975 resultados para WEAK FERROMAGNETISM


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A (II,Mn)VI diluted magnetic semiconductor quantum dot with an integer number of electrons controlled with a gate voltage is considered. We show that a single electron is able to induce a collective spontaneous magnetization of the Mn spins, overcoming the short range antiferromagnetic interactions, at a temperature order of 1 K, 2 orders of magnitude above the ordering temperature in bulk. The magnetic behavior of the dot depends dramatically on the parity of the number of electrons in the dot.

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Ferromagnetism is predicted in undoped diluted magnetic semiconductors illuminated by intense sub-band-gap laser radiation . The mechanism for photoinduced ferromagnetism is coherence between conduction and valence bands induced by the light which leads to an optical exchange interaction. The ferromagnetic critical temperature TC depends both on the properties of the material and on the frequency and intensity of the laser and could be above 1K.

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This paper proposes a new feature representation method based on the construction of a Confidence Matrix (CM). This representation consists of posterior probability values provided by several weak classifiers, each one trained and used in different sets of features from the original sample. The CM allows the final classifier to abstract itself from discovering underlying groups of features. In this work the CM is applied to isolated character image recognition, for which several set of features can be extracted from each sample. Experimentation has shown that the use of CM permits a significant improvement in accuracy in most cases, while the others remain the same. The results were obtained after experimenting with four well-known corpora, using evolved meta-classifiers with the k-Nearest Neighbor rule as a weak classifier and by applying statistical significance tests.

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Banks in the northern eurozone have capital ratios that are, on average, less than half of the capital ratios of banks in the eurozone’s periphery. The authors explain this by the fact that northern eurozone banks profit from the financial solidity of their governments and follow business strategies aimed at issuing too much subsidised debt. In doing so, they weaken their balance sheets and become more fragile – less able to withstand future shocks. Paradoxically, financially strong governments breed fragile banks. The opposite occurs in countries with financially weak governments. In these countries banks are forced to strengthen themselves because they are unable to rely on their governments. As a result they have significantly more capital and reserves than banks in the northern eurozone. Recommendations More than in the south, the governments of northern Europe should stand up and force the banks to issue more equity. This should go much further than what is foreseen in the Basel III accord. If the experience of the southern eurozone countries is any guide, banks in the north of the eurozone should at least double the capital and the reserves as a percentage of their balance sheets. Failure to do so risks destroying the financial solidity of the northern European governments when, in the future, negative shocks force these governments to come to the rescue of their undercapitalised banks. The new responsibilities entrusted to the European Central Bank as the single supervisor in the eurozone create a unique opportunity for that institution to change the regulatory and supervisory culture in the eurozone – one that has allowed the large banks to continue living dangerously, with insufficient capital.

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There are clear benefits to price stability. High inflation can distort corporate investment decisions and the consumption behaviour of households. Changes to inflation redistribute real wealth and income between different segments of society, such as savers and borrowers, or young and old. Price stability is therefore a fundamental public good and it became a fundamental principle of European Economic and Monetary Union. But the European Treaties do not define price stability. It was left to the Governing Council of the European Central Bank (ECB) to quantify it: "Price stability is defined as a year-on-year increase in the Harmonised Index of Consumer Prices (HICP) for the euro area of below 2%"[1]. The Governing Council has also clarified that it aims to maintain inflation below, but close to, two percent over the medium term, though it has not quantified what 'closeness' means, nor has it given a precise definition of the 'medium term'[2]. The clarification has been widely interpreted to mean that the actual target of the ECB is close to, but below, two percent inflation in the medium term.

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The political, military and economic parameters of German power influence the vision of the international order that Berlin favours. Politically, Germany is a regional power in the EU with considerable diplomatic potential. Economically, it is the world's third largest power with growing global trade and investment links. At the same time, Germany's military potential is limited and the German strategic culture makes the country sceptical about the use of military instruments. Berlin is thus essentially interested in maintaining peace and stability, both in Europe and globally, and in developing diplomatic mechanisms to manage regional and global crises and conflicts. The German preference for dialogue and compromise in conflict situations in the regional and global dimensions may increasingly pose a risk to maintaining the cohesion and credibility of NATO – both from the perspective of the USA and Germany’s allies from Central-Eastern and Northern Europe.

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Mode of access: Internet.

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Vita.

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"This report is based on research sponsored by the U. S. Navy through the Office of Naval Research, Contract Nonr-2653(00) [Task NR 061-106]"

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"NsG 24-59. Sponsored by National Aeronautics and Space Administration."

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The concept of biperfect (noncocommutative) weak Hopf algebras is introduced and their properties are discussed. A new type of quasi-bicrossed products is constructed by means of weak Hopf skew-pairs of the weak Hopf algebras which are generalizations of the Hopf pairs introduced by Takeuchi. As a special case, the quantum double of a finite dimensional biperfect (noncocommutative) weak Hopf algebra is built. Examples of quantum doubles from a Clifford monoid as well as a noncommutative and noncocommutative weak Hopf algebra are given, generalizing quantum doubles from a group and a noncommutative and noncocommutative Hopf algebra, respectively. Moreover, some characterizations of quantum doubles of finite dimensional biperfect weak Hopf algebras are obtained. (C) 2004 American Institute of Physics.