435 research outputs found

    Should we perform multiparametric magnetic resonance imaging of the bladder before transurethral resection of bladder? Time to reconsider the rules

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    We would like to congratulate Ueno and colleagues [1] on their paper on diagnostic accuracy and interobserver agreement for the new Vesical Imaging-Reporting and Data System (VI-RADS) [2] for muscle-invasive bladder cancer (MIBC) in this issue of European Urology. Their report on 74 patients who underwent multiparametric magnetic resonance imaging (mpMRI) before transurethral resection of bladder tumor (TURBT) raises great interest in the RADS (Reporting and Data Systems) era. They address the questions of reproducibility and diagnostic performance of mpMRI in the setting of bladder ca (BC), in which potential applications of this imaging technique have seen constant growth in the past decades without a definitive role having been identified

    Enhanced binding revisited for a spinless particle in non-relativistic QED

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    We consider a spinless particle coupled to a quantized Bose field and show that such a system has a ground state for two classes of short-range potentials which are alone too weak to have a zero-energy resonance

    Binding threshold for the Pauli-Fierz operator

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    For the Pauli-Fierz operator with a short range potential we study the binding threshold as a function of the fine structure constant α\alpha and show that it converges to the binding threshold for the Schr\"odinger operator in the small α\alpha limit

    S-ICD is effective in preventing sudden death in Arrhythmogenic Cardiomyopathy athletes during exercise

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    Here we describe the cases of two elite athletes, with a diagnosis of Arrhythmogenic Cardiomyopathy (ACM), in which a Subcutaneous Implantable Cardioverter Defibrillator (S-ICD) has been implanted. Both patients experienced a ventricular tachycardia during exercise and received effective S-ICD shocks that interrupted arrhythmias. This report reveals for the first time that the S-ICD is effective in reverting arrhythmias in ACM patients, even during exercise. Moreover, these cases may confirm that competition/physical activity is associated with ICD shocks

    Ground States in the Spin Boson Model

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    We prove that the Hamiltonian of the model describing a spin which is linearly coupled to a field of relativistic and massless bosons, also known as the spin-boson model, admits a ground state for small values of the coupling constant lambda. We show that the ground state energy is an analytic function of lambda and that the corresponding ground state can also be chosen to be an analytic function of lambda. No infrared regularization is imposed. Our proof is based on a modified version of the BFS operator theoretic renormalization analysis. Moreover, using a positivity argument we prove that the ground state of the spin-boson model is unique. We show that the expansion coefficients of the ground state and the ground state energy can be calculated using regular analytic perturbation theory

    Ground State and Resonances in the Standard Model of Non-relativistic QED

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    We prove existence of a ground state and resonances in the standard model of the non-relativistic quantum electro-dynamics (QED). To this end we introduce a new canonical transformation of QED Hamiltonians and use the spectral renormalization group technique with a new choice of Banach spaces.Comment: 50 pages change

    Modelling double skin façades (DSFs) in whole-building energy simulation tools: Validation and inter-software comparison of a mechanically ventilated single-story DSF

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    Double skin façades (DSFs) have been proposed as responsive building systems to improve the building envelope's performance. Reliable simulation of DSF performance is a prerequisite to support the design and implementation of these systems in real buildings. Building energy simulation (BES) tools are commonly used by practitioners to predict the whole building energy performance, but the simulation of the thermophysical behaviour of DSFs may be challenging when carried out through BES tools. Using an exhaust-air façade case study, we analyse and assess the reliability of four popular BES tools when these are used to simulate a DSF, either through available in-built models or through custom-built representations based on zonal models. We carry out this study by comparing numerical simulations and experimental data for a series of significant thermophysical quantities, and we reflect on the performance and limitations of the different tools. The results show that no tool is outstandingly better performing over the others, but some tools offer better predictions when the focus is placed on certain thermophysical quantities, while others should be chosen if the focus is on different ones. After comparing the different models’ limitations and challenges, we conclude that BES tools can simulate the performance of DSF systems over long periods. However, their use alone is not recommended when the simulation's scope is to replicate and study short-term phenomena and dynamic aspects, such as sizing the building's HVAC system

    A new approach to the modelling of local defects in crystals: the reduced Hartree-Fock case

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    This article is concerned with the derivation and the mathematical study of a new mean-field model for the description of interacting electrons in crystals with local defects. We work with a reduced Hartree-Fock model, obtained from the usual Hartree-Fock model by neglecting the exchange term. First, we recall the definition of the self-consistent Fermi sea of the perfect crystal, which is obtained as a minimizer of some periodic problem, as was shown by Catto, Le Bris and Lions. We also prove some of its properties which were not mentioned before. Then, we define and study in details a nonlinear model for the electrons of the crystal in the presence of a defect. We use formal analogies between the Fermi sea of a perturbed crystal and the Dirac sea in Quantum Electrodynamics in the presence of an external electrostatic field. The latter was recently studied by Hainzl, Lewin, S\'er\'e and Solovej, based on ideas from Chaix and Iracane. This enables us to define the ground state of the self-consistent Fermi sea in the presence of a defect. We end the paper by proving that our model is in fact the thermodynamic limit of the so-called supercell model, widely used in numerical simulations.Comment: Final version, to appear in Comm. Math. Phy
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