4,975 research outputs found

    Vassiliev Invariants for Links from Chern-Simons Perturbation Theory

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    The general structure of the perturbative expansion of the vacuum expectation value of a product of Wilson-loop operators is analyzed in the context of Chern-Simons gauge theory. Wilson loops are opened into Wilson lines in order to unravel the algebraic structure encoded in the group factors of the perturbative series expansion. In the process a factorization theorem is proved for Wilson lines. Wilson lines are then closed back into Wilson loops and new link invariants of finite type are defined. Integral expressions for these invariants are presented for the first three primitive ones of lower degree in the case of two-component links. In addition, explicit numerical results are obtained for all two-component links of no more than six crossings up to degree four.Comment: 44 pages, LaTex, epsf.sty, 15 figure

    The Neoplastic Side of the Abdominal Wall: A Comprehensive Pictorial Essay of Benign and Malignant Neoplasms

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    Abdominal wall neoplasms are usually benign and, in the majority of these cases, no further work-up or treatment is indicated. The percentage of malignant abdominal neoplasms, however, is not negligible. Radiologists play a pivotal role in identifying imaging features that should favor malignancy, including larger lesion size, edema, neurovascular involvement, and peripheral or inhomogeneous dynamic enhancement, thus indicating to the clinician the need for further work-up. Histopathology is the reference standard for the characterization of abdominal wall neoplasms. In patients undergoing surgery, radiological assessment is needed to guide the surgeon by providing a comprehensive anatomic guide of the tumor extension. We present a pictorial review of benign and malignant abdominal wall neoplasms that can be encountered on radiological examinations, with a main focus on CT and MRI features that help in narrowing the differential diagnosis

    The Benign Side of the Abdominal Wall: A Pictorial Review of Non-Neoplastic Diseases

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    The abdominal wall is the location of a wide spectrum of pathological conditions, from benign to malignant ones. Imaging is often recommended for the evaluation of known palpable abdominal masses. However, abdominal wall pathologies are often incidentally discovered and represent a clinical and diagnostic challenge. Knowledge of the possible etiologies and complications, combined with clinical history and laboratory findings, is crucial for the correct management of these conditions. Specific imaging clues can help the radiologist narrow the differential diagnosis and distinguish between malignant and benign processes. In this pictorial review, we will focus on the non-neoplastic benign masses and processes that can be encountered on the abdominal wall on cross-sectional imaging, with a particular focus on their management. Distinctive sonographic imaging clues, compared with computed tomography (CT) and magnetic resonance (MR) findings will be highlighted, together with clinical and practical tips for reaching the diagnosis and guiding patient management, to provide a complete diagnostic guide for the radiologist

    Entre la decolonización y el capital humano. reflexiones en torno al rol esperado del docente en el Chile post transición

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    The relationship between socioeconomic mobility and school levels has been thematized since the generalization of modern institutionalized education systems. The demand for Chilean quality education is associated with exitism and the formation of Human Capital, crashing with mismatches between public policies, the crisis of legitimization of public education, and the Latin American epistemic advance that influences the pedagogical exercise through critical pedagogy or decolonization as a new way of organizing / re-creating knowledge. Thus, the teacher is required from two dichotomous currents, which makes him a vortex with unusual edges. This article of reflection seeks to expose some aspects of these contradictions, addressing the theory of Human Capital in education and the decolonization of pedagogy, in relation to the expected role of teachers in Chile.La relación entre movilidad socioeconómica y niveles escolares se ha tematizado desde la generalización de los sistemas institucionalizados modernos de educación. La exigencia de educación de calidad chilena está asociada al exitismo y a la formación de Capital Humano, estrellándose con desajustes entre políticas públicas, la crisis de legitimación de la educación pública, y el avance epistémico latinoamericano que influye el ejercicio pedagógico a través de la pedagogía crítica o la descolonización como nueva forma de organizar/re-crear conocimiento. Es así que el docente es requerido desde dos corrientes dicotómicas, lo que le convierte en un vórtice con inusitadas aristas. El presente artículo de reflexión busca exponer algunos aspectos de dichas contradicciones, abordando la teoría de Capital Humano en educación y de la decolonización de la pedagogía, en relación al rol esperado del profesorado en Chile

    Entre la decolonización y el capital humano. reflexiones en torno al rol esperado del docente en el Chile post transición

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    The relationship between socioeconomic mobility and school levels has been thematized since the generalization of modern institutionalized education systems. The demand for Chilean quality education is associated with exitism and the formation of Human Capital, crashing with mismatches between public policies, the crisis of legitimization of public education, and the Latin American epistemic advance that influences the pedagogical exercise through critical pedagogy or decolonization as a new way of organizing / re-creating knowledge. Thus, the teacher is required from two dichotomous currents, which makes him a vortex with unusual edges. This article of reflection seeks to expose some aspects of these contradictions, addressing the theory of Human Capital in education and the decolonization of pedagogy, in relation to the expected role of teachers in Chile.La relación entre movilidad socioeconómica y niveles escolares se ha tematizado desde la generalización de los sistemas institucionalizados modernos de educación. La exigencia de educación de calidad chilena está asociada al exitismo y a la formación de Capital Humano, estrellándose con desajustes entre políticas públicas, la crisis de legitimación de la educación pública, y el avance epistémico latinoamericano que influye el ejercicio pedagógico a través de la pedagogía crítica o la descolonización como nueva forma de organizar/re-crear conocimiento. Es así que el docente es requerido desde dos corrientes dicotómicas, lo que le convierte en un vórtice con inusitadas aristas. El presente artículo de reflexión busca exponer algunos aspectos de dichas contradicciones, abordando la teoría de Capital Humano en educación y de la decolonización de la pedagogía, en relación al rol esperado del profesorado en Chile

    AB0690 Antiphospholipid antibodies and spondyloarthritis. Truth or myth? Our results in a third level hospital

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    [EN] The importance of antiphospholipid antibodies and their clinical involvement in thrombotic phenomena, isolated or associated with certain autoimmune diseases such as systemic lupus erythematosus, is known. However, in spondyloarthritis (SpA) there is little published data about it.S

    Modeling of the binodal curve of ionic liquid/salt aqueous systems

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    Ionic Liquid-based Aqueous Two Phase Systems (ILATPS) are an innovative technique to separate biomolecules that combines the advantages of liquid–liquid extraction and hydrophilic ionic liquids. Most ILATPS are based on ionic liquids and conventional inorganic salts, and the phase envelope, described by the binodal curve, is usually modeled by empirical equations that are used to determine the phase compositions and assess the ionic liquid recyclability. However, these empirical equations may provide a poor extrapolation ability or low accuracy at the extreme regions of the binodal curve or suffer from problems of convergence. Therefore, the aim of this work is the analysis of the binodal curve equations, comparing the models reported in the literature to describe ILATPS and proposing alternative equations to improve accuracy or to reduce the mathematical complexity. For this purpose, a database compiling binodal experimental data of 100 ILATPS has been built, so that the analysis could make it possible to obtain representative conclusions for all these systems. Several models were developed, and different statistical criteria were used to assess the advantages and disadvantages of each one of these models for the binodal curve. The results show that, when accuracy is critical, a proposed model with just an additional parameter reduced more than 25% the residual mean squared error (RMSE) with respect to the commonly used equation, without losing the statistical significance of the parameters. For complex problems where an explicit equation in both the concentration of ionic liquid and of salt is needed, the use of an explicit model developed with 3 adjusted parameters that kept high accuracy (R2 > 0.996 and RMSE < 0.66) is proposed. Finally, the analysis also revealed that a fitting method based on the minimization of relative errors is recommended to increase the accuracy of the binodal curve at high salt concentrations, which is the crucial region for assessing the recyclability of the ionic liquid.This work was developed in the scope of the project CICECO Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and co-financed by FEDER under the PT2020 Partnership Agreement. The authors also acknowledge FCT for the Post-doctoral grant SFRH/BPD/79263/2011 of S.P.M. Ventura
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