808 research outputs found

    Endoscopy-assisted removal through combined lower and middle meatotomies of an ectopic upper third molar in the sinus associated with a dentigerous cyst

    Get PDF
    The aim of this case report is to present an original conservative technique for the transnasal endoscopy-assisted extraction of an ectopic upper third molar associated with a dentigerous cyst occupying the whole maxillary sinus by means of combined lower and middle meatotomies. The proposed technique is a viable, minimally-invasive alternative to the Caldwell–Luc operation (with or without the repositioning of a bone lid), and also to endoscopic middle meatal antrostomy in cases where this would be unable to ensure adequate access because of the position and size of the ectopic tooth and associated cyst

    Critical generalized inverse participation ratio distributions

    Full text link
    The system size dependence of the fluctuations in generalized inverse participation ratios (IPR's) Iα(q)I_{\alpha}(q) at criticality is investigated numerically. The variances of the IPR logarithms are found to be scale-invariant at the macroscopic limit. The finite size corrections to the variances decay algebraically with nontrivial exponents, which depend on the Hamiltonian symmetry and the dimensionality. The large-qq dependence of the asymptotic values of the variances behaves as q2q^2 according to theoretical estimates. These results ensure the self-averaging of the corresponding generalized dimensions.Comment: RevTex4, 5 pages, 4 .eps figures, to be published in Phys. Rev.

    Genetic variability among Blastoschizomyces capitatus isolates from different clinical sources.

    Get PDF
    Sixteen clinical isolates and nine ATCC reference strains of Blastoschizomyces capitatus were analysed genetically, examined for the cellobiose, arbutin and salicin assimilation and tested for the aspartyl-proteinase secretion. The restriction endonuclease analysis (REA) with HpaII and HinfI enzymes and the electrophoretic karyotype (EK) were investigated. Both the restriction enzymes revealed two groups (I, II) constituted by the same isolates: 17 isolates (68%) in group I and 8 (32%) in group II. The EK analysis revealed sixteen groups. These data prompts for a genetic variability of the isolates of Blastoschizomyces capitatus and their account in two distinct genetic groups as suggested by REA. This grouping was confirmed by examing the utilisation of cellobiose, arbutin and salicin. The tests for secretory aspartyl proteinase (Sap) were positive only for three isolates, suggesting a marginal role of this specific enzyme in pathogenesis for these isolates

    Electro-thermal dynamic simulations and results of a deorbiting tethered system

    Get PDF
    Deorbiting techniques with small or better no propellant consumption are an important and critical field of space studies for the mitigation of orbital debris. Electrodynamic tethers (EDTs) are of particular interest because they make possible to deorbit space debris by exploiting the Lorentz force that is provided by the current flowing in the tether thanks to the interaction of the system with the Earth’s magnetosphere and the ionosphere. This paper focuses on the differences between two software packages built at the University of Padova (FLEX and FLEXSIM) and their results in simulating various deorbiting scenarios. Both FLEXSIM and FLEX simulate the electro-thermal behaviour and the dynamics of an EDT. However, while the first one has the simplifying assumption that the tether is always aligned with the local vertical, the second one considers also the overall system attitude with respect to the radial direction and the tether flexibility. The computational times of these S/W are very different and it is important to understand the scenarios that are more appropriate for their use. Results aim to show the impact of different solar activity (simulations are done at different epochs) and lengths of conductive and non conductive segments of tether, in the range of a few hundreds of meters, on the total re-entry time. As expected, deorbiting is faster for high solar activity and conductive tether length but the performance must be balanced against the dynamics stability. The issue of stability over the deorbiting time is evaluated numerically for specific cases by using FLEX

    Deployment profile analysis for tethered deorbiting technologies

    Get PDF
    Over the past few decades, the man-made space debris has become an increasingly concerning problem for future space missions. Fortunately, some innovative "green" deorbiting technologies have been emerged. Among these strategies, electrodynamic tethers have demonstrated to be a promising option, thanks to their passive and fuel-free characteristics. By leveraging the Earth's ionosphere and the geomagnetic field, an electrodynamic tether generates a Lorentz drag force, that can significantly reduce the altitude of a satellite and ultimately cause it to re-enter the atmosphere. The goal of this research is to investigate a critical part of satellite tethered technology, namely the deployment phase. To accomplish this, we utilized a software tool developed by the University of Padova to simulate the dynamics of the deployment phase and optimize its trajectory, in order to meet the desired boundary conditions. This paper gives a description of the software and shows the results of a sensitivity analysis on the trajectory profile that examines the impact of variations in the release angle of the tether and the speed profile actuated by the motor that controls the deployment speed

    Stochastic ionization through noble tori: Renormalization results

    Full text link
    We find that chaos in the stochastic ionization problem develops through the break-up of a sequence of noble tori. In addition to being very accurate, our method of choice, the renormalization map, is ideally suited for analyzing properties at criticality. Our computations of chaos thresholds agree closely with the widely used empirical Chirikov criterion

    Deployment requirements for deorbiting electrodynamic tether technology

    Get PDF
    In the last decades, green deorbiting technologies have begun to be investigated and have raised a great interest in the space community. Among the others, electrodynamic tethers appear to be a promising option. By interacting with the surrounding ionosphere, electrodynamic tethers generate a drag Lorentz force to decrease the orbit altitude of the satellite, causing its re-entry in the atmosphere without using propellant. In this work, the requirements that drive the design of the deployment mechanism proposed for the H2020 Project E.T.PACK\u2014Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit\u2014are presented and discussed. Additionally, this work presents the synthesis of the reference profiles used by the motor of the deployer to make the tethered system reach the desired final conditions. The result is a strategy for deploying electrodynamic tape-shaped tethers used for deorbiting satellites at the end of their operational life

    Coherent Tunneling of Atoms from Bose-condensed Gases at Finite Temperatures

    Full text link
    Tunneling of atoms between two trapped Bose-condensed gases at finite temperatures is explored using a many-body linear response tunneling formalism similar to that used in superconductors. To lowest order, the tunneling currents can be expressed quite generally in terms of the single-particle Green's functions of the isolated Bose gases. A coherent first-order tunneling Josephson current between two atomic Bose-condensates is found, in addition to coherent and dissipative contributions from second-order condensate-noncondensate and noncondensate-noncondensate tunneling. Our work is a generalization of Meier and Zwerger, who recently treated tunneling between uniform atomic Bose gases. We apply our formalism to the analysis of an out-coupling experiment induced by light wave fields, using a simple Bogoliubov-Popov quasiparticle approximation for the trapped Bose gas. For tunneling into the vacuum, we recover the results of Japha, Choi, Burnett and Band, who recently pointed out the usefulness of studying the spectrum of out-coupled atoms. In particular, we show that the small tunneling current of noncondensate atoms from a trapped Bose gas has a broad spectrum of energies, with a characteristic structure associated with the Bogoliubov quasiparticle u^2 and v^2 amplitudes.Comment: 26 pages, 5 figures, minor changes, to appear in PR
    • …
    corecore