931 resultados para Hard And Brittle Coating
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During fertilization in marine invertebrates, fusion between sperm and egg cell membranes occurs at the tip of the sperm acrosomal process. In abalone sperm the acrosomal process is coated with an 18-kDa protein. In situ, this protein has no effect on the egg vitelline envelope, but in vitro it is a potent fusagen of liposomes. Thus, the 18-kDa protein may mediate membrane fusion between the gametes, a step in gamete recognition known to restrict heterospecific fertilization in other species. The cDNA and deduced amino acid sequences of the 18-kDa protein were determined for five species of California abalone. The deduced amino acid sequences exhibit extraordinary divergence; the percent identity varies from 27% to 87%. Analysis of nucleotide substitution shows extremely high frequencies of amino acid-altering substitution compared to silent substitution, demonstrating that positive Darwinian selection promotes the divergence of this protein. However, amino acid replacement is conservative with respect to size and polarity of residue. The data support the developing idea that in free-spawning marine invertebrates, the proteins mediating fertilization may be subjected to intense, and as yet unknown, selective forces. The extraordinary divergence of fertilization proteins may be related to the establishment of barriers to heterospecific fertilization.
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The seventh round of the Transatlantic Trade and Investment Partnership (TTIP) negotiations between the European Union and the United States will take place in Washington on 29 September. If concluded successfully, the TTIP would become the world’s largest free trade pact. The EU and the US account for nearly half of the world’s GDP and 30% of world trade with exchanges of goods and services worth around €723 billion a year and €1.8 billion a day. The Partnership, unprecedented in its scope and ambition, has generated great expectations which will be hard to meet in reality. It could however have a beneficial effect on trade multilateralism, provided that it is the result of an open negotiating process.
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Russian President Vladimir Putin’s visit to Serbia on 16 October has demonstrated Moscow’s willingness to secure its interests in the Balkans and use Belgrade in its confrontation with the West. It seems, however, that Russia does not have much to offer to Serbia’s authorities, which are reluctant to make more concessions towards Russia. However, Moscow has already gained a strong position in Serbia, which is due to the country’s dependence on Russian natural resources and, in particular, strong support for Russian policy on the part of Serbian elites and society. The traditional pro-Russian attitudes have been strengthened as a result of a series of Russia-inspired, wide-ranging soft power initiatives which have proved so successful that a large part of society has begun to believe that Russia’s interests are consistent with Serbia’s. Russia’s increasingly active policy towards Serbia and the Serbian minorities in the neighbouring countries – Bosnia and Herzegovina, Montenegro and Kosovo – has been part of a larger plan aimed at hampering the integration of the Balkan states with the Euro-Atlantic structures and maintaining an area of instability and frozen conflicts in the EU’s near neighbourhood. Russia’s policy is also becoming increasingly effective due to the EU states’ diminishing support for Balkan countries’ European integration.
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Michelle Egan and Jacques Pelkmans provide an overview of the TBT chapter in TTIP and the various issues between the US and the EU in this area, which in turn requires extensive expositions of domestic regulation in the US and the EU. TBTs, outside heavily regulated sectors such as chemicals, automobiles or medicines (which have separate chapters in TTIP), can be caused by divergent (voluntary) standards, technical regulations and conformity assessment. Indeed, in all three the US and the EU have long experienced frictions with considerable trading costs. The 1998 Mutual Recognition Agreement about conformity assessment only succeeded in two out of six sectors. The US and European standardisation traditions differ and this paper explains why it is so hard, also economically, to realise convergence. However, the authors reject the unproductive ‘stand-off’ between US and EU negotiators on standardisation and suggest to clarify the enormous economic ‘installed base’ of prominent US standards in the world economy and build a solution from there. As to technical regulation, the prospect of converging regulation (via harmonisation) is often dim, but equivalence (given similar levels of regulatory protection) can be an option.
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"December 10, 1980."
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"This edition is limited to one thousand copies, of which this is ... no. three hundred and twenty-five."
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Mode of access: Internet.
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Includes music.
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Mode of access: Internet.