Ultraviolet Dust Grain Properties in Starburst Galaxies: Evidence from Radiative Transfer Modeling and Local Group Extinction Curves

This paper summarizes the evidence of the ultraviolet properties of dust grains found in starburst galaxies. Observations of starburst galaxies clearly show that the 2175 A feature is weak or absent. This can be the result of radiative transfer effects (mixing the dust and stars) or due to dust grains which do not have this feature. Spherical DIRTY radiative transfer models imply that it is not radiative transfer effects, but other radiative transfer models with disk/bulge geometries have found cases where it could be radiative transfer effects. Recent work on the extinction curves in the Magellanic Clouds and Milky Way has revealed that the traditional explanation of low metallicity for the absence of the 2175 A feature in the Small Magellanic Cloud is likely incorrect. The SMC has one sightline with a 2175 A feature and the Milky Way has sightlines without this feature. In addition, where the 2175 A feature is found to be weak or absent in both Magellanic Clouds and the Milky Way, there is evidence for recent star formation. Taking the sum of the radiative transfer modeling of starburst galaxies and the behavior of Local Group extinction curves, it is likely that the dust grains in starburst galaxies intrinsically lack the 2175 A feature.Comment: 7 pages, To appear in the proceedings of: "The Spectral Energy Distribution of Gas-Rich Galaxies: Confronting Models with Data", Heidelberg, 4-8 Oct. 2004, eds. C.C. Popescu and R.J. Tuffs, AIP Conf. Ser., in press [fixed typo in title

The Nursing Faculty Shortage: A Crisis for Health Care

Reviews research on the nursing faculty shortage and the need for more doctorate-level training, examines contributing factors, considers current approaches and interventions, and makes recommendations, such as creating a competitive fellowships program

Results of a Survey of Graduate Courses in Applied Welfare Economics

teaching, trade, welfare, Agricultural and Food Policy, International Relations/Trade, Teaching/Communication/Extension/Profession,

ECONOMIC MALAISE SLOWS REFORM: A REVIEW OF CURRENT CONDITIONS IN THE SOVIET UNION

Agricultural and Food Policy,

DISCUSSION: AGRICULTURAL POLICIES, TRADE AGREEMENTS AND DISPUTE SETTLEMENT

Agricultural and Food Policy, International Relations/Trade,

Results of a Survey of Graduate Courses in Agricultural Trade

teaching, agricultural, trade, Agricultural and Food Policy, International Relations/Trade, Teaching/Communication/Extension/Profession,

Automated Morphological Segmentation and Evaluation

In this paper we introduce (i) a new method for morphological segmentation of part of speech labelled German words and (ii) some measures related to the MDL principle for evaluation of morphological segmentations. The segmentation algorithm is capable to discover hierarchical structure and to retrieve new morphemes. It achieved 75 % recall and 99 % precision. Regarding MDL based evaluation, a linear combination of vocabulary size and size of reduced deterministic finite state automata matching exactly the segmentation output turned out to be an appropriate measure to rank segmentation models according to their quality

WHAT WENT WRONG IN SEATTLE?

International Relations/Trade,

Did the WTO Play a Role in the Food Crisis?

When high prices or natural calamities result in starvation and political unrest in the developing world emergency food aid is the best short run response. However, over a longer time frame it is important to have in place international rules that allow the market to function to help alleviate food shortages rather than making them worse. Given Canada’s trading position we have a huge stake in getting these rules right. Although the future of the Doha Round is unclear there is still time to make a start on developing better rules for export prohibitions, restrictions and export taxes that would serve the world better in times of shortage. A first step would be effective disciplines on the use of export taxes, and export restrictions and embargo’s.WTO, food, crisis, Agricultural and Food Policy, International Development, International Relations/Trade,