63 research outputs found

    Late syn- to post-collisional magmatism in Madagascar: the genesis of the Ambalavao and Maevarano Suites

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    The East African Orogen involves a collage of Proterozoic microcontinents and arc terranes that became wedged between older cratonic blocks during the assembly of Gondwana. The Ediacaran–Cambrian Ambalavao and Maevarano Suites in Madagascar were emplaced during the waning orogenic stages and consist of weakly deformed to undeformed plutonic rocks and dykes of mainly porphyritic granite but also gabbro, diorite and charnockite. U-Pb geochronological data date emplacement of the Ambalavao Suite to between ca. 580 Ma and 540 Ma and the Maevarano Suite to between ca. 537 Ma and 522 Ma. Major and trace element concentrations are consistent with emplacement in a syn- to post-collisional tectonic setting as A-type (anorogenic) suites. Oxygen (ÎŽÂč⁞O of 5.27‰–7.45‰) and hafnium (ΔHf(t) of –27.8 to –12.3) isotopic data from plutons in the Itremo and Antananarivo Domains are consistent with incorporation of an ancient crustal source. More primitive ÎŽÂč⁞O (5.27‰–5.32‰) and ΔHf(t) (+0.0 to +0.2) isotopic values recorded in samples collected from the Ikalamavony Domain demonstrate the isotopic variation of basement sources present in the Malagasy crust. The Hf isotopic composition of Malagasy zircon are unlike more juvenile Ediacaran–Cambrian zircon sources elsewhere in the East African Orogen and, as such, Madagascar represents a distinct and identifiable detrital zircon source region in Phanerozoic sedimentary provenance studies. Taken together, these data indicate that high-T crustal anatexis, crustal assimilation and interaction of crustal material with mantle-derived melts were the processes operating during magma emplacement. This magmatism was coeval with polyphase deformation throughout Madagascar during the amalgamation of Gondwana and magmatism is interpreted to reflect lithospheric delamination of an extensive orogenic plateau.Donnelly B. Archibald, Alan S. Collins, John D. Foden, Justin L. Payne, Peter Holden, ThĂ©odore Razakamanan

    Information ontrol and the exercise of power in the obstetrical encounter

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    Interactions between doctor and patient involve participants with unequal power and possibly different interests. While a number of studies have focused upon the doctor/patient relationship, few have examined the utility of the concept of power and its capacity to help us understand the outcome of these interactions. The information sought by pregnant women from their obstetricians is used to provide a case study of one conceptualization and test of the utility of the concept of power. Pregnant women and their obstetricians are found to have different perceptions of the information that should be exchanged during their interactions. Women generally fail to obtain the information they want. Lower social class patients desire more and obtain less information than their higher status counterparts

    Crystal structure of dichlorido(4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane)iron(III) hexafluoridophosphate

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    The title compound, [FeCl₂(C₁₄H₃₀N₄)]PF₆, contains FeÂłâș coordinated by the four nitro­gen atoms of an ethyl­ene cross-bridged cyclam macrocycle and two cis chloride ligands in a distorted octa­hedral environment. In contrast to other similar compounds this is a monomer. Inter­molecular C-H...Cl inter­actions exist in the structure between the complex ions. Comparison with the mononuclear FeÂČâș complex of the same ligand shows that the smaller FeÂłâș ion is more fully engulfed by the cavity of the bicyclic ligand. Comparison with the ÎŒ-oxido dinuclear complex of an unsubstituted ligand of the same size demonstrates that the methyl groups of 4,11-dimethyl-1,4,8,11-tetra­aza­bicyclo­[6.6.2]hexa­decane prevent dimerization upon oxidation

    The Australian Reproductive Genetic Carrier Screening Project (Mackenzie's Mission): Design and Implementation

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    Published: 28 October 2022Reproductive genetic carrier screening (RGCS) provides people with information about their chance of having children with autosomal recessive or X-linked genetic conditions, enabling informed reproductive decision-making. RGCS is recommended to be offered to all couples during preconception or in early pregnancy. However, cost and a lack of awareness may prevent access. To address this, the Australian Government funded Mackenzie’s Mission—the Australian Reproductive Genetic Carrier Screening Project. Mackenzie’s Mission aims to assess the acceptability and feasibility of an easily accessible RGCS program, provided free of charge to the participant. In study Phase 1, implementation needs were mapped, and key study elements were developed. In Phase 2, RGCS is being offered by healthcare providers educated by the study team. Reproductive couples who provide consent are screened for over 1200 genes associated with >750 serious, childhood-onset genetic conditions. Those with an increased chance result are provided comprehensive genetic counseling support. Reproductive couples, recruiting healthcare providers, and study team members are also invited to complete surveys and/or interviews. In Phase 3, a mixed-methods analysis will be undertaken to assess the program outcomes, psychosocial implications and implementation considerations alongside an ongoing bioethical analysis and a health economic evaluation. Findings will inform the implementation of an ethically robust RGCS program.Alison D. Archibald ... Tristan Hardy ... et al. and The Mackenzie’s Mission Study Tea

    A Review of the fossil record of turtles of the clade Baenidae

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    The fossil record of the turtle clade Baenidae ranges from the Early Cretaceous (Aptian—Albian) to the Eocene. The group is present throughout North America during the Early Cretaceous, but is restricted to the western portions of the continents in the Late Cretaceous and Paleogene. No credible remains of the clade have been reported outside of North America to date. Baenids were warmadapted freshwater aquatic turtles that supported high levels of diversity at times through niche partitioning, particularly by adapting to a broad range of dietary preferences ranging from omnivorous to molluscivorous. Current phylogenies place Baenidae near the split of crown-group Testudines. Within Baenidae three more inclusive, named clades are recognized: Baenodda, Palatobaeninae and Eubaeninae. A taxonomic review of the group concludes that of 49 named taxa, 30 are nomina valida, 12 are nomina invalida and 7 are nomina dubia

    A new periodical on mammals

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    Structure of the K-T mammal radiation in North America: speculations on turnover rates and trophic structure

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    Preliminary results from Montana and New Mexico (USA) indicate that appearance rates for mammal species increase from the latest Cretaceous (Lancian) into the early Paleocene (Puercan) with a slight decline into the middle Paleocene (Torrejonian). Disappearance rates decline over the same interval and equal appearance rates by the Torrejonian. These results are the opposite of those found by Van Valen (1978). Some groups (condylarthrans) have more frequent speciation events and . shorter species durations than suggested by Stanley (1979). The overall appearance rate for the K-T interval is very similar to that for the Paleocene-Eoeene transition (both about 1 sp./10⁎ yrs.). The overall disappearance rate for the K-T interval (1.4 sp./10⁎ yrs.) is markedly higher than for the Paleocene—Eocene transition (0.5 sp./10⁎ yrs.). With the extinction of dinosaurs, “guilds” of small mammals are re-established and new “guilds” form after about 2.5X10⁔ years. Appearance rates are highest during guild establishment

    New material and reinterpretation of the Late Cretaceous eutherian mammal Paranyctoides from Uzbekistan

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    Paranyctoides aralensis, based on a partially known set of lower postcanines from the Turonian Bissekty Formation of Uzbekistan, is proposed to be a junior subjective synonym of Sailestes quadrans, itself based on an M1 from the same stratigraphic unit. As a result, the latter taxon is recombined as Paranyctoides quadrans comb. nov. Based on newly col− lected or recognized specimens, we show that this species has four lower incisors, including a procumbent i1 and a rela− tively small i4, as well as five double−rooted premolars, the smallest of which (p3) can be lost ontogenetically. The p5 of this species is premolariform, rather than molariform as previously thought based on an erroneous identification, and re− sembles North American species of Paranyctoides in the presence of a small, cingulid−like paraconid and a distal talonid cusp, as well as the absence of a metaconid. The lower molars of Paranyctoides are unique among Late Cretaceous eutherians in having a larger, lingually placed paraconid. Paranycoides probably is the sister taxon of the Late Cretaceous Zhelestidae

    New specimens of the multituberculate mammal Uzbekbaatar from the Late Cretaceous of Uzbekistan

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    Uzbekbaatar Kielan−Jaworowska and Nessov, 1992 is among the rarest mammals and the only multituberculate in the diverse, eutherian dominated Bissekty (Turonian) and Aitym (?Coniacian) local faunas, Kyzylkum Desert, Uzbekistan. New material from the Bissekty local fauna, suggests that only one multituberculate species, Uzbekbaatar kizylkumensis Kielan−Jaworowska and Nessov, 1992 is present in the Bissekty fauna. A newly collected p4 is better preserved than the holotype and demonstrates presence of the posterolabial cusp in the p4 of Uzbekbaatar. New material of Uzbekbaatar is consistent with placement of this taxon within the basal cimolodontan “Paracimexomys group.
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