90 research outputs found

    Longevity and clinical effectiveness of the humoral and cellular responses to SARS-CoV-2 vaccination in hemodialysis patients

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    sponsorship: The authors are indebted to Tessa Acke, Manuela Caster, Evelyne Deglorie, Mirjam Demesmaecker, Suzanne Dries-sens, Inne Hoebrekx, Annelien Leunen, Carine Lowis, Isa-bel Moyaert, Danny Pauwels, Joris Penders, Melissa Renders, Carmen Reynders, Sofie Tombeur, Katrien Uyt-tersprot, Femke Van Den Berg, Kristel Van Varenbergh, Tine Verheyen, Manon Verhulst, and Sophie Vlee-schouwers for their invaluable help in the collection of the patient data and analysis of the samples. This research was supported by a grant of Amgen (DONATION-331036) . The funding source had no role in the design, conduct, or analysis of the study or the decision to submit the manu-script for publication. (Amgen|DONATION-331036)status: Publishe

    Calcium balance in chronic kidney disease: walking the tightrope

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    Calcium supplements for prevention and treatment of mineral and bone disorders in chronic kidney disease (CKD) have been alternately praised and damned. Clinical evidence in favor of either attitude has been lacking. The calcium balance study by Spiegel and Brady in patients with late stage 3 and stage 4 CKD suggests that CKD subjects ingesting 2000mg of elemental calcium per day are in marked positive balance. Methodological limitations such as unproven steady state warrant caution and confirmatory studies

    Factors Associated to Purchase of Quality-Labelled Beef

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    The aim of the present study is to identify the factors associated to purchase of quality-labelled beef. For this purpose a total of 364 surveys were carried out on buyers of beef in three Spanish cities. The sample was divided into three groups of buyers according to the beef purchasing habits with a quality label. A logistic regression analysis was used to estimate the differences between groups. The results show the importance of the production region as a quality aspect. Income level, association of quality-labelled beef with “guarantee and tradition” aspects, purchasing frequency, place of purchase, production systems and lifestyles are all variables that enabled us to establish differences between groups.beef quality, quality label, consumer perception, Demand and Price Analysis,

    Exploring metamaterial horizons: New concepts and geometrical tools for the description of advanced electromagnetic phenomena

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    Einstein’s theory of general relativity has dramatically changed our world view, by describing gravity as an intrinsic deformation of space and time. About fifteen years ago, John Pendry and Ulf Leonhardt had the intriguing idea to emulate the behaviour of light in a deformed space by making use of carefully designed artificial metamaterials. Metamaterials consist of elements that are very small with respect to the characteristic length of light waves. By optimizing the shape, the density, and the size of these elements, metamaterials can control the trajectory of light rays in a very precise way that allows them to reproduce light trajectories inside a deformed space. The equivalence between a deformed space and specific metamaterial properties lies at the heart of the technique known as transformation optics and allows for a very intuitive understanding of the behaviour of light inside advanced metamaterials. For example, transformation optics has been used to design invisibility devices that hide an object by smoothly guiding light rays around it. In recent years, rapidly advancing fabrication methods have resulted in metamaterial designs that are not yet understood in an intuitive way, such as reconfigurable, two-dimensional, or quantum metamaterials. In this work, the author introduces new concepts to describe advanced metamaterial designs in an intuitive way, so that they can be used in future light-based applications. The author starts by reviewing the fields of metamaterials and transformation optics. Based on three hallmark elements, i.e., thin wires, split-ring resonators, and helices, the first chapter discusses the unusual behaviour of light inside negative-index, hyperbolic, and chiral metamaterials as well as their relevance to photonic applications. Subsequently, in the second chapter, transformation optics is shown to be a powerful design tool that naturally extends the principle of Fermat from simple dielectrics to the realm of metamaterials. In the following chapters, the author introduces several concepts to describe advanced metamaterial designs such as materials that implement vector potentials for photons, reconfigurable metasurfaces with fundamental speed limits, two-dimensional metamaterial waveguides that emulate a deformation of their surface, and metamaterial black holes
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