Kinematical & Chemical Characteristics of the Thin and Thick Disks

I discuss how the chemical abundance distributions, kinematics and age distributions of stars in the thin and thick disks of the Galaxy can be used to decipher the merger history of the Milky Way, a typical large galaxy. The observational evidence points to a rather quiescent past merging history, unusual in the context of the `consensus' cold-dark-matter cosmology favoured from observations of structure on scales larger than individual galaxies.Comment: 12 pages, 4 figures; review at IAU Symposium 254, `The Galaxy Disk in Cosmological Context', Copenhagen, June 2008, eds J. Andersen, J. Bland-Hawthorn & B. Nordstro

The star-formation history of the Milky Way Galaxy

The star-formation histories of the main stellar components of the Milky Way constrain critical aspects of galaxy formation and evolution. I discuss recent determinations of such histories, together with their interpretation in terms of theories of disk galaxy evolution.Comment: Invited review, IAU Symposium 258; 12 pages, 1 figur

Exploring Jewish forms of speaking to God : the use of apostrophe in David Rosenmann-Taub’s Cortejo y epinicio

textIn his first published collection of poetry, Cortejo y epinicio (1949), Chilean author David Rosenmann-Taub (1927) references Jewish culture, prayers and beliefs. This project seeks to foreground the Jewishness in his work, as well as the cross-cultural spaces it creates. One of the central means in which Rosenmann-Taub explores Jewish forms of relating to God is through the use of apostrophe. The first section of this essay offers a theoretical framework for discussing apostrophe in poetry and prayer. The three following sections focus on three poems – “Elegía y Kadisch,” “Gólgota,” and “Schabat” – that depict speakers talking to or about God. Their reactions range from continued pleading with God, in the hope of hearing some response, to an attempt to speak for God to a refusal to address God at all. With each section, I consider the poem alongside the Jewish prayers and conventions that serve as a reference point for the poem’s rewritten prayers to God. This comparison not only highlights the notable presence of Jewish forms in Rosenmann-Taub’s poetry, but also points to how he challenges and reframes them. Rosenmann-Taub dramatizes the thresholds between belief and disbelief, divine and earthly, to point to the construction of faith as a mode of being that collapses these boundaries. In the final section of the essay, I situate Rosenmann-Taub’s work within its historical and literary context to highlight the ways in which his inquiries resonate with other poetic works emerging in Chile at that moment in time, as well as how he builds on them by representing Jewishness, heterogeneity, and heterodoxy as part of Chilean culture.Comparative Literatur

A Neural Network Architecture for Figure-ground Separation of Connected Scenic Figures

A neural network model, called an FBF network, is proposed for automatic parallel separation of multiple image figures from each other and their backgrounds in noisy grayscale or multi-colored images. The figures can then be processed in parallel by an array of self-organizing Adaptive Resonance Theory (ART) neural networks for automatic target recognition. An FBF network can automatically separate the disconnected but interleaved spirals that Minsky and Papert introduced in their book Perceptrons. The network's design also clarifies why humans cannot rapidly separate interleaved spirals, yet can rapidly detect conjunctions of disparity and color, or of disparity and motion, that distinguish target figures from surrounding distractors. Figure-ground separation is accomplished by iterating operations of a Feature Contour System (FCS) and a Boundary Contour System (BCS) in the order FCS-BCS-FCS, hence the term FBF, that have been derived from an analysis of biological vision. The FCS operations include the use of nonlinear shunting networks to compensate for variable illumination and nonlinear diffusion networks to control filling-in. A key new feature of an FBF network is the use of filling-in for figure-ground separation. The BCS operations include oriented filters joined to competitive and cooperative interactions designed to detect, regularize, and complete boundaries in up to 50 percent noise, while suppressing the noise. A modified CORT-X filter is described which uses both on-cells and off-cells to generate a boundary segmentation from a noisy image.Air Force Office of Scientific Research (90-0175); Army Research Office (DAAL-03-88-K0088); Defense Advanced Research Projects Agency (90-0083); Hughes Research Laboratories (S1-804481-D, S1-903136); American Society for Engineering Educatio