¿Fue Ovidio un poeta latino de la Edad de Plata?

Este artículo busca establecer cómo las características más sobresalientes de las Metamorfosis de Ovidio, consideradas por muchos estudiosos como el modelo por excelencia de los poetas latinos del siglo I d.C. no resultan tan influyentes en la praxis poética de los autores neronianos y flavianos. Aun considerando los numerosos paralelismos formales y estilísticos existentes en estos autores, tal como el uso de la paradoja, la sobreexplicitación visual y la acumulación de detalles, resulta claro que el propósito y el uso de los diferentes topoi literarios que estos poetas hacen son completamente distintos. Un análisis de los motivos de la nekya y la tempestad en Ovidio, Lucano, Silio Itálico, Valerio Flaco y Estacio muestra cuánto más a menudo los poetas latinos del siglo I d.C. recurren a la obra de Virgilio que a la de Ovidio

A cultura escolar da educação física no EJA : O paradoxo entre a ruptura com a noção de atividade e a falta da prática corporal

This paper is the result of a research based on the school culture concept, which object is the specific school culture of the physical education (PE) within a school for youth and adults situated in Curitiba - PR. Methodologically we followed the principles and concepts of the ethnomethodology, that led us to a long immersion in the research field. The main results of the research show the relevance of the teacher identity for constituting the school culture of the PE, as well the paradox resulting of a mere theoretical approach: on the one hand this school culture show us the importance of the disruption with the PE's tradition based on the notion of "activity", and on the other hand reveal the necessity of the body experience as a fundament to build a theoretical construct

Planktic and benthic foraminifreral isotope data for ODP Site 207-1258

The mid-Cretaceous is widely considered the archetypal ice-free greenhouse interval in Earth history, with a thermal maximum around Cenomanian-Turonian boundary time (ca. 90 Ma). However, contemporaneous glaciations have been hypothesized based on sequence stratigraphic evidence for rapid sea-level oscillation and oxygen isotope excursions in records generated from carbonates of questionable preservation and/or of low resolution. We present new oxygen isotope records for the mid-Cenomanian Demerara Rise that are of much higher resolution than previously available, taken from both planktic and benthic foraminifers, and utilizing only extremely well preserved glassy foraminifers. Our records show no evidence of glaciation, calling into question the hypothesized ice sheets and rendering the origin of inferred rapid sea-level oscillations enigmatic. Simple mass-balance calculations demonstrate that this Cretaceous sea-level paradox is unlikely to be explained by hidden ice sheets existing below the limit of d18O detection.

Stable isotope record of Cretaceous samples of DSDP Hole 71-511

Oxygen isotope data for upper Turonian planktonic foraminifera at Deep Sea Drilling Project Site 511 (Falkland Plateau, 60°S paleolatitude) exhibit an ~2 per mil excursion to values as low as -4.66 per mil (Vienna Peedee belemnite standard; PDB) coincident with the warmest tropical temperature estimates yet obtained for the open ocean. The lowest planktonic foraminifer d18O values suggest that the upper ocean was as warm as 30-32°C. This is an extraordinary temperature for 60°S latitude but is consistent with temperatures estimated from apparently coeval mollusc d18O from nearby James Ross Island (65°S paleolatitude). Glassy textural preservation, a well-defined depth distribution in Site 511 planktonics, low sediment burial temperature (~32°C), and lack of evidence of highly depleted pore waters argue against diagenesis (even solid state diffusion) as the cause of the very depleted planktonic values. The lack of change in benthic foraminifer d18O suggests brackish water capping as the mechanism for the low planktonic d18O values. However, mixing ratio calculations show that the amount of freshwater required to produce a 2 per mil shift in ambient water would drive a 7 psu decrease in salinity. The abundance and diversity of planktonic foraminifera and nannofossils, high planktonic:benthic ratios, and the appearance of keeled foraminifera argue against lower-than-normal marine salinities. Isotope calculations and climate models indicate that we cannot call upon more depleted freshwater d18O to explain this record. Without more late Turonian data, especially from outside the South Atlantic basin, we can currently only speculate on possible causes of this paradoxical record from the core of the Cretaceous greenhouse.

Age model for ODP Leg 175 sites

Upwelling along the western coast of Africa south of the equator may be partitioned into three major areas, each having its own dynamics and history: (1) the eastern equatorial region, comprising the Congo Fan and the area of Mid-Angola; (2) the Namibia upwelling system, extending from the Walvis Ridge to Lüderitz; and (3) the Cape Province region, where upwelling is subdued. The highest nutrient contents in thermocline waters are in the northern region, the lowest in the southern one. Wind effects are at a maximum near the southern end of the Namibia upwelling system, and maximum productivity occurs near Walvis Bay, where the product between upwelling rate and nutrient content of upwelled waters is at a maximum. In the Congo/Angola region, opal tends to follow organic carbon quite closely in the Quaternary record. However, organic carbon has a strong precessional component, while opal does not. Despite relatively low opal content, sediments off Angola show the same patterns as those off the Congo; thus, they are part of the same regime. The spectrum shows nonlinear interference patterns between high- and low-latitude forcing, presumably tied to thermocline fertility and wind. On Walvis Ridge, as in the Congo-Angola region, the organic matter record behaves normally; that is, supply is high during glacial periods. In contrast, interglacial periods are favorable for opal deposition. The pattern suggests reduction in silicate content of the thermocline during glacial periods. The reversed phase (opal abundant during interglacials) persists during the entire Pleistocene and can be demonstrated deep into the Pliocene, not just on Walvis Ridge but all the way to the Oranje River and off the Cape Province. From comparison with other regions, it appears that silicate is diminished in the global thermocline, on average, whenever winds become strong enough to substantially shorten the residence time of silicate in upper waters (Walvis Hypothesis, solving the Walvis Paradox of reversed phase in opal deposition). The central discovery during Leg 175 was the documentation of a late Pliocene opal maximum for the entire Namibia upwelling system (early Matuyama Diatom Maximum [MDM]). The maximum is centered on the period between the end of the Gauss Chron and the beginning of the Olduvai Chron. A rather sharp increase in both organic matter deposition and opal deposition occurs near 3 Ma in the middle of the Gauss Chron, in association with a series of major cooling steps. As concerns organic matter, high production persists at least to 1 Ma, when there are large changes in variability, heralding subsequent pulsed production periods. From 3 to 2 Ma, organic matter and opal deposition run more or less parallel, but after 2 Ma opal goes out of phase with organic matter. Apparently, this is the point when silicate becomes limiting to opal production. Thus, the MDM conundrum is solved by linking planetary cooling to increased mixing and upwelling (ramping up to the MDM) and a general removal of silicate from the upper ocean through excess precipitation over global supply (ramping down from the MDM). The hypothesis concerning the origin of the Namibia opal acme or MDM is fundamentally the same as the Walvis Hypothesis, stating that glacial conditions result in removal of silicate from the thermocline (and quite likely from the ocean as a whole, given enough time). The Namibia opal acme, and other opal maxima in the latest Neogene in other regions of the ocean, marks the interval when a cooling ocean selectively removes the abundant silicate inherited from a warm ocean. When the excess silicate is removed, the process ceases. According to the data gathered during Leg 175, major upwelling started in the late part of the late Miocene. Presumably, this process contributed to the drawing down of carbon dioxide from the atmosphere, helping to prepare the way for Northern Hemisphere glaciation.

Radiogenic isotope trace composition of the Labrador Sea

Geological reconstructions and general circulation models suggest that the onset of both Northern Hemisphere glaciation, 2.7 Myr ago, and convection of Labrador Sea Water (LSW) were caused by the closure of the Panama Gateway ~4.5 Myr ago. Time series data that have been obtained from studies of ferromanganese crusts from the northwestern Atlantic suggest that radiogenic isotopes of intermediate ocean residence time (Pb and Nd) can serve as suitable tracers to reconstruct these events. However, it has been unclear until now as to whether the changes that have been observed in isotope composition at this time are the result of increased thermohaline circulation or due to the effects of increased glacial weathering. In this paper we adopt a box model approach to demonstrate that the shifts in radiogenic isotope compositions are unlikely to be due to changes in convection in LSW but can be explained in terms of increases of erosion levels due to the glaciation of Greenland and Canada. Furthermore, we provide experimental evidence for the incongruent release of a labile fraction of strongly radiogenic Pb and nonradiogenic Nd from continental detritus eroding into the Labrador Sea. This can be attributed to the glacial weathering of old continents and accounts for the paradox that one of the areas of the world most deficient in radiogenic Pb should provide such a rich supply of radiogenic Pb to the oceans. An important general conclusion is that the compositions of radiogenic isotopes in seawater are not always a reflection of their continental sources. Perhaps more importantly, the transition from chemical weathering to mechanical erosion is likely to result in significant variations in radiogenic tracers in seawater.

Oxygen isotope composition of planktonic foraminifer Globigerinoides ruber in sediment core GeoB1413 from the eastern edge of the South Atlantic central gyre

Die Paläozeanographie versucht die Klimageschichte des Quartärs zu rekonstruieren und die Zusammenhänge zwischen Klimaänderungen und ozeanischer Zirkulation besser zu verstehen. Ein wichtiges Hilfsmittel stellen die planktischen Foraminiferen dar. Die Analyse planktischer Foraminiferengemeinschaften hat gezeigt, daß die Verbreitung dieser Protozoa durch die Umweltbedingungen in den Oberflächenwasserströmen bestimmt wird (BoLTOVSKOY, 1969; CIFELLI& BENIER, 1976; OTIENS, 1991). Durch ihre Ablagerung und Erhaltung am Meeresboden speichern sie diese Informationen und bilden einen Indikator für Wassermassen und Oberflächenwassertemperaturschichtung. Zeitliche und räumliche Veränderungen der Faunenvergesellschaftungen und der Verhältnisse stabiler Sauerstoff- und Kohlenstoffisotope einzelner Foraminiferenarten haben damit einen maßgeblichen Beitrag zur Kenntnis der spätquartären Temperatur- und Zirkulationsänderungen der Oberflächenströme geliefert (SHACKLETON & OPDYKE, 1973; BE et al., 1976; RUDDIMAN & McooYRE, 1976; VINCENT & BERGER, 1981; CLIMAP, 1981; RA VELO et al., 1990). Mit Hilfe der planktischen Foraminiferen soll diese Arbeit einen Beitrag zur Rekonstruktion der spätquartären Ozeanographie des Südatlantiks liefern. Die Oberflächenströme des Südatlantiks sind das Bindeglied im Wärmeaustausch zwischen niederen und hohen Breiten. Durch den Südäquatorialstrom (SEC) werden warme Wassermassen, die sich aufgrund der hohen Sonneneinstrahlung im tropischen Atlantik gebildet haben, in den Nordatlantik transportiert. Die Wärme wird im Nordatlantik unter Bildung des Nordatlantischen-Tiefenwassers (NADW) an die Atmosphäre abgegeben. Durch dieses Ereignis wird maßgeblich das nordeuropäische Klima beeinflußt (BROECKER & DENTON, 1989). Die Intensität des SEC wird durch den saisonal variierenden SE-, NE-Passat gesteuert, der hauptsächlich durch die Präzession der geneigten Erdachse bzw. durch die Insolation auf der Nordhalbkugel kontrolliert wird (Mc OOYRE et aI., 1989; MOLFINO & Mc INTYRE, 1990). Der SEC fließt entlang des Äquators von Ost nach West und kalte, nährstotfreiche, tiefere Wassermassen (Südatlantisches-Zentralwasser (SACW)) steigen vor allem im Osten auf und erzeugen das hochproduktive äquatoriale Auftriebsgebiet. Im Osten ist der Temperaturgradient in der Wassersäule steiler, und die Thermoklinentiefe nimmt von Ost nach West zu. Die Lage der Thermokline ist damit ein wesentlicher Faktor, der den Wärmehaushalt im Atlantik mitbestimmt. So wird z. B. im äquatorialen Auftriebsgebiet und im Auftriebsgebiet des küstennahen Benguela-Stroms, wo die Thermoklinentiefe durch aufsteigende kalte Wassermassen gering ist, eine Wärmezunahme von 100 W/qm im Wärmehaushalt erreicht (PETERSON & STRAMMA, 1991). Zur spätquartären Rekonstruktion des Wärmeflusses und der Oberflächenzirkulation im Südostatlantik ist es daher wichtig, auch die zeitlichen und räumlichen Veränderungen tieferer Wasserschichten (bis 300 m) zu erfassen.

Age models for ODPO Leg 130 sites

The Neogene carbonate stratigraphy of five sites drilled on Ontong Java Plateau during Leg 130 reveals a number of patterns which are unexpected, and which we refer to as loss paradox, equatorial insensitivity, and climate paradox. They denote the following unresolved questions. 1 The loss of carbonate at depth (as derived from differences in accumulation rates) is much greater than suggested by the change in carbonate percentages (calculated under the assumption that carbonate dissolution is the cause of loss). This indicates an important role for redeposition processes, such as winnowing (bottom currents), sifting (resuspension and catabatic flow) and episodic sloughing or solifluction (presumably stimulated by earthquakes). 2 Accumulation rates are not markedly increased at the time a site crosses the equator. There are several possible reasons. Equatorial upwelling may be unimportant in controlling sedimentation rates this far in the western Pacific, or its output may be spread over a considerable distance from the equator. Alternatively, increased supply below the equator is compensated for by increased removal (e.g. from resuspension by bioturbation, combined with catabatic flow). It is conceivable that errors in the timescale could also produce the effect seen. 3 There is an overall tendency for agreement between the stratigraphic patterns of carbonate content and of accumulation rates, but neither pattern is readily explained by reference to changes in climate (represented by benthic delta18O) or in sea-level (as derived from sequence stratigraphy).

Abundance and biomass of planktonic diatom Proboscia alata and associated species, chlorophyll a, organic carbon and nitrogen concentrations in waters over the Bering Sea middle shelf in August 2001

During most of the vegetation season from late May to early September large-sized diatom alga Proboscia alata forms local patches with high abundances and biomasses in different oceanographic domains of the eastern Bering Sea shelf. For 0-25 m layer average abundance and biomass of species in these patches are 700000 cells/l and 5 g/m**3 (wet weight), while corresponding estimates for the layer of maximal species concentrations are 40000000 cells/l and 38 g/m**3 (wet weight) or 1.6 g C/m**3. These levels of abundance and biomass are typical for the spring diatom bloom in the region. Outbursts of P. alata mass development are important for the carbon cycle in the pelagic zone of the shelf area in the summer season. The paradox of P. alata summertime blooms over the middle shelf lies in their occurrences against the background of the sharp seasonal pycnocline and deficiency in nutrients in the upper mixed layer. Duration of the outbursts in P. alata development is about two weeks and size of patches with high abundances can be as large as 200 km across. Degradation of the P. alata summertime outbursts may occur during 4-5 days. Rapid sinking of cells through the seasonal pycnocline results in intense transport of organic matter to bottom sediments. One of possible factors responsible for rapid degradation of the blooms is affect on the population by ectoparasitic flagellates. At terminal stages of the P. alata blooms percentage of infected cells can reach 70-99%.

Benthic stable oxygen and stable carbon isotopes records from the sub-Antarctic Atlantic over several glacial-interglacial transitions

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Development strategy in Bihar through revitalizing the agricultural sector : a preliminary analysis

Based mainly on secondary data and partly on primary information obtained through field surveys in selected rural areas in Bihar in 2011, this paper firstly argues the critical importance of agricultural growth for overall economic development, and then reviews the sluggish growth of agriculture in Bihar in the past and examines the major reasons for this. The long-term negligence of agricultural research (especially development and diffusion endeavors for improved rice varieties suitable to the local conditions of Bihar) by the state government and some sort of ‘backwardness’ in tube-well irrigation technology can be pointed out as important constraints. There is, in particular, the ‘paradox’ in Bihar agriculture of why rice and wheat yields have remained so low in spite of the relatively well-developed irrigation by tube-wells. Finally, by showing the process of a rapid increase in autumn and winter rice yields during the 1990s in West Bengal, it is suggested that Bihar farmers and policy-makers should learn from the experience of West Bengal in order to get some hints for the development of the rice sector in Bihar.