La Trobe University

About: La Trobe University is a education organization based out in Melbourne, Victoria, Australia. It is known for research contribution in the topics: Population & Health care. The organization has 13370 authors who have published 41291 publications receiving 1138269 citations. The organization is also known as: LaTrobe University & LTU.

Primitive basalts and andesites from the Mt. Shasta region, N. California: products of varying melt fraction and water content

Abstract: Quaternary volcanism in the Mt. Shasta region has produced primitive magmas [Mg/(Mg+Fe*)>0.7, MgO>8 wt% and Ni>150 ppm] ranging in composition from high-alumina basalt to andesite and these record variable extents ofmelting in their mantle source. Trace and major element chemical variations, petrologic evidence and the results of phase equilibrium studies are consistent with variations in H2O content in the mantle source as the primary control on the differences in extent of melting. High-SiO2, high-MgO (SiO2=52% and MgO=11 wt%) basaltic andesites resemble hydrous melts (H2O=3 to 5 wt%) in equilibrium with a depleted harzburgite residue. These magmas represent depletion of the mantle source by 20 to 30 wt% melting. High-SiO2, high-MgO (SiO2=58% and MgO=9 wt%) andesites are produced by higher degrees of melting and contain evidence for higher H2O contents (H2O=6 wt%). High-alumina basalts (SiO2=48.5% and Al2O3=17 wt%) represent nearly anhydrous low degree partial melts (from 6 to 10% depletion) of a mantle source that has been only slightly enriched by a fluid component derived from the subducted slab. The temperatures and pressures of last equilibration with upper mantle are 1200°C and 1300°C for the basaltic andesite and basaltic magmas, respectively. A model is developed that satisfies the petrologic temperature constraints and involves magma generation whereby a heterogeneous distribution of H2O in the mantle results in the production of a spectrum of mantle melts ranging from wet (calc-alkaline) to dry (tholeiitic).

Distinguishing irony from deception: Understanding the speaker's second-order intention

Abstract: This study investigated how children detect the attitude behind irony and dis· tinguish it from the attitude conveyed by a white lie. Two hypotheses were tested: (1) the ability to distinguish the second-order intentions of the liar vs. ironist (i.e. what each wants the listener to know) should be a prerequisite for the ability to distinguish ironic from deceptive attitude; (2) the presence of distinctive intonations (sarcastic", sincere) should facilitate the distinction between ironic and deceptive attitude. hve- to 7-year-olds heard two stories which ended in either a deceptive or an ironic statement. Children distinguished between the stories in two ways: (a) in terms of whether the speaker wanted the listener to believe him or not (second­ order intention judgement); (b) in terms of whether the speaker was being mean or nice (attitude judgement). In one condition, the final utterances were distinguished by intonation (sarcastic for the irony, sincere for the lie); in the other condition, the utterances were spoken identically, without intonation, in the form of an indirect quote. Results supported the first but not the second hypothesis, Almost all children who failed to make correct second-order judgements also failed to distinguish which speaker was being mean (ironist) and which was being nice (white liar). However, those who succeeded on the second-order question but failed the attitude question were equally distributed across the intonation and no-intonation con­ ditions, Thus, for children of this age, intonation failed to facilitate the ability to distinguish the negative attitude conveyed by irony from the positive attitude conveyed by a white lie.

Analysis of the assembly profiles for mitochondrial- and nuclear-DNA-encoded subunits into complex I.

Abstract: Complex I of the respiratory chain is composed of at least 45 subunits that assemble together at the mitochondrial inner membrane. Defects in human complex I result in energy generation disorders and are also implicated in Parkinson's disease and altered apoptotic signaling. The assembly of this complex is poorly understood and is complicated by its large size and its regulation by two genomes, with seven subunits encoded by mitochondrial DNA (mtDNA) and the remainder encoded by nuclear genes. Here we analyzed the assembly of a number of mtDNA- and nuclear-gene-encoded subunits into complex I. We found that mtDNA-encoded subunits first assemble into intermediate complexes and require significant chase times for their integration into the holoenzyme. In contrast, a set of newly imported nuclear-gene-encoded subunits integrate with preexisting complex I subunits to form intermediates and/or the fully assembly holoenzyme. One of the intermediate complexes represents a subassembly associated with the chaperone B17.2L. By using isolated patient mitochondria, we show that this subassembly is a productive intermediate in complex I assembly since import of the missing subunit restores complex I assembly. Our studies point to a mechanism of complex I biogenesis involving two complementary processes, (i) synthesis of mtDNA-encoded subunits to seed de novo assembly and (ii) exchange of preexisting subunits with newly imported ones to maintain complex I homeostasis. Subunit exchange may also act as an efficient mechanism to prevent the accumulation of oxidatively damaged subunits that would otherwise be detrimental to mitochondrial oxidative phosphorylation and have the potential to cause disease.