Integrated Stellar Populations: Confronting Photometry with Spectroscopy

We investigate the ability of spectroscopic techniques to yield realistic star formation histories (SFHs) for the bulges of spiral galaxies based on a comparison with their observed broadband colors. Full spectrum fitting to optical spectra indicates that recent (within ~1 Gyr) star formation activity can contribute significantly to the V-band flux, whilst accounting for only a minor fraction of the stellar mass budget which is made up primarily of old stars. Furthermore, recent implementations of stellar population (SP) models reveal that the inclusion of a more complete treatment of the thermally pulsating asymptotic giant branch (TP-AGB) phase to SP models greatly increases the NIR flux for SPs of ages 0.2-2 Gyr. Comparing the optical--NIR colors predicted from population synthesis fitting, using models which do not include all stages of the TP-AGB phase, to the observed colors reveals that observed optical--NIR colors are too red compared to the model predictions. However, when a 1 Gyr SP from models including a full treatment the TP-AGB phase is used, the observed and predicted colors are in good agreement. This has strong implications for the interpretation of stellar populations, dust content, and SFHs derived from colors alone.Comment: 6 pages, 6 figures, accepted for publication in the Astrophysical Journa

Dartmouth Outward Bound Center and the rise of experiential education 1957-1976

Purpose: The article discusses Outward Bound’s participation in the human potential movement through its incorporation of T-group practices and the reform language of experiential education in the late 1960s and early 1970s. Design/methodology/approach: The article reports on original research conducted using materials from Dartmouth College and other Outward Bound collections from 1957-1976. It follows a case study approach to illustrate themes pertaining to Outward Bound’s creation and evolution in the United States, and the establishment of experiential education more broadly. Findings: Building on prior research (Freeman, 2011; Millikan, 2006), the present article elaborates on the conditions under which Outward Bound abandoned muscular Christianity in favor of humanistic psychology. Experiential education provided both a set of practices and a reform language that helped Outward Bound expand into the educational mainstream, which also helped to extend self-expressive pedagogies into formal and nonformal settings. Research implications: The Dartmouth Outward Bound Center’s tenure coincided with and reflected broader cultural changes, from the cold war motif of spiritual warfare, frontier masculinity, and national service to the rise of self-expression in education. Future scholars can situate specific curricular initiatives in the context of these paradigms, particularly in outdoor education. Originality/value: The article draws attention to one of the forms that the human potential movement took in education – experiential education – and the reasons for its adoption. It also reinforces emerging understandings of post-WWII American outdoor education as a product of the cold war and reflective of subsequent changes in the wider culture to a narrower focus on the self

Stellar Populations in Spiral Galaxies

We report preliminary results of the characterization of bulge and inner disk stellar populations for 8 nearby spiral galaxies using Gemini/GMOS. The long-slit spectra extend out to 1-2 disk scale lengths with S/N/Ang > 50. Two different model fitting techniques, absorption-line indices and full spectral synthesis, are found to weigh age, metallicity, and abundance ratios differently, but with careful attention to the data/model matching (resolution and flux calibration), we are able constrain real signatures of age and metallicity gradients in star-forming galaxies.Comment: 4 pages, 3 figures. To appear in the proceedings for IAUS 241 "Stellar Populations as Building Blocks of Galaxies", Eds. R.F. Peletier and A. Vazdeki

Efficient, Superstabilizing Decentralised Optimisation for Dynamic Task Allocation Environments

Decentralised optimisation is a key issue for multi-agent systems, and while many solution techniques have been developed, few provide support for dynamic environments, which change over time, such as disaster management. Given this, in this paper, we present Bounded Fast Max Sum (BFMS): a novel, dynamic, superstabilizing algorithm which provides a bounded approximate solution to certain classes of distributed constraint optimisation problems. We achieve this by eliminating dependencies in the constraint functions, according to how much impact they have on the overall solution value. In more detail, we propose iGHS, which computes a maximum spanning tree on subsections of the constraint graph, in order to reduce communication and computation overheads. Given this, we empirically evaluate BFMS, which shows that BFMS reduces communication and computation done by Bounded Max Sum by up to 99%, while obtaining 60-88% of the optimal utility

Political vs. Currency Premia in International Real Interest Differentials: A Study of Forward Rates for 24 Countries

Different approaches to quantifying the degree of capital mobility for a cross-section of currencies -- particularly saving-investment correlations and tests of real interest parity - have appeared to show a surprisingly low degree of financial market integration. We use a new data set, forward rate data for 24 countries, including many small industrialized countries and seven LDCs, to decompose the real interest differential into two parts: the covered interest differential, or political premium, and the real forward discount, or currency premium. The latter in turn can be decomposed into the exchange risk premium and expected real depreciation. We find a high degree of capital mobility across political boundaries for most of the 011 countries, plus Hong Kong and Singapore, for our sample period of 1982 to 1987. Even for most of the other LDCs and smaller industrialized countries, for which covered interest parity clearly fails, the political premium is not as big a component of the real interest differential as the currency premium. France would appear to have higher capital mobility than most by the criterion of real interest differentials, but is seen in fact to have low capital mobility by the criterion of covered interest differentials, a clear example of the superiority of the latter criterion.

Hamilton-Jacobi Theory and Moving Frames

The interplay between the Hamilton-Jacobi theory of orthogonal separation of variables and the theory of group actions is investigated based on concrete examples.Comment: This is a contribution to the Vadim Kuznetsov Memorial Issue on Integrable Systems and Related Topics, published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

Environmental Effects in the Evolution of Galactic Bulges

We investigate possible environmental trends in the evolution of galactic bulges over the redshift range 0<z<0.6. For this purpose, we construct the Fundamental Plane (FP) for cluster and field samples at redshifts =0.4 and =0.54 using surface photometry based on HST imaging and velocity dispersions based on Keck spectroscopy. As a reference point for our study we include data for pure ellipticals, which we model as single-component Sersic profiles; whereas for multi-component galaxies we undertake decompositions using Sersic and exponential models for the bulge and disk respectively. Although the FP for both distant cluster and field samples are offset from the local relation, consistent with evolutionary trends found in earlier studies, we detect significant differences in the zero point of ~=0.2 dex between the field and cluster samples at a given redshift. For both clusters, the environmentally-dependent offset is in the sense expected for an accelerated evolution of bulges in dense environments. By matching the mass range of our samples, we confirm that this difference does not arise as a result of the mass-dependent downsizing effects seen in larger field samples. Our result is also consistent with the hypothesis that - at fixed mass and environment - the star formation histories of galactic bulges and pure spheroids are indistinguishable, and difficult to reconcile with the picture whereby the majority of large bulges form primarily via secular processes within spiral galaxies.Comment: 5 pages, 3 figures, accepted for publication in ApJ Letter

Climate Change Impact Assessment for Surface Transportation in the Pacific Northwest and Alaska

WA-RD 772.