3,369 research outputs found

    Cross-correlations between volume change and price change

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    In finance, one usually deals not with prices but with growth rates RR, defined as the difference in logarithm between two consecutive prices. Here we consider not the trading volume, but rather the volume growth rate R~\tilde R, the difference in logarithm between two consecutive values of trading volume. To this end, we use several methods to analyze the properties of volume changes R~|\tilde R|, and their relationship to price changes R|R|. We analyze 14,98114,981 daily recordings of the S\&P 500 index over the 59-year period 1950--2009, and find power-law {\it cross-correlations\/} between R|R| and R~|\tilde R| using detrended cross-correlation analysis (DCCA). We introduce a joint stochastic process that models these cross-correlations. Motivated by the relationship between R| R| and R~|\tilde R|, we estimate the tail exponent α~{\tilde\alpha} of the probability density function P(R~)R~1α~P(|\tilde R|) \sim |\tilde R|^{-1 -\tilde\alpha} for both the S\&P 500 index as well as the collection of 1819 constituents of the New York Stock Exchange Composite index on 17 July 2009. As a new method to estimate α~\tilde\alpha, we calculate the time intervals τq\tau_q between events where R~>q\tilde R>q. We demonstrate that τˉq\bar\tau_q, the average of τq\tau_q, obeys τˉqqα~\bar \tau_q \sim q^{\tilde\alpha}. We find α~3\tilde \alpha \approx 3. Furthermore, by aggregating all τq\tau_q values of 28 global financial indices, we also observe an approximate inverse cubic law.Comment: 7 pages, 5 figure

    Retraction: Inactivation of MAP kinase signalling in Myc Transformed Cells and Rescue by LiCl inhibition of GSK3

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    The corresponding author submitted this article [1] to Molecular Cancer on the assumption that the co-author had agreed to the submission. Since this is not the case, the authors are retracting the article. The corresponding author is deeply sorry for any inconvenience this may have caused to the editorial and publishing staff. An apology is also extended to the readers

    Optimization Of Detergent-Mediated Reconstitution Of Influenza A M2 Protein Into Proteoliposomes

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    We report the optimization of detergent-mediated reconstitution of an integral membrane-bound protein, full-length influenza M2 protein, by direct insertion into detergent-saturated liposomes. Detergent-mediated reconstitution is an important method for preparing proteoliposomes for studying membrane proteins, and must be optimized for each combination of protein and membrane constituents used. The purpose of the reconstitution was to prepare samples for site-directed spin-labeling electron paramagnetic resonance (SDSL-EPR) studies. Our goals in optimizing the protocol were to minimize the amount of detergent used, reduce overall proteoliposome preparation time, and confirm the removal of all detergent. The liposomes were comprised of (1-palmitoyl-2-oleyl-sn-glycero-phosphocholine (POPC) and 1-palmitoyl-2-oleyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG), and the detergent octylglucoside (OG) was used for reconstitution. Rigorous physical characterization was applied to optimize each step of the reconstitution process. We used dynamic light scattering (DLS) to determine the amount of OG needed to saturate the preformed liposomes. During detergent removal by absorption with Bio-Beads, we quantified the detergent concentration by means of a colorimetric assay, thereby determining the number of Bio-Bead additions needed to remove all detergent from the final proteoliposomes. We found that the overnight Bio-Bead incubation used in previously published protocols can be omitted, reducing the time needed for reconstitution. We also monitored the size distribution of the proteoliposomes with DLS, confirming that the size distribution remains essentially constant throughout the reconstitution process

    Evolution of Preprofessional Pharmacy Curricula

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    Objectives. To examine changes in preprofessional pharmacy curricular requirements and trends, and determine rationales for and implications of modifications. Methods. Prerequisite curricular requirements compiled between 2006 and 2011 from all doctor of pharmacy (PharmD) programs approved by the Accreditation Council of Pharmacy Education were reviewed to ascertain trends over the past 5 years. An online survey was conducted of 20 programs that required either 3 years of prerequisite courses or a bachelor’s degree, and a random sample of 20 programs that required 2 years of prerequisites. Standardized telephone interviews were then conducted with representatives of 9 programs. Results. In 2006, 4 programs required 3 years of prerequisite courses and none required a bachelor’s degree; by 2011, these increased to 18 programs and 7 programs, respectively. Of 40 programs surveyed, responses were received from 28 (70%), 9 (32%) of which reported having increased the number of prerequisite courses since 2006. Reasons given for changes included desire to raise the level of academic achievement of students entering the PharmD program, desire to increase incoming student maturity, and desire to add clinical sciences and experiential coursework to the pharmacy curriculum. Some colleges and schools experienced a temporary decrease in applicants. Conclusions. The preprofessional curriculum continues to evolve, with many programs increasing the number of course prerequisites. The implications of increasing prerequisites were variable and included a perceived increase in maturity and quality of applicants and, for some schools, a temporary decrease in the number of applicants

    Role of Vitamin A in Retinal Diseases

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    Vitamin A has an essential role in vision in that it forms the photosensitive pigments that absorb light and initiate the visual process. However, vitamin A and its analogues also have critical roles in maintaining the structural integrity of the retina. Disruption of the metabolism of vitamin A results in several blinding diseases. This review focuses on our recent studies on the role of a protein critical to the processing of vitamin A, RPE65. The absence or dysfunction of this protein causes the childhood blinding disease Leber congenital amaurosis

    Molecular Marker-Assisted Breeding

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    The potential value of genetic markers, linkage maps and indirect selection in plant breeding has been known for over 80 years. However, it was not until the development of DNA marker technology in the 1980s, that a large enough number of environmentally insensitive genetic markers could be generated to adequately tag a range of important agronomic traits. Since this time DNA marker technology has promised to dramatically enhance the efficiency of plant breeding as molecular biology has already revolutionized research in the life sciences. Yet it is only now as we enter the new millennium that advances in automated technology present the convenience, speed and level of throughput that can finally offer relevance to modern plant breeding pro grams. The theoretical basis for molecular marker-assisted breeding is well established but still rapidly evolving with a wide array of published examples covering most crops of major economic importance. Meanwhile, dramatic advances are being made in applied genomics, which will undoubtedly fuel the development of Knowledge-led breeding schemes. However, beyond these scientific developments there is a particular paucity of studies addressing the practical and economic benefits of molecular breeding

    The New Political Economy of EU State Aid Policy

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    Despite its importance and singularity, the EU’s state aid policy has attracted less scholarly attention than other elements of EU competition policy. Introducing the themes addressed by the special issue, this article briefly reviews the development of EU policy and highlights why the control of state aid matters. The Commission’s response to the current economic crisis notably in banking and the car industry is a key concern, but the interests of the special issue go far beyond. They include: the role of the European Commission in the development of EU policy, the politics of state aid, and a clash between models of capitalism. The special issue also examines the impact of EU policy. It investigates how EU state aid decisions affect not only industrial policy at the national level (and therefore at the EU level), but the welfare state and territorial relations within federal member states, the external implications of EU action and the strategies pursued by the Commission to limit any potential disadvantage to European firms, and the conflict between the EU’s expanding legal order and national
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