803 research outputs found

    Non-Gaussian buoyancy statistics in fingering convection

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    We examine the statistics of active scalar fluctuations in high-Rayleigh number fingering convection with high-resolution three-dimensional numerical experiments. The one-point distribution of buoyancy fluctuations is found to present significantly non-Gaussian tails. A modified theory based on an original approach by Yakhot (1989) is used to model the active scalar distributions as a function of the conditional expectation values of scalar dissipation and fluxes in the flow. Simple models for these two quantities highlight the role of blob-like coherent structures for scalar statistics in fingering convection

    Sénescence, sélection sexuelle et dynamique de population du bouquetin des Alpes (Capra Ibex)

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    Le principal objectif de cette thĂšse est d’étudier les variations intra et inter individuelle pour deux traits phĂ©notypiques reliĂ©s Ă  la valeur sĂ©lective, et d’analyser la dynamique d’une population sauvage de bouquetin des Alpes (Capra ibex). Le premier chapitre analyse la relation de deux traits phĂ©notypiques reliĂ©s Ă  la valeur sĂ©lective (le gain de masse corporelle, et l’intensitĂ© d’infection parasitaire gastro-intestinal) et d’un caractĂšre sexuel secondaire (la croissance des cornes) avec l’ñge, des facteurs environnementaux, la survie, et avec l’hĂ©tĂ©rozygotie, ceci au sein d’un large Ă©chantillon de bouquetins des Alpes mĂąles en libertĂ©s et marquĂ©s individuellement. À travers la croissance corporelle et les comptages fĂ©caux d’oeufs de nĂ©matodes gastro-intestinaux, il a Ă©tĂ© mis en Ă©vidence un phĂ©nomĂšne de sĂ©nescence et de coĂ»t pour la reproduction. En analysant un large Ă©chantillon de squelettes de bouquetins mĂąles trouvĂ©s morts dans l’hiver pour cause de famine, nous avons trouvĂ© que le dĂ©but de la sĂ©nescence Ă©tait caractĂ©risĂ© par la longueur de segments de croissance annuels Ăąges spĂ©cifiques des cornes, mais pas par leur asymĂ©trie. Enfin, des corrĂ©lations entre l’hĂ©tĂ©rozygotie et la valeur sĂ©lective ont Ă©tĂ© mises en Ă©vidence pour la croissance des cornes, mais pas pour la masse corporelle et l’intensitĂ© d’infection parasitaire. Le deuxiĂšme chapitre traite de l’importance relative de la densitĂ© dĂ©pendance et de la variabilitĂ© stochastique du climat sur la dynamique d’une population d’ongulĂ© de montagne, Ă  travers l’analyse de sĂ©rie temporelle de 45 ans de recensements de bouquetins des Alpes collectĂ©s dans le Parc National du Grand Paradis en Italie. Pendant les 28 premiĂšres annĂ©es de l’étude, le nombre total de bouquetins a variĂ© entre 2600 et 4000 sans tendance visuelle apparente. Au cours de cette pĂ©riode, il est apparu que des oscillations avec une pĂ©riodicitĂ© de 3 Ă  8 ans Ă©taient prĂ©sentes. DĂšs 1982, les comptages de bouquetin ont augmentĂ©s rĂ©guliĂšrement pour atteindre un pic de 5000 en 1993 et ensuite dĂ©croĂźtre. Nous avons montrĂ© que la taille de population du bouquetin Ă©tait limitĂ©e Ă  la fois par la densitĂ© dĂ©pendance et par l’épaisseur de neige. Un modĂšle basĂ© sur ces deux facteurs et ajustĂ© pour les 19 premiĂšres annĂ©es de donnĂ©es, rĂ©ussi avec succĂšs Ă  prĂ©dire l’augmentation et le dĂ©clin subsĂ©quent de la taille totale de la population pour les 20 derniĂšres annĂ©es de l’étude. Cette thĂšse conclue avec un troisiĂšme chapitre prĂ©sentant deux techniques innovatrices utiles pour l’étude de populations d’ongulĂ©s en libertĂ©.Abstract: The main objectives of this thesis are to investigate within and between-individual variation in fitness related phenotypic traits and to analyse the population dynamics of a wild population of Alpine ibex (Capra ibex). The first chapter analyzes the relationship of two fitness-related phenotypic traits (body mass gain and the intensity of gastrointestinal parasite infection) and one secondary sexual trait (horn growth) with age, environmental factors, survival and heterozygosity in a large sample of individually tagged free-ranging Alpine ibex males. Evidence for senescence and costs of reproduction in body growth and fecal counts of gastrointestinal nematode eggs was found. Analysing a large sample of male ibex skulls, found dead in winter from starvation, we found that the onset of senescence was signaled by the length of age specific yearly horn growth segments, but not by their asymmetry. Finally evidence for heterozygosity-fitness correlations was found for horn growth, but not for body mass and the intensity of parasite infection. The second chapter investigates the relative importance of density dependence and of stochastic climatic variability in the population dynamics of a mountain ungulate, analysing a 45 year long time series of Alpine ibex censuses collected in the Gran Paradiso National Park, Italy During the first 28 years of the study, the total number of ibex ranged from about 2600 to about 4000 with no visually apparent trend. During this period oscillations with periodicities of about 3 and 8 years appeared to be present. From 1982 onwards, ibex counts increased steadily and peaked at almost 5000 in 1993, decreasing afterwards. We show that the ibex population size was limited by both density dependence and deep snow. A model based on these factors fit to the first 19 years of data was successful in forecasting the increase and subsequent decline in total population size over the final 20 years of the study. The thesis concludes with a third chapter presenting two innovative techniques useful in the study of free-ranging populations of ungulates

    Generation of large-scale winds in horizontally anisotropic convection

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    We simulate three-dimensional, horizontally periodic Rayleigh-B\'enard convection between free-slip horizontal plates, rotating about a distant horizontal axis. When both the temperature difference between the plates and the rotation rate are sufficiently large, a strong horizontal wind is generated that is perpendicular to both the rotation vector and the gravity vector. The wind is turbulent, large-scale, and vertically sheared. Horizontal anisotropy, engendered here by rotation, appears necessary for such wind generation. Most of the kinetic energy of the flow resides in the wind, and the vertical turbulent heat flux is much lower on average than when there is no wind

    German Pig Farmers’ Attitudes towards Animal Welfare Programs and their Willingness to Participate in these Programs: An Empirical Study

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    In recent years, the image of intensive livestock production systems has been suffering from increasing public criticism. Many consumers express strong demands for higher farm animal welfare standards – especially in conventional livestock husbandry systems. This applies primarily to products from pork production, as consumers have criticized that the animals have not enough space in their stables and no possibility for outdoor access. Although pig farmers are key stakeholders for the implementation of animal welfare programs (AWPs) there is little evidence of their attitudes towards AWPs. Thus, the main objective of this investigation was to investigate pig farmers’ attitudes towards AWPs and to determine target groups for participation in AWPs. Therefore conventional pig farmers throughout Germany were questioned via an online survey. For statistical analysis an explorative factor analysis and a hierarchical cluster analysis were applied. Four factors and three farmer groups were identified which significantly differ regarding their attitudes towards AWPs and their willingness to participate in AWPs. For all groups of farmers the economic aspects are important for implementing AWPs. The orientation on the production process is strongly influenced by monetary aspects. This paper represents a starting point for the design of tailormade strategies to increase the market penetration of AWPs and to provide incentives for farmers to participate in AWPs. Further financial incentives are needed to transfer pig farmers attitudes into corresponding behaviour

    Deregulierung in der öffentlichen Debatte in Deutschland

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    Die Studie untersucht die öffentlichen Äußerungen in Reden, PressebeitrĂ€gen und Presseinterviews von fĂŒhrenden deutschen Politikern und wirtschaftswissenschaftlichen Politikberatern zu Deregulierungsforderungen fĂŒr den Zeitraum zwischen der Agenda-2010 Rede des damaligen Bundeskanzlers Gerhard Schröder im FrĂŒhjahr 2003 bis zum Ausbruch der Finanzkrise 2007. Aus den Forderungen dieser Persönlichkeiten wird danach ein Regulierungsindex berechnet, an dem man ablesen kann, wie stark sich der Einzelne fĂŒr den RĂŒckbau des Staates ausgesprochen hat. AuffĂ€llig an den Ergebnissen ist, dass die untersuchte Volkswirte sich deutlich stĂ€rker fĂŒr Deregulierungen und den RĂŒckbau des Staatseinflusses eingesetzt haben als fast alle Politiker. Politiker von der FDP waren dabei ĂŒblicherweise die grĂ¶ĂŸten DeregulierungsbefĂŒrworter, gefolgt von Unionspolitikern. AuffĂ€llig ist, dass es dabei durchaus Unionspolitiker gab, die sich fĂŒr einen stĂ€rkeren Staat eingesetzt haben als einzelne prominente Sozialdemokraten.The study examines public statements by German politicians and economic policy advisors on questions of deregulation. The period covered stretches from the former chancellor Gerhard Schröder's speech on the Agenda 2010 reform package in early 2003 until the beginning of the financial crisis in 2007. Based on the citations found, an index is created with which one can measure the degree of support for cutting back the government's influence on the economy. According to this index, economic policy advisors have been pushing much harder for deregulation than the large majority of German politicians. Among politicians, those of the FDP have been most in favor of cutting back the government's influence, followed by the CDU/CSU politicians. Interestingly, some of the CDU/CSU politicians have been less in favor of deregulation than prominent Social Democrats

    German Pig Farmers’ Attitudes Towards Farm Animal Welfare And Their Willingness To Participate In Animal Welfare Pro-grams: An Empirical Study

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    Many consumers express strong demands for higher farm animal welfare standards – especially in conventional livestock husbandry systems. This applies primarily to products from pork production, as consumers have recognized a quality decrease in recent years. Although pig farmers are key stakeholders for the implementation of animal welfare programs (AWPs) there is little evidence of their attitudes towards farm animal welfare (FAW) and AWPs. Thus, the main objective of this investigation was to investigate pig farmers’ attitudes towards FAW and AWPs and to determine target groups for participation in AWPs. Therefore, an explorative factor analysis and a hierarchical cluster analysis were applied. Three farmer groups were identified which significantly differ regarding their attitudes towards FAW and their willingness to participate in AWPs. This paper represents a starting point for the design of tailor-made strategies to increase the market penetration of AWPs

    Deregulierung in der öffentlichen Debatte in Deutschland

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    The study examines public statements by German politicians and economic policy advisors on questions of deregulation. The period covered stretches from the former chancellor Gerhard Schröder's speech on the Agenda 2010 reform package in early 2003 until the beginning of the financial crisis in 2007. Based on the citations found, an index is created with which one can measure the degree of support for cutting back the government's influence on the economy. According to this index, economic policy advisors have been pushing much harder for deregulation than the large majority of German politicians. Among politicians, those of the FDP have been most in favor of cutting back the government's influence, followed by the CDU/CSU politicians. Interestingly, some of the CDU/CSU politicians have been less in favor of deregulation than prominent Social Democrats.

    Introduction—Up, down, round and round: Verticalities in the history of science

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    History of science's spatial turn has focused on the horizontal dimension, leaving the role of the vertical mostly unexplored as both a condition and object of scientific knowledge production. This special issue seeks to contribute to a burgeoning discussion on the role of verticality in modern sciences, building upon a wider interdisciplinary debate about the importance of the vertical and the volumetric in the making of modern lifeworlds. In this essay and in the contributions that follow, verticality appears as a condition of knowledge production—a set of movements and mobilities, technical challenges, political negotiations, and bodily hardships—and an object of scientific inquiry, requiring new techniques of mapping and visualisation and generative of new insights into physical processes and temporal change. By foregrounding the vertical, historians of science can gain new insights and tell new stories about how science is done in the field, the observatory, and the laboratory, and about how those sciences have helped build a modern, three‐dimensional world
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