669 research outputs found

    Numerical analysis of moored ship motion considering harbor resonance in Pohang new harbor

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    This paper proposes a computational method for estimating moored ship motion taking into consideration harbor resonance, and provides a way to estimate the effect that harbor resonance has on moored ship motion. The computation of harbor resonance used the CGWAVE model, and the computation of moored ship motion used the three-dimensional Green???s function method. This method was verified with field motion measurement data from actual moored ships and wave field data and down time record data from Pohang New Harbor. The resonance periods obtained from wave field data in Pohang New Harbor were 80, 33, 23, and 8 min, which were the long waves, and 42, 54, and 60 s, which were the infra-gravity waves inside the harbor slip. The simulation results for harbor resonance were compared to the actual wave field data. This study investigated whether harbor resonance has an effect on moored ship motion using simulated results of ship motion both with and without harbor resonance included. In the case of harbor resonance included, moored ship motion increased by 10???30% when compared with the results without harbor resonance included. We found that harbor resonance has a greater effect on the surge and heave motion of a large-sized ship and on the roll and the yaw motion of a small-sized ship

    Does the Presence of Professional Football Cause Crime in a City? Evidence from Pontiac, Michigan

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    We empirically explore the relationship between the National Football League (NFL) and crime using daily panel data from Detroit. We exploit the natural experiment of the Detroit Lions movement from Pontiac MI to downtown Detroit in 2002 to examine the impact of NFL games on crime in a jurisdiction. Pontiac is used as a treatment city and other suburban cities are used as a comparison group. Employing a triple difference-in-difference approach, we find little to no change in crime on a home game day in Pontiac compared to other suburban cities. There is no difference in crime between the football season and off-season, among the groups, after the Lions moved. While not conclusive, our results are suggestive that professional football does not create additional crime except for larceny

    Quasiparticle Inelastic Lifetime from Paramagnons in Disordered Superconductors

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    The paramagnon contribution to the quasiparticle inelastic scattering rate in disordered superconductors is presented. Using Anderson's exact eigenstate formalism, it is shown that the scattering rate is Stoner enhanced and is further enhanced by the disorder relative to the clean case in a manner similar to the disorder enhancement of the long-range Coulomb contribution. The results are discussed in connection with the possibility of conventional or unconventional superconductivity in the borocarbides. The results are compared to recent tunneling experiments on LuNi2_{2}B2_{2}C.Comment: 5 pages, no figure

    The ADAMTS (A Disintegrin and Metalloproteinase with Thrombospondin motifs) family

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    The ADAMTS (A Disintegrin and Metalloproteinase with Thrombospondin motifs) enzymes are secreted, multi-domain matrix-associated zinc metalloendopeptidases that have diverse roles in tissue morphogenesis and patho-physiological remodeling, in inflammation and in vascular biology. The human family includes 19 members that can be sub-grouped on the basis of their known substrates, namely the aggrecanases or proteoglycanases (ADAMTS1, 4, 5, 8, 9, 15 and 20), the procollagen N-propeptidases (ADAMTS2, 3 and 14), the cartilage oligomeric matrix protein-cleaving enzymes (ADAMTS7 and 12), the von-Willebrand Factor proteinase (ADAMTS13) and a group of orphan enzymes (ADAMTS6, 10, 16, 17, 18 and 19). Control of the structure and function of the extracellular matrix (ECM) is a central theme of the biology of the ADAMTS, as exemplified by the actions of the procollagen-N-propeptidases in collagen fibril assembly and of the aggrecanases in the cleavage or modification of ECM proteoglycans. Defects in certain family members give rise to inherited genetic disorders, while the aberrant expression or function of others is associated with arthritis, cancer and cardiovascular disease. In particular, ADAMTS4 and 5 have emerged as therapeutic targets in arthritis. Multiple ADAMTSs from different sub-groupings exert either positive or negative effects on tumorigenesis and metastasis, with both metalloproteinase-dependent and -independent actions known to occur. The basic ADAMTS structure comprises a metalloproteinase catalytic domain and a carboxy-terminal ancillary domain, the latter determining substrate specificity and the localization of the protease and its interaction partners; ancillary domains probably also have independent biological functions. Focusing primarily on the aggrecanases and proteoglycanases, this review provides a perspective on the evolution of the ADAMTS family, their links with developmental and disease mechanisms, and key questions for the future

    Magnetic pair breaking in disordered superconducting films

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    A theory for the effects of nonmagnetic disorder on the magnetic pair breaking rate α\alpha induced by paramagnetic impurities in quasi two-dimensional superconductors is presented. Within the framework of a strong-coupling theory for disordered superconductors, we find that the disorder dependence of α\alpha is determined by the disorder enhancements of both the electron-phonon coupling and the spin-flip scattering rate. These two effects have a tendency to cancel each other. With parameter values appropriate for Pb_{0.9} Bi_{0.1}, we find a pair breaking rate that is very weakly dependent on disorder for sheet resistances 0 < R < 2.5 kOhm, in agreement with a recent experiment by Chervenak and Valles.Comment: 6 pp., REVTeX, epsf, 2 eps figs, final version as publishe

    An Inventory of Sports Economics Courses in the US

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    Sports economics is a young, growing field in the discipline of economics. An examination of course catalogs at 169 national liberal arts colleges and 254 national universities uncovered undergraduate sports economics classes offered at 17% of the liberal arts colleges and 29.5% of the universities. The characteristics of colleges and universities offering sports economics courses are analyzed. The state of the undergraduate curriculum in economics and barriers to the creation of new elective course offerings are also discussed

    Testing the predictability and efficiency of securitized real estate markets

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    This paper conducts tests of the random walk hypothesis and market efficiency for 14 national public real estate markets. Random walk properties of equity prices influence the return dynamics and determine the trading strategies of investors. To examine the stochastic properties of local real estate index returns and to test the hypothesis that public real estate stock prices follow a random walk, the single variance ratio tests of Lo and MacKinlay (1988) as well as the multiple variance ratio test of Chow and Denning (1993) are employed. Weak-form market efficiency is tested directly using non-parametric runs tests. Empirical evidence shows that weekly stock prices in major securitized real estate markets do not follow a random walk. The empirical findings of return predictability suggest that investors might be able to develop trading strategies allowing them to earn excess returns compared to a buy-and-hold strategy

    Shaping gold nanocomposites with tunable optical properties

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    We report the synthesis of morphological uniform composites using miniemulsions of poly(tert-butyl acrylate) or poly(styrene) containing organically capped gold nanocrystals (NCs). The optical features of such hybrid structures are dominated by plasmonic effects and depend critically on the morphology of the resulting nanocomposite. In particular, we demonstrate the ability to tune the overall optical response in the visible spectral region by varying the Au NCs arrangement within the polymer matrix, and therefore the interparticle plasmon coupling, using Au NCs resulting from the same batch of synthesis. This is a consequence of two well-known effects on the optical properties of Au particles: the variation of the surrounding dielectric refractive index and interparticle plasmonic coupling. The research reported here shows a general strategy to produce optical responsive nanocomposites via control of the morphology of submicrometric polymer particles containing metal nanocrystals and thus is an alternative to the more common strategy of size tuning metal nanoparticles used as nanofillers

    Facile formation of highly mobile supported lipid bilayers on surface-quaternized pH-responsive polymer brushes

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    Poly(2-dimethylamino)ethyl methacrylate) (PDMA) brushes are grown from planar substrates via surface atom transfer radical polymerization (ATRP). Quaternization of these brushes is conducted using 1-iodooctadecane in n-hexane, which is a non-solvent for PDMA. Ellipsometry, AFM, and water contact angle measurements show that surface-confined quaternization occurs under these conditions, producing pH-responsive brushes that have a hydrophobic upper surface. Systematic variation of the 1-iodooctadecane concentration and reaction time enables the mean degree of surface quaternization to be optimized. Relatively low degrees of surface quaternization (ca. 10 mol % as judged by XPS) produce brushes that enable the formation of supported lipid bilayers, with the hydrophobic pendent octadecyl groups promoting in situ rupture of lipid vesicles. Control experiments confirm that quaternized PDMA brushes prepared in a good brush solvent (THF) produce non-pH-responsive brushes, presumably because the pendent octadecyl groups form micelle-like physical cross-links throughout the brush layer. Supported lipid bilayers (SLBs) can also be formed on the non-quaternized PDMA precursor brushes, but such structures proved to be unstable to small changes in pH. Thus, surface quaternization of PDMA brushes using 1-iodooctadecane in n-hexane provides the best protocol for the formation of robust SLBs. Fluorescence recovery after photobleaching (FRAP) studies of such SLBs indicate diffusion coefficients (2.8 ± 0.3 μm s–1) and mobile fractions (98 ± 2%) that are comparable to the literature data reported for SLBs prepared directly on planar glass substrates
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