997 resultados para 027:347.78


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Fil: Viñas, Mariela. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Viñas, Mariela. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Viñas, Mariela. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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We report a near-continuous, stable isotopic record for the Pliocene-Pleistocene (4.8 to 0.8 Ma) from Ocean Drilling Program Site 704 in the sub-Antarctic South Atlantic (47°S, 7°E). During the early to middle Pliocene (4.8 to 3.2 Ma), variation in delta18O was less than ~0.5 per mil, and absolute values were generally less than those of the Holocene. These results indicate some warming and minor deglaciation of Antarctica during intervals of the Pliocene but are inconsistent with scenarios calling for major warming and deglaciation of the Antarctic ice sheet. The climate System operated within relatively narrow limits prior to ~3.2 Ma, and the Antarctic cryosphere probably did not fluctuate on a large scale until the late Pliocene. Benthic oxygen isotopic values exceeded 3 per mil for the first time at 3.16 Ma. The amplitude and mean of the delta18O signal increased at 2.7 Ma, suggesting a shift in climate mode during the latest Gauss. The greatest delta18O values of the Gaus anti Gilbert chrons occurred at ~2.6 Ma, just below a hiatus that removed the interval from ~2.6 to 2.3 Ma in Site 704. These results agree with those from Subantarctic Site 514, which suggest that the latest Gauss (2.68 to 2.47 Ma) was the time of greatest change in Neogene climate in the northern Antarctic and Subanthtic regions. During this period, surface water cooled as the Polar Front Zone (PFZ) migrated north and perennial sea ice Cover expanded into the Subantarctic region. Antarctic ice volume increased and the ventilation rate of Southern Ocean deep water decreased during glacial events after 2.7 Ma. We suggest that these changes in the Southern Ocean were related to a gradual lowering of sea level and a reduction in the flux of North Atlantic Deep Water (NADW) with the Initiation of ice growth in the northern hemisphere. The early Matuyama Chron (~ 2.3 to 1.7 Ma) was marked by relatively warm climates in the Southern Ocean except for strong glacial events associated with isotopic stages 82 (2.027 Ma), 78 (1.941 Ma), and 70 (1.782 Ma). At 1.67 Ma (stage 65/64 transition), surface waters cooled as the PFZ migrated equatorward and oscillated about a far northerly position for a prolonged interval between 1.67 and 1.5 Ma (stages 65 to 57). Beginning at ~1.42 Ma (stage 52), all parameters (delta18O, delta13C, %opal, %CaCO3) in Hole 704 become highly correlated with each other and display a very strong 41-kyr cyclicity. This increase in the importance of the 41-kyr cycle is attributed to an increase in the amplitude of the Earth's obliquity cycle that was likely reinforced by increased glacial suppression of NADW, which may explain the tightly coupled response that developed between the Southern Ocean and the North Atlantic beginning at ~1.42 Ma (stage 52).

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The introduction of pharmaceutical product patents in India and other developing countries is expected to have a significant effect on public health and local pharmaceutical industries. This paper draws implications from the historical experience of Japan when it introduced product patents in 1976. In Japan, narrow patents and promotion of cross-licensing were effective tools to keep drug prices in check while ensuring the introduction of new drugs. While the global pharmaceutical market surrounding India today differs considerably from that of the 1970's, the Japanese experience offers a policy option that may profitably be considered by India today. The Indian patent system emphasizes the patentability requirement in contrast to the Japanese patent policy which relied on narrow patents and extensive licensing. R&D by local firms and the development of local products may be promoted more effectively under the Japanese model.

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The introduction of pharmaceutical product patents in India and other developing countries is expected to have a significant effect on public health and local pharmaceutical industries. This paper draws implications from the historical experience of Japan when it introduced product patents in 1976. In Japan, narrow patents and promotion of cross-licensing were effective tools to keep drug prices in check while ensuring the introduction of new drugs. While the global pharmaceutical market surrounding India today differs considerably from that of the 1970's, the Japanese experience offers a policy option that may profitably be considered by India today. The Indian patent system emphasizes the patentability requirement in contrast to the Japanese patent policy which relied on narrow patents and extensive licensing. R&D by local firms and the development of local products may be promoted more effectively under the Japanese model.