Renewed diversification is associated with new ecological opportunity in the Neotropical turtle ants.

Ecological opportunity, defined as access to new resources free from competitors, is thought to be a catalyst for the process of adaptive radiation. Much of what we know about ecological opportunity, and the larger process of adaptive radiation, is derived from vertebrate diversification on islands. Here, we examine lineage diversification in the turtle ants (Cephalotes), a species-rich group of ants that has diversified throughout the Neotropics. We show that crown group turtle ants originated during the Eocene (around 46 mya), coincident with global warming and the origin of many other clades. We also show a marked lineage-wide slowdown in diversification rates in the Miocene. Contrasting this overall pattern, a species group associated with the young and seasonally harsh Chacoan biogeographic region underwent a recent burst of diversification. Subsequent analyses also indicated that there is significant phylogenetic clustering within the Chacoan region and that speciation rates are highest there. Together, these findings suggest that recent ecological opportunity, from successful colonization of novel habitat, may have facilitated renewed turtle ant diversification. Our findings highlight a central role of ecological opportunity within a successful continental radiation.

Superparamagnetic gadonanotubes are high-performance MRI contrast agents.

We report the nanoscale loading and confinement of aquated Gd3+n-ion clusters within ultra-short single-walled carbon nanotubes (US-tubes); these Gd3+n@US-tube species are linear superparamagnetic molecular magnets with Magnetic Resonance Imaging (MRI) efficacies 40 to 90 times larger than any Gd3+-based contrast agent (CA) in current clinical use.

Clinicians' choices of restorative materials for children.

BACKGROUND: Recently, there has been an expansion in the range of tooth-coloured restorative materials available. In 1999, the National Health and Medical Research Council recommended clinicians use alternatives to amalgam in children 'where appropriate'. METHODS: A three-part 29-item questionnaire was developed, tested in a focus group, and distributed to members of the Australasian Academy of Paediatric Dentistry (AA; paediatric dentists and paediatric dentistry postgraduate students; n=55), and the Australian and New Zealand Society of Paediatric Dentistry, Victorian Branch (SPD; general dentists and dental therapists; n=50). Participant information, material choices, and six hypothetical clinical scenarios were addressed. RESULTS: The overall response rate was 74 per cent. For both groups, the first ranked factor influencing choice of restorative material for vital primary teeth was child age, and caries experience for vital first permanent molars. For moderate-sized Class I and II restorations in primary molars, a tooth-coloured material was chosen by 92 and 84 per cent respondents respectively. For restoring two separate proximal lesions in a primary molar, 65 per cent chose a tooth-coloured material followed by a stainless steel crown (27 per cent; all AA members), then amalgam (8 per cent). The SPD respondents were significantly more likely to choose glass ionomer cement for Class I and II restorations and for restoring two proximal lesions (all p=0.000) in primary molars than AA respondents, who were more likely to choose composite resins/compomers or amalgam/stainless steel crowns for these restorations. Younger respondents (21-40 years) were significantly more likely to choose composite resins/compomers or amalgam/stainless steel crowns (p=0.048) than older respondents (41-65 years), who were likely to choose glass ionomer cement. CONCLUSIONS: For Class I and II restorations in primary molars, glass ionomer cement was the material chosen most frequently (SPD respondents); preference for amalgam or stainless steel crowns was low (both SPD and AA groups). The wide range of materials chosen for the hypothetical clinical scenarios suggests the need for guidelines on selection of restorative materials, and the need for longitudinal studies to follow actual clinical outcomes of the materials chosen.