The first biarmosuchian from the upper Madumabisa Mudstone Formation (Luangwa Basin) of Zambia

This contribution reports the first occurrence of a biarmosuchian therapsid from the upper Madumabisa Mudstone Formation of the Luangwa Basin of northeastern Zambia. Although incomplete, the fossil preserves diagnostic features of post-Biarmosuchus biarmosuchians, such as the presence of a preparietal bone and parasagittal ridges on the basicranial rami of the pterygoids, that allow its unambiguous referral to this group. Based primarily on the record of dicynodonts, the upper Madumabisa Mudstone assemblage can be correlated with the Cistecephalus Assemblage Zone of South Africa. During this interval, the tetrapod faunas of the Karoo and Luangwa basins were remarkably similar and likely characterized by frequent biotic interchange.National Geographic Society grant 8571-08 and 8962-11 The Grainger Foundation and Field Museum/IDP Foundation, Inc. African Partners Program National Science Foundation (EAR-1337569, EAR-1337291, EAR-1336986

Replacement names for the therapsid genera Criocephalus Broom 1928 and Olivieria Brink 1965.

Main articleOur knowledge of premammalian synapsid evolutionary history has benefited from over a hundred years of fossil collecting, especially within the Permo-Triassic sediments of South Africa's Beaufort Group (Rubidge 1995) and the Cis-Ural region of Eastern Europe (Ivachnenko et al. 1997). In the course of our research and discussions we have discovered several errors in the present state of non-mammalian synapsid taxonomy. Here we propose emendations concerning the genera Criocephalus Broom 1928 and Olivieria Brink 1965.Palaeo-Anthropology Scientific Trust; French Embassy in South Africa; Co-operation and Cultural Service

Vacuum Infusion Process Development for Conformal Ablative Thermal Protection System Materials

Conformal ablators are low density composite materials comprised of a flexible carbon felt based fibrous substrate and a high surface area phenolic matrix. These materials are fabricated to near net shape by molding the substrate, placing in a rigid matched mold and infusing with liquid resin through a vacuum assisted process. The open mold process, originally developed for older rigid substrate ablators, such as PICA, wastes a substantial amount of resin. In this work, a vacuum infusion process a type of liquid composite molding where resin is directly injected into a closed mold under vacuum is advanced for conformal ablators. The process reduces waste over the state-of-the-art technique. Small, flat samples of Conformal Phenolic Impregnated Carbon Ablator are infused using the new approach and subjected to a range of curing configurations and conditions. Resulting materials are inspected for quality and compared to material produced using the standard process. Lessons learned inform subsequent plans for process scale up

The vertebrate fauna of the Upper Permian of Niger — II, Preliminary description of a new pareiasaur

Main articleThe skull of a new pareiasaur, Bunostegos akokanensis gen. et sp. nov., is described on the basis of a partial skull from the Upper Permian Moradi Formation of north-central Niger. Autapomorphies of the genus include the presence of three hemispherical bosses at the tip of the snout, an enlarged laterally projecting supraorbital boss positioned on each postfrontal, and additional, smaller bosses on the squamosal and supratemporal bones. Bunostegos is further characterized by a tab-like process of the nasal that articulates with the frontal, a pineal foramen located equidistant between the parietal-frontal and parietal-postparietal sutural contacts, a postparietal that is excluded from the caudal margin of the dorsal skull roof, and a blunt interpterygoid vacuity. The discovery of Bunostegos suggests an unsuspected degree of biogeographic endemism for central West Africa during the Late Permian.Non

Histological evidence of trauma in tusks of southern African dicynodonts

Dicynodonts were a clade of globally-distributed therapsids known for their abundance in the fossil record and for surviving the Permo-Triassic mass extinction. The group had distinctive dental adaptations including a beak and, in many species, paired maxillary tusks. The function of these tusks has long been of interest, yet remains poorly understood.We report here on two instances of unusual morphology in tusk dentine from specimens of: 1) Lystrosaurus from the Karoo Basin of South Africa and, 2) an unidentified dicynodontoid from the Luangwa Basin of Zambia. In both, the cross-sectional shape of the tusk root is lobed and infolded, which histological features suggest is a result of abnormal dentine deposition. We infer that this abnormal morphology is likely the consequence of trauma given its reparative nature and structural similarities to trauma-related morphologies reported in the tusks of modern elephants. This study demonstrates that histological sampling of dicynodont tusks can shed light on the biology of this important clade of therapsids.National Geographic Exploration Grant NGS-158R-18 National Science Foundation PLR-1341304 National Science Foundation DEB-1701383 Palaeontological Scientific TrustJNC201

The impact of early life immune challenge on behavior and microglia during postnatal development

Sexual dichotomy exists in the development, presentation, and course of many neuropsychiatric disorders, including anxiety. Anxiety disorders are one of the earliest psychiatric illnesses to manifest and a role for immune system programming of the developing CNS has emerged in relation to anxiety. Adult rodents neonatally exposed to an immune challenge exhibit increased anxiety-related behaviors. The objective of this study was to determine the impact of postnatal immune challenge on behavior and microglia during the postnatal period and in adulthood. Mice were administered lipopolysaccharide (LPS; 0.05mg/kg, i.p.) or saline on postnatal days (P) three and five. Anxiety-related behavior was assessed during early development on P15 and P21, and re-assessed in adulthood at 10 and 12 weeks. Results reveal sex-specificity in the temporal emergence and phenotypic profile of behaviors displayed by LPS-treated mice. Male LPS-treated mice exhibited reduced exploratory in early development (P15 and P21) that persisted into adulthood. Female LPS-mice exhibited increased anxiety-like behaviors in the EPM in adulthood. These results demonstrate a role for interactions between sex and the immune system in shaping the developmental trajectory of exploratory and anxiety-like behaviors

Excitons in coupled InAs/InP self-assembled quantum wires

Optical transitions in coupled InAs/InP self-assembled quantum wires are studied within the single-band effective mass approximation including effects due to strain. Both vertically and horizontally coupled quantum wires are investigated and the ground state, excited states and the photoluminescence peak energies are calculated. Where possible we compare with available photo-luminescence data from which it was possible to determine the height of the quantum wires. An anti-crossing of the energy of excited states is found for vertically coupled wires signaling a change of symmetry of the exciton wavefunction. This crossing is the signature of two different coupling regimes.Comment: 8 pages, 8 figures. To appear in Physical Review

High-field magnetoexcitons in unstrained GaAs/AlxGa1-xAs quantum dots

The magnetic field dependence of the excitonic states in unstrained GaAs/AlxGa1-xAs quantum dots is investigated theoretically and experimentally. The diamagnetic shift for the ground and the excited states are studied in magnetic fields of varying orientation. In the theoretical study, calculations are performed within the single band effective mass approximation, including band nonparabolicity, the full experimental three-dimensional dot shape and the electron-hole Coulomb interaction. These calculations are compared with the experimental results for both the ground and the excited states in fields up to 50 Tesla. Good agreement is found between theory and experiment

A new cluster-type statistical model for the prediction of deformation textures

An attempt was done to improve the quality of deformation texture predictions by statistical models through the introduction of "clusters" of N grains thus defining a third, intermediate length scale. The interaction between each cluster and the macroscopic length scale is of the Taylor type, whereas inside each cluster a VPSC scheme is used. Predictions of cold rolling deformation textures were quantitatively compared with experimental results for a steel alloy. The results are encouraging