726 research outputs found

    Corrigendum to ‘Dietary aflatoxin B1 (AFB1) reduces growth performance, impacting growth axis, metabolism, and tissue integrity in juvenile gilthead sea bream (Sparus aurata)’. Aquaculture, volume 533, 25 February 2021, 736189

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    The authors regret the errors in a few table references within the text. Specifically, it should reads as follows within the following subsections/ page: 3.2. Blood analysis (page 5)info:eu-repo/semantics/publishedVersio

    A computational analysis of lower bounds for big bucket production planning problems

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    In this paper, we analyze a variety of approaches to obtain lower bounds for multi-level production planning problems with big bucket capacities, i.e., problems in which multiple items compete for the same resources. We give an extensive survey of both known and new methods, and also establish relationships between some of these methods that, to our knowledge, have not been presented before. As will be highlighted, understanding the substructures of difficult problems provide crucial insights on why these problems are hard to solve, and this is addressed by a thorough analysis in the paper. We conclude with computational results on a variety of widely used test sets, and a discussion of future research

    Why 'scaffolding' is the wrong metaphor : the cognitive usefulness of mathematical representations.

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    The metaphor of scaffolding has become current in discussions of the cognitive help we get from artefacts, environmental affordances and each other. Consideration of mathematical tools and representations indicates that in these cases at least (and plausibly for others), scaffolding is the wrong picture, because scaffolding in good order is immobile, temporary and crude. Mathematical representations can be manipulated, are not temporary structures to aid development, and are refined. Reflection on examples from elementary algebra indicates that Menary is on the right track with his ‘enculturation’ view of mathematical cognition. Moreover, these examples allow us to elaborate his remarks on the uniqueness of mathematical representations and their role in the emergence of new thoughts.Peer reviewe

    Potential energy threshold for nano-hillock formation by impact of slow highly charged ions on a CaF2_2(111) surface

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    We investigate the formation of nano-sized hillocks on the (111) surface of CaF2_2 single crystals by impact of slow highly charged ions. Atomic force microscopy reveals a surprisingly sharp and well-defined threshold of potential energy carried into the collision of about 14 keV for hillock formation. Estimates of the energy density deposited suggest that the threshold is linked to a solid-liquid phase transition (``melting'') on the nanoscale. With increasing potential energy, both the basal diameter and the height of the hillocks increase. The present results reveal a remarkable similarity between the present predominantly potential-energy driven process and track formation by the thermal spike of swift (\sim GeV) heavy ions.Comment: 10 pages, 2 figure

    A Cauchy-Dirac delta function

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    The Dirac delta function has solid roots in 19th century work in Fourier analysis and singular integrals by Cauchy and others, anticipating Dirac's discovery by over a century, and illuminating the nature of Cauchy's infinitesimals and his infinitesimal definition of delta.Comment: 24 pages, 2 figures; Foundations of Science, 201

    Ten Misconceptions from the History of Analysis and Their Debunking

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    The widespread idea that infinitesimals were "eliminated" by the "great triumvirate" of Cantor, Dedekind, and Weierstrass is refuted by an uninterrupted chain of work on infinitesimal-enriched number systems. The elimination claim is an oversimplification created by triumvirate followers, who tend to view the history of analysis as a pre-ordained march toward the radiant future of Weierstrassian epsilontics. In the present text, we document distortions of the history of analysis stemming from the triumvirate ideology of ontological minimalism, which identified the continuum with a single number system. Such anachronistic distortions characterize the received interpretation of Stevin, Leibniz, d'Alembert, Cauchy, and others.Comment: 46 pages, 4 figures; Foundations of Science (2012). arXiv admin note: text overlap with arXiv:1108.2885 and arXiv:1110.545

    Mixed integer programming in production planning with backlogging and setup carryover : modeling and algorithms

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    This paper proposes a mixed integer programming formulation for modeling the capacitated multi-level lot sizing problem with both backlogging and setup carryover. Based on the model formulation, a progressive time-oriented decomposition heuristic framework is then proposed, where improvement and construction heuristics are effectively combined, therefore efficiently avoiding the weaknesses associated with the one-time decisions made by other classical time-oriented decomposition algorithms. Computational results show that the proposed optimization framework provides competitive solutions within a reasonable time

    The Epigravettian chronology and the human population of eastern Central Europe during MIS2

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    The goal of this paper is to refine the relative and absolute chronology of Epigravettian culture (26.5-15.0 ka) in eastern Central Europe (ECE) and clarify its relation to the Last Glacial Maximum (LGM) and subsequent climatic changes. Epigravettian sites were sorted into three chronological clusters: initial LGM (ILGM) (26.5-24.0 ka), local LGM (LLGM) (24.0-20.0 ka), and post-LGM (PLGM) (20.0-14.7 ka). We obtained new radiocarbon dates from previously dated and undated sites, then analysed the lithic tool typology and faunal data to seek correlations between age and archaeological features.The lithic typology study did not find differences between ILGM and LLGM sites, but the tool type variance between LLGM and PLGM was significant, applicable for relative chronology. ILGM and LLGM lithic assemblages were characterized by domestic tool dominance and the frequent use of flake tools. PLGM assemblages were correlated with armature dominance and blade/let tools. Among the armatures, backed point variants characterized the PLGM sites compared to the ILGM and LLGM. The sole ILGM lithic armature was the retouched blade/let point. The LLGM also possessed this type and often included backed blade/lets.ILGM faunal data, although few, implied the hunting of mammoth and reindeer. The LLGM data represented recurring hunting of reindeer and horse, and PLGM data indicated the hunting of horse, reindeer, and mammoth.Our results suggested that the territory of Poland was deserted by humans in the LLGM. Moravia and Lower Austria was inhabited until the first half of the LLGM, while the Carpathian Basin was all along the ILGM. The preference for the Carpathian Basin could have been the milder climate, the abundance of fauna, and permanent access to tree vegetation. After the LGM the glacial flora and fauna gradually disappeared, leading to a reduced human presence in southern ECE. Thus, the disappearance of the Epigravettian culture and Pleistocene hunter-gatherer occupations are linked to the amelioration of climate that resulted in the disappearance of the Pleistocene environment. (C) 2021 The Authors. Published by Elsevier Ltd.Human Origin
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