830 research outputs found

    Spectral weight function for the half-filled Hubbard model: a singular value decomposition approach

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    The singular value decomposition technique is used to reconstruct the electronic spectral weight function for a half-filled Hubbard model with on-site repulsion U=4tU=4t from Quantum Monte Carlo data. A two-band structure for the single-particle excitation spectrum is found to persist as the lattice size exceeds the spin-spin correlation length. The observed bands are flat in the vicinity of the (0,Ï€),(Ï€,0)(0,\pi),(\pi,0) points in the Brillouin zone, in accordance with experimental data for high-temperature superconducting compounds.Comment: 4 pages, Revtex

    Quantum Noise in Multipixel Image Processing

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    We consider the general problem of the quantum noise in a multipixel measurement of an optical image. We first give a precise criterium in order to characterize intrinsic single mode and multimode light. Then, using a transverse mode decomposition, for each type of possible linear combination of the pixels' outputs we give the exact expression of the detection mode, i.e. the mode carrying the noise. We give also the only way to reduce the noise in one or several simultaneous measurements.Comment: 8 pages and 1 figur

    Non Animal Methodologies (NAMs): research, testing, assessment and applications

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    The role of Academia to train new generation of scientists and future researchers on Non Animal Methodologies (NAMs) is crucial. Professor/student community from the Università degli Studi di Milano, Module Toxicology and in vitro models II year Master Degree, Veterinary Biotechnological Sciences Curriculum, worked together through a didactic integrated approach, in order to define Educational impact of NAMs

    Perineural invasion in vulvar squamous-cell carcinoma is an independent risk factor for cancer-specific survival, but not for locoregional recurrence: results from a single tertiary referral center

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    SIMPLE SUMMARY: Vulvar squamous cell carcinoma is a rare tumor but represents a serious health issue, especially due to the increasing incidence over the past decades. Many efforts have been made to identify new prognostic and therapeutic factors and, in this context, growing evidence concerning a pivotal role of perineural invasion. With this study, we investigated the role of perineural invasion in a large cohort of FIGO stage Ib-IIIc vulvar squamous cell carcinomas and found that perineural invasion-positive tumors have more aggressive biological behaviors and showed reduced cancer-specific survival as compared to perineural invasion-negative tumors, while this feature does not appear to be related to a greater risk to develop loco-regional recurrence. Further evaluations are warranted to confirm the prognostic role of perineural invasion and its potential use to tailor adjuvant treatment. ABSTRACT: The aims of this study were to assess the prevalence of perineural invasion (PNI) in vulvar squamous cell carcinoma (VSCC) and its prognostic role in locoregional recurrence (LRR) and cancer-specific survival (CSS). We performed a retrospective analysis of 223 consecutive stage IB–IIIC surgically treated VSCCs at S. Anna Hospital, University of Turin, from 2000 to 2019. We identified 133/223 (59.6%) patients with PNI-positive VSCCs. PNI was associated with aggressive biological features (i.e., advanced FIGO stage, larger tumor diameter, greater depth of invasion, a higher number of metastatic lymph nodes, and lymphovascular invasion) and shorter 5-year CSS (78% vs. 90%, log-rank p = 0.02) compared with PNI-negative VSCCs. Multivariate analysis showed that PNI (HR 2.99 CI 95% 1.17–7.63; p = 0.02) and the presence of tumor cells on pathological surgical margins (HR 3.13 CI 95% 1.37–7.13; p = 0.007) are independent prognostic factors for CSS. PNI does not appear to be related to LRR, but is an independent prognostic factor for worse survival outcomes. Future studies are necessary to explore the possible value of PNI in tailoring the choice of adjuvant treatment

    Convergence rates in expectation for Tikhonov-type regularization of Inverse Problems with Poisson data

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    In this paper we study a Tikhonov-type method for ill-posed nonlinear operator equations \gdag = F( ag) where \gdag is an integrable, non-negative function. We assume that data are drawn from a Poisson process with density t\gdag where t>0t>0 may be interpreted as an exposure time. Such problems occur in many photonic imaging applications including positron emission tomography, confocal fluorescence microscopy, astronomic observations, and phase retrieval problems in optics. Our approach uses a Kullback-Leibler-type data fidelity functional and allows for general convex penalty terms. We prove convergence rates of the expectation of the reconstruction error under a variational source condition as t→∞t\to\infty both for an a priori and for a Lepski{\u\i}-type parameter choice rule

    Structural Measurements for Enhanced MAV Flight

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    Our sense of touch allows us to feel the forces in our limbs when we walk, swim, or hold our arms out the window of a moving car. We anticipate this sense is key in the locomotion of natural flyers. Inspired by the sense of touch, the overall goal of this research is to develop techniques for the estimation of aerodynamic loads from structural measurements for flight control applications. We submit a general algorithm for the direct estimation of distributed steady loads over bodies from embedded noisy deformation-based measurements. The estimation algorithm is applied to a linearly elastic membrane test problem where three applied distributed loads are estimated using three measurement configurations with various amounts of noise. We demonstrate accurate load estimates with simple sensor configurations, despite noisy measurements. Online real-time aerodynamic load estimates may lead to flight control designs that improve the stability and agility of micro air vehicles

    Guindilia trinervis Gillies ex Hook. & Arn.

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