2,745 research outputs found

    Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface

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    Recent theories and experiments have suggested that strong spin-orbit coupling effects in certain band insulators can give rise to a new phase of quantum matter, the so-called topological insulator, which can show macroscopic entanglement effects. Such systems feature two-dimensional surface states whose electrodynamic properties are described not by the conventional Maxwell equations but rather by an attached axion field, originally proposed to describe strongly interacting particles. It has been proposed that a topological insulator with a single spin-textured Dirac cone interfaced with a superconductor can form the most elementary unit for performing fault-tolerant quantum computation. Here we present an angle-resolved photoemission spectroscopy study and first-principle theoretical calculation-predictions that reveal the first observation of such a topological state of matter featuring a single-surface-Dirac-cone realized in the naturally occurring Bi2_2Se3_3 class of materials. Our results, supported by our theoretical predictions and calculations, demonstrate that undoped compound of this class of materials can serve as the parent matrix compound for the long-sought topological device where in-plane surface carrier transport would have a purely quantum topological origin. Our study further suggests that the undoped compound reached via n-to-p doping should show topological transport phenomena even at room temperature.Comment: 3 Figures, 18 pages, Submitted to NATURE PHYSICS in December 200

    Lateral variability of ichnological content in muddy contourites: Weak bottom currents affecting organisms’ behavior

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    Although bioturbation is commonly recognized in contourites, only a few studies have analyzed the ichnological content of these deposits in detail. These studies have mainly focused on meso-scale bigradational sequence (a coarsening upward followed by a fining-upward sequence resulting from variations in current velocity). Here we present data from gravitational cores collected along the NW Iberian Margin showing systematic variation in ichnological content across proximal to distal depocenters within a large-scale elongated contourite drift. Data demonstrate that tracemakers’ behavior varies depending on the distance relative to the bottom current core. Trace fossils are already known to be a useful tool for studying of contouritic deposits and are even used as criterion for differentiating associated facies (e.g., turbidites, debrites), though not without controversy. We propose a mechanism by which the distance to the bottom current core exerts tangible influence on specific macro-benthic tracemaker communities in contourite deposits. This parameter itself reflects other bottom current features, such as hydrodynamic energy, grain size, nutrient transport, etc. Ichnological analysis can thus resolve cryptic features of contourite drift depositional settings.The contribution and research by JD was funded through the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 792314 (ICON-SE). The research of FJR-T was funded by project CGL2015-66835-P (Secretaría de Estado de Investigacion, Desarrollo e Innovacion, Spain), Research Group RNM-178 (Junta de Andalucía), and Scientific Excellence Unit UCE-2016- 05 (Universidad de Granada). AM’s research is funded by the I2C program of the Xunta de Galicia Postdoctoral programme (ED481B 2016/029-0). The research was conducted as part of “The Drifters Research Group” (RHUL) and “Ichnology and Palaeoenvironment Research Group” (UGR) programs

    The smaller vesicomyid bivalves in the genus Isorropodon (Bivalvia, Vesicomyidae, Pliocardiinae) also harbour chemoautotrophic symbionts

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    Species of Isorropodon are vesicomyid bivalves for which little information is available regarding host phylogeny and bacterial symbioses. In this study we investigated the symbioses in three Isorropodon species from three cold seep areas: Isorropodon bigoti (Gulf of Guinea), Isorropodon megadesmus (Gulf of Cadiz) and Isorropodon perplexum (Eastern Mediterranean). Analysis of bacterial 16S ribosomal RNA gene sequences demonstrated that each vesicomyid species harbours a single symbiont phylotype, that symbionts from the three species cluster together, and that they are closely related to other known vesicomyid symbionts. These results are confirmed by other marker genes (encoding 23S rRNA and APS reductase) and by fluorescence in situ hybridization. Due to their extended depth range and transoceanic distribution Isorropodon species are interesting examples to further study evolutionary processes in bivalve hosts and their associated symbionts

    New mutations at the imprinted Gnas cluster show gene dosage effects of Gsα in postnatal growth and implicate XLαs in bone and fat metabolism, but not in suckling

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    The imprinted Gnas cluster is involved in obesity, energy metabolism, feeding behavior, and viability. Relative contribution of paternally expressed proteins XLαs, XLN1, and ALEX or a double dose of maternally expressed Gsα to phenotype has not been established. In this study, we have generated two new mutants (Ex1A-T-CON and Ex1A-T) at the Gnas cluster. Paternal inheritance of Ex1A-T-CON leads to loss of imprinting of Gsα, resulting in preweaning growth retardation followed by catch-up growth. Paternal inheritance of Ex1A-T leads to loss of imprinting of Gsα and loss of expression of XLαs and XLN1. These mice have severe preweaning growth retardation and incomplete catch-up growth. They are fully viable probably because suckling is unimpaired, unlike mutants in which the expression of all the known paternally expressed Gnasxl proteins (XLαs, XLN1 and ALEX) is compromised. We suggest that loss of ALEX is most likely responsible for the suckling defects previously observed. In adults, paternal inheritance of Ex1A-T results in an increased metabolic rate and reductions in fat mass, leptin, and bone mineral density attributable to loss of XLαs. This is, to our knowledge, the first report describing a role for XLαs in bone metabolism. We propose that XLαs is involved in the regulation of bone and adipocyte metabolism

    Diagnostic Value of EBUS-TBNA for Lung Cancer with Non-Enlarged Lymph Nodes: A Study in a Tuberculosis-Endemic Country

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    BACKGROUND: In tuberculosis (TB)-endemic areas, contrast-enhanced computed tomography (CT) and positron emission tomography (PET) findings of lung cancer patients with non-enlarged lymph nodes are frequently discrepant. Endobronchial ultrasound-guided transbronchial aspiration (EBUS-TBNA) enables real-time nodal sampling, and thereby improves nodal diagnosis accuracy. This study aimed to compare the accuracy of nodal diagnosis by using EBUS-TBNA, and PET. METHODS: We studied 43 lung cancer patients with CT-defined non-enlarged mediastinal and hilar lymph nodes and examined 78 lymph nodes using EBUS-TBNA. RESULTS: The sensitivity, specificity, positive predictive value, and negative predictive value of EBUS-TBNA were 80.6%, 100%, 100%, and 85.7%, respectively. PET had low specificity (18.9%) and a low positive predictive value (44.4%). The diagnostic accuracy of EBUS-TBNA was higher than that of PET (91% vs. 47.4%; p<0.001). Compared to CT-based nodal assessment, PET yielded a positive diagnostic impact in 36.9% nodes, a negative diagnostic impact in 46.2% nodes, and no diagnostic impact in 16.9% nodes. Patients with lymph nodes showing negative PET diagnostic impact had a high incidence of previous pulmonary TB. Multivariate analysis indicated that detection of hilar nodes on PET was an independent predictor of negative diagnostic impact of PET. CONCLUSION: In a TB-endemic area with a condition of CT-defined non-enlarged lymph node, the negative diagnostic impact of PET limits its clinical usefulness for nodal staging; therefore, EBUS-TBNA, which facilitates direct diagnosis, is preferred

    Absence of association between SERPINE2 genetic polymorphisms and chronic obstructive pulmonary disease in Han Chinese: a case-control cohort study

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    <p>Abstract</p> <p>Background</p> <p>Recent studies have proposed that the serine protease inhibitor E2 (<it>SERPINE2</it>) was a novel susceptibility gene for chronic obstructive pulmonary disease (COPD) in Caucasians. However, this issue still remained controversial. Additional evidences from populations with different environments and/or genetic backgrounds, such as East Asian, would be helpful to elucidate the issue.</p> <p>Methods</p> <p>In this study, five proposed causal SNPs in <it>SERPINE2 </it>were genotyped in 327 COPD patients and 349 controls, all of which belonged to the Han population sampled from Southwest China. The frequency of each SNP was compared both individually and in combination between patients and controls. The potential relationship between these SNPs and severity of COPD was also investigated.</p> <p>Results</p> <p>Three SNPs (rs3795877, rs6747096, and rs3795879) showed complete linkage disequilibrium (r<sup>2 </sup>= 1), and the minor allele frequencies were 13.0% and 12.9% in case and control cohorts, respectively, with no significant difference observed (<it>P </it>= 0.96). We also failed to observe any significant correlation between these SNPs and COPD severity (<it>P </it>= 0.67). The other two SNPs (rs7579646 and rs840088) also presented a similar pattern. Moreover, four major haplotypes were observed in our sample but none showed a significant difference between case and control groups (<it>P </it>> 0.1).</p> <p>Conclusion</p> <p>Our results failed to obtain the evidence that these SNPs in <it>SERPINE2 </it>contributed to the COPD susceptibility in the Han Chinese population.</p

    Application of real-time global media monitoring and ‘derived questions’ for enhancing communication by regulatory bodies:the case of human papillomavirus vaccines

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    Abstract Background The benefit-risk balance of vaccines is regularly debated by the public, but the utility of media monitoring for regulatory bodies is unclear. A media monitoring study was conducted at the European Medicines Agency (EMA) concerning human papillomavirus (HPV) vaccines during a European Union (EU) referral procedure assessing the potential causality of complex regional pain syndrome (CRPS) and postural orthostatic tachycardia syndrome (POTS) reported to the authorities as suspected adverse reactions. Methods To evaluate the utility of media monitoring in real life, prospective real-time monitoring of worldwide online news was conducted from September to December 2015 with inductive content analysis, generating ‘derived questions’. The evaluation was performed through the validation of the predictive capacity of these questions against journalists’ queries, review of the EMA’s public statement and feedback from EU regulators. Results A total of 4230 news items were identified, containing personal stories, scientific and policy/process-related topics. Explicit and implicit concerns were identified, including those raised due to lack of knowledge or anticipated once more information would be published. Fifty derived questions were generated and categorised into 12 themes. The evaluation demonstrated that providing the media monitoring findings to assessors and communicators resulted in (1) confirming that public concerns regarding CRPS and POTS would be covered by the assessment; (2) meeting specific information needs proactively in the public statement; (3) predicting all queries from journalists; and (4) altering the tone of the public statement with respectful acknowledgement of the health status of patients with CRSP or POTS. Conclusions The study demonstrated the potential utility of media monitoring for regulatory bodies to support communication proactivity and preparedness, intended to support trusted safe and effective vaccine use. Derived questions seem to be a familiar and effective format for presenting media monitoring results in the scientific-regulatory environment. It is suggested that media monitoring could form part of regular surveillance for medicines of high public interest. Future work is recommended to develop efficient monitoring strategies for that purpose

    Application of real-time global media monitoring and ‘derived questions’ for enhancing communication by regulatory bodies:the case of human papillomavirus vaccines

    Get PDF
    Abstract Background The benefit-risk balance of vaccines is regularly debated by the public, but the utility of media monitoring for regulatory bodies is unclear. A media monitoring study was conducted at the European Medicines Agency (EMA) concerning human papillomavirus (HPV) vaccines during a European Union (EU) referral procedure assessing the potential causality of complex regional pain syndrome (CRPS) and postural orthostatic tachycardia syndrome (POTS) reported to the authorities as suspected adverse reactions. Methods To evaluate the utility of media monitoring in real life, prospective real-time monitoring of worldwide online news was conducted from September to December 2015 with inductive content analysis, generating ‘derived questions’. The evaluation was performed through the validation of the predictive capacity of these questions against journalists’ queries, review of the EMA’s public statement and feedback from EU regulators. Results A total of 4230 news items were identified, containing personal stories, scientific and policy/process-related topics. Explicit and implicit concerns were identified, including those raised due to lack of knowledge or anticipated once more information would be published. Fifty derived questions were generated and categorised into 12 themes. The evaluation demonstrated that providing the media monitoring findings to assessors and communicators resulted in (1) confirming that public concerns regarding CRPS and POTS would be covered by the assessment; (2) meeting specific information needs proactively in the public statement; (3) predicting all queries from journalists; and (4) altering the tone of the public statement with respectful acknowledgement of the health status of patients with CRSP or POTS. Conclusions The study demonstrated the potential utility of media monitoring for regulatory bodies to support communication proactivity and preparedness, intended to support trusted safe and effective vaccine use. Derived questions seem to be a familiar and effective format for presenting media monitoring results in the scientific-regulatory environment. It is suggested that media monitoring could form part of regular surveillance for medicines of high public interest. Future work is recommended to develop efficient monitoring strategies for that purpose
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