-sight. We quantify this result and find it to be significant at the ~3 sigma level. Until such time as a satisfactory explanation for this finding is presented, our results warn against treating the M31 subgroup as complete, unbiased and relaxed.Comment: 15 pages, 9 figures. Accepted for publication in MNRA

A New Galaxy in the Local Group: the Antlia Dwarf Galaxy

We report the discovery of new member of the Local Group in the constellation of Antlia. Optically the system appears to be a typical dwarf spheroidal galaxy of type dE3.5 with no apparent young blue stars or unusual features. A color-magnitude diagram in I, V-I shows the tip of the red giant branch, giving a distance modulus of 25.3 +/- 0.2 (1.15 Mpc +/- 0.1) and a metallicity of -1.6 +/- 0.3. Although Antlia is in a relatively isolated part of the Local Group it is only 1.2 degrees away on the sky from the Local Group dwarf NGC3109, and may be an associated system.Comment: AJ in press, 15 pages, 7 figures, figure 2 in b/w for space saving, full postscript version available at http://www.ast.cam.ac.uk/~gkth/antlia-pp.htm

Extremophiles and their application to veterinary medicine

<p/> <p>Extremophiles are organisms that can grow and thrive in harsh conditions, e.g., extremes of temperature, pH, salinity, radiation, pressure and oxygen tension. Thermophilic, halophilic and radiation-resistant organisms are all microbes, some of which are able to withstand multiple extremes. Psychrophiles, or cold-loving organisms, include not only microbes, but fish that live in polar waters and animals that can withstand freezing. Extremophiles are structurally adapted at a molecular level to withstand these conditions. Thermophiles have particularly stable proteins and cell membranes, psychrophiles have flexible cellular proteins and membranes and/or antifreeze proteins, salt-resistant halophiles contain compatible solutes or high concentrations of inorganic ions, and acidophiles and alkaliphiles are able to pump ions to keep their internal pH close to neutrality. Their interest to veterinary medicine resides in their capacity to be pathogenic, and as sources of enzymes and other molecules for diagnostic and pharmaceutical purposes. In particular, thermostable DNA polymerases are a mainstay of PCR-based diagnostics.</p

Se confronter à l’engagement : discussion autour de trois perspectives critiques

Partant du constat que les pratiques de « communication des sciences » et de « gouvernance scientifique » tendent progressivement à se recouvrir, cette contribution se propose d'explorer les réponses que les chercheurs en sciences sociales – et d'autres acteurs – apportent aux projets européens d'engagement public dans le domaine de la science. Trois initiatives britanniques sont brièvement présentées : le débat national sur les aliments génétiquement modifiés, l'inclusion de « profanes » dans des comités scientifiques consultatifs, et les tentatives d’anticipation des réactions de la société face aux nanosciences et à la biologie de synthèse. Trois perspectives analytiques et politiques sont ensuite exposées : l’analyse « sceptique » aux yeux de laquelle de telles initiatives seraient surtout symboliques et légitimatrices ; la perspective « transitionnelle » pour laquelle elles constitueraient une étape nécessaire mais insuffisante dans le développement de la culture scientifique et politique ; enfin, nous proposons une interprétation « performative ». On conclura par une réflexion plaidant contre l’évaluation réductionniste des initiatives d’engagement.Starting from the observation that “science communication” and “scientific governance” have become partly merged processes, this paper sets out to explore how social scientists and others might respond to current European initiatives in public engagement with science. Three British initiatives are briefly presented: national debate over genetically modified foods, the inclusion of lay members on scientific advisory committees, and attempts to anticipate societal responses to the nanosciences and synthetic biology. Three analytical and policy perspectives are then presented. Firstly, the “sceptical” view that such initiatives are essentially tokenistic and legitmatory. Secondly, the “transitional” perspective that these are a necessary but insufficient stage in the development of scientific and political culture. Finally, a “performative” interpretation is proposed. The paper concludes with an argument against the reductionist evaluation of engagement initiatives

On the local constitution of global futures. Science and democratic engagement in a decentred world.

This essay focuses on the relationship between public engagement with science and larger discussions of globalized and decentred democracy. In particular, it asks whether public engagement on very specific issues and in the form of carefully-planned exercises should be seen as a distraction (or irrelevance) with regard to the democratic process or else as an enhancement and invigoration of it. It will be argued that we cannot tackle these issues of engagement and democracy without considering the wider challenges of governing what are very often globalized, socio-culturally complex and generally-wicked problems. There is a tendency for engagement initiatives to operate at the regional or national levels. But what happens when the issues are presented as crossing borders and boundaries, and when the traditional centres of power seem sidelined by the expressed requirement for ‘global’ governance? Going further, issues of science and technology governance often involve a special concern with the future or, more specifically, the multiple futures suggested by science, technology and innovation and their relationship to our sense of the present. I will suggest that the heterogeneous practices of scientific governance represent both a challenge when it comes to issues such as climate change and global food security but also an important focus for STS scholarship. Finally, and in the spirit of more grounded conclusions, I suggest six ‘red blooded’ principles for public engagement which can at least get us started in addressing these issues.