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  1. Article ; Online: conditions for Turing and wave instabilities in reaction-diffusion systems.

    Villar-Sepúlveda, Edgardo / Champneys, Alan R

    Journal of mathematical biology

    2023  Volume 86, Issue 3, Page(s) 39

    Abstract: ... equilibrium of a reaction-diffusion system with n components and diagonal diffusion matrix. These can be ...

    Abstract Necessary and sufficient conditions are provided for a diffusion-driven instability of a stable equilibrium of a reaction-diffusion system with n components and diagonal diffusion matrix. These can be either Turing or wave instabilities. Known necessary and sufficient conditions are reproduced for there to exist diffusion rates that cause a Turing bifurcation of a stable homogeneous state in the absence of diffusion. The method of proof here though, which is based on study of dispersion relations in the contrasting limits in which the wavenumber tends to zero and to [Formula: see text], gives a constructive method for choosing diffusion constants. The results are illustrated on a 3-component FitzHugh-Nagumo-like model proposed to study excitable wavetrains, and for two different coupled Brusselator systems with 4-components.
    Language English
    Publishing date 2023-01-28
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 187101-8
    ISSN 1432-1416 ; 0303-6812
    ISSN (online) 1432-1416
    ISSN 0303-6812
    DOI 10.1007/s00285-023-01870-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 1495: Show issues Location:
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    Jg. 1995 - 2021: Lesesall (1.OG)
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  2. Article ; Online: Impact of risk factors on the efficacy and complications of ultrasound-guided percutaneous liver biopsy of space-occupying lesions.

    Varela-Ponte, R / Martínez-Lago, N / Vieito-Villar, M / Martin Carreira-Villamor, J

    Radiologia

    2022  Volume 64, Issue 6, Page(s) 497–505

    Abstract: Introduction: Ultrasound-guided percutaneous liver biopsy is considered the technique of choice for the histological diagnosis of space-occupying lesions, given its high level of safety and diagnostic performance. However, since it is an invasive ... ...

    Abstract Introduction: Ultrasound-guided percutaneous liver biopsy is considered the technique of choice for the histological diagnosis of space-occupying lesions, given its high level of safety and diagnostic performance. However, since it is an invasive diagnostic procedure, complications can occur. Various clinical and radiological parameters have been analysed as factors related with the efficacy of the technique or with its complications; however, the results have been contradictory. Thus, we aimed to evaluate the impact of various risk factors on the efficacy and complications of ultrasound-guided percutaneous liver biopsy in the diagnosis of space-occupying lesions in ordinary clinical practice.
    Material and methods: This retrospective observational study included all patients who underwent real-time ultrasound-guided percutaneous biopsies of space-occupying liver lesions with the free-hand technique between December 2012 and February 2018 in the diagnostic imaging department at the Hospital Clínico Universitario de Santiago de Compostela. We analysed the following risk factors: location of the lesion in upper liver segments (II, IVa, VII, or VIII); proximity to the liver capsule, distance from the skin >100mm, interposition of osseus or vascular structures, inability to go through healthy parenchyma, and lack of patient cooperation during the procedure. Efficacy was analysed in terms of the number of cylinders obtained and the percentage of adequate biopsies; safety was analysed in terms of the percentage of complications, which were classified as major or minor.
    Results: We included 295 biopsies in 278 patients (median age, 69 years; 64.1% male; 44.7% had prior neoplasms). In 61.4%, the biopsy was indicated for the initial diagnosis; 82.4% of biopsies were done in hospitalised patients, and 65% of the lesions were located in the right liver lobe. The median number of cylinders obtained was 3 (range 1-6); 91.2% of the biopsies were adequate and 92.2% were considered clinically useful. These percentages did not differ significantly according to the presence of risk factors. Complications occurred in 10 (3.4%) patients. Complications were considered major in 3 (0.9%) patients (2 (0.6%) bleeding complications and 1 (0.3%) infectious complication) and minor in 7 (2.4%). The percentage of complications was significantly higher in patients who did not cooperate during the procedure (P=.04).
    Conclusions: Ultrasound-guided percutaneous liver biopsy is an efficacious and safe technique for the histological diagnosis of space-occupying liver lesions. Our results confirm the increased rate of complications when patients fail to cooperate during the procedure.
    MeSH term(s) Humans ; Male ; Aged ; Female ; Image-Guided Biopsy/adverse effects ; Risk Factors ; Ultrasonography, Interventional/adverse effects ; Liver Neoplasms/diagnostic imaging
    Language English
    Publishing date 2022-06-02
    Publishing country Spain
    Document type Observational Study ; Journal Article
    ISSN 2173-5107
    ISSN (online) 2173-5107
    DOI 10.1016/j.rxeng.2020.09.012
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Gatekeepers to quality.

    Villar, R N

    The bone & joint journal

    2013  Volume 95-B, Issue 1, Page(s) 1

    MeSH term(s) Editorial Policies ; Orthopedics ; Periodicals as Topic/standards
    Language English
    Publishing date 2013-01
    Publishing country England
    Document type Editorial
    ZDB-ID 2697156-2
    ISSN 2049-4408 ; 2049-4394
    ISSN (online) 2049-4408
    ISSN 2049-4394
    DOI 10.1302/0301-620X.95B1.31374
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  4. Article ; Online: Reshaping orthopaedic history.

    Villar, R N

    The bone & joint journal

    2013  Volume 95-B, Issue 4, Page(s) 433

    MeSH term(s) Orthopedics ; Periodicals as Topic ; Publishing
    Language English
    Publishing date 2013-04
    Publishing country England
    Document type Editorial
    ZDB-ID 2697156-2
    ISSN 2049-4408 ; 2049-4394
    ISSN (online) 2049-4408
    ISSN 2049-4394
    DOI 10.1302/0301-620X.95B4.31901
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  5. Article ; Online: What an editor seeks.

    Villar, R N

    The bone & joint journal

    2013  Volume 95-B, Issue 5, Page(s) 577

    MeSH term(s) Biomedical Research/standards ; Editorial Policies ; Orthopedics/standards ; Publishing/standards
    Language English
    Publishing date 2013-05
    Publishing country England
    Document type Editorial
    ZDB-ID 2697156-2
    ISSN 2049-4408 ; 2049-4394
    ISSN (online) 2049-4408
    ISSN 2049-4394
    DOI 10.1302/0301-620X.95B5.32071
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: What the guru showed me.

    Villar, R N

    The bone & joint journal

    2013  Volume 95-B, Issue 2, Page(s) 145

    MeSH term(s) Cultural Diversity ; Humans ; Interpersonal Relations ; Journalism, Medical ; United Kingdom
    Language English
    Publishing date 2013-02
    Publishing country England
    Document type Editorial ; Personal Narratives
    ZDB-ID 2697156-2
    ISSN 2049-4408 ; 2049-4394
    ISSN (online) 2049-4408
    ISSN 2049-4394
    DOI 10.1302/0301-620X.95B2.31559
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: The skill of the primary rewriter.

    Villar, R N

    The bone & joint journal

    2013  Volume 95-B, Issue 3, Page(s) 289

    MeSH term(s) Editorial Policies ; Orthopedics ; Periodicals as Topic ; Writing
    Language English
    Publishing date 2013-03
    Publishing country England
    Document type Editorial
    ZDB-ID 2697156-2
    ISSN 2049-4408 ; 2049-4394
    ISSN (online) 2049-4408
    ISSN 2049-4394
    DOI 10.1302/0301-620X.95B3.31742
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Book ; Online: Approximately Equivariant Graph Networks

    Huang, Ningyuan / Levie, Ron / Villar, Soledad

    2023  

    Abstract: Graph neural networks (GNNs) are commonly described as being permutation equivariant with respect to node relabeling in the graph. This symmetry of GNNs is often compared to the translation equivariance symmetry of Euclidean convolution neural networks ( ... ...

    Abstract Graph neural networks (GNNs) are commonly described as being permutation equivariant with respect to node relabeling in the graph. This symmetry of GNNs is often compared to the translation equivariance symmetry of Euclidean convolution neural networks (CNNs). However, these two symmetries are fundamentally different: The translation equivariance of CNNs corresponds to symmetries of the fixed domain acting on the image signal (sometimes known as active symmetries), whereas in GNNs any permutation acts on both the graph signals and the graph domain (sometimes described as passive symmetries). In this work, we focus on the active symmetries of GNNs, by considering a learning setting where signals are supported on a fixed graph. In this case, the natural symmetries of GNNs are the automorphisms of the graph. Since real-world graphs tend to be asymmetric, we relax the notion of symmetries by formalizing approximate symmetries via graph coarsening. We present a bias-variance formula that quantifies the tradeoff between the loss in expressivity and the gain in the regularity of the learned estimator, depending on the chosen symmetry group. To illustrate our approach, we conduct extensive experiments on image inpainting, traffic flow prediction, and human pose estimation with different choices of symmetries. We show theoretically and empirically that the best generalization performance can be achieved by choosing a suitably larger group than the graph automorphism group, but smaller than the full permutation group.
    Keywords Statistics - Machine Learning ; Computer Science - Machine Learning
    Subject code 511
    Publishing date 2023-08-20
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: What's in a name?

    Villar, R N

    The Journal of bone and joint surgery. British volume

    2012  Volume 94, Issue 12, Page(s) 1585

    MeSH term(s) Humans ; Names ; Periodicals as Topic
    Language English
    Publishing date 2012-12
    Publishing country England
    Document type Editorial
    ZDB-ID 220626-2
    ISSN 2044-5377 ; 0301-620X ; 0447-9076
    ISSN (online) 2044-5377
    ISSN 0301-620X ; 0447-9076
    DOI 10.1302/0301-620X.94B12.31183
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    Uk I Zs.58/1: Show issues Location:
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  10. Article ; Online: Enhancement of lossy mode resonance sensing properties by the introduction of an intermediate low-refractive-index layer.

    Armas, Dayron / Kwietniewski, Norbert / Matías, Ignacio R / Burnat, Dariusz / Śmietana, Mateusz / Del Villar, Ignacio

    Optics letters

    2023  Volume 48, Issue 12, Page(s) 3123–3126

    Abstract: Devices based on the lossy mode resonance (LMR) effect have found numerous sensing applications. Herein, the enhancement of the sensing properties by the introduction of an intermediate layer between the substrate and the LMR-supporting film is discussed. ...

    Abstract Devices based on the lossy mode resonance (LMR) effect have found numerous sensing applications. Herein, the enhancement of the sensing properties by the introduction of an intermediate layer between the substrate and the LMR-supporting film is discussed. Experimental results for a silicon oxide (SiO
    MeSH term(s) Refractometry ; Biosensing Techniques ; Silicon Dioxide
    Chemical Substances Silicon Dioxide (7631-86-9)
    Language English
    Publishing date 2023-06-16
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4794
    ISSN (online) 1539-4794
    DOI 10.1364/OL.487135
    Database MEDical Literature Analysis and Retrieval System OnLINE

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