160 research outputs found

    Optimal execution for portfolio transactions

    Get PDF
    Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, February 2007.Includes bibliographical references.In my thesis I explore the problem of optimizing trading strategies for complex portfolio transitions. Institutional investors run into this issue during periodic portfolio rebalancing or transition between asset managers. The costs of rebalancing can be broadly broken into trading costs (both the transaction cost and the market impact) and the opportunity costs of delaying the execution and bearing the risk of current-to-target portfolio divergence. This thesis proposes a methodology for measuring the opportunity cost as well as a strategy that minimizes the proposed measure through optimal portfolio transition execution. The benefits from the proposed trading strategy are benchmarked against the industry standard portfolio trading practices.by Alexander Fadeev.S.M

    Capillary-Wave Model for the Solidification of Dilute Binary Alloys

    Full text link
    Starting from a phase-field description of the isothermal solidification of a dilute binary alloy, we establish a model where capillary waves of the solidification front interact with the diffusive concentration field of the solute. The model does not rely on the sharp-interface assumption, and includes non-equilibrium effects, relevant in the rapid-growth regime. In many applications it can be evaluated analytically, culminating in the appearance of an instability which, interfering with the Mullins-Sekerka instability, is similar to that, found by Cahn in grain-boundary motion.Comment: 17 pages, 12 figure

    In vitro synthesis of uniform poly(dG)–poly(dC) by Klenow exo(−) fragment of polymerase I

    Get PDF
    In this paper, we describe a production procedure of the one-to-one double helical complex of poly(dG)–poly(dC), characterized by a well-defined length (up to 10 kb) and narrow size distribution of molecules. Direct evidence of strands slippage during poly(dG)–poly(dC) synthesis by Klenow exo(−) fragment of polymerase I is obtained by fluorescence resonance energy transfer (FRET). We show that the polymer extension results in an increase in the separation distance between fluorescent dyes attached to 5â€Č ends of the strands in time and, as a result, losing communication between the dyes via FRET. Analysis of the products of the early steps of the synthesis by high-performance liquid chromatography and mass spectroscopy suggest that only one nucleotide is added to each of the strand composing poly(dG)–poly(dC) in the elementary step of the polymer extension. We show that proper pairing of a base at the 3â€Č end of the primer strand with a base in sequence of the template strand is required for initiation of the synthesis. If the 3â€Č end nucleotide in either poly(dG) or poly(dC) strand is substituted for A, the polymer does not grow. Introduction of the T-nucleotide into the complementary strand to permit pairing with A-nucleotide results in the restoration of the synthesis. The data reported here correspond with a slippage model of replication, which includes the formation of loops on the 3â€Č ends of both strands composing poly(dG)–poly(dC) and their migration over long-molecular distances (ÎŒm) to 5â€Č ends of the strands

    Strategies for Large Oil and Gas Companies Operating to Support Sustainable Development and Environmental Safety in the Russian Arctic

    Get PDF
    IAs conventional oil and gas sources become less productive, unconventional hydrocarbon sources become more attractive due to new technologies and become the target of expanded exploration. Oil and gas development in the Arctic is challenging but promising, the largest reserves of Oil and Gas in the Arctic are on the Arctic Shelf in Russia. Most Arctic communities, especially indigenous communities, depend on fishing, hunting, and gathering, this requires the preservation of environmental health. In this article we tried to delineate a strategy for large oil and gas companies to diversify risk by proposing a form of social entrepreneurship that works for environmentally vulnerable regions with low infrastructure or skilled labor. With this framework, large oil and gas companies could effectively and reliably support smaller-scale enterprises preserving environmental health and creating an innovative business ecosystem that promotes a Arctic. Our model could also lead to local and indigenous entrepreneurship and a more equitable distribution of wealth in the Arctic

    assessment of blood capillaries and structural proteins localization

    Get PDF
    The papillary dermis of human skin is responsible for its biomechanical properties and for supply of epidermis with chemicals. Dermis is mainly composed of structural protein molecules, including collagen and elastin, and contains blood capillaries. Connective tissue diseases, as well as cardiovascular complications have manifestations on the molecular level in the papillary dermis (e.g. alteration of collagen I and III content) and in the capillary structure. In this paper we assessed the molecular structure of internal and external regions of skin capillaries using two-photon fluorescence lifetime imaging (FLIM) of endogenous compounds. It was shown that the capillaries are characterized by a fast fluorescence decay, which is originated from red blood cells and blood plasma. Using the second harmonic generation signal, FLIM segmentation was performed, which provided for spatial localization and fluorescence decay parameters distribution of collagen I and elastin in the dermal papillae. It was demonstrated that the lifetime distribution was different for the inner area of dermal papillae around the capillary loop that was suggested to be due to collagen III. Hence, we propose a generalized approach to two-photon imaging of the papillary dermis components, which extends the capabilities of this technique in skin diagnosis

    Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

    Get PDF
    We show the distribution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three genomic nomenclature systems to all sequence data from the World Health Organization European Region available until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation, compare the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2
    • 

    corecore