1,546 research outputs found
Evidence for coeval Late Triassic terrestrial impacts from the Rochechouart (France) meteorite crater
High temperature impact melt breccias from the Rochechouart (France)
meteorite crater record magnetization component with antipodal, normal and
reverse polarities. The corresponding paleomagnetic pole for this component
lies between the 220 Ma and 210 Ma reference poles on the Eurasian apparent
polar wander path, consistent with the 214 8 Ma 40Ar/39Ar age of the
crater. Late Triassic tectonic reconstructions of the Eurasian and North
American plates place this pole within 95% confidence limits of the
paleomagnetic pole from the Manicouagan (Canada) meteorite impact crater, which
is dated at 214 1 Ma. Together, these observations reinforce the
hypothesis of a Late Triassic, multiple meteorite impact event on Earth
Does mandatory IFRS adoption improve the information environment?
Author's pre-print version. Final version published in Contemporary Accounting Research. Available online at http://onlinelibrary.wiley.com/We examine the effect of mandatory International Financial Reporting Standards (‘IFRS’) adoption on firms’ information environment. We find that after mandatory IFRS adoption consensus forecast errors decrease for firms that mandatorily adopt IFRS relative to forecast errors of other firms. We also find decreasing forecast errors for voluntary adopters, but this effect is smaller and not robust. Moreover, we show that the magnitude of the forecast errors decrease is associated with the firm-specific differences between local GAAP and IFRS. Exploiting individual analyst level data and isolating settings where investors would benefit more from either increased comparability or higher quality information, we document that the improvement in the information environment is driven both by information and comparability effects. These results are robust to variations in the measurement of information environment quality, forecast horizon, sample composition and tests of earnings management
Ancient DNA Suggests Dwarf and ‘Giant’ Emu Are Conspecific
) is unclear. King Island Emu were mainly distinguished by their much smaller size and a reported darker colour compared to modern Emu. oxidase subunit I (COI) region (1,544 bp), as well as a region of the melanocortin 1 receptor gene (57 bp) were sequenced using a multiplex PCR approach. The results show that haplotypes for King Island Emu fall within the diversity of modern Emu.These data show the close relationship of these emu when compared to other congeneric bird species and indicate that the King Island and modern Emu share a recent common ancestor. King Island emu possibly underwent insular dwarfism as a result of phenotypic plasticity. The close relationship between the King Island and the modern Emu suggests it is most appropriate that the former should be considered a subspecies of the latter. Although both taxa show a close genetic relationship they differ drastically in size. This study also suggests that rates of morphological and neutral molecular evolution are decoupled
Pattern of symptomatic congenital heart disease amongst Oriental neonates: a decade's experience
Between 1981 and 1990, 765 symptomatic neonates with major congenital heart malformations were admitted into the Grantham Hospital. This represented an incidence of 10 per 10,000 live births for Hong Kong. The figure was comparable to those reported for Caucasians. Among the 744 Oriental neonates, obstruction of the pulmonary outflow tract occurred most frequently (281, 37.8%), followed by left ventricular outflow tract obstruction (169, 22.7%), left-to-right shunting (115, 15.5%), complete transposition (92, 12.4%), common mixing situations (62, 8.3%), and miscellaneous causes (25,3.3%). When compared with the available reports from the West, Chinese neonates had a high preference for pulmonary outflow tract obstruction (p<0.005), especially the anomaly of pulmonary atresia and intact ventricular septum. This correlated well with cyanosis as the commonest neonatal presentation (64%). Contrary to previous reports that aortic coarctation was rare among Orientals, this abnormality was observed frequently in our study. The rare occurrence of critical aortic valvar stenosis among Chinese, however, was supported by our present analysis. Other lesions, such as left-to-right shunting and complete transposition, showed no significant racial difference in the frequency of occurrence. Such knowledge concerning the pattern of congenital heart disease amongst Oriental neonates can facilitate early diagnosis and timely referral of babies to the appropriate center for management.published_or_final_versio
OBEDIS Core Variables Project : European Expert Guidelines on a Minimal Core Set of Variables to Include in Randomized, Controlled Clinical Trials of Obesity Interventions
Heterogeneity of interindividual and intraindividual responses to interventions is often observed in randomized, controlled trials for obesity. To address the global epidemic of obesity and move toward more personalized treatment regimens, the global research community must come together to identify factors that may drive these heterogeneous responses to interventions. This project, called OBEDIS (OBEsity Diverse Interventions Sharing - focusing on dietary and other interventions), provides a set of European guidelines for a minimal set of variables to include in future clinical trials on obesity, regardless of the specific endpoints. Broad adoption of these guidelines will enable researchers to harmonize and merge data from multiple intervention studies, allowing stratification of patients according to precise phenotyping criteria which are measured using standardized methods. In this way, studies across Europe may be pooled for better prediction of individuals' responses to an intervention for obesity - ultimately leading to better patient care and improved obesity outcomes.Peer reviewe
A comparison of in vitro properties of resting SOD1 transgenic microglia reveals evidence of reduced neuroprotective function
<p>Abstract</p> <p>Background</p> <p>Overexpression of mutant copper/zinc superoxide dismutase (<it>SOD1</it>) in rodents has provided useful models for studying the pathogenesis of amyotrophic lateral sclerosis (ALS). Microglia have been shown to contribute to ALS disease progression in these models, although the mechanism of this contribution remains to be elucidated. Here, we present the first evidence of the effects of overexpression of mutant (TG G93A) and wild type (TG WT) human <it>SOD1 </it>transgenes on a set of functional properties of microglia relevant to ALS progression, including expression of integrin β-1, spreading and migration, phagocytosis of apoptotic neuronal cell debris, and intracellular calcium changes in response to an inflammatory stimulus.</p> <p>Results</p> <p>TG SOD1 G93A but not TG SOD1 WT microglia had lower expression levels of the cell adhesion molecule subunit integrin β-1 than their NTG control cells [NTG (G93A) and NTG (WT), respectively, 92.8 ± 2.8% on TG G93A, 92.0 ± 6.6% on TG WT, 100.0 ± 1.6% on NTG (G93A), and 100.0 ± 2.7% on NTG (WT) cells], resulting in decreased spreading ability, with no effect on ability to migrate. Both TG G93A and TG WT microglia had reduced capacity to phagocytose apoptotic neuronal cell debris (13.0 ± 1.3% for TG G93A, 16.5 ± 1.9% for TG WT, 28.6 ± 1.8% for NTG (G93A), and 26.9 ± 2.8% for NTG (WT) cells). Extracellular stimulation of microglia with ATP resulted in smaller increase in intracellular free calcium in TG G93A and TG WT microglia relative to NTG controls (0.28 ± 0.02 μM for TG G93A, 0.24 ± 0.03 μM for TG WT, 0.39 ± 0.03 μM for NTG (G93A), and 0.37 ± 0.05 μM for NTG (WT) microglia).</p> <p>Conclusions</p> <p>These findings indicate that, under resting conditions, microglia from mutant <it>SOD1 </it>transgenic mice have a reduced capacity to elicit physiological responses following tissue disturbances and that higher levels of stimulatory signals, and/or prolonged stimulation may be necessary to initiate these responses. Overall, resting mutant <it>SOD1</it>-overexpressing microglia may have reduced capacity to function as sensors of disturbed tissue/cellular homeostasis in the CNS and thus have reduced neuroprotective function.</p
Increased Inter-Colony Fusion Rates Are Associated with Reduced COI Haplotype Diversity in an Invasive Colonial Ascidian Didemnum vexillum
Considerable progress in our understanding of the population genetic changes associated with biological invasions has been made over the past decade. Using selectively neutral loci, it has been established that reductions in genetic diversity, reflecting founder effects, have occurred during the establishment of some invasive populations. However, some colonial organisms may actually gain an ecological advantage from reduced genetic diversity because of the associated reduction in inter-colony conflict. Here we report population genetic analyses, along with colony fusion experiments, for a highly invasive colonial ascidian, Didemnum vexillum. Analyses based on mitochondrial cytochrome oxidase I (COI) partial coding sequences revealed two distinct D. vexillum clades. One COI clade appears to be restricted to the probable native region (i.e., north-west Pacific Ocean), while the other clade is present in widely dispersed temperate coastal waters around the world. This clade structure was supported by 18S ribosomal DNA (rDNA) sequence data, which revealed a one base-pair difference between the two clades. Recently established populations of D. vexillum in New Zealand displayed greatly reduced COI genetic diversity when compared with D. vexillum in Japan. In association with this reduction in genetic diversity was a significantly higher inter-colony fusion rate between randomly paired New Zealand D. vexillum colonies (80%, standard deviation ±18%) when compared with colonies found in Japan (27%, standard deviation ±15%). The results of this study add to growing evidence that for colonial organisms reductions in population level genetic diversity may alter colony interaction dynamics and enhance the invasive potential of newly colonizing species
A Potential New Pathway for Staphylococcus aureus Dissemination: The Silent Survival of S. aureus Phagocytosed by Human Monocyte-Derived Macrophages
Although considered to be an extracellular pathogen, Staphylococcus aureus is able to invade a variety of mammalian, non-professional phagocytes and can also survive engulfment by professional phagocytes such as neutrophils and monocytes. In both of these cell types S. aureus promptly escapes from the endosomes/phagosomes and proliferates within the cytoplasm, which quickly leads to host cell death. In this report we show that S. aureus interacted with human monocyte-derived macrophages in a very different way to those of other mammalian cells. Upon phagocytosis by macrophages, S. aureus persisted intracellularly in vacuoles for 3–4 days before escaping into the cytoplasm and causing host cell lysis. Until the point of host cell lysis the infected macrophages showed no signs of apoptosis or necrosis and were functional. They were able to eliminate intracellular staphylococci if prestimulated with interferon-γ at concentrations equivalent to human therapeutic doses. S. aureus survival was dependent on the alternative sigma factor B as well as the global regulator agr, but not SarA. Furthermore, isogenic mutants deficient in α-toxin, the metalloprotease aureolysin, protein A, and sortase A were efficiently killed by macrophages upon phagocytosis, although with different kinetics. In particular α-toxin was a key effector molecule that was essential for S. aureus intracellular survival in macrophages. Together, our data indicate that the ability of S. aureus to survive phagocytosis by macrophages is determined by multiple virulence factors in a way that differs considerably from its interactions with other cell types. S. aureus persists inside macrophages for several days without affecting the viability of these mobile cells which may serve as vehicles for the dissemination of infection
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