3,423 research outputs found

    Uncovering the mechanism of the impurity-selective Mott transition in paramagnetic V2_{2}O3_{3}

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    While the phase diagrams of the one- and multi-orbital Hubbard model have been well studied, the physics of real Mott insulators is often much richer, material dependent, and poorly understood. In the prototype Mott insulator V2_{2}O3_{3}, chemical pressure was initially believed to explain why the paramagnetic-metal to antiferromagnetic-insulator transition temperature is lowered by Ti doping while Cr doping strengthens correlations, eventually rendering the high-temperature phase paramagnetic insulating. However, this scenario has been recently shown both experimentally and theoretically to be untenable. Based on full structural optimization, we demonstrate via the charge self-consistent combination of density functional theory and dynamical mean-field theory that changes in the V2_{2}O3_{3} phase diagram are driven by defect-induced local symmetry breakings resulting from dramatically different couplings of Cr and Ti dopants to the host system. This finding emphasizes the high sensitivity of the Mott metal-insulator transition to the local environment and the importance of accurately accounting for the one-electron Hamiltonian, since correlations crucially respond to it.Comment: 5 pages, 5 figures, supplementary informatio

    An engineered cardiac reporter cell line identifies human embryonic stem cell-derived myocardial precursors.

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    Unlike some organs, the heart is unable to repair itself after injury. Human embryonic stem cells (hESCs) grow and divide indefinitely while maintaining the potential to develop into many tissues of the body. As such, they provide an unprecedented opportunity to treat human diseases characterized by tissue loss. We have identified early myocardial precursors derived from hESCs (hMPs) using an α-myosin heavy chain (αMHC)-GFP reporter line. We have demonstrated by immunocytochemistry and quantitative real-time PCR (qPCR) that reporter activation is restricted to hESC-derived cardiomyocytes (CMs) differentiated in vitro, and that hMPs give rise exclusively to muscle in an in vivo teratoma formation assay. We also demonstrate that the reporter does not interfere with hESC genomic stability. Importantly, we show that hMPs give rise to atrial, ventricular and specialized conduction CM subtypes by qPCR and microelectrode array analysis. Expression profiling of hMPs over the course of differentiation implicate Wnt and transforming growth factor-β signaling pathways in CM development. The identification of hMPs using this αMHC-GFP reporter line will provide important insight into the pathways regulating human myocardial development, and may provide a novel therapeutic reagent for the treatment of cardiac disease

    The FIR-absorption of short period quantum wires and the transition from one to two dimensions

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    We investigate the FIR-absorption of short period parallel quantum wires in a perpendicular quantizing magnetic field. The external time-dependent electric field is linearly polarized along the wire modulation. The mutual Coulomb interaction of the electrons is treated self-consistently in the ground state and in the absorption calculation within the Hartree approximation. We consider the effects of a metal gate grating coupler, with the same or with a different period as the wire modulation, on the absorption. The evolution of the magnetoplasmon in the nonlocal region where it is split into several Bernstein modes is discussed in the transition from: narrow to broad wires, and isolated to overlapping wires. We show that in the case of narrow and not strongly modulated wires the absorption can be directly correlated with the underlying electronic bandstructure.Comment: 15 pages, 9 figures, Revtex, to appear in Phys. Rev.

    Development Thinking as Cultural Neo?Colonialism—the Case of Sri Lanka

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    Summary The independence struggle in Sri Lanka gave rise to various counter?ideologies challenging the imposed ideologies of the colonialists. During the post?independence period it seemed that the counter?ideologies had come into their own and were beginning to be put into effect. Yet from the 1950s a new imposed ideology, arising from Western definitions of the problems of'development', began increasingly to be adopted in centres of official decision?making, and the counter?ideologies which arose from actual political debate in the country began to recede. This paper describes the sociological mechanisms by which this imposed structure of knowledge is maintained, the air of unreality surrounding it, and the stultifying effects it has on discussions of the real issues, of what development is about. RESUME Théories sur le développement en tant que néo?colonialisme culturel—lecasdeSri Lanka La lutte pour I'indépendance à Sri Lanka fit naître diverses idéologies mettant en question celles des colonialistes. Pendant la période qui a suivi I'indépendance il a semblé que ces idéologies occupaient le terrain et commençaient à être concrétisées. Cependant, à partlr des années '50 s'est imposée une nouvelle idéologie dérivée des définitions occidentales de développement, progressivement adoptée par les organismes de décision officiels; et les idéologies nées du débat politique au sein du pays ont subi un recul. Cette étude décrit les mécanismes sociologiques par lesquels se maintient cette structure imposée de connaissances, I'atmosphère irréelle qui I'entoure, et ses effets répressifs sur la discussion des vrais thèmes du développement. RESUMEN La ideología del desarrollo como neocolonialismo cultural—El casodeSri Lanka Susantha Goonatilake La lucha la independent en Sri Lanka dio origan a varias contraideologías que se oponían a las ideologías impuestas por los colonialistas. Durante el período que siguió a la independencia pareció que las contra?ideologías se habían consolidado estaban empezando a ser puestas en práctice. Sin embargo desde la déceda de 1950 una nueva Ideología externa, emanada de las definiciones occidentales de los problemas del ‘desarrollo’, empezó a ser adoptada en forma creciente en los centros de decisión oficial, las contra?ideologías que surgieron del debate político real en el país empezaron a perder terreno. Este artlculo describe los mecanismos sociológicos que hacen posible la mantención de esta estructura de conocimiento impuesta, el aire de irrealidad que ía rodea, losefectos esterilizadores que tiene en las discusiones de los problemas reales, de la verdadera problemática del desarrollo

    Identification of women with an increased risk of developing radiation-induced breast cancer

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    In the previous issue of Breast Cancer Research, Broeks and collaborators present the results of a study suggesting that germline mutations in BRCA1, BRCA2, ATM or CHEK2 may double the risk of radiation-induced contralateral breast cancer following radiotherapy for a first breast cancer. The assocation appeared to be strongest among women who were below the age of 40 at the time of their first breast cancer and among women who developed their second cancer 5 years or more after the first. While there were a number of methodological issues that might limit the conclusions drawn from this paper, this is one of several recent studies suggesting that carriers of pathogenic alleles in DNA repair and damage recognition genes may have an increased risk of breast cancer following exposure to ionising radiation, even at low doses. This finding has important implications for the protection of breast cancer patients and their close relatives. If confirmed, mutation carriers may wish to consider alternatives to X-ray for diagnostic purposes. The need for tailored cancer treatment strategies in carriers should also be evaluated carefully

    Idarucizumab for Dabigatran Reversal - Full Cohort Analysis.

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    BACKGROUND: Idarucizumab, a monoclonal antibody fragment, was developed to reverse the anticoagulant effect of dabigatran. METHODS: We performed a multicenter, prospective, open-label study to determine whether 5 g of intravenous idarucizumab would be able to reverse the anticoagulant effect of dabigatran in patients who had uncontrolled bleeding (group A) or were about to undergo an urgent procedure (group B). The primary end point was the maximum percentage reversal of the anticoagulant effect of dabigatran within 4 hours after the administration of idarucizumab, on the basis of the diluted thrombin time or ecarin clotting time. Secondary end points included the restoration of hemostasis and safety measures. RESULTS: A total of 503 patients were enrolled: 301 in group A, and 202 in group B. The median maximum percentage reversal of dabigatran was 100% (95% confidence interval, 100 to 100), on the basis of either the diluted thrombin time or the ecarin clotting time. In group A, 137 patients (45.5%) presented with gastrointestinal bleeding and 98 (32.6%) presented with intracranial hemorrhage; among the patients who could be assessed, the median time to the cessation of bleeding was 2.5 hours. In group B, the median time to the initiation of the intended procedure was 1.6 hours; periprocedural hemostasis was assessed as normal in 93.4% of the patients, mildly abnormal in 5.1%, and moderately abnormal in 1.5%. At 90 days, thrombotic events had occurred in 6.3% of the patients in group A and in 7.4% in group B, and the mortality rate was 18.8% and 18.9%, respectively. There were no serious adverse safety signals. CONCLUSIONS: In emergency situations, idarucizumab rapidly, durably, and safely reversed the anticoagulant effect of dabigatran. (Funded by Boehringer Ingelheim; RE-VERSE AD ClinicalTrials.gov number, NCT02104947 .)

    137,138,139^{137,138,139}La(nn, γ\gamma) cross sections constrained with statistical decay properties of 138,139,140^{138,139,140}La nuclei

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    The nuclear level densities and γ\gamma-ray strength functions of 138,139,140^{138,139,140}La were measured using the 139^{139}La(3^{3}He, α\alpha), 139^{139}La(3^{3}He, 3^{3}He′^\prime) and 139^{139}La(d, p) reactions. The particle-γ\gamma coincidences were recorded with the silicon particle telescope (SiRi) and NaI(Tl) (CACTUS) arrays. In the context of these experimental results, the low-energy enhancement in the A∼\sim140 region is discussed. The 137,138,139^{137,138,139}La(n,γ)n, \gamma) cross sections were calculated at ss- and pp-process temperatures using the experimentally measured nuclear level densities and γ\gamma-ray strength functions. Good agreement is found between 139^{139}La(n,γ)n, \gamma) calculated cross sections and previous measurements

    SmartOTPs: An Air-Gapped 2-Factor Authentication for Smart-Contract Wallets

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    With the recent rise of cryptocurrencies' popularity, the security and management of crypto-tokens have become critical. We have witnessed many attacks on users and providers, which have resulted in significant financial losses. To remedy these issues, several wallet solutions have been proposed. However, these solutions often lack either essential security features, usability, or do not allow users to customize their spending rules. In this paper, we propose SmartOTPs, a smart-contract wallet framework that gives a flexible, usable, and secure way of managing crypto-tokens in a self-sovereign fashion. The proposed framework consists of four components (i.e., an authenticator, a client, a hardware wallet, and a smart contract), and it provides 2-factor authentication (2FA) performed in two stages of interaction with the blockchain. To the best of our knowledge, our framework is the first one that utilizes one-time passwords (OTPs) in the setting of the public blockchain. In SmartOTPs, the OTPs are aggregated by a Merkle tree and hash chains whereby for each authentication only a short OTP (e.g., 16B-long) is transferred from the authenticator to the client. Such a novel setting enables us to make a fully air-gapped authenticator by utilizing small QR codes or a few mnemonic words, while additionally offering resilience against quantum cryptanalysis. We have made a proof-of-concept based on the Ethereum platform. Our cost analysis shows that the average cost of a transfer operation is comparable to existing 2FA solutions using smart contracts with multi-signatures
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