11,824 research outputs found

    Essence and Cause: Making Something Be What It Is

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    Aristotle frequently describes essence as a “cause” or “explanation”, thus ascribing to essence some sort of causal or explanatory role. This explanatory role is often explicated by scholars in terms of essence “making the thing be what it is” or “making it the very thing that it is”. I argue that this is problematic, at least on the assumption that “making” expresses an explanatory relation, since it violates certain formal features of explanation. I then consider whether Aristotle is vulnerable to this problem by examining the explanatory role of essence in Posterior Analytics and Metaphysics Z 17

    Bridging stylized facts in finance and data non-stationarities

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    Employing a recent technique which allows the representation of nonstationary data by means of a juxtaposition of locally stationary patches of different length, we introduce a comprehensive analysis of the key observables in a financial market: the trading volume and the price fluctuations. From the segmentation procedure we are able to introduce a quantitative description of a group of statistical features (stylizes facts) of the trading volume and price fluctuations, namely the tails of each distribution, the U-shaped profile of the volume in a trading session and the evolution of the trading volume autocorrelation function. The segmentation of the trading volume series provides evidence of slow evolution of the fluctuating parameters of each patch, pointing to the mixing scenario. Assuming that long-term features are the outcome of a statistical mixture of simple local forms, we test and compare different probability density functions to provide the long-term distribution of the trading volume, concluding that the log-normal gives the best agreement with the empirical distribution. Moreover, the segmentation of the magnitude price fluctuations are quite different from the results for the trading volume, indicating that changes in the statistics of price fluctuations occur at a faster scale than in the case of trading volume.Comment: 13 pages, 12 figure

    AIRPORT PRIVATIZATION MOVEMENT IN THE 21ST CENTURY

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    This paper examines airport privatization as a whole. Since airport privatization is so complex, this paper begins by laying out the fundamentals of airport privatization and the airport structure in the United States (U.S.). Understanding these crucial fundamentals will help readers comprehend how the supporters of this concept are attempting to revolutionize airports in the U.S. This paper entails an analysis of its corresponding literature, heavily relying on the Transportation Research Board (TRB) and the American Association of Airport Executives (AAAE) since they are two active organizations concerning this topic. This paper also used information from interviews with long-time airport manager, Gary Shafer, who previously wrote his MPA research paper on this same topic. The literature review consists of: the Federal Aviation Administration’s (FAA) Airport Privatization Pilot Program (APPP), the various airport examples of this concept being implemented in the U.S. and it finally distinguishes where airport privatization is more likely to occur and become a success. This paper will also analyze what the public sector has to gain and lose with airport privatization through a review of case studies and it will also reveal and relate the misconceptions regarding this concept. Proponents of airport privatization argue that this policy aids the public sector by allowing them to relinquish having to operate an airport and opponents of airport privatization believe that the public sector would be relinquishing of a public asset by privatizing its airport

    RedescripciĂłn y afinidades de Castianeira badia (Simon 1877) (Araneida, Clubionidae)

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    Weyl geometry, anti-De Sitter space, and Φ4\Phi^4-theory

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    We study the Gaussian approximation to the quantum fluctuations of the metric of the four dimensional anti-De Sitter spacetime. The associated massless scalar field has a quartic self interaction, for which we construct the generating functional of the nn-point correlation functions. The concomitant infrared divergence is cured by a mass renormalization provided by the cosmological constant, which is also responsible for the renormalization of the coupling constant of the field theory.Comment: 9 pages, 1 figur

    Fish, Marmelos Conservation Area (BX044), Madeira River basin, states of Amazonas and RondĂ´nia, Brazil.

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    The present study provides a species list of fish from the Marmelos River Area – BX044 in the states ofAmazonas and Rondônia in northern Brazil. During a Rapid Ecological Assessment (REA) performed in October andNovember of 2003, 133 fish species from six orders and 24 families were recorded. The most diverse families wereCharacidae (47 species), Cichlidae (15 species), Loricariidae (12 species) and Pimelodidae (7 species). 23 fish specieswere common to the entire river basin and 4 were endemic to the aquatic system studied
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