454 research outputs found

    Long term survival of mature autotransplanted teeth: A retrospective single center analysis

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    Objective: The replacement of an irremediably compromised tooth requires an implant rehabilitation or a traditional fixed partial denture. In well-selected cases, a further therapeutic possibility is represented by tooth autotransplantation. Although dental transplants are poorly understood and practiced, the international literature agrees that it is considered the first choice when applicable. The advantages of this technique are numerous: use of an autologous element, maintenance of tissue trophism, aesthetic and functional restoration, costs reduction. Although autotransplantation is often performed with immature teeth, even mature teeth with fully formed apex can be used as donors. The aim of the present work was to analyze consecutive cases of completely formed donor teeth autotransplantations performed from 2005 to 2011 in 21 patients for evaluating the survival and success rate. Materials and methods: The medical records of patients who underwent transplantation in a specialized center in Rimini (Italy) from 2005 to 2011 were checked. Only transplants of mature donor molars were considered. Patients were called up to evaluate the survival rate and success rate. Results: The mean age at the time of the surgery was 33,6 \ub1 7,4; mean follow up was 11,9 years \ub11,9. Success rate at the time of latest recall visit was 80 % and survival 95 % of the analyzed cases. Conclusions: The survival and success rate are in complete agreement with the most recent literature and confirm that the technique of autotransplantation is reliable when indications and protocols are rigidly followed, also using mature teeth as donors

    Natural risk management for industrial plants and infrastructures: the DaBo system

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    Natural risk management on complex critical infrastructures often requires integration of data coming out from a huge number of sensors. Solutions are sometimes derived by classical supervisory control and data acquisition systems (SCADAs), usually employed in manufacturing and industrial plants environment. This “control room” approach often proves to be ineffective when the system to be monitored goes beyond the limits of the single plant and it is extended to the surrounding environment including buildings and public infrastructures in a strong interaction with local communities. The paper presents the case study of a hydroelectric plant extended over a territory of a few tens of square kilometers and subject to hydrogeological problems of various kinds, with interactions with buildings and infrastructures. The huge number of sensors installed for production control proved to be far to monitor the safety of the plant in its environmental context. We present here the risk assessment procedure and the proposed actions, also in terms of sensor installation. DaBo platform work as a data integrator. The structural and hydraulic “ordinary state” is continuously generated by means of numerical modeling basing upon real time observed boundary conditions. This state, via a suitable set of state variables, is compared with sensor data allowing a clear synthesis of the safety of the infrastructure and its natural and anthropic context. DaBo poses itself as a systems integrator both from a conceptual and an operational point of view, able to activate direct measures to reduce the risk in case of emergency, involving also local civil protection authorities. The platform integrates information from a wide range of sensors (viz. temperature, water level, strain, water content), weather alerts, weather forecast from high resolution limited area models. The main innovation of DaBo consists in the dashboard designed to provide communication of risk to the end user and to link the warnings to action procedures. It is technically a responsive single page web application that is based on an information storage and management layer by a high capacity relational database, a powerful scalable business logic tier for decision support and early warning system, and a multi profiled responsive user interface. The goal is to ensure the operation of the entire supply chain that connects the various sources of information to the entire user range

    Effect of an electric field on an intermittent granular flow

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    Granular gravity driven flows of glass beads have been observed in a silo with a flat bottom. A DC high electric field has been applied perpendicularly to the silo to tune the cohesion. The outlet mass flow has been measured. An image subtraction technique has been applied to visualize the flow geometry and a spatiotemporal analysis of the flow dynamics has been performed. The outlet mass flow is independent of voltage, but a transition from funnel flow to rathole flow is observed. This transition is of probabilistic nature and an intermediate situation exists between the funnel and the rathole situations. At a given voltage, two kinds of flow dynamics can occur : a continuous flow or an intermittent flow. The electric field increases the probability to observe an intermittent flow.Comment: Accepted for publication in PRE on Apr 9, 201

    Dirac dispersion and non-trivial Berry's phase in three-dimensional semimetal RhSb3

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    We report observations of magnetoresistance, quantum oscillations and angle-resolved photoemission in RhSb3_3, a unfilled skutterudite semimetal with low carrier density. The calculated electronic band structure of RhSb3_3 entails a Z2Z_2 quantum number ν0=0,ν1=ν2=ν3=1\nu_0=0,\nu_1=\nu_2=\nu_3=1 in analogy to strong topological insulators, and inverted linear valence/conduction bands that touch at discrete points close to the Fermi level, in agreement with angle-resolved photoemission results. Transport experiments reveal an unsaturated linear magnetoresistance that approaches a factor of 200 at 60 T magnetic fields, and quantum oscillations observable up to 150~K that are consistent with a large Fermi velocity (1.3×106\sim 1.3\times 10^6 ms1^{-1}), high carrier mobility (14\sim 14 m2m^2/Vs), and small three dimensional hole pockets with nontrivial Berry phase. A very small, sample-dependent effective mass that falls as low as 0.015(7)0.015(7) bare masses scales with Fermi velocity, suggesting RhSb3_3 is a new class of zero-gap three-dimensional Dirac semimetal.Comment: 9 pages, 4 figure

    Coherent ultrafast spin-dynamics probed in three dimensional topological insulators

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    Topological insulators are candidates to open up a novel route in spin based electronics. Different to traditional ferromagnetic materials, where the carrier spin-polarization and magnetization are based on the exchange interaction, the spin properties in topological insulators are based on the coupling of spin- and orbit interaction connected to its momentum. Specific ways to control the spin-polarization with light have been demonstrated: the energy momentum landscape of the Dirac cone provides spin-momentum locking of the charge current and its spin. The directionality of spin and momentum, as well as control with light has been demonstrated. Here we demonstrate a coherent femtosecond control of spin-polarization for states in the valence band at around the Dirac cone.Comment: 14 pages, 4 figure

    Influence of Spin Orbit Coupling in the Iron-Based Superconductors

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    We report on the influence of spin-orbit coupling (SOC) in the Fe-based superconductors (FeSCs) via application of circularly-polarized spin and angle-resolved photoemission spectroscopy. We combine this technique in representative members of both the Fe-pnictides and Fe-chalcogenides with ab initio density functional theory and tight-binding calculations to establish an ubiquitous modification of the electronic structure in these materials imbued by SOC. The influence of SOC is found to be concentrated on the hole pockets where the superconducting gap is generally found to be largest. This result contests descriptions of superconductivity in these materials in terms of pure spin-singlet eigenstates, raising questions regarding the possible pairing mechanisms and role of SOC therein.Comment: For supplementary information, see http://qmlab.ubc.ca/ARPES/PUBLICATIONS/articles.htm

    Doping dependent charge order correlations in electron-doped cuprates

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    Understanding the interplay between charge order (CO) and other phenomena (e.g. pseudogap, antiferromagnetism, and superconductivity) is one of the central questions in the cuprate high-temperature superconductors. The discovery that similar forms of CO exist in both hole- and electron-doped cuprates opened a path to determine what subset of the CO phenomenology is universal to all the cuprates. Here, we use resonant x-ray scattering to measure the charge order correlations in electron-doped cuprates (La2-xCexCuO4 and Nd2-xCexCuO4) and their relationship to antiferromagnetism, pseudogap, and superconductivity. Detailed measurements of Nd2-xCexCuO4 show that CO is present in the x = 0.059 to 0.166 range, and that its doping dependent wavevector is consistent with the separation between straight segments of the Fermi surface. The CO onset temperature is highest between x = 0.106 and 0.166, but decreases at lower doping levels, indicating that it is not tied to the appearance of antiferromagnetic correlations or the pseudogap. Near optimal doping, where the CO wavevector is also consistent with a previously observed phonon anomaly, measurements of the CO below and above the superconducting transition temperature, or in a magnetic field, show that the CO is insensitive to superconductivity. Overall these findings indicate that, while verified in the electron-doped cuprates, material-dependent details determine whether the CO correlations acquire sufficient strength to compete for the ground state of the cuprates.Comment: Supplementary information available upon reques

    Emergence of pseudogap from short-range spin-correlations in electron doped cuprates

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    Electron interactions are pivotal for defining the electronic structure of quantum materials. In particular, the strong electron Coulomb repulsion is considered the keystone for describing the emergence of exotic and/or ordered phases of quantum matter as disparate as high-temperature superconductivity and charge- or magnetic-order. However, a comprehensive understanding of fundamental electronic properties of quantum materials is often complicated by the appearance of an enigmatic partial suppression of low-energy electronic states, known as the pseudogap. Here we take advantage of ultrafast angle-resolved photoemission spectroscopy to unveil the temperature evolution of the low-energy density of states in the electron-doped cuprate Nd2-x_{\text{2-x}}Cex_{\text{x}}CuO4_{\text{4}}, an emblematic system where the pseudogap intertwines with magnetic degrees of freedom. By photoexciting the electronic system across the pseudogap onset temperature T*, we report the direct relation between the momentum-resolved pseudogap spectral features and the spin-correlation length with an unprecedented sensitivity. This transient approach, corroborated by mean field model calculations, allows us to establish the pseudogap in electron-doped cuprates as a precursor to the incipient antiferromagnetic order even when long-range antiferromagnetic correlations are not established, as in the case of optimal doping.Comment: 17 pages, 3 figure

    Collapse of superconductivity in cuprates via ultrafast quenching of phase coherence

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    The possibility of driving phase transitions in low-density condensates through the loss of phase coherence alone has far-reaching implications for the study of quantum phases of matter. This has inspired the development of tools to control and explore the collective properties of condensate phases via phase fluctuations. Electrically-gated oxide interfaces, ultracold Fermi atoms, and cuprate superconductors, which are characterized by an intrinsically small phase-stiffness, are paradigmatic examples where these tools are having a dramatic impact. Here we use light pulses shorter than the internal thermalization time to drive and probe the phase fragility of the Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} cuprate superconductor, completely melting the superconducting condensate without affecting the pairing strength. The resulting ultrafast dynamics of phase fluctuations and charge excitations are captured and disentangled by time-resolved photoemission spectroscopy. This work demonstrates the dominant role of phase coherence in the superconductor-to-normal state phase transition and offers a benchmark for non-equilibrium spectroscopic investigations of the cuprate phase diagram.Comment: 24 pages, 9 figures, Main Text and Supplementary Informatio
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