2,559 research outputs found

    Improved time-decay for a class of scaling critical electromagnetic Schr\"odinger flows

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    We consider a Schr\"odinger hamiltonian H(A,a)H(A,a) with scaling critical and time independent external electromagnetic potential, and assume that the angular operator LL associated to HH is positive definite. We prove the following: if ∥e−itH(A,a)∥L1→L∞≲t−n/2\|e^{-itH(A,a)}\|_{L^1\to L^\infty}\lesssim t^{-n/2}, then ∥∣x∣−g(n)e−itH(A,a)∣x∣−g(n)∥L1→L∞≲t−n/2−g(n) \||x|^{-g(n)}e^{-itH(A,a)}|x|^{-g(n)}\|_{L^1\to L^\infty}\lesssim t^{-n/2-g(n)}, g(n)g(n) being a positive number, explicitly depending on the ground level of LL and the space dimension nn. We prove similar results also for the heat semi-group generated by H(A,a)H(A,a)

    Improved time-decay for a class of scaling critical electromagnetic Schrödinger flows

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    We consider a Schr\"odinger hamiltonian HH with scaling critical and time independent external electromagnetic potential, and assume that the angular operator LL associated to HH is positively definite. We prove the following: if ∥e−itH∥L1→L∞≤Ct−n/2\|e^{-itH}\|_{L^1\to L^\infty}\leq Ct^{-n/2}, then ∥∣x∣−g(n)e−itH∣x∣−g(n)∥L1→L∞≤Ct−n/2−g(n) \||x|^{-g(n)}e^{-itH}|x|^{-g(n)}\|_{L^1\to L^\infty}\leq Ct^{-n/2-g(n)}, being g(n)g(n) a positive number, explicitly depending on the ground level of LL and the space dimension nn

    Influence of size, shape and core\u2013shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiOx

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    Ag and Ag@MgO core-shell nanoparticles (NPs) with a diameter of d = 3-10 nm were obtained by physical synthesis methods and deposited on Si with its native ultrathin oxide layer SiOx (Si/SiOx). Scanning electron microscopy and transmission electron microscopy (TEM) images of bare Ag NPs revealed the presence of small NP aggregates caused by diffusion on the surface and agglomeration. Atomic resolution TEM gave evidence of the presence of crystalline multidomains in the NPs, which were due to aggregation and multitwinning occurring during NP growth in the nanocluster source. Co-deposition of Ag NPs and Mg atoms in an oxygen atmosphere gave rise to formation of a MgO shell matrix surrounding the Ag NPs. The behaviour of the surface plasmon resonance (SPR) excitation in surface differential reflectivity (SDR) spectra with p-polarised light was investigated for bare Ag and Ag@MgO NPs. It was shown that the presence of MgO around the Ag NPs caused a red shift of the plasmon excitation, and served preserve its existence after prolonged (five months) exposure to air, realizing the possibility of technological applications in plasmonic devices. The Ag NP and Ag@MgO NP film features in the SDR spectra could be reproduced by classical electrodynamics simulations by treating the NP-containing layer as an effective Maxwell Garnett medium. The simulations gave results in agreement with the experiments when accounting for the experimentally observed aggregation

    Pathologist's approach to paediatric and neonatal eosinophilic gastrointestinal disorders

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    Children are not simply miniature adults. The evaluation of their gastrointestinal disorders is therefore different from that in full-grown adults and requires a particular clinical/pathologic approach. : Different studies have tried to assess the normal eosinophil distribution in the gastrointestinal tract in adults while very few studies have investigated the paediatric population, consequently complicating the pathologist's ability in identifying an abnormal number of eosinophils in this setting of patients. : When evaluating gastrointestinal tract biopsies with eosinophilia, eosinophilic count must be considered along with other histological features like eosinophil distribution in the gastrointestinal wall, their degranulation, cryptitis and crypt abscesses, other accompanying inflammatory cells, apoptotic bodies, foreign material or microorganisms; these findings, although rarely specific, may be a useful aid for diagnosis. : Reports should not include a diagnosis of primary eosinophilic gastrointestinal disorders (EoGID) if clinical data and test results do not rule out other forms of gastrointestinal eosinophilia. A more descriptive definition like "with eosinophilic pattern" should be favoured over a specific diagnosis of "eosinophilic disorder" in order to avoid potential confusion between different entities

    Field emission from two-dimensional GeAs

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    GeAs is a layered material of the IV-V groups that is attracting growing attention for possible applications in electronic and optoelectronic devices. In this study, exfoliated multilayer GeAs nanoflakes are structurally characterized and used as the channel of back-gate field-effect transistors. It is shown that their gate-modulated p-type conduction is decreased by exposure to light or electron beam. Moreover, the observation of a field emission current demonstrates the suitability of GeAs nanoflakes as cold cathodes for electron emission and opens up new perspective applications of two-dimensional GeAs in vacuum electronics. Field emission occurs with a turn-on field of ~80 V/{\mu}m and attains a current density higher than 10 A/cm^2, following the general Fowler-Nordheim model with high reproducibility.Comment: 10 pages, 3 figure

    Not only a small liver - The pathologist's perspective in the pediatric liver transplant setting

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    open8Pediatric liver transplantation represents a safe and long-lasting treatment option for various disease types, requiring the pathologist's input. Indeed, an accurate and timely diagnosis is crucial in reporting and grading native liver diseases, evaluating donor liver eligibility and identifying signs of organ injury in the post-transplant follow-up. However, as the procedure is more frequently and widely performed, deceptive and unexplored histopathologic features have emerged with relevant consequences on patient management, particularly when dealing with long-term treatment and weaning of immunosuppression. : In this complex and challenging scenario, this review aims to depict the most relevant histopathologic conditions which could be encountered in pediatric liver transplantation. We will tackle the conditions representing the main indications for transplantation in childhood as well as the complications burdening the post-transplant phases, either immunologically (i.e., rejection) or non-immunologically mediated. Lastly, we hope to provide concise, yet significant, suggestions related to innovative pathology techniques in pediatric liver transplantation.openGambella, Alessandro; Mastracci, Luca; Caporalini, Chiara; Francalanci, Paola; Mescoli, Claudia; Ferro, Jacopo; Alaggio, Rita; Grillo, FedericaGambella, Alessandro; Mastracci, Luca; Caporalini, Chiara; Francalanci, Paola; Mescoli, Claudia; Ferro, Jacopo; Alaggio, Rita; Grillo, Federic

    Morphology and Molecular Features of Rare Colorectal Carcinoma Histotypes

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    Several histopathological variants of colorectal carcinoma can be distinguished, some associated with specific molecular profiles. However, in routine practice, ninety/ninety-five percent of all large bowel tumors are diagnosed as conventional adenocarcinoma, even though they are a heterogeneous group including rare histotypes, which are often under-recognized. Indeed, colorectal cancer exhibits differences in incidence, location of tumor, pathogenesis, molecular pathways and outcome depending on histotype. The aim is therefore to review the morphological and molecular features of these rare variants of intestinal carcinomas which may hold the key to differences in prognosis and treatment
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