1,951 research outputs found

    An extension of the associated rational functions on the unit circle

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    A special class of orthogonal rational functions (ORFs) is presented in this paper. Starting with a sequence of ORFs and the corresponding rational functions of the second kind, we define a new sequence as a linear combination of the previous ones, the coefficients of this linear combination being self-reciprocal rational functions. We show that, under very general conditions on the self-reciprocal coefficients, this new sequence satisfies orthogonality conditions as well as a recurrence relation. Further, we identify the Caratheodory function of the corresponding orthogonality measure in terms of such self-reciprocal coefficients. The new class under study includes the associated rational functions as a particular case. As a consequence of the previous general analysis, we obtain explicit representations for the associated rational functions of arbitrary order, as well as for the related Caratheodory function. Such representations are used to find new properties of the associated rational functions.Comment: 27 page

    What Should We Do to Prevent Zoonoses with Pandemic Potential?

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    The majority of new infectious diseases that affect human beings are zoonoses. Zoonotic pressure is increasing for various reasons. These include: 1) the growth of the human population; 2) the growing concentration of human beings; 3) the growing mobility of the human population; 4) the rapid growth in the human usage of nonhuman animals; 5) the increasing intensification of the farm animal sector; 6) increasing ecological degradation, and 7) the lack of political will to address the previous six factors. These factors and the interplay between them create perfect storm conditions for the emergence of zoonoses with pandemic potential. What compounds the problem is a lack of moral theory on how to prevent zoonoses and associated pandemics. This article aims to address this gap by drawing on interdisciplinary work on zoonotic and pandemic prevention

    Veganism

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    Narrowly understood, veganism is the practice of excluding all animal products from one’s diet, with the exception of human milk. More broadly, veganism is not only a food ethics, but it encompasses all other areas of life. As defined by the Vegan Society when it became an established charity in the UK in 1979, veganism is best understood as “a philosophy and way of living which seeks to exclude – as far as is possible and practicable – all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose; and by extension, promotes the development and use of animal-free alternatives for the benefit of humans, animals and the environment”. There are two main moral justifications for veganism, both of which rely on a common assumption: that sentience, i.e., the capacity to feel pleasure and pain, is the necessary and sufficient trait to be morally considerable. In what follows, I present these two justifications and a third one which, although less popular, captures some core intuitions among vegans. I then present a challenge faced by veganism and two arguments that reject it as discriminatory, and briefly conclude

    Determinants of soil organic matter chemistry in maritime temperate forest ecosystems

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    While the influence of climate, vegetation, management and abiotic site factors on total carbon budgets and turn-over is intensively assessed, the influences of these ecosystem properties on the chemical complexity of soil organic matter (SOM) remains poorly understood. This study addresses the chemical composition of NaOH-extracted SOM from maritime temperate forest sites in Flanders (Belgium) by pyrolysis-GC/MS. The studied forests were chosen based on dominant tree species (Pinus sylvestris, Fagus sylvatica, Quercus robur and Populus spp.), soil texture and soil-moisture conditions. Differences in extractable-SOM pyrolysis products were correlated to site variables including dominant tree species, management of the woody biomass, site history, soil properties, total carbon stocks and indicators for microbial activity. Despite of a typical high intercorrelation between these site variables, the influence of the dominant tree species is prominent. The extractable-SOM composition is strongly correlated to litter quality and available nutrients. In nutrient-poor forests with low litter quality, the decomposition of relatively recalcitrant compounds (i.e. short and mid-chain alkanes/alkenes and aromatic compounds) appears hampered, causing a relative accumulation of these compounds in the soil. However, if substrate quality is favorable, no accumulations of recalcitrant compounds were observed, not even under high soil-moisture conditions. Former heathland vegetation still had a profound influence on extractable-SOM chemistry of young pine forests after a minimum of 60 year
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