980 resultados para Siglo 15º-20º


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In recent decades wild boar have greatly increased in Europe due a combination of environmental and human factors. Because of a high reproduction rate, wild boar cause conflicts with human activities and in particularly agriculture. However, there are concerns also about environmental impact and in particular on ground nesting birds. Our study aim to evaluate the potential impact of wild boar on pheasants nests. Predation rates were compared between two areas with different wild boar abundance and between nests placed in fenced plots with no wild boar access (but accessible to other predators) and open plots in which the wild boar gains access. Predation rate by wild boar in the area with higher wild boar abundance was 61.5% whereas in the area with lower abundance was 16.0%. In plots with free access, wild boar predation was 34.2% whereas in exclusion plots we did not registered predation by wild boar. Moreover, wild boar resulted the main nest predator (total loss 22.8%). Our findings suggest that wild boar could have e strong impact on pheasant reproductive success.

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A new chemical procedure for cleaning marine carbonates was applied to remove detritus as well as metaloxide contaminations of marine shells from Eemian deposits and adjoining succession of a sediment core from Dagebüll, Schleswig- Holstein. Hence, one can significantly reduce the contamination with detrital uranium and thorium. Thermal ionisation mass spectrometry was applied to determine the uranium and thorium activities used for 230Th/U dating of these shells. At least ten samples of marine bivalves of five different core sections were analysed. Samples located below a five meter thick clay layer at 19-24 m yielded an average age of 132±18 ka. Shells located above the clays at 15-20 m depth were strongly influenced by percolating groundwaters of an open system. Therefore, a reliable dating of these samples was not possible.

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Carbon dioxide, ammonia, and reactive phosphate in the interstitial water of three sediment cores of the West African continental margin result from oxidation of sedimentary organic matter by bacterial sulfate reduction. The proposed model is a modification of one initially suggested by Richards (1965) for processes in anoxic waters: (CH2O)106 (NH3)8 (H3PO4) (0.7-0.2) + 53 SO4**2- =106 CO2 + 106 H20 + 8 NH3 + (0.7 - 0.2) H3PO4 + 53 S**2- The amount of reduced interstitial sulfate, the carbon-to-nitrogen-to-phosphorus atomic ratio of the sedimentary organic matter, as well as small amounts of carbon dioxide, which precipitated as interstitial calcium carbonate, are included in the general oxidation-reduction reaction. Preferential loss of nitrogen and phosphorus from organic matter close to the surface was recorded in both the interstitial water and sediment composition. It appeared that in deeper sections of the core organic carbon compounds were oxidized which were probably in an even lower oxidation state than that indicated by the proposed model. An estimated 2 % of the amount of organic matter still present was oxidized after it became incorporated into the sediment; whereas sulfide sulfur contents indicate that a much larger percentage (15-20%) seemed to have been subject to bacterial oxidation during the Pleistocene period, when a very thin oxidizing layer on the sediment allowed the above decomposition process to start relatively early favoured by almost fresh organic matter, and by almost unrestricted exchange of sulfate with the overlying water.

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The state of consolidation of outer Bengal Fan deposits is closely related to their depositional history. Early Pleistocene sediments are underconsolidated, i.e., fabric strength is lower than under equilibrium with the present overburden stress, at depths greater than 60-80 mbsf. This may be due to rapid accumulation (>15-20 cm/k.y.) and overlying low-permeability (<10**-7 cm/s) deposits. The underlying Pliocene sediments are overconsolidated, i.e., fabric strength is higher than in equilibrium with the present overburden stress; at Sites 717 and 719 the sediments are slightly overconsolidated, whereas at Site 718 the overconsolidation is significant. Overconsolidation is explained by erosion that occurred during the early Pleistocene for which a stratigraphic gap was recorded in the drilled cores. The eroded section is estimated to be in the range of 10-40 m at Sites 717 and 719, respectively, and 130-150 m at Site 718. Below 250-300 mbsf the most sediments are normally consolidated. The amount of erosion seems to be related to block rotation and uplift due to intraplate deformation.

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Vols. 1-2, 5-11, 15-20 edited by A. Crampon; v.3-4, 12-14, 21-23, edited by J.M Péronne.

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Ser. 1-3 (op. 15-20, 24, 25, 33, 40, 44, 45, 69-72, 74, 75)

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Index B: Table chronologique des ordonnances des rois de France de la troisième race jusqu'au règne de Louis XII inclusivement, suivie d'une table alphabétique pour en faciliter l'usage, par J. M. Pardessus ... . Paris, Imprimerie royale, 1847. 2 p. l., viii, 607 p. 40 cm.

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At head of title: Department of Commerce.

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Vols. 5-14 called n.F., 1.-10. Jahrg.; v. 15-20 called also n.F., 11.-16. Jahrg.

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"Reflexions sur les avantages qui résulten du Plan de M. de Forge" pp. 15-20.

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1.-2. bdchen. Selbstbiographie.--3.-14. bdchen. Dramatische dichtungen: 1. Baldur der gute. Helge. 2. Stärkodder. Hagbarth und Signe. 3. Palnatoke. Hakon Jarl. 4. Olaf der hoilige. Die Wäringer in Konstantinopel. 5. Axel und Walburg. Erich und Abel. 6. Correggio. Hugo von Rheinberg. 7. Sokrates. Der hirtenknabe. 8.-9. Aladdin; oder, Die wunderlampe. 10. Die fischerstochter. 11. Die drillingbrüder von Damask. 12. Der kleine schauspieler. Ludlam's höhle.--15.-20. bdchen. Erzählende dichtungen: 1-4. Die inseln im südmeere. 5. König Hroar. 6. Novellen und mährchen.--21. bdchen. Gedichte.

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Edited by the Commercial Department of the Board of Trade from Apr. 1893 to Oct. 1916.

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2 v. 23 cm.