47 research outputs found

    Scale-free static and dynamical correlations in melts of monodisperse and Flory-distributed homopolymers: A review of recent bond-fluctuation model studies

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    It has been assumed until very recently that all long-range correlations are screened in three-dimensional melts of linear homopolymers on distances beyond the correlation length ξ\xi characterizing the decay of the density fluctuations. Summarizing simulation results obtained by means of a variant of the bond-fluctuation model with finite monomer excluded volume interactions and topology violating local and global Monte Carlo moves, we show that due to an interplay of the chain connectivity and the incompressibility constraint, both static and dynamical correlations arise on distances r≫ξr \gg \xi. These correlations are scale-free and, surprisingly, do not depend explicitly on the compressibility of the solution. Both monodisperse and (essentially) Flory-distributed equilibrium polymers are considered.Comment: 60 pages, 49 figure

    Pittosporum ridleyi (Pittosporaceae), a new name for the ‘rusty-leaved’ pittosporum in Malaysia

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    The poorly understood ‘rusty-leaved’ pittosporum, Pittosporum ferrugineum W.T.Aiton has been comprehensively revised as part of the ongoing revision of the family Pittosporaceae across its range. Aiton’s Pittosporum ferrugineum s.s. has been found to be a different species to the species currently known as P. ferrugineum in the Malay Peninsula, Borneo and the Andaman Islands (India). Hence the common coastal species in these areas needs a new name and is presented here as Pittosporum ridleyi L.Cayzer & G.Chandler, a new name for an old species

    Assessing Photoinduced Toxicity of Polycyclic Aromatic Hydrocarbons in an Urbanized Estuary

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    Increases in contaminants associated with urban sprawl are a particular concern in the rapidly developing coastal areas of the southeastern United States. Polycyclic aromatic hydrocarbons (PAHs) are contaminants associated with vehicle emissions and runoff from impervious surfaces. Increased vehicular traffic and more impervious surfaces lead to an increased loading of PAHs into coastal estuarine systems. The phototoxic effect of PAH-contaminated sediments on a sediment-dwelling meiobenthic copepod, Amphiascus tenuiremis, was estimated in Murrells Inlet, a small, high-salinity estuary with moderate urbanization located in Georgetown and Horry Counties, South Carolina, USA. Field-determined solar ultraviolet radiation (UV) and UV extinction coefficients were incorporated into laboratory toxicity experiments, and a model was developed to predict areas of specific hazard to A. tenuiremis in the estuary. The model incorporated laboratory toxicity data, UV extinction coefficients, and historical sediment chemistry and bathymetric data within a spatial model of sedimentary areas of the estuary. The model predicted that approximately 8-16% of the total creek habitat suitable for meiobenthic copepods is at risk to photoinduced PAH toxicity. This area is in the northern, more developed part of Murrells Inlet

    Recent advances in understanding Apiales and a revised classification

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    Despite the long history of recognising the angiosperm order Apiales as a natural alliance, the circumscription of the order and the relationships among its constituent groups have been troublesome. Recent studies, however, have made great progress in understanding phylo- genetic relationships in Apiales. Although much of this recent work has been based on molecular data, the results are congruent with other sources of data, including morphology and geography. A unified picture of relationships has now emerged regarding the delimitation of Apiales, which includes a core group of four families (Apiaceae, Araliaceae, Myodocarpaceae, Pittosporaceae) to which three small families are also added (Griseliniaceae, Torricelliaceae and Pennantiaceae). After a brief review of recent advances in each of the major groups, a revised classification of the order is presented, which includes the recognition of the new suborder Apiineae (comprising the four core families) and two new subfamilies within Apiaceae (Azorelloideae and Mackinlayoideae)

    Entrepreneurial orientation and firm performance: The unique impact of innovativeness, proactiveness, and risk-taking

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    This paper develops a theoretical model of the relationship between firm-level entrepreneurship and firm performance. This model is intended to further clarify the consequences of an ‘entrepreneurial orientation,’ paying particular attention to the differential relationship that exists between the three sub-dimensions of entrepreneurial orientation and firm performance. Included in the theoretical model are other important variables (such as organizational structure and environmental characteristics) that may impact the EO-performance relationship. Propositions are developed regarding the various configurations of the sub-dimensions of EO and organizational structure that would be most appropriate in a given environmental context. Future research may also benefit from considering the important role that organizational strategy and life cycle stage play in this model. The implications of this model for both researchers and managers are discussed.Journal Articl
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