73 research outputs found

    The postcranial skeleton of monolophosaurus jiangi (dinosauria: Theropoda) from the Middle Jurassic of Xinjiang, China, and a review of Middle Jurassic Chinese theropods

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    The Middle Jurassic was a critical time in the evolution of theropod dinosaurs, highlighted by the origination and radiation of the large-bodied and morphologically diverse Tetanurae. Middle Jurassic tetanurans are rare but have been described from Europe, South America and China. In particular, China has yielded a number of potential basal tetanurans, but these have received little detailed treatment in the literature. Here we redescribe the postcranial skeleton of one of the most complete Chinese Middle Jurassic theropods, Monolophosaurus. Several features confirmthe tetanuran affinities of Monolophosaurus, but the possession of ‘primitive’ traits such as a double-faceted pubic peduncle of the ilium and a hood-like supracetabular crest suggest a basal position within Tetanurae. This conflicts with most published cladistic analyses that place Monolophosaurus in a more derived position within Allosauroidea.We review the Middle Jurassic record of Chinese theropods and compare Monolophosaurus to other Middle Jurassic theropods globally. These comparisons suggest that Monolophosaurus and Chuandongocoelurus formed an endemic theropod clade limited to the Middle Jurassic of Asia. Other Middle Jurassic Chinese theropods deserve further study

    Site-specific spectroscopic measurement of spin and charge in (LuFeO3)m/(LuFe2O4)1 multiferroic superlattices

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    Interface materials offer a means to achieve electrical control of ferrimagnetism at room temperature as was recently demonstrated in (LuFeO3)m/(LuFe2O4)1 superlattices. A challenge to understanding the inner workings of these complex magnetoelectric multiferroics is the multitude of distinct Fe centres and their associated environments. This is because macroscopic techniques characterize average responses rather than the role of individual iron centres. Here, we combine optical absorption, magnetic circular dichroism and first-principles calculations to uncover the origin of high-temperature magnetism in these superlattices and the charge-ordering pattern in the m = 3 member. In a significant conceptual advance, interface spectra establish how Lu-layer distortion selectively enhances the Fe2+ → Fe3+ charge-transfer contribution in the spin-up channel, strengthens the exchange interactions and increases the Curie temperature. Comparison of predicted and measured spectra also identifies a non-polar charge ordering arrangement in the LuFe2O4 layer. This site-specific spectroscopic approach opens the door to understanding engineered materials with multiple metal centres and strong entanglement.Fil: Fan, Shiyu. University of Tennessee; Estados UnidosFil: Das, Hena. Cornell University; Estados UnidosFil: Rébola, Alejandro Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Smith, Kevin. University of Tennessee; Estados UnidosFil: Mundy, Julia. Harvard University; Estados Unidos. Cornell University; Estados UnidosFil: Brooks, Charles. Cornell University; Estados UnidosFil: Holtz, Megan E.. Cornell University; Estados UnidosFil: Muller, David A.. Cornell University; Estados UnidosFil: Fennie, Craig J.. Cornell University; Estados UnidosFil: Ramesh, Ramamoorthy. Lawrence Berkeley National Laboratory; Estados Unidos. University of California at Berkeley; Estados UnidosFil: Schlom, Darrell G.. Cornell University; Estados UnidosFil: McGill, Stephen. National High Magnetic Field Laboratory; Estados UnidosFil: Musfeldt, Janice L.. University of Tennessee; Estados Unido

    Variation, variability, and the origin of the avian endocranium:Insights from the anatomy of alioramus altai (theropoda: Tyrannosauroidea)

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    The internal braincase anatomy of the holotype of Alioramus altai, a relatively small-bodied tyrannosauroid from the Late Cretaceous of Mongolia, was studied using high-resolution computed tomography. A number of derived characters strengthen the diagnosis of this taxon as both a tyrannosauroid and a unique, new species (e.g., endocranial position of the gasserian ganglion, internal ramification of the facial nerve). Also present are features intermediate between the basal theropod and avialan conditions that optimize as the ancestral condition for Coelurosauria--a diverse group of derived theropods that includes modern birds. The expression of several primitive theropod features as derived character states within Tyrannosauroidea establishes previously unrecognized evolutionary complexity and morphological plasticity at the base of Coelurosauria. It also demonstrates the critical role heterochrony may have played in driving patterns of endocranial variability within the group and potentially reveals stages in the evolution of neuroanatomical development that could not be inferred based solely on developmental observations of the major archosaurian crown clades. We discuss the integration of paleontology with variability studies, especially as applied to the nature of morphological transformations along the phylogenetically long branches that tend to separate the crown clades of major vertebrate groups

    Decreasing Burden of Malaria in Pregnancy in Malawian Women and Its Relationship to Use of Intermittent Preventive Therapy or Bed Nets

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    The World Health Organization recommends insecticidal bednets and intermittent preventive treatment to reduce malaria in pregnancy. Longitudinal data of malaria prevalence and pregnancy outcomes are valuable in gauging the impact of these antimalarial interventions.We recruited 8,131 women delivering in a single Malawian hospital over 9 years. We recorded demographic data, antenatal prescription of intermittent preventive therapy during pregnancy with sulfadoxine-pyrimethamine and bed net use, and examined finger-prick blood for malaria parasites and hemoglobin concentration. In 4,712 women, we examined placental blood for malaria parasites and recorded the infant's birth weight. Peripheral and placental parasitemia prevalence declined from 23.5% to 5.0% and from 25.2% to 6.8% respectively. Smaller declines in prevalence of low birth weight and anemia were observed. Coverage of intermittent preventive treatment and bednets increased. Number of sulfadoxine-pyrimethamine doses received correlated inversely with placental parasitemia (Odds Ratio (95% CI): 0.79 (0.68, 0.91)), maternal anemia (0.81, (0.73, 0.90)) and low birth weight from 1997-2001 (0.63 (0.53, 0.75)), but not from 2002-2006. Bednet use protected from peripheral parasitemia (0.47, (0.37, 0.60)) and placental parasitemia (0.41, (0.31, 0.54)) and low birth weight (0.75 (0.59, 0.95)) but not anemia throughout the study. Compared to women without nets who did not receive 2-dose sulfadoxine-pyrimethamine, women using nets and receiving 2-dose sulfadoxine-pyrimethamine were less likely to have parasitemia or low birth weight babies. Women receiving 2-dose sulfadoxine-pyrimethamine alone had little evidence of protection whereas bednets alone gave intermediate protection.Increased bednet coverage explains changes in parasitemia and birth weight among pregnant women better than sulfadoxine-pyrimethamine use. High bed net coverage, and sulfadoxine-pyrimethamine resistance, may be contributing to its apparent loss of effectiveness

    The first definitive carcharodontosaurid (Dinosauria:Theropoda) from Asia and the delayed ascent of tyrannosaurids

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    Little is known about the evolution of large-bodied theropod dinosaurs during the Early to mid Cretaceous in Asia. Prior to this time, Asia was home to an endemic fauna of basal tetanurans, whereas terminal Cretaceous ecosystems were dominated by tyrannosaurids, but the intervening 60 million years left a sparse fossil record. Here, we redescribe the enigmatic large-bodied Chilantaisaurus maortuensis from the Turonian of Inner Mongolia, China. We refer this species to a new genus, Shaochilong, and analyze its systematic affinities. Although Shaochilong has previously been allied with several disparate theropod groups (Megalosauridae, Allosauridae, Tyrannosauroidea, Maniraptora), we find strong support for a derived carcharodontosaurid placement. As such, Shaochilong is the first unequivocal Asian member of Carcharodontosauridae, which was once thought to be restricted to Gondwana. The discovery of an Asian carcharodontosaurid indicates that this clade was cosmopolitan in the Early to mid Cretaceous and that Asian large-bodied theropod faunas were no longer endemic at this time. It may also suggest that the ascent of tyrannosaurids into the large-bodied dinosaurian predator niche was a late event that occurred towards the end of the Cretaceous,between the Turonian and the Campanian
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