2,825 research outputs found

    Análisis evolutivo de cinco familias de briofitas empleando fósiles virtuales

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    Traditional taxa paraphyletic or polyphyletic on a molecular phylogenetic tree may be interpreted as populations of surviving ancestors that are evolutionarily static in expressed traits though labile in DNA traits used to track genetic continuity. In those cases in which re-evolution (convergence) of such taxa is deemed improbable, such heterophyly may be used to infer evolutionary series of virtual fossils reflecting macroevolution. Descent with modification of taxa is here demonstrated by reinterpreting published cladograms of molecular studies of Dicranaceae, Pottiaceae, Grimmiaceae, Hypopterygiaceae, and Mniaceae as taxon trees. Given this argument, superimposed inferred ancestors are support for the theory of punctuated equilibrium.Los táxones parafiléticos o polifiléticos tradicionales en un árbol molecular filogenético pueden interpretarse como poblaciones de ancestros supervivientes que están evolutivamente estáticos en los caracteres expresados a través de lábiles en los caracteres ADN que se emplean para seguir la continuidad genética. En esos casos en los cuales la re-evolución (convergencia) de tales táxones se considere improbable, la heterofilia puede usarse para inferir series evolutivas de fósiles virtuales que reflejan la macroevolución. El descenso con modificación de táxones se demuestra con la interpretación publicada de los cladogramas de estudios moleculares de Dicranaceae, Pottiaceae, Grimmiaceae, Hypopterygiaceae y Mniaceae como árboles taxonómicos. En vista de este argumento, resulta que los ancestros inferidos superimpuestos apoyan la teoría del equilibrio puntuado

    Exploring a Non-Minimal Sterile Neutrino Model Involving Decay at IceCube and Beyond

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    We study the phenomenology of neutrino decay together with neutrino oscillations in the context of eV-scale sterile neutrinos. We review the formalism of visible neutrino decay in which one of the decay products is a neutrino that potentially can be observed. We apply the formalism developed for decay to the recent sterile neutrino search performed by IceCube with TeV neutrinos. We show that for ν4\nu_4 lifetime τ4/m4≲10−16eV−1s\tau_4/m_4 \lesssim 10^{-16} {\rm eV^{-1}s}, the interpretation of the high-energy IceCube analysis can be significantly changed.Comment: 12 pages, 7 figures. Find code at: https://github.com/arguelles/nuSQUIDSDeca

    Computer-Aided Techniques as a Tool for the Integration of Industrial Processes

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    The main topics of this working paper are: (1) To roughly characterize the main processes of industrial systems by their essential features. (2) To point out the possibilities of rationalization of the main processes of industrial systems -- first of all by utilization of computers. (3) To sketch some methodological aspects of analysis and synthesis of industrial processes. (4) To recommend problems that could be investigated in IIASA in connection with the rationalization of Integrated Industrial Systems by utilization of computers. (5) To investigate the role of CAD techniques as a tool for the integration of industrial processes. The main objective of this working paper is to explain the problems and to fix the limits of the area to be discussed at the CAD conference at IIASA in November 1974. We shall not describe here state-of-the-art reports or solutions to the problems but will only point out the direction of possible research and various ideas which will be explained in some papers presented at the conference

    Leptodontium stellatifolium (Pottiaceae, Bryophyta) en la Isla Réunion, un rango de disyunción significativo

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    A species of mountainous regions of Latin America, Leptodontium stellatifolium, is reported from La Réunion Island in the Indian Ocean. This is a major geographic range disjunction. The species is illustrated and described from La Réunion material, and its considerable variation across its range and within La Réunion is discussed. Explanations of its distribution are suggested in terms of both ancient sky and ocean island spore dispersal, and recent, human-mediated introduction. We provide a key for species of Leptodontium occurring on La Réunion.Leptodontium stellatifolium (Pottiaceae, Bryophyta) en la Isla Réunion, un rango de disyunción significativo. Leptodontium stellatifolium, una especie de las regiones montañosas de América Latina, es registrada para La Réunion en el Océano Indico. Esta es una disyunción geográfica significativa. La especie es descrita e ilustrada y se discute su variación a lo largo del rango de distribución y dentro de la isla. Se sugiere que su distribución puede deberse a una dispersión antigua por aire y a través de las islas o bien fue recientemente introducida por el hombre. Se incluye una clave de las especies de Leptodontium en La Réunion

    Measurements of CH4, N2O, CO, H2O and O3 in the middle atmosphere by the ATMOS experiment on Spacelab 3

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    The volume mixing ratios of five minor gases (CH4, N2O, CO, H2O, and O3) were retrieved through the middle atmosphere from the analysis of 0.01/cm resolution infrared solar occultation spectra recorded near 28 N and 48 S latitudes with the ATMOS (Atmospheric Trace Molecule Spectroscopy) instrument, flown on board Spacelab 3. The results, which constitute the first simultaneous observations of continuous profiles through the middle atmosphere for these gases, are in general agreement with reported measurements from ground, balloon and satellite-based instruments for the same seasons. In detail, the vertical profiles of these gases show the effects of the upper and middle atmospheric transport patterns dominant during the season of these observations. The profiles inferred at different longitudes around 28 N suggest a near-uniform zonal distribution of these gases. Although based on fewer observations, the sunrise occultation measurements point to a larger variability in the vertical distribution of these gases at 48 S
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