3,776 research outputs found

    On the Decades-Long Stability of the Interstellar Wind through the Solar System

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    We have revisited the series of observations recently used to infer a temporal variation of the interstellar helium flow over the last forty years. Concerning the recent IBEX-Lo direct detection of Helium neutrals, there are two types of precise and unambiguous measurements which do not rely on the exact response of the instrument: the count rate maxima as a function of the spin angle, which determines the ecliptic latitude of the flow, and the count rate maxima as a function of IBEX longitude, which determines a tight relationship between the ecliptic longitude of the flow and its velocity far from the Sun. These measurements provide parameters (and couples of parameters in the second case) remarkably similar to the canonical, old values. In contrast, the preferential choice of a lower velocity and higher longitude reported before from IBEX data is based only on the count rate variation (at each spin phase maximum) as a function of the satellite longitude, when drifting across the region of high fluxes. We have examined the consequences of dead time counting effects, and conclude that their inclusion at a realistic level is sufficient to reconcile the data with the old parameters, calling for further investigations. We discuss the analyses of the STEREO pickup ion (PUI) data and argue that the statistical method that has been preferred to infer the neutral flow longitude (instead of the more direct method based on the PUI maximum flux directions), is not appropriate. Moreover, transport effects may have been significant at the very weak solar activity level of 2007-2009, in which case the longitudes of the PUI maxima are only upper limits on the flow longitude. Finally, we found that the use of some flow longitude determinations based on UV glow data are not adequate. At variance with recent conclusions we find no evidence for a temporal variability of the interstellar helium flow.Comment: 8 pages, 3 figures, accepted for publication in Astronomy and Astrophysic

    Mining Complex Hydrobiological Data with Galois Lattices

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    We have used Galois lattices for mining hydrobiological data. These data are about macrophytes, that are macroscopic plants living in water bodies. These plants are characterized by several biological traits, that own several modalities. Our aim is to cluster the plants according to their common traits and modalities and to find out the relations between traits. Galois lattices are efficient methods for such an aim, but apply on binary data. In this article, we detail a few approaches we used to transform complex hydrobiological data into binary data and compare the first results obtained thanks to Galois lattices

    Observation of Lyman-alpha emission in interplanetary space

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    The extraterrestrial Lyman-alpha emission was mapped by the OGO 5 satellite, when it was outside the geocorona. Three maps, obtained at different periods of the year, are presented and analyzed. The results suggest that at least half of the emission takes place in the solar system, and give strong support to the theory that in its motion toward the apex, the sun crosses neutral atomic hydrogen of interstellar origin, giving rise to an apparent interstellar wind

    Reproduce or perish? The artefact of the fertility ; concept and the French School of Demography

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    "This article investigates the complicated and intertwined history between the scientific discipline of demography, the depopulation debate and the pronatalist lobby, and French republican policies from the late nineteenth century till the eve of the Second World War. The authoress suggests that central to this history is the concept and codification of fertility." (author's abstract

    Semantic HMC for Big Data Analysis

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    Analyzing Big Data can help corporations to im-prove their efficiency. In this work we present a new vision to derive Value from Big Data using a Semantic Hierarchical Multi-label Classification called Semantic HMC based in a non-supervised Ontology learning process. We also proposea Semantic HMC process, using scalable Machine-Learning techniques and Rule-based reasoning

    Toward a Theory of the Arts and Sustainability

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    To make real progress on what can only be classified as environmental emergencies, we need a wide base of public consensus for action given that public motivation and involvement is a prerequisite for policymakers to implement what our scientists urge us to do. In this light, crucial thresholds of public motivation and involvement can be created by reaching into the hearts of individuals, an area of competitive advantage for the arts. Efforts to enhance understanding in this arena, however, must incorporate sufficient complexity given highly complex and inter-related challenges in sustainability. This article thus presents a theoretical framework for the arts and sustainability based on the variables of artistic complexity and public engagement. The arts, when allowed sufficient scope and freedom, can assist society in marshalling and galvanizing people across the globe to take essential steps toward a sustainable planet

    Demographic Knowledge, ‘Race Suicide’ and the Making of Racial Jews in Interwar Europe

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    This essay takes a critical stance on the category of demographic engineering. I regard demographic engineering as naturalizing the connection between population, territory and security eschewing both the modern edge of the concept of population and its power effect. My argument is that the connection between security and population that is underlying demographic engineering is not a ‘natural’ behavior of ‘populations’ but an artefact of demographic knowledge that can be traced back to interwar Europe when the population/security nexus was reformulated in the light of ‘race suicide,’ ‘depopulation’ and the making of racial Jews. Demographic engineering is a loaded category that obfuscates how demographic knowledge constitutes populations to make them available to political intervention it calls for as a necessity
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