El argumento de 'Lo Uno sobre lo múltiple' en el Tratado sobre las Ideas de Aristóteles

En este trabajo procuramos ofrecer, en primer lugar, un análisis del argumento de lo uno sobre lo múltiple presente en el tratado Sobre las Ideas de Aristóteles, con el fin de determinar las diferencias entre la Idea platónica y el universal aristotélico. En segundo lugar, nos preguntamos acerca de la validez de la reconstrucción aristotélica de los argumentos platónicos y sostenemos que hay indicios en los diálogos que nos permiten concluir que Aristóteles no traiciona el pensamiento de Platón. Por último, subrayamos que el examen crítico al que somete los argumentos es relevante, no sólo para establecer la distinción entre la Idea platónica y el universal aristotélico, sino también para establecer los aspectos de su propio pensamiento que permanecen deudores de las doctrinas platónicas

Biocombustibles en Argentina, Brasil y Colombia : Avances y limitaciones

Los biocombustibles introducen espacios agrícolas en la producción energética. Luego modifican la gobernanza de las redes energéticas y de los territorios productivos. Las principales críticas a los biocombustibles se dirigen a su producción a partir de cultivos tradicionales, pero interesa preguntarse también sobre la sostenibilidad de su producción a partir de cultivos alternativos, que no competirían con los cultivos alimentarios, puesto que se ubicarían en regiones agrícolas marginales. El texto trata sobre las producciones de biocombustibles de los países de América del Sur, en sus contextos internacionales, nacionales y locales. Se profundiza la mirada sobre Argentina, Brasil y Colombia, líderes continentales en el sector. Se analizan la evolución del mercado energético, los actores involucrados y las políticas implementadas. A otra escala, se plantea la puesta en marcha de las cadenas de biocombustibles alternativos.

The 'Philosophical paintings' of the Republic

En el presente artículo examino la apropiación platónica del lenguaje poético en República y sostengo que, a pesar de sus críticas a la poesía en los libros 3 y 10, el lenguaje poético está correctamente entrelazado dentro del tejido filosófico para pintar lo corrupto, lo feo y lo inmoral. En términos específicos, la adaptación platónica de diversos motivos poéticos e imágenes en República se vuelve más significativa si prestamos atención a Sócrates como un quasi-pintor en el diálogo e interpretamos sus imágenes filosóficas como una respuesta de la filosofía a las engañosas representaciones dramáticas de la poesía. De este modo, el arte de la pintura que, incluso es criticado en el libro 10 de República, en manos de Platón resulta una herramienta filosófica que le permite investigar la relación de nuestro mundo senso-perceptivo ordinario con el campo metafísico de las Ideas y el lugar de lo humano en él

Neogene benthic foraminiferal faunas of a southwest Pacific bathyal depth transect

Temporal changes in benthic foraminiferal assemblages were quantitatively examined (> 63 µm fraction) in four southwest Pacific deep-sea Neogene sequences in a depth transect between approximately 1300 and 3200 m to assist in evaluating paleoeeanographic history. The most conspicuous changes in benthic foraminiferal assemblages occurred in association with paleoclimatic changes defined at least in part by oxygen isotopic changes. The largest, centered at ~15 Ma (early Middle Miocene), is represented by an increase in the relative frequencies of Epistominella exigua, which underwent a major upward depth migration at that time. This was contemporaneous with the well-known positive oxygen isotopic shift in the early Middle Miocene. In Sites 588 and 590, most of the increase in relative abundances of E. exigua occurred during the middle to later part of the ~80 shift, following major growth of the east Antarctic ice sheet. Later assemblage changes occurred at 8.5 and 6.5 Ma. These associations indicate that the benthic foraminiferal assemblages in this depth transect largely adjusted to changes in deep waters related to Antarctic cryospheric evolution. In general, the Neogene benthic foraminiferal assemblages in this region underwent little change during the last 23 million years. This faunal conservatism suggests that deep-sea environments underwent relatively little change in the southwest Pacific during much of the Neogene. Although paleoceanographic changes did occur, partly in response to highlatitude cryospheric evolution, these were not of sufficient magnitude to create major deep-sea faunal changes in this part of the ocean. The benthic foraminiferal assemblages are dominated by individuals smaller than 150 µm. Most taxonomic turnover occurred in the larger (> 150 µm) size fractions.

Highly dealkylated copper and nickel etioporpyfrins in marine sediments

Copper porphyrins have been recognized as natural constituents of marine sediments only within the past 5 years (Palmer and Baker, 1978, Science201, 49-51). In that report it was suggested that these pigments may derive from and be markers for oxidized terrestrial organic matter redeposited in the marine environment. In the present study we describe the distribution of copper porphyrins in sediments from several north Pacific and Gulf of California DSDP/IPQD sites (Legs 56,63,64). These allochthonous pigments have now been found to be accompanied by identical arrays of highly dealkylated nickel etioporphyrins. Evaluation of data from this and past studies clearly reveals that there is a strong carbon-number distribution similarity betweeen coincident Cu and Ni etioporphyrins. This homology match is taken as reflecting a common source for the tetrapyrrole ligands of this population of Cu and Ni chelates. Predepositional generation of these highly dealkylated etioporphyrins is concluded from the occurrence of these pigments in sediments continuing essentially all stages of in situ chlorophyll diagenesis (cf. Baker and Louda, 1983). That is, their presence is not regulated by the in situ diagenetic continuum. Thus, the highly dealkylated Cu and Ni etioporphyrins represent an 'allochthonous' background over which 'autochthonous' (viz. marine produced) chlorophyll derivatives are deposited and are undergoing in situ diagenesis.

Ostracoda fauna of surface sediments from the Persian Gulf

During the "Meteor"-Expedition to the Persian Gulf in March-May 1965, approximately 300 samples were collected. Most of them have been already studied by various authors in sedimentological as well as micropaleontological respects. 49 samples were selected for ostracode studies. These samples are arranged to form a long-axis section ("Laengsprofil"), and 4 shorter cross-profiles, perpendicular to the long-axis profile in the Persian Gulf and Gulf of Oman. 52 species of ostracodes in this area were specifically determined; 39 of them are described under open nomenclature. 13 species are already known from surrounding sea areas: 2 species from the Red Sea; 2 species from the east coast of Africa; 1 species from the Mediterranean Sea; and others from the Indian and Pacific Oceans. 12 species show close relationships to species from the Indopacific Ocean. The ostracode species found in the area can be grouped after the method of BRAUN-BLANQUT into 2 bioassociations. Association 1 with the following 4 characteristic species : Cytherella cf. pulchra, Loxoconcha sp. A, Neomonoceratina sp. A, Alocopocythere reticulata. Association 2 with 1 characteristic species: Ruggieria (Ruggieria) sp. B. The association 1 is widespread in the entire studied area of the Persian Gulf, where it is considered to characterize the shallow water region down to 200 m. The association 2 is restricted to the deeper water below 200 m of the inner part of the Oman Gulf. Only a few species known from the shallow water association of the Persian Gulf are present. Within the two ostracode associations mentioned above 4 zones from the total studied area could be related to the water depth. The zones A-D are characterized more or less readily by the relative abundance of certain species: Zone A : 7-30 m depth, on substrates of poorly coarse-grained clayey marl; Zone B: 30-94 m depth, on substrates of richly coarse-grained calcareous marl; Zone C: 94-1961208 m depth, on substrates of richly coarse-grained calcareous marl; Zone D: 196/208-500 m depth, on substrates of calcareous clay, poor in benthos. The regional and bathymetric distribution of the ostracode fauna in the area studied was compared in relation to 10 environmental factors: water depth, temperature, salinity, water density, O2-concentration, phosphate-silica contents, pH-values, stratification of the water body, water currents and type of sediments. The major environmental factors which appear to control the ostracode distribution are water depth (as a complex factor), O2-concentration and the type of sediment. At 3 stations (GIK01058, GIK01074 and GIK01204) species of the shallow water association were found together with a few bathyal species. These stations are situated at the outer Biaban shelf, in an area where the bottom water of the Persian Gulf flows down the slope towards the Oman Gulf. Several samples of the Zone B in the major part of the Persian Gulf show also a high species diversity containing a high percentage of subfossil ostracode carapaces. It is probable that the recent biocoenosis has been mixed with a late quarternary thanatocoenosis.

Cronica generale d'Hispagna et del regno di Valenza...

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