24,682 research outputs found

    Democracy Versus the National Security State

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    A South African perspective on global imbalances

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    Financial inflows into South African financial markets have resumed in 2009 and gained momentum in 2010, largely as a result of low interest rates and an oversupply of liquidity in advanced economies. As an emerging-market country with a current-account defi cit, South Africa is to some extent reliant on these inflows to fund its own external imbalance. However, fi nancial infl ows have exerted significant upward pressure on the exchange rate of the rand, with negative effects on the exporting sectors of the economy. Prices of South African bonds and equities have also increased significantly, raising possible concerns about their sustainability and possible sudden reversals. There are, however, also characteristics of the South African economy and financial system that improves its resilience to shocks and the side-effects of global imbalances. To date, South Africa has not implemented direct measures to stem capital controls, for various reasons. Its policy reactions to global imbalances comprised mainly countercyclical monetary and fiscal policy, a further accumulation of foreign exchange reserves to moderate the exchange rate appreciation and further relaxations of controls on capital outflows.

    Derivatives of Entropy Rate in Special Families of Hidden Markov Chains

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    Consider a hidden Markov chain obtained as the observation process of an ordinary Markov chain corrupted by noise. Zuk, et. al. [13], [14] showed how, in principle, one can explicitly compute the derivatives of the entropy rate of at extreme values of the noise. Namely, they showed that the derivatives of standard upper approximations to the entropy rate actually stabilize at an explicit finite time. We generalize this result to a natural class of hidden Markov chains called ``Black Holes.'' We also discuss in depth special cases of binary Markov chains observed in binary symmetric noise, and give an abstract formula for the first derivative in terms of a measure on the simplex due to Blackwell.Comment: The relaxed condtions for entropy rate and examples are taken out (to be part of another paper). The section about general principle and an example to determine the domain of analyticity is taken out (to be part of another paper). A section about binary Markov chains corrupted by binary symmetric noise is adde

    Rethinking one`s own culture

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    African people reflecting on their own situation will frequently find themselves in a dilemma to identify with western and traditional values. A case study of the Burji (Ethiopia and Kenya) examplifies this. First a description is given of the Burji actively dealing with their problems, trying among other things to keep Burjiness alive. Then in presenting a semiotic model it is shown how the phenomenon of their changing group identity (which is not grasped by theories of ethnic group or ethnicity) can be analyzed. The model presented may be useful for analyzing similar cases in the Third World

    Flat-plate heat pipe

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    Flat plate (vapor chamber) heat pipes were made by enclosing metal wicking between two capillary grooved flat panels. These heat pipes provide a unique configuration and have good capacity and conductance capabilities in zero gravity. When these flat plate vapor chamber heat pipes are heated or cooled, the surfaces are essentially isothermal, varying only 3 to 5 C over the panel surface

    Regulation of tissue crosstalk by skeletal muscle-derived myonectin and other myokines.

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    The integrated control of animal physiology requires intimate tissue crosstalk, a vital task mediated by circulating humoral factors. As one type of these factors, adipose tissue-derived adipokines have recently garnered attention as important regulators of systemic insulin sensitivity and metabolic homeostasis. However, the realization that skeletal muscle also secretes a variety of biologically and metabolically active polypeptide factors (collectively called myokines) has provided a new conceptual framework to understand the critical role skeletal muscle plays in coordinating whole-body energy balance. Here, we highlight recent progress made in the myokine field and discuss possible roles of myonectin, which we have recently identified as a potential postprandial signal derived from skeletal muscle to integrate metabolic processes in other tissues, such as adipose and liver; one of its roles is to promote fatty acid uptake into cells. Myonectin is also likely an important mediator in inter-tissue crosstalk

    Equivalence of Statistical Mechanical Ensembles for Non-Critical Quantum Systems

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    We consider the problem of whether the canonical and microcanonical ensembles are locally equivalent for short-ranged quantum Hamiltonians of NN spins arranged on a dd-dimensional lattices. For any temperature for which the system has a finite correlation length, we prove that the canonical and microcanonical state are approximately equal on regions containing up to O(N1/(d+1))O(N^{1/(d+1)}) spins. The proof rests on a variant of the Berry--Esseen theorem for quantum lattice systems and ideas from quantum information theory

    Entanglement area law from specific heat capacity

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    We study the scaling of entanglement in low-energy states of quantum many-body models on lattices of arbitrary dimensions. We allow for unbounded Hamiltonians such that systems with bosonic degrees of freedom are included. We show that if at low enough temperatures the specific heat capacity of the model decays exponentially with inverse temperature, the entanglement in every low-energy state satisfies an area law (with a logarithmic correction). This behaviour of the heat capacity is typically observed in gapped systems. Assuming merely that the low-temperature specific heat decays polynomially with temperature, we find a subvolume scaling of entanglement. Our results give experimentally verifiable conditions for area laws, show that they are a generic property of low-energy states of matter, and, to the best of our knowledge, constitute the first proof of an area law for unbounded Hamiltonians beyond those that are integrable.Comment: v3 now featuring bosonic system
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