Australian National University

About: Australian National University is a education organization based out in Canberra, Australian Capital Territory, Australia. It is known for research contribution in the topics: Population & Galaxy. The organization has 34419 authors who have published 109261 publications receiving 4315448 citations. The organization is also known as: The Australian National University & ANU.

Optical Classification of Southern Warm Infrared Galaxies

Abstract: In this paper, we present high-resolution optical spectra and optical classifications from our large sample of 285 warm infrared galaxies 108 < LIR < 1012.5 L☉. We have classified these galaxies using new theoretical lines on the standard optical diagnostic diagrams. We use a theoretical extreme mixing line between the starburst and AGN regions to classify LINER galaxies and we define a theoretical boundary separating AGNs from starbursts. We find that many galaxies previously classified as LINERs appear to lie on a mixing sequence between starburst and AGN type galaxies. These are likely to be of a composite nature with their excitation being a combination of photoionization due to hot stars plus either ionization by a power-law radiation field associated with an AGN or shock excitation where the shock may result from such processes as cooling flows, superwind activity, or an accretion disk around an AGN. We compare our theory-based classification scheme with the previous semiempirical scheme of Veilleux & Osterbrock . We find that our classification method results in 6% ambiguity in classifications between the different diagnostic diagrams compared with 16% ambiguity using the traditional Veilleux & Osterbrock method. We find that 70% of the galaxies in our sample are classified optically as starburst, 17% are Seyfert 2, 4% are Seyfert 1, and 0.4% are LINERs. A further 2% of our sample are certainly composite galaxies. A fraction (20%) of the Seyfert galaxies, 3% of the starburst galaxies, and 71% of the ambiguous galaxies are possibly composite in nature (11% of the total sample).

Flavones induce expression of nodulation genes in Rhizobium

Abstract: To successfully establish nitrogen-fixing root nodules in a legume plant, a Rhizobium requires at least six plasmid-borne genes (designated nodABCDEF) (Djordjevic et al 1985a; Djordjevic et al 1985b), which are arranged in three separate operons (nodABC, nodD and nodFE) (Torok et al 1984; Rossen et al 1985b). Only one nodulation gene, nodD, is expressed by Rhizobium in culture and its gene product, together with substances secreted by the host plant, induces expression of genes in nodABC and nodFE (Innes et al 1985; Rossen et al 1985b). Lac fusions to presently undefined nod genes, located in regions II and IV of the 14 kb nodulation fragment of R. trifolii, also respond to substances in plant exudate (Innes et al 1985). It is therefore likely that these regions, too, are under control of the nodD product. We report here that the inducing activity of washings of undamaged clover roots is due to flavones, and that several structurally related compounds have similar activities.

Zeta, a novel class of glutathione transferases in a range of species from plants to humans

Abstract: Sequence alignment and phylogenetic analysis has identified a new subgroup of glutathione S-transferase (GST)-like proteins from a range of species extending from plants to humans. This group has been termed the Zeta class. An atomic model of the N-terminal domain suggests that the members of the Zeta class have a similar structure to that of other GSTs, binding glutathione in a similar orientation in the G site. Recombinant human GSTZ1-1 has been expressed in Escherichia coli and characterized. The protein is a dimer composed of 24.2 kDa subunits and has minimal glutathione-conjugating activity with ethacrynic acid and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole. Although low in comparison with other GSTs, GSTZ1-1 has glutathione peroxidase activity with t-butyl and cumene hydroperoxides. The members of the Zeta class have been conserved over a long evolutionary period, suggesting that they might have a role in the metabolism of a compound that is common in many living cells.

An introduction to boosting and leveraging

Abstract: We provide an introduction to theoretical and practical aspects of Boosting and Ensemble learning, providing a useful reference for researchers in the field of Boosting as well as for those seeking to enter this fascinating area of research. We begin with a short background concerning the necessary learning theoretical foundations of weak learners and their linear combinations. We then point out the useful connection between Boosting and the Theory of Optimization, which facilitates the understanding of Boosting and later on enables us to move on to new Boosting algorithms, applicable to a broad spectrum of problems. In order to increase the relevance of the paper to practitioners, we have added remarks, pseudo code, "tricks of the trade", and algorithmic considerations where appropriate. Finally, we illustrate the usefulness of Boosting algorithms by giving an overview of some existing applications. The main ideas are illustrated on the problem of binary classification, although several extensions are discussed.

Low Fertility and the State: The Efficacy of Policy

Abstract: Some 30 countries today have fertility rates below 1.5 births per woman. The governments of each of these countries have reported to the United Nations that they consider this rate to be "too low" (United Nations 2004). When fertility is moderately below replacement level the size of subsequent generations falls only slowly and if considered necessary there is an opportunity to supplement the generation size with migration. When fertility remains very low however the generation size falls rapidly and massive migration would be required to offset the decline (United Nations 2000). Hence we can think in terms of a "safety zone" for low fertility. Population dynamics tends to confirm the view of governments that the "safety zone" lies above 1.5 births per woman. (excerpt)