3,851 research outputs found

    Does Internet access to official data display any regularity: case of the Electronic Data Delivery System of the Central Bank of Turkey

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    1990s were the years of enormous growth of information exchange. Rapid development, augmented coverage and wide accessibility of Internet have been the key factors of that amazing growth. People’s access to economic and financial data was one of the major areas in which new trends and patterns of usage were observed. Owing to the elevated importance of financial information in today’s sophisticated markets, it is hypothesized that the linkage between data access patterns and economic events should display some regularity. In addition, one should be able to explain part of the irregularities. This study examines the access statistics of the Central Bank of Turkey’s Electronic Data Delivery System on these grounds. Using OLS and EGARCH models, significant evidence was obtained for the existence of regularities (i.e. calendar effects) in the data.Data access; Macroeconomic data; Return to information; Economics of information

    A state variable for crumpled thin sheets

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    Despite the apparent ease with which a sheet of paper is crumpled and tossed away, crumpling dynamics are often considered a paradigm of complexity. This complexity arises from the infinite number of configurations a disordered crumpled sheet can take. Here we experimentally show that key aspects of crumpling have a very simple description; the evolution of the damage in crumpling dynamics can largely be described by a single global quantity, the total length of all creases. We follow the evolution of the damage network in repetitively crumpled elastoplastic sheets, and show that the dynamics of this quantity are deterministic, and depend only on the instantaneous state of the crease network and not at all on the crumpling history. We also show that this global quantity captures the crumpling dynamics of a sheet crumpled for the first time. This leads to a remarkable reduction in complexity, allowing a description of a highly disordered system by a single state parameter. Similar strategies may also be useful in analyzing other systems that evolve under geometric and mechanical constraints, from faulting of tectonic plates to the evolution of proteins

    Epicyclic oscillations of fluid bodies Paper II. Strong gravity

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    Fluids in external gravity may oscillate with frequencies characteristic of the epicyclic motions of test particles. We explicitly demonstrate that global oscillations of a slender, perfect fluid torus around a Kerr black hole admit incompressible vertical and radial epicyclic modes. Our results may be directly relevant to one of the most puzzling astrophysical phenomena -- high (hundreds of hertz) frequency quasiperiodic oscillations (QPOs) detected in X-ray fluxes from several black hole sources. Such QPOs are pairs of stable frequencies in the 3/2 ratio. It seems that they originate a few gravitational radii away from the black hole and thus observations of them have the potential to become an accurate probe of super-strong gravity.Comment: submitted to Classical and Quantum Gravit

    Sustainable Development and Environmentally Friendly Energy Systems

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    People are relying upon oil for primary energy and this will continue for a few more decades. Other conventional sources may be more enduring but are not without serious disadvantages. The renewable energy resources are particularly suited for the provision of rural power supplies and a major advantage is that equipment such as flat plate solar driers, wind machines, etc., can be constructed using local resources. Without the advantage results from the feasibility of local maintenance and the general encouragement, such local manufacture gives to the buildup of a small-scale rural-based industry. This communication comprises a comprehensive review of energy sources, the environment, and sustainable development. It includes the renewable energy technologies, energy efficiency systems, energy conservation scenarios, energy savings in greenhouses environment and other mitigation measures necessary to reduce climate change. This study gives some examples of small-scale energy converters, nevertheless, it should be noted that small conventional, i.e., engines are currently the major source of power in rural areas and will continue to be so for a long time to come

    Promotion and Implementation of Bioenergy for a Better Environment

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    - There is strong scientific evidence that the average temperature of the earth's surface is rising and this may be attribute to increased concentration of carbon dioxide (CO2), and other greenhouse gases (GHGs) in the atmosphere as released by burning fossil fuels. One of the chief sources of greenhouse gases is burning of fossil fuels. Biogas from biomass appears to have potential as an alternative energy source, which is potentially rich in biomass resources. In the present paper, current literature is reviewed regarding the ecological, social, cultural and economic impacts of biogas technology. In this article an attempt has been made to give an overview of present and future use of biomass as an industrial feedstock for production of fuels, chemicals and other materials. However, to be truly competitive in an open market situation, higher value products are required
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